libbpf: Add bpf_link support for BPF_PROG_TYPE_SOCKMAP

Introduce a libbpf API function bpf_program__attach_sockmap()
which allow user to get a bpf_link for their corresponding programs.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240410043532.3737722-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/lib/bpf/libbpf.c

@@ -149,6 +149,7 @@ static const char * const link_type_name[] = {
 	[BPF_LINK_TYPE_TCX]			= "tcx",
 	[BPF_LINK_TYPE_UPROBE_MULTI]		= "uprobe_multi",
 	[BPF_LINK_TYPE_NETKIT]			= "netkit",
+	[BPF_LINK_TYPE_SOCKMAP]			= "sockmap",
 };
 
 static const char * const map_type_name[] = {
@@ -12533,6 +12534,12 @@ bpf_program__attach_netns(const struct bpf_program *prog, int netns_fd)
 	return bpf_program_attach_fd(prog, netns_fd, "netns", NULL);
 }
 
+struct bpf_link *
+bpf_program__attach_sockmap(const struct bpf_program *prog, int map_fd)
+{
+	return bpf_program_attach_fd(prog, map_fd, "sockmap", NULL);
+}
+
 struct bpf_link *bpf_program__attach_xdp(const struct bpf_program *prog, int ifindex)
 {
 	/* target_fd/target_ifindex use the same field in LINK_CREATE */

tools/lib/bpf/libbpf.h

@@ -795,6 +795,8 @@ bpf_program__attach_cgroup(const struct bpf_program *prog, int cgroup_fd);
 LIBBPF_API struct bpf_link *
 bpf_program__attach_netns(const struct bpf_program *prog, int netns_fd);
 LIBBPF_API struct bpf_link *
+bpf_program__attach_sockmap(const struct bpf_program *prog, int map_fd);
+LIBBPF_API struct bpf_link *
 bpf_program__attach_xdp(const struct bpf_program *prog, int ifindex);
 LIBBPF_API struct bpf_link *
 bpf_program__attach_freplace(const struct bpf_program *prog,

tools/lib/bpf/libbpf.map

@@ -419,6 +419,7 @@ LIBBPF_1.4.0 {
 
 LIBBPF_1.5.0 {
 	global:
+		bpf_program__attach_sockmap;
 		ring__consume_n;
 		ring_buffer__consume_n;
 } LIBBPF_1.4.0;