netdev - Re: [PATCH 3/3] netfilter: nat: don't assign a null snat rule to bridged traffic if no matching

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Date:	Sun, 31 Jul 2016 21:02:26 +0200
From:	Florian Westphal <fw@...len.de>
To:	fxp2001640163@...il.com
Cc:	pablo@...filter.org, kaber@...sh.net, kadlec@...ckhole.kfki.hu,
	netfilter-devel@...r.kernel.org, coreteam@...filter.org,
	netdev@...r.kernel.org, Xiaoping Fan <xfan@...eaurora.org>
Subject: Re: [PATCH 3/3] netfilter: nat: don't assign a null snat rule to
 bridged traffic if no matching

fxp2001640163@...il.com <fxp2001640163@...il.com> wrote:
> From: Xiaoping Fan <xfan@...eaurora.org>
> 
> In some case, bridged packet will come back again for routing. When bridge
> netfilter is enabled, a null snat rule is assigned to bridged packet if no
> matching in nat chain. Then nat rule matching is skipped when packet comes
> back for routing. This result in private IP address exported to public
> network. So we don't assign a null snat rule to bridged traffic if no
> matching.

This looks bogus.

However, we already have issue with existing iptables nat vs nftables
nat.

So I think it might make sense to delay NULL binding allocation until
we confirm the conntrack so users don't have to rmmod iptable_nat
anymore when they use nftables as well.