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Merge branch 'narrow-loads'

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Andrey Ignatov says:

====================
This patch set adds support for narrow loads with offset > 0 to BPF
verifier.

Patch 1 provides more details and is the main patch in the set.
Patches 2 and 3 add new test cases to test_verifier and test_sock_addr
selftests.

v1->v2:
- fix -Wdeclaration-after-statement warning.
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov
2018-11-10 22:29:59 -08:00
parent f2cbf95826 e7605475f5
commit 407be8d03e
4 changed files with 79 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
include/linux/filter.h
View File

@@ -668,24 +668,10 @@ static inline u32 bpf_ctx_off_adjust_machine(u32 size)
return size;
}
static inline bool bpf_ctx_narrow_align_ok(u32 off, u32 size_access,
u32 size_default)
{
size_default = bpf_ctx_off_adjust_machine(size_default);
size_access = bpf_ctx_off_adjust_machine(size_access);
#ifdef __LITTLE_ENDIAN
return (off & (size_default - 1)) == 0;
#else
return (off & (size_default - 1)) + size_access == size_default;
#endif
}
static inline bool
bpf_ctx_narrow_access_ok(u32 off, u32 size, u32 size_default)
{
return bpf_ctx_narrow_align_ok(off, size, size_default) &&
size <= size_default && (size & (size - 1)) == 0;
return size <= size_default && (size & (size - 1)) == 0;
}
#define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0]))

21
kernel/bpf/verifier.c
View File

@@ -5718,10 +5718,10 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
int i, cnt, size, ctx_field_size, delta = 0;
const int insn_cnt = env->prog->len;
struct bpf_insn insn_buf[16], *insn;
u32 target_size, size_default, off;
struct bpf_prog *new_prog;
enum bpf_access_type type;
bool is_narrower_load;
u32 target_size;
if (ops->gen_prologue || env->seen_direct_write) {
if (!ops->gen_prologue) {
@@ -5814,9 +5814,9 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
* 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) {
u32 size_default = bpf_ctx_off_adjust_machine(ctx_field_size);
u32 off = insn->off;
u8 size_code;
if (type == BPF_WRITE) {
@@ -5844,12 +5844,23 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
}
if (is_narrower_load && size < target_size) {
if (ctx_field_size <= 4)
u8 shift = (off & (size_default - 1)) * 8;
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
} else {
if (shift)
insn_buf[cnt++] = BPF_ALU64_IMM(BPF_RSH,
insn->dst_reg,
shift);
insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg,
(1 << size * 8) - 1);
}
}
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);

28
tools/testing/selftests/bpf/test_sock_addr.c
View File

@@ -574,24 +574,44 @@ static int bind4_prog_load(const struct sock_addr_test *test)
/* if (sk.family == AF_INET && */
BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
offsetof(struct bpf_sock_addr, family)),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, AF_INET, 16),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, AF_INET, 24),
/* (sk.type == SOCK_DGRAM || sk.type == SOCK_STREAM) && */
BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
offsetof(struct bpf_sock_addr, type)),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, SOCK_DGRAM, 1),
BPF_JMP_A(1),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, SOCK_STREAM, 12),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, SOCK_STREAM, 20),
/* 1st_byte_of_user_ip4 == expected && */
BPF_LDX_MEM(BPF_B, BPF_REG_7, BPF_REG_6,
offsetof(struct bpf_sock_addr, user_ip4)),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, ip4.u4_addr8[0], 10),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, ip4.u4_addr8[0], 18),
/* 2nd_byte_of_user_ip4 == expected && */
BPF_LDX_MEM(BPF_B, BPF_REG_7, BPF_REG_6,
offsetof(struct bpf_sock_addr, user_ip4) + 1),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, ip4.u4_addr8[1], 16),
/* 3rd_byte_of_user_ip4 == expected && */
BPF_LDX_MEM(BPF_B, BPF_REG_7, BPF_REG_6,
offsetof(struct bpf_sock_addr, user_ip4) + 2),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, ip4.u4_addr8[2], 14),
/* 4th_byte_of_user_ip4 == expected && */
BPF_LDX_MEM(BPF_B, BPF_REG_7, BPF_REG_6,
offsetof(struct bpf_sock_addr, user_ip4) + 3),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, ip4.u4_addr8[3], 12),
/* 1st_half_of_user_ip4 == expected && */
BPF_LDX_MEM(BPF_H, BPF_REG_7, BPF_REG_6,
offsetof(struct bpf_sock_addr, user_ip4)),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, ip4.u4_addr16[0], 8),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, ip4.u4_addr16[0], 10),
/* 2nd_half_of_user_ip4 == expected && */
BPF_LDX_MEM(BPF_H, BPF_REG_7, BPF_REG_6,
offsetof(struct bpf_sock_addr, user_ip4) + 2),
BPF_JMP_IMM(BPF_JNE, BPF_REG_7, ip4.u4_addr16[1], 8),
/* whole_user_ip4 == expected) { */
BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,

