From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09EA7C71155 for ; Tue, 1 Dec 2020 00:23:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9EDAB207FF for ; Tue, 1 Dec 2020 00:22:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="OZSIUni6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730832AbgLAAWk (ORCPT ); Mon, 30 Nov 2020 19:22:40 -0500 Received: from mail.kernel.org ([198.145.29.99]:53870 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727375AbgLAAWk (ORCPT ); Mon, 30 Nov 2020 19:22:40 -0500 Received: from localhost (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0E14720706; Tue, 1 Dec 2020 00:21:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606782119; bh=jidxCeKSZhkwUbNx5KSkEk3WyfcJfqoe6qsuKPa93Xg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OZSIUni6CuHazkbY4OgDC4XQpZdATYDeMo2AQrStNF+L0AxXLrQVGpDeIJspqRJdZ igso+8FlvYZAATRbsbBFCBTIx7AYTpkTMfpk5a0BS1kMRmstzrgYG3GCxtzywkfgZ5 pJXoeQtko8JHeg1/5/lv2AZSjNYTxnBM/sTMZH3A= Date: Mon, 30 Nov 2020 19:21:57 -0500 From: Sasha Levin To: Mimi Zohar Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Maurizio Drocco , Bruno Meneguele , linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: [PATCH AUTOSEL 5.7 03/30] ima: extend boot_aggregate with kernel measurements Message-ID: <20201201002157.GT643756@sasha-vm> References: <20200708154116.3199728-1-sashal@kernel.org> <20200708154116.3199728-3-sashal@kernel.org> <1594224793.23056.251.camel@linux.ibm.com> <20200709012735.GX2722994@sasha-vm> <5b8dcdaf66fbe2a39631833b03772a11613fbbbf.camel@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <5b8dcdaf66fbe2a39631833b03772a11613fbbbf.camel@linux.ibm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Nov 29, 2020 at 08:17:38AM -0500, Mimi Zohar wrote: >Hi Sasha, > >On Wed, 2020-07-08 at 21:27 -0400, Sasha Levin wrote: >> On Wed, Jul 08, 2020 at 12:13:13PM -0400, Mimi Zohar wrote: >> >Hi Sasha, >> > >> >On Wed, 2020-07-08 at 11:40 -0400, Sasha Levin wrote: >> >> From: Maurizio Drocco >> >> >> >> [ Upstream commit 20c59ce010f84300f6c655d32db2610d3433f85c ] >> >> >> >> Registers 8-9 are used to store measurements of the kernel and its >> >> command line (e.g., grub2 bootloader with tpm module enabled). IMA >> >> should include them in the boot aggregate. Registers 8-9 should be >> >> only included in non-SHA1 digests to avoid ambiguity. >> > >> >Prior to Linux 5.8, the SHA1 template data hashes were padded before >> >being extended into the TPM. Support for calculating and extending >> >the per TPM bank template data digests is only being upstreamed in >> >Linux 5.8. >> > >> >How will attestation servers know whether to include PCRs 8 & 9 in the >> >the boot_aggregate calculation? Now, there is a direct relationship >> >between the template data SHA1 padded digest not including PCRs 8 & 9, >> >and the new per TPM bank template data digest including them. >> >> Got it, I'll drop it then, thank you! > >After re-thinking this over, I realized that the attestation server can >verify the "boot_aggregate" based on the quoted PCRs without knowing >whether padded SHA1 hashes or per TPM bank hash values were extended >into the TPM[1], but non-SHA1 boot aggregate values [2] should always >include PCRs 8 & 9. > >Any place commit 6f1a1d103b48 was backported [2], this commit >20c59ce010f8 ("ima: extend boot_aggregate with kernel measurements") >should be backported as well. Which kernels should it apply to? 5.7 is EOL now, so I looked at 5.4 but it doesn't apply cleanly there. -- Thanks, Sasha