linux-kernel - Re: [PATCH 5/9] Make use of permissions, returned by kobj

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Date:	Wed, 12 Mar 2008 11:26:19 +0300
From:	Pavel Emelyanov <xemul@...nvz.org>
To:	Greg KH <greg@...ah.com>, serue@...ibm.com
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, menage@...gle.com,
	sukadev@...ibm.com, Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH 5/9] Make use of permissions, returned by kobj_lookup

Greg KH wrote:
> On Tue, Mar 11, 2008 at 12:57:55PM +0300, Pavel Emelyanov wrote:
>> Besides, I've measured some things - the lat_syscall test for open from 
>> lmbench test suite and the nptl perf test. Here are the results:
>>
>>         sec     nosec
>> open    3.0980s  3.0709s
>> nptl    2.7746s  2.7710s
>>
>> So we have 0.88% loss in open and ~0.15% with nptl. I know, this is not that
>> much, but it is noticeable. Besides, this is only two tests, digging deeper
>> may reveal more.
> 
> I think that is in the noise of sampling if you run that test many more
> times.

These numbers are average values of 20 runs of each test. I didn't
provide the measurement accuracy, but the abs(open.sec - open.nosec)
is greater than it.

>> Let alone the fact that simply turning the CONFIG_SECURITY to 'y' puts +8Kb 
>> to the vmlinux...
>>
>> I think, I finally agree with you and Al Viro, that the kobj mapper is 
>> not the right place to put the filtering, but taking the above numbers 
>> into account, can we put the "hooks" into the #else /* CONFIG_SECURITY */
>> versions of security_inode_permission/security_file_permission/etc?
> 
> Ask the security module interface maintainers about this, not me :)

OK :) Thanks for your time, Greg.

So, Serge, since you already have a LSM-based version, maybe you can
change it with the proposed "fix" and send it to LSM maintainers for
review?

> good luck,
> 
> greg k-h
> 

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