bpf: Create fentry/fexit/fmod_ret links through BPF_LINK_CREATE

Make fentry/fexit/fmod_ret as valid attach-types for BPF_LINK_CREATE.
Pass a cookie along with BPF_LINK_CREATE requests.

Signed-off-by: Kui-Feng Lee <[email protected]>

Author: Kui-Feng Lee

include/uapi/linux/bpf.h

@@ -1490,6 +1490,13 @@ union bpf_attr {
 				__aligned_u64	addrs;
 				__aligned_u64	cookies;
 			} kprobe_multi;
+			struct {
+				/* black box user-provided value passed through
+				 * to BPF program at the execution time and
+				 * accessible through bpf_get_attach_cookie() BPF helper
+				 */
+				__u64		cookie;
+			} tracing;
 		};
 	} link_create;
 

kernel/bpf/syscall.c

@@ -3189,6 +3189,10 @@ attach_type_to_prog_type(enum bpf_attach_type attach_type)
 		return BPF_PROG_TYPE_SK_LOOKUP;
 	case BPF_XDP:
 		return BPF_PROG_TYPE_XDP;
+	case BPF_TRACE_FENTRY:
+	case BPF_TRACE_FEXIT:
+	case BPF_MODIFY_RETURN:
+		return BPF_PROG_TYPE_TRACING;
 	default:
 		return BPF_PROG_TYPE_UNSPEC;
 	}
@@ -4254,6 +4258,11 @@ static int tracing_bpf_link_attach(const union bpf_attr *attr, bpfptr_t uattr,
 					       attr->link_create.target_fd,
 					       attr->link_create.target_btf_id,
 					       0);
+	else if (prog->type == BPF_PROG_TYPE_TRACING)
+		return bpf_tracing_prog_attach(prog,
+					       0,
+					       0,
+					       attr->link_create.tracing.cookie);
 
 	return -EINVAL;
 }

tools/include/uapi/linux/bpf.h

@@ -1490,6 +1490,13 @@ union bpf_attr {
 				__aligned_u64	addrs;
 				__aligned_u64	cookies;
 			} kprobe_multi;
+			struct {
+				/* black box user-provided value passed through
+				 * to BPF program at the execution time and
+				 * accessible through bpf_get_attach_cookie() BPF helper
+				 */
+				__u64		cookie;
+			} tracing;
 		};
 	} link_create;