On Wed, Mar 22, 2017 at 02:44:12PM +0100, Florian Westphal wrote:
> Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote:
> > On Tue, Mar 21, 2017 at 07:54:37PM +0100, Florian Westphal wrote:
> > > nft add rule ip6 f i meta l4proto ipv6-icmp icmpv6 type nd-router-advert
> > > <cmdline>:1:50-60: Error: conflicting protocols specified: unknown vs. icmpv6
> > >
> > > add icmpv6 to nexthdr list so base gets updated correctly.
> > >
> > > Reported-by: Thomas Woerner <twoerner@xxxxxxxxxx>
> > > Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
> > > ---
> > > NB: This is STILL not correct.
> > > nft add rule ip6 f i meta l4proto ipv6-icmp icmpv6 type nd-router-advert
> > > gets listed as
> > > icmpv6 type nd-router-advert
> > >
> > > because post processing removes the l3 dependency.
> > >
> > > However, "icmpv6 type nd-router-advert" uses dependency
> > > ip6 nexthdr icmpv6
> > > which isn't the same as meta l4proto icmpv6.
> > >
> > > I suspect nft should always generate implicit l4 dependencies
> > > via meta in the ipv6 case, what do others think
> > > (and not autoremove 'nexthdr' check)?
> >
> > I think we should use meta l4proto, ip6 nexthdr may point to some of
> > the extension headers in the packet actually.
>
> Yes.
> Alright, I'll work on this change towards l4 meta.
>
> > > diff --git a/src/proto.c b/src/proto.c
> > > index 79e9dbf2b33e..fcdfbe73c735 100644
> > > --- a/src/proto.c
> > > +++ b/src/proto.c
> > > @@ -779,6 +779,7 @@ const struct proto_desc proto_inet_service = {
> > > PROTO_LINK(IPPROTO_TCP, &proto_tcp),
> > > PROTO_LINK(IPPROTO_DCCP, &proto_dccp),
> > > PROTO_LINK(IPPROTO_SCTP, &proto_sctp),
> > > + PROTO_LINK(IPPROTO_ICMPV6, &proto_icmp6),
> >
> > This also allows icmp6 from IPv4, right? I remember I mentioned this
> > in a patch that I attached to bugzilla at some point so I didn't apply
> > this.
>
> Yes, whats the concern with that?
Not a problem these days from inet/netdev chains since:
commit 0011985554e269e1cc8f8e5b41eb9dcd795ebe8c
Author: Arturo Borrero Gonzalez <arturo@xxxxxxxxxx>
Date: Wed Jan 25 12:51:08 2017 +0100
payload: explicit network ctx assignment for icmp/icmp6 in special families
Now we generate the right bytecode to restrict this to IPv6:
# nft --debug=netlink add rule inet f i icmpv6 type nd-router-advert
inet f i
[ meta load nfproto => reg 1 ]
[ cmp eq reg 1 0x0000000a ]
[ payload load 1b @ network header + 6 => reg 1 ]
[ cmp eq reg 1 0x0000003a ]
[ payload load 1b @ transport header + 0 => reg 1 ]
[ cmp eq reg 1 0x00000086 ]
So forget my concern, just remove this mental "postit" note, it's stale ;)
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