From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751824Ab3LJAfq (ORCPT ); Mon, 9 Dec 2013 19:35:46 -0500 Received: from terminus.zytor.com ([198.137.202.10]:38844 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751726Ab3LJAfl (ORCPT ); Mon, 9 Dec 2013 19:35:41 -0500 Message-ID: <52A66190.9060907@zytor.com> Date: Mon, 09 Dec 2013 16:34:24 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Kees Cook , linux-kernel@vger.kernel.org CC: Rik van Riel , Andrew Morton , Matthew Garrett , Vivek Goyal , Rob Landley , Eric Biederman , Ingo Molnar , Peter Zijlstra , Mel Gorman , linux-doc@vger.kernel.org, kexec@lists.infradead.org Subject: Re: [PATCH v2] kexec: add sysctl to disable kexec References: <20131210001620.GA7938@www.outflux.net> In-Reply-To: <20131210001620.GA7938@www.outflux.net> X-Enigmail-Version: 1.6 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 12/09/2013 04:16 PM, Kees Cook wrote: > For general-purpose (i.e. distro) kernel builds it makes sense to build with > CONFIG_KEXEC to allow end users to choose what kind of things they want to do > with kexec. However, in the face of trying to lock down a system with such > a kernel, there needs to be a way to disable kexec (much like module loading > can be disabled). Without this, it is too easy for the root user to modify > kernel memory even when CONFIG_STRICT_DEVMEM and modules_disabled are set. > > Signed-off-by: Kees Cook > Acked-by: Rik van Riel So the logic is to load a crashkernel and then lock down the machine before services, networking etc. are enabled? -hpa