Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755988AbZCZMn7 (ORCPT ); Thu, 26 Mar 2009 08:43:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751175AbZCZMns (ORCPT ); Thu, 26 Mar 2009 08:43:48 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:58530 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751949AbZCZMnr (ORCPT ); Thu, 26 Mar 2009 08:43:47 -0400 Date: Thu, 26 Mar 2009 13:43:38 +0100 From: Pavel Machek To: Miklos Szeredi Cc: serue@us.ibm.com, bfields@fieldses.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, ebiederm@xmission.com, linux-fsdevel@vger.kernel.org Subject: Re: unprivileged mounts vs. rmdir (was: VFS, NFS security bug? ...) Message-ID: <20090326124338.GA1466@ucw.cz> References: <20090311232356.GP13540@fieldses.org> <20090312161047.GA15209@us.ibm.com> <517f3f820903121321sf6d2014q8165b925d5d44db7@mail.gmail.com> <20090313175848.GB27891@fieldses.org> <20090316163611.GB10959@fieldses.org> <20090316170433.GA2996@us.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1632 Lines: 40 On Mon 2009-03-23 14:21:30, Miklos Szeredi wrote: > [CCs trimmed] > > On Mon, 16 Mar 2009, Serge E. Hallyn wrote: > > Quoting J. Bruce Fields (bfields@fieldses.org): > > > special privilege, so don't consult filesystem permissions (do I have > > > that right? What happened to the attempt to allow ordinary users to > > > mount?). > > > > Well, they keep getting stalled because we don't have a good answer for > > what to do about the fact that an unprivileged user can make trees > > undeletable by pinning them with mounts. (Miklos and Eric cc'd in case > > I didn't explain that well enough). > > That's correct. > > The best answer I can come up with is to allow rmdir/unlink to > automatically umount trees from their respective dentries. Obviously > this can't be done for regular (privileged) mounts, which must keep > returning EBUSY in such situations. > > But for unprivileged mounts I can't see any fundamental issue with > such an approach. > > Does anyone see a problem with this? Is there a better solution? Well... traditionally if you have an open file or cwd inside mounted tree... that blocks unmount, right? What will you do with processes that have open (deleted) files inside the mount? What about cwd? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/