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selftests/bpf: specify expected instructions in test_verifier tests
Allows to specify expected and unexpected instruction sequences in
test_verifier test cases. The instructions are requested from kernel
after BPF program loading, thus allowing to check some of the
transformations applied by BPF verifier.
- `expected_insn` field specifies a sequence of instructions expected
to be found in the program;
- `unexpected_insn` field specifies a sequence of instructions that
are not expected to be found in the program;
- `INSN_OFF_MASK` and `INSN_IMM_MASK` values could be used to mask
`off` and `imm` fields.
- `SKIP_INSNS` could be used to specify that some instructions in the
(un)expected pattern are not important (behavior similar to usage of
`\t` in `errstr` field).
The intended usage is as follows:
{
"inline simple bpf_loop call",
.insns = {
/* main */
BPF_ALU64_IMM(BPF_MOV, BPF_REG_1, 1),
BPF_RAW_INSN(BPF_LD | BPF_IMM | BPF_DW, BPF_REG_2,
BPF_PSEUDO_FUNC, 0, 6),
...
BPF_EXIT_INSN(),
/* callback */
BPF_ALU64_IMM(BPF_MOV, BPF_REG_0, 1),
BPF_EXIT_INSN(),
},
.expected_insns = {
BPF_ALU64_IMM(BPF_MOV, BPF_REG_1, 1),
SKIP_INSNS(),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_CALL, 8, 1)
},
.unexpected_insns = {
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0,
INSN_OFF_MASK, INSN_IMM_MASK),
},
.prog_type = BPF_PROG_TYPE_TRACEPOINT,
.result = ACCEPT,
.runs = 0,
},
Here it is expected that move of 1 to register 1 would remain in place
and helper function call instruction would be replaced by a relative
call instruction.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/r/20220620235344.569325-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Eduard Zingerman
Alexei Starovoitov
parent
aca80dd95e
commit
933ff53191
1 changed files with 234 additions and 0 deletions
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@ -51,6 +51,8 @@
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#endif
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#define MAX_INSNS BPF_MAXINSNS
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#define MAX_EXPECTED_INSNS 32
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#define MAX_UNEXPECTED_INSNS 32
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#define MAX_TEST_INSNS 1000000
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#define MAX_FIXUPS 8
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#define MAX_NR_MAPS 23
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@ -58,6 +60,10 @@
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#define POINTER_VALUE 0xcafe4all
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#define TEST_DATA_LEN 64
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#define INSN_OFF_MASK ((__s16)0xFFFF)
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#define INSN_IMM_MASK ((__s32)0xFFFFFFFF)
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#define SKIP_INSNS() BPF_RAW_INSN(0xde, 0xa, 0xd, 0xbeef, 0xdeadbeef)
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#define F_NEEDS_EFFICIENT_UNALIGNED_ACCESS (1 << 0)
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#define F_LOAD_WITH_STRICT_ALIGNMENT (1 << 1)
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@ -79,6 +85,23 @@ struct bpf_test {
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const char *descr;
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struct bpf_insn insns[MAX_INSNS];
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struct bpf_insn *fill_insns;
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/* If specified, test engine looks for this sequence of
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* instructions in the BPF program after loading. Allows to
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* test rewrites applied by verifier. Use values
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* INSN_OFF_MASK and INSN_IMM_MASK to mask `off` and `imm`
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* fields if content does not matter. The test case fails if
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* specified instructions are not found.
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*
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* The sequence could be split into sub-sequences by adding
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* SKIP_INSNS instruction at the end of each sub-sequence. In
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* such case sub-sequences are searched for one after another.
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*/
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struct bpf_insn expected_insns[MAX_EXPECTED_INSNS];
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/* If specified, test engine applies same pattern matching
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* logic as for `expected_insns`. If the specified pattern is
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* matched test case is marked as failed.
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*/
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struct bpf_insn unexpected_insns[MAX_UNEXPECTED_INSNS];
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int fixup_map_hash_8b[MAX_FIXUPS];
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int fixup_map_hash_48b[MAX_FIXUPS];
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int fixup_map_hash_16b[MAX_FIXUPS];
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@ -1126,6 +1149,214 @@ static bool cmp_str_seq(const char *log, const char *exp)
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return true;
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}
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static int get_xlated_program(int fd_prog, struct bpf_insn **buf, int *cnt)
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{
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struct bpf_prog_info info = {};
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__u32 info_len = sizeof(info);
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__u32 xlated_prog_len;
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__u32 buf_element_size = sizeof(struct bpf_insn);
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if (bpf_obj_get_info_by_fd(fd_prog, &info, &info_len)) {
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perror("bpf_obj_get_info_by_fd failed");
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return -1;
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}
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xlated_prog_len = info.xlated_prog_len;
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if (xlated_prog_len % buf_element_size) {
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printf("Program length %d is not multiple of %d\n",
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xlated_prog_len, buf_element_size);
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return -1;
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}
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*cnt = xlated_prog_len / buf_element_size;
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*buf = calloc(*cnt, buf_element_size);
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if (!buf) {
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perror("can't allocate xlated program buffer");
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return -ENOMEM;
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}
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bzero(&info, sizeof(info));
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info.xlated_prog_len = xlated_prog_len;
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info.xlated_prog_insns = (__u64)*buf;
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if (bpf_obj_get_info_by_fd(fd_prog, &info, &info_len)) {
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perror("second bpf_obj_get_info_by_fd failed");
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goto out_free_buf;
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}
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return 0;
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out_free_buf:
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free(*buf);
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return -1;
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}
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static bool is_null_insn(struct bpf_insn *insn)
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{
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struct bpf_insn null_insn = {};
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return memcmp(insn, &null_insn, sizeof(null_insn)) == 0;
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}
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static bool is_skip_insn(struct bpf_insn *insn)
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{
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struct bpf_insn skip_insn = SKIP_INSNS();
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return memcmp(insn, &skip_insn, sizeof(skip_insn)) == 0;
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}
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static int null_terminated_insn_len(struct bpf_insn *seq, int max_len)
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{
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int i;
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for (i = 0; i < max_len; ++i) {
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if (is_null_insn(&seq[i]))
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return i;
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}
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return max_len;
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}
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static bool compare_masked_insn(struct bpf_insn *orig, struct bpf_insn *masked)
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{
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struct bpf_insn orig_masked;
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memcpy(&orig_masked, orig, sizeof(orig_masked));
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if (masked->imm == INSN_IMM_MASK)
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orig_masked.imm = INSN_IMM_MASK;
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if (masked->off == INSN_OFF_MASK)
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orig_masked.off = INSN_OFF_MASK;
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return memcmp(&orig_masked, masked, sizeof(orig_masked)) == 0;
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}
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static int find_insn_subseq(struct bpf_insn *seq, struct bpf_insn *subseq,
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int seq_len, int subseq_len)
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{
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int i, j;
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if (subseq_len > seq_len)
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return -1;
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for (i = 0; i < seq_len - subseq_len + 1; ++i) {
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bool found = true;
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for (j = 0; j < subseq_len; ++j) {
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if (!compare_masked_insn(&seq[i + j], &subseq[j])) {
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found = false;
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break;
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}
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}
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if (found)
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return i;
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}
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return -1;
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}
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static int find_skip_insn_marker(struct bpf_insn *seq, int len)
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{
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int i;
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for (i = 0; i < len; ++i)
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if (is_skip_insn(&seq[i]))
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return i;
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return -1;
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}
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/* Return true if all sub-sequences in `subseqs` could be found in
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* `seq` one after another. Sub-sequences are separated by a single
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* nil instruction.
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*/
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static bool find_all_insn_subseqs(struct bpf_insn *seq, struct bpf_insn *subseqs,
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int seq_len, int max_subseqs_len)
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{
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int subseqs_len = null_terminated_insn_len(subseqs, max_subseqs_len);
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while (subseqs_len > 0) {
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int skip_idx = find_skip_insn_marker(subseqs, subseqs_len);
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int cur_subseq_len = skip_idx < 0 ? subseqs_len : skip_idx;
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int subseq_idx = find_insn_subseq(seq, subseqs,
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seq_len, cur_subseq_len);
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if (subseq_idx < 0)
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return false;
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seq += subseq_idx + cur_subseq_len;
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seq_len -= subseq_idx + cur_subseq_len;
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subseqs += cur_subseq_len + 1;
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subseqs_len -= cur_subseq_len + 1;
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}
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return true;
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}
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static void print_insn(struct bpf_insn *buf, int cnt)
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{
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int i;
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printf(" addr op d s off imm\n");
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for (i = 0; i < cnt; ++i) {
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struct bpf_insn *insn = &buf[i];
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if (is_null_insn(insn))
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break;
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if (is_skip_insn(insn))
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printf(" ...\n");
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else
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printf(" %04x: %02x %1x %x %04hx %08x\n",
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i, insn->code, insn->dst_reg,
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insn->src_reg, insn->off, insn->imm);
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}
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}
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static bool check_xlated_program(struct bpf_test *test, int fd_prog)
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{
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struct bpf_insn *buf;
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int cnt;
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bool result = true;
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bool check_expected = !is_null_insn(test->expected_insns);
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bool check_unexpected = !is_null_insn(test->unexpected_insns);
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if (!check_expected && !check_unexpected)
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goto out;
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if (get_xlated_program(fd_prog, &buf, &cnt)) {
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printf("FAIL: can't get xlated program\n");
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result = false;
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goto out;
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}
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if (check_expected &&
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!find_all_insn_subseqs(buf, test->expected_insns,
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cnt, MAX_EXPECTED_INSNS)) {
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printf("FAIL: can't find expected subsequence of instructions\n");
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result = false;
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if (verbose) {
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printf("Program:\n");
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print_insn(buf, cnt);
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printf("Expected subsequence:\n");
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print_insn(test->expected_insns, MAX_EXPECTED_INSNS);
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}
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}
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if (check_unexpected &&
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find_all_insn_subseqs(buf, test->unexpected_insns,
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cnt, MAX_UNEXPECTED_INSNS)) {
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printf("FAIL: found unexpected subsequence of instructions\n");
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result = false;
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if (verbose) {
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printf("Program:\n");
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print_insn(buf, cnt);
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printf("Un-expected subsequence:\n");
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print_insn(test->unexpected_insns, MAX_UNEXPECTED_INSNS);
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}
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}
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free(buf);
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out:
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return result;
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}
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static void do_test_single(struct bpf_test *test, bool unpriv,
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int *passes, int *errors)
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{
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@ -1262,6 +1493,9 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
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if (verbose)
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printf(", verifier log:\n%s", bpf_vlog);
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if (!check_xlated_program(test, fd_prog))
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goto fail_log;
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run_errs = 0;
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run_successes = 0;
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if (!alignment_prevented_execution && fd_prog >= 0 && test->runs >= 0) {
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