libbpf: Add support for BPF tc link

[ Commit msg tbd ]

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/include/uapi/linux/bpf.h

@@ -999,6 +999,8 @@ enum bpf_attach_type {
 	BPF_PERF_EVENT,
 	BPF_TRACE_KPROBE_MULTI,
 	BPF_LSM_CGROUP,
+	BPF_NET_INGRESS,
+	BPF_NET_EGRESS,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -1015,6 +1017,7 @@ enum bpf_link_type {
 	BPF_LINK_TYPE_PERF_EVENT = 7,
 	BPF_LINK_TYPE_KPROBE_MULTI = 8,
 	BPF_LINK_TYPE_STRUCT_OPS = 9,
+	BPF_LINK_TYPE_TC = 10,
 
 	MAX_BPF_LINK_TYPE,
 };
@@ -1373,14 +1376,20 @@ union bpf_attr {
 	};
 
 	struct { /* anonymous struct used by BPF_PROG_ATTACH/DETACH commands */
-		__u32		target_fd;	/* container object to attach to */
+		union {
+			__u32	target_fd;	/* container object to attach to */
+			__u32	target_ifindex; /* target ifindex */
+		};
 		__u32		attach_bpf_fd;	/* eBPF program to attach */
 		__u32		attach_type;
 		__u32		attach_flags;
-		__u32		replace_bpf_fd;	/* previously attached eBPF
+		union {
+			__u32	attach_priority;
+			__u32	replace_bpf_fd;	/* previously attached eBPF
 						 * program to replace if
 						 * BPF_F_REPLACE is used
 						 */
+		};
 	};
 
 	struct { /* anonymous struct used by BPF_PROG_TEST_RUN command */
@@ -1426,7 +1435,10 @@ union bpf_attr {
 	} info;
 
 	struct { /* anonymous struct used by BPF_PROG_QUERY command */
-		__u32		target_fd;	/* container object to query */
+		union {
+			__u32	target_fd;	/* container object to query */
+			__u32	target_ifindex; /* target ifindex */
+		};
 		__u32		attach_type;
 		__u32		query_flags;
 		__u32		attach_flags;
@@ -1501,6 +1513,9 @@ union bpf_attr {
 				 */
 				__u64		cookie;
 			} tracing;
+			struct {
+				__u32		priority;
+			} tc;
 		};
 	} link_create;
 
@@ -6147,6 +6162,11 @@ struct bpf_link_info {
 		struct {
 			__u32 ifindex;
 		} xdp;
+		struct {
+			__u32 ifindex;
+			__u32 attach_type;
+			__u32 priority;
+		} tc;
 	};
 } __attribute__((aligned(8)));
 

tools/lib/bpf/bpf.c

@@ -741,6 +741,10 @@ int bpf_link_create(int prog_fd, int target_fd,
 		if (!OPTS_ZEROED(opts, tracing))
 			return libbpf_err(-EINVAL);
 		break;
+	case BPF_NET_INGRESS:
+	case BPF_NET_EGRESS:
+		attr.link_create.tc.priority = OPTS_GET(opts, tc.priority, 0);
+		break;
 	default:
 		if (!OPTS_ZEROED(opts, flags))
 			return libbpf_err(-EINVAL);

tools/lib/bpf/bpf.h

@@ -334,6 +334,9 @@ struct bpf_link_create_opts {
 		struct {
 			__u64 cookie;
 		} tracing;
+		struct {
+			__u32 priority;
+		} tc;
 	};
 	size_t :0;
 };

tools/lib/bpf/libbpf.c

@@ -8458,6 +8458,8 @@ static const struct bpf_sec_def section_defs[] = {
 	SEC_DEF("kretsyscall+",		KPROBE, 0, SEC_NONE, attach_ksyscall),
 	SEC_DEF("usdt+",		KPROBE,	0, SEC_NONE, attach_usdt),
 	SEC_DEF("tc",			SCHED_CLS, 0, SEC_NONE),
+	SEC_DEF("tc/ingress",		SCHED_CLS, BPF_NET_INGRESS, SEC_ATTACHABLE_OPT),
+	SEC_DEF("tc/egress",		SCHED_CLS, BPF_NET_EGRESS, SEC_ATTACHABLE_OPT),
 	SEC_DEF("classifier",		SCHED_CLS, 0, SEC_NONE),
 	SEC_DEF("action",		SCHED_ACT, 0, SEC_NONE),
 	SEC_DEF("tracepoint+",		TRACEPOINT, 0, SEC_NONE, attach_tp),
@@ -11205,11 +11207,10 @@ 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;
@@ -11227,7 +11228,7 @@ 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);
@@ -11240,6 +11241,16 @@ 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)
 {
@@ -11258,6 +11269,16 @@ 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_tc(const struct bpf_program *prog,
+					int ifindex, __u32 priority)
+{
+	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts,
+			    .tc.priority = priority);
+
+	/* 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_freplace(const struct bpf_program *prog,
 					      int target_fd,
 					      const char *attach_func_name)

tools/lib/bpf/libbpf.h

@@ -641,6 +641,8 @@ 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_tc(const struct bpf_program *prog, int ifindex, __u32 priority);
+LIBBPF_API struct bpf_link *
 bpf_program__attach_freplace(const struct bpf_program *prog,
 			     int target_fd, const char *attach_func_name);
 

tools/lib/bpf/libbpf.map

@@ -346,6 +346,7 @@ LIBBPF_0.8.0 {
 		bpf_object__destroy_subskeleton;
 		bpf_object__open_subskeleton;
 		bpf_program__attach_kprobe_multi_opts;
+		bpf_program__attach_tc;
 		bpf_program__attach_trace_opts;
 		bpf_program__attach_usdt;
 		bpf_program__set_insns;