Re: [PATCH v2 net-next] af_unix: dont send SCM_CREDENTIALS by default

From: Eric Dumazet <redacted>
Date: Mon, 19 Sep 2011 17:52:27 +0200

This patch includes SCM_CREDENTIALS information in a af_unix message/skb
only if requested by the sender, [man 7 unix for details how to include
ancillary data using sendmsg() system call]

Note: This might break buggy applications that expected SCM_CREDENTIAL
from an unaware write() system call, and receiver not using SO_PASSCRED
socket option.

If SOCK_PASSCRED is set on source or destination socket, we still
include credentials for mere write() syscalls.

I thought a lot about this and I think we should be able to get away
with this trick, so I've added this patch to net-next, thanks!