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Date: Sun, 25 Aug 2019 22:22:13 -0700
From: Song Liu <liu.song.a23@...il.com>
To: Alexei Starovoitov <ast@...nel.org>
Cc: "David S . Miller" <davem@...emloft.net>,
Daniel Borkmann <daniel@...earbox.net>,
Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
Kernel Team <kernel-team@...com>
Subject: Re: [PATCH bpf-next 3/4] selftests/bpf: verifier precise tests
On Fri, Aug 23, 2019 at 2:59 AM Alexei Starovoitov <ast@...nel.org> wrote:
>
> Use BPF_F_TEST_STATE_FREQ flag to check that precision
> tracking works as expected by comparing every step it takes.
>
> Signed-off-by: Alexei Starovoitov <ast@...nel.org>
> ---
> tools/testing/selftests/bpf/test_verifier.c | 68 ++++++++--
> .../testing/selftests/bpf/verifier/precise.c | 117 ++++++++++++++++++
> 2 files changed, 174 insertions(+), 11 deletions(-)
> create mode 100644 tools/testing/selftests/bpf/verifier/precise.c
>
> diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
> index 44e2d640b088..d27fd929abb9 100644
> --- a/tools/testing/selftests/bpf/test_verifier.c
> +++ b/tools/testing/selftests/bpf/test_verifier.c
> @@ -61,6 +61,7 @@
> #define UNPRIV_SYSCTL "kernel/unprivileged_bpf_disabled"
> static bool unpriv_disabled = false;
> static int skips;
> +static bool verbose = false;
>
> struct bpf_test {
> const char *descr;
> @@ -92,7 +93,8 @@ struct bpf_test {
> enum {
> UNDEF,
> ACCEPT,
> - REJECT
> + REJECT,
> + VERBOSE_ACCEPT,
> } result, result_unpriv;
> enum bpf_prog_type prog_type;
> uint8_t flags;
> @@ -859,6 +861,36 @@ static int do_prog_test_run(int fd_prog, bool unpriv, uint32_t expected_val,
> return 0;
> }
>
> +static bool cmp_str_seq(const char *log, const char *exp)
Maybe call it str_str_seq()?
> +{
> + char needle[80];
> + const char *p, *q;
> + int len;
> +
> + do {
> + p = strchr(exp, '\t');
> + if (!p)
> + p = exp + strlen(exp);
> +
> + len = p - exp;
> + if (len >= sizeof(needle) || !len) {
> + printf("FAIL\nTestcase bug\n");
> + return false;
> + }
> + strncpy(needle, exp, len);
> + needle[len] = 0;
> + q = strstr(log, needle);
> + if (!q) {
> + printf("FAIL\nUnexpected verifier log in successful load!\n"
> + "EXP: %s\nRES:\n", needle);
> + return false;
> + }
> + log = q + len;
> + exp = p + 1;
> + } while (*p);
> + return true;
> +}
> +
> static void do_test_single(struct bpf_test *test, bool unpriv,
> int *passes, int *errors)
> {
> @@ -897,14 +929,20 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
> pflags |= BPF_F_STRICT_ALIGNMENT;
> if (test->flags & F_NEEDS_EFFICIENT_UNALIGNED_ACCESS)
> pflags |= BPF_F_ANY_ALIGNMENT;
> + if (test->flags & ~3)
> + pflags |= test->flags;
^^^^^^ why do we need these two lines?
>
> + expected_ret = unpriv && test->result_unpriv != UNDEF ?
> + test->result_unpriv : test->result;
> + expected_err = unpriv && test->errstr_unpriv ?
> + test->errstr_unpriv : test->errstr;
> memset(&attr, 0, sizeof(attr));
> attr.prog_type = prog_type;
> attr.expected_attach_type = test->expected_attach_type;
> attr.insns = prog;
> attr.insns_cnt = prog_len;
> attr.license = "GPL";
> - attr.log_level = 4;
> + attr.log_level = verbose || expected_ret == VERBOSE_ACCEPT ? 1 : 4;
> attr.prog_flags = pflags;
>
> fd_prog = bpf_load_program_xattr(&attr, bpf_vlog, sizeof(bpf_vlog));
> @@ -914,14 +952,9 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
> goto close_fds;
> }
>
> - expected_ret = unpriv && test->result_unpriv != UNDEF ?
