svn commit: r329582 - stable/11/sys/netinet6

[Eric van Gyzen]

Author: vangyzen
Date: Mon Feb 19 15:56:33 2018
New Revision: 329582
URL: https://svnweb.freebsd.org/changeset/base/329582

Log:
  MFC r329181
  
  Update the MTU in affected routes when IPv6 RA changes the MTU
  
  ip6_calcmtu() only looks at the interface MTU if neither the TCP hostcache
  nor the route provides an MTU.  Update the routes so they do not provide
  stale MTUs.
  
  This fixes UNH IPv6 conformance test cases v6LC_4_1_08 and v6LC_4_1_09,
  which use a RA to reduce the link MTU from 1500 to 1280.
  
  Reported and tested by:	Farrell Woods <Farrell_Woods at Dell.com>
  Sponsored by:	Dell EMC
  Differential Revision:	https://reviews.freebsd.org/D14257

Modified:
  stable/11/sys/netinet6/nd6_rtr.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/netinet6/nd6_rtr.c
==============================================================================
--- stable/11/sys/netinet6/nd6_rtr.c	Mon Feb 19 15:54:26 2018	(r329581)
+++ stable/11/sys/netinet6/nd6_rtr.c	Mon Feb 19 15:56:33 2018	(r329582)
@@ -406,8 +406,11 @@ nd6_ra_input(struct mbuf *m, int off, int icmp6len)
 			int change = (ndi->linkmtu != mtu);
 
 			ndi->linkmtu = mtu;
-			if (change) /* in6_maxmtu may change */
+			if (change) {
+				/* in6_maxmtu may change */
 				in6_setmaxmtu();
+				rt_updatemtu(ifp);
+			}
 		} else {
 			nd6log((LOG_INFO, "nd6_ra_input: bogus mtu "
 			    "mtu=%lu sent from %s; "