libbpf: Add support for bpf_link-based cgroup attachment

Add bpf_program__attach_cgroup(), which uses BPF_LINK_CREATE subcommand to
create an FD-based kernel bpf_link. Also add low-level bpf_link_create() API.

If expected_attach_type is not specified explicitly with
bpf_program__set_expected_attach_type(), libbpf will try to determine proper
attach type from BPF program's section definition.

Also add support for bpf_link's underlying BPF program replacement:
  - unconditional through high-level bpf_link__update_program() API;
  - cmpxchg-like with specifying expected current BPF program through
    low-level bpf_link_update() API.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200330030001.2312810-4-andriin@fb.com
This commit is contained in:
Andrii Nakryiko
2020-03-29 20:00:00 -07:00
committed by Alexei Starovoitov
parent 0c991ebc8c
commit cc4f864bb1
6 changed files with 122 additions and 1 deletions

View File

@@ -224,6 +224,8 @@ LIBBPF_API int bpf_link__fd(const struct bpf_link *link);
LIBBPF_API const char *bpf_link__pin_path(const struct bpf_link *link);
LIBBPF_API int bpf_link__pin(struct bpf_link *link, const char *path);
LIBBPF_API int bpf_link__unpin(struct bpf_link *link);
LIBBPF_API int bpf_link__update_program(struct bpf_link *link,
struct bpf_program *prog);
LIBBPF_API void bpf_link__disconnect(struct bpf_link *link);
LIBBPF_API int bpf_link__destroy(struct bpf_link *link);
@@ -245,13 +247,17 @@ bpf_program__attach_tracepoint(struct bpf_program *prog,
LIBBPF_API struct bpf_link *
bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
const char *tp_name);
LIBBPF_API struct bpf_link *
bpf_program__attach_trace(struct bpf_program *prog);
LIBBPF_API struct bpf_link *
bpf_program__attach_lsm(struct bpf_program *prog);
LIBBPF_API struct bpf_link *
bpf_program__attach_cgroup(struct bpf_program *prog, int cgroup_fd);
struct bpf_map;
LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map);
struct bpf_insn;
/*