Re: point2point network interfaces cannot receive ipv6 packets

[Paul Goyette <paul%vps1.whooppee.com@localhost>]

I can confirm that this patch works on my tun device (carrying ipv6 
inside ipv4).


On Sun, 12 Apr 2015, Roy Marples wrote:

> On Fri, 2015-04-10 at 17:27 +0100, Robert Swindells wrote:
> > Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost> wrote:
> > > On 2015/04/03 16:14, Takahiro HAYASHI wrote:
> > > > It seems that IFF_POINTTOPOINT interfaces like tun and gif cannot
> > > > receive ipv6 packets.
> > > > This occurs on NetBSD/amd64 -current since Feb 27 2015.
> > > >
> > > > For example, establishing gif tunnnel between 2 hosts.
> > > >
> > > > [host1] <---> [host2]
> > > > 192.168.0.1   192.168.0.2  ipv4 address of real interface
> > > > fd00::1       fd00::2      gif address
> > > >
> > > > When I ping6, a host can send ICMPv6 ECHO(128), but the other host
> > > > returns ICMPv6 DST_UNREACH(1) code UNREACH_ADDR(3) to pinging host.
> > >
> > > I think the reason of this issue is below commit:
> > >    http://www.nerv.org/netbsd/?q=id:20150226T095446Z.75354d997222ae09acc944ba1c6cf573c3ea724b
> >
> > The following patch helps for me. It results in the RTF_LLINFO flag getting
> > set for the route for the interface.
> >
> > The comment looks to be incorrect in any case.
> >
> > Robert Swindells
> >
> > Index: in6.c
> > ===================================================================
> > RCS file: /cvsroot/src/sys/netinet6/in6.c,v
> > retrieving revision 1.186
> > diff -u -r1.186 in6.c
> > --- in6.c       7 Apr 2015 23:30:36 -0000       1.186
> > +++ in6.c       10 Apr 2015 16:10:31 -0000
> > @@ -1695,7 +1695,7 @@
> >         /* Add ownaddr as loopback rtentry, if necessary (ex. on p2p link). */
> >         if (newhost) {
> >                 /* set the rtrequest function to create llinfo */
> > -               if ((ifp->if_flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) == 0)
> > +               if ((ifp->if_flags & IFF_LOOPBACK) == 0)
> >                         ia->ia_ifa.ifa_rtrequest = nd6_rtrequest;
> >                 in6_ifaddlocal(&ia->ia_ifa);
> >         } else {
>
> We shouldn't really need the LLINFO flag on P2P interfaces.
> Here is a patch which introduces p2p_rtrequest() which installs a
> correct and working local route for P2P interfaces, based on an older
> patch for OpenBSD.
>
> I intend to commit this to fix the PR early next week when I can put
> more testing into it. Commentary welcome as I can't test many P2P
> interfaces.
>
> Roy

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