From: Florian Westphal <fw@strlen.de>
To: Leonardo Bras <leonardo@linux.ibm.com>
Cc: netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
bridge@lists.linux-foundation.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org,
Pablo Neira Ayuso <pablo@netfilter.org>,
Jozsef Kadlecsik <kadlec@netfilter.org>,
Florian Westphal <fw@strlen.de>,
Roopa Prabhu <roopa@cumulusnetworks.com>,
Nikolay Aleksandrov <nikolay@cumulusnetworks.com>,
"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH v4 2/2] net: br_netfiler_hooks: Drops IPv6 packets if IPv6 module is not loaded
Date: Fri, 30 Aug 2019 22:55:41 +0200 [thread overview]
Message-ID: <20190830205541.GR20113@breakpoint.cc> (raw)
In-Reply-To: <20190830181354.26279-3-leonardo@linux.ibm.com>
Leonardo Bras <leonardo@linux.ibm.com> wrote:
> A kernel panic can happen if a host has disabled IPv6 on boot and have to
> process guest packets (coming from a bridge) using it's ip6tables.
>
> IPv6 packets need to be dropped if the IPv6 module is not loaded.
>
> Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com>
> ---
> net/bridge/br_netfilter_hooks.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
> index d3f9592f4ff8..5e8693730df1 100644
> --- a/net/bridge/br_netfilter_hooks.c
> +++ b/net/bridge/br_netfilter_hooks.c
> @@ -493,6 +493,8 @@ static unsigned int br_nf_pre_routing(void *priv,
> brnet = net_generic(state->net, brnf_net_id);
> if (IS_IPV6(skb) || is_vlan_ipv6(skb, state->net) ||
> is_pppoe_ipv6(skb, state->net)) {
> + if (!ipv6_mod_enabled())
> + return NF_DROP;
> if (!brnet->call_ip6tables &&
> !br_opt_get(br, BROPT_NF_CALL_IP6TABLES))
> return NF_ACCEPT;
No, thats too aggressive and turns the bridge into an ipv6 blackhole.
There are two solutions:
1. The above patch, but use NF_ACCEPT instead
2. keep the DROP, but move it below the call_ip6tables test,
so that users can tweak call-ip6tables to accept packets.
Perhaps it would be good to also add a pr_warn_once() that
tells that ipv6 was disabled on command line and
call-ip6tables isn't supported in this configuration.
I would go with option two.
next prev parent reply other threads:[~2019-08-30 20:55 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
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 [this message]
2019-08-31 4:42 ` Leonardo Bras
2019-08-31 8:43 ` Florian Westphal
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190830205541.GR20113@breakpoint.cc \
--to=fw@strlen.de \
--cc=bridge@lists.linux-foundation.org \
--cc=coreteam@netfilter.org \
--cc=davem@davemloft.net \
--cc=kadlec@netfilter.org \
--cc=leonardo@linux.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=netfilter-devel@vger.kernel.org \
--cc=nikolay@cumulusnetworks.com \
--cc=pablo@netfilter.org \
--cc=roopa@cumulusnetworks.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).