netdev - Re: [PATCH rfc] netfilter: two xtables matches

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Date:	Wed, 5 Dec 2012 16:50:23 -0500
From:	Willem de Bruijn <willemb@...gle.com>
To:	Jan Engelhardt <jengelh@...i.de>
Cc:	netfilter-devel <netfilter-devel@...r.kernel.org>,
	netdev@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
	David Miller <davem@...emloft.net>,
	Patrick McHardy <kaber@...sh.net>,
	Pablo Neira Ayuso <pablo@...filter.org>
Subject: Re: [PATCH rfc] netfilter: two xtables matches

On Wed, Dec 5, 2012 at 4:45 PM, Willem de Bruijn <willemb@...gle.com> wrote:
> On Wed, Dec 5, 2012 at 3:00 PM, Jan Engelhardt <jengelh@...i.de> wrote:
>> On Wednesday 2012-12-05 20:28, Willem de Bruijn wrote:
>>
>>>Somehow, the first part of this email went missing. Not critical,
>>>but for completeness:
>>>
>>>These two patches each add an xtables match.
>>>
>>>The xt_priority match is a straighforward addition in the style of
>>>xt_mark, adding the option to filter on one more sk_buff field. I
>>>have an immediate application for this. The amount of code (in
>>>kernel + userspace) to add a single check proved quite large.
>>
>> Hm so yeah, can't we just place this in xt_mark.c?
>
> I'm happy to do so, but note that that breaks the custom of
> having one static struct xt_$NAME for each file xt_$NAME.[ch].
>
> It may be reasonable, as the same issue may keep popping up
> as additional sk_buff fields are found useful for filtering. For
> instance, skb->queue_mapping could be used in conjuction with
> network flow classification (ethtool -N).

bad example: queue_mapping is tx only. I thought of rxqueues.

> All the ancillary data
> accessible from BPF likely has some use and could be ported
> to iptables (rxhash, pkt_type, ...).
>
> To avoid rule explosion, I considered an xt_skbuff match rule that
> applies the same mask operation, range and inversion tests, and
> takes a field id to select the sk_buff field to operate on. I think
> the BPF patch is a better long term solution.
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