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linux/tools/testing/selftests/bpf/progs/verifier_array_access.c
Daniel Xu 973cb1382e bpf: selftests: Test constant key extraction on irrelevant maps 
Test that very high constant map keys are not interpreted as an error
value by the verifier. This would previously fail.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/c0590b62eb9303f389b2f52c0c7e9cf22a358a30.1738689872.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-02-07 15:45:44 -08:00

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// SPDX-License-Identifier: GPL-2.0
/* Converted from tools/testing/selftests/bpf/verifier/array_access.c */
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
#define MAX_ENTRIES 11
struct test_val {
unsigned int index;
int foo[MAX_ENTRIES];
};
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 1);
__type(key, int);
__type(value, struct test_val);
__uint(map_flags, BPF_F_RDONLY_PROG);
} map_array_ro SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 1);
__type(key, int);
__type(value, struct test_val);
__uint(map_flags, BPF_F_WRONLY_PROG);
} map_array_wo SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__uint(max_entries, 2);
__type(key, __u32);
__type(value, struct test_val);
} map_array_pcpu SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 2);
__type(key, __u32);
__type(value, struct test_val);
} map_array SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 1);
__type(key, long long);
__type(value, struct test_val);
} map_hash_48b SEC(".maps");
SEC("socket")
__description("valid map access into an array with a constant")
__success __failure_unpriv __msg_unpriv("R0 leaks addr")
__retval(0)
__naked void an_array_with_a_constant_1(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_hash_48b] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = %[test_val_foo]; \
*(u64*)(r0 + 0) = r1; \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_48b),
__imm_const(test_val_foo, offsetof(struct test_val, foo))
: __clobber_all);
}
SEC("socket")
__description("valid map access into an array with a register")
__success __failure_unpriv __msg_unpriv("R0 leaks addr")
__retval(0) __flag(BPF_F_ANY_ALIGNMENT)
__naked void an_array_with_a_register_1(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_hash_48b] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = 4; \
r1 <<= 2; \
r0 += r1; \
r1 = %[test_val_foo]; \
*(u64*)(r0 + 0) = r1; \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_48b),
__imm_const(test_val_foo, offsetof(struct test_val, foo))
: __clobber_all);
}
SEC("socket")
__description("valid map access into an array with a variable")
__success __failure_unpriv __msg_unpriv("R0 leaks addr")
__retval(0) __flag(BPF_F_ANY_ALIGNMENT)
__naked void an_array_with_a_variable_1(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_hash_48b] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = *(u32*)(r0 + 0); \
if r1 >= %[max_entries] goto l0_%=; \
r1 <<= 2; \
r0 += r1; \
r1 = %[test_val_foo]; \
*(u64*)(r0 + 0) = r1; \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_48b),
__imm_const(max_entries, MAX_ENTRIES),
__imm_const(test_val_foo, offsetof(struct test_val, foo))
: __clobber_all);
}
SEC("socket")
__description("valid map access into an array with a signed variable")
__success __failure_unpriv __msg_unpriv("R0 leaks addr")
__retval(0) __flag(BPF_F_ANY_ALIGNMENT)
__naked void array_with_a_signed_variable(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_hash_48b] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = *(u32*)(r0 + 0); \
if w1 s> 0xffffffff goto l1_%=; \
w1 = 0; \
l1_%=: w2 = %[max_entries]; \
if r2 s> r1 goto l2_%=; \
w1 = 0; \
l2_%=: w1 <<= 2; \
r0 += r1; \
r1 = %[test_val_foo]; \
*(u64*)(r0 + 0) = r1; \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_48b),
__imm_const(max_entries, MAX_ENTRIES),
__imm_const(test_val_foo, offsetof(struct test_val, foo))
: __clobber_all);
}
SEC("socket")
__description("invalid map access into an array with a constant")
__failure __msg("invalid access to map value, value_size=48 off=48 size=8")
__failure_unpriv
__naked void an_array_with_a_constant_2(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_hash_48b] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = %[test_val_foo]; \
*(u64*)(r0 + %[__imm_0]) = r1; \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_48b),
