// SPDX-License-Identifier: GPL-2.0
/* Converted from tools/testing/selftests/bpf/verifier/var_off.c */
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 1);
__type(key, long long);
__type(value, long long);
} map_hash_8b SEC(".maps");
SEC("lwt_in")
__description("variable-offset ctx access")
__failure __msg("variable ctx access var_off=(0x0; 0x4)")
__naked void variable_offset_ctx_access(void)
{
asm volatile (" \
/* Get an unknown value */ \
r2 = *(u32*)(r1 + 0); \
/* Make it small and 4-byte aligned */ \
r2 &= 4; \
/* add it to skb. We now have either &skb->len or\
* &skb->pkt_type, but we don't know which \
*/ \
r1 += r2; \
/* dereference it */ \
r0 = *(u32*)(r1 + 0); \
exit; \
" ::: __clobber_all);
}
SEC("cgroup/skb")
__description("variable-offset stack read, priv vs unpriv")
__success __failure_unpriv
__msg_unpriv("R2 variable stack access prohibited for !root")
__retval(0)
__naked void stack_read_priv_vs_unpriv(void)
{
asm volatile (" \
/* Fill the top 8 bytes of the stack */ \
r0 = 0; \
*(u64*)(r10 - 8) = r0; \
/* Get an unknown value */ \
r2 = *(u32*)(r1 + 0); \
/* Make it small and 4-byte aligned */ \
r2 &= 4; \
r2 -= 8; \
/* add it to fp. We now have either fp-4 or fp-8, but\
* we don't know which \
*/ \
r2 += r10; \
/* dereference it for a stack read */ \
r0 = *(u32*)(r2 + 0); \
r0 = 0; \
exit; \
" ::: __clobber_all);
}
SEC("cgroup/skb")
__description("variable-offset stack read, uninitialized")
__success
__failure_unpriv __msg_unpriv("R2 variable stack access prohibited for !root")
__naked void variable_offset_stack_read_uninitialized(void)
{
asm volatile (" \
/* Get an unknown value */ \
r2 = *(u32*)(r1 + 0); \
/* Make it small and 4-byte aligned */ \
r2 &= 4; \
r2 -= 8; \
/* add it to fp. We now have either fp-4 or fp-8, but\
* we don't know which \
*/ \
r2 += r10; \
/* dereference it for a stack read */ \
r0 = *(u32*)(r2 + 0); \
r0 = 0; \
exit; \
" ::: __clobber_all);
}
SEC("socket")
__description("variable-offset stack write, priv vs unpriv")
__success
/* Check that the maximum stack depth is correctly maintained according to the
* maximum possible variable offset.
*/
__log_level(4) __msg("stack depth 16")
__failure_unpriv
/* Variable stack access is rejected for unprivileged.
*/
__msg_unpriv("R2 variable stack access prohibited for !root")
__retval(0)
__naked void stack_write_priv_vs_unpriv(void)
{
asm volatile (" \
/* Get an unknown value */ \
r2 = *(u32*)(r1 + 0); \
/* Make it small and 8-byte aligned */ \
r2 &= 8; \
r2 -= 16; \
/* Add it to fp. We now have either fp-8 or \
* fp-16, but we don't know which \
*/ \
r2 += r10; \
/* Dereference it for a stack write */ \
r0 = 0; \
*(u64*)(r2 + 0) = r0; \
exit; \
" ::: __clobber_all);
}
/* Similar to the previous test, but this time also perform a read from the
* address written to with a variable offset. The read is allowed, showing that,
* after a variable-offset write, a priviledged program can read the slots that
* were in the range of that write (even if the verifier doesn't actually know if
* the slot being read was really written to or not.
*
* Despite this test being mostly a superset, the previous test is also kept for
* the sake of it checking the stack depth in the case where there is no read.
*/
SEC("socket")
__description("variable-offset stack write followed by read")
__success
/* Check that the maximum stack depth is correctly maintained according to the
* maximum possible variable offset.
*/
__log_level(4) __msg("stack depth 16")
__failure_unpriv
__msg_unpriv("R2 variable stack access prohibited for !root")
__retval(0)
__naked void stack_write_followed_by_read(void)
{
asm volatile (" \
/* Get an unknown value */ \
r2 = *(u32*)(r1 + 0); \
/* Make it small and 8-byte aligned */ \
r2 &= 8; \
r2 -= 16; \
/* Add it to fp. We now have either fp-8 or fp-16, but\
* we don't know which \
*/ \
r2 += r10; \
/* Dereference it for a stack write */ \
r0 = 0; \
*(u64*)(r2 + 0) = r0; \
/* Now read from the address we just wrote. */ \
r3 = *(u64*)(r2 + 0); \
r0 = 0; \
exit; \
" ::: __clobber_all);
}
SEC("socket")
__description("variable-offset stack write clobbers spilled regs")
__failure
/* In the priviledged case, dereferencing a spilled-and-then-filled
* register is rejected because the previous variable offset stack
* write might have overwritten the spilled pointer (i.e. we lose track
* of the spilled register when we analyze the write).
*/
__msg("R2 invalid mem access 'scalar'")
__failure_unpriv
/* The unprivileged case is not too interesting; variable
* stack access is rejected.
*/
__msg_unpriv("R2 variable stack access prohibited for !root")
__naked void stack_write_clobbers_spilled_regs(void)
{
asm volatile (" \
/* Dummy instruction; needed because we need to patch the next one\
* and we can't patch the first instruction. \
*/ \
r6 = 0; \
/* Make R0 a map ptr */ \
r0 = %[map_hash_8b] ll; \
/* Get an unknown value */ \
r2 = *(u32*)(r1 + 0); \
/* Make it small and 8-byte aligned */ \
r2 &= 8; \
r2 -= 16; \
/* Add it to fp. We now have either fp-8 or fp-16, but\
* we don't know which. \
*/ \
r2 += r10; \
/* Spill R0(map ptr) into stack */ \
*(u64*)(r10 - 8) = r0; \
/* Dereference the unknown value for a stack write */\
r0 = 0; \
*(u64*)(r2 + 0) = r0; \
/* Fill the register back into R2 */ \
r2 = *(u64*)(r10 - 8); \
/* Try to dereference R2 for a memory load */ \
r0 = *(u64*)(r2 + 8); \
exit; \
" :
: __imm_addr(map_hash_8b)
: __clobber_all);
}
SEC("sockops")
__description("indirect variable-offset stack access, unbounded")
__failure __msg("invalid unbounded variable-offset indirect access to stack R4")
__naked void variable_offset_stack_access_unbounded(void)
{
asm volatile (" \
r2 = 6; \
r3 = 28; \
/* Fill the top 16 bytes of the stack. */ \
r4 = 0; \
*(u64*)(r10 - 16) = r4; \
r4 = 0; \
*(u64*)(r10 - 8) = r4; \
/* Get an unknown value. */ \
r4 = *(u64*)(r1 + %[bpf_sock_ops_bytes_received]);\
/* Check the lower bound but don't check the upper one. */\
if r4 s< 0 goto l0_%=; \
/* Point the lower bound to initialized stack. Offset is now in range\
* from fp-16 to fp+0x7fffffffffffffef, i.e. max value is unbounded.\
*/ \
r4 -= 16; \
r4 += r10; \
r5 = 8; \
/* Dereference it indirectly. */ \
call %[bpf_getsockopt]; \
l0_%=: r0 = 0; \
exit; \
" :
: __imm(bpf_getsockopt),
__imm_const(bpf_sock_ops_bytes_received, offsetof(struct bpf_sock_ops, bytes_received))
: __clobber_all);
}
SEC("lwt_in")
__description("indirect variable-offset stack access, max out of bound")
__failure __msg("invalid variable-offset indirect access to stack R2")
__naked void access_max_out_of_bound(void)
{
asm volatile (" \
/* Fill the top 8 bytes of the stack */ \
r2 = 0; \
*(u64*)(r10 - 8) = r2; \
/* Get an unknown value */ \
r2 = *(u32*)(r1 + 0); \
/* Make it small and 4-byte aligned */ \
r2 &= 4; \
r2 -= 8; \
/* add it to fp. We now have either fp-4 or fp-8, but\
* we don't know which \
*/ \
r2 += r10; \
/* dereference it indirectly */ \
r1 = %[map_hash_8b] ll; \
call %[bpf_map_lookup_elem]; \
r0 = 0; \
exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_8b)
: __clobber_all);
}
/* Similar to the test above, but this time check the special case of a
* zero-sized stack access. We used to have a bug causing crashes for zero-sized
* out-of-bounds accesses.
