From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754331AbaHKWLM (ORCPT ); Mon, 11 Aug 2014 18:11:12 -0400 Received: from mga03.intel.com ([143.182.124.21]:50114 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754196AbaHKWLJ (ORCPT ); Mon, 11 Aug 2014 18:11:09 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,844,1400050800"; d="scan'208";a="467602175" Message-ID: <53E93F77.9030305@linux.intel.com> Date: Mon, 11 Aug 2014 15:11:03 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.7.0 MIME-Version: 1.0 To: Amit Shah , linux-kernel@vger.kernel.org CC: Rusty Russell , Virtualization List , kvm list , jgarzik@bitpay.com, duwe@lst.de, Amos Kong , ricardo.neri-calderon@linux.intel.com, tytso@mit.edu, herbert@gondor.apana.org.au Subject: Re: [PATCH 1/1] virtio: rng: add derating factor for use by hwrng core References: <6f2df652355d6e78da846d06e32489b7d9cdfcc2.1407782982.git.amit.shah@redhat.com> In-Reply-To: <6f2df652355d6e78da846d06e32489b7d9cdfcc2.1407782982.git.amit.shah@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/11/2014 11:49 AM, Amit Shah wrote: > The khwrngd thread is started when a hwrng device of sufficient > quality is registered. The virtio-rng device is backed by the > hypervisor, and we trust the hypervisor to provide real entropy. A > malicious hypervisor is a scenario that's ruled out, so we are certain > the quality of randomness we receive is perfectly trustworthy. Hence, > we use 100% for the factor, indicating maximum confidence in the source. > > Signed-off-by: Amit Shah It isn't "ruled out", it is just irrelevant: if the hypervisor is malicious, the quality of your random number source is the least of your problems. -hpa