libbpf: Add support for BPF tc link

Implement tc BPF link support for libbpf. The bpf_program__attach_fd() API has been refactored slightly in order to pass bpf_link_create_opts. A new bpf_program__attach_tcx() has been added on top of this which allows for passing ifindex and other relevant parameters. Co-developed-by: Nikolay Aleksandrov <[email protected]> Signed-off-by: Nikolay Aleksandrov <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]>
cilium · May 17, 2023 · d0b894b · d0b894b
1 parent 947f61c
commit d0b894b
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Showing 5 changed files with 57 additions and 5 deletions.
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
@@ -754,6 +754,10 @@ int bpf_link_create(int prog_fd, int target_fd,
 		if (!OPTS_ZEROED(opts, tracing))
 			return libbpf_err(-EINVAL);
 		break;
+	case BPF_TCX_INGRESS:
+	case BPF_TCX_EGRESS:
+		attr.link_create.tcx.relative_fd = OPTS_GET(opts, tcx.relative_fd, 0);
+		attr.link_create.tcx.expected_revision = OPTS_GET(opts, tcx.expected_revision, 0);
 	default:
 		if (!OPTS_ZEROED(opts, flags))
 			return libbpf_err(-EINVAL);

diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
@@ -356,6 +356,13 @@ struct bpf_link_create_opts {
 		struct {
 			__u64 cookie;
 		} tracing;
+		struct {
+			union {
+				__u32 relative_fd;
+				__u32 relative_id;
+			};
+			__u32 expected_revision;
+		} tcx;
 	};
 	size_t :0;
 };

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
@@ -11566,11 +11566,10 @@ static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_li
 }
 
 static struct bpf_link *
-bpf_program__attach_fd(const struct bpf_program *prog, int target_fd, int btf_id,
-		       const char *target_name)
+bpf_program__attach_fd_opts(const struct bpf_program *prog,
+			    const struct bpf_link_create_opts *opts,
+			    int target_fd, const char *target_name)
 {
-	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts,
-			    .target_btf_id = btf_id);
 	enum bpf_attach_type attach_type;
 	char errmsg[STRERR_BUFSIZE];
 	struct bpf_link *link;
@@ -11588,7 +11587,7 @@ bpf_program__attach_fd(const struct bpf_program *prog, int target_fd, int btf_id
 	link->detach = &bpf_link__detach_fd;
 
 	attach_type = bpf_program__expected_attach_type(prog);
-	link_fd = bpf_link_create(prog_fd, target_fd, attach_type, &opts);
+	link_fd = bpf_link_create(prog_fd, target_fd, attach_type, opts);
 	if (link_fd < 0) {
 		link_fd = -errno;
 		free(link);
@@ -11601,6 +11600,16 @@ bpf_program__attach_fd(const struct bpf_program *prog, int target_fd, int btf_id
 	return link;
 }
 
+static struct bpf_link *
+bpf_program__attach_fd(const struct bpf_program *prog, int target_fd, int btf_id,
+		       const char *target_name)
+{
+	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts,
+			    .target_btf_id = btf_id);
+
+	return bpf_program__attach_fd_opts(prog, &opts, target_fd, target_name);
+}
+
 struct bpf_link *
 bpf_program__attach_cgroup(const struct bpf_program *prog, int cgroup_fd)
 {
@@ -11619,6 +11628,29 @@ struct bpf_link *bpf_program__attach_xdp(const struct bpf_program *prog, int ifi
 	return bpf_program__attach_fd(prog, ifindex, 0, "xdp");
 }
 
+struct bpf_link *
+bpf_program__attach_tcx_revision(const struct bpf_program *prog, int ifindex,
+				 __u32 flags, __u32 relative_object,
+				 __u32 expected_revision)
+{
+	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts,
+		.tcx.expected_revision = expected_revision,
+		.tcx.relative_fd = relative_object,
+		.flags = flags,
+	);
+
+	/* target_fd/target_ifindex use the same field in LINK_CREATE */
+	return bpf_program__attach_fd_opts(prog, &opts, ifindex, "tc");
+}
+
+struct bpf_link *
+bpf_program__attach_tcx(const struct bpf_program *prog, int ifindex,
+			__u32 flags, __u32 relative_object)
+{
+	return bpf_program__attach_tcx_revision(prog, ifindex, flags,
+						relative_object, 0);
+}
+
 struct bpf_link *bpf_program__attach_freplace(const struct bpf_program *prog,
 					      int target_fd,
 					      const char *attach_func_name)

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
@@ -715,6 +715,13 @@ bpf_program__attach_netns(const struct bpf_program *prog, int netns_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_tcx(const struct bpf_program *prog, int ifindex,
+			__u32 flags, __u32 relative_object);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_tcx_revision(const struct bpf_program *prog, int ifindex,
+				 __u32 flags, __u32 relative_object,
+				 __u32 expected_revision);
+LIBBPF_API struct bpf_link *
 bpf_program__attach_freplace(const struct bpf_program *prog,
 			     int target_fd, const char *attach_func_name);
 

diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
@@ -395,4 +395,6 @@ LIBBPF_1.2.0 {
 LIBBPF_1.3.0 {
 	global:
 		bpf_prog_detach_opts;
+		bpf_program__attach_tcx;
+		bpf_program__attach_tcx_revision;
 } LIBBPF_1.2.0;