audit: Use current instead of NETLINK_CREDS() in audit_filter

Get caller process uid and gid and pid values from the current task
instead of the NETLINK_CB.  This is simpler than passing NETLINK_CREDS
from from audit_receive_msg to audit_filter_user_rules and avoid the
chance of being hit by the occassional bugs in netlink uid/gid
credential passing.  This is a safe changes because all netlink
requests are processed in the task of the sending process.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/kernel/audit.c b/kernel/audit.c
index 7b7268e..fecb150 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -744,7 +744,7 @@
 		if (!audit_enabled && msg_type != AUDIT_USER_AVC)
 			return 0;
 
-		err = audit_filter_user(&NETLINK_CB(skb));
+		err = audit_filter_user();
 		if (err == 1) {
 			err = 0;
 			if (msg_type == AUDIT_USER_TTY) {