From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:55954 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727132AbeIZUyO (ORCPT ); Wed, 26 Sep 2018 16:54:14 -0400 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w8QEeMM1113451 for ; Wed, 26 Sep 2018 10:40:56 -0400 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0b-001b2d01.pphosted.com with ESMTP id 2mrbjp9t2d-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 26 Sep 2018 10:40:56 -0400 Received: from localhost by e06smtp01.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 26 Sep 2018 15:40:55 +0100 Subject: Re: [PATCH v2, RESEND 0/3] tpm: retrieve digest size of unknown algorithms from TPM From: Mimi Zohar To: Roberto Sassu , jarkko.sakkinen@linux.intel.com Cc: linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 26 Sep 2018 10:40:40 -0400 In-Reply-To: <20180917093820.20500-1-roberto.sassu@huawei.com> References: <20180917093820.20500-1-roberto.sassu@huawei.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Message-Id: <1537972840.3459.6.camel@linux.ibm.com> Sender: linux-integrity-owner@vger.kernel.org List-ID: 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 Thanks! Mimi