*/
SEC("socket")
__description("indirect variable-offset stack access, zero-sized, max out of bound")
__failure __msg("invalid variable-offset indirect access to stack R1")
__naked void zero_sized_access_max_out_of_bound(void)
{
asm volatile (" \
r0 = 0; \
/* Fill some stack */ \
*(u64*)(r10 - 16) = r0; \
*(u64*)(r10 - 8) = r0; \
/* Get an unknown value */ \
r1 = *(u32*)(r1 + 0); \
r1 &= 63; \
r1 += -16; \
/* r1 is now anywhere in [-16,48) */ \
r1 += r10; \
r2 = 0; \
r3 = 0; \
call %[bpf_probe_read_kernel]; \
exit; \
" :
: __imm(bpf_probe_read_kernel)
: __clobber_all);
}
SEC("lwt_in")
__description("indirect variable-offset stack access, min out of bound")
__failure __msg("invalid variable-offset indirect access to stack R2")
__naked void access_min_out_of_bound(void)
{
asm volatile (" \
/* Fill the top 8 bytes of the stack */ \
r2 = 0; \
*(u64*)(r10 - 8) = r2; \
/* Get an unknown value */ \
r2 = *(u32*)(r1 + 0); \
/* Make it small and 4-byte aligned */ \
r2 &= 4; \
r2 -= 516; \
/* add it to fp. We now have either fp-516 or fp-512, but\
* we don't know which \
*/ \
r2 += r10; \
/* dereference it indirectly */ \
r1 = %[map_hash_8b] ll; \
call %[bpf_map_lookup_elem]; \
r0 = 0; \
exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_8b)
: __clobber_all);
}
SEC("cgroup/skb")
__description("indirect variable-offset stack access, min_off < min_initialized")
__success
__failure_unpriv __msg_unpriv("R2 variable stack access prohibited for !root")
__naked void access_min_off_min_initialized(void)
{
asm volatile (" \
/* Fill only the top 8 bytes of the stack. */ \
r2 = 0; \
*(u64*)(r10 - 8) = r2; \
/* Get an unknown value */ \
r2 = *(u32*)(r1 + 0); \
/* Make it small and 4-byte aligned. */ \
r2 &= 4; \
r2 -= 16; \
/* Add it to fp. We now have either fp-12 or fp-16, but we don't know\
* which. fp-16 size 8 is partially uninitialized stack.\
*/ \
r2 += r10; \
/* Dereference it indirectly. */ \
r1 = %[map_hash_8b] ll; \
call %[bpf_map_lookup_elem]; \
r0 = 0; \
exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_8b)
: __clobber_all);
}
SEC("cgroup/skb")
__description("indirect variable-offset stack access, priv vs unpriv")
__success __failure_unpriv
__msg_unpriv("R2 variable stack access prohibited for !root")
__retval(0)
__naked void stack_access_priv_vs_unpriv(void)
{
asm volatile (" \
/* Fill the top 16 bytes of the stack. */ \
r2 = 0; \
*(u64*)(r10 - 16) = r2; \
r2 = 0; \
*(u64*)(r10 - 8) = r2; \
/* Get an unknown value. */ \
r2 = *(u32*)(r1 + 0); \
/* Make it small and 4-byte aligned. */ \
r2 &= 4; \
r2 -= 16; \
/* Add it to fp. We now have either fp-12 or fp-16, we don't know\
* which, but either way it points to initialized stack.\
*/ \
r2 += r10; \
/* Dereference it indirectly. */ \
r1 = %[map_hash_8b] ll; \
call %[bpf_map_lookup_elem]; \
r0 = 0; \
exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_8b)
: __clobber_all);
}
SEC("lwt_in")
__description("indirect variable-offset stack access, ok")
__success __retval(0)
__naked void variable_offset_stack_access_ok(void)
{
asm volatile (" \
/* Fill the top 16 bytes of the stack. */ \
r2 = 0; \
*(u64*)(r10 - 16) = r2; \
r2 = 0; \
*(u64*)(r10 - 8) = r2; \
/* Get an unknown value. */ \
r2 = *(u32*)(r1 + 0); \
/* Make it small and 4-byte aligned. */ \
r2 &= 4; \
r2 -= 16; \
/* Add it to fp. We now have either fp-12 or fp-16, we don't know\
* which, but either way it points to initialized stack.\
*/ \
r2 += r10; \
/* Dereference it indirectly. */ \
r1 = %[map_hash_8b] ll; \
call %[bpf_map_lookup_elem]; \
r0 = 0; \
exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_8b)
: __clobber_all);
}
char _license[] SEC("license") = "GPL";
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