__imm_const(__imm_0, (MAX_ENTRIES + 1) << 2),
__imm_const(test_val_foo, offsetof(struct test_val, foo))
: __clobber_all);
}
SEC("socket")
__description("invalid map access into an array with a register")
__failure __msg("R0 min value is outside of the allowed memory range")
__failure_unpriv
__flag(BPF_F_ANY_ALIGNMENT)
__naked void an_array_with_a_register_2(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_hash_48b] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = %[__imm_0]; \
r1 <<= 2; \
r0 += r1; \
r1 = %[test_val_foo]; \
*(u64*)(r0 + 0) = r1; \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_48b),
__imm_const(__imm_0, MAX_ENTRIES + 1),
__imm_const(test_val_foo, offsetof(struct test_val, foo))
: __clobber_all);
}
SEC("socket")
__description("invalid map access into an array with a variable")
__failure
__msg("R0 unbounded memory access, make sure to bounds check any such access")
__failure_unpriv
__flag(BPF_F_ANY_ALIGNMENT)
__naked void an_array_with_a_variable_2(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_hash_48b] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = *(u32*)(r0 + 0); \
r1 <<= 2; \
r0 += r1; \
r1 = %[test_val_foo]; \
*(u64*)(r0 + 0) = r1; \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_48b),
__imm_const(test_val_foo, offsetof(struct test_val, foo))
: __clobber_all);
}
SEC("socket")
__description("invalid map access into an array with no floor check")
__failure __msg("R0 unbounded memory access")
__failure_unpriv __msg_unpriv("R0 leaks addr")
__flag(BPF_F_ANY_ALIGNMENT)
__naked void array_with_no_floor_check(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_hash_48b] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = *(u64*)(r0 + 0); \
w2 = %[max_entries]; \
if r2 s> r1 goto l1_%=; \
w1 = 0; \
l1_%=: w1 <<= 2; \
r0 += r1; \
r1 = %[test_val_foo]; \
*(u64*)(r0 + 0) = r1; \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_48b),
__imm_const(max_entries, MAX_ENTRIES),
__imm_const(test_val_foo, offsetof(struct test_val, foo))
: __clobber_all);
}
SEC("socket")
__description("invalid map access into an array with a invalid max check")
__failure __msg("invalid access to map value, value_size=48 off=44 size=8")
__failure_unpriv __msg_unpriv("R0 leaks addr")
__flag(BPF_F_ANY_ALIGNMENT)
__naked void with_a_invalid_max_check_1(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_hash_48b] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = *(u32*)(r0 + 0); \
w2 = %[__imm_0]; \
if r2 > r1 goto l1_%=; \
w1 = 0; \
l1_%=: w1 <<= 2; \
r0 += r1; \
r1 = %[test_val_foo]; \
*(u64*)(r0 + 0) = r1; \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_48b),
__imm_const(__imm_0, MAX_ENTRIES + 1),
__imm_const(test_val_foo, offsetof(struct test_val, foo))
: __clobber_all);
}
SEC("socket")
__description("invalid map access into an array with a invalid max check")
__failure __msg("R0 pointer += pointer")
__failure_unpriv
__flag(BPF_F_ANY_ALIGNMENT)
__naked void with_a_invalid_max_check_2(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_hash_48b] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r8 = r0; \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_hash_48b] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r0 += r8; \
r0 = *(u32*)(r0 + %[test_val_foo]); \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_hash_48b),
__imm_const(test_val_foo, offsetof(struct test_val, foo))
: __clobber_all);
}
SEC("socket")
__description("valid read map access into a read-only array 1")
__success __success_unpriv __retval(28)
__naked void a_read_only_array_1_1(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_array_ro] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r0 = *(u32*)(r0 + 0); \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_array_ro)
: __clobber_all);
}
SEC("tc")
__description("valid read map access into a read-only array 2")
__success __retval(65507)
__naked void a_read_only_array_2_1(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_array_ro] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = r0; \
r2 = 4; \
r3 = 0; \
r4 = 0; \
r5 = 0; \
call %[bpf_csum_diff]; \
l0_%=: exit; \
" :
: __imm(bpf_csum_diff),
__imm(bpf_map_lookup_elem),
__imm_addr(map_array_ro)
: __clobber_all);
}
SEC("socket")