48
tools/testing/selftests/bpf/test_verifier.c
View File

@@ -2026,29 +2026,27 @@ static struct bpf_test tests[] = {
.result = ACCEPT,
},
{
"check skb->hash byte load not permitted 1",
"check skb->hash byte load permitted 1",
.insns = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_1,
offsetof(struct __sk_buff, hash) + 1),
BPF_EXIT_INSN(),
},
.errstr = "invalid bpf_context access",
.result = REJECT,
.result = ACCEPT,
},
{
"check skb->hash byte load not permitted 2",
"check skb->hash byte load permitted 2",
.insns = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_1,
offsetof(struct __sk_buff, hash) + 2),
BPF_EXIT_INSN(),
},
.errstr = "invalid bpf_context access",
.result = REJECT,
.result = ACCEPT,
},
{
"check skb->hash byte load not permitted 3",
"check skb->hash byte load permitted 3",
.insns = {
BPF_MOV64_IMM(BPF_REG_0, 0),
#if __BYTE_ORDER == __LITTLE_ENDIAN
@@ -2060,8 +2058,7 @@ static struct bpf_test tests[] = {
#endif
BPF_EXIT_INSN(),
},
.errstr = "invalid bpf_context access",
.result = REJECT,
.result = ACCEPT,
},
{
"check cb access: byte, wrong type",
@@ -2173,7 +2170,7 @@ static struct bpf_test tests[] = {
.result = ACCEPT,
},
{
"check skb->hash half load not permitted",
"check skb->hash half load permitted 2",
.insns = {
BPF_MOV64_IMM(BPF_REG_0, 0),
#if __BYTE_ORDER == __LITTLE_ENDIAN
@@ -2182,6 +2179,37 @@ static struct bpf_test tests[] = {
#else
BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
offsetof(struct __sk_buff, hash)),
#endif
BPF_EXIT_INSN(),
},
.result = ACCEPT,
},
{
"check skb->hash half load not permitted, unaligned 1",
.insns = {
BPF_MOV64_IMM(BPF_REG_0, 0),
#if __BYTE_ORDER == __LITTLE_ENDIAN
BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
offsetof(struct __sk_buff, hash) + 1),
#else
BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
offsetof(struct __sk_buff, hash) + 3),
#endif
BPF_EXIT_INSN(),
},
.errstr = "invalid bpf_context access",
.result = REJECT,
},
{
"check skb->hash half load not permitted, unaligned 3",
.insns = {
BPF_MOV64_IMM(BPF_REG_0, 0),
#if __BYTE_ORDER == __LITTLE_ENDIAN
BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
offsetof(struct __sk_buff, hash) + 3),
#else
BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
offsetof(struct __sk_buff, hash) + 1),
#endif
BPF_EXIT_INSN(),
},