netdev - Re: Removing skb_orphan() from ip_rcv

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Message-ID: <f69a7930-6e8a-d717-0aa4-a63ea6e7b5e0@mojatatu.com>
Date:   Tue, 25 Jun 2019 07:06:55 -0400
From:   Jamal Hadi Salim <jhs@...atatu.com>
To:     Joe Stringer <joe@...d.net.nz>
Cc:     Eric Dumazet <eric.dumazet@...il.com>,
        Florian Westphal <fw@...len.de>,
        netdev <netdev@...r.kernel.org>,
        john fastabend <john.fastabend@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Lorenz Bauer <lmb@...udflare.com>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Paolo Abeni <pabeni@...hat.com>
Subject: Re: Removing skb_orphan() from ip_rcv_core()

On 2019-06-24 11:26 p.m., Joe Stringer wrote:
[..]
> 
> I haven't got as far as UDP yet, but I didn't see any need for a
> dependency on netfilter.

I'd be curious to see what you did. My experience, even for TCP is
the socket(transparent/tproxy) lookup code (to set skb->sk either
listening or established) is entangled in
CONFIG_NETFILTER_SOMETHING_OR_OTHER. You have to rip it out of
there (in the tproxy tc action into that  code). Only then can you
compile out netfilter.
I didnt bother to rip out code for udp case.
i.e if you needed udp to work with the tc action,
youd have to turn on NF. But that was because we had
no need for udp transparent proxying.
IOW:
There is really no reason, afaik, for tproxy code to only be
accessed if netfilter is compiled in. Not sure i made sense.

cheers,
jamal