__description("invalid write map access into a read-only array 1")
__failure __msg("write into map forbidden")
__failure_unpriv
__naked void a_read_only_array_1_2(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_array_ro] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = 42; \
*(u64*)(r0 + 0) = r1; \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_array_ro)
: __clobber_all);
}
SEC("tc")
__description("invalid write map access into a read-only array 2")
__failure __msg("write into map forbidden")
__naked void a_read_only_array_2_2(void)
{
asm volatile (" \
r6 = r1; \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_array_ro] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = r6; \
r2 = 0; \
r3 = r0; \
r4 = 8; \
call %[bpf_skb_load_bytes]; \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm(bpf_skb_load_bytes),
__imm_addr(map_array_ro)
: __clobber_all);
}
SEC("socket")
__description("valid write map access into a write-only array 1")
__success __success_unpriv __retval(1)
__naked void a_write_only_array_1_1(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_array_wo] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = 42; \
*(u64*)(r0 + 0) = r1; \
l0_%=: r0 = 1; \
exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_array_wo)
: __clobber_all);
}
SEC("tc")
__description("valid write map access into a write-only array 2")
__success __retval(0)
__naked void a_write_only_array_2_1(void)
{
asm volatile (" \
r6 = r1; \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_array_wo] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = r6; \
r2 = 0; \
r3 = r0; \
r4 = 8; \
call %[bpf_skb_load_bytes]; \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm(bpf_skb_load_bytes),
__imm_addr(map_array_wo)
: __clobber_all);
}
SEC("socket")
__description("invalid read map access into a write-only array 1")
__failure __msg("read from map forbidden")
__failure_unpriv
__naked void a_write_only_array_1_2(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_array_wo] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r0 = *(u64*)(r0 + 0); \
l0_%=: exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_array_wo)
: __clobber_all);
}
SEC("tc")
__description("invalid read map access into a write-only array 2")
__failure __msg("read from map forbidden")
__naked void a_write_only_array_2_2(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 8) = r1; \
r2 = r10; \
r2 += -8; \
r1 = %[map_array_wo] ll; \
call %[bpf_map_lookup_elem]; \
if r0 == 0 goto l0_%=; \
r1 = r0; \
r2 = 4; \
r3 = 0; \
r4 = 0; \
r5 = 0; \
call %[bpf_csum_diff]; \
l0_%=: exit; \
" :
: __imm(bpf_csum_diff),
__imm(bpf_map_lookup_elem),
__imm_addr(map_array_wo)
: __clobber_all);
}
SEC("socket")
__description("valid map access into an array using constant without nullness")
__success __retval(4) __log_level(2)
__msg("mark_precise: frame0: regs= stack=-8 before {{[0-9]}}: ({{[a-f0-9]+}}) *(u32 *)(r10 -8) = {{(1|r[0-9])}}")
unsigned int an_array_with_a_constant_no_nullness(void)
{
/* Need 8-byte alignment for spill tracking */
__u32 __attribute__((aligned(8))) key = 1;
struct test_val *val;
val = bpf_map_lookup_elem(&map_array, &key);
val->index = offsetof(struct test_val, foo);
return val->index;
}
SEC("socket")
__description("valid multiple map access into an array using constant without nullness")
__success __retval(8) __log_level(2)
__msg("mark_precise: frame0: regs= stack=-8 before {{[0-9]}}: ({{[a-f0-9]+}}) *(u32 *)(r10 -16) = {{(0|r[0-9])}}")
__msg("mark_precise: frame0: regs= stack=-8 before {{[0-9]}}: ({{[a-f0-9]+}}) *(u32 *)(r10 -8) = {{(1|r[0-9])}}")
unsigned int multiple_array_with_a_constant_no_nullness(void)
{
__u32 __attribute__((aligned(8))) key = 1;
__u32 __attribute__((aligned(8))) key2 = 0;
struct test_val *val, *val2;
val = bpf_map_lookup_elem(&map_array, &key);
val->index = offsetof(struct test_val, foo);
val2 = bpf_map_lookup_elem(&map_array, &key2);
val2->index = offsetof(struct test_val, foo);
return val->index + val2->index;
}
SEC("socket")
__description("valid map access into an array using natural aligned 32-bit constant 0 without nullness")
__success __retval(4)
unsigned int an_array_with_a_32bit_constant_0_no_nullness(void)
{
/* Unlike the above tests, 32-bit zeroing is precisely tracked even
* if writes are not aligned to BPF_REG_SIZE. This tests that our
* STACK_ZERO handling functions.
