From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Florian Westphal <fw@strlen.de>
Cc: Leonardo Bras <leonardo@linux.ibm.com>,
netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
bridge@lists.linux-foundation.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org,
Jozsef Kadlecsik <kadlec@netfilter.org>,
Roopa Prabhu <roopa@cumulusnetworks.com>,
Nikolay Aleksandrov <nikolay@cumulusnetworks.com>,
"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH v4 1/2] netfilter: Terminate rule eval if protocol=IPv6 and ipv6 module is disabled
Date: Tue, 3 Sep 2019 21:31:55 +0200 [thread overview]
Message-ID: <20190903193155.v74ws47zcn6zrwpr@salvia> (raw)
In-Reply-To: <20190903170550.GA13660@breakpoint.cc>
On Tue, Sep 03, 2019 at 07:05:50PM +0200, Florian Westphal wrote:
> Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > On Tue, Sep 03, 2019 at 01:46:50PM -0300, Leonardo Bras wrote:
> > > On Fri, 2019-08-30 at 22:58 +0200, Florian Westphal wrote:
> > > > Leonardo Bras <leonardo@linux.ibm.com> wrote:
> > > > > If IPv6 is disabled on boot (ipv6.disable=1), but nft_fib_inet ends up
> > > > > dealing with a IPv6 packet, it causes a kernel panic in
> > > > > fib6_node_lookup_1(), crashing in bad_page_fault.
> > > > >
> > > > > The panic is caused by trying to deference a very low address (0x38
> > > > > in ppc64le), due to ipv6.fib6_main_tbl = NULL.
> > > > > BUG: Kernel NULL pointer dereference at 0x00000038
> > > > >
> > > > > The kernel panic was reproduced in a host that disabled IPv6 on boot and
> > > > > have to process guest packets (coming from a bridge) using it's ip6tables.
> > > > >
> > > > > Terminate rule evaluation when packet protocol is IPv6 but the ipv6 module
> > > > > is not loaded.
> > > > >
> > > > > Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com>
> > > >
> > > > Acked-by: Florian Westphal <fw@strlen.de>
> > > >
> > >
> > > Hello Pablo,
> > >
> > > Any trouble with this patch?
> > > I could see the other* one got applied, but not this one.
> > > *(The other did not get acked, so i released it alone as v5)
> > >
> > > Is there any fix I need to do in this one?
> >
> > Hm, I see, so this one:
> >
> > https://patchwork.ozlabs.org/patch/1156100/
> >
> > is not enough?
>
> No, its not.
>
> > I was expecting we could find a way to handle this from br_netfilter
> > alone itself.
>
> We can't because we support ipv6 fib lookups from the netdev family
> as well.
>
> Alternative is to auto-accept ipv6 packets from the nf_tables eval loop,
> but I think its worse.
Could we add a restriction for nf_tables + br_netfilter + !ipv6. I
mean, if this is an IPv6 packet, nf_tables is on and IPv6 module if
off, then drop this packet?
By dropping packet, the user could diagnose that its setup is
incomplete. I mean, if nf_tables fib ipv6 is used, then this setup is
really wrong and the user forgots to load the ipv6 module.
next prev parent reply other threads:[~2019-09-03 19:32 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-30 18:13 [PATCH v4 0/2] Drop IPV6 packets if IPv6 is disabled on boot Leonardo Bras
2019-08-30 18:13 ` [PATCH v4 1/2] netfilter: Terminate rule eval if protocol=IPv6 and ipv6 module is disabled Leonardo Bras
2019-08-30 20:58 ` Florian Westphal
2019-09-03 16:46 ` Leonardo Bras
2019-09-03 16:49 ` Pablo Neira Ayuso
2019-09-03 16:56 ` Leonardo Bras
2019-09-03 17:05 ` Florian Westphal
2019-09-03 19:31 ` Pablo Neira Ayuso [this message]
2019-09-03 19:48 ` Florian Westphal
2019-09-03 20:19 ` Pablo Neira Ayuso
2019-09-03 20:35 ` Florian Westphal
2019-09-03 20:55 ` Pablo Neira Ayuso
2019-09-03 20:55 ` Pablo Neira Ayuso
2019-08-30 18:13 ` [PATCH v4 2/2] net: br_netfiler_hooks: Drops IPv6 packets if IPv6 module is not loaded Leonardo Bras
2019-08-30 20:55 ` Florian Westphal
2019-08-31 4:42 ` Leonardo Bras
2019-08-31 8:43 ` Florian Westphal
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