channel-socket: Only set CLOEXEC if we have space for fds

MSG_CMSG_CLOEXEC cleans up received fd's; it's really only for Unix
sockets, but currently we enable it for everything; some socket types
(IP_MPTCP) don't like this.

Only enable it when we're giving the recvmsg room to receive fd's
anyway.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210421112834.107651-2-dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

diff --git a/io/channel-socket.c b/io/channel-socket.c
index de259f7eed2752c92ec0b1b77e90896e8ea314e4..606ec97cf7c39023c6419a2a1976b09eb836d41f 100644 (file)
--- a/io/channel-socket.c
+++ b/io/channel-socket.c
@@ -487,15 +487,15 @@ static ssize_t qio_channel_socket_readv(QIOChannel *ioc,
 
     memset(control, 0, CMSG_SPACE(sizeof(int) * SOCKET_MAX_FDS));
 
-#ifdef MSG_CMSG_CLOEXEC
-    sflags |= MSG_CMSG_CLOEXEC;
-#endif
-
     msg.msg_iov = (struct iovec *)iov;
     msg.msg_iovlen = niov;
     if (fds && nfds) {
         msg.msg_control = control;
         msg.msg_controllen = sizeof(control);
+#ifdef MSG_CMSG_CLOEXEC
+        sflags |= MSG_CMSG_CLOEXEC;
+#endif
+
     }
 
  retry: