// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Facebook */
#include <errno.h>
#include <string.h>
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
char _license[] SEC("license") = "GPL";
#define ITER_HELPERS \
__imm(bpf_iter_num_new), \
__imm(bpf_iter_num_next), \
__imm(bpf_iter_num_destroy)
SEC("?raw_tp")
__success
int force_clang_to_emit_btf_for_externs(void *ctx)
{
/* we need this as a workaround to enforce compiler emitting BTF
* information for bpf_iter_num_{new,next,destroy}() kfuncs,
* as, apparently, it doesn't emit it for symbols only referenced from
* assembly (or cleanup attribute, for that matter, as well)
*/
bpf_repeat(0);
return 0;
}
SEC("?raw_tp")
__success __log_level(2)
__msg("fp-8_w=iter_num(ref_id=1,state=active,depth=0)")
int create_and_destroy(void *ctx)
{
struct bpf_iter_num iter;
asm volatile (
/* create iterator */
"r1 = %[iter];"
"r2 = 0;"
"r3 = 1000;"
"call %[bpf_iter_num_new];"
/* destroy iterator */
"r1 = %[iter];"
"call %[bpf_iter_num_destroy];"
:
: __imm_ptr(iter), ITER_HELPERS
: __clobber_common
);
return 0;
}
SEC("?raw_tp")
__failure __msg("Unreleased reference id=1")
int create_and_forget_to_destroy_fail(void *ctx)
{
struct bpf_iter_num iter;
asm volatile (
/* create iterator */
"r1 = %[iter];"
"r2 = 0;"
"r3 = 1000;"
"call %[bpf_iter_num_new];"
:
: __imm_ptr(iter), ITER_HELPERS
: __clobber_common
);
return 0;
}
SEC("?raw_tp")
__failure __msg("expected an initialized iter_num as arg #1")
int destroy_without_creating_fail(void *ctx)
{
/* init with zeros to stop verifier complaining about uninit stack */
struct bpf_iter_num iter;
asm volatile (
"r1 = %[iter];"
"call %[bpf_iter_num_destroy];"
:
: __imm_ptr(iter), ITER_HELPERS
: __clobber_common
);
return 0;
}
SEC("?raw_tp")
__failure __msg("expected an initialized iter_num as arg #1")
int compromise_iter_w_direct_write_fail(void *ctx)
{
struct bpf_iter_num iter;
asm volatile (
/* create iterator */
"r1 = %[iter];"
"r2 = 0;"
"r3 = 1000;"
"call %[bpf_iter_num_new];"
/* directly write over first half of iter state */
"*(u64 *)(%[iter] + 0) = r0;"
/* (attempt to) destroy iterator */
"r1 = %[iter];"
"call %[bpf_iter_num_destroy];"
:
: __imm_ptr(iter), ITER_HELPERS
: __clobber_common
);
return 0;
}
SEC("?raw_tp")
__failure __msg("Unreleased reference id=1")
int compromise_iter_w_direct_write_and_skip_destroy_fail(void *ctx)
{
struct bpf_iter_num iter;
asm volatile (
/* create iterator */
"r1 = %[iter];"
"r2 = 0;"
"r3 = 1000;"
"call %[bpf_iter_num_new];"
/* directly write over first half of iter state */
"*(u64 *)(%[iter] + 0) = r0;"
/* don't destroy iter, leaking ref, which should fail */
:
: __imm_ptr(iter), ITER_HELPERS
: __clobber_common
);
return 0;
}
SEC("?raw_tp")
__failure __msg("expected an initialized iter_num as arg #1")
int compromise_iter_w_helper_write_fail(void *ctx)
{
struct bpf_iter_num iter;
asm volatile (
/* create iterator */
"r1 = %[iter];"
"r2 = 0;"
"r3 = 1000;"
"call %[bpf_iter_num_new];"
/* overwrite 8th byte with bpf_probe_read_kernel() */
"r1 = %[iter];"
"r1 += 7;"
"r2 = 1;"
"r3 = 0;" /* NULL */
"call %[bpf_probe_read_kernel];"
/* (attempt to) destroy iterator */
"r1 = %[iter];"
"call %[bpf_iter_num_destroy];"
:
: __imm_ptr(iter), ITER_HELPERS, __imm(bpf_probe_read_kernel)
: __clobber_common
);
return 0;
}
static __noinline void subprog_with_iter(void)
{
struct bpf_iter_num iter;
bpf_iter_num_new(&iter, 0, 1);
return;
}
SEC("?raw_tp")
__failure
/* ensure there was a call to subprog, which might happen without __noinline */
__msg("returning from callee:")
__msg("Unreleased reference id=1")
int leak_iter_from_subprog_fail(void *ctx)
{
subprog_with_iter();
return 0;
}
SEC("?raw_tp")
__success __log_level(2)
__msg("fp-8_w=iter_num(ref_id=1,state=active,depth=0)")
int valid_stack_reuse(void *ctx)
{
struct bpf_iter_num iter;
asm volatile (
/* create iterator */
"r1 = %[iter];"
"r2 = 0;"
"r3 = 1000;"
"call %[bpf_iter_num_new];"
/* destroy iterator */
"r1 = %[iter];"
"call %[bpf_iter_num_destroy];"
/* now reuse same stack slots */
/* create iterator */
"r1 = %[iter];"
"r2 = 0;"
