Introduce two new MAC Framework and MAC policy entry points:

mac_reflect_mbuf_icmp()
  mac_reflect_mbuf_tcp()

These entry points permit MAC policies to do "update in place"
changes to the labels on ICMP and TCP mbuf headers when an ICMP or
TCP response is generated to a packet outside of the context of
an existing socket.  For example, in respond to a ping or a RST
packet to a SYN on a closed port.

Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, Network Associates Laboratories

sys/netinet/ip_icmp.c

@@ -648,6 +648,9 @@ icmp_reflect(m)
 		goto done;
 	}
 match:
+#ifdef MAC
+	mac_reflect_mbuf_icmp(m);
+#endif
 	t = IA_SIN(ia)->sin_addr;
 	ip->ip_src = t;
 	ip->ip_ttl = ip_defttl;

sys/netinet/tcp_subr.c

@@ -488,10 +488,10 @@ tcp_respond(tp, ipgen, th, m, ack, seq, flags)
 		mac_create_mbuf_from_socket(tp->t_inpcb->inp_socket, m);
 	} else {
 		/*
-		 * XXXMAC: This will need to call a mac function that
+		 * Packet is not associated with a socket, so possibly
-		 * modifies the mbuf label in place for TCP datagrams
+		 * update the label in place.
-		 * not associated with a PCB.
 		 */
+		mac_reflect_mbuf_tcp(m);
 	}
 #endif
 	nth->th_seq = htonl(seq);

sys/netinet/tcp_timewait.c

@@ -488,10 +488,10 @@ tcp_respond(tp, ipgen, th, m, ack, seq, flags)
 		mac_create_mbuf_from_socket(tp->t_inpcb->inp_socket, m);
 	} else {
 		/*
-		 * XXXMAC: This will need to call a mac function that
+		 * Packet is not associated with a socket, so possibly
-		 * modifies the mbuf label in place for TCP datagrams
+		 * update the label in place.
-		 * not associated with a PCB.
 		 */
+		mac_reflect_mbuf_tcp(m);
 	}
 #endif
 	nth->th_seq = htonl(seq);