// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
* Copyright (c) 2016 Facebook
* Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
*/
#include <uapi/linux/btf.h>
#include <linux/bpf-cgroup.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/bpf_verifier.h>
#include <linux/filter.h>
#include <net/netlink.h>
#include <linux/file.h>
#include <linux/vmalloc.h>
#include <linux/stringify.h>
#include <linux/bsearch.h>
#include <linux/sort.h>
#include <linux/perf_event.h>
#include <linux/ctype.h>
#include <linux/error-injection.h>
#include <linux/bpf_lsm.h>
#include <linux/btf_ids.h>
#include <linux/poison.h>
#include <linux/module.h>
#include <linux/cpumask.h>
#include <linux/bpf_mem_alloc.h>
#include <net/xdp.h>
#include <linux/trace_events.h>
#include <linux/kallsyms.h>
#include "disasm.h"
static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
[_id] = & _name ## _verifier_ops,
#define BPF_MAP_TYPE(_id, _ops)
#define BPF_LINK_TYPE(_id, _name)
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
#undef BPF_MAP_TYPE
#undef BPF_LINK_TYPE
};
struct bpf_mem_alloc bpf_global_percpu_ma;
static bool bpf_global_percpu_ma_set;
/* bpf_check() is a static code analyzer that walks eBPF program
* instruction by instruction and updates register/stack state.
* All paths of conditional branches are analyzed until 'bpf_exit' insn.
*
* The first pass is depth-first-search to check that the program is a DAG.
* It rejects the following programs:
* - larger than BPF_MAXINSNS insns
* - if loop is present (detected via back-edge)
* - unreachable insns exist (shouldn't be a forest. program = one function)
* - out of bounds or malformed jumps
* The second pass is all possible path descent from the 1st insn.
* Since it's analyzing all paths through the program, the length of the
* analysis is limited to 64k insn, which may be hit even if total number of
* insn is less then 4K, but there are too many branches that change stack/regs.
* Number of 'branches to be analyzed' is limited to 1k
*
* On entry to each instruction, each register has a type, and the instruction
* changes the types of the registers depending on instruction semantics.
* If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
* copied to R1.
*
* All registers are 64-bit.
* R0 - return register
* R1-R5 argument passing registers
* R6-R9 callee saved registers
* R10 - frame pointer read-only
*
* At the start of BPF program the register R1 contains a pointer to bpf_context
* and has type PTR_TO_CTX.
*
* Verifier tracks arithmetic operations on pointers in case:
* BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
* BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
* 1st insn copies R10 (which has FRAME_PTR) type into R1
* and 2nd arithmetic instruction is pattern matched to recognize
* that it wants to construct a pointer to some element within stack.
* So after 2nd insn, the register R1 has type PTR_TO_STACK
* (and -20 constant is saved for further stack bounds checking).
* Meaning that this reg is a pointer to stack plus known immediate constant.
*
* Most of the time the registers have SCALAR_VALUE type, which
* means the register has some value, but it's not a valid pointer.
* (like pointer plus pointer becomes SCALAR_VALUE type)
*
* When verifier sees load or store instructions the type of base register
* can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK, PTR_TO_SOCKET. These are
* four pointer types recognized by check_mem_access() function.
*
* PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
* and the range of [ptr, ptr + map's value_size) is accessible.
*
* registers used to pass values to function calls are checked against
* function argument constraints.
*
* ARG_PTR_TO_MAP_KEY is one of such argument constraints.
* It means that the register type passed to this function must be
* PTR_TO_STACK and it will be used inside the function as
* 'pointer to map element key'
*
* For example the argument constraints for bpf_map_lookup_elem():
* .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
* .arg1_type = ARG_CONST_MAP_PTR,
* .arg2_type = ARG_PTR_TO_MAP_KEY,
*
* ret_type says that this function returns 'pointer to map elem value or null'
* function expects 1st argument to be a const pointer to 'struct bpf_map' and
* 2nd argument should be a pointer to stack, which will be used inside
* the helper function as a pointer to map element key.
*
* On the kernel side the helper function looks like:
* u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
* {
* struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
* void *key = (void *) (unsigned long) r2;
* void *value;
*
* here kernel can access 'key' and 'map' pointers safely, knowing that
* [key, key + map->key_size) bytes are valid and were initialized on
* the stack of eBPF program.
* }
*
* Corresponding eBPF program may look like:
* BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR
* BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
* BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP
* BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
* here verifier looks at prototype of map_lookup_elem() and sees:
* .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
* Now verifier knows that this map has key of R1->map_ptr->key_size bytes
*
* Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
* Now verifier checks that [R2, R2 + map's key_size) are within stack limits
* and were initialized prior to this call.
* If it's ok, then verifier allows this BPF_CALL insn and looks at
* .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
* R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
* returns either pointer to map value or NULL.
*
* When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
* insn, the register holding that pointer in the true branch changes state to
* PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
* branch. See check_cond_jmp_op().
*
* After the call R0 is set to return type of the function and registers R1-R5
* are set to NOT_INIT to indicate that they are no longer readable.
*
* The following reference types represent a potential reference to a kernel
* resource which, after first being allocated, must be checked and freed by
* the BPF program:
* - PTR_TO_SOCKET_OR_NULL, PTR_TO_SOCKET
*
* When the verifier sees a helper call return a reference type, it allocates a
* pointer id for the reference and stores it in the current function state.
* Similar to the way that PTR_TO_MAP_VALUE_OR_NULL is converted into
* PTR_TO_MAP_VALUE, PTR_TO_SOCKET_OR_NULL becomes PTR_TO_SOCKET when the type
* passes through a NULL-check conditional. For the branch wherein the state is
* changed to CONST_IMM, the verifier releases the reference.
*
* For each helper function that allocates a reference, such as
* bpf_sk_lookup_tcp(), there is a corresponding release function, such as
* bpf_sk_release(). When a reference type passes into the release function,
* the verifier also releases the reference. If any unchecked or unreleased
* reference remains at the end of the program, the verifier rejects it.
*/
/* verifier_state + insn_idx are pushed to stack when branch is encountered */
struct bpf_verifier_stack_elem {
/* verifier state is 'st'
* before processing instruction 'insn_idx'
* and after processing instruction 'prev_insn_idx'
*/
struct bpf_verifier_state st;
int insn_idx;
int prev_insn_idx;
struct bpf_verifier_stack_elem *next;
/* length of verifier log at the time this state was pushed on stack */
u32 log_pos;
};
#define BPF_COMPLEXITY_LIMIT_JMP_SEQ 8192
#define BPF_COMPLEXITY_LIMIT_STATES 64
#define BPF_MAP_KEY_POISON (1ULL << 63)
#define BPF_MAP_KEY_SEEN (1ULL << 62)
#define BPF_GLOBAL_PERCPU_MA_MAX_SIZE 512
static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx);
static int release_reference(struct bpf_verifier_env *env, int ref_obj_id);
static void invalidate_non_owning_refs(struct bpf_verifier_env *env);
static bool in_rbtree_lock_required_cb(struct bpf_verifier_env *env);
static int ref_set_non_owning(struct bpf_verifier_env *env,
struct bpf_reg_state *reg);
static void specialize_kfunc(struct bpf_verifier_env *env,
u32 func_id, u16 offset, unsigned long *addr);
static bool is_trusted_reg(const struct bpf_reg_state *reg);
static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux)
{
return aux->map_ptr_state.poison;
}
static bool bpf_map_ptr_unpriv(const struct bpf_insn_aux_data *aux)
{
return aux->map_ptr_state.unpriv;
}
static void bpf_map_ptr_store(struct bpf_insn_aux_data *aux,
struct bpf_map *map,
bool unpriv, bool poison)
{
unpriv |= bpf_map_ptr_unpriv(aux);
aux->map_ptr_state.unpriv = unpriv;
aux->map_ptr_state.poison = poison;
aux->map_ptr_state.map_ptr = map;
}
static bool bpf_map_key_poisoned(const struct bpf_insn_aux_data *aux)
{
return aux->map_key_state & BPF_MAP_KEY_POISON;
}
static bool bpf_map_key_unseen(const struct bpf_insn_aux_data *aux)
{
return !(aux->map_key_state & BPF_MAP_KEY_SEEN);
}
static u64 bpf_map_key_immediate(const struct bpf_insn_aux_data *aux)
{
return aux->map_key_state & ~(BPF_MAP_KEY_SEEN | BPF_MAP_KEY_POISON);
}
static void bpf_map_key_store(struct bpf_insn_aux_data *aux, u64 state)
{
bool poisoned = bpf_map_key_poisoned(aux);
aux->map_key_state = state | BPF_MAP_KEY_SEEN |
(poisoned ? BPF_MAP_KEY_POISON : 0ULL);
}
static bool bpf_helper_call(const struct bpf_insn *insn)
{
return insn->code == (BPF_JMP | BPF_CALL) &&
insn->src_reg == 0;
}
static bool bpf_pseudo_call(const struct bpf_insn *insn)
{
return insn->code == (BPF_JMP | BPF_CALL) &&
insn->src_reg == BPF_PSEUDO_CALL;
}
static bool bpf_pseudo_kfunc_call(const struct bpf_insn *insn)
{
return insn->code == (BPF_JMP | BPF_CALL) &&
insn->src_reg == BPF_PSEUDO_KFUNC_CALL;
}
struct bpf_call_arg_meta {
struct bpf_map *map_ptr;
bool raw_mode;
bool pkt_access;
u8 release_regno;
int regno;
int access_size;
int mem_size;
u64 msize_max_value;
int ref_obj_id;
int dynptr_id;
int map_uid;
int func_id;
struct btf *btf;
u32 btf_id;
struct btf *ret_btf;
u32 ret_btf_id;
u32 subprogno;
struct btf_field *kptr_field;
};
struct bpf_kfunc_call_arg_meta {
/* In parameters */
struct btf *btf;
u32 func_id;
u32 kfunc_flags;
const struct btf_type *func_proto;
const char *func_name;
/* Out parameters */
u32 ref_obj_id;
u8 release_regno;
bool r0_rdonly;
u32 ret_btf_id;
u64 r0_size;
u32 subprogno;
struct {
u64 value;
bool found;
} arg_constant;
/* arg_{btf,btf_id,owning_ref} are used by kfunc-specific handling,
* generally to pass info about user-defined local kptr types to later
* verification logic
* bpf_obj_drop/bpf_percpu_obj_drop
* Record the local kptr type to be drop'd
* bpf_refcount_acquire (via KF_ARG_PTR_TO_REFCOUNTED_KPTR arg type)
* Record the local kptr type to be refcount_incr'd and use
* arg_owning_ref to determine whether refcount_acquire should be
* fallible
*/
struct btf *arg_btf;
u32 arg_btf_id;
bool arg_owning_ref;
struct {
struct btf_field *field;
} arg_list_head;
struct {
struct btf_field *field;
} arg_rbtree_root;
struct {
enum bpf_dynptr_type type;
u32 id;
u32 ref_obj_id;
} initialized_dynptr;
struct {
u8 spi;
u8 frameno;
} iter;
struct {
struct bpf_map *ptr;
int uid;
} map;
u64 mem_size;
};
struct btf *btf_vmlinux;
static const char *btf_type_name(const struct btf *btf, u32 id)
{
return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off);
}
static DEFINE_MUTEX(bpf_verifier_lock);
static DEFINE_MUTEX(bpf_percpu_ma_lock);
__printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
{
struct bpf_verifier_env *env = private_data;
va_list args;
if (!bpf_verifier_log_needed(&env->log))
return;
va_start(args, fmt);
bpf_verifier_vlog(&env->log, fmt, args);
va_end(args);
}
static void verbose_invalid_scalar(struct bpf_verifier_env *env,
struct bpf_reg_state *reg,
struct bpf_retval_range range, const char *ctx,
const char *reg_name)
{
bool unknown = true;
verbose(env, "%s the register %s has", ctx, reg_name);
if (reg->smin_value > S64_MIN) {
verbose(env, " smin=%lld", reg->smin_value);
unknown = false;
}
if (reg->smax_value < S64_MAX) {
verbose(env, " smax=%lld", reg->smax_value);
unknown = false;
}
if (unknown)
verbose(env, " unknown scalar value");
verbose(env, " should have been in [%d, %d]\n", range.minval, range.maxval);
}
static bool reg_not_null(const struct bpf_reg_state *reg)
{
enum bpf_reg_type type;
type = reg->type;
if (type_may_be_null(type))
return false;
type = base_type(type);
return type == PTR_TO_SOCKET ||
type == PTR_TO_TCP_SOCK ||
type == PTR_TO_MAP_VALUE ||
type == PTR_TO_MAP_KEY ||
type == PTR_TO_SOCK_COMMON ||
(type == PTR_TO_BTF_ID && is_trusted_reg(reg)) ||
type == PTR_TO_MEM;
}
static struct btf_record *reg_btf_record(const struct bpf_reg_state *reg)
{
struct btf_record *rec = NULL;
struct btf_struct_meta *meta;
if (reg->type == PTR_TO_MAP_VALUE) {
rec = reg->map_ptr->record;
} else if (type_is_ptr_alloc_obj(reg->type)) {
meta = btf_find_struct_meta(reg->btf, reg->btf_id);
if (meta)
rec = meta->record;
}
return rec;
}
static bool subprog_is_global(const struct bpf_verifier_env *env, int subprog)
{
struct bpf_func_info_aux *aux = env->prog->aux->func_info_aux;
return aux && aux[subprog].linkage == BTF_FUNC_GLOBAL;
}
static const char *subprog_name(const struct bpf_verifier_env *env, int subprog)
{
struct bpf_func_info *info;
if (!env->prog->aux->func_info)
return "";
info = &env->prog->aux->func_info[subprog];
return btf_type_name(env->prog->aux->btf, info->type_id);
}
static void mark_subprog_exc_cb(struct bpf_verifier_env *env, int subprog)
{
struct bpf_subprog_info *info = subprog_info(env, subprog);
info->is_cb = true;
info->is_async_cb = true;
info->is_exception_cb = true;
}
static bool subprog_is_exc_cb(struct bpf_verifier_env *env, int subprog)
{
return subprog_info(env, subprog)->is_exception_cb;
}
static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
{
return btf_record_has_field(reg_btf_record(reg), BPF_SPIN_LOCK);
}
static bool type_is_rdonly_mem(u32 type)
{
return type & MEM_RDONLY;
}
static bool is_acquire_function(enum bpf_func_id func_id,
const struct bpf_map *map)
{
enum bpf_map_type map_type = map ? map->map_type : BPF_MAP_TYPE_UNSPEC;
if (func_id == BPF_FUNC_sk_lookup_tcp ||
func_id == BPF_FUNC_sk_lookup_udp ||
func_id == BPF_FUNC_skc_lookup_tcp ||
func_id == BPF_FUNC_ringbuf_reserve ||
func_id == BPF_FUNC_kptr_xchg)
return true;
if (func_id == BPF_FUNC_map_lookup_elem &&
(map_type == BPF_MAP_TYPE_SOCKMAP ||
map_type == BPF_MAP_TYPE_SOCKHASH))
return true;
return false;
}
static bool is_ptr_cast_function(enum bpf_func_id func_id)
{
return func_id == BPF_FUNC_tcp_sock ||
func_id == BPF_FUNC_sk_fullsock ||
func_id == BPF_FUNC_skc_to_tcp_sock ||
func_id == BPF_FUNC_skc_to_tcp6_sock ||
func_id == BPF_FUNC_skc_to_udp6_sock ||
func_id == BPF_FUNC_skc_to_mptcp_sock ||
func_id == BPF_FUNC_skc_to_tcp_timewait_sock ||
func_id == BPF_FUNC_skc_to_tcp_request_sock;
}
static bool is_dynptr_ref_function(enum bpf_func_id func_id)
{
return func_id == BPF_FUNC_dynptr_data;
}
static bool is_sync_callback_calling_kfunc(u32 btf_id);
static bool is_async_callback_calling_kfunc(u32 btf_id);
static bool is_callback_calling_kfunc(u32 btf_id);
static bool is_bpf_throw_kfunc(struct bpf_insn *insn);
static bool is_bpf_wq_set_callback_impl_kfunc(u32 btf_id);
static bool is_sync_callback_calling_function(enum bpf_func_id func_id)
{
return func_id == BPF_FUNC_for_each_map_elem ||
func_id == BPF_FUNC_find_vma ||
func_id == BPF_FUNC_loop ||
func_id == BPF_FUNC_user_ringbuf_drain;
}
static bool is_async_callback_calling_function(enum bpf_func_id func_id)
{
return func_id == BPF_FUNC_timer_set_callback;
}
static bool is_callback_calling_function(enum bpf_func_id func_id)
{
return is_sync_callback_calling_function(func_id) ||
is_async_callback_calling_function(func_id);
}
static bool is_sync_callback_calling_insn(struct bpf_insn *insn)
{
return (bpf_helper_call(insn) && is_sync_callback_calling_function(insn->imm)) ||
(bpf_pseudo_kfunc_call(insn) && is_sync_callback_calling_kfunc(insn->imm));
}
static bool is_async_callback_calling_insn(struct bpf_insn *insn)
{
return (bpf_helper_call(insn) && is_async_callback_calling_function(insn->imm)) ||
(bpf_pseudo_kfunc_call(insn) && is_async_callback_calling_kfunc(insn->imm));
}
static bool is_may_goto_insn(struct bpf_insn *insn)
{
return insn->code == (BPF_JMP | BPF_JCOND) && insn->src_reg == BPF_MAY_GOTO;
}
static bool is_may_goto_insn_at(struct bpf_verifier_env *env, int insn_idx)
{
return is_may_goto_insn(&env->prog->insnsi[insn_idx]);
}
static bool is_storage_get_function(enum bpf_func_id func_id)
{
return func_id == BPF_FUNC_sk_storage_get ||
func_id == BPF_FUNC_inode_storage_get ||
func_id == BPF_FUNC_task_storage_get ||
func_id == BPF_FUNC_cgrp_storage_get;
}
static bool helper_multiple_ref_obj_use(enum bpf_func_id func_id,
const struct bpf_map *map)
{
int ref_obj_uses = 0;
if (is_ptr_cast_function(func_id))
ref_obj_uses++;
if (is_acquire_function(func_id, map))
ref_obj_uses++;
if (is_dynptr_ref_function(func_id))
ref_obj_uses++;
return ref_obj_uses > 1;
}
static bool is_cmpxchg_insn(const struct bpf_insn *insn)
{
return BPF_CLASS(insn->code) == BPF_STX &&
BPF_MODE(insn->code) == BPF_ATOMIC &&
insn->imm == BPF_CMPXCHG;
}
static int __get_spi(s32 off)
{
return (-off - 1) / BPF_REG_SIZE;
}
static struct bpf_func_state *func(struct bpf_verifier_env *env,
const struct bpf_reg_state *reg)
{
struct bpf_verifier_state *cur = env->cur_state;
return cur->frame[reg->frameno];
}
static bool is_spi_bounds_valid(struct bpf_func_state *state, int spi, int nr_slots)
{
int allocated_slots = state->allocated_stack / BPF_REG_SIZE;
/* We need to check that slots between [spi - nr_slots + 1, spi] are
* within [0, allocated_stack).
*
* Please note that the spi grows downwards. For example, a dynptr
* takes the size of two stack slots; the first slot will be at
* spi and the second slot will be at spi - 1.
*/
return spi - nr_slots + 1 >= 0 && spi < allocated_slots;
}
static int stack_slot_obj_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
const char *obj_kind, int nr_slots)
{
int off, spi;
if (!tnum_is_const(reg->var_off)) {
verbose(env, "%s has to be at a constant offset\n", obj_kind);
return -EINVAL;
}
off = reg->off + reg->var_off.value;
if (off % BPF_REG_SIZE) {
verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off);
return -EINVAL;
}
spi = __get_spi(off);
if (spi + 1 < nr_slots) {
verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off);
return -EINVAL;
}
if (!is_spi_bounds_valid(func(env, reg), spi, nr_slots))
return -ERANGE;
return spi;
}
static int dynptr_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
return stack_slot_obj_get_spi(env, reg, "dynptr", BPF_DYNPTR_NR_SLOTS);
}
static int iter_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int nr_slots)
{
return stack_slot_obj_get_spi(env, reg, "iter", nr_slots);
}
static enum bpf_dynptr_type arg_to_dynptr_type(enum bpf_arg_type arg_type)
{
switch (arg_type & DYNPTR_TYPE_FLAG_MASK) {
case DYNPTR_TYPE_LOCAL:
return BPF_DYNPTR_TYPE_LOCAL;
case DYNPTR_TYPE_RINGBUF:
return BPF_DYNPTR_TYPE_RINGBUF;
case DYNPTR_TYPE_SKB:
return BPF_DYNPTR_TYPE_SKB;
case DYNPTR_TYPE_XDP:
return BPF_DYNPTR_TYPE_XDP;
default:
return BPF_DYNPTR_TYPE_INVALID;
}
}
static enum bpf_type_flag get_dynptr_type_flag(enum bpf_dynptr_type type)
{
switch (type) {
case BPF_DYNPTR_TYPE_LOCAL:
return DYNPTR_TYPE_LOCAL;
case BPF_DYNPTR_TYPE_RINGBUF:
return DYNPTR_TYPE_RINGBUF;
case BPF_DYNPTR_TYPE_SKB:
return DYNPTR_TYPE_SKB;
case BPF_DYNPTR_TYPE_XDP:
return DYNPTR_TYPE_XDP;
default:
return 0;
}
}
static bool dynptr_type_refcounted(enum bpf_dynptr_type type)
{
return type == BPF_DYNPTR_TYPE_RINGBUF;
}
static void __mark_dynptr_reg(struct bpf_reg_state *reg,
enum bpf_dynptr_type type,
bool first_slot, int dynptr_id);
static void __mark_reg_not_init(const struct bpf_verifier_env *env,
struct bpf_reg_state *reg);
static void mark_dynptr_stack_regs(struct bpf_verifier_env *env,
struct bpf_reg_state *sreg1,
struct bpf_reg_state *sreg2,
enum bpf_dynptr_type type)
{
int id = ++env->id_gen;
__mark_dynptr_reg(sreg1, type, true, id);
__mark_dynptr_reg(sreg2, type, false, id);
}
static void mark_dynptr_cb_reg(struct bpf_verifier_env *env,
struct bpf_reg_state *reg,
enum bpf_dynptr_type type)
{
__mark_dynptr_reg(reg, type, true, ++env->id_gen);
}
static int destroy_if_dynptr_stack_slot(struct bpf_verifier_env *env,
struct bpf_func_state *state, int spi);
static int mark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
enum bpf_arg_type arg_type, int insn_idx, int clone_ref_obj_id)
{
struct bpf_func_state *state = func(env, reg);
enum bpf_dynptr_type type;
int spi, i, err;
spi = dynptr_get_spi(env, reg);
if (spi < 0)
return spi;
/* We cannot assume both spi and spi - 1 belong to the same dynptr,
* hence we need to call destroy_if_dynptr_stack_slot twice for both,
* to ensure that for the following example:
* [d1][d1][d2][d2]
* spi 3 2 1 0
* So marking spi = 2 should lead to destruction of both d1 and d2. In
* case they do belong to same dynptr, second call won't see slot_type
* as STACK_DYNPTR and will simply skip destruction.
*/
err = destroy_if_dynptr_stack_slot(env, state, spi);
if (err)
return err;
err = destroy_if_dynptr_stack_slot(env, state, spi - 1);
if (err)
return err;
for (i = 0; i < BPF_REG_SIZE; i++) {
state->stack[spi].slot_type[i] = STACK_DYNPTR;
state->stack[spi - 1].slot_type[i] = STACK_DYNPTR;
}
type = arg_to_dynptr_type(arg_type);
if (type == BPF_DYNPTR_TYPE_INVALID)
return -EINVAL;
mark_dynptr_stack_regs(env, &state->stack[spi].spilled_ptr,
&state->stack[spi - 1].spilled_ptr, type);
if (dynptr_type_refcounted(type)) {
/* The id is used to track proper releasing */
int id;
if (clone_ref_obj_id)
id = clone_ref_obj_id;
else
id = acquire_reference_state(env, insn_idx);
if (id < 0)
return id;
state->stack[spi].spilled_ptr.ref_obj_id = id;
state->stack[spi - 1].spilled_ptr.ref_obj_id = id;
}
state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN;
return 0;
}
static void invalidate_dynptr(struct bpf_verifier_env *env, struct bpf_func_state *state, int spi)
{
int i;
for (i = 0; i < BPF_REG_SIZE; i++) {
state->stack[spi].slot_type[i] = STACK_INVALID;
state->stack[spi - 1].slot_type[i] = STACK_INVALID;
}
__mark_reg_not_init(env, &state->stack[spi].spilled_ptr);
__mark_reg_not_init(env, &state->stack[spi - 1].spilled_ptr);
/* Why do we need to set REG_LIVE_WRITTEN for STACK_INVALID slot?
*
* While we don't allow reading STACK_INVALID, it is still possible to
* do <8 byte writes marking some but not all slots as STACK_MISC. Then,
* helpers or insns can do partial read of that part without failing,
* but check_stack_range_initialized, check_stack_read_var_off, and
* check_stack_read_fixed_off will do mark_reg_read for all 8-bytes of
* the slot conservatively. Hence we need to prevent those liveness
* marking walks.
*
* This was not a problem before because STACK_INVALID is only set by
* default (where the default reg state has its reg->parent as NULL), or
* in clean_live_states after REG_LIVE_DONE (at which point
* mark_reg_read won't walk reg->parent chain), but not randomly during
* verifier state exploration (like we did above). Hence, for our case
* parentage chain will still be live (i.e. reg->parent may be
* non-NULL), while earlier reg->parent was NULL, so we need
* REG_LIVE_WRITTEN to screen off read marker propagation when it is
* done later on reads or by mark_dynptr_read as well to unnecessary
* mark registers in verifier state.
*/
state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN;
}
static int unmark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
struct bpf_func_state *state = func(env, reg);
int spi, ref_obj_id, i;
spi = dynptr_get_spi(env, reg);
if (spi < 0)
return spi;
if (!dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) {
invalidate_dynptr(env, state, spi);
return 0;
}
ref_obj_id = state->stack[spi].spilled_ptr.ref_obj_id;
/* If the dynptr has a ref_obj_id, then we need to invalidate
* two things:
*
* 1) Any dynptrs with a matching ref_obj_id (clones)
* 2) Any slices derived from this dynptr.
*/
/* Invalidate any slices associated with this dynptr */
WARN_ON_ONCE(release_reference(env, ref_obj_id));
/* Invalidate any dynptr clones */
for (i = 1; i < state->allocated_stack / BPF_REG_SIZE; i++) {
if (state->stack[i].spilled_ptr.ref_obj_id != ref_obj_id)
continue;
/* it should always be the case that if the ref obj id
* matches then the stack slot also belongs to a
* dynptr
*/
if (state->stack[i].slot_type[0] != STACK_DYNPTR) {
verbose(env, "verifier internal error: misconfigured ref_obj_id\n");
return -EFAULT;
}
if (state->stack[i].spilled_ptr.dynptr.first_slot)
invalidate_dynptr(env, state, i);
}
return 0;
}
static void __mark_reg_unknown(const struct bpf_verifier_env *env,
struct bpf_reg_state *reg);
static void mark_reg_invalid(const struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
if (!env->allow_ptr_leaks)
__mark_reg_not_init(env, reg);
else
__mark_reg_unknown(env, reg);
}
static int destroy_if_dynptr_stack_slot(struct bpf_verifier_env *env,
struct bpf_func_state *state, int spi)
{
struct bpf_func_state *fstate;
struct bpf_reg_state *dreg;
int i, dynptr_id;
/* We always ensure that STACK_DYNPTR is never set partially,
* hence just checking for slot_type[0] is enough. This is
* different for STACK_SPILL, where it may be only set for
* 1 byte, so code has to use is_spilled_reg.
*/
if (state->stack[spi].slot_type[0] != STACK_DYNPTR)
return 0;
/* Reposition spi to first slot */
if (!state->stack[spi].spilled_ptr.dynptr.first_slot)
spi = spi + 1;
if (dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) {
verbose(env, "cannot overwrite referenced dynptr\n");
return -EINVAL;
}
mark_stack_slot_scratched(env, spi);
mark_stack_slot_scratched(env, spi - 1);
/* Writing partially to one dynptr stack slot destroys both. */
for (i = 0; i < BPF_REG_SIZE; i++) {
state->stack[spi].slot_type[i] = STACK_INVALID;
state->stack[spi - 1].slot_type[i] = STACK_INVALID;
}
dynptr_id = state->stack[spi].spilled_ptr.id;
/* Invalidate any slices associated with this dynptr */
bpf_for_each_reg_in_vstate(env->cur_state, fstate, dreg, ({
/* Dynptr slices are only PTR_TO_MEM_OR_NULL and PTR_TO_MEM */
if (dreg->type != (PTR_TO_MEM | PTR_MAYBE_NULL) && dreg->type != PTR_TO_MEM)
continue;
if (dreg->dynptr_id == dynptr_id)
mark_reg_invalid(env, dreg);
}));
/* Do not release reference state, we are destroying dynptr on stack,
* not using some helper to release it. Just reset register.
*/
__mark_reg_not_init(env, &state->stack[spi].spilled_ptr);
__mark_reg_not_init(env, &state->stack[spi - 1].spilled_ptr);
/* Same reason as unmark_stack_slots_dynptr above */
state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN;
return 0;
}
static bool is_dynptr_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
int spi;
if (reg->type == CONST_PTR_TO_DYNPTR)
return false;
spi = dynptr_get_spi(env, reg);
/* -ERANGE (i.e. spi not falling into allocated stack slots) isn't an
* error because this just means the stack state hasn't been updated yet.
* We will do check_mem_access to check and update stack bounds later.
*/
if (spi < 0 && spi != -ERANGE)
return false;
/* We don't need to check if the stack slots are marked by previous
* dynptr initializations because we allow overwriting existing unreferenced
* STACK_DYNPTR slots, see mark_stack_slots_dynptr which calls
* destroy_if_dynptr_stack_slot to ensure dynptr objects at the slots we are
* touching are completely destructed before we reinitialize them for a new
* one. For referenced ones, destroy_if_dynptr_stack_slot returns an error early
* instead of delaying it until the end where the user will get "Unreleased
* reference" error.
*/
return true;
}
static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
struct bpf_func_state *state = func(env, reg);
int i, spi;
/* This already represents first slot of initialized bpf_dynptr.
*
* CONST_PTR_TO_DYNPTR already has fixed and var_off as 0 due to
* check_func_arg_reg_off's logic, so we don't need to check its
* offset and alignment.
*/
if (reg->type == CONST_PTR_TO_DYNPTR)
return true;
spi = dynptr_get_spi(env, reg);
if (spi < 0)
return false;
if (!state->stack[spi].spilled_ptr.dynptr.first_slot)
return false;
for (i = 0; i < BPF_REG_SIZE; i++) {
if (state->stack[spi].slot_type[i] != STACK_DYNPTR ||
state->stack[spi - 1].slot_type[i] != STACK_DYNPTR)
return false;
}
return true;
}
static bool is_dynptr_type_expected(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
enum bpf_arg_type arg_type)
{
struct bpf_func_state *state = func(env, reg);
enum bpf_dynptr_type dynptr_type;
int spi;
/* ARG_PTR_TO_DYNPTR takes any type of dynptr */
if (arg_type == ARG_PTR_TO_DYNPTR)
return true;
dynptr_type = arg_to_dynptr_type(arg_type);
if (reg->type == CONST_PTR_TO_DYNPTR) {
return reg->dynptr.type == dynptr_type;
} else {
spi = dynptr_get_spi(env, reg);
if (spi < 0)
return false;
return state->stack[spi].spilled_ptr.dynptr.type == dynptr_type;
}
}
static void __mark_reg_known_zero(struct bpf_reg_state *reg);
static bool in_rcu_cs(struct bpf_verifier_env *env);
static bool is_kfunc_rcu_protected(struct bpf_kfunc_call_arg_meta *meta);
static int mark_stack_slots_iter(struct bpf_verifier_env *env,
struct bpf_kfunc_call_arg_meta *meta,
struct bpf_reg_state *reg, int insn_idx,
struct btf *btf, u32 btf_id, int nr_slots)
{
struct bpf_func_state *state = func(env, reg);
int spi, i, j, id;
spi = iter_get_spi(env, reg, nr_slots);
if (spi < 0)
return spi;
id = acquire_reference_state(env, insn_idx);
if (id < 0)
return id;
for (i = 0; i < nr_slots; i++) {
struct bpf_stack_state *slot = &state->stack[spi - i];
struct bpf_reg_state *st = &slot->spilled_ptr;
__mark_reg_known_zero(st);
st->type = PTR_TO_STACK; /* we don't have dedicated reg type */
if (is_kfunc_rcu_protected(meta)) {
if (in_rcu_cs(env))
st->type |= MEM_RCU;
else
st->type |= PTR_UNTRUSTED;
}
st->live |= REG_LIVE_WRITTEN;
st->ref_obj_id = i == 0 ? id : 0;
st->iter.btf = btf;
st->iter.btf_id = btf_id;
st->iter.state = BPF_ITER_STATE_ACTIVE;
st->iter.depth = 0;
for (j = 0; j < BPF_REG_SIZE; j++)
slot->slot_type[j] = STACK_ITER;
mark_stack_slot_scratched(env, spi - i);
}
return 0;
}
static int unmark_stack_slots_iter(struct bpf_verifier_env *env,
struct bpf_reg_state *reg, int nr_slots)
{
struct bpf_func_state *state = func(env, reg);
int spi, i, j;
spi = iter_get_spi(env, reg, nr_slots);
if (spi < 0)
return spi;
for (i = 0; i < nr_slots; i++) {
struct bpf_stack_state *slot = &state->stack[spi - i];
struct bpf_reg_state *st = &slot->spilled_ptr;
if (i == 0)
WARN_ON_ONCE(release_reference(env, st->ref_obj_id));
__mark_reg_not_init(env, st);
/* see unmark_stack_slots_dynptr() for why we need to set REG_LIVE_WRITTEN */
st->live |= REG_LIVE_WRITTEN;
for (j = 0; j < BPF_REG_SIZE; j++)
slot->slot_type[j] = STACK_INVALID;
mark_stack_slot_scratched(env, spi - i);
}
return 0;
}
static bool is_iter_reg_valid_uninit(struct bpf_verifier_env *env,
struct bpf_reg_state *reg, int nr_slots)
{
struct bpf_func_state *state = func(env, reg);
int spi, i, j;
/* For -ERANGE (i.e. spi not falling into allocated stack slots), we
* will do check_mem_access to check and update stack bounds later, so
* return true for that case.
*/
spi = iter_get_spi(env, reg, nr_slots);
if (spi == -ERANGE)
return true;
if (spi < 0)
return false;
for (i = 0; i < nr_slots; i++) {
struct bpf_stack_state *slot = &state->stack[spi - i];
for (j = 0; j < BPF_REG_SIZE; j++)
if (slot->slot_type[j] == STACK_ITER)
return false;
}
return true;
}
static int is_iter_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
struct btf *btf, u32 btf_id, int nr_slots)
{
struct bpf_func_state *state = func(env, reg);
int spi, i, j;
spi = iter_get_spi(env, reg, nr_slots);
if (spi < 0)
return -EINVAL;
for (i = 0; i < nr_slots; i++) {
struct bpf_stack_state *slot = &state->stack[spi - i];
struct bpf_reg_state *st = &slot->spilled_ptr;
if (st->type & PTR_UNTRUSTED)
return -EPROTO;
/* only main (first) slot has ref_obj_id set */
if (i == 0 && !st->ref_obj_id)
return -EINVAL;
if (i != 0 && st->ref_obj_id)
return -EINVAL;
if (st->iter.btf != btf || st->iter.btf_id != btf_id)
return -EINVAL;
for (j = 0; j < BPF_REG_SIZE; j++)
if (slot->slot_type[j] != STACK_ITER)
return -EINVAL;
}
return 0;
}
/* Check if given stack slot is "special":
* - spilled register state (STACK_SPILL);
* - dynptr state (STACK_DYNPTR);
* - iter state (STACK_ITER).
*/
static bool is_stack_slot_special(const struct bpf_stack_state *stack)
{
enum bpf_stack_slot_type type = stack->slot_type[BPF_REG_SIZE - 1];
switch (type) {
case STACK_SPILL:
case STACK_DYNPTR:
case STACK_ITER:
return true;
case STACK_INVALID:
case STACK_MISC:
case STACK_ZERO:
return false;
default:
WARN_ONCE(1, "unknown stack slot type %d\n", type);
return true;
}
}
/* The reg state of a pointer or a bounded scalar was saved when
* it was spilled to the stack.
*/
static bool is_spilled_reg(const struct bpf_stack_state *stack)
{
return stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL;
}
static bool is_spilled_scalar_reg(const struct bpf_stack_state *stack)
{
return stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL &&
stack->spilled_ptr.type == SCALAR_VALUE;
}
static bool is_spilled_scalar_reg64(const struct bpf_stack_state *stack)
{
return stack->slot_type[0] == STACK_SPILL &&
stack->spilled_ptr.type == SCALAR_VALUE;
}
/* Mark stack slot as STACK_MISC, unless it is already STACK_INVALID, in which
* case they are equivalent, or it's STACK_ZERO, in which case we preserve
* more precise STACK_ZERO.
* Note, in uprivileged mode leaving STACK_INVALID is wrong, so we take
* env->allow_ptr_leaks into account and force STACK_MISC, if necessary.
*/
static void mark_stack_slot_misc(struct bpf_verifier_env *env, u8 *stype)
{
if (*stype == STACK_ZERO)
return;
if (env->allow_ptr_leaks && *stype == STACK_INVALID)
return;
*stype = STACK_MISC;
}
static void scrub_spilled_slot(u8 *stype)
{
if (*stype != STACK_INVALID)
*stype = STACK_MISC;
}
/* copy array src of length n * size bytes to dst. dst is reallocated if it's too
* small to hold src. This is different from krealloc since we don't want to preserve
* the contents of dst.
*
* Leaves dst untouched if src is NULL or length is zero. Returns NULL if memory could
* not be allocated.
*/
static void *copy_array(void *dst, const void *src, size_t n, size_t size, gfp_t flags)
{
size_t alloc_bytes;
void *orig = dst;
size_t bytes;
if (ZERO_OR_NULL_PTR(src))
goto out;
if (unlikely(check_mul_overflow(n, size, &bytes)))
return NULL;
alloc_bytes = max(ksize(orig), kmalloc_size_roundup(bytes));
dst = krealloc(orig, alloc_bytes, flags);
if (!dst) {
kfree(orig);
return NULL;
}
memcpy(dst, src, bytes);
out:
return dst ? dst : ZERO_SIZE_PTR;
}
/* resize an array from old_n items to new_n items. the array is reallocated if it's too
* small to hold new_n items. new items are zeroed out if the array grows.
*
* Contrary to krealloc_array, does not free arr if new_n is zero.
*/
static void *realloc_array(void *arr, size_t old_n, size_t new_n, size_t size)
{
size_t alloc_size;
void *new_arr;
if (!new_n || old_n == new_n)
goto out;
alloc_size = kmalloc_size_roundup(size_mul(new_n, size));
new_arr = krealloc(arr, alloc_size, GFP_KERNEL);
if (!new_arr) {
kfree(arr);
return NULL;
}
arr = new_arr;
if (new_n > old_n)
memset(arr + old_n * size, 0, (new_n - old_n) * size);
out:
return arr ? arr : ZERO_SIZE_PTR;
}
static int copy_reference_state(struct bpf_func_state *dst, const struct bpf_func_state *src)
{
dst->refs = copy_array(dst->refs, src->refs, src->acquired_refs,
sizeof(struct bpf_reference_state), GFP_KERNEL);
if (!dst->refs)
return -ENOMEM;
dst->acquired_refs = src->acquired_refs;
return 0;
}
static int copy_stack_state(struct bpf_func_state *dst, const struct bpf_func_state *src)
{
size_t n = src->allocated_stack / BPF_REG_SIZE;
dst->stack = copy_array(dst->stack, src->stack, n, sizeof(struct bpf_stack_state),
GFP_KERNEL);
if (!dst->stack)
return -ENOMEM;
dst->allocated_stack = src->allocated_stack;
return 0;
}
static int resize_reference_state(struct bpf_func_state *state, size_t n)
{
state->refs = realloc_array(state->refs, state->acquired_refs, n,
sizeof(struct bpf_reference_state));
if (!state->refs)
return -ENOMEM;
state->acquired_refs = n;
return 0;
}
/* Possibly update state->allocated_stack to be at least size bytes. Also
* possibly update the function's high-water mark in its bpf_subprog_info.
*/
static int grow_stack_state(struct bpf_verifier_env *env, struct bpf_func_state *state, int size)
{
size_t old_n = state->allocated_stack / BPF_REG_SIZE, n;
/* The stack size is always a multiple of BPF_REG_SIZE. */
size = round_up(size, BPF_REG_SIZE);
n = size / BPF_REG_SIZE;
if (old_n >= n)
return 0;
state->stack = realloc_array(state->stack, old_n, n, sizeof(struct bpf_stack_state));
if (!state->stack)
return -ENOMEM;
state->allocated_stack = size;
/* update known max for given subprogram */
if (env->subprog_info[state->subprogno].stack_depth < size)
env->subprog_info[state->subprogno].stack_depth = size;
return 0;
}
/* Acquire a pointer id from the env and update the state->refs to include
* this new pointer reference.
* On success, returns a valid pointer id to associate with the register
* On failure, returns a negative errno.
*/
static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx)
{
struct bpf_func_state *state = cur_func(env);
int new_ofs = state->acquired_refs;
int id, err;
err = resize_reference_state(state, state->acquired_refs + 1);
if (err)
return err;
id = ++env->id_gen;
state->refs[new_ofs].id = id;
state->refs[new_ofs].insn_idx = insn_idx;
state->refs[new_ofs].callback_ref = state->in_callback_fn ? state->frameno : 0;
return id;
}
/* release function corresponding to acquire_reference_state(). Idempotent. */
static int release_reference_state(struct bpf_func_state *state, int ptr_id)
{
int i, last_idx;
last_idx = state->acquired_refs - 1;
for (i = 0; i < state->acquired_refs; i++) {
if (state->refs[i].id == ptr_id) {
/* Cannot release caller references in callbacks */
if (state->in_callback_fn && state->refs[i].callback_ref != state->frameno)
return -EINVAL;
if (last_idx && i != last_idx)
memcpy(&state->refs[i], &state->refs[last_idx],
sizeof(*state->refs));
memset(&state->refs[last_idx], 0, sizeof(*state->refs));
state->acquired_refs--;
return 0;
}
}
return -EINVAL;
}
static void free_func_state(struct bpf_func_state *state)
{
if (!state)
return;
kfree(state->refs);
kfree(state->stack);
kfree(state);
}
static void clear_jmp_history(struct bpf_verifier_state *state)
{
kfree(state->jmp_history);
state->jmp_history = NULL;
state->jmp_history_cnt = 0;
}
static void free_verifier_state(struct bpf_verifier_state *state,
bool free_self)
{
int i;
for (i = 0; i <= state->curframe; i++) {
free_func_state(state->frame[i]);
state->frame[i] = NULL;
}
clear_jmp_history(state);
if (free_self)
kfree(state);
}
/* copy verifier state from src to dst growing dst stack space
* when necessary to accommodate larger src stack
*/
static int copy_func_state(struct bpf_func_state *dst,
const struct bpf_func_state *src)
{
int err;
memcpy(dst, src, offsetof(struct bpf_func_state, acquired_refs));
err = copy_reference_state(dst, src);
if (err)
return err;
return copy_stack_state(dst, src);
}
static int copy_verifier_state(struct bpf_verifier_state *dst_state,
const struct bpf_verifier_state *src)
{
struct bpf_func_state *dst;
int i, err;
dst_state->jmp_history = copy_array(dst_state->jmp_history, src->jmp_history,
src->jmp_history_cnt, sizeof(*dst_state->jmp_history),
GFP_USER);
if (!dst_state->jmp_history)
return -ENOMEM;
dst_state->jmp_history_cnt = src->jmp_history_cnt;
/* if dst has more stack frames then src frame, free them, this is also
* necessary in case of exceptional exits using bpf_throw.
*/
for (i = src->curframe + 1; i <= dst_state->curframe; i++) {
free_func_state(dst_state->frame[i]);
dst_state->frame[i] = NULL;
}
dst_state->speculative = src->speculative;
dst_state->active_rcu_lock = src->active_rcu_lock;
dst_state->active_preempt_lock = src->active_preempt_lock;
dst_state->in_sleepable = src->in_sleepable;
dst_state->curframe = src->curframe;
dst_state->active_lock.ptr = src->active_lock.ptr;
dst_state->active_lock.id = src->active_lock.id;
dst_state->branches = src->branches;
dst_state->parent = src->parent;
dst_state->first_insn_idx = src->first_insn_idx;
dst_state->last_insn_idx = src->last_insn_idx;
dst_state->dfs_depth = src->dfs_depth;
dst_state->callback_unroll_depth = src->callback_unroll_depth;
dst_state->used_as_loop_entry = src->used_as_loop_entry;
dst_state->may_goto_depth = src->may_goto_depth;
for (i = 0; i <= src->curframe; i++) {
dst = dst_state->frame[i];
if (!dst) {
dst = kzalloc(sizeof(*dst), GFP_KERNEL);
if (!dst)
return -ENOMEM;
dst_state->frame[i] = dst;
}
err = copy_func_state(dst, src->frame[i]);
if (err)
return err;
}
return 0;
}
static u32 state_htab_size(struct bpf_verifier_env *env)
{
return env->prog->len;
}
static struct bpf_verifier_state_list **explored_state(struct bpf_verifier_env *env, int idx)
{
struct bpf_verifier_state *cur = env->cur_state;
struct bpf_func_state *state = cur->frame[cur->curframe];
return &env->explored_states[(idx ^ state->callsite) % state_htab_size(env)];
}
static bool same_callsites(struct bpf_verifier_state *a, struct bpf_verifier_state *b)
{
int fr;
if (a->curframe != b->curframe)
return false;
for (fr = a->curframe; fr >= 0; fr--)
if (a->frame[fr]->callsite != b->frame[fr]->callsite)
return false;
return true;
}
/* Open coded iterators allow back-edges in the state graph in order to
* check unbounded loops that iterators.
*
* In is_state_visited() it is necessary to know if explored states are
* part of some loops in order to decide whether non-exact states
* comparison could be used:
* - non-exact states comparison establishes sub-state relation and uses
* read and precision marks to do so, these marks are propagated from
* children states and thus are not guaranteed to be final in a loop;
* - exact states comparison just checks if current and explored states
* are identical (and thus form a back-edge).
*
* Paper "A New Algorithm for Identifying Loops in Decompilation"
* by Tao Wei, Jian Mao, Wei Zou and Yu Chen [1] presents a convenient
* algorithm for loop structure detection and gives an overview of
* relevant terminology. It also has helpful illustrations.
*
* [1] https://api.semanticscholar.org/CorpusID:15784067
*
* We use a similar algorithm but because loop nested structure is
* irrelevant for verifier ours is significantly simpler and resembles
* strongly connected components algorithm from Sedgewick's textbook.
*
* Define topmost loop entry as a first node of the loop traversed in a
* depth first search starting from initial state. The goal of the loop
* tracking algorithm is to associate topmost loop entries with states
* derived from these entries.
*
* For each step in the DFS states traversal algorithm needs to identify
* the following situations:
*
* initial initial initial
* | | |
* V V V
* ... ... .---------> hdr
* | | | |
* V V | V
* cur .-> succ | .------...
* | | | | | |
* V | V | V V
* succ '-- cur | ... ...
* | | |
* | V V
* | succ <- cur
* | |
* | V
* | ...
* | |
* '----'
*
* (A) successor state of cur (B) successor state of cur or it's entry
* not yet traversed are in current DFS path, thus cur and succ
* are members of the same outermost loop
*
* initial initial
* | |
* V V
* ... ...
* | |
* V V
* .------... .------...
* | | | |
* V V V V
* .-> hdr ... ... ...
* | | | | |
* | V V V V
* | succ <- cur succ <- cur
* | | |
* | V V
* | ... ...
* | | |
* '----' exit
*
* (C) successor state of cur is a part of some loop but this loop
* does not include cur or successor state is not in a loop at all.
*
* Algorithm could be described as the following python code:
*
* traversed = set() # Set of traversed nodes
* entries = {} # Mapping from node to loop entry
* depths = {} # Depth level assigned to graph node
* path = set() # Current DFS path
*
* # Find outermost loop entry known for n
* def get_loop_entry(n):
* h = entries.get(n, None)
* while h in entries and entries[h] != h:
* h = entries[h]
* return h
*
* # Update n's loop entry if h's outermost entry comes
* # before n's outermost entry in current DFS path.
* def update_loop_entry(n, h):
* n1 = get_loop_entry(n) or n
* h1 = get_loop_entry(h) or h
* if h1 in path and depths[h1] <= depths[n1]:
* entries[n] = h1
*
* def dfs(n, depth):
* traversed.add(n)
* path.add(n)
* depths[n] = depth
* for succ in G.successors(n):
* if succ not in traversed:
* # Case A: explore succ and update cur's loop entry
* # only if succ's entry is in current DFS path.
* dfs(succ, depth + 1)
* h = get_loop_entry(succ)
* update_loop_entry(n, h)
* else:
* # Case B or C depending on `h1 in path` check in update_loop_entry().
* update_loop_entry(n, succ)
* path.remove(n)
*
* To adapt this algorithm for use with verifier:
* - use st->branch == 0 as a signal that DFS of succ had been finished
* and cur's loop entry has to be updated (case A), handle this in
* update_branch_counts();
* - use st->branch > 0 as a signal that st is in the current DFS path;
* - handle cases B and C in is_state_visited();
* - update topmost loop entry for intermediate states in get_loop_entry().
*/
static struct bpf_verifier_state *get_loop_entry(struct bpf_verifier_state *st)
{
struct bpf_verifier_state *topmost = st->loop_entry, *old;
while (topmost && topmost->loop_entry && topmost != topmost->loop_entry)
topmost = topmost->loop_entry;
/* Update loop entries for intermediate states to avoid this
* traversal in future get_loop_entry() calls.
*/
while (st && st->loop_entry != topmost) {
old = st->loop_entry;
st->loop_entry = topmost;
st = old;
}
return topmost;
}
static void update_loop_entry(struct bpf_verifier_state *cur, struct bpf_verifier_state *hdr)
{
struct bpf_verifier_state *cur1, *hdr1;
cur1 = get_loop_entry(cur) ?: cur;
hdr1 = get_loop_entry(hdr) ?: hdr;
/* The head1->branches check decides between cases B and C in
* comment for get_loop_entry(). If hdr1->branches == 0 then
* head's topmost loop entry is not in current DFS path,
* hence 'cur' and 'hdr' are not in the same loop and there is
* no need to update cur->loop_entry.
*/
if (hdr1->branches && hdr1->dfs_depth <= cur1->dfs_depth) {
cur->loop_entry = hdr;
hdr->used_as_loop_entry = true;
}
}
static void update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
{
while (st) {
u32 br = --st->branches;
/* br == 0 signals that DFS exploration for 'st' is finished,
* thus it is necessary to update parent's loop entry if it
* turned out that st is a part of some loop.
* This is a part of 'case A' in get_loop_entry() comment.
*/
if (br == 0 && st->parent && st->loop_entry)
update_loop_entry(st->parent, st->loop_entry);
/* WARN_ON(br > 1) technically makes sense here,
* but see comment in push_stack(), hence:
*/
WARN_ONCE((int)br < 0,
"BUG update_branch_counts:branches_to_explore=%d\n",
br);
if (br)
break;
st = st->parent;
}
}
static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx,
int *insn_idx, bool pop_log)
{
struct bpf_verifier_state *cur = env->cur_state;
struct bpf_verifier_stack_elem *elem, *head = env->head;
int err;
if (env->head == NULL)
return -ENOENT;
if (cur) {
err = copy_verifier_state(cur, &head->st);
if (err)
return err;
}
if (pop_log)
bpf_vlog_reset(&env->log, head->log_pos);
if (insn_idx)
*insn_idx = head->insn_idx;
if (prev_insn_idx)
*prev_insn_idx = head->prev_insn_idx;
elem = head->next;
free_verifier_state(&head->st, false);
kfree(head);
env->head = elem;
env->stack_size--;
return 0;
}
static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
int insn_idx, int prev_insn_idx,
bool speculative)
{
struct bpf_verifier_state *cur = env->cur_state;
struct bpf_verifier_stack_elem *elem;
int err;
elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
if (!elem)
goto err;
elem->insn_idx = insn_idx;
elem->prev_insn_idx = prev_insn_idx;
elem->next = env->head;
elem->log_pos = env->log.end_pos;
env->head = elem;
env->stack_size++;
err = copy_verifier_state(&elem->st, cur);
if (err)
goto err;
elem->st.speculative |= speculative;
if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
verbose(env, "The sequence of %d jumps is too complex.\n",
env->stack_size);
goto err;
}
if (elem->st.parent) {
++elem->st.parent->branches;
/* WARN_ON(branches > 2) technically makes sense here,
* but
* 1. speculative states will bump 'branches' for non-branch
* instructions
* 2. is_state_visited() heuristics may decide not to create
* a new state for a sequence of branches and all such current
* and cloned states will be pointing to a single parent state
* which might have large 'branches' count.
*/
}
return &elem->st;
err:
free_verifier_state(env->cur_state, true);
env->cur_state = NULL;
/* pop all elements and return */
while (!pop_stack(env, NULL, NULL, false));
return NULL;
}
#define CALLER_SAVED_REGS 6
static const int caller_saved[CALLER_SAVED_REGS] = {
BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
};
/* This helper doesn't clear reg->id */
static void ___mark_reg_known(struct bpf_reg_state *reg, u64 imm)
{
reg->var_off = tnum_const(imm);
reg->smin_value = (s64)imm;
reg->smax_value = (s64)imm;
reg->umin_value = imm;
reg->umax_value = imm;
reg->s32_min_value = (s32)imm;
reg->s32_max_value = (s32)imm;
reg->u32_min_value = (u32)imm;
reg->u32_max_value = (u32)imm;
}
/* Mark the unknown part of a register (variable offset or scalar value) as
* known to have the value @imm.
*/
static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm)
{
/* Clear off and union(map_ptr, range) */
memset(((u8 *)reg) + sizeof(reg->type), 0,
offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type));
reg->id = 0;
reg->ref_obj_id = 0;
___mark_reg_known(reg, imm);
}
static void __mark_reg32_known(struct bpf_reg_state *reg, u64 imm)
{
reg->var_off = tnum_const_subreg(reg->var_off, imm);
reg->s32_min_value = (s32)imm;
reg->s32_max_value = (s32)imm;
reg->u32_min_value = (u32)imm;
reg->u32_max_value = (u32)imm;
}
/* Mark the 'variable offset' part of a register as zero. This should be
* used only on registers holding a pointer type.
*/
static void __mark_reg_known_zero(struct bpf_reg_state *reg)
{
__mark_reg_known(reg, 0);
}
static void __mark_reg_const_zero(const struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
__mark_reg_known(reg, 0);
reg->type = SCALAR_VALUE;
/* all scalars are assumed imprecise initially (unless unprivileged,
* in which case everything is forced to be precise)
*/
reg->precise = !env->bpf_capable;
}
static void mark_reg_known_zero(struct bpf_verifier_env *env,
struct bpf_reg_state *regs, u32 regno)
{
if (WARN_ON(regno >= MAX_BPF_REG)) {
verbose(env, "mark_reg_known_zero(regs, %u)\n", regno);
/* Something bad happened, let's kill all regs */
for (regno = 0; regno < MAX_BPF_REG; regno++)
__mark_reg_not_init(env, regs + regno);
return;
}
__mark_reg_known_zero(regs + regno);
}
static void __mark_dynptr_reg(struct bpf_reg_state *reg, enum bpf_dynptr_type type,
bool first_slot, int dynptr_id)
{
/* reg->type has no meaning for STACK_DYNPTR, but when we set reg for
* callback arguments, it does need to be CONST_PTR_TO_DYNPTR, so simply
* set it unconditionally as it is ignored for STACK_DYNPTR anyway.
*/
__mark_reg_known_zero(reg);
reg->type = CONST_PTR_TO_DYNPTR;
/* Give each dynptr a unique id to uniquely associate slices to it. */
reg->id = dynptr_id;
reg->dynptr.type = type;
reg->dynptr.first_slot = first_slot;
}
static void mark_ptr_not_null_reg(struct bpf_reg_state *reg)
{
if (base_type(reg->type) == PTR_TO_MAP_VALUE) {
const struct bpf_map *map = reg->map_ptr;
if (map->inner_map_meta) {
reg->type = CONST_PTR_TO_MAP;
reg->map_ptr = map->inner_map_meta;
/* transfer reg's id which is unique for every map_lookup_elem
* as UID of the inner map.
*/
if (btf_record_has_field(map->inner_map_meta->record, BPF_TIMER))
reg->map_uid = reg->id;
if (btf_record_has_field(map->inner_map_meta->record, BPF_WORKQUEUE))
reg->map_uid = reg->id;
} else if (map->map_type == BPF_MAP_TYPE_XSKMAP) {
reg->type = PTR_TO_XDP_SOCK;
} else if (map->map_type == BPF_MAP_TYPE_SOCKMAP ||
map->map_type == BPF_MAP_TYPE_SOCKHASH) {
reg->type = PTR_TO_SOCKET;
} else {
reg->type = PTR_TO_MAP_VALUE;
}
return;
}
reg->type &= ~PTR_MAYBE_NULL;
}
static void mark_reg_graph_node(struct bpf_reg_state *regs, u32 regno,
struct btf_field_graph_root *ds_head)
{
__mark_reg_known_zero(®s[regno]);
regs[regno].type = PTR_TO_BTF_ID | MEM_ALLOC;
regs[regno].btf = ds_head->btf;
regs[regno].btf_id = ds_head->value_btf_id;
regs[regno].off = ds_head->node_offset;
}
static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg)
{
return type_is_pkt_pointer(reg->type);
}
static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg)
{
return reg_is_pkt_pointer(reg) ||
reg->type == PTR_TO_PACKET_END;
}
static bool reg_is_dynptr_slice_pkt(const struct bpf_reg_state *reg)
{
return base_type(reg->type) == PTR_TO_MEM &&
(reg->type & DYNPTR_TYPE_SKB || reg->type & DYNPTR_TYPE_XDP);
}
/* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */
static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg,
enum bpf_reg_type which)
{
/* The register can already have a range from prior markings.
* This is fine as long as it hasn't been advanced from its
* origin.
*/
return reg->type == which &&
reg->id == 0 &&
reg->off == 0 &&
tnum_equals_const(reg->var_off, 0);
}
/* Reset the min/max bounds of a register */
static void __mark_reg_unbounded(struct bpf_reg_state *reg)
{
reg->smin_value = S64_MIN;
reg->smax_value = S64_MAX;
reg->umin_value = 0;
reg->umax_value = U64_MAX;
reg->s32_min_value = S32_MIN;
reg->s32_max_value = S32_MAX;
reg->u32_min_value = 0;
reg->u32_max_value = U32_MAX;
}
static void __mark_reg64_unbounded(struct bpf_reg_state *reg)
{
reg->smin_value = S64_MIN;
reg->smax_value = S64_MAX;
reg->umin_value = 0;
reg->umax_value = U64_MAX;
}
static void __mark_reg32_unbounded(struct bpf_reg_state *reg)
{
reg->s32_min_value = S32_MIN;
reg->s32_max_value = S32_MAX;
reg->u32_min_value = 0;
reg->u32_max_value = U32_MAX;
}
static void __update_reg32_bounds(struct bpf_reg_state *reg)
{
struct tnum var32_off = tnum_subreg(reg->var_off);
/* min signed is max(sign bit) | min(other bits) */
reg->s32_min_value = max_t(s32, reg->s32_min_value,
var32_off.value | (var32_off.mask & S32_MIN));
/* max signed is min(sign bit) | max(other bits) */
reg->s32_max_value = min_t(s32, reg->s32_max_value,
var32_off.value | (var32_off.mask & S32_MAX));
reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)var32_off.value);
reg->u32_max_value = min(reg->u32_max_value,
(u32)(var32_off.value | var32_off.mask));
}
static void __update_reg64_bounds(struct bpf_reg_state *reg)
{
/* min signed is max(sign bit) | min(other bits) */
reg->smin_value = max_t(s64, reg->smin_value,
reg->var_off.value | (reg->var_off.mask & S64_MIN));
/* max signed is min(sign bit) | max(other bits) */
reg->smax_value = min_t(s64, reg->smax_value,
reg->var_off.value | (reg->var_off.mask & S64_MAX));
reg->umin_value = max(reg->umin_value, reg->var_off.value);
reg->umax_value = min(reg->umax_value,
reg->var_off.value | reg->var_off.mask);
}
static void __update_reg_bounds(struct bpf_reg_state *reg)
{
__update_reg32_bounds(reg);
__update_reg64_bounds(reg);
}
/* Uses signed min/max values to inform unsigned, and vice-versa */
static void __reg32_deduce_bounds(struct bpf_reg_state *reg)
{
/* If upper 32 bits of u64/s64 range don't change, we can use lower 32
* bits to improve our u32/s32 boundaries.
*
* E.g., the case where we have upper 32 bits as zero ([10, 20] in
* u64) is pretty trivial, it's obvious that in u32 we'll also have
* [10, 20] range. But this property holds for any 64-bit range as
* long as upper 32 bits in that entire range of values stay the same.
*
* E.g., u64 range [0x10000000A, 0x10000000F] ([4294967306, 4294967311]
* in decimal) has the same upper 32 bits throughout all the values in
* that range. As such, lower 32 bits form a valid [0xA, 0xF] ([10, 15])
* range.
*
* Note also, that [0xA, 0xF] is a valid range both in u32 and in s32,
* following the rules outlined below about u64/s64 correspondence
* (which equally applies to u32 vs s32 correspondence). In general it
* depends on actual hexadecimal values of 32-bit range. They can form
* only valid u32, or only valid s32 ranges in some cases.
*
* So we use all these insights to derive bounds for subregisters here.
*/
if ((reg->umin_value >> 32) == (reg->umax_value >> 32)) {
/* u64 to u32 casting preserves validity of low 32 bits as
* a range, if upper 32 bits are the same
*/
reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)reg->umin_value);
reg->u32_max_value = min_t(u32, reg->u32_max_value, (u32)reg->umax_value);
if ((s32)reg->umin_value <= (s32)reg->umax_value) {
reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->umin_value);
reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->umax_value);
}
}
if ((reg->smin_value >> 32) == (reg->smax_value >> 32)) {
/* low 32 bits should form a proper u32 range */
if ((u32)reg->smin_value <= (u32)reg->smax_value) {
reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)reg->smin_value);
reg->u32_max_value = min_t(u32, reg->u32_max_value, (u32)reg->smax_value);
}
/* low 32 bits should form a proper s32 range */
if ((s32)reg->smin_value <= (s32)reg->smax_value) {
reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->smin_value);
reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->smax_value);
}
}
/* Special case where upper bits form a small sequence of two
* sequential numbers (in 32-bit unsigned space, so 0xffffffff to
* 0x00000000 is also valid), while lower bits form a proper s32 range
* going from negative numbers to positive numbers. E.g., let's say we
* have s64 range [-1, 1] ([0xffffffffffffffff, 0x0000000000000001]).
* Possible s64 values are {-1, 0, 1} ({0xffffffffffffffff,
* 0x0000000000000000, 0x00000000000001}). Ignoring upper 32 bits,
* we still get a valid s32 range [-1, 1] ([0xffffffff, 0x00000001]).
* Note that it doesn't have to be 0xffffffff going to 0x00000000 in
* upper 32 bits. As a random example, s64 range
* [0xfffffff0fffffff0; 0xfffffff100000010], forms a valid s32 range
* [-16, 16] ([0xfffffff0; 0x00000010]) in its 32 bit subregister.
*/
if ((u32)(reg->umin_value >> 32) + 1 == (u32)(reg->umax_value >> 32) &&
(s32)reg->umin_value < 0 && (s32)reg->umax_value >= 0) {
reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->umin_value);
reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->umax_value);
}
if ((u32)(reg->smin_value >> 32) + 1 == (u32)(reg->smax_value >> 32) &&
(s32)reg->smin_value < 0 && (s32)reg->smax_value >= 0) {
reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->smin_value);
reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->smax_value);
}
/* if u32 range forms a valid s32 range (due to matching sign bit),
* try to learn from that
*/
if ((s32)reg->u32_min_value <= (s32)reg->u32_max_value) {
reg->s32_min_value = max_t(s32, reg->s32_min_value, reg->u32_min_value);
reg->s32_max_value = min_t(s32, reg->s32_max_value, reg->u32_max_value);
}
/* If we cannot cross the sign boundary, then signed and unsigned bounds
* are the same, so combine. This works even in the negative case, e.g.
* -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
*/
if ((u32)reg->s32_min_value <= (u32)reg->s32_max_value) {
reg->u32_min_value = max_t(u32, reg->s32_min_value, reg->u32_min_value);
reg->u32_max_value = min_t(u32, reg->s32_max_value, reg->u32_max_value);
}
}
static void __reg64_deduce_bounds(struct bpf_reg_state *reg)
{
/* If u64 range forms a valid s64 range (due to matching sign bit),
* try to learn from that. Let's do a bit of ASCII art to see when
* this is happening. Let's take u64 range first:
*
* 0 0x7fffffffffffffff 0x8000000000000000 U64_MAX
* |-------------------------------|--------------------------------|
*
* Valid u64 range is formed when umin and umax are anywhere in the
* range [0, U64_MAX], and umin <= umax. u64 case is simple and
* straightforward. Let's see how s64 range maps onto the same range
* of values, annotated below the line for comparison:
*
* 0 0x7fffffffffffffff 0x8000000000000000 U64_MAX
* |-------------------------------|--------------------------------|
* 0 S64_MAX S64_MIN -1
*
* So s64 values basically start in the middle and they are logically
* contiguous to the right of it, wrapping around from -1 to 0, and
* then finishing as S64_MAX (0x7fffffffffffffff) right before
* S64_MIN. We can try drawing the continuity of u64 vs s64 values
* more visually as mapped to sign-agnostic range of hex values.
*
* u64 start u64 end
* _______________________________________________________________
* / \
* 0 0x7fffffffffffffff 0x8000000000000000 U64_MAX
* |-------------------------------|--------------------------------|
* 0 S64_MAX S64_MIN -1
* / \
* >------------------------------ ------------------------------->
* s64 continues... s64 end s64 start s64 "midpoint"
*
* What this means is that, in general, we can't always derive
* something new about u64 from any random s64 range, and vice versa.
*
* But we can do that in two particular cases. One is when entire
* u64/s64 range is *entirely* contained within left half of the above
* diagram or when it is *entirely* contained in the right half. I.e.:
*
* |-------------------------------|--------------------------------|
* ^ ^ ^ ^
* A B C D
*
* [A, B] and [C, D] are contained entirely in their respective halves
* and form valid contiguous ranges as both u64 and s64 values. [A, B]
* will be non-negative both as u64 and s64 (and in fact it will be
* identical ranges no matter the signedness). [C, D] treated as s64
* will be a range of negative values, while in u64 it will be
* non-negative range of values larger than 0x8000000000000000.
*
* Now, any other range here can't be represented in both u64 and s64
* simultaneously. E.g., [A, C], [A, D], [B, C], [B, D] are valid
* contiguous u64 ranges, but they are discontinuous in s64. [B, C]
* in s64 would be properly presented as [S64_MIN, C] and [B, S64_MAX],
* for example. Similarly, valid s64 range [D, A] (going from negative
* to positive values), would be two separate [D, U64_MAX] and [0, A]
* ranges as u64. Currently reg_state can't represent two segments per
* numeric domain, so in such situations we can only derive maximal
* possible range ([0, U64_MAX] for u64, and [S64_MIN, S64_MAX] for s64).
*
* So we use these facts to derive umin/umax from smin/smax and vice
* versa only if they stay within the same "half". This is equivalent
* to checking sign bit: lower half will have sign bit as zero, upper
* half have sign bit 1. Below in code we simplify this by just
* casting umin/umax as smin/smax and checking if they form valid
* range, and vice versa. Those are equivalent checks.
*/
if ((s64)reg->umin_value <= (s64)reg->umax_value) {
reg->smin_value = max_t(s64, reg->smin_value, reg->umin_value);
reg->smax_value = min_t(s64, reg->smax_value, reg->umax_value);
}
/* If we cannot cross the sign boundary, then signed and unsigned bounds
* are the same, so combine. This works even in the negative case, e.g.
* -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
*/
if ((u64)reg->smin_value <= (u64)reg->smax_value) {
reg->umin_value = max_t(u64, reg->smin_value, reg->umin_value);
reg->umax_value = min_t(u64, reg->smax_value, reg->umax_value);
}
}
static void __reg_deduce_mixed_bounds(struct bpf_reg_state *reg)
{
/* Try to tighten 64-bit bounds from 32-bit knowledge, using 32-bit
* values on both sides of 64-bit range in hope to have tighter range.
* E.g., if r1 is [0x1'00000000, 0x3'80000000], and we learn from
* 32-bit signed > 0 operation that s32 bounds are now [1; 0x7fffffff].
* With this, we can substitute 1 as low 32-bits of _low_ 64-bit bound
* (0x100000000 -> 0x100000001) and 0x7fffffff as low 32-bits of
* _high_ 64-bit bound (0x380000000 -> 0x37fffffff) and arrive at a
* better overall bounds for r1 as [0x1'000000001; 0x3'7fffffff].
* We just need to make sure that derived bounds we are intersecting
* with are well-formed ranges in respective s64 or u64 domain, just
* like we do with similar kinds of 32-to-64 or 64-to-32 adjustments.
*/
__u64 new_umin, new_umax;
__s64 new_smin, new_smax;
/* u32 -> u64 tightening, it's always well-formed */
new_umin = (reg->umin_value & ~0xffffffffULL) | reg->u32_min_value;
new_umax = (reg->umax_value & ~0xffffffffULL) | reg->u32_max_value;
reg->umin_value = max_t(u64, reg->umin_value, new_umin);
reg->umax_value = min_t(u64, reg->umax_value, new_umax);
/* u32 -> s64 tightening, u32 range embedded into s64 preserves range validity */
new_smin = (reg->smin_value & ~0xffffffffULL) | reg->u32_min_value;
new_smax = (reg->smax_value & ~0xffffffffULL) | reg->u32_max_value;
reg->smin_value = max_t(s64, reg->smin_value, new_smin);
reg->smax_value = min_t(s64, reg->smax_value, new_smax);
/* if s32 can be treated as valid u32 range, we can use it as well */
if ((u32)reg->s32_min_value <= (u32)reg->s32_max_value) {
/* s32 -> u64 tightening */
new_umin = (reg->umin_value & ~0xffffffffULL) | (u32)reg->s32_min_value;
new_umax = (reg->umax_value & ~0xffffffffULL) | (u32)reg->s32_max_value;
reg->umin_value = max_t(u64, reg->umin_value, new_umin);
reg->umax_value = min_t(u64, reg->umax_value, new_umax);
/* s32 -> s64 tightening */
new_smin = (reg->smin_value & ~0xffffffffULL) | (u32)reg->s32_min_value;
new_smax = (reg->smax_value & ~0xffffffffULL) | (u32)reg->s32_max_value;
reg->smin_value = max_t(s64, reg->smin_value, new_smin);
reg->smax_value = min_t(s64, reg->smax_value, new_smax);
}
/* Here we would like to handle a special case after sign extending load,
* when upper bits for a 64-bit range are all 1s or all 0s.
*
* Upper bits are all 1s when register is in a range:
* [0xffff_ffff_0000_0000, 0xffff_ffff_ffff_ffff]
* Upper bits are all 0s when register is in a range:
* [0x0000_0000_0000_0000, 0x0000_0000_ffff_ffff]
* Together this forms are continuous range:
* [0xffff_ffff_0000_0000, 0x0000_0000_ffff_ffff]
*
* Now, suppose that register range is in fact tighter:
* [0xffff_ffff_8000_0000, 0x0000_0000_ffff_ffff] (R)
* Also suppose that it's 32-bit range is positive,
* meaning that lower 32-bits of the full 64-bit register
* are in the range:
* [0x0000_0000, 0x7fff_ffff] (W)
*
* If this happens, then any value in a range:
* [0xffff_ffff_0000_0000, 0xffff_ffff_7fff_ffff]
* is smaller than a lowest bound of the range (R):
* 0xffff_ffff_8000_0000
* which means that upper bits of the full 64-bit register
* can't be all 1s, when lower bits are in range (W).
*
* Note that:
* - 0xffff_ffff_8000_0000 == (s64)S32_MIN
* - 0x0000_0000_7fff_ffff == (s64)S32_MAX
* These relations are used in the conditions below.
*/
if (reg->s32_min_value >= 0 && reg->smin_value >= S32_MIN && reg->smax_value <= S32_MAX) {
reg->smin_value = reg->s32_min_value;
reg->smax_value = reg->s32_max_value;
reg->umin_value = reg->s32_min_value;
reg->umax_value = reg->s32_max_value;
reg->var_off = tnum_intersect(reg->var_off,
tnum_range(reg->smin_value, reg->smax_value));
}
}
static void __reg_deduce_bounds(struct bpf_reg_state *reg)
{
__reg32_deduce_bounds(reg);
__reg64_deduce_bounds(reg);
__reg_deduce_mixed_bounds(reg);
}
/* Attempts to improve var_off based on unsigned min/max information */
static void __reg_bound_offset(struct bpf_reg_state *reg)
{
struct tnum var64_off = tnum_intersect(reg->var_off,
tnum_range(reg->umin_value,
reg->umax_value));
struct tnum var32_off = tnum_intersect(tnum_subreg(var64_off),
tnum_range(reg->u32_min_value,
reg->u32_max_value));
reg->var_off = tnum_or(tnum_clear_subreg(var64_off), var32_off);
}
static void reg_bounds_sync(struct bpf_reg_state *reg)
{
/* We might have learned new bounds from the var_off. */
__update_reg_bounds(reg);
/* We might have learned something about the sign bit. */
__reg_deduce_bounds(reg);
__reg_deduce_bounds(reg);
/* We might have learned some bits from the bounds. */
__reg_bound_offset(reg);
/* Intersecting with the old var_off might have improved our bounds
* slightly, e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
* then new var_off is (0; 0x7f...fc) which improves our umax.
*/
__update_reg_bounds(reg);
}
static int reg_bounds_sanity_check(struct bpf_verifier_env *env,
struct bpf_reg_state *reg, const char *ctx)
{
const char *msg;
if (reg->umin_value > reg->umax_value ||
reg->smin_value > reg->smax_value ||
reg->u32_min_value > reg->u32_max_value ||
reg->s32_min_value > reg->s32_max_value) {
msg = "range bounds violation";
goto out;
}
if (tnum_is_const(reg->var_off)) {
u64 uval = reg->var_off.value;
s64 sval = (s64)uval;
if (reg->umin_value != uval || reg->umax_value != uval ||
reg->smin_value != sval || reg->smax_value != sval) {
msg = "const tnum out of sync with range bounds";
goto out;
}
}
if (tnum_subreg_is_const(reg->var_off)) {
u32 uval32 = tnum_subreg(reg->var_off).value;
s32 sval32 = (s32)uval32;
if (reg->u32_min_value != uval32 || reg->u32_max_value != uval32 ||
reg->s32_min_value != sval32 || reg->s32_max_value != sval32) {
msg = "const subreg tnum out of sync with range bounds";
goto out;
}
}
return 0;
out:
verbose(env, "REG INVARIANTS VIOLATION (%s): %s u64=[%#llx, %#llx] "
"s64=[%#llx, %#llx] u32=[%#x, %#x] s32=[%#x, %#x] var_off=(%#llx, %#llx)\n",
ctx, msg, reg->umin_value, reg->umax_value,
reg->smin_value, reg->smax_value,
reg->u32_min_value, reg->u32_max_value,
reg->s32_min_value, reg->s32_max_value,
reg->var_off.value, reg->var_off.mask);
if (env->test_reg_invariants)
return -EFAULT;
__mark_reg_unbounded(reg);
return 0;
}
static bool __reg32_bound_s64(s32 a)
{
return a >= 0 && a <= S32_MAX;
}
static void __reg_assign_32_into_64(struct bpf_reg_state *reg)
{
reg->umin_value = reg->u32_min_value;
reg->umax_value = reg->u32_max_value;
/* Attempt to pull 32-bit signed bounds into 64-bit bounds but must
* be positive otherwise set to worse case bounds and refine later
* from tnum.
*/
if (__reg32_bound_s64(reg->s32_min_value) &&
__reg32_bound_s64(reg->s32_max_value)) {
reg->smin_value = reg->s32_min_value;
reg->smax_value = reg->s32_max_value;
} else {
reg->smin_value = 0;
reg->smax_value = U32_MAX;
}
}
/* Mark a register as having a completely unknown (scalar) value. */
static void __mark_reg_unknown_imprecise(struct bpf_reg_state *reg)
{
/*
* Clear type, off, and union(map_ptr, range) and
* padding between 'type' and union
*/
memset(reg, 0, offsetof(struct bpf_reg_state, var_off));
reg->type = SCALAR_VALUE;
reg->id = 0;
reg->ref_obj_id = 0;
reg->var_off = tnum_unknown;
reg->frameno = 0;
reg->precise = false;
__mark_reg_unbounded(reg);
}
/* Mark a register as having a completely unknown (scalar) value,
* initialize .precise as true when not bpf capable.
*/
static void __mark_reg_unknown(const struct bpf_verifier_env *env,
struct bpf_reg_state *reg)
{
__mark_reg_unknown_imprecise(reg);
reg->precise = !env->bpf_capable;
}
static void mark_reg_unknown(struct bpf_verifier_env *env,
struct bpf_reg_state *regs, u32 regno)
{
if (WARN_ON(regno >= MAX_BPF_REG)) {
verbose(env, "mark_reg_unknown(regs, %u)\n", regno);
/* Something bad happened, let's kill all regs except FP */
for (regno = 0; regno < BPF_REG_FP; regno++)
__mark_reg_not_init(env, regs + regno);
return;
}
__mark_reg_unknown(env, regs + regno);
}
static int __mark_reg_s32_range(struct bpf_verifier_env *env,
struct bpf_reg_state *regs,
u32 regno,
s32 s32_min,
s32 s32_max)
{
struct bpf_reg_state *reg = regs + regno;
reg->s32_min_value = max_t(s32, reg->s32_min_value, s32_min);
reg->s32_max_value = min_t(s32, reg->s32_max_value, s32_max);
reg->smin_value = max_t(s64, reg->smin_value, s32_min);
reg->smax_value = min_t(s64, reg->smax_value, s32_max);
reg_bounds_sync(reg);
return reg_bounds_sanity_check(env, reg, "s32_range");
}
static void __mark_reg_not_init(const struct bpf_verifier_env *env,
struct bpf_reg_state *reg)
{
__mark_reg_unknown(env, reg);
reg->type = NOT_INIT;
}
static void mark_reg_not_init(struct bpf_verifier_env *env,
struct bpf_reg_state *regs, u32 regno)
{
if (WARN_ON(regno >= MAX_BPF_REG)) {
verbose(env, "mark_reg_not_init(regs, %u)\n", regno);
/* Something bad happened, let's kill all regs except FP */
for (regno = 0; regno < BPF_REG_FP; regno++)
__mark_reg_not_init(env, regs + regno);
return;
}
__mark_reg_not_init(env, regs + regno);
}
static void mark_btf_ld_reg(struct bpf_verifier_env *env,
struct bpf_reg_state *regs, u32 regno,
enum bpf_reg_type reg_type,
struct btf *btf, u32 btf_id,
enum bpf_type_flag flag)
{
if (reg_type == SCALAR_VALUE) {
mark_reg_unknown(env, regs, regno);
return;
}
mark_reg_known_zero(env, regs, regno);
regs[regno].type = PTR_TO_BTF_ID | flag;
regs[regno].btf = btf;
regs[regno].btf_id = btf_id;
if (type_may_be_null(flag))
regs[regno].id = ++env->id_gen;
}
#define DEF_NOT_SUBREG (0)
static void init_reg_state(struct bpf_verifier_env *env,
struct bpf_func_state *state)
{
struct bpf_reg_state *regs = state->regs;
int i;
for (i = 0; i < MAX_BPF_REG; i++) {
mark_reg_not_init(env, regs, i);
regs[i].live = REG_LIVE_NONE;
regs[i].parent = NULL;
regs[i].subreg_def = DEF_NOT_SUBREG;
}
/* frame pointer */
regs[BPF_REG_FP].type = PTR_TO_STACK;
mark_reg_known_zero(env, regs, BPF_REG_FP);
regs[BPF_REG_FP].frameno = state->frameno;
}
static struct bpf_retval_range retval_range(s32 minval, s32 maxval)
{
return (struct bpf_retval_range){ minval, maxval };
}
#define BPF_MAIN_FUNC (-1)
static void init_func_state(struct bpf_verifier_env *env,
struct bpf_func_state *state,
int callsite, int frameno, int subprogno)
{
state->callsite = callsite;
state->frameno = frameno;
state->subprogno = subprogno;
state->callback_ret_range = retval_range(0, 0);
init_reg_state(env, state);
mark_verifier_state_scratched(env);
}
/* Similar to push_stack(), but for async callbacks */
static struct bpf_verifier_state *push_async_cb(struct bpf_verifier_env *env,
int insn_idx, int prev_insn_idx,
int subprog, bool is_sleepable)
{
struct bpf_verifier_stack_elem *elem;
struct bpf_func_state *frame;
elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
if (!elem)
goto err;
elem->insn_idx = insn_idx;
elem->prev_insn_idx = prev_insn_idx;
elem->next = env->head;
elem->log_pos = env->log.end_pos;
env->head = elem;
env->stack_size++;
if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
verbose(env,
"The sequence of %d jumps is too complex for async cb.\n",
env->stack_size);
goto err;
}
/* Unlike push_stack() do not copy_verifier_state().
* The caller state doesn't matter.
* This is async callback. It starts in a fresh stack.
* Initialize it similar to do_check_common().
*/
elem->st.branches = 1;
elem->st.in_sleepable = is_sleepable;
frame = kzalloc(sizeof(*frame), GFP_KERNEL);
if (!frame)
goto err;
init_func_state(env, frame,
BPF_MAIN_FUNC /* callsite */,
0 /* frameno within this callchain */,
subprog /* subprog number within this prog */);
elem->st.frame[0] = frame;
return &elem->st;
err:
free_verifier_state(env->cur_state, true);
env->cur_state = NULL;
/* pop all elements and return */
while (!pop_stack(env, NULL, NULL, false));
return NULL;
}
enum reg_arg_type {
SRC_OP, /* register is used as source operand */
DST_OP, /* register is used as destination operand */
DST_OP_NO_MARK /* same as above, check only, don't mark */
};
static int cmp_subprogs(const void *a, const void *b)
{
return ((struct bpf_subprog_info *)a)->start -
((struct bpf_subprog_info *)b)->start;
}
static int find_subprog(struct bpf_verifier_env *env, int off)
{
struct bpf_subprog_info *p;
p = bsearch(&off, env->subprog_info, env->subprog_cnt,
sizeof(env->subprog_info[0]), cmp_subprogs);
if (!p)
return -ENOENT;
return p - env->subprog_info;
}
static int add_subprog(struct bpf_verifier_env *env, int off)
{
int insn_cnt = env->prog->len;
int ret;
if (off >= insn_cnt || off < 0) {
verbose(env, "call to invalid destination\n");
return -EINVAL;
}
ret = find_subprog(env, off);
if (ret >= 0)
return ret;
if (env->subprog_cnt >= BPF_MAX_SUBPROGS) {
verbose(env, "too many subprograms\n");
return -E2BIG;
}
/* determine subprog starts. The end is one before the next starts */
env->subprog_info[env->subprog_cnt++].start = off;
sort(env->subprog_info, env->subprog_cnt,
sizeof(env->subprog_info[0]), cmp_subprogs, NULL);
return env->subprog_cnt - 1;
}
static int bpf_find_exception_callback_insn_off(struct bpf_verifier_env *env)
{
struct bpf_prog_aux *aux = env->prog->aux;
struct btf *btf = aux->btf;
const struct btf_type *t;
u32 main_btf_id, id;
const char *name;
int ret, i;
/* Non-zero func_info_cnt implies valid btf */
if (!aux->func_info_cnt)
return 0;
main_btf_id = aux->func_info[0].type_id;
t = btf_type_by_id(btf, main_btf_id);
if (!t) {
verbose(env, "invalid btf id for main subprog in func_info\n");
return -EINVAL;
}
name = btf_find_decl_tag_value(btf, t, -1, "exception_callback:");
if (IS_ERR(name)) {
ret = PTR_ERR(name);
/* If there is no tag present, there is no exception callback */
if (ret == -ENOENT)
ret = 0;
else if (ret == -EEXIST)
verbose(env, "multiple exception callback tags for main subprog\n");
return ret;
}
ret = btf_find_by_name_kind(btf, name, BTF_KIND_FUNC);
if (ret < 0) {
verbose(env, "exception callback '%s' could not be found in BTF\n", name);
return ret;
}
id = ret;
t = btf_type_by_id(btf, id);
if (btf_func_linkage(t) != BTF_FUNC_GLOBAL) {
verbose(env, "exception callback '%s' must have global linkage\n", name);
return -EINVAL;
}
ret = 0;
for (i = 0; i < aux->func_info_cnt; i++) {
if (aux->func_info[i].type_id != id)
continue;
ret = aux->func_info[i].insn_off;
/* Further func_info and subprog checks will also happen
* later, so assume this is the right insn_off for now.
*/
if (!ret) {
verbose(env, "invalid exception callback insn_off in func_info: 0\n");
ret = -EINVAL;
}
}
if (!ret) {
verbose(env, "exception callback type id not found in func_info\n");
ret = -EINVAL;
}
return ret;
}
#define MAX_KFUNC_DESCS 256
#define MAX_KFUNC_BTFS 256
struct bpf_kfunc_desc {
struct btf_func_model func_model;
u32 func_id;
s32 imm;
u16 offset;
unsigned long addr;
};
struct bpf_kfunc_btf {
struct btf *btf;
struct module *module;
u16 offset;
};
struct bpf_kfunc_desc_tab {
/* Sorted by func_id (BTF ID) and offset (fd_array offset) during
* verification. JITs do lookups by bpf_insn, where func_id may not be
* available, therefore at the end of verification do_misc_fixups()
* sorts this by imm and offset.
*/
struct bpf_kfunc_desc descs[MAX_KFUNC_DESCS];
u32 nr_descs;
};
struct bpf_kfunc_btf_tab {
struct bpf_kfunc_btf descs[MAX_KFUNC_BTFS];
u32 nr_descs;
};
static int kfunc_desc_cmp_by_id_off(const void *a, const void *b)
{
const struct bpf_kfunc_desc *d0 = a;
const struct bpf_kfunc_desc *d1 = b;
/* func_id is not greater than BTF_MAX_TYPE */
return d0->func_id - d1->func_id ?: d0->offset - d1->offset;
}
static int kfunc_btf_cmp_by_off(const void *a, const void *b)
{
const struct bpf_kfunc_btf *d0 = a;
const struct bpf_kfunc_btf *d1 = b;
return d0->offset - d1->offset;
}
static const struct bpf_kfunc_desc *
find_kfunc_desc(const struct bpf_prog *prog, u32 func_id, u16 offset)
{
struct bpf_kfunc_desc desc = {
.func_id = func_id,
.offset = offset,
};
struct bpf_kfunc_desc_tab *tab;
tab = prog->aux->kfunc_tab;
return bsearch(&desc, tab->descs, tab->nr_descs,
sizeof(tab->descs[0]), kfunc_desc_cmp_by_id_off);
}
int bpf_get_kfunc_addr(const struct bpf_prog *prog, u32 func_id,
u16 btf_fd_idx, u8 **func_addr)
{
const struct bpf_kfunc_desc *desc;
desc = find_kfunc_desc(prog, func_id, btf_fd_idx);
if (!desc)
return -EFAULT;
*func_addr = (u8 *)desc->addr;
return 0;
}
static struct btf *__find_kfunc_desc_btf(struct bpf_verifier_env *env,
s16 offset)
{
struct bpf_kfunc_btf kf_btf = { .offset = offset };
struct bpf_kfunc_btf_tab *tab;
struct bpf_kfunc_btf *b;
struct module *mod;
struct btf *btf;
int btf_fd;
tab = env->prog->aux->kfunc_btf_tab;
b = bsearch(&kf_btf, tab->descs, tab->nr_descs,
sizeof(tab->descs[0]), kfunc_btf_cmp_by_off);
if (!b) {
if (tab->nr_descs == MAX_KFUNC_BTFS) {
verbose(env, "too many different module BTFs\n");
return ERR_PTR(-E2BIG);
}
if (bpfptr_is_null(env->fd_array)) {
verbose(env, "kfunc offset > 0 without fd_array is invalid\n");
return ERR_PTR(-EPROTO);
}
if (copy_from_bpfptr_offset(&btf_fd, env->fd_array,
offset * sizeof(btf_fd),
sizeof(btf_fd)))
return ERR_PTR(-EFAULT);
btf = btf_get_by_fd(btf_fd);
if (IS_ERR(btf)) {
verbose(env, "invalid module BTF fd specified\n");
return btf;
}
if (!btf_is_module(btf)) {
verbose(env, "BTF fd for kfunc is not a module BTF\n");
btf_put(btf);
return ERR_PTR(-EINVAL);
}
mod = btf_try_get_module(btf);
if (!mod) {
btf_put(btf);
return ERR_PTR(-ENXIO);
}
b = &tab->descs[tab->nr_descs++];
b->btf = btf;
b->module = mod;
b->offset = offset;
sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
kfunc_btf_cmp_by_off, NULL);
}
return b->btf;
}
void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab)
{
if (!tab)
return;
while (tab->nr_descs--) {
module_put(tab->descs[tab->nr_descs].module);
btf_put(tab->descs[tab->nr_descs].btf);
}
kfree(tab);
}
static struct btf *find_kfunc_desc_btf(struct bpf_verifier_env *env, s16 offset)
{
if (offset) {
if (offset < 0) {
/* In the future, this can be allowed to increase limit
* of fd index into fd_array, interpreted as u16.
