From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:42754 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727146AbeI0AR7 (ORCPT ); Wed, 26 Sep 2018 20:17:59 -0400 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w8QHsDNs011532 for ; Wed, 26 Sep 2018 14:03:52 -0400 Received: from e06smtp03.uk.ibm.com (e06smtp03.uk.ibm.com [195.75.94.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 2mre5dtqeu-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 26 Sep 2018 14:03:52 -0400 Received: from localhost by e06smtp03.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 26 Sep 2018 19:03:49 +0100 Subject: Re: [PATCH v2, RESEND 0/3] tpm: retrieve digest size of unknown algorithms from TPM From: Mimi Zohar To: jarkko.sakkinen@linux.intel.com, Roberto Sassu Cc: linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, David Safford Date: Wed, 26 Sep 2018 14:03:34 -0400 In-Reply-To: <1537972840.3459.6.camel@linux.ibm.com> References: <20180917093820.20500-1-roberto.sassu@huawei.com> <1537972840.3459.6.camel@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Message-Id: <1537985014.3459.24.camel@linux.ibm.com> Sender: linux-integrity-owner@vger.kernel.org List-ID: On Wed, 2018-09-26 at 10:40 -0400, Mimi Zohar wrote: > On Mon, 2018-09-17 at 11:38 +0200, Roberto Sassu wrote: > > Resending to maintainer with correct mailing lists in CC. > > > > The TPM driver currently relies on the crypto subsystem to determine the > > digest size of supported TPM algorithms. In the future, TPM vendors might > > implement new algorithms in their chips, and those algorithms might not > > be supported by the crypto subsystem. > > > > Usually, vendors provide patches for the new hardware, and likely > > the crypto subsystem will be updated before the new algorithm is > > introduced. However, old kernels might be updated later, after patches > > are included in the mainline kernel. This would leave the opportunity > > for attackers to misuse PCRs, as PCR banks with an unknown algorithm > > are not extended. > > > > This patch set provides a long term solution for this issue. If a TPM > > algorithm is not known by the crypto subsystem, the TPM driver retrieves > > the digest size from the TPM with a PCR read. All the PCR banks are > > extended, even if the algorithm is not yet supported by the crypto > > subsystem. > > Other than checking the digest size before copying the pcrread buffer, > the patches look good. Please add my Ack on all 3 patches. > > (New address) Acked-by: Mimi Zohar I've reviewed, and am currently running with these patches. Even if the IMA changes were in a separate patch, we wouldn't be able to break up the patch set anyway. Jarkko, I'd appreciate your carrying the entire patch set. Roberto, a similar change needs to be made for tpm_pcr_extend. Are you planning on posting those changes as well? Mimi