diff options
author | Andrii Nakryiko <andrii@kernel.org> | 2022-06-28 00:15:26 +0300 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2022-06-28 23:13:33 +0300 |
commit | bd054102a8c7f36ff03446cc41822601180241f3 (patch) | |
tree | c6933c1c7cce03aabda6c10b93ca19408a802e86 /tools/lib | |
parent | 31e42721976b9c445477038f8a4006150cd27a60 (diff) | |
download | linux-bd054102a8c7f36ff03446cc41822601180241f3.tar.xz |
libbpf: enforce strict libbpf 1.0 behaviors
Remove support for legacy features and behaviors that previously had to
be disabled by calling libbpf_set_strict_mode():
- legacy BPF map definitions are not supported now;
- RLIMIT_MEMLOCK auto-setting, if necessary, is always on (but see
libbpf_set_memlock_rlim());
- program name is used for program pinning (instead of section name);
- cleaned up error returning logic;
- entry BPF programs should have SEC() always.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220627211527.2245459-15-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools/lib')
-rw-r--r-- | tools/lib/bpf/bpf.c | 4 | ||||
-rw-r--r-- | tools/lib/bpf/libbpf.c | 212 | ||||
-rw-r--r-- | tools/lib/bpf/libbpf.h | 34 | ||||
-rw-r--r-- | tools/lib/bpf/libbpf_internal.h | 24 | ||||
-rw-r--r-- | tools/lib/bpf/libbpf_legacy.h | 24 |
5 files changed, 37 insertions, 261 deletions
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index 2f3495d80d69..6d848b02c1e0 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -147,10 +147,6 @@ int bump_rlimit_memlock(void) { struct rlimit rlim; - /* this the default in libbpf 1.0, but for now user has to opt-in explicitly */ - if (!(libbpf_mode & LIBBPF_STRICT_AUTO_RLIMIT_MEMLOCK)) - return 0; - /* if kernel supports memcg-based accounting, skip bumping RLIMIT_MEMLOCK */ if (memlock_bumped || kernel_supports(NULL, FEAT_MEMCG_ACCOUNT)) return 0; diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index ae58cf2898ad..e994797bcd48 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -278,12 +278,9 @@ static inline __u64 ptr_to_u64(const void *ptr) return (__u64) (unsigned long) ptr; } -/* this goes away in libbpf 1.0 */ -enum libbpf_strict_mode libbpf_mode = LIBBPF_STRICT_NONE; - int libbpf_set_strict_mode(enum libbpf_strict_mode mode) { - libbpf_mode = mode; + /* as of v1.0 libbpf_set_strict_mode() is a no-op */ return 0; } @@ -367,9 +364,10 @@ struct bpf_sec_def { * linux/filter.h. */ struct bpf_program { - const struct bpf_sec_def *sec_def; + char *name; char *sec_name; size_t sec_idx; + const struct bpf_sec_def *sec_def; /* this program's instruction offset (in number of instructions) * within its containing ELF section */ @@ -389,12 +387,6 @@ struct bpf_program { */ size_t sub_insn_off; - char *name; - /* name with / replaced by _; makes recursive pinning - * in bpf_object__pin_programs easier - */ - char *pin_name; - /* instructions that belong to BPF program; insns[0] is located at * sec_insn_off instruction within its ELF section in ELF file, so * when mapping ELF file instruction index to the local instruction, @@ -695,7 +687,6 @@ static void bpf_program__exit(struct bpf_program *prog) bpf_program__unload(prog); zfree(&prog->name); zfree(&prog->sec_name); - zfree(&prog->pin_name); zfree(&prog->insns); zfree(&prog->reloc_desc); @@ -704,26 +695,6 @@ static void bpf_program__exit(struct bpf_program *prog) prog->sec_idx = -1; } -static char *__bpf_program__pin_name(struct bpf_program *prog) -{ - char *name, *p; - - if (libbpf_mode & LIBBPF_STRICT_SEC_NAME) - name = strdup(prog->name); - else - name = strdup(prog->sec_name); - - if (!name) - return NULL; - - p = name; - - while ((p = strchr(p, '/'))) - *p = '_'; - - return name; -} - static bool insn_is_subprog_call(const struct bpf_insn *insn) { return BPF_CLASS(insn->code) == BPF_JMP && @@ -790,10 +761,6 @@ bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog, if (!prog->name) goto errout; - prog->pin_name = __bpf_program__pin_name(prog); - if (!prog->pin_name) - goto errout; - prog->insns = malloc(insn_data_sz); if (!prog->insns) goto errout; @@ -2007,143 +1974,6 @@ static int bpf_object__init_kconfig_map(struct bpf_object *obj) return 0; } -static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict) -{ - Elf_Data *symbols = obj->efile.symbols; - int i, map_def_sz = 0, nr_maps = 0, nr_syms; - Elf_Data *data = NULL; - Elf_Scn *scn; - - if (obj->efile.maps_shndx < 0) - return 0; - - if (libbpf_mode & LIBBPF_STRICT_MAP_DEFINITIONS) { - pr_warn("legacy map definitions in SEC(\"maps\") are not supported\n"); - return -EOPNOTSUPP; - } - - if (!symbols) - return -EINVAL; - - scn = elf_sec_by_idx(obj, obj->efile.maps_shndx); - data = elf_sec_data(obj, scn); - if (!scn || !data) { - pr_warn("elf: failed to get legacy map definitions for %s\n", - obj->path); - return -EINVAL; - } - - /* - * Count number of maps. Each map has a name. - * Array of maps is not supported: only the first element is - * considered. - * - * TODO: Detect array of map and report error. - */ - nr_syms = symbols->d_size / sizeof(Elf64_Sym); - for (i = 0; i < nr_syms; i++) { - Elf64_Sym *sym = elf_sym_by_idx(obj, i); - - if (sym->st_shndx != obj->efile.maps_shndx) - continue; - if (ELF64_ST_TYPE(sym->st_info) == STT_SECTION) - continue; - nr_maps++; - } - /* Assume equally sized map definitions */ - pr_debug("elf: found %d legacy map definitions (%zd bytes) in %s\n", - nr_maps, data->d_size, obj->path); - - if (!data->d_size || nr_maps == 0 || (data->d_size % nr_maps) != 0) { - pr_warn("elf: unable to determine legacy map definition size in %s\n", - obj->path); - return -EINVAL; - } - map_def_sz = data->d_size / nr_maps; - - /* Fill obj->maps using data in "maps" section. */ - for (i = 0; i < nr_syms; i++) { - Elf64_Sym *sym = elf_sym_by_idx(obj, i); - const char *map_name; - struct bpf_map_def *def; - struct bpf_map *map; - - if (sym->st_shndx != obj->efile.maps_shndx) - continue; - if (ELF64_ST_TYPE(sym->st_info) == STT_SECTION) - continue; - - map = bpf_object__add_map(obj); - if (IS_ERR(map)) - return PTR_ERR(map); - - map_name = elf_sym_str(obj, sym->st_name); - if (!map_name) { - pr_warn("failed to get map #%d name sym string for obj %s\n", - i, obj->path); - return -LIBBPF_ERRNO__FORMAT; - } - - pr_warn("map '%s' (legacy): legacy map definitions are deprecated, use BTF-defined maps instead\n", map_name); - - if (ELF64_ST_BIND(sym->st_info) == STB_LOCAL) { - pr_warn("map '%s' (legacy): static maps are not supported\n", map_name); - return -ENOTSUP; - } - - map->libbpf_type = LIBBPF_MAP_UNSPEC; - map->sec_idx = sym->st_shndx; - map->sec_offset = sym->st_value; - pr_debug("map '%s' (legacy): at sec_idx %d, offset %zu.\n", - map_name, map->sec_idx, map->sec_offset); - if (sym->st_value + map_def_sz > data->d_size) { - pr_warn("corrupted maps section in %s: last map \"%s\" too small\n", - obj->path, map_name); - return -EINVAL; - } - - map->name = strdup(map_name); - if (!map->name) { - pr_warn("map '%s': failed to alloc map name\n", map_name); - return -ENOMEM; - } - pr_debug("map %d is \"%s\"\n", i, map->name); - def = (struct bpf_map_def *)(data->d_buf + sym->st_value); - /* - * If the definition of the map in the object file fits in - * bpf_map_def, copy it. Any extra fields in our version - * of bpf_map_def will default to zero as a result of the - * calloc above. - */ - if (map_def_sz <= sizeof(struct bpf_map_def)) { - memcpy(&map->def, def, map_def_sz); - } else { - /* - * Here the map structure being read is bigger than what - * we expect, truncate if the excess bits are all zero. - * If they are not zero, reject this map as - * incompatible. - */ - char *b; - - for (b = ((char *)def) + sizeof(struct bpf_map_def); - b < ((char *)def) + map_def_sz; b++) { - if (*b != 0) { - pr_warn("maps section in %s: \"%s\" has unrecognized, non-zero options\n", - obj->path, map_name); - if (strict) - return -EINVAL; - } - } - memcpy(&map->def, def, sizeof(struct bpf_map_def)); - } - - /* btf info may not exist but fill it in if it does exist */ - (void) bpf_map_find_btf_info(obj, map); - } - return 