SELinux: return -ECONNREFUSED from ip_postroute to signal fatal error

The SELinux netfilter hooks just return NF_DROP if they drop a packet.  We
want to signal that a drop in this hook is a permanant fatal error and is not
transient.  If we do this the error will be passed back up the stack in some
places and applications will get a faster interaction that something went
wrong.
Signed-off-by: NEric Paris <eparis@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

security/selinux/hooks.c

@@ -4585,11 +4585,11 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb, int ifindex,
 				secmark_perm = PACKET__SEND;
 			break;
 		default:
-			return NF_DROP;
+			return NF_DROP_ERR(-ECONNREFUSED);
 		}
 		if (secmark_perm == PACKET__FORWARD_OUT) {
 			if (selinux_skb_peerlbl_sid(skb, family, &peer_sid))
-				return NF_DROP;
+				return NF_DROP_ERR(-ECONNREFUSED);
 		} else
 			peer_sid = SECINITSID_KERNEL;
 	} else {
@@ -4602,28 +4602,28 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb, int ifindex,
 	ad.u.net.netif = ifindex;
 	ad.u.net.family = family;
 	if (selinux_parse_skb(skb, &ad, &addrp, 0, NULL))
-		return NF_DROP;
+		return NF_DROP_ERR(-ECONNREFUSED);
 
 	if (secmark_active)
 		if (avc_has_perm(peer_sid, skb->secmark,
 				 SECCLASS_PACKET, secmark_perm, &ad))
-			return NF_DROP;
+			return NF_DROP_ERR(-ECONNREFUSED);
 
 	if (peerlbl_active) {
 		u32 if_sid;
 		u32 node_sid;
 
 		if (sel_netif_sid(ifindex, &if_sid))
-			return NF_DROP;
+			return NF_DROP_ERR(-ECONNREFUSED);
 		if (avc_has_perm(peer_sid, if_sid,
 				 SECCLASS_NETIF, NETIF__EGRESS, &ad))
-			return NF_DROP;
+			return NF_DROP_ERR(-ECONNREFUSED);
 
 		if (sel_netnode_sid(addrp, family, &node_sid))
-			return NF_DROP;
+			return NF_DROP_ERR(-ECONNREFUSED);
 		if (avc_has_perm(peer_sid, node_sid,
 				 SECCLASS_NODE, NODE__SENDTO, &ad))
-			return NF_DROP;
+			return NF_DROP_ERR(-ECONNREFUSED);
 	}
 
 	return NF_ACCEPT;