*/
verbose(env, "negative offset disallowed for kernel module function call\n");
return ERR_PTR(-EINVAL);
}
return __find_kfunc_desc_btf(env, offset);
}
return btf_vmlinux ?: ERR_PTR(-ENOENT);
}
static int add_kfunc_call(struct bpf_verifier_env *env, u32 func_id, s16 offset)
{
const struct btf_type *func, *func_proto;
struct bpf_kfunc_btf_tab *btf_tab;
struct bpf_kfunc_desc_tab *tab;
struct bpf_prog_aux *prog_aux;
struct bpf_kfunc_desc *desc;
const char *func_name;
struct btf *desc_btf;
unsigned long call_imm;
unsigned long addr;
int err;
prog_aux = env->prog->aux;
tab = prog_aux->kfunc_tab;
btf_tab = prog_aux->kfunc_btf_tab;
if (!tab) {
if (!btf_vmlinux) {
verbose(env, "calling kernel function is not supported without CONFIG_DEBUG_INFO_BTF\n");
return -ENOTSUPP;
}
if (!env->prog->jit_requested) {
verbose(env, "JIT is required for calling kernel function\n");
return -ENOTSUPP;
}
if (!bpf_jit_supports_kfunc_call()) {
verbose(env, "JIT does not support calling kernel function\n");
return -ENOTSUPP;
}
if (!env->prog->gpl_compatible) {
verbose(env, "cannot call kernel function from non-GPL compatible program\n");
return -EINVAL;
}
tab = kzalloc(sizeof(*tab), GFP_KERNEL);
if (!tab)
return -ENOMEM;
prog_aux->kfunc_tab = tab;
}
/* func_id == 0 is always invalid, but instead of returning an error, be
* conservative and wait until the code elimination pass before returning
* error, so that invalid calls that get pruned out can be in BPF programs
* loaded from userspace. It is also required that offset be untouched
* for such calls.
*/
if (!func_id && !offset)
return 0;
if (!btf_tab && offset) {
btf_tab = kzalloc(sizeof(*btf_tab), GFP_KERNEL);
if (!btf_tab)
return -ENOMEM;
prog_aux->kfunc_btf_tab = btf_tab;
}
desc_btf = find_kfunc_desc_btf(env, offset);
if (IS_ERR(desc_btf)) {
verbose(env, "failed to find BTF for kernel function\n");
return PTR_ERR(desc_btf);
}
if (find_kfunc_desc(env->prog, func_id, offset))
return 0;
if (tab->nr_descs == MAX_KFUNC_DESCS) {
verbose(env, "too many different kernel function calls\n");
return -E2BIG;
}
func = btf_type_by_id(desc_btf, func_id);
if (!func || !btf_type_is_func(func)) {
verbose(env, "kernel btf_id %u is not a function\n",
func_id);
return -EINVAL;
}
func_proto = btf_type_by_id(desc_btf, func->type);
if (!func_proto || !btf_type_is_func_proto(func_proto)) {
verbose(env, "kernel function btf_id %u does not have a valid func_proto\n",
func_id);
return -EINVAL;
}
func_name = btf_name_by_offset(desc_btf, func->name_off);
addr = kallsyms_lookup_name(func_name);
if (!addr) {
verbose(env, "cannot find address for kernel function %s\n",
func_name);
return -EINVAL;
}
specialize_kfunc(env, func_id, offset, &addr);
if (bpf_jit_supports_far_kfunc_call()) {
call_imm = func_id;
} else {
call_imm = BPF_CALL_IMM(addr);
/* Check whether the relative offset overflows desc->imm */
if ((unsigned long)(s32)call_imm != call_imm) {
verbose(env, "address of kernel function %s is out of range\n",
func_name);
return -EINVAL;
}
}
if (bpf_dev_bound_kfunc_id(func_id)) {
err = bpf_dev_bound_kfunc_check(&env->log, prog_aux);
if (err)
return err;
}
desc = &tab->descs[tab->nr_descs++];
desc->func_id = func_id;
desc->imm = call_imm;
desc->offset = offset;
desc->addr = addr;
err = btf_distill_func_proto(&env->log, desc_btf,
func_proto, func_name,
&desc->func_model);
if (!err)
sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
kfunc_desc_cmp_by_id_off, NULL);
return err;
}
static int kfunc_desc_cmp_by_imm_off(const void *a, const void *b)
{
const struct bpf_kfunc_desc *d0 = a;
const struct bpf_kfunc_desc *d1 = b;
if (d0->imm != d1->imm)
return d0->imm < d1->imm ? -1 : 1;
if (d0->offset != d1->offset)
return d0->offset < d1->offset ? -1 : 1;
return 0;
}
static void sort_kfunc_descs_by_imm_off(struct bpf_prog *prog)
{
struct bpf_kfunc_desc_tab *tab;
tab = prog->aux->kfunc_tab;
if (!tab)
return;
sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
kfunc_desc_cmp_by_imm_off, NULL);
}
bool bpf_prog_has_kfunc_call(const struct bpf_prog *prog)
{
return !!prog->aux->kfunc_tab;
}
const struct btf_func_model *
bpf_jit_find_kfunc_model(const struct bpf_prog *prog,
const struct bpf_insn *insn)
{
const struct bpf_kfunc_desc desc = {
.imm = insn->imm,
.offset = insn->off,
};
const struct bpf_kfunc_desc *res;
struct bpf_kfunc_desc_tab *tab;
tab = prog->aux->kfunc_tab;
res = bsearch(&desc, tab->descs, tab->nr_descs,
sizeof(tab->descs[0]), kfunc_desc_cmp_by_imm_off);
return res ? &res->func_model : NULL;
}
static int add_subprog_and_kfunc(struct bpf_verifier_env *env)
{
struct bpf_subprog_info *subprog = env->subprog_info;
int i, ret, insn_cnt = env->prog->len, ex_cb_insn;
struct bpf_insn *insn = env->prog->insnsi;
/* Add entry function. */
ret = add_subprog(env, 0);
if (ret)
return ret;
for (i = 0; i < insn_cnt; i++, insn++) {
if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn) &&
!bpf_pseudo_kfunc_call(insn))
continue;
if (!env->bpf_capable) {
verbose(env, "loading/calling other bpf or kernel functions are allowed for CAP_BPF and CAP_SYS_ADMIN\n");
return -EPERM;
}
if (bpf_pseudo_func(insn) || bpf_pseudo_call(insn))
ret = add_subprog(env, i + insn->imm + 1);
else
ret = add_kfunc_call(env, insn->imm, insn->off);
if (ret < 0)
return ret;
}
ret = bpf_find_exception_callback_insn_off(env);
if (ret < 0)
return ret;
ex_cb_insn = ret;
/* If ex_cb_insn > 0, this means that the main program has a subprog
* marked using BTF decl tag to serve as the exception callback.
*/
if (ex_cb_insn) {
ret = add_subprog(env, ex_cb_insn);
if (ret < 0)
return ret;
for (i = 1; i < env->subprog_cnt; i++) {
if (env->subprog_info[i].start != ex_cb_insn)
continue;
env->exception_callback_subprog = i;
mark_subprog_exc_cb(env, i);
break;
}
}
/* Add a fake 'exit' subprog which could simplify subprog iteration
* logic. 'subprog_cnt' should not be increased.
*/
subprog[env->subprog_cnt].start = insn_cnt;
if (env->log.level & BPF_LOG_LEVEL2)
for (i = 0; i < env->subprog_cnt; i++)
verbose(env, "func#%d @%d\n", i, subprog[i].start);
return 0;
}
static int check_subprogs(struct bpf_verifier_env *env)
{
int i, subprog_start, subprog_end, off, cur_subprog = 0;
struct bpf_subprog_info *subprog = env->subprog_info;
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
/* now check that all jumps are within the same subprog */
subprog_start = subprog[cur_subprog].start;
subprog_end = subprog[cur_subprog + 1].start;
for (i = 0; i < insn_cnt; i++) {
u8 code = insn[i].code;
if (code == (BPF_JMP | BPF_CALL) &&
insn[i].src_reg == 0 &&
insn[i].imm == BPF_FUNC_tail_call) {
subprog[cur_subprog].has_tail_call = true;
subprog[cur_subprog].tail_call_reachable = true;
}
if (BPF_CLASS(code) == BPF_LD &&
(BPF_MODE(code) == BPF_ABS || BPF_MODE(code) == BPF_IND))
subprog[cur_subprog].has_ld_abs = true;
if (BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32)
goto next;
if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL)
goto next;
if (code == (BPF_JMP32 | BPF_JA))
off = i + insn[i].imm + 1;
else
off = i + insn[i].off + 1;
if (off < subprog_start || off >= subprog_end) {
verbose(env, "jump out of range from insn %d to %d\n", i, off);
return -EINVAL;
}
next:
if (i == subprog_end - 1) {
/* to avoid fall-through from one subprog into another
* the last insn of the subprog should be either exit
* or unconditional jump back or bpf_throw call
*/
if (code != (BPF_JMP | BPF_EXIT) &&
code != (BPF_JMP32 | BPF_JA) &&
code != (BPF_JMP | BPF_JA)) {
verbose(env, "last insn is not an exit or jmp\n");
return -EINVAL;
}
subprog_start = subprog_end;
cur_subprog++;
if (cur_subprog < env->subprog_cnt)
subprog_end = subprog[cur_subprog + 1].start;
}
}
return 0;
}
/* Parentage chain of this register (or stack slot) should take care of all
* issues like callee-saved registers, stack slot allocation time, etc.
*/
static int mark_reg_read(struct bpf_verifier_env *env,
const struct bpf_reg_state *state,
struct bpf_reg_state *parent, u8 flag)
{
bool writes = parent == state->parent; /* Observe write marks */
int cnt = 0;
while (parent) {
/* if read wasn't screened by an earlier write ... */
if (writes && state->live & REG_LIVE_WRITTEN)
break;
if (parent->live & REG_LIVE_DONE) {
verbose(env, "verifier BUG type %s var_off %lld off %d\n",
reg_type_str(env, parent->type),
parent->var_off.value, parent->off);
return -EFAULT;
}
/* The first condition is more likely to be true than the
* second, checked it first.
*/
if ((parent->live & REG_LIVE_READ) == flag ||
parent->live & REG_LIVE_READ64)
/* The parentage chain never changes and
* this parent was already marked as LIVE_READ.
* There is no need to keep walking the chain again and
* keep re-marking all parents as LIVE_READ.
* This case happens when the same register is read
* multiple times without writes into it in-between.
* Also, if parent has the stronger REG_LIVE_READ64 set,
* then no need to set the weak REG_LIVE_READ32.
*/
break;
/* ... then we depend on parent's value */
parent->live |= flag;
/* REG_LIVE_READ64 overrides REG_LIVE_READ32. */
if (flag == REG_LIVE_READ64)
parent->live &= ~REG_LIVE_READ32;
state = parent;
parent = state->parent;
writes = true;
cnt++;
}
if (env->longest_mark_read_walk < cnt)
env->longest_mark_read_walk = cnt;
return 0;
}
static int mark_dynptr_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
struct bpf_func_state *state = func(env, reg);
int spi, ret;
/* For CONST_PTR_TO_DYNPTR, it must have already been done by
* check_reg_arg in check_helper_call and mark_btf_func_reg_size in
* check_kfunc_call.
*/
if (reg->type == CONST_PTR_TO_DYNPTR)
return 0;
spi = dynptr_get_spi(env, reg);
if (spi < 0)
return spi;
/* Caller ensures dynptr is valid and initialized, which means spi is in
* bounds and spi is the first dynptr slot. Simply mark stack slot as
* read.
*/
ret = mark_reg_read(env, &state->stack[spi].spilled_ptr,
state->stack[spi].spilled_ptr.parent, REG_LIVE_READ64);
if (ret)
return ret;
return mark_reg_read(env, &state->stack[spi - 1].spilled_ptr,
state->stack[spi - 1].spilled_ptr.parent, REG_LIVE_READ64);
}
static int mark_iter_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
int spi, int nr_slots)
{
struct bpf_func_state *state = func(env, reg);
int err, i;
for (i = 0; i < nr_slots; i++) {
struct bpf_reg_state *st = &state->stack[spi - i].spilled_ptr;
err = mark_reg_read(env, st, st->parent, REG_LIVE_READ64);
if (err)
return err;
mark_stack_slot_scratched(env, spi - i);
}
return 0;
}
/* This function is supposed to be used by the following 32-bit optimization
* code only. It returns TRUE if the source or destination register operates
* on 64-bit, otherwise return FALSE.
*/
static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn,
u32 regno, struct bpf_reg_state *reg, enum reg_arg_type t)
{
u8 code, class, op;
code = insn->code;
class = BPF_CLASS(code);
op = BPF_OP(code);
if (class == BPF_JMP) {
/* BPF_EXIT for "main" will reach here. Return TRUE
* conservatively.
*/
if (op == BPF_EXIT)
return true;
if (op == BPF_CALL) {
/* BPF to BPF call will reach here because of marking
* caller saved clobber with DST_OP_NO_MARK for which we
* don't care the register def because they are anyway
* marked as NOT_INIT already.
*/
if (insn->src_reg == BPF_PSEUDO_CALL)
return false;
/* Helper call will reach here because of arg type
* check, conservatively return TRUE.
*/
if (t == SRC_OP)
return true;
return false;
}
}
if (class == BPF_ALU64 && op == BPF_END && (insn->imm == 16 || insn->imm == 32))
return false;
if (class == BPF_ALU64 || class == BPF_JMP ||
(class == BPF_ALU && op == BPF_END && insn->imm == 64))
return true;
if (class == BPF_ALU || class == BPF_JMP32)
return false;
if (class == BPF_LDX) {
if (t != SRC_OP)
return BPF_SIZE(code) == BPF_DW || BPF_MODE(code) == BPF_MEMSX;
/* LDX source must be ptr. */
return true;
}
if (class == BPF_STX) {
/* BPF_STX (including atomic variants) has multiple source
* operands, one of which is a ptr. Check whether the caller is
* asking about it.
*/
if (t == SRC_OP && reg->type != SCALAR_VALUE)
return true;
return BPF_SIZE(code) == BPF_DW;
}
if (class == BPF_LD) {
u8 mode = BPF_MODE(code);
/* LD_IMM64 */
if (mode == BPF_IMM)
return true;
/* Both LD_IND and LD_ABS return 32-bit data. */
if (t != SRC_OP)
return false;
/* Implicit ctx ptr. */
if (regno == BPF_REG_6)
return true;
/* Explicit source could be any width. */
return true;
}
if (class == BPF_ST)
/* The only source register for BPF_ST is a ptr. */
return true;
/* Conservatively return true at default. */
return true;
}
/* Return the regno defined by the insn, or -1. */
static int insn_def_regno(const struct bpf_insn *insn)
{
switch (BPF_CLASS(insn->code)) {
case BPF_JMP:
case BPF_JMP32:
case BPF_ST:
return -1;
case BPF_STX:
if ((BPF_MODE(insn->code) == BPF_ATOMIC ||
BPF_MODE(insn->code) == BPF_PROBE_ATOMIC) &&
(insn->imm & BPF_FETCH)) {
if (insn->imm == BPF_CMPXCHG)
return BPF_REG_0;
else
return insn->src_reg;
} else {
return -1;
}
default:
return insn->dst_reg;
}
}
/* Return TRUE if INSN has defined any 32-bit value explicitly. */
static bool insn_has_def32(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
int dst_reg = insn_def_regno(insn);
if (dst_reg == -1)
return false;
return !is_reg64(env, insn, dst_reg, NULL, DST_OP);
}
static void mark_insn_zext(struct bpf_verifier_env *env,
struct bpf_reg_state *reg)
{
s32 def_idx = reg->subreg_def;
if (def_idx == DEF_NOT_SUBREG)
return;
env->insn_aux_data[def_idx - 1].zext_dst = true;
/* The dst will be zero extended, so won't be sub-register anymore. */
reg->subreg_def = DEF_NOT_SUBREG;
}
static int __check_reg_arg(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno,
enum reg_arg_type t)
{
struct bpf_insn *insn = env->prog->insnsi + env->insn_idx;
struct bpf_reg_state *reg;
bool rw64;
if (regno >= MAX_BPF_REG) {
verbose(env, "R%d is invalid\n", regno);
return -EINVAL;
}
mark_reg_scratched(env, regno);
reg = ®s[regno];
rw64 = is_reg64(env, insn, regno, reg, t);
if (t == SRC_OP) {
/* check whether register used as source operand can be read */
if (reg->type == NOT_INIT) {
verbose(env, "R%d !read_ok\n", regno);
return -EACCES;
}
/* We don't need to worry about FP liveness because it's read-only */
if (regno == BPF_REG_FP)
return 0;
if (rw64)
mark_insn_zext(env, reg);
return mark_reg_read(env, reg, reg->parent,
rw64 ? REG_LIVE_READ64 : REG_LIVE_READ32);
} else {
/* check whether register used as dest operand can be written to */
if (regno == BPF_REG_FP) {
verbose(env, "frame pointer is read only\n");
return -EACCES;
}
reg->live |= REG_LIVE_WRITTEN;
reg->subreg_def = rw64 ? DEF_NOT_SUBREG : env->insn_idx + 1;
if (t == DST_OP)
mark_reg_unknown(env, regs, regno);
}
return 0;
}
static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
enum reg_arg_type t)
{
struct bpf_verifier_state *vstate = env->cur_state;
struct bpf_func_state *state = vstate->frame[vstate->curframe];
return __check_reg_arg(env, state->regs, regno, t);
}
static int insn_stack_access_flags(int frameno, int spi)
{
return INSN_F_STACK_ACCESS | (spi << INSN_F_SPI_SHIFT) | frameno;
}
static int insn_stack_access_spi(int insn_flags)
{
return (insn_flags >> INSN_F_SPI_SHIFT) & INSN_F_SPI_MASK;
}
static int insn_stack_access_frameno(int insn_flags)
{
return insn_flags & INSN_F_FRAMENO_MASK;
}
static void mark_jmp_point(struct bpf_verifier_env *env, int idx)
{
env->insn_aux_data[idx].jmp_point = true;
}
static bool is_jmp_point(struct bpf_verifier_env *env, int insn_idx)
{
return env->insn_aux_data[insn_idx].jmp_point;
}
#define LR_FRAMENO_BITS 3
#define LR_SPI_BITS 6
#define LR_ENTRY_BITS (LR_SPI_BITS + LR_FRAMENO_BITS + 1)
#define LR_SIZE_BITS 4
#define LR_FRAMENO_MASK ((1ull << LR_FRAMENO_BITS) - 1)
#define LR_SPI_MASK ((1ull << LR_SPI_BITS) - 1)
#define LR_SIZE_MASK ((1ull << LR_SIZE_BITS) - 1)
#define LR_SPI_OFF LR_FRAMENO_BITS
#define LR_IS_REG_OFF (LR_SPI_BITS + LR_FRAMENO_BITS)
#define LINKED_REGS_MAX 6
struct linked_reg {
u8 frameno;
union {
u8 spi;
u8 regno;
};
bool is_reg;
};
struct linked_regs {
int cnt;
struct linked_reg entries[LINKED_REGS_MAX];
};
static struct linked_reg *linked_regs_push(struct linked_regs *s)
{
if (s->cnt < LINKED_REGS_MAX)
return &s->entries[s->cnt++];
return NULL;
}
/* Use u64 as a vector of 6 10-bit values, use first 4-bits to track
* number of elements currently in stack.
* Pack one history entry for linked registers as 10 bits in the following format:
* - 3-bits frameno
* - 6-bits spi_or_reg
* - 1-bit is_reg
*/
static u64 linked_regs_pack(struct linked_regs *s)
{
u64 val = 0;
int i;
for (i = 0; i < s->cnt; ++i) {
struct linked_reg *e = &s->entries[i];
u64 tmp = 0;
tmp |= e->frameno;
tmp |= e->spi << LR_SPI_OFF;
tmp |= (e->is_reg ? 1 : 0) << LR_IS_REG_OFF;
val <<= LR_ENTRY_BITS;
val |= tmp;
}
val <<= LR_SIZE_BITS;
val |= s->cnt;
return val;
}
static void linked_regs_unpack(u64 val, struct linked_regs *s)
{
int i;
s->cnt = val & LR_SIZE_MASK;
val >>= LR_SIZE_BITS;
for (i = 0; i < s->cnt; ++i) {
struct linked_reg *e = &s->entries[i];
e->frameno = val & LR_FRAMENO_MASK;
e->spi = (val >> LR_SPI_OFF) & LR_SPI_MASK;
e->is_reg = (val >> LR_IS_REG_OFF) & 0x1;
val >>= LR_ENTRY_BITS;
}
}
/* for any branch, call, exit record the history of jmps in the given state */
static int push_jmp_history(struct bpf_verifier_env *env, struct bpf_verifier_state *cur,
int insn_flags, u64 linked_regs)
{
u32 cnt = cur->jmp_history_cnt;
struct bpf_jmp_history_entry *p;
size_t alloc_size;
/* combine instruction flags if we already recorded this instruction */
if (env->cur_hist_ent) {
/* atomic instructions push insn_flags twice, for READ and
* WRITE sides, but they should agree on stack slot
*/
WARN_ONCE((env->cur_hist_ent->flags & insn_flags) &&
(env->cur_hist_ent->flags & insn_flags) != insn_flags,
"verifier insn history bug: insn_idx %d cur flags %x new flags %x\n",
env->insn_idx, env->cur_hist_ent->flags, insn_flags);
env->cur_hist_ent->flags |= insn_flags;
WARN_ONCE(env->cur_hist_ent->linked_regs != 0,
"verifier insn history bug: insn_idx %d linked_regs != 0: %#llx\n",
env->insn_idx, env->cur_hist_ent->linked_regs);
env->cur_hist_ent->linked_regs = linked_regs;
return 0;
}
cnt++;
alloc_size = kmalloc_size_roundup(size_mul(cnt, sizeof(*p)));
p = krealloc(cur->jmp_history, alloc_size, GFP_USER);
if (!p)
return -ENOMEM;
cur->jmp_history = p;
p = &cur->jmp_history[cnt - 1];
p->idx = env->insn_idx;
p->prev_idx = env->prev_insn_idx;
p->flags = insn_flags;
p->linked_regs = linked_regs;
cur->jmp_history_cnt = cnt;
env->cur_hist_ent = p;
return 0;
}
static struct bpf_jmp_history_entry *get_jmp_hist_entry(struct bpf_verifier_state *st,
u32 hist_end, int insn_idx)
{
if (hist_end > 0 && st->jmp_history[hist_end - 1].idx == insn_idx)
return &st->jmp_history[hist_end - 1];
return NULL;
}
/* Backtrack one insn at a time. If idx is not at the top of recorded
* history then previous instruction came from straight line execution.
* Return -ENOENT if we exhausted all instructions within given state.
*
* It's legal to have a bit of a looping with the same starting and ending
* insn index within the same state, e.g.: 3->4->5->3, so just because current
* instruction index is the same as state's first_idx doesn't mean we are
* done. If there is still some jump history left, we should keep going. We
* need to take into account that we might have a jump history between given
* state's parent and itself, due to checkpointing. In this case, we'll have
* history entry recording a jump from last instruction of parent state and
* first instruction of given state.
*/
static int get_prev_insn_idx(struct bpf_verifier_state *st, int i,
u32 *history)
{
u32 cnt = *history;
if (i == st->first_insn_idx) {
if (cnt == 0)
return -ENOENT;
if (cnt == 1 && st->jmp_history[0].idx == i)
return -ENOENT;
}
if (cnt && st->jmp_history[cnt - 1].idx == i) {
i = st->jmp_history[cnt - 1].prev_idx;
(*history)--;
} else {
i--;
}
return i;
}
static const char *disasm_kfunc_name(void *data, const struct bpf_insn *insn)
{
const struct btf_type *func;
struct btf *desc_btf;
if (insn->src_reg != BPF_PSEUDO_KFUNC_CALL)
return NULL;
desc_btf = find_kfunc_desc_btf(data, insn->off);
if (IS_ERR(desc_btf))
return "<error>";
func = btf_type_by_id(desc_btf, insn->imm);
return btf_name_by_offset(desc_btf, func->name_off);
}
static inline void bt_init(struct backtrack_state *bt, u32 frame)
{
bt->frame = frame;
}
static inline void bt_reset(struct backtrack_state *bt)
{
struct bpf_verifier_env *env = bt->env;
memset(bt, 0, sizeof(*bt));
bt->env = env;
}
static inline u32 bt_empty(struct backtrack_state *bt)
{
u64 mask = 0;
int i;
for (i = 0; i <= bt->frame; i++)
mask |= bt->reg_masks[i] | bt->stack_masks[i];
return mask == 0;
}
static inline int bt_subprog_enter(struct backtrack_state *bt)
{
if (bt->frame == MAX_CALL_FRAMES - 1) {
verbose(bt->env, "BUG subprog enter from frame %d\n", bt->frame);
WARN_ONCE(1, "verifier backtracking bug");
return -EFAULT;
}
bt->frame++;
return 0;
}
static inline int bt_subprog_exit(struct backtrack_state *bt)
{
if (bt->frame == 0) {
verbose(bt->env, "BUG subprog exit from frame 0\n");
WARN_ONCE(1, "verifier backtracking bug");
return -EFAULT;
}
bt->frame--;
return 0;
}
static inline void bt_set_frame_reg(struct backtrack_state *bt, u32 frame, u32 reg)
{
bt->reg_masks[frame] |= 1 << reg;
}
static inline void bt_clear_frame_reg(struct backtrack_state *bt, u32 frame, u32 reg)
{
bt->reg_masks[frame] &= ~(1 << reg);
}
static inline void bt_set_reg(struct backtrack_state *bt, u32 reg)
{
bt_set_frame_reg(bt, bt->frame, reg);
}
static inline void bt_clear_reg(struct backtrack_state *bt, u32 reg)
{
bt_clear_frame_reg(bt, bt->frame, reg);
}
static inline void bt_set_frame_slot(struct backtrack_state *bt, u32 frame, u32 slot)
{
bt->stack_masks[frame] |= 1ull << slot;
}
static inline void bt_clear_frame_slot(struct backtrack_state *bt, u32 frame, u32 slot)
{
bt->stack_masks[frame] &= ~(1ull << slot);
}
static inline u32 bt_frame_reg_mask(struct backtrack_state *bt, u32 frame)
{
return bt->reg_masks[frame];
}
static inline u32 bt_reg_mask(struct backtrack_state *bt)
{
return bt->reg_masks[bt->frame];
}
static inline u64 bt_frame_stack_mask(struct backtrack_state *bt, u32 frame)
{
return bt->stack_masks[frame];
}
static inline u64 bt_stack_mask(struct backtrack_state *bt)
{
return bt->stack_masks[bt->frame];
}
static inline bool bt_is_reg_set(struct backtrack_state *bt, u32 reg)
{
return bt->reg_masks[bt->frame] & (1 << reg);
}
static inline bool bt_is_frame_reg_set(struct backtrack_state *bt, u32 frame, u32 reg)
{
return bt->reg_masks[frame] & (1 << reg);
}
static inline bool bt_is_frame_slot_set(struct backtrack_state *bt, u32 frame, u32 slot)
{
return bt->stack_masks[frame] & (1ull << slot);
}
/* format registers bitmask, e.g., "r0,r2,r4" for 0x15 mask */
static void fmt_reg_mask(char *buf, ssize_t buf_sz, u32 reg_mask)
{
DECLARE_BITMAP(mask, 64);
bool first = true;
int i, n;
buf[0] = '\0';
bitmap_from_u64(mask, reg_mask);
for_each_set_bit(i, mask, 32) {
n = snprintf(buf, buf_sz, "%sr%d", first ? "" : ",", i);
first = false;
buf += n;
buf_sz -= n;
if (buf_sz < 0)
break;
}
}
/* format stack slots bitmask, e.g., "-8,-24,-40" for 0x15 mask */
static void fmt_stack_mask(char *buf, ssize_t buf_sz, u64 stack_mask)
{
DECLARE_BITMAP(mask, 64);
bool first = true;
int i, n;
buf[0] = '\0';
bitmap_from_u64(mask, stack_mask);
for_each_set_bit(i, mask, 64) {
n = snprintf(buf, buf_sz, "%s%d", first ? "" : ",", -(i + 1) * 8);
first = false;
buf += n;
buf_sz -= n;
if (buf_sz < 0)
break;
}
}
/* If any register R in hist->linked_regs is marked as precise in bt,
* do bt_set_frame_{reg,slot}(bt, R) for all registers in hist->linked_regs.
*/
static void bt_sync_linked_regs(struct backtrack_state *bt, struct bpf_jmp_history_entry *hist)
{
struct linked_regs linked_regs;
bool some_precise = false;
int i;
if (!hist || hist->linked_regs == 0)
return;
linked_regs_unpack(hist->linked_regs, &linked_regs);
for (i = 0; i < linked_regs.cnt; ++i) {
struct linked_reg *e = &linked_regs.entries[i];
if ((e->is_reg && bt_is_frame_reg_set(bt, e->frameno, e->regno)) ||
(!e->is_reg && bt_is_frame_slot_set(bt, e->frameno, e->spi))) {
some_precise = true;
break;
}
}
if (!some_precise)
return;
for (i = 0; i < linked_regs.cnt; ++i) {
struct linked_reg *e = &linked_regs.entries[i];
if (e->is_reg)
bt_set_frame_reg(bt, e->frameno, e->regno);
else
bt_set_frame_slot(bt, e->frameno, e->spi);
}
}
static bool calls_callback(struct bpf_verifier_env *env, int insn_idx);
/* For given verifier state backtrack_insn() is called from the last insn to
* the first insn. Its purpose is to compute a bitmask of registers and
* stack slots that needs precision in the parent verifier state.
*
* @idx is an index of the instruction we are currently processing;
* @subseq_idx is an index of the subsequent instruction that:
* - *would be* executed next, if jump history is viewed in forward order;
* - *was* processed previously during backtracking.
*/
static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx,
struct bpf_jmp_history_entry *hist, struct backtrack_state *bt)
{
const struct bpf_insn_cbs cbs = {
.cb_call = disasm_kfunc_name,
.cb_print = verbose,
.private_data = env,
};
struct bpf_insn *insn = env->prog->insnsi + idx;
u8 class = BPF_CLASS(insn->code);
u8 opcode = BPF_OP(insn->code);
u8 mode = BPF_MODE(insn->code);
u32 dreg = insn->dst_reg;
u32 sreg = insn->src_reg;
u32 spi, i, fr;
if (insn->code == 0)
return 0;
if (env->log.level & BPF_LOG_LEVEL2) {
fmt_reg_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, bt_reg_mask(bt));
verbose(env, "mark_precise: frame%d: regs=%s ",
bt->frame, env->tmp_str_buf);
fmt_stack_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, bt_stack_mask(bt));
verbose(env, "stack=%s before ", env->tmp_str_buf);
verbose(env, "%d: ", idx);
print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
}
/* If there is a history record that some registers gained range at this insn,
* propagate precision marks to those registers, so that bt_is_reg_set()
* accounts for these registers.
*/
bt_sync_linked_regs(bt, hist);
if (class == BPF_ALU || class == BPF_ALU64) {
if (!bt_is_reg_set(bt, dreg))
return 0;
if (opcode == BPF_END || opcode == BPF_NEG) {
/* sreg is reserved and unused
* dreg still need precision before this insn
*/
return 0;
} else if (opcode == BPF_MOV) {
if (BPF_SRC(insn->code) == BPF_X) {
/* dreg = sreg or dreg = (s8, s16, s32)sreg
* dreg needs precision after this insn
* sreg needs precision before this insn
*/
bt_clear_reg(bt, dreg);
if (sreg != BPF_REG_FP)
bt_set_reg(bt, sreg);
} else {
/* dreg = K
* dreg needs precision after this insn.
* Corresponding register is already marked
* as precise=true in this verifier state.
* No further markings in parent are necessary
*/
bt_clear_reg(bt, dreg);
}
} else {
if (BPF_SRC(insn->code) == BPF_X) {
/* dreg += sreg
* both dreg and sreg need precision
* before this insn
*/
if (sreg != BPF_REG_FP)
bt_set_reg(bt, sreg);
} /* else dreg += K
* dreg still needs precision before this insn
*/
}
} else if (class == BPF_LDX) {
if (!bt_is_reg_set(bt, dreg))
return 0;
bt_clear_reg(bt, dreg);
/* scalars can only be spilled into stack w/o losing precision.
* Load from any other memory can be zero extended.
* The desire to keep that precision is already indicated
* by 'precise' mark in corresponding register of this state.
* No further tracking necessary.
*/
if (!hist || !(hist->flags & INSN_F_STACK_ACCESS))
return 0;
/* dreg = *(u64 *)[fp - off] was a fill from the stack.
* that [fp - off] slot contains scalar that needs to be
* tracked with precision
*/
spi = insn_stack_access_spi(hist->flags);
fr = insn_stack_access_frameno(hist->flags);
bt_set_frame_slot(bt, fr, spi);
} else if (class == BPF_STX || class == BPF_ST) {
if (bt_is_reg_set(bt, dreg))
/* stx & st shouldn't be using _scalar_ dst_reg
* to access memory. It means backtracking
* encountered a case of pointer subtraction.
*/
return -ENOTSUPP;
/* scalars can only be spilled into stack */
if (!hist || !(hist->flags & INSN_F_STACK_ACCESS))
return 0;
spi = insn_stack_access_spi(hist->flags);
fr = insn_stack_access_frameno(hist->flags);
if (!bt_is_frame_slot_set(bt, fr, spi))
return 0;
bt_clear_frame_slot(bt, fr, spi);
if (class == BPF_STX)
bt_set_reg(bt, sreg);
} else if (class == BPF_JMP || class == BPF_JMP32) {
if (bpf_pseudo_call(insn)) {
int subprog_insn_idx, subprog;
subprog_insn_idx = idx + insn->imm + 1;
subprog = find_subprog(env, subprog_insn_idx);
if (subprog < 0)
return -EFAULT;
if (subprog_is_global(env, subprog)) {
/* check that jump history doesn't have any
* extra instructions from subprog; the next
* instruction after call to global subprog
* should be literally next instruction in
* caller program
*/
WARN_ONCE(idx + 1 != subseq_idx, "verifier backtracking bug");
/* r1-r5 are invalidated after subprog call,
* so for global func call it shouldn't be set
* anymore
*/
if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) {
verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
WARN_ONCE(1, "verifier backtracking bug");
return -EFAULT;
}
/* global subprog always sets R0 */
bt_clear_reg(bt, BPF_REG_0);
return 0;
} else {
/* static subprog call instruction, which
* means that we are exiting current subprog,
* so only r1-r5 could be still requested as
* precise, r0 and r6-r10 or any stack slot in
* the current frame should be zero by now
*/
if (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) {
verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
WARN_ONCE(1, "verifier backtracking bug");
return -EFAULT;
}
/* we are now tracking register spills correctly,
* so any instance of leftover slots is a bug
*/
if (bt_stack_mask(bt) != 0) {
verbose(env, "BUG stack slots %llx\n", bt_stack_mask(bt));
WARN_ONCE(1, "verifier backtracking bug (subprog leftover stack slots)");
return -EFAULT;
}
/* propagate r1-r5 to the caller */
for (i = BPF_REG_1; i <= BPF_REG_5; i++) {
if (bt_is_reg_set(bt, i)) {
bt_clear_reg(bt, i);
bt_set_frame_reg(bt, bt->frame - 1, i);
}
}
if (bt_subprog_exit(bt))
return -EFAULT;
return 0;
}
} else if (is_sync_callback_calling_insn(insn) && idx != subseq_idx - 1) {
/* exit from callback subprog to callback-calling helper or
* kfunc call. Use idx/subseq_idx check to discern it from
* straight line code backtracking.
* Unlike the subprog call handling above, we shouldn't
* propagate precision of r1-r5 (if any requested), as they are
* not actually arguments passed directly to callback subprogs
*/
if (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) {
verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
WARN_ONCE(1, "verifier backtracking bug");
return -EFAULT;
}
if (bt_stack_mask(bt) != 0) {
verbose(env, "BUG stack slots %llx\n", bt_stack_mask(bt));
WARN_ONCE(1, "verifier backtracking bug (callback leftover stack slots)");
return -EFAULT;
}
/* clear r1-r5 in callback subprog's mask */
for (i = BPF_REG_1; i <= BPF_REG_5; i++)
bt_clear_reg(bt, i);
if (bt_subprog_exit(bt))
return -EFAULT;
return 0;
} else if (opcode == BPF_CALL) {
/* kfunc with imm==0 is invalid and fixup_kfunc_call will
* catch this error later. Make backtracking conservative
* with ENOTSUPP.
*/
if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL && insn->imm == 0)
return -ENOTSUPP;
/* regular helper call sets R0 */
bt_clear_reg(bt, BPF_REG_0);
if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) {
/* if backtracing was looking for registers R1-R5
* they should have been found already.
*/
verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
WARN_ONCE(1, "verifier backtracking bug");
return -EFAULT;
}
} else if (opcode == BPF_EXIT) {
bool r0_precise;
/* Backtracking to a nested function call, 'idx' is a part of
* the inner frame 'subseq_idx' is a part of the outer frame.
* In case of a regular function call, instructions giving
* precision to registers R1-R5 should have been found already.
* In case of a callback, it is ok to have R1-R5 marked for
* backtracking, as these registers are set by the function
* invoking callback.
*/
if (subseq_idx >= 0 && calls_callback(env, subseq_idx))
for (i = BPF_REG_1; i <= BPF_REG_5; i++)
bt_clear_reg(bt, i);
if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) {
verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
WARN_ONCE(1, "verifier backtracking bug");
return -EFAULT;
}
/* BPF_EXIT in subprog or callback always returns
* right after the call instruction, so by checking
* whether the instruction at subseq_idx-1 is subprog
* call or not we can distinguish actual exit from
* *subprog* from exit from *callback*. In the former
* case, we need to propagate r0 precision, if
* necessary. In the former we never do that.
*/
r0_precise = subseq_idx - 1 >= 0 &&
bpf_pseudo_call(&env->prog->insnsi[subseq_idx - 1]) &&
bt_is_reg_set(bt, BPF_REG_0);
bt_clear_reg(bt, BPF_REG_0);
if (bt_subprog_enter(bt))
return -EFAULT;
if (r0_precise)
bt_set_reg(bt, BPF_REG_0);
/* r6-r9 and stack slots will stay set in caller frame
* bitmasks until we return back from callee(s)
*/
return 0;
} else if (BPF_SRC(insn->code) == BPF_X) {
if (!bt_is_reg_set(bt, dreg) && !bt_is_reg_set(bt, sreg))
return 0;
/* dreg <cond> sreg
* Both dreg and sreg need precision before
* this insn. If only sreg was marked precise
* before it would be equally necessary to
* propagate it to dreg.
*/
bt_set_reg(bt, dreg);
bt_set_reg(bt, sreg);
} else if (BPF_SRC(insn->code) == BPF_K) {
/* dreg <cond> K
* Only dreg still needs precision before
* this insn, so for the K-based conditional
* there is nothing new to be marked.
*/
}
} else if (class == BPF_LD) {
if (!bt_is_reg_set(bt, dreg))
return 0;
bt_clear_reg(bt, dreg);
/* It's ld_imm64 or ld_abs or ld_ind.
* For ld_imm64 no further tracking of precision
* into parent is necessary
*/
if (mode == BPF_IND || mode == BPF_ABS)
/* to be analyzed */
return -ENOTSUPP;
}
/* Propagate precision marks to linked registers, to account for
* registers marked as precise in this function.
*/
bt_sync_linked_regs(bt, hist);
return 0;
}
/* the scalar precision tracking algorithm:
* . at the start all registers have precise=false.
* . scalar ranges are tracked as normal through alu and jmp insns.
* . once precise value of the scalar register is used in:
* . ptr + scalar alu
* . if (scalar cond K|scalar)
* . helper_call(.., scalar, ...) where ARG_CONST is expected
* backtrack through the verifier states and mark all registers and
* stack slots with spilled constants that these scalar regisers
* should be precise.
* . during state pruning two registers (or spilled stack slots)
* are equivalent if both are not precise.
*
* Note the verifier cannot simply walk register parentage chain,
* since many different registers and stack slots could have been
* used to compute single precise scalar.
*
* The approach of starting with precise=true for all registers and then
* backtrack to mark a register as not precise when the verifier detects
* that program doesn't care about specific value (e.g., when helper
* takes register as ARG_ANYTHING parameter) is not safe.
*
* It's ok to walk single parentage chain of the verifier states.
* It's possible that this backtracking will go all the way till 1st insn.
* All other branches will be explored for needing precision later.
*
* The backtracking needs to deal with cases like:
* R8=map_value(id=0,off=0,ks=4,vs=1952,imm=0) R9_w=map_value(id=0,off=40,ks=4,vs=1952,imm=0)
* r9 -= r8
* r5 = r9
* if r5 > 0x79f goto pc+7
* R5_w=inv(id=0,umax_value=1951,var_off=(0x0; 0x7ff))
* r5 += 1
* ...
* call bpf_perf_event_output#25
* where .arg5_type = ARG_CONST_SIZE_OR_ZERO
*
* and this case:
* r6 = 1
* call foo // uses callee's r6 inside to compute r0
* r0 += r6
* if r0 == 0 goto
*
* to track above reg_mask/stack_mask needs to be independent for each frame.
*
* Also if parent's curframe > frame where backtracking started,
* the verifier need to mark registers in both frames, otherwise callees
* may incorrectly prune callers. This is similar to
* commit 7640ead93924 ("bpf: verifier: make sure callees don't prune with caller differences")
*
* For now backtracking falls back into conservative marking.
*/
static void mark_all_scalars_precise(struct bpf_verifier_env *env,
struct bpf_verifier_state *st)
{
struct bpf_func_state *func;
struct bpf_reg_state *reg;
int i, j;
if (env->log.level & BPF_LOG_LEVEL2) {
verbose(env, "mark_precise: frame%d: falling back to forcing all scalars precise\n",
st->curframe);
}
/* big hammer: mark all scalars precise in this path.
* pop_stack may still get !precise scalars.
* We also skip current state and go straight to first parent state,
* because precision markings in current non-checkpointed state are
* not needed. See why in the comment in __mark_chain_precision below.
*/
for (st = st->parent; st; st = st->parent) {
for (i = 0; i <= st->curframe; i++) {
func = st->frame[i];
for (j = 0; j < BPF_REG_FP; j++) {
reg = &func->regs[j];
if (reg->type != SCALAR_VALUE || reg->precise)
continue;
reg->precise = true;
if (env->log.level & BPF_LOG_LEVEL2) {
verbose(env, "force_precise: frame%d: forcing r%d to be precise\n",
i, j);
}
}
for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) {
if (!is_spilled_reg(&func->stack[j]))
continue;
reg = &func->stack[j].spilled_ptr;
if (reg->type != SCALAR_VALUE || reg->precise)
continue;
reg->precise = true;
if (env->log.level & BPF_LOG_LEVEL2) {
verbose(env, "force_precise: frame%d: forcing fp%d to be precise\n",
i, -(j + 1) * 8);
}
}
}
}
}
static void mark_all_scalars_imprecise(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
{
struct bpf_func_state *func;
struct bpf_reg_state *reg;
int i, j;
for (i = 0; i <= st->curframe; i++) {
func = st->frame[i];
for (j = 0; j < BPF_REG_FP; j++) {
reg = &func->regs[j];
if (reg->type != SCALAR_VALUE)
continue;
reg->precise = false;
}
for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) {
if (!is_spilled_reg(&func->stack[j]))
continue;
reg = &func->stack[j].spilled_ptr;
if (reg->type != SCALAR_VALUE)
continue;
reg->precise = false;
}
}
}
/*
* __mark_chain_precision() backtracks BPF program instruction sequence and
* chain of verifier states making sure that register *regno* (if regno >= 0)
* and/or stack slot *spi* (if spi >= 0) are marked as precisely tracked
* SCALARS, as well as any other registers and slots that contribute to
* a tracked state of given registers/stack slots, depending on specific BPF
* assembly instructions (see backtrack_insns() for exact instruction handling
* logic). This backtracking relies on recorded jmp_history and is able to
* traverse entire chain of parent states. This process ends only when all the
* necessary registers/slots and their transitive dependencies are marked as
* precise.
*
* One important and subtle aspect is that precise marks *do not matter* in
* the currently verified state (current state). It is important to understand
* why this is the case.
*
* First, note that current state is the state that is not yet "checkpointed",
* i.e., it is not yet put into env->explored_states, and it has no children
* states as well. It's ephemeral, and can end up either a) being discarded if
* compatible explored state is found at some point or BPF_EXIT instruction is
* reached or b) checkpointed and put into env->explored_states, branching out
* into one or more children states.
*
* In the former case, precise markings in current state are completely
* ignored by state comparison code (see regsafe() for details). Only
* checkpointed ("old") state precise markings are important, and if old
* state's register/slot is precise, regsafe() assumes current state's
* register/slot as precise and checks value ranges exactly and precisely. If
* states turn out to be compatible, current state's necessary precise
* markings and any required parent states' precise markings are enforced
* after the fact with propagate_precision() logic, after the fact. But it's
* important to realize that in this case, even after marking current state
* registers/slots as precise, we immediately discard current state. So what
* actually matters is any of the precise markings propagated into current
* state's parent states, which are always checkpointed (due to b) case above).
* As such, for scenario a) it doesn't matter if current state has precise
* markings set or not.
*
* Now, for the scenario b), checkpointing and forking into child(ren)
* state(s). Note that before current state gets to checkpointing step, any
* processed instruction always assumes precise SCALAR register/slot
* knowledge: if precise value or range is useful to prune jump branch, BPF
* verifier takes this opportunity enthusiastically. Similarly, when
* register's value is used to calculate offset or memory address, exact
* knowledge of SCALAR range is assumed, checked, and enforced. So, similar to
* what we mentioned above about state comparison ignoring precise markings
* during state comparison, BPF verifier ignores and also assumes precise
* markings *at will* during instruction verification process. But as verifier
* assumes precision, it also propagates any precision dependencies across
* parent states, which are not yet finalized, so can be further restricted
* based on new knowledge gained from restrictions enforced by their children
* states. This is so that once those parent states are finalized, i.e., when
* they have no more active children state, state comparison logic in
* is_state_visited() would enforce strict and precise SCALAR ranges, if
* required for correctness.
*
* To build a bit more intuition, note also that once a state is checkpointed,
* the path we took to get to that state is not important. This is crucial
* property for state pruning. When state is checkpointed and finalized at
* some instruction index, it can be correctly and safely used to "short
* circuit" any *compatible* state that reaches exactly the same instruction
* index. I.e., if we jumped to that instruction from a completely different
* code path than original finalized state was derived from, it doesn't
* matter, current state can be discarded because from that instruction
* forward having a compatible state will ensure we will safely reach the
* exit. States describe preconditions for further exploration, but completely
* forget the history of how we got here.
*
* This also means that even if we needed precise SCALAR range to get to
* finalized state, but from that point forward *that same* SCALAR register is
* never used in a precise context (i.e., it's precise value is not needed for
* correctness), it's correct and safe to mark such register as "imprecise"
* (i.e., precise marking set to false). This is what we rely on when we do
* not set precise marking in current state. If no child state requires
* precision for any given SCALAR register, it's safe to dictate that it can
* be imprecise. If any child state does require this register to be precise,
* we'll mark it precise later retroactively during precise markings
* propagation from child state to parent states.
*
* Skipping precise marking setting in current state is a mild version of
* relying on the above observation. But we can utilize this property even
* more aggressively by proactively forgetting any precise marking in the
* current state (which we inherited from the parent state), right before we
* checkpoint it and branch off into new child state. This is done by
* mark_all_scalars_imprecise() to hopefully get more permissive and generic
* finalized states which help in short circuiting more future states.
*/
static int __mark_chain_precision(struct bpf_verifier_env *env, int regno)
{
struct backtrack_state *bt = &env->bt;
struct bpf_verifier_state *st = env->cur_state;
int first_idx = st->first_insn_idx;
int last_idx = env->insn_idx;
int subseq_idx = -1;
struct bpf_func_state *func;
struct bpf_reg_state *reg;
bool skip_first = true;
int i, fr, err;
if (!env->bpf_capable)
return 0;
/* set frame number from which we are starting to backtrack */
bt_init(bt, env->cur_state->curframe);
/* Do sanity checks against current state of register and/or stack
* slot, but don't set precise flag in current state, as precision
* tracking in the current state is unnecessary.
*/
func = st->frame[bt->frame];
if (regno >= 0) {
reg = &func->regs[regno];
if (reg->type != SCALAR_VALUE) {
WARN_ONCE(1, "backtracing misuse");
return -EFAULT;
}
bt_set_reg(bt, regno);
}
if (bt_empty(bt))
return 0;
for (;;) {
DECLARE_BITMAP(mask, 64);
u32 history = st->jmp_history_cnt;
struct bpf_jmp_history_entry *hist;
if (env->log.level & BPF_LOG_LEVEL2) {
verbose(env, "mark_precise: frame%d: last_idx %d first_idx %d subseq_idx %d \n",
bt->frame, last_idx, first_idx, subseq_idx);
}
if (last_idx < 0) {
/* we are at the entry into subprog, which
* is expected for global funcs, but only if
* requested precise registers are R1-R5
* (which are global func's input arguments)
*/
if (st->curframe == 0 &&
st->frame[0]->subprogno > 0 &&
st->frame[0]->callsite == BPF_MAIN_FUNC &&
bt_stack_mask(bt) == 0 &&
(bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) == 0) {
bitmap_from_u64(mask, bt_reg_mask(bt));
for_each_set_bit(i, mask, 32) {
reg = &st->frame[0]->regs[i];
bt_clear_reg(bt, i);
if (reg->type == SCALAR_VALUE)
reg->precise = true;
}
return 0;
}
verbose(env, "BUG backtracking func entry subprog %d reg_mask %x stack_mask %llx\n",
st->frame[0]->subprogno, bt_reg_mask(bt), bt_stack_mask(bt));
WARN_ONCE(1, "verifier backtracking bug");
return -EFAULT;
}
for (i = last_idx;;) {
if (skip_first) {
err = 0;
skip_first = false;
} else {
hist = get_jmp_hist_entry(st, history, i);
err = backtrack_insn(env, i, subseq_idx, hist, bt);
}
if (err == -ENOTSUPP) {
mark_all_scalars_precise(env, env->cur_state);
bt_reset(bt);
return 0;
} else if (err) {
return err;
}
if (bt_empty(bt))
/* Found assignment(s) into tracked register in this state.
* Since this state is already marked, just return.
* Nothing to be tracked further in the parent state.
*/
return 0;
subseq_idx = i;
i = get_prev_insn_idx(st, i, &history);
if (i == -ENOENT)
break;
if (i >= env->prog->len) {
/* This can happen if backtracking reached insn 0
* and there are still reg_mask or stack_mask
* to backtrack.
* It means the backtracking missed the spot where
* particular register was initialized with a constant.
*/
verbose(env, "BUG backtracking idx %d\n", i);
WARN_ONCE(1, "verifier backtracking bug");
return -EFAULT;
}
}
st = st->parent;
if (!st)
break;
for (fr = bt->frame; fr >= 0; fr--) {
func = st->frame[fr];
bitmap_from_u64(mask, bt_frame_reg_mask(bt, fr));
for_each_set_bit(i, mask, 32) {
reg = &func->regs[i];
if (reg->type != SCALAR_VALUE) {
bt_clear_frame_reg(bt, fr, i);
continue;
}
if (reg->precise)
bt_clear_frame_reg(bt, fr, i);
else
reg->precise = true;
}
bitmap_from_u64(mask, bt_frame_stack_mask(bt, fr));
for_each_set_bit(i, mask, 64) {
if (i >= func->allocated_stack / BPF_REG_SIZE) {
verbose(env, "BUG backtracking (stack slot %d, total slots %d)\n",
i, func->allocated_stack / BPF_REG_SIZE);
WARN_ONCE(1, "verifier backtracking bug (stack slot out of bounds)");
return -EFAULT;
}
if (!is_spilled_scalar_reg(&func->stack[i])) {
bt_clear_frame_slot(bt, fr, i);
continue;
}
reg = &func->stack[i].spilled_ptr;
if (reg->precise)
bt_clear_frame_slot(bt, fr, i);
else
reg->precise = true;
}
if (env->log.level & BPF_LOG_LEVEL2) {
fmt_reg_mask(env->tmp_str_buf, TMP_STR_BUF_LEN,
bt_frame_reg_mask(bt, fr));
verbose(env, "mark_precise: frame%d: parent state regs=%s ",
fr, env->tmp_str_buf);
fmt_stack_mask(env->tmp_str_buf, TMP_STR_BUF_LEN,
bt_frame_stack_mask(bt, fr));
verbose(env, "stack=%s: ", env->tmp_str_buf);
print_verifier_state(env, func, true);
}
}
if (bt_empty(bt))
return 0;
subseq_idx = first_idx;
last_idx = st->last_insn_idx;
first_idx = st->first_insn_idx;
}
/* if we still have requested precise regs or slots, we missed
* something (e.g., stack access through non-r10 register), so
* fallback to marking all precise
*/
if (!bt_empty(bt)) {
mark_all_scalars_precise(env, env->cur_state);
bt_reset(bt);
}
return 0;
}
int mark_chain_precision(struct bpf_verifier_env *env, int regno)
{
return __mark_chain_precision(env, regno);
}
/* mark_chain_precision_batch() assumes that env->bt is set in the caller to
* desired reg and stack masks across all relevant frames
*/
static int mark_chain_precision_batch(struct bpf_verifier_env *env)
{
return __mark_chain_precision(env, -1);
}
static bool is_spillable_regtype(enum bpf_reg_type type)
{
switch (base_type(type)) {
case PTR_TO_MAP_VALUE:
case PTR_TO_STACK:
case PTR_TO_CTX:
case PTR_TO_PACKET:
case PTR_TO_PACKET_META:
case PTR_TO_PACKET_END:
case PTR_TO_FLOW_KEYS:
case CONST_PTR_TO_MAP:
case PTR_TO_SOCKET:
case PTR_TO_SOCK_COMMON:
case PTR_TO_TCP_SOCK:
case PTR_TO_XDP_SOCK:
case PTR_TO_BTF_ID:
case PTR_TO_BUF:
case PTR_TO_MEM:
case PTR_TO_FUNC:
case PTR_TO_MAP_KEY:
case PTR_TO_ARENA:
return true;
default:
return false;
}
}
/* Does this register contain a constant zero? */
static bool register_is_null(struct bpf_reg_state *reg)
{
return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0);
}
/* check if register is a constant scalar value */
static bool is_reg_const(struct bpf_reg_state *reg, bool subreg32)
{
return reg->type == SCALAR_VALUE &&
tnum_is_const(subreg32 ? tnum_subreg(reg->var_off) : reg->var_off);
}
/* assuming is_reg_const() is true, return constant value of a register */
static u64 reg_const_value(struct bpf_reg_state *reg, bool subreg32)
{
return subreg32 ? tnum_subreg(reg->var_off).value : reg->var_off.value;
}
static bool __is_pointer_value(bool allow_ptr_leaks,
const struct bpf_reg_state *reg)
{
if (allow_ptr_leaks)
return false;
return reg->type != SCALAR_VALUE;
}
static void assign_scalar_id_before_mov(struct bpf_verifier_env *env,
struct bpf_reg_state *src_reg)
{
if (src_reg->type != SCALAR_VALUE)
return;
if (src_reg->id & BPF_ADD_CONST) {
/*
* The verifier is processing rX = rY insn and
* rY->id has special linked register already.
* Cleared it, since multiple rX += const are not supported.
*/
src_reg->id = 0;
src_reg->off = 0;
}
if (!src_reg->id && !tnum_is_const(src_reg->var_off))
/* Ensure that src_reg has a valid ID that will be copied to
* dst_reg and then will be used by sync_linked_regs() to
* propagate min/max range.
*/
src_reg->id = ++env->id_gen;
}
/* Copy src state preserving dst->parent and dst->live fields */
static void copy_register_state(struct bpf_reg_state *dst, const struct bpf_reg_state *src)
{
struct bpf_reg_state *parent = dst->parent;
enum bpf_reg_liveness live = dst->live;
*dst = *src;
dst->parent = parent;
dst->live = live;
}
static void save_register_state(struct bpf_verifier_env *env,
struct bpf_func_state *state,
int spi, struct bpf_reg_state *reg,
int size)
{
int i;
copy_register_state(&state->stack[spi].spilled_ptr, reg);
if (size == BPF_REG_SIZE)
state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
for (i = BPF_REG_SIZE; i > BPF_REG_SIZE - size; i--)
state->stack[spi].slot_type[i - 1] = STACK_SPILL;
/* size < 8 bytes spill */
for (; i; i--)
mark_stack_slot_misc(env, &state->stack[spi].slot_type[i - 1]);
}
static bool is_bpf_st_mem(struct bpf_insn *insn)
{
return BPF_CLASS(insn->code) == BPF_ST && BPF_MODE(insn->code) == BPF_MEM;
}
static int get_reg_width(struct bpf_reg_state *reg)
{
return fls64(reg->umax_value);
}
/* See comment for mark_fastcall_pattern_for_call() */
static void check_fastcall_stack_contract(struct bpf_verifier_env *env,
struct bpf_func_state *state, int insn_idx, int off)
{
struct bpf_subprog_info *subprog = &env->subprog_info[state->subprogno];
struct bpf_insn_aux_data *aux = env->insn_aux_data;
int i;
if (subprog->fastcall_stack_off <= off || aux[insn_idx].fastcall_pattern)
return;
/* access to the region [max_stack_depth .. fastcall_stack_off)
* from something that is not a part of the fastcall pattern,
* disable fastcall rewrites for current subprogram by setting
* fastcall_stack_off to a value smaller than any possible offset.
*/
subprog->fastcall_stack_off = S16_MIN;
/* reset fastcall aux flags within subprogram,
* happens at most once per subprogram
*/
for (i = subprog->start; i < (subprog + 1)->start; ++i) {
aux[i].fastcall_spills_num = 0;
aux[i].fastcall_pattern = 0;
}
}
/* check_stack_{read,write}_fixed_off functions track spill/fill of registers,
* stack boundary and alignment are checked in check_mem_access()
*/
static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
/* stack frame we're writing to */
struct bpf_func_state *state,
int off, int size, int value_regno,
int insn_idx)
{
struct bpf_func_state *cur; /* state of the current function */
int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
struct bpf_insn *insn = &env->prog->insnsi[insn_idx];
struct bpf_reg_state *reg = NULL;
int insn_flags = insn_stack_access_flags(state->frameno, spi);
/* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
* so it's aligned access and [off, off + size) are within stack limits
*/
if (!env->allow_ptr_leaks &&
is_spilled_reg(&state->stack[spi]) &&
size != BPF_REG_SIZE) {
verbose(env, "attempt to corrupt spilled pointer on stack\n");
return -EACCES;
}
cur = env->cur_state->frame[env->cur_state->curframe];
if (value_regno >= 0)
reg = &cur->regs[value_regno];
if (!env->bypass_spec_v4) {
bool sanitize = reg && is_spillable_regtype(reg->type);
for (i = 0; i < size; i++) {
u8 type = state->stack[spi].slot_type[i];
if (type != STACK_MISC && type != STACK_ZERO) {
sanitize = true;
break;
}
}
if (sanitize)
env->insn_aux_data[insn_idx].sanitize_stack_spill = true;
}
err = destroy_if_dynptr_stack_slot(env, state, spi);
if (err)
return err;
check_fastcall_stack_contract(env, state, insn_idx, off);
mark_stack_slot_scratched(env, spi);
if (reg && !(off % BPF_REG_SIZE) && reg->type == SCALAR_VALUE && env->bpf_capable) {
bool reg_value_fits;
reg_value_fits = get_reg_width(reg) <= BITS_PER_BYTE * size;
/* Make sure that reg had an ID to build a relation on spill. */
if (reg_value_fits)
assign_scalar_id_before_mov(env, reg);
save_register_state(env, state, spi, reg, size);
/* Break the relation on a narrowing spill. */
if (!reg_value_fits)
state->stack[spi].spilled_ptr.id = 0;
} else if (!reg && !(off % BPF_REG_SIZE) && is_bpf_st_mem(insn) &&
env->bpf_capable) {
struct bpf_reg_state *tmp_reg = &env->fake_reg[0];
memset(tmp_reg, 0, sizeof(*tmp_reg));
__mark_reg_known(tmp_reg, insn->imm);
tmp_reg->type = SCALAR_VALUE;
save_register_state(env, state, spi, tmp_reg, size);
} else if (reg && is_spillable_regtype(reg->type)) {
/* register containing pointer is being spilled into stack */
if (size != BPF_REG_SIZE) {
verbose_linfo(env, insn_idx, "; ");
verbose(env, "invalid size of register spill\n");
return -EACCES;
}
if (state != cur && reg->type == PTR_TO_STACK) {
verbose(env, "cannot spill pointers to stack into stack frame of the caller\n");
return -EINVAL;
}
save_register_state(env, state, spi, reg, size);
} else {
u8 type = STACK_MISC;
/* regular write of data into stack destroys any spilled ptr */
state->stack[spi].spilled_ptr.type = NOT_INIT;
/* Mark slots as STACK_MISC if they belonged to spilled ptr/dynptr/iter. */
if (is_stack_slot_special(&state->stack[spi]))
for (i = 0; i < BPF_REG_SIZE; i++)
scrub_spilled_slot(&state->stack[spi].slot_type[i]);
/* only mark the slot as written if all 8 bytes were written
* otherwise read propagation may incorrectly stop too soon
* when stack slots are partially written.
* This heuristic means that read propagation will be
* conservative, since it will add reg_live_read marks
* to stack slots all the way to first state when programs
* writes+reads less than 8 bytes
*/
if (size == BPF_REG_SIZE)
state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
/* when we zero initialize stack slots mark them as such */
if ((reg && register_is_null(reg)) ||
(!reg && is_bpf_st_mem(insn) && insn->imm == 0)) {
/* STACK_ZERO case happened because register spill
* wasn't properly aligned at the stack slot boundary,
* so it's not a register spill anymore; force
* originating register to be precise to make
* STACK_ZERO correct for subsequent states
*/
err = mark_chain_precision(env, value_regno);
if (err)
return err;
type = STACK_ZERO;
}
/* Mark slots affected by this stack write. */
for (i = 0; i < size; i++)
state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] = type;
insn_flags = 0; /* not a register spill */
}
if (insn_flags)
return push_jmp_history(env, env->cur_state, insn_flags, 0);
return 0;
}
/* Write the stack: 'stack[ptr_regno + off] = value_regno'. 'ptr_regno' is
* known to contain a variable offset.
* This function checks whether the write is permitted and conservatively
* tracks the effects of the write, considering that each stack slot in the
* dynamic range is potentially written to.
*
* 'off' includes 'regno->off'.
* 'value_regno' can be -1, meaning that an unknown value is being written to
* the stack.
*
* Spilled pointers in range are not marked as written because we don't know
* what's going to be actually written. This means that read propagation for
* future reads cannot be terminated by this write.
*
* For privileged programs, uninitialized stack slots are considered
* initialized by this write (even though we don't know exactly what offsets
* are going to be written to). The idea is that we don't want the verifier to
* reject future reads that access slots written to through variable offsets.
*/
static int check_stack_write_var_off(struct bpf_verifier_env *env,
/* func where register points to */
struct bpf_func_state *state,
int ptr_regno, int off, int size,
int value_regno, int insn_idx)
{
struct bpf_func_state *cur; /* state of the current function */
int min_off, max_off;
int i, err;
struct bpf_reg_state *ptr_reg = NULL, *value_reg = NULL;
struct bpf_insn *insn = &env->prog->insnsi[insn_idx];
bool writing_zero = false;
/* set if the fact that we're writing a zero is used to let any
* stack slots remain STACK_ZERO
*/
bool zero_used = false;
cur = env->cur_state->frame[env->cur_state->curframe];
ptr_reg = &cur->regs[ptr_regno];
min_off = ptr_reg->smin_value + off;
max_off = ptr_reg->smax_value + off + size;
if (value_regno >= 0)
value_reg = &cur->regs[value_regno];
if ((value_reg && register_is_null(value_reg)) ||
(!value_reg && is_bpf_st_mem(insn) && insn->imm == 0))
writing_zero = true;
for (i = min_off; i < max_off; i++) {
int spi;
spi = __get_spi(i);
err = destroy_if_dynptr_stack_slot(env, state, spi);
if (err)
return err;
}
check_fastcall_stack_contract(env, state, insn_idx, min_off);
/* Variable offset writes destroy any spilled pointers in range. */
for (i = min_off; i < max_off; i++) {
u8 new_type, *stype;
int slot, spi;
slot = -i - 1;
spi = slot / BPF_REG_SIZE;
stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
mark_stack_slot_scratched(env, spi);
if (!env->allow_ptr_leaks && *stype != STACK_MISC && *stype != STACK_ZERO) {
/* Reject the write if range we may write to has not
* been initialized beforehand. If we didn't reject
* here, the ptr status would be erased below (even
* though not all slots are actually overwritten),
* possibly opening the door to leaks.
*
* We do however catch STACK_INVALID case below, and
* only allow reading possibly uninitialized memory
* later for CAP_PERFMON, as the write may not happen to
* that slot.
*/
verbose(env, "spilled ptr in range of var-offset stack write; insn %d, ptr off: %d",
insn_idx, i);
return -EINVAL;
}
/* If writing_zero and the spi slot contains a spill of value 0,
* maintain the spill type.
*/
if (writing_zero && *stype == STACK_SPILL &&
is_spilled_scalar_reg(&state->stack[spi])) {
struct bpf_reg_state *spill_reg = &state->stack[spi].spilled_ptr;
if (tnum_is_const(spill_reg->var_off) && spill_reg->var_off.value == 0) {
zero_used = true;
continue;
}
}
/* Erase all other spilled pointers. */
state->stack[spi].spilled_ptr.type = NOT_INIT;
/* Update the slot type. */
new_type = STACK_MISC;
if (writing_zero && *stype == STACK_ZERO) {
new_type = STACK_ZERO;
zero_used = true;
}
/* If the slot is STACK_INVALID, we check whether it's OK to
* pretend that it will be initialized by this write. The slot
* might not actually be written to, and so if we mark it as
* initialized future reads might leak uninitialized memory.
* For privileged programs, we will accept such reads to slots
* that may or may not be written because, if we're reject
* them, the error would be too confusing.
*/
if (*stype == STACK_INVALID && !env->allow_uninit_stack) {
verbose(env, "uninit stack in range of var-offset write prohibited for !root; insn %d, off: %d",
insn_idx, i);
return -EINVAL;
}
*stype = new_type;
}
if (zero_used) {
/* backtracking doesn't work for STACK_ZERO yet. */
err = mark_chain_precision(env, value_regno);
if (err)
return err;
}
return 0;
}
/* When register 'dst_regno' is assigned some values from stack[min_off,
* max_off), we set the register's type according to the types of the
* respective stack slots. If all the stack values are known to be zeros, then
* so is the destination reg. Otherwise, the register is considered to be
* SCALAR. This function does not deal with register filling; the caller must
* ensure that all spilled registers in the stack range have been marked as
* read.
*/
static void mark_reg_stack_read(struct bpf_verifier_env *env,
/* func where src register points to */
struct bpf_func_state *ptr_state,
int min_off, int max_off, int dst_regno)
{
struct bpf_verifier_state *vstate = env->cur_state;
struct bpf_func_state *state = vstate->frame[vstate->curframe];
int i, slot, spi;
u8 *stype;
int zeros = 0;
for (i = min_off; i < max_off; i++) {
slot = -i - 1;
spi = slot / BPF_REG_SIZE;
mark_stack_slot_scratched(env, spi);
stype = ptr_state->stack[spi].slot_type;
if (stype[slot % BPF_REG_SIZE] != STACK_ZERO)
break;
zeros++;
}
if (zeros == max_off - min_off) {
/* Any access_size read into register is zero extended,
* so the whole register == const_zero.
*/
__mark_reg_const_zero(env, &state->regs[dst_regno]);
} else {
/* have read misc data from the stack */
mark_reg_unknown(env, state->regs, dst_regno);
}
state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
}
/* Read the stack at 'off' and put the results into the register indicated by
* 'dst_regno'. It handles reg filling if the addressed stack slot is a
* spilled reg.
*
* 'dst_regno' can be -1, meaning that the read value is not going to a
* register.
*
* The access is assumed to be within the current stack bounds.
*/
static int check_stack_read_fixed_off(struct bpf_verifier_env *env,
/* func where src register points to */
struct bpf_func_state *reg_state,
int off, int size, int dst_regno)
{
struct bpf_verifier_state *vstate = env->cur_state;
struct bpf_func_state *state = vstate->frame[vstate->curframe];
int i, slot = -off - 1, spi = slot / BPF_REG_SIZE;
struct bpf_reg_state *reg;
u8 *stype, type;
int insn_flags = insn_stack_access_flags(reg_state->frameno, spi);
stype = reg_state->stack[spi].slot_type;
reg = ®_state->stack[spi].spilled_ptr;
mark_stack_slot_scratched(env, spi);
check_fastcall_stack_contract(env, state, env->insn_idx, off);
if (is_spilled_reg(®_state->stack[spi])) {
u8 spill_size = 1;
for (i = BPF_REG_SIZE - 1; i > 0 && stype[i - 1] == STACK_SPILL; i--)
spill_size++;
if (size != BPF_REG_SIZE || spill_size != BPF_REG_SIZE) {
if (reg->type != SCALAR_VALUE) {
verbose_linfo(env, env->insn_idx, "; ");
verbose(env, "invalid size of register fill\n");
return -EACCES;
}
mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
if (dst_regno < 0)
return 0;
if (size <= spill_size &&
bpf_stack_narrow_access_ok(off, size, spill_size)) {
/* The earlier check_reg_arg() has decided the
* subreg_def for this insn. Save it first.
*/
s32 subreg_def = state->regs[dst_regno].subreg_def;
copy_register_state(&state->regs[dst_regno], reg);
state->regs[dst_regno].subreg_def = subreg_def;
/* Break the relation on a narrowing fill.
* coerce_reg_to_size will adjust the boundaries.
*/
if (get_reg_width(reg) > size * BITS_PER_BYTE)
state->regs[dst_regno].id = 0;
} else {
int spill_cnt = 0, zero_cnt = 0;
for (i = 0; i < size; i++) {
type = stype[(slot - i) % BPF_REG_SIZE];
if (type == STACK_SPILL) {
spill_cnt++;
continue;
}
if (type == STACK_MISC)
continue;
if (type == STACK_ZERO) {
zero_cnt++;
continue;
}
if (type == STACK_INVALID && env->allow_uninit_stack)
continue;
verbose(env, "invalid read from stack off %d+%d size %d\n",
off, i, size);
return -EACCES;
}
if (spill_cnt == size &&
tnum_is_const(reg->var_off) && reg->var_off.value == 0) {
__mark_reg_const_zero(env, &state->regs[dst_regno]);
/* this IS register fill, so keep insn_flags */
} else if (zero_cnt == size) {
/* similarly to mark_reg_stack_read(), preserve zeroes */
__mark_reg_const_zero(env, &state->regs[dst_regno]);
insn_flags = 0; /* not restoring original register state */
} else {
mark_reg_unknown(env, state->regs, dst_regno);
insn_flags = 0; /* not restoring original register state */
}
}
state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
} else if (dst_regno >= 0) {
/* restore register state from stack */
copy_register_state(&state->regs[dst_regno], reg);
/* mark reg as written since spilled pointer state likely
* has its liveness marks cleared by is_state_visited()
* which resets stack/reg liveness for state transitions
*/
state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
} else if (__is_pointer_value(env->allow_ptr_leaks, reg)) {
/* If dst_regno==-1, the caller is asking us whether
* it is acceptable to use this value as a SCALAR_VALUE
* (e.g. for XADD).
* We must not allow unprivileged callers to do that
* with spilled pointers.
*/
verbose(env, "leaking pointer from stack off %d\n",
off);
return -EACCES;
}
mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
} else {
for (i = 0; i < size; i++) {
type = stype[(slot - i) % BPF_REG_SIZE];
if (type == STACK_MISC)
continue;
if (type == STACK_ZERO)
continue;
if (type == STACK_INVALID && env->allow_uninit_stack)
continue;
verbose(env, "invalid read from stack off %d+%d size %d\n",
off, i, size);
return -EACCES;
}
mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
if (dst_regno >= 0)
mark_reg_stack_read(env, reg_state, off, off + size, dst_regno);
insn_flags = 0; /* we are not restoring spilled register */
}
if (insn_flags)
return push_jmp_history(env, env->cur_state, insn_flags, 0);
return 0;
}
enum bpf_access_src {
ACCESS_DIRECT = 1, /* the access is performed by an instruction */
ACCESS_HELPER = 2, /* the access is performed by a helper */
};
static int check_stack_range_initialized(struct bpf_verifier_env *env,
int regno, int off, int access_size,
bool zero_size_allowed,
enum bpf_access_src type,
struct bpf_call_arg_meta *meta);
static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno)
{
return cur_regs(env) + regno;
}
/* Read the stack at 'ptr_regno + off' and put the result into the register
* 'dst_regno'.
* 'off' includes the pointer register's fixed offset(i.e. 'ptr_regno.off'),
* but not its variable offset.
* 'size' is assumed to be <= reg size and the access is assumed to be aligned.
*
* As opposed to check_stack_read_fixed_off, this function doesn't deal with
* filling registers (i.e. reads of spilled register cannot be detected when
* the offset is not fixed). We conservatively mark 'dst_regno' as containing
* SCALAR_VALUE. That's why we assert that the 'ptr_regno' has a variable
* offset; for a fixed offset check_stack_read_fixed_off should be used
* instead.
*/
static int check_stack_read_var_off(struct bpf_verifier_env *env,
int ptr_regno, int off, int size, int dst_regno)
{
/* The state of the source register. */
struct bpf_reg_state *reg = reg_state(env, ptr_regno);
struct bpf_func_state *ptr_state = func(env, reg);
int err;
int min_off, max_off;
/* Note that we pass a NULL meta, so raw access will not be permitted.
*/
err = check_stack_range_initialized(env, ptr_regno, off, size,
false, ACCESS_DIRECT, NULL);
if (err)
return err;
min_off = reg->smin_value + off;
max_off = reg->smax_value + off;
mark_reg_stack_read(env, ptr_state, min_off, max_off + size, dst_regno);
check_fastcall_stack_contract(env, ptr_state, env->insn_idx, min_off);
return 0;
}
/* check_stack_read dispatches to check_stack_read_fixed_off or
* check_stack_read_var_off.
*
* The caller must ensure that the offset falls within the allocated stack
* bounds.
*
* 'dst_regno' is a register which will receive the value from the stack. It
* can be -1, meaning that the read value is not going to a register.
*/
static int check_stack_read(struct bpf_verifier_env *env,
int ptr_regno, int off, int size,
int dst_regno)
{
struct bpf_reg_state *reg = reg_state(env, ptr_regno);
struct bpf_func_state *state = func(env, reg);
int err;
/* Some accesses are only permitted with a static offset. */
bool var_off = !tnum_is_const(reg->var_off);
/* The offset is required to be static when reads don't go to a
* register, in order to not leak pointers (see
* check_stack_read_fixed_off).
*/
if (dst_regno < 0 && var_off) {
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
verbose(env, "variable offset stack pointer cannot be passed into helper function; var_off=%s off=%d size=%d\n",
tn_buf, off, size);
return -EACCES;
}
/* Variable offset is prohibited for unprivileged mode for simplicity
* since it requires corresponding support in Spectre masking for stack
* ALU. See also retrieve_ptr_limit(). The check in
* check_stack_access_for_ptr_arithmetic() called by
* adjust_ptr_min_max_vals() prevents users from creating stack pointers
* with variable offsets, therefore no check is required here. Further,
* just checking it here would be insufficient as speculative stack
* writes could still lead to unsafe speculative behaviour.
*/
if (!var_off) {
off += reg->var_off.value;
err = check_stack_read_fixed_off(env, state, off, size,
dst_regno);
} else {
/* Variable offset stack reads need more conservative handling
* than fixed offset ones. Note that dst_regno >= 0 on this
* branch.
*/
err = check_stack_read_var_off(env, ptr_regno, off, size,
dst_regno);
}
return err;
}
/* check_stack_write dispatches to check_stack_write_fixed_off or
* check_stack_write_var_off.
*
* 'ptr_regno' is the register used as a pointer into the stack.
* 'off' includes 'ptr_regno->off', but not its variable offset (if any).
* 'value_regno' is the register whose value we're writing to the stack. It can
* be -1, meaning that we're not writing from a register.
*
* The caller must ensure that the offset falls within the maximum stack size.
*/
static int check_stack_write(struct bpf_verifier_env *env,
int ptr_regno, int off, int size,
int value_regno, int insn_idx)
{
struct bpf_reg_state *reg = reg_state(env, ptr_regno);
struct bpf_func_state *state = func(env, reg);
int err;
if (tnum_is_const(reg->var_off)) {
off += reg->var_off.value;
err = check_stack_write_fixed_off(env, state, off, size,
value_regno, insn_idx);
} else {
/* Variable offset stack reads need more conservative handling
* than fixed offset ones.
*/
err = check_stack_write_var_off(env, state,
ptr_regno, off, size,
value_regno, insn_idx);
}
return err;
}
static int check_map_access_type(struct bpf_verifier_env *env, u32 regno,
int off, int size, enum bpf_access_type type)
{
struct bpf_reg_state *regs = cur_regs(env);
struct bpf_map *map = regs[regno].map_ptr;
u32 cap = bpf_map_flags_to_cap(map);
if (type == BPF_WRITE && !(cap & BPF_MAP_CAN_WRITE)) {
verbose(env, "write into map forbidden, value_size=%d off=%d size=%d\n",
map->value_size, off, size);
return -EACCES;
}
if (type == BPF_READ && !(cap & BPF_MAP_CAN_READ)) {
verbose(env, "read from map forbidden, value_size=%d off=%d size=%d\n",
map->value_size, off, size);
return -EACCES;
}
return 0;
}
/* check read/write into memory region (e.g., map value, ringbuf sample, etc) */
static int __check_mem_access(struct bpf_verifier_env *env, int regno,
int off, int size, u32 mem_size,
bool zero_size_allowed)
{
bool size_ok = size > 0 || (size == 0 && zero_size_allowed);
struct bpf_reg_state *reg;
if (off >= 0 && size_ok && (u64)off + size <= mem_size)
return 0;
reg = &cur_regs(env)[regno];
switch (reg->type) {
case PTR_TO_MAP_KEY:
verbose(env, "invalid access to map key, key_size=%d off=%d size=%d\n",
mem_size, off, size);
break;
case PTR_TO_MAP_VALUE:
verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n",
mem_size, off, size);
break;
case PTR_TO_PACKET:
case PTR_TO_PACKET_META:
case PTR_TO_PACKET_END:
verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
off, size, regno, reg->id, off, mem_size);
break;
case PTR_TO_MEM:
default:
verbose(env, "invalid access to memory, mem_size=%u off=%d size=%d\n",
mem_size, off, size);
}
return -EACCES;
}
/* check read/write into a memory region with possible variable offset */
static int check_mem_region_access(struct bpf_verifier_env *env, u32 regno,
int off, int size, u32 mem_size,
bool zero_size_allowed)
{
struct bpf_verifier_state *vstate = env->cur_state;
struct bpf_func_state *state = vstate->frame[vstate->curframe];
struct bpf_reg_state *reg = &state->regs[regno];
int err;
/* We may have adjusted the register pointing to memory region, so we
* need to try adding each of min_value and max_value to off
* to make sure our theoretical access will be safe.
*
* The minimum value is only important with signed
* comparisons where we can't assume the floor of a
* value is 0. If we are using signed variables for our
* index'es we need to make sure that whatever we use
* will have a set floor within our range.
*/
if (reg->smin_value < 0 &&
(reg->smin_value == S64_MIN ||
(off + reg->smin_value != (s64)(s32)(off + reg->smin_value)) ||
reg->smin_value + off < 0)) {
verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
regno);
return -EACCES;
}
err = __check_mem_access(env, regno, reg->smin_value + off, size,
mem_size, zero_size_allowed);
if (err) {
verbose(env, "R%d min value is outside of the allowed memory range\n",
regno);
return err;
}
/* If we haven't set a max value then we need to bail since we can't be
* sure we won't do bad things.
* If reg->umax_value + off could overflow, treat that as unbounded too.
*/
if (reg->umax_value >= BPF_MAX_VAR_OFF) {
verbose(env, "R%d unbounded memory access, make sure to bounds check any such access\n",
regno);
return -EACCES;
}
err = __check_mem_access(env, regno, reg->umax_value + off, size,
mem_size, zero_size_allowed);
if (err) {
verbose(env, "R%d max value is outside of the allowed memory range\n",
regno);
return err;
}
return 0;
}
static int __check_ptr_off_reg(struct bpf_verifier_env *env,
const struct bpf_reg_state *reg, int regno,
bool fixed_off_ok)
{
/* Access to this pointer-typed register or passing it to a helper
* is only allowed in its original, unmodified form.
*/
if (reg->off < 0) {
verbose(env, "negative offset %s ptr R%d off=%d disallowed\n",
reg_type_str(env, reg->type), regno, reg->off);
return -EACCES;
}
if (!fixed_off_ok && reg->off) {
verbose(env, "dereference of modified %s ptr R%d off=%d disallowed\n",
reg_type_str(env, reg->type), regno, reg->off);
return -EACCES;
}
if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
verbose(env, "variable %s access var_off=%s disallowed\n",
reg_type_str(env, reg->type), tn_buf);
return -EACCES;
}
return 0;
}
static int check_ptr_off_reg(struct bpf_verifier_env *env,
const struct bpf_reg_state *reg, int regno)
{
return __check_ptr_off_reg(env, reg, regno, false);
}
static int map_kptr_match_type(struct bpf_verifier_env *env,
struct btf_field *kptr_field,
struct bpf_reg_state *reg, u32 regno)
{
const char *targ_name = btf_type_name(kptr_field->kptr.btf, kptr_field->kptr.btf_id);
int perm_flags;
const char *reg_name = "";
if (btf_is_kernel(reg->btf)) {
perm_flags = PTR_MAYBE_NULL | PTR_TRUSTED | MEM_RCU;
/* Only unreferenced case accepts untrusted pointers */
if (kptr_field->type == BPF_KPTR_UNREF)
perm_flags |= PTR_UNTRUSTED;
} else {
perm_flags = PTR_MAYBE_NULL | MEM_ALLOC;
if (kptr_field->type == BPF_KPTR_PERCPU)
perm_flags |= MEM_PERCPU;
}
if (base_type(reg->type) != PTR_TO_BTF_ID || (type_flag(reg->type) & ~perm_flags))
goto bad_type;
/* We need to verify reg->type and reg->btf, before accessing reg->btf */
reg_name = btf_type_name(reg->btf, reg->btf_id);
/* For ref_ptr case, release function check should ensure we get one
* referenced PTR_TO_BTF_ID, and that its fixed offset is 0. For the
* normal store of unreferenced kptr, we must ensure var_off is zero.
* Since ref_ptr cannot be accessed directly by BPF insns, checks for
* reg->off and reg->ref_obj_id are not needed here.
*/
if (__check_ptr_off_reg(env, reg, regno, true))
return -EACCES;
/* A full type match is needed, as BTF can be vmlinux, module or prog BTF, and
* we also need to take into account the reg->off.
*
* We want to support cases like:
*
* struct foo {
* struct bar br;
* struct baz bz;
* };
*
* struct foo *v;
* v = func(); // PTR_TO_BTF_ID
* val->foo = v; // reg->off is zero, btf and btf_id match type
* val->bar = &v->br; // reg->off is still zero, but we need to retry with
* // first member type of struct after comparison fails
* val->baz = &v->bz; // reg->off is non-zero, so struct needs to be walked
* // to match type
*
* In the kptr_ref case, check_func_arg_reg_off already ensures reg->off
* is zero. We must also ensure that btf_struct_ids_match does not walk
* the struct to match type against first member of struct, i.e. reject
* second case from above. Hence, when type is BPF_KPTR_REF, we set
* strict mode to true for type match.
*/
if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->off,
kptr_field->kptr.btf, kptr_field->kptr.btf_id,
kptr_field->type != BPF_KPTR_UNREF))
goto bad_type;
return 0;
bad_type:
verbose(env, "invalid kptr access, R%d type=%s%s ", regno,
reg_type_str(env, reg->type), reg_name);
verbose(env, "expected=%s%s", reg_type_str(env, PTR_TO_BTF_ID), targ_name);
if (kptr_field->type == BPF_KPTR_UNREF)
verbose(env, " or %s%s\n", reg_type_str(env, PTR_TO_BTF_ID | PTR_UNTRUSTED),
targ_name);
else
verbose(env, "\n");
return -EINVAL;
}
static bool in_sleepable(struct bpf_verifier_env *env)
{
return env->prog->sleepable ||
(env->cur_state && env->cur_state->in_sleepable);
}
/* The non-sleepable programs and sleepable programs with explicit bpf_rcu_read_lock()
* can dereference RCU protected pointers and result is PTR_TRUSTED.
*/
static bool in_rcu_cs(struct bpf_verifier_env *env)
{
return env->cur_state->active_rcu_lock ||
env->cur_state->active_lock.ptr ||
!in_sleepable(env);
}
/* Once GCC supports btf_type_tag the following mechanism will be replaced with tag check */
BTF_SET_START(rcu_protected_types)
BTF_ID(struct, prog_test_ref_kfunc)
#ifdef CONFIG_CGROUPS
BTF_ID(struct, cgroup)
#endif
#ifdef CONFIG_BPF_JIT
BTF_ID(struct, bpf_cpumask)
#endif
BTF_ID(struct, task_struct)
BTF_ID(struct, bpf_crypto_ctx)
BTF_SET_END(rcu_protected_types)
static bool rcu_protected_object(const struct btf *btf, u32 btf_id)
{
if (!btf_is_kernel(btf))
return true;
return btf_id_set_contains(&rcu_protected_types, btf_id);
}
static struct btf_record *kptr_pointee_btf_record(struct btf_field *kptr_field)
{
struct btf_struct_meta *meta;
if (btf_is_kernel(kptr_field->kptr.btf))
return NULL;
meta = btf_find_struct_meta(kptr_field->kptr.btf,
kptr_field->kptr.btf_id);
return meta ? meta->record : NULL;
}
static bool rcu_safe_kptr(const struct btf_field *field)
{
const struct btf_field_kptr *kptr = &field->kptr;
return field->type == BPF_KPTR_PERCPU ||
(field->type == BPF_KPTR_REF && rcu_protected_object(kptr->btf, kptr->btf_id));
}
static u32 btf_ld_kptr_type(struct bpf_verifier_env *env, struct btf_field *kptr_field)
{
struct btf_record *rec;
u32 ret;
ret = PTR_MAYBE_NULL;
if (rcu_safe_kptr(kptr_field) && in_rcu_cs(env)) {
ret |= MEM_RCU;
if (kptr_field->type == BPF_KPTR_PERCPU)
ret |= MEM_PERCPU;
else if (!btf_is_kernel(kptr_field->kptr.btf))
ret |= MEM_ALLOC;
rec = kptr_pointee_btf_record(kptr_field);
if (rec && btf_record_has_field(rec, BPF_GRAPH_NODE))
ret |= NON_OWN_REF;
} else {
ret |= PTR_UNTRUSTED;
}
return ret;
}
static int check_map_kptr_access(struct bpf_verifier_env *env, u32 regno,
int value_regno, int insn_idx,
struct btf_field *kptr_field)
{
struct bpf_insn *insn = &env->prog->insnsi[insn_idx];
int class = BPF_CLASS(insn->code);
struct bpf_reg_state *val_reg;
/* Things we already checked for in check_map_access and caller:
* - Reject cases where variable offset may touch kptr
* - size of access (must be BPF_DW)
* - tnum_is_const(reg->var_off)
* - kptr_field->offset == off + reg->var_off.value
*/
/* Only BPF_[LDX,STX,ST] | BPF_MEM | BPF_DW is supported */
if (BPF_MODE(insn->code) != BPF_MEM) {
verbose(env, "kptr in map can only be accessed using BPF_MEM instruction mode\n");
return -EACCES;
}
/* We only allow loading referenced kptr, since it will be marked as
* untrusted, similar to unreferenced kptr.
*/
if (class != BPF_LDX &&
(kptr_field->type == BPF_KPTR_REF || kptr_field->type == BPF_KPTR_PERCPU)) {
verbose(env, "store to referenced kptr disallowed\n");
return -EACCES;
}
if (class == BPF_LDX) {
val_reg = reg_state(env, value_regno);
/* We can simply mark the value_regno receiving the pointer
* value from map as PTR_TO_BTF_ID, with the correct type.
*/
mark_btf_ld_reg(env, cur_regs(env), value_regno, PTR_TO_BTF_ID, kptr_field->kptr.btf,
kptr_field->kptr.btf_id, btf_ld_kptr_type(env, kptr_field));
} else if (class == BPF_STX) {
val_reg = reg_state(env, value_regno);
if (!register_is_null(val_reg) &&
map_kptr_match_type(env, kptr_field, val_reg, value_regno))
return -EACCES;
} else if (class == BPF_ST) {
if (insn->imm) {
verbose(env, "BPF_ST imm must be 0 when storing to kptr at off=%u\n",
kptr_field->offset);
return -EACCES;
}
} else {
verbose(env, "kptr in map can only be accessed using BPF_LDX/BPF_STX/BPF_ST\n");
return -EACCES;
}
return 0;
}
/* check read/write into a map element with possible variable offset */
static int check_map_access(struct bpf_verifier_env *env, u32 regno,
int off, int size, bool zero_size_allowed,
enum bpf_access_src src)
{
struct bpf_verifier_state *vstate = env->cur_state;
struct bpf_func_state *state = vstate->frame[vstate->curframe];
struct bpf_reg_state *reg = &state->regs[regno];
struct bpf_map *map = reg->map_ptr;
struct btf_record *rec;
int err, i;
err = check_mem_region_access(env, regno, off, size, map->value_size,
zero_size_allowed);
if (err)
return err;
if (IS_ERR_OR_NULL(map->record))
return 0;
rec = map->record;
for (i = 0; i < rec->cnt; i++) {
struct btf_field *field = &rec->fields[i];
u32 p = field->offset;
/* If any part of a field can be touched by load/store, reject
* this program. To check that [x1, x2) overlaps with [y1, y2),
* it is sufficient to check x1 < y2 && y1 < x2.
