From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756614AbYERLDU (ORCPT ); Sun, 18 May 2008 07:03:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751779AbYERLDM (ORCPT ); Sun, 18 May 2008 07:03:12 -0400 Received: from mail.gmx.net ([213.165.64.20]:52218 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1750951AbYERLDL (ORCPT ); Sun, 18 May 2008 07:03:11 -0400 X-Authenticated: #428038 X-Provags-ID: V01U2FsdGVkX1+y0qdnJRSySiEG+ajnf6L5N5X7bPuX1LwAafcaTQ Kw7Gxx1iFZAR+W Date: Sun, 18 May 2008 13:03:06 +0200 From: Matthias Andree To: linux-kernel@vger.kernel.org Subject: Re: [PATCH] drivers/net: remove network drivers' last few uses of IRQF_SAMPLE_RANDOM Message-ID: <20080518110306.GD9845@merlin.emma.line.org> Mail-Followup-To: linux-kernel@vger.kernel.org References: <20080515142154.0595e475@core> <36D9DB17C6DE9E40B059440DB8D95F52052D71BB@orsmsx418.amr.corp.intel.com> <20080515215517.GI1936@cs181133002.pp.htv.fi> <1211070968.18026.113.camel@calx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1211070968.18026.113.camel@calx> X-PGP-Key: http://home.pages.de/~mandree/keys/GPGKEY.asc User-Agent: Mutt/1.5.18 (2008-05-17) X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 17 May 2008, Matt Mackall wrote: > It certainly makes sense to sample network timing noise. It often does > not make sense to assume that there's any entropy in those timing > samples. For instance: > > - our clock resolution may be low enough that an attacker can guess our > samples (ie it's simply HZ, very common in embedded land) > - the bus involved (ISA, peripheral bus, even slow PCI) may have the > same issue > - it may be heavily correlated with some other measurement (ie network > vs disk samples on file servers) > > We currently assume that IRQF_SAMPLE_RANDOM means 'this is a completely > trusted unobservable entropy source' which is obviously wrong for > network devices but is right for some other classes of device. Without looking at code, should your summary should include "independent of (as in non-correlated with) other sources" according to your argument? -- Matthias Andree