Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753668Ab3JEXWT (ORCPT ); Sat, 5 Oct 2013 19:22:19 -0400 Received: from mail-vc0-f178.google.com ([209.85.220.178]:61111 "EHLO mail-vc0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752473Ab3JEXWP (ORCPT ); Sat, 5 Oct 2013 19:22:15 -0400 MIME-Version: 1.0 In-Reply-To: References: <87li281wx6.fsf_-_@xmission.com> <1381014462.1974.162@driftwood> Date: Sat, 5 Oct 2013 16:22:15 -0700 X-Google-Sender-Auth: KPLvIdeZz3S5VEZ9ex6bcHo6KTQ Message-ID: Subject: Re: [RFC][PATCH 0/3] vfs: Detach mounts on unlink. From: Linus Torvalds To: Rob Landley Cc: "Eric W. Biederman" , Miklos Szeredi , "Serge E. Hallyn" , Al Viro , Linux-Fsdevel , Kernel Mailing List , Andy Lutomirski Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 797 Lines: 23 On Sat, Oct 5, 2013 at 4:17 PM, Linus Torvalds wrote: > > So learn this pattern: every time you use chroot, add a simple > > chdir("/"); > > immediately after the chroot call. .. btw, also make sure that you close all non-essential file descriptors. Having any open directory file descriptors pointing to outside the chroot is also a classic escape. Even then, escaping chroot is usually fairly easy. Making a escape-proof chroot is really quite hard. Basically impossible if you allow root. Linus -- 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/