Message-ID: <20081020193428.8k6ottvjfc1woscw@webmail8.dotsterhost.com>
Date: Mon, 20 Oct 2008 19:34:28 +0000
From: crispin@crispincowan.com
To: Shaya Potter <spotter@cs.columbia.edu>
Cc: Kentaro Takeda <takedakn@nttdata.co.jp>,
       Stephen Smalley <sds@tycho.nsa.gov>, James Morris <jmorris@namei.org>,
       Chris Wright <chrisw@sous-sol.org>,
       "Serge E. Hallyn" <serue@us.ibm.com>,
       linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org,
       Toshiharu Harada <haradats@nttdata.co.jp>,
       Andrew Morton <akpm@linux-foundation.org>,
       Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
       Al Viro <viro@zeniv.linux.org.uk>, Christoph Hellwig <hch@lst.de>,
       Casey Schaufler <casey@schaufler-ca.com>
Subject: Re: [TOMOYO #11 (linux-next) 01/11] Introduce new LSM hooks where
	vfsmount is available.
References: <20081020073423.024299308@nttdata.co.jp>
	<20081020073643.986810046@nttdata.co.jp> <48FC7938.1070906@cs.columbia.edu>
In-Reply-To: <48FC7938.1070906@cs.columbia.edu>
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Quoting Shaya Potter <spotter@cs.columbia.edu>:
> I know I'm late to the game in this, but as I recently asked about this
> and didn't get an answer, I'll re-ask my approach.
>
> Why can't you do this
>
> in lookup()
>
> - resolve rules (not for single process, but for all processes) for
> said path and tag dentry (seem to already have a hook)
>
> in permission()

Because it doesn't work  
http://kerneltrap.org/mailarchive/linux-fsdevel/2007/6/8/319446

Quick summary: The difference between the pathname model and the label  
model is dynamism. The accessi really is determined by the pathname to  
the file that you used to access the file. If you try to compute  
access based on attributes tagged onto the file, then you have to  
re-compute those attributes every time someone renames a file.

Crispin


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