From d6e6286a12e7b8a4ddc66237c4ccf6f531ef1c82 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 27 Mar 2023 11:52:00 -0700 Subject: [PATCH 1/3] libbpf: disassociate section handler on explicit bpf_program__set_type() call If user explicitly overrides programs's type with bpf_program__set_type() API call, we need to disassociate whatever SEC_DEF handler libbpf determined initially based on program's SEC() definition, as it's not goind to be valid anymore and could lead to crashes and/or confusing failures. Also, fix up bpf_prog_test_load() helper in selftests/bpf, which is force-setting program type (even if that's completely unnecessary; this is quite a legacy piece of code), and thus should expect auto-attach to not work, yet one of the tests explicitly relies on auto-attach for testing. Instead, force-set program type only if it differs from the desired one. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20230327185202.1929145-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- tools/lib/bpf/libbpf.c | 1 + tools/testing/selftests/bpf/testing_helpers.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 15737d7b5a28..49cd304ae3bc 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -8468,6 +8468,7 @@ int bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type) return libbpf_err(-EBUSY); prog->type = type; + prog->sec_def = NULL; return 0; } diff --git a/tools/testing/selftests/bpf/testing_helpers.c b/tools/testing/selftests/bpf/testing_helpers.c index 6c44153755e6..ecfea13f938b 100644 --- a/tools/testing/selftests/bpf/testing_helpers.c +++ b/tools/testing/selftests/bpf/testing_helpers.c @@ -195,7 +195,7 @@ int bpf_prog_test_load(const char *file, enum bpf_prog_type type, goto err_out; } - if (type != BPF_PROG_TYPE_UNSPEC) + if (type != BPF_PROG_TYPE_UNSPEC && bpf_program__type(prog) != type) bpf_program__set_type(prog, type); flags = bpf_program__flags(prog) | BPF_F_TEST_RND_HI32; From b3c63d7ad81ad6f43921d59af18fc25c64327a74 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 27 Mar 2023 11:52:01 -0700 Subject: [PATCH 2/3] veristat: add -d debug mode option to see debug libbpf log Add -d option to allow requesting libbpf debug logs from veristat. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20230327185202.1929145-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/veristat.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/veristat.c b/tools/testing/selftests/bpf/veristat.c index 83231456d3c5..263df32fbda8 100644 --- a/tools/testing/selftests/bpf/veristat.c +++ b/tools/testing/selftests/bpf/veristat.c @@ -135,6 +135,7 @@ static struct env { char **filenames; int filename_cnt; bool verbose; + bool debug; bool quiet; int log_level; enum resfmt out_fmt; @@ -169,7 +170,7 @@ static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va { if (!env.verbose) return 0; - if (level == LIBBPF_DEBUG /* && !env.verbose */) + if (level == LIBBPF_DEBUG && !env.debug) return 0; return vfprintf(stderr, format, args); } @@ -186,6 +187,7 @@ static const struct argp_option opts[] = { { NULL, 'h', NULL, OPTION_HIDDEN, "Show the full help" }, { "verbose", 'v', NULL, 0, "Verbose mode" }, { "log-level", 'l', "LEVEL", 0, "Verifier log level (default 0 for normal mode, 1 for verbose mode)" }, + { "debug", 'd', NULL, 0, "Debug mode (turns on libbpf debug logging)" }, { "quiet", 'q', NULL, 0, "Quiet mode" }, { "emit", 'e', "SPEC", 0, "Specify stats to be emitted" }, { "sort", 's', "SPEC", 0, "Specify sort order" }, @@ -212,6 +214,10 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state) case 'v': env.verbose = true; break; + case 'd': + env.debug = true; + env.verbose = true; + break; case 'q': env.quiet = true; break; From fa7cc90620870e4444bb5184c08148495b1627c6 