Correct a bug introduced with reduced TCP state handling; make

sure that the MAC label on TCP responses during TIMEWAIT is
properly set from either the socket (if available), or the mbuf
that it's responding to.

Unfortunately, this is made somewhat difficult by the TCP code,
as tcp_twstart() calls tcp_twrespond() after discarding the socket
but without a reference to the mbuf that causes the "response".
Passing both the socket and the mbuf works arounds this--eventually
it might be good to make sure the mbuf always gets passed in in
"response" scenarios but working through this provided to
complicate things too much.

Approved by:	re (scottl)
Reviewed by:	hsu
Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, Network Associates Laboratories

1 files changed, 18 insertions, 3 deletions

diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index 58395f5..8816bc6 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -1661,13 +1661,13 @@ tcp_twstart(tp)
 	so->so_pcb = NULL;
 	tw->tw_cred = crhold(so->so_cred);
 	tw->tw_so_options = so->so_options;
+	if (acknow)
+		tcp_twrespond(tw, so, NULL, TH_ACK);
 	sotryfree(so);
 	inp->inp_socket = NULL;
 	inp->inp_ppcb = (caddr_t)tw;
 	inp->inp_vflag |= INP_TIMEWAIT;
 	tcp_timer_2msl_reset(tw, tw_time);
-	if (acknow)
-		tcp_twrespond(tw, TH_ACK);
 	INP_UNLOCK(inp);
 }
 
@@ -1693,8 +1693,13 @@ tcp_twclose(struct tcptw *tw, int reuse)
 	return (NULL);
 }
 
+/*
+ * One of so and msrc must be non-NULL for use by the MAC Framework to
+ * construct a label for ay resulting packet.
+ */
 int
-tcp_twrespond(struct tcptw *tw, int flags)
+tcp_twrespond(struct tcptw *tw, struct socket *so, struct mbuf *msrc,
+    int flags)
 {
 	struct inpcb *inp = tw->tw_inpcb;
 	struct tcphdr *th;
@@ -1708,11 +1713,21 @@ tcp_twrespond(struct tcptw *tw, int flags)
 	int isipv6 = inp->inp_inc.inc_isipv6;
 #endif
 
+	KASSERT(so != NULL || msrc != NULL,
+	    ("tcp_twrespond: so and msrc NULL"));
+
 	m = m_gethdr(M_DONTWAIT, MT_HEADER);
 	if (m == NULL)
 		return (ENOBUFS);
 	m->m_data += max_linkhdr;
 
+#ifdef MAC
+	if (so != NULL)
+		mac_create_mbuf_from_socket(so, m);
+	else
+		mac_create_mbuf_netlayer(msrc, m);
+#endif
+
 #ifdef INET6
 	if (isipv6) {
 		hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);