linux-kernel - Re: Out of tree module using LSM

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Message-ID: <20071208105018.GA4381@ucw.cz>
Date:	Sat, 8 Dec 2007 10:50:19 +0000
From:	Pavel Machek <pavel@....cz>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Christoph Hellwig <hch@...radead.org>,
	Jan Engelhardt <jengelh@...putergmbh.de>,
	Greg KH <greg@...ah.com>,
	Jon Masters <jonathan@...masters.org>, Valdis.Kletnieks@...edu,
	Al Viro <viro@....linux.org.uk>,
	Casey Schaufler <casey@...aufler-ca.com>,
	"Tvrtko A. Ursulin" <tvrtko.ursulin@...hos.com>,
	linux-kernel@...r.kernel.org
Subject: Re: Out of tree module using LSM

On Thu 2007-11-29 23:58:44, Andi Kleen wrote:
> Alan Cox <alan@...rguk.ukuu.org.uk> writes:
> >
> > The simple case is
> > 	open
> > 	write cathedral and bazaar in some order
> > 	close
> > 	<trap close -> process -> label eric_t>
> >
> > 	open (eric_t) - SELinux "no"
> >
> >
> > Anyone smart will then write it out of order and keep the file open, or
> 
> That would assume Eric already has a program running on your system
> optimized to inject his works in a obfuscated way. And if he has a
> program running he can do nearly everything already.  You already
> lost the game.
> 
> The normal case Tvrtko et.al. are trying to handle would be more the
> work getting downloaded from somewhere or read from a usb stick using
> normal programs like web browsers or file managers who don't do any
> out of order writing tricks and other obfuscation.

Fortunately normal programs tend to be dynamically linked, so
LD_PRELOAD is fine to handle them. And we know we can't handle nasty
programs. Seems like LD_PRELOAD is the way to go.

							Pavel

-- 
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