From dd4436bb838338cfda253d7f012610a73e4078fd Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sun, 20 Oct 2019 20:38:59 -0700 Subject: [PATCH] libbpf: Teach bpf_object__open to guess program types Teach bpf_object__open how to guess program type and expected attach type from section names, similar to what bpf_prog_load() does. This seems like a really useful features and an oversight to not have this done during bpf_object_open(). To preserver backwards compatible behavior of bpf_prog_load(), its attr->prog_type is treated as an override of bpf_object__open() decisions, if attr->prog_type is not UNSPECIFIED. There is a slight difference in behavior for bpf_prog_load(). Previously, if bpf_prog_load() was loading BPF object with more than one program, first program's guessed program type and expected attach type would determine corresponding attributes of all the subsequent program types, even if their sections names suggest otherwise. That seems like a rather dubious behavior and with this change it will behave more sanely: each program's type is determined individually, unless they are forced to uniformity through attr->prog_type. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20191021033902.3856966-5-andriin@fb.com --- tools/lib/bpf/libbpf.c | 65 +++++++++++++++++++++++------------------- 1 file changed, 36 insertions(+), 29 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index a027fbf89966..803219d6898c 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -3611,6 +3611,7 @@ static struct bpf_object * __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, struct bpf_object_open_opts *opts) { + struct bpf_program *prog; struct bpf_object *obj; const char *obj_name; char tmp_name[64]; @@ -3650,8 +3651,24 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, CHECK_ERR(bpf_object__probe_caps(obj), err, out); CHECK_ERR(bpf_object__elf_collect(obj, relaxed_maps), err, out); CHECK_ERR(bpf_object__collect_reloc(obj), err, out); - bpf_object__elf_finish(obj); + + bpf_object__for_each_program(prog, obj) { + enum bpf_prog_type prog_type; + enum bpf_attach_type attach_type; + + err = libbpf_prog_type_by_name(prog->section_name, &prog_type, + &attach_type); + if (err == -ESRCH) + /* couldn't guess, but user might manually specify */ + continue; + if (err) + goto out; + + bpf_program__set_type(prog, prog_type); + bpf_program__set_expected_attach_type(prog, attach_type); + } + return obj; out: bpf_object__close(obj); @@ -4691,7 +4708,7 @@ int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type, free(type_names); } - return -EINVAL; + return -ESRCH; } int libbpf_attach_type_by_name(const char *name, @@ -4721,15 +4738,6 @@ int libbpf_attach_type_by_name(const char *name, return -EINVAL; } -static int -bpf_program__identify_section(struct bpf_program *prog, - enum bpf_prog_type *prog_type, - enum bpf_attach_type *expected_attach_type) -{ - return libbpf_prog_type_by_name(prog->section_name, prog_type, - expected_attach_type); -} - int bpf_map__fd(const struct bpf_map *map) { return map ? map->fd : -EINVAL; @@ -4897,8 +4905,6 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr, { struct bpf_object_open_attr open_attr = {}; struct bpf_program *prog, *first_prog = NULL; - enum bpf_attach_type expected_attach_type; - enum bpf_prog_type prog_type; struct bpf_object *obj; struct bpf_map *map; int err; @@ -4916,26 +4922,27 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr, return -ENOENT; bpf_object__for_each_program(prog, obj) { + enum bpf_attach_type attach_type = attr->expected_attach_type; /* - * If type is not specified, try to guess it based on - * section name. + * to preserve backwards compatibility, bpf_prog_load treats + * attr->prog_type, if specified, as an override to whatever + * bpf_object__open guessed */ - prog_type = attr->prog_type; - prog->prog_ifindex = attr->ifindex; - expected_attach_type = attr->expected_attach_type; - if (prog_type == BPF_PROG_TYPE_UNSPEC) { - err = bpf_program__identify_section(prog, &prog_type, - &expected_attach_type); - if (err < 0) { - bpf_object__close(obj); - return -EINVAL; - } + if (attr->prog_type != BPF_PROG_TYPE_UNSPEC) { + bpf_program__set_type(prog, attr->prog_type); + bpf_program__set_expected_attach_type(prog, + attach_type); + } + if (bpf_program__get_type(prog) == BPF_PROG_TYPE_UNSPEC) { + /* + * we haven't guessed from section name and user + * didn't provide a fallback type, too bad... + */ + bpf_object__close(obj); + return -EINVAL; } - bpf_program__set_type(prog, prog_type); - bpf_program__set_expected_attach_type(prog, - expected_attach_type); - + prog->prog_ifindex = attr->ifindex; prog->log_level = attr->log_level; prog->prog_flags = attr->prog_flags; if (!first_prog)