[src/trunk]: src/sys/netinet6 Fix RTF_{REJECT, BLACKHOLE} behavior for IPv6 ro...

[ozaki-r <ozaki-r%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/ff1c6136c03d
branches:  trunk
changeset: 344795:ff1c6136c03d
user:      ozaki-r <ozaki-r%NetBSD.org@localhost>
date:      Thu Apr 21 05:07:50 2016 +0000

description:
Fix RTF_{REJECT,BLACKHOLE} behavior for IPv6 routes

We still need a nexthop route to reflect RTF_{REJECT,BLACKHOLE}.
In the future, we would do it w/o looking up a route.

diffstat:

 sys/netinet6/nd6.c |  85 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 83 insertions(+), 2 deletions(-)

diffs (127 lines):

diff -r 1196c6b0ab3e -r ff1c6136c03d sys/netinet6/nd6.c
--- a/sys/netinet6/nd6.c        Wed Apr 20 17:18:52 2016 +0000
+++ b/sys/netinet6/nd6.c        Thu Apr 21 05:07:50 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nd6.c,v 1.190 2016/04/10 08:15:52 ozaki-r Exp $        */
+/*     $NetBSD: nd6.c,v 1.191 2016/04/21 05:07:50 ozaki-r Exp $        */
 /*     $KAME: nd6.c,v 1.279 2002/06/08 11:16:51 itojun Exp $   */
 
 /*
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nd6.c,v 1.190 2016/04/10 08:15:52 ozaki-r Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nd6.c,v 1.191 2016/04/21 05:07:50 ozaki-r Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_net_mpsafe.h"
@@ -2107,6 +2107,70 @@
        mutex_exit(softnet_lock);
 }
 
+/*
+ * Next hop determination.  This routine was derived from ip_output.c.
+ */
+static int
+nd6_determine_nexthop(struct ifnet *ifp, const struct sockaddr_in6 *dst,
+    struct rtentry *rt0, struct rtentry **ret_rt, bool *sendpkt)
+{
+       struct rtentry *rt = rt0;
+       struct rtentry *gwrt = NULL;
+       struct sockaddr_in6 *gw6 = satosin6(rt->rt_gateway);
+
+       /*
+        * We skip link-layer address resolution and NUD
+        * if the gateway is not a neighbor from ND point
+        * of view, regardless of the value of nd_ifinfo.flags.
+        * The second condition is a bit tricky; we skip
+        * if the gateway is our own address, which is
+        * sometimes used to install a route to a p2p link.
+        */
+       if (!nd6_is_addr_neighbor(gw6, ifp) ||
+           in6ifa_ifpwithaddr(ifp, &gw6->sin6_addr)) {
+               /*
+                * We allow this kind of tricky route only
+                * when the outgoing interface is p2p.
+                * XXX: we may need a more generic rule here.
+                */
+               if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
+                       goto hostunreach;
+
+               *sendpkt = true;
+               return 0;
+       }
+
+       /* Try to use a cached nexthop route (gwroute) if exists */
+       gwrt = rt_get_gwroute(rt);
+       if (gwrt == NULL || (gwrt->rt_flags & RTF_UP) == 0) {
+               if (gwrt != NULL) {
+                       rtfree(gwrt);
+               }
+               /* Look up a nexthop route */
+               gwrt = rtalloc1(rt->rt_gateway, 1);
+               rt_set_gwroute(rt, gwrt);
+               rt = gwrt;
+               if (rt == NULL)
+                       goto hostunreach;
+               /* the "G" test below also prevents rt == rt0 */
+               if ((rt->rt_flags & RTF_GATEWAY) ||
+                   (rt->rt_ifp != ifp)) {
+                       if (rt0->rt_gwroute != NULL)
+                               rtfree(rt0->rt_gwroute);
+                       rt0->rt_gwroute = NULL;
+                       goto hostunreach;
+               }
+       }
+       *ret_rt = gwrt;
+       return 0;
+
+hostunreach:
+       if (gwrt != NULL)
+               rtfree(gwrt);
+
+       return EHOSTUNREACH;
+}
+
 int
 nd6_output(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m,
     const struct sockaddr_in6 *dst, struct rtentry *rt)
@@ -2115,6 +2179,7 @@
        struct llentry *ln = NULL;
        int error = 0;
        bool created = false;
+       struct rtentry *nexthop = NULL;
 
        if (IN6_IS_ADDR_MULTICAST(&dst->sin6_addr))
                goto sendpkt;
@@ -2129,6 +2194,19 @@
         * or an anycast address(i.e. not a multicast).
         */
 
+       if (rt != NULL && (rt->rt_flags & RTF_GATEWAY) != 0) {
+               bool sendpkt = false;
+
+               /* Still need a nexthop to reflect RTF_{REJECT,BLACKHOLE} */
+               error = nd6_determine_nexthop(ifp, dst, rt, &nexthop, &sendpkt);
+               if (error != 0)
+                       senderr(error);
+               if (nexthop != NULL)
+                       rt = nexthop;
+               if (sendpkt)
+                       goto sendpkt;
+       }
+
        /* Look up the neighbor cache for the nexthop */
        ln = nd6_lookup(&dst->sin6_addr, ifp, true);
        if ((ln == NULL) && nd6_is_addr_neighbor(dst, ifp))  {
@@ -2262,6 +2340,9 @@
        if (m != NULL)
                m_freem(m);
   exit:
+       if (nexthop != NULL)
+               rtfree(nexthop);
+
        if (created)
                nd6_gc_neighbors(LLTABLE6(ifp));