Merge branch 'next' into for-linus

1 files changed, 23 insertions, 1 deletions

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index ec68e1c05b8..466fbcc5cf7 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1381,8 +1381,10 @@ static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
 static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)
 {
 	int err = 0;
+
 	UNIXCB(skb).pid  = get_pid(scm->pid);
-	UNIXCB(skb).cred = get_cred(scm->cred);
+	if (scm->cred)
+		UNIXCB(skb).cred = get_cred(scm->cred);
 	UNIXCB(skb).fp = NULL;
 	if (scm->fp && send_fds)
 		err = unix_attach_fds(scm, skb);
@@ -1392,6 +1394,24 @@ static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool sen
 }
 
 /*
+ * Some apps rely on write() giving SCM_CREDENTIALS
+ * We include credentials if source or destination socket
+ * asserted SOCK_PASSCRED.
+ */
+static void maybe_add_creds(struct sk_buff *skb, const struct socket *sock,
+			    const struct sock *other)
+{
+	if (UNIXCB(skb).cred)
+		return;
+	if (test_bit(SOCK_PASSCRED, &sock->flags) ||
+	    !other->sk_socket ||
+	    test_bit(SOCK_PASSCRED, &other->sk_socket->flags)) {
+		UNIXCB(skb).pid  = get_pid(task_tgid(current));
+		UNIXCB(skb).cred = get_current_cred();
+	}
+}
+
+/*
  *	Send AF_UNIX data.
  */
 
@@ -1538,6 +1558,7 @@ restart:
 
 	if (sock_flag(other, SOCK_RCVTSTAMP))
 		__net_timestamp(skb);
+	maybe_add_creds(skb, sock, other);
 	skb_queue_tail(&other->sk_receive_queue, skb);
 	if (max_level > unix_sk(other)->recursion_level)
 		unix_sk(other)->recursion_level = max_level;
@@ -1652,6 +1673,7 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
 		    (other->sk_shutdown & RCV_SHUTDOWN))
 			goto pipe_err_free;
 
+		maybe_add_creds(skb, sock, other);
 		skb_queue_tail(&other->sk_receive_queue, skb);
 		if (max_level > unix_sk(other)->recursion_level)
 			unix_sk(other)->recursion_level = max_level;