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Date: Sun, 14 Jun 2026 00:25:47 +0200
From: Florian Westphal <fw@strlen.de>
To: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Ren Wei <n05ec@lzu.edu.cn>, netfilter-devel@vger.kernel.org,
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Subject: Re: [PATCH nf 1/1] netfilter: xt_nat: reject unsupported target
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In-Reply-To: <ai3WcsS00Rbjy61u@chamomile>

Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > We can only use NFPROTO_BRIDGE targets, never UNSPEC, for NF_BRIDGE
> > caller.
> 
> Maybe it is simply this patch:
> 
> commit b6fe26f86a1649f84e057f3f15605b08eda15497
> Author: Pablo Neira Ayuso <pablo@netfilter.org>
> Date:   Wed Apr 15 12:21:00 2026 +0200
>  
>     netfilter: xtables: restrict several matches to inet family
> 
> which was missing xt_nat.c?

No, ebtables targets are incompatible, they return different
values compared to ip/ip6tables.

We need a nft_target_bridge_validate (or alternative method) that
rejects all targets that are not NFPROTO_BRIDGE.

This is wnat ebtables.c already does which is why this poc would
not work for classic xtables.

That said, this patch (the xt_nat.c patch) might be a good idea
anyway, but I don't think its enough.