From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Subject: Re: [PATCH] audit: fix size of netlink messages
Date: Mon, 10 Jun 2013 10:50:30 +0200
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To: Thomas Graf <tgraf@suug.ch>
Cc: linux-audit@redhat.com, viro@zeniv.linux.org.uk
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Le 09/06/2013 15:29, Thomas Graf a =E9crit :
> On 06/07/13 at 06:24pm, Nicolas Dichtel wrote:
>> Put Thomas in CC.
>>
>> Le 07/06/2013 17:43, Eric Paris a =E9crit :
>>> On Fri, 2013-06-07 at 17:25 +0200, Nicolas Dichtel wrote:
>>>
>>> NAK.
>>>
>>> I tried this once before and as I recal userspace actually expected the
>>> stoopidity of being unaligned and broke   :-(
>> On which userspace tools do you think?
>>
>> For example, in the libnl, the function which tries to get the next
>> netlink message expects this alignment:
>
> You should only align the end of the Netlink message if you
> append another Netlink message after it. There is no point
> in aligning it if no message follows in the same buffer.
>
> A receiver should never enforce alignment for the last message.
> Some do and this is causing a lot of pain. An example is the
> Open vSwitch implementation which stricly enforces alignment of
> nlmsg_len which makes attempts to implement zerocopy for the
> upcall more difficult than it should be.
>
Ok, thank you for the clarification.