> - test->result_unpriv : test->result;
> - expected_err = unpriv && test->errstr_unpriv ?
> - test->errstr_unpriv : test->errstr;
> -
> alignment_prevented_execution = 0;
>
> - if (expected_ret == ACCEPT) {
> + if (expected_ret == ACCEPT || expected_ret == VERBOSE_ACCEPT) {
> if (fd_prog < 0) {
> printf("FAIL\nFailed to load prog '%s'!\n",
> strerror(errno));
> @@ -932,6 +965,9 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
> (test->flags & F_NEEDS_EFFICIENT_UNALIGNED_ACCESS))
> alignment_prevented_execution = 1;
> #endif
> + if (expected_ret == VERBOSE_ACCEPT && !cmp_str_seq(bpf_vlog, expected_err)) {
> + goto fail_log;
> + }
> } else {
> if (fd_prog >= 0) {
> printf("FAIL\nUnexpected success to load!\n");
> @@ -957,6 +993,9 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
> }
> }
>
> + if (verbose)
> + printf(", verifier log:\n%s", bpf_vlog);
> +
> run_errs = 0;
> run_successes = 0;
> if (!alignment_prevented_execution && fd_prog >= 0) {
> @@ -1097,17 +1136,24 @@ int main(int argc, char **argv)
> {
> unsigned int from = 0, to = ARRAY_SIZE(tests);
> bool unpriv = !is_admin();
> + int arg = 1;
> +
> + if (argc > 1 && strcmp(argv[1], "-v") == 0) {
> + arg++;
> + verbose = true;
> + argc--;
> + }
>
> if (argc == 3) {
> - unsigned int l = atoi(argv[argc - 2]);
> - unsigned int u = atoi(argv[argc - 1]);
> + unsigned int l = atoi(argv[arg]);
> + unsigned int u = atoi(argv[arg + 1]);
>
> if (l < to && u < to) {
> from = l;
> to = u + 1;
> }
> } else if (argc == 2) {
> - unsigned int t = atoi(argv[argc - 1]);
> + unsigned int t = atoi(argv[arg]);
>
> if (t < to) {
> from = t;
> diff --git a/tools/testing/selftests/bpf/verifier/precise.c b/tools/testing/selftests/bpf/verifier/precise.c
> new file mode 100644
> index 000000000000..a20953c23721
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/verifier/precise.c
> @@ -0,0 +1,117 @@
> +{
> + "precise: test 1",
> + .insns = {
> + BPF_MOV64_IMM(BPF_REG_0, 1),
> + BPF_LD_MAP_FD(BPF_REG_6, 0),
> + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
> + BPF_MOV64_REG(BPF_REG_2, BPF_REG_FP),
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
> + BPF_ST_MEM(BPF_DW, BPF_REG_FP, -8, 0),
> + BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
> + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
> + BPF_EXIT_INSN(),
> +
> + BPF_MOV64_REG(BPF_REG_9, BPF_REG_0),
> +
> + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
> + BPF_MOV64_REG(BPF_REG_2, BPF_REG_FP),
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
> + BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
> + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
> + BPF_EXIT_INSN(),
> +
> + BPF_MOV64_REG(BPF_REG_8, BPF_REG_0),
> +
> + BPF_ALU64_REG(BPF_SUB, BPF_REG_9, BPF_REG_8), /* map_value_ptr -= map_value_ptr */
> + BPF_MOV64_REG(BPF_REG_2, BPF_REG_9),
> + BPF_JMP_IMM(BPF_JLT, BPF_REG_2, 8, 1),
> + BPF_EXIT_INSN(),
> +
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, 1), /* R2=inv(umin=1, umax=8) */
