From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Sakkinen Subject: Re: [tpmdd-devel] [PATCH RESEND 3/3] tpm-chip: Export TPM device to user space even when startup failed Date: Wed, 30 Aug 2017 13:20:02 +0300 Message-ID: <20170830102002.nufnr77whz5jzwfr@linux.intel.com> References: <20170824083714.10016-1-Alexander.Steffen@infineon.com> <20170824083714.10016-4-Alexander.Steffen@infineon.com> <20170825172021.lw3ycxqw63ubrcm2@linux.intel.com> <20170829125509.55aylht3ikes3bpy@linux.intel.com> <20170829151739.315ae581@kitsune.suse.cz> <20170830101510.rlkh2p3zecfsrhgl@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <20170830101510.rlkh2p3zecfsrhgl@linux.intel.com> Sender: owner-linux-security-module@vger.kernel.org To: Michal =?iso-8859-1?Q?Such=E1nek?= Cc: Alexander.Steffen@infineon.com, linux-security-module@vger.kernel.org, tpmdd-devel@lists.sourceforge.net List-Id: tpmdd-devel@lists.sourceforge.net On Wed, Aug 30, 2017 at 01:15:10PM +0300, Jarkko Sakkinen wrote: > On Tue, Aug 29, 2017 at 03:17:39PM +0200, Michal Suchánek wrote: > > Hello, > > > > On Tue, 29 Aug 2017 15:55:09 +0300 > > Jarkko Sakkinen wrote: > > > > > On Mon, Aug 28, 2017 at 05:15:58PM +0000, > > > Alexander.Steffen@infineon.com wrote: > > > > But is that just because nobody bothered to implement the necessary > > > > logic or for some other reason? > > > > > > We do not want user space to access broken hardware. It's a huge risk > > > for system stability and potentially could be used for evil purposes. > > > > > > This is not going to mainline as it is not suitable for general > > > consumption. You must use a patched kernel if you want this. > > > > > > /Jarkko > > > > > > > It has been pointed out that userspace applications that use direct IO > > access exist for the purpose. So using a kernel driver is an > > improvement over that if the interface is otherwise sane. > > > > What do you expect is the potential for instability or evil use? > > By definition the use of broken hardware can have unpredictable effects. > Use a patched kernel if you want to do it. > > /Jarkko I.e. too many unknown unknowns for mainline. I could consider a solution for the TPM error case on self-test that allows only restricted subset of commands. The patch description did not go to *any* detail on how it is used so practically it's unreviewable at this point. There's a big burder of proof and now there's only hand waving. /Jarkko