*/
if (reg->smin_value + off < p + field->size &&
p < reg->umax_value + off + size) {
switch (field->type) {
case BPF_KPTR_UNREF:
case BPF_KPTR_REF:
case BPF_KPTR_PERCPU:
if (src != ACCESS_DIRECT) {
verbose(env, "kptr cannot be accessed indirectly by helper\n");
return -EACCES;
}
if (!tnum_is_const(reg->var_off)) {
verbose(env, "kptr access cannot have variable offset\n");
return -EACCES;
}
if (p != off + reg->var_off.value) {
verbose(env, "kptr access misaligned expected=%u off=%llu\n",
p, off + reg->var_off.value);
return -EACCES;
}
if (size != bpf_size_to_bytes(BPF_DW)) {
verbose(env, "kptr access size must be BPF_DW\n");
return -EACCES;
}
break;
default:
verbose(env, "%s cannot be accessed directly by load/store\n",
btf_field_type_name(field->type));
return -EACCES;
}
}
}
return 0;
}
#define MAX_PACKET_OFF 0xffff
static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
const struct bpf_call_arg_meta *meta,
enum bpf_access_type t)
{
enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
switch (prog_type) {
/* Program types only with direct read access go here! */
case BPF_PROG_TYPE_LWT_IN:
case BPF_PROG_TYPE_LWT_OUT:
case BPF_PROG_TYPE_LWT_SEG6LOCAL:
case BPF_PROG_TYPE_SK_REUSEPORT:
case BPF_PROG_TYPE_FLOW_DISSECTOR:
case BPF_PROG_TYPE_CGROUP_SKB:
if (t == BPF_WRITE)
return false;
fallthrough;
/* Program types with direct read + write access go here! */
case BPF_PROG_TYPE_SCHED_CLS:
case BPF_PROG_TYPE_SCHED_ACT:
case BPF_PROG_TYPE_XDP:
case BPF_PROG_TYPE_LWT_XMIT:
case BPF_PROG_TYPE_SK_SKB:
case BPF_PROG_TYPE_SK_MSG:
if (meta)
return meta->pkt_access;
env->seen_direct_write = true;
return true;
case BPF_PROG_TYPE_CGROUP_SOCKOPT:
if (t == BPF_WRITE)
env->seen_direct_write = true;
return true;
default:
return false;
}
}
static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
int size, bool zero_size_allowed)
{
struct bpf_reg_state *regs = cur_regs(env);
struct bpf_reg_state *reg = ®s[regno];
int err;
/* We may have added a variable offset to the packet pointer; but any
* reg->range we have comes after that. We are only checking the fixed
* offset.
*/
/* We don't allow negative numbers, because we aren't tracking enough
* detail to prove they're safe.
*/
if (reg->smin_value < 0) {
verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
regno);
return -EACCES;
}
err = reg->range < 0 ? -EINVAL :
__check_mem_access(env, regno, off, size, reg->range,
zero_size_allowed);
if (err) {
verbose(env, "R%d offset is outside of the packet\n", regno);
return err;
}
/* __check_mem_access has made sure "off + size - 1" is within u16.
* reg->umax_value can't be bigger than MAX_PACKET_OFF which is 0xffff,
* otherwise find_good_pkt_pointers would have refused to set range info
* that __check_mem_access would have rejected this pkt access.
* Therefore, "off + reg->umax_value + size - 1" won't overflow u32.
*/
env->prog->aux->max_pkt_offset =
max_t(u32, env->prog->aux->max_pkt_offset,
off + reg->umax_value + size - 1);
return err;
}
/* check access to 'struct bpf_context' fields. Supports fixed offsets only */
static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size,
enum bpf_access_type t, enum bpf_reg_type *reg_type,
struct btf **btf, u32 *btf_id, bool *is_retval, bool is_ldsx)
{
struct bpf_insn_access_aux info = {
.reg_type = *reg_type,
.log = &env->log,
.is_retval = false,
.is_ldsx = is_ldsx,
};
if (env->ops->is_valid_access &&
env->ops->is_valid_access(off, size, t, env->prog, &info)) {
/* A non zero info.ctx_field_size indicates that this field is a
* candidate for later verifier transformation to load the whole
* field and then apply a mask when accessed with a narrower
* access than actual ctx access size. A zero info.ctx_field_size
* will only allow for whole field access and rejects any other
* type of narrower access.
*/
*reg_type = info.reg_type;
*is_retval = info.is_retval;
if (base_type(*reg_type) == PTR_TO_BTF_ID) {
*btf = info.btf;
*btf_id = info.btf_id;
} else {
env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
}
/* remember the offset of last byte accessed in ctx */
if (env->prog->aux->max_ctx_offset < off + size)
env->prog->aux->max_ctx_offset = off + size;
return 0;
}
verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size);
return -EACCES;
}
static int check_flow_keys_access(struct bpf_verifier_env *env, int off,
int size)
{
if (size < 0 || off < 0 ||
(u64)off + size > sizeof(struct bpf_flow_keys)) {
verbose(env, "invalid access to flow keys off=%d size=%d\n",
off, size);
return -EACCES;
}
return 0;
}
static int check_sock_access(struct bpf_verifier_env *env, int insn_idx,
u32 regno, int off, int size,
enum bpf_access_type t)
{
struct bpf_reg_state *regs = cur_regs(env);
struct bpf_reg_state *reg = ®s[regno];
struct bpf_insn_access_aux info = {};
bool valid;
if (reg->smin_value < 0) {
verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
regno);
return -EACCES;
}
switch (reg->type) {
case PTR_TO_SOCK_COMMON:
valid = bpf_sock_common_is_valid_access(off, size, t, &info);
break;
case PTR_TO_SOCKET:
valid = bpf_sock_is_valid_access(off, size, t, &info);
break;
case PTR_TO_TCP_SOCK:
valid = bpf_tcp_sock_is_valid_access(off, size, t, &info);
break;
case PTR_TO_XDP_SOCK:
valid = bpf_xdp_sock_is_valid_access(off, size, t, &info);
break;
default:
valid = false;
}
if (valid) {
env->insn_aux_data[insn_idx].ctx_field_size =
info.ctx_field_size;
return 0;
}
verbose(env, "R%d invalid %s access off=%d size=%d\n",
regno, reg_type_str(env, reg->type), off, size);
return -EACCES;
}
static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
{
return __is_pointer_value(env->allow_ptr_leaks, reg_state(env, regno));
}
static bool is_ctx_reg(struct bpf_verifier_env *env, int regno)
{
const struct bpf_reg_state *reg = reg_state(env, regno);
return reg->type == PTR_TO_CTX;
}
static bool is_sk_reg(struct bpf_verifier_env *env, int regno)
{
const struct bpf_reg_state *reg = reg_state(env, regno);
return type_is_sk_pointer(reg->type);
}
static bool is_pkt_reg(struct bpf_verifier_env *env, int regno)
{
const struct bpf_reg_state *reg = reg_state(env, regno);
return type_is_pkt_pointer(reg->type);
}
static bool is_flow_key_reg(struct bpf_verifier_env *env, int regno)
{
const struct bpf_reg_state *reg = reg_state(env, regno);
/* Separate to is_ctx_reg() since we still want to allow BPF_ST here. */
return reg->type == PTR_TO_FLOW_KEYS;
}
static bool is_arena_reg(struct bpf_verifier_env *env, int regno)
{
const struct bpf_reg_state *reg = reg_state(env, regno);
return reg->type == PTR_TO_ARENA;
}
static u32 *reg2btf_ids[__BPF_REG_TYPE_MAX] = {
#ifdef CONFIG_NET
[PTR_TO_SOCKET] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK],
[PTR_TO_SOCK_COMMON] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
[PTR_TO_TCP_SOCK] = &btf_sock_ids[BTF_SOCK_TYPE_TCP],
#endif
[CONST_PTR_TO_MAP] = btf_bpf_map_id,
};
static bool is_trusted_reg(const struct bpf_reg_state *reg)
{
/* A referenced register is always trusted. */
if (reg->ref_obj_id)
return true;
/* Types listed in the reg2btf_ids are always trusted */
if (reg2btf_ids[base_type(reg->type)] &&
!bpf_type_has_unsafe_modifiers(reg->type))
return true;
/* If a register is not referenced, it is trusted if it has the
* MEM_ALLOC or PTR_TRUSTED type modifiers, and no others. Some of the
* other type modifiers may be safe, but we elect to take an opt-in
* approach here as some (e.g. PTR_UNTRUSTED and PTR_MAYBE_NULL) are
* not.
*
* Eventually, we should make PTR_TRUSTED the single source of truth
* for whether a register is trusted.
*/
return type_flag(reg->type) & BPF_REG_TRUSTED_MODIFIERS &&
!bpf_type_has_unsafe_modifiers(reg->type);
}
static bool is_rcu_reg(const struct bpf_reg_state *reg)
{
return reg->type & MEM_RCU;
}
static void clear_trusted_flags(enum bpf_type_flag *flag)
{
*flag &= ~(BPF_REG_TRUSTED_MODIFIERS | MEM_RCU);
}
static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
const struct bpf_reg_state *reg,
int off, int size, bool strict)
{
struct tnum reg_off;
int ip_align;
/* Byte size accesses are always allowed. */
if (!strict || size == 1)
return 0;
/* For platforms that do not have a Kconfig enabling
* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
* NET_IP_ALIGN is universally set to '2'. And on platforms
* that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
* to this code only in strict mode where we want to emulate
* the NET_IP_ALIGN==2 checking. Therefore use an
* unconditional IP align value of '2'.
*/
ip_align = 2;
reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off));
if (!tnum_is_aligned(reg_off, size)) {
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
verbose(env,
"misaligned packet access off %d+%s+%d+%d size %d\n",
ip_align, tn_buf, reg->off, off, size);
return -EACCES;
}
return 0;
}
static int check_generic_ptr_alignment(struct bpf_verifier_env *env,
const struct bpf_reg_state *reg,
const char *pointer_desc,
int off, int size, bool strict)
{
struct tnum reg_off;
/* Byte size accesses are always allowed. */
if (!strict || size == 1)
return 0;
reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off));
if (!tnum_is_aligned(reg_off, size)) {
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
verbose(env, "misaligned %saccess off %s+%d+%d size %d\n",
pointer_desc, tn_buf, reg->off, off, size);
return -EACCES;
}
return 0;
}
static int check_ptr_alignment(struct bpf_verifier_env *env,
const struct bpf_reg_state *reg, int off,
int size, bool strict_alignment_once)
{
bool strict = env->strict_alignment || strict_alignment_once;
const char *pointer_desc = "";
switch (reg->type) {
case PTR_TO_PACKET:
case PTR_TO_PACKET_META:
/* Special case, because of NET_IP_ALIGN. Given metadata sits
* right in front, treat it the very same way.
*/
return check_pkt_ptr_alignment(env, reg, off, size, strict);
case PTR_TO_FLOW_KEYS:
pointer_desc = "flow keys ";
break;
case PTR_TO_MAP_KEY:
pointer_desc = "key ";
break;
case PTR_TO_MAP_VALUE:
pointer_desc = "value ";
break;
case PTR_TO_CTX:
pointer_desc = "context ";
break;
case PTR_TO_STACK:
pointer_desc = "stack ";
/* The stack spill tracking logic in check_stack_write_fixed_off()
* and check_stack_read_fixed_off() relies on stack accesses being
* aligned.
*/
strict = true;
break;
case PTR_TO_SOCKET:
pointer_desc = "sock ";
break;
case PTR_TO_SOCK_COMMON:
pointer_desc = "sock_common ";
break;
case PTR_TO_TCP_SOCK:
pointer_desc = "tcp_sock ";
break;
case PTR_TO_XDP_SOCK:
pointer_desc = "xdp_sock ";
break;
case PTR_TO_ARENA:
return 0;
default:
break;
}
return check_generic_ptr_alignment(env, reg, pointer_desc, off, size,
strict);
}
static int round_up_stack_depth(struct bpf_verifier_env *env, int stack_depth)
{
if (env->prog->jit_requested)
return round_up(stack_depth, 16);
/* round up to 32-bytes, since this is granularity
* of interpreter stack size
*/
return round_up(max_t(u32, stack_depth, 1), 32);
}
/* starting from main bpf function walk all instructions of the function
* and recursively walk all callees that given function can call.
* Ignore jump and exit insns.
* Since recursion is prevented by check_cfg() this algorithm
* only needs a local stack of MAX_CALL_FRAMES to remember callsites
*/
static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx)
{
struct bpf_subprog_info *subprog = env->subprog_info;
struct bpf_insn *insn = env->prog->insnsi;
int depth = 0, frame = 0, i, subprog_end;
bool tail_call_reachable = false;
int ret_insn[MAX_CALL_FRAMES];
int ret_prog[MAX_CALL_FRAMES];
int j;
i = subprog[idx].start;
process_func:
/* protect against potential stack overflow that might happen when
* bpf2bpf calls get combined with tailcalls. Limit the caller's stack
* depth for such case down to 256 so that the worst case scenario
* would result in 8k stack size (32 which is tailcall limit * 256 =
* 8k).
*
* To get the idea what might happen, see an example:
* func1 -> sub rsp, 128
* subfunc1 -> sub rsp, 256
* tailcall1 -> add rsp, 256
* func2 -> sub rsp, 192 (total stack size = 128 + 192 = 320)
* subfunc2 -> sub rsp, 64
* subfunc22 -> sub rsp, 128
* tailcall2 -> add rsp, 128
* func3 -> sub rsp, 32 (total stack size 128 + 192 + 64 + 32 = 416)
*
* tailcall will unwind the current stack frame but it will not get rid
* of caller's stack as shown on the example above.
*/
if (idx && subprog[idx].has_tail_call && depth >= 256) {
verbose(env,
"tail_calls are not allowed when call stack of previous frames is %d bytes. Too large\n",
depth);
return -EACCES;
}
depth += round_up_stack_depth(env, subprog[idx].stack_depth);
if (depth > MAX_BPF_STACK) {
verbose(env, "combined stack size of %d calls is %d. Too large\n",
frame + 1, depth);
return -EACCES;
}
continue_func:
subprog_end = subprog[idx + 1].start;
for (; i < subprog_end; i++) {
int next_insn, sidx;
if (bpf_pseudo_kfunc_call(insn + i) && !insn[i].off) {
bool err = false;
if (!is_bpf_throw_kfunc(insn + i))
continue;
if (subprog[idx].is_cb)
err = true;
for (int c = 0; c < frame && !err; c++) {
if (subprog[ret_prog[c]].is_cb) {
err = true;
break;
}
}
if (!err)
continue;
verbose(env,
"bpf_throw kfunc (insn %d) cannot be called from callback subprog %d\n",
i, idx);
return -EINVAL;
}
if (!bpf_pseudo_call(insn + i) && !bpf_pseudo_func(insn + i))
continue;
/* remember insn and function to return to */
ret_insn[frame] = i + 1;
ret_prog[frame] = idx;
/* find the callee */
next_insn = i + insn[i].imm + 1;
sidx = find_subprog(env, next_insn);
if (sidx < 0) {
WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
next_insn);
return -EFAULT;
}
if (subprog[sidx].is_async_cb) {
if (subprog[sidx].has_tail_call) {
verbose(env, "verifier bug. subprog has tail_call and async cb\n");
return -EFAULT;
}
/* async callbacks don't increase bpf prog stack size unless called directly */
if (!bpf_pseudo_call(insn + i))
continue;
if (subprog[sidx].is_exception_cb) {
verbose(env, "insn %d cannot call exception cb directly\n", i);
return -EINVAL;
}
}
i = next_insn;
idx = sidx;
if (subprog[idx].has_tail_call)
tail_call_reachable = true;
frame++;
if (frame >= MAX_CALL_FRAMES) {
verbose(env, "the call stack of %d frames is too deep !\n",
frame);
return -E2BIG;
}
goto process_func;
}
/* if tail call got detected across bpf2bpf calls then mark each of the
* currently present subprog frames as tail call reachable subprogs;
* this info will be utilized by JIT so that we will be preserving the
* tail call counter throughout bpf2bpf calls combined with tailcalls
*/
if (tail_call_reachable)
for (j = 0; j < frame; j++) {
if (subprog[ret_prog[j]].is_exception_cb) {
verbose(env, "cannot tail call within exception cb\n");
return -EINVAL;
}
subprog[ret_prog[j]].tail_call_reachable = true;
}
if (subprog[0].tail_call_reachable)
env->prog->aux->tail_call_reachable = true;
/* end of for() loop means the last insn of the 'subprog'
* was reached. Doesn't matter whether it was JA or EXIT
*/
if (frame == 0)
return 0;
depth -= round_up_stack_depth(env, subprog[idx].stack_depth);
frame--;
i = ret_insn[frame];
idx = ret_prog[frame];
goto continue_func;
}
static int check_max_stack_depth(struct bpf_verifier_env *env)
{
struct bpf_subprog_info *si = env->subprog_info;
int ret;
for (int i = 0; i < env->subprog_cnt; i++) {
if (!i || si[i].is_async_cb) {
ret = check_max_stack_depth_subprog(env, i);
if (ret < 0)
return ret;
}
continue;
}
return 0;
}
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
static int get_callee_stack_depth(struct bpf_verifier_env *env,
const struct bpf_insn *insn, int idx)
{
int start = idx + insn->imm + 1, subprog;
subprog = find_subprog(env, start);
if (subprog < 0) {
WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
start);
return -EFAULT;
}
return env->subprog_info[subprog].stack_depth;
}
#endif
static int __check_buffer_access(struct bpf_verifier_env *env,
const char *buf_info,
const struct bpf_reg_state *reg,
int regno, int off, int size)
{
if (off < 0) {
verbose(env,
"R%d invalid %s buffer access: off=%d, size=%d\n",
regno, buf_info, off, size);
return -EACCES;
}
if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
verbose(env,
"R%d invalid variable buffer offset: off=%d, var_off=%s\n",
regno, off, tn_buf);
return -EACCES;
}
return 0;
}
static int check_tp_buffer_access(struct bpf_verifier_env *env,
const struct bpf_reg_state *reg,
int regno, int off, int size)
{
int err;
err = __check_buffer_access(env, "tracepoint", reg, regno, off, size);
if (err)
return err;
if (off + size > env->prog->aux->max_tp_access)
env->prog->aux->max_tp_access = off + size;
return 0;
}
static int check_buffer_access(struct bpf_verifier_env *env,
const struct bpf_reg_state *reg,
int regno, int off, int size,
bool zero_size_allowed,
u32 *max_access)
{
const char *buf_info = type_is_rdonly_mem(reg->type) ? "rdonly" : "rdwr";
int err;
err = __check_buffer_access(env, buf_info, reg, regno, off, size);
if (err)
return err;
if (off + size > *max_access)
*max_access = off + size;
return 0;
}
/* BPF architecture zero extends alu32 ops into 64-bit registesr */
static void zext_32_to_64(struct bpf_reg_state *reg)
{
reg->var_off = tnum_subreg(reg->var_off);
__reg_assign_32_into_64(reg);
}
/* truncate register to smaller size (in bytes)
* must be called with size < BPF_REG_SIZE
*/
static void coerce_reg_to_size(struct bpf_reg_state *reg, int size)
{
u64 mask;
/* clear high bits in bit representation */
reg->var_off = tnum_cast(reg->var_off, size);
/* fix arithmetic bounds */
mask = ((u64)1 << (size * 8)) - 1;
if ((reg->umin_value & ~mask) == (reg->umax_value & ~mask)) {
reg->umin_value &= mask;
reg->umax_value &= mask;
} else {
reg->umin_value = 0;
reg->umax_value = mask;
}
reg->smin_value = reg->umin_value;
reg->smax_value = reg->umax_value;
/* If size is smaller than 32bit register the 32bit register
* values are also truncated so we push 64-bit bounds into
* 32-bit bounds. Above were truncated < 32-bits already.
*/
if (size < 4)
__mark_reg32_unbounded(reg);
reg_bounds_sync(reg);
}
static void set_sext64_default_val(struct bpf_reg_state *reg, int size)
{
if (size == 1) {
reg->smin_value = reg->s32_min_value = S8_MIN;
reg->smax_value = reg->s32_max_value = S8_MAX;
} else if (size == 2) {
reg->smin_value = reg->s32_min_value = S16_MIN;
reg->smax_value = reg->s32_max_value = S16_MAX;
} else {
/* size == 4 */
reg->smin_value = reg->s32_min_value = S32_MIN;
reg->smax_value = reg->s32_max_value = S32_MAX;
}
reg->umin_value = reg->u32_min_value = 0;
reg->umax_value = U64_MAX;
reg->u32_max_value = U32_MAX;
reg->var_off = tnum_unknown;
}
static void coerce_reg_to_size_sx(struct bpf_reg_state *reg, int size)
{
s64 init_s64_max, init_s64_min, s64_max, s64_min, u64_cval;
u64 top_smax_value, top_smin_value;
u64 num_bits = size * 8;
if (tnum_is_const(reg->var_off)) {
u64_cval = reg->var_off.value;
if (size == 1)
reg->var_off = tnum_const((s8)u64_cval);
else if (size == 2)
reg->var_off = tnum_const((s16)u64_cval);
else
/* size == 4 */
reg->var_off = tnum_const((s32)u64_cval);
u64_cval = reg->var_off.value;
reg->smax_value = reg->smin_value = u64_cval;
reg->umax_value = reg->umin_value = u64_cval;
reg->s32_max_value = reg->s32_min_value = u64_cval;
reg->u32_max_value = reg->u32_min_value = u64_cval;
return;
}
top_smax_value = ((u64)reg->smax_value >> num_bits) << num_bits;
top_smin_value = ((u64)reg->smin_value >> num_bits) << num_bits;
if (top_smax_value != top_smin_value)
goto out;
/* find the s64_min and s64_min after sign extension */
if (size == 1) {
init_s64_max = (s8)reg->smax_value;
init_s64_min = (s8)reg->smin_value;
} else if (size == 2) {
init_s64_max = (s16)reg->smax_value;
init_s64_min = (s16)reg->smin_value;
} else {
init_s64_max = (s32)reg->smax_value;
init_s64_min = (s32)reg->smin_value;
}
s64_max = max(init_s64_max, init_s64_min);
s64_min = min(init_s64_max, init_s64_min);
/* both of s64_max/s64_min positive or negative */
if ((s64_max >= 0) == (s64_min >= 0)) {
reg->smin_value = reg->s32_min_value = s64_min;
reg->smax_value = reg->s32_max_value = s64_max;
reg->umin_value = reg->u32_min_value = s64_min;
reg->umax_value = reg->u32_max_value = s64_max;
reg->var_off = tnum_range(s64_min, s64_max);
return;
}
out:
set_sext64_default_val(reg, size);
}
static void set_sext32_default_val(struct bpf_reg_state *reg, int size)
{
if (size == 1) {
reg->s32_min_value = S8_MIN;
reg->s32_max_value = S8_MAX;
} else {
/* size == 2 */
reg->s32_min_value = S16_MIN;
reg->s32_max_value = S16_MAX;
}
reg->u32_min_value = 0;
reg->u32_max_value = U32_MAX;
reg->var_off = tnum_subreg(tnum_unknown);
}
static void coerce_subreg_to_size_sx(struct bpf_reg_state *reg, int size)
{
s32 init_s32_max, init_s32_min, s32_max, s32_min, u32_val;
u32 top_smax_value, top_smin_value;
u32 num_bits = size * 8;
if (tnum_is_const(reg->var_off)) {
u32_val = reg->var_off.value;
if (size == 1)
reg->var_off = tnum_const((s8)u32_val);
else
reg->var_off = tnum_const((s16)u32_val);
u32_val = reg->var_off.value;
reg->s32_min_value = reg->s32_max_value = u32_val;
reg->u32_min_value = reg->u32_max_value = u32_val;
return;
}
top_smax_value = ((u32)reg->s32_max_value >> num_bits) << num_bits;
top_smin_value = ((u32)reg->s32_min_value >> num_bits) << num_bits;
if (top_smax_value != top_smin_value)
goto out;
/* find the s32_min and s32_min after sign extension */
if (size == 1) {
init_s32_max = (s8)reg->s32_max_value;
init_s32_min = (s8)reg->s32_min_value;
} else {
/* size == 2 */
init_s32_max = (s16)reg->s32_max_value;
init_s32_min = (s16)reg->s32_min_value;
}
s32_max = max(init_s32_max, init_s32_min);
s32_min = min(init_s32_max, init_s32_min);
if ((s32_min >= 0) == (s32_max >= 0)) {
reg->s32_min_value = s32_min;
reg->s32_max_value = s32_max;
reg->u32_min_value = (u32)s32_min;
reg->u32_max_value = (u32)s32_max;
reg->var_off = tnum_subreg(tnum_range(s32_min, s32_max));
return;
}
out:
set_sext32_default_val(reg, size);
}
static bool bpf_map_is_rdonly(const struct bpf_map *map)
{
/* A map is considered read-only if the following condition are true:
*
* 1) BPF program side cannot change any of the map content. The
* BPF_F_RDONLY_PROG flag is throughout the lifetime of a map
* and was set at map creation time.
* 2) The map value(s) have been initialized from user space by a
* loader and then "frozen", such that no new map update/delete
* operations from syscall side are possible for the rest of
* the map's lifetime from that point onwards.
* 3) Any parallel/pending map update/delete operations from syscall
* side have been completed. Only after that point, it's safe to
* assume that map value(s) are immutable.
*/
return (map->map_flags & BPF_F_RDONLY_PROG) &&
READ_ONCE(map->frozen) &&
!bpf_map_write_active(map);
}
static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val,
bool is_ldsx)
{
void *ptr;
u64 addr;
int err;
err = map->ops->map_direct_value_addr(map, &addr, off);
if (err)
return err;
ptr = (void *)(long)addr + off;
switch (size) {
case sizeof(u8):
*val = is_ldsx ? (s64)*(s8 *)ptr : (u64)*(u8 *)ptr;
break;
case sizeof(u16):
*val = is_ldsx ? (s64)*(s16 *)ptr : (u64)*(u16 *)ptr;
break;
case sizeof(u32):
*val = is_ldsx ? (s64)*(s32 *)ptr : (u64)*(u32 *)ptr;
break;
case sizeof(u64):
*val = *(u64 *)ptr;
break;
default:
return -EINVAL;
}
return 0;
}
#define BTF_TYPE_SAFE_RCU(__type) __PASTE(__type, __safe_rcu)
#define BTF_TYPE_SAFE_RCU_OR_NULL(__type) __PASTE(__type, __safe_rcu_or_null)
#define BTF_TYPE_SAFE_TRUSTED(__type) __PASTE(__type, __safe_trusted)
#define BTF_TYPE_SAFE_TRUSTED_OR_NULL(__type) __PASTE(__type, __safe_trusted_or_null)
/*
* Allow list few fields as RCU trusted or full trusted.
* This logic doesn't allow mix tagging and will be removed once GCC supports
* btf_type_tag.
*/
/* RCU trusted: these fields are trusted in RCU CS and never NULL */
BTF_TYPE_SAFE_RCU(struct task_struct) {
const cpumask_t *cpus_ptr;
struct css_set __rcu *cgroups;
struct task_struct __rcu *real_parent;
struct task_struct *group_leader;
};
BTF_TYPE_SAFE_RCU(struct cgroup) {
/* cgrp->kn is always accessible as documented in kernel/cgroup/cgroup.c */
struct kernfs_node *kn;
};
BTF_TYPE_SAFE_RCU(struct css_set) {
struct cgroup *dfl_cgrp;
};
/* RCU trusted: these fields are trusted in RCU CS and can be NULL */
BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct) {
struct file __rcu *exe_file;
};
/* skb->sk, req->sk are not RCU protected, but we mark them as such
* because bpf prog accessible sockets are SOCK_RCU_FREE.
*/
BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff) {
struct sock *sk;
};
BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock) {
struct sock *sk;
};
/* full trusted: these fields are trusted even outside of RCU CS and never NULL */
BTF_TYPE_SAFE_TRUSTED(struct bpf_iter_meta) {
struct seq_file *seq;
};
BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task) {
struct bpf_iter_meta *meta;
struct task_struct *task;
};
BTF_TYPE_SAFE_TRUSTED(struct linux_binprm) {
struct file *file;
};
BTF_TYPE_SAFE_TRUSTED(struct file) {
struct inode *f_inode;
};
BTF_TYPE_SAFE_TRUSTED(struct dentry) {
/* no negative dentry-s in places where bpf can see it */
struct inode *d_inode;
};
BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket) {
struct sock *sk;
};
static bool type_is_rcu(struct bpf_verifier_env *env,
struct bpf_reg_state *reg,
const char *field_name, u32 btf_id)
{
BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct task_struct));
BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct cgroup));
BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct css_set));
return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu");
}
static bool type_is_rcu_or_null(struct bpf_verifier_env *env,
struct bpf_reg_state *reg,
const char *field_name, u32 btf_id)
{
BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct));
BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff));
BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock));
return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu_or_null");
}
static bool type_is_trusted(struct bpf_verifier_env *env,
struct bpf_reg_state *reg,
const char *field_name, u32 btf_id)
{
BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter_meta));
BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task));
BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct linux_binprm));
BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct file));
BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct dentry));
return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_trusted");
}
static bool type_is_trusted_or_null(struct bpf_verifier_env *env,
struct bpf_reg_state *reg,
const char *field_name, u32 btf_id)
{
BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket));
return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id,
"__safe_trusted_or_null");
}
static int check_ptr_to_btf_access(struct bpf_verifier_env *env,
struct bpf_reg_state *regs,
int regno, int off, int size,
enum bpf_access_type atype,
int value_regno)
{
struct bpf_reg_state *reg = regs + regno;
const struct btf_type *t = btf_type_by_id(reg->btf, reg->btf_id);
const char *tname = btf_name_by_offset(reg->btf, t->name_off);
const char *field_name = NULL;
enum bpf_type_flag flag = 0;
u32 btf_id = 0;
int ret;
if (!env->allow_ptr_leaks) {
verbose(env,
"'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n",
tname);
return -EPERM;
}
if (!env->prog->gpl_compatible && btf_is_kernel(reg->btf)) {
verbose(env,
"Cannot access kernel 'struct %s' from non-GPL compatible program\n",
tname);
return -EINVAL;
}
if (off < 0) {
verbose(env,
"R%d is ptr_%s invalid negative access: off=%d\n",
regno, tname, off);
return -EACCES;
}
if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
verbose(env,
"R%d is ptr_%s invalid variable offset: off=%d, var_off=%s\n",
regno, tname, off, tn_buf);
return -EACCES;
}
if (reg->type & MEM_USER) {
verbose(env,
"R%d is ptr_%s access user memory: off=%d\n",
regno, tname, off);
return -EACCES;
}
if (reg->type & MEM_PERCPU) {
verbose(env,
"R%d is ptr_%s access percpu memory: off=%d\n",
regno, tname, off);
return -EACCES;
}
if (env->ops->btf_struct_access && !type_is_alloc(reg->type) && atype == BPF_WRITE) {
if (!btf_is_kernel(reg->btf)) {
verbose(env, "verifier internal error: reg->btf must be kernel btf\n");
return -EFAULT;
}
ret = env->ops->btf_struct_access(&env->log, reg, off, size);
} else {
/* Writes are permitted with default btf_struct_access for
* program allocated objects (which always have ref_obj_id > 0),
* but not for untrusted PTR_TO_BTF_ID | MEM_ALLOC.
*/
if (atype != BPF_READ && !type_is_ptr_alloc_obj(reg->type)) {
verbose(env, "only read is supported\n");
return -EACCES;
}
if (type_is_alloc(reg->type) && !type_is_non_owning_ref(reg->type) &&
!(reg->type & MEM_RCU) && !reg->ref_obj_id) {
verbose(env, "verifier internal error: ref_obj_id for allocated object must be non-zero\n");
return -EFAULT;
}
ret = btf_struct_access(&env->log, reg, off, size, atype, &btf_id, &flag, &field_name);
}
if (ret < 0)
return ret;
if (ret != PTR_TO_BTF_ID) {
/* just mark; */
} else if (type_flag(reg->type) & PTR_UNTRUSTED) {
/* If this is an untrusted pointer, all pointers formed by walking it
* also inherit the untrusted flag.
*/
flag = PTR_UNTRUSTED;
} else if (is_trusted_reg(reg) || is_rcu_reg(reg)) {
/* By default any pointer obtained from walking a trusted pointer is no
* longer trusted, unless the field being accessed has explicitly been
* marked as inheriting its parent's state of trust (either full or RCU).
* For example:
* 'cgroups' pointer is untrusted if task->cgroups dereference
* happened in a sleepable program outside of bpf_rcu_read_lock()
* section. In a non-sleepable program it's trusted while in RCU CS (aka MEM_RCU).
* Note bpf_rcu_read_unlock() converts MEM_RCU pointers to PTR_UNTRUSTED.
*
* A regular RCU-protected pointer with __rcu tag can also be deemed
* trusted if we are in an RCU CS. Such pointer can be NULL.
*/
if (type_is_trusted(env, reg, field_name, btf_id)) {
flag |= PTR_TRUSTED;
} else if (type_is_trusted_or_null(env, reg, field_name, btf_id)) {
flag |= PTR_TRUSTED | PTR_MAYBE_NULL;
} else if (in_rcu_cs(env) && !type_may_be_null(reg->type)) {
if (type_is_rcu(env, reg, field_name, btf_id)) {
/* ignore __rcu tag and mark it MEM_RCU */
flag |= MEM_RCU;
} else if (flag & MEM_RCU ||
type_is_rcu_or_null(env, reg, field_name, btf_id)) {
/* __rcu tagged pointers can be NULL */
flag |= MEM_RCU | PTR_MAYBE_NULL;
/* We always trust them */
if (type_is_rcu_or_null(env, reg, field_name, btf_id) &&
flag & PTR_UNTRUSTED)
flag &= ~PTR_UNTRUSTED;
} else if (flag & (MEM_PERCPU | MEM_USER)) {
/* keep as-is */
} else {
/* walking unknown pointers yields old deprecated PTR_TO_BTF_ID */
clear_trusted_flags(&flag);
}
} else {
/*
* If not in RCU CS or MEM_RCU pointer can be NULL then
* aggressively mark as untrusted otherwise such
* pointers will be plain PTR_TO_BTF_ID without flags
* and will be allowed to be passed into helpers for
* compat reasons.
*/
flag = PTR_UNTRUSTED;
}
} else {
/* Old compat. Deprecated */
clear_trusted_flags(&flag);
}
if (atype == BPF_READ && value_regno >= 0)
mark_btf_ld_reg(env, regs, value_regno, ret, reg->btf, btf_id, flag);
return 0;
}
static int check_ptr_to_map_access(struct bpf_verifier_env *env,
struct bpf_reg_state *regs,
int regno, int off, int size,
enum bpf_access_type atype,
int value_regno)
{
struct bpf_reg_state *reg = regs + regno;
struct bpf_map *map = reg->map_ptr;
struct bpf_reg_state map_reg;
enum bpf_type_flag flag = 0;
const struct btf_type *t;
const char *tname;
u32 btf_id;
int ret;
if (!btf_vmlinux) {
verbose(env, "map_ptr access not supported without CONFIG_DEBUG_INFO_BTF\n");
return -ENOTSUPP;
}
if (!map->ops->map_btf_id || !*map->ops->map_btf_id) {
verbose(env, "map_ptr access not supported for map type %d\n",
map->map_type);
return -ENOTSUPP;
}
t = btf_type_by_id(btf_vmlinux, *map->ops->map_btf_id);
tname = btf_name_by_offset(btf_vmlinux, t->name_off);
if (!env->allow_ptr_leaks) {
verbose(env,
"'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n",
tname);
return -EPERM;
}
if (off < 0) {
verbose(env, "R%d is %s invalid negative access: off=%d\n",
regno, tname, off);
return -EACCES;
}
if (atype != BPF_READ) {
verbose(env, "only read from %s is supported\n", tname);
return -EACCES;
}
/* Simulate access to a PTR_TO_BTF_ID */
memset(&map_reg, 0, sizeof(map_reg));
mark_btf_ld_reg(env, &map_reg, 0, PTR_TO_BTF_ID, btf_vmlinux, *map->ops->map_btf_id, 0);
ret = btf_struct_access(&env->log, &map_reg, off, size, atype, &btf_id, &flag, NULL);
if (ret < 0)
return ret;
if (value_regno >= 0)
mark_btf_ld_reg(env, regs, value_regno, ret, btf_vmlinux, btf_id, flag);
return 0;
}
/* Check that the stack access at the given offset is within bounds. The
* maximum valid offset is -1.
*
* The minimum valid offset is -MAX_BPF_STACK for writes, and
* -state->allocated_stack for reads.
*/
static int check_stack_slot_within_bounds(struct bpf_verifier_env *env,
s64 off,
struct bpf_func_state *state,
enum bpf_access_type t)
{
struct bpf_insn_aux_data *aux = &env->insn_aux_data[env->insn_idx];
int min_valid_off, max_bpf_stack;
/* If accessing instruction is a spill/fill from bpf_fastcall pattern,
* add room for all caller saved registers below MAX_BPF_STACK.
* In case if bpf_fastcall rewrite won't happen maximal stack depth
* would be checked by check_max_stack_depth_subprog().
*/
max_bpf_stack = MAX_BPF_STACK;
if (aux->fastcall_pattern)
max_bpf_stack += CALLER_SAVED_REGS * BPF_REG_SIZE;
if (t == BPF_WRITE || env->allow_uninit_stack)
min_valid_off = -max_bpf_stack;
else
min_valid_off = -state->allocated_stack;
if (off < min_valid_off || off > -1)
return -EACCES;
return 0;
}
/* Check that the stack access at 'regno + off' falls within the maximum stack
* bounds.
*
* 'off' includes `regno->offset`, but not its dynamic part (if any).
*/
static int check_stack_access_within_bounds(
struct bpf_verifier_env *env,
int regno, int off, int access_size,
enum bpf_access_src src, enum bpf_access_type type)
{
struct bpf_reg_state *regs = cur_regs(env);
struct bpf_reg_state *reg = regs + regno;
struct bpf_func_state *state = func(env, reg);
s64 min_off, max_off;
int err;
char *err_extra;
if (src == ACCESS_HELPER)
/* We don't know if helpers are reading or writing (or both). */
err_extra = " indirect access to";
else if (type == BPF_READ)
err_extra = " read from";
else
err_extra = " write to";
if (tnum_is_const(reg->var_off)) {
min_off = (s64)reg->var_off.value + off;
max_off = min_off + access_size;
} else {
if (reg->smax_value >= BPF_MAX_VAR_OFF ||
reg->smin_value <= -BPF_MAX_VAR_OFF) {
verbose(env, "invalid unbounded variable-offset%s stack R%d\n",
err_extra, regno);
return -EACCES;
}
min_off = reg->smin_value + off;
max_off = reg->smax_value + off + access_size;
}
err = check_stack_slot_within_bounds(env, min_off, state, type);
if (!err && max_off > 0)
err = -EINVAL; /* out of stack access into non-negative offsets */
if (!err && access_size < 0)
/* access_size should not be negative (or overflow an int); others checks
* along the way should have prevented such an access.
*/
err = -EFAULT; /* invalid negative access size; integer overflow? */
if (err) {
if (tnum_is_const(reg->var_off)) {
verbose(env, "invalid%s stack R%d off=%d size=%d\n",
err_extra, regno, off, access_size);
} else {
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
verbose(env, "invalid variable-offset%s stack R%d var_off=%s off=%d size=%d\n",
err_extra, regno, tn_buf, off, access_size);
}
return err;
}
/* Note that there is no stack access with offset zero, so the needed stack
* size is -min_off, not -min_off+1.
*/
return grow_stack_state(env, state, -min_off /* size */);
}
static bool get_func_retval_range(struct bpf_prog *prog,
struct bpf_retval_range *range)
{
if (prog->type == BPF_PROG_TYPE_LSM &&
prog->expected_attach_type == BPF_LSM_MAC &&
!bpf_lsm_get_retval_range(prog, range)) {
return true;
}
return false;
}
/* check whether memory at (regno + off) is accessible for t = (read | write)
* if t==write, value_regno is a register which value is stored into memory
* if t==read, value_regno is a register which will receive the value from memory
* if t==write && value_regno==-1, some unknown value is stored into memory
* if t==read && value_regno==-1, don't care what we read from memory
*/
static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno,
int off, int bpf_size, enum bpf_access_type t,
int value_regno, bool strict_alignment_once, bool is_ldsx)
{
struct bpf_reg_state *regs = cur_regs(env);
struct bpf_reg_state *reg = regs + regno;
int size, err = 0;
size = bpf_size_to_bytes(bpf_size);
if (size < 0)
return size;
/* alignment checks will add in reg->off themselves */
err = check_ptr_alignment(env, reg, off, size, strict_alignment_once);
if (err)
return err;
/* for access checks, reg->off is just part of off */
off += reg->off;
if (reg->type == PTR_TO_MAP_KEY) {
if (t == BPF_WRITE) {
verbose(env, "write to change key R%d not allowed\n", regno);
return -EACCES;
}
err = check_mem_region_access(env, regno, off, size,
reg->map_ptr->key_size, false);
if (err)
return err;
if (value_regno >= 0)
mark_reg_unknown(env, regs, value_regno);
} else if (reg->type == PTR_TO_MAP_VALUE) {
struct btf_field *kptr_field = NULL;
if (t == BPF_WRITE && value_regno >= 0 &&
is_pointer_value(env, value_regno)) {
verbose(env, "R%d leaks addr into map\n", value_regno);
return -EACCES;
}
err = check_map_access_type(env, regno, off, size, t);
if (err)
return err;
err = check_map_access(env, regno, off, size, false, ACCESS_DIRECT);
if (err)
return err;
if (tnum_is_const(reg->var_off))
kptr_field = btf_record_find(reg->map_ptr->record,
off + reg->var_off.value, BPF_KPTR);
if (kptr_field) {
err = check_map_kptr_access(env, regno, value_regno, insn_idx, kptr_field);
} else if (t == BPF_READ && value_regno >= 0) {
struct bpf_map *map = reg->map_ptr;
/* if map is read-only, track its contents as scalars */
if (tnum_is_const(reg->var_off) &&
bpf_map_is_rdonly(map) &&
map->ops->map_direct_value_addr) {
int map_off = off + reg->var_off.value;
u64 val = 0;
err = bpf_map_direct_read(map, map_off, size,
&val, is_ldsx);
if (err)
return err;
regs[value_regno].type = SCALAR_VALUE;
__mark_reg_known(®s[value_regno], val);
} else {
mark_reg_unknown(env, regs, value_regno);
}
}
} else if (base_type(reg->type) == PTR_TO_MEM) {
bool rdonly_mem = type_is_rdonly_mem(reg->type);
if (type_may_be_null(reg->type)) {
verbose(env, "R%d invalid mem access '%s'\n", regno,
reg_type_str(env, reg->type));
return -EACCES;
}
if (t == BPF_WRITE && rdonly_mem) {
verbose(env, "R%d cannot write into %s\n",
regno, reg_type_str(env, reg->type));
return -EACCES;
}
if (t == BPF_WRITE && value_regno >= 0 &&
is_pointer_value(env, value_regno)) {
verbose(env, "R%d leaks addr into mem\n", value_regno);
return -EACCES;
}
err = check_mem_region_access(env, regno, off, size,
reg->mem_size, false);
if (!err && value_regno >= 0 && (t == BPF_READ || rdonly_mem))
mark_reg_unknown(env, regs, value_regno);
} else if (reg->type == PTR_TO_CTX) {
bool is_retval = false;
struct bpf_retval_range range;
enum bpf_reg_type reg_type = SCALAR_VALUE;
struct btf *btf = NULL;
u32 btf_id = 0;
if (t == BPF_WRITE && value_regno >= 0 &&
is_pointer_value(env, value_regno)) {
verbose(env, "R%d leaks addr into ctx\n", value_regno);
return -EACCES;
}
err = check_ptr_off_reg(env, reg, regno);
if (err < 0)
return err;
err = check_ctx_access(env, insn_idx, off, size, t, ®_type, &btf,
&btf_id, &is_retval, is_ldsx);
if (err)
verbose_linfo(env, insn_idx, "; ");
if (!err && t == BPF_READ && value_regno >= 0) {
/* ctx access returns either a scalar, or a
* PTR_TO_PACKET[_META,_END]. In the latter
* case, we know the offset is zero.
*/
if (reg_type == SCALAR_VALUE) {
if (is_retval && get_func_retval_range(env->prog, &range)) {
err = __mark_reg_s32_range(env, regs, value_regno,
range.minval, range.maxval);
if (err)
return err;
} else {
mark_reg_unknown(env, regs, value_regno);
}
} else {
mark_reg_known_zero(env, regs,
value_regno);
if (type_may_be_null(reg_type))
regs[value_regno].id = ++env->id_gen;
/* A load of ctx field could have different
* actual load size with the one encoded in the
* insn. When the dst is PTR, it is for sure not
* a sub-register.
*/
regs[value_regno].subreg_def = DEF_NOT_SUBREG;
if (base_type(reg_type) == PTR_TO_BTF_ID) {
regs[value_regno].btf = btf;
regs[value_regno].btf_id = btf_id;
}
}
regs[value_regno].type = reg_type;
}
} else if (reg->type == PTR_TO_STACK) {
/* Basic bounds checks. */
err = check_stack_access_within_bounds(env, regno, off, size, ACCESS_DIRECT, t);
if (err)
return err;
if (t == BPF_READ)
err = check_stack_read(env, regno, off, size,
value_regno);
else
err = check_stack_write(env, regno, off, size,
value_regno, insn_idx);
} else if (reg_is_pkt_pointer(reg)) {
if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
verbose(env, "cannot write into packet\n");
return -EACCES;
}
if (t == BPF_WRITE && value_regno >= 0 &&
is_pointer_value(env, value_regno)) {
verbose(env, "R%d leaks addr into packet\n",
value_regno);
return -EACCES;
}
err = check_packet_access(env, regno, off, size, false);
if (!err && t == BPF_READ && value_regno >= 0)
mark_reg_unknown(env, regs, value_regno);
} else if (reg->type == PTR_TO_FLOW_KEYS) {
if (t == BPF_WRITE && value_regno >= 0 &&
is_pointer_value(env, value_regno)) {
verbose(env, "R%d leaks addr into flow keys\n",
value_regno);
return -EACCES;
}
err = check_flow_keys_access(env, off, size);
if (!err && t == BPF_READ && value_regno >= 0)
mark_reg_unknown(env, regs, value_regno);
} else if (type_is_sk_pointer(reg->type)) {
if (t == BPF_WRITE) {
verbose(env, "R%d cannot write into %s\n",
regno, reg_type_str(env, reg->type));
return -EACCES;
}
err = check_sock_access(env, insn_idx, regno, off, size, t);
if (!err && value_regno >= 0)
mark_reg_unknown(env, regs, value_regno);
} else if (reg->type == PTR_TO_TP_BUFFER) {
err = check_tp_buffer_access(env, reg, regno, off, size);
if (!err && t == BPF_READ && value_regno >= 0)
mark_reg_unknown(env, regs, value_regno);
} else if (base_type(reg->type) == PTR_TO_BTF_ID &&
!type_may_be_null(reg->type)) {
err = check_ptr_to_btf_access(env, regs, regno, off, size, t,
value_regno);
} else if (reg->type == CONST_PTR_TO_MAP) {
err = check_ptr_to_map_access(env, regs, regno, off, size, t,
value_regno);
} else if (base_type(reg->type) == PTR_TO_BUF) {
bool rdonly_mem = type_is_rdonly_mem(reg->type);
u32 *max_access;
if (rdonly_mem) {
if (t == BPF_WRITE) {
verbose(env, "R%d cannot write into %s\n",
regno, reg_type_str(env, reg->type));
return -EACCES;
}
max_access = &env->prog->aux->max_rdonly_access;
} else {
max_access = &env->prog->aux->max_rdwr_access;
}
err = check_buffer_access(env, reg, regno, off, size, false,
max_access);
if (!err && value_regno >= 0 && (rdonly_mem || t == BPF_READ))
mark_reg_unknown(env, regs, value_regno);
} else if (reg->type == PTR_TO_ARENA) {
if (t == BPF_READ && value_regno >= 0)
mark_reg_unknown(env, regs, value_regno);
} else {
verbose(env, "R%d invalid mem access '%s'\n", regno,
reg_type_str(env, reg->type));
return -EACCES;
}
if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ &&
regs[value_regno].type == SCALAR_VALUE) {
if (!is_ldsx)
/* b/h/w load zero-extends, mark upper bits as known 0 */
coerce_reg_to_size(®s[value_regno], size);
else
coerce_reg_to_size_sx(®s[value_regno], size);
}
return err;
}
static int save_aux_ptr_type(struct bpf_verifier_env *env, enum bpf_reg_type type,
bool allow_trust_mismatch);
static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn)
{
int load_reg;
int err;
switch (insn->imm) {
case BPF_ADD:
case BPF_ADD | BPF_FETCH:
case BPF_AND:
case BPF_AND | BPF_FETCH:
case BPF_OR:
case BPF_OR | BPF_FETCH:
case BPF_XOR:
case BPF_XOR | BPF_FETCH:
case BPF_XCHG:
case BPF_CMPXCHG:
break;
default:
verbose(env, "BPF_ATOMIC uses invalid atomic opcode %02x\n", insn->imm);
return -EINVAL;
}
if (BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) {
verbose(env, "invalid atomic operand size\n");
return -EINVAL;
}
/* check src1 operand */
err = check_reg_arg(env, insn->src_reg, SRC_OP);
if (err)
return err;
/* check src2 operand */
err = check_reg_arg(env, insn->dst_reg, SRC_OP);
if (err)
return err;
if (insn->imm == BPF_CMPXCHG) {
/* Check comparison of R0 with memory location */
const u32 aux_reg = BPF_REG_0;
err = check_reg_arg(env, aux_reg, SRC_OP);
if (err)
return err;
if (is_pointer_value(env, aux_reg)) {
verbose(env, "R%d leaks addr into mem\n", aux_reg);
return -EACCES;
}
}
if (is_pointer_value(env, insn->src_reg)) {
verbose(env, "R%d leaks addr into mem\n", insn->src_reg);
return -EACCES;
}
if (is_ctx_reg(env, insn->dst_reg) ||
is_pkt_reg(env, insn->dst_reg) ||
is_flow_key_reg(env, insn->dst_reg) ||
is_sk_reg(env, insn->dst_reg) ||
(is_arena_reg(env, insn->dst_reg) && !bpf_jit_supports_insn(insn, true))) {
verbose(env, "BPF_ATOMIC stores into R%d %s is not allowed\n",
insn->dst_reg,
reg_type_str(env, reg_state(env, insn->dst_reg)->type));
return -EACCES;
}
if (insn->imm & BPF_FETCH) {
if (insn->imm == BPF_CMPXCHG)
load_reg = BPF_REG_0;
else
load_reg = insn->src_reg;
/* check and record load of old value */
err = check_reg_arg(env, load_reg, DST_OP);
if (err)
return err;
} else {
/* This instruction accesses a memory location but doesn't
* actually load it into a register.
*/
load_reg = -1;
}
/* Check whether we can read the memory, with second call for fetch
* case to simulate the register fill.
*/
err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
BPF_SIZE(insn->code), BPF_READ, -1, true, false);
if (!err && load_reg >= 0)
err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
BPF_SIZE(insn->code), BPF_READ, load_reg,
true, false);
if (err)
return err;
if (is_arena_reg(env, insn->dst_reg)) {
err = save_aux_ptr_type(env, PTR_TO_ARENA, false);
if (err)
return err;
}
/* Check whether we can write into the same memory. */
err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
BPF_SIZE(insn->code), BPF_WRITE, -1, true, false);
if (err)
return err;
return 0;
}
/* When register 'regno' is used to read the stack (either directly or through
* a helper function) make sure that it's within stack boundary and, depending
* on the access type and privileges, that all elements of the stack are
* initialized.
*
* 'off' includes 'regno->off', but not its dynamic part (if any).
*
* All registers that have been spilled on the stack in the slots within the
* read offsets are marked as read.
*/
static int check_stack_range_initialized(
struct bpf_verifier_env *env, int regno, int off,
int access_size, bool zero_size_allowed,
enum bpf_access_src type, struct bpf_call_arg_meta *meta)
{
struct bpf_reg_state *reg = reg_state(env, regno);
struct bpf_func_state *state = func(env, reg);
int err, min_off, max_off, i, j, slot, spi;
char *err_extra = type == ACCESS_HELPER ? " indirect" : "";
enum bpf_access_type bounds_check_type;
/* Some accesses can write anything into the stack, others are
* read-only.
*/
bool clobber = false;
if (access_size == 0 && !zero_size_allowed) {
verbose(env, "invalid zero-sized read\n");
return -EACCES;
}
if (type == ACCESS_HELPER) {
/* The bounds checks for writes are more permissive than for
* reads. However, if raw_mode is not set, we'll do extra
* checks below.
*/
bounds_check_type = BPF_WRITE;
clobber = true;
} else {
bounds_check_type = BPF_READ;
}
err = check_stack_access_within_bounds(env, regno, off, access_size,
type, bounds_check_type);
if (err)
return err;
if (tnum_is_const(reg->var_off)) {
min_off = max_off = reg->var_off.value + off;
} else {
/* Variable offset is prohibited for unprivileged mode for
* simplicity since it requires corresponding support in
* Spectre masking for stack ALU.
* See also retrieve_ptr_limit().
*/
if (!env->bypass_spec_v1) {
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
verbose(env, "R%d%s variable offset stack access prohibited for !root, var_off=%s\n",
regno, err_extra, tn_buf);
return -EACCES;
}
/* Only initialized buffer on stack is allowed to be accessed
* with variable offset. With uninitialized buffer it's hard to
* guarantee that whole memory is marked as initialized on
* helper return since specific bounds are unknown what may
* cause uninitialized stack leaking.
*/
if (meta && meta->raw_mode)
meta = NULL;
min_off = reg->smin_value + off;
max_off = reg->smax_value + off;
}
if (meta && meta->raw_mode) {
/* Ensure we won't be overwriting dynptrs when simulating byte
* by byte access in check_helper_call using meta.access_size.
* This would be a problem if we have a helper in the future
* which takes:
*
* helper(uninit_mem, len, dynptr)
*
* Now, uninint_mem may overlap with dynptr pointer. Hence, it
* may end up writing to dynptr itself when touching memory from
* arg 1. This can be relaxed on a case by case basis for known
* safe cases, but reject due to the possibilitiy of aliasing by
* default.
*/
for (i = min_off; i < max_off + access_size; i++) {
int stack_off = -i - 1;
spi = __get_spi(i);
/* raw_mode may write past allocated_stack */
if (state->allocated_stack <= stack_off)
continue;
if (state->stack[spi].slot_type[stack_off % BPF_REG_SIZE] == STACK_DYNPTR) {
verbose(env, "potential write to dynptr at off=%d disallowed\n", i);
return -EACCES;
}
}
meta->access_size = access_size;
meta->regno = regno;
return 0;
}
for (i = min_off; i < max_off + access_size; i++) {
u8 *stype;
slot = -i - 1;
spi = slot / BPF_REG_SIZE;
if (state->allocated_stack <= slot) {
verbose(env, "verifier bug: allocated_stack too small");
return -EFAULT;
}
stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
if (*stype == STACK_MISC)
goto mark;
if ((*stype == STACK_ZERO) ||
(*stype == STACK_INVALID && env->allow_uninit_stack)) {
if (clobber) {
/* helper can write anything into the stack */
*stype = STACK_MISC;
}
goto mark;
}
if (is_spilled_reg(&state->stack[spi]) &&
(state->stack[spi].spilled_ptr.type == SCALAR_VALUE ||
env->allow_ptr_leaks)) {
if (clobber) {
__mark_reg_unknown(env, &state->stack[spi].spilled_ptr);
for (j = 0; j < BPF_REG_SIZE; j++)
scrub_spilled_slot(&state->stack[spi].slot_type[j]);
}
goto mark;
}
if (tnum_is_const(reg->var_off)) {
verbose(env, "invalid%s read from stack R%d off %d+%d size %d\n",
err_extra, regno, min_off, i - min_off, access_size);
} else {
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
verbose(env, "invalid%s read from stack R%d var_off %s+%d size %d\n",
err_extra, regno, tn_buf, i - min_off, access_size);
}
return -EACCES;
mark:
/* reading any byte out of 8-byte 'spill_slot' will cause
* the whole slot to be marked as 'read'
*/
mark_reg_read(env, &state->stack[spi].spilled_ptr,
state->stack[spi].spilled_ptr.parent,
REG_LIVE_READ64);
/* We do not set REG_LIVE_WRITTEN for stack slot, as we can not
* be sure that whether stack slot is written to or not. Hence,
* we must still conservatively propagate reads upwards even if
* helper may write to the entire memory range.
*/
}
return 0;
}
static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
int access_size, bool zero_size_allowed,
struct bpf_call_arg_meta *meta)
{
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
u32 *max_access;
switch (base_type(reg->type)) {
case PTR_TO_PACKET:
case PTR_TO_PACKET_META:
return check_packet_access(env, regno, reg->off, access_size,
zero_size_allowed);
case PTR_TO_MAP_KEY:
if (meta && meta->raw_mode) {
verbose(env, "R%d cannot write into %s\n", regno,
reg_type_str(env, reg->type));
return -EACCES;
}
return check_mem_region_access(env, regno, reg->off, access_size,
reg->map_ptr->key_size, false);
case PTR_TO_MAP_VALUE:
if (check_map_access_type(env, regno, reg->off, access_size,
meta && meta->raw_mode ? BPF_WRITE :
BPF_READ))
return -EACCES;
return check_map_access(env, regno, reg->off, access_size,
zero_size_allowed, ACCESS_HELPER);
case PTR_TO_MEM:
if (type_is_rdonly_mem(reg->type)) {
if (meta && meta->raw_mode) {
verbose(env, "R%d cannot write into %s\n", regno,
reg_type_str(env, reg->type));
return -EACCES;
}
}
return check_mem_region_access(env, regno, reg->off,
access_size, reg->mem_size,
zero_size_allowed);
case PTR_TO_BUF:
if (type_is_rdonly_mem(reg->type)) {
if (meta && meta->raw_mode) {
verbose(env, "R%d cannot write into %s\n", regno,
reg_type_str(env, reg->type));
return -EACCES;
}
max_access = &env->prog->aux->max_rdonly_access;
} else {
max_access = &env->prog->aux->max_rdwr_access;
}
return check_buffer_access(env, reg, regno, reg->off,
access_size, zero_size_allowed,
max_access);
case PTR_TO_STACK:
return check_stack_range_initialized(
env,
regno, reg->off, access_size,
zero_size_allowed, ACCESS_HELPER, meta);
case PTR_TO_BTF_ID:
return check_ptr_to_btf_access(env, regs, regno, reg->off,
access_size, BPF_READ, -1);
case PTR_TO_CTX:
/* in case the function doesn't know how to access the context,
* (because we are in a program of type SYSCALL for example), we
* can not statically check its size.
* Dynamically check it now.
*/
if (!env->ops->convert_ctx_access) {
enum bpf_access_type atype = meta && meta->raw_mode ? BPF_WRITE : BPF_READ;
int offset = access_size - 1;
/* Allow zero-byte read from PTR_TO_CTX */
if (access_size == 0)
return zero_size_allowed ? 0 : -EACCES;
return check_mem_access(env, env->insn_idx, regno, offset, BPF_B,
atype, -1, false, false);
}
fallthrough;
default: /* scalar_value or invalid ptr */
/* Allow zero-byte read from NULL, regardless of pointer type */
if (zero_size_allowed && access_size == 0 &&
register_is_null(reg))
return 0;
verbose(env, "R%d type=%s ", regno,
reg_type_str(env, reg->type));
verbose(env, "expected=%s\n", reg_type_str(env, PTR_TO_STACK));
return -EACCES;
}
}
/* verify arguments to helpers or kfuncs consisting of a pointer and an access
* size.
*
* @regno is the register containing the access size. regno-1 is the register
* containing the pointer.
*/
static int check_mem_size_reg(struct bpf_verifier_env *env,
struct bpf_reg_state *reg, u32 regno,
bool zero_size_allowed,
struct bpf_call_arg_meta *meta)
{
int err;
/* This is used to refine r0 return value bounds for helpers
* that enforce this value as an upper bound on return values.
* See do_refine_retval_range() for helpers that can refine
* the return value. C type of helper is u32 so we pull register
* bound from umax_value however, if negative verifier errors
* out. Only upper bounds can be learned because retval is an
* int type and negative retvals are allowed.
*/
meta->msize_max_value = reg->umax_value;
/* The register is SCALAR_VALUE; the access check
* happens using its boundaries.
*/
if (!tnum_is_const(reg->var_off))
/* For unprivileged variable accesses, disable raw
* mode so that the program is required to
* initialize all the memory that the helper could
* just partially fill up.
*/
meta = NULL;
if (reg->smin_value < 0) {
verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n",
regno);
return -EACCES;
}
if (reg->umin_value == 0 && !zero_size_allowed) {
verbose(env, "R%d invalid zero-sized read: u64=[%lld,%lld]\n",
regno, reg->umin_value, reg->umax_value);
return -EACCES;
}
if (reg->umax_value >= BPF_MAX_VAR_SIZ) {
verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
regno);
return -EACCES;
}
err = check_helper_mem_access(env, regno - 1,
reg->umax_value,
zero_size_allowed, meta);
if (!err)
err = mark_chain_precision(env, regno);
return err;
}
static int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
u32 regno, u32 mem_size)
{
bool may_be_null = type_may_be_null(reg->type);
struct bpf_reg_state saved_reg;
struct bpf_call_arg_meta meta;
int err;
if (register_is_null(reg))
return 0;
memset(&meta, 0, sizeof(meta));
/* Assuming that the register contains a value check if the memory
* access is safe. Temporarily save and restore the register's state as
* the conversion shouldn't be visible to a caller.
*/
if (may_be_null) {
saved_reg = *reg;
mark_ptr_not_null_reg(reg);
}
err = check_helper_mem_access(env, regno, mem_size, true, &meta);
/* Check access for BPF_WRITE */
meta.raw_mode = true;
err = err ?: check_helper_mem_access(env, regno, mem_size, true, &meta);
if (may_be_null)
*reg = saved_reg;
return err;
}
static int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
u32 regno)
{
struct bpf_reg_state *mem_reg = &cur_regs(env)[regno - 1];
bool may_be_null = type_may_be_null(mem_reg->type);
struct bpf_reg_state saved_reg;
struct bpf_call_arg_meta meta;
int err;
WARN_ON_ONCE(regno < BPF_REG_2 || regno > BPF_REG_5);
memset(&meta, 0, sizeof(meta));
if (may_be_null) {
saved_reg = *mem_reg;
mark_ptr_not_null_reg(mem_reg);
}
err = check_mem_size_reg(env, reg, regno, true, &meta);
/* Check access for BPF_WRITE */
meta.raw_mode = true;
err = err ?: check_mem_size_reg(env, reg, regno, true, &meta);
if (may_be_null)
*mem_reg = saved_reg;
return err;
}
/* Implementation details:
* bpf_map_lookup returns PTR_TO_MAP_VALUE_OR_NULL.
* bpf_obj_new returns PTR_TO_BTF_ID | MEM_ALLOC | PTR_MAYBE_NULL.
* Two bpf_map_lookups (even with the same key) will have different reg->id.
* Two separate bpf_obj_new will also have different reg->id.
* For traditional PTR_TO_MAP_VALUE or PTR_TO_BTF_ID | MEM_ALLOC, the verifier
* clears reg->id after value_or_null->value transition, since the verifier only
* cares about the range of access to valid map value pointer and doesn't care
* about actual address of the map element.
* For maps with 'struct bpf_spin_lock' inside map value the verifier keeps
* reg->id > 0 after value_or_null->value transition. By doing so
* two bpf_map_lookups will be considered two different pointers that
* point to different bpf_spin_locks. Likewise for pointers to allocated objects
* returned from bpf_obj_new.
* The verifier allows taking only one bpf_spin_lock at a time to avoid
* dead-locks.
* Since only one bpf_spin_lock is allowed the checks are simpler than
* reg_is_refcounted() logic. The verifier needs to remember only
* one spin_lock instead of array of acquired_refs.
* cur_state->active_lock remembers which map value element or allocated
* object got locked and clears it after bpf_spin_unlock.
*/
static int process_spin_lock(struct bpf_verifier_env *env, int regno,
bool is_lock)
{
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
struct bpf_verifier_state *cur = env->cur_state;
bool is_const = tnum_is_const(reg->var_off);
u64 val = reg->var_off.value;
struct bpf_map *map = NULL;
struct btf *btf = NULL;
struct btf_record *rec;
if (!is_const) {
verbose(env,
"R%d doesn't have constant offset. bpf_spin_lock has to be at the constant offset\n",
regno);
return -EINVAL;
}
if (reg->type == PTR_TO_MAP_VALUE) {
map = reg->map_ptr;
if (!map->btf) {
verbose(env,
"map '%s' has to have BTF in order to use bpf_spin_lock\n",
map->name);
return -EINVAL;
}
} else {
btf = reg->btf;
}
rec = reg_btf_record(reg);
if (!btf_record_has_field(rec, BPF_SPIN_LOCK)) {
verbose(env, "%s '%s' has no valid bpf_spin_lock\n", map ? "map" : "local",
map ? map->name : "kptr");
return -EINVAL;
}
if (rec->spin_lock_off != val + reg->off) {
verbose(env, "off %lld doesn't point to 'struct bpf_spin_lock' that is at %d\n",
val + reg->off, rec->spin_lock_off);
return -EINVAL;
}
if (is_lock) {
if (cur->active_lock.ptr) {
verbose(env,
"Locking two bpf_spin_locks are not allowed\n");
return -EINVAL;
}
if (map)
cur->active_lock.ptr = map;
else
cur->active_lock.ptr = btf;
cur->active_lock.id = reg->id;
} else {
void *ptr;
if (map)
ptr = map;
else
ptr = btf;
if (!cur->active_lock.ptr) {
verbose(env, "bpf_spin_unlock without taking a lock\n");
return -EINVAL;
}
if (cur->active_lock.ptr != ptr ||
cur->active_lock.id != reg->id) {
verbose(env, "bpf_spin_unlock of different lock\n");
return -EINVAL;
}
invalidate_non_owning_refs(env);
cur->active_lock.ptr = NULL;
cur->active_lock.id = 0;
}
return 0;
}
static int process_timer_func(struct bpf_verifier_env *env, int regno,
struct bpf_call_arg_meta *meta)
{
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
bool is_const = tnum_is_const(reg->var_off);
struct bpf_map *map = reg->map_ptr;
u64 val = reg->var_off.value;
if (!is_const) {
verbose(env,
"R%d doesn't have constant offset. bpf_timer has to be at the constant offset\n",
regno);
return -EINVAL;
}
if (!map->btf) {
verbose(env, "map '%s' has to have BTF in order to use bpf_timer\n",
map->name);
return -EINVAL;
}
if (!btf_record_has_field(map->record, BPF_TIMER)) {
verbose(env, "map '%s' has no valid bpf_timer\n", map->name);
return -EINVAL;
}
if (map->record->timer_off != val + reg->off) {
verbose(env, "off %lld doesn't point to 'struct bpf_timer' that is at %d\n",
val + reg->off, map->record->timer_off);
return -EINVAL;
}
if (meta->map_ptr) {
verbose(env, "verifier bug. Two map pointers in a timer helper\n");
return -EFAULT;
}
meta->map_uid = reg->map_uid;
meta->map_ptr = map;
return 0;
}
static int process_wq_func(struct bpf_verifier_env *env, int regno,
struct bpf_kfunc_call_arg_meta *meta)
{
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
struct bpf_map *map = reg->map_ptr;
u64 val = reg->var_off.value;
if (map->record->wq_off != val + reg->off) {
verbose(env, "off %lld doesn't point to 'struct bpf_wq' that is at %d\n",
val + reg->off, map->record->wq_off);
return -EINVAL;
}
meta->map.uid = reg->map_uid;
meta->map.ptr = map;
return 0;
}
static int process_kptr_func(struct bpf_verifier_env *env, int regno,
struct bpf_call_arg_meta *meta)
{
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
struct btf_field *kptr_field;
struct bpf_map *map_ptr;
struct btf_record *rec;
u32 kptr_off;
if (type_is_ptr_alloc_obj(reg->type)) {
rec = reg_btf_record(reg);
} else { /* PTR_TO_MAP_VALUE */
map_ptr = reg->map_ptr;
if (!map_ptr->btf) {
verbose(env, "map '%s' has to have BTF in order to use bpf_kptr_xchg\n",
map_ptr->name);
return -EINVAL;
}
rec = map_ptr->record;
meta->map_ptr = map_ptr;
}
if (!tnum_is_const(reg->var_off)) {
verbose(env,
"R%d doesn't have constant offset. kptr has to be at the constant offset\n",
regno);
return -EINVAL;
}
if (!btf_record_has_field(rec, BPF_KPTR)) {
verbose(env, "R%d has no valid kptr\n", regno);
return -EINVAL;
}
kptr_off = reg->off + reg->var_off.value;
kptr_field = btf_record_find(rec, kptr_off, BPF_KPTR);
if (!kptr_field) {
verbose(env, "off=%d doesn't point to kptr\n", kptr_off);
return -EACCES;
}
if (kptr_field->type != BPF_KPTR_REF && kptr_field->type != BPF_KPTR_PERCPU) {
verbose(env, "off=%d kptr isn't referenced kptr\n", kptr_off);
return -EACCES;
}
meta->kptr_field = kptr_field;
return 0;
}
/* There are two register types representing a bpf_dynptr, one is PTR_TO_STACK
* which points to a stack slot, and the other is CONST_PTR_TO_DYNPTR.
*
* In both cases we deal with the first 8 bytes, but need to mark the next 8
* bytes as STACK_DYNPTR in case of PTR_TO_STACK. In case of
* CONST_PTR_TO_DYNPTR, we are guaranteed to get the beginning of the object.
*
* Mutability of bpf_dynptr is at two levels, one is at the level of struct
* bpf_dynptr itself, i.e. whether the helper is receiving a pointer to struct
* bpf_dynptr or pointer to const struct bpf_dynptr. In the former case, it can
* mutate the view of the dynptr and also possibly destroy it. In the latter
* case, it cannot mutate the bpf_dynptr itself but it can still mutate the
* memory that dynptr points to.
*
* The verifier will keep track both levels of mutation (bpf_dynptr's in
* reg->type and the memory's in reg->dynptr.type), but there is no support for
* readonly dynptr view yet, hence only the first case is tracked and checked.
*
* This is consistent with how C applies the const modifier to a struct object,
* where the pointer itself inside bpf_dynptr becomes const but not what it
* points to.
*
* Helpers which do not mutate the bpf_dynptr set MEM_RDONLY in their argument
* type, and declare it as 'const struct bpf_dynptr *' in their prototype.
*/
static int process_dynptr_func(struct bpf_verifier_env *env, int regno, int insn_idx,
enum bpf_arg_type arg_type, int clone_ref_obj_id)
{
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
int err;
if (reg->type != PTR_TO_STACK && reg->type != CONST_PTR_TO_DYNPTR) {
verbose(env,
"arg#%d expected pointer to stack or const struct bpf_dynptr\n",
regno);
return -EINVAL;
}
/* MEM_UNINIT and MEM_RDONLY are exclusive, when applied to an
* ARG_PTR_TO_DYNPTR (or ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_*):
*/
if ((arg_type & (MEM_UNINIT | MEM_RDONLY)) == (MEM_UNINIT | MEM_RDONLY)) {
verbose(env, "verifier internal error: misconfigured dynptr helper type flags\n");
return -EFAULT;
}
/* MEM_UNINIT - Points to memory that is an appropriate candidate for
* constructing a mutable bpf_dynptr object.
*
* Currently, this is only possible with PTR_TO_STACK
* pointing to a region of at least 16 bytes which doesn't
* contain an existing bpf_dynptr.
*
* MEM_RDONLY - Points to a initialized bpf_dynptr that will not be
* mutated or destroyed. However, the memory it points to
* may be mutated.
*
* None - Points to a initialized dynptr that can be mutated and
* destroyed, including mutation of the memory it points
* to.
*/
if (arg_type & MEM_UNINIT) {
int i;
if (!is_dynptr_reg_valid_uninit(env, reg)) {
verbose(env, "Dynptr has to be an uninitialized dynptr\n");
return -EINVAL;
}
/* we write BPF_DW bits (8 bytes) at a time */
for (i = 0; i < BPF_DYNPTR_SIZE; i += 8) {
err = check_mem_access(env, insn_idx, regno,
i, BPF_DW, BPF_WRITE, -1, false, false);
if (err)
return err;
}
err = mark_stack_slots_dynptr(env, reg, arg_type, insn_idx, clone_ref_obj_id);
} else /* MEM_RDONLY and None case from above */ {
/* For the reg->type == PTR_TO_STACK case, bpf_dynptr is never const */
if (reg->type == CONST_PTR_TO_DYNPTR && !(arg_type & MEM_RDONLY)) {
verbose(env, "cannot pass pointer to const bpf_dynptr, the helper mutates it\n");
return -EINVAL;
}
if (!is_dynptr_reg_valid_init(env, reg)) {
verbose(env,
"Expected an initialized dynptr as arg #%d\n",
regno);
return -EINVAL;
}
/* Fold modifiers (in this case, MEM_RDONLY) when checking expected type */
if (!is_dynptr_type_expected(env, reg, arg_type & ~MEM_RDONLY)) {
verbose(env,
"Expected a dynptr of type %s as arg #%d\n",
dynptr_type_str(arg_to_dynptr_type(arg_type)), regno);
return -EINVAL;
}
err = mark_dynptr_read(env, reg);
}
return err;
}
static u32 iter_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int spi)
{
struct bpf_func_state *state = func(env, reg);
return state->stack[spi].spilled_ptr.ref_obj_id;
}
static bool is_iter_kfunc(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->kfunc_flags & (KF_ITER_NEW | KF_ITER_NEXT | KF_ITER_DESTROY);
}
static bool is_iter_new_kfunc(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->kfunc_flags & KF_ITER_NEW;
}
static bool is_iter_next_kfunc(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->kfunc_flags & KF_ITER_NEXT;
}
static bool is_iter_destroy_kfunc(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->kfunc_flags & KF_ITER_DESTROY;
}
static bool is_kfunc_arg_iter(struct bpf_kfunc_call_arg_meta *meta, int arg_idx,
const struct btf_param *arg)
{
/* btf_check_iter_kfuncs() guarantees that first argument of any iter
* kfunc is iter state pointer
*/
if (is_iter_kfunc(meta))
return arg_idx == 0;
/* iter passed as an argument to a generic kfunc */
return btf_param_match_suffix(meta->btf, arg, "__iter");
}
static int process_iter_arg(struct bpf_verifier_env *env, int regno, int insn_idx,
struct bpf_kfunc_call_arg_meta *meta)
{
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
const struct btf_type *t;
int spi, err, i, nr_slots, btf_id;
/* For iter_{new,next,destroy} functions, btf_check_iter_kfuncs()
* ensures struct convention, so we wouldn't need to do any BTF
* validation here. But given iter state can be passed as a parameter
* to any kfunc, if arg has "__iter" suffix, we need to be a bit more
* conservative here.
*/
btf_id = btf_check_iter_arg(meta->btf, meta->func_proto, regno - 1);
if (btf_id < 0) {
verbose(env, "expected valid iter pointer as arg #%d\n", regno);
return -EINVAL;
}
t = btf_type_by_id(meta->btf, btf_id);
nr_slots = t->size / BPF_REG_SIZE;
if (is_iter_new_kfunc(meta)) {
/* bpf_iter_<type>_new() expects pointer to uninit iter state */
if (!is_iter_reg_valid_uninit(env, reg, nr_slots)) {
verbose(env, "expected uninitialized iter_%s as arg #%d\n",
iter_type_str(meta->btf, btf_id), regno);
return -EINVAL;
}
for (i = 0; i < nr_slots * 8; i += BPF_REG_SIZE) {
err = check_mem_access(env, insn_idx, regno,
i, BPF_DW, BPF_WRITE, -1, false, false);
if (err)
return err;
}
err = mark_stack_slots_iter(env, meta, reg, insn_idx, meta->btf, btf_id, nr_slots);
if (err)
return err;
} else {
/* iter_next() or iter_destroy(), as well as any kfunc
* accepting iter argument, expect initialized iter state
*/
err = is_iter_reg_valid_init(env, reg, meta->btf, btf_id, nr_slots);
switch (err) {
case 0:
break;
case -EINVAL:
verbose(env, "expected an initialized iter_%s as arg #%d\n",
iter_type_str(meta->btf, btf_id), regno);
return err;
case -EPROTO:
verbose(env, "expected an RCU CS when using %s\n", meta->func_name);
return err;
default:
return err;
}
spi = iter_get_spi(env, reg, nr_slots);
if (spi < 0)
return spi;
err = mark_iter_read(env, reg, spi, nr_slots);
if (err)
return err;
/* remember meta->iter info for process_iter_next_call() */
meta->iter.spi = spi;
meta->iter.frameno = reg->frameno;
meta->ref_obj_id = iter_ref_obj_id(env, reg, spi);
if (is_iter_destroy_kfunc(meta)) {
err = unmark_stack_slots_iter(env, reg, nr_slots);
if (err)
return err;
}
}
return 0;
}
/* Look for a previous loop entry at insn_idx: nearest parent state
* stopped at insn_idx with callsites matching those in cur->frame.
*/
static struct bpf_verifier_state *find_prev_entry(struct bpf_verifier_env *env,
struct bpf_verifier_state *cur,
int insn_idx)
{
struct bpf_verifier_state_list *sl;
struct bpf_verifier_state *st;
/* Explored states are pushed in stack order, most recent states come first */
sl = *explored_state(env, insn_idx);
for (; sl; sl = sl->next) {
/* If st->branches != 0 state is a part of current DFS verification path,
* hence cur & st for a loop.
*/
st = &sl->state;
if (st->insn_idx == insn_idx && st->branches && same_callsites(st, cur) &&
st->dfs_depth < cur->dfs_depth)
return st;
}
return NULL;
}
static void reset_idmap_scratch(struct bpf_verifier_env *env);
static bool regs_exact(const struct bpf_reg_state *rold,
const struct bpf_reg_state *rcur,
struct bpf_idmap *idmap);
static void maybe_widen_reg(struct bpf_verifier_env *env,
struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
struct bpf_idmap *idmap)
{
if (rold->type != SCALAR_VALUE)
return;
if (rold->type != rcur->type)
return;
if (rold->precise || rcur->precise || regs_exact(rold, rcur, idmap))
return;
__mark_reg_unknown(env, rcur);
}
static int widen_imprecise_scalars(struct bpf_verifier_env *env,
struct bpf_verifier_state *old,
struct bpf_verifier_state *cur)
{
struct bpf_func_state *fold, *fcur;
int i, fr;
reset_idmap_scratch(env);
for (fr = old->curframe; fr >= 0; fr--) {
fold = old->frame[fr];
fcur = cur->frame[fr];
for (i = 0; i < MAX_BPF_REG; i++)
maybe_widen_reg(env,
&fold->regs[i],
&fcur->regs[i],
&env->idmap_scratch);
for (i = 0; i < fold->allocated_stack / BPF_REG_SIZE; i++) {
if (!is_spilled_reg(&fold->stack[i]) ||
!is_spilled_reg(&fcur->stack[i]))
continue;
maybe_widen_reg(env,
&fold->stack[i].spilled_ptr,
&fcur->stack[i].spilled_ptr,
&env->idmap_scratch);
}
}
return 0;
}
static struct bpf_reg_state *get_iter_from_state(struct bpf_verifier_state *cur_st,
struct bpf_kfunc_call_arg_meta *meta)
{
int iter_frameno = meta->iter.frameno;
int iter_spi = meta->iter.spi;
return &cur_st->frame[iter_frameno]->stack[iter_spi].spilled_ptr;
}
/* process_iter_next_call() is called when verifier gets to iterator's next
* "method" (e.g., bpf_iter_num_next() for numbers iterator) call. We'll refer
* to it as just "iter_next()" in comments below.
*
* BPF verifier relies on a crucial contract for any iter_next()
* implementation: it should *eventually* return NULL, and once that happens
* it should keep returning NULL. That is, once iterator exhausts elements to
* iterate, it should never reset or spuriously return new elements.
*
* With the assumption of such contract, process_iter_next_call() simulates
* a fork in the verifier state to validate loop logic correctness and safety
* without having to simulate infinite amount of iterations.
*
* In current state, we first assume that iter_next() returned NULL and
* iterator state is set to DRAINED (BPF_ITER_STATE_DRAINED). In such
* conditions we should not form an infinite loop and should eventually reach
* exit.
*
* Besides that, we also fork current state and enqueue it for later
* verification. In a forked state we keep iterator state as ACTIVE
* (BPF_ITER_STATE_ACTIVE) and assume non-NULL return from iter_next(). We
* also bump iteration depth to prevent erroneous infinite loop detection
* later on (see iter_active_depths_differ() comment for details). In this
* state we assume that we'll eventually loop back to another iter_next()
* calls (it could be in exactly same location or in some other instruction,
* it doesn't matter, we don't make any unnecessary assumptions about this,
* everything revolves around iterator state in a stack slot, not which
* instruction is calling iter_next()). When that happens, we either will come
* to iter_next() with equivalent state and can conclude that next iteration
* will proceed in exactly the same way as we just verified, so it's safe to
* assume that loop converges. If not, we'll go on another iteration
* simulation with a different input state, until all possible starting states
* are validated or we reach maximum number of instructions limit.
*
* This way, we will either exhaustively discover all possible input states
* that iterator loop can start with and eventually will converge, or we'll
* effectively regress into bounded loop simulation logic and either reach
* maximum number of instructions if loop is not provably convergent, or there
* is some statically known limit on number of iterations (e.g., if there is
* an explicit `if n > 100 then break;` statement somewhere in the loop).
*
* Iteration convergence logic in is_state_visited() relies on exact
* states comparison, which ignores read and precision marks.
* This is necessary because read and precision marks are not finalized
* while in the loop. Exact comparison might preclude convergence for
* simple programs like below:
*
* i = 0;
* while(iter_next(&it))
* i++;
*
* At each iteration step i++ would produce a new distinct state and
* eventually instruction processing limit would be reached.
*
* To avoid such behavior speculatively forget (widen) range for
* imprecise scalar registers, if those registers were not precise at the
* end of the previous iteration and do not match exactly.
*
* This is a conservative heuristic that allows to verify wide range of programs,
* however it precludes verification of programs that conjure an
* imprecise value on the first loop iteration and use it as precise on a second.
* For example, the following safe program would fail to verify:
*
* struct bpf_num_iter it;
* int arr[10];
* int i = 0, a = 0;
* bpf_iter_num_new(&it, 0, 10);
* while (bpf_iter_num_next(&it)) {
* if (a == 0) {
* a = 1;
* i = 7; // Because i changed verifier would forget
* // it's range on second loop entry.
* } else {
* arr[i] = 42; // This would fail to verify.
* }
* }
* bpf_iter_num_destroy(&it);
*/
static int process_iter_next_call(struct bpf_verifier_env *env, int insn_idx,
struct bpf_kfunc_call_arg_meta *meta)
{
struct bpf_verifier_state *cur_st = env->cur_state, *queued_st, *prev_st;
struct bpf_func_state *cur_fr = cur_st->frame[cur_st->curframe], *queued_fr;
struct bpf_reg_state *cur_iter, *queued_iter;
BTF_TYPE_EMIT(struct bpf_iter);
cur_iter = get_iter_from_state(cur_st, meta);
if (cur_iter->iter.state != BPF_ITER_STATE_ACTIVE &&
cur_iter->iter.state != BPF_ITER_STATE_DRAINED) {
verbose(env, "verifier internal error: unexpected iterator state %d (%s)\n",
cur_iter->iter.state, iter_state_str(cur_iter->iter.state));
return -EFAULT;
}
if (cur_iter->iter.state == BPF_ITER_STATE_ACTIVE) {
/* Because iter_next() call is a checkpoint is_state_visitied()
* should guarantee parent state with same call sites and insn_idx.
*/
if (!cur_st->parent || cur_st->parent->insn_idx != insn_idx ||
!same_callsites(cur_st->parent, cur_st)) {
verbose(env, "bug: bad parent state for iter next call");
return -EFAULT;
}
/* Note cur_st->parent in the call below, it is necessary to skip
* checkpoint created for cur_st by is_state_visited()
* right at this instruction.
*/
prev_st = find_prev_entry(env, cur_st->parent, insn_idx);
/* branch out active iter state */
queued_st = push_stack(env, insn_idx + 1, insn_idx, false);
if (!queued_st)
return -ENOMEM;
queued_iter = get_iter_from_state(queued_st, meta);
queued_iter->iter.state = BPF_ITER_STATE_ACTIVE;
queued_iter->iter.depth++;
if (prev_st)
widen_imprecise_scalars(env, prev_st, queued_st);
queued_fr = queued_st->frame[queued_st->curframe];
mark_ptr_not_null_reg(&queued_fr->regs[BPF_REG_0]);
}
/* switch to DRAINED state, but keep the depth unchanged */
/* mark current iter state as drained and assume returned NULL */
cur_iter->iter.state = BPF_ITER_STATE_DRAINED;
__mark_reg_const_zero(env, &cur_fr->regs[BPF_REG_0]);
return 0;
}
static bool arg_type_is_mem_size(enum bpf_arg_type type)
{
return type == ARG_CONST_SIZE ||
type == ARG_CONST_SIZE_OR_ZERO;
}
static bool arg_type_is_raw_mem(enum bpf_arg_type type)
{
return base_type(type) == ARG_PTR_TO_MEM &&
type & MEM_UNINIT;
}
static bool arg_type_is_release(enum bpf_arg_type type)
{
return type & OBJ_RELEASE;
}
static bool arg_type_is_dynptr(enum bpf_arg_type type)
{
return base_type(type) == ARG_PTR_TO_DYNPTR;
}
static int resolve_map_arg_type(struct bpf_verifier_env *env,
const struct bpf_call_arg_meta *meta,
enum bpf_arg_type *arg_type)
{
if (!meta->map_ptr) {
/* kernel subsystem misconfigured verifier */
verbose(env, "invalid map_ptr to access map->type\n");
return -EACCES;
}
switch (meta->map_ptr->map_type) {
case BPF_MAP_TYPE_SOCKMAP:
case BPF_MAP_TYPE_SOCKHASH:
if (*arg_type == ARG_PTR_TO_MAP_VALUE) {
*arg_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON;
} else {
verbose(env, "invalid arg_type for sockmap/sockhash\n");
return -EINVAL;
}
break;
case BPF_MAP_TYPE_BLOOM_FILTER:
if (meta->func_id == BPF_FUNC_map_peek_elem)
*arg_type = ARG_PTR_TO_MAP_VALUE;
break;
default:
break;
}
return 0;
}
struct bpf_reg_types {
const enum bpf_reg_type types[10];
u32 *btf_id;
};
static const struct bpf_reg_types sock_types = {
.types = {
PTR_TO_SOCK_COMMON,
PTR_TO_SOCKET,
PTR_TO_TCP_SOCK,
PTR_TO_XDP_SOCK,
},
};
#ifdef CONFIG_NET
static const struct bpf_reg_types btf_id_sock_common_types = {
.types = {
PTR_TO_SOCK_COMMON,
PTR_TO_SOCKET,
PTR_TO_TCP_SOCK,
PTR_TO_XDP_SOCK,
PTR_TO_BTF_ID,
PTR_TO_BTF_ID | PTR_TRUSTED,
},
.btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
};
#endif
static const struct bpf_reg_types mem_types = {
.types = {
PTR_TO_STACK,
PTR_TO_PACKET,
PTR_TO_PACKET_META,
PTR_TO_MAP_KEY,
PTR_TO_MAP_VALUE,
PTR_TO_MEM,
PTR_TO_MEM | MEM_RINGBUF,
PTR_TO_BUF,
PTR_TO_BTF_ID | PTR_TRUSTED,
},
};
static const struct bpf_reg_types spin_lock_types = {
.types = {
PTR_TO_MAP_VALUE,
PTR_TO_BTF_ID | MEM_ALLOC,
}
};
static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } };
static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } };
static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } };
static const struct bpf_reg_types ringbuf_mem_types = { .types = { PTR_TO_MEM | MEM_RINGBUF } };
static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } };
static const struct bpf_reg_types btf_ptr_types = {
.types = {
PTR_TO_BTF_ID,
PTR_TO_BTF_ID | PTR_TRUSTED,
PTR_TO_BTF_ID | MEM_RCU,
},
};
static const struct bpf_reg_types percpu_btf_ptr_types = {
.types = {
PTR_TO_BTF_ID | MEM_PERCPU,
PTR_TO_BTF_ID | MEM_PERCPU | MEM_RCU,
PTR_TO_BTF_ID | MEM_PERCPU | PTR_TRUSTED,
}
};
static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } };
static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } };
static const struct bpf_reg_types const_str_ptr_types = { .types = { PTR_TO_MAP_VALUE } };
static const struct bpf_reg_types timer_types = { .types = { PTR_TO_MAP_VALUE } };
static const struct bpf_reg_types kptr_xchg_dest_types = {
.types = {
PTR_TO_MAP_VALUE,
PTR_TO_BTF_ID | MEM_ALLOC
}
};
static const struct bpf_reg_types dynptr_types = {
.types = {
PTR_TO_STACK,
CONST_PTR_TO_DYNPTR,
}
};
static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
[ARG_PTR_TO_MAP_KEY] = &mem_types,
[ARG_PTR_TO_MAP_VALUE] = &mem_types,
[ARG_CONST_SIZE] = &scalar_types,
[ARG_CONST_SIZE_OR_ZERO] = &scalar_types,
[ARG_CONST_ALLOC_SIZE_OR_ZERO] = &scalar_types,
[ARG_CONST_MAP_PTR] = &const_map_ptr_types,
[ARG_PTR_TO_CTX] = &context_types,
[ARG_PTR_TO_SOCK_COMMON] = &sock_types,
#ifdef CONFIG_NET
[ARG_PTR_TO_BTF_ID_SOCK_COMMON] = &btf_id_sock_common_types,
#endif
[ARG_PTR_TO_SOCKET] = &fullsock_types,
[ARG_PTR_TO_BTF_ID] = &btf_ptr_types,
[ARG_PTR_TO_SPIN_LOCK] = &spin_lock_types,
[ARG_PTR_TO_MEM] = &mem_types,
[ARG_PTR_TO_RINGBUF_MEM] = &ringbuf_mem_types,
[ARG_PTR_TO_PERCPU_BTF_ID] = &percpu_btf_ptr_types,
[ARG_PTR_TO_FUNC] = &func_ptr_types,
[ARG_PTR_TO_STACK] = &stack_ptr_types,
[ARG_PTR_TO_CONST_STR] = &const_str_ptr_types,
[ARG_PTR_TO_TIMER] = &timer_types,
[ARG_KPTR_XCHG_DEST] = &kptr_xchg_dest_types,
[ARG_PTR_TO_DYNPTR] = &dynptr_types,
};
static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
enum bpf_arg_type arg_type,
const u32 *arg_btf_id,
struct bpf_call_arg_meta *meta)
{
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
enum bpf_reg_type expected, type = reg->type;
const struct bpf_reg_types *compatible;
int i, j;
compatible = compatible_reg_types[base_type(arg_type)];
if (!compatible) {
verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type);
return -EFAULT;
}
/* ARG_PTR_TO_MEM + RDONLY is compatible with PTR_TO_MEM and PTR_TO_MEM + RDONLY,
* but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM and NOT with PTR_TO_MEM + RDONLY
*
* Same for MAYBE_NULL:
*
* ARG_PTR_TO_MEM + MAYBE_NULL is compatible with PTR_TO_MEM and PTR_TO_MEM + MAYBE_NULL,
* but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM but NOT with PTR_TO_MEM + MAYBE_NULL
*
* ARG_PTR_TO_MEM is compatible with PTR_TO_MEM that is tagged with a dynptr type.
*
* Therefore we fold these flags depending on the arg_type before comparison.
