From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Subject: Re: [PATCH 5/7] efi: Get the secure boot status [ver #3] Date: Fri, 25 Nov 2016 12:35:03 +0000 Message-ID: <17565.1480077303@warthog.procyon.org.uk> References: <147990561294.7576.6464430479448167484.stgit@warthog.procyon.org.uk> <147990565051.7576.9673287945782426886.stgit@warthog.procyon.org.uk> <1480016487.2444.18.camel@HansenPartnership.com> <15173.1480066220@warthog.procyon.org.uk> <16661.1480075392@warthog.procyon.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-ID: <17564.1480077303.1@warthog.procyon.org.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Ard Biesheuvel Cc: James Bottomley , "linux-efi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , dhowells@redhat.com, linux-security-module , Lukas Wunner , keyrings@vger.kernel.org, "linux-arm-kernel@lists.infradead.org" List-Id: linux-efi@vger.kernel.org Ard Biesheuvel wrote: > Yes. In pre-2.6, DeployedMode is not a reserved name, and so it may be > possible for someone to slip in a DeployedMode=0 on a secure boot > enabled system to trick the kernel into thinking lockdown should be > disabled. How does one get the version number? Unfortunately, searching the document for 'version' doesn't help as every page has that in the footer:-/ > > + if (val == 1) > > + return 0; > > I think the logic is the wrong way around here. Secure Boot is enabled > if SecureBoot=1 and SetupMode=0, unless DeployedMode=0. So you should > return 0 here if val == 0, but only when running on 2.6 or later. Good point. David From mboxrd@z Thu Jan 1 00:00:00 1970 From: dhowells@redhat.com (David Howells) Date: Fri, 25 Nov 2016 12:35:03 +0000 Subject: [PATCH 5/7] efi: Get the secure boot status [ver #3] In-Reply-To: References: <147990561294.7576.6464430479448167484.stgit@warthog.procyon.org.uk> <147990565051.7576.9673287945782426886.stgit@warthog.procyon.org.uk> <1480016487.2444.18.camel@HansenPartnership.com> <15173.1480066220@warthog.procyon.org.uk> <16661.1480075392@warthog.procyon.org.uk> Message-ID: <17565.1480077303@warthog.procyon.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Ard Biesheuvel wrote: > Yes. In pre-2.6, DeployedMode is not a reserved name, and so it may be > possible for someone to slip in a DeployedMode=0 on a secure boot > enabled system to trick the kernel into thinking lockdown should be > disabled. How does one get the version number? Unfortunately, searching the document for 'version' doesn't help as every page has that in the footer:-/ > > + if (val == 1) > > + return 0; > > I think the logic is the wrong way around here. Secure Boot is enabled > if SecureBoot=1 and SetupMode=0, unless DeployedMode=0. So you should > return 0 here if val == 0, but only when running on 2.6 or later. Good point. David From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754491AbcKYMpV (ORCPT ); Fri, 25 Nov 2016 07:45:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:55890 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754453AbcKYMpD (ORCPT ); Fri, 25 Nov 2016 07:45:03 -0500 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <147990561294.7576.6464430479448167484.stgit@warthog.procyon.org.uk> <147990565051.7576.9673287945782426886.stgit@warthog.procyon.org.uk> <1480016487.2444.18.camel@HansenPartnership.com> <15173.1480066220@warthog.procyon.org.uk> <16661.1480075392@warthog.procyon.org.uk> To: Ard Biesheuvel Cc: dhowells@redhat.com, James Bottomley , "linux-efi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , linux-security-module , Lukas Wunner , keyrings@vger.kernel.org, "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH 5/7] efi: Get the secure boot status [ver #3] MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <17564.1480077303.1@warthog.procyon.org.uk> Date: Fri, 25 Nov 2016 12:35:03 +0000 Message-ID: <17565.1480077303@warthog.procyon.org.uk> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Fri, 25 Nov 2016 12:35:06 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ard Biesheuvel wrote: > Yes. In pre-2.6, DeployedMode is not a reserved name, and so it may be > possible for someone to slip in a DeployedMode=0 on a secure boot > enabled system to trick the kernel into thinking lockdown should be > disabled. How does one get the version number? Unfortunately, searching the document for 'version' doesn't help as every page has that in the footer:-/ > > + if (val == 1) > > + return 0; > > I think the logic is the wrong way around here. Secure Boot is enabled > if SecureBoot=1 and SetupMode=0, unless DeployedMode=0. So you should > return 0 here if val == 0, but only when running on 2.6 or later. Good point. David