libbpf: Add support for program extensions
Add minimal support for program extensions. bpf_object_open_opts() needs to be called with attach_prog_fd = target_prog_fd and BPF program extension needs to have in .c file section definition like SEC("freplace/func_to_be_replaced"). libbpf will search for "func_to_be_replaced" in the target_prog_fd's BTF and will pass it in attach_btf_id to the kernel. This approach works for tests, but more compex use case may need to request function name (and attach_btf_id that kernel sees) to be more dynamic. Such API will be added in future patches. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20200121005348.2769920-3-ast@kernel.org
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@ -180,6 +180,7 @@ enum bpf_prog_type {
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BPF_PROG_TYPE_CGROUP_SOCKOPT,
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BPF_PROG_TYPE_TRACING,
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BPF_PROG_TYPE_STRUCT_OPS,
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BPF_PROG_TYPE_EXT,
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};
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enum bpf_attach_type {
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@ -237,7 +237,8 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
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attr.expected_attach_type = load_attr->expected_attach_type;
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if (attr.prog_type == BPF_PROG_TYPE_STRUCT_OPS) {
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attr.attach_btf_id = load_attr->attach_btf_id;
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} else if (attr.prog_type == BPF_PROG_TYPE_TRACING) {
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} else if (attr.prog_type == BPF_PROG_TYPE_TRACING ||
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attr.prog_type == BPF_PROG_TYPE_EXT) {
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attr.attach_btf_id = load_attr->attach_btf_id;
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attr.attach_prog_fd = load_attr->attach_prog_fd;
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} else {
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@ -4837,7 +4837,8 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
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load_attr.license = license;
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if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) {
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load_attr.attach_btf_id = prog->attach_btf_id;
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} else if (prog->type == BPF_PROG_TYPE_TRACING) {
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} else if (prog->type == BPF_PROG_TYPE_TRACING ||
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prog->type == BPF_PROG_TYPE_EXT) {
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load_attr.attach_prog_fd = prog->attach_prog_fd;
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load_attr.attach_btf_id = prog->attach_btf_id;
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} else {
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@ -4918,7 +4919,8 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
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{
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int err = 0, fd, i, btf_id;
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if (prog->type == BPF_PROG_TYPE_TRACING) {
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if (prog->type == BPF_PROG_TYPE_TRACING ||
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prog->type == BPF_PROG_TYPE_EXT) {
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btf_id = libbpf_find_attach_btf_id(prog);
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if (btf_id <= 0)
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return btf_id;
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@ -5092,7 +5094,8 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
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bpf_program__set_type(prog, prog_type);
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bpf_program__set_expected_attach_type(prog, attach_type);
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if (prog_type == BPF_PROG_TYPE_TRACING)
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if (prog_type == BPF_PROG_TYPE_TRACING ||
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prog_type == BPF_PROG_TYPE_EXT)
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prog->attach_prog_fd = OPTS_GET(opts, attach_prog_fd, 0);
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}
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@ -6166,6 +6169,7 @@ BPF_PROG_TYPE_FNS(xdp, BPF_PROG_TYPE_XDP);
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BPF_PROG_TYPE_FNS(perf_event, BPF_PROG_TYPE_PERF_EVENT);
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BPF_PROG_TYPE_FNS(tracing, BPF_PROG_TYPE_TRACING);
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BPF_PROG_TYPE_FNS(struct_ops, BPF_PROG_TYPE_STRUCT_OPS);
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BPF_PROG_TYPE_FNS(extension, BPF_PROG_TYPE_EXT);
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enum bpf_attach_type
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bpf_program__get_expected_attach_type(struct bpf_program *prog)
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@ -6265,6 +6269,9 @@ static const struct bpf_sec_def section_defs[] = {
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.expected_attach_type = BPF_TRACE_FEXIT,
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.is_attach_btf = true,
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.attach_fn = attach_trace),
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SEC_DEF("freplace/", EXT,
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.is_attach_btf = true,
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.attach_fn = attach_trace),
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BPF_PROG_SEC("xdp", BPF_PROG_TYPE_XDP),
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BPF_PROG_SEC("perf_event", BPF_PROG_TYPE_PERF_EVENT),
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BPF_PROG_SEC("lwt_in", BPF_PROG_TYPE_LWT_IN),
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@ -318,6 +318,7 @@ LIBBPF_API int bpf_program__set_xdp(struct bpf_program *prog);
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LIBBPF_API int bpf_program__set_perf_event(struct bpf_program *prog);
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LIBBPF_API int bpf_program__set_tracing(struct bpf_program *prog);
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LIBBPF_API int bpf_program__set_struct_ops(struct bpf_program *prog);
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LIBBPF_API int bpf_program__set_extension(struct bpf_program *prog);
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LIBBPF_API enum bpf_prog_type bpf_program__get_type(struct bpf_program *prog);
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LIBBPF_API void bpf_program__set_type(struct bpf_program *prog,
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@ -339,6 +340,7 @@ LIBBPF_API bool bpf_program__is_xdp(const struct bpf_program *prog);
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LIBBPF_API bool bpf_program__is_perf_event(const struct bpf_program *prog);
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LIBBPF_API bool bpf_program__is_tracing(const struct bpf_program *prog);
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LIBBPF_API bool bpf_program__is_struct_ops(const struct bpf_program *prog);
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LIBBPF_API bool bpf_program__is_extension(const struct bpf_program *prog);
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/*
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* No need for __attribute__((packed)), all members of 'bpf_map_def'
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@ -228,7 +228,9 @@ LIBBPF_0.0.7 {
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bpf_prog_attach_xattr;
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bpf_program__attach;
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bpf_program__name;
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bpf_program__is_extension;
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bpf_program__is_struct_ops;
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bpf_program__set_extension;
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bpf_program__set_struct_ops;
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btf__align_of;
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libbpf_find_kernel_btf;
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@ -107,6 +107,7 @@ probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
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case BPF_PROG_TYPE_CGROUP_SOCKOPT:
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case BPF_PROG_TYPE_TRACING:
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case BPF_PROG_TYPE_STRUCT_OPS:
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case BPF_PROG_TYPE_EXT:
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default:
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break;
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}
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