From: Florian Westphal <fw@strlen•de>
To: Jiri Pirko <jiri@resnulli•us>
Cc: netdev@vger•kernel.org, davem@davemloft•net, pablo@netfilter•org,
netfilter-devel@vger•kernel.org, yoshfuji@linux-ipv6•org,
kadlec@blackhole•kfki.hu, kaber@trash•net, mleitner@redhat•com,
kuznet@ms2•inr.ac.ru, jmorris@namei•org, wensong@linux-vs•org,
horms@verge•net.au, ja@ssi•bg, edumazet@google•com,
pshelar@nicira•com, jasowang@redhat•com,
alexander.h.duyck@intel•com, coreteam@netfilter•org,
fw@strlen•de
Subject: Re: [patch net-next 2/3] netfilter: ip6_tables: use reasm skb for matching
Date: Tue, 5 Nov 2013 14:32:05 +0100 [thread overview]
Message-ID: <20131105133205.GC15370@breakpoint.cc> (raw)
In-Reply-To: <1383649333-6321-3-git-send-email-jiri@resnulli.us>
Jiri Pirko <jiri@resnulli•us> wrote:
> This patch fixes for example following situation:
> On HOSTA do:
> ip6tables -I INPUT -p icmpv6 -j DROP
> ip6tables -I INPUT -p icmpv6 -m icmp6 --icmpv6-type 128 -j ACCEPT
untested:
-A INPUT -p icmpv6 -m icmp6 --icmpv6-type 128 -j ACCEPT
-A INPUT -p icmpv6 -m conntrack --ctstatus CONFIRMED -j ACCEPT
-A INPUT -p icmpv6 -j DROP
> and on HOSTB you do:
> ping6 HOSTA -s2000 (MTU is 1500)
>
> Incoming echo requests will be filtered out on HOSTA. This issue does
> not occur with smaller packets than MTU (where fragmentation does not happen).
Patrick, any reason not to kill the special-casing (ct has assigned helper or
unconfirmed conntrack) in __ipv6_conntrack_in() ?
This should make ipv6 frag behaviour consistent; right now its rather
confusing from ruleset point of view, especially the first packet
of a connection is always seen as reassembled.
So with Jiris rules
-A INPUT -p icmpv6 -m icmp6 --icmpv6-type 128 -j ACCEPT
-A INPUT -p icmpv6 -j DROP
ping6 -s $bignum works for the first packet but not for subsequent ones
which is quite irritating.
This change would obviously have userspace visibility (e.g. -m frag
won't work anymore when conntrack is on), but so far I couldn't come
up with a scenario where a legitimate ruleset could break.
next prev parent reply other threads:[~2013-11-05 13:32 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-05 11:02 [patch net-next 0/3] couple of reasm fixes Jiri Pirko
2013-11-05 11:02 ` [patch net-next 1/3] move skb_nfct_reasm into skbuff.h Jiri Pirko
2013-11-05 11:50 ` Marcelo Ricardo Leitner
2013-11-06 1:00 ` Simon Horman
2013-11-05 11:02 ` [patch net-next 2/3] netfilter: ip6_tables: use reasm skb for matching Jiri Pirko
2013-11-05 11:50 ` Marcelo Ricardo Leitner
2013-11-05 13:32 ` Florian Westphal [this message]
2013-11-05 13:41 ` Patrick McHardy
2013-11-05 15:01 ` Jiri Pirko
2013-11-05 15:39 ` Florian Westphal
2013-11-05 18:19 ` Patrick McHardy
2013-11-05 18:21 ` Jiri Pirko
2013-11-05 18:16 ` Patrick McHardy
2013-11-05 20:55 ` Jiri Pirko
2013-11-05 22:02 ` Patrick McHardy
2013-11-06 14:18 ` Jiri Pirko
2013-11-06 14:33 ` Florian Westphal
2013-11-06 14:44 ` Jiri Pirko
2013-11-06 14:51 ` Patrick McHardy
2013-11-06 15:29 ` Jiri Pirko
2013-11-06 16:12 ` Eric Dumazet
2013-11-05 11:02 ` [patch net-next 3/3] fix skb_morph to preserve skb->sk and skb->destructor pointers Jiri Pirko
2013-11-05 11:50 ` Marcelo Ricardo Leitner
2013-11-05 14:06 ` Eric Dumazet
2013-11-05 14:47 ` Jiri Pirko
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