netdev - Re: [PATCH nf-next 3/3] netfilter: Introduce egress hook

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Message-ID: <CAF90-WgoteQXB9WQmeT1eOHA3GpPbwPCEvNzwKkN20WqpdHW-A@mail.gmail.com>
Date:   Thu, 23 Apr 2020 16:44:44 +0200
From:   Laura Garcia <nevola@...il.com>
To:     Pablo Neira Ayuso <pablo@...filter.org>,
        Lukas Wunner <lukas@...ner.de>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        Netfilter Development Mailing list 
        <netfilter-devel@...r.kernel.org>, coreteam@...filter.org,
        netdev@...r.kernel.org, Martin Mares <mj@....cz>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Thomas Graf <tgraf@...g.ch>,
        Alexei Starovoitov <ast@...nel.org>,
        David Miller <davem@...emloft.net>
Subject: Re: [PATCH nf-next 3/3] netfilter: Introduce egress hook

On Sun, Mar 15, 2020 at 2:29 PM Pablo Neira Ayuso <pablo@...filter.org> wrote:
>
> Hello Daniel,
>
> On Sat, Mar 14, 2020 at 01:12:02AM +0100, Daniel Borkmann wrote:
> > On 3/13/20 3:55 PM, Pablo Neira Ayuso wrote:
> [...]
> > > We have plans to support for NAT64 and NAT46, this is the right spot
> > > to do this mangling. There is already support for the tunneling
> >
> > But why is existing local-out or post-routing hook _not_ sufficient for
> > NAT64 given it being IP based?
>
> Those hooks are not coming at the end of the IP processing. There is
> very relevant IP code after those hooks that cannot be bypassed such
> as fragmentation, tunneling and neighbour output. Such transformation
> needs to happen after the IP processing, exactly from where Lukas is
> proposing.
>
> [...]
> > > infrastructure in netfilter from ingress, this spot from egress will
> > > allow us to perform the tunneling from here. There is also no way to
> > > drop traffic generated by dhclient, this also allow for filtering such
> > > locally generated traffic. And many more.

Hi,

Any chance to continue with this approach? I'm afraid outbound
af_packets also could not be filtered without this hook.

Thanks.