SELinux: indicate fatal error in compat netfilter code

The SELinux ip postroute code indicates when policy rejected a packet and
passes the error back up the stack.  The compat code does not.  This patch
sends the same kind of error back up the stack in the compat code.
Based-on-patch-by: NPaul Moore <paul.moore@hp.com>
Signed-off-by: NEric Paris <eparis@redhat.com>
Reviewed-by: NPaul Moore <paul.moore@hp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

security/selinux/hooks.c

@@ -4524,11 +4524,11 @@ static unsigned int selinux_ip_postroute_compat(struct sk_buff *skb,
 	if (selinux_secmark_enabled())
 		if (avc_has_perm(sksec->sid, skb->secmark,
 				 SECCLASS_PACKET, PACKET__SEND, &ad))
-			return NF_DROP;
+			return NF_DROP_ERR(-ECONNREFUSED);
 
 	if (selinux_policycap_netpeer)
 		if (selinux_xfrm_postroute_last(sksec->sid, skb, &ad, proto))
-			return NF_DROP;
+			return NF_DROP_ERR(-ECONNREFUSED);
 
 	return NF_ACCEPT;
 }