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 27 Mar 2023 11:52:02 -0700 Subject: [PATCH 3/3] veristat: guess and substitue underlying program type for freplace (EXT) progs SEC("freplace") (i.e., BPF_PROG_TYPE_EXT) programs are not loadable as is through veristat, as kernel expects actual program's FD during BPF_PROG_LOAD time, which veristat has no way of knowing. Unfortunately, freplace programs are a pretty important class of programs, especially when dealing with XDP chaining solutions, which rely on EXT programs. So let's do our best and teach veristat to try to guess the original program type, based on program's context argument type. And if guessing process succeeds, we manually override freplace/EXT with guessed program type using bpf_program__set_type() setter to increase chances of proper BPF verification. We rely on BTF and maintain a simple lookup table. This process is obviously not 100% bulletproof, as valid program might not use context and thus wouldn't have to specify correct type. Also, __sk_buff is very ambiguous and is the context type across many different program types. We pick BPF_PROG_TYPE_CGROUP_SKB for now, which seems to work fine in practice so far. Similarly, some program types require specifying attach type, and so we pick one out of possible few variants. Best effort at its best. But this makes veristat even more widely applicable. Signed-off-by: Andrii Nakryiko Tested-by: Eduard Zingerman Link: https://lore.kernel.org/r/20230327185202.1929145-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/veristat.c | 121 ++++++++++++++++++++++++- 1 file changed, 117 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/bpf/veristat.c b/tools/testing/selftests/bpf/veristat.c index 263df32fbda8..055df1abd7ca 100644 --- a/tools/testing/selftests/bpf/veristat.c +++ b/tools/testing/selftests/bpf/veristat.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -778,7 +779,62 @@ static int parse_verif_log(char * const buf, size_t buf_sz, struct verif_stats * return 0; } -static void fixup_obj(struct bpf_object *obj) +static int guess_prog_type_by_ctx_name(const char *ctx_name, + enum bpf_prog_type *prog_type, + enum bpf_attach_type *attach_type) +{ + /* We need to guess program type based on its declared context type. + * This guess can't be perfect as many different program types might + * share the same context type. So we can only hope to reasonably + * well guess this and get lucky. + * + * Just in case, we support both UAPI-side type names and + * kernel-internal names. + */ + static struct { + const char *uapi_name; + const char *kern_name; + enum bpf_prog_type prog_type; + enum bpf_attach_type attach_type; + } ctx_map[] = { + /* __sk_buff is most ambiguous, for now we assume cgroup_skb */ + { "__sk_buff", "sk_buff", BPF_PROG_TYPE_CGROUP_SKB, BPF_CGROUP_INET_INGRESS }, + { "bpf_sock", "sock", BPF_PROG_TYPE_CGROUP_SOCK, BPF_CGROUP_INET4_POST_BIND }, + { "bpf_sock_addr", "bpf_sock_addr_kern", BPF_PROG_TYPE_CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_BIND }, + { "bpf_sock_ops", "bpf_sock_ops_kern", BPF_PROG_TYPE_SOCK_OPS, BPF_CGROUP_SOCK_OPS }, + { "sk_msg_md", "sk_msg", BPF_PROG_TYPE_SK_MSG, BPF_SK_MSG_VERDICT }, + { "bpf_cgroup_dev_ctx", "bpf_cgroup_dev_ctx", BPF_PROG_TYPE_CGROUP_DEVICE, BPF_CGROUP_DEVICE }, + { "bpf_sysctl", "bpf_sysctl_kern", BPF_PROG_TYPE_CGROUP_SYSCTL, BPF_CGROUP_SYSCTL }, + { "bpf_sockopt", "bpf_sockopt_kern", BPF_PROG_TYPE_CGROUP_SOCKOPT, BPF_CGROUP_SETSOCKOPT }, + { "sk_reuseport_md", "sk_reuseport_kern", BPF_PROG_TYPE_SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT_OR_MIGRATE }, + { "bpf_sk_lookup", "bpf_sk_lookup_kern", BPF_PROG_TYPE_SK_LOOKUP, BPF_SK_LOOKUP }, + { "xdp_md", "xdp_buff", BPF_PROG_TYPE_XDP, BPF_XDP }, + /* tracing types with no expected attach