*/
struct test_val *val;
__u32 key = 0;
val = bpf_map_lookup_elem(&map_array, &key);
val->index = offsetof(struct test_val, foo);
return val->index;
}
SEC("socket")
__description("valid map access into a pcpu array using constant without nullness")
__success __retval(4) __log_level(2)
__msg("mark_precise: frame0: regs= stack=-8 before {{[0-9]}}: ({{[a-f0-9]+}}) *(u32 *)(r10 -8) = {{(1|r[0-9])}}")
unsigned int a_pcpu_array_with_a_constant_no_nullness(void)
{
__u32 __attribute__((aligned(8))) key = 1;
struct test_val *val;
val = bpf_map_lookup_elem(&map_array_pcpu, &key);
val->index = offsetof(struct test_val, foo);
return val->index;
}
SEC("socket")
__description("invalid map access into an array using constant without nullness")
__failure __msg("R0 invalid mem access 'map_value_or_null'")
unsigned int an_array_with_a_constant_no_nullness_out_of_bounds(void)
{
/* Out of bounds */
__u32 __attribute__((aligned(8))) key = 3;
struct test_val *val;
val = bpf_map_lookup_elem(&map_array, &key);
val->index = offsetof(struct test_val, foo);
return val->index;
}
SEC("socket")
__description("invalid map access into an array using constant smaller than key_size")
__failure __msg("R0 invalid mem access 'map_value_or_null'")
unsigned int an_array_with_a_constant_too_small(void)
{
__u32 __attribute__((aligned(8))) key;
struct test_val *val;
/* Mark entire key as STACK_MISC */
bpf_probe_read_user(&key, sizeof(key), NULL);
/* Spilling only the bottom byte results in a tnum const of 1.
* We want to check that the verifier rejects it, as the spill is < 4B.
*/
*(__u8 *)&key = 1;
val = bpf_map_lookup_elem(&map_array, &key);
/* Should fail, as verifier cannot prove in-bound lookup */
val->index = offsetof(struct test_val, foo);
return val->index;
}
SEC("socket")
__description("invalid map access into an array using constant larger than key_size")
__failure __msg("R0 invalid mem access 'map_value_or_null'")
unsigned int an_array_with_a_constant_too_big(void)
{
struct test_val *val;
__u64 key = 1;
/* Even if the constant value is < max_entries, if the spill size is
* larger than the key size, the set bits may not be where we expect them
* to be on different endian architectures.
*/
val = bpf_map_lookup_elem(&map_array, &key);
val->index = offsetof(struct test_val, foo);
return val->index;
}
SEC("socket")
__description("invalid elided lookup using const and non-const key")
__failure __msg("R0 invalid mem access 'map_value_or_null'")
unsigned int mixed_const_and_non_const_key_lookup(void)
{
__u32 __attribute__((aligned(8))) key;
struct test_val *val;
__u32 rand;
rand = bpf_get_prandom_u32();
key = rand > 42 ? 1 : rand;
val = bpf_map_lookup_elem(&map_array, &key);
return val->index;
}
SEC("socket")
__failure __msg("invalid read from stack R2 off=4096 size=4")
__naked void key_lookup_at_invalid_fp(void)
{
asm volatile (" \
r1 = %[map_array] ll; \
r2 = r10; \
r2 += 4096; \
call %[bpf_map_lookup_elem]; \
r0 = *(u64*)(r0 + 0); \
exit; \
" :
: __imm(bpf_map_lookup_elem),
__imm_addr(map_array)
: __clobber_all);
}
volatile __u32 __attribute__((aligned(8))) global_key;
SEC("socket")
__description("invalid elided lookup using non-stack key")
__failure __msg("R0 invalid mem access 'map_value_or_null'")
unsigned int non_stack_key_lookup(void)
{
struct test_val *val;
global_key = 1;
val = bpf_map_lookup_elem(&map_array, (void *)&global_key);
val->index = offsetof(struct test_val, foo);
return val->index;
}
SEC("socket")
__description("doesn't reject UINT64_MAX as s64 for irrelevant maps")
__success __retval(42)
unsigned int doesnt_reject_irrelevant_maps(void)
{
__u64 key = 0xFFFFFFFFFFFFFFFF;
struct test_val *val;
val = bpf_map_lookup_elem(&map_hash_48b, &key);
if (val)
return val->index;
return 42;
}
char _license[] SEC("license") = "GPL";
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