linux-kernel - Re: [AppArmor 39/45] AppArmor: Profile loading and manipulation, pathname matching

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Message-ID: <467193FD.3010803@hawkeye.stone.uk.eu.org>
Date:	Thu, 14 Jun 2007 20:16:13 +0100
From:	Jack Stone <jack@...keye.stone.uk.eu.org>
To:	david@...g.hm
CC:	greg@...ah.com, agruen@...e.de, sds@...ho.nsa.gov,
	jjohansen@...e.de, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, pavel@....cz
Subject: Re: [AppArmor 39/45] AppArmor: Profile loading and manipulation,
 pathname matching

david@...g.hm wrote:
> On Sun, 10 Jun 2007, Pavel Machek wrote:
>> But you have that regex in _user_ space, in a place where policy
>> is loaded into kernel.
> 
> then the kernel is going to have to call out to userspace every time a
> file is created or renamed and the policy is going to be enforced
> incorrectly until userspace finished labeling/relabeling whatever is
> moved. building this sort of race condigion for security into the kernel
> is highly questionable at best.
> 
>> AA has regex parser in _kernel_ space, which is very wrong.
> 
> see Linus' rants about why it's not automaticaly the best thing to move
> functionality into userspace.
> 
> remember that the files covered by an AA policy can change as files are
> renamed. this isn't the case with SELinux so it doesn't have this sort
> of problem.

How about using the inotify interface on / to watch for file changes and
 updating the SELinux policies on the fly. This could be done from a
userspace daemon and should require minimal SELinux changes.

The only possible problems I can see are the (hopefully) small gap
between the file change and updating the policy and the performance
problems of watching the whole system for changes.

Just my $0.02.

Jack
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