Date: Wed, 26 Sep 2007 11:47:29 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: David Newall <david@davidnewall.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>, Bill Davidsen <davidsen@tmr.com>,
       Philipp Marek <philipp@marek.priv.at>, 7eggert@gmx.de,
       majkls <majkls@prepere.com>, bunk@fs.tum.de,
       linux-kernel@vger.kernel.org
Subject: Re: Chroot bug
Message-ID: <20070926114729.3b9d1fb4@the-village.bc.nu>
In-Reply-To: <46FA334F.7030802@davidnewall.com>
References: <56705.193.171.152.61.1190289559.squirrel@webmail.marek.priv.at>
	<46F29A9A.4070806@davidnewall.com>
	<200709201817.17282@x5>
	<46F2B59F.8090709@davidnewall.com>
	<46F2DDD0.3030500@tmr.com>
	<46F380E4.4040606@davidnewall.com>
	<20070924213215.GA32716@vino.hallyn.com>
	<46F83474.5040503@davidnewall.com>
	<20070924230008.GA3160@vino.hallyn.com>
	<46F8BC8A.7080006@davidnewall.com>
	<20070925114947.GA9721@vino.hallyn.com>
	<46F91417.9050600@davidnewall.com>
	<46F924E3.50205@davidnewall.com>
	<20070925163040.12a3c2f8@the-village.bc.nu>
	<46F92AAB.1060903@davidnewall.com>
	<20070925164806.4cadc6a5@the-village.bc.nu>
	<46F99EDE.70905@davidnewall.com>
	<20070926011847.49bbb9a2@the-village.bc.nu>
	<46FA334F.7030802@davidnewall.com>
Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street,
 Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a
 Lloegr o'r rhif cofrestru 3798903
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 839
Lines: 23

> > The dot-dot entry in the root directory is interpreted to mean the 
> > root directory itself. Thus, dot-dot cannot be used to access files 
> > outside the subtree rooted at the root directory.

Which is behaviour chroot preserves properly.

The specification says explicitly

	"The process working directory is unaffected by chroot()."


chroot is not and never has been a security tool. People have built
things based upon the properties of chroot but extended (BSD jails, Linux
vserver) but they are quite different.

You could probably write yourself an LSM module to do this too

Alan
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/