From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264720AbUEEQgv (ORCPT ); Wed, 5 May 2004 12:36:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264722AbUEEQgv (ORCPT ); Wed, 5 May 2004 12:36:51 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:14810 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S264720AbUEEQgu (ORCPT ); Wed, 5 May 2004 12:36:50 -0400 Date: Wed, 5 May 2004 17:36:50 +0100 From: viro@parcelfarce.linux.theplanet.co.uk To: Nikita Danilov Cc: linux kernel mailing list Subject: Re: [PATCH-RFC] code for raceless /sys/fs/foofs/* Message-ID: <20040505163650.GO17014@parcelfarce.linux.theplanet.co.uk> References: <16536.61900.721224.492325@laputa.namesys.com> <20040505162802.GN17014@parcelfarce.linux.theplanet.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040505162802.GN17014@parcelfarce.linux.theplanet.co.uk> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 05, 2004 at 05:28:03PM +0100, viro@parcelfarce.linux.theplanet.co.uk wrote: > On Wed, May 05, 2004 at 05:53:16PM +0400, Nikita Danilov wrote: > > Hello, > > > > attached patch adds code necessary to safely export per-super-block > > information in /sys/fs and /proc/fs. > > > > Common problem with exporting file system information in procfs or sysfs > > is a race between method that inputs/outputs data and concurrent umount > > of the super-block involved. > > Aside of the implementation questions (will comment later), there is an > interface problem here. We end up allowing anyone who has sysfs mounted > (in chroot jail, in limited namespace, etc.) to pin down _any_ reiser4 > superblock, whether they have the thing itself mounted or not. [sorry about truncated message - -ENOCOFFEE hits] We also allow anyone with sysfs mounted to see which filesystems are currently mounted on the box - again, regardless of being able to see them in the chroot jail/restricted namespace/etc. It can easily become an issue in setups where such information is sensitive.