From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [patch 2/2] VFS: allow filesystem to override mknod capability checks Date: Mon, 24 Sep 2007 13:38:13 +0100 Message-ID: <20070924123813.GB17409@infradead.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: hch@infradead.org, trond.myklebust@fys.uio.no, adilger@clusterfs.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org To: Miklos Szeredi Return-path: Received: from pentafluge.infradead.org ([213.146.154.40]:40217 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756102AbXIXMiQ (ORCPT ); Mon, 24 Sep 2007 08:38:16 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Mon, Sep 24, 2007 at 02:25:54PM +0200, Miklos Szeredi wrote: > From: Miklos Szeredi > > Add a new super block flag, that results in the VFS not checking if > the current process has enough privileges to do an mknod(). > > If this flag is set, all mounts for this super block will have the > "nodev" flag implied. > > This is needed on filesystems, where an unprivileged user may be able > to create a device node, without causing security problems. > > One such example is "mountlo" a loopback mount utility implemented > with fuse and UML, which runs as an unprivileged userspace process. > In this case the user does in fact have the right to create device > nodes within the filesystem image, as long as the user has write > access to the image. Since the filesystem is mounted with "nodev", > adding device nodes is not a security concern. This one looks okay, but I'd prefer to not put it in until we actually have proper non-privilegued mounts.