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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,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 84726C433DF for ; Thu, 20 Aug 2020 15:46:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4EFB02054F for ; Thu, 20 Aug 2020 15:46:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729026AbgHTPqG (ORCPT ); Thu, 20 Aug 2020 11:46:06 -0400 Received: from mga01.intel.com ([192.55.52.88]:32883 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728209AbgHTPqE (ORCPT ); Thu, 20 Aug 2020 11:46:04 -0400 IronPort-SDR: 2KyHS3IREAzJ0tfDtbYmswe1WRn+HXBZYi1Xl31Uy8OVInrLeELdkAAHX3tDXtUYEO9V/4VQ/f N+0jOuX/2oNA== X-IronPort-AV: E=McAfee;i="6000,8403,9718"; a="173372167" X-IronPort-AV: E=Sophos;i="5.76,333,1592895600"; d="scan'208";a="173372167" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Aug 2020 08:46:04 -0700 IronPort-SDR: 6+uuEjHIxSqbONS30x1eFKWkIyzGvLQTkpdVMXB6qcM2I1vgYcHkh4O6PgJfl6N3JjXsMbBCl7 mGvI8w9yGtjQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.76,333,1592895600"; d="scan'208";a="498190222" Received: from mkidd-mobl.ger.corp.intel.com (HELO localhost) ([10.249.33.244]) by fmsmga005.fm.intel.com with ESMTP; 20 Aug 2020 08:46:02 -0700 Date: Thu, 20 Aug 2020 18:46:02 +0300 From: Jarkko Sakkinen To: Jerry Snitselaar Cc: Mimi Zohar , Jason Gunthorpe , James Bottomley , linux-integrity@vger.kernel.org Subject: Re: [PATCH v4 1/1] tpm: add sysfs exports for all banks of PCR registers Message-ID: <20200820154602.GB5462@linux.intel.com> References: <20200818164602.GZ1152540@nvidia.com> <39eb6b408e7f060ab241954102d06f97d1f99611.camel@linux.ibm.com> <20200818183603.GC1152540@nvidia.com> <14eaf21a808e333ca414c954d8f3a2f7b6dbf2ca.camel@linux.ibm.com> <20200819120238.GD1152540@nvidia.com> <59f983156fed466d568c324de72ef733c1a15d76.camel@linux.ibm.com> <20200819140943.GH1152540@nvidia.com> <20200819221647.GN9942@linux.intel.com> <87lfiamevo.fsf@jsnitsel.users.ipa.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87lfiamevo.fsf@jsnitsel.users.ipa.redhat.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Wed, Aug 19, 2020 at 03:48:11PM -0700, Jerry Snitselaar wrote: > > Jarkko Sakkinen @ 2020-08-19 15:16 MST: > > > On Wed, Aug 19, 2020 at 10:53:38AM -0400, Mimi Zohar wrote: > >> On Wed, 2020-08-19 at 11:09 -0300, Jason Gunthorpe wrote: > >> > On Wed, Aug 19, 2020 at 09:27:33AM -0400, Mimi Zohar wrote: > >> > > On Wed, 2020-08-19 at 09:02 -0300, Jason Gunthorpe wrote: > >> > > > On Tue, Aug 18, 2020 at 02:55:50PM -0400, Mimi Zohar wrote: > >> > > > > >> > > > > The problem is that there isn't just one single userspace library or > >> > > > > application for reading PCRs. So now not only is there the kernel > >> > > > > "boot_aggregate" regression testing, but regression testing of the tool > >> > > > > itself to support multiple methods of reading the PCRs. > >> > > > > >> > > > I was thinking just open code > >> > > > open("/dev/tpm") > >> > > > write(read_pcrs_cmd) > >> > > > read(read_pcrs_cmd) > >> > > > > >> > > > It isn't particularly hard to retrive the PCRs, don't really need to > >> > > > depend on a library. > >> > > > >> > > Ok, do you want to contribute it to ima-evm-utils? While you're at it, > >> > > do you also have code to parse the TPM 2.0 event log that you could > >> > > contribute? > >> > > > >> > > Seriously, we shouldn't be (re-)writing code to do this. > >> > > >> > The kernel should not be used a dumping ground to work around a > >> > dysfunctional userspace either. :( > >> > > >> > You've basicaly said you can't rely on a sane userspace library > >> > because *reasons* so we need to dump stuff in the kernel instead. > >> > > >> > It is not a good justification to add new uAPI. > >> > > >> > James seems to have the same basic conclusion too, unfortunately. > >> > >> "dysfunctional" is dropping existing TPM 1.2 sysfs support, which was > >> done without consideration about existing applications/tools (e.g. ima- > >> evm-utils, ltp) and without community input. It's not only James that > >> is advocating for exporting the TPM PCRs, but Jerry Snitselaar, who > >> reviewed this patch and exported the TPM version, and Nayna Jain, who > >> exported the TPM 2.0 event log. I'm pretty sure there are a number of > >> other people who would agree. > >> > >> Mimi > > > > This is not true. TPM 1.2 sysfs was not dropped. > > > > Not adding something does not mean technically dropping something. > > > > /Jarkko > > When reviewing it I honestly didn't give much(any?) thought to whether > it should be there. My thought was it adhered to the 1 value per file > rule unlike the 1.2 pcrs file and that was about it. > > IIRC when 2.0 was added there was the issue of things like the 1.2 pcrs > not conforming to standards, possible issues of races, and a question of > what exactly should be exported. 1.2 has a number of files for doing > things that I think were also handled by ppi and userspace. > > I guess the question is where does the line get drawn. My exporting the > major version of the tpm probably could've been handled instead with a > pr_info spitting it out for people to grab out of dmesg. > > > Jerry TPM protocol version is a different case tha dumping all the PCRs as ASCII. It fairly unintrusive feature for the kernel, kernel has this knowledge stored already and it is constant for a boot cycle. /Jarkko