SELinux: Add warning messages on network denial due to error

Currently network traffic can be sliently dropped due to non-avc errors which
can lead to much confusion when trying to debug the problem.  This patch adds
warning messages so that when these events occur there is a user visible
notification.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/selinux/netnode.c b/security/selinux/netnode.c
index 49c5277..f3c526f 100644
--- a/security/selinux/netnode.c
+++ b/security/selinux/netnode.c
@@ -264,8 +264,12 @@
 
 out:
 	spin_unlock_bh(&sel_netnode_lock);
-	if (ret != 0)
+	if (unlikely(ret)) {
+		printk(KERN_WARNING
+		       "SELinux: failure in sel_netnode_sid_slow(),"
+		       " unable to determine network node label\n");
 		kfree(new);
+	}
 	return ret;
 }