From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754700AbXGBTAw (ORCPT ); Mon, 2 Jul 2007 15:00:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753260AbXGBTAp (ORCPT ); Mon, 2 Jul 2007 15:00:45 -0400 Received: from straum.hexapodia.org ([64.81.70.185]:35085 "EHLO straum.hexapodia.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753187AbXGBTAo (ORCPT ); Mon, 2 Jul 2007 15:00:44 -0400 Date: Mon, 2 Jul 2007 12:00:43 -0700 From: Andy Isaacson To: Kyle Moffett Cc: Davide Libenzi , Linux Kernel Mailing List , Rik van Riel Subject: Re: [patch 0/4] MAP_NOZERO v2 - VM_NOZERO/MAP_NOZERO early summer madness Message-ID: <20070702190043.GN9157@hexapodia.org> References: <20070629193954.GL9157@hexapodia.org> <8F40BE4A-BD38-4C3F-B77D-35661E84C553@mac.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.2i X-PGP-Fingerprint: 1914 0645 FD53 C18E EEEF C402 4A69 B1F3 68D2 A63F X-PGP-Key-URL: http://web.hexapodia.org/~adi/gpg.txt X-Domestic-Surveillance: money launder bomb tax evasion Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jun 30, 2007 at 08:21:52PM -0400, Kyle Moffett wrote: > That's why you'd need to call an LSM hook to get a unique identifier, > as the LSM would actually need to allocate identifiers for > equivalence classes. Secondly, processes may change labels as they > run, so you couldn't just call it once and cache the result, you > would need to call it for every freed page (or every re-use of a page). Davide's patch adds a owner_uid field to mm_struct. Assuming that turns into a "mm security equivalence class identifier", the LSM can simply update it when a label-change-event occurs. No need to call out to (potentially heavyweight!) LSM code in page allocation critical paths. I'm a bit concerned that tracking the equivalence classes will get expensive. I think you can end up with quadratic explosion in the worst case (every user using every permutation of LSM bits). -andy