Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262062AbVEKVYP (ORCPT ); Wed, 11 May 2005 17:24:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262061AbVEKVYP (ORCPT ); Wed, 11 May 2005 17:24:15 -0400 Received: from mail.shareable.org ([81.29.64.88]:49872 "EHLO mail.shareable.org") by vger.kernel.org with ESMTP id S262056AbVEKVYH (ORCPT ); Wed, 11 May 2005 17:24:07 -0400 Date: Wed, 11 May 2005 22:23:43 +0100 From: Jamie Lokier To: Bodo Eggert <7eggert@gmx.de> Cc: Miklos Szeredi , ericvh@gmail.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, smfrench@austin.rr.com, hch@infradead.org Subject: Re: [RCF] [PATCH] unprivileged mount/umount Message-ID: <20050511212343.GC5093@mail.shareable.org> References: <406SQ-5P9-5@gated-at.bofh.it> <40rNB-6p8-3@gated-at.bofh.it> <40t37-7ol-5@gated-at.bofh.it> <42VeB-8hG-3@gated-at.bofh.it> <42WNo-1eJ-17@gated-at.bofh.it> <20050511170700.GC2141@mail.shareable.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1750 Lines: 52 Bodo Eggert wrote: > > > > How about a new clone option "CLONE_NOSUID"? > > > > > > IMO, the clone call ist the wrong place to create namespaces. It > > > should be deprecated by a mkdir/chdir-like interface. > > > > And the mkdir/chdir interface already exists, see "cd /proc/NNN/root". > > If you want persistent namespaces, this will be a PITA (I don't want a > keep-the-namespace-open-daemon), and if you don't, it will be racy > (user a logs in, while his second/nth login expires). > > Keeping a list of named namespaces in kernel can be made cheap and secure. Still easy. To keep persistent named namespaces in /var/namespaces, thus: # Just once please! mount -t tmpfs none /var/namespaces # Make a named namespace. NSNAME='fred' mkdir /var/namespaces/$NSNAME run_in_new_namespace mount -t bind / /var/namespaces/$NSNAME # Make a named namespace for the _original_ namespace. mkdir /var/namespaces/initial mount -t bind / /var/namespaces/initial # Access the namespace. ls /var/namespaces/fred # Enter the namespace. chroot /var/namespaces/fred # Delete a named namespace. NSNAME='fred' umount /var/namespaces/$NSNAME rmdir /var/namespaces/$NSNAME Some of the above will fail due to security checks in fs/namespace.c, where it tests against current->namespace. Without those checks, which seem to have no purpose _other_ than preventing the above usage, I think the above would all work. -- Jamie - 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/