From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [patch 7/9] unprivileged mounts: allow unprivileged fuse mounts Date: Tue, 8 Jan 2008 23:58:20 +0100 Message-ID: <20080108225820.GA9735@elf.ucw.cz> References: <20080108113502.184459371@szeredi.hu> <20080108113630.861045063@szeredi.hu> <20080108214625.GE5050@ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: akpm@linux-foundation.org, hch@infradead.org, serue@us.ibm.com, viro@ftp.linux.org.uk, ebiederm@xmission.com, kzak@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, containers@lists.osdl.org, util-linux-ng@vger.kernel.org To: Miklos Szeredi Return-path: Received: from gprs189-60.eurotel.cz ([160.218.189.60]:55820 "EHLO amd.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752075AbYAHW6P (ORCPT ); Tue, 8 Jan 2008 17:58:15 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue 2008-01-08 23:42:20, Miklos Szeredi wrote: > > On Tue 2008-01-08 12:35:09, Miklos Szeredi wrote: > > > From: Miklos Szeredi > > > > > > Use FS_SAFE for "fuse" fs type, but not for "fuseblk". > > > > > > FUSE was designed from the beginning to be safe for unprivileged users. This > > > has also been verified in practice over many years. In addition unprivileged > > > > Eh? So 'kill -9 no longer works' and 'suspend no longer works' is not > > considered important enough to even mention? > > No. Because in practice they don't seem to matter. Also because > there's no way in which fuse could be done differently to address > these issues. > > The 'kill -9' thing is basically due to VFS level locking not being > interruptible. It could be changed, but I'm not sure it's worth it. Well, I believe it should be changed. "You need to mount /sys, then echo X to Y before kill -9 works" does not look nice... I agree it is not easy. > > 'updatedb no longer works' is not a problem? > > I haven't seen any problems with updatedb, and haven't had any bug > reports about it either. Ok, I don't know much about FUSE. In current version, if user creates infinite maze and mounts it under ~, updatedb just does not enter it? > AFAIR there were two security vulnerabilities in fuse's history, one > of them an information leak in the kernel module, and the other one an > mtab corruption issue in the fusermount utility. I don't think this > is such a bad track record. Not bad indeed. But I'd consider 'kill -9 not working' to be DoS vulnerability... and I'm woried about problems fuse + user mounts expose in other parts of system. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html