Message-ID: <46FA3EE8.4080707@davidnewall.com>
Date: Wed, 26 Sep 2007 20:43:44 +0930
From: David Newall <david@davidnewall.com>
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To: Olivier Galibert <galibert@pobox.com>, Kyle Moffett <mrmacman_g4@mac.com>,
       Adrian Bunk <bunk@kernel.org>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
       "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
References: <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> <20070926005551.GS6800@stusta.de> <F23AFB4D-E989-4F06-A256-4D12D852DFA2@mac.com> <46FA341A.80706@davidnewall.com> <20070926104500.GA4354@dspnet.fr.eu.org>
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Olivier Galibert wrote:
> chroot does not allow you to walk out if you're in.

You're mistaken.  Or more properly, further use of chroot lets you walk 
out.  This really has been said before, and before, and before.

    chroot("subtree");   // enter chroot
    chdir("/");    // now at subtree
    chroot("/tmp");   // now outside of chroot


BSD redefined chroot so that the working directory is set to the new 
root on subsequent uses of chroot; that's how they solved the bug.
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