From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751882AbdJXSQS (ORCPT ); Tue, 24 Oct 2017 14:16:18 -0400 Received: from mga11.intel.com ([192.55.52.93]:40812 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751755AbdJXSQN (ORCPT ); Tue, 24 Oct 2017 14:16:13 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,428,1503385200"; d="scan'208";a="141762922" Date: Tue, 24 Oct 2017 20:15:12 +0200 From: Jarkko Sakkinen To: Dmitry Torokhov Cc: Jason Gunthorpe , PrasannaKumar Muralidharan , Stefan Berger , linux-integrity@vger.kernel.org, David Howells , Herbert Xu , "open list:INTEGRITY MEASUREMENT ARCHITECTURE IMA" , Dmitry Kasatkin , open list , linux-security-module@vger.kernel.org, "moderated list:TPM DEVICE DRIVER" , "open list:KEYS-TRUSTED" , "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" , James Morris , Matt Mackall , "open list:INTEGRITY MEASUREMENT ARCHITECTURE IMA" , David Safford , Mimi Zohar , "Serge E. Hallyn" Subject: Re: [tpmdd-devel] [PATCH] tpm: remove chip_num parameter from in-kernel API Message-ID: <20171024181512.iaxtzgxexhki7aqr@linux.intel.com> References: <20171023123817.18559-1-jarkko.sakkinen@linux.intel.com> <20171023163139.GA17394@obsidianresearch.com> <20171024154440.3jeupmus43jcgbbz@linux.intel.com> <20171024155526.GA32250@obsidianresearch.com> <20171024161118.GA348@obsidianresearch.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 24, 2017 at 10:02:00AM -0700, Dmitry Torokhov wrote: > On Tue, Oct 24, 2017 at 9:11 AM, Jason Gunthorpe > wrote: > > On Tue, Oct 24, 2017 at 09:37:33PM +0530, PrasannaKumar Muralidharan wrote: > >> Hi Jason, > >> > >> On 24 October 2017 at 21:25, Jason Gunthorpe > >> wrote: > >> > On Tue, Oct 24, 2017 at 09:21:15PM +0530, PrasannaKumar Muralidharan wrote: > >> > > >> >> Please check the RFC [1]. It does use chip id. The rfc has issues and > >> >> has to be fixed but still there could be users of the API. > >> >> > >> >> 1. https://www.spinics.net/lists/linux-crypto/msg28282.html > >> > > >> > That patch isn't safe at all. You need to store a kref to th chip in > >> > the hwrng, not parse a string. > >> > >> The drivers/char/hw_random/tpm-rng.c module does not store the chip > >> reference so I guess the usage is safe. > > > > It is using the default TPM, it is always safe to use the default tpm. > > tpm-rng is abomination that should be kicked out as soon as possible. > It wrecks havoc with the power management (TPM chip drivers may go > into suspend state, but tpm_rng does not do any power management and > happily forwards requests to suspended hardware) and may be available > when there is no TPM at all yet (the drivers have not been probed yet, > or have gotten a deferral, etc). > > TPM core should register HWRNGs when chips are ready. > > Thanks. > > -- > Dmitry I'm fine to review a two patch set where: 1. Patch 1 removes the existing TPM rng driver 2. Patch 2 makes the TPM driver as rng producer Unrelate to patch that I'm proposing now but this sounds sensible. /Jarkko