*/
if (arg_type & MEM_RDONLY)
type &= ~MEM_RDONLY;
if (arg_type & PTR_MAYBE_NULL)
type &= ~PTR_MAYBE_NULL;
if (base_type(arg_type) == ARG_PTR_TO_MEM)
type &= ~DYNPTR_TYPE_FLAG_MASK;
/* Local kptr types are allowed as the source argument of bpf_kptr_xchg */
if (meta->func_id == BPF_FUNC_kptr_xchg && type_is_alloc(type) && regno == BPF_REG_2) {
type &= ~MEM_ALLOC;
type &= ~MEM_PERCPU;
}
for (i = 0; i < ARRAY_SIZE(compatible->types); i++) {
expected = compatible->types[i];
if (expected == NOT_INIT)
break;
if (type == expected)
goto found;
}
verbose(env, "R%d type=%s expected=", regno, reg_type_str(env, reg->type));
for (j = 0; j + 1 < i; j++)
verbose(env, "%s, ", reg_type_str(env, compatible->types[j]));
verbose(env, "%s\n", reg_type_str(env, compatible->types[j]));
return -EACCES;
found:
if (base_type(reg->type) != PTR_TO_BTF_ID)
return 0;
if (compatible == &mem_types) {
if (!(arg_type & MEM_RDONLY)) {
verbose(env,
"%s() may write into memory pointed by R%d type=%s\n",
func_id_name(meta->func_id),
regno, reg_type_str(env, reg->type));
return -EACCES;
}
return 0;
}
switch ((int)reg->type) {
case PTR_TO_BTF_ID:
case PTR_TO_BTF_ID | PTR_TRUSTED:
case PTR_TO_BTF_ID | PTR_TRUSTED | PTR_MAYBE_NULL:
case PTR_TO_BTF_ID | MEM_RCU:
case PTR_TO_BTF_ID | PTR_MAYBE_NULL:
case PTR_TO_BTF_ID | PTR_MAYBE_NULL | MEM_RCU:
{
/* For bpf_sk_release, it needs to match against first member
* 'struct sock_common', hence make an exception for it. This
* allows bpf_sk_release to work for multiple socket types.
*/
bool strict_type_match = arg_type_is_release(arg_type) &&
meta->func_id != BPF_FUNC_sk_release;
if (type_may_be_null(reg->type) &&
(!type_may_be_null(arg_type) || arg_type_is_release(arg_type))) {
verbose(env, "Possibly NULL pointer passed to helper arg%d\n", regno);
return -EACCES;
}
if (!arg_btf_id) {
if (!compatible->btf_id) {
verbose(env, "verifier internal error: missing arg compatible BTF ID\n");
return -EFAULT;
}
arg_btf_id = compatible->btf_id;
}
if (meta->func_id == BPF_FUNC_kptr_xchg) {
if (map_kptr_match_type(env, meta->kptr_field, reg, regno))
return -EACCES;
} else {
if (arg_btf_id == BPF_PTR_POISON) {
verbose(env, "verifier internal error:");
verbose(env, "R%d has non-overwritten BPF_PTR_POISON type\n",
regno);
return -EACCES;
}
if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->off,
btf_vmlinux, *arg_btf_id,
strict_type_match)) {
verbose(env, "R%d is of type %s but %s is expected\n",
regno, btf_type_name(reg->btf, reg->btf_id),
btf_type_name(btf_vmlinux, *arg_btf_id));
return -EACCES;
}
}
break;
}
case PTR_TO_BTF_ID | MEM_ALLOC:
case PTR_TO_BTF_ID | MEM_PERCPU | MEM_ALLOC:
if (meta->func_id != BPF_FUNC_spin_lock && meta->func_id != BPF_FUNC_spin_unlock &&
meta->func_id != BPF_FUNC_kptr_xchg) {
verbose(env, "verifier internal error: unimplemented handling of MEM_ALLOC\n");
return -EFAULT;
}
/* Check if local kptr in src arg matches kptr in dst arg */
if (meta->func_id == BPF_FUNC_kptr_xchg && regno == BPF_REG_2) {
if (map_kptr_match_type(env, meta->kptr_field, reg, regno))
return -EACCES;
}
break;
case PTR_TO_BTF_ID | MEM_PERCPU:
case PTR_TO_BTF_ID | MEM_PERCPU | MEM_RCU:
case PTR_TO_BTF_ID | MEM_PERCPU | PTR_TRUSTED:
/* Handled by helper specific checks */
break;
default:
verbose(env, "verifier internal error: invalid PTR_TO_BTF_ID register for type match\n");
return -EFAULT;
}
return 0;
}
static struct btf_field *
reg_find_field_offset(const struct bpf_reg_state *reg, s32 off, u32 fields)
{
struct btf_field *field;
struct btf_record *rec;
rec = reg_btf_record(reg);
if (!rec)
return NULL;
field = btf_record_find(rec, off, fields);
if (!field)
return NULL;
return field;
}
static int check_func_arg_reg_off(struct bpf_verifier_env *env,
const struct bpf_reg_state *reg, int regno,
enum bpf_arg_type arg_type)
{
u32 type = reg->type;
/* When referenced register is passed to release function, its fixed
* offset must be 0.
*
* We will check arg_type_is_release reg has ref_obj_id when storing
* meta->release_regno.
*/
if (arg_type_is_release(arg_type)) {
/* ARG_PTR_TO_DYNPTR with OBJ_RELEASE is a bit special, as it
* may not directly point to the object being released, but to
* dynptr pointing to such object, which might be at some offset
* on the stack. In that case, we simply to fallback to the
* default handling.
*/
if (arg_type_is_dynptr(arg_type) && type == PTR_TO_STACK)
return 0;
/* Doing check_ptr_off_reg check for the offset will catch this
* because fixed_off_ok is false, but checking here allows us
* to give the user a better error message.
*/
if (reg->off) {
verbose(env, "R%d must have zero offset when passed to release func or trusted arg to kfunc\n",
regno);
return -EINVAL;
}
return __check_ptr_off_reg(env, reg, regno, false);
}
switch (type) {
/* Pointer types where both fixed and variable offset is explicitly allowed: */
case PTR_TO_STACK:
case PTR_TO_PACKET:
case PTR_TO_PACKET_META:
case PTR_TO_MAP_KEY:
case PTR_TO_MAP_VALUE:
case PTR_TO_MEM:
case PTR_TO_MEM | MEM_RDONLY:
case PTR_TO_MEM | MEM_RINGBUF:
case PTR_TO_BUF:
case PTR_TO_BUF | MEM_RDONLY:
case PTR_TO_ARENA:
case SCALAR_VALUE:
return 0;
/* All the rest must be rejected, except PTR_TO_BTF_ID which allows
* fixed offset.
*/
case PTR_TO_BTF_ID:
case PTR_TO_BTF_ID | MEM_ALLOC:
case PTR_TO_BTF_ID | PTR_TRUSTED:
case PTR_TO_BTF_ID | MEM_RCU:
case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF:
case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF | MEM_RCU:
/* When referenced PTR_TO_BTF_ID is passed to release function,
* its fixed offset must be 0. In the other cases, fixed offset
* can be non-zero. This was already checked above. So pass
* fixed_off_ok as true to allow fixed offset for all other
* cases. var_off always must be 0 for PTR_TO_BTF_ID, hence we
* still need to do checks instead of returning.
*/
return __check_ptr_off_reg(env, reg, regno, true);
default:
return __check_ptr_off_reg(env, reg, regno, false);
}
}
static struct bpf_reg_state *get_dynptr_arg_reg(struct bpf_verifier_env *env,
const struct bpf_func_proto *fn,
struct bpf_reg_state *regs)
{
struct bpf_reg_state *state = NULL;
int i;
for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++)
if (arg_type_is_dynptr(fn->arg_type[i])) {
if (state) {
verbose(env, "verifier internal error: multiple dynptr args\n");
return NULL;
}
state = ®s[BPF_REG_1 + i];
}
if (!state)
verbose(env, "verifier internal error: no dynptr arg found\n");
return state;
}
static int dynptr_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
struct bpf_func_state *state = func(env, reg);
int spi;
if (reg->type == CONST_PTR_TO_DYNPTR)
return reg->id;
spi = dynptr_get_spi(env, reg);
if (spi < 0)
return spi;
return state->stack[spi].spilled_ptr.id;
}
static int dynptr_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
struct bpf_func_state *state = func(env, reg);
int spi;
if (reg->type == CONST_PTR_TO_DYNPTR)
return reg->ref_obj_id;
spi = dynptr_get_spi(env, reg);
if (spi < 0)
return spi;
return state->stack[spi].spilled_ptr.ref_obj_id;
}
static enum bpf_dynptr_type dynptr_get_type(struct bpf_verifier_env *env,
struct bpf_reg_state *reg)
{
struct bpf_func_state *state = func(env, reg);
int spi;
if (reg->type == CONST_PTR_TO_DYNPTR)
return reg->dynptr.type;
spi = __get_spi(reg->off);
if (spi < 0) {
verbose(env, "verifier internal error: invalid spi when querying dynptr type\n");
return BPF_DYNPTR_TYPE_INVALID;
}
return state->stack[spi].spilled_ptr.dynptr.type;
}
static int check_reg_const_str(struct bpf_verifier_env *env,
struct bpf_reg_state *reg, u32 regno)
{
struct bpf_map *map = reg->map_ptr;
int err;
int map_off;
u64 map_addr;
char *str_ptr;
if (reg->type != PTR_TO_MAP_VALUE)
return -EINVAL;
if (!bpf_map_is_rdonly(map)) {
verbose(env, "R%d does not point to a readonly map'\n", regno);
return -EACCES;
}
if (!tnum_is_const(reg->var_off)) {
verbose(env, "R%d is not a constant address'\n", regno);
return -EACCES;
}
if (!map->ops->map_direct_value_addr) {
verbose(env, "no direct value access support for this map type\n");
return -EACCES;
}
err = check_map_access(env, regno, reg->off,
map->value_size - reg->off, false,
ACCESS_HELPER);
if (err)
return err;
map_off = reg->off + reg->var_off.value;
err = map->ops->map_direct_value_addr(map, &map_addr, map_off);
if (err) {
verbose(env, "direct value access on string failed\n");
return err;
}
str_ptr = (char *)(long)(map_addr);
if (!strnchr(str_ptr + map_off, map->value_size - map_off, 0)) {
verbose(env, "string is not zero-terminated\n");
return -EINVAL;
}
return 0;
}
static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
struct bpf_call_arg_meta *meta,
const struct bpf_func_proto *fn,
int insn_idx)
{
u32 regno = BPF_REG_1 + arg;
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
enum bpf_arg_type arg_type = fn->arg_type[arg];
enum bpf_reg_type type = reg->type;
u32 *arg_btf_id = NULL;
int err = 0;
if (arg_type == ARG_DONTCARE)
return 0;
err = check_reg_arg(env, regno, SRC_OP);
if (err)
return err;
if (arg_type == ARG_ANYTHING) {
if (is_pointer_value(env, regno)) {
verbose(env, "R%d leaks addr into helper function\n",
regno);
return -EACCES;
}
return 0;
}
if (type_is_pkt_pointer(type) &&
!may_access_direct_pkt_data(env, meta, BPF_READ)) {
verbose(env, "helper access to the packet is not allowed\n");
return -EACCES;
}
if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE) {
err = resolve_map_arg_type(env, meta, &arg_type);
if (err)
return err;
}
if (register_is_null(reg) && type_may_be_null(arg_type))
/* A NULL register has a SCALAR_VALUE type, so skip
* type checking.
*/
goto skip_type_check;
/* arg_btf_id and arg_size are in a union. */
if (base_type(arg_type) == ARG_PTR_TO_BTF_ID ||
base_type(arg_type) == ARG_PTR_TO_SPIN_LOCK)
arg_btf_id = fn->arg_btf_id[arg];
err = check_reg_type(env, regno, arg_type, arg_btf_id, meta);
if (err)
return err;
err = check_func_arg_reg_off(env, reg, regno, arg_type);
if (err)
return err;
skip_type_check:
if (arg_type_is_release(arg_type)) {
if (arg_type_is_dynptr(arg_type)) {
struct bpf_func_state *state = func(env, reg);
int spi;
/* Only dynptr created on stack can be released, thus
* the get_spi and stack state checks for spilled_ptr
* should only be done before process_dynptr_func for
* PTR_TO_STACK.
*/
if (reg->type == PTR_TO_STACK) {
spi = dynptr_get_spi(env, reg);
if (spi < 0 || !state->stack[spi].spilled_ptr.ref_obj_id) {
verbose(env, "arg %d is an unacquired reference\n", regno);
return -EINVAL;
}
} else {
verbose(env, "cannot release unowned const bpf_dynptr\n");
return -EINVAL;
}
} else if (!reg->ref_obj_id && !register_is_null(reg)) {
verbose(env, "R%d must be referenced when passed to release function\n",
regno);
return -EINVAL;
}
if (meta->release_regno) {
verbose(env, "verifier internal error: more than one release argument\n");
return -EFAULT;
}
meta->release_regno = regno;
}
if (reg->ref_obj_id && base_type(arg_type) != ARG_KPTR_XCHG_DEST) {
if (meta->ref_obj_id) {
verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n",
regno, reg->ref_obj_id,
meta->ref_obj_id);
return -EFAULT;
}
meta->ref_obj_id = reg->ref_obj_id;
}
switch (base_type(arg_type)) {
case ARG_CONST_MAP_PTR:
/* bpf_map_xxx(map_ptr) call: remember that map_ptr */
if (meta->map_ptr) {
/* Use map_uid (which is unique id of inner map) to reject:
* inner_map1 = bpf_map_lookup_elem(outer_map, key1)
* inner_map2 = bpf_map_lookup_elem(outer_map, key2)
* if (inner_map1 && inner_map2) {
* timer = bpf_map_lookup_elem(inner_map1);
* if (timer)
* // mismatch would have been allowed
* bpf_timer_init(timer, inner_map2);
* }
*
* Comparing map_ptr is enough to distinguish normal and outer maps.
*/
if (meta->map_ptr != reg->map_ptr ||
meta->map_uid != reg->map_uid) {
verbose(env,
"timer pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n",
meta->map_uid, reg->map_uid);
return -EINVAL;
}
}
meta->map_ptr = reg->map_ptr;
meta->map_uid = reg->map_uid;
break;
case ARG_PTR_TO_MAP_KEY:
/* bpf_map_xxx(..., map_ptr, ..., key) call:
* check that [key, key + map->key_size) are within
* stack limits and initialized
*/
if (!meta->map_ptr) {
/* in function declaration map_ptr must come before
* map_key, so that it's verified and known before
* we have to check map_key here. Otherwise it means
* that kernel subsystem misconfigured verifier
*/
verbose(env, "invalid map_ptr to access map->key\n");
return -EACCES;
}
err = check_helper_mem_access(env, regno,
meta->map_ptr->key_size, false,
NULL);
break;
case ARG_PTR_TO_MAP_VALUE:
if (type_may_be_null(arg_type) && register_is_null(reg))
return 0;
/* bpf_map_xxx(..., map_ptr, ..., value) call:
* check [value, value + map->value_size) validity
*/
if (!meta->map_ptr) {
/* kernel subsystem misconfigured verifier */
verbose(env, "invalid map_ptr to access map->value\n");
return -EACCES;
}
meta->raw_mode = arg_type & MEM_UNINIT;
err = check_helper_mem_access(env, regno,
meta->map_ptr->value_size, false,
meta);
break;
case ARG_PTR_TO_PERCPU_BTF_ID:
if (!reg->btf_id) {
verbose(env, "Helper has invalid btf_id in R%d\n", regno);
return -EACCES;
}
meta->ret_btf = reg->btf;
meta->ret_btf_id = reg->btf_id;
break;
case ARG_PTR_TO_SPIN_LOCK:
if (in_rbtree_lock_required_cb(env)) {
verbose(env, "can't spin_{lock,unlock} in rbtree cb\n");
return -EACCES;
}
if (meta->func_id == BPF_FUNC_spin_lock) {
err = process_spin_lock(env, regno, true);
if (err)
return err;
} else if (meta->func_id == BPF_FUNC_spin_unlock) {
err = process_spin_lock(env, regno, false);
if (err)
return err;
} else {
verbose(env, "verifier internal error\n");
return -EFAULT;
}
break;
case ARG_PTR_TO_TIMER:
err = process_timer_func(env, regno, meta);
if (err)
return err;
break;
case ARG_PTR_TO_FUNC:
meta->subprogno = reg->subprogno;
break;
case ARG_PTR_TO_MEM:
/* The access to this pointer is only checked when we hit the
* next is_mem_size argument below.
*/
meta->raw_mode = arg_type & MEM_UNINIT;
if (arg_type & MEM_FIXED_SIZE) {
err = check_helper_mem_access(env, regno, fn->arg_size[arg], false, meta);
if (err)
return err;
if (arg_type & MEM_ALIGNED)
err = check_ptr_alignment(env, reg, 0, fn->arg_size[arg], true);
}
break;
case ARG_CONST_SIZE:
err = check_mem_size_reg(env, reg, regno, false, meta);
break;
case ARG_CONST_SIZE_OR_ZERO:
err = check_mem_size_reg(env, reg, regno, true, meta);
break;
case ARG_PTR_TO_DYNPTR:
err = process_dynptr_func(env, regno, insn_idx, arg_type, 0);
if (err)
return err;
break;
case ARG_CONST_ALLOC_SIZE_OR_ZERO:
if (!tnum_is_const(reg->var_off)) {
verbose(env, "R%d is not a known constant'\n",
regno);
return -EACCES;
}
meta->mem_size = reg->var_off.value;
err = mark_chain_precision(env, regno);
if (err)
return err;
break;
case ARG_PTR_TO_CONST_STR:
{
err = check_reg_const_str(env, reg, regno);
if (err)
return err;
break;
}
case ARG_KPTR_XCHG_DEST:
err = process_kptr_func(env, regno, meta);
if (err)
return err;
break;
}
return err;
}
static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id)
{
enum bpf_attach_type eatype = env->prog->expected_attach_type;
enum bpf_prog_type type = resolve_prog_type(env->prog);
if (func_id != BPF_FUNC_map_update_elem &&
func_id != BPF_FUNC_map_delete_elem)
return false;
/* It's not possible to get access to a locked struct sock in these
* contexts, so updating is safe.
*/
switch (type) {
case BPF_PROG_TYPE_TRACING:
if (eatype == BPF_TRACE_ITER)
return true;
break;
case BPF_PROG_TYPE_SOCK_OPS:
/* map_update allowed only via dedicated helpers with event type checks */
if (func_id == BPF_FUNC_map_delete_elem)
return true;
break;
case BPF_PROG_TYPE_SOCKET_FILTER:
case BPF_PROG_TYPE_SCHED_CLS:
case BPF_PROG_TYPE_SCHED_ACT:
case BPF_PROG_TYPE_XDP:
case BPF_PROG_TYPE_SK_REUSEPORT:
case BPF_PROG_TYPE_FLOW_DISSECTOR:
case BPF_PROG_TYPE_SK_LOOKUP:
return true;
default:
break;
}
verbose(env, "cannot update sockmap in this context\n");
return false;
}
static bool allow_tail_call_in_subprogs(struct bpf_verifier_env *env)
{
return env->prog->jit_requested &&
bpf_jit_supports_subprog_tailcalls();
}
static int check_map_func_compatibility(struct bpf_verifier_env *env,
struct bpf_map *map, int func_id)
{
if (!map)
return 0;
/* We need a two way check, first is from map perspective ... */
switch (map->map_type) {
case BPF_MAP_TYPE_PROG_ARRAY:
if (func_id != BPF_FUNC_tail_call)
goto error;
break;
case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
if (func_id != BPF_FUNC_perf_event_read &&
func_id != BPF_FUNC_perf_event_output &&
func_id != BPF_FUNC_skb_output &&
func_id != BPF_FUNC_perf_event_read_value &&
func_id != BPF_FUNC_xdp_output)
goto error;
break;
case BPF_MAP_TYPE_RINGBUF:
if (func_id != BPF_FUNC_ringbuf_output &&
func_id != BPF_FUNC_ringbuf_reserve &&
func_id != BPF_FUNC_ringbuf_query &&
func_id != BPF_FUNC_ringbuf_reserve_dynptr &&
func_id != BPF_FUNC_ringbuf_submit_dynptr &&
func_id != BPF_FUNC_ringbuf_discard_dynptr)
goto error;
break;
case BPF_MAP_TYPE_USER_RINGBUF:
if (func_id != BPF_FUNC_user_ringbuf_drain)
goto error;
break;
case BPF_MAP_TYPE_STACK_TRACE:
if (func_id != BPF_FUNC_get_stackid)
goto error;
break;
case BPF_MAP_TYPE_CGROUP_ARRAY:
if (func_id != BPF_FUNC_skb_under_cgroup &&
func_id != BPF_FUNC_current_task_under_cgroup)
goto error;
break;
case BPF_MAP_TYPE_CGROUP_STORAGE:
case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
if (func_id != BPF_FUNC_get_local_storage)
goto error;
break;
case BPF_MAP_TYPE_DEVMAP:
case BPF_MAP_TYPE_DEVMAP_HASH:
if (func_id != BPF_FUNC_redirect_map &&
func_id != BPF_FUNC_map_lookup_elem)
goto error;
break;
/* Restrict bpf side of cpumap and xskmap, open when use-cases
* appear.
*/
case BPF_MAP_TYPE_CPUMAP:
if (func_id != BPF_FUNC_redirect_map)
goto error;
break;
case BPF_MAP_TYPE_XSKMAP:
if (func_id != BPF_FUNC_redirect_map &&
func_id != BPF_FUNC_map_lookup_elem)
goto error;
break;
case BPF_MAP_TYPE_ARRAY_OF_MAPS:
case BPF_MAP_TYPE_HASH_OF_MAPS:
if (func_id != BPF_FUNC_map_lookup_elem)
goto error;
break;
case BPF_MAP_TYPE_SOCKMAP:
if (func_id != BPF_FUNC_sk_redirect_map &&
func_id != BPF_FUNC_sock_map_update &&
func_id != BPF_FUNC_msg_redirect_map &&
func_id != BPF_FUNC_sk_select_reuseport &&
func_id != BPF_FUNC_map_lookup_elem &&
!may_update_sockmap(env, func_id))
goto error;
break;
case BPF_MAP_TYPE_SOCKHASH:
if (func_id != BPF_FUNC_sk_redirect_hash &&
func_id != BPF_FUNC_sock_hash_update &&
func_id != BPF_FUNC_msg_redirect_hash &&
func_id != BPF_FUNC_sk_select_reuseport &&
func_id != BPF_FUNC_map_lookup_elem &&
!may_update_sockmap(env, func_id))
goto error;
break;
case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
if (func_id != BPF_FUNC_sk_select_reuseport)
goto error;
break;
case BPF_MAP_TYPE_QUEUE:
case BPF_MAP_TYPE_STACK:
if (func_id != BPF_FUNC_map_peek_elem &&
func_id != BPF_FUNC_map_pop_elem &&
func_id != BPF_FUNC_map_push_elem)
goto error;
break;
case BPF_MAP_TYPE_SK_STORAGE:
if (func_id != BPF_FUNC_sk_storage_get &&
func_id != BPF_FUNC_sk_storage_delete &&
func_id != BPF_FUNC_kptr_xchg)
goto error;
break;
case BPF_MAP_TYPE_INODE_STORAGE:
if (func_id != BPF_FUNC_inode_storage_get &&
func_id != BPF_FUNC_inode_storage_delete &&
func_id != BPF_FUNC_kptr_xchg)
goto error;
break;
case BPF_MAP_TYPE_TASK_STORAGE:
if (func_id != BPF_FUNC_task_storage_get &&
func_id != BPF_FUNC_task_storage_delete &&
func_id != BPF_FUNC_kptr_xchg)
goto error;
break;
case BPF_MAP_TYPE_CGRP_STORAGE:
if (func_id != BPF_FUNC_cgrp_storage_get &&
func_id != BPF_FUNC_cgrp_storage_delete &&
func_id != BPF_FUNC_kptr_xchg)
goto error;
break;
case BPF_MAP_TYPE_BLOOM_FILTER:
if (func_id != BPF_FUNC_map_peek_elem &&
func_id != BPF_FUNC_map_push_elem)
goto error;
break;
default:
break;
}
/* ... and second from the function itself. */
switch (func_id) {
case BPF_FUNC_tail_call:
if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
goto error;
if (env->subprog_cnt > 1 && !allow_tail_call_in_subprogs(env)) {
verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
return -EINVAL;
}
break;
case BPF_FUNC_perf_event_read:
case BPF_FUNC_perf_event_output:
case BPF_FUNC_perf_event_read_value:
case BPF_FUNC_skb_output:
case BPF_FUNC_xdp_output:
if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
goto error;
break;
case BPF_FUNC_ringbuf_output:
case BPF_FUNC_ringbuf_reserve:
case BPF_FUNC_ringbuf_query:
case BPF_FUNC_ringbuf_reserve_dynptr:
case BPF_FUNC_ringbuf_submit_dynptr:
case BPF_FUNC_ringbuf_discard_dynptr:
if (map->map_type != BPF_MAP_TYPE_RINGBUF)
goto error;
break;
case BPF_FUNC_user_ringbuf_drain:
if (map->map_type != BPF_MAP_TYPE_USER_RINGBUF)
goto error;
break;
case BPF_FUNC_get_stackid:
if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
goto error;
break;
case BPF_FUNC_current_task_under_cgroup:
case BPF_FUNC_skb_under_cgroup:
if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
goto error;
break;
case BPF_FUNC_redirect_map:
if (map->map_type != BPF_MAP_TYPE_DEVMAP &&
map->map_type != BPF_MAP_TYPE_DEVMAP_HASH &&
map->map_type != BPF_MAP_TYPE_CPUMAP &&
map->map_type != BPF_MAP_TYPE_XSKMAP)
goto error;
break;
case BPF_FUNC_sk_redirect_map:
case BPF_FUNC_msg_redirect_map:
case BPF_FUNC_sock_map_update:
if (map->map_type != BPF_MAP_TYPE_SOCKMAP)
goto error;
break;
case BPF_FUNC_sk_redirect_hash:
case BPF_FUNC_msg_redirect_hash:
case BPF_FUNC_sock_hash_update:
if (map->map_type != BPF_MAP_TYPE_SOCKHASH)
goto error;
break;
case BPF_FUNC_get_local_storage:
if (map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE &&
map->map_type != BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
goto error;
break;
case BPF_FUNC_sk_select_reuseport:
if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY &&
map->map_type != BPF_MAP_TYPE_SOCKMAP &&
map->map_type != BPF_MAP_TYPE_SOCKHASH)
goto error;
break;
case BPF_FUNC_map_pop_elem:
if (map->map_type != BPF_MAP_TYPE_QUEUE &&
map->map_type != BPF_MAP_TYPE_STACK)
goto error;
break;
case BPF_FUNC_map_peek_elem:
case BPF_FUNC_map_push_elem:
if (map->map_type != BPF_MAP_TYPE_QUEUE &&
map->map_type != BPF_MAP_TYPE_STACK &&
map->map_type != BPF_MAP_TYPE_BLOOM_FILTER)
goto error;
break;
case BPF_FUNC_map_lookup_percpu_elem:
if (map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY &&
map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
map->map_type != BPF_MAP_TYPE_LRU_PERCPU_HASH)
goto error;
break;
case BPF_FUNC_sk_storage_get:
case BPF_FUNC_sk_storage_delete:
if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
goto error;
break;
case BPF_FUNC_inode_storage_get:
case BPF_FUNC_inode_storage_delete:
if (map->map_type != BPF_MAP_TYPE_INODE_STORAGE)
goto error;
break;
case BPF_FUNC_task_storage_get:
case BPF_FUNC_task_storage_delete:
if (map->map_type != BPF_MAP_TYPE_TASK_STORAGE)
goto error;
break;
case BPF_FUNC_cgrp_storage_get:
case BPF_FUNC_cgrp_storage_delete:
if (map->map_type != BPF_MAP_TYPE_CGRP_STORAGE)
goto error;
break;
default:
break;
}
return 0;
error:
verbose(env, "cannot pass map_type %d into func %s#%d\n",
map->map_type, func_id_name(func_id), func_id);
return -EINVAL;
}
static bool check_raw_mode_ok(const struct bpf_func_proto *fn)
{
int count = 0;
if (arg_type_is_raw_mem(fn->arg1_type))
count++;
if (arg_type_is_raw_mem(fn->arg2_type))
count++;
if (arg_type_is_raw_mem(fn->arg3_type))
count++;
if (arg_type_is_raw_mem(fn->arg4_type))
count++;
if (arg_type_is_raw_mem(fn->arg5_type))
count++;
/* We only support one arg being in raw mode at the moment,
* which is sufficient for the helper functions we have
* right now.
*/
return count <= 1;
}
static bool check_args_pair_invalid(const struct bpf_func_proto *fn, int arg)
{
bool is_fixed = fn->arg_type[arg] & MEM_FIXED_SIZE;
bool has_size = fn->arg_size[arg] != 0;
bool is_next_size = false;
if (arg + 1 < ARRAY_SIZE(fn->arg_type))
is_next_size = arg_type_is_mem_size(fn->arg_type[arg + 1]);
if (base_type(fn->arg_type[arg]) != ARG_PTR_TO_MEM)
return is_next_size;
return has_size == is_next_size || is_next_size == is_fixed;
}
static bool check_arg_pair_ok(const struct bpf_func_proto *fn)
{
/* bpf_xxx(..., buf, len) call will access 'len'
* bytes from memory 'buf'. Both arg types need
* to be paired, so make sure there's no buggy
* helper function specification.
*/
if (arg_type_is_mem_size(fn->arg1_type) ||
check_args_pair_invalid(fn, 0) ||
check_args_pair_invalid(fn, 1) ||
check_args_pair_invalid(fn, 2) ||
check_args_pair_invalid(fn, 3) ||
check_args_pair_invalid(fn, 4))
return false;
return true;
}
static bool check_btf_id_ok(const struct bpf_func_proto *fn)
{
int i;
for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++) {
if (base_type(fn->arg_type[i]) == ARG_PTR_TO_BTF_ID)
return !!fn->arg_btf_id[i];
if (base_type(fn->arg_type[i]) == ARG_PTR_TO_SPIN_LOCK)
return fn->arg_btf_id[i] == BPF_PTR_POISON;
if (base_type(fn->arg_type[i]) != ARG_PTR_TO_BTF_ID && fn->arg_btf_id[i] &&
/* arg_btf_id and arg_size are in a union. */
(base_type(fn->arg_type[i]) != ARG_PTR_TO_MEM ||
!(fn->arg_type[i] & MEM_FIXED_SIZE)))
return false;
}
return true;
}
static int check_func_proto(const struct bpf_func_proto *fn, int func_id)
{
return check_raw_mode_ok(fn) &&
check_arg_pair_ok(fn) &&
check_btf_id_ok(fn) ? 0 : -EINVAL;
}
/* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
* are now invalid, so turn them into unknown SCALAR_VALUE.
*
* This also applies to dynptr slices belonging to skb and xdp dynptrs,
* since these slices point to packet data.
*/
static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
{
struct bpf_func_state *state;
struct bpf_reg_state *reg;
bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
if (reg_is_pkt_pointer_any(reg) || reg_is_dynptr_slice_pkt(reg))
mark_reg_invalid(env, reg);
}));
}
enum {
AT_PKT_END = -1,
BEYOND_PKT_END = -2,
};
static void mark_pkt_end(struct bpf_verifier_state *vstate, int regn, bool range_open)
{
struct bpf_func_state *state = vstate->frame[vstate->curframe];
struct bpf_reg_state *reg = &state->regs[regn];
if (reg->type != PTR_TO_PACKET)
/* PTR_TO_PACKET_META is not supported yet */
return;
/* The 'reg' is pkt > pkt_end or pkt >= pkt_end.
* How far beyond pkt_end it goes is unknown.
* if (!range_open) it's the case of pkt >= pkt_end
* if (range_open) it's the case of pkt > pkt_end
* hence this pointer is at least 1 byte bigger than pkt_end
*/
if (range_open)
reg->range = BEYOND_PKT_END;
else
reg->range = AT_PKT_END;
}
/* The pointer with the specified id has released its reference to kernel
* resources. Identify all copies of the same pointer and clear the reference.
*/
static int release_reference(struct bpf_verifier_env *env,
int ref_obj_id)
{
struct bpf_func_state *state;
struct bpf_reg_state *reg;
int err;
err = release_reference_state(cur_func(env), ref_obj_id);
if (err)
return err;
bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
if (reg->ref_obj_id == ref_obj_id)
mark_reg_invalid(env, reg);
}));
return 0;
}
static void invalidate_non_owning_refs(struct bpf_verifier_env *env)
{
struct bpf_func_state *unused;
struct bpf_reg_state *reg;
bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({
if (type_is_non_owning_ref(reg->type))
mark_reg_invalid(env, reg);
}));
}
static void clear_caller_saved_regs(struct bpf_verifier_env *env,
struct bpf_reg_state *regs)
{
int i;
/* after the call registers r0 - r5 were scratched */
for (i = 0; i < CALLER_SAVED_REGS; i++) {
mark_reg_not_init(env, regs, caller_saved[i]);
__check_reg_arg(env, regs, caller_saved[i], DST_OP_NO_MARK);
}
}
typedef int (*set_callee_state_fn)(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee,
int insn_idx);
static int set_callee_state(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee, int insn_idx);
static int setup_func_entry(struct bpf_verifier_env *env, int subprog, int callsite,
set_callee_state_fn set_callee_state_cb,
struct bpf_verifier_state *state)
{
struct bpf_func_state *caller, *callee;
int err;
if (state->curframe + 1 >= MAX_CALL_FRAMES) {
verbose(env, "the call stack of %d frames is too deep\n",
state->curframe + 2);
return -E2BIG;
}
if (state->frame[state->curframe + 1]) {
verbose(env, "verifier bug. Frame %d already allocated\n",
state->curframe + 1);
return -EFAULT;
}
caller = state->frame[state->curframe];
callee = kzalloc(sizeof(*callee), GFP_KERNEL);
if (!callee)
return -ENOMEM;
state->frame[state->curframe + 1] = callee;
/* callee cannot access r0, r6 - r9 for reading and has to write
* into its own stack before reading from it.
* callee can read/write into caller's stack
*/
init_func_state(env, callee,
/* remember the callsite, it will be used by bpf_exit */
callsite,
state->curframe + 1 /* frameno within this callchain */,
subprog /* subprog number within this prog */);
/* Transfer references to the callee */
err = copy_reference_state(callee, caller);
err = err ?: set_callee_state_cb(env, caller, callee, callsite);
if (err)
goto err_out;
/* only increment it after check_reg_arg() finished */
state->curframe++;
return 0;
err_out:
free_func_state(callee);
state->frame[state->curframe + 1] = NULL;
return err;
}
static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
const struct btf *btf,
struct bpf_reg_state *regs)
{
struct bpf_subprog_info *sub = subprog_info(env, subprog);
struct bpf_verifier_log *log = &env->log;
u32 i;
int ret;
ret = btf_prepare_func_args(env, subprog);
if (ret)
return ret;
/* check that BTF function arguments match actual types that the
* verifier sees.
*/
for (i = 0; i < sub->arg_cnt; i++) {
u32 regno = i + 1;
struct bpf_reg_state *reg = ®s[regno];
struct bpf_subprog_arg_info *arg = &sub->args[i];
if (arg->arg_type == ARG_ANYTHING) {
if (reg->type != SCALAR_VALUE) {
bpf_log(log, "R%d is not a scalar\n", regno);
return -EINVAL;
}
} else if (arg->arg_type == ARG_PTR_TO_CTX) {
ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE);
if (ret < 0)
return ret;
/* If function expects ctx type in BTF check that caller
* is passing PTR_TO_CTX.
*/
if (reg->type != PTR_TO_CTX) {
bpf_log(log, "arg#%d expects pointer to ctx\n", i);
return -EINVAL;
}
} else if (base_type(arg->arg_type) == ARG_PTR_TO_MEM) {
ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE);
if (ret < 0)
return ret;
if (check_mem_reg(env, reg, regno, arg->mem_size))
return -EINVAL;
if (!(arg->arg_type & PTR_MAYBE_NULL) && (reg->type & PTR_MAYBE_NULL)) {
bpf_log(log, "arg#%d is expected to be non-NULL\n", i);
return -EINVAL;
}
} else if (base_type(arg->arg_type) == ARG_PTR_TO_ARENA) {
/*
* Can pass any value and the kernel won't crash, but
* only PTR_TO_ARENA or SCALAR make sense. Everything
* else is a bug in the bpf program. Point it out to
* the user at the verification time instead of
* run-time debug nightmare.
*/
if (reg->type != PTR_TO_ARENA && reg->type != SCALAR_VALUE) {
bpf_log(log, "R%d is not a pointer to arena or scalar.\n", regno);
return -EINVAL;
}
} else if (arg->arg_type == (ARG_PTR_TO_DYNPTR | MEM_RDONLY)) {
ret = check_func_arg_reg_off(env, reg, regno, ARG_PTR_TO_DYNPTR);
if (ret)
return ret;
ret = process_dynptr_func(env, regno, -1, arg->arg_type, 0);
if (ret)
return ret;
} else if (base_type(arg->arg_type) == ARG_PTR_TO_BTF_ID) {
struct bpf_call_arg_meta meta;
int err;
if (register_is_null(reg) && type_may_be_null(arg->arg_type))
continue;
memset(&meta, 0, sizeof(meta)); /* leave func_id as zero */
err = check_reg_type(env, regno, arg->arg_type, &arg->btf_id, &meta);
err = err ?: check_func_arg_reg_off(env, reg, regno, arg->arg_type);
if (err)
return err;
} else {
bpf_log(log, "verifier bug: unrecognized arg#%d type %d\n",
i, arg->arg_type);
return -EFAULT;
}
}
return 0;
}
/* Compare BTF of a function call with given bpf_reg_state.
* Returns:
* EFAULT - there is a verifier bug. Abort verification.
* EINVAL - there is a type mismatch or BTF is not available.
* 0 - BTF matches with what bpf_reg_state expects.
* Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
*/
static int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog,
struct bpf_reg_state *regs)
{
struct bpf_prog *prog = env->prog;
struct btf *btf = prog->aux->btf;
u32 btf_id;
int err;
if (!prog->aux->func_info)
return -EINVAL;
btf_id = prog->aux->func_info[subprog].type_id;
if (!btf_id)
return -EFAULT;
if (prog->aux->func_info_aux[subprog].unreliable)
return -EINVAL;
err = btf_check_func_arg_match(env, subprog, btf, regs);
/* Compiler optimizations can remove arguments from static functions
* or mismatched type can be passed into a global function.
* In such cases mark the function as unreliable from BTF point of view.
*/
if (err)
prog->aux->func_info_aux[subprog].unreliable = true;
return err;
}
static int push_callback_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
int insn_idx, int subprog,
set_callee_state_fn set_callee_state_cb)
{
struct bpf_verifier_state *state = env->cur_state, *callback_state;
struct bpf_func_state *caller, *callee;
int err;
caller = state->frame[state->curframe];
err = btf_check_subprog_call(env, subprog, caller->regs);
if (err == -EFAULT)
return err;
/* set_callee_state is used for direct subprog calls, but we are
* interested in validating only BPF helpers that can call subprogs as
* callbacks
*/
env->subprog_info[subprog].is_cb = true;
if (bpf_pseudo_kfunc_call(insn) &&
!is_callback_calling_kfunc(insn->imm)) {
verbose(env, "verifier bug: kfunc %s#%d not marked as callback-calling\n",
func_id_name(insn->imm), insn->imm);
return -EFAULT;
} else if (!bpf_pseudo_kfunc_call(insn) &&
!is_callback_calling_function(insn->imm)) { /* helper */
verbose(env, "verifier bug: helper %s#%d not marked as callback-calling\n",
func_id_name(insn->imm), insn->imm);
return -EFAULT;
}
if (is_async_callback_calling_insn(insn)) {
struct bpf_verifier_state *async_cb;
/* there is no real recursion here. timer and workqueue callbacks are async */
env->subprog_info[subprog].is_async_cb = true;
async_cb = push_async_cb(env, env->subprog_info[subprog].start,
insn_idx, subprog,
is_bpf_wq_set_callback_impl_kfunc(insn->imm));
if (!async_cb)
return -EFAULT;
callee = async_cb->frame[0];
callee->async_entry_cnt = caller->async_entry_cnt + 1;
/* Convert bpf_timer_set_callback() args into timer callback args */
err = set_callee_state_cb(env, caller, callee, insn_idx);
if (err)
return err;
return 0;
}
/* for callback functions enqueue entry to callback and
* proceed with next instruction within current frame.
*/
callback_state = push_stack(env, env->subprog_info[subprog].start, insn_idx, false);
if (!callback_state)
return -ENOMEM;
err = setup_func_entry(env, subprog, insn_idx, set_callee_state_cb,
callback_state);
if (err)
return err;
callback_state->callback_unroll_depth++;
callback_state->frame[callback_state->curframe - 1]->callback_depth++;
caller->callback_depth = 0;
return 0;
}
static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
int *insn_idx)
{
struct bpf_verifier_state *state = env->cur_state;
struct bpf_func_state *caller;
int err, subprog, target_insn;
target_insn = *insn_idx + insn->imm + 1;
subprog = find_subprog(env, target_insn);
if (subprog < 0) {
verbose(env, "verifier bug. No program starts at insn %d\n", target_insn);
return -EFAULT;
}
caller = state->frame[state->curframe];
err = btf_check_subprog_call(env, subprog, caller->regs);
if (err == -EFAULT)
return err;
if (subprog_is_global(env, subprog)) {
const char *sub_name = subprog_name(env, subprog);
/* Only global subprogs cannot be called with a lock held. */
if (env->cur_state->active_lock.ptr) {
verbose(env, "global function calls are not allowed while holding a lock,\n"
"use static function instead\n");
return -EINVAL;
}
/* Only global subprogs cannot be called with preemption disabled. */
if (env->cur_state->active_preempt_lock) {
verbose(env, "global function calls are not allowed with preemption disabled,\n"
"use static function instead\n");
return -EINVAL;
}
if (err) {
verbose(env, "Caller passes invalid args into func#%d ('%s')\n",
subprog, sub_name);
return err;
}
verbose(env, "Func#%d ('%s') is global and assumed valid.\n",
subprog, sub_name);
/* mark global subprog for verifying after main prog */
subprog_aux(env, subprog)->called = true;
clear_caller_saved_regs(env, caller->regs);
/* All global functions return a 64-bit SCALAR_VALUE */
mark_reg_unknown(env, caller->regs, BPF_REG_0);
caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;
/* continue with next insn after call */
return 0;
}
/* for regular function entry setup new frame and continue
* from that frame.
*/
err = setup_func_entry(env, subprog, *insn_idx, set_callee_state, state);
if (err)
return err;
clear_caller_saved_regs(env, caller->regs);
/* and go analyze first insn of the callee */
*insn_idx = env->subprog_info[subprog].start - 1;
if (env->log.level & BPF_LOG_LEVEL) {
verbose(env, "caller:\n");
print_verifier_state(env, caller, true);
verbose(env, "callee:\n");
print_verifier_state(env, state->frame[state->curframe], true);
}
return 0;
}
int map_set_for_each_callback_args(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee)
{
/* bpf_for_each_map_elem(struct bpf_map *map, void *callback_fn,
* void *callback_ctx, u64 flags);
* callback_fn(struct bpf_map *map, void *key, void *value,
* void *callback_ctx);
*/
callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1];
callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY;
__mark_reg_known_zero(&callee->regs[BPF_REG_2]);
callee->regs[BPF_REG_2].map_ptr = caller->regs[BPF_REG_1].map_ptr;
callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE;
__mark_reg_known_zero(&callee->regs[BPF_REG_3]);
callee->regs[BPF_REG_3].map_ptr = caller->regs[BPF_REG_1].map_ptr;
/* pointer to stack or null */
callee->regs[BPF_REG_4] = caller->regs[BPF_REG_3];
/* unused */
__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
return 0;
}
static int set_callee_state(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee, int insn_idx)
{
int i;
/* copy r1 - r5 args that callee can access. The copy includes parent
* pointers, which connects us up to the liveness chain
*/
for (i = BPF_REG_1; i <= BPF_REG_5; i++)
callee->regs[i] = caller->regs[i];
return 0;
}
static int set_map_elem_callback_state(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee,
int insn_idx)
{
struct bpf_insn_aux_data *insn_aux = &env->insn_aux_data[insn_idx];
struct bpf_map *map;
int err;
/* valid map_ptr and poison value does not matter */
map = insn_aux->map_ptr_state.map_ptr;
if (!map->ops->map_set_for_each_callback_args ||
!map->ops->map_for_each_callback) {
verbose(env, "callback function not allowed for map\n");
return -ENOTSUPP;
}
err = map->ops->map_set_for_each_callback_args(env, caller, callee);
if (err)
return err;
callee->in_callback_fn = true;
callee->callback_ret_range = retval_range(0, 1);
return 0;
}
static int set_loop_callback_state(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee,
int insn_idx)
{
/* bpf_loop(u32 nr_loops, void *callback_fn, void *callback_ctx,
* u64 flags);
* callback_fn(u32 index, void *callback_ctx);
*/
callee->regs[BPF_REG_1].type = SCALAR_VALUE;
callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3];
/* unused */
__mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
__mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
callee->in_callback_fn = true;
callee->callback_ret_range = retval_range(0, 1);
return 0;
}
static int set_timer_callback_state(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee,
int insn_idx)
{
struct bpf_map *map_ptr = caller->regs[BPF_REG_1].map_ptr;
/* bpf_timer_set_callback(struct bpf_timer *timer, void *callback_fn);
* callback_fn(struct bpf_map *map, void *key, void *value);
*/
callee->regs[BPF_REG_1].type = CONST_PTR_TO_MAP;
__mark_reg_known_zero(&callee->regs[BPF_REG_1]);
callee->regs[BPF_REG_1].map_ptr = map_ptr;
callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY;
__mark_reg_known_zero(&callee->regs[BPF_REG_2]);
callee->regs[BPF_REG_2].map_ptr = map_ptr;
callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE;
__mark_reg_known_zero(&callee->regs[BPF_REG_3]);
callee->regs[BPF_REG_3].map_ptr = map_ptr;
/* unused */
__mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
callee->in_async_callback_fn = true;
callee->callback_ret_range = retval_range(0, 1);
return 0;
}
static int set_find_vma_callback_state(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee,
int insn_idx)
{
/* bpf_find_vma(struct task_struct *task, u64 addr,
* void *callback_fn, void *callback_ctx, u64 flags)
* (callback_fn)(struct task_struct *task,
* struct vm_area_struct *vma, void *callback_ctx);
*/
callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1];
callee->regs[BPF_REG_2].type = PTR_TO_BTF_ID;
__mark_reg_known_zero(&callee->regs[BPF_REG_2]);
callee->regs[BPF_REG_2].btf = btf_vmlinux;
callee->regs[BPF_REG_2].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA];
/* pointer to stack or null */
callee->regs[BPF_REG_3] = caller->regs[BPF_REG_4];
/* unused */
__mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
callee->in_callback_fn = true;
callee->callback_ret_range = retval_range(0, 1);
return 0;
}
static int set_user_ringbuf_callback_state(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee,
int insn_idx)
{
/* bpf_user_ringbuf_drain(struct bpf_map *map, void *callback_fn, void
* callback_ctx, u64 flags);
* callback_fn(const struct bpf_dynptr_t* dynptr, void *callback_ctx);
*/
__mark_reg_not_init(env, &callee->regs[BPF_REG_0]);
mark_dynptr_cb_reg(env, &callee->regs[BPF_REG_1], BPF_DYNPTR_TYPE_LOCAL);
callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3];
/* unused */
__mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
__mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
callee->in_callback_fn = true;
callee->callback_ret_range = retval_range(0, 1);
return 0;
}
static int set_rbtree_add_callback_state(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee,
int insn_idx)
{
/* void bpf_rbtree_add_impl(struct bpf_rb_root *root, struct bpf_rb_node *node,
* bool (less)(struct bpf_rb_node *a, const struct bpf_rb_node *b));
*
* 'struct bpf_rb_node *node' arg to bpf_rbtree_add_impl is the same PTR_TO_BTF_ID w/ offset
* that 'less' callback args will be receiving. However, 'node' arg was release_reference'd
* by this point, so look at 'root'
*/
struct btf_field *field;
field = reg_find_field_offset(&caller->regs[BPF_REG_1], caller->regs[BPF_REG_1].off,
BPF_RB_ROOT);
if (!field || !field->graph_root.value_btf_id)
return -EFAULT;
mark_reg_graph_node(callee->regs, BPF_REG_1, &field->graph_root);
ref_set_non_owning(env, &callee->regs[BPF_REG_1]);
mark_reg_graph_node(callee->regs, BPF_REG_2, &field->graph_root);
ref_set_non_owning(env, &callee->regs[BPF_REG_2]);
__mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
__mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
callee->in_callback_fn = true;
callee->callback_ret_range = retval_range(0, 1);
return 0;
}
static bool is_rbtree_lock_required_kfunc(u32 btf_id);
/* Are we currently verifying the callback for a rbtree helper that must
* be called with lock held? If so, no need to complain about unreleased
* lock
*/
static bool in_rbtree_lock_required_cb(struct bpf_verifier_env *env)
{
struct bpf_verifier_state *state = env->cur_state;
struct bpf_insn *insn = env->prog->insnsi;
struct bpf_func_state *callee;
int kfunc_btf_id;
if (!state->curframe)
return false;
callee = state->frame[state->curframe];
if (!callee->in_callback_fn)
return false;
kfunc_btf_id = insn[callee->callsite].imm;
return is_rbtree_lock_required_kfunc(kfunc_btf_id);
}
static bool retval_range_within(struct bpf_retval_range range, const struct bpf_reg_state *reg,
bool return_32bit)
{
if (return_32bit)
return range.minval <= reg->s32_min_value && reg->s32_max_value <= range.maxval;
else
return range.minval <= reg->smin_value && reg->smax_value <= range.maxval;
}
static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
{
struct bpf_verifier_state *state = env->cur_state, *prev_st;
struct bpf_func_state *caller, *callee;
struct bpf_reg_state *r0;
bool in_callback_fn;
int err;
callee = state->frame[state->curframe];
r0 = &callee->regs[BPF_REG_0];
if (r0->type == PTR_TO_STACK) {
/* technically it's ok to return caller's stack pointer
* (or caller's caller's pointer) back to the caller,
* since these pointers are valid. Only current stack
* pointer will be invalid as soon as function exits,
* but let's be conservative
*/
verbose(env, "cannot return stack pointer to the caller\n");
return -EINVAL;
}
caller = state->frame[state->curframe - 1];
if (callee->in_callback_fn) {
if (r0->type != SCALAR_VALUE) {
verbose(env, "R0 not a scalar value\n");
return -EACCES;
}
/* we are going to rely on register's precise value */
err = mark_reg_read(env, r0, r0->parent, REG_LIVE_READ64);
err = err ?: mark_chain_precision(env, BPF_REG_0);
if (err)
return err;
/* enforce R0 return value range, and bpf_callback_t returns 64bit */
if (!retval_range_within(callee->callback_ret_range, r0, false)) {
verbose_invalid_scalar(env, r0, callee->callback_ret_range,
"At callback return", "R0");
return -EINVAL;
}
if (!calls_callback(env, callee->callsite)) {
verbose(env, "BUG: in callback at %d, callsite %d !calls_callback\n",
*insn_idx, callee->callsite);
return -EFAULT;
}
} else {
/* return to the caller whatever r0 had in the callee */
caller->regs[BPF_REG_0] = *r0;
}
/* callback_fn frame should have released its own additions to parent's
* reference state at this point, or check_reference_leak would
* complain, hence it must be the same as the caller. There is no need
* to copy it back.
*/
if (!callee->in_callback_fn) {
/* Transfer references to the caller */
err = copy_reference_state(caller, callee);
if (err)
return err;
}
/* for callbacks like bpf_loop or bpf_for_each_map_elem go back to callsite,
* there function call logic would reschedule callback visit. If iteration
* converges is_state_visited() would prune that visit eventually.
*/
in_callback_fn = callee->in_callback_fn;
if (in_callback_fn)
*insn_idx = callee->callsite;
else
*insn_idx = callee->callsite + 1;
if (env->log.level & BPF_LOG_LEVEL) {
verbose(env, "returning from callee:\n");
print_verifier_state(env, callee, true);
verbose(env, "to caller at %d:\n", *insn_idx);
print_verifier_state(env, caller, true);
}
/* clear everything in the callee. In case of exceptional exits using
* bpf_throw, this will be done by copy_verifier_state for extra frames. */
free_func_state(callee);
state->frame[state->curframe--] = NULL;
/* for callbacks widen imprecise scalars to make programs like below verify:
*
* struct ctx { int i; }
* void cb(int idx, struct ctx *ctx) { ctx->i++; ... }
* ...
* struct ctx = { .i = 0; }
* bpf_loop(100, cb, &ctx, 0);
*
* This is similar to what is done in process_iter_next_call() for open
* coded iterators.
*/
prev_st = in_callback_fn ? find_prev_entry(env, state, *insn_idx) : NULL;
if (prev_st) {
err = widen_imprecise_scalars(env, prev_st, state);
if (err)
return err;
}
return 0;
}
static int do_refine_retval_range(struct bpf_verifier_env *env,
struct bpf_reg_state *regs, int ret_type,
int func_id,
struct bpf_call_arg_meta *meta)
{
struct bpf_reg_state *ret_reg = ®s[BPF_REG_0];
if (ret_type != RET_INTEGER)
return 0;
switch (func_id) {
case BPF_FUNC_get_stack:
case BPF_FUNC_get_task_stack:
case BPF_FUNC_probe_read_str:
case BPF_FUNC_probe_read_kernel_str:
case BPF_FUNC_probe_read_user_str:
ret_reg->smax_value = meta->msize_max_value;
ret_reg->s32_max_value = meta->msize_max_value;
ret_reg->smin_value = -MAX_ERRNO;
ret_reg->s32_min_value = -MAX_ERRNO;
reg_bounds_sync(ret_reg);
break;
case BPF_FUNC_get_smp_processor_id:
ret_reg->umax_value = nr_cpu_ids - 1;
ret_reg->u32_max_value = nr_cpu_ids - 1;
ret_reg->smax_value = nr_cpu_ids - 1;
ret_reg->s32_max_value = nr_cpu_ids - 1;
ret_reg->umin_value = 0;
ret_reg->u32_min_value = 0;
ret_reg->smin_value = 0;
ret_reg->s32_min_value = 0;
reg_bounds_sync(ret_reg);
break;
}
return reg_bounds_sanity_check(env, ret_reg, "retval");
}
static int
record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
int func_id, int insn_idx)
{
struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
struct bpf_map *map = meta->map_ptr;
if (func_id != BPF_FUNC_tail_call &&
func_id != BPF_FUNC_map_lookup_elem &&
func_id != BPF_FUNC_map_update_elem &&
func_id != BPF_FUNC_map_delete_elem &&
func_id != BPF_FUNC_map_push_elem &&
func_id != BPF_FUNC_map_pop_elem &&
func_id != BPF_FUNC_map_peek_elem &&
func_id != BPF_FUNC_for_each_map_elem &&
func_id != BPF_FUNC_redirect_map &&
func_id != BPF_FUNC_map_lookup_percpu_elem)
return 0;
if (map == NULL) {
verbose(env, "kernel subsystem misconfigured verifier\n");
return -EINVAL;
}
/* In case of read-only, some additional restrictions
* need to be applied in order to prevent altering the
* state of the map from program side.
*/
if ((map->map_flags & BPF_F_RDONLY_PROG) &&
(func_id == BPF_FUNC_map_delete_elem ||
func_id == BPF_FUNC_map_update_elem ||
func_id == BPF_FUNC_map_push_elem ||
func_id == BPF_FUNC_map_pop_elem)) {
verbose(env, "write into map forbidden\n");
return -EACCES;
}
if (!aux->map_ptr_state.map_ptr)
bpf_map_ptr_store(aux, meta->map_ptr,
!meta->map_ptr->bypass_spec_v1, false);
else if (aux->map_ptr_state.map_ptr != meta->map_ptr)
bpf_map_ptr_store(aux, meta->map_ptr,
!meta->map_ptr->bypass_spec_v1, true);
return 0;
}
static int
record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
int func_id, int insn_idx)
{
struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
struct bpf_reg_state *regs = cur_regs(env), *reg;
struct bpf_map *map = meta->map_ptr;
u64 val, max;
int err;
if (func_id != BPF_FUNC_tail_call)
return 0;
if (!map || map->map_type != BPF_MAP_TYPE_PROG_ARRAY) {
verbose(env, "kernel subsystem misconfigured verifier\n");
return -EINVAL;
}
reg = ®s[BPF_REG_3];
val = reg->var_off.value;
max = map->max_entries;
if (!(is_reg_const(reg, false) && val < max)) {
bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
return 0;
}
err = mark_chain_precision(env, BPF_REG_3);
if (err)
return err;
if (bpf_map_key_unseen(aux))
bpf_map_key_store(aux, val);
else if (!bpf_map_key_poisoned(aux) &&
bpf_map_key_immediate(aux) != val)
bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
return 0;
}
static int check_reference_leak(struct bpf_verifier_env *env, bool exception_exit)
{
struct bpf_func_state *state = cur_func(env);
bool refs_lingering = false;
int i;
if (!exception_exit && state->frameno && !state->in_callback_fn)
return 0;
for (i = 0; i < state->acquired_refs; i++) {
if (!exception_exit && state->in_callback_fn && state->refs[i].callback_ref != state->frameno)
continue;
verbose(env, "Unreleased reference id=%d alloc_insn=%d\n",
state->refs[i].id, state->refs[i].insn_idx);
refs_lingering = true;
}
return refs_lingering ? -EINVAL : 0;
}
static int check_bpf_snprintf_call(struct bpf_verifier_env *env,
struct bpf_reg_state *regs)
{
struct bpf_reg_state *fmt_reg = ®s[BPF_REG_3];
struct bpf_reg_state *data_len_reg = ®s[BPF_REG_5];
struct bpf_map *fmt_map = fmt_reg->map_ptr;
struct bpf_bprintf_data data = {};
int err, fmt_map_off, num_args;
u64 fmt_addr;
char *fmt;
/* data must be an array of u64 */
if (data_len_reg->var_off.value % 8)
return -EINVAL;
num_args = data_len_reg->var_off.value / 8;
/* fmt being ARG_PTR_TO_CONST_STR guarantees that var_off is const
* and map_direct_value_addr is set.
*/
fmt_map_off = fmt_reg->off + fmt_reg->var_off.value;
err = fmt_map->ops->map_direct_value_addr(fmt_map, &fmt_addr,
fmt_map_off);
if (err) {
verbose(env, "verifier bug\n");
return -EFAULT;
}
fmt = (char *)(long)fmt_addr + fmt_map_off;
/* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we
* can focus on validating the format specifiers.
*/
err = bpf_bprintf_prepare(fmt, UINT_MAX, NULL, num_args, &data);
if (err < 0)
verbose(env, "Invalid format string\n");
return err;
}
static int check_get_func_ip(struct bpf_verifier_env *env)
{
enum bpf_prog_type type = resolve_prog_type(env->prog);
int func_id = BPF_FUNC_get_func_ip;
if (type == BPF_PROG_TYPE_TRACING) {
if (!bpf_prog_has_trampoline(env->prog)) {
verbose(env, "func %s#%d supported only for fentry/fexit/fmod_ret programs\n",
func_id_name(func_id), func_id);
return -ENOTSUPP;
}
return 0;
} else if (type == BPF_PROG_TYPE_KPROBE) {
return 0;
}
verbose(env, "func %s#%d not supported for program type %d\n",
func_id_name(func_id), func_id, type);
return -ENOTSUPP;
}
static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env)
{
return &env->insn_aux_data[env->insn_idx];
}
static bool loop_flag_is_zero(struct bpf_verifier_env *env)
{
struct bpf_reg_state *regs = cur_regs(env);
struct bpf_reg_state *reg = ®s[BPF_REG_4];
bool reg_is_null = register_is_null(reg);
if (reg_is_null)
mark_chain_precision(env, BPF_REG_4);
return reg_is_null;
}
static void update_loop_inline_state(struct bpf_verifier_env *env, u32 subprogno)
{
struct bpf_loop_inline_state *state = &cur_aux(env)->loop_inline_state;
if (!state->initialized) {
state->initialized = 1;
state->fit_for_inline = loop_flag_is_zero(env);
state->callback_subprogno = subprogno;
return;
}
if (!state->fit_for_inline)
return;
state->fit_for_inline = (loop_flag_is_zero(env) &&
state->callback_subprogno == subprogno);
}
static int get_helper_proto(struct bpf_verifier_env *env, int func_id,
const struct bpf_func_proto **ptr)
{
if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID)
return -ERANGE;
if (!env->ops->get_func_proto)
return -EINVAL;
*ptr = env->ops->get_func_proto(func_id, env->prog);
return *ptr ? 0 : -EINVAL;
}
static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
int *insn_idx_p)
{
enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
bool returns_cpu_specific_alloc_ptr = false;
const struct bpf_func_proto *fn = NULL;
enum bpf_return_type ret_type;
enum bpf_type_flag ret_flag;
struct bpf_reg_state *regs;
struct bpf_call_arg_meta meta;
int insn_idx = *insn_idx_p;
bool changes_data;
int i, err, func_id;
/* find function prototype */
func_id = insn->imm;
err = get_helper_proto(env, insn->imm, &fn);
if (err == -ERANGE) {
verbose(env, "invalid func %s#%d\n", func_id_name(func_id), func_id);
return -EINVAL;
}
if (err) {
verbose(env, "program of this type cannot use helper %s#%d\n",
func_id_name(func_id), func_id);
return err;
}
/* eBPF programs must be GPL compatible to use GPL-ed functions */
if (!env->prog->gpl_compatible && fn->gpl_only) {
verbose(env, "cannot call GPL-restricted function from non-GPL compatible program\n");
return -EINVAL;
}
if (fn->allowed && !fn->allowed(env->prog)) {
verbose(env, "helper call is not allowed in probe\n");
return -EINVAL;
}
if (!in_sleepable(env) && fn->might_sleep) {
verbose(env, "helper call might sleep in a non-sleepable prog\n");
return -EINVAL;
}
/* With LD_ABS/IND some JITs save/restore skb from r1. */
changes_data = bpf_helper_changes_pkt_data(fn->func);
if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) {
verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n",
func_id_name(func_id), func_id);
return -EINVAL;
}
memset(&meta, 0, sizeof(meta));
meta.pkt_access = fn->pkt_access;
err = check_func_proto(fn, func_id);
if (err) {
verbose(env, "kernel subsystem misconfigured func %s#%d\n",
func_id_name(func_id), func_id);
return err;
}
if (env->cur_state->active_rcu_lock) {
if (fn->might_sleep) {
verbose(env, "sleepable helper %s#%d in rcu_read_lock region\n",
func_id_name(func_id), func_id);
return -EINVAL;
}
if (in_sleepable(env) && is_storage_get_function(func_id))
env->insn_aux_data[insn_idx].storage_get_func_atomic = true;
}
if (env->cur_state->active_preempt_lock) {
if (fn->might_sleep) {
verbose(env, "sleepable helper %s#%d in non-preemptible region\n",
func_id_name(func_id), func_id);
return -EINVAL;
}
if (in_sleepable(env) && is_storage_get_function(func_id))
env->insn_aux_data[insn_idx].storage_get_func_atomic = true;
}
meta.func_id = func_id;
/* check args */
for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) {
err = check_func_arg(env, i, &meta, fn, insn_idx);
if (err)
return err;
}
err = record_func_map(env, &meta, func_id, insn_idx);
if (err)
return err;
err = record_func_key(env, &meta, func_id, insn_idx);
if (err)
return err;
/* Mark slots with STACK_MISC in case of raw mode, stack offset
* is inferred from register state.
*/
for (i = 0; i < meta.access_size; i++) {
err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B,
BPF_WRITE, -1, false, false);
if (err)
return err;
}
regs = cur_regs(env);
if (meta.release_regno) {
err = -EINVAL;
/* This can only be set for PTR_TO_STACK, as CONST_PTR_TO_DYNPTR cannot
* be released by any dynptr helper. Hence, unmark_stack_slots_dynptr
* is safe to do directly.
*/
if (arg_type_is_dynptr(fn->arg_type[meta.release_regno - BPF_REG_1])) {
if (regs[meta.release_regno].type == CONST_PTR_TO_DYNPTR) {
verbose(env, "verifier internal error: CONST_PTR_TO_DYNPTR cannot be released\n");
return -EFAULT;
}
err = unmark_stack_slots_dynptr(env, ®s[meta.release_regno]);
} else if (func_id == BPF_FUNC_kptr_xchg && meta.ref_obj_id) {
u32 ref_obj_id = meta.ref_obj_id;
bool in_rcu = in_rcu_cs(env);
struct bpf_func_state *state;
struct bpf_reg_state *reg;
err = release_reference_state(cur_func(env), ref_obj_id);
if (!err) {
bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
if (reg->ref_obj_id == ref_obj_id) {
if (in_rcu && (reg->type & MEM_ALLOC) && (reg->type & MEM_PERCPU)) {
reg->ref_obj_id = 0;
reg->type &= ~MEM_ALLOC;
reg->type |= MEM_RCU;
} else {
mark_reg_invalid(env, reg);
}
}
}));
}
} else if (meta.ref_obj_id) {
err = release_reference(env, meta.ref_obj_id);
} else if (register_is_null(®s[meta.release_regno])) {
/* meta.ref_obj_id can only be 0 if register that is meant to be
* released is NULL, which must be > R0.
*/
err = 0;
}
if (err) {
verbose(env, "func %s#%d reference has not been acquired before\n",
func_id_name(func_id), func_id);
return err;
}
}
switch (func_id) {
case BPF_FUNC_tail_call:
err = check_reference_leak(env, false);
if (err) {
verbose(env, "tail_call would lead to reference leak\n");
return err;
}
break;
case BPF_FUNC_get_local_storage:
/* check that flags argument in get_local_storage(map, flags) is 0,
* this is required because get_local_storage() can't return an error.
*/
if (!register_is_null(®s[BPF_REG_2])) {
verbose(env, "get_local_storage() doesn't support non-zero flags\n");
return -EINVAL;
}
break;
case BPF_FUNC_for_each_map_elem:
err = push_callback_call(env, insn, insn_idx, meta.subprogno,
set_map_elem_callback_state);
break;
case BPF_FUNC_timer_set_callback:
err = push_callback_call(env, insn, insn_idx, meta.subprogno,
set_timer_callback_state);
break;
case BPF_FUNC_find_vma:
err = push_callback_call(env, insn, insn_idx, meta.subprogno,
set_find_vma_callback_state);
break;
case BPF_FUNC_snprintf:
err = check_bpf_snprintf_call(env, regs);
break;
case BPF_FUNC_loop:
update_loop_inline_state(env, meta.subprogno);
/* Verifier relies on R1 value to determine if bpf_loop() iteration
* is finished, thus mark it precise.
*/
err = mark_chain_precision(env, BPF_REG_1);
if (err)
return err;
if (cur_func(env)->callback_depth < regs[BPF_REG_1].umax_value) {
err = push_callback_call(env, insn, insn_idx, meta.subprogno,
set_loop_callback_state);
} else {
cur_func(env)->callback_depth = 0;
if (env->log.level & BPF_LOG_LEVEL2)
verbose(env, "frame%d bpf_loop iteration limit reached\n",
env->cur_state->curframe);
}
break;
case BPF_FUNC_dynptr_from_mem:
if (regs[BPF_REG_1].type != PTR_TO_MAP_VALUE) {
verbose(env, "Unsupported reg type %s for bpf_dynptr_from_mem data\n",
reg_type_str(env, regs[BPF_REG_1].type));
return -EACCES;
}
break;
case BPF_FUNC_set_retval:
if (prog_type == BPF_PROG_TYPE_LSM &&
env->prog->expected_attach_type == BPF_LSM_CGROUP) {
if (!env->prog->aux->attach_func_proto->type) {
/* Make sure programs that attach to void
* hooks don't try to modify return value.
*/
verbose(env, "BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n");
return -EINVAL;
}
}
break;
case BPF_FUNC_dynptr_data:
{
struct bpf_reg_state *reg;
int id, ref_obj_id;
reg = get_dynptr_arg_reg(env, fn, regs);
if (!reg)
return -EFAULT;
if (meta.dynptr_id) {
verbose(env, "verifier internal error: meta.dynptr_id already set\n");
return -EFAULT;
}
if (meta.ref_obj_id) {
verbose(env, "verifier internal error: meta.ref_obj_id already set\n");
return -EFAULT;
}
id = dynptr_id(env, reg);
if (id < 0) {
verbose(env, "verifier internal error: failed to obtain dynptr id\n");
return id;
}
ref_obj_id = dynptr_ref_obj_id(env, reg);
if (ref_obj_id < 0) {
verbose(env, "verifier internal error: failed to obtain dynptr ref_obj_id\n");
return ref_obj_id;
}
meta.dynptr_id = id;
meta.ref_obj_id = ref_obj_id;
break;
}
case BPF_FUNC_dynptr_write:
{
enum bpf_dynptr_type dynptr_type;
struct bpf_reg_state *reg;
reg = get_dynptr_arg_reg(env, fn, regs);
if (!reg)
return -EFAULT;
dynptr_type = dynptr_get_type(env, reg);
if (dynptr_type == BPF_DYNPTR_TYPE_INVALID)
return -EFAULT;
if (dynptr_type == BPF_DYNPTR_TYPE_SKB)
/* this will trigger clear_all_pkt_pointers(), which will
* invalidate all dynptr slices associated with the skb
*/
changes_data = true;
break;
}
case BPF_FUNC_per_cpu_ptr:
case BPF_FUNC_this_cpu_ptr:
{
struct bpf_reg_state *reg = ®s[BPF_REG_1];
const struct btf_type *type;
if (reg->type & MEM_RCU) {
type = btf_type_by_id(reg->btf, reg->btf_id);
if (!type || !btf_type_is_struct(type)) {
verbose(env, "Helper has invalid btf/btf_id in R1\n");
return -EFAULT;
}
returns_cpu_specific_alloc_ptr = true;
env->insn_aux_data[insn_idx].call_with_percpu_alloc_ptr = true;
}
break;
}
case BPF_FUNC_user_ringbuf_drain:
err = push_callback_call(env, insn, insn_idx, meta.subprogno,
set_user_ringbuf_callback_state);
break;
}
if (err)
return err;
/* reset caller saved regs */
for (i = 0; i < CALLER_SAVED_REGS; i++) {
mark_reg_not_init(env, regs, caller_saved[i]);
check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
}
/* helper call returns 64-bit value. */
regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;
/* update return register (already marked as written above) */
ret_type = fn->ret_type;
ret_flag = type_flag(ret_type);
switch (base_type(ret_type)) {
case RET_INTEGER:
/* sets type to SCALAR_VALUE */
mark_reg_unknown(env, regs, BPF_REG_0);
break;
case RET_VOID:
regs[BPF_REG_0].type = NOT_INIT;
break;
case RET_PTR_TO_MAP_VALUE:
/* There is no offset yet applied, variable or fixed */
mark_reg_known_zero(env, regs, BPF_REG_0);
/* remember map_ptr, so that check_map_access()
* can check 'value_size' boundary of memory access
* to map element returned from bpf_map_lookup_elem()
*/
if (meta.map_ptr == NULL) {
verbose(env,
"kernel subsystem misconfigured verifier\n");
return -EINVAL;
}
regs[BPF_REG_0].map_ptr = meta.map_ptr;
regs[BPF_REG_0].map_uid = meta.map_uid;
regs[BPF_REG_0].type = PTR_TO_MAP_VALUE | ret_flag;
if (!type_may_be_null(ret_type) &&
btf_record_has_field(meta.map_ptr->record, BPF_SPIN_LOCK)) {
regs[BPF_REG_0].id = ++env->id_gen;
}
break;
case RET_PTR_TO_SOCKET:
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].type = PTR_TO_SOCKET | ret_flag;
break;
case RET_PTR_TO_SOCK_COMMON:
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON | ret_flag;
break;
case RET_PTR_TO_TCP_SOCK:
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].type = PTR_TO_TCP_SOCK | ret_flag;
break;
case RET_PTR_TO_MEM:
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
regs[BPF_REG_0].mem_size = meta.mem_size;
break;
case RET_PTR_TO_MEM_OR_BTF_ID:
{
const struct btf_type *t;
mark_reg_known_zero(env, regs, BPF_REG_0);
t = btf_type_skip_modifiers(meta.ret_btf, meta.ret_btf_id, NULL);
if (!btf_type_is_struct(t)) {
u32 tsize;
const struct btf_type *ret;
const char *tname;
/* resolve the type size of ksym. */
ret = btf_resolve_size(meta.ret_btf, t, &tsize);
if (IS_ERR(ret)) {
tname = btf_name_by_offset(meta.ret_btf, t->name_off);
verbose(env, "unable to resolve the size of type '%s': %ld\n",
tname, PTR_ERR(ret));
return -EINVAL;
}
regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
regs[BPF_REG_0].mem_size = tsize;
} else {
if (returns_cpu_specific_alloc_ptr) {
regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC | MEM_RCU;
} else {
/* MEM_RDONLY may be carried from ret_flag, but it
* doesn't apply on PTR_TO_BTF_ID. Fold it, otherwise
* it will confuse the check of PTR_TO_BTF_ID in
* check_mem_access().
*/
ret_flag &= ~MEM_RDONLY;
regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
}
regs[BPF_REG_0].btf = meta.ret_btf;
regs[BPF_REG_0].btf_id = meta.ret_btf_id;
}
break;
}
case RET_PTR_TO_BTF_ID:
{
struct btf *ret_btf;
int ret_btf_id;
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
if (func_id == BPF_FUNC_kptr_xchg) {
ret_btf = meta.kptr_field->kptr.btf;
ret_btf_id = meta.kptr_field->kptr.btf_id;
if (!btf_is_kernel(ret_btf)) {
regs[BPF_REG_0].type |= MEM_ALLOC;
if (meta.kptr_field->type == BPF_KPTR_PERCPU)
regs[BPF_REG_0].type |= MEM_PERCPU;
}
} else {
if (fn->ret_btf_id == BPF_PTR_POISON) {
verbose(env, "verifier internal error:");
verbose(env, "func %s has non-overwritten BPF_PTR_POISON return type\n",
func_id_name(func_id));
return -EINVAL;
}
ret_btf = btf_vmlinux;
ret_btf_id = *fn->ret_btf_id;
}
if (ret_btf_id == 0) {
verbose(env, "invalid return type %u of func %s#%d\n",
base_type(ret_type), func_id_name(func_id),
func_id);
return -EINVAL;
}
regs[BPF_REG_0].btf = ret_btf;
regs[BPF_REG_0].btf_id = ret_btf_id;
break;
}
default:
verbose(env, "unknown return type %u of func %s#%d\n",
base_type(ret_type), func_id_name(func_id), func_id);
return -EINVAL;
}
if (type_may_be_null(regs[BPF_REG_0].type))
regs[BPF_REG_0].id = ++env->id_gen;
if (helper_multiple_ref_obj_use(func_id, meta.map_ptr)) {
verbose(env, "verifier internal error: func %s#%d sets ref_obj_id more than once\n",
func_id_name(func_id), func_id);
return -EFAULT;
}
if (is_dynptr_ref_function(func_id))
regs[BPF_REG_0].dynptr_id = meta.dynptr_id;
if (is_ptr_cast_function(func_id) || is_dynptr_ref_function(func_id)) {
/* For release_reference() */
regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;
} else if (is_acquire_function(func_id, meta.map_ptr)) {
int id = acquire_reference_state(env, insn_idx);
if (id < 0)
return id;
/* For mark_ptr_or_null_reg() */
regs[BPF_REG_0].id = id;
/* For release_reference() */
regs[BPF_REG_0].ref_obj_id = id;
}
err = do_refine_retval_range(env, regs, fn->ret_type, func_id, &meta);
if (err)
return err;
err = check_map_func_compatibility(env, meta.map_ptr, func_id);
if (err)
return err;
if ((func_id == BPF_FUNC_get_stack ||
func_id == BPF_FUNC_get_task_stack) &&
!env->prog->has_callchain_buf) {
const char *err_str;
#ifdef CONFIG_PERF_EVENTS
err = get_callchain_buffers(sysctl_perf_event_max_stack);
err_str = "cannot get callchain buffer for func %s#%d\n";
#else
err = -ENOTSUPP;
err_str = "func %s#%d not supported without CONFIG_PERF_EVENTS\n";
#endif
if (err) {
verbose(env, err_str, func_id_name(func_id), func_id);
return err;
}
env->prog->has_callchain_buf = true;
}
if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack)
env->prog->call_get_stack = true;
if (func_id == BPF_FUNC_get_func_ip) {
if (check_get_func_ip(env))
return -ENOTSUPP;
env->prog->call_get_func_ip = true;
}
if (changes_data)
clear_all_pkt_pointers(env);
return 0;
}
/* mark_btf_func_reg_size() is used when the reg size is determined by
* the BTF func_proto's return value size and argument.
*/
static void mark_btf_func_reg_size(struct bpf_verifier_env *env, u32 regno,
size_t reg_size)
{
struct bpf_reg_state *reg = &cur_regs(env)[regno];
if (regno == BPF_REG_0) {
/* Function return value */
reg->live |= REG_LIVE_WRITTEN;
reg->subreg_def = reg_size == sizeof(u64) ?
DEF_NOT_SUBREG : env->insn_idx + 1;
} else {
/* Function argument */
if (reg_size == sizeof(u64)) {
mark_insn_zext(env, reg);
mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
} else {
mark_reg_read(env, reg, reg->parent, REG_LIVE_READ32);
}
}
}
static bool is_kfunc_acquire(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->kfunc_flags & KF_ACQUIRE;
}
static bool is_kfunc_release(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->kfunc_flags & KF_RELEASE;
}
static bool is_kfunc_trusted_args(struct bpf_kfunc_call_arg_meta *meta)
{
return (meta->kfunc_flags & KF_TRUSTED_ARGS) || is_kfunc_release(meta);
}
static bool is_kfunc_sleepable(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->kfunc_flags & KF_SLEEPABLE;
}
static bool is_kfunc_destructive(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->kfunc_flags & KF_DESTRUCTIVE;
}
static bool is_kfunc_rcu(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->kfunc_flags & KF_RCU;
}
static bool is_kfunc_rcu_protected(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->kfunc_flags & KF_RCU_PROTECTED;
}
static bool is_kfunc_arg_mem_size(const struct btf *btf,
const struct btf_param *arg,
const struct bpf_reg_state *reg)
{
const struct btf_type *t;
t = btf_type_skip_modifiers(btf, arg->type, NULL);
if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE)
return false;
return btf_param_match_suffix(btf, arg, "__sz");
}
static bool is_kfunc_arg_const_mem_size(const struct btf *btf,
const struct btf_param *arg,
const struct bpf_reg_state *reg)
{
const struct btf_type *t;
t = btf_type_skip_modifiers(btf, arg->type, NULL);
if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE)
return false;
return btf_param_match_suffix(btf, arg, "__szk");
}
static bool is_kfunc_arg_optional(const struct btf *btf, const struct btf_param *arg)
{
return btf_param_match_suffix(btf, arg, "__opt");
}
static bool is_kfunc_arg_constant(const struct btf *btf, const struct btf_param *arg)
{
return btf_param_match_suffix(btf, arg, "__k");
}
static bool is_kfunc_arg_ignore(const struct btf *btf, const struct btf_param *arg)
{
return btf_param_match_suffix(btf, arg, "__ign");
}
static bool is_kfunc_arg_map(const struct btf *btf, const struct btf_param *arg)
{
return btf_param_match_suffix(btf, arg, "__map");
}
static bool is_kfunc_arg_alloc_obj(const struct btf *btf, const struct btf_param *arg)
{
return btf_param_match_suffix(btf, arg, "__alloc");
}
static bool is_kfunc_arg_uninit(const struct btf *btf, const struct btf_param *arg)
{
return btf_param_match_suffix(btf, arg, "__uninit");
}
static bool is_kfunc_arg_refcounted_kptr(const struct btf *btf, const struct btf_param *arg)
{
return btf_param_match_suffix(btf, arg, "__refcounted_kptr");
}
static bool is_kfunc_arg_nullable(const struct btf *btf, const struct btf_param *arg)
{
return btf_param_match_suffix(btf, arg, "__nullable");
}
static bool is_kfunc_arg_const_str(const struct btf *btf, const struct btf_param *arg)
{
return btf_param_match_suffix(btf, arg, "__str");
}
static bool is_kfunc_arg_scalar_with_name(const struct btf *btf,
const struct btf_param *arg,
const char *name)
{
int len, target_len = strlen(name);
const char *param_name;
param_name = btf_name_by_offset(btf, arg->name_off);
if (str_is_empty(param_name))
return false;
len = strlen(param_name);
if (len != target_len)
return false;
if (strcmp(param_name, name))
return false;
return true;
}
enum {
KF_ARG_DYNPTR_ID,
KF_ARG_LIST_HEAD_ID,
KF_ARG_LIST_NODE_ID,
KF_ARG_RB_ROOT_ID,
KF_ARG_RB_NODE_ID,
KF_ARG_WORKQUEUE_ID,
};
BTF_ID_LIST(kf_arg_btf_ids)
BTF_ID(struct, bpf_dynptr)
BTF_ID(struct, bpf_list_head)
BTF_ID(struct, bpf_list_node)
BTF_ID(struct, bpf_rb_root)
BTF_ID(struct, bpf_rb_node)
BTF_ID(struct, bpf_wq)
static bool __is_kfunc_ptr_arg_type(const struct btf *btf,
const struct btf_param *arg, int type)
{
const struct btf_type *t;
u32 res_id;
t = btf_type_skip_modifiers(btf, arg->type, NULL);
if (!t)
return false;
if (!btf_type_is_ptr(t))
return false;
t = btf_type_skip_modifiers(btf, t->type, &res_id);
if (!t)
return false;
return btf_types_are_same(btf, res_id, btf_vmlinux, kf_arg_btf_ids[type]);
}
static bool is_kfunc_arg_dynptr(const struct btf *btf, const struct btf_param *arg)
{
return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_DYNPTR_ID);
}
static bool is_kfunc_arg_list_head(const struct btf *btf, const struct btf_param *arg)
{
return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_LIST_HEAD_ID);
}
static bool is_kfunc_arg_list_node(const struct btf *btf, const struct btf_param *arg)
{
return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_LIST_NODE_ID);
}
static bool is_kfunc_arg_rbtree_root(const struct btf *btf, const struct btf_param *arg)
{
return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_ROOT_ID);
}
static bool is_kfunc_arg_rbtree_node(const struct btf *btf, const struct btf_param *arg)
{
return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_NODE_ID);
}
static bool is_kfunc_arg_wq(const struct btf *btf, const struct btf_param *arg)
{
return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_WORKQUEUE_ID);
}
static bool is_kfunc_arg_callback(struct bpf_verifier_env *env, const struct btf *btf,
const struct btf_param *arg)
{
const struct btf_type *t;
t = btf_type_resolve_func_ptr(btf, arg->type, NULL);
if (!t)
return false;
return true;
}
/* Returns true if struct is composed of scalars, 4 levels of nesting allowed */
static bool __btf_type_is_scalar_struct(struct bpf_verifier_env *env,
const struct btf *btf,
const struct btf_type *t, int rec)
{
const struct btf_type *member_type;
const struct btf_member *member;
u32 i;
if (!btf_type_is_struct(t))
return false;
for_each_member(i, t, member) {
const struct btf_array *array;
member_type = btf_type_skip_modifiers(btf, member->type, NULL);
if (btf_type_is_struct(member_type)) {
if (rec >= 3) {
verbose(env, "max struct nesting depth exceeded\n");
return false;
}
if (!__btf_type_is_scalar_struct(env, btf, member_type, rec + 1))
return false;
continue;
}
if (btf_type_is_array(member_type)) {
array = btf_array(member_type);
if (!array->nelems)
return false;
member_type = btf_type_skip_modifiers(btf, array->type, NULL);
if (!btf_type_is_scalar(member_type))
return false;
continue;
}
if (!btf_type_is_scalar(member_type))
return false;
}
return true;
}
enum kfunc_ptr_arg_type {
KF_ARG_PTR_TO_CTX,
KF_ARG_PTR_TO_ALLOC_BTF_ID, /* Allocated object */
KF_ARG_PTR_TO_REFCOUNTED_KPTR, /* Refcounted local kptr */
KF_ARG_PTR_TO_DYNPTR,
KF_ARG_PTR_TO_ITER,
KF_ARG_PTR_TO_LIST_HEAD,
KF_ARG_PTR_TO_LIST_NODE,
KF_ARG_PTR_TO_BTF_ID, /* Also covers reg2btf_ids conversions */
KF_ARG_PTR_TO_MEM,
KF_ARG_PTR_TO_MEM_SIZE, /* Size derived from next argument, skip it */
KF_ARG_PTR_TO_CALLBACK,
KF_ARG_PTR_TO_RB_ROOT,
KF_ARG_PTR_TO_RB_NODE,
KF_ARG_PTR_TO_NULL,
KF_ARG_PTR_TO_CONST_STR,
KF_ARG_PTR_TO_MAP,
KF_ARG_PTR_TO_WORKQUEUE,
};
enum special_kfunc_type {
KF_bpf_obj_new_impl,
KF_bpf_obj_drop_impl,
KF_bpf_refcount_acquire_impl,
KF_bpf_list_push_front_impl,
KF_bpf_list_push_back_impl,
KF_bpf_list_pop_front,
KF_bpf_list_pop_back,
KF_bpf_cast_to_kern_ctx,
KF_bpf_rdonly_cast,
KF_bpf_rcu_read_lock,
KF_bpf_rcu_read_unlock,
KF_bpf_rbtree_remove,
KF_bpf_rbtree_add_impl,
KF_bpf_rbtree_first,
KF_bpf_dynptr_from_skb,
KF_bpf_dynptr_from_xdp,
KF_bpf_dynptr_slice,
KF_bpf_dynptr_slice_rdwr,
KF_bpf_dynptr_clone,
KF_bpf_percpu_obj_new_impl,
KF_bpf_percpu_obj_drop_impl,
KF_bpf_throw,
KF_bpf_wq_set_callback_impl,
KF_bpf_preempt_disable,
KF_bpf_preempt_enable,
KF_bpf_iter_css_task_new,
KF_bpf_session_cookie,
};
BTF_SET_START(special_kfunc_set)
BTF_ID(func, bpf_obj_new_impl)
BTF_ID(func, bpf_obj_drop_impl)
BTF_ID(func, bpf_refcount_acquire_impl)
BTF_ID(func, bpf_list_push_front_impl)
BTF_ID(func, bpf_list_push_back_impl)
BTF_ID(func, bpf_list_pop_front)
BTF_ID(func, bpf_list_pop_back)
BTF_ID(func, bpf_cast_to_kern_ctx)
BTF_ID(func, bpf_rdonly_cast)
BTF_ID(func, bpf_rbtree_remove)
BTF_ID(func, bpf_rbtree_add_impl)
BTF_ID(func, bpf_rbtree_first)
BTF_ID(func, bpf_dynptr_from_skb)
BTF_ID(func, bpf_dynptr_from_xdp)
BTF_ID(func, bpf_dynptr_slice)
BTF_ID(func, bpf_dynptr_slice_rdwr)
BTF_ID(func, bpf_dynptr_clone)
BTF_ID(func, bpf_percpu_obj_new_impl)
BTF_ID(func, bpf_percpu_obj_drop_impl)
BTF_ID(func, bpf_throw)
BTF_ID(func, bpf_wq_set_callback_impl)
#ifdef CONFIG_CGROUPS
BTF_ID(func, bpf_iter_css_task_new)
#endif
BTF_SET_END(special_kfunc_set)
BTF_ID_LIST(special_kfunc_list)
BTF_ID(func, bpf_obj_new_impl)
BTF_ID(func, bpf_obj_drop_impl)
BTF_ID(func, bpf_refcount_acquire_impl)
BTF_ID(func, bpf_list_push_front_impl)
BTF_ID(func, bpf_list_push_back_impl)
BTF_ID(func, bpf_list_pop_front)
BTF_ID(func, bpf_list_pop_back)
BTF_ID(func, bpf_cast_to_kern_ctx)
BTF_ID(func, bpf_rdonly_cast)
BTF_ID(func, bpf_rcu_read_lock)
BTF_ID(func, bpf_rcu_read_unlock)
BTF_ID(func, bpf_rbtree_remove)
BTF_ID(func, bpf_rbtree_add_impl)
BTF_ID(func, bpf_rbtree_first)
BTF_ID(func, bpf_dynptr_from_skb)
BTF_ID(func, bpf_dynptr_from_xdp)
BTF_ID(func, bpf_dynptr_slice)
BTF_ID(func, bpf_dynptr_slice_rdwr)
BTF_ID(func, bpf_dynptr_clone)
BTF_ID(func, bpf_percpu_obj_new_impl)
BTF_ID(func, bpf_percpu_obj_drop_impl)
BTF_ID(func, bpf_throw)
BTF_ID(func, bpf_wq_set_callback_impl)
BTF_ID(func, bpf_preempt_disable)
BTF_ID(func, bpf_preempt_enable)
#ifdef CONFIG_CGROUPS
BTF_ID(func, bpf_iter_css_task_new)
#else
BTF_ID_UNUSED
#endif
#ifdef CONFIG_BPF_EVENTS
BTF_ID(func, bpf_session_cookie)
#else
BTF_ID_UNUSED
#endif
static bool is_kfunc_ret_null(struct bpf_kfunc_call_arg_meta *meta)
{
if (meta->func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl] &&
meta->arg_owning_ref) {
return false;
}
return meta->kfunc_flags & KF_RET_NULL;
}
static bool is_kfunc_bpf_rcu_read_lock(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->func_id == special_kfunc_list[KF_bpf_rcu_read_lock];
}
static bool is_kfunc_bpf_rcu_read_unlock(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->func_id == special_kfunc_list[KF_bpf_rcu_read_unlock];
}
static bool is_kfunc_bpf_preempt_disable(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->func_id == special_kfunc_list[KF_bpf_preempt_disable];
}
static bool is_kfunc_bpf_preempt_enable(struct bpf_kfunc_call_arg_meta *meta)
{
return meta->func_id == special_kfunc_list[KF_bpf_preempt_enable];
}
static enum kfunc_ptr_arg_type
get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
struct bpf_kfunc_call_arg_meta *meta,
const struct btf_type *t, const struct btf_type *ref_t,
const char *ref_tname, const struct btf_param *args,
int argno, int nargs)
{
u32 regno = argno + 1;
struct bpf_reg_state *regs = cur_regs(env);
struct bpf_reg_state *reg = ®s[regno];
bool arg_mem_size = false;
if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx])
return KF_ARG_PTR_TO_CTX;
/* In this function, we verify the kfunc's BTF as per the argument type,
* leaving the rest of the verification with respect to the register
* type to our caller. When a set of conditions hold in the BTF type of
* arguments, we resolve it to a known kfunc_ptr_arg_type.
