netdev - Re: [PATCH net-next] bridge: ebtables: Avoid resetting limit rule state

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Date:   Fri, 8 Dec 2017 06:46:06 +0100
From:   Linus Lüssing <linus.luessing@...3.blue>
To:     Pablo Neira Ayuso <pablo@...filter.org>
Cc:     netfilter-devel@...r.kernel.org,
        Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
        Florian Westphal <fw@...len.de>,
        Stephen Hemminger <stephen@...workplumber.org>,
        "David S . Miller" <davem@...emloft.net>, coreteam@...filter.org,
        bridge@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] bridge: ebtables: Avoid resetting limit rule
 state

On Thu, Dec 07, 2017 at 01:26:19AM +0100, Pablo Neira Ayuso wrote:
> > I also had a quick look at a 4.15-rc1 kernel in a VM now. I still
> > end up in ebt_limit_mt_check() with the variables being reset
> > when editing the table somewhere.
> 
> My question is if your fix would work with 4.15-rc1.

You are absoluetly right, it's not working anymore since the
commit you mentioned initially :-(
("xtables: extend matches and targets with .usersize").
info->prev is always 0 since exactly this commit.

That means, trying tricks in ebt_limit_mt_check() is too
late now, the old values are already overwritten? (or is there
some commit scheme which installs the ebt_limit_info provided
by ebt_limit_check() some time after its call?)

Extending the usersize to include info->prev would probably be too
hackish/ugly, right?