> + BPF_MOV64_REG(BPF_REG_1, BPF_REG_FP),
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8),
> + BPF_MOV64_IMM(BPF_REG_3, 0),
> + BPF_EMIT_CALL(BPF_FUNC_probe_read),
> + BPF_EXIT_INSN(),
> + },
> + .prog_type = BPF_PROG_TYPE_TRACEPOINT,
> + .fixup_map_array_48b = { 1 },
> + .result = VERBOSE_ACCEPT,
> + .errstr =
> + "26: (85) call bpf_probe_read#4\
> + last_idx 26 first_idx 20\
> + regs=4 stack=0 before 25\
> + regs=4 stack=0 before 24\
> + regs=4 stack=0 before 23\
> + regs=4 stack=0 before 22\
> + regs=4 stack=0 before 20\
> + parent didn't have regs=4 stack=0 marks\
> + last_idx 19 first_idx 10\
> + regs=4 stack=0 before 19\
> + regs=200 stack=0 before 18\
> + regs=300 stack=0 before 17\
> + regs=201 stack=0 before 15\
> + regs=201 stack=0 before 14\
> + regs=200 stack=0 before 13\
> + regs=200 stack=0 before 12\
> + regs=200 stack=0 before 11\
> + regs=200 stack=0 before 10\
> + parent already had regs=0 stack=0 marks",
> +},
> +{
> + "precise: test 2",
> + .insns = {
> + BPF_MOV64_IMM(BPF_REG_0, 1),
> + BPF_LD_MAP_FD(BPF_REG_6, 0),
> + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
> + BPF_MOV64_REG(BPF_REG_2, BPF_REG_FP),
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
> + BPF_ST_MEM(BPF_DW, BPF_REG_FP, -8, 0),
> + BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
> + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
> + BPF_EXIT_INSN(),
> +
> + BPF_MOV64_REG(BPF_REG_9, BPF_REG_0),
> +
> + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
> + BPF_MOV64_REG(BPF_REG_2, BPF_REG_FP),
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
> + BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
> + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
> + BPF_EXIT_INSN(),
> +
> + BPF_MOV64_REG(BPF_REG_8, BPF_REG_0),
> +
> + BPF_ALU64_REG(BPF_SUB, BPF_REG_9, BPF_REG_8), /* map_value_ptr -= map_value_ptr */
> + BPF_MOV64_REG(BPF_REG_2, BPF_REG_9),
> + BPF_JMP_IMM(BPF_JLT, BPF_REG_2, 8, 1),
> + BPF_EXIT_INSN(),
> +
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, 1), /* R2=inv(umin=1, umax=8) */
> + BPF_MOV64_REG(BPF_REG_1, BPF_REG_FP),
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8),
> + BPF_MOV64_IMM(BPF_REG_3, 0),
> + BPF_EMIT_CALL(BPF_FUNC_probe_read),
> + BPF_EXIT_INSN(),
> + },
> + .prog_type = BPF_PROG_TYPE_TRACEPOINT,
> + .fixup_map_array_48b = { 1 },
> + .result = VERBOSE_ACCEPT,
> + .flags = BPF_F_TEST_STATE_FREQ,
> + .errstr =
> + "26: (85) call bpf_probe_read#4\
> + last_idx 26 first_idx 22\
> + regs=4 stack=0 before 25\
> + regs=4 stack=0 before 24\
> + regs=4 stack=0 before 23\
> + regs=4 stack=0 before 22\
> + parent didn't have regs=4 stack=0 marks\
> + last_idx 20 first_idx 20\
> + regs=4 stack=0 before 20\
> + parent didn't have regs=4 stack=0 marks\
> + last_idx 19 first_idx 17\
> + regs=4 stack=0 before 19\
> + regs=200 stack=0 before 18\
> + regs=300 stack=0 before 17\
> + parent already had regs=0 stack=0 marks",
> +},
> --
> 2.20.0
>
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