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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43E8FC433FE for ; Thu, 14 Apr 2022 12:14:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243046AbiDNMQ7 (ORCPT ); Thu, 14 Apr 2022 08:16:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50536 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232670AbiDNMQ4 (ORCPT ); Thu, 14 Apr 2022 08:16:56 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E76653881; Thu, 14 Apr 2022 05:14:30 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 9AA44B82934; Thu, 14 Apr 2022 12:14:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E23C5C385A1; Thu, 14 Apr 2022 12:14:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1649938468; bh=/lJMbuqCUvWBZpDnchq4yA5y4o3tnZsGQzcMlBudlhc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rhIklwqG0vK08DiwAvIq46xKLUt/JvMV2fvNoRox7yLjyIuBlgwssXE0jQyTaduf4 Fj1e02mps6gNkaGfUaj6v6PTuxnFMAMwKHAbjPKt/VLqfruZ7oE+jWVgGRnwbXpShI Er/kXcujqDv91ZI+JRntMtLeZs9O8AJ9oz7sObp8FOZQlwldfJB6UvKiS0YuDf2SuH G7l84ppQyR0cUJQTn2PipFZABkvqO0PJbcumc01QZDk28aybHtHipO6xZxUPSyPP4i SDplQYQAFZdiFIEQsMO6jQaW05ZjpLSZPQJBYZQrL5HWN9CwvWJUa4ZhKHP2dGSTqw 3fnzX95jTG8LA== Date: Thu, 14 Apr 2022 15:13:20 +0300 From: Jarkko Sakkinen To: Jason Gunthorpe Cc: Lukas Wunner , Lino Sanfilippo , peterhuewe@gmx.de, devicetree@vger.kernel.org, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, stefanb@linux.ibm.com, p.rosenberger@kunbus.com Subject: Re: [PATCH 1/5] tpm: add functions to set and unset the tpm chips reset state Message-ID: References: <20220407111849.5676-1-LinoSanfilippo@gmx.de> <20220407111849.5676-2-LinoSanfilippo@gmx.de> <20220407142526.GW64706@ziepe.ca> <20220410171123.GA24453@wunner.de> <20220411114741.GA64706@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220411114741.GA64706@ziepe.ca> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 11, 2022 at 08:47:41AM -0300, Jason Gunthorpe wrote: > On Sun, Apr 10, 2022 at 07:11:23PM +0200, Lukas Wunner wrote: > > On Thu, Apr 07, 2022 at 11:25:26AM -0300, Jason Gunthorpe wrote: > > > On Thu, Apr 07, 2022 at 01:18:45PM +0200, Lino Sanfilippo wrote: > > > > Currently it is not possible to set the tpm chips reset state from within > > > > the driver. This is problematic if the chip is still in reset after the > > > > system comes up. This may e.g. happen if the reset line is pulled into > > > > reset state by a pin configuration in the device tree. > > > > > > This kind of system is badly misdesigned. > > > > > > TPM PCRs fundementally cannot work if the TPM reset line is under > > > software control. > > > > Not every system which incorporates a TPM wants to use or is even capable > > of measuring software state of any kind or perform secure boot. > > > > Those systems may merely want to use the TPM to store key material. > > Then maybe the TPM driver should make it clear somehow that the PCRs > don't work in these systems. > > It is really dangerous to add capabilities like this that should > never, ever be used in sanely designed systems. > > Jason I agree. That niche should do the bad things with oot patches. BR, Jarkko