netdev - Re: [PATCH 4/4] netfilter: Fix format string of nfnetlink

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Message-ID: <5526F5F6.4010907@nod.at>
Date:	Thu, 09 Apr 2015 23:58:14 +0200
From:	Richard Weinberger <richard@....at>
To:	Pablo Neira Ayuso <pablo@...filter.org>
CC:	netdev@...r.kernel.org, linux-wireless@...r.kernel.org,
	coreteam@...filter.org, netfilter-devel@...r.kernel.org,
	linux-kernel@...r.kernel.org, sameo@...ux.intel.com,
	aloisio.almeida@...nbossa.org, lauro.venancio@...nbossa.org,
	davem@...emloft.net, kadlec@...ckhole.kfki.hu, kaber@...sh.net
Subject: Re: [PATCH 4/4] netfilter: Fix format string of nfnetlink_queue proc
 file

Am 16.03.2015 um 14:11 schrieb Pablo Neira Ayuso:
> On Fri, Mar 13, 2015 at 03:22:07PM +0100, Richard Weinberger wrote:
>> Am 13.03.2015 um 14:53 schrieb Pablo Neira Ayuso:
>>>> You mean statistics via netlink attributes? I can add that!
>>>
>>> Add a new NFQNL_CFG_CMD_STATS command to request the statistics. If
>>> NLM_F_DUMP is set, then we'll basically provide the full list of
>>> instances. Otherwise, in case you want to retrieve stats for a
>>> specific netlink socket, you can use the netlink portID as index.
>>> And you'll have to add attributes for this new command, yes.
>>
>> This was my plan. Thanks for the pointer!
> 
> It would be great if you can contribute this new interface.

FYI, it is still on my TODO.
I fear I won't find the time to do a patch for the upcoming merge window
and it has to wait for v4.2.

>>>> But I think we should also fix the format string of the proc file
>>>> as the fix is easy and non-intrusive.
>>>
>>> Unfortunately we don't know how many people are relying on that
>>> output, I prefer to remain conservative and provide a proper netlink
>>> interface for this.
>>
>> I understand your concerns but an application which is able to parse positive
>> and negative numbers can also parse pure positives.
>> Just made a small test application, glibc's %d in sscanf() can also deal with UINT_MAX.
>> And I don't expect that applications to check whether the returned values from
>> /proc/net/netfilter/nfnetlink_queue are between INT_MIN and INT_MAX.
>>
>> That said, I'd have assumed that an user would report negative values as plain kernel bug.
> 
> Makes sense, please fix net/netfilter/nfnetlink_log.c too.

Patches sent! :)

Thanks,
//richard
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