libbpf: Support link-based cgroup attach with options

Currently libbpf supports bpf_program__attach_cgroup() with signature:
  LIBBPF_API struct bpf_link *
  bpf_program__attach_cgroup(const struct bpf_program *prog, int cgroup_fd);

To support mprog style attachment, additionsl fields like flags,
relative_{fd,id} and expected_revision are needed.

Add a new API:
  LIBBPF_API struct bpf_link *
  bpf_program__attach_cgroup_opts(const struct bpf_program *prog, int cgroup_fd,
                                  const struct bpf_cgroup_opts *opts);
where bpf_cgroup_opts contains all above needed fields.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250606163146.2429212-1-yonghong.song@linux.dev

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index a9c3e33d0f8a9bf5c5fe9f9eea22b364ee0c9469..6eb421ccf91bde378c7cd44b454ffab5051bc562 100644 (file)
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -837,6 +837,50 @@ int bpf_link_create(int prog_fd, int target_fd,
                if (!OPTS_ZEROED(opts, netkit))
                        return libbpf_err(-EINVAL);
                break;
+       case BPF_CGROUP_INET_INGRESS:
+       case BPF_CGROUP_INET_EGRESS:
+       case BPF_CGROUP_INET_SOCK_CREATE:
+       case BPF_CGROUP_INET_SOCK_RELEASE:
+       case BPF_CGROUP_INET4_BIND:
+       case BPF_CGROUP_INET6_BIND:
+       case BPF_CGROUP_INET4_POST_BIND:
+       case BPF_CGROUP_INET6_POST_BIND:
+       case BPF_CGROUP_INET4_CONNECT:
+       case BPF_CGROUP_INET6_CONNECT:
+       case BPF_CGROUP_UNIX_CONNECT:
+       case BPF_CGROUP_INET4_GETPEERNAME:
+       case BPF_CGROUP_INET6_GETPEERNAME:
+       case BPF_CGROUP_UNIX_GETPEERNAME:
+       case BPF_CGROUP_INET4_GETSOCKNAME:
+       case BPF_CGROUP_INET6_GETSOCKNAME:
+       case BPF_CGROUP_UNIX_GETSOCKNAME:
+       case BPF_CGROUP_UDP4_SENDMSG:
+       case BPF_CGROUP_UDP6_SENDMSG:
+       case BPF_CGROUP_UNIX_SENDMSG:
+       case BPF_CGROUP_UDP4_RECVMSG:
+       case BPF_CGROUP_UDP6_RECVMSG:
+       case BPF_CGROUP_UNIX_RECVMSG:
+       case BPF_CGROUP_SOCK_OPS:
+       case BPF_CGROUP_DEVICE:
+       case BPF_CGROUP_SYSCTL:
+       case BPF_CGROUP_GETSOCKOPT:
+       case BPF_CGROUP_SETSOCKOPT:
+       case BPF_LSM_CGROUP:
+               relative_fd = OPTS_GET(opts, cgroup.relative_fd, 0);
+               relative_id = OPTS_GET(opts, cgroup.relative_id, 0);
+               if (relative_fd && relative_id)
+                       return libbpf_err(-EINVAL);
+               if (relative_id) {
+                       attr.link_create.cgroup.relative_id = relative_id;
+                       attr.link_create.flags |= BPF_F_ID;
+               } else {
+                       attr.link_create.cgroup.relative_fd = relative_fd;
+               }
+               attr.link_create.cgroup.expected_revision =
+                       OPTS_GET(opts, cgroup.expected_revision, 0);
+               if (!OPTS_ZEROED(opts, cgroup))
+                       return libbpf_err(-EINVAL);
+               break;
        default:
                if (!OPTS_ZEROED(opts, flags))
                        return libbpf_err(-EINVAL);

diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 777627d33d2571acbb0883180852ea59b1bda77d..1342564214c8b57c1f417ae07e02f382975936ca 100644 (file)
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -438,6 +438,11 @@ struct bpf_link_create_opts {
                        __u32 relative_id;
                        __u64 expected_revision;
                } netkit;
+               struct {
+                       __u32 relative_fd;
+                       __u32 relative_id;
+                       __u64 expected_revision;
+               } cgroup;
        };
        size_t :0;
 };

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e9c641a2fb203cf336c95b390574c6f2753d5943..6445165a24f239df34794a781a202886a42c7ad7 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -12837,6 +12837,34 @@ struct bpf_link *bpf_program__attach_xdp(const struct bpf_program *prog, int ifi
        return bpf_program_attach_fd(prog, ifindex, "xdp", NULL);
 }
 
+struct bpf_link *
+bpf_program__attach_cgroup_opts(const struct bpf_program *prog, int cgroup_fd,
+                               const struct bpf_cgroup_opts *opts)
+{
+       LIBBPF_OPTS(bpf_link_create_opts, link_create_opts);
+       __u32 relative_id;
+       int relative_fd;
+
+       if (!OPTS_VALID(opts, bpf_cgroup_opts))
+               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("prog '%s': relative_fd and relative_id cannot be set at the same time\n",
+                       prog->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);
+
+       return bpf_program_attach_fd(prog, cgroup_fd, "cgroup", &link_create_opts);
+}
+
 struct bpf_link *
 bpf_program__attach_tcx(const struct bpf_program *prog, int ifindex,
                        const struct bpf_tcx_opts *opts)

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 1137e7d2e1b5a0ed8d2b94cd00e91bc6abae08b3..d1cf813a057bc7db6912b9039c55e2c94b7b0dba 100644 (file)
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -877,6 +877,21 @@ LIBBPF_API struct bpf_link *
 bpf_program__attach_netkit(const struct bpf_program *prog, int ifindex,
                           const struct bpf_netkit_opts *opts);
 
+struct bpf_cgroup_opts {
+       /* size of this struct, for forward/backward compatibility */
+       size_t sz;
+       __u32 flags;
+       __u32 relative_fd;
+       __u32 relative_id;
+       __u64 expected_revision;
+       size_t :0;
+};
+#define bpf_cgroup_opts__last_field expected_revision
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_cgroup_opts(const struct bpf_program *prog, int cgroup_fd,
+                               const struct bpf_cgroup_opts *opts);
+
 struct bpf_map;
 
 LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map);

diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 1205f9a4fe0486c80462a354f5af96e2f6f74a81..c7fc0bde56486554ff8b4fd2fa002271c76b2cd2 100644 (file)
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -437,6 +437,7 @@ LIBBPF_1.6.0 {
                bpf_linker__add_fd;
                bpf_linker__new_fd;
                bpf_object__prepare;
+               bpf_program__attach_cgroup_opts;
                bpf_program__func_info;
                bpf_program__func_info_cnt;
                bpf_program__line_info;