*/
if (btf_is_prog_ctx_type(&env->log, meta->btf, t, resolve_prog_type(env->prog), argno))
return KF_ARG_PTR_TO_CTX;
if (is_kfunc_arg_nullable(meta->btf, &args[argno]) && register_is_null(reg))
return KF_ARG_PTR_TO_NULL;
if (is_kfunc_arg_alloc_obj(meta->btf, &args[argno]))
return KF_ARG_PTR_TO_ALLOC_BTF_ID;
if (is_kfunc_arg_refcounted_kptr(meta->btf, &args[argno]))
return KF_ARG_PTR_TO_REFCOUNTED_KPTR;
if (is_kfunc_arg_dynptr(meta->btf, &args[argno]))
return KF_ARG_PTR_TO_DYNPTR;
if (is_kfunc_arg_iter(meta, argno, &args[argno]))
return KF_ARG_PTR_TO_ITER;
if (is_kfunc_arg_list_head(meta->btf, &args[argno]))
return KF_ARG_PTR_TO_LIST_HEAD;
if (is_kfunc_arg_list_node(meta->btf, &args[argno]))
return KF_ARG_PTR_TO_LIST_NODE;
if (is_kfunc_arg_rbtree_root(meta->btf, &args[argno]))
return KF_ARG_PTR_TO_RB_ROOT;
if (is_kfunc_arg_rbtree_node(meta->btf, &args[argno]))
return KF_ARG_PTR_TO_RB_NODE;
if (is_kfunc_arg_const_str(meta->btf, &args[argno]))
return KF_ARG_PTR_TO_CONST_STR;
if (is_kfunc_arg_map(meta->btf, &args[argno]))
return KF_ARG_PTR_TO_MAP;
if (is_kfunc_arg_wq(meta->btf, &args[argno]))
return KF_ARG_PTR_TO_WORKQUEUE;
if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) {
if (!btf_type_is_struct(ref_t)) {
verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n",
meta->func_name, argno, btf_type_str(ref_t), ref_tname);
return -EINVAL;
}
return KF_ARG_PTR_TO_BTF_ID;
}
if (is_kfunc_arg_callback(env, meta->btf, &args[argno]))
return KF_ARG_PTR_TO_CALLBACK;
if (argno + 1 < nargs &&
(is_kfunc_arg_mem_size(meta->btf, &args[argno + 1], ®s[regno + 1]) ||
is_kfunc_arg_const_mem_size(meta->btf, &args[argno + 1], ®s[regno + 1])))
arg_mem_size = true;
/* This is the catch all argument type of register types supported by
* check_helper_mem_access. However, we only allow when argument type is
* pointer to scalar, or struct composed (recursively) of scalars. When
* arg_mem_size is true, the pointer can be void *.
*/
if (!btf_type_is_scalar(ref_t) && !__btf_type_is_scalar_struct(env, meta->btf, ref_t, 0) &&
(arg_mem_size ? !btf_type_is_void(ref_t) : 1)) {
verbose(env, "arg#%d pointer type %s %s must point to %sscalar, or struct with scalar\n",
argno, btf_type_str(ref_t), ref_tname, arg_mem_size ? "void, " : "");
return -EINVAL;
}
return arg_mem_size ? KF_ARG_PTR_TO_MEM_SIZE : KF_ARG_PTR_TO_MEM;
}
static int process_kf_arg_ptr_to_btf_id(struct bpf_verifier_env *env,
struct bpf_reg_state *reg,
const struct btf_type *ref_t,
const char *ref_tname, u32 ref_id,
struct bpf_kfunc_call_arg_meta *meta,
int argno)
{
const struct btf_type *reg_ref_t;
bool strict_type_match = false;
const struct btf *reg_btf;
const char *reg_ref_tname;
bool taking_projection;
bool struct_same;
u32 reg_ref_id;
if (base_type(reg->type) == PTR_TO_BTF_ID) {
reg_btf = reg->btf;
reg_ref_id = reg->btf_id;
} else {
reg_btf = btf_vmlinux;
reg_ref_id = *reg2btf_ids[base_type(reg->type)];
}
/* Enforce strict type matching for calls to kfuncs that are acquiring
* or releasing a reference, or are no-cast aliases. We do _not_
* enforce strict matching for plain KF_TRUSTED_ARGS kfuncs by default,
* as we want to enable BPF programs to pass types that are bitwise
* equivalent without forcing them to explicitly cast with something
* like bpf_cast_to_kern_ctx().
*
* For example, say we had a type like the following:
*
* struct bpf_cpumask {
* cpumask_t cpumask;
* refcount_t usage;
* };
*
* Note that as specified in <linux/cpumask.h>, cpumask_t is typedef'ed
* to a struct cpumask, so it would be safe to pass a struct
* bpf_cpumask * to a kfunc expecting a struct cpumask *.
*
* The philosophy here is similar to how we allow scalars of different
* types to be passed to kfuncs as long as the size is the same. The
* only difference here is that we're simply allowing
* btf_struct_ids_match() to walk the struct at the 0th offset, and
* resolve types.
*/
if ((is_kfunc_release(meta) && reg->ref_obj_id) ||
btf_type_ids_nocast_alias(&env->log, reg_btf, reg_ref_id, meta->btf, ref_id))
strict_type_match = true;
WARN_ON_ONCE(is_kfunc_release(meta) &&
(reg->off || !tnum_is_const(reg->var_off) ||
reg->var_off.value));
reg_ref_t = btf_type_skip_modifiers(reg_btf, reg_ref_id, ®_ref_id);
reg_ref_tname = btf_name_by_offset(reg_btf, reg_ref_t->name_off);
struct_same = btf_struct_ids_match(&env->log, reg_btf, reg_ref_id, reg->off, meta->btf, ref_id, strict_type_match);
/* If kfunc is accepting a projection type (ie. __sk_buff), it cannot
* actually use it -- it must cast to the underlying type. So we allow
* caller to pass in the underlying type.
*/
taking_projection = btf_is_projection_of(ref_tname, reg_ref_tname);
if (!taking_projection && !struct_same) {
verbose(env, "kernel function %s args#%d expected pointer to %s %s but R%d has a pointer to %s %s\n",
meta->func_name, argno, btf_type_str(ref_t), ref_tname, argno + 1,
btf_type_str(reg_ref_t), reg_ref_tname);
return -EINVAL;
}
return 0;
}
static int ref_set_non_owning(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
struct bpf_verifier_state *state = env->cur_state;
struct btf_record *rec = reg_btf_record(reg);
if (!state->active_lock.ptr) {
verbose(env, "verifier internal error: ref_set_non_owning w/o active lock\n");
return -EFAULT;
}
if (type_flag(reg->type) & NON_OWN_REF) {
verbose(env, "verifier internal error: NON_OWN_REF already set\n");
return -EFAULT;
}
reg->type |= NON_OWN_REF;
if (rec->refcount_off >= 0)
reg->type |= MEM_RCU;
return 0;
}
static int ref_convert_owning_non_owning(struct bpf_verifier_env *env, u32 ref_obj_id)
{
struct bpf_func_state *state, *unused;
struct bpf_reg_state *reg;
int i;
state = cur_func(env);
if (!ref_obj_id) {
verbose(env, "verifier internal error: ref_obj_id is zero for "
"owning -> non-owning conversion\n");
return -EFAULT;
}
for (i = 0; i < state->acquired_refs; i++) {
if (state->refs[i].id != ref_obj_id)
continue;
/* Clear ref_obj_id here so release_reference doesn't clobber
* the whole reg
*/
bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({
if (reg->ref_obj_id == ref_obj_id) {
reg->ref_obj_id = 0;
ref_set_non_owning(env, reg);
}
}));
return 0;
}
verbose(env, "verifier internal error: ref state missing for ref_obj_id\n");
return -EFAULT;
}
/* Implementation details:
*
* Each register points to some region of memory, which we define as an
* allocation. Each allocation may embed a bpf_spin_lock which protects any
* special BPF objects (bpf_list_head, bpf_rb_root, etc.) part of the same
* allocation. The lock and the data it protects are colocated in the same
* memory region.
*
* Hence, everytime a register holds a pointer value pointing to such
* allocation, the verifier preserves a unique reg->id for it.
*
* The verifier remembers the lock 'ptr' and the lock 'id' whenever
* bpf_spin_lock is called.
*
* To enable this, lock state in the verifier captures two values:
* active_lock.ptr = Register's type specific pointer
* active_lock.id = A unique ID for each register pointer value
*
* Currently, PTR_TO_MAP_VALUE and PTR_TO_BTF_ID | MEM_ALLOC are the two
* supported register types.
*
* The active_lock.ptr in case of map values is the reg->map_ptr, and in case of
* allocated objects is the reg->btf pointer.
*
* The active_lock.id is non-unique for maps supporting direct_value_addr, as we
* can establish the provenance of the map value statically for each distinct
* lookup into such maps. They always contain a single map value hence unique
* IDs for each pseudo load pessimizes the algorithm and rejects valid programs.
*
* So, in case of global variables, they use array maps with max_entries = 1,
* hence their active_lock.ptr becomes map_ptr and id = 0 (since they all point
* into the same map value as max_entries is 1, as described above).
*
* In case of inner map lookups, the inner map pointer has same map_ptr as the
* outer map pointer (in verifier context), but each lookup into an inner map
* assigns a fresh reg->id to the lookup, so while lookups into distinct inner
* maps from the same outer map share the same map_ptr as active_lock.ptr, they
* will get different reg->id assigned to each lookup, hence different
* active_lock.id.
*
* In case of allocated objects, active_lock.ptr is the reg->btf, and the
* reg->id is a unique ID preserved after the NULL pointer check on the pointer
* returned from bpf_obj_new. Each allocation receives a new reg->id.
*/
static int check_reg_allocation_locked(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
void *ptr;
u32 id;
switch ((int)reg->type) {
case PTR_TO_MAP_VALUE:
ptr = reg->map_ptr;
break;
case PTR_TO_BTF_ID | MEM_ALLOC:
ptr = reg->btf;
break;
default:
verbose(env, "verifier internal error: unknown reg type for lock check\n");
return -EFAULT;
}
id = reg->id;
if (!env->cur_state->active_lock.ptr)
return -EINVAL;
if (env->cur_state->active_lock.ptr != ptr ||
env->cur_state->active_lock.id != id) {
verbose(env, "held lock and object are not in the same allocation\n");
return -EINVAL;
}
return 0;
}
static bool is_bpf_list_api_kfunc(u32 btf_id)
{
return btf_id == special_kfunc_list[KF_bpf_list_push_front_impl] ||
btf_id == special_kfunc_list[KF_bpf_list_push_back_impl] ||
btf_id == special_kfunc_list[KF_bpf_list_pop_front] ||
btf_id == special_kfunc_list[KF_bpf_list_pop_back];
}
static bool is_bpf_rbtree_api_kfunc(u32 btf_id)
{
return btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl] ||
btf_id == special_kfunc_list[KF_bpf_rbtree_remove] ||
btf_id == special_kfunc_list[KF_bpf_rbtree_first];
}
static bool is_bpf_graph_api_kfunc(u32 btf_id)
{
return is_bpf_list_api_kfunc(btf_id) || is_bpf_rbtree_api_kfunc(btf_id) ||
btf_id == special_kfunc_list[KF_bpf_refcount_acquire_impl];
}
static bool is_sync_callback_calling_kfunc(u32 btf_id)
{
return btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl];
}
static bool is_async_callback_calling_kfunc(u32 btf_id)
{
return btf_id == special_kfunc_list[KF_bpf_wq_set_callback_impl];
}
static bool is_bpf_throw_kfunc(struct bpf_insn *insn)
{
return bpf_pseudo_kfunc_call(insn) && insn->off == 0 &&
insn->imm == special_kfunc_list[KF_bpf_throw];
}
static bool is_bpf_wq_set_callback_impl_kfunc(u32 btf_id)
{
return btf_id == special_kfunc_list[KF_bpf_wq_set_callback_impl];
}
static bool is_callback_calling_kfunc(u32 btf_id)
{
return is_sync_callback_calling_kfunc(btf_id) ||
is_async_callback_calling_kfunc(btf_id);
}
static bool is_rbtree_lock_required_kfunc(u32 btf_id)
{
return is_bpf_rbtree_api_kfunc(btf_id);
}
static bool check_kfunc_is_graph_root_api(struct bpf_verifier_env *env,
enum btf_field_type head_field_type,
u32 kfunc_btf_id)
{
bool ret;
switch (head_field_type) {
case BPF_LIST_HEAD:
ret = is_bpf_list_api_kfunc(kfunc_btf_id);
break;
case BPF_RB_ROOT:
ret = is_bpf_rbtree_api_kfunc(kfunc_btf_id);
break;
default:
verbose(env, "verifier internal error: unexpected graph root argument type %s\n",
btf_field_type_name(head_field_type));
return false;
}
if (!ret)
verbose(env, "verifier internal error: %s head arg for unknown kfunc\n",
btf_field_type_name(head_field_type));
return ret;
}
static bool check_kfunc_is_graph_node_api(struct bpf_verifier_env *env,
enum btf_field_type node_field_type,
u32 kfunc_btf_id)
{
bool ret;
switch (node_field_type) {
case BPF_LIST_NODE:
ret = (kfunc_btf_id == special_kfunc_list[KF_bpf_list_push_front_impl] ||
kfunc_btf_id == special_kfunc_list[KF_bpf_list_push_back_impl]);
break;
case BPF_RB_NODE:
ret = (kfunc_btf_id == special_kfunc_list[KF_bpf_rbtree_remove] ||
kfunc_btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl]);
break;
default:
verbose(env, "verifier internal error: unexpected graph node argument type %s\n",
btf_field_type_name(node_field_type));
return false;
}
if (!ret)
verbose(env, "verifier internal error: %s node arg for unknown kfunc\n",
btf_field_type_name(node_field_type));
return ret;
}
static int
__process_kf_arg_ptr_to_graph_root(struct bpf_verifier_env *env,
struct bpf_reg_state *reg, u32 regno,
struct bpf_kfunc_call_arg_meta *meta,
enum btf_field_type head_field_type,
struct btf_field **head_field)
{
const char *head_type_name;
struct btf_field *field;
struct btf_record *rec;
u32 head_off;
if (meta->btf != btf_vmlinux) {
verbose(env, "verifier internal error: unexpected btf mismatch in kfunc call\n");
return -EFAULT;
}
if (!check_kfunc_is_graph_root_api(env, head_field_type, meta->func_id))
return -EFAULT;
head_type_name = btf_field_type_name(head_field_type);
if (!tnum_is_const(reg->var_off)) {
verbose(env,
"R%d doesn't have constant offset. %s has to be at the constant offset\n",
regno, head_type_name);
return -EINVAL;
}
rec = reg_btf_record(reg);
head_off = reg->off + reg->var_off.value;
field = btf_record_find(rec, head_off, head_field_type);
if (!field) {
verbose(env, "%s not found at offset=%u\n", head_type_name, head_off);
return -EINVAL;
}
/* All functions require bpf_list_head to be protected using a bpf_spin_lock */
if (check_reg_allocation_locked(env, reg)) {
verbose(env, "bpf_spin_lock at off=%d must be held for %s\n",
rec->spin_lock_off, head_type_name);
return -EINVAL;
}
if (*head_field) {
verbose(env, "verifier internal error: repeating %s arg\n", head_type_name);
return -EFAULT;
}
*head_field = field;
return 0;
}
static int process_kf_arg_ptr_to_list_head(struct bpf_verifier_env *env,
struct bpf_reg_state *reg, u32 regno,
struct bpf_kfunc_call_arg_meta *meta)
{
return __process_kf_arg_ptr_to_graph_root(env, reg, regno, meta, BPF_LIST_HEAD,
&meta->arg_list_head.field);
}
static int process_kf_arg_ptr_to_rbtree_root(struct bpf_verifier_env *env,
struct bpf_reg_state *reg, u32 regno,
struct bpf_kfunc_call_arg_meta *meta)
{
return __process_kf_arg_ptr_to_graph_root(env, reg, regno, meta, BPF_RB_ROOT,
&meta->arg_rbtree_root.field);
}
static int
__process_kf_arg_ptr_to_graph_node(struct bpf_verifier_env *env,
struct bpf_reg_state *reg, u32 regno,
struct bpf_kfunc_call_arg_meta *meta,
enum btf_field_type head_field_type,
enum btf_field_type node_field_type,
struct btf_field **node_field)
{
const char *node_type_name;
const struct btf_type *et, *t;
struct btf_field *field;
u32 node_off;
if (meta->btf != btf_vmlinux) {
verbose(env, "verifier internal error: unexpected btf mismatch in kfunc call\n");
return -EFAULT;
}
if (!check_kfunc_is_graph_node_api(env, node_field_type, meta->func_id))
return -EFAULT;
node_type_name = btf_field_type_name(node_field_type);
if (!tnum_is_const(reg->var_off)) {
verbose(env,
"R%d doesn't have constant offset. %s has to be at the constant offset\n",
regno, node_type_name);
return -EINVAL;
}
node_off = reg->off + reg->var_off.value;
field = reg_find_field_offset(reg, node_off, node_field_type);
if (!field) {
verbose(env, "%s not found at offset=%u\n", node_type_name, node_off);
return -EINVAL;
}
field = *node_field;
et = btf_type_by_id(field->graph_root.btf, field->graph_root.value_btf_id);
t = btf_type_by_id(reg->btf, reg->btf_id);
if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, 0, field->graph_root.btf,
field->graph_root.value_btf_id, true)) {
verbose(env, "operation on %s expects arg#1 %s at offset=%d "
"in struct %s, but arg is at offset=%d in struct %s\n",
btf_field_type_name(head_field_type),
btf_field_type_name(node_field_type),
field->graph_root.node_offset,
btf_name_by_offset(field->graph_root.btf, et->name_off),
node_off, btf_name_by_offset(reg->btf, t->name_off));
return -EINVAL;
}
meta->arg_btf = reg->btf;
meta->arg_btf_id = reg->btf_id;
if (node_off != field->graph_root.node_offset) {
verbose(env, "arg#1 offset=%d, but expected %s at offset=%d in struct %s\n",
node_off, btf_field_type_name(node_field_type),
field->graph_root.node_offset,
btf_name_by_offset(field->graph_root.btf, et->name_off));
return -EINVAL;
}
return 0;
}
static int process_kf_arg_ptr_to_list_node(struct bpf_verifier_env *env,
struct bpf_reg_state *reg, u32 regno,
struct bpf_kfunc_call_arg_meta *meta)
{
return __process_kf_arg_ptr_to_graph_node(env, reg, regno, meta,
BPF_LIST_HEAD, BPF_LIST_NODE,
&meta->arg_list_head.field);
}
static int process_kf_arg_ptr_to_rbtree_node(struct bpf_verifier_env *env,
struct bpf_reg_state *reg, u32 regno,
struct bpf_kfunc_call_arg_meta *meta)
{
return __process_kf_arg_ptr_to_graph_node(env, reg, regno, meta,
BPF_RB_ROOT, BPF_RB_NODE,
&meta->arg_rbtree_root.field);
}
/*
* css_task iter allowlist is needed to avoid dead locking on css_set_lock.
* LSM hooks and iters (both sleepable and non-sleepable) are safe.
* Any sleepable progs are also safe since bpf_check_attach_target() enforce
* them can only be attached to some specific hook points.
*/
static bool check_css_task_iter_allowlist(struct bpf_verifier_env *env)
{
enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
switch (prog_type) {
case BPF_PROG_TYPE_LSM:
return true;
case BPF_PROG_TYPE_TRACING:
if (env->prog->expected_attach_type == BPF_TRACE_ITER)
return true;
fallthrough;
default:
return in_sleepable(env);
}
}
static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_arg_meta *meta,
int insn_idx)
{
const char *func_name = meta->func_name, *ref_tname;
const struct btf *btf = meta->btf;
const struct btf_param *args;
struct btf_record *rec;
u32 i, nargs;
int ret;
args = (const struct btf_param *)(meta->func_proto + 1);
nargs = btf_type_vlen(meta->func_proto);
if (nargs > MAX_BPF_FUNC_REG_ARGS) {
verbose(env, "Function %s has %d > %d args\n", func_name, nargs,
MAX_BPF_FUNC_REG_ARGS);
return -EINVAL;
}
/* Check that BTF function arguments match actual types that the
* verifier sees.
*/
for (i = 0; i < nargs; i++) {
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[i + 1];
const struct btf_type *t, *ref_t, *resolve_ret;
enum bpf_arg_type arg_type = ARG_DONTCARE;
u32 regno = i + 1, ref_id, type_size;
bool is_ret_buf_sz = false;
int kf_arg_type;
t = btf_type_skip_modifiers(btf, args[i].type, NULL);
if (is_kfunc_arg_ignore(btf, &args[i]))
continue;
if (btf_type_is_scalar(t)) {
if (reg->type != SCALAR_VALUE) {
verbose(env, "R%d is not a scalar\n", regno);
return -EINVAL;
}
if (is_kfunc_arg_constant(meta->btf, &args[i])) {
if (meta->arg_constant.found) {
verbose(env, "verifier internal error: only one constant argument permitted\n");
return -EFAULT;
}
if (!tnum_is_const(reg->var_off)) {
verbose(env, "R%d must be a known constant\n", regno);
return -EINVAL;
}
ret = mark_chain_precision(env, regno);
if (ret < 0)
return ret;
meta->arg_constant.found = true;
meta->arg_constant.value = reg->var_off.value;
} else if (is_kfunc_arg_scalar_with_name(btf, &args[i], "rdonly_buf_size")) {
meta->r0_rdonly = true;
is_ret_buf_sz = true;
} else if (is_kfunc_arg_scalar_with_name(btf, &args[i], "rdwr_buf_size")) {
is_ret_buf_sz = true;
}
if (is_ret_buf_sz) {
if (meta->r0_size) {
verbose(env, "2 or more rdonly/rdwr_buf_size parameters for kfunc");
return -EINVAL;
}
if (!tnum_is_const(reg->var_off)) {
verbose(env, "R%d is not a const\n", regno);
return -EINVAL;
}
meta->r0_size = reg->var_off.value;
ret = mark_chain_precision(env, regno);
if (ret)
return ret;
}
continue;
}
if (!btf_type_is_ptr(t)) {
verbose(env, "Unrecognized arg#%d type %s\n", i, btf_type_str(t));
return -EINVAL;
}
if ((is_kfunc_trusted_args(meta) || is_kfunc_rcu(meta)) &&
(register_is_null(reg) || type_may_be_null(reg->type)) &&
!is_kfunc_arg_nullable(meta->btf, &args[i])) {
verbose(env, "Possibly NULL pointer passed to trusted arg%d\n", i);
return -EACCES;
}
if (reg->ref_obj_id) {
if (is_kfunc_release(meta) && meta->ref_obj_id) {
verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n",
regno, reg->ref_obj_id,
meta->ref_obj_id);
return -EFAULT;
}
meta->ref_obj_id = reg->ref_obj_id;
if (is_kfunc_release(meta))
meta->release_regno = regno;
}
ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
ref_tname = btf_name_by_offset(btf, ref_t->name_off);
kf_arg_type = get_kfunc_ptr_arg_type(env, meta, t, ref_t, ref_tname, args, i, nargs);
if (kf_arg_type < 0)
return kf_arg_type;
switch (kf_arg_type) {
case KF_ARG_PTR_TO_NULL:
continue;
case KF_ARG_PTR_TO_MAP:
if (!reg->map_ptr) {
verbose(env, "pointer in R%d isn't map pointer\n", regno);
return -EINVAL;
}
if (meta->map.ptr && reg->map_ptr->record->wq_off >= 0) {
/* Use map_uid (which is unique id of inner map) to reject:
* inner_map1 = bpf_map_lookup_elem(outer_map, key1)
* inner_map2 = bpf_map_lookup_elem(outer_map, key2)
* if (inner_map1 && inner_map2) {
* wq = bpf_map_lookup_elem(inner_map1);
* if (wq)
* // mismatch would have been allowed
* bpf_wq_init(wq, inner_map2);
* }
*
* Comparing map_ptr is enough to distinguish normal and outer maps.
*/
if (meta->map.ptr != reg->map_ptr ||
meta->map.uid != reg->map_uid) {
verbose(env,
"workqueue pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n",
meta->map.uid, reg->map_uid);
return -EINVAL;
}
}
meta->map.ptr = reg->map_ptr;
meta->map.uid = reg->map_uid;
fallthrough;
case KF_ARG_PTR_TO_ALLOC_BTF_ID:
case KF_ARG_PTR_TO_BTF_ID:
if (!is_kfunc_trusted_args(meta) && !is_kfunc_rcu(meta))
break;
if (!is_trusted_reg(reg)) {
if (!is_kfunc_rcu(meta)) {
verbose(env, "R%d must be referenced or trusted\n", regno);
return -EINVAL;
}
if (!is_rcu_reg(reg)) {
verbose(env, "R%d must be a rcu pointer\n", regno);
return -EINVAL;
}
}
fallthrough;
case KF_ARG_PTR_TO_CTX:
case KF_ARG_PTR_TO_DYNPTR:
case KF_ARG_PTR_TO_ITER:
case KF_ARG_PTR_TO_LIST_HEAD:
case KF_ARG_PTR_TO_LIST_NODE:
case KF_ARG_PTR_TO_RB_ROOT:
case KF_ARG_PTR_TO_RB_NODE:
case KF_ARG_PTR_TO_MEM:
case KF_ARG_PTR_TO_MEM_SIZE:
case KF_ARG_PTR_TO_CALLBACK:
case KF_ARG_PTR_TO_REFCOUNTED_KPTR:
case KF_ARG_PTR_TO_CONST_STR:
case KF_ARG_PTR_TO_WORKQUEUE:
break;
default:
WARN_ON_ONCE(1);
return -EFAULT;
}
if (is_kfunc_release(meta) && reg->ref_obj_id)
arg_type |= OBJ_RELEASE;
ret = check_func_arg_reg_off(env, reg, regno, arg_type);
if (ret < 0)
return ret;
switch (kf_arg_type) {
case KF_ARG_PTR_TO_CTX:
if (reg->type != PTR_TO_CTX) {
verbose(env, "arg#%d expected pointer to ctx, but got %s\n",
i, reg_type_str(env, reg->type));
return -EINVAL;
}
if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) {
ret = get_kern_ctx_btf_id(&env->log, resolve_prog_type(env->prog));
if (ret < 0)
return -EINVAL;
meta->ret_btf_id = ret;
}
break;
case KF_ARG_PTR_TO_ALLOC_BTF_ID:
if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC)) {
if (meta->func_id != special_kfunc_list[KF_bpf_obj_drop_impl]) {
verbose(env, "arg#%d expected for bpf_obj_drop_impl()\n", i);
return -EINVAL;
}
} else if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC | MEM_PERCPU)) {
if (meta->func_id != special_kfunc_list[KF_bpf_percpu_obj_drop_impl]) {
verbose(env, "arg#%d expected for bpf_percpu_obj_drop_impl()\n", i);
return -EINVAL;
}
} else {
verbose(env, "arg#%d expected pointer to allocated object\n", i);
return -EINVAL;
}
if (!reg->ref_obj_id) {
verbose(env, "allocated object must be referenced\n");
return -EINVAL;
}
if (meta->btf == btf_vmlinux) {
meta->arg_btf = reg->btf;
meta->arg_btf_id = reg->btf_id;
}
break;
case KF_ARG_PTR_TO_DYNPTR:
{
enum bpf_arg_type dynptr_arg_type = ARG_PTR_TO_DYNPTR;
int clone_ref_obj_id = 0;
if (reg->type == CONST_PTR_TO_DYNPTR)
dynptr_arg_type |= MEM_RDONLY;
if (is_kfunc_arg_uninit(btf, &args[i]))
dynptr_arg_type |= MEM_UNINIT;
if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) {
dynptr_arg_type |= DYNPTR_TYPE_SKB;
} else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_xdp]) {
dynptr_arg_type |= DYNPTR_TYPE_XDP;
} else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_clone] &&
(dynptr_arg_type & MEM_UNINIT)) {
enum bpf_dynptr_type parent_type = meta->initialized_dynptr.type;
if (parent_type == BPF_DYNPTR_TYPE_INVALID) {
verbose(env, "verifier internal error: no dynptr type for parent of clone\n");
return -EFAULT;
}
dynptr_arg_type |= (unsigned int)get_dynptr_type_flag(parent_type);
clone_ref_obj_id = meta->initialized_dynptr.ref_obj_id;
if (dynptr_type_refcounted(parent_type) && !clone_ref_obj_id) {
verbose(env, "verifier internal error: missing ref obj id for parent of clone\n");
return -EFAULT;
}
}
ret = process_dynptr_func(env, regno, insn_idx, dynptr_arg_type, clone_ref_obj_id);
if (ret < 0)
return ret;
if (!(dynptr_arg_type & MEM_UNINIT)) {
int id = dynptr_id(env, reg);
if (id < 0) {
verbose(env, "verifier internal error: failed to obtain dynptr id\n");
return id;
}
meta->initialized_dynptr.id = id;
meta->initialized_dynptr.type = dynptr_get_type(env, reg);
meta->initialized_dynptr.ref_obj_id = dynptr_ref_obj_id(env, reg);
}
break;
}
case KF_ARG_PTR_TO_ITER:
if (meta->func_id == special_kfunc_list[KF_bpf_iter_css_task_new]) {
if (!check_css_task_iter_allowlist(env)) {
verbose(env, "css_task_iter is only allowed in bpf_lsm, bpf_iter and sleepable progs\n");
return -EINVAL;
}
}
ret = process_iter_arg(env, regno, insn_idx, meta);
if (ret < 0)
return ret;
break;
case KF_ARG_PTR_TO_LIST_HEAD:
if (reg->type != PTR_TO_MAP_VALUE &&
reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
verbose(env, "arg#%d expected pointer to map value or allocated object\n", i);
return -EINVAL;
}
if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC) && !reg->ref_obj_id) {
verbose(env, "allocated object must be referenced\n");
return -EINVAL;
}
ret = process_kf_arg_ptr_to_list_head(env, reg, regno, meta);
if (ret < 0)
return ret;
break;
case KF_ARG_PTR_TO_RB_ROOT:
if (reg->type != PTR_TO_MAP_VALUE &&
reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
verbose(env, "arg#%d expected pointer to map value or allocated object\n", i);
return -EINVAL;
}
if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC) && !reg->ref_obj_id) {
verbose(env, "allocated object must be referenced\n");
return -EINVAL;
}
ret = process_kf_arg_ptr_to_rbtree_root(env, reg, regno, meta);
if (ret < 0)
return ret;
break;
case KF_ARG_PTR_TO_LIST_NODE:
if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
verbose(env, "arg#%d expected pointer to allocated object\n", i);
return -EINVAL;
}
if (!reg->ref_obj_id) {
verbose(env, "allocated object must be referenced\n");
return -EINVAL;
}
ret = process_kf_arg_ptr_to_list_node(env, reg, regno, meta);
if (ret < 0)
return ret;
break;
case KF_ARG_PTR_TO_RB_NODE:
if (meta->func_id == special_kfunc_list[KF_bpf_rbtree_remove]) {
if (!type_is_non_owning_ref(reg->type) || reg->ref_obj_id) {
verbose(env, "rbtree_remove node input must be non-owning ref\n");
return -EINVAL;
}
if (in_rbtree_lock_required_cb(env)) {
verbose(env, "rbtree_remove not allowed in rbtree cb\n");
return -EINVAL;
}
} else {
if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
verbose(env, "arg#%d expected pointer to allocated object\n", i);
return -EINVAL;
}
if (!reg->ref_obj_id) {
verbose(env, "allocated object must be referenced\n");
return -EINVAL;
}
}
ret = process_kf_arg_ptr_to_rbtree_node(env, reg, regno, meta);
if (ret < 0)
return ret;
break;
case KF_ARG_PTR_TO_MAP:
/* If argument has '__map' suffix expect 'struct bpf_map *' */
ref_id = *reg2btf_ids[CONST_PTR_TO_MAP];
ref_t = btf_type_by_id(btf_vmlinux, ref_id);
ref_tname = btf_name_by_offset(btf, ref_t->name_off);
fallthrough;
case KF_ARG_PTR_TO_BTF_ID:
/* Only base_type is checked, further checks are done here */
if ((base_type(reg->type) != PTR_TO_BTF_ID ||
(bpf_type_has_unsafe_modifiers(reg->type) && !is_rcu_reg(reg))) &&
!reg2btf_ids[base_type(reg->type)]) {
verbose(env, "arg#%d is %s ", i, reg_type_str(env, reg->type));
verbose(env, "expected %s or socket\n",
reg_type_str(env, base_type(reg->type) |
(type_flag(reg->type) & BPF_REG_TRUSTED_MODIFIERS)));
return -EINVAL;
}
ret = process_kf_arg_ptr_to_btf_id(env, reg, ref_t, ref_tname, ref_id, meta, i);
if (ret < 0)
return ret;
break;
case KF_ARG_PTR_TO_MEM:
resolve_ret = btf_resolve_size(btf, ref_t, &type_size);
if (IS_ERR(resolve_ret)) {
verbose(env, "arg#%d reference type('%s %s') size cannot be determined: %ld\n",
i, btf_type_str(ref_t), ref_tname, PTR_ERR(resolve_ret));
return -EINVAL;
}
ret = check_mem_reg(env, reg, regno, type_size);
if (ret < 0)
return ret;
break;
case KF_ARG_PTR_TO_MEM_SIZE:
{
struct bpf_reg_state *buff_reg = ®s[regno];
const struct btf_param *buff_arg = &args[i];
struct bpf_reg_state *size_reg = ®s[regno + 1];
const struct btf_param *size_arg = &args[i + 1];
if (!register_is_null(buff_reg) || !is_kfunc_arg_optional(meta->btf, buff_arg)) {
ret = check_kfunc_mem_size_reg(env, size_reg, regno + 1);
if (ret < 0) {
verbose(env, "arg#%d arg#%d memory, len pair leads to invalid memory access\n", i, i + 1);
return ret;
}
}
if (is_kfunc_arg_const_mem_size(meta->btf, size_arg, size_reg)) {
if (meta->arg_constant.found) {
verbose(env, "verifier internal error: only one constant argument permitted\n");
return -EFAULT;
}
if (!tnum_is_const(size_reg->var_off)) {
verbose(env, "R%d must be a known constant\n", regno + 1);
return -EINVAL;
}
meta->arg_constant.found = true;
meta->arg_constant.value = size_reg->var_off.value;
}
/* Skip next '__sz' or '__szk' argument */
i++;
break;
}
case KF_ARG_PTR_TO_CALLBACK:
if (reg->type != PTR_TO_FUNC) {
verbose(env, "arg%d expected pointer to func\n", i);
return -EINVAL;
}
meta->subprogno = reg->subprogno;
break;
case KF_ARG_PTR_TO_REFCOUNTED_KPTR:
if (!type_is_ptr_alloc_obj(reg->type)) {
verbose(env, "arg#%d is neither owning or non-owning ref\n", i);
return -EINVAL;
}
if (!type_is_non_owning_ref(reg->type))
meta->arg_owning_ref = true;
rec = reg_btf_record(reg);
if (!rec) {
verbose(env, "verifier internal error: Couldn't find btf_record\n");
return -EFAULT;
}
if (rec->refcount_off < 0) {
verbose(env, "arg#%d doesn't point to a type with bpf_refcount field\n", i);
return -EINVAL;
}
meta->arg_btf = reg->btf;
meta->arg_btf_id = reg->btf_id;
break;
case KF_ARG_PTR_TO_CONST_STR:
if (reg->type != PTR_TO_MAP_VALUE) {
verbose(env, "arg#%d doesn't point to a const string\n", i);
return -EINVAL;
}
ret = check_reg_const_str(env, reg, regno);
if (ret)
return ret;
break;
case KF_ARG_PTR_TO_WORKQUEUE:
if (reg->type != PTR_TO_MAP_VALUE) {
verbose(env, "arg#%d doesn't point to a map value\n", i);
return -EINVAL;
}
ret = process_wq_func(env, regno, meta);
if (ret < 0)
return ret;
break;
}
}
if (is_kfunc_release(meta) && !meta->release_regno) {
verbose(env, "release kernel function %s expects refcounted PTR_TO_BTF_ID\n",
func_name);
return -EINVAL;
}
return 0;
}
static int fetch_kfunc_meta(struct bpf_verifier_env *env,
struct bpf_insn *insn,
struct bpf_kfunc_call_arg_meta *meta,
const char **kfunc_name)
{
const struct btf_type *func, *func_proto;
u32 func_id, *kfunc_flags;
const char *func_name;
struct btf *desc_btf;
if (kfunc_name)
*kfunc_name = NULL;
if (!insn->imm)
return -EINVAL;
desc_btf = find_kfunc_desc_btf(env, insn->off);
if (IS_ERR(desc_btf))
return PTR_ERR(desc_btf);
func_id = insn->imm;
func = btf_type_by_id(desc_btf, func_id);
func_name = btf_name_by_offset(desc_btf, func->name_off);
if (kfunc_name)
*kfunc_name = func_name;
func_proto = btf_type_by_id(desc_btf, func->type);
kfunc_flags = btf_kfunc_id_set_contains(desc_btf, func_id, env->prog);
if (!kfunc_flags) {
return -EACCES;
}
memset(meta, 0, sizeof(*meta));
meta->btf = desc_btf;
meta->func_id = func_id;
meta->kfunc_flags = *kfunc_flags;
meta->func_proto = func_proto;
meta->func_name = func_name;
return 0;
}
static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name);
static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
int *insn_idx_p)
{
bool sleepable, rcu_lock, rcu_unlock, preempt_disable, preempt_enable;
u32 i, nargs, ptr_type_id, release_ref_obj_id;
struct bpf_reg_state *regs = cur_regs(env);
const char *func_name, *ptr_type_name;
const struct btf_type *t, *ptr_type;
struct bpf_kfunc_call_arg_meta meta;
struct bpf_insn_aux_data *insn_aux;
int err, insn_idx = *insn_idx_p;
const struct btf_param *args;
const struct btf_type *ret_t;
struct btf *desc_btf;
/* skip for now, but return error when we find this in fixup_kfunc_call */
if (!insn->imm)
return 0;
err = fetch_kfunc_meta(env, insn, &meta, &func_name);
if (err == -EACCES && func_name)
verbose(env, "calling kernel function %s is not allowed\n", func_name);
if (err)
return err;
desc_btf = meta.btf;
insn_aux = &env->insn_aux_data[insn_idx];
insn_aux->is_iter_next = is_iter_next_kfunc(&meta);
if (is_kfunc_destructive(&meta) && !capable(CAP_SYS_BOOT)) {
verbose(env, "destructive kfunc calls require CAP_SYS_BOOT capability\n");
return -EACCES;
}
sleepable = is_kfunc_sleepable(&meta);
if (sleepable && !in_sleepable(env)) {
verbose(env, "program must be sleepable to call sleepable kfunc %s\n", func_name);
return -EACCES;
}
/* Check the arguments */
err = check_kfunc_args(env, &meta, insn_idx);
if (err < 0)
return err;
if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) {
err = push_callback_call(env, insn, insn_idx, meta.subprogno,
set_rbtree_add_callback_state);
if (err) {
verbose(env, "kfunc %s#%d failed callback verification\n",
func_name, meta.func_id);
return err;
}
}
if (meta.func_id == special_kfunc_list[KF_bpf_session_cookie]) {
meta.r0_size = sizeof(u64);
meta.r0_rdonly = false;
}
if (is_bpf_wq_set_callback_impl_kfunc(meta.func_id)) {
err = push_callback_call(env, insn, insn_idx, meta.subprogno,
set_timer_callback_state);
if (err) {
verbose(env, "kfunc %s#%d failed callback verification\n",
func_name, meta.func_id);
return err;
}
}
rcu_lock = is_kfunc_bpf_rcu_read_lock(&meta);
rcu_unlock = is_kfunc_bpf_rcu_read_unlock(&meta);
preempt_disable = is_kfunc_bpf_preempt_disable(&meta);
preempt_enable = is_kfunc_bpf_preempt_enable(&meta);
if (env->cur_state->active_rcu_lock) {
struct bpf_func_state *state;
struct bpf_reg_state *reg;
u32 clear_mask = (1 << STACK_SPILL) | (1 << STACK_ITER);
if (in_rbtree_lock_required_cb(env) && (rcu_lock || rcu_unlock)) {
verbose(env, "Calling bpf_rcu_read_{lock,unlock} in unnecessary rbtree callback\n");
return -EACCES;
}
if (rcu_lock) {
verbose(env, "nested rcu read lock (kernel function %s)\n", func_name);
return -EINVAL;
} else if (rcu_unlock) {
bpf_for_each_reg_in_vstate_mask(env->cur_state, state, reg, clear_mask, ({
if (reg->type & MEM_RCU) {
reg->type &= ~(MEM_RCU | PTR_MAYBE_NULL);
reg->type |= PTR_UNTRUSTED;
}
}));
env->cur_state->active_rcu_lock = false;
} else if (sleepable) {
verbose(env, "kernel func %s is sleepable within rcu_read_lock region\n", func_name);
return -EACCES;
}
} else if (rcu_lock) {
env->cur_state->active_rcu_lock = true;
} else if (rcu_unlock) {
verbose(env, "unmatched rcu read unlock (kernel function %s)\n", func_name);
return -EINVAL;
}
if (env->cur_state->active_preempt_lock) {
if (preempt_disable) {
env->cur_state->active_preempt_lock++;
} else if (preempt_enable) {
env->cur_state->active_preempt_lock--;
} else if (sleepable) {
verbose(env, "kernel func %s is sleepable within non-preemptible region\n", func_name);
return -EACCES;
}
} else if (preempt_disable) {
env->cur_state->active_preempt_lock++;
} else if (preempt_enable) {
verbose(env, "unmatched attempt to enable preemption (kernel function %s)\n", func_name);
return -EINVAL;
}
/* In case of release function, we get register number of refcounted
* PTR_TO_BTF_ID in bpf_kfunc_arg_meta, do the release now.
*/
if (meta.release_regno) {
err = release_reference(env, regs[meta.release_regno].ref_obj_id);
if (err) {
verbose(env, "kfunc %s#%d reference has not been acquired before\n",
func_name, meta.func_id);
return err;
}
}
if (meta.func_id == special_kfunc_list[KF_bpf_list_push_front_impl] ||
meta.func_id == special_kfunc_list[KF_bpf_list_push_back_impl] ||
meta.func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) {
release_ref_obj_id = regs[BPF_REG_2].ref_obj_id;
insn_aux->insert_off = regs[BPF_REG_2].off;
insn_aux->kptr_struct_meta = btf_find_struct_meta(meta.arg_btf, meta.arg_btf_id);
err = ref_convert_owning_non_owning(env, release_ref_obj_id);
if (err) {
verbose(env, "kfunc %s#%d conversion of owning ref to non-owning failed\n",
func_name, meta.func_id);
return err;
}
err = release_reference(env, release_ref_obj_id);
if (err) {
verbose(env, "kfunc %s#%d reference has not been acquired before\n",
func_name, meta.func_id);
return err;
}
}
if (meta.func_id == special_kfunc_list[KF_bpf_throw]) {
if (!bpf_jit_supports_exceptions()) {
verbose(env, "JIT does not support calling kfunc %s#%d\n",
func_name, meta.func_id);
return -ENOTSUPP;
}
env->seen_exception = true;
/* In the case of the default callback, the cookie value passed
* to bpf_throw becomes the return value of the program.
*/
if (!env->exception_callback_subprog) {
err = check_return_code(env, BPF_REG_1, "R1");
if (err < 0)
return err;
}
}
for (i = 0; i < CALLER_SAVED_REGS; i++)
mark_reg_not_init(env, regs, caller_saved[i]);
/* Check return type */
t = btf_type_skip_modifiers(desc_btf, meta.func_proto->type, NULL);
if (is_kfunc_acquire(&meta) && !btf_type_is_struct_ptr(meta.btf, t)) {
/* Only exception is bpf_obj_new_impl */
if (meta.btf != btf_vmlinux ||
(meta.func_id != special_kfunc_list[KF_bpf_obj_new_impl] &&
meta.func_id != special_kfunc_list[KF_bpf_percpu_obj_new_impl] &&
meta.func_id != special_kfunc_list[KF_bpf_refcount_acquire_impl])) {
verbose(env, "acquire kernel function does not return PTR_TO_BTF_ID\n");
return -EINVAL;
}
}
if (btf_type_is_scalar(t)) {
mark_reg_unknown(env, regs, BPF_REG_0);
mark_btf_func_reg_size(env, BPF_REG_0, t->size);
} else if (btf_type_is_ptr(t)) {
ptr_type = btf_type_skip_modifiers(desc_btf, t->type, &ptr_type_id);
if (meta.btf == btf_vmlinux && btf_id_set_contains(&special_kfunc_set, meta.func_id)) {
if (meta.func_id == special_kfunc_list[KF_bpf_obj_new_impl] ||
meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) {
struct btf_struct_meta *struct_meta;
struct btf *ret_btf;
u32 ret_btf_id;
if (meta.func_id == special_kfunc_list[KF_bpf_obj_new_impl] && !bpf_global_ma_set)
return -ENOMEM;
if (((u64)(u32)meta.arg_constant.value) != meta.arg_constant.value) {
verbose(env, "local type ID argument must be in range [0, U32_MAX]\n");
return -EINVAL;
}
ret_btf = env->prog->aux->btf;
ret_btf_id = meta.arg_constant.value;
/* This may be NULL due to user not supplying a BTF */
if (!ret_btf) {
verbose(env, "bpf_obj_new/bpf_percpu_obj_new requires prog BTF\n");
return -EINVAL;
}
ret_t = btf_type_by_id(ret_btf, ret_btf_id);
if (!ret_t || !__btf_type_is_struct(ret_t)) {
verbose(env, "bpf_obj_new/bpf_percpu_obj_new type ID argument must be of a struct\n");
return -EINVAL;
}
if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) {
if (ret_t->size > BPF_GLOBAL_PERCPU_MA_MAX_SIZE) {
verbose(env, "bpf_percpu_obj_new type size (%d) is greater than %d\n",
ret_t->size, BPF_GLOBAL_PERCPU_MA_MAX_SIZE);
return -EINVAL;
}
if (!bpf_global_percpu_ma_set) {
mutex_lock(&bpf_percpu_ma_lock);
if (!bpf_global_percpu_ma_set) {
/* Charge memory allocated with bpf_global_percpu_ma to
* root memcg. The obj_cgroup for root memcg is NULL.
*/
err = bpf_mem_alloc_percpu_init(&bpf_global_percpu_ma, NULL);
if (!err)
bpf_global_percpu_ma_set = true;
}
mutex_unlock(&bpf_percpu_ma_lock);
if (err)
return err;
}
mutex_lock(&bpf_percpu_ma_lock);
err = bpf_mem_alloc_percpu_unit_init(&bpf_global_percpu_ma, ret_t->size);
mutex_unlock(&bpf_percpu_ma_lock);
if (err)
return err;
}
struct_meta = btf_find_struct_meta(ret_btf, ret_btf_id);
if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) {
if (!__btf_type_is_scalar_struct(env, ret_btf, ret_t, 0)) {
verbose(env, "bpf_percpu_obj_new type ID argument must be of a struct of scalars\n");
return -EINVAL;
}
if (struct_meta) {
verbose(env, "bpf_percpu_obj_new type ID argument must not contain special fields\n");
return -EINVAL;
}
}
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC;
regs[BPF_REG_0].btf = ret_btf;
regs[BPF_REG_0].btf_id = ret_btf_id;
if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl])
regs[BPF_REG_0].type |= MEM_PERCPU;
insn_aux->obj_new_size = ret_t->size;
insn_aux->kptr_struct_meta = struct_meta;
} else if (meta.func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl]) {
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC;
regs[BPF_REG_0].btf = meta.arg_btf;
regs[BPF_REG_0].btf_id = meta.arg_btf_id;
insn_aux->kptr_struct_meta =
btf_find_struct_meta(meta.arg_btf,
meta.arg_btf_id);
} else if (meta.func_id == special_kfunc_list[KF_bpf_list_pop_front] ||
meta.func_id == special_kfunc_list[KF_bpf_list_pop_back]) {
struct btf_field *field = meta.arg_list_head.field;
mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root);
} else if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_remove] ||
meta.func_id == special_kfunc_list[KF_bpf_rbtree_first]) {
struct btf_field *field = meta.arg_rbtree_root.field;
mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root);
} else if (meta.func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) {
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].type = PTR_TO_BTF_ID | PTR_TRUSTED;
regs[BPF_REG_0].btf = desc_btf;
regs[BPF_REG_0].btf_id = meta.ret_btf_id;
} else if (meta.func_id == special_kfunc_list[KF_bpf_rdonly_cast]) {
ret_t = btf_type_by_id(desc_btf, meta.arg_constant.value);
if (!ret_t || !btf_type_is_struct(ret_t)) {
verbose(env,
"kfunc bpf_rdonly_cast type ID argument must be of a struct\n");
return -EINVAL;
}
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].type = PTR_TO_BTF_ID | PTR_UNTRUSTED;
regs[BPF_REG_0].btf = desc_btf;
regs[BPF_REG_0].btf_id = meta.arg_constant.value;
} else if (meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice] ||
meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice_rdwr]) {
enum bpf_type_flag type_flag = get_dynptr_type_flag(meta.initialized_dynptr.type);
mark_reg_known_zero(env, regs, BPF_REG_0);
if (!meta.arg_constant.found) {
verbose(env, "verifier internal error: bpf_dynptr_slice(_rdwr) no constant size\n");
return -EFAULT;
}
regs[BPF_REG_0].mem_size = meta.arg_constant.value;
/* PTR_MAYBE_NULL will be added when is_kfunc_ret_null is checked */
regs[BPF_REG_0].type = PTR_TO_MEM | type_flag;
if (meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice]) {
regs[BPF_REG_0].type |= MEM_RDONLY;
} else {
/* this will set env->seen_direct_write to true */
if (!may_access_direct_pkt_data(env, NULL, BPF_WRITE)) {
verbose(env, "the prog does not allow writes to packet data\n");
return -EINVAL;
}
}
if (!meta.initialized_dynptr.id) {
verbose(env, "verifier internal error: no dynptr id\n");
return -EFAULT;
}
regs[BPF_REG_0].dynptr_id = meta.initialized_dynptr.id;
/* we don't need to set BPF_REG_0's ref obj id
* because packet slices are not refcounted (see
* dynptr_type_refcounted)
*/
} else {
verbose(env, "kernel function %s unhandled dynamic return type\n",
meta.func_name);
return -EFAULT;
}
} else if (btf_type_is_void(ptr_type)) {
/* kfunc returning 'void *' is equivalent to returning scalar */
mark_reg_unknown(env, regs, BPF_REG_0);
} else if (!__btf_type_is_struct(ptr_type)) {
if (!meta.r0_size) {
__u32 sz;
if (!IS_ERR(btf_resolve_size(desc_btf, ptr_type, &sz))) {
meta.r0_size = sz;
meta.r0_rdonly = true;
}
}
if (!meta.r0_size) {
ptr_type_name = btf_name_by_offset(desc_btf,
ptr_type->name_off);
verbose(env,
"kernel function %s returns pointer type %s %s is not supported\n",
func_name,
btf_type_str(ptr_type),
ptr_type_name);
return -EINVAL;
}
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].type = PTR_TO_MEM;
regs[BPF_REG_0].mem_size = meta.r0_size;
if (meta.r0_rdonly)
regs[BPF_REG_0].type |= MEM_RDONLY;
/* Ensures we don't access the memory after a release_reference() */
if (meta.ref_obj_id)
regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;
} else {
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].btf = desc_btf;
regs[BPF_REG_0].type = PTR_TO_BTF_ID;
regs[BPF_REG_0].btf_id = ptr_type_id;
if (is_iter_next_kfunc(&meta)) {
struct bpf_reg_state *cur_iter;
cur_iter = get_iter_from_state(env->cur_state, &meta);
if (cur_iter->type & MEM_RCU) /* KF_RCU_PROTECTED */
regs[BPF_REG_0].type |= MEM_RCU;
else
regs[BPF_REG_0].type |= PTR_TRUSTED;
}
}
if (is_kfunc_ret_null(&meta)) {
regs[BPF_REG_0].type |= PTR_MAYBE_NULL;
/* For mark_ptr_or_null_reg, see 93c230e3f5bd6 */
regs[BPF_REG_0].id = ++env->id_gen;
}
mark_btf_func_reg_size(env, BPF_REG_0, sizeof(void *));
if (is_kfunc_acquire(&meta)) {
int id = acquire_reference_state(env, insn_idx);
if (id < 0)
return id;
if (is_kfunc_ret_null(&meta))
regs[BPF_REG_0].id = id;
regs[BPF_REG_0].ref_obj_id = id;
} else if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_first]) {
ref_set_non_owning(env, ®s[BPF_REG_0]);
}
if (reg_may_point_to_spin_lock(®s[BPF_REG_0]) && !regs[BPF_REG_0].id)
regs[BPF_REG_0].id = ++env->id_gen;
} else if (btf_type_is_void(t)) {
if (meta.btf == btf_vmlinux && btf_id_set_contains(&special_kfunc_set, meta.func_id)) {
if (meta.func_id == special_kfunc_list[KF_bpf_obj_drop_impl] ||
meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_drop_impl]) {
insn_aux->kptr_struct_meta =
btf_find_struct_meta(meta.arg_btf,
meta.arg_btf_id);
}
}
}
nargs = btf_type_vlen(meta.func_proto);
args = (const struct btf_param *)(meta.func_proto + 1);
for (i = 0; i < nargs; i++) {
u32 regno = i + 1;
t = btf_type_skip_modifiers(desc_btf, args[i].type, NULL);
if (btf_type_is_ptr(t))
mark_btf_func_reg_size(env, regno, sizeof(void *));
else
/* scalar. ensured by btf_check_kfunc_arg_match() */
mark_btf_func_reg_size(env, regno, t->size);
}
if (is_iter_next_kfunc(&meta)) {
err = process_iter_next_call(env, insn_idx, &meta);
if (err)
return err;
}
return 0;
}
static bool check_reg_sane_offset(struct bpf_verifier_env *env,
const struct bpf_reg_state *reg,
enum bpf_reg_type type)
{
bool known = tnum_is_const(reg->var_off);
s64 val = reg->var_off.value;
s64 smin = reg->smin_value;
if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) {
verbose(env, "math between %s pointer and %lld is not allowed\n",
reg_type_str(env, type), val);
return false;
}
if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) {
verbose(env, "%s pointer offset %d is not allowed\n",
reg_type_str(env, type), reg->off);
return false;
}
if (smin == S64_MIN) {
verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n",
reg_type_str(env, type));
return false;
}
if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) {
verbose(env, "value %lld makes %s pointer be out of bounds\n",
smin, reg_type_str(env, type));
return false;
}
return true;
}
enum {
REASON_BOUNDS = -1,
REASON_TYPE = -2,
REASON_PATHS = -3,
REASON_LIMIT = -4,
REASON_STACK = -5,
};
static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg,
u32 *alu_limit, bool mask_to_left)
{
u32 max = 0, ptr_limit = 0;
switch (ptr_reg->type) {
case PTR_TO_STACK:
/* Offset 0 is out-of-bounds, but acceptable start for the
* left direction, see BPF_REG_FP. Also, unknown scalar
* offset where we would need to deal with min/max bounds is
* currently prohibited for unprivileged.
*/
max = MAX_BPF_STACK + mask_to_left;
ptr_limit = -(ptr_reg->var_off.value + ptr_reg->off);
break;
case PTR_TO_MAP_VALUE:
max = ptr_reg->map_ptr->value_size;
ptr_limit = (mask_to_left ?
ptr_reg->smin_value :
ptr_reg->umax_value) + ptr_reg->off;
break;
default:
return REASON_TYPE;
}
if (ptr_limit >= max)
return REASON_LIMIT;
*alu_limit = ptr_limit;
return 0;
}
static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env,
const struct bpf_insn *insn)
{
return env->bypass_spec_v1 || BPF_SRC(insn->code) == BPF_K;
}
static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux,
u32 alu_state, u32 alu_limit)
{
/* If we arrived here from different branches with different
* state or limits to sanitize, then this won't work.
*/
if (aux->alu_state &&
(aux->alu_state != alu_state ||
aux->alu_limit != alu_limit))
return REASON_PATHS;
/* Corresponding fixup done in do_misc_fixups(). */
aux->alu_state = alu_state;
aux->alu_limit = alu_limit;
return 0;
}
static int sanitize_val_alu(struct bpf_verifier_env *env,
struct bpf_insn *insn)
{
struct bpf_insn_aux_data *aux = cur_aux(env);
if (can_skip_alu_sanitation(env, insn))
return 0;
return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0);
}
static bool sanitize_needed(u8 opcode)
{
return opcode == BPF_ADD || opcode == BPF_SUB;
}
struct bpf_sanitize_info {
struct bpf_insn_aux_data aux;
bool mask_to_left;
};
static struct bpf_verifier_state *
sanitize_speculative_path(struct bpf_verifier_env *env,
const struct bpf_insn *insn,
u32 next_idx, u32 curr_idx)
{
struct bpf_verifier_state *branch;
struct bpf_reg_state *regs;
branch = push_stack(env, next_idx, curr_idx, true);
if (branch && insn) {
regs = branch->frame[branch->curframe]->regs;
if (BPF_SRC(insn->code) == BPF_K) {
mark_reg_unknown(env, regs, insn->dst_reg);
} else if (BPF_SRC(insn->code) == BPF_X) {
mark_reg_unknown(env, regs, insn->dst_reg);
mark_reg_unknown(env, regs, insn->src_reg);
}
}
return branch;
}
static int sanitize_ptr_alu(struct bpf_verifier_env *env,
struct bpf_insn *insn,
const struct bpf_reg_state *ptr_reg,
const struct bpf_reg_state *off_reg,
struct bpf_reg_state *dst_reg,
struct bpf_sanitize_info *info,
const bool commit_window)
{
struct bpf_insn_aux_data *aux = commit_window ? cur_aux(env) : &info->aux;
struct bpf_verifier_state *vstate = env->cur_state;
bool off_is_imm = tnum_is_const(off_reg->var_off);
bool off_is_neg = off_reg->smin_value < 0;
bool ptr_is_dst_reg = ptr_reg == dst_reg;
u8 opcode = BPF_OP(insn->code);
u32 alu_state, alu_limit;
struct bpf_reg_state tmp;
bool ret;
int err;
if (can_skip_alu_sanitation(env, insn))
return 0;
/* We already marked aux for masking from non-speculative
* paths, thus we got here in the first place. We only care
* to explore bad access from here.
*/
if (vstate->speculative)
goto do_sim;
if (!commit_window) {
if (!tnum_is_const(off_reg->var_off) &&
(off_reg->smin_value < 0) != (off_reg->smax_value < 0))
return REASON_BOUNDS;
info->mask_to_left = (opcode == BPF_ADD && off_is_neg) ||
(opcode == BPF_SUB && !off_is_neg);
}
err = retrieve_ptr_limit(ptr_reg, &alu_limit, info->mask_to_left);
if (err < 0)
return err;
if (commit_window) {
/* In commit phase we narrow the masking window based on
* the observed pointer move after the simulated operation.
*/
alu_state = info->aux.alu_state;
alu_limit = abs(info->aux.alu_limit - alu_limit);
} else {
alu_state = off_is_neg ? BPF_ALU_NEG_VALUE : 0;
alu_state |= off_is_imm ? BPF_ALU_IMMEDIATE : 0;
alu_state |= ptr_is_dst_reg ?
BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST;
/* Limit pruning on unknown scalars to enable deep search for
* potential masking differences from other program paths.
*/
if (!off_is_imm)
env->explore_alu_limits = true;
}
err = update_alu_sanitation_state(aux, alu_state, alu_limit);
if (err < 0)
return err;
do_sim:
/* If we're in commit phase, we're done here given we already
* pushed the truncated dst_reg into the speculative verification
* stack.
*
* Also, when register is a known constant, we rewrite register-based
* operation to immediate-based, and thus do not need masking (and as
* a consequence, do not need to simulate the zero-truncation either).
*/
if (commit_window || off_is_imm)
return 0;
/* Simulate and find potential out-of-bounds access under
* speculative execution from truncation as a result of
* masking when off was not within expected range. If off
* sits in dst, then we temporarily need to move ptr there
* to simulate dst (== 0) +/-= ptr. Needed, for example,
* for cases where we use K-based arithmetic in one direction
* and truncated reg-based in the other in order to explore
* bad access.
*/
if (!ptr_is_dst_reg) {
tmp = *dst_reg;
copy_register_state(dst_reg, ptr_reg);
}
ret = sanitize_speculative_path(env, NULL, env->insn_idx + 1,
env->insn_idx);
if (!ptr_is_dst_reg && ret)
*dst_reg = tmp;
return !ret ? REASON_STACK : 0;
}
static void sanitize_mark_insn_seen(struct bpf_verifier_env *env)
{
struct bpf_verifier_state *vstate = env->cur_state;
/* If we simulate paths under speculation, we don't update the
* insn as 'seen' such that when we verify unreachable paths in
* the non-speculative domain, sanitize_dead_code() can still
* rewrite/sanitize them.
*/
if (!vstate->speculative)
env->insn_aux_data[env->insn_idx].seen = env->pass_cnt;
}
static int sanitize_err(struct bpf_verifier_env *env,
const struct bpf_insn *insn, int reason,
const struct bpf_reg_state *off_reg,
const struct bpf_reg_state *dst_reg)
{
static const char *err = "pointer arithmetic with it prohibited for !root";
const char *op = BPF_OP(insn->code) == BPF_ADD ? "add" : "sub";
u32 dst = insn->dst_reg, src = insn->src_reg;
switch (reason) {
case REASON_BOUNDS:
verbose(env, "R%d has unknown scalar with mixed signed bounds, %s\n",
off_reg == dst_reg ? dst : src, err);
break;
case REASON_TYPE:
verbose(env, "R%d has pointer with unsupported alu operation, %s\n",
off_reg == dst_reg ? src : dst, err);
break;
case REASON_PATHS:
verbose(env, "R%d tried to %s from different maps, paths or scalars, %s\n",
dst, op, err);
break;
case REASON_LIMIT:
verbose(env, "R%d tried to %s beyond pointer bounds, %s\n",
dst, op, err);
break;
case REASON_STACK:
verbose(env, "R%d could not be pushed for speculative verification, %s\n",
dst, err);
break;
default:
verbose(env, "verifier internal error: unknown reason (%d)\n",
reason);
break;
}
return -EACCES;
}
/* check that stack access falls within stack limits and that 'reg' doesn't
* have a variable offset.
*
* Variable offset is prohibited for unprivileged mode for simplicity since it
* requires corresponding support in Spectre masking for stack ALU. See also
* retrieve_ptr_limit().
*
*
* 'off' includes 'reg->off'.
*/
static int check_stack_access_for_ptr_arithmetic(
struct bpf_verifier_env *env,
int regno,
const struct bpf_reg_state *reg,
int off)
{
if (!tnum_is_const(reg->var_off)) {
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
verbose(env, "R%d variable stack access prohibited for !root, var_off=%s off=%d\n",
regno, tn_buf, off);
return -EACCES;
}
if (off >= 0 || off < -MAX_BPF_STACK) {
verbose(env, "R%d stack pointer arithmetic goes out of range, "
"prohibited for !root; off=%d\n", regno, off);
return -EACCES;
}
return 0;
}
static int sanitize_check_bounds(struct bpf_verifier_env *env,
const struct bpf_insn *insn,
const struct bpf_reg_state *dst_reg)
{
u32 dst = insn->dst_reg;
/* For unprivileged we require that resulting offset must be in bounds
* in order to be able to sanitize access later on.
*/
if (env->bypass_spec_v1)
return 0;
switch (dst_reg->type) {
case PTR_TO_STACK:
if (check_stack_access_for_ptr_arithmetic(env, dst, dst_reg,
dst_reg->off + dst_reg->var_off.value))
return -EACCES;
break;
case PTR_TO_MAP_VALUE:
if (check_map_access(env, dst, dst_reg->off, 1, false, ACCESS_HELPER)) {
verbose(env, "R%d pointer arithmetic of map value goes out of range, "
"prohibited for !root\n", dst);
return -EACCES;
}
break;
default:
break;
}
return 0;
}
/* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
* Caller should also handle BPF_MOV case separately.
* If we return -EACCES, caller may want to try again treating pointer as a
* scalar. So we only emit a diagnostic if !env->allow_ptr_leaks.
*/
static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
struct bpf_insn *insn,
const struct bpf_reg_state *ptr_reg,
const struct bpf_reg_state *off_reg)
{
struct bpf_verifier_state *vstate = env->cur_state;
struct bpf_func_state *state = vstate->frame[vstate->curframe];
struct bpf_reg_state *regs = state->regs, *dst_reg;
bool known = tnum_is_const(off_reg->var_off);
s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value,
smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value;
u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value,
umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value;
struct bpf_sanitize_info info = {};
u8 opcode = BPF_OP(insn->code);
u32 dst = insn->dst_reg;
int ret;
dst_reg = ®s[dst];
if ((known && (smin_val != smax_val || umin_val != umax_val)) ||
smin_val > smax_val || umin_val > umax_val) {
/* Taint dst register if offset had invalid bounds derived from
* e.g. dead branches.
*/
__mark_reg_unknown(env, dst_reg);
return 0;
}
if (BPF_CLASS(insn->code) != BPF_ALU64) {
/* 32-bit ALU ops on pointers produce (meaningless) scalars */
if (opcode == BPF_SUB && env->allow_ptr_leaks) {
__mark_reg_unknown(env, dst_reg);
return 0;
}
verbose(env,
"R%d 32-bit pointer arithmetic prohibited\n",
dst);
return -EACCES;
}
if (ptr_reg->type & PTR_MAYBE_NULL) {
verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n",
dst, reg_type_str(env, ptr_reg->type));
return -EACCES;
}
switch (base_type(ptr_reg->type)) {
case PTR_TO_CTX:
case PTR_TO_MAP_VALUE:
case PTR_TO_MAP_KEY:
case PTR_TO_STACK:
case PTR_TO_PACKET_META:
case PTR_TO_PACKET:
case PTR_TO_TP_BUFFER:
case PTR_TO_BTF_ID:
case PTR_TO_MEM:
case PTR_TO_BUF:
case PTR_TO_FUNC:
case CONST_PTR_TO_DYNPTR:
break;
case PTR_TO_FLOW_KEYS:
if (known)
break;
fallthrough;
case CONST_PTR_TO_MAP:
/* smin_val represents the known value */
if (known && smin_val == 0 && opcode == BPF_ADD)
break;
fallthrough;
default:
verbose(env, "R%d pointer arithmetic on %s prohibited\n",
dst, reg_type_str(env, ptr_reg->type));
return -EACCES;
}
/* In case of 'scalar += pointer', dst_reg inherits pointer type and id.
* The id may be overwritten later if we create a new variable offset.
*/
dst_reg->type = ptr_reg->type;
dst_reg->id = ptr_reg->id;
if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) ||
!check_reg_sane_offset(env, ptr_reg, ptr_reg->type))
return -EINVAL;
/* pointer types do not carry 32-bit bounds at the moment. */
__mark_reg32_unbounded(dst_reg);
if (sanitize_needed(opcode)) {
ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg,
&info, false);
if (ret < 0)
return sanitize_err(env, insn, ret, off_reg, dst_reg);
}
switch (opcode) {
case BPF_ADD:
/* We can take a fixed offset as long as it doesn't overflow
* the s32 'off' field
*/
if (known && (ptr_reg->off + smin_val ==
(s64)(s32)(ptr_reg->off + smin_val))) {
/* pointer += K. Accumulate it into fixed offset */
dst_reg->smin_value = smin_ptr;
dst_reg->smax_value = smax_ptr;
dst_reg->umin_value = umin_ptr;
dst_reg->umax_value = umax_ptr;
dst_reg->var_off = ptr_reg->var_off;
dst_reg->off = ptr_reg->off + smin_val;
dst_reg->raw = ptr_reg->raw;
break;
}
/* A new variable offset is created. Note that off_reg->off
* == 0, since it's a scalar.
* dst_reg gets the pointer type and since some positive
* integer value was added to the pointer, give it a new 'id'
* if it's a PTR_TO_PACKET.
* this creates a new 'base' pointer, off_reg (variable) gets
* added into the variable offset, and we copy the fixed offset
* from ptr_reg.
*/
if (check_add_overflow(smin_ptr, smin_val, &dst_reg->smin_value) ||
check_add_overflow(smax_ptr, smax_val, &dst_reg->smax_value)) {
dst_reg->smin_value = S64_MIN;
dst_reg->smax_value = S64_MAX;
}
if (check_add_overflow(umin_ptr, umin_val, &dst_reg->umin_value) ||
check_add_overflow(umax_ptr, umax_val, &dst_reg->umax_value)) {
dst_reg->umin_value = 0;
dst_reg->umax_value = U64_MAX;
}
dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off);
dst_reg->off = ptr_reg->off;
dst_reg->raw = ptr_reg->raw;
if (reg_is_pkt_pointer(ptr_reg)) {
dst_reg->id = ++env->id_gen;
/* something was added to pkt_ptr, set range to zero */
memset(&dst_reg->raw, 0, sizeof(dst_reg->raw));
}
break;
case BPF_SUB:
if (dst_reg == off_reg) {
/* scalar -= pointer. Creates an unknown scalar */
verbose(env, "R%d tried to subtract pointer from scalar\n",
dst);
return -EACCES;
}
/* We don't allow subtraction from FP, because (according to
* test_verifier.c test "invalid fp arithmetic", JITs might not
* be able to deal with it.
*/
if (ptr_reg->type == PTR_TO_STACK) {
verbose(env, "R%d subtraction from stack pointer prohibited\n",
dst);
return -EACCES;
}
if (known && (ptr_reg->off - smin_val ==
(s64)(s32)(ptr_reg->off - smin_val))) {
/* pointer -= K. Subtract it from fixed offset */
dst_reg->smin_value = smin_ptr;
dst_reg->smax_value = smax_ptr;
dst_reg->umin_value = umin_ptr;
dst_reg->umax_value = umax_ptr;
dst_reg->var_off = ptr_reg->var_off;
dst_reg->id = ptr_reg->id;
dst_reg->off = ptr_reg->off - smin_val;
dst_reg->raw = ptr_reg->raw;
break;
}
/* A new variable offset is created. If the subtrahend is known
* nonnegative, then any reg->range we had before is still good.
*/
if (check_sub_overflow(smin_ptr, smax_val, &dst_reg->smin_value) ||
check_sub_overflow(smax_ptr, smin_val, &dst_reg->smax_value)) {
/* Overflow possible, we know nothing */
dst_reg->smin_value = S64_MIN;
dst_reg->smax_value = S64_MAX;
}
if (umin_ptr < umax_val) {
/* Overflow possible, we know nothing */
dst_reg->umin_value = 0;
dst_reg->umax_value = U64_MAX;
} else {
/* Cannot overflow (as long as bounds are consistent) */
dst_reg->umin_value = umin_ptr - umax_val;
dst_reg->umax_value = umax_ptr - umin_val;
}
dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off);
dst_reg->off = ptr_reg->off;
dst_reg->raw = ptr_reg->raw;
if (reg_is_pkt_pointer(ptr_reg)) {
dst_reg->id = ++env->id_gen;
/* something was added to pkt_ptr, set range to zero */
if (smin_val < 0)
memset(&dst_reg->raw, 0, sizeof(dst_reg->raw));
}
break;
case BPF_AND:
case BPF_OR:
case BPF_XOR:
/* bitwise ops on pointers are troublesome, prohibit. */
verbose(env, "R%d bitwise operator %s on pointer prohibited\n",
dst, bpf_alu_string[opcode >> 4]);
return -EACCES;
default:
/* other operators (e.g. MUL,LSH) produce non-pointer results */
verbose(env, "R%d pointer arithmetic with %s operator prohibited\n",
dst, bpf_alu_string[opcode >> 4]);
return -EACCES;
}
if (!check_reg_sane_offset(env, dst_reg, ptr_reg->type))
return -EINVAL;
reg_bounds_sync(dst_reg);
if (sanitize_check_bounds(env, insn, dst_reg) < 0)
return -EACCES;
if (sanitize_needed(opcode)) {
ret = sanitize_ptr_alu(env, insn, dst_reg, off_reg, dst_reg,
&info, true);
if (ret < 0)
return sanitize_err(env, insn, ret, off_reg, dst_reg);
}
return 0;
}
static void scalar32_min_max_add(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
s32 *dst_smin = &dst_reg->s32_min_value;
s32 *dst_smax = &dst_reg->s32_max_value;
u32 *dst_umin = &dst_reg->u32_min_value;
u32 *dst_umax = &dst_reg->u32_max_value;
if (check_add_overflow(*dst_smin, src_reg->s32_min_value, dst_smin) ||
check_add_overflow(*dst_smax, src_reg->s32_max_value, dst_smax)) {
*dst_smin = S32_MIN;
*dst_smax = S32_MAX;
}
if (check_add_overflow(*dst_umin, src_reg->u32_min_value, dst_umin) ||
check_add_overflow(*dst_umax, src_reg->u32_max_value, dst_umax)) {
*dst_umin = 0;
*dst_umax = U32_MAX;
}
}
static void scalar_min_max_add(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
s64 *dst_smin = &dst_reg->smin_value;
s64 *dst_smax = &dst_reg->smax_value;
u64 *dst_umin = &dst_reg->umin_value;
u64 *dst_umax = &dst_reg->umax_value;
if (check_add_overflow(*dst_smin, src_reg->smin_value, dst_smin) ||
check_add_overflow(*dst_smax, src_reg->smax_value, dst_smax)) {
*dst_smin = S64_MIN;
*dst_smax = S64_MAX;
}
if (check_add_overflow(*dst_umin, src_reg->umin_value, dst_umin) ||
check_add_overflow(*dst_umax, src_reg->umax_value, dst_umax)) {
*dst_umin = 0;
*dst_umax = U64_MAX;
}
}
static void scalar32_min_max_sub(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
s32 *dst_smin = &dst_reg->s32_min_value;
s32 *dst_smax = &dst_reg->s32_max_value;
u32 umin_val = src_reg->u32_min_value;
u32 umax_val = src_reg->u32_max_value;
if (check_sub_overflow(*dst_smin, src_reg->s32_max_value, dst_smin) ||
check_sub_overflow(*dst_smax, src_reg->s32_min_value, dst_smax)) {
/* Overflow possible, we know nothing */
*dst_smin = S32_MIN;
*dst_smax = S32_MAX;
}
if (dst_reg->u32_min_value < umax_val) {
/* Overflow possible, we know nothing */
dst_reg->u32_min_value = 0;
dst_reg->u32_max_value = U32_MAX;
} else {
/* Cannot overflow (as long as bounds are consistent) */
dst_reg->u32_min_value -= umax_val;
dst_reg->u32_max_value -= umin_val;
}
}
static void scalar_min_max_sub(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
s64 *dst_smin = &dst_reg->smin_value;
s64 *dst_smax = &dst_reg->smax_value;
u64 umin_val = src_reg->umin_value;
u64 umax_val = src_reg->umax_value;
if (check_sub_overflow(*dst_smin, src_reg->smax_value, dst_smin) ||
check_sub_overflow(*dst_smax, src_reg->smin_value, dst_smax)) {
/* Overflow possible, we know nothing */
*dst_smin = S64_MIN;
*dst_smax = S64_MAX;
}
if (dst_reg->umin_value < umax_val) {
/* Overflow possible, we know nothing */
dst_reg->umin_value = 0;
dst_reg->umax_value = U64_MAX;
} else {
/* Cannot overflow (as long as bounds are consistent) */
dst_reg->umin_value -= umax_val;
dst_reg->umax_value -= umin_val;
}
}
static void scalar32_min_max_mul(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
s32 smin_val = src_reg->s32_min_value;
u32 umin_val = src_reg->u32_min_value;
u32 umax_val = src_reg->u32_max_value;
if (smin_val < 0 || dst_reg->s32_min_value < 0) {
/* Ain't nobody got time to multiply that sign */
__mark_reg32_unbounded(dst_reg);
return;
}
/* Both values are positive, so we can work with unsigned and
* copy the result to signed (unless it exceeds S32_MAX).
*/
if (umax_val > U16_MAX || dst_reg->u32_max_value > U16_MAX) {
/* Potential overflow, we know nothing */
__mark_reg32_unbounded(dst_reg);
return;
}
dst_reg->u32_min_value *= umin_val;
dst_reg->u32_max_value *= umax_val;
if (dst_reg->u32_max_value > S32_MAX) {
/* Overflow possible, we know nothing */
dst_reg->s32_min_value = S32_MIN;
dst_reg->s32_max_value = S32_MAX;
} else {
dst_reg->s32_min_value = dst_reg->u32_min_value;
dst_reg->s32_max_value = dst_reg->u32_max_value;
}
}
static void scalar_min_max_mul(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
s64 smin_val = src_reg->smin_value;
u64 umin_val = src_reg->umin_value;
u64 umax_val = src_reg->umax_value;
if (smin_val < 0 || dst_reg->smin_value < 0) {
/* Ain't nobody got time to multiply that sign */
__mark_reg64_unbounded(dst_reg);
return;
}
/* Both values are positive, so we can work with unsigned and
* copy the result to signed (unless it exceeds S64_MAX).
*/
if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) {
/* Potential overflow, we know nothing */
__mark_reg64_unbounded(dst_reg);
return;
}
dst_reg->umin_value *= umin_val;
dst_reg->umax_value *= umax_val;
if (dst_reg->umax_value > S64_MAX) {
/* Overflow possible, we know nothing */
dst_reg->smin_value = S64_MIN;
dst_reg->smax_value = S64_MAX;
} else {
dst_reg->smin_value = dst_reg->umin_value;
dst_reg->smax_value = dst_reg->umax_value;
}
}
static void scalar32_min_max_and(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
bool src_known = tnum_subreg_is_const(src_reg->var_off);
bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
struct tnum var32_off = tnum_subreg(dst_reg->var_off);
u32 umax_val = src_reg->u32_max_value;
if (src_known && dst_known) {
__mark_reg32_known(dst_reg, var32_off.value);
return;
}
/* We get our minimum from the var_off, since that's inherently
* bitwise. Our maximum is the minimum of the operands' maxima.
*/
dst_reg->u32_min_value = var32_off.value;
dst_reg->u32_max_value = min(dst_reg->u32_max_value, umax_val);
/* Safe to set s32 bounds by casting u32 result into s32 when u32
* doesn't cross sign boundary. Otherwise set s32 bounds to unbounded.
*/
if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) {
dst_reg->s32_min_value = dst_reg->u32_min_value;
dst_reg->s32_max_value = dst_reg->u32_max_value;
} else {
dst_reg->s32_min_value = S32_MIN;
dst_reg->s32_max_value = S32_MAX;
}
}
static void scalar_min_max_and(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
bool src_known = tnum_is_const(src_reg->var_off);
bool dst_known = tnum_is_const(dst_reg->var_off);
u64 umax_val = src_reg->umax_value;
if (src_known && dst_known) {
__mark_reg_known(dst_reg, dst_reg->var_off.value);
return;
}
/* We get our minimum from the var_off, since that's inherently
* bitwise. Our maximum is the minimum of the operands' maxima.
*/
dst_reg->umin_value = dst_reg->var_off.value;
dst_reg->umax_value = min(dst_reg->umax_value, umax_val);
/* Safe to set s64 bounds by casting u64 result into s64 when u64
* doesn't cross sign boundary. Otherwise set s64 bounds to unbounded.
*/
if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) {
dst_reg->smin_value = dst_reg->umin_value;
dst_reg->smax_value = dst_reg->umax_value;
} else {
dst_reg->smin_value = S64_MIN;
dst_reg->smax_value = S64_MAX;
}
/* We may learn something more from the var_off */
__update_reg_bounds(dst_reg);
}
static void scalar32_min_max_or(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
bool src_known = tnum_subreg_is_const(src_reg->var_off);
bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
struct tnum var32_off = tnum_subreg(dst_reg->var_off);
u32 umin_val = src_reg->u32_min_value;
if (src_known && dst_known) {
__mark_reg32_known(dst_reg, var32_off.value);
return;
}
/* We get our maximum from the var_off, and our minimum is the
* maximum of the operands' minima
*/
dst_reg->u32_min_value = max(dst_reg->u32_min_value, umin_val);
dst_reg->u32_max_value = var32_off.value | var32_off.mask;
/* Safe to set s32 bounds by casting u32 result into s32 when u32
* doesn't cross sign boundary. Otherwise set s32 bounds to unbounded.
*/
if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) {
dst_reg->s32_min_value = dst_reg->u32_min_value;
dst_reg->s32_max_value = dst_reg->u32_max_value;
} else {
dst_reg->s32_min_value = S32_MIN;
dst_reg->s32_max_value = S32_MAX;
}
}
static void scalar_min_max_or(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
bool src_known = tnum_is_const(src_reg->var_off);
bool dst_known = tnum_is_const(dst_reg->var_off);
u64 umin_val = src_reg->umin_value;
if (src_known && dst_known) {
__mark_reg_known(dst_reg, dst_reg->var_off.value);
return;
}
/* We get our maximum from the var_off, and our minimum is the
* maximum of the operands' minima
*/
dst_reg->umin_value = max(dst_reg->umin_value, umin_val);
dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;
/* Safe to set s64 bounds by casting u64 result into s64 when u64
* doesn't cross sign boundary. Otherwise set s64 bounds to unbounded.
*/
if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) {
dst_reg->smin_value = dst_reg->umin_value;
dst_reg->smax_value = dst_reg->umax_value;
} else {
dst_reg->smin_value = S64_MIN;
dst_reg->smax_value = S64_MAX;
}
/* We may learn something more from the var_off */
__update_reg_bounds(dst_reg);
}
static void scalar32_min_max_xor(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
bool src_known = tnum_subreg_is_const(src_reg->var_off);
bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
struct tnum var32_off = tnum_subreg(dst_reg->var_off);
if (src_known && dst_known) {
__mark_reg32_known(dst_reg, var32_off.value);
return;
}
/* We get both minimum and maximum from the var32_off. */
dst_reg->u32_min_value = var32_off.value;
dst_reg->u32_max_value = var32_off.value | var32_off.mask;
/* Safe to set s32 bounds by casting u32 result into s32 when u32
* doesn't cross sign boundary. Otherwise set s32 bounds to unbounded.
*/
if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) {
dst_reg->s32_min_value = dst_reg->u32_min_value;
dst_reg->s32_max_value = dst_reg->u32_max_value;
} else {
dst_reg->s32_min_value = S32_MIN;
dst_reg->s32_max_value = S32_MAX;
}
}
static void scalar_min_max_xor(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
bool src_known = tnum_is_const(src_reg->var_off);
bool dst_known = tnum_is_const(dst_reg->var_off);
if (src_known && dst_known) {
/* dst_reg->var_off.value has been updated earlier */
__mark_reg_known(dst_reg, dst_reg->var_off.value);
return;
}
/* We get both minimum and maximum from the var_off. */
dst_reg->umin_value = dst_reg->var_off.value;
dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;
/* Safe to set s64 bounds by casting u64 result into s64 when u64
* doesn't cross sign boundary. Otherwise set s64 bounds to unbounded.
*/
if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) {
dst_reg->smin_value = dst_reg->umin_value;
dst_reg->smax_value = dst_reg->umax_value;
} else {
dst_reg->smin_value = S64_MIN;
dst_reg->smax_value = S64_MAX;
}
__update_reg_bounds(dst_reg);
}
static void __scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
u64 umin_val, u64 umax_val)
{
/* We lose all sign bit information (except what we can pick
* up from var_off)
*/
dst_reg->s32_min_value = S32_MIN;
dst_reg->s32_max_value = S32_MAX;
/* If we might shift our top bit out, then we know nothing */
if (umax_val > 31 || dst_reg->u32_max_value > 1ULL << (31 - umax_val)) {
dst_reg->u32_min_value = 0;
dst_reg->u32_max_value = U32_MAX;
} else {
dst_reg->u32_min_value <<= umin_val;
dst_reg->u32_max_value <<= umax_val;
}
}
static void scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
u32 umax_val = src_reg->u32_max_value;
u32 umin_val = src_reg->u32_min_value;
/* u32 alu operation will zext upper bits */
struct tnum subreg = tnum_subreg(dst_reg->var_off);
__scalar32_min_max_lsh(dst_reg, umin_val, umax_val);
dst_reg->var_off = tnum_subreg(tnum_lshift(subreg, umin_val));
/* Not required but being careful mark reg64 bounds as unknown so
* that we are forced to pick them up from tnum and zext later and
* if some path skips this step we are still safe.
*/
__mark_reg64_unbounded(dst_reg);
__update_reg32_bounds(dst_reg);
}
static void __scalar64_min_max_lsh(struct bpf_reg_state *dst_reg,
u64 umin_val, u64 umax_val)
{
/* Special case <<32 because it is a common compiler pattern to sign
* extend subreg by doing <<32 s>>32. In this case if 32bit bounds are
* positive we know this shift will also be positive so we can track
* bounds correctly. Otherwise we lose all sign bit information except
* what we can pick up from var_off. Perhaps we can generalize this
* later to shifts of any length.
*/
if (umin_val == 32 && umax_val == 32 && dst_reg->s32_max_value >= 0)
dst_reg->smax_value = (s64)dst_reg->s32_max_value << 32;
else
dst_reg->smax_value = S64_MAX;
if (umin_val == 32 && umax_val == 32 && dst_reg->s32_min_value >= 0)
dst_reg->smin_value = (s64)dst_reg->s32_min_value << 32;
else
dst_reg->smin_value = S64_MIN;
/* If we might shift our top bit out, then we know nothing */
if (dst_reg->umax_value > 1ULL << (63 - umax_val)) {
dst_reg->umin_value = 0;
dst_reg->umax_value = U64_MAX;
} else {
dst_reg->umin_value <<= umin_val;
dst_reg->umax_value <<= umax_val;
}
}
static void scalar_min_max_lsh(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
u64 umax_val = src_reg->umax_value;
u64 umin_val = src_reg->umin_value;
/* scalar64 calc uses 32bit unshifted bounds so must be called first */
__scalar64_min_max_lsh(dst_reg, umin_val, umax_val);
__scalar32_min_max_lsh(dst_reg, umin_val, umax_val);
dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
/* We may learn something more from the var_off */
__update_reg_bounds(dst_reg);
}
static void scalar32_min_max_rsh(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
struct tnum subreg = tnum_subreg(dst_reg->var_off);
u32 umax_val = src_reg->u32_max_value;
u32 umin_val = src_reg->u32_min_value;
/* BPF_RSH is an unsigned shift. If the value in dst_reg might
* be negative, then either:
* 1) src_reg might be zero, so the sign bit of the result is
* unknown, so we lose our signed bounds
* 2) it's known negative, thus the unsigned bounds capture the
* signed bounds
* 3) the signed bounds cross zero, so they tell us nothing
* about the result
* If the value in dst_reg is known nonnegative, then again the
* unsigned bounds capture the signed bounds.
* Thus, in all cases it suffices to blow away our signed bounds
* and rely on inferring new ones from the unsigned bounds and
* var_off of the result.
*/
dst_reg->s32_min_value = S32_MIN;
dst_reg->s32_max_value = S32_MAX;
dst_reg->var_off = tnum_rshift(subreg, umin_val);
dst_reg->u32_min_value >>= umax_val;
dst_reg->u32_max_value >>= umin_val;
__mark_reg64_unbounded(dst_reg);
__update_reg32_bounds(dst_reg);
}
static void scalar_min_max_rsh(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
u64 umax_val = src_reg->umax_value;
u64 umin_val = src_reg->umin_value;
/* BPF_RSH is an unsigned shift. If the value in dst_reg might
* be negative, then either:
* 1) src_reg might be zero, so the sign bit of the result is
* unknown, so we lose our signed bounds
* 2) it's known negative, thus the unsigned bounds capture the
* signed bounds
* 3) the signed bounds cross zero, so they tell us nothing
* about the result
* If the value in dst_reg is known nonnegative, then again the
* unsigned bounds capture the signed bounds.
* Thus, in all cases it suffices to blow away our signed bounds
* and rely on inferring new ones from the unsigned bounds and
* var_off of the result.
*/
dst_reg->smin_value = S64_MIN;
dst_reg->smax_value = S64_MAX;
dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val);
dst_reg->umin_value >>= umax_val;
dst_reg->umax_value >>= umin_val;
/* Its not easy to operate on alu32 bounds here because it depends
* on bits being shifted in. Take easy way out and mark unbounded
* so we can recalculate later from tnum.
*/
__mark_reg32_unbounded(dst_reg);
__update_reg_bounds(dst_reg);
}
static void scalar32_min_max_arsh(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
u64 umin_val = src_reg->u32_min_value;
/* Upon reaching here, src_known is true and
* umax_val is equal to umin_val.
*/
dst_reg->s32_min_value = (u32)(((s32)dst_reg->s32_min_value) >> umin_val);
dst_reg->s32_max_value = (u32)(((s32)dst_reg->s32_max_value) >> umin_val);
dst_reg->var_off = tnum_arshift(tnum_subreg(dst_reg->var_off), umin_val, 32);
/* blow away the dst_reg umin_value/umax_value and rely on
* dst_reg var_off to refine the result.
*/
dst_reg->u32_min_value = 0;
dst_reg->u32_max_value = U32_MAX;
__mark_reg64_unbounded(dst_reg);
__update_reg32_bounds(dst_reg);
}
static void scalar_min_max_arsh(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
u64 umin_val = src_reg->umin_value;
/* Upon reaching here, src_known is true and umax_val is equal
* to umin_val.
*/
dst_reg->smin_value >>= umin_val;
dst_reg->smax_value >>= umin_val;
dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val, 64);
/* blow away the dst_reg umin_value/umax_value and rely on
* dst_reg var_off to refine the result.
*/
dst_reg->umin_value = 0;
dst_reg->umax_value = U64_MAX;
/* Its not easy to operate on alu32 bounds here because it depends
* on bits being shifted in from upper 32-bits. Take easy way out
* and mark unbounded so we can recalculate later from tnum.
*/
__mark_reg32_unbounded(dst_reg);
__update_reg_bounds(dst_reg);
}
static bool is_safe_to_compute_dst_reg_range(struct bpf_insn *insn,
const struct bpf_reg_state *src_reg)
{
bool src_is_const = false;
u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32;
if (insn_bitness == 32) {
if (tnum_subreg_is_const(src_reg->var_off)
&& src_reg->s32_min_value == src_reg->s32_max_value
&& src_reg->u32_min_value == src_reg->u32_max_value)
src_is_const = true;
} else {
if (tnum_is_const(src_reg->var_off)
&& src_reg->smin_value == src_reg->smax_value
&& src_reg->umin_value == src_reg->umax_value)
src_is_const = true;
}
switch (BPF_OP(insn->code)) {
case BPF_ADD:
case BPF_SUB:
case BPF_AND:
case BPF_XOR:
case BPF_OR:
case BPF_MUL:
return true;
/* Shift operators range is only computable if shift dimension operand
* is a constant. Shifts greater than 31 or 63 are undefined. This
* includes shifts by a negative number.
