[PATCH bpf-next v2 13/15] libbpf: Support attaching struct_ops to a cgroup
From: Amery Hung <hidden>
Date: 2026-06-23 17:50:28
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [library] (libbpf), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
From: Martin KaFai Lau <martin.lau@kernel.org> Add bpf_map__attach_cgroup_opts() to attach a struct_ops map to a cgroup through a BPF link. Also extend struct bpf_prog_query_opts with a type_id field so a BPF_STRUCT_OPS query on a cgroup can select the struct_ops type to enumerate. Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Signed-off-by: Amery Hung <redacted> --- tools/lib/bpf/bpf.c | 2 ++ tools/lib/bpf/bpf.h | 3 +- tools/lib/bpf/libbpf.c | 59 ++++++++++++++++++++++++++++++++++ tools/lib/bpf/libbpf.h | 3 ++ tools/lib/bpf/libbpf.map | 5 +++ tools/lib/bpf/libbpf_version.h | 2 +- 6 files changed, 72 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 96819c082c77..a9de7f107cf7 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c@@ -934,6 +934,7 @@ int bpf_link_create(int prog_fd, int target_fd, case BPF_CGROUP_GETSOCKOPT: case BPF_CGROUP_SETSOCKOPT: case BPF_LSM_CGROUP: + case BPF_STRUCT_OPS: relative_fd = OPTS_GET(opts, cgroup.relative_fd, 0); relative_id = OPTS_GET(opts, cgroup.relative_id, 0); if (relative_fd && relative_id)
@@ -1056,6 +1057,7 @@ int bpf_prog_query_opts(int target, enum bpf_attach_type type, attr.query.attach_type = type; attr.query.query_flags = OPTS_GET(opts, query_flags, 0); attr.query.count = OPTS_GET(opts, count, 0); + attr.query.type_id = OPTS_GET(opts, type_id, 0); attr.query.prog_ids = ptr_to_u64(OPTS_GET(opts, prog_ids, NULL)); attr.query.link_ids = ptr_to_u64(OPTS_GET(opts, link_ids, NULL)); attr.query.prog_attach_flags = ptr_to_u64(OPTS_GET(opts, prog_attach_flags, NULL));
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 7534a593edae..490e8cb4ba53 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h@@ -637,9 +637,10 @@ struct bpf_prog_query_opts { __u32 *link_ids; __u32 *link_attach_flags; __u64 revision; + __u32 type_id; size_t :0; }; -#define bpf_prog_query_opts__last_field revision +#define bpf_prog_query_opts__last_field type_id /** * @brief **bpf_prog_query_opts()** queries the BPF programs and BPF links
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 1368752aa13c..17f8466e33fa 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c@@ -14104,6 +14104,65 @@ struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map) return &link->link; } +struct bpf_link *bpf_map__attach_cgroup_opts(const struct bpf_map *map, int cgroup_fd, + const struct bpf_cgroup_opts *opts) +{ + LIBBPF_OPTS(bpf_link_create_opts, link_create_opts); + struct bpf_link_struct_ops *link; + __u32 relative_id, zero = 0; + int err, fd, relative_fd; + + if (!OPTS_VALID(opts, bpf_cgroup_opts)) + return libbpf_err_ptr(-EINVAL); + + if (!bpf_map__is_struct_ops(map)) { + pr_warn("map '%s': can't attach non-struct_ops map\n", map->name); + return libbpf_err_ptr(-EINVAL); + } + + if (map->fd < 0) { + pr_warn("map '%s': can't attach BPF map without FD (was it created?)\n", map->name); + return libbpf_err_ptr(-EINVAL); + } + + relative_id = OPTS_GET(opts, relative_id, 0); + relative_fd = OPTS_GET(opts, relative_fd, 0); + + if (relative_fd && relative_id) { + pr_warn("map '%s': relative_fd and relative_id cannot be set at the same time\n", + map->name); + return libbpf_err_ptr(-EINVAL); + } + + link_create_opts.cgroup.expected_revision = OPTS_GET(opts, expected_revision, 0); + link_create_opts.cgroup.relative_fd = relative_fd; + link_create_opts.cgroup.relative_id = relative_id; + link_create_opts.flags = OPTS_GET(opts, flags, 0); + + link = calloc(1, sizeof(*link)); + if (!link) + return libbpf_err_ptr(-ENOMEM); + + err = bpf_map_update_elem(map->fd, &zero, map->st_ops->kern_vdata, 0); + if (err && err != -EBUSY) { + free(link); + return libbpf_err_ptr(err); + } + + link->link.detach = bpf_link__detach_struct_ops; + + fd = bpf_link_create(map->fd, cgroup_fd, BPF_STRUCT_OPS, &link_create_opts); + if (fd < 0) { + free(link); + return libbpf_err_ptr(fd); + } + + link->link.fd = fd; + link->map_fd = map->fd; + + return &link->link; +} + /* * Swap the back struct_ops of a link with a new struct_ops map. */
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index b965ad571540..0e5f4e9bba41 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h@@ -960,6 +960,9 @@ bpf_program__attach_cgroup_opts(const struct bpf_program *prog, int cgroup_fd, struct bpf_map; LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map); +LIBBPF_API struct bpf_link *bpf_map__attach_cgroup_opts(const struct bpf_map *map, + int cgroup_fd, + const struct bpf_cgroup_opts *opts); LIBBPF_API int bpf_link__update_map(struct bpf_link *link, const struct bpf_map *map); struct bpf_iter_attach_opts {
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index b731df19ae69..1b01d49e58eb 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map@@ -462,3 +462,8 @@ LIBBPF_1.8.0 { bpf_program__clone; btf__new_empty_opts; } LIBBPF_1.7.0; + +LIBBPF_1.9.0 { + global: + bpf_map__attach_cgroup_opts; +} LIBBPF_1.8.0;
diff --git a/tools/lib/bpf/libbpf_version.h b/tools/lib/bpf/libbpf_version.h
index c446c0cd8cf9..57b74ef3618c 100644
--- a/tools/lib/bpf/libbpf_version.h
+++ b/tools/lib/bpf/libbpf_version.h@@ -4,6 +4,6 @@ #define __LIBBPF_VERSION_H #define LIBBPF_MAJOR_VERSION 1 -#define LIBBPF_MINOR_VERSION 8 +#define LIBBPF_MINOR_VERSION 9 #endif /* __LIBBPF_VERSION_H */
--
2.53.0-Meta