diff options
| -rw-r--r-- | include/linux/bpf_verifier.h | 9 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 15 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/verifier_spill_fill.c | 26 |
3 files changed, 39 insertions, 11 deletions
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 0dcde339dc7e..84365e6dd85d 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -919,6 +919,15 @@ static inline void mark_verifier_state_scratched(struct bpf_verifier_env *env) env->scratched_stack_slots = ~0ULL; } +static inline bool bpf_stack_narrow_access_ok(int off, int fill_size, int spill_size) +{ +#ifdef __BIG_ENDIAN + off -= spill_size - fill_size; +#endif + + return !(off % BPF_REG_SIZE); +} + const char *reg_type_str(struct bpf_verifier_env *env, enum bpf_reg_type type); const char *dynptr_type_str(enum bpf_dynptr_type type); const char *iter_type_str(const struct btf *btf, u32 btf_id); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 28f62f24da7e..82af971926ac 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4778,7 +4778,8 @@ static int check_stack_read_fixed_off(struct bpf_verifier_env *env, if (dst_regno < 0) return 0; - if (!(off % BPF_REG_SIZE) && size == spill_size) { + 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. */ @@ -4786,6 +4787,12 @@ static int check_stack_read_fixed_off(struct bpf_verifier_env *env, 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; @@ -6061,10 +6068,10 @@ static void coerce_reg_to_size(struct bpf_reg_state *reg, int size) * values are also truncated so we push 64-bit bounds into * 32-bit bounds. Above were truncated < 32-bits already. */ - if (size < 4) { + if (size < 4) __mark_reg32_unbounded(reg); - reg_bounds_sync(reg); - } + + reg_bounds_sync(reg); } static void set_sext64_default_val(struct bpf_reg_state *reg, int size) diff --git a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c index f9803005e1c0..3e5d063ea7e8 100644 --- a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c +++ b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c @@ -217,7 +217,7 @@ __naked void uninit_u32_from_the_stack(void) SEC("tc") __description("Spill a u32 const scalar. Refill as u16. Offset to skb->data") -__failure __msg("invalid access to packet") +__success __retval(0) __naked void u16_offset_to_skb_data(void) { asm volatile (" \ @@ -225,13 +225,19 @@ __naked void u16_offset_to_skb_data(void) r3 = *(u32*)(r1 + %[__sk_buff_data_end]); \ w4 = 20; \ *(u32*)(r10 - 8) = r4; \ - r4 = *(u16*)(r10 - 8); \ + " +#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ + "r4 = *(u16*)(r10 - 8);" +#else + "r4 = *(u16*)(r10 - 6);" +#endif + " \ r0 = r2; \ - /* r0 += r4 R0=pkt R2=pkt R3=pkt_end R4=umax=65535 */\ + /* r0 += r4 R0=pkt R2=pkt R3=pkt_end R4=20 */\ r0 += r4; \ - /* if (r0 > r3) R0=pkt,umax=65535 R2=pkt R3=pkt_end R4=umax=65535 */\ + /* if (r0 > r3) R0=pkt,off=20 R2=pkt R3=pkt_end R4=20 */\ if r0 > r3 goto l0_%=; \ - /* r0 = *(u32 *)r2 R0=pkt,umax=65535 R2=pkt R3=pkt_end R4=20 */\ + /* r0 = *(u32 *)r2 R0=pkt,off=20 R2=pkt R3=pkt_end R4=20 */\ r0 = *(u32*)(r2 + 0); \ l0_%=: r0 = 0; \ exit; \ @@ -268,7 +274,7 @@ l0_%=: r0 = 0; \ } SEC("tc") -__description("Spill a u32 const scalar. Refill as u16 from fp-6. Offset to skb->data") +__description("Spill a u32 const scalar. Refill as u16 from MSB. Offset to skb->data") __failure __msg("invalid access to packet") __naked void _6_offset_to_skb_data(void) { @@ -277,7 +283,13 @@ __naked void _6_offset_to_skb_data(void) r3 = *(u32*)(r1 + %[__sk_buff_data_end]); \ w4 = 20; \ *(u32*)(r10 - 8) = r4; \ - r4 = *(u16*)(r10 - 6); \ + " +#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ + "r4 = *(u16*)(r10 - 6);" +#else + "r4 = *(u16*)(r10 - 8);" +#endif + " \ r0 = r2; \ /* r0 += r4 R0=pkt R2=pkt R3=pkt_end R4=umax=65535 */\ r0 += r4; \ |