0; -} - const struct btf_type * skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id) { @@ -2700,12 +2530,11 @@ static int bpf_object__init_maps(struct bpf_object *obj, { const char *pin_root_path; bool strict; - int err; + int err = 0; strict = !OPTS_GET(opts, relaxed_maps, false); pin_root_path = OPTS_GET(opts, pin_root_path, NULL); - err = bpf_object__init_user_maps(obj, strict); err = err ?: bpf_object__init_user_btf_maps(obj, strict, pin_root_path); err = err ?: bpf_object__init_global_data_maps(obj); err = err ?: bpf_object__init_kconfig_map(obj); @@ -3979,28 +3808,8 @@ static int bpf_object__collect_externs(struct bpf_object *obj) return 0; } -static bool prog_is_subprog(const struct bpf_object *obj, - const struct bpf_program *prog) -{ - /* For legacy reasons, libbpf supports an entry-point BPF programs - * without SEC() attribute, i.e., those in the .text section. But if - * there are 2 or more such programs in the .text section, they all - * must be subprograms called from entry-point BPF programs in - * designated SEC()'tions, otherwise there is no way to distinguish - * which of those programs should be loaded vs which are a subprogram. - * Similarly, if there is a function/program in .text and at least one - * other BPF program with custom SEC() attribute, then we just assume - * .text programs are subprograms (even if they are not called from - * other programs), because libbpf never explicitly supported mixing - * SEC()-designated BPF programs and .text entry-point BPF programs. - * - * In libbpf 1.0 strict mode, we always consider .text - * programs to be subprograms. - */ - - if (libbpf_mode & LIBBPF_STRICT_SEC_NAME) - return prog->sec_idx == obj->efile.text_shndx; - +static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog) +{ return prog->sec_idx == obj->efile.text_shndx && obj->nr_programs > 1; } @@ -8163,8 +7972,7 @@ int bpf_object__pin_programs(struct bpf_object *obj, const char *path) char buf[PATH_MAX]; int len; - len = snprintf(buf, PATH_MAX, "%s/%s", path, - prog->pin_name); + len = snprintf(buf, PATH_MAX, "%s/%s", path, prog->name); if (len < 0) { err = -EINVAL; goto err_unpin_programs; @@ -8185,8 +7993,7 @@ err_unpin_programs: char buf[PATH_MAX]; int len; - len = snprintf(buf, PATH_MAX, "%s/%s", path, - prog->pin_name); + len = snprintf(buf, PATH_MAX, "%s/%s", path, prog->name); if (len < 0) continue; else if (len >= PATH_MAX) @@ -8210,8 +8017,7 @@ int bpf_object__unpin_programs(struct bpf_object *obj, const char *path) char buf[PATH_MAX]; int len; - len = snprintf(buf, PATH_MAX, "%s/%s", path, - prog->pin_name); + len = snprintf(buf, PATH_MAX, "%s/%s", path, prog->name); if (len < 0) return libbpf_err(-EINVAL); else if (len >= PATH_MAX) diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 5eb3145b8945..e4d5353f757b 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -886,40 +886,6 @@ LIBBPF_API int bpf_map__lookup_and_delete_elem(const struct bpf_map *map, LIBBPF_API int bpf_map__get_next_key(const struct bpf_map *map, const void *cur_key, void *next_key, size_t key_sz); -/** - * @brief **libbpf_get_error()** extracts the error code from the passed - * pointer - * @param ptr pointer returned from libbpf API function - * @return error code; or 0 if no error occured - * - * Many libbpf API functions which return pointers have logic to encode error - * codes as pointers, and do not return NULL. Meaning **libbpf_get_error()** - * should be used on the return value from these functions immediately after - * calling the API function, with no intervening calls that could clobber the - * `errno` variable. Consult the individual functions documentation to verify - * if this logic applies should be used. - * - * For these API functions, if `libbpf_set_strict_mode(LIBBPF_STRICT_CLEAN_PTRS)` - * is enabled, NULL is returned on error instead. - * - * If ptr is NULL, then errno should be already set by the failing - * API, because libbpf never returns NULL on success and it now always - * sets errno on