netdev - Re: [PATCH nf-next v4 5/5] af_packet: Introduce egress hook

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Date:   Sun, 24 Jan 2021 12:14:32 +0100
From:   Lukas Wunner <lukas@...ner.de>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        netfilter-devel <netfilter-devel@...r.kernel.org>,
        coreteam@...filter.org,
        Network Development <netdev@...r.kernel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Thomas Graf <tgraf@...g.ch>,
        Laura Garcia Liebana <nevola@...il.com>,
        John Fastabend <john.fastabend@...il.com>
Subject: Re: [PATCH nf-next v4 5/5] af_packet: Introduce egress hook

On Fri, Jan 22, 2021 at 11:13:19AM -0500, Willem de Bruijn wrote:
> On Fri, Jan 22, 2021 at 4:44 AM Lukas Wunner <lukas@...ner.de> wrote:
> > Add egress hook for AF_PACKET sockets that have the PACKET_QDISC_BYPASS
> > socket option set to on, which allows packets to escape without being
> > filtered in the egress path.
> >
> > This patch only updates the AF_PACKET path, it does not update
> > dev_direct_xmit() so the XDP infrastructure has a chance to bypass
> > Netfilter.
> 
> Isn't the point of PACKET_QDISC_BYPASS to skip steps like this?

I suppose PACKET_QDISC_BYPASS "was introduced to bypass qdisc,
not to bypass everything."

(The quote is taken from this message by Eric Dumazet:
https://lore.kernel.org/netfilter-devel/a9006cf7-f4ba-81b1-fca1-fd2e97939fdc@gmail.com/
)

Thanks,

Lukas