Subject: [PATCH 1/2] Revert "af_unix: dont send SCM_CREDENTIAL when dest socket is NULL"

From: [email-masked] (Eric W. Biederman)
Date: Wed, 03 Apr 2013 19:13:35 -0700

This reverts commit 14134f6584212d585b310ce95428014b653dfaf6.

The problem that the above patch was meant to address is that af_unix
messages are not being coallesced because we are sending unnecesarry
credentials.  Not sending credentials in maybe_add_creds totally
breaks unconnected unix domain sockets that wish to send credentails
to other sockets.

In practice this break some versions of udev because they receive a
message and the sending uid is bogus so they drop the message.

Cc: [email-masked]
Reported-by: Sven Joachim <[email-masked]>
Signed-off-by: "Eric W. Biederman" <[email-masked]>
---
 net/unix/af_unix.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 971282b..f153a8d 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1412,8 +1412,8 @@ static void maybe_add_creds(struct sk_buff *skb, const struct socket *sock,
 	if (UNIXCB(skb).cred)
 		return;
 	if (test_bit(SOCK_PASSCRED, &sock->flags) ||
-	    (other->sk_socket &&
-	    test_bit(SOCK_PASSCRED, &other->sk_socket->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();
 	}
-- 
1.7.5.4