"r3 = 1000;"
"call %[bpf_iter_num_new];"
/* destroy iterator */
"r1 = %[iter];"
"call %[bpf_iter_num_destroy];"
:
: __imm_ptr(iter), ITER_HELPERS
: __clobber_common
);
return 0;
}
SEC("?raw_tp")
__failure __msg("expected uninitialized iter_num as arg #1")
int double_create_fail(void *ctx)
{
struct bpf_iter_num iter;
asm volatile (
/* create iterator */
"r1 = %[iter];"
"r2 = 0;"
"r3 = 1000;"
"call %[bpf_iter_num_new];"
/* (attempt to) create iterator again */
"r1 = %[iter];"
"r2 = 0;"
"r3 = 1000;"
"call %[bpf_iter_num_new];"
/* destroy iterator */
"r1 = %[iter];"
"call %[bpf_iter_num_destroy];"
:
: __imm_ptr(iter), ITER_HELPERS
: __clobber_common
);
return 0;
}
SEC("?raw_tp")
__failure __msg("expected an initialized iter_num as arg #1")
int double_destroy_fail(void *ctx)
{
struct bpf_iter_num iter;
asm volatile (
/* create iterator */
"r1 = %[iter];"
"r2 = 0;"
"r3 = 1000;"
"call %[bpf_iter_num_new];"
/* destroy iterator */
"r1 = %[iter];"
"call %[bpf_iter_num_destroy];"
/* (attempt to) destroy iterator again */
"r1 = %[iter];"
"call %[bpf_iter_num_destroy];"
:
: __imm_ptr(iter), ITER_HELPERS
: __clobber_common
);
return 0;
}
SEC("?raw_tp")
__failure __msg("expected an initialized iter_num as arg #1")
int next_without_new_fail(void *ctx)
{
struct bpf_iter_num iter;
asm volatile (
/* don't create iterator and try to iterate*/
"r1 = %[iter];"
"call %[bpf_iter_num_next];"
/* destroy iterator */
"r1 = %[iter];"
"call %[bpf_iter_num_destroy];"
:
: __imm_ptr(iter), ITER_HELPERS
: __clobber_common
);
return 0;
}
SEC("?raw_tp")
__failure __msg("expected an initialized iter_num as arg #1")
int next_after_destroy_fail(void *ctx)
{
struct bpf_iter_num iter;
asm volatile (
/* create iterator */
"r1 = %[iter];"
"r2 = 0;"
"r3 = 1000;"
"call %[bpf_iter_num_new];"
/* destroy iterator */
"r1 = %[iter];"
"call %[bpf_iter_num_destroy];"
/* don't create iterator and try to iterate*/
"r1 = %[iter];"
"call %[bpf_iter_num_next];"
:
: __imm_ptr(iter), ITER_HELPERS
: __clobber_common
);
return 0;
}
SEC("?raw_tp")
__failure __msg("invalid read from stack")
int __naked read_from_iter_slot_fail(void)
{
asm volatile (
/* r6 points to struct bpf_iter_num on the stack */
"r6 = r10;"
"r6 += -24;"
/* create iterator */
"r1 = r6;"
"r2 = 0;"
"r3 = 1000;"
"call %[bpf_iter_num_new];"
/* attemp to leak bpf_iter_num state */
"r7 = *(u64 *)(r6 + 0);"
"r8 = *(u64 *)(r6 + 8);"
/* destroy iterator */
"r1 = r6;"
"call %[bpf_iter_num_destroy];"
/* leak bpf_iter_num state */
"r0 = r7;"
"if r7 > r8 goto +1;"
"r0 = r8;"
"exit;"
:
: ITER_HELPERS
: __clobber_common, "r6", "r7", "r8"
);
}
int zero;
SEC("?raw_tp")
__failure
__flag(BPF_F_TEST_STATE_FREQ)
__msg("Unreleased reference")
int stacksafe_should_not_conflate_stack_spill_and_iter(void *ctx)
{
struct bpf_iter_num iter;
asm volatile (
/* Create a fork in logic, with general setup as follows:
* - fallthrough (first) path is valid;
* - branch (second) path is invalid.
* Then depending on what we do in fallthrough vs branch path,
* we try to detect bugs in func_states_equal(), regsafe(),
* refsafe(), stack_safe(), and similar by tricking verifier
* into believing that branch state is a valid subset of
* a fallthrough state. Verifier should reject overall
* validation, unless there is a bug somewhere in verifier
* logic.
*/
"call %[bpf_get_prandom_u32];"
"r6 = r0;"
"call %[bpf_get_prandom_u32];"
"r7 = r0;"
"if r6 > r7 goto bad;" /* fork */
/* spill r6 into stack slot of bpf_iter_num var */
"*(u64 *)(%[iter] + 0) = r6;"
"goto skip_bad;"
"bad:"
/* create iterator in the same stack slot */
"r1 = %[iter];"
"r2 = 0;"
"r3 = 1000;"
"call %[bpf_iter_num_new];"
/* but then forget about it and overwrite it back to r6 spill */
"*(u64 *)(%[iter] + 0) = r6;"
"skip_bad:"
"goto +0;" /* force checkpoint */
/* corrupt stack slots, if they are really dynptr */
"*(u64 *)(%[iter] + 0) = r6;"
:
: __imm_ptr(iter),
__imm_addr(zero),
__imm(bpf_get_prandom_u32),
__imm(bpf_dynptr_from_mem),
ITER_HELPERS
: __clobber_common, "r6", "r7"
);
return 0;
}
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