*/
case BPF_LSH:
case BPF_RSH:
case BPF_ARSH:
return (src_is_const && src_reg->umax_value < insn_bitness);
default:
return false;
}
}
/* WARNING: This function does calculations on 64-bit values, but the actual
* execution may occur on 32-bit values. Therefore, things like bitshifts
* need extra checks in the 32-bit case.
*/
static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
struct bpf_insn *insn,
struct bpf_reg_state *dst_reg,
struct bpf_reg_state src_reg)
{
u8 opcode = BPF_OP(insn->code);
bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64);
int ret;
if (!is_safe_to_compute_dst_reg_range(insn, &src_reg)) {
__mark_reg_unknown(env, dst_reg);
return 0;
}
if (sanitize_needed(opcode)) {
ret = sanitize_val_alu(env, insn);
if (ret < 0)
return sanitize_err(env, insn, ret, NULL, NULL);
}
/* Calculate sign/unsigned bounds and tnum for alu32 and alu64 bit ops.
* There are two classes of instructions: The first class we track both
* alu32 and alu64 sign/unsigned bounds independently this provides the
* greatest amount of precision when alu operations are mixed with jmp32
* operations. These operations are BPF_ADD, BPF_SUB, BPF_MUL, BPF_ADD,
* and BPF_OR. This is possible because these ops have fairly easy to
* understand and calculate behavior in both 32-bit and 64-bit alu ops.
* See alu32 verifier tests for examples. The second class of
* operations, BPF_LSH, BPF_RSH, and BPF_ARSH, however are not so easy
* with regards to tracking sign/unsigned bounds because the bits may
* cross subreg boundaries in the alu64 case. When this happens we mark
* the reg unbounded in the subreg bound space and use the resulting
* tnum to calculate an approximation of the sign/unsigned bounds.
*/
switch (opcode) {
case BPF_ADD:
scalar32_min_max_add(dst_reg, &src_reg);
scalar_min_max_add(dst_reg, &src_reg);
dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
break;
case BPF_SUB:
scalar32_min_max_sub(dst_reg, &src_reg);
scalar_min_max_sub(dst_reg, &src_reg);
dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off);
break;
case BPF_MUL:
dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off);
scalar32_min_max_mul(dst_reg, &src_reg);
scalar_min_max_mul(dst_reg, &src_reg);
break;
case BPF_AND:
dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off);
scalar32_min_max_and(dst_reg, &src_reg);
scalar_min_max_and(dst_reg, &src_reg);
break;
case BPF_OR:
dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off);
scalar32_min_max_or(dst_reg, &src_reg);
scalar_min_max_or(dst_reg, &src_reg);
break;
case BPF_XOR:
dst_reg->var_off = tnum_xor(dst_reg->var_off, src_reg.var_off);
scalar32_min_max_xor(dst_reg, &src_reg);
scalar_min_max_xor(dst_reg, &src_reg);
break;
case BPF_LSH:
if (alu32)
scalar32_min_max_lsh(dst_reg, &src_reg);
else
scalar_min_max_lsh(dst_reg, &src_reg);
break;
case BPF_RSH:
if (alu32)
scalar32_min_max_rsh(dst_reg, &src_reg);
else
scalar_min_max_rsh(dst_reg, &src_reg);
break;
case BPF_ARSH:
if (alu32)
scalar32_min_max_arsh(dst_reg, &src_reg);
else
scalar_min_max_arsh(dst_reg, &src_reg);
break;
default:
break;
}
/* ALU32 ops are zero extended into 64bit register */
if (alu32)
zext_32_to_64(dst_reg);
reg_bounds_sync(dst_reg);
return 0;
}
/* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max
* and var_off.
*/
static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
struct bpf_insn *insn)
{
struct bpf_verifier_state *vstate = env->cur_state;
struct bpf_func_state *state = vstate->frame[vstate->curframe];
struct bpf_reg_state *regs = state->regs, *dst_reg, *src_reg;
struct bpf_reg_state *ptr_reg = NULL, off_reg = {0};
bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64);
u8 opcode = BPF_OP(insn->code);
int err;
dst_reg = ®s[insn->dst_reg];
src_reg = NULL;
if (dst_reg->type == PTR_TO_ARENA) {
struct bpf_insn_aux_data *aux = cur_aux(env);
if (BPF_CLASS(insn->code) == BPF_ALU64)
/*
* 32-bit operations zero upper bits automatically.
* 64-bit operations need to be converted to 32.
*/
aux->needs_zext = true;
/* Any arithmetic operations are allowed on arena pointers */
return 0;
}
if (dst_reg->type != SCALAR_VALUE)
ptr_reg = dst_reg;
if (BPF_SRC(insn->code) == BPF_X) {
src_reg = ®s[insn->src_reg];
if (src_reg->type != SCALAR_VALUE) {
if (dst_reg->type != SCALAR_VALUE) {
/* Combining two pointers by any ALU op yields
* an arbitrary scalar. Disallow all math except
* pointer subtraction
*/
if (opcode == BPF_SUB && env->allow_ptr_leaks) {
mark_reg_unknown(env, regs, insn->dst_reg);
return 0;
}
verbose(env, "R%d pointer %s pointer prohibited\n",
insn->dst_reg,
bpf_alu_string[opcode >> 4]);
return -EACCES;
} else {
/* scalar += pointer
* This is legal, but we have to reverse our
* src/dest handling in computing the range
*/
err = mark_chain_precision(env, insn->dst_reg);
if (err)
return err;
return adjust_ptr_min_max_vals(env, insn,
src_reg, dst_reg);
}
} else if (ptr_reg) {
/* pointer += scalar */
err = mark_chain_precision(env, insn->src_reg);
if (err)
return err;
return adjust_ptr_min_max_vals(env, insn,
dst_reg, src_reg);
} else if (dst_reg->precise) {
/* if dst_reg is precise, src_reg should be precise as well */
err = mark_chain_precision(env, insn->src_reg);
if (err)
return err;
}
} else {
/* Pretend the src is a reg with a known value, since we only
* need to be able to read from this state.
*/
off_reg.type = SCALAR_VALUE;
__mark_reg_known(&off_reg, insn->imm);
src_reg = &off_reg;
if (ptr_reg) /* pointer += K */
return adjust_ptr_min_max_vals(env, insn,
ptr_reg, src_reg);
}
/* Got here implies adding two SCALAR_VALUEs */
if (WARN_ON_ONCE(ptr_reg)) {
print_verifier_state(env, state, true);
verbose(env, "verifier internal error: unexpected ptr_reg\n");
return -EINVAL;
}
if (WARN_ON(!src_reg)) {
print_verifier_state(env, state, true);
verbose(env, "verifier internal error: no src_reg\n");
return -EINVAL;
}
err = adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg);
if (err)
return err;
/*
* Compilers can generate the code
* r1 = r2
* r1 += 0x1
* if r2 < 1000 goto ...
* use r1 in memory access
* So remember constant delta between r2 and r1 and update r1 after
* 'if' condition.
*/
if (env->bpf_capable && BPF_OP(insn->code) == BPF_ADD &&
dst_reg->id && is_reg_const(src_reg, alu32)) {
u64 val = reg_const_value(src_reg, alu32);
if ((dst_reg->id & BPF_ADD_CONST) ||
/* prevent overflow in sync_linked_regs() later */
val > (u32)S32_MAX) {
/*
* If the register already went through rX += val
* we cannot accumulate another val into rx->off.
*/
dst_reg->off = 0;
dst_reg->id = 0;
} else {
dst_reg->id |= BPF_ADD_CONST;
dst_reg->off = val;
}
} else {
/*
* Make sure ID is cleared otherwise dst_reg min/max could be
* incorrectly propagated into other registers by sync_linked_regs()
*/
dst_reg->id = 0;
}
return 0;
}
/* check validity of 32-bit and 64-bit arithmetic operations */
static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
struct bpf_reg_state *regs = cur_regs(env);
u8 opcode = BPF_OP(insn->code);
int err;
if (opcode == BPF_END || opcode == BPF_NEG) {
if (opcode == BPF_NEG) {
if (BPF_SRC(insn->code) != BPF_K ||
insn->src_reg != BPF_REG_0 ||
insn->off != 0 || insn->imm != 0) {
verbose(env, "BPF_NEG uses reserved fields\n");
return -EINVAL;
}
} else {
if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
(insn->imm != 16 && insn->imm != 32 && insn->imm != 64) ||
(BPF_CLASS(insn->code) == BPF_ALU64 &&
BPF_SRC(insn->code) != BPF_TO_LE)) {
verbose(env, "BPF_END uses reserved fields\n");
return -EINVAL;
}
}
/* check src operand */
err = check_reg_arg(env, insn->dst_reg, SRC_OP);
if (err)
return err;
if (is_pointer_value(env, insn->dst_reg)) {
verbose(env, "R%d pointer arithmetic prohibited\n",
insn->dst_reg);
return -EACCES;
}
/* check dest operand */
err = check_reg_arg(env, insn->dst_reg, DST_OP);
if (err)
return err;
} else if (opcode == BPF_MOV) {
if (BPF_SRC(insn->code) == BPF_X) {
if (BPF_CLASS(insn->code) == BPF_ALU) {
if ((insn->off != 0 && insn->off != 8 && insn->off != 16) ||
insn->imm) {
verbose(env, "BPF_MOV uses reserved fields\n");
return -EINVAL;
}
} else if (insn->off == BPF_ADDR_SPACE_CAST) {
if (insn->imm != 1 && insn->imm != 1u << 16) {
verbose(env, "addr_space_cast insn can only convert between address space 1 and 0\n");
return -EINVAL;
}
if (!env->prog->aux->arena) {
verbose(env, "addr_space_cast insn can only be used in a program that has an associated arena\n");
return -EINVAL;
}
} else {
if ((insn->off != 0 && insn->off != 8 && insn->off != 16 &&
insn->off != 32) || insn->imm) {
verbose(env, "BPF_MOV uses reserved fields\n");
return -EINVAL;
}
}
/* check src operand */
err = check_reg_arg(env, insn->src_reg, SRC_OP);
if (err)
return err;
} else {
if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
verbose(env, "BPF_MOV uses reserved fields\n");
return -EINVAL;
}
}
/* check dest operand, mark as required later */
err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
if (err)
return err;
if (BPF_SRC(insn->code) == BPF_X) {
struct bpf_reg_state *src_reg = regs + insn->src_reg;
struct bpf_reg_state *dst_reg = regs + insn->dst_reg;
if (BPF_CLASS(insn->code) == BPF_ALU64) {
if (insn->imm) {
/* off == BPF_ADDR_SPACE_CAST */
mark_reg_unknown(env, regs, insn->dst_reg);
if (insn->imm == 1) { /* cast from as(1) to as(0) */
dst_reg->type = PTR_TO_ARENA;
/* PTR_TO_ARENA is 32-bit */
dst_reg->subreg_def = env->insn_idx + 1;
}
} else if (insn->off == 0) {
/* case: R1 = R2
* copy register state to dest reg
*/
assign_scalar_id_before_mov(env, src_reg);
copy_register_state(dst_reg, src_reg);
dst_reg->live |= REG_LIVE_WRITTEN;
dst_reg->subreg_def = DEF_NOT_SUBREG;
} else {
/* case: R1 = (s8, s16 s32)R2 */
if (is_pointer_value(env, insn->src_reg)) {
verbose(env,
"R%d sign-extension part of pointer\n",
insn->src_reg);
return -EACCES;
} else if (src_reg->type == SCALAR_VALUE) {
bool no_sext;
no_sext = src_reg->umax_value < (1ULL << (insn->off - 1));
if (no_sext)
assign_scalar_id_before_mov(env, src_reg);
copy_register_state(dst_reg, src_reg);
if (!no_sext)
dst_reg->id = 0;
coerce_reg_to_size_sx(dst_reg, insn->off >> 3);
dst_reg->live |= REG_LIVE_WRITTEN;
dst_reg->subreg_def = DEF_NOT_SUBREG;
} else {
mark_reg_unknown(env, regs, insn->dst_reg);
}
}
} else {
/* R1 = (u32) R2 */
if (is_pointer_value(env, insn->src_reg)) {
verbose(env,
"R%d partial copy of pointer\n",
insn->src_reg);
return -EACCES;
} else if (src_reg->type == SCALAR_VALUE) {
if (insn->off == 0) {
bool is_src_reg_u32 = get_reg_width(src_reg) <= 32;
if (is_src_reg_u32)
assign_scalar_id_before_mov(env, src_reg);
copy_register_state(dst_reg, src_reg);
/* Make sure ID is cleared if src_reg is not in u32
* range otherwise dst_reg min/max could be incorrectly
* propagated into src_reg by sync_linked_regs()
*/
if (!is_src_reg_u32)
dst_reg->id = 0;
dst_reg->live |= REG_LIVE_WRITTEN;
dst_reg->subreg_def = env->insn_idx + 1;
} else {
/* case: W1 = (s8, s16)W2 */
bool no_sext = src_reg->umax_value < (1ULL << (insn->off - 1));
if (no_sext)
assign_scalar_id_before_mov(env, src_reg);
copy_register_state(dst_reg, src_reg);
if (!no_sext)
dst_reg->id = 0;
dst_reg->live |= REG_LIVE_WRITTEN;
dst_reg->subreg_def = env->insn_idx + 1;
coerce_subreg_to_size_sx(dst_reg, insn->off >> 3);
}
} else {
mark_reg_unknown(env, regs,
insn->dst_reg);
}
zext_32_to_64(dst_reg);
reg_bounds_sync(dst_reg);
}
} else {
/* case: R = imm
* remember the value we stored into this reg
*/
/* clear any state __mark_reg_known doesn't set */
mark_reg_unknown(env, regs, insn->dst_reg);
regs[insn->dst_reg].type = SCALAR_VALUE;
if (BPF_CLASS(insn->code) == BPF_ALU64) {
__mark_reg_known(regs + insn->dst_reg,
insn->imm);
} else {
__mark_reg_known(regs + insn->dst_reg,
(u32)insn->imm);
}
}
} else if (opcode > BPF_END) {
verbose(env, "invalid BPF_ALU opcode %x\n", opcode);
return -EINVAL;
} else { /* all other ALU ops: and, sub, xor, add, ... */
if (BPF_SRC(insn->code) == BPF_X) {
if (insn->imm != 0 || insn->off > 1 ||
(insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) {
verbose(env, "BPF_ALU uses reserved fields\n");
return -EINVAL;
}
/* check src1 operand */
err = check_reg_arg(env, insn->src_reg, SRC_OP);
if (err)
return err;
} else {
if (insn->src_reg != BPF_REG_0 || insn->off > 1 ||
(insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) {
verbose(env, "BPF_ALU uses reserved fields\n");
return -EINVAL;
}
}
/* check src2 operand */
err = check_reg_arg(env, insn->dst_reg, SRC_OP);
if (err)
return err;
if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
verbose(env, "div by zero\n");
return -EINVAL;
}
if ((opcode == BPF_LSH || opcode == BPF_RSH ||
opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
if (insn->imm < 0 || insn->imm >= size) {
verbose(env, "invalid shift %d\n", insn->imm);
return -EINVAL;
}
}
/* check dest operand */
err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
err = err ?: adjust_reg_min_max_vals(env, insn);
if (err)
return err;
}
return reg_bounds_sanity_check(env, ®s[insn->dst_reg], "alu");
}
static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
struct bpf_reg_state *dst_reg,
enum bpf_reg_type type,
bool range_right_open)
{
struct bpf_func_state *state;
struct bpf_reg_state *reg;
int new_range;
if (dst_reg->off < 0 ||
(dst_reg->off == 0 && range_right_open))
/* This doesn't give us any range */
return;
if (dst_reg->umax_value > MAX_PACKET_OFF ||
dst_reg->umax_value + dst_reg->off > MAX_PACKET_OFF)
/* Risk of overflow. For instance, ptr + (1<<63) may be less
* than pkt_end, but that's because it's also less than pkt.
*/
return;
new_range = dst_reg->off;
if (range_right_open)
new_range++;
/* Examples for register markings:
*
* pkt_data in dst register:
*
* r2 = r3;
* r2 += 8;
* if (r2 > pkt_end) goto <handle exception>
* <access okay>
*
* r2 = r3;
* r2 += 8;
* if (r2 < pkt_end) goto <access okay>
* <handle exception>
*
* Where:
* r2 == dst_reg, pkt_end == src_reg
* r2=pkt(id=n,off=8,r=0)
* r3=pkt(id=n,off=0,r=0)
*
* pkt_data in src register:
*
* r2 = r3;
* r2 += 8;
* if (pkt_end >= r2) goto <access okay>
* <handle exception>
*
* r2 = r3;
* r2 += 8;
* if (pkt_end <= r2) goto <handle exception>
* <access okay>
*
* Where:
* pkt_end == dst_reg, r2 == src_reg
* r2=pkt(id=n,off=8,r=0)
* r3=pkt(id=n,off=0,r=0)
*
* Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
* or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8)
* and [r3, r3 + 8-1) respectively is safe to access depending on
* the check.
*/
/* If our ids match, then we must have the same max_value. And we
* don't care about the other reg's fixed offset, since if it's too big
* the range won't allow anything.
* dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16.
*/
bpf_for_each_reg_in_vstate(vstate, state, reg, ({
if (reg->type == type && reg->id == dst_reg->id)
/* keep the maximum range already checked */
reg->range = max(reg->range, new_range);
}));
}
/*
* <reg1> <op> <reg2>, currently assuming reg2 is a constant
*/
static int is_scalar_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2,
u8 opcode, bool is_jmp32)
{
struct tnum t1 = is_jmp32 ? tnum_subreg(reg1->var_off) : reg1->var_off;
struct tnum t2 = is_jmp32 ? tnum_subreg(reg2->var_off) : reg2->var_off;
u64 umin1 = is_jmp32 ? (u64)reg1->u32_min_value : reg1->umin_value;
u64 umax1 = is_jmp32 ? (u64)reg1->u32_max_value : reg1->umax_value;
s64 smin1 = is_jmp32 ? (s64)reg1->s32_min_value : reg1->smin_value;
s64 smax1 = is_jmp32 ? (s64)reg1->s32_max_value : reg1->smax_value;
u64 umin2 = is_jmp32 ? (u64)reg2->u32_min_value : reg2->umin_value;
u64 umax2 = is_jmp32 ? (u64)reg2->u32_max_value : reg2->umax_value;
s64 smin2 = is_jmp32 ? (s64)reg2->s32_min_value : reg2->smin_value;
s64 smax2 = is_jmp32 ? (s64)reg2->s32_max_value : reg2->smax_value;
switch (opcode) {
case BPF_JEQ:
/* constants, umin/umax and smin/smax checks would be
* redundant in this case because they all should match
*/
if (tnum_is_const(t1) && tnum_is_const(t2))
return t1.value == t2.value;
/* non-overlapping ranges */
if (umin1 > umax2 || umax1 < umin2)
return 0;
if (smin1 > smax2 || smax1 < smin2)
return 0;
if (!is_jmp32) {
/* if 64-bit ranges are inconclusive, see if we can
* utilize 32-bit subrange knowledge to eliminate
* branches that can't be taken a priori
*/
if (reg1->u32_min_value > reg2->u32_max_value ||
reg1->u32_max_value < reg2->u32_min_value)
return 0;
if (reg1->s32_min_value > reg2->s32_max_value ||
reg1->s32_max_value < reg2->s32_min_value)
return 0;
}
break;
case BPF_JNE:
/* constants, umin/umax and smin/smax checks would be
* redundant in this case because they all should match
*/
if (tnum_is_const(t1) && tnum_is_const(t2))
return t1.value != t2.value;
/* non-overlapping ranges */
if (umin1 > umax2 || umax1 < umin2)
return 1;
if (smin1 > smax2 || smax1 < smin2)
return 1;
if (!is_jmp32) {
/* if 64-bit ranges are inconclusive, see if we can
* utilize 32-bit subrange knowledge to eliminate
* branches that can't be taken a priori
*/
if (reg1->u32_min_value > reg2->u32_max_value ||
reg1->u32_max_value < reg2->u32_min_value)
return 1;
if (reg1->s32_min_value > reg2->s32_max_value ||
reg1->s32_max_value < reg2->s32_min_value)
return 1;
}
break;
case BPF_JSET:
if (!is_reg_const(reg2, is_jmp32)) {
swap(reg1, reg2);
swap(t1, t2);
}
if (!is_reg_const(reg2, is_jmp32))
return -1;
if ((~t1.mask & t1.value) & t2.value)
return 1;
if (!((t1.mask | t1.value) & t2.value))
return 0;
break;
case BPF_JGT:
if (umin1 > umax2)
return 1;
else if (umax1 <= umin2)
return 0;
break;
case BPF_JSGT:
if (smin1 > smax2)
return 1;
else if (smax1 <= smin2)
return 0;
break;
case BPF_JLT:
if (umax1 < umin2)
return 1;
else if (umin1 >= umax2)
return 0;
break;
case BPF_JSLT:
if (smax1 < smin2)
return 1;
else if (smin1 >= smax2)
return 0;
break;
case BPF_JGE:
if (umin1 >= umax2)
return 1;
else if (umax1 < umin2)
return 0;
break;
case BPF_JSGE:
if (smin1 >= smax2)
return 1;
else if (smax1 < smin2)
return 0;
break;
case BPF_JLE:
if (umax1 <= umin2)
return 1;
else if (umin1 > umax2)
return 0;
break;
case BPF_JSLE:
if (smax1 <= smin2)
return 1;
else if (smin1 > smax2)
return 0;
break;
}
return -1;
}
static int flip_opcode(u32 opcode)
{
/* How can we transform "a <op> b" into "b <op> a"? */
static const u8 opcode_flip[16] = {
/* these stay the same */
[BPF_JEQ >> 4] = BPF_JEQ,
[BPF_JNE >> 4] = BPF_JNE,
[BPF_JSET >> 4] = BPF_JSET,
/* these swap "lesser" and "greater" (L and G in the opcodes) */
[BPF_JGE >> 4] = BPF_JLE,
[BPF_JGT >> 4] = BPF_JLT,
[BPF_JLE >> 4] = BPF_JGE,
[BPF_JLT >> 4] = BPF_JGT,
[BPF_JSGE >> 4] = BPF_JSLE,
[BPF_JSGT >> 4] = BPF_JSLT,
[BPF_JSLE >> 4] = BPF_JSGE,
[BPF_JSLT >> 4] = BPF_JSGT
};
return opcode_flip[opcode >> 4];
}
static int is_pkt_ptr_branch_taken(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg,
u8 opcode)
{
struct bpf_reg_state *pkt;
if (src_reg->type == PTR_TO_PACKET_END) {
pkt = dst_reg;
} else if (dst_reg->type == PTR_TO_PACKET_END) {
pkt = src_reg;
opcode = flip_opcode(opcode);
} else {
return -1;
}
if (pkt->range >= 0)
return -1;
switch (opcode) {
case BPF_JLE:
/* pkt <= pkt_end */
fallthrough;
case BPF_JGT:
/* pkt > pkt_end */
if (pkt->range == BEYOND_PKT_END)
/* pkt has at last one extra byte beyond pkt_end */
return opcode == BPF_JGT;
break;
case BPF_JLT:
/* pkt < pkt_end */
fallthrough;
case BPF_JGE:
/* pkt >= pkt_end */
if (pkt->range == BEYOND_PKT_END || pkt->range == AT_PKT_END)
return opcode == BPF_JGE;
break;
}
return -1;
}
/* compute branch direction of the expression "if (<reg1> opcode <reg2>) goto target;"
* and return:
* 1 - branch will be taken and "goto target" will be executed
* 0 - branch will not be taken and fall-through to next insn
* -1 - unknown. Example: "if (reg1 < 5)" is unknown when register value
* range [0,10]
*/
static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2,
u8 opcode, bool is_jmp32)
{
if (reg_is_pkt_pointer_any(reg1) && reg_is_pkt_pointer_any(reg2) && !is_jmp32)
return is_pkt_ptr_branch_taken(reg1, reg2, opcode);
if (__is_pointer_value(false, reg1) || __is_pointer_value(false, reg2)) {
u64 val;
/* arrange that reg2 is a scalar, and reg1 is a pointer */
if (!is_reg_const(reg2, is_jmp32)) {
opcode = flip_opcode(opcode);
swap(reg1, reg2);
}
/* and ensure that reg2 is a constant */
if (!is_reg_const(reg2, is_jmp32))
return -1;
if (!reg_not_null(reg1))
return -1;
/* If pointer is valid tests against zero will fail so we can
* use this to direct branch taken.
*/
val = reg_const_value(reg2, is_jmp32);
if (val != 0)
return -1;
switch (opcode) {
case BPF_JEQ:
return 0;
case BPF_JNE:
return 1;
default:
return -1;
}
}
/* now deal with two scalars, but not necessarily constants */
return is_scalar_branch_taken(reg1, reg2, opcode, is_jmp32);
}
/* Opcode that corresponds to a *false* branch condition.
* E.g., if r1 < r2, then reverse (false) condition is r1 >= r2
*/
static u8 rev_opcode(u8 opcode)
{
switch (opcode) {
case BPF_JEQ: return BPF_JNE;
case BPF_JNE: return BPF_JEQ;
/* JSET doesn't have it's reverse opcode in BPF, so add
* BPF_X flag to denote the reverse of that operation
*/
case BPF_JSET: return BPF_JSET | BPF_X;
case BPF_JSET | BPF_X: return BPF_JSET;
case BPF_JGE: return BPF_JLT;
case BPF_JGT: return BPF_JLE;
case BPF_JLE: return BPF_JGT;
case BPF_JLT: return BPF_JGE;
case BPF_JSGE: return BPF_JSLT;
case BPF_JSGT: return BPF_JSLE;
case BPF_JSLE: return BPF_JSGT;
case BPF_JSLT: return BPF_JSGE;
default: return 0;
}
}
/* Refine range knowledge for <reg1> <op> <reg>2 conditional operation. */
static void regs_refine_cond_op(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2,
u8 opcode, bool is_jmp32)
{
struct tnum t;
u64 val;
/* In case of GE/GT/SGE/JST, reuse LE/LT/SLE/SLT logic from below */
switch (opcode) {
case BPF_JGE:
case BPF_JGT:
case BPF_JSGE:
case BPF_JSGT:
opcode = flip_opcode(opcode);
swap(reg1, reg2);
break;
default:
break;
}
switch (opcode) {
case BPF_JEQ:
if (is_jmp32) {
reg1->u32_min_value = max(reg1->u32_min_value, reg2->u32_min_value);
reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value);
reg1->s32_min_value = max(reg1->s32_min_value, reg2->s32_min_value);
reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value);
reg2->u32_min_value = reg1->u32_min_value;
reg2->u32_max_value = reg1->u32_max_value;
reg2->s32_min_value = reg1->s32_min_value;
reg2->s32_max_value = reg1->s32_max_value;
t = tnum_intersect(tnum_subreg(reg1->var_off), tnum_subreg(reg2->var_off));
reg1->var_off = tnum_with_subreg(reg1->var_off, t);
reg2->var_off = tnum_with_subreg(reg2->var_off, t);
} else {
reg1->umin_value = max(reg1->umin_value, reg2->umin_value);
reg1->umax_value = min(reg1->umax_value, reg2->umax_value);
reg1->smin_value = max(reg1->smin_value, reg2->smin_value);
reg1->smax_value = min(reg1->smax_value, reg2->smax_value);
reg2->umin_value = reg1->umin_value;
reg2->umax_value = reg1->umax_value;
reg2->smin_value = reg1->smin_value;
reg2->smax_value = reg1->smax_value;
reg1->var_off = tnum_intersect(reg1->var_off, reg2->var_off);
reg2->var_off = reg1->var_off;
}
break;
case BPF_JNE:
if (!is_reg_const(reg2, is_jmp32))
swap(reg1, reg2);
if (!is_reg_const(reg2, is_jmp32))
break;
/* try to recompute the bound of reg1 if reg2 is a const and
* is exactly the edge of reg1.
*/
val = reg_const_value(reg2, is_jmp32);
if (is_jmp32) {
/* u32_min_value is not equal to 0xffffffff at this point,
* because otherwise u32_max_value is 0xffffffff as well,
* in such a case both reg1 and reg2 would be constants,
* jump would be predicted and reg_set_min_max() won't
* be called.
*
* Same reasoning works for all {u,s}{min,max}{32,64} cases
* below.
*/
if (reg1->u32_min_value == (u32)val)
reg1->u32_min_value++;
if (reg1->u32_max_value == (u32)val)
reg1->u32_max_value--;
if (reg1->s32_min_value == (s32)val)
reg1->s32_min_value++;
if (reg1->s32_max_value == (s32)val)
reg1->s32_max_value--;
} else {
if (reg1->umin_value == (u64)val)
reg1->umin_value++;
if (reg1->umax_value == (u64)val)
reg1->umax_value--;
if (reg1->smin_value == (s64)val)
reg1->smin_value++;
if (reg1->smax_value == (s64)val)
reg1->smax_value--;
}
break;
case BPF_JSET:
if (!is_reg_const(reg2, is_jmp32))
swap(reg1, reg2);
if (!is_reg_const(reg2, is_jmp32))
break;
val = reg_const_value(reg2, is_jmp32);
/* BPF_JSET (i.e., TRUE branch, *not* BPF_JSET | BPF_X)
* requires single bit to learn something useful. E.g., if we
* know that `r1 & 0x3` is true, then which bits (0, 1, or both)
* are actually set? We can learn something definite only if
* it's a single-bit value to begin with.
*
* BPF_JSET | BPF_X (i.e., negation of BPF_JSET) doesn't have
* this restriction. I.e., !(r1 & 0x3) means neither bit 0 nor
* bit 1 is set, which we can readily use in adjustments.
*/
if (!is_power_of_2(val))
break;
if (is_jmp32) {
t = tnum_or(tnum_subreg(reg1->var_off), tnum_const(val));
reg1->var_off = tnum_with_subreg(reg1->var_off, t);
} else {
reg1->var_off = tnum_or(reg1->var_off, tnum_const(val));
}
break;
case BPF_JSET | BPF_X: /* reverse of BPF_JSET, see rev_opcode() */
if (!is_reg_const(reg2, is_jmp32))
swap(reg1, reg2);
if (!is_reg_const(reg2, is_jmp32))
break;
val = reg_const_value(reg2, is_jmp32);
if (is_jmp32) {
t = tnum_and(tnum_subreg(reg1->var_off), tnum_const(~val));
reg1->var_off = tnum_with_subreg(reg1->var_off, t);
} else {
reg1->var_off = tnum_and(reg1->var_off, tnum_const(~val));
}
break;
case BPF_JLE:
if (is_jmp32) {
reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value);
reg2->u32_min_value = max(reg1->u32_min_value, reg2->u32_min_value);
} else {
reg1->umax_value = min(reg1->umax_value, reg2->umax_value);
reg2->umin_value = max(reg1->umin_value, reg2->umin_value);
}
break;
case BPF_JLT:
if (is_jmp32) {
reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value - 1);
reg2->u32_min_value = max(reg1->u32_min_value + 1, reg2->u32_min_value);
} else {
reg1->umax_value = min(reg1->umax_value, reg2->umax_value - 1);
reg2->umin_value = max(reg1->umin_value + 1, reg2->umin_value);
}
break;
case BPF_JSLE:
if (is_jmp32) {
reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value);
reg2->s32_min_value = max(reg1->s32_min_value, reg2->s32_min_value);
} else {
reg1->smax_value = min(reg1->smax_value, reg2->smax_value);
reg2->smin_value = max(reg1->smin_value, reg2->smin_value);
}
break;
case BPF_JSLT:
if (is_jmp32) {
reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value - 1);
reg2->s32_min_value = max(reg1->s32_min_value + 1, reg2->s32_min_value);
} else {
reg1->smax_value = min(reg1->smax_value, reg2->smax_value - 1);
reg2->smin_value = max(reg1->smin_value + 1, reg2->smin_value);
}
break;
default:
return;
}
}
/* Adjusts the register min/max values in the case that the dst_reg and
* src_reg are both SCALAR_VALUE registers (or we are simply doing a BPF_K
* check, in which case we have a fake SCALAR_VALUE representing insn->imm).
* Technically we can do similar adjustments for pointers to the same object,
* but we don't support that right now.
*/
static int reg_set_min_max(struct bpf_verifier_env *env,
struct bpf_reg_state *true_reg1,
struct bpf_reg_state *true_reg2,
struct bpf_reg_state *false_reg1,
struct bpf_reg_state *false_reg2,
u8 opcode, bool is_jmp32)
{
int err;
/* If either register is a pointer, we can't learn anything about its
* variable offset from the compare (unless they were a pointer into
* the same object, but we don't bother with that).
*/
if (false_reg1->type != SCALAR_VALUE || false_reg2->type != SCALAR_VALUE)
return 0;
/* fallthrough (FALSE) branch */
regs_refine_cond_op(false_reg1, false_reg2, rev_opcode(opcode), is_jmp32);
reg_bounds_sync(false_reg1);
reg_bounds_sync(false_reg2);
/* jump (TRUE) branch */
regs_refine_cond_op(true_reg1, true_reg2, opcode, is_jmp32);
reg_bounds_sync(true_reg1);
reg_bounds_sync(true_reg2);
err = reg_bounds_sanity_check(env, true_reg1, "true_reg1");
err = err ?: reg_bounds_sanity_check(env, true_reg2, "true_reg2");
err = err ?: reg_bounds_sanity_check(env, false_reg1, "false_reg1");
err = err ?: reg_bounds_sanity_check(env, false_reg2, "false_reg2");
return err;
}
static void mark_ptr_or_null_reg(struct bpf_func_state *state,
struct bpf_reg_state *reg, u32 id,
bool is_null)
{
if (type_may_be_null(reg->type) && reg->id == id &&
(is_rcu_reg(reg) || !WARN_ON_ONCE(!reg->id))) {
/* Old offset (both fixed and variable parts) should have been
* known-zero, because we don't allow pointer arithmetic on
* pointers that might be NULL. If we see this happening, don't
* convert the register.
*
* But in some cases, some helpers that return local kptrs
* advance offset for the returned pointer. In those cases, it
* is fine to expect to see reg->off.
*/
if (WARN_ON_ONCE(reg->smin_value || reg->smax_value || !tnum_equals_const(reg->var_off, 0)))
return;
if (!(type_is_ptr_alloc_obj(reg->type) || type_is_non_owning_ref(reg->type)) &&
WARN_ON_ONCE(reg->off))
return;
if (is_null) {
reg->type = SCALAR_VALUE;
/* We don't need id and ref_obj_id from this point
* onwards anymore, thus we should better reset it,
* so that state pruning has chances to take effect.
*/
reg->id = 0;
reg->ref_obj_id = 0;
return;
}
mark_ptr_not_null_reg(reg);
if (!reg_may_point_to_spin_lock(reg)) {
/* For not-NULL ptr, reg->ref_obj_id will be reset
* in release_reference().
*
* reg->id is still used by spin_lock ptr. Other
* than spin_lock ptr type, reg->id can be reset.
*/
reg->id = 0;
}
}
}
/* The logic is similar to find_good_pkt_pointers(), both could eventually
* be folded together at some point.
*/
static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno,
bool is_null)
{
struct bpf_func_state *state = vstate->frame[vstate->curframe];
struct bpf_reg_state *regs = state->regs, *reg;
u32 ref_obj_id = regs[regno].ref_obj_id;
u32 id = regs[regno].id;
if (ref_obj_id && ref_obj_id == id && is_null)
/* regs[regno] is in the " == NULL" branch.
* No one could have freed the reference state before
* doing the NULL check.
*/
WARN_ON_ONCE(release_reference_state(state, id));
bpf_for_each_reg_in_vstate(vstate, state, reg, ({
mark_ptr_or_null_reg(state, reg, id, is_null);
}));
}
static bool try_match_pkt_pointers(const struct bpf_insn *insn,
struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg,
struct bpf_verifier_state *this_branch,
struct bpf_verifier_state *other_branch)
{
if (BPF_SRC(insn->code) != BPF_X)
return false;
/* Pointers are always 64-bit. */
if (BPF_CLASS(insn->code) == BPF_JMP32)
return false;
switch (BPF_OP(insn->code)) {
case BPF_JGT:
if ((dst_reg->type == PTR_TO_PACKET &&
src_reg->type == PTR_TO_PACKET_END) ||
(dst_reg->type == PTR_TO_PACKET_META &&
reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
/* pkt_data' > pkt_end, pkt_meta' > pkt_data */
find_good_pkt_pointers(this_branch, dst_reg,
dst_reg->type, false);
mark_pkt_end(other_branch, insn->dst_reg, true);
} else if ((dst_reg->type == PTR_TO_PACKET_END &&
src_reg->type == PTR_TO_PACKET) ||
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
src_reg->type == PTR_TO_PACKET_META)) {
/* pkt_end > pkt_data', pkt_data > pkt_meta' */
find_good_pkt_pointers(other_branch, src_reg,
src_reg->type, true);
mark_pkt_end(this_branch, insn->src_reg, false);
} else {
return false;
}
break;
case BPF_JLT:
if ((dst_reg->type == PTR_TO_PACKET &&
src_reg->type == PTR_TO_PACKET_END) ||
(dst_reg->type == PTR_TO_PACKET_META &&
reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
/* pkt_data' < pkt_end, pkt_meta' < pkt_data */
find_good_pkt_pointers(other_branch, dst_reg,
dst_reg->type, true);
mark_pkt_end(this_branch, insn->dst_reg, false);
} else if ((dst_reg->type == PTR_TO_PACKET_END &&
src_reg->type == PTR_TO_PACKET) ||
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
src_reg->type == PTR_TO_PACKET_META)) {
/* pkt_end < pkt_data', pkt_data > pkt_meta' */
find_good_pkt_pointers(this_branch, src_reg,
src_reg->type, false);
mark_pkt_end(other_branch, insn->src_reg, true);
} else {
return false;
}
break;
case BPF_JGE:
if ((dst_reg->type == PTR_TO_PACKET &&
src_reg->type == PTR_TO_PACKET_END) ||
(dst_reg->type == PTR_TO_PACKET_META &&
reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
/* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */
find_good_pkt_pointers(this_branch, dst_reg,
dst_reg->type, true);
mark_pkt_end(other_branch, insn->dst_reg, false);
} else if ((dst_reg->type == PTR_TO_PACKET_END &&
src_reg->type == PTR_TO_PACKET) ||
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
src_reg->type == PTR_TO_PACKET_META)) {
/* pkt_end >= pkt_data', pkt_data >= pkt_meta' */
find_good_pkt_pointers(other_branch, src_reg,
src_reg->type, false);
mark_pkt_end(this_branch, insn->src_reg, true);
} else {
return false;
}
break;
case BPF_JLE:
if ((dst_reg->type == PTR_TO_PACKET &&
src_reg->type == PTR_TO_PACKET_END) ||
(dst_reg->type == PTR_TO_PACKET_META &&
reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
/* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */
find_good_pkt_pointers(other_branch, dst_reg,
dst_reg->type, false);
mark_pkt_end(this_branch, insn->dst_reg, true);
} else if ((dst_reg->type == PTR_TO_PACKET_END &&
src_reg->type == PTR_TO_PACKET) ||
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
src_reg->type == PTR_TO_PACKET_META)) {
/* pkt_end <= pkt_data', pkt_data <= pkt_meta' */
find_good_pkt_pointers(this_branch, src_reg,
src_reg->type, true);
mark_pkt_end(other_branch, insn->src_reg, false);
} else {
return false;
}
break;
default:
return false;
}
return true;
}
static void __collect_linked_regs(struct linked_regs *reg_set, struct bpf_reg_state *reg,
u32 id, u32 frameno, u32 spi_or_reg, bool is_reg)
{
struct linked_reg *e;
if (reg->type != SCALAR_VALUE || (reg->id & ~BPF_ADD_CONST) != id)
return;
e = linked_regs_push(reg_set);
if (e) {
e->frameno = frameno;
e->is_reg = is_reg;
e->regno = spi_or_reg;
} else {
reg->id = 0;
}
}
/* For all R being scalar registers or spilled scalar registers
* in verifier state, save R in linked_regs if R->id == id.
* If there are too many Rs sharing same id, reset id for leftover Rs.
*/
static void collect_linked_regs(struct bpf_verifier_state *vstate, u32 id,
struct linked_regs *linked_regs)
{
struct bpf_func_state *func;
struct bpf_reg_state *reg;
int i, j;
id = id & ~BPF_ADD_CONST;
for (i = vstate->curframe; i >= 0; i--) {
func = vstate->frame[i];
for (j = 0; j < BPF_REG_FP; j++) {
reg = &func->regs[j];
__collect_linked_regs(linked_regs, reg, id, i, j, true);
}
for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) {
if (!is_spilled_reg(&func->stack[j]))
continue;
reg = &func->stack[j].spilled_ptr;
__collect_linked_regs(linked_regs, reg, id, i, j, false);
}
}
}
/* For all R in linked_regs, copy known_reg range into R
* if R->id == known_reg->id.
*/
static void sync_linked_regs(struct bpf_verifier_state *vstate, struct bpf_reg_state *known_reg,
struct linked_regs *linked_regs)
{
struct bpf_reg_state fake_reg;
struct bpf_reg_state *reg;
struct linked_reg *e;
int i;
for (i = 0; i < linked_regs->cnt; ++i) {
e = &linked_regs->entries[i];
reg = e->is_reg ? &vstate->frame[e->frameno]->regs[e->regno]
: &vstate->frame[e->frameno]->stack[e->spi].spilled_ptr;
if (reg->type != SCALAR_VALUE || reg == known_reg)
continue;
if ((reg->id & ~BPF_ADD_CONST) != (known_reg->id & ~BPF_ADD_CONST))
continue;
if ((!(reg->id & BPF_ADD_CONST) && !(known_reg->id & BPF_ADD_CONST)) ||
reg->off == known_reg->off) {
copy_register_state(reg, known_reg);
} else {
s32 saved_off = reg->off;
fake_reg.type = SCALAR_VALUE;
__mark_reg_known(&fake_reg, (s32)reg->off - (s32)known_reg->off);
/* reg = known_reg; reg += delta */
copy_register_state(reg, known_reg);
/*
* Must preserve off, id and add_const flag,
* otherwise another sync_linked_regs() will be incorrect.
*/
reg->off = saved_off;
scalar32_min_max_add(reg, &fake_reg);
scalar_min_max_add(reg, &fake_reg);
reg->var_off = tnum_add(reg->var_off, fake_reg.var_off);
}
}
}
static int check_cond_jmp_op(struct bpf_verifier_env *env,
struct bpf_insn *insn, int *insn_idx)
{
struct bpf_verifier_state *this_branch = env->cur_state;
struct bpf_verifier_state *other_branch;
struct bpf_reg_state *regs = this_branch->frame[this_branch->curframe]->regs;
struct bpf_reg_state *dst_reg, *other_branch_regs, *src_reg = NULL;
struct bpf_reg_state *eq_branch_regs;
struct linked_regs linked_regs = {};
u8 opcode = BPF_OP(insn->code);
bool is_jmp32;
int pred = -1;
int err;
/* Only conditional jumps are expected to reach here. */
if (opcode == BPF_JA || opcode > BPF_JCOND) {
verbose(env, "invalid BPF_JMP/JMP32 opcode %x\n", opcode);
return -EINVAL;
}
if (opcode == BPF_JCOND) {
struct bpf_verifier_state *cur_st = env->cur_state, *queued_st, *prev_st;
int idx = *insn_idx;
if (insn->code != (BPF_JMP | BPF_JCOND) ||
insn->src_reg != BPF_MAY_GOTO ||
insn->dst_reg || insn->imm || insn->off == 0) {
verbose(env, "invalid may_goto off %d imm %d\n",
insn->off, insn->imm);
return -EINVAL;
}
prev_st = find_prev_entry(env, cur_st->parent, idx);
/* branch out 'fallthrough' insn as a new state to explore */
queued_st = push_stack(env, idx + 1, idx, false);
if (!queued_st)
return -ENOMEM;
queued_st->may_goto_depth++;
if (prev_st)
widen_imprecise_scalars(env, prev_st, queued_st);
*insn_idx += insn->off;
return 0;
}
/* check src2 operand */
err = check_reg_arg(env, insn->dst_reg, SRC_OP);
if (err)
return err;
dst_reg = ®s[insn->dst_reg];
if (BPF_SRC(insn->code) == BPF_X) {
if (insn->imm != 0) {
verbose(env, "BPF_JMP/JMP32 uses reserved fields\n");
return -EINVAL;
}
/* check src1 operand */
err = check_reg_arg(env, insn->src_reg, SRC_OP);
if (err)
return err;
src_reg = ®s[insn->src_reg];
if (!(reg_is_pkt_pointer_any(dst_reg) && reg_is_pkt_pointer_any(src_reg)) &&
is_pointer_value(env, insn->src_reg)) {
verbose(env, "R%d pointer comparison prohibited\n",
insn->src_reg);
return -EACCES;
}
} else {
if (insn->src_reg != BPF_REG_0) {
verbose(env, "BPF_JMP/JMP32 uses reserved fields\n");
return -EINVAL;
}
src_reg = &env->fake_reg[0];
memset(src_reg, 0, sizeof(*src_reg));
src_reg->type = SCALAR_VALUE;
__mark_reg_known(src_reg, insn->imm);
}
is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
pred = is_branch_taken(dst_reg, src_reg, opcode, is_jmp32);
if (pred >= 0) {
/* If we get here with a dst_reg pointer type it is because
* above is_branch_taken() special cased the 0 comparison.
*/
if (!__is_pointer_value(false, dst_reg))
err = mark_chain_precision(env, insn->dst_reg);
if (BPF_SRC(insn->code) == BPF_X && !err &&
!__is_pointer_value(false, src_reg))
err = mark_chain_precision(env, insn->src_reg);
if (err)
return err;
}
if (pred == 1) {
/* Only follow the goto, ignore fall-through. If needed, push
* the fall-through branch for simulation under speculative
* execution.
*/
if (!env->bypass_spec_v1 &&
!sanitize_speculative_path(env, insn, *insn_idx + 1,
*insn_idx))
return -EFAULT;
if (env->log.level & BPF_LOG_LEVEL)
print_insn_state(env, this_branch->frame[this_branch->curframe]);
*insn_idx += insn->off;
return 0;
} else if (pred == 0) {
/* Only follow the fall-through branch, since that's where the
* program will go. If needed, push the goto branch for
* simulation under speculative execution.
*/
if (!env->bypass_spec_v1 &&
!sanitize_speculative_path(env, insn,
*insn_idx + insn->off + 1,
*insn_idx))
return -EFAULT;
if (env->log.level & BPF_LOG_LEVEL)
print_insn_state(env, this_branch->frame[this_branch->curframe]);
return 0;
}
/* Push scalar registers sharing same ID to jump history,
* do this before creating 'other_branch', so that both
* 'this_branch' and 'other_branch' share this history
* if parent state is created.
*/
if (BPF_SRC(insn->code) == BPF_X && src_reg->type == SCALAR_VALUE && src_reg->id)
collect_linked_regs(this_branch, src_reg->id, &linked_regs);
if (dst_reg->type == SCALAR_VALUE && dst_reg->id)
collect_linked_regs(this_branch, dst_reg->id, &linked_regs);
if (linked_regs.cnt > 1) {
err = push_jmp_history(env, this_branch, 0, linked_regs_pack(&linked_regs));
if (err)
return err;
}
other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx,
false);
if (!other_branch)
return -EFAULT;
other_branch_regs = other_branch->frame[other_branch->curframe]->regs;
if (BPF_SRC(insn->code) == BPF_X) {
err = reg_set_min_max(env,
&other_branch_regs[insn->dst_reg],
&other_branch_regs[insn->src_reg],
dst_reg, src_reg, opcode, is_jmp32);
} else /* BPF_SRC(insn->code) == BPF_K */ {
/* reg_set_min_max() can mangle the fake_reg. Make a copy
* so that these are two different memory locations. The
* src_reg is not used beyond here in context of K.
*/
memcpy(&env->fake_reg[1], &env->fake_reg[0],
sizeof(env->fake_reg[0]));
err = reg_set_min_max(env,
&other_branch_regs[insn->dst_reg],
&env->fake_reg[0],
dst_reg, &env->fake_reg[1],
opcode, is_jmp32);
}
if (err)
return err;
if (BPF_SRC(insn->code) == BPF_X &&
src_reg->type == SCALAR_VALUE && src_reg->id &&
!WARN_ON_ONCE(src_reg->id != other_branch_regs[insn->src_reg].id)) {
sync_linked_regs(this_branch, src_reg, &linked_regs);
sync_linked_regs(other_branch, &other_branch_regs[insn->src_reg], &linked_regs);
}
if (dst_reg->type == SCALAR_VALUE && dst_reg->id &&
!WARN_ON_ONCE(dst_reg->id != other_branch_regs[insn->dst_reg].id)) {
sync_linked_regs(this_branch, dst_reg, &linked_regs);
sync_linked_regs(other_branch, &other_branch_regs[insn->dst_reg], &linked_regs);
}
/* if one pointer register is compared to another pointer
* register check if PTR_MAYBE_NULL could be lifted.
* E.g. register A - maybe null
* register B - not null
* for JNE A, B, ... - A is not null in the false branch;
* for JEQ A, B, ... - A is not null in the true branch.
*
* Since PTR_TO_BTF_ID points to a kernel struct that does
* not need to be null checked by the BPF program, i.e.,
* could be null even without PTR_MAYBE_NULL marking, so
* only propagate nullness when neither reg is that type.
*/
if (!is_jmp32 && BPF_SRC(insn->code) == BPF_X &&
__is_pointer_value(false, src_reg) && __is_pointer_value(false, dst_reg) &&
type_may_be_null(src_reg->type) != type_may_be_null(dst_reg->type) &&
base_type(src_reg->type) != PTR_TO_BTF_ID &&
base_type(dst_reg->type) != PTR_TO_BTF_ID) {
eq_branch_regs = NULL;
switch (opcode) {
case BPF_JEQ:
eq_branch_regs = other_branch_regs;
break;
case BPF_JNE:
eq_branch_regs = regs;
break;
default:
/* do nothing */
break;
}
if (eq_branch_regs) {
if (type_may_be_null(src_reg->type))
mark_ptr_not_null_reg(&eq_branch_regs[insn->src_reg]);
else
mark_ptr_not_null_reg(&eq_branch_regs[insn->dst_reg]);
}
}
/* detect if R == 0 where R is returned from bpf_map_lookup_elem().
* NOTE: these optimizations below are related with pointer comparison
* which will never be JMP32.
*/
if (!is_jmp32 && BPF_SRC(insn->code) == BPF_K &&
insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
type_may_be_null(dst_reg->type)) {
/* Mark all identical registers in each branch as either
* safe or unknown depending R == 0 or R != 0 conditional.
*/
mark_ptr_or_null_regs(this_branch, insn->dst_reg,
opcode == BPF_JNE);
mark_ptr_or_null_regs(other_branch, insn->dst_reg,
opcode == BPF_JEQ);
} else if (!try_match_pkt_pointers(insn, dst_reg, ®s[insn->src_reg],
this_branch, other_branch) &&
is_pointer_value(env, insn->dst_reg)) {
verbose(env, "R%d pointer comparison prohibited\n",
insn->dst_reg);
return -EACCES;
}
if (env->log.level & BPF_LOG_LEVEL)
print_insn_state(env, this_branch->frame[this_branch->curframe]);
return 0;
}
/* verify BPF_LD_IMM64 instruction */
static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
struct bpf_insn_aux_data *aux = cur_aux(env);
struct bpf_reg_state *regs = cur_regs(env);
struct bpf_reg_state *dst_reg;
struct bpf_map *map;
int err;
if (BPF_SIZE(insn->code) != BPF_DW) {
verbose(env, "invalid BPF_LD_IMM insn\n");
return -EINVAL;
}
if (insn->off != 0) {
verbose(env, "BPF_LD_IMM64 uses reserved fields\n");
return -EINVAL;
}
err = check_reg_arg(env, insn->dst_reg, DST_OP);
if (err)
return err;
dst_reg = ®s[insn->dst_reg];
if (insn->src_reg == 0) {
u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
dst_reg->type = SCALAR_VALUE;
__mark_reg_known(®s[insn->dst_reg], imm);
return 0;
}
/* All special src_reg cases are listed below. From this point onwards
* we either succeed and assign a corresponding dst_reg->type after
* zeroing the offset, or fail and reject the program.
*/
mark_reg_known_zero(env, regs, insn->dst_reg);
if (insn->src_reg == BPF_PSEUDO_BTF_ID) {
dst_reg->type = aux->btf_var.reg_type;
switch (base_type(dst_reg->type)) {
case PTR_TO_MEM:
dst_reg->mem_size = aux->btf_var.mem_size;
break;
case PTR_TO_BTF_ID:
dst_reg->btf = aux->btf_var.btf;
dst_reg->btf_id = aux->btf_var.btf_id;
break;
default:
verbose(env, "bpf verifier is misconfigured\n");
return -EFAULT;
}
return 0;
}
if (insn->src_reg == BPF_PSEUDO_FUNC) {
struct bpf_prog_aux *aux = env->prog->aux;
u32 subprogno = find_subprog(env,
env->insn_idx + insn->imm + 1);
if (!aux->func_info) {
verbose(env, "missing btf func_info\n");
return -EINVAL;
}
if (aux->func_info_aux[subprogno].linkage != BTF_FUNC_STATIC) {
verbose(env, "callback function not static\n");
return -EINVAL;
}
dst_reg->type = PTR_TO_FUNC;
dst_reg->subprogno = subprogno;
return 0;
}
map = env->used_maps[aux->map_index];
dst_reg->map_ptr = map;
if (insn->src_reg == BPF_PSEUDO_MAP_VALUE ||
insn->src_reg == BPF_PSEUDO_MAP_IDX_VALUE) {
if (map->map_type == BPF_MAP_TYPE_ARENA) {
__mark_reg_unknown(env, dst_reg);
return 0;
}
dst_reg->type = PTR_TO_MAP_VALUE;
dst_reg->off = aux->map_off;
WARN_ON_ONCE(map->max_entries != 1);
/* We want reg->id to be same (0) as map_value is not distinct */
} else if (insn->src_reg == BPF_PSEUDO_MAP_FD ||
insn->src_reg == BPF_PSEUDO_MAP_IDX) {
dst_reg->type = CONST_PTR_TO_MAP;
} else {
verbose(env, "bpf verifier is misconfigured\n");
return -EINVAL;
}
return 0;
}
static bool may_access_skb(enum bpf_prog_type type)
{
switch (type) {
case BPF_PROG_TYPE_SOCKET_FILTER:
case BPF_PROG_TYPE_SCHED_CLS:
case BPF_PROG_TYPE_SCHED_ACT:
return true;
default:
return false;
}
}
/* verify safety of LD_ABS|LD_IND instructions:
* - they can only appear in the programs where ctx == skb
* - since they are wrappers of function calls, they scratch R1-R5 registers,
* preserve R6-R9, and store return value into R0
*
* Implicit input:
* ctx == skb == R6 == CTX
*
* Explicit input:
* SRC == any register
* IMM == 32-bit immediate
*
* Output:
* R0 - 8/16/32-bit skb data converted to cpu endianness
*/
static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
struct bpf_reg_state *regs = cur_regs(env);
static const int ctx_reg = BPF_REG_6;
u8 mode = BPF_MODE(insn->code);
int i, err;
if (!may_access_skb(resolve_prog_type(env->prog))) {
verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
return -EINVAL;
}
if (!env->ops->gen_ld_abs) {
verbose(env, "bpf verifier is misconfigured\n");
return -EINVAL;
}
if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
BPF_SIZE(insn->code) == BPF_DW ||
(mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
verbose(env, "BPF_LD_[ABS|IND] uses reserved fields\n");
return -EINVAL;
}
/* check whether implicit source operand (register R6) is readable */
err = check_reg_arg(env, ctx_reg, SRC_OP);
if (err)
return err;
/* Disallow usage of BPF_LD_[ABS|IND] with reference tracking, as
* gen_ld_abs() may terminate the program at runtime, leading to
* reference leak.
*/
err = check_reference_leak(env, false);
if (err) {
verbose(env, "BPF_LD_[ABS|IND] cannot be mixed with socket references\n");
return err;
}
if (env->cur_state->active_lock.ptr) {
verbose(env, "BPF_LD_[ABS|IND] cannot be used inside bpf_spin_lock-ed region\n");
return -EINVAL;
}
if (env->cur_state->active_rcu_lock) {
verbose(env, "BPF_LD_[ABS|IND] cannot be used inside bpf_rcu_read_lock-ed region\n");
return -EINVAL;
}
if (env->cur_state->active_preempt_lock) {
verbose(env, "BPF_LD_[ABS|IND] cannot be used inside bpf_preempt_disable-ed region\n");
return -EINVAL;
}
if (regs[ctx_reg].type != PTR_TO_CTX) {
verbose(env,
"at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
return -EINVAL;
}
if (mode == BPF_IND) {
/* check explicit source operand */
err = check_reg_arg(env, insn->src_reg, SRC_OP);
if (err)
return err;
}
err = check_ptr_off_reg(env, ®s[ctx_reg], ctx_reg);
if (err < 0)
return err;
/* reset caller saved regs to unreadable */
for (i = 0; i < CALLER_SAVED_REGS; i++) {
mark_reg_not_init(env, regs, caller_saved[i]);
check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
}
/* mark destination R0 register as readable, since it contains
* the value fetched from the packet.
* Already marked as written above.
*/
mark_reg_unknown(env, regs, BPF_REG_0);
/* ld_abs load up to 32-bit skb data. */
regs[BPF_REG_0].subreg_def = env->insn_idx + 1;
return 0;
}
static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name)
{
const char *exit_ctx = "At program exit";
struct tnum enforce_attach_type_range = tnum_unknown;
const struct bpf_prog *prog = env->prog;
struct bpf_reg_state *reg;
struct bpf_retval_range range = retval_range(0, 1);
enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
int err;
struct bpf_func_state *frame = env->cur_state->frame[0];
const bool is_subprog = frame->subprogno;
bool return_32bit = false;
/* LSM and struct_ops func-ptr's return type could be "void" */
if (!is_subprog || frame->in_exception_callback_fn) {
switch (prog_type) {
case BPF_PROG_TYPE_LSM:
if (prog->expected_attach_type == BPF_LSM_CGROUP)
/* See below, can be 0 or 0-1 depending on hook. */
break;
fallthrough;
case BPF_PROG_TYPE_STRUCT_OPS:
if (!prog->aux->attach_func_proto->type)
return 0;
break;
default:
break;
}
}
/* eBPF calling convention is such that R0 is used
* to return the value from eBPF program.
* Make sure that it's readable at this time
* of bpf_exit, which means that program wrote
* something into it earlier
*/
err = check_reg_arg(env, regno, SRC_OP);
if (err)
return err;
if (is_pointer_value(env, regno)) {
verbose(env, "R%d leaks addr as return value\n", regno);
return -EACCES;
}
reg = cur_regs(env) + regno;
if (frame->in_async_callback_fn) {
/* enforce return zero from async callbacks like timer */
exit_ctx = "At async callback return";
range = retval_range(0, 0);
goto enforce_retval;
}
if (is_subprog && !frame->in_exception_callback_fn) {
if (reg->type != SCALAR_VALUE) {
verbose(env, "At subprogram exit the register R%d is not a scalar value (%s)\n",
regno, reg_type_str(env, reg->type));
return -EINVAL;
}
return 0;
}
switch (prog_type) {
case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG ||
env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG ||
env->prog->expected_attach_type == BPF_CGROUP_UNIX_RECVMSG ||
env->prog->expected_attach_type == BPF_CGROUP_INET4_GETPEERNAME ||
env->prog->expected_attach_type == BPF_CGROUP_INET6_GETPEERNAME ||
env->prog->expected_attach_type == BPF_CGROUP_UNIX_GETPEERNAME ||
env->prog->expected_attach_type == BPF_CGROUP_INET4_GETSOCKNAME ||
env->prog->expected_attach_type == BPF_CGROUP_INET6_GETSOCKNAME ||
env->prog->expected_attach_type == BPF_CGROUP_UNIX_GETSOCKNAME)
range = retval_range(1, 1);
if (env->prog->expected_attach_type == BPF_CGROUP_INET4_BIND ||
env->prog->expected_attach_type == BPF_CGROUP_INET6_BIND)
range = retval_range(0, 3);
break;
case BPF_PROG_TYPE_CGROUP_SKB:
if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) {
range = retval_range(0, 3);
enforce_attach_type_range = tnum_range(2, 3);
}
break;
case BPF_PROG_TYPE_CGROUP_SOCK:
case BPF_PROG_TYPE_SOCK_OPS:
case BPF_PROG_TYPE_CGROUP_DEVICE:
case BPF_PROG_TYPE_CGROUP_SYSCTL:
case BPF_PROG_TYPE_CGROUP_SOCKOPT:
break;
case BPF_PROG_TYPE_RAW_TRACEPOINT:
if (!env->prog->aux->attach_btf_id)
return 0;
range = retval_range(0, 0);
break;
case BPF_PROG_TYPE_TRACING:
switch (env->prog->expected_attach_type) {
case BPF_TRACE_FENTRY:
case BPF_TRACE_FEXIT:
range = retval_range(0, 0);
break;
case BPF_TRACE_RAW_TP:
case BPF_MODIFY_RETURN:
return 0;
case BPF_TRACE_ITER:
break;
default:
return -ENOTSUPP;
}
break;
case BPF_PROG_TYPE_SK_LOOKUP:
range = retval_range(SK_DROP, SK_PASS);
break;
case BPF_PROG_TYPE_LSM:
if (env->prog->expected_attach_type != BPF_LSM_CGROUP) {
/* no range found, any return value is allowed */
if (!get_func_retval_range(env->prog, &range))
return 0;
/* no restricted range, any return value is allowed */
if (range.minval == S32_MIN && range.maxval == S32_MAX)
return 0;
return_32bit = true;
} else if (!env->prog->aux->attach_func_proto->type) {
/* Make sure programs that attach to void
* hooks don't try to modify return value.
*/
range = retval_range(1, 1);
}
break;
case BPF_PROG_TYPE_NETFILTER:
range = retval_range(NF_DROP, NF_ACCEPT);
break;
case BPF_PROG_TYPE_EXT:
/* freplace program can return anything as its return value
* depends on the to-be-replaced kernel func or bpf program.
*/
default:
return 0;
}
enforce_retval:
if (reg->type != SCALAR_VALUE) {
verbose(env, "%s the register R%d is not a known value (%s)\n",
exit_ctx, regno, reg_type_str(env, reg->type));
return -EINVAL;
}
err = mark_chain_precision(env, regno);
if (err)
return err;
if (!retval_range_within(range, reg, return_32bit)) {
verbose_invalid_scalar(env, reg, range, exit_ctx, reg_name);
if (!is_subprog &&
prog->expected_attach_type == BPF_LSM_CGROUP &&
prog_type == BPF_PROG_TYPE_LSM &&
!prog->aux->attach_func_proto->type)
verbose(env, "Note, BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n");
return -EINVAL;
}
if (!tnum_is_unknown(enforce_attach_type_range) &&
tnum_in(enforce_attach_type_range, reg->var_off))
env->prog->enforce_expected_attach_type = 1;
return 0;
}
/* non-recursive DFS pseudo code
* 1 procedure DFS-iterative(G,v):
* 2 label v as discovered
* 3 let S be a stack
* 4 S.push(v)
* 5 while S is not empty
* 6 t <- S.peek()
* 7 if t is what we're looking for:
* 8 return t
* 9 for all edges e in G.adjacentEdges(t) do
* 10 if edge e is already labelled
* 11 continue with the next edge
* 12 w <- G.adjacentVertex(t,e)
* 13 if vertex w is not discovered and not explored
* 14 label e as tree-edge
* 15 label w as discovered
* 16 S.push(w)
* 17 continue at 5
* 18 else if vertex w is discovered
* 19 label e as back-edge
* 20 else
* 21 // vertex w is explored
* 22 label e as forward- or cross-edge
* 23 label t as explored
* 24 S.pop()
*
* convention:
* 0x10 - discovered
* 0x11 - discovered and fall-through edge labelled
* 0x12 - discovered and fall-through and branch edges labelled
* 0x20 - explored
*/
enum {
DISCOVERED = 0x10,
EXPLORED = 0x20,
FALLTHROUGH = 1,
BRANCH = 2,
};
static void mark_prune_point(struct bpf_verifier_env *env, int idx)
{
env->insn_aux_data[idx].prune_point = true;
}
static bool is_prune_point(struct bpf_verifier_env *env, int insn_idx)
{
return env->insn_aux_data[insn_idx].prune_point;
}
static void mark_force_checkpoint(struct bpf_verifier_env *env, int idx)
{
env->insn_aux_data[idx].force_checkpoint = true;
}
static bool is_force_checkpoint(struct bpf_verifier_env *env, int insn_idx)
{
return env->insn_aux_data[insn_idx].force_checkpoint;
}
static void mark_calls_callback(struct bpf_verifier_env *env, int idx)
{
env->insn_aux_data[idx].calls_callback = true;
}
static bool calls_callback(struct bpf_verifier_env *env, int insn_idx)
{
return env->insn_aux_data[insn_idx].calls_callback;
}
enum {
DONE_EXPLORING = 0,
KEEP_EXPLORING = 1,
};
/* t, w, e - match pseudo-code above:
* t - index of current instruction
* w - next instruction
* e - edge
*/
static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
{
int *insn_stack = env->cfg.insn_stack;
int *insn_state = env->cfg.insn_state;
if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
return DONE_EXPLORING;
if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
return DONE_EXPLORING;
if (w < 0 || w >= env->prog->len) {
verbose_linfo(env, t, "%d: ", t);
verbose(env, "jump out of range from insn %d to %d\n", t, w);
return -EINVAL;
}
if (e == BRANCH) {
/* mark branch target for state pruning */
mark_prune_point(env, w);
mark_jmp_point(env, w);
}
if (insn_state[w] == 0) {
/* tree-edge */
insn_state[t] = DISCOVERED | e;
insn_state[w] = DISCOVERED;
if (env->cfg.cur_stack >= env->prog->len)
return -E2BIG;
insn_stack[env->cfg.cur_stack++] = w;
return KEEP_EXPLORING;
} else if ((insn_state[w] & 0xF0) == DISCOVERED) {
if (env->bpf_capable)
return DONE_EXPLORING;
verbose_linfo(env, t, "%d: ", t);
verbose_linfo(env, w, "%d: ", w);
verbose(env, "back-edge from insn %d to %d\n", t, w);
return -EINVAL;
} else if (insn_state[w] == EXPLORED) {
/* forward- or cross-edge */
insn_state[t] = DISCOVERED | e;
} else {
verbose(env, "insn state internal bug\n");
return -EFAULT;
}
return DONE_EXPLORING;
}
static int visit_func_call_insn(int t, struct bpf_insn *insns,
struct bpf_verifier_env *env,
bool visit_callee)
{
int ret, insn_sz;
insn_sz = bpf_is_ldimm64(&insns[t]) ? 2 : 1;
ret = push_insn(t, t + insn_sz, FALLTHROUGH, env);
if (ret)
return ret;
mark_prune_point(env, t + insn_sz);
/* when we exit from subprog, we need to record non-linear history */
mark_jmp_point(env, t + insn_sz);
if (visit_callee) {
mark_prune_point(env, t);
ret = push_insn(t, t + insns[t].imm + 1, BRANCH, env);
}
return ret;
}
/* Bitmask with 1s for all caller saved registers */
#define ALL_CALLER_SAVED_REGS ((1u << CALLER_SAVED_REGS) - 1)
/* Return a bitmask specifying which caller saved registers are
* clobbered by a call to a helper *as if* this helper follows
* bpf_fastcall contract:
* - includes R0 if function is non-void;
* - includes R1-R5 if corresponding parameter has is described
* in the function prototype.
*/
static u32 helper_fastcall_clobber_mask(const struct bpf_func_proto *fn)
{
u32 mask;
int i;
mask = 0;
if (fn->ret_type != RET_VOID)
mask |= BIT(BPF_REG_0);
for (i = 0; i < ARRAY_SIZE(fn->arg_type); ++i)
if (fn->arg_type[i] != ARG_DONTCARE)
mask |= BIT(BPF_REG_1 + i);
return mask;
}
/* True if do_misc_fixups() replaces calls to helper number 'imm',
* replacement patch is presumed to follow bpf_fastcall contract
* (see mark_fastcall_pattern_for_call() below).
*/
static bool verifier_inlines_helper_call(struct bpf_verifier_env *env, s32 imm)
{
switch (imm) {
#ifdef CONFIG_X86_64
case BPF_FUNC_get_smp_processor_id:
return env->prog->jit_requested && bpf_jit_supports_percpu_insn();
#endif
default:
return false;
}
}
/* Same as helper_fastcall_clobber_mask() but for kfuncs, see comment above */
static u32 kfunc_fastcall_clobber_mask(struct bpf_kfunc_call_arg_meta *meta)
{
u32 vlen, i, mask;
vlen = btf_type_vlen(meta->func_proto);
mask = 0;
if (!btf_type_is_void(btf_type_by_id(meta->btf, meta->func_proto->type)))
mask |= BIT(BPF_REG_0);
for (i = 0; i < vlen; ++i)
mask |= BIT(BPF_REG_1 + i);
return mask;
}
/* Same as verifier_inlines_helper_call() but for kfuncs, see comment above */
static bool is_fastcall_kfunc_call(struct bpf_kfunc_call_arg_meta *meta)
{
if (meta->btf == btf_vmlinux)
return meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx] ||
meta->func_id == special_kfunc_list[KF_bpf_rdonly_cast];
return false;
}
/* LLVM define a bpf_fastcall function attribute.
* This attribute means that function scratches only some of
* the caller saved registers defined by ABI.
* For BPF the set of such registers could be defined as follows:
* - R0 is scratched only if function is non-void;
* - R1-R5 are scratched only if corresponding parameter type is defined
* in the function prototype.
*
* The contract between kernel and clang allows to simultaneously use
* such functions and maintain backwards compatibility with old
* kernels that don't understand bpf_fastcall calls:
*
* - for bpf_fastcall calls clang allocates registers as-if relevant r0-r5
* registers are not scratched by the call;
*
* - as a post-processing step, clang visits each bpf_fastcall call and adds
* spill/fill for every live r0-r5;
*
* - stack offsets used for the spill/fill are allocated as lowest
* stack offsets in whole function and are not used for any other
* purposes;
*
* - when kernel loads a program, it looks for such patterns
* (bpf_fastcall function surrounded by spills/fills) and checks if
* spill/fill stack offsets are used exclusively in fastcall patterns;
*
* - if so, and if verifier or current JIT inlines the call to the
* bpf_fastcall function (e.g. a helper call), kernel removes unnecessary
* spill/fill pairs;
*
* - when old kernel loads a program, presence of spill/fill pairs
* keeps BPF program valid, albeit slightly less efficient.
*
* For example:
*
* r1 = 1;
* r2 = 2;
* *(u64 *)(r10 - 8) = r1; r1 = 1;
* *(u64 *)(r10 - 16) = r2; r2 = 2;
* call %[to_be_inlined] --> call %[to_be_inlined]
* r2 = *(u64 *)(r10 - 16); r0 = r1;
* r1 = *(u64 *)(r10 - 8); r0 += r2;
* r0 = r1; exit;
* r0 += r2;
* exit;
*
* The purpose of mark_fastcall_pattern_for_call is to:
* - look for such patterns;
* - mark spill and fill instructions in env->insn_aux_data[*].fastcall_pattern;
* - mark set env->insn_aux_data[*].fastcall_spills_num for call instruction;
* - update env->subprog_info[*]->fastcall_stack_off to find an offset
* at which bpf_fastcall spill/fill stack slots start;
* - update env->subprog_info[*]->keep_fastcall_stack.
*
* The .fastcall_pattern and .fastcall_stack_off are used by
* check_fastcall_stack_contract() to check if every stack access to
* fastcall spill/fill stack slot originates from spill/fill
* instructions, members of fastcall patterns.
*
* If such condition holds true for a subprogram, fastcall patterns could
* be rewritten by remove_fastcall_spills_fills().
* Otherwise bpf_fastcall patterns are not changed in the subprogram
* (code, presumably, generated by an older clang version).
*
* For example, it is *not* safe to remove spill/fill below:
*
* r1 = 1;
* *(u64 *)(r10 - 8) = r1; r1 = 1;
* call %[to_be_inlined] --> call %[to_be_inlined]
* r1 = *(u64 *)(r10 - 8); r0 = *(u64 *)(r10 - 8); <---- wrong !!!
* r0 = *(u64 *)(r10 - 8); r0 += r1;
* r0 += r1; exit;
* exit;
*/
static void mark_fastcall_pattern_for_call(struct bpf_verifier_env *env,
struct bpf_subprog_info *subprog,
int insn_idx, s16 lowest_off)
{
struct bpf_insn *insns = env->prog->insnsi, *stx, *ldx;
struct bpf_insn *call = &env->prog->insnsi[insn_idx];
const struct bpf_func_proto *fn;
u32 clobbered_regs_mask = ALL_CALLER_SAVED_REGS;
u32 expected_regs_mask;
bool can_be_inlined = false;
s16 off;
int i;
if (bpf_helper_call(call)) {
if (get_helper_proto(env, call->imm, &fn) < 0)
/* error would be reported later */
return;
clobbered_regs_mask = helper_fastcall_clobber_mask(fn);
can_be_inlined = fn->allow_fastcall &&
(verifier_inlines_helper_call(env, call->imm) ||
bpf_jit_inlines_helper_call(call->imm));
}
if (bpf_pseudo_kfunc_call(call)) {
struct bpf_kfunc_call_arg_meta meta;
int err;
err = fetch_kfunc_meta(env, call, &meta, NULL);
if (err < 0)
/* error would be reported later */
return;
clobbered_regs_mask = kfunc_fastcall_clobber_mask(&meta);
can_be_inlined = is_fastcall_kfunc_call(&meta);
}
if (clobbered_regs_mask == ALL_CALLER_SAVED_REGS)
return;
/* e.g. if helper call clobbers r{0,1}, expect r{2,3,4,5} in the pattern */
expected_regs_mask = ~clobbered_regs_mask & ALL_CALLER_SAVED_REGS;
/* match pairs of form:
*
* *(u64 *)(r10 - Y) = rX (where Y % 8 == 0)
* ...
* call %[to_be_inlined]
* ...
* rX = *(u64 *)(r10 - Y)
*/
for (i = 1, off = lowest_off; i <= ARRAY_SIZE(caller_saved); ++i, off += BPF_REG_SIZE) {
if (insn_idx - i < 0 || insn_idx + i >= env->prog->len)
break;
stx = &insns[insn_idx - i];
ldx = &insns[insn_idx + i];
/* must be a stack spill/fill pair */
if (stx->code != (BPF_STX | BPF_MEM | BPF_DW) ||
ldx->code != (BPF_LDX | BPF_MEM | BPF_DW) ||
stx->dst_reg != BPF_REG_10 ||
ldx->src_reg != BPF_REG_10)
break;
/* must be a spill/fill for the same reg */
if (stx->src_reg != ldx->dst_reg)
break;
/* must be one of the previously unseen registers */
if ((BIT(stx->src_reg) & expected_regs_mask) == 0)
break;
/* must be a spill/fill for the same expected offset,
* no need to check offset alignment, BPF_DW stack access
* is always 8-byte aligned.
*/
if (stx->off != off || ldx->off != off)
break;
expected_regs_mask &= ~BIT(stx->src_reg);
env->insn_aux_data[insn_idx - i].fastcall_pattern = 1;
env->insn_aux_data[insn_idx + i].fastcall_pattern = 1;
}
if (i == 1)
return;
/* Conditionally set 'fastcall_spills_num' to allow forward
* compatibility when more helper functions are marked as
* bpf_fastcall at compile time than current kernel supports, e.g:
*
* 1: *(u64 *)(r10 - 8) = r1
* 2: call A ;; assume A is bpf_fastcall for current kernel
* 3: r1 = *(u64 *)(r10 - 8)
* 4: *(u64 *)(r10 - 8) = r1
* 5: call B ;; assume B is not bpf_fastcall for current kernel
* 6: r1 = *(u64 *)(r10 - 8)
*
* There is no need to block bpf_fastcall rewrite for such program.
* Set 'fastcall_pattern' for both calls to keep check_fastcall_stack_contract() happy,
* don't set 'fastcall_spills_num' for call B so that remove_fastcall_spills_fills()
* does not remove spill/fill pair {4,6}.
*/
if (can_be_inlined)
env->insn_aux_data[insn_idx].fastcall_spills_num = i - 1;
else
subprog->keep_fastcall_stack = 1;
subprog->fastcall_stack_off = min(subprog->fastcall_stack_off, off);
}
static int mark_fastcall_patterns(struct bpf_verifier_env *env)
{
struct bpf_subprog_info *subprog = env->subprog_info;
struct bpf_insn *insn;
s16 lowest_off;
int s, i;
for (s = 0; s < env->subprog_cnt; ++s, ++subprog) {
/* find lowest stack spill offset used in this subprog */
lowest_off = 0;
for (i = subprog->start; i < (subprog + 1)->start; ++i) {
insn = env->prog->insnsi + i;
if (insn->code != (BPF_STX | BPF_MEM | BPF_DW) ||
insn->dst_reg != BPF_REG_10)
continue;
lowest_off = min(lowest_off, insn->off);
}
/* use this offset to find fastcall patterns */
for (i = subprog->start; i < (subprog + 1)->start; ++i) {
insn = env->prog->insnsi + i;
if (insn->code != (BPF_JMP | BPF_CALL))
continue;
mark_fastcall_pattern_for_call(env, subprog, i, lowest_off);
}
}
return 0;
}
/* Visits the instruction at index t and returns one of the following:
* < 0 - an error occurred
* DONE_EXPLORING - the instruction was fully explored
* KEEP_EXPLORING - there is still work to be done before it is fully explored
*/
static int visit_insn(int t, struct bpf_verifier_env *env)
{
struct bpf_insn *insns = env->prog->insnsi, *insn = &insns[t];
int ret, off, insn_sz;
if (bpf_pseudo_func(insn))
return visit_func_call_insn(t, insns, env, true);
/* All non-branch instructions have a single fall-through edge. */
if (BPF_CLASS(insn->code) != BPF_JMP &&
BPF_CLASS(insn->code) != BPF_JMP32) {
insn_sz = bpf_is_ldimm64(insn) ? 2 : 1;
return push_insn(t, t + insn_sz, FALLTHROUGH, env);
}
switch (BPF_OP(insn->code)) {
case BPF_EXIT:
return DONE_EXPLORING;
case BPF_CALL:
if (is_async_callback_calling_insn(insn))
/* Mark this call insn as a prune point to trigger
* is_state_visited() check before call itself is
* processed by __check_func_call(). Otherwise new
* async state will be pushed for further exploration.
*/
mark_prune_point(env, t);
/* For functions that invoke callbacks it is not known how many times
* callback would be called. Verifier models callback calling functions
* by repeatedly visiting callback bodies and returning to origin call
* instruction.
* In order to stop such iteration verifier needs to identify when a
* state identical some state from a previous iteration is reached.
* Check below forces creation of checkpoint before callback calling
* instruction to allow search for such identical states.
*/
if (is_sync_callback_calling_insn(insn)) {
mark_calls_callback(env, t);
mark_force_checkpoint(env, t);
mark_prune_point(env, t);
mark_jmp_point(env, t);
}
if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) {
struct bpf_kfunc_call_arg_meta meta;
ret = fetch_kfunc_meta(env, insn, &meta, NULL);
if (ret == 0 && is_iter_next_kfunc(&meta)) {
mark_prune_point(env, t);
/* Checking and saving state checkpoints at iter_next() call
* is crucial for fast convergence of open-coded iterator loop
* logic, so we need to force it. If we don't do that,
* is_state_visited() might skip saving a checkpoint, causing
* unnecessarily long sequence of not checkpointed
* instructions and jumps, leading to exhaustion of jump
* history buffer, and potentially other undesired outcomes.
* It is expected that with correct open-coded iterators
* convergence will happen quickly, so we don't run a risk of
* exhausting memory.
*/
mark_force_checkpoint(env, t);
}
}
return visit_func_call_insn(t, insns, env, insn->src_reg == BPF_PSEUDO_CALL);
case BPF_JA:
if (BPF_SRC(insn->code) != BPF_K)
return -EINVAL;
if (BPF_CLASS(insn->code) == BPF_JMP)
off = insn->off;
else
off = insn->imm;
/* unconditional jump with single edge */
ret = push_insn(t, t + off + 1, FALLTHROUGH, env);
if (ret)
return ret;
mark_prune_point(env, t + off + 1);
mark_jmp_point(env, t + off + 1);
return ret;
default:
/* conditional jump with two edges */
mark_prune_point(env, t);
if (is_may_goto_insn(insn))
mark_force_checkpoint(env, t);
ret = push_insn(t, t + 1, FALLTHROUGH, env);
if (ret)
return ret;
return push_insn(t, t + insn->off + 1, BRANCH, env);
}
}
/* non-recursive depth-first-search to detect loops in BPF program
* loop == back-edge in directed graph
*/
static int check_cfg(struct bpf_verifier_env *env)
{
int insn_cnt = env->prog->len;
int *insn_stack, *insn_state;
int ex_insn_beg, i, ret = 0;
bool ex_done = false;
insn_state = env->cfg.insn_state = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
if (!insn_state)
return -ENOMEM;
insn_stack = env->cfg.insn_stack = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
if (!insn_stack) {
kvfree(insn_state);
return -ENOMEM;
}
insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
insn_stack[0] = 0; /* 0 is the first instruction */
env->cfg.cur_stack = 1;
walk_cfg:
while (env->cfg.cur_stack > 0) {
int t = insn_stack[env->cfg.cur_stack - 1];
ret = visit_insn(t, env);
switch (ret) {
case DONE_EXPLORING:
insn_state[t] = EXPLORED;
env->cfg.cur_stack--;
break;
case KEEP_EXPLORING:
break;
default:
if (ret > 0) {
verbose(env, "visit_insn internal bug\n");
ret = -EFAULT;
}
goto err_free;
}
}
if (env->cfg.cur_stack < 0) {
verbose(env, "pop stack internal bug\n");
ret = -EFAULT;
goto err_free;
}
if (env->exception_callback_subprog && !ex_done) {
ex_insn_beg = env->subprog_info[env->exception_callback_subprog].start;
insn_state[ex_insn_beg] = DISCOVERED;
insn_stack[0] = ex_insn_beg;
env->cfg.cur_stack = 1;
ex_done = true;
goto walk_cfg;
}
for (i = 0; i < insn_cnt; i++) {
struct bpf_insn *insn = &env->prog->insnsi[i];
if (insn_state[i] != EXPLORED) {
verbose(env, "unreachable insn %d\n", i);
ret = -EINVAL;
goto err_free;
}
if (bpf_is_ldimm64(insn)) {
if (insn_state[i + 1] != 0) {
verbose(env, "jump into the middle of ldimm64 insn %d\n", i);
ret = -EINVAL;
goto err_free;
}
i++; /* skip second half of ldimm64 */
}
}
ret = 0; /* cfg looks good */
err_free:
kvfree(insn_state);
kvfree(insn_stack);
env->cfg.insn_state = env->cfg.insn_stack = NULL;
return ret;
}
static int check_abnormal_return(struct bpf_verifier_env *env)
{
int i;
for (i = 1; i < env->subprog_cnt; i++) {
if (env->subprog_info[i].has_ld_abs) {
verbose(env, "LD_ABS is not allowed in subprogs without BTF\n");
return -EINVAL;
}
if (env->subprog_info[i].has_tail_call) {
verbose(env, "tail_call is not allowed in subprogs without BTF\n");
return -EINVAL;
}
}
return 0;
}
/* The minimum supported BTF func info size */
#define MIN_BPF_FUNCINFO_SIZE 8
#define MAX_FUNCINFO_REC_SIZE 252
static int check_btf_func_early(struct bpf_verifier_env *env,
const union bpf_attr *attr,
bpfptr_t uattr)
{
u32 krec_size = sizeof(struct bpf_func_info);
const struct btf_type *type, *func_proto;
u32 i, nfuncs, urec_size, min_size;
struct bpf_func_info *krecord;
struct bpf_prog *prog;
const struct btf *btf;
u32 prev_offset = 0;
bpfptr_t urecord;
int ret = -ENOMEM;
nfuncs = attr->func_info_cnt;
if (!nfuncs) {
if (check_abnormal_return(env))
return -EINVAL;
return 0;
}
urec_size = attr->func_info_rec_size;
if (urec_size < MIN_BPF_FUNCINFO_SIZE ||
urec_size > MAX_FUNCINFO_REC_SIZE ||
urec_size % sizeof(u32)) {
verbose(env, "invalid func info rec size %u\n", urec_size);
return -EINVAL;
}
prog = env->prog;
btf = prog->aux->btf;
urecord = make_bpfptr(attr->func_info, uattr.is_kernel);
min_size = min_t(u32, krec_size, urec_size);
krecord = kvcalloc(nfuncs, krec_size, GFP_KERNEL | __GFP_NOWARN);
if (!krecord)
return -ENOMEM;
for (i = 0; i < nfuncs; i++) {
ret = bpf_check_uarg_tail_zero(urecord, krec_size, urec_size);
if (ret) {
if (ret == -E2BIG) {
verbose(env, "nonzero tailing record in func info");
/* set the size kernel expects so loader can zero
* out the rest of the record.
*/
if (copy_to_bpfptr_offset(uattr,
offsetof(union bpf_attr, func_info_rec_size),
&min_size, sizeof(min_size)))
ret = -EFAULT;
}
goto err_free;
}
if (copy_from_bpfptr(&krecord[i], urecord, min_size)) {
ret = -EFAULT;
goto err_free;
}
/* check insn_off */
ret = -EINVAL;
if (i == 0) {
if (krecord[i].insn_off) {
verbose(env,
"nonzero insn_off %u for the first func info record",
krecord[i].insn_off);
goto err_free;
}
} else if (krecord[i].insn_off <= prev_offset) {
verbose(env,
"same or smaller insn offset (%u) than previous func info record (%u)",
krecord[i].insn_off, prev_offset);
goto err_free;
}
/* check type_id */
type = btf_type_by_id(btf, krecord[i].type_id);
if (!type || !btf_type_is_func(type)) {
verbose(env, "invalid type id %d in func info",
krecord[i].type_id);
goto err_free;
}
func_proto = btf_type_by_id(btf, type->type);
if (unlikely(!func_proto || !btf_type_is_func_proto(func_proto)))
/* btf_func_check() already verified it during BTF load */
goto err_free;
prev_offset = krecord[i].insn_off;
bpfptr_add(&urecord, urec_size);
}
prog->aux->func_info = krecord;
prog->aux->func_info_cnt = nfuncs;
return 0;
err_free:
kvfree(krecord);
return ret;
}
static int check_btf_func(struct bpf_verifier_env *env,
const union bpf_attr *attr,
bpfptr_t uattr)
{
const struct btf_type *type, *func_proto, *ret_type;
u32 i, nfuncs, urec_size;
struct bpf_func_info *krecord;
struct bpf_func_info_aux *info_aux = NULL;
struct bpf_prog *prog;
const struct btf *btf;
bpfptr_t urecord;
bool scalar_return;
int ret = -ENOMEM;
nfuncs = attr->func_info_cnt;
if (!nfuncs) {
if (check_abnormal_return(env))
return -EINVAL;
return 0;
}
if (nfuncs != env->subprog_cnt) {
verbose(env, "number of funcs in func_info doesn't match number of subprogs\n");
return -EINVAL;
}
urec_size = attr->func_info_rec_size;
prog = env->prog;
btf = prog->aux->btf;
urecord = make_bpfptr(attr->func_info, uattr.is_kernel);
krecord = prog->aux->func_info;
info_aux = kcalloc(nfuncs, sizeof(*info_aux), GFP_KERNEL | __GFP_NOWARN);
if (!info_aux)
return -ENOMEM;
for (i = 0; i < nfuncs; i++) {
/* check insn_off */
ret = -EINVAL;
if (env->subprog_info[i].start != krecord[i].insn_off) {
verbose(env, "func_info BTF section doesn't match subprog layout in BPF program\n");
goto err_free;
}
/* Already checked type_id */
type = btf_type_by_id(btf, krecord[i].type_id);
info_aux[i].linkage = BTF_INFO_VLEN(type->info);
/* Already checked func_proto */
func_proto = btf_type_by_id(btf, type->type);
ret_type = btf_type_skip_modifiers(btf, func_proto->type, NULL);
scalar_return =
btf_type_is_small_int(ret_type) || btf_is_any_enum(ret_type);
if (i && !scalar_return && env->subprog_info[i].has_ld_abs) {
verbose(env, "LD_ABS is only allowed in functions that return 'int'.\n");
goto err_free;
}
if (i && !scalar_return && env->subprog_info[i].has_tail_call) {
verbose(env, "tail_call is only allowed in functions that return 'int'.\n");
goto err_free;
}
bpfptr_add(&urecord, urec_size);
}
prog->aux->func_info_aux = info_aux;
return 0;
err_free:
kfree(info_aux);
return ret;
}
static void adjust_btf_func(struct bpf_verifier_env *env)
{
struct bpf_prog_aux *aux = env->prog->aux;
int i;
if (!aux->func_info)
return;
/* func_info is not available for hidden subprogs */
for (i = 0; i < env->subprog_cnt - env->hidden_subprog_cnt; i++)
aux->func_info[i].insn_off = env->subprog_info[i].start;
}
#define MIN_BPF_LINEINFO_SIZE offsetofend(struct bpf_line_info, line_col)
#define MAX_LINEINFO_REC_SIZE MAX_FUNCINFO_REC_SIZE
static int check_btf_line(struct bpf_verifier_env *env,
const union bpf_attr *attr,
bpfptr_t uattr)
{
u32 i, s, nr_linfo, ncopy, expected_size, rec_size, prev_offset = 0;
struct bpf_subprog_info *sub;
struct bpf_line_info *linfo;
struct bpf_prog *prog;
const struct btf *btf;
bpfptr_t ulinfo;
int err;
nr_linfo = attr->line_info_cnt;
if (!nr_linfo)
return 0;
if (nr_linfo > INT_MAX / sizeof(struct bpf_line_info))
return -EINVAL;
rec_size = attr->line_info_rec_size;
if (rec_size < MIN_BPF_LINEINFO_SIZE ||
rec_size > MAX_LINEINFO_REC_SIZE ||
rec_size & (sizeof(u32) - 1))
return -EINVAL;
/* Need to zero it in case the userspace may
* pass in a smaller bpf_line_info object.
