From e7bf94dbb882b7d679a6a18e40e4f28076eb249f Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 14 Nov 2019 10:57:18 -0800 Subject: libbpf: Add support for attaching BPF programs to other BPF programs Extend libbpf api to pass attach_prog_fd into bpf_object__open. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20191114185720.1641606-19-ast@kernel.org --- tools/include/uapi/linux/bpf.h | 1 + tools/lib/bpf/bpf.c | 8 +++-- tools/lib/bpf/bpf.h | 5 ++- tools/lib/bpf/libbpf.c | 71 +++++++++++++++++++++++++++++++++++------- tools/lib/bpf/libbpf.h | 3 +- 5 files changed, 71 insertions(+), 17 deletions(-) (limited to 'tools') diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 69c200e6e696..4842a134b202 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -425,6 +425,7 @@ union bpf_attr { __aligned_u64 line_info; /* line info */ __u32 line_info_cnt; /* number of bpf_line_info records */ __u32 attach_btf_id; /* in-kernel BTF type id to attach to */ + __u32 attach_prog_fd; /* 0 to attach to vmlinux */ }; struct { /* anonymous struct used by BPF_OBJ_* commands */ diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index b3e3e99a0f28..98596e15390f 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -228,10 +228,13 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr, memset(&attr, 0, sizeof(attr)); attr.prog_type = load_attr->prog_type; attr.expected_attach_type = load_attr->expected_attach_type; - if (attr.prog_type == BPF_PROG_TYPE_TRACING) + if (attr.prog_type == BPF_PROG_TYPE_TRACING) { attr.attach_btf_id = load_attr->attach_btf_id; - else + attr.attach_prog_fd = load_attr->attach_prog_fd; + } else { attr.prog_ifindex = load_attr->prog_ifindex; + attr.kern_version = load_attr->kern_version; + } attr.insn_cnt = (__u32)load_attr->insns_cnt; attr.insns = ptr_to_u64(load_attr->insns); attr.license = ptr_to_u64(load_attr->license); @@ -245,7 +248,6 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr, attr.log_size = 0; } - attr.kern_version = load_attr->kern_version; attr.prog_btf_fd = load_attr->prog_btf_fd; attr.func_info_rec_size = load_attr->func_info_rec_size; attr.func_info_cnt = load_attr->func_info_cnt; diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h index 1c53bc5b4b3c..3c791fa8e68e 100644 --- a/tools/lib/bpf/bpf.h +++ b/tools/lib/bpf/bpf.h @@ -77,7 +77,10 @@ struct bpf_load_program_attr { const struct bpf_insn *insns; size_t insns_cnt; const char *license; - __u32 kern_version; + union { + __u32 kern_version; + __u32 attach_prog_fd; + }; union { __u32 prog_ifindex; __u32 attach_btf_id; diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 98ee033e021f..7132c6bdec02 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -189,6 +189,7 @@ struct bpf_program { enum bpf_attach_type expected_attach_type; __u32 attach_btf_id; + __u32 attach_prog_fd; void *func_info; __u32 func_info_rec_size; __u32 func_info_cnt; @@ -3683,8 +3684,13 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, load_attr.insns = insns; load_attr.insns_cnt = insns_cnt; load_attr.license = license; - load_attr.kern_version = kern_version; - load_attr.prog_ifindex = prog->prog_ifindex; + if (prog->type == BPF_PROG_TYPE_TRACING) { + load_attr.attach_prog_fd = prog->attach_prog_fd; + load_attr.attach_btf_id = prog->attach_btf_id; + } else { + load_attr.kern_version = kern_version; + load_attr.prog_ifindex = prog->prog_ifindex; + } /* if .BTF.ext was loaded, kernel supports associated BTF for prog */ if (prog->obj->btf_ext) btf_fd = bpf_object__btf_fd(prog->obj); @@ -3699,7 +3705,6 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, load_attr.line_info_cnt = prog->line_info_cnt; load_attr.log_level = prog->log_level; load_attr.prog_flags = prog->prog_flags; - load_attr.attach_btf_id = prog->attach_btf_id; retry_load: log_buf = malloc(log_buf_size); @@ -3856,9 +3861,9 @@ bpf_object__load_progs(struct bpf_object *obj, int log_level) return 0; } -static int libbpf_attach_btf_id_by_name(const char *name, - enum bpf_attach_type attach_type); - +static int libbpf_find_attach_btf_id(const char *name, + enum bpf_attach_type attach_type, + __u32 attach_prog_fd); 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) @@ -3869,6 +3874,7 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, const char *obj_name; char tmp_name[64]; bool relaxed_maps; + __u32 attach_prog_fd; int err; if (elf_version(EV_CURRENT) == EV_NONE) { @@ -3899,6 +3905,7 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, obj->relaxed_core_relocs = OPTS_GET(opts, relaxed_core_relocs, false); relaxed_maps = OPTS_GET(opts, relaxed_maps, false); pin_root_path = OPTS_GET(opts, pin_root_path, NULL); + attach_prog_fd = OPTS_GET(opts, attach_prog_fd, 0); CHECK_ERR(bpf_object__elf_init(obj), err, out); CHECK_ERR(bpf_object__check_endianness(obj), err, out); @@ -3923,11 +3930,13 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, bpf_program__set_type(prog, prog_type); bpf_program__set_expected_attach_type(prog, attach_type); if (prog_type == BPF_PROG_TYPE_TRACING) { - err = libbpf_attach_btf_id_by_name(prog->section_name, - attach_type); + err = libbpf_find_attach_btf_id(prog->section_name, + attach_type, + attach_prog_fd); if (err <= 0) goto out; prog->attach_btf_id = err; + prog->attach_prog_fd = attach_prog_fd; } } @@ -5086,8 +5095,42 @@ int libbpf_find_vmlinux_btf_id(const char *name, return err; } -static int libbpf_attach_btf_id_by_name(const char *name, - enum bpf_attach_type attach_type) +static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd) +{ + struct bpf_prog_info_linear *info_linear; + struct bpf_prog_info *info; + struct btf *btf = NULL; + int err = -EINVAL; + + info_linear = bpf_program__get_prog_info_linear(attach_prog_fd, 0); + if (IS_ERR_OR_NULL(info_linear)) { + pr_warn("failed get_prog_info_linear for FD %d\n", + attach_prog_fd); + return -EINVAL; + } + info = &info_linear->info; + if (!info->btf_id) { + pr_warn("The target program doesn't have BTF\n"); + goto out; + } + if (btf__get_from_id(info->btf_id, &btf)) { + pr_warn("Failed to get BTF of the program\n"); + goto out; + } + err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); + btf__free(btf); + if (err <= 0) { + pr_warn("%s is not found in prog's BTF\n", name); + goto out; + } +out: + free(info_linear); + return err; +} + +static int libbpf_find_attach_btf_id(const char *name, + enum bpf_attach_type attach_type, + __u32 attach_prog_fd) { int i, err; @@ -5099,8 +5142,12 @@ static int libbpf_attach_btf_id_by_name(const char *name, continue; if (strncmp(name, section_names[i].sec, section_names[i].len)) continue; - err = libbpf_find_vmlinux_btf_id(name + section_names[i].len, - attach_type); + if (attach_prog_fd) + err = libbpf_find_prog_btf_id(name + section_names[i].len, + attach_prog_fd); + else + err = libbpf_find_vmlinux_btf_id(name + section_names[i].len, + attach_type); if (err <= 0) pr_warn("%s is not found in vmlinux BTF\n", name); return err; diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index fbff419f6daf..0dbf4bfba0c4 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -108,8 +108,9 @@ struct bpf_object_open_opts { * auto-pinned to that path on load; defaults to "/sys/fs/bpf". */ const char *pin_root_path; + __u32 attach_prog_fd; }; -#define bpf_object_open_opts__last_field pin_root_path +#define bpf_object_open_opts__last_field attach_prog_fd LIBBPF_API struct bpf_object *bpf_object__open(const char *path); LIBBPF_API struct bpf_object * -- cgit v1.2.3