type */ + { "bpf_user_pt_regs_t", "pt_regs", BPF_PROG_TYPE_KPROBE }, + { "bpf_perf_event_data", "bpf_perf_event_data_kern", BPF_PROG_TYPE_PERF_EVENT }, + /* raw_tp programs use u64[] from kernel side, we don't want + * to match on that, probably; so NULL for kern-side type + */ + { "bpf_raw_tracepoint_args", NULL, BPF_PROG_TYPE_RAW_TRACEPOINT }, + }; + int i; + + if (!ctx_name) + return -EINVAL; + + for (i = 0; i < ARRAY_SIZE(ctx_map); i++) { + if (strcmp(ctx_map[i].uapi_name, ctx_name) == 0 || + (ctx_map[i].kern_name && strcmp(ctx_map[i].kern_name, ctx_name) == 0)) { + *prog_type = ctx_map[i].prog_type; + *attach_type = ctx_map[i].attach_type; + return 0; + } + } + + return -ESRCH; +} + +static void fixup_obj(struct bpf_object *obj, struct bpf_program *prog, const char *filename) { struct bpf_map *map; @@ -798,18 +854,75 @@ static void fixup_obj(struct bpf_object *obj) bpf_map__set_max_entries(map, 1); } } + + /* SEC(freplace) programs can't be loaded with veristat as is, + * but we can try guessing their target program's expected type by + * looking at the type of program's first argument and substituting + * corresponding program type + */ + if (bpf_program__type(prog) == BPF_PROG_TYPE_EXT) { + const struct btf *btf = bpf_object__btf(obj); + const char *prog_name = bpf_program__name(prog); + enum bpf_prog_type prog_type; + enum bpf_attach_type attach_type; + const struct btf_type *t; + const char *ctx_name; + int id; + + if (!btf) + goto skip_freplace_fixup; + + id = btf__find_by_name_kind(btf, prog_name, BTF_KIND_FUNC); + t = btf__type_by_id(btf, id); + t = btf__type_by_id(btf, t->type); + if (!btf_is_func_proto(t) || btf_vlen(t) != 1) + goto skip_freplace_fixup; + + /* context argument is a pointer to a struct/typedef */ + t = btf__type_by_id(btf, btf_params(t)[0].type); + while (t && btf_is_mod(t)) + t = btf__type_by_id(btf, t->type); + if (!t || !btf_is_ptr(t)) + goto skip_freplace_fixup; + t = btf__type_by_id(btf, t->type); + while (t && btf_is_mod(t)) + t = btf__type_by_id(btf, t->type); + if (!t) + goto skip_freplace_fixup; + + ctx_name = btf__name_by_offset(btf, t->name_off); + + if (guess_prog_type_by_ctx_name(ctx_name, &prog_type, &attach_type) == 0) { + bpf_program__set_type(prog, prog_type); + bpf_program__set_expected_attach_type(prog, attach_type); + + if (!env.quiet) { + printf("Using guessed program type '%s' for %s/%s...\n", + libbpf_bpf_prog_type_str(prog_type), + filename, prog_name); + } + } else { + if (!env.quiet) { + printf("Failed to guess program type for freplace program with context type name '%s' for %s/%s. Consider using canonical type names to help veristat...\n", + ctx_name, filename, prog_name); + } + } + } +skip_freplace_fixup: + return; } static int process_prog(const char *filename, struct bpf_object *obj, struct bpf_program *prog) { const char *prog_name = bpf_program__name(prog); + const char *base_filename = basename(filename); size_t buf_sz = sizeof(verif_log_buf); char *buf = verif_log_buf; struct verif_stats *stats; int err = 0; void *tmp; - if (!should_process_file_prog(basename(filename), bpf_program__name(prog))) { + if (!should_process_file_prog(base_filename, bpf_program__name(prog))) { env.progs_skipped++; return 0; } @@ -835,12 +948,12 @@ static int process_prog(const char *filename, struct bpf_object *obj, struct bpf verif_log_buf[0] = '\0'; /* increase chances of successful BPF object loading */ - fixup_obj(obj); + fixup_obj(obj, prog, base_filename); err = bpf_object__load(obj); env.progs_processed++; - stats->file_name = strdup(basename(filename)); + stats->file_name = strdup(base_filename); stats->prog_name = strdup(bpf_program__name(prog)); stats->stats[VERDICT] = err == 0; /* 1 - success, 0 - failure */ parse_verif_log(buf, buf_sz, stats);