*/
linfo = kvcalloc(nr_linfo, sizeof(struct bpf_line_info),
GFP_KERNEL | __GFP_NOWARN);
if (!linfo)
return -ENOMEM;
prog = env->prog;
btf = prog->aux->btf;
s = 0;
sub = env->subprog_info;
ulinfo = make_bpfptr(attr->line_info, uattr.is_kernel);
expected_size = sizeof(struct bpf_line_info);
ncopy = min_t(u32, expected_size, rec_size);
for (i = 0; i < nr_linfo; i++) {
err = bpf_check_uarg_tail_zero(ulinfo, expected_size, rec_size);
if (err) {
if (err == -E2BIG) {
verbose(env, "nonzero tailing record in line_info");
if (copy_to_bpfptr_offset(uattr,
offsetof(union bpf_attr, line_info_rec_size),
&expected_size, sizeof(expected_size)))
err = -EFAULT;
}
goto err_free;
}
if (copy_from_bpfptr(&linfo[i], ulinfo, ncopy)) {
err = -EFAULT;
goto err_free;
}
/*
* Check insn_off to ensure
* 1) strictly increasing AND
* 2) bounded by prog->len
*
* The linfo[0].insn_off == 0 check logically falls into
* the later "missing bpf_line_info for func..." case
* because the first linfo[0].insn_off must be the
* first sub also and the first sub must have
* subprog_info[0].start == 0.
*/
if ((i && linfo[i].insn_off <= prev_offset) ||
linfo[i].insn_off >= prog->len) {
verbose(env, "Invalid line_info[%u].insn_off:%u (prev_offset:%u prog->len:%u)\n",
i, linfo[i].insn_off, prev_offset,
prog->len);
err = -EINVAL;
goto err_free;
}
if (!prog->insnsi[linfo[i].insn_off].code) {
verbose(env,
"Invalid insn code at line_info[%u].insn_off\n",
i);
err = -EINVAL;
goto err_free;
}
if (!btf_name_by_offset(btf, linfo[i].line_off) ||
!btf_name_by_offset(btf, linfo[i].file_name_off)) {
verbose(env, "Invalid line_info[%u].line_off or .file_name_off\n", i);
err = -EINVAL;
goto err_free;
}
if (s != env->subprog_cnt) {
if (linfo[i].insn_off == sub[s].start) {
sub[s].linfo_idx = i;
s++;
} else if (sub[s].start < linfo[i].insn_off) {
verbose(env, "missing bpf_line_info for func#%u\n", s);
err = -EINVAL;
goto err_free;
}
}
prev_offset = linfo[i].insn_off;
bpfptr_add(&ulinfo, rec_size);
}
if (s != env->subprog_cnt) {
verbose(env, "missing bpf_line_info for %u funcs starting from func#%u\n",
env->subprog_cnt - s, s);
err = -EINVAL;
goto err_free;
}
prog->aux->linfo = linfo;
prog->aux->nr_linfo = nr_linfo;
return 0;
err_free:
kvfree(linfo);
return err;
}
#define MIN_CORE_RELO_SIZE sizeof(struct bpf_core_relo)
#define MAX_CORE_RELO_SIZE MAX_FUNCINFO_REC_SIZE
static int check_core_relo(struct bpf_verifier_env *env,
const union bpf_attr *attr,
bpfptr_t uattr)
{
u32 i, nr_core_relo, ncopy, expected_size, rec_size;
struct bpf_core_relo core_relo = {};
struct bpf_prog *prog = env->prog;
const struct btf *btf = prog->aux->btf;
struct bpf_core_ctx ctx = {
.log = &env->log,
.btf = btf,
};
bpfptr_t u_core_relo;
int err;
nr_core_relo = attr->core_relo_cnt;
if (!nr_core_relo)
return 0;
if (nr_core_relo > INT_MAX / sizeof(struct bpf_core_relo))
return -EINVAL;
rec_size = attr->core_relo_rec_size;
if (rec_size < MIN_CORE_RELO_SIZE ||
rec_size > MAX_CORE_RELO_SIZE ||
rec_size % sizeof(u32))
return -EINVAL;
u_core_relo = make_bpfptr(attr->core_relos, uattr.is_kernel);
expected_size = sizeof(struct bpf_core_relo);
ncopy = min_t(u32, expected_size, rec_size);
/* Unlike func_info and line_info, copy and apply each CO-RE
* relocation record one at a time.
*/
for (i = 0; i < nr_core_relo; i++) {
/* future proofing when sizeof(bpf_core_relo) changes */
err = bpf_check_uarg_tail_zero(u_core_relo, expected_size, rec_size);
if (err) {
if (err == -E2BIG) {
verbose(env, "nonzero tailing record in core_relo");
if (copy_to_bpfptr_offset(uattr,
offsetof(union bpf_attr, core_relo_rec_size),
&expected_size, sizeof(expected_size)))
err = -EFAULT;
}
break;
}
if (copy_from_bpfptr(&core_relo, u_core_relo, ncopy)) {
err = -EFAULT;
break;
}
if (core_relo.insn_off % 8 || core_relo.insn_off / 8 >= prog->len) {
verbose(env, "Invalid core_relo[%u].insn_off:%u prog->len:%u\n",
i, core_relo.insn_off, prog->len);
err = -EINVAL;
break;
}
err = bpf_core_apply(&ctx, &core_relo, i,
&prog->insnsi[core_relo.insn_off / 8]);
if (err)
break;
bpfptr_add(&u_core_relo, rec_size);
}
return err;
}
static int check_btf_info_early(struct bpf_verifier_env *env,
const union bpf_attr *attr,
bpfptr_t uattr)
{
struct btf *btf;
int err;
if (!attr->func_info_cnt && !attr->line_info_cnt) {
if (check_abnormal_return(env))
return -EINVAL;
return 0;
}
btf = btf_get_by_fd(attr->prog_btf_fd);
if (IS_ERR(btf))
return PTR_ERR(btf);
if (btf_is_kernel(btf)) {
btf_put(btf);
return -EACCES;
}
env->prog->aux->btf = btf;
err = check_btf_func_early(env, attr, uattr);
if (err)
return err;
return 0;
}
static int check_btf_info(struct bpf_verifier_env *env,
const union bpf_attr *attr,
bpfptr_t uattr)
{
int err;
if (!attr->func_info_cnt && !attr->line_info_cnt) {
if (check_abnormal_return(env))
return -EINVAL;
return 0;
}
err = check_btf_func(env, attr, uattr);
if (err)
return err;
err = check_btf_line(env, attr, uattr);
if (err)
return err;
err = check_core_relo(env, attr, uattr);
if (err)
return err;
return 0;
}
/* check %cur's range satisfies %old's */
static bool range_within(const struct bpf_reg_state *old,
const struct bpf_reg_state *cur)
{
return old->umin_value <= cur->umin_value &&
old->umax_value >= cur->umax_value &&
old->smin_value <= cur->smin_value &&
old->smax_value >= cur->smax_value &&
old->u32_min_value <= cur->u32_min_value &&
old->u32_max_value >= cur->u32_max_value &&
old->s32_min_value <= cur->s32_min_value &&
old->s32_max_value >= cur->s32_max_value;
}
/* If in the old state two registers had the same id, then they need to have
* the same id in the new state as well. But that id could be different from
* the old state, so we need to track the mapping from old to new ids.
* Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent
* regs with old id 5 must also have new id 9 for the new state to be safe. But
* regs with a different old id could still have new id 9, we don't care about
* that.
* So we look through our idmap to see if this old id has been seen before. If
* so, we require the new id to match; otherwise, we add the id pair to the map.
*/
static bool check_ids(u32 old_id, u32 cur_id, struct bpf_idmap *idmap)
{
struct bpf_id_pair *map = idmap->map;
unsigned int i;
/* either both IDs should be set or both should be zero */
if (!!old_id != !!cur_id)
return false;
if (old_id == 0) /* cur_id == 0 as well */
return true;
for (i = 0; i < BPF_ID_MAP_SIZE; i++) {
if (!map[i].old) {
/* Reached an empty slot; haven't seen this id before */
map[i].old = old_id;
map[i].cur = cur_id;
return true;
}
if (map[i].old == old_id)
return map[i].cur == cur_id;
if (map[i].cur == cur_id)
return false;
}
/* We ran out of idmap slots, which should be impossible */
WARN_ON_ONCE(1);
return false;
}
/* Similar to check_ids(), but allocate a unique temporary ID
* for 'old_id' or 'cur_id' of zero.
* This makes pairs like '0 vs unique ID', 'unique ID vs 0' valid.
*/
static bool check_scalar_ids(u32 old_id, u32 cur_id, struct bpf_idmap *idmap)
{
old_id = old_id ? old_id : ++idmap->tmp_id_gen;
cur_id = cur_id ? cur_id : ++idmap->tmp_id_gen;
return check_ids(old_id, cur_id, idmap);
}
static void clean_func_state(struct bpf_verifier_env *env,
struct bpf_func_state *st)
{
enum bpf_reg_liveness live;
int i, j;
for (i = 0; i < BPF_REG_FP; i++) {
live = st->regs[i].live;
/* liveness must not touch this register anymore */
st->regs[i].live |= REG_LIVE_DONE;
if (!(live & REG_LIVE_READ))
/* since the register is unused, clear its state
* to make further comparison simpler
*/
__mark_reg_not_init(env, &st->regs[i]);
}
for (i = 0; i < st->allocated_stack / BPF_REG_SIZE; i++) {
live = st->stack[i].spilled_ptr.live;
/* liveness must not touch this stack slot anymore */
st->stack[i].spilled_ptr.live |= REG_LIVE_DONE;
if (!(live & REG_LIVE_READ)) {
__mark_reg_not_init(env, &st->stack[i].spilled_ptr);
for (j = 0; j < BPF_REG_SIZE; j++)
st->stack[i].slot_type[j] = STACK_INVALID;
}
}
}
static void clean_verifier_state(struct bpf_verifier_env *env,
struct bpf_verifier_state *st)
{
int i;
if (st->frame[0]->regs[0].live & REG_LIVE_DONE)
/* all regs in this state in all frames were already marked */
return;
for (i = 0; i <= st->curframe; i++)
clean_func_state(env, st->frame[i]);
}
/* the parentage chains form a tree.
* the verifier states are added to state lists at given insn and
* pushed into state stack for future exploration.
* when the verifier reaches bpf_exit insn some of the verifer states
* stored in the state lists have their final liveness state already,
* but a lot of states will get revised from liveness point of view when
* the verifier explores other branches.
* Example:
* 1: r0 = 1
* 2: if r1 == 100 goto pc+1
* 3: r0 = 2
* 4: exit
* when the verifier reaches exit insn the register r0 in the state list of
* insn 2 will be seen as !REG_LIVE_READ. Then the verifier pops the other_branch
* of insn 2 and goes exploring further. At the insn 4 it will walk the
* parentage chain from insn 4 into insn 2 and will mark r0 as REG_LIVE_READ.
*
* Since the verifier pushes the branch states as it sees them while exploring
* the program the condition of walking the branch instruction for the second
* time means that all states below this branch were already explored and
* their final liveness marks are already propagated.
* Hence when the verifier completes the search of state list in is_state_visited()
* we can call this clean_live_states() function to mark all liveness states
* as REG_LIVE_DONE to indicate that 'parent' pointers of 'struct bpf_reg_state'
* will not be used.
* This function also clears the registers and stack for states that !READ
* to simplify state merging.
*
* Important note here that walking the same branch instruction in the callee
* doesn't meant that the states are DONE. The verifier has to compare
* the callsites
*/
static void clean_live_states(struct bpf_verifier_env *env, int insn,
struct bpf_verifier_state *cur)
{
struct bpf_verifier_state_list *sl;
sl = *explored_state(env, insn);
while (sl) {
if (sl->state.branches)
goto next;
if (sl->state.insn_idx != insn ||
!same_callsites(&sl->state, cur))
goto next;
clean_verifier_state(env, &sl->state);
next:
sl = sl->next;
}
}
static bool regs_exact(const struct bpf_reg_state *rold,
const struct bpf_reg_state *rcur,
struct bpf_idmap *idmap)
{
return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 &&
check_ids(rold->id, rcur->id, idmap) &&
check_ids(rold->ref_obj_id, rcur->ref_obj_id, idmap);
}
enum exact_level {
NOT_EXACT,
EXACT,
RANGE_WITHIN
};
/* Returns true if (rold safe implies rcur safe) */
static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold,
struct bpf_reg_state *rcur, struct bpf_idmap *idmap,
enum exact_level exact)
{
if (exact == EXACT)
return regs_exact(rold, rcur, idmap);
if (!(rold->live & REG_LIVE_READ) && exact == NOT_EXACT)
/* explored state didn't use this */
return true;
if (rold->type == NOT_INIT) {
if (exact == NOT_EXACT || rcur->type == NOT_INIT)
/* explored state can't have used this */
return true;
}
/* Enforce that register types have to match exactly, including their
* modifiers (like PTR_MAYBE_NULL, MEM_RDONLY, etc), as a general
* rule.
*
* One can make a point that using a pointer register as unbounded
* SCALAR would be technically acceptable, but this could lead to
* pointer leaks because scalars are allowed to leak while pointers
* are not. We could make this safe in special cases if root is
* calling us, but it's probably not worth the hassle.
*
* Also, register types that are *not* MAYBE_NULL could technically be
* safe to use as their MAYBE_NULL variants (e.g., PTR_TO_MAP_VALUE
* is safe to be used as PTR_TO_MAP_VALUE_OR_NULL, provided both point
* to the same map).
* However, if the old MAYBE_NULL register then got NULL checked,
* doing so could have affected others with the same id, and we can't
* check for that because we lost the id when we converted to
* a non-MAYBE_NULL variant.
* So, as a general rule we don't allow mixing MAYBE_NULL and
* non-MAYBE_NULL registers as well.
*/
if (rold->type != rcur->type)
return false;
switch (base_type(rold->type)) {
case SCALAR_VALUE:
if (env->explore_alu_limits) {
/* explore_alu_limits disables tnum_in() and range_within()
* logic and requires everything to be strict
*/
return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 &&
check_scalar_ids(rold->id, rcur->id, idmap);
}
if (!rold->precise && exact == NOT_EXACT)
return true;
if ((rold->id & BPF_ADD_CONST) != (rcur->id & BPF_ADD_CONST))
return false;
if ((rold->id & BPF_ADD_CONST) && (rold->off != rcur->off))
return false;
/* Why check_ids() for scalar registers?
*
* Consider the following BPF code:
* 1: r6 = ... unbound scalar, ID=a ...
* 2: r7 = ... unbound scalar, ID=b ...
* 3: if (r6 > r7) goto +1
* 4: r6 = r7
* 5: if (r6 > X) goto ...
* 6: ... memory operation using r7 ...
*
* First verification path is [1-6]:
* - at (4) same bpf_reg_state::id (b) would be assigned to r6 and r7;
* - at (5) r6 would be marked <= X, sync_linked_regs() would also mark
* r7 <= X, because r6 and r7 share same id.
* Next verification path is [1-4, 6].
*
* Instruction (6) would be reached in two states:
* I. r6{.id=b}, r7{.id=b} via path 1-6;
* II. r6{.id=a}, r7{.id=b} via path 1-4, 6.
*
* Use check_ids() to distinguish these states.
* ---
* Also verify that new value satisfies old value range knowledge.
*/
return range_within(rold, rcur) &&
tnum_in(rold->var_off, rcur->var_off) &&
check_scalar_ids(rold->id, rcur->id, idmap);
case PTR_TO_MAP_KEY:
case PTR_TO_MAP_VALUE:
case PTR_TO_MEM:
case PTR_TO_BUF:
case PTR_TO_TP_BUFFER:
/* If the new min/max/var_off satisfy the old ones and
* everything else matches, we are OK.
*/
return memcmp(rold, rcur, offsetof(struct bpf_reg_state, var_off)) == 0 &&
range_within(rold, rcur) &&
tnum_in(rold->var_off, rcur->var_off) &&
check_ids(rold->id, rcur->id, idmap) &&
check_ids(rold->ref_obj_id, rcur->ref_obj_id, idmap);
case PTR_TO_PACKET_META:
case PTR_TO_PACKET:
/* We must have at least as much range as the old ptr
* did, so that any accesses which were safe before are
* still safe. This is true even if old range < old off,
* since someone could have accessed through (ptr - k), or
* even done ptr -= k in a register, to get a safe access.
*/
if (rold->range > rcur->range)
return false;
/* If the offsets don't match, we can't trust our alignment;
* nor can we be sure that we won't fall out of range.
*/
if (rold->off != rcur->off)
return false;
/* id relations must be preserved */
if (!check_ids(rold->id, rcur->id, idmap))
return false;
/* new val must satisfy old val knowledge */
return range_within(rold, rcur) &&
tnum_in(rold->var_off, rcur->var_off);
case PTR_TO_STACK:
/* two stack pointers are equal only if they're pointing to
* the same stack frame, since fp-8 in foo != fp-8 in bar
*/
return regs_exact(rold, rcur, idmap) && rold->frameno == rcur->frameno;
case PTR_TO_ARENA:
return true;
default:
return regs_exact(rold, rcur, idmap);
}
}
static struct bpf_reg_state unbound_reg;
static __init int unbound_reg_init(void)
{
__mark_reg_unknown_imprecise(&unbound_reg);
unbound_reg.live |= REG_LIVE_READ;
return 0;
}
late_initcall(unbound_reg_init);
static bool is_stack_all_misc(struct bpf_verifier_env *env,
struct bpf_stack_state *stack)
{
u32 i;
for (i = 0; i < ARRAY_SIZE(stack->slot_type); ++i) {
if ((stack->slot_type[i] == STACK_MISC) ||
(stack->slot_type[i] == STACK_INVALID && env->allow_uninit_stack))
continue;
return false;
}
return true;
}
static struct bpf_reg_state *scalar_reg_for_stack(struct bpf_verifier_env *env,
struct bpf_stack_state *stack)
{
if (is_spilled_scalar_reg64(stack))
return &stack->spilled_ptr;
if (is_stack_all_misc(env, stack))
return &unbound_reg;
return NULL;
}
static bool stacksafe(struct bpf_verifier_env *env, struct bpf_func_state *old,
struct bpf_func_state *cur, struct bpf_idmap *idmap,
enum exact_level exact)
{
int i, spi;
/* walk slots of the explored stack and ignore any additional
* slots in the current stack, since explored(safe) state
* didn't use them
*/
for (i = 0; i < old->allocated_stack; i++) {
struct bpf_reg_state *old_reg, *cur_reg;
spi = i / BPF_REG_SIZE;
if (exact != NOT_EXACT &&
(i >= cur->allocated_stack ||
old->stack[spi].slot_type[i % BPF_REG_SIZE] !=
cur->stack[spi].slot_type[i % BPF_REG_SIZE]))
return false;
if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ)
&& exact == NOT_EXACT) {
i += BPF_REG_SIZE - 1;
/* explored state didn't use this */
continue;
}
if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_INVALID)
continue;
if (env->allow_uninit_stack &&
old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_MISC)
continue;
/* explored stack has more populated slots than current stack
* and these slots were used
*/
if (i >= cur->allocated_stack)
return false;
/* 64-bit scalar spill vs all slots MISC and vice versa.
* Load from all slots MISC produces unbound scalar.
* Construct a fake register for such stack and call
* regsafe() to ensure scalar ids are compared.
*/
old_reg = scalar_reg_for_stack(env, &old->stack[spi]);
cur_reg = scalar_reg_for_stack(env, &cur->stack[spi]);
if (old_reg && cur_reg) {
if (!regsafe(env, old_reg, cur_reg, idmap, exact))
return false;
i += BPF_REG_SIZE - 1;
continue;
}
/* if old state was safe with misc data in the stack
* it will be safe with zero-initialized stack.
* The opposite is not true
*/
if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_MISC &&
cur->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_ZERO)
continue;
if (old->stack[spi].slot_type[i % BPF_REG_SIZE] !=
cur->stack[spi].slot_type[i % BPF_REG_SIZE])
/* Ex: old explored (safe) state has STACK_SPILL in
* this stack slot, but current has STACK_MISC ->
* this verifier states are not equivalent,
* return false to continue verification of this path
*/
return false;
if (i % BPF_REG_SIZE != BPF_REG_SIZE - 1)
continue;
/* Both old and cur are having same slot_type */
switch (old->stack[spi].slot_type[BPF_REG_SIZE - 1]) {
case STACK_SPILL:
/* when explored and current stack slot are both storing
* spilled registers, check that stored pointers types
* are the same as well.
* Ex: explored safe path could have stored
* (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8}
* but current path has stored:
* (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16}
* such verifier states are not equivalent.
* return false to continue verification of this path
*/
if (!regsafe(env, &old->stack[spi].spilled_ptr,
&cur->stack[spi].spilled_ptr, idmap, exact))
return false;
break;
case STACK_DYNPTR:
old_reg = &old->stack[spi].spilled_ptr;
cur_reg = &cur->stack[spi].spilled_ptr;
if (old_reg->dynptr.type != cur_reg->dynptr.type ||
old_reg->dynptr.first_slot != cur_reg->dynptr.first_slot ||
!check_ids(old_reg->ref_obj_id, cur_reg->ref_obj_id, idmap))
return false;
break;
case STACK_ITER:
old_reg = &old->stack[spi].spilled_ptr;
cur_reg = &cur->stack[spi].spilled_ptr;
/* iter.depth is not compared between states as it
* doesn't matter for correctness and would otherwise
* prevent convergence; we maintain it only to prevent
* infinite loop check triggering, see
* iter_active_depths_differ()
*/
if (old_reg->iter.btf != cur_reg->iter.btf ||
old_reg->iter.btf_id != cur_reg->iter.btf_id ||
old_reg->iter.state != cur_reg->iter.state ||
/* ignore {old_reg,cur_reg}->iter.depth, see above */
!check_ids(old_reg->ref_obj_id, cur_reg->ref_obj_id, idmap))
return false;
break;
case STACK_MISC:
case STACK_ZERO:
case STACK_INVALID:
continue;
/* Ensure that new unhandled slot types return false by default */
default:
return false;
}
}
return true;
}
static bool refsafe(struct bpf_func_state *old, struct bpf_func_state *cur,
struct bpf_idmap *idmap)
{
int i;
if (old->acquired_refs != cur->acquired_refs)
return false;
for (i = 0; i < old->acquired_refs; i++) {
if (!check_ids(old->refs[i].id, cur->refs[i].id, idmap))
return false;
}
return true;
}
/* compare two verifier states
*
* all states stored in state_list are known to be valid, since
* verifier reached 'bpf_exit' instruction through them
*
* this function is called when verifier exploring different branches of
* execution popped from the state stack. If it sees an old state that has
* more strict register state and more strict stack state then this execution
* branch doesn't need to be explored further, since verifier already
* concluded that more strict state leads to valid finish.
*
* Therefore two states are equivalent if register state is more conservative
* and explored stack state is more conservative than the current one.
* Example:
* explored current
* (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
* (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
*
* In other words if current stack state (one being explored) has more
* valid slots than old one that already passed validation, it means
* the verifier can stop exploring and conclude that current state is valid too
*
* Similarly with registers. If explored state has register type as invalid
* whereas register type in current state is meaningful, it means that
* the current state will reach 'bpf_exit' instruction safely
*/
static bool func_states_equal(struct bpf_verifier_env *env, struct bpf_func_state *old,
struct bpf_func_state *cur, enum exact_level exact)
{
int i;
if (old->callback_depth > cur->callback_depth)
return false;
for (i = 0; i < MAX_BPF_REG; i++)
if (!regsafe(env, &old->regs[i], &cur->regs[i],
&env->idmap_scratch, exact))
return false;
if (!stacksafe(env, old, cur, &env->idmap_scratch, exact))
return false;
if (!refsafe(old, cur, &env->idmap_scratch))
return false;
return true;
}
static void reset_idmap_scratch(struct bpf_verifier_env *env)
{
env->idmap_scratch.tmp_id_gen = env->id_gen;
memset(&env->idmap_scratch.map, 0, sizeof(env->idmap_scratch.map));
}
static bool states_equal(struct bpf_verifier_env *env,
struct bpf_verifier_state *old,
struct bpf_verifier_state *cur,
enum exact_level exact)
{
int i;
if (old->curframe != cur->curframe)
return false;
reset_idmap_scratch(env);
/* Verification state from speculative execution simulation
* must never prune a non-speculative execution one.
*/
if (old->speculative && !cur->speculative)
return false;
if (old->active_lock.ptr != cur->active_lock.ptr)
return false;
/* Old and cur active_lock's have to be either both present
* or both absent.
*/
if (!!old->active_lock.id != !!cur->active_lock.id)
return false;
if (old->active_lock.id &&
!check_ids(old->active_lock.id, cur->active_lock.id, &env->idmap_scratch))
return false;
if (old->active_rcu_lock != cur->active_rcu_lock)
return false;
if (old->active_preempt_lock != cur->active_preempt_lock)
return false;
if (old->in_sleepable != cur->in_sleepable)
return false;
/* for states to be equal callsites have to be the same
* and all frame states need to be equivalent
*/
for (i = 0; i <= old->curframe; i++) {
if (old->frame[i]->callsite != cur->frame[i]->callsite)
return false;
if (!func_states_equal(env, old->frame[i], cur->frame[i], exact))
return false;
}
return true;
}
/* Return 0 if no propagation happened. Return negative error code if error
* happened. Otherwise, return the propagated bit.
*/
static int propagate_liveness_reg(struct bpf_verifier_env *env,
struct bpf_reg_state *reg,
struct bpf_reg_state *parent_reg)
{
u8 parent_flag = parent_reg->live & REG_LIVE_READ;
u8 flag = reg->live & REG_LIVE_READ;
int err;
/* When comes here, read flags of PARENT_REG or REG could be any of
* REG_LIVE_READ64, REG_LIVE_READ32, REG_LIVE_NONE. There is no need
* of propagation if PARENT_REG has strongest REG_LIVE_READ64.
*/
if (parent_flag == REG_LIVE_READ64 ||
/* Or if there is no read flag from REG. */
!flag ||
/* Or if the read flag from REG is the same as PARENT_REG. */
parent_flag == flag)
return 0;
err = mark_reg_read(env, reg, parent_reg, flag);
if (err)
return err;
return flag;
}
/* A write screens off any subsequent reads; but write marks come from the
* straight-line code between a state and its parent. When we arrive at an
* equivalent state (jump target or such) we didn't arrive by the straight-line
* code, so read marks in the state must propagate to the parent regardless
* of the state's write marks. That's what 'parent == state->parent' comparison
* in mark_reg_read() is for.
*/
static int propagate_liveness(struct bpf_verifier_env *env,
const struct bpf_verifier_state *vstate,
struct bpf_verifier_state *vparent)
{
struct bpf_reg_state *state_reg, *parent_reg;
struct bpf_func_state *state, *parent;
int i, frame, err = 0;
if (vparent->curframe != vstate->curframe) {
WARN(1, "propagate_live: parent frame %d current frame %d\n",
vparent->curframe, vstate->curframe);
return -EFAULT;
}
/* Propagate read liveness of registers... */
BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG);
for (frame = 0; frame <= vstate->curframe; frame++) {
parent = vparent->frame[frame];
state = vstate->frame[frame];
parent_reg = parent->regs;
state_reg = state->regs;
/* We don't need to worry about FP liveness, it's read-only */
for (i = frame < vstate->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++) {
err = propagate_liveness_reg(env, &state_reg[i],
&parent_reg[i]);
if (err < 0)
return err;
if (err == REG_LIVE_READ64)
mark_insn_zext(env, &parent_reg[i]);
}
/* Propagate stack slots. */
for (i = 0; i < state->allocated_stack / BPF_REG_SIZE &&
i < parent->allocated_stack / BPF_REG_SIZE; i++) {
parent_reg = &parent->stack[i].spilled_ptr;
state_reg = &state->stack[i].spilled_ptr;
err = propagate_liveness_reg(env, state_reg,
parent_reg);
if (err < 0)
return err;
}
}
return 0;
}
/* find precise scalars in the previous equivalent state and
* propagate them into the current state
*/
static int propagate_precision(struct bpf_verifier_env *env,
const struct bpf_verifier_state *old)
{
struct bpf_reg_state *state_reg;
struct bpf_func_state *state;
int i, err = 0, fr;
bool first;
for (fr = old->curframe; fr >= 0; fr--) {
state = old->frame[fr];
state_reg = state->regs;
first = true;
for (i = 0; i < BPF_REG_FP; i++, state_reg++) {
if (state_reg->type != SCALAR_VALUE ||
!state_reg->precise ||
!(state_reg->live & REG_LIVE_READ))
continue;
if (env->log.level & BPF_LOG_LEVEL2) {
if (first)
verbose(env, "frame %d: propagating r%d", fr, i);
else
verbose(env, ",r%d", i);
}
bt_set_frame_reg(&env->bt, fr, i);
first = false;
}
for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
if (!is_spilled_reg(&state->stack[i]))
continue;
state_reg = &state->stack[i].spilled_ptr;
if (state_reg->type != SCALAR_VALUE ||
!state_reg->precise ||
!(state_reg->live & REG_LIVE_READ))
continue;
if (env->log.level & BPF_LOG_LEVEL2) {
if (first)
verbose(env, "frame %d: propagating fp%d",
fr, (-i - 1) * BPF_REG_SIZE);
else
verbose(env, ",fp%d", (-i - 1) * BPF_REG_SIZE);
}
bt_set_frame_slot(&env->bt, fr, i);
first = false;
}
if (!first)
verbose(env, "\n");
}
err = mark_chain_precision_batch(env);
if (err < 0)
return err;
return 0;
}
static bool states_maybe_looping(struct bpf_verifier_state *old,
struct bpf_verifier_state *cur)
{
struct bpf_func_state *fold, *fcur;
int i, fr = cur->curframe;
if (old->curframe != fr)
return false;
fold = old->frame[fr];
fcur = cur->frame[fr];
for (i = 0; i < MAX_BPF_REG; i++)
if (memcmp(&fold->regs[i], &fcur->regs[i],
offsetof(struct bpf_reg_state, parent)))
return false;
return true;
}
static bool is_iter_next_insn(struct bpf_verifier_env *env, int insn_idx)
{
return env->insn_aux_data[insn_idx].is_iter_next;
}
/* is_state_visited() handles iter_next() (see process_iter_next_call() for
* terminology) calls specially: as opposed to bounded BPF loops, it *expects*
* states to match, which otherwise would look like an infinite loop. So while
* iter_next() calls are taken care of, we still need to be careful and
* prevent erroneous and too eager declaration of "ininite loop", when
* iterators are involved.
*
* Here's a situation in pseudo-BPF assembly form:
*
* 0: again: ; set up iter_next() call args
* 1: r1 = &it ; <CHECKPOINT HERE>
* 2: call bpf_iter_num_next ; this is iter_next() call
* 3: if r0 == 0 goto done
* 4: ... something useful here ...
* 5: goto again ; another iteration
* 6: done:
* 7: r1 = &it
* 8: call bpf_iter_num_destroy ; clean up iter state
* 9: exit
*
* This is a typical loop. Let's assume that we have a prune point at 1:,
* before we get to `call bpf_iter_num_next` (e.g., because of that `goto
* again`, assuming other heuristics don't get in a way).
*
* When we first time come to 1:, let's say we have some state X. We proceed
* to 2:, fork states, enqueue ACTIVE, validate NULL case successfully, exit.
* Now we come back to validate that forked ACTIVE state. We proceed through
* 3-5, come to goto, jump to 1:. Let's assume our state didn't change, so we
* are converging. But the problem is that we don't know that yet, as this
* convergence has to happen at iter_next() call site only. So if nothing is
* done, at 1: verifier will use bounded loop logic and declare infinite
* looping (and would be *technically* correct, if not for iterator's
* "eventual sticky NULL" contract, see process_iter_next_call()). But we
* don't want that. So what we do in process_iter_next_call() when we go on
* another ACTIVE iteration, we bump slot->iter.depth, to mark that it's
* a different iteration. So when we suspect an infinite loop, we additionally
* check if any of the *ACTIVE* iterator states depths differ. If yes, we
* pretend we are not looping and wait for next iter_next() call.
*
* This only applies to ACTIVE state. In DRAINED state we don't expect to
* loop, because that would actually mean infinite loop, as DRAINED state is
* "sticky", and so we'll keep returning into the same instruction with the
* same state (at least in one of possible code paths).
*
* This approach allows to keep infinite loop heuristic even in the face of
* active iterator. E.g., C snippet below is and will be detected as
* inifintely looping:
*
* struct bpf_iter_num it;
* int *p, x;
*
* bpf_iter_num_new(&it, 0, 10);
* while ((p = bpf_iter_num_next(&t))) {
* x = p;
* while (x--) {} // <<-- infinite loop here
* }
*
*/
static bool iter_active_depths_differ(struct bpf_verifier_state *old, struct bpf_verifier_state *cur)
{
struct bpf_reg_state *slot, *cur_slot;
struct bpf_func_state *state;
int i, fr;
for (fr = old->curframe; fr >= 0; fr--) {
state = old->frame[fr];
for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
if (state->stack[i].slot_type[0] != STACK_ITER)
continue;
slot = &state->stack[i].spilled_ptr;
if (slot->iter.state != BPF_ITER_STATE_ACTIVE)
continue;
cur_slot = &cur->frame[fr]->stack[i].spilled_ptr;
if (cur_slot->iter.depth != slot->iter.depth)
return true;
}
}
return false;
}
static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
{
struct bpf_verifier_state_list *new_sl;
struct bpf_verifier_state_list *sl, **pprev;
struct bpf_verifier_state *cur = env->cur_state, *new, *loop_entry;
int i, j, n, err, states_cnt = 0;
bool force_new_state = env->test_state_freq || is_force_checkpoint(env, insn_idx);
bool add_new_state = force_new_state;
bool force_exact;
/* bpf progs typically have pruning point every 4 instructions
* http://vger.kernel.org/bpfconf2019.html#session-1
* Do not add new state for future pruning if the verifier hasn't seen
* at least 2 jumps and at least 8 instructions.
* This heuristics helps decrease 'total_states' and 'peak_states' metric.
* In tests that amounts to up to 50% reduction into total verifier
* memory consumption and 20% verifier time speedup.
*/
if (env->jmps_processed - env->prev_jmps_processed >= 2 &&
env->insn_processed - env->prev_insn_processed >= 8)
add_new_state = true;
pprev = explored_state(env, insn_idx);
sl = *pprev;
clean_live_states(env, insn_idx, cur);
while (sl) {
states_cnt++;
if (sl->state.insn_idx != insn_idx)
goto next;
if (sl->state.branches) {
struct bpf_func_state *frame = sl->state.frame[sl->state.curframe];
if (frame->in_async_callback_fn &&
frame->async_entry_cnt != cur->frame[cur->curframe]->async_entry_cnt) {
/* Different async_entry_cnt means that the verifier is
* processing another entry into async callback.
* Seeing the same state is not an indication of infinite
* loop or infinite recursion.
* But finding the same state doesn't mean that it's safe
* to stop processing the current state. The previous state
* hasn't yet reached bpf_exit, since state.branches > 0.
* Checking in_async_callback_fn alone is not enough either.
* Since the verifier still needs to catch infinite loops
* inside async callbacks.
*/
goto skip_inf_loop_check;
}
/* BPF open-coded iterators loop detection is special.
* states_maybe_looping() logic is too simplistic in detecting
* states that *might* be equivalent, because it doesn't know
* about ID remapping, so don't even perform it.
* See process_iter_next_call() and iter_active_depths_differ()
* for overview of the logic. When current and one of parent
* states are detected as equivalent, it's a good thing: we prove
* convergence and can stop simulating further iterations.
* It's safe to assume that iterator loop will finish, taking into
* account iter_next() contract of eventually returning
* sticky NULL result.
*
* Note, that states have to be compared exactly in this case because
* read and precision marks might not be finalized inside the loop.
* E.g. as in the program below:
*
* 1. r7 = -16
* 2. r6 = bpf_get_prandom_u32()
* 3. while (bpf_iter_num_next(&fp[-8])) {
* 4. if (r6 != 42) {
* 5. r7 = -32
* 6. r6 = bpf_get_prandom_u32()
* 7. continue
* 8. }
* 9. r0 = r10
* 10. r0 += r7
* 11. r8 = *(u64 *)(r0 + 0)
* 12. r6 = bpf_get_prandom_u32()
* 13. }
*
* Here verifier would first visit path 1-3, create a checkpoint at 3
* with r7=-16, continue to 4-7,3. Existing checkpoint at 3 does
* not have read or precision mark for r7 yet, thus inexact states
* comparison would discard current state with r7=-32
* => unsafe memory access at 11 would not be caught.
*/
if (is_iter_next_insn(env, insn_idx)) {
if (states_equal(env, &sl->state, cur, RANGE_WITHIN)) {
struct bpf_func_state *cur_frame;
struct bpf_reg_state *iter_state, *iter_reg;
int spi;
cur_frame = cur->frame[cur->curframe];
/* btf_check_iter_kfuncs() enforces that
* iter state pointer is always the first arg
*/
iter_reg = &cur_frame->regs[BPF_REG_1];
/* current state is valid due to states_equal(),
* so we can assume valid iter and reg state,
* no need for extra (re-)validations
*/
spi = __get_spi(iter_reg->off + iter_reg->var_off.value);
iter_state = &func(env, iter_reg)->stack[spi].spilled_ptr;
if (iter_state->iter.state == BPF_ITER_STATE_ACTIVE) {
update_loop_entry(cur, &sl->state);
goto hit;
}
}
goto skip_inf_loop_check;
}
if (is_may_goto_insn_at(env, insn_idx)) {
if (sl->state.may_goto_depth != cur->may_goto_depth &&
states_equal(env, &sl->state, cur, RANGE_WITHIN)) {
update_loop_entry(cur, &sl->state);
goto hit;
}
}
if (calls_callback(env, insn_idx)) {
if (states_equal(env, &sl->state, cur, RANGE_WITHIN))
goto hit;
goto skip_inf_loop_check;
}
/* attempt to detect infinite loop to avoid unnecessary doomed work */
if (states_maybe_looping(&sl->state, cur) &&
states_equal(env, &sl->state, cur, EXACT) &&
!iter_active_depths_differ(&sl->state, cur) &&
sl->state.may_goto_depth == cur->may_goto_depth &&
sl->state.callback_unroll_depth == cur->callback_unroll_depth) {
verbose_linfo(env, insn_idx, "; ");
verbose(env, "infinite loop detected at insn %d\n", insn_idx);
verbose(env, "cur state:");
print_verifier_state(env, cur->frame[cur->curframe], true);
verbose(env, "old state:");
print_verifier_state(env, sl->state.frame[cur->curframe], true);
return -EINVAL;
}
/* if the verifier is processing a loop, avoid adding new state
* too often, since different loop iterations have distinct
* states and may not help future pruning.
* This threshold shouldn't be too low to make sure that
* a loop with large bound will be rejected quickly.
* The most abusive loop will be:
* r1 += 1
* if r1 < 1000000 goto pc-2
* 1M insn_procssed limit / 100 == 10k peak states.
* This threshold shouldn't be too high either, since states
* at the end of the loop are likely to be useful in pruning.
*/
skip_inf_loop_check:
if (!force_new_state &&
env->jmps_processed - env->prev_jmps_processed < 20 &&
env->insn_processed - env->prev_insn_processed < 100)
add_new_state = false;
goto miss;
}
/* If sl->state is a part of a loop and this loop's entry is a part of
* current verification path then states have to be compared exactly.
* 'force_exact' is needed to catch the following case:
*
* initial Here state 'succ' was processed first,
* | it was eventually tracked to produce a
* V state identical to 'hdr'.
* .---------> hdr All branches from 'succ' had been explored
* | | and thus 'succ' has its .branches == 0.
* | V
* | .------... Suppose states 'cur' and 'succ' correspond
* | | | to the same instruction + callsites.
* | V V In such case it is necessary to check
* | ... ... if 'succ' and 'cur' are states_equal().
* | | | If 'succ' and 'cur' are a part of the
* | V V same loop exact flag has to be set.
* | succ <- cur To check if that is the case, verify
* | | if loop entry of 'succ' is in current
* | V DFS path.
* | ...
* | |
* '----'
*
* Additional details are in the comment before get_loop_entry().
*/
loop_entry = get_loop_entry(&sl->state);
force_exact = loop_entry && loop_entry->branches > 0;
if (states_equal(env, &sl->state, cur, force_exact ? RANGE_WITHIN : NOT_EXACT)) {
if (force_exact)
update_loop_entry(cur, loop_entry);
hit:
sl->hit_cnt++;
/* reached equivalent register/stack state,
* prune the search.
* Registers read by the continuation are read by us.
* If we have any write marks in env->cur_state, they
* will prevent corresponding reads in the continuation
* from reaching our parent (an explored_state). Our
* own state will get the read marks recorded, but
* they'll be immediately forgotten as we're pruning
* this state and will pop a new one.
*/
err = propagate_liveness(env, &sl->state, cur);
/* if previous state reached the exit with precision and
* current state is equivalent to it (except precision marks)
* the precision needs to be propagated back in
* the current state.
*/
if (is_jmp_point(env, env->insn_idx))
err = err ? : push_jmp_history(env, cur, 0, 0);
err = err ? : propagate_precision(env, &sl->state);
if (err)
return err;
return 1;
}
miss:
/* when new state is not going to be added do not increase miss count.
* Otherwise several loop iterations will remove the state
* recorded earlier. The goal of these heuristics is to have
* states from some iterations of the loop (some in the beginning
* and some at the end) to help pruning.
*/
if (add_new_state)
sl->miss_cnt++;
/* heuristic to determine whether this state is beneficial
* to keep checking from state equivalence point of view.
* Higher numbers increase max_states_per_insn and verification time,
* but do not meaningfully decrease insn_processed.
* 'n' controls how many times state could miss before eviction.
* Use bigger 'n' for checkpoints because evicting checkpoint states
* too early would hinder iterator convergence.
*/
n = is_force_checkpoint(env, insn_idx) && sl->state.branches > 0 ? 64 : 3;
if (sl->miss_cnt > sl->hit_cnt * n + n) {
/* the state is unlikely to be useful. Remove it to
* speed up verification
*/
*pprev = sl->next;
if (sl->state.frame[0]->regs[0].live & REG_LIVE_DONE &&
!sl->state.used_as_loop_entry) {
u32 br = sl->state.branches;
WARN_ONCE(br,
"BUG live_done but branches_to_explore %d\n",
br);
free_verifier_state(&sl->state, false);
kfree(sl);
env->peak_states--;
} else {
/* cannot free this state, since parentage chain may
* walk it later. Add it for free_list instead to
* be freed at the end of verification
*/
sl->next = env->free_list;
env->free_list = sl;
}
sl = *pprev;
continue;
}
next:
pprev = &sl->next;
sl = *pprev;
}
if (env->max_states_per_insn < states_cnt)
env->max_states_per_insn = states_cnt;
if (!env->bpf_capable && states_cnt > BPF_COMPLEXITY_LIMIT_STATES)
return 0;
if (!add_new_state)
return 0;
/* There were no equivalent states, remember the current one.
* Technically the current state is not proven to be safe yet,
* but it will either reach outer most bpf_exit (which means it's safe)
* or it will be rejected. When there are no loops the verifier won't be
* seeing this tuple (frame[0].callsite, frame[1].callsite, .. insn_idx)
* again on the way to bpf_exit.
* When looping the sl->state.branches will be > 0 and this state
* will not be considered for equivalence until branches == 0.
*/
new_sl = kzalloc(sizeof(struct bpf_verifier_state_list), GFP_KERNEL);
if (!new_sl)
return -ENOMEM;
env->total_states++;
env->peak_states++;
env->prev_jmps_processed = env->jmps_processed;
env->prev_insn_processed = env->insn_processed;
/* forget precise markings we inherited, see __mark_chain_precision */
if (env->bpf_capable)
mark_all_scalars_imprecise(env, cur);
/* add new state to the head of linked list */
new = &new_sl->state;
err = copy_verifier_state(new, cur);
if (err) {
free_verifier_state(new, false);
kfree(new_sl);
return err;
}
new->insn_idx = insn_idx;
WARN_ONCE(new->branches != 1,
"BUG is_state_visited:branches_to_explore=%d insn %d\n", new->branches, insn_idx);
cur->parent = new;
cur->first_insn_idx = insn_idx;
cur->dfs_depth = new->dfs_depth + 1;
clear_jmp_history(cur);
new_sl->next = *explored_state(env, insn_idx);
*explored_state(env, insn_idx) = new_sl;
/* connect new state to parentage chain. Current frame needs all
* registers connected. Only r6 - r9 of the callers are alive (pushed
* to the stack implicitly by JITs) so in callers' frames connect just
* r6 - r9 as an optimization. Callers will have r1 - r5 connected to
* the state of the call instruction (with WRITTEN set), and r0 comes
* from callee with its full parentage chain, anyway.
*/
/* clear write marks in current state: the writes we did are not writes
* our child did, so they don't screen off its reads from us.
* (There are no read marks in current state, because reads always mark
* their parent and current state never has children yet. Only
* explored_states can get read marks.)
*/
for (j = 0; j <= cur->curframe; j++) {
for (i = j < cur->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++)
cur->frame[j]->regs[i].parent = &new->frame[j]->regs[i];
for (i = 0; i < BPF_REG_FP; i++)
cur->frame[j]->regs[i].live = REG_LIVE_NONE;
}
/* all stack frames are accessible from callee, clear them all */
for (j = 0; j <= cur->curframe; j++) {
struct bpf_func_state *frame = cur->frame[j];
struct bpf_func_state *newframe = new->frame[j];
for (i = 0; i < frame->allocated_stack / BPF_REG_SIZE; i++) {
frame->stack[i].spilled_ptr.live = REG_LIVE_NONE;
frame->stack[i].spilled_ptr.parent =
&newframe->stack[i].spilled_ptr;
}
}
return 0;
}
/* Return true if it's OK to have the same insn return a different type. */
static bool reg_type_mismatch_ok(enum bpf_reg_type type)
{
switch (base_type(type)) {
case PTR_TO_CTX:
case PTR_TO_SOCKET:
case PTR_TO_SOCK_COMMON:
case PTR_TO_TCP_SOCK:
case PTR_TO_XDP_SOCK:
case PTR_TO_BTF_ID:
case PTR_TO_ARENA:
return false;
default:
return true;
}
}
/* If an instruction was previously used with particular pointer types, then we
* need to be careful to avoid cases such as the below, where it may be ok
* for one branch accessing the pointer, but not ok for the other branch:
*
* R1 = sock_ptr
* goto X;
* ...
* R1 = some_other_valid_ptr;
* goto X;
* ...
* R2 = *(u32 *)(R1 + 0);
*/
static bool reg_type_mismatch(enum bpf_reg_type src, enum bpf_reg_type prev)
{
return src != prev && (!reg_type_mismatch_ok(src) ||
!reg_type_mismatch_ok(prev));
}
static int save_aux_ptr_type(struct bpf_verifier_env *env, enum bpf_reg_type type,
bool allow_trust_mismatch)
{
enum bpf_reg_type *prev_type = &env->insn_aux_data[env->insn_idx].ptr_type;
if (*prev_type == NOT_INIT) {
/* Saw a valid insn
* dst_reg = *(u32 *)(src_reg + off)
* save type to validate intersecting paths
*/
*prev_type = type;
} else if (reg_type_mismatch(type, *prev_type)) {
/* Abuser program is trying to use the same insn
* dst_reg = *(u32*) (src_reg + off)
* with different pointer types:
* src_reg == ctx in one branch and
* src_reg == stack|map in some other branch.
* Reject it.
*/
if (allow_trust_mismatch &&
base_type(type) == PTR_TO_BTF_ID &&
base_type(*prev_type) == PTR_TO_BTF_ID) {
/*
* Have to support a use case when one path through
* the program yields TRUSTED pointer while another
* is UNTRUSTED. Fallback to UNTRUSTED to generate
* BPF_PROBE_MEM/BPF_PROBE_MEMSX.
*/
*prev_type = PTR_TO_BTF_ID | PTR_UNTRUSTED;
} else {
verbose(env, "same insn cannot be used with different pointers\n");
return -EINVAL;
}
}
return 0;
}
static int do_check(struct bpf_verifier_env *env)
{
bool pop_log = !(env->log.level & BPF_LOG_LEVEL2);
struct bpf_verifier_state *state = env->cur_state;
struct bpf_insn *insns = env->prog->insnsi;
struct bpf_reg_state *regs;
int insn_cnt = env->prog->len;
bool do_print_state = false;
int prev_insn_idx = -1;
for (;;) {
bool exception_exit = false;
struct bpf_insn *insn;
u8 class;
int err;
/* reset current history entry on each new instruction */
env->cur_hist_ent = NULL;
env->prev_insn_idx = prev_insn_idx;
if (env->insn_idx >= insn_cnt) {
verbose(env, "invalid insn idx %d insn_cnt %d\n",
env->insn_idx, insn_cnt);
return -EFAULT;
}
insn = &insns[env->insn_idx];
class = BPF_CLASS(insn->code);
if (++env->insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
verbose(env,
"BPF program is too large. Processed %d insn\n",
env->insn_processed);
return -E2BIG;
}
state->last_insn_idx = env->prev_insn_idx;
if (is_prune_point(env, env->insn_idx)) {
err = is_state_visited(env, env->insn_idx);
if (err < 0)
return err;
if (err == 1) {
/* found equivalent state, can prune the search */
if (env->log.level & BPF_LOG_LEVEL) {
if (do_print_state)
verbose(env, "\nfrom %d to %d%s: safe\n",
env->prev_insn_idx, env->insn_idx,
env->cur_state->speculative ?
" (speculative execution)" : "");
else
verbose(env, "%d: safe\n", env->insn_idx);
}
goto process_bpf_exit;
}
}
if (is_jmp_point(env, env->insn_idx)) {
err = push_jmp_history(env, state, 0, 0);
if (err)
return err;
}
if (signal_pending(current))
return -EAGAIN;
if (need_resched())
cond_resched();
if (env->log.level & BPF_LOG_LEVEL2 && do_print_state) {
verbose(env, "\nfrom %d to %d%s:",
env->prev_insn_idx, env->insn_idx,
env->cur_state->speculative ?
" (speculative execution)" : "");
print_verifier_state(env, state->frame[state->curframe], true);
do_print_state = false;
}
if (env->log.level & BPF_LOG_LEVEL) {
const struct bpf_insn_cbs cbs = {
.cb_call = disasm_kfunc_name,
.cb_print = verbose,
.private_data = env,
};
if (verifier_state_scratched(env))
print_insn_state(env, state->frame[state->curframe]);
verbose_linfo(env, env->insn_idx, "; ");
env->prev_log_pos = env->log.end_pos;
verbose(env, "%d: ", env->insn_idx);
print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
env->prev_insn_print_pos = env->log.end_pos - env->prev_log_pos;
env->prev_log_pos = env->log.end_pos;
}
if (bpf_prog_is_offloaded(env->prog->aux)) {
err = bpf_prog_offload_verify_insn(env, env->insn_idx,
env->prev_insn_idx);
if (err)
return err;
}
regs = cur_regs(env);
sanitize_mark_insn_seen(env);
prev_insn_idx = env->insn_idx;
if (class == BPF_ALU || class == BPF_ALU64) {
err = check_alu_op(env, insn);
if (err)
return err;
} else if (class == BPF_LDX) {
enum bpf_reg_type src_reg_type;
/* check for reserved fields is already done */
/* check src operand */
err = check_reg_arg(env, insn->src_reg, SRC_OP);
if (err)
return err;
err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
if (err)
return err;
src_reg_type = regs[insn->src_reg].type;
/* check that memory (src_reg + off) is readable,
* the state of dst_reg will be updated by this func
*/
err = check_mem_access(env, env->insn_idx, insn->src_reg,
insn->off, BPF_SIZE(insn->code),
BPF_READ, insn->dst_reg, false,
BPF_MODE(insn->code) == BPF_MEMSX);
err = err ?: save_aux_ptr_type(env, src_reg_type, true);
err = err ?: reg_bounds_sanity_check(env, ®s[insn->dst_reg], "ldx");
if (err)
return err;
} else if (class == BPF_STX) {
enum bpf_reg_type dst_reg_type;
if (BPF_MODE(insn->code) == BPF_ATOMIC) {
err = check_atomic(env, env->insn_idx, insn);
if (err)
return err;
env->insn_idx++;
continue;
}
if (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0) {
verbose(env, "BPF_STX uses reserved fields\n");
return -EINVAL;
}
/* check src1 operand */
err = check_reg_arg(env, insn->src_reg, SRC_OP);
if (err)
return err;
/* check src2 operand */
err = check_reg_arg(env, insn->dst_reg, SRC_OP);
if (err)
return err;
dst_reg_type = regs[insn->dst_reg].type;
/* check that memory (dst_reg + off) is writeable */
err = check_mem_access(env, env->insn_idx, insn->dst_reg,
insn->off, BPF_SIZE(insn->code),
BPF_WRITE, insn->src_reg, false, false);
if (err)
return err;
err = save_aux_ptr_type(env, dst_reg_type, false);
if (err)
return err;
} else if (class == BPF_ST) {
enum bpf_reg_type dst_reg_type;
if (BPF_MODE(insn->code) != BPF_MEM ||
insn->src_reg != BPF_REG_0) {
verbose(env, "BPF_ST uses reserved fields\n");
return -EINVAL;
}
/* check src operand */
err = check_reg_arg(env, insn->dst_reg, SRC_OP);
if (err)
return err;
dst_reg_type = regs[insn->dst_reg].type;
/* check that memory (dst_reg + off) is writeable */
err = check_mem_access(env, env->insn_idx, insn->dst_reg,
insn->off, BPF_SIZE(insn->code),
BPF_WRITE, -1, false, false);
if (err)
return err;
err = save_aux_ptr_type(env, dst_reg_type, false);
if (err)
return err;
} else if (class == BPF_JMP || class == BPF_JMP32) {
u8 opcode = BPF_OP(insn->code);
env->jmps_processed++;
if (opcode == BPF_CALL) {
if (BPF_SRC(insn->code) != BPF_K ||
(insn->src_reg != BPF_PSEUDO_KFUNC_CALL
&& insn->off != 0) ||
(insn->src_reg != BPF_REG_0 &&
insn->src_reg != BPF_PSEUDO_CALL &&
insn->src_reg != BPF_PSEUDO_KFUNC_CALL) ||
insn->dst_reg != BPF_REG_0 ||
class == BPF_JMP32) {
verbose(env, "BPF_CALL uses reserved fields\n");
return -EINVAL;
}
if (env->cur_state->active_lock.ptr) {
if ((insn->src_reg == BPF_REG_0 && insn->imm != BPF_FUNC_spin_unlock) ||
(insn->src_reg == BPF_PSEUDO_KFUNC_CALL &&
(insn->off != 0 || !is_bpf_graph_api_kfunc(insn->imm)))) {
verbose(env, "function calls are not allowed while holding a lock\n");
return -EINVAL;
}
}
if (insn->src_reg == BPF_PSEUDO_CALL) {
err = check_func_call(env, insn, &env->insn_idx);
} else if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) {
err = check_kfunc_call(env, insn, &env->insn_idx);
if (!err && is_bpf_throw_kfunc(insn)) {
exception_exit = true;
goto process_bpf_exit_full;
}
} else {
err = check_helper_call(env, insn, &env->insn_idx);
}
if (err)
return err;
mark_reg_scratched(env, BPF_REG_0);
} else if (opcode == BPF_JA) {
if (BPF_SRC(insn->code) != BPF_K ||
insn->src_reg != BPF_REG_0 ||
insn->dst_reg != BPF_REG_0 ||
(class == BPF_JMP && insn->imm != 0) ||
(class == BPF_JMP32 && insn->off != 0)) {
verbose(env, "BPF_JA uses reserved fields\n");
return -EINVAL;
}
if (class == BPF_JMP)
env->insn_idx += insn->off + 1;
else
env->insn_idx += insn->imm + 1;
continue;
} else if (opcode == BPF_EXIT) {
if (BPF_SRC(insn->code) != BPF_K ||
insn->imm != 0 ||
insn->src_reg != BPF_REG_0 ||
insn->dst_reg != BPF_REG_0 ||
class == BPF_JMP32) {
verbose(env, "BPF_EXIT uses reserved fields\n");
return -EINVAL;
}
process_bpf_exit_full:
if (env->cur_state->active_lock.ptr && !env->cur_state->curframe) {
verbose(env, "bpf_spin_unlock is missing\n");
return -EINVAL;
}
if (env->cur_state->active_rcu_lock && !env->cur_state->curframe) {
verbose(env, "bpf_rcu_read_unlock is missing\n");
return -EINVAL;
}
if (env->cur_state->active_preempt_lock && !env->cur_state->curframe) {
verbose(env, "%d bpf_preempt_enable%s missing\n",
env->cur_state->active_preempt_lock,
env->cur_state->active_preempt_lock == 1 ? " is" : "(s) are");
return -EINVAL;
}
/* We must do check_reference_leak here before
* prepare_func_exit to handle the case when
* state->curframe > 0, it may be a callback
* function, for which reference_state must
* match caller reference state when it exits.
*/
err = check_reference_leak(env, exception_exit);
if (err)
return err;
/* The side effect of the prepare_func_exit
* which is being skipped is that it frees
* bpf_func_state. Typically, process_bpf_exit
* will only be hit with outermost exit.
* copy_verifier_state in pop_stack will handle
* freeing of any extra bpf_func_state left over
* from not processing all nested function
* exits. We also skip return code checks as
* they are not needed for exceptional exits.
*/
if (exception_exit)
goto process_bpf_exit;
if (state->curframe) {
/* exit from nested function */
err = prepare_func_exit(env, &env->insn_idx);
if (err)
return err;
do_print_state = true;
continue;
}
err = check_return_code(env, BPF_REG_0, "R0");
if (err)
return err;
process_bpf_exit:
mark_verifier_state_scratched(env);
update_branch_counts(env, env->cur_state);
err = pop_stack(env, &prev_insn_idx,
&env->insn_idx, pop_log);
if (err < 0) {
if (err != -ENOENT)
return err;
break;
} else {
do_print_state = true;
continue;
}
} else {
err = check_cond_jmp_op(env, insn, &env->insn_idx);
if (err)
return err;
}
} else if (class == BPF_LD) {
u8 mode = BPF_MODE(insn->code);
if (mode == BPF_ABS || mode == BPF_IND) {
err = check_ld_abs(env, insn);
if (err)
return err;
} else if (mode == BPF_IMM) {
err = check_ld_imm(env, insn);
if (err)
return err;
env->insn_idx++;
sanitize_mark_insn_seen(env);
} else {
verbose(env, "invalid BPF_LD mode\n");
return -EINVAL;
}
} else {
verbose(env, "unknown insn class %d\n", class);
return -EINVAL;
}
env->insn_idx++;
}
return 0;
}
static int find_btf_percpu_datasec(struct btf *btf)
{
const struct btf_type *t;
const char *tname;
int i, n;
/*
* Both vmlinux and module each have their own ".data..percpu"
* DATASECs in BTF. So for module's case, we need to skip vmlinux BTF
* types to look at only module's own BTF types.
*/
n = btf_nr_types(btf);
if (btf_is_module(btf))
i = btf_nr_types(btf_vmlinux);
else
i = 1;
for(; i < n; i++) {
t = btf_type_by_id(btf, i);
if (BTF_INFO_KIND(t->info) != BTF_KIND_DATASEC)
continue;
tname = btf_name_by_offset(btf, t->name_off);
if (!strcmp(tname, ".data..percpu"))
return i;
}
return -ENOENT;
}
/* replace pseudo btf_id with kernel symbol address */
static int check_pseudo_btf_id(struct bpf_verifier_env *env,
struct bpf_insn *insn,
struct bpf_insn_aux_data *aux)
{
const struct btf_var_secinfo *vsi;
const struct btf_type *datasec;
struct btf_mod_pair *btf_mod;
const struct btf_type *t;
const char *sym_name;
bool percpu = false;
u32 type, id = insn->imm;
struct btf *btf;
s32 datasec_id;
u64 addr;
int i, btf_fd, err;
btf_fd = insn[1].imm;
if (btf_fd) {
btf = btf_get_by_fd(btf_fd);
if (IS_ERR(btf)) {
verbose(env, "invalid module BTF object FD specified.\n");
return -EINVAL;
}
} else {
if (!btf_vmlinux) {
verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n");
return -EINVAL;
}
btf = btf_vmlinux;
btf_get(btf);
}
t = btf_type_by_id(btf, id);
if (!t) {
verbose(env, "ldimm64 insn specifies invalid btf_id %d.\n", id);
err = -ENOENT;
goto err_put;
}
if (!btf_type_is_var(t) && !btf_type_is_func(t)) {
verbose(env, "pseudo btf_id %d in ldimm64 isn't KIND_VAR or KIND_FUNC\n", id);
err = -EINVAL;
goto err_put;
}
sym_name = btf_name_by_offset(btf, t->name_off);
addr = kallsyms_lookup_name(sym_name);
if (!addr) {
verbose(env, "ldimm64 failed to find the address for kernel symbol '%s'.\n",
sym_name);
err = -ENOENT;
goto err_put;
}
insn[0].imm = (u32)addr;
insn[1].imm = addr >> 32;
if (btf_type_is_func(t)) {
aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY;
aux->btf_var.mem_size = 0;
goto check_btf;
}
datasec_id = find_btf_percpu_datasec(btf);
if (datasec_id > 0) {
datasec = btf_type_by_id(btf, datasec_id);
for_each_vsi(i, datasec, vsi) {
if (vsi->type == id) {
percpu = true;
break;
}
}
}
type = t->type;
t = btf_type_skip_modifiers(btf, type, NULL);
if (percpu) {
aux->btf_var.reg_type = PTR_TO_BTF_ID | MEM_PERCPU;
aux->btf_var.btf = btf;
aux->btf_var.btf_id = type;
} else if (!btf_type_is_struct(t)) {
const struct btf_type *ret;
const char *tname;
u32 tsize;
/* resolve the type size of ksym. */
ret = btf_resolve_size(btf, t, &tsize);
if (IS_ERR(ret)) {
tname = btf_name_by_offset(btf, t->name_off);
verbose(env, "ldimm64 unable to resolve the size of type '%s': %ld\n",
tname, PTR_ERR(ret));
err = -EINVAL;
goto err_put;
}
aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY;
aux->btf_var.mem_size = tsize;
} else {
aux->btf_var.reg_type = PTR_TO_BTF_ID;
aux->btf_var.btf = btf;
aux->btf_var.btf_id = type;
}
check_btf:
/* check whether we recorded this BTF (and maybe module) already */
for (i = 0; i < env->used_btf_cnt; i++) {
if (env->used_btfs[i].btf == btf) {
btf_put(btf);
return 0;
}
}
if (env->used_btf_cnt >= MAX_USED_BTFS) {
err = -E2BIG;
goto err_put;
}
btf_mod = &env->used_btfs[env->used_btf_cnt];
btf_mod->btf = btf;
btf_mod->module = NULL;
/* if we reference variables from kernel module, bump its refcount */
if (btf_is_module(btf)) {
btf_mod->module = btf_try_get_module(btf);
if (!btf_mod->module) {
err = -ENXIO;
goto err_put;
}
}
env->used_btf_cnt++;
return 0;
err_put:
btf_put(btf);
return err;
}
static bool is_tracing_prog_type(enum bpf_prog_type type)
{
switch (type) {
case BPF_PROG_TYPE_KPROBE:
case BPF_PROG_TYPE_TRACEPOINT:
case BPF_PROG_TYPE_PERF_EVENT:
case BPF_PROG_TYPE_RAW_TRACEPOINT:
case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
return true;
default:
return false;
}
}
static int check_map_prog_compatibility(struct bpf_verifier_env *env,
struct bpf_map *map,
struct bpf_prog *prog)
{
enum bpf_prog_type prog_type = resolve_prog_type(prog);
if (btf_record_has_field(map->record, BPF_LIST_HEAD) ||
btf_record_has_field(map->record, BPF_RB_ROOT)) {
if (is_tracing_prog_type(prog_type)) {
verbose(env, "tracing progs cannot use bpf_{list_head,rb_root} yet\n");
return -EINVAL;
}
}
if (btf_record_has_field(map->record, BPF_SPIN_LOCK)) {
if (prog_type == BPF_PROG_TYPE_SOCKET_FILTER) {
verbose(env, "socket filter progs cannot use bpf_spin_lock yet\n");
return -EINVAL;
}
if (is_tracing_prog_type(prog_type)) {
verbose(env, "tracing progs cannot use bpf_spin_lock yet\n");
return -EINVAL;
}
}
if (btf_record_has_field(map->record, BPF_TIMER)) {
if (is_tracing_prog_type(prog_type)) {
verbose(env, "tracing progs cannot use bpf_timer yet\n");
return -EINVAL;
}
}
if (btf_record_has_field(map->record, BPF_WORKQUEUE)) {
if (is_tracing_prog_type(prog_type)) {
verbose(env, "tracing progs cannot use bpf_wq yet\n");
return -EINVAL;
}
}
if ((bpf_prog_is_offloaded(prog->aux) || bpf_map_is_offloaded(map)) &&
!bpf_offload_prog_map_match(prog, map)) {
verbose(env, "offload device mismatch between prog and map\n");
return -EINVAL;
}
if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
verbose(env, "bpf_struct_ops map cannot be used in prog\n");
return -EINVAL;
}
if (prog->sleepable)
switch (map->map_type) {
case BPF_MAP_TYPE_HASH:
case BPF_MAP_TYPE_LRU_HASH:
case BPF_MAP_TYPE_ARRAY:
case BPF_MAP_TYPE_PERCPU_HASH:
case BPF_MAP_TYPE_PERCPU_ARRAY:
case BPF_MAP_TYPE_LRU_PERCPU_HASH:
case BPF_MAP_TYPE_ARRAY_OF_MAPS:
case BPF_MAP_TYPE_HASH_OF_MAPS:
case BPF_MAP_TYPE_RINGBUF:
case BPF_MAP_TYPE_USER_RINGBUF:
case BPF_MAP_TYPE_INODE_STORAGE:
case BPF_MAP_TYPE_SK_STORAGE:
case BPF_MAP_TYPE_TASK_STORAGE:
case BPF_MAP_TYPE_CGRP_STORAGE:
case BPF_MAP_TYPE_QUEUE:
case BPF_MAP_TYPE_STACK:
case BPF_MAP_TYPE_ARENA:
break;
default:
verbose(env,
"Sleepable programs can only use array, hash, ringbuf and local storage maps\n");
return -EINVAL;
}
return 0;
}
static bool bpf_map_is_cgroup_storage(struct bpf_map *map)
{
return (map->map_type == BPF_MAP_TYPE_CGROUP_STORAGE ||
map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE);
}
/* Add map behind fd to used maps list, if it's not already there, and return
* its index. Also set *reused to true if this map was already in the list of
* used maps.
* Returns <0 on error, or >= 0 index, on success.
*/
static int add_used_map_from_fd(struct bpf_verifier_env *env, int fd, bool *reused)
{
CLASS(fd, f)(fd);
struct bpf_map *map;
int i;
map = __bpf_map_get(f);
if (IS_ERR(map)) {
verbose(env, "fd %d is not pointing to valid bpf_map\n", fd);
return PTR_ERR(map);
}
/* check whether we recorded this map already */
for (i = 0; i < env->used_map_cnt; i++) {
if (env->used_maps[i] == map) {
*reused = true;
return i;
}
}
if (env->used_map_cnt >= MAX_USED_MAPS) {
verbose(env, "The total number of maps per program has reached the limit of %u\n",
MAX_USED_MAPS);
return -E2BIG;
}
if (env->prog->sleepable)
atomic64_inc(&map->sleepable_refcnt);
/* hold the map. If the program is rejected by verifier,
* the map will be released by release_maps() or it
* will be used by the valid program until it's unloaded
* and all maps are released in bpf_free_used_maps()
*/
bpf_map_inc(map);
*reused = false;
env->used_maps[env->used_map_cnt++] = map;
return env->used_map_cnt - 1;
}
/* find and rewrite pseudo imm in ld_imm64 instructions:
*
* 1. if it accesses map FD, replace it with actual map pointer.
* 2. if it accesses btf_id of a VAR, replace it with pointer to the var.
*
* NOTE: btf_vmlinux is required for converting pseudo btf_id.
*/
static int resolve_pseudo_ldimm64(struct bpf_verifier_env *env)
{
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
int i, err;
err = bpf_prog_calc_tag(env->prog);
if (err)
return err;
for (i = 0; i < insn_cnt; i++, insn++) {
if (BPF_CLASS(insn->code) == BPF_LDX &&
((BPF_MODE(insn->code) != BPF_MEM && BPF_MODE(insn->code) != BPF_MEMSX) ||
insn->imm != 0)) {
verbose(env, "BPF_LDX uses reserved fields\n");
return -EINVAL;
}
if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
struct bpf_insn_aux_data *aux;
struct bpf_map *map;
int map_idx;
u64 addr;
u32 fd;
bool reused;
if (i == insn_cnt - 1 || insn[1].code != 0 ||
insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
insn[1].off != 0) {
verbose(env, "invalid bpf_ld_imm64 insn\n");
return -EINVAL;
}
if (insn[0].src_reg == 0)
/* valid generic load 64-bit imm */
goto next_insn;
if (insn[0].src_reg == BPF_PSEUDO_BTF_ID) {
aux = &env->insn_aux_data[i];
err = check_pseudo_btf_id(env, insn, aux);
if (err)
return err;
goto next_insn;
}
if (insn[0].src_reg == BPF_PSEUDO_FUNC) {
aux = &env->insn_aux_data[i];
aux->ptr_type = PTR_TO_FUNC;
goto next_insn;
}
/* In final convert_pseudo_ld_imm64() step, this is
* converted into regular 64-bit imm load insn.
*/
switch (insn[0].src_reg) {
case BPF_PSEUDO_MAP_VALUE:
case BPF_PSEUDO_MAP_IDX_VALUE:
break;
case BPF_PSEUDO_MAP_FD:
case BPF_PSEUDO_MAP_IDX:
if (insn[1].imm == 0)
break;
fallthrough;
default:
verbose(env, "unrecognized bpf_ld_imm64 insn\n");
return -EINVAL;
}
switch (insn[0].src_reg) {
case BPF_PSEUDO_MAP_IDX_VALUE:
case BPF_PSEUDO_MAP_IDX:
if (bpfptr_is_null(env->fd_array)) {
verbose(env, "fd_idx without fd_array is invalid\n");
return -EPROTO;
}
if (copy_from_bpfptr_offset(&fd, env->fd_array,
insn[0].imm * sizeof(fd),
sizeof(fd)))
return -EFAULT;
break;
default:
fd = insn[0].imm;
break;
}
map_idx = add_used_map_from_fd(env, fd, &reused);
if (map_idx < 0)
return map_idx;
map = env->used_maps[map_idx];
aux = &env->insn_aux_data[i];
aux->map_index = map_idx;
err = check_map_prog_compatibility(env, map, env->prog);
if (err)
return err;
if (insn[0].src_reg == BPF_PSEUDO_MAP_FD ||
insn[0].src_reg == BPF_PSEUDO_MAP_IDX) {
addr = (unsigned long)map;
} else {
u32 off = insn[1].imm;
if (off >= BPF_MAX_VAR_OFF) {
verbose(env, "direct value offset of %u is not allowed\n", off);
return -EINVAL;
}
if (!map->ops->map_direct_value_addr) {
verbose(env, "no direct value access support for this map type\n");
return -EINVAL;
}
err = map->ops->map_direct_value_addr(map, &addr, off);
if (err) {
verbose(env, "invalid access to map value pointer, value_size=%u off=%u\n",
map->value_size, off);
return err;
}
aux->map_off = off;
addr += off;
}
insn[0].imm = (u32)addr;
insn[1].imm = addr >> 32;
/* proceed with extra checks only if its newly added used map */
if (reused)
goto next_insn;
if (bpf_map_is_cgroup_storage(map) &&
bpf_cgroup_storage_assign(env->prog->aux, map)) {
verbose(env, "only one cgroup storage of each type is allowed\n");
return -EBUSY;
}
if (map->map_type == BPF_MAP_TYPE_ARENA) {
if (env->prog->aux->arena) {
verbose(env, "Only one arena per program\n");
return -EBUSY;
}
if (!env->allow_ptr_leaks || !env->bpf_capable) {
verbose(env, "CAP_BPF and CAP_PERFMON are required to use arena\n");
return -EPERM;
}
if (!env->prog->jit_requested) {
verbose(env, "JIT is required to use arena\n");
return -EOPNOTSUPP;
}
if (!bpf_jit_supports_arena()) {
verbose(env, "JIT doesn't support arena\n");
return -EOPNOTSUPP;
}
env->prog->aux->arena = (void *)map;
if (!bpf_arena_get_user_vm_start(env->prog->aux->arena)) {
verbose(env, "arena's user address must be set via map_extra or mmap()\n");
return -EINVAL;
}
}
next_insn:
insn++;
i++;
continue;
}
/* Basic sanity check before we invest more work here. */
if (!bpf_opcode_in_insntable(insn->code)) {
verbose(env, "unknown opcode %02x\n", insn->code);
return -EINVAL;
}
}
/* now all pseudo BPF_LD_IMM64 instructions load valid
* 'struct bpf_map *' into a register instead of user map_fd.
* These pointers will be used later by verifier to validate map access.
*/
return 0;
}
/* drop refcnt of maps used by the rejected program */
static void release_maps(struct bpf_verifier_env *env)
{
__bpf_free_used_maps(env->prog->aux, env->used_maps,
env->used_map_cnt);
}
/* drop refcnt of maps used by the rejected program */
static void release_btfs(struct bpf_verifier_env *env)
{
__bpf_free_used_btfs(env->used_btfs, env->used_btf_cnt);
}
/* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
{
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
int i;
for (i = 0; i < insn_cnt; i++, insn++) {
if (insn->code != (BPF_LD | BPF_IMM | BPF_DW))
continue;
if (insn->src_reg == BPF_PSEUDO_FUNC)
continue;
insn->src_reg = 0;
}
}
/* single env->prog->insni[off] instruction was replaced with the range
* insni[off, off + cnt). Adjust corresponding insn_aux_data by copying
* [0, off) and [off, end) to new locations, so the patched range stays zero
*/
static void adjust_insn_aux_data(struct bpf_verifier_env *env,
struct bpf_insn_aux_data *new_data,
struct bpf_prog *new_prog, u32 off, u32 cnt)
{
struct bpf_insn_aux_data *old_data = env->insn_aux_data;
struct bpf_insn *insn = new_prog->insnsi;
u32 old_seen = old_data[off].seen;
u32 prog_len;
int i;
/* aux info at OFF always needs adjustment, no matter fast path
* (cnt == 1) is taken or not. There is no guarantee INSN at OFF is the
* original insn at old prog.
*/
old_data[off].zext_dst = insn_has_def32(env, insn + off + cnt - 1);
if (cnt == 1)
return;
prog_len = new_prog->len;
memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
memcpy(new_data + off + cnt - 1, old_data + off,
sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
for (i = off; i < off + cnt - 1; i++) {
/* Expand insni[off]'s seen count to the patched range. */
new_data[i].seen = old_seen;
new_data[i].zext_dst = insn_has_def32(env, insn + i);
}
env->insn_aux_data = new_data;
vfree(old_data);
}
static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len)
{
int i;
if (len == 1)
return;
/* NOTE: fake 'exit' subprog should be updated as well. */
for (i = 0; i <= env->subprog_cnt; i++) {
if (env->subprog_info[i].start <= off)
continue;
env->subprog_info[i].start += len - 1;
}
}
static void adjust_poke_descs(struct bpf_prog *prog, u32 off, u32 len)
{
struct bpf_jit_poke_descriptor *tab = prog->aux->poke_tab;
int i, sz = prog->aux->size_poke_tab;
struct bpf_jit_poke_descriptor *desc;
for (i = 0; i < sz; i++) {
desc = &tab[i];
if (desc->insn_idx <= off)
continue;
desc->insn_idx += len - 1;
}
}
static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off,
const struct bpf_insn *patch, u32 len)
{
struct bpf_prog *new_prog;
struct bpf_insn_aux_data *new_data = NULL;
if (len > 1) {
new_data = vzalloc(array_size(env->prog->len + len - 1,
sizeof(struct bpf_insn_aux_data)));
if (!new_data)
return NULL;
}
new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
if (IS_ERR(new_prog)) {
if (PTR_ERR(new_prog) == -ERANGE)
verbose(env,
"insn %d cannot be patched due to 16-bit range\n",
env->insn_aux_data[off].orig_idx);
vfree(new_data);
return NULL;
}
adjust_insn_aux_data(env, new_data, new_prog, off, len);
adjust_subprog_starts(env, off, len);
adjust_poke_descs(new_prog, off, len);
return new_prog;
}
/*
* For all jmp insns in a given 'prog' that point to 'tgt_idx' insn adjust the
* jump offset by 'delta'.
*/
static int adjust_jmp_off(struct bpf_prog *prog, u32 tgt_idx, u32 delta)
{
struct bpf_insn *insn = prog->insnsi;
u32 insn_cnt = prog->len, i;
s32 imm;
s16 off;
for (i = 0; i < insn_cnt; i++, insn++) {
u8 code = insn->code;
if (tgt_idx <= i && i < tgt_idx + delta)
continue;
if ((BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32) ||
BPF_OP(code) == BPF_CALL || BPF_OP(code) == BPF_EXIT)
continue;
if (insn->code == (BPF_JMP32 | BPF_JA)) {
if (i + 1 + insn->imm != tgt_idx)
continue;
if (check_add_overflow(insn->imm, delta, &imm))
return -ERANGE;
insn->imm = imm;
} else {
if (i + 1 + insn->off != tgt_idx)
continue;
if (check_add_overflow(insn->off, delta, &off))
return -ERANGE;
insn->off = off;
}
}
return 0;
}
static int adjust_subprog_starts_after_remove(struct bpf_verifier_env *env,
u32 off, u32 cnt)
{
int i, j;
/* find first prog starting at or after off (first to remove) */
for (i = 0; i < env->subprog_cnt; i++)
if (env->subprog_info[i].start >= off)
break;
/* find first prog starting at or after off + cnt (first to stay) */
for (j = i; j < env->subprog_cnt; j++)
if (env->subprog_info[j].start >= off + cnt)
break;
/* if j doesn't start exactly at off + cnt, we are just removing
* the front of previous prog
*/
if (env->subprog_info[j].start != off + cnt)
j--;
if (j > i) {
struct bpf_prog_aux *aux = env->prog->aux;
int move;
/* move fake 'exit' subprog as well */
move = env->subprog_cnt + 1 - j;
memmove(env->subprog_info + i,
env->subprog_info + j,
sizeof(*env->subprog_info) * move);
env->subprog_cnt -= j - i;
/* remove func_info */
if (aux->func_info) {
move = aux->func_info_cnt - j;
memmove(aux->func_info + i,
aux->func_info + j,
sizeof(*aux->func_info) * move);
aux->func_info_cnt -= j - i;
/* func_info->insn_off is set after all code rewrites,
* in adjust_btf_func() - no need to adjust
*/
}
} else {
/* convert i from "first prog to remove" to "first to adjust" */
if (env->subprog_info[i].start == off)
i++;
}
/* update fake 'exit' subprog as well */
for (; i <= env->subprog_cnt; i++)
env->subprog_info[i].start -= cnt;
return 0;
}
static int bpf_adj_linfo_after_remove(struct bpf_verifier_env *env, u32 off,
u32 cnt)
{
struct bpf_prog *prog = env->prog;
u32 i, l_off, l_cnt, nr_linfo;
struct bpf_line_info *linfo;
nr_linfo = prog->aux->nr_linfo;
if (!nr_linfo)
return 0;
linfo = prog->aux->linfo;
/* find first line info to remove, count lines to be removed */
for (i = 0; i < nr_linfo; i++)
if (linfo[i].insn_off >= off)
break;
l_off = i;
l_cnt = 0;
for (; i < nr_linfo; i++)
if (linfo[i].insn_off < off + cnt)
l_cnt++;
else
break;
/* First live insn doesn't match first live linfo, it needs to "inherit"
* last removed linfo. prog is already modified, so prog->len == off
* means no live instructions after (tail of the program was removed).
*/
if (prog->len != off && l_cnt &&
(i == nr_linfo || linfo[i].insn_off != off + cnt)) {
l_cnt--;
linfo[--i].insn_off = off + cnt;
}
/* remove the line info which refer to the removed instructions */
if (l_cnt) {
memmove(linfo + l_off, linfo + i,
sizeof(*linfo) * (nr_linfo - i));
prog->aux->nr_linfo -= l_cnt;
nr_linfo = prog->aux->nr_linfo;
}
/* pull all linfo[i].insn_off >= off + cnt in by cnt */
for (i = l_off; i < nr_linfo; i++)
linfo[i].insn_off -= cnt;
/* fix up all subprogs (incl. 'exit') which start >= off */
for (i = 0; i <= env->subprog_cnt; i++)
if (env->subprog_info[i].linfo_idx > l_off) {
/* program may have started in the removed region but
* may not be fully removed
*/
if (env->subprog_info[i].linfo_idx >= l_off + l_cnt)
env->subprog_info[i].linfo_idx -= l_cnt;
else
env->subprog_info[i].linfo_idx = l_off;
}
return 0;
}
static int verifier_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt)
{
struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
unsigned int orig_prog_len = env->prog->len;
int err;
if (bpf_prog_is_offloaded(env->prog->aux))
bpf_prog_offload_remove_insns(env, off, cnt);
err = bpf_remove_insns(env->prog, off, cnt);
if (err)
return err;
err = adjust_subprog_starts_after_remove(env, off, cnt);
if (err)
return err;
err = bpf_adj_linfo_after_remove(env, off, cnt);
if (err)
return err;
memmove(aux_data + off, aux_data + off + cnt,
sizeof(*aux_data) * (orig_prog_len - off - cnt));
return 0;
}
/* The verifier does more data flow analysis than llvm and will not
* explore branches that are dead at run time. Malicious programs can
* have dead code too. Therefore replace all dead at-run-time code
* with 'ja -1'.
*
* Just nops are not optimal, e.g. if they would sit at the end of the
* program and through another bug we would manage to jump there, then
* we'd execute beyond program memory otherwise. Returning exception
* code also wouldn't work since we can have subprogs where the dead
* code could be located.
*/
static void sanitize_dead_code(struct bpf_verifier_env *env)
{
struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
struct bpf_insn trap = BPF_JMP_IMM(BPF_JA, 0, 0, -1);
struct bpf_insn *insn = env->prog->insnsi;
const int insn_cnt = env->prog->len;
int i;
for (i = 0; i < insn_cnt; i++) {
if (aux_data[i].seen)
continue;
memcpy(insn + i, &trap, sizeof(trap));
aux_data[i].zext_dst = false;
}
}
static bool insn_is_cond_jump(u8 code)
{
u8 op;
op = BPF_OP(code);
if (BPF_CLASS(code) == BPF_JMP32)
return op != BPF_JA;
if (BPF_CLASS(code) != BPF_JMP)
return false;
return op != BPF_JA && op != BPF_EXIT && op != BPF_CALL;
}
static void opt_hard_wire_dead_code_branches(struct bpf_verifier_env *env)
{
struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
struct bpf_insn ja = BPF_JMP_IMM(BPF_JA, 0, 0, 0);
struct bpf_insn *insn = env->prog->insnsi;
const int insn_cnt = env->prog->len;
int i;
for (i = 0; i < insn_cnt; i++, insn++) {
if (!insn_is_cond_jump(insn->code))
continue;
if (!aux_data[i + 1].seen)
ja.off = insn->off;
else if (!aux_data[i + 1 + insn->off].seen)
ja.off = 0;
else
continue;
if (bpf_prog_is_offloaded(env->prog->aux))
bpf_prog_offload_replace_insn(env, i, &ja);
memcpy(insn, &ja, sizeof(ja));
}
}
static int opt_remove_dead_code(struct bpf_verifier_env *env)
{
struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
int insn_cnt = env->prog->len;
int i, err;
for (i = 0; i < insn_cnt; i++) {
int j;
j = 0;
while (i + j < insn_cnt && !aux_data[i + j].seen)
j++;
if (!j)
continue;
err = verifier_remove_insns(env, i, j);
if (err)
return err;
insn_cnt = env->prog->len;
}
return 0;
}
static const struct bpf_insn NOP = BPF_JMP_IMM(BPF_JA, 0, 0, 0);
static int opt_remove_nops(struct bpf_verifier_env *env)
{
const struct bpf_insn ja = NOP;
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
int i, err;
for (i = 0; i < insn_cnt; i++) {
if (memcmp(&insn[i], &ja, sizeof(ja)))
continue;
err = verifier_remove_insns(env, i, 1);
if (err)
return err;
insn_cnt--;
i--;
}
return 0;
}
static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env,
const union bpf_attr *attr)
{
struct bpf_insn *patch, zext_patch[2], rnd_hi32_patch[4];
struct bpf_insn_aux_data *aux = env->insn_aux_data;
int i, patch_len, delta = 0, len = env->prog->len;
struct bpf_insn *insns = env->prog->insnsi;
struct bpf_prog *new_prog;
bool rnd_hi32;
rnd_hi32 = attr->prog_flags & BPF_F_TEST_RND_HI32;
zext_patch[1] = BPF_ZEXT_REG(0);
rnd_hi32_patch[1] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, 0);
rnd_hi32_patch[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_AX, 32);
rnd_hi32_patch[3] = BPF_ALU64_REG(BPF_OR, 0, BPF_REG_AX);
for (i = 0; i < len; i++) {
int adj_idx = i + delta;
struct bpf_insn insn;
int load_reg;
insn = insns[adj_idx];
load_reg = insn_def_regno(&insn);
if (!aux[adj_idx].zext_dst) {
u8 code, class;
u32 imm_rnd;
if (!rnd_hi32)
continue;
code = insn.code;
class = BPF_CLASS(code);
if (load_reg == -1)
continue;
/* NOTE: arg "reg" (the fourth one) is only used for
* BPF_STX + SRC_OP, so it is safe to pass NULL
* here.
*/
if (is_reg64(env, &insn, load_reg, NULL, DST_OP)) {
if (class == BPF_LD &&
BPF_MODE(code) == BPF_IMM)
i++;
continue;
}
/* ctx load could be transformed into wider load. */
if (class == BPF_LDX &&
aux[adj_idx].ptr_type == PTR_TO_CTX)
continue;
imm_rnd = get_random_u32();
rnd_hi32_patch[0] = insn;
rnd_hi32_patch[1].imm = imm_rnd;
rnd_hi32_patch[3].dst_reg = load_reg;
patch = rnd_hi32_patch;
patch_len = 4;
goto apply_patch_buffer;
}
/* Add in an zero-extend instruction if a) the JIT has requested
* it or b) it's a CMPXCHG.
*
* The latter is because: BPF_CMPXCHG always loads a value into
* R0, therefore always zero-extends. However some archs'
* equivalent instruction only does this load when the
* comparison is successful. This detail of CMPXCHG is
* orthogonal to the general zero-extension behaviour of the
* CPU, so it's treated independently of bpf_jit_needs_zext.
*/
if (!bpf_jit_needs_zext() && !is_cmpxchg_insn(&insn))
continue;
/* Zero-extension is done by the caller. */
if (bpf_pseudo_kfunc_call(&insn))
continue;
if (WARN_ON(load_reg == -1)) {
verbose(env, "verifier bug. zext_dst is set, but no reg is defined\n");
return -EFAULT;
}
zext_patch[0] = insn;
zext_patch[1].dst_reg = load_reg;
zext_patch[1].src_reg = load_reg;
patch = zext_patch;
patch_len = 2;
apply_patch_buffer:
new_prog = bpf_patch_insn_data(env, adj_idx, patch, patch_len);
if (!new_prog)
return -ENOMEM;
env->prog = new_prog;
insns = new_prog->insnsi;
aux = env->insn_aux_data;
delta += patch_len - 1;
}
return 0;
}
/* convert load instructions that access fields of a context type into a
* sequence of instructions that access fields of the underlying structure:
* struct __sk_buff -> struct sk_buff
* struct bpf_sock_ops -> struct sock
*/
static int convert_ctx_accesses(struct bpf_verifier_env *env)
{
struct bpf_subprog_info *subprogs = env->subprog_info;
const struct bpf_verifier_ops *ops = env->ops;
int i, cnt, size, ctx_field_size, delta = 0, epilogue_cnt = 0;
const int insn_cnt = env->prog->len;
struct bpf_insn *epilogue_buf = env->epilogue_buf;
struct bpf_insn *insn_buf = env->insn_buf;
struct bpf_insn *insn;
u32 target_size, size_default, off;
struct bpf_prog *new_prog;
enum bpf_access_type type;
bool is_narrower_load;
int epilogue_idx = 0;
if (ops->gen_epilogue) {
epilogue_cnt = ops->gen_epilogue(epilogue_buf, env->prog,
-(subprogs[0].stack_depth + 8));
if (epilogue_cnt >= INSN_BUF_SIZE) {
verbose(env, "bpf verifier is misconfigured\n");
return -EINVAL;
} else if (epilogue_cnt) {
/* Save the ARG_PTR_TO_CTX for the epilogue to use */
cnt = 0;
subprogs[0].stack_depth += 8;
insn_buf[cnt++] = BPF_STX_MEM(BPF_DW, BPF_REG_FP, BPF_REG_1,
-subprogs[0].stack_depth);
insn_buf[cnt++] = env->prog->insnsi[0];
new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
env->prog = new_prog;
delta += cnt - 1;
}
}
if (ops->gen_prologue || env->seen_direct_write) {
if (!ops->gen_prologue) {
verbose(env, "bpf verifier is misconfigured\n");
return -EINVAL;
}
cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
env->prog);
if (cnt >= INSN_BUF_SIZE) {
verbose(env, "bpf verifier is misconfigured\n");
return -EINVAL;
} else if (cnt) {
new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
env->prog = new_prog;
delta += cnt - 1;
}
}
if (delta)
WARN_ON(adjust_jmp_off(env->prog, 0, delta));
if (bpf_prog_is_offloaded(env->prog->aux))
return 0;
insn = env->prog->insnsi + delta;
for (i = 0; i < insn_cnt; i++, insn++) {
bpf_convert_ctx_access_t convert_ctx_access;
u8 mode;
if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
insn->code == (BPF_LDX | BPF_MEM | BPF_DW) ||
insn->code == (BPF_LDX | BPF_MEMSX | BPF_B) ||
insn->code == (BPF_LDX | BPF_MEMSX | BPF_H) ||
insn->code == (BPF_LDX | BPF_MEMSX | BPF_W)) {
type = BPF_READ;
} else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) ||
insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
insn->code == (BPF_STX | BPF_MEM | BPF_DW) ||
insn->code == (BPF_ST | BPF_MEM | BPF_B) ||
insn->code == (BPF_ST | BPF_MEM | BPF_H) ||
insn->code == (BPF_ST | BPF_MEM | BPF_W) ||
insn->code == (BPF_ST | BPF_MEM | BPF_DW)) {
type = BPF_WRITE;
} else if ((insn->code == (BPF_STX | BPF_ATOMIC | BPF_W) ||
insn->code == (BPF_STX | BPF_ATOMIC | BPF_DW)) &&
env->insn_aux_data[i + delta].ptr_type == PTR_TO_ARENA) {
insn->code = BPF_STX | BPF_PROBE_ATOMIC | BPF_SIZE(insn->code);
env->prog->aux->num_exentries++;
continue;
} else if (insn->code == (BPF_JMP | BPF_EXIT) &&
epilogue_cnt &&
i + delta < subprogs[1].start) {
/* Generate epilogue for the main prog */
if (epilogue_idx) {
/* jump back to the earlier generated epilogue */
insn_buf[0] = BPF_JMP32_A(epilogue_idx - i - delta - 1);
cnt = 1;
} else {
memcpy(insn_buf, epilogue_buf,
epilogue_cnt * sizeof(*epilogue_buf));
cnt = epilogue_cnt;
/* epilogue_idx cannot be 0. It must have at
* least one ctx ptr saving insn before the
* epilogue.