error. - * - * Example usage: - * - * struct perf_buffer *pb; - * - * pb = perf_buffer__new(bpf_map__fd(obj->maps.events), PERF_BUFFER_PAGES, &opts); - * err = libbpf_get_error(pb); - * if (err) { - * pb = NULL; - * fprintf(stderr, "failed to open perf buffer: %d\n", err); - * goto cleanup; - * } - */ -LIBBPF_API long libbpf_get_error(const void *ptr); - struct bpf_xdp_set_link_opts { size_t sz; int old_fd; diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index a1ad145ffa74..9cd7829cbe41 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -15,7 +15,6 @@ #include <linux/err.h> #include <fcntl.h> #include <unistd.h> -#include "libbpf_legacy.h" #include "relo_core.h" /* make sure libbpf doesn't use kernel-only integer typedefs */ @@ -478,8 +477,6 @@ int btf_ext_visit_str_offs(struct btf_ext *btf_ext, str_off_visit_fn visit, void __s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type_name, __u32 kind); -extern enum libbpf_strict_mode libbpf_mode; - typedef int (*kallsyms_cb_t)(unsigned long long sym_addr, char sym_type, const char *sym_name, void *ctx); @@ -498,12 +495,8 @@ static inline int libbpf_err(int ret) */ static inline int libbpf_err_errno(int ret) { - if (libbpf_mode & LIBBPF_STRICT_DIRECT_ERRS) - /* errno is already assumed to be set on error */ - return ret < 0 ? -errno : ret; - - /* legacy: on error return -1 directly and don't touch errno */ - return ret; + /* errno is already assumed to be set on error */ + return ret < 0 ? -errno : ret; } /* handle error for pointer-returning APIs, err is assumed to be < 0 always */ @@ -511,12 +504,7 @@ static inline void *libbpf_err_ptr(int err) { /* set errno on error, this doesn't break anything */ errno = -err; - - if (libbpf_mode & LIBBPF_STRICT_CLEAN_PTRS) - return NULL; - - /* legacy: encode err as ptr */ - return ERR_PTR(err); + return NULL; } /* handle pointer-returning APIs' error handling */ @@ -526,11 +514,7 @@ static inline void *libbpf_ptr(void *ret) if (IS_ERR(ret)) errno = -PTR_ERR(ret); - if (libbpf_mode & LIBBPF_STRICT_CLEAN_PTRS) - return IS_ERR(ret) ? NULL : ret; - - /* legacy: pass-through original pointer */ - return ret; + return IS_ERR(ret) ? NULL : ret; } static inline bool str_is_empty(const char *s) diff --git a/tools/lib/bpf/libbpf_legacy.h b/tools/lib/bpf/libbpf_legacy.h index d7bcbd01f66f..863f49df8bf4 100644 --- a/tools/lib/bpf/libbpf_legacy.h +++ b/tools/lib/bpf/libbpf_legacy.h @@ -20,6 +20,11 @@ extern "C" { #endif +/* As of libbpf 1.0 libbpf_set_strict_mode() and enum libbpf_struct_mode have + * no effect. But they are left in libbpf_legacy.h so that applications that + * prepared for libbpf 1.0 before final release by using + * libbpf_set_strict_mode() still work with libbpf 1.0+ without any changes. + */ enum libbpf_strict_mode { /* Turn on all supported strict features of libbpf to simulate libbpf * v1.0 behavior. @@ -88,6 +93,25 @@ enum libbpf_strict_mode { LIBBPF_API int libbpf_set_strict_mode(enum libbpf_strict_mode mode); +/** + * @brief **libbpf_get_error()** extracts the error code from the passed + * pointer + * @param ptr pointer returned from libbpf API function + * @return error code; or 0 if no error occured + * + * Note, as of libbpf 1.0 this function is not necessary and not recommended + * to be used. Libbpf doesn't return error code embedded into the pointer + * itself. Instead, NULL is returned on error and error code is passed through + * thread-local errno variable. **libbpf_get_error()** is just returning -errno + * value if it receives NULL, which is correct only if errno hasn't been + * modified between libbpf API call and corresponding **libbpf_get_error()** + * call. Prefer to check return for NULL and use errno directly. + * + * This API is left in libbpf 1.0 to allow applications that were 1.0-ready + * before final libbpf 1.0 without needing to change them. + */ +LIBBPF_API long libbpf_get_error(const void *ptr); + #define DECLARE_LIBBPF_OPTS LIBBPF_OPTS /* "Discouraged" APIs which don't follow consistent libbpf naming patterns. |