Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760580AbXIYRFX (ORCPT ); Tue, 25 Sep 2007 13:05:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751333AbXIYRFJ (ORCPT ); Tue, 25 Sep 2007 13:05:09 -0400 Received: from sovereign.computergmbh.de ([85.214.69.204]:39133 "EHLO sovereign.computergmbh.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751464AbXIYRFH (ORCPT ); Tue, 25 Sep 2007 13:05:07 -0400 Date: Tue, 25 Sep 2007 19:05:06 +0200 (CEST) From: Jan Engelhardt To: Miloslav Semler cc: serge@hallyn.com, davidsen@tmr.com, philipp@marek.priv.at, 7eggert@gmx.de, alan@lxorguk.ukuu.org.uk, linux-kernel@vger.kernel.org Subject: Re: Chroot bug In-Reply-To: <46F93EAF.20706@prepere.com> Message-ID: 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> <46F92C17.3060405@davidnewall.com> <46F9351D.8020906@prepere.com> <46F93EAF.20706@prepere.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1170 Lines: 34 On Sep 25 2007 19:00, Miloslav Semler wrote: >> > This does not help. Let's try: >> > chroot somewhere >> > mkdir foo >> > fd = open / >> > chroot foo >> > >> >> ('fd' implicitly closed and chdir to /foo) >> > Really? Try it. I am sure, that this works. You can create directory in chroot > and break chroot by this. fd is not closed, because linux doesn't close > descriptors by chroot syscall. this can be done every time if you have > CAP_SYS_CHROOT. In case you have not followed my earlier email, I'll repost: |>> So what? Just do this: chdir into the root after chroot. |> |> I don't think so. His exploit just got me all the way out of a |> chroot within a chroot within a chroot, inclusive of lots of |> chdirs. |> | |Close all fds that point to directories outside the root ;-) Perhaps that was formulated a bit sloppy. It of course means "On chroot(2), implicitly close all FDs that point outside." - 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/