*/
epilogue_idx = i + delta;
}
goto patch_insn_buf;
} else {
continue;
}
if (type == BPF_WRITE &&
env->insn_aux_data[i + delta].sanitize_stack_spill) {
struct bpf_insn patch[] = {
*insn,
BPF_ST_NOSPEC(),
};
cnt = ARRAY_SIZE(patch);
new_prog = bpf_patch_insn_data(env, i + delta, patch, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = new_prog;
insn = new_prog->insnsi + i + delta;
continue;
}
switch ((int)env->insn_aux_data[i + delta].ptr_type) {
case PTR_TO_CTX:
if (!ops->convert_ctx_access)
continue;
convert_ctx_access = ops->convert_ctx_access;
break;
case PTR_TO_SOCKET:
case PTR_TO_SOCK_COMMON:
convert_ctx_access = bpf_sock_convert_ctx_access;
break;
case PTR_TO_TCP_SOCK:
convert_ctx_access = bpf_tcp_sock_convert_ctx_access;
break;
case PTR_TO_XDP_SOCK:
convert_ctx_access = bpf_xdp_sock_convert_ctx_access;
break;
case PTR_TO_BTF_ID:
case PTR_TO_BTF_ID | PTR_UNTRUSTED:
/* PTR_TO_BTF_ID | MEM_ALLOC always has a valid lifetime, unlike
* PTR_TO_BTF_ID, and an active ref_obj_id, but the same cannot
* be said once it is marked PTR_UNTRUSTED, hence we must handle
* any faults for loads into such types. BPF_WRITE is disallowed
* for this case.
*/
case PTR_TO_BTF_ID | MEM_ALLOC | PTR_UNTRUSTED:
if (type == BPF_READ) {
if (BPF_MODE(insn->code) == BPF_MEM)
insn->code = BPF_LDX | BPF_PROBE_MEM |
BPF_SIZE((insn)->code);
else
insn->code = BPF_LDX | BPF_PROBE_MEMSX |
BPF_SIZE((insn)->code);
env->prog->aux->num_exentries++;
}
continue;
case PTR_TO_ARENA:
if (BPF_MODE(insn->code) == BPF_MEMSX) {
verbose(env, "sign extending loads from arena are not supported yet\n");
return -EOPNOTSUPP;
}
insn->code = BPF_CLASS(insn->code) | BPF_PROBE_MEM32 | BPF_SIZE(insn->code);
env->prog->aux->num_exentries++;
continue;
default:
continue;
}
ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size;
size = BPF_LDST_BYTES(insn);
mode = BPF_MODE(insn->code);
/* If the read access is a narrower load of the field,
* convert to a 4/8-byte load, to minimum program type specific
* convert_ctx_access changes. If conversion is successful,
* we will apply proper mask to the result.
*/
is_narrower_load = size < ctx_field_size;
size_default = bpf_ctx_off_adjust_machine(ctx_field_size);
off = insn->off;
if (is_narrower_load) {
u8 size_code;
if (type == BPF_WRITE) {
verbose(env, "bpf verifier narrow ctx access misconfigured\n");
return -EINVAL;
}
size_code = BPF_H;
if (ctx_field_size == 4)
size_code = BPF_W;
else if (ctx_field_size == 8)
size_code = BPF_DW;
insn->off = off & ~(size_default - 1);
insn->code = BPF_LDX | BPF_MEM | size_code;
}
target_size = 0;
cnt = convert_ctx_access(type, insn, insn_buf, env->prog,
&target_size);
if (cnt == 0 || cnt >= INSN_BUF_SIZE ||
(ctx_field_size && !target_size)) {
verbose(env, "bpf verifier is misconfigured\n");
return -EINVAL;
}
if (is_narrower_load && size < target_size) {
u8 shift = bpf_ctx_narrow_access_offset(
off, size, size_default) * 8;
if (shift && cnt + 1 >= INSN_BUF_SIZE) {
verbose(env, "bpf verifier narrow ctx load misconfigured\n");
return -EINVAL;
}
if (ctx_field_size <= 4) {
if (shift)
insn_buf[cnt++] = BPF_ALU32_IMM(BPF_RSH,
insn->dst_reg,
shift);
insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
(1 << size * 8) - 1);
} else {
if (shift)
insn_buf[cnt++] = BPF_ALU64_IMM(BPF_RSH,
insn->dst_reg,
shift);
insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
(1ULL << size * 8) - 1);
}
}
if (mode == BPF_MEMSX)
insn_buf[cnt++] = BPF_RAW_INSN(BPF_ALU64 | BPF_MOV | BPF_X,
insn->dst_reg, insn->dst_reg,
size * 8, 0);
patch_insn_buf:
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
/* keep walking new program and skip insns we just inserted */
env->prog = new_prog;
insn = new_prog->insnsi + i + delta;
}
return 0;
}
static int jit_subprogs(struct bpf_verifier_env *env)
{
struct bpf_prog *prog = env->prog, **func, *tmp;
int i, j, subprog_start, subprog_end = 0, len, subprog;
struct bpf_map *map_ptr;
struct bpf_insn *insn;
void *old_bpf_func;
int err, num_exentries;
if (env->subprog_cnt <= 1)
return 0;
for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn))
continue;
/* Upon error here we cannot fall back to interpreter but
* need a hard reject of the program. Thus -EFAULT is
* propagated in any case.
*/
subprog = find_subprog(env, i + insn->imm + 1);
if (subprog < 0) {
WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
i + insn->imm + 1);
return -EFAULT;
}
/* temporarily remember subprog id inside insn instead of
* aux_data, since next loop will split up all insns into funcs
*/
insn->off = subprog;
/* remember original imm in case JIT fails and fallback
* to interpreter will be needed
*/
env->insn_aux_data[i].call_imm = insn->imm;
/* point imm to __bpf_call_base+1 from JITs point of view */
insn->imm = 1;
if (bpf_pseudo_func(insn)) {
#if defined(MODULES_VADDR)
u64 addr = MODULES_VADDR;
#else
u64 addr = VMALLOC_START;
#endif
/* jit (e.g. x86_64) may emit fewer instructions
* if it learns a u32 imm is the same as a u64 imm.
* Set close enough to possible prog address.
*/
insn[0].imm = (u32)addr;
insn[1].imm = addr >> 32;
}
}
err = bpf_prog_alloc_jited_linfo(prog);
if (err)
goto out_undo_insn;
err = -ENOMEM;
func = kcalloc(env->subprog_cnt, sizeof(prog), GFP_KERNEL);
if (!func)
goto out_undo_insn;
for (i = 0; i < env->subprog_cnt; i++) {
subprog_start = subprog_end;
subprog_end = env->subprog_info[i + 1].start;
len = subprog_end - subprog_start;
/* bpf_prog_run() doesn't call subprogs directly,
* hence main prog stats include the runtime of subprogs.
* subprogs don't have IDs and not reachable via prog_get_next_id
* func[i]->stats will never be accessed and stays NULL
*/
func[i] = bpf_prog_alloc_no_stats(bpf_prog_size(len), GFP_USER);
if (!func[i])
goto out_free;
memcpy(func[i]->insnsi, &prog->insnsi[subprog_start],
len * sizeof(struct bpf_insn));
func[i]->type = prog->type;
func[i]->len = len;
if (bpf_prog_calc_tag(func[i]))
goto out_free;
func[i]->is_func = 1;
func[i]->sleepable = prog->sleepable;
func[i]->aux->func_idx = i;
/* Below members will be freed only at prog->aux */
func[i]->aux->btf = prog->aux->btf;
func[i]->aux->func_info = prog->aux->func_info;
func[i]->aux->func_info_cnt = prog->aux->func_info_cnt;
func[i]->aux->poke_tab = prog->aux->poke_tab;
func[i]->aux->size_poke_tab = prog->aux->size_poke_tab;
for (j = 0; j < prog->aux->size_poke_tab; j++) {
struct bpf_jit_poke_descriptor *poke;
poke = &prog->aux->poke_tab[j];
if (poke->insn_idx < subprog_end &&
poke->insn_idx >= subprog_start)
poke->aux = func[i]->aux;
}
func[i]->aux->name[0] = 'F';
func[i]->aux->stack_depth = env->subprog_info[i].stack_depth;
func[i]->jit_requested = 1;
func[i]->blinding_requested = prog->blinding_requested;
func[i]->aux->kfunc_tab = prog->aux->kfunc_tab;
func[i]->aux->kfunc_btf_tab = prog->aux->kfunc_btf_tab;
func[i]->aux->linfo = prog->aux->linfo;
func[i]->aux->nr_linfo = prog->aux->nr_linfo;
func[i]->aux->jited_linfo = prog->aux->jited_linfo;
func[i]->aux->linfo_idx = env->subprog_info[i].linfo_idx;
func[i]->aux->arena = prog->aux->arena;
num_exentries = 0;
insn = func[i]->insnsi;
for (j = 0; j < func[i]->len; j++, insn++) {
if (BPF_CLASS(insn->code) == BPF_LDX &&
(BPF_MODE(insn->code) == BPF_PROBE_MEM ||
BPF_MODE(insn->code) == BPF_PROBE_MEM32 ||
BPF_MODE(insn->code) == BPF_PROBE_MEMSX))
num_exentries++;
if ((BPF_CLASS(insn->code) == BPF_STX ||
BPF_CLASS(insn->code) == BPF_ST) &&
BPF_MODE(insn->code) == BPF_PROBE_MEM32)
num_exentries++;
if (BPF_CLASS(insn->code) == BPF_STX &&
BPF_MODE(insn->code) == BPF_PROBE_ATOMIC)
num_exentries++;
}
func[i]->aux->num_exentries = num_exentries;
func[i]->aux->tail_call_reachable = env->subprog_info[i].tail_call_reachable;
func[i]->aux->exception_cb = env->subprog_info[i].is_exception_cb;
if (!i)
func[i]->aux->exception_boundary = env->seen_exception;
func[i] = bpf_int_jit_compile(func[i]);
if (!func[i]->jited) {
err = -ENOTSUPP;
goto out_free;
}
cond_resched();
}
/* at this point all bpf functions were successfully JITed
* now populate all bpf_calls with correct addresses and
* run last pass of JIT
*/
for (i = 0; i < env->subprog_cnt; i++) {
insn = func[i]->insnsi;
for (j = 0; j < func[i]->len; j++, insn++) {
if (bpf_pseudo_func(insn)) {
subprog = insn->off;
insn[0].imm = (u32)(long)func[subprog]->bpf_func;
insn[1].imm = ((u64)(long)func[subprog]->bpf_func) >> 32;
continue;
}
if (!bpf_pseudo_call(insn))
continue;
subprog = insn->off;
insn->imm = BPF_CALL_IMM(func[subprog]->bpf_func);
}
/* we use the aux data to keep a list of the start addresses
* of the JITed images for each function in the program
*
* for some architectures, such as powerpc64, the imm field
* might not be large enough to hold the offset of the start
* address of the callee's JITed image from __bpf_call_base
*
* in such cases, we can lookup the start address of a callee
* by using its subprog id, available from the off field of
* the call instruction, as an index for this list
*/
func[i]->aux->func = func;
func[i]->aux->func_cnt = env->subprog_cnt - env->hidden_subprog_cnt;
func[i]->aux->real_func_cnt = env->subprog_cnt;
}
for (i = 0; i < env->subprog_cnt; i++) {
old_bpf_func = func[i]->bpf_func;
tmp = bpf_int_jit_compile(func[i]);
if (tmp != func[i] || func[i]->bpf_func != old_bpf_func) {
verbose(env, "JIT doesn't support bpf-to-bpf calls\n");
err = -ENOTSUPP;
goto out_free;
}
cond_resched();
}
/* finally lock prog and jit images for all functions and
* populate kallsysm. Begin at the first subprogram, since
* bpf_prog_load will add the kallsyms for the main program.
*/
for (i = 1; i < env->subprog_cnt; i++) {
err = bpf_prog_lock_ro(func[i]);
if (err)
goto out_free;
}
for (i = 1; i < env->subprog_cnt; i++)
bpf_prog_kallsyms_add(func[i]);
/* Last step: make now unused interpreter insns from main
* prog consistent for later dump requests, so they can
* later look the same as if they were interpreted only.
*/
for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
if (bpf_pseudo_func(insn)) {
insn[0].imm = env->insn_aux_data[i].call_imm;
insn[1].imm = insn->off;
insn->off = 0;
continue;
}
if (!bpf_pseudo_call(insn))
continue;
insn->off = env->insn_aux_data[i].call_imm;
subprog = find_subprog(env, i + insn->off + 1);
insn->imm = subprog;
}
prog->jited = 1;
prog->bpf_func = func[0]->bpf_func;
prog->jited_len = func[0]->jited_len;
prog->aux->extable = func[0]->aux->extable;
prog->aux->num_exentries = func[0]->aux->num_exentries;
prog->aux->func = func;
prog->aux->func_cnt = env->subprog_cnt - env->hidden_subprog_cnt;
prog->aux->real_func_cnt = env->subprog_cnt;
prog->aux->bpf_exception_cb = (void *)func[env->exception_callback_subprog]->bpf_func;
prog->aux->exception_boundary = func[0]->aux->exception_boundary;
bpf_prog_jit_attempt_done(prog);
return 0;
out_free:
/* We failed JIT'ing, so at this point we need to unregister poke
* descriptors from subprogs, so that kernel is not attempting to
* patch it anymore as we're freeing the subprog JIT memory.
*/
for (i = 0; i < prog->aux->size_poke_tab; i++) {
map_ptr = prog->aux->poke_tab[i].tail_call.map;
map_ptr->ops->map_poke_untrack(map_ptr, prog->aux);
}
/* At this point we're guaranteed that poke descriptors are not
* live anymore. We can just unlink its descriptor table as it's
* released with the main prog.
*/
for (i = 0; i < env->subprog_cnt; i++) {
if (!func[i])
continue;
func[i]->aux->poke_tab = NULL;
bpf_jit_free(func[i]);
}
kfree(func);
out_undo_insn:
/* cleanup main prog to be interpreted */
prog->jit_requested = 0;
prog->blinding_requested = 0;
for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
if (!bpf_pseudo_call(insn))
continue;
insn->off = 0;
insn->imm = env->insn_aux_data[i].call_imm;
}
bpf_prog_jit_attempt_done(prog);
return err;
}
static int fixup_call_args(struct bpf_verifier_env *env)
{
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
struct bpf_prog *prog = env->prog;
struct bpf_insn *insn = prog->insnsi;
bool has_kfunc_call = bpf_prog_has_kfunc_call(prog);
int i, depth;
#endif
int err = 0;
if (env->prog->jit_requested &&
!bpf_prog_is_offloaded(env->prog->aux)) {
err = jit_subprogs(env);
if (err == 0)
return 0;
if (err == -EFAULT)
return err;
}
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
if (has_kfunc_call) {
verbose(env, "calling kernel functions are not allowed in non-JITed programs\n");
return -EINVAL;
}
if (env->subprog_cnt > 1 && env->prog->aux->tail_call_reachable) {
/* When JIT fails the progs with bpf2bpf calls and tail_calls
* have to be rejected, since interpreter doesn't support them yet.
*/
verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
return -EINVAL;
}
for (i = 0; i < prog->len; i++, insn++) {
if (bpf_pseudo_func(insn)) {
/* When JIT fails the progs with callback calls
* have to be rejected, since interpreter doesn't support them yet.
*/
verbose(env, "callbacks are not allowed in non-JITed programs\n");
return -EINVAL;
}
if (!bpf_pseudo_call(insn))
continue;
depth = get_callee_stack_depth(env, insn, i);
if (depth < 0)
return depth;
bpf_patch_call_args(insn, depth);
}
err = 0;
#endif
return err;
}
/* replace a generic kfunc with a specialized version if necessary */
static void specialize_kfunc(struct bpf_verifier_env *env,
u32 func_id, u16 offset, unsigned long *addr)
{
struct bpf_prog *prog = env->prog;
bool seen_direct_write;
void *xdp_kfunc;
bool is_rdonly;
if (bpf_dev_bound_kfunc_id(func_id)) {
xdp_kfunc = bpf_dev_bound_resolve_kfunc(prog, func_id);
if (xdp_kfunc) {
*addr = (unsigned long)xdp_kfunc;
return;
}
/* fallback to default kfunc when not supported by netdev */
}
if (offset)
return;
if (func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) {
seen_direct_write = env->seen_direct_write;
is_rdonly = !may_access_direct_pkt_data(env, NULL, BPF_WRITE);
if (is_rdonly)
*addr = (unsigned long)bpf_dynptr_from_skb_rdonly;
/* restore env->seen_direct_write to its original value, since
* may_access_direct_pkt_data mutates it
*/
env->seen_direct_write = seen_direct_write;
}
}
static void __fixup_collection_insert_kfunc(struct bpf_insn_aux_data *insn_aux,
u16 struct_meta_reg,
u16 node_offset_reg,
struct bpf_insn *insn,
struct bpf_insn *insn_buf,
int *cnt)
{
struct btf_struct_meta *kptr_struct_meta = insn_aux->kptr_struct_meta;
struct bpf_insn addr[2] = { BPF_LD_IMM64(struct_meta_reg, (long)kptr_struct_meta) };
insn_buf[0] = addr[0];
insn_buf[1] = addr[1];
insn_buf[2] = BPF_MOV64_IMM(node_offset_reg, insn_aux->insert_off);
insn_buf[3] = *insn;
*cnt = 4;
}
static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
struct bpf_insn *insn_buf, int insn_idx, int *cnt)
{
const struct bpf_kfunc_desc *desc;
if (!insn->imm) {
verbose(env, "invalid kernel function call not eliminated in verifier pass\n");
return -EINVAL;
}
*cnt = 0;
/* insn->imm has the btf func_id. Replace it with an offset relative to
* __bpf_call_base, unless the JIT needs to call functions that are
* further than 32 bits away (bpf_jit_supports_far_kfunc_call()).
*/
desc = find_kfunc_desc(env->prog, insn->imm, insn->off);
if (!desc) {
verbose(env, "verifier internal error: kernel function descriptor not found for func_id %u\n",
insn->imm);
return -EFAULT;
}
if (!bpf_jit_supports_far_kfunc_call())
insn->imm = BPF_CALL_IMM(desc->addr);
if (insn->off)
return 0;
if (desc->func_id == special_kfunc_list[KF_bpf_obj_new_impl] ||
desc->func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) {
struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta;
struct bpf_insn addr[2] = { BPF_LD_IMM64(BPF_REG_2, (long)kptr_struct_meta) };
u64 obj_new_size = env->insn_aux_data[insn_idx].obj_new_size;
if (desc->func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl] && kptr_struct_meta) {
verbose(env, "verifier internal error: NULL kptr_struct_meta expected at insn_idx %d\n",
insn_idx);
return -EFAULT;
}
insn_buf[0] = BPF_MOV64_IMM(BPF_REG_1, obj_new_size);
insn_buf[1] = addr[0];
insn_buf[2] = addr[1];
insn_buf[3] = *insn;
*cnt = 4;
} else if (desc->func_id == special_kfunc_list[KF_bpf_obj_drop_impl] ||
desc->func_id == special_kfunc_list[KF_bpf_percpu_obj_drop_impl] ||
desc->func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl]) {
struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta;
struct bpf_insn addr[2] = { BPF_LD_IMM64(BPF_REG_2, (long)kptr_struct_meta) };
if (desc->func_id == special_kfunc_list[KF_bpf_percpu_obj_drop_impl] && kptr_struct_meta) {
verbose(env, "verifier internal error: NULL kptr_struct_meta expected at insn_idx %d\n",
insn_idx);
return -EFAULT;
}
if (desc->func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl] &&
!kptr_struct_meta) {
verbose(env, "verifier internal error: kptr_struct_meta expected at insn_idx %d\n",
insn_idx);
return -EFAULT;
}
insn_buf[0] = addr[0];
insn_buf[1] = addr[1];
insn_buf[2] = *insn;
*cnt = 3;
} else if (desc->func_id == special_kfunc_list[KF_bpf_list_push_back_impl] ||
desc->func_id == special_kfunc_list[KF_bpf_list_push_front_impl] ||
desc->func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) {
struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta;
int struct_meta_reg = BPF_REG_3;
int node_offset_reg = BPF_REG_4;
/* rbtree_add has extra 'less' arg, so args-to-fixup are in diff regs */
if (desc->func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) {
struct_meta_reg = BPF_REG_4;
node_offset_reg = BPF_REG_5;
}
if (!kptr_struct_meta) {
verbose(env, "verifier internal error: kptr_struct_meta expected at insn_idx %d\n",
insn_idx);
return -EFAULT;
}
__fixup_collection_insert_kfunc(&env->insn_aux_data[insn_idx], struct_meta_reg,
node_offset_reg, insn, insn_buf, cnt);
} else if (desc->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx] ||
desc->func_id == special_kfunc_list[KF_bpf_rdonly_cast]) {
insn_buf[0] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_1);
*cnt = 1;
} else if (is_bpf_wq_set_callback_impl_kfunc(desc->func_id)) {
struct bpf_insn ld_addrs[2] = { BPF_LD_IMM64(BPF_REG_4, (long)env->prog->aux) };
insn_buf[0] = ld_addrs[0];
insn_buf[1] = ld_addrs[1];
insn_buf[2] = *insn;
*cnt = 3;
}
return 0;
}
/* The function requires that first instruction in 'patch' is insnsi[prog->len - 1] */
static int add_hidden_subprog(struct bpf_verifier_env *env, struct bpf_insn *patch, int len)
{
struct bpf_subprog_info *info = env->subprog_info;
int cnt = env->subprog_cnt;
struct bpf_prog *prog;
/* We only reserve one slot for hidden subprogs in subprog_info. */
if (env->hidden_subprog_cnt) {
verbose(env, "verifier internal error: only one hidden subprog supported\n");
return -EFAULT;
}
/* We're not patching any existing instruction, just appending the new
* ones for the hidden subprog. Hence all of the adjustment operations
* in bpf_patch_insn_data are no-ops.
*/
prog = bpf_patch_insn_data(env, env->prog->len - 1, patch, len);
if (!prog)
return -ENOMEM;
env->prog = prog;
info[cnt + 1].start = info[cnt].start;
info[cnt].start = prog->len - len + 1;
env->subprog_cnt++;
env->hidden_subprog_cnt++;
return 0;
}
/* Do various post-verification rewrites in a single program pass.
* These rewrites simplify JIT and interpreter implementations.
*/
static int do_misc_fixups(struct bpf_verifier_env *env)
{
struct bpf_prog *prog = env->prog;
enum bpf_attach_type eatype = prog->expected_attach_type;
enum bpf_prog_type prog_type = resolve_prog_type(prog);
struct bpf_insn *insn = prog->insnsi;
const struct bpf_func_proto *fn;
const int insn_cnt = prog->len;
const struct bpf_map_ops *ops;
struct bpf_insn_aux_data *aux;
struct bpf_insn *insn_buf = env->insn_buf;
struct bpf_prog *new_prog;
struct bpf_map *map_ptr;
int i, ret, cnt, delta = 0, cur_subprog = 0;
struct bpf_subprog_info *subprogs = env->subprog_info;
u16 stack_depth = subprogs[cur_subprog].stack_depth;
u16 stack_depth_extra = 0;
if (env->seen_exception && !env->exception_callback_subprog) {
struct bpf_insn patch[] = {
env->prog->insnsi[insn_cnt - 1],
BPF_MOV64_REG(BPF_REG_0, BPF_REG_1),
BPF_EXIT_INSN(),
};
ret = add_hidden_subprog(env, patch, ARRAY_SIZE(patch));
if (ret < 0)
return ret;
prog = env->prog;
insn = prog->insnsi;
env->exception_callback_subprog = env->subprog_cnt - 1;
/* Don't update insn_cnt, as add_hidden_subprog always appends insns */
mark_subprog_exc_cb(env, env->exception_callback_subprog);
}
for (i = 0; i < insn_cnt;) {
if (insn->code == (BPF_ALU64 | BPF_MOV | BPF_X) && insn->imm) {
if ((insn->off == BPF_ADDR_SPACE_CAST && insn->imm == 1) ||
(((struct bpf_map *)env->prog->aux->arena)->map_flags & BPF_F_NO_USER_CONV)) {
/* convert to 32-bit mov that clears upper 32-bit */
insn->code = BPF_ALU | BPF_MOV | BPF_X;
/* clear off and imm, so it's a normal 'wX = wY' from JIT pov */
insn->off = 0;
insn->imm = 0;
} /* cast from as(0) to as(1) should be handled by JIT */
goto next_insn;
}
if (env->insn_aux_data[i + delta].needs_zext)
/* Convert BPF_CLASS(insn->code) == BPF_ALU64 to 32-bit ALU */
insn->code = BPF_ALU | BPF_OP(insn->code) | BPF_SRC(insn->code);
/* Make sdiv/smod divide-by-minus-one exceptions impossible. */
if ((insn->code == (BPF_ALU64 | BPF_MOD | BPF_K) ||
insn->code == (BPF_ALU64 | BPF_DIV | BPF_K) ||
insn->code == (BPF_ALU | BPF_MOD | BPF_K) ||
insn->code == (BPF_ALU | BPF_DIV | BPF_K)) &&
insn->off == 1 && insn->imm == -1) {
bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
bool isdiv = BPF_OP(insn->code) == BPF_DIV;
struct bpf_insn *patchlet;
struct bpf_insn chk_and_sdiv[] = {
BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
BPF_NEG | BPF_K, insn->dst_reg,
0, 0, 0),
};
struct bpf_insn chk_and_smod[] = {
BPF_MOV32_IMM(insn->dst_reg, 0),
};
patchlet = isdiv ? chk_and_sdiv : chk_and_smod;
cnt = isdiv ? ARRAY_SIZE(chk_and_sdiv) : ARRAY_SIZE(chk_and_smod);
new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Make divide-by-zero and divide-by-minus-one exceptions impossible. */
if (insn->code == (BPF_ALU64 | BPF_MOD | BPF_X) ||
insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) ||
insn->code == (BPF_ALU | BPF_MOD | BPF_X) ||
insn->code == (BPF_ALU | BPF_DIV | BPF_X)) {
bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
bool isdiv = BPF_OP(insn->code) == BPF_DIV;
bool is_sdiv = isdiv && insn->off == 1;
bool is_smod = !isdiv && insn->off == 1;
struct bpf_insn *patchlet;
struct bpf_insn chk_and_div[] = {
/* [R,W]x div 0 -> 0 */
BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
BPF_JNE | BPF_K, insn->src_reg,
0, 2, 0),
BPF_ALU32_REG(BPF_XOR, insn->dst_reg, insn->dst_reg),
BPF_JMP_IMM(BPF_JA, 0, 0, 1),
*insn,
};
struct bpf_insn chk_and_mod[] = {
/* [R,W]x mod 0 -> [R,W]x */
BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
BPF_JEQ | BPF_K, insn->src_reg,
0, 1 + (is64 ? 0 : 1), 0),
*insn,
BPF_JMP_IMM(BPF_JA, 0, 0, 1),
BPF_MOV32_REG(insn->dst_reg, insn->dst_reg),
};
struct bpf_insn chk_and_sdiv[] = {
/* [R,W]x sdiv 0 -> 0
* LLONG_MIN sdiv -1 -> LLONG_MIN
* INT_MIN sdiv -1 -> INT_MIN
*/
BPF_MOV64_REG(BPF_REG_AX, insn->src_reg),
BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
BPF_ADD | BPF_K, BPF_REG_AX,
0, 0, 1),
BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
BPF_JGT | BPF_K, BPF_REG_AX,
0, 4, 1),
BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
BPF_JEQ | BPF_K, BPF_REG_AX,
0, 1, 0),
BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
BPF_MOV | BPF_K, insn->dst_reg,
0, 0, 0),
/* BPF_NEG(LLONG_MIN) == -LLONG_MIN == LLONG_MIN */
BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
BPF_NEG | BPF_K, insn->dst_reg,
0, 0, 0),
BPF_JMP_IMM(BPF_JA, 0, 0, 1),
*insn,
};
struct bpf_insn chk_and_smod[] = {
/* [R,W]x mod 0 -> [R,W]x */
/* [R,W]x mod -1 -> 0 */
BPF_MOV64_REG(BPF_REG_AX, insn->src_reg),
BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
BPF_ADD | BPF_K, BPF_REG_AX,
0, 0, 1),
BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
BPF_JGT | BPF_K, BPF_REG_AX,
0, 3, 1),
BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
BPF_JEQ | BPF_K, BPF_REG_AX,
0, 3 + (is64 ? 0 : 1), 1),
BPF_MOV32_IMM(insn->dst_reg, 0),
BPF_JMP_IMM(BPF_JA, 0, 0, 1),
*insn,
BPF_JMP_IMM(BPF_JA, 0, 0, 1),
BPF_MOV32_REG(insn->dst_reg, insn->dst_reg),
};
if (is_sdiv) {
patchlet = chk_and_sdiv;
cnt = ARRAY_SIZE(chk_and_sdiv);
} else if (is_smod) {
patchlet = chk_and_smod;
cnt = ARRAY_SIZE(chk_and_smod) - (is64 ? 2 : 0);
} else {
patchlet = isdiv ? chk_and_div : chk_and_mod;
cnt = isdiv ? ARRAY_SIZE(chk_and_div) :
ARRAY_SIZE(chk_and_mod) - (is64 ? 2 : 0);
}
new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Make it impossible to de-reference a userspace address */
if (BPF_CLASS(insn->code) == BPF_LDX &&
(BPF_MODE(insn->code) == BPF_PROBE_MEM ||
BPF_MODE(insn->code) == BPF_PROBE_MEMSX)) {
struct bpf_insn *patch = &insn_buf[0];
u64 uaddress_limit = bpf_arch_uaddress_limit();
if (!uaddress_limit)
goto next_insn;
*patch++ = BPF_MOV64_REG(BPF_REG_AX, insn->src_reg);
if (insn->off)
*patch++ = BPF_ALU64_IMM(BPF_ADD, BPF_REG_AX, insn->off);
*patch++ = BPF_ALU64_IMM(BPF_RSH, BPF_REG_AX, 32);
*patch++ = BPF_JMP_IMM(BPF_JLE, BPF_REG_AX, uaddress_limit >> 32, 2);
*patch++ = *insn;
*patch++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
*patch++ = BPF_MOV64_IMM(insn->dst_reg, 0);
cnt = patch - insn_buf;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Implement LD_ABS and LD_IND with a rewrite, if supported by the program type. */
if (BPF_CLASS(insn->code) == BPF_LD &&
(BPF_MODE(insn->code) == BPF_ABS ||
BPF_MODE(insn->code) == BPF_IND)) {
cnt = env->ops->gen_ld_abs(insn, insn_buf);
if (cnt == 0 || cnt >= INSN_BUF_SIZE) {
verbose(env, "bpf verifier is misconfigured\n");
return -EINVAL;
}
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Rewrite pointer arithmetic to mitigate speculation attacks. */
if (insn->code == (BPF_ALU64 | BPF_ADD | BPF_X) ||
insn->code == (BPF_ALU64 | BPF_SUB | BPF_X)) {
const u8 code_add = BPF_ALU64 | BPF_ADD | BPF_X;
const u8 code_sub = BPF_ALU64 | BPF_SUB | BPF_X;
struct bpf_insn *patch = &insn_buf[0];
bool issrc, isneg, isimm;
u32 off_reg;
aux = &env->insn_aux_data[i + delta];
if (!aux->alu_state ||
aux->alu_state == BPF_ALU_NON_POINTER)
goto next_insn;
isneg = aux->alu_state & BPF_ALU_NEG_VALUE;
issrc = (aux->alu_state & BPF_ALU_SANITIZE) ==
BPF_ALU_SANITIZE_SRC;
isimm = aux->alu_state & BPF_ALU_IMMEDIATE;
off_reg = issrc ? insn->src_reg : insn->dst_reg;
if (isimm) {
*patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
} else {
if (isneg)
*patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
*patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
*patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg);
*patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg);
*patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0);
*patch++ = BPF_ALU64_IMM(BPF_ARSH, BPF_REG_AX, 63);
*patch++ = BPF_ALU64_REG(BPF_AND, BPF_REG_AX, off_reg);
}
if (!issrc)
*patch++ = BPF_MOV64_REG(insn->dst_reg, insn->src_reg);
insn->src_reg = BPF_REG_AX;
if (isneg)
insn->code = insn->code == code_add ?
code_sub : code_add;
*patch++ = *insn;
if (issrc && isneg && !isimm)
*patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
cnt = patch - insn_buf;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
if (is_may_goto_insn(insn)) {
int stack_off = -stack_depth - 8;
stack_depth_extra = 8;
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_AX, BPF_REG_10, stack_off);
if (insn->off >= 0)
insn_buf[1] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_AX, 0, insn->off + 2);
else
insn_buf[1] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_AX, 0, insn->off - 1);
insn_buf[2] = BPF_ALU64_IMM(BPF_SUB, BPF_REG_AX, 1);
insn_buf[3] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_AX, stack_off);
cnt = 4;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
if (insn->code != (BPF_JMP | BPF_CALL))
goto next_insn;
if (insn->src_reg == BPF_PSEUDO_CALL)
goto next_insn;
if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) {
ret = fixup_kfunc_call(env, insn, insn_buf, i + delta, &cnt);
if (ret)
return ret;
if (cnt == 0)
goto next_insn;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Skip inlining the helper call if the JIT does it. */
if (bpf_jit_inlines_helper_call(insn->imm))
goto next_insn;
if (insn->imm == BPF_FUNC_get_route_realm)
prog->dst_needed = 1;
if (insn->imm == BPF_FUNC_get_prandom_u32)
bpf_user_rnd_init_once();
if (insn->imm == BPF_FUNC_override_return)
prog->kprobe_override = 1;
if (insn->imm == BPF_FUNC_tail_call) {
/* If we tail call into other programs, we
* cannot make any assumptions since they can
* be replaced dynamically during runtime in
* the program array.
*/
prog->cb_access = 1;
if (!allow_tail_call_in_subprogs(env))
prog->aux->stack_depth = MAX_BPF_STACK;
prog->aux->max_pkt_offset = MAX_PACKET_OFF;
/* mark bpf_tail_call as different opcode to avoid
* conditional branch in the interpreter for every normal
* call and to prevent accidental JITing by JIT compiler
* that doesn't support bpf_tail_call yet
*/
insn->imm = 0;
insn->code = BPF_JMP | BPF_TAIL_CALL;
aux = &env->insn_aux_data[i + delta];
if (env->bpf_capable && !prog->blinding_requested &&
prog->jit_requested &&
!bpf_map_key_poisoned(aux) &&
!bpf_map_ptr_poisoned(aux) &&
!bpf_map_ptr_unpriv(aux)) {
struct bpf_jit_poke_descriptor desc = {
.reason = BPF_POKE_REASON_TAIL_CALL,
.tail_call.map = aux->map_ptr_state.map_ptr,
.tail_call.key = bpf_map_key_immediate(aux),
.insn_idx = i + delta,
};
ret = bpf_jit_add_poke_descriptor(prog, &desc);
if (ret < 0) {
verbose(env, "adding tail call poke descriptor failed\n");
return ret;
}
insn->imm = ret + 1;
goto next_insn;
}
if (!bpf_map_ptr_unpriv(aux))
goto next_insn;
/* instead of changing every JIT dealing with tail_call
* emit two extra insns:
* if (index >= max_entries) goto out;
* index &= array->index_mask;
* to avoid out-of-bounds cpu speculation
*/
if (bpf_map_ptr_poisoned(aux)) {
verbose(env, "tail_call abusing map_ptr\n");
return -EINVAL;
}
map_ptr = aux->map_ptr_state.map_ptr;
insn_buf[0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3,
map_ptr->max_entries, 2);
insn_buf[1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3,
container_of(map_ptr,
struct bpf_array,
map)->index_mask);
insn_buf[2] = *insn;
cnt = 3;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
if (insn->imm == BPF_FUNC_timer_set_callback) {
/* The verifier will process callback_fn as many times as necessary
* with different maps and the register states prepared by
* set_timer_callback_state will be accurate.
*
* The following use case is valid:
* map1 is shared by prog1, prog2, prog3.
* prog1 calls bpf_timer_init for some map1 elements
* prog2 calls bpf_timer_set_callback for some map1 elements.
* Those that were not bpf_timer_init-ed will return -EINVAL.
* prog3 calls bpf_timer_start for some map1 elements.
* Those that were not both bpf_timer_init-ed and
* bpf_timer_set_callback-ed will return -EINVAL.
*/
struct bpf_insn ld_addrs[2] = {
BPF_LD_IMM64(BPF_REG_3, (long)prog->aux),
};
insn_buf[0] = ld_addrs[0];
insn_buf[1] = ld_addrs[1];
insn_buf[2] = *insn;
cnt = 3;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto patch_call_imm;
}
if (is_storage_get_function(insn->imm)) {
if (!in_sleepable(env) ||
env->insn_aux_data[i + delta].storage_get_func_atomic)
insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_ATOMIC);
else
insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_KERNEL);
insn_buf[1] = *insn;
cnt = 2;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto patch_call_imm;
}
/* bpf_per_cpu_ptr() and bpf_this_cpu_ptr() */
if (env->insn_aux_data[i + delta].call_with_percpu_alloc_ptr) {
/* patch with 'r1 = *(u64 *)(r1 + 0)' since for percpu data,
* bpf_mem_alloc() returns a ptr to the percpu data ptr.
*/
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, 0);
insn_buf[1] = *insn;
cnt = 2;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto patch_call_imm;
}
/* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup
* and other inlining handlers are currently limited to 64 bit
* only.
*/
if (prog->jit_requested && BITS_PER_LONG == 64 &&
(insn->imm == BPF_FUNC_map_lookup_elem ||
insn->imm == BPF_FUNC_map_update_elem ||
insn->imm == BPF_FUNC_map_delete_elem ||
insn->imm == BPF_FUNC_map_push_elem ||
insn->imm == BPF_FUNC_map_pop_elem ||
insn->imm == BPF_FUNC_map_peek_elem ||
insn->imm == BPF_FUNC_redirect_map ||
insn->imm == BPF_FUNC_for_each_map_elem ||
insn->imm == BPF_FUNC_map_lookup_percpu_elem)) {
aux = &env->insn_aux_data[i + delta];
if (bpf_map_ptr_poisoned(aux))
goto patch_call_imm;
map_ptr = aux->map_ptr_state.map_ptr;
ops = map_ptr->ops;
if (insn->imm == BPF_FUNC_map_lookup_elem &&
ops->map_gen_lookup) {
cnt = ops->map_gen_lookup(map_ptr, insn_buf);
if (cnt == -EOPNOTSUPP)
goto patch_map_ops_generic;
if (cnt <= 0 || cnt >= INSN_BUF_SIZE) {
verbose(env, "bpf verifier is misconfigured\n");
return -EINVAL;
}
new_prog = bpf_patch_insn_data(env, i + delta,
insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
BUILD_BUG_ON(!__same_type(ops->map_lookup_elem,
(void *(*)(struct bpf_map *map, void *key))NULL));
BUILD_BUG_ON(!__same_type(ops->map_delete_elem,
(long (*)(struct bpf_map *map, void *key))NULL));
BUILD_BUG_ON(!__same_type(ops->map_update_elem,
(long (*)(struct bpf_map *map, void *key, void *value,
u64 flags))NULL));
BUILD_BUG_ON(!__same_type(ops->map_push_elem,
(long (*)(struct bpf_map *map, void *value,
u64 flags))NULL));
BUILD_BUG_ON(!__same_type(ops->map_pop_elem,
(long (*)(struct bpf_map *map, void *value))NULL));
BUILD_BUG_ON(!__same_type(ops->map_peek_elem,
(long (*)(struct bpf_map *map, void *value))NULL));
BUILD_BUG_ON(!__same_type(ops->map_redirect,
(long (*)(struct bpf_map *map, u64 index, u64 flags))NULL));
BUILD_BUG_ON(!__same_type(ops->map_for_each_callback,
(long (*)(struct bpf_map *map,
bpf_callback_t callback_fn,
void *callback_ctx,
u64 flags))NULL));
BUILD_BUG_ON(!__same_type(ops->map_lookup_percpu_elem,
(void *(*)(struct bpf_map *map, void *key, u32 cpu))NULL));
patch_map_ops_generic:
switch (insn->imm) {
case BPF_FUNC_map_lookup_elem:
insn->imm = BPF_CALL_IMM(ops->map_lookup_elem);
goto next_insn;
case BPF_FUNC_map_update_elem:
insn->imm = BPF_CALL_IMM(ops->map_update_elem);
goto next_insn;
case BPF_FUNC_map_delete_elem:
insn->imm = BPF_CALL_IMM(ops->map_delete_elem);
goto next_insn;
case BPF_FUNC_map_push_elem:
insn->imm = BPF_CALL_IMM(ops->map_push_elem);
goto next_insn;
case BPF_FUNC_map_pop_elem:
insn->imm = BPF_CALL_IMM(ops->map_pop_elem);
goto next_insn;
case BPF_FUNC_map_peek_elem:
insn->imm = BPF_CALL_IMM(ops->map_peek_elem);
goto next_insn;
case BPF_FUNC_redirect_map:
insn->imm = BPF_CALL_IMM(ops->map_redirect);
goto next_insn;
case BPF_FUNC_for_each_map_elem:
insn->imm = BPF_CALL_IMM(ops->map_for_each_callback);
goto next_insn;
case BPF_FUNC_map_lookup_percpu_elem:
insn->imm = BPF_CALL_IMM(ops->map_lookup_percpu_elem);
goto next_insn;
}
goto patch_call_imm;
}
/* Implement bpf_jiffies64 inline. */
if (prog->jit_requested && BITS_PER_LONG == 64 &&
insn->imm == BPF_FUNC_jiffies64) {
struct bpf_insn ld_jiffies_addr[2] = {
BPF_LD_IMM64(BPF_REG_0,
(unsigned long)&jiffies),
};
insn_buf[0] = ld_jiffies_addr[0];
insn_buf[1] = ld_jiffies_addr[1];
insn_buf[2] = BPF_LDX_MEM(BPF_DW, BPF_REG_0,
BPF_REG_0, 0);
cnt = 3;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf,
cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
#if defined(CONFIG_X86_64) && !defined(CONFIG_UML)
/* Implement bpf_get_smp_processor_id() inline. */
if (insn->imm == BPF_FUNC_get_smp_processor_id &&
verifier_inlines_helper_call(env, insn->imm)) {
/* BPF_FUNC_get_smp_processor_id inlining is an
* optimization, so if pcpu_hot.cpu_number is ever
* changed in some incompatible and hard to support
* way, it's fine to back out this inlining logic
*/
insn_buf[0] = BPF_MOV32_IMM(BPF_REG_0, (u32)(unsigned long)&pcpu_hot.cpu_number);
insn_buf[1] = BPF_MOV64_PERCPU_REG(BPF_REG_0, BPF_REG_0);
insn_buf[2] = BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0);
cnt = 3;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
#endif
/* Implement bpf_get_func_arg inline. */
if (prog_type == BPF_PROG_TYPE_TRACING &&
insn->imm == BPF_FUNC_get_func_arg) {
/* Load nr_args from ctx - 8 */
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
insn_buf[1] = BPF_JMP32_REG(BPF_JGE, BPF_REG_2, BPF_REG_0, 6);
insn_buf[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_2, 3);
insn_buf[3] = BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_1);
insn_buf[4] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_2, 0);
insn_buf[5] = BPF_STX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0);
insn_buf[6] = BPF_MOV64_IMM(BPF_REG_0, 0);
insn_buf[7] = BPF_JMP_A(1);
insn_buf[8] = BPF_MOV64_IMM(BPF_REG_0, -EINVAL);
cnt = 9;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Implement bpf_get_func_ret inline. */
if (prog_type == BPF_PROG_TYPE_TRACING &&
insn->imm == BPF_FUNC_get_func_ret) {
if (eatype == BPF_TRACE_FEXIT ||
eatype == BPF_MODIFY_RETURN) {
/* Load nr_args from ctx - 8 */
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
insn_buf[1] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3);
insn_buf[2] = BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1);
insn_buf[3] = BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0);
insn_buf[4] = BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_3, 0);
insn_buf[5] = BPF_MOV64_IMM(BPF_REG_0, 0);
cnt = 6;
} else {
insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, -EOPNOTSUPP);
cnt = 1;
}
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Implement get_func_arg_cnt inline. */
if (prog_type == BPF_PROG_TYPE_TRACING &&
insn->imm == BPF_FUNC_get_func_arg_cnt) {
/* Load nr_args from ctx - 8 */
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
if (!new_prog)
return -ENOMEM;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Implement bpf_get_func_ip inline. */
if (prog_type == BPF_PROG_TYPE_TRACING &&
insn->imm == BPF_FUNC_get_func_ip) {
/* Load IP address from ctx - 16 */
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -16);
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
if (!new_prog)
return -ENOMEM;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Implement bpf_get_branch_snapshot inline. */
if (IS_ENABLED(CONFIG_PERF_EVENTS) &&
prog->jit_requested && BITS_PER_LONG == 64 &&
insn->imm == BPF_FUNC_get_branch_snapshot) {
/* We are dealing with the following func protos:
* u64 bpf_get_branch_snapshot(void *buf, u32 size, u64 flags);
* int perf_snapshot_branch_stack(struct perf_branch_entry *entries, u32 cnt);
*/
const u32 br_entry_size = sizeof(struct perf_branch_entry);
/* struct perf_branch_entry is part of UAPI and is
* used as an array element, so extremely unlikely to
* ever grow or shrink
*/
BUILD_BUG_ON(br_entry_size != 24);
/* if (unlikely(flags)) return -EINVAL */
insn_buf[0] = BPF_JMP_IMM(BPF_JNE, BPF_REG_3, 0, 7);
/* Transform size (bytes) into number of entries (cnt = size / 24).
* But to avoid expensive division instruction, we implement
* divide-by-3 through multiplication, followed by further
* division by 8 through 3-bit right shift.
* Refer to book "Hacker's Delight, 2nd ed." by Henry S. Warren, Jr.,
* p. 227, chapter "Unsigned Division by 3" for details and proofs.
*
* N / 3 <=> M * N / 2^33, where M = (2^33 + 1) / 3 = 0xaaaaaaab.
*/
insn_buf[1] = BPF_MOV32_IMM(BPF_REG_0, 0xaaaaaaab);
insn_buf[2] = BPF_ALU64_REG(BPF_MUL, BPF_REG_2, BPF_REG_0);
insn_buf[3] = BPF_ALU64_IMM(BPF_RSH, BPF_REG_2, 36);
/* call perf_snapshot_branch_stack implementation */
insn_buf[4] = BPF_EMIT_CALL(static_call_query(perf_snapshot_branch_stack));
/* if (entry_cnt == 0) return -ENOENT */
insn_buf[5] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4);
/* return entry_cnt * sizeof(struct perf_branch_entry) */
insn_buf[6] = BPF_ALU32_IMM(BPF_MUL, BPF_REG_0, br_entry_size);
insn_buf[7] = BPF_JMP_A(3);
/* return -EINVAL; */
insn_buf[8] = BPF_MOV64_IMM(BPF_REG_0, -EINVAL);
insn_buf[9] = BPF_JMP_A(1);
/* return -ENOENT; */
insn_buf[10] = BPF_MOV64_IMM(BPF_REG_0, -ENOENT);
cnt = 11;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
continue;
}
/* Implement bpf_kptr_xchg inline */
if (prog->jit_requested && BITS_PER_LONG == 64 &&
insn->imm == BPF_FUNC_kptr_xchg &&
bpf_jit_supports_ptr_xchg()) {
insn_buf[0] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_2);
insn_buf[1] = BPF_ATOMIC_OP(BPF_DW, BPF_XCHG, BPF_REG_1, BPF_REG_0, 0);
cnt = 2;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
patch_call_imm:
fn = env->ops->get_func_proto(insn->imm, env->prog);
/* all functions that have prototype and verifier allowed
* programs to call them, must be real in-kernel functions
*/
if (!fn->func) {
verbose(env,
"kernel subsystem misconfigured func %s#%d\n",
func_id_name(insn->imm), insn->imm);
return -EFAULT;
}
insn->imm = fn->func - __bpf_call_base;
next_insn:
if (subprogs[cur_subprog + 1].start == i + delta + 1) {
subprogs[cur_subprog].stack_depth += stack_depth_extra;
subprogs[cur_subprog].stack_extra = stack_depth_extra;
cur_subprog++;
stack_depth = subprogs[cur_subprog].stack_depth;
stack_depth_extra = 0;
}
i++;
insn++;
}
env->prog->aux->stack_depth = subprogs[0].stack_depth;
for (i = 0; i < env->subprog_cnt; i++) {
int subprog_start = subprogs[i].start;
int stack_slots = subprogs[i].stack_extra / 8;
if (!stack_slots)
continue;
if (stack_slots > 1) {
verbose(env, "verifier bug: stack_slots supports may_goto only\n");
return -EFAULT;
}
/* Add ST insn to subprog prologue to init extra stack */
insn_buf[0] = BPF_ST_MEM(BPF_DW, BPF_REG_FP,
-subprogs[i].stack_depth, BPF_MAX_LOOPS);
/* Copy first actual insn to preserve it */
insn_buf[1] = env->prog->insnsi[subprog_start];
new_prog = bpf_patch_insn_data(env, subprog_start, insn_buf, 2);
if (!new_prog)
return -ENOMEM;
env->prog = prog = new_prog;
/*
* If may_goto is a first insn of a prog there could be a jmp
* insn that points to it, hence adjust all such jmps to point
* to insn after BPF_ST that inits may_goto count.
* Adjustment will succeed because bpf_patch_insn_data() didn't fail.
*/
WARN_ON(adjust_jmp_off(env->prog, subprog_start, 1));
}
/* Since poke tab is now finalized, publish aux to tracker. */
for (i = 0; i < prog->aux->size_poke_tab; i++) {
map_ptr = prog->aux->poke_tab[i].tail_call.map;
if (!map_ptr->ops->map_poke_track ||
!map_ptr->ops->map_poke_untrack ||
!map_ptr->ops->map_poke_run) {
verbose(env, "bpf verifier is misconfigured\n");
return -EINVAL;
}
ret = map_ptr->ops->map_poke_track(map_ptr, prog->aux);
if (ret < 0) {
verbose(env, "tracking tail call prog failed\n");
return ret;
}
}
sort_kfunc_descs_by_imm_off(env->prog);
return 0;
}
static struct bpf_prog *inline_bpf_loop(struct bpf_verifier_env *env,
int position,
s32 stack_base,
u32 callback_subprogno,
u32 *total_cnt)
{
s32 r6_offset = stack_base + 0 * BPF_REG_SIZE;
s32 r7_offset = stack_base + 1 * BPF_REG_SIZE;
s32 r8_offset = stack_base + 2 * BPF_REG_SIZE;
int reg_loop_max = BPF_REG_6;
int reg_loop_cnt = BPF_REG_7;
int reg_loop_ctx = BPF_REG_8;
struct bpf_insn *insn_buf = env->insn_buf;
struct bpf_prog *new_prog;
u32 callback_start;
u32 call_insn_offset;
s32 callback_offset;
u32 cnt = 0;
/* This represents an inlined version of bpf_iter.c:bpf_loop,
* be careful to modify this code in sync.
*/
/* Return error and jump to the end of the patch if
* expected number of iterations is too big.
*/
insn_buf[cnt++] = BPF_JMP_IMM(BPF_JLE, BPF_REG_1, BPF_MAX_LOOPS, 2);
insn_buf[cnt++] = BPF_MOV32_IMM(BPF_REG_0, -E2BIG);
insn_buf[cnt++] = BPF_JMP_IMM(BPF_JA, 0, 0, 16);
/* spill R6, R7, R8 to use these as loop vars */
insn_buf[cnt++] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, r6_offset);
insn_buf[cnt++] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_7, r7_offset);
insn_buf[cnt++] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_8, r8_offset);
/* initialize loop vars */
insn_buf[cnt++] = BPF_MOV64_REG(reg_loop_max, BPF_REG_1);
insn_buf[cnt++] = BPF_MOV32_IMM(reg_loop_cnt, 0);
insn_buf[cnt++] = BPF_MOV64_REG(reg_loop_ctx, BPF_REG_3);
/* loop header,
* if reg_loop_cnt >= reg_loop_max skip the loop body
*/
insn_buf[cnt++] = BPF_JMP_REG(BPF_JGE, reg_loop_cnt, reg_loop_max, 5);
/* callback call,
* correct callback offset would be set after patching
*/
insn_buf[cnt++] = BPF_MOV64_REG(BPF_REG_1, reg_loop_cnt);
insn_buf[cnt++] = BPF_MOV64_REG(BPF_REG_2, reg_loop_ctx);
insn_buf[cnt++] = BPF_CALL_REL(0);
/* increment loop counter */
insn_buf[cnt++] = BPF_ALU64_IMM(BPF_ADD, reg_loop_cnt, 1);
/* jump to loop header if callback returned 0 */
insn_buf[cnt++] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, -6);
/* return value of bpf_loop,
* set R0 to the number of iterations
*/
insn_buf[cnt++] = BPF_MOV64_REG(BPF_REG_0, reg_loop_cnt);
/* restore original values of R6, R7, R8 */
insn_buf[cnt++] = BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_10, r6_offset);
insn_buf[cnt++] = BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_10, r7_offset);
insn_buf[cnt++] = BPF_LDX_MEM(BPF_DW, BPF_REG_8, BPF_REG_10, r8_offset);
*total_cnt = cnt;
new_prog = bpf_patch_insn_data(env, position, insn_buf, cnt);
if (!new_prog)
return new_prog;
/* callback start is known only after patching */
callback_start = env->subprog_info[callback_subprogno].start;
/* Note: insn_buf[12] is an offset of BPF_CALL_REL instruction */
call_insn_offset = position + 12;
callback_offset = callback_start - call_insn_offset - 1;
new_prog->insnsi[call_insn_offset].imm = callback_offset;
return new_prog;
}
static bool is_bpf_loop_call(struct bpf_insn *insn)
{
return insn->code == (BPF_JMP | BPF_CALL) &&
insn->src_reg == 0 &&
insn->imm == BPF_FUNC_loop;
}
/* For all sub-programs in the program (including main) check
* insn_aux_data to see if there are bpf_loop calls that require
* inlining. If such calls are found the calls are replaced with a
* sequence of instructions produced by `inline_bpf_loop` function and
* subprog stack_depth is increased by the size of 3 registers.
* This stack space is used to spill values of the R6, R7, R8. These
* registers are used to store the loop bound, counter and context
* variables.
*/
static int optimize_bpf_loop(struct bpf_verifier_env *env)
{
struct bpf_subprog_info *subprogs = env->subprog_info;
int i, cur_subprog = 0, cnt, delta = 0;
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
u16 stack_depth = subprogs[cur_subprog].stack_depth;
u16 stack_depth_roundup = round_up(stack_depth, 8) - stack_depth;
u16 stack_depth_extra = 0;
for (i = 0; i < insn_cnt; i++, insn++) {
struct bpf_loop_inline_state *inline_state =
&env->insn_aux_data[i + delta].loop_inline_state;
if (is_bpf_loop_call(insn) && inline_state->fit_for_inline) {
struct bpf_prog *new_prog;
stack_depth_extra = BPF_REG_SIZE * 3 + stack_depth_roundup;
new_prog = inline_bpf_loop(env,
i + delta,
-(stack_depth + stack_depth_extra),
inline_state->callback_subprogno,
&cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = new_prog;
insn = new_prog->insnsi + i + delta;
}
if (subprogs[cur_subprog + 1].start == i + delta + 1) {
subprogs[cur_subprog].stack_depth += stack_depth_extra;
cur_subprog++;
stack_depth = subprogs[cur_subprog].stack_depth;
stack_depth_roundup = round_up(stack_depth, 8) - stack_depth;
stack_depth_extra = 0;
}
}
env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;
return 0;
}
/* Remove unnecessary spill/fill pairs, members of fastcall pattern,
* adjust subprograms stack depth when possible.
*/
static int remove_fastcall_spills_fills(struct bpf_verifier_env *env)
{
struct bpf_subprog_info *subprog = env->subprog_info;
struct bpf_insn_aux_data *aux = env->insn_aux_data;
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
u32 spills_num;
bool modified = false;
int i, j;
for (i = 0; i < insn_cnt; i++, insn++) {
if (aux[i].fastcall_spills_num > 0) {
spills_num = aux[i].fastcall_spills_num;
/* NOPs would be removed by opt_remove_nops() */
for (j = 1; j <= spills_num; ++j) {
*(insn - j) = NOP;
*(insn + j) = NOP;
}
modified = true;
}
if ((subprog + 1)->start == i + 1) {
if (modified && !subprog->keep_fastcall_stack)
subprog->stack_depth = -subprog->fastcall_stack_off;
subprog++;
modified = false;
}
}
return 0;
}
static void free_states(struct bpf_verifier_env *env)
{
struct bpf_verifier_state_list *sl, *sln;
int i;
sl = env->free_list;
while (sl) {
sln = sl->next;
free_verifier_state(&sl->state, false);
kfree(sl);
sl = sln;
}
env->free_list = NULL;
if (!env->explored_states)
return;
for (i = 0; i < state_htab_size(env); i++) {
sl = env->explored_states[i];
while (sl) {
sln = sl->next;
free_verifier_state(&sl->state, false);
kfree(sl);
sl = sln;
}
env->explored_states[i] = NULL;
}
}
static int do_check_common(struct bpf_verifier_env *env, int subprog)
{
bool pop_log = !(env->log.level & BPF_LOG_LEVEL2);
struct bpf_subprog_info *sub = subprog_info(env, subprog);
struct bpf_verifier_state *state;
struct bpf_reg_state *regs;
int ret, i;
env->prev_linfo = NULL;
env->pass_cnt++;
state = kzalloc(sizeof(struct bpf_verifier_state), GFP_KERNEL);
if (!state)
return -ENOMEM;
state->curframe = 0;
state->speculative = false;
state->branches = 1;
state->frame[0] = kzalloc(sizeof(struct bpf_func_state), GFP_KERNEL);
if (!state->frame[0]) {
kfree(state);
return -ENOMEM;
}
env->cur_state = state;
init_func_state(env, state->frame[0],
BPF_MAIN_FUNC /* callsite */,
0 /* frameno */,
subprog);
state->first_insn_idx = env->subprog_info[subprog].start;
state->last_insn_idx = -1;
regs = state->frame[state->curframe]->regs;
if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) {
const char *sub_name = subprog_name(env, subprog);
struct bpf_subprog_arg_info *arg;
struct bpf_reg_state *reg;
verbose(env, "Validating %s() func#%d...\n", sub_name, subprog);
ret = btf_prepare_func_args(env, subprog);
if (ret)
goto out;
if (subprog_is_exc_cb(env, subprog)) {
state->frame[0]->in_exception_callback_fn = true;
/* We have already ensured that the callback returns an integer, just
* like all global subprogs. We need to determine it only has a single
* scalar argument.
*/
if (sub->arg_cnt != 1 || sub->args[0].arg_type != ARG_ANYTHING) {
verbose(env, "exception cb only supports single integer argument\n");
ret = -EINVAL;
goto out;
}
}
for (i = BPF_REG_1; i <= sub->arg_cnt; i++) {
arg = &sub->args[i - BPF_REG_1];
reg = ®s[i];
if (arg->arg_type == ARG_PTR_TO_CTX) {
reg->type = PTR_TO_CTX;
mark_reg_known_zero(env, regs, i);
} else if (arg->arg_type == ARG_ANYTHING) {
reg->type = SCALAR_VALUE;
mark_reg_unknown(env, regs, i);
} else if (arg->arg_type == (ARG_PTR_TO_DYNPTR | MEM_RDONLY)) {
/* assume unspecial LOCAL dynptr type */
__mark_dynptr_reg(reg, BPF_DYNPTR_TYPE_LOCAL, true, ++env->id_gen);
} else if (base_type(arg->arg_type) == ARG_PTR_TO_MEM) {
reg->type = PTR_TO_MEM;
if (arg->arg_type & PTR_MAYBE_NULL)
reg->type |= PTR_MAYBE_NULL;
mark_reg_known_zero(env, regs, i);
reg->mem_size = arg->mem_size;
reg->id = ++env->id_gen;
} else if (base_type(arg->arg_type) == ARG_PTR_TO_BTF_ID) {
reg->type = PTR_TO_BTF_ID;
if (arg->arg_type & PTR_MAYBE_NULL)
reg->type |= PTR_MAYBE_NULL;
if (arg->arg_type & PTR_UNTRUSTED)
reg->type |= PTR_UNTRUSTED;
if (arg->arg_type & PTR_TRUSTED)
reg->type |= PTR_TRUSTED;
mark_reg_known_zero(env, regs, i);
reg->btf = bpf_get_btf_vmlinux(); /* can't fail at this point */
reg->btf_id = arg->btf_id;
reg->id = ++env->id_gen;
} else if (base_type(arg->arg_type) == ARG_PTR_TO_ARENA) {
/* caller can pass either PTR_TO_ARENA or SCALAR */
mark_reg_unknown(env, regs, i);
} else {
WARN_ONCE(1, "BUG: unhandled arg#%d type %d\n",
i - BPF_REG_1, arg->arg_type);
ret = -EFAULT;
goto out;
}
}
} else {
/* if main BPF program has associated BTF info, validate that
* it's matching expected signature, and otherwise mark BTF
* info for main program as unreliable
*/
if (env->prog->aux->func_info_aux) {
ret = btf_prepare_func_args(env, 0);
if (ret || sub->arg_cnt != 1 || sub->args[0].arg_type != ARG_PTR_TO_CTX)
env->prog->aux->func_info_aux[0].unreliable = true;
}
/* 1st arg to a function */
regs[BPF_REG_1].type = PTR_TO_CTX;
mark_reg_known_zero(env, regs, BPF_REG_1);
}
ret = do_check(env);
out:
/* check for NULL is necessary, since cur_state can be freed inside
* do_check() under memory pressure.
*/
if (env->cur_state) {
free_verifier_state(env->cur_state, true);
env->cur_state = NULL;
}
while (!pop_stack(env, NULL, NULL, false));
if (!ret && pop_log)
bpf_vlog_reset(&env->log, 0);
free_states(env);
return ret;
}
/* Lazily verify all global functions based on their BTF, if they are called
* from main BPF program or any of subprograms transitively.
* BPF global subprogs called from dead code are not validated.
* All callable global functions must pass verification.
* Otherwise the whole program is rejected.
* Consider:
* int bar(int);
* int foo(int f)
* {
* return bar(f);
* }
* int bar(int b)
* {
* ...
* }
* foo() will be verified first for R1=any_scalar_value. During verification it
* will be assumed that bar() already verified successfully and call to bar()
* from foo() will be checked for type match only. Later bar() will be verified
* independently to check that it's safe for R1=any_scalar_value.
*/
static int do_check_subprogs(struct bpf_verifier_env *env)
{
struct bpf_prog_aux *aux = env->prog->aux;
struct bpf_func_info_aux *sub_aux;
int i, ret, new_cnt;
if (!aux->func_info)
return 0;
/* exception callback is presumed to be always called */
if (env->exception_callback_subprog)
subprog_aux(env, env->exception_callback_subprog)->called = true;
again:
new_cnt = 0;
for (i = 1; i < env->subprog_cnt; i++) {
if (!subprog_is_global(env, i))
continue;
sub_aux = subprog_aux(env, i);
if (!sub_aux->called || sub_aux->verified)
continue;
env->insn_idx = env->subprog_info[i].start;
WARN_ON_ONCE(env->insn_idx == 0);
ret = do_check_common(env, i);
if (ret) {
return ret;
} else if (env->log.level & BPF_LOG_LEVEL) {
verbose(env, "Func#%d ('%s') is safe for any args that match its prototype\n",
i, subprog_name(env, i));
}
/* We verified new global subprog, it might have called some
* more global subprogs that we haven't verified yet, so we
* need to do another pass over subprogs to verify those.
*/
sub_aux->verified = true;
new_cnt++;
}
/* We can't loop forever as we verify at least one global subprog on
* each pass.
*/
if (new_cnt)
goto again;
return 0;
}
static int do_check_main(struct bpf_verifier_env *env)
{
int ret;
env->insn_idx = 0;
ret = do_check_common(env, 0);
if (!ret)
env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;
return ret;
}
static void print_verification_stats(struct bpf_verifier_env *env)
{
int i;
if (env->log.level & BPF_LOG_STATS) {
verbose(env, "verification time %lld usec\n",
div_u64(env->verification_time, 1000));
verbose(env, "stack depth ");
for (i = 0; i < env->subprog_cnt; i++) {
u32 depth = env->subprog_info[i].stack_depth;
verbose(env, "%d", depth);
if (i + 1 < env->subprog_cnt)
verbose(env, "+");
}
verbose(env, "\n");
}
verbose(env, "processed %d insns (limit %d) max_states_per_insn %d "
"total_states %d peak_states %d mark_read %d\n",
env->insn_processed, BPF_COMPLEXITY_LIMIT_INSNS,
env->max_states_per_insn, env->total_states,
env->peak_states, env->longest_mark_read_walk);
}
static int check_struct_ops_btf_id(struct bpf_verifier_env *env)
{
const struct btf_type *t, *func_proto;
const struct bpf_struct_ops_desc *st_ops_desc;
const struct bpf_struct_ops *st_ops;
const struct btf_member *member;
struct bpf_prog *prog = env->prog;
u32 btf_id, member_idx;
struct btf *btf;
const char *mname;
int err;
if (!prog->gpl_compatible) {
verbose(env, "struct ops programs must have a GPL compatible license\n");
return -EINVAL;
}
if (!prog->aux->attach_btf_id)
return -ENOTSUPP;
btf = prog->aux->attach_btf;
if (btf_is_module(btf)) {
/* Make sure st_ops is valid through the lifetime of env */
env->attach_btf_mod = btf_try_get_module(btf);
if (!env->attach_btf_mod) {
verbose(env, "struct_ops module %s is not found\n",
btf_get_name(btf));
return -ENOTSUPP;
}
}
btf_id = prog->aux->attach_btf_id;
st_ops_desc = bpf_struct_ops_find(btf, btf_id);
if (!st_ops_desc) {
verbose(env, "attach_btf_id %u is not a supported struct\n",
btf_id);
return -ENOTSUPP;
}
st_ops = st_ops_desc->st_ops;
t = st_ops_desc->type;
member_idx = prog->expected_attach_type;
if (member_idx >= btf_type_vlen(t)) {
verbose(env, "attach to invalid member idx %u of struct %s\n",
member_idx, st_ops->name);
return -EINVAL;
}
member = &btf_type_member(t)[member_idx];
mname = btf_name_by_offset(btf, member->name_off);
func_proto = btf_type_resolve_func_ptr(btf, member->type,
NULL);
if (!func_proto) {
verbose(env, "attach to invalid member %s(@idx %u) of struct %s\n",
mname, member_idx, st_ops->name);
return -EINVAL;
}
err = bpf_struct_ops_supported(st_ops, __btf_member_bit_offset(t, member) / 8);
if (err) {
verbose(env, "attach to unsupported member %s of struct %s\n",
mname, st_ops->name);
return err;
}
if (st_ops->check_member) {
err = st_ops->check_member(t, member, prog);
if (err) {
verbose(env, "attach to unsupported member %s of struct %s\n",
mname, st_ops->name);
return err;
}
}
/* btf_ctx_access() used this to provide argument type info */
prog->aux->ctx_arg_info =
st_ops_desc->arg_info[member_idx].info;
prog->aux->ctx_arg_info_size =
st_ops_desc->arg_info[member_idx].cnt;
prog->aux->attach_func_proto = func_proto;
prog->aux->attach_func_name = mname;
env->ops = st_ops->verifier_ops;
return 0;
}
#define SECURITY_PREFIX "security_"
static int check_attach_modify_return(unsigned long addr, const char *func_name)
{
if (within_error_injection_list(addr) ||
!strncmp(SECURITY_PREFIX, func_name, sizeof(SECURITY_PREFIX) - 1))
return 0;
return -EINVAL;
}
/* list of non-sleepable functions that are otherwise on
* ALLOW_ERROR_INJECTION list
*/
BTF_SET_START(btf_non_sleepable_error_inject)
/* Three functions below can be called from sleepable and non-sleepable context.
* Assume non-sleepable from bpf safety point of view.
*/
BTF_ID(func, __filemap_add_folio)
#ifdef CONFIG_FAIL_PAGE_ALLOC
BTF_ID(func, should_fail_alloc_page)
#endif
#ifdef CONFIG_FAILSLAB
BTF_ID(func, should_failslab)
#endif
BTF_SET_END(btf_non_sleepable_error_inject)
static int check_non_sleepable_error_inject(u32 btf_id)
{
return btf_id_set_contains(&btf_non_sleepable_error_inject, btf_id);
}
int bpf_check_attach_target(struct bpf_verifier_log *log,
const struct bpf_prog *prog,
const struct bpf_prog *tgt_prog,
u32 btf_id,
struct bpf_attach_target_info *tgt_info)
{
bool prog_extension = prog->type == BPF_PROG_TYPE_EXT;
bool prog_tracing = prog->type == BPF_PROG_TYPE_TRACING;
char trace_symbol[KSYM_SYMBOL_LEN];
const char prefix[] = "btf_trace_";
struct bpf_raw_event_map *btp;
int ret = 0, subprog = -1, i;
const struct btf_type *t;
bool conservative = true;
const char *tname, *fname;
struct btf *btf;
long addr = 0;
struct module *mod = NULL;
if (!btf_id) {
bpf_log(log, "Tracing programs must provide btf_id\n");
return -EINVAL;
}
btf = tgt_prog ? tgt_prog->aux->btf : prog->aux->attach_btf;
if (!btf) {
bpf_log(log,
"FENTRY/FEXIT program can only be attached to another program annotated with BTF\n");
return -EINVAL;
}
t = btf_type_by_id(btf, btf_id);
if (!t) {
bpf_log(log, "attach_btf_id %u is invalid\n", btf_id);
return -EINVAL;
}
tname = btf_name_by_offset(btf, t->name_off);
if (!tname) {
bpf_log(log, "attach_btf_id %u doesn't have a name\n", btf_id);
return -EINVAL;
}
if (tgt_prog) {
struct bpf_prog_aux *aux = tgt_prog->aux;
if (bpf_prog_is_dev_bound(prog->aux) &&
!bpf_prog_dev_bound_match(prog, tgt_prog)) {
bpf_log(log, "Target program bound device mismatch");
return -EINVAL;
}
for (i = 0; i < aux->func_info_cnt; i++)
if (aux->func_info[i].type_id == btf_id) {
subprog = i;
break;
}
if (subprog == -1) {
bpf_log(log, "Subprog %s doesn't exist\n", tname);
return -EINVAL;
}
if (aux->func && aux->func[subprog]->aux->exception_cb) {
bpf_log(log,
"%s programs cannot attach to exception callback\n",
prog_extension ? "Extension" : "FENTRY/FEXIT");
return -EINVAL;
}
conservative = aux->func_info_aux[subprog].unreliable;
if (prog_extension) {
if (conservative) {
bpf_log(log,
"Cannot replace static functions\n");
return -EINVAL;
}
if (!prog->jit_requested) {
bpf_log(log,
"Extension programs should be JITed\n");
return -EINVAL;
}
}
if (!tgt_prog->jited) {
bpf_log(log, "Can attach to only JITed progs\n");
return -EINVAL;
}
if (prog_tracing) {
if (aux->attach_tracing_prog) {
/*
* Target program is an fentry/fexit which is already attached
* to another tracing program. More levels of nesting
* attachment are not allowed.
*/
bpf_log(log, "Cannot nest tracing program attach more than once\n");
return -EINVAL;
}
} else if (tgt_prog->type == prog->type) {
/*
* To avoid potential call chain cycles, prevent attaching of a
* program extension to another extension. It's ok to attach
* fentry/fexit to extension program.
*/
bpf_log(log, "Cannot recursively attach\n");
return -EINVAL;
}
if (tgt_prog->type == BPF_PROG_TYPE_TRACING &&
prog_extension &&
(tgt_prog->expected_attach_type == BPF_TRACE_FENTRY ||
tgt_prog->expected_attach_type == BPF_TRACE_FEXIT)) {
/* Program extensions can extend all program types
* except fentry/fexit. The reason is the following.
* The fentry/fexit programs are used for performance
* analysis, stats and can be attached to any program
* type. When extension program is replacing XDP function
* it is necessary to allow performance analysis of all
* functions. Both original XDP program and its program
* extension. Hence attaching fentry/fexit to
* BPF_PROG_TYPE_EXT is allowed. If extending of
* fentry/fexit was allowed it would be possible to create
* long call chain fentry->extension->fentry->extension
* beyond reasonable stack size. Hence extending fentry
* is not allowed.
*/
bpf_log(log, "Cannot extend fentry/fexit\n");
return -EINVAL;
}
} else {
if (prog_extension) {
bpf_log(log, "Cannot replace kernel functions\n");
return -EINVAL;
}
}
switch (prog->expected_attach_type) {
case BPF_TRACE_RAW_TP:
if (tgt_prog) {
bpf_log(log,
"Only FENTRY/FEXIT progs are attachable to another BPF prog\n");
return -EINVAL;
}
if (!btf_type_is_typedef(t)) {
bpf_log(log, "attach_btf_id %u is not a typedef\n",
btf_id);
return -EINVAL;
}
if (strncmp(prefix, tname, sizeof(prefix) - 1)) {
bpf_log(log, "attach_btf_id %u points to wrong type name %s\n",
btf_id, tname);
return -EINVAL;
}
tname += sizeof(prefix) - 1;
/* The func_proto of "btf_trace_##tname" is generated from typedef without argument
* names. Thus using bpf_raw_event_map to get argument names.
*/
btp = bpf_get_raw_tracepoint(tname);
if (!btp)
return -EINVAL;
fname = kallsyms_lookup((unsigned long)btp->bpf_func, NULL, NULL, NULL,
trace_symbol);
bpf_put_raw_tracepoint(btp);
if (fname)
ret = btf_find_by_name_kind(btf, fname, BTF_KIND_FUNC);
if (!fname || ret < 0) {
bpf_log(log, "Cannot find btf of tracepoint template, fall back to %s%s.\n",
prefix, tname);
t = btf_type_by_id(btf, t->type);
if (!btf_type_is_ptr(t))
/* should never happen in valid vmlinux build */
return -EINVAL;
} else {
t = btf_type_by_id(btf, ret);
if (!btf_type_is_func(t))
/* should never happen in valid vmlinux build */
return -EINVAL;
}
t = btf_type_by_id(btf, t->type);
if (!btf_type_is_func_proto(t))
/* should never happen in valid vmlinux build */
return -EINVAL;
break;
case BPF_TRACE_ITER:
if (!btf_type_is_func(t)) {
bpf_log(log, "attach_btf_id %u is not a function\n",
btf_id);
return -EINVAL;
}
t = btf_type_by_id(btf, t->type);
if (!btf_type_is_func_proto(t))
return -EINVAL;
ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel);
if (ret)
return ret;
break;
default:
if (!prog_extension)
return -EINVAL;
fallthrough;
case BPF_MODIFY_RETURN:
case BPF_LSM_MAC:
case BPF_LSM_CGROUP:
case BPF_TRACE_FENTRY:
case BPF_TRACE_FEXIT:
if (!btf_type_is_func(t)) {
bpf_log(log, "attach_btf_id %u is not a function\n",
btf_id);
return -EINVAL;
}
if (prog_extension &&
btf_check_type_match(log, prog, btf, t))
return -EINVAL;
t = btf_type_by_id(btf, t->type);
if (!btf_type_is_func_proto(t))
return -EINVAL;
if ((prog->aux->saved_dst_prog_type || prog->aux->saved_dst_attach_type) &&
(!tgt_prog || prog->aux->saved_dst_prog_type != tgt_prog->type ||
prog->aux->saved_dst_attach_type != tgt_prog->expected_attach_type))
return -EINVAL;
if (tgt_prog && conservative)
t = NULL;
ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel);
if (ret < 0)
return ret;
if (tgt_prog) {
if (subprog == 0)
addr = (long) tgt_prog->bpf_func;
else
addr = (long) tgt_prog->aux->func[subprog]->bpf_func;
} else {
if (btf_is_module(btf)) {
mod = btf_try_get_module(btf);
if (mod)
addr = find_kallsyms_symbol_value(mod, tname);
else
addr = 0;
} else {
addr = kallsyms_lookup_name(tname);
}
if (!addr) {
module_put(mod);
bpf_log(log,
"The address of function %s cannot be found\n",
tname);
return -ENOENT;
}
}
if (prog->sleepable) {
ret = -EINVAL;
switch (prog->type) {
case BPF_PROG_TYPE_TRACING:
/* fentry/fexit/fmod_ret progs can be sleepable if they are
* attached to ALLOW_ERROR_INJECTION and are not in denylist.
*/
if (!check_non_sleepable_error_inject(btf_id) &&
within_error_injection_list(addr))
ret = 0;
/* fentry/fexit/fmod_ret progs can also be sleepable if they are
* in the fmodret id set with the KF_SLEEPABLE flag.
*/
else {
u32 *flags = btf_kfunc_is_modify_return(btf, btf_id,
prog);
if (flags && (*flags & KF_SLEEPABLE))
ret = 0;
}
break;
case BPF_PROG_TYPE_LSM:
/* LSM progs check that they are attached to bpf_lsm_*() funcs.
* Only some of them are sleepable.
*/
if (bpf_lsm_is_sleepable_hook(btf_id))
ret = 0;
break;
default:
break;
}
if (ret) {
module_put(mod);
bpf_log(log, "%s is not sleepable\n", tname);
return ret;
}
} else if (prog->expected_attach_type == BPF_MODIFY_RETURN) {
if (tgt_prog) {
module_put(mod);
bpf_log(log, "can't modify return codes of BPF programs\n");
return -EINVAL;
}
ret = -EINVAL;
if (btf_kfunc_is_modify_return(btf, btf_id, prog) ||
!check_attach_modify_return(addr, tname))
ret = 0;
if (ret) {
module_put(mod);
bpf_log(log, "%s() is not modifiable\n", tname);
return ret;
}
}
break;
}
tgt_info->tgt_addr = addr;
tgt_info->tgt_name = tname;
tgt_info->tgt_type = t;
tgt_info->tgt_mod = mod;
return 0;
}
BTF_SET_START(btf_id_deny)
BTF_ID_UNUSED
#ifdef CONFIG_SMP
BTF_ID(func, migrate_disable)
BTF_ID(func, migrate_enable)
#endif
#if !defined CONFIG_PREEMPT_RCU && !defined CONFIG_TINY_RCU
BTF_ID(func, rcu_read_unlock_strict)
#endif
#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_TRACE_PREEMPT_TOGGLE)
BTF_ID(func, preempt_count_add)
BTF_ID(func, preempt_count_sub)
#endif
#ifdef CONFIG_PREEMPT_RCU
BTF_ID(func, __rcu_read_lock)
BTF_ID(func, __rcu_read_unlock)
#endif
BTF_SET_END(btf_id_deny)
static bool can_be_sleepable(struct bpf_prog *prog)
{
if (prog->type == BPF_PROG_TYPE_TRACING) {
switch (prog->expected_attach_type) {
case BPF_TRACE_FENTRY:
case BPF_TRACE_FEXIT:
case BPF_MODIFY_RETURN:
case BPF_TRACE_ITER:
return true;
default:
return false;
}
}
return prog->type == BPF_PROG_TYPE_LSM ||
prog->type == BPF_PROG_TYPE_KPROBE /* only for uprobes */ ||
prog->type == BPF_PROG_TYPE_STRUCT_OPS;
}
static int check_attach_btf_id(struct bpf_verifier_env *env)
{
struct bpf_prog *prog = env->prog;
struct bpf_prog *tgt_prog = prog->aux->dst_prog;
struct bpf_attach_target_info tgt_info = {};
u32 btf_id = prog->aux->attach_btf_id;
struct bpf_trampoline *tr;
int ret;
u64 key;
if (prog->type == BPF_PROG_TYPE_SYSCALL) {
if (prog->sleepable)
/* attach_btf_id checked to be zero already */
return 0;
verbose(env, "Syscall programs can only be sleepable\n");
return -EINVAL;
}
if (prog->sleepable && !can_be_sleepable(prog)) {
verbose(env, "Only fentry/fexit/fmod_ret, lsm, iter, uprobe, and struct_ops programs can be sleepable\n");
return -EINVAL;
}
if (prog->type == BPF_PROG_TYPE_STRUCT_OPS)
return check_struct_ops_btf_id(env);
if (prog->type != BPF_PROG_TYPE_TRACING &&
prog->type != BPF_PROG_TYPE_LSM &&
prog->type != BPF_PROG_TYPE_EXT)
return 0;
ret = bpf_check_attach_target(&env->log, prog, tgt_prog, btf_id, &tgt_info);
if (ret)
return ret;
if (tgt_prog && prog->type == BPF_PROG_TYPE_EXT) {
/* to make freplace equivalent to their targets, they need to
* inherit env->ops and expected_attach_type for the rest of the
* verification
*/
env->ops = bpf_verifier_ops[tgt_prog->type];
prog->expected_attach_type = tgt_prog->expected_attach_type;
}
/* store info about the attachment target that will be used later */
prog->aux->attach_func_proto = tgt_info.tgt_type;
prog->aux->attach_func_name = tgt_info.tgt_name;
prog->aux->mod = tgt_info.tgt_mod;
if (tgt_prog) {
prog->aux->saved_dst_prog_type = tgt_prog->type;
prog->aux->saved_dst_attach_type = tgt_prog->expected_attach_type;
}
if (prog->expected_attach_type == BPF_TRACE_RAW_TP) {
prog->aux->attach_btf_trace = true;
return 0;
} else if (prog->expected_attach_type == BPF_TRACE_ITER) {
if (!bpf_iter_prog_supported(prog))
return -EINVAL;
return 0;
}
if (prog->type == BPF_PROG_TYPE_LSM) {
ret = bpf_lsm_verify_prog(&env->log, prog);
if (ret < 0)
return ret;
} else if (prog->type == BPF_PROG_TYPE_TRACING &&
btf_id_set_contains(&btf_id_deny, btf_id)) {
return -EINVAL;
}
key = bpf_trampoline_compute_key(tgt_prog, prog->aux->attach_btf, btf_id);
tr = bpf_trampoline_get(key, &tgt_info);
if (!tr)
return -ENOMEM;
if (tgt_prog && tgt_prog->aux->tail_call_reachable)
tr->flags = BPF_TRAMP_F_TAIL_CALL_CTX;
prog->aux->dst_trampoline = tr;
return 0;
}
struct btf *bpf_get_btf_vmlinux(void)
{
if (!btf_vmlinux && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
mutex_lock(&bpf_verifier_lock);
if (!btf_vmlinux)
btf_vmlinux = btf_parse_vmlinux();
mutex_unlock(&bpf_verifier_lock);
}
return btf_vmlinux;
}
int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u32 uattr_size)
{
u64 start_time = ktime_get_ns();
struct bpf_verifier_env *env;
int i, len, ret = -EINVAL, err;
u32 log_true_size;
bool is_priv;
/* no program is valid */
if (ARRAY_SIZE(bpf_verifier_ops) == 0)
return -EINVAL;
/* 'struct bpf_verifier_env' can be global, but since it's not small,
* allocate/free it every time bpf_check() is called
*/
env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
if (!env)
return -ENOMEM;
env->bt.env = env;
len = (*prog)->len;
env->insn_aux_data =
vzalloc(array_size(sizeof(struct bpf_insn_aux_data), len));
ret = -ENOMEM;
if (!env->insn_aux_data)
goto err_free_env;
for (i = 0; i < len; i++)
env->insn_aux_data[i].orig_idx = i;
env->prog = *prog;
env->ops = bpf_verifier_ops[env->prog->type];
env->fd_array = make_bpfptr(attr->fd_array, uattr.is_kernel);
env->allow_ptr_leaks = bpf_allow_ptr_leaks(env->prog->aux->token);
env->allow_uninit_stack = bpf_allow_uninit_stack(env->prog->aux->token);
env->bypass_spec_v1 = bpf_bypass_spec_v1(env->prog->aux->token);
env->bypass_spec_v4 = bpf_bypass_spec_v4(env->prog->aux->token);
env->bpf_capable = is_priv = bpf_token_capable(env->prog->aux->token, CAP_BPF);
bpf_get_btf_vmlinux();
/* grab the mutex to protect few globals used by verifier */
if (!is_priv)
mutex_lock(&bpf_verifier_lock);
/* user could have requested verbose verifier output
* and supplied buffer to store the verification trace
*/
ret = bpf_vlog_init(&env->log, attr->log_level,
(char __user *) (unsigned long) attr->log_buf,
attr->log_size);
if (ret)
goto err_unlock;
mark_verifier_state_clean(env);
if (IS_ERR(btf_vmlinux)) {
/* Either gcc or pahole or kernel are broken. */
verbose(env, "in-kernel BTF is malformed\n");
ret = PTR_ERR(btf_vmlinux);
goto skip_full_check;
}
env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
env->strict_alignment = true;
if (attr->prog_flags & BPF_F_ANY_ALIGNMENT)
env->strict_alignment = false;
if (is_priv)
env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ;
env->test_reg_invariants = attr->prog_flags & BPF_F_TEST_REG_INVARIANTS;
env->explored_states = kvcalloc(state_htab_size(env),
sizeof(struct bpf_verifier_state_list *),
GFP_USER);
ret = -ENOMEM;
if (!env->explored_states)
goto skip_full_check;
ret = check_btf_info_early(env, attr, uattr);
if (ret < 0)
goto skip_full_check;
ret = add_subprog_and_kfunc(env);
if (ret < 0)
goto skip_full_check;
ret = check_subprogs(env);
if (ret < 0)
goto skip_full_check;
ret = check_btf_info(env, attr, uattr);
if (ret < 0)
goto skip_full_check;
ret = check_attach_btf_id(env);
if (ret)
goto skip_full_check;
ret = resolve_pseudo_ldimm64(env);
if (ret < 0)
goto skip_full_check;
if (bpf_prog_is_offloaded(env->prog->aux)) {
ret = bpf_prog_offload_verifier_prep(env->prog);
if (ret)
goto skip_full_check;
}
ret = check_cfg(env);
if (ret < 0)
goto skip_full_check;
ret = mark_fastcall_patterns(env);
if (ret < 0)
goto skip_full_check;
ret = do_check_main(env);
ret = ret ?: do_check_subprogs(env);
if (ret == 0 && bpf_prog_is_offloaded(env->prog->aux))
ret = bpf_prog_offload_finalize(env);
skip_full_check:
kvfree(env->explored_states);
/* might decrease stack depth, keep it before passes that
* allocate additional slots.
*/
if (ret == 0)
ret = remove_fastcall_spills_fills(env);
if (ret == 0)
ret = check_max_stack_depth(env);
/* instruction rewrites happen after this point */
if (ret == 0)
ret = optimize_bpf_loop(env);
if (is_priv) {
if (ret == 0)
opt_hard_wire_dead_code_branches(env);
if (ret == 0)
ret = opt_remove_dead_code(env);
if (ret == 0)
ret = opt_remove_nops(env);
} else {
if (ret == 0)
sanitize_dead_code(env);
}
if (ret == 0)
/* program is valid, convert *(u32*)(ctx + off) accesses */
ret = convert_ctx_accesses(env);
if (ret == 0)
ret = do_misc_fixups(env);
/* do 32-bit optimization after insn patching has done so those patched
* insns could be handled correctly.
*/
if (ret == 0 && !bpf_prog_is_offloaded(env->prog->aux)) {
ret = opt_subreg_zext_lo32_rnd_hi32(env, attr);
env->prog->aux->verifier_zext = bpf_jit_needs_zext() ? !ret
: false;
}
if (ret == 0)
ret = fixup_call_args(env);
env->verification_time = ktime_get_ns() - start_time;
print_verification_stats(env);
env->prog->aux->verified_insns = env->insn_processed;
/* preserve original error even if log finalization is successful */
err = bpf_vlog_finalize(&env->log, &log_true_size);
if (err)
ret = err;
if (uattr_size >= offsetofend(union bpf_attr, log_true_size) &&
copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, log_true_size),
&log_true_size, sizeof(log_true_size))) {
ret = -EFAULT;
goto err_release_maps;
}
if (ret)
goto err_release_maps;
if (env->used_map_cnt) {
/* if program passed verifier, update used_maps in bpf_prog_info */
env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
sizeof(env->used_maps[0]),
GFP_KERNEL);
if (!env->prog->aux->used_maps) {
ret = -ENOMEM;
goto err_release_maps;
}
memcpy(env->prog->aux->used_maps, env->used_maps,
sizeof(env->used_maps[0]) * env->used_map_cnt);
env->prog->aux->used_map_cnt = env->used_map_cnt;
}
if (env->used_btf_cnt) {
/* if program passed verifier, update used_btfs in bpf_prog_aux */
env->prog->aux->used_btfs = kmalloc_array(env->used_btf_cnt,
sizeof(env->used_btfs[0]),
GFP_KERNEL);
if (!env->prog->aux->used_btfs) {
ret = -ENOMEM;
goto err_release_maps;
}
memcpy(env->prog->aux->used_btfs, env->used_btfs,
sizeof(env->used_btfs[0]) * env->used_btf_cnt);
env->prog->aux->used_btf_cnt = env->used_btf_cnt;
}
if (env->used_map_cnt || env->used_btf_cnt) {
/* program is valid. Convert pseudo bpf_ld_imm64 into generic
* bpf_ld_imm64 instructions
*/
convert_pseudo_ld_imm64(env);
}
adjust_btf_func(env);
err_release_maps:
if (!env->prog->aux->used_maps)
/* if we didn't copy map pointers into bpf_prog_info, release
* them now. Otherwise free_used_maps() will release them.
*/
release_maps(env);
if (!env->prog->aux->used_btfs)
release_btfs(env);
/* extension progs temporarily inherit the attach_type of their targets
for verification purposes, so set it back to zero before returning
*/
if (env->prog->type == BPF_PROG_TYPE_EXT)
env->prog->expected_attach_type = 0;
*prog = env->prog;
module_put(env->attach_btf_mod);
err_unlock:
if (!is_priv)
mutex_unlock(&bpf_verifier_lock);
vfree(env->insn_aux_data);
err_free_env:
kfree(env);
return ret;
}
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