[src/trunk]: src/sys/net Fix a bug that vlan(4) fragments IPv6 packets

[yamaguchi <yamaguchi%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/fbfd019c19db
branches:  trunk
changeset: 460948:fbfd019c19db
user:      yamaguchi <yamaguchi%NetBSD.org@localhost>
date:      Mon Nov 11 02:34:46 2019 +0000

description:
Fix a bug that vlan(4) fragments IPv6 packets
even the MTU > packet length.

The bug is appeared when the mtu is increased on SIOCSETVLAN.

>From t-kusaba@IIJ

diffstat:

 sys/net/if_vlan.c |  11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diffs (39 lines):

diff -r 6bee9b0d2975 -r fbfd019c19db sys/net/if_vlan.c
--- a/sys/net/if_vlan.c Sun Nov 10 23:39:03 2019 +0000
+++ b/sys/net/if_vlan.c Mon Nov 11 02:34:46 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_vlan.c,v 1.147 2019/10/21 06:26:12 ozaki-r Exp $    */
+/*     $NetBSD: if_vlan.c,v 1.148 2019/11/11 02:34:46 yamaguchi Exp $  */
 
 /*
  * Copyright (c) 2000, 2001 The NetBSD Foundation, Inc.
@@ -78,7 +78,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_vlan.c,v 1.147 2019/10/21 06:26:12 ozaki-r Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_vlan.c,v 1.148 2019/11/11 02:34:46 yamaguchi Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -119,6 +119,7 @@
 #ifdef INET6
 #include <netinet6/in6_ifattach.h>
 #include <netinet6/in6_var.h>
+#include <netinet6/nd6.h>
 #endif
 
 #include "ioconf.h"
@@ -540,6 +541,12 @@
        nmib->ifvm_p = p;
        nmib->ifvm_tag = vid;
        ifv->ifv_if.if_mtu = p->if_mtu - nmib->ifvm_mtufudge;
+#ifdef INET6
+       KERNEL_LOCK_UNLESS_NET_MPSAFE();
+       if (in6_present)
+               nd6_setmtu(ifp);
+       KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
+#endif
        ifv->ifv_if.if_flags = p->if_flags &
            (IFF_UP | IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST);