1 files changed, 62 insertions, 10 deletions

diff --git a/include/net/scm.h b/include/net/scm.h
index 585adc1346bd..c5bcdf65f55c 100644
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -120,15 +120,49 @@ static inline bool scm_has_secdata(struct socket *sock)
 }
 #endif /* CONFIG_SECURITY_NETWORK */
 
-static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
-				struct scm_cookie *scm, int flags)
+static __inline__ void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm)
+{
+	struct file *pidfd_file = NULL;
+	int pidfd;
+
+	/*
+	 * put_cmsg() doesn't return an error if CMSG is truncated,
+	 * that's why we need to opencode these checks here.
+	 */
+	if ((msg->msg_controllen <= sizeof(struct cmsghdr)) ||
+	    (msg->msg_controllen - sizeof(struct cmsghdr)) < sizeof(int)) {
+		msg->msg_flags |= MSG_CTRUNC;
+		return;
+	}
+
+	if (!scm->pid)
+		return;
+
+	pidfd = pidfd_prepare(scm->pid, 0, &pidfd_file);
+
+	if (put_cmsg(msg, SOL_SOCKET, SCM_PIDFD, sizeof(int), &pidfd)) {
+		if (pidfd_file) {
+			put_unused_fd(pidfd);
+			fput(pidfd_file);
+		}
+
+		return;
+	}
+
+	if (pidfd_file)
+		fd_install(pidfd, pidfd_file);
+}
+
+static inline bool __scm_recv_common(struct socket *sock, struct msghdr *msg,
+				     struct scm_cookie *scm, int flags)
 {
 	if (!msg->msg_control) {
-		if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp ||
-		    scm_has_secdata(sock))
+		if (test_bit(SOCK_PASSCRED, &sock->flags) ||
+		    test_bit(SOCK_PASSPIDFD, &sock->flags) ||
+		    scm->fp || scm_has_secdata(sock))
 			msg->msg_flags |= MSG_CTRUNC;
 		scm_destroy(scm);
-		return;
+		return false;
 	}
 
 	if (test_bit(SOCK_PASSCRED, &sock->flags)) {
@@ -141,16 +175,34 @@ static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
 		put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds);
 	}
 
-	scm_destroy_cred(scm);
-
 	scm_passec(sock, msg, scm);
 
-	if (!scm->fp)
+	if (scm->fp)
+		scm_detach_fds(msg, scm);
+
+	return true;
+}
+
+static inline void scm_recv(struct socket *sock, struct msghdr *msg,
+			    struct scm_cookie *scm, int flags)
+{
+	if (!__scm_recv_common(sock, msg, scm, flags))
 		return;
-	
-	scm_detach_fds(msg, scm);
+
+	scm_destroy_cred(scm);
 }
 
+static inline void scm_recv_unix(struct socket *sock, struct msghdr *msg,
+				 struct scm_cookie *scm, int flags)
+{
+	if (!__scm_recv_common(sock, msg, scm, flags))
+		return;
+
+	if (test_bit(SOCK_PASSPIDFD, &sock->flags))
+		scm_pidfd_recv(msg, scm);
+
+	scm_destroy_cred(scm);
+}
 
 #endif /* __LINUX_NET_SCM_H */