On 12/07/16(Tue) 11:33, Claudio Jeker wrote:
> On Tue, Jul 12, 2016 at 11:28:47AM +0200, Martin Pieuchot wrote:
> > By default we have a route to reject compatible addresses:
> >
> > ::/96 ::1 UGRS 0 0 32768 8 lo0
> >
> > But the corresponding check in ip6_input() is still commented because it
> > is "stronger than RFC1933". However since 1996 this RFC has been
> > obsoleted twice and the newer one, RFC4213 says:
> >
> > The following changes have been performed since RFC 2893:
> >
> > - Removed automatic tunneling and use of IPv4-compatible
> > addresses.
> >
> > - [...]
> >
> >
> > Then later it explicitly documents:
> >
> > After the decapsulation, the node MUST silently discard a packet with
> > an invalid IPv6 source address. The list of invalid source addresses
> > SHOULD include at least:
> >
> > - all the IPv4-compatible IPv6 addresses [RFC3513] (::/96),
> > excluding the unspecified address for Duplicate Address Detection
> > (::/128)
> >
> > - [...]
> >
> >
> > Do I understand correctly that it is time to enable this check?
>
> Would you then remove the ::/96 reject route from the routing table?
I think this should be a second discussion. We also have a route for
IPv4-mapped IPv6 addresses & have a similar check enabled in ip6_input():
::ffff:0.0.0.0/96 ::1 UGRS 0 0 32768 8 lo0
Now routes also prevent any user from sending packets to such destinations.
Note that we don't have similar checks in ip6_output().
> Or is this more a belt and suspender kind of thing?
It is.
> > Index: netinet6/ip6_input.c
> > ===================================================================
> > RCS file: /cvs/src/sys/netinet6/ip6_input.c,v
> > retrieving revision 1.162
> > diff -u -p -r1.162 ip6_input.c
> > --- netinet6/ip6_input.c 6 Jul 2016 15:50:00 -0000 1.162
> > +++ netinet6/ip6_input.c 12 Jul 2016 09:17:04 -0000
> > @@ -299,20 +299,17 @@ ip6_input(struct mbuf *m)
> > ip6stat.ip6s_badscope++;
> > goto bad;
> > }
> > -#if 0
> > +
> > /*
> > * Reject packets with IPv4 compatible addresses (auto tunnel).
> > *
> > - * The code forbids auto tunnel relay case in RFC1933 (the check is
> > - * stronger than RFC1933). We may want to re-enable it if mech-xx
> > - * is revised to forbid relaying case.
> > + * The code forbids automatic tunneling as per RFC4213.
> > */
> > if (IN6_IS_ADDR_V4COMPAT(&ip6->ip6_src) ||
> > IN6_IS_ADDR_V4COMPAT(&ip6->ip6_dst)) {
> > ip6stat.ip6s_badscope++;
> > goto bad;
> > }
> > -#endif
> >
> > /*
> > * If the packet has been received on a loopback interface it
> >
>
> --
> :wq Claudio
>
