From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:58062 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750962AbeEAWVc (ORCPT ); Tue, 1 May 2018 18:21:32 -0400 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w41MFruG117989 for ; Tue, 1 May 2018 18:21:32 -0400 Received: from e06smtp15.uk.ibm.com (e06smtp15.uk.ibm.com [195.75.94.111]) by mx0a-001b2d01.pphosted.com with ESMTP id 2hpyx8t2ww-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 01 May 2018 18:21:31 -0400 Received: from localhost by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 1 May 2018 23:21:29 +0100 Subject: Re: linux-next: UEFI Secure boot lockdown patchset From: Mimi Zohar To: Matthew Garrett Cc: David Howells , linux-integrity , Ben Hutchings , Nayna Jain Date: Tue, 01 May 2018 18:21:25 -0400 In-Reply-To: References: <26787.1519902415@warthog.procyon.org.uk> <8106.1525201247@warthog.procyon.org.uk> <1525205707.5669.91.camel@linux.vnet.ibm.com> <1525211403.5669.141.camel@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Message-Id: <1525213285.5669.152.camel@linux.vnet.ibm.com> Sender: linux-integrity-owner@vger.kernel.org List-ID: On Tue, 2018-05-01 at 21:59 +0000, Matthew Garrett wrote: > On Tue, May 1, 2018 at 2:50 PM Mimi Zohar wrote: > > > On Tue, 2018-05-01 at 21:02 +0000, Matthew Garrett wrote: > > > Hm. My concern is that distributions are going to ship IMA in a > > > configuration that allows users to add their own keys at boot time (it's > > > difficult to use it in a generic way otherwise), and that's going to > allow > > > kexecing of arbitrary images without requiring physical access. I think > > > kexec_file_load() needs to be relying on non-IMA signatures. > > > I don't see how. Unless the kernel was built with extra room for a > > local CA public key (CONFIG_SYSTEM_EXTRA_CERTIFICATE), which would be > > loaded onto the builtin keyring, there is no way of adding keys to the > > IMA keyring. Adding the extra public key would require the kernel to > > be resigned. > > Oh, is kexec verified off the _module keyring? We still end up with the > problem that distributions don't have a mechanism to ship IMA signatures > yet, but that avoids the user modification problem. I've just posted a > patchset to debian-dpkg, we'll see how that goes. I'm not aware of a _module keyring. With IMA-appraisal, the signature verification of the kernel image (kexec_file_load) uses the trusted IMA keyring. Nayna Jain posted a patch that defines a new platform keyring[1], which would only be used to validate the kernel image and initramfs signatures. Your review would be much appreciated! I really do hope that some version of including file signatures in Debian packages will be upstreamed soon. Good luck! [1] https://lkml.org/lkml/2018/2/28/1089 Mimi