From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 0/2] Shared flags Date: Tue, 11 Nov 2008 06:14:29 -0500 Message-ID: <20081111111428.GA18228@infradead.org> References: <49183DF9.9010003@etersoft.ru> <20081111085211.GB2323@infradead.org> <20081111100940.GA8968@shareable.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20081111100940.GA8968@shareable.org> Sender: linux-fsdevel-owner@vger.kernel.org To: Jamie Lokier Cc: Christoph Hellwig , Pavel Shilovsky , linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org List-Id: linux-api@vger.kernel.org On Tue, Nov 11, 2008 at 10:09:40AM +0000, Jamie Lokier wrote: > Christoph Hellwig wrote: > > On Mon, Nov 10, 2008 at 04:58:17PM +0300, Pavel Shilovsky wrote: > > > #define O_DENYREAD 004000000 /* Do not permit read access */ > > > #define O_DENYWRITE 010000000 /* Do not permit write access */ > > > #define O_DENYDELETE 020000000 /* Do not permit delete or rename operations*/ > > > (2) you also need to enforce these semantics in the VFS for local > > filesystems > > > > Now if (2) doesn't cause too much overhead I would say it's fine, if not > > I would rather avoid it. > > On the face of it, they look like they have similar denial-of-service > potential as mandatory locks. For example, a root process cleaning > out /tmp gets stuck because a user process has O_DENYDELETE set. Oh, that's the part I forgot to mention in the previous mail, all of these option of course can only be root only, everything else would be - as you say - a complete security nightmare.