netdev - Re: [PATCH] net: Fix security_socket

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Date:	Mon, 25 Jul 2011 10:00:29 -0700
From:	Casey Schaufler <casey@...aufler-ca.com>
To:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
CC:	anton@...ba.org, mjt@....msk.ru, davem@...emloft.net,
	netdev@...r.kernel.org, linux-security-module@...r.kernel.org,
	Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: [PATCH] net: Fix security_socket_sendmsg() bypass problem.

On 7/25/2011 9:43 AM, Tetsuo Handa wrote:
> Casey Schaufler wrote:
>>> OK. Then, the question is how to reduce performance loss by redundant
>>> security_socket_sendmsg() calls.
>> Not to be splitting hairs, but if the packets are headed to
>> different destinations the calls to security_socket_sendmsg()
>> are not redundant, they are necessary and appropriate. What
>> you have with sendmmsg() is an optimization that sacrifices
>> correctness for performance.
> Excuse me, but this thread is not trying to remove necessary and appropriate
> security_socket_sendmsg() calls. Linux 3.0 was released without necessary and
> appropriate security_socket_sendmsg() calls, and I'm trying to correct it (via
> msg11504.html or msg11510.html) for Linux 3.0.x stable release.

I understand. Sorry if I did a poor job of jumping into
the thread.

>> I fear that you are going to find that the work you have
>> to do to reduce the number of calls is going to outweigh
>> the benefits of your optimization, as has been pointed out
>> earlier.
> I fear it too. Unless many dozens (maybe some hundreds) of packets are sent by
> sendmmsg(), msg11504.html might show better performance than msg11510.html .
> But I don't have a machine to benchmark.

Is there some chance that the original authors could step up
to help with the benchmarking effort on this repair? Having been
on the end where I introduced problems more than once, I have a
good understanding of the principle "you broke it, you bought it".

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