From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:48468 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751140AbeEAXnr (ORCPT ); Tue, 1 May 2018 19:43:47 -0400 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w41NgPcf039746 for ; Tue, 1 May 2018 19:43:47 -0400 Received: from e06smtp15.uk.ibm.com (e06smtp15.uk.ibm.com [195.75.94.111]) by mx0a-001b2d01.pphosted.com with ESMTP id 2hq1bcsbwq-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 01 May 2018 19:43:46 -0400 Received: from localhost by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 2 May 2018 00:43:44 +0100 Subject: Re: linux-next: UEFI Secure boot lockdown patchset From: Mimi Zohar To: Matthew Garrett Cc: David Howells , linux-integrity , Ben Hutchings , nayna@linux.vnet.ibm.com Date: Tue, 01 May 2018 19:43:40 -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> <1525213285.5669.152.camel@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Message-Id: <1525218220.5669.164.camel@linux.vnet.ibm.com> Sender: linux-integrity-owner@vger.kernel.org List-ID: On Tue, 2018-05-01 at 22:32 +0000, Matthew Garrett wrote: > On Tue, May 1, 2018 at 3:21 PM Mimi Zohar wrote: > > > On Tue, 2018-05-01 at 21:59 +0000, Matthew Garrett wrote: > > > 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. > > INTEGRITY_KEYRING_MODULE is defined, but doesn't appear to be used > anywhere. Odd. Anyway, distributions are unlikely to ship with > CONFIG_INTEGRITY_TRUSTED_KEYRING since it makes it impossible for users to > determine which set of IMA or EVM signatures they want to trust. So if > validation is against the IMA keyring rather than builtin_trusted_keys, > it's going to be possible for users to extend the set of trusted keys. If > CONFIG_KEXEC_BZIMAGE_VERIFY_SIG is set then the kernel seems to do the > right thing here, but it's not clear to me how that's supposed to interact > with IMA? >>From your description, whatever keys the distros are loading onto the builtin_trusted_keys keyring for verifying the kexec kernel image, could just as easily be added to the IMA trusted keyring (CONFIG_INTEGRITY_TRUSTED_KEYRING). I don't see the difference. Loading other keys requires reserving memory for a local CA public key. Mimi