netdev - Re: [PATCH v15 nf-next 3/3] netfilter: nft_chain_filter: Add bridge double vlan and pppoe

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Message-ID: <a4a3dce4-0f2c-4153-abbe-81e5d2715bbe@gmail.com>
Date: Tue, 28 Oct 2025 12:43:12 +0100
From: Eric Woudstra <ericwouds@...il.com>
To: Florian Westphal <fw@...len.de>
Cc: Pablo Neira Ayuso <pablo@...filter.org>,
 Jozsef Kadlecsik <kadlec@...filter.org>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Simon Horman <horms@...nel.org>, Nikolay Aleksandrov <razor@...ckwall.org>,
 Ido Schimmel <idosch@...dia.com>, netfilter-devel@...r.kernel.org,
 netdev@...r.kernel.org, bridge@...ts.linux.dev
Subject: Re: [PATCH v15 nf-next 3/3] netfilter: nft_chain_filter: Add bridge
 double vlan and pppoe

On 10/2/25 10:25 AM, Florian Westphal wrote:
> Eric Woudstra <ericwouds@...il.com> wrote:
>> This adds the capability to evaluate 802.1ad, QinQ, PPPoE and PPPoE-in-Q
>> packets in the bridge filter chain.
> 
> Same comment as previous patch, this needs to explain the why, not the what.
> 
> nft_do_chain_bridge() passes all packets to the interpreter, so the
> above statement is not correct either, you can already filter on all of
> these packet types.  This exposes NFT_PKTINFO_L4PROTO etc, which is
> different than what this commit message says.

So I have corrected the commit messages now, but:

> I also vaguely remember I commented that this changes (breaks?) existing
> behaviour for a rule like "tcp dport 22 accept" which may now match e.g.
> a PPPoE packet.
> 
> Pablo, whats your take on this?  Do we need a new NFPROTO_BRIDGE
> expression that can munge (populate) nft_pktinfo with the l4 data?
> 
> That would move this off to user policy (config) land.
> 
> (or extend nft_meta_bridge, doesn't absolutely require a brand new expression).
> 
Did you get any answer on this somewhere? I think that answer may affect
this commit, so I'll wait before sending the next version for now.