Re: [PATCH] tpm: Fix TPM 1.2 Shutdown sequence to prevent future TPM operations

From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Doug Anderson <dianders@chromium.org>,
	Jason Gunthorpe <jgg@ziepe.ca>, "# 4.0+" <stable@vger.kernel.org>,
	Guenter Roeck <groeck@chromium.org>,
	Vadim Sukhomlinov <sukhomlinov@google.com>,
	Arnd Bergmann <arnd@arndb.de>, Peter Huewe <peterhuewe@gmx.de>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-integrity@vger.kernel.org
Subject: Re: [PATCH] tpm: Fix TPM 1.2 Shutdown sequence to prevent future TPM operations
Date: Tue, 6 Aug 2019 00:05:01 +0300	[thread overview]
Message-ID: <20190805210501.vjtmwgxjg334vtnc@linux.intel.com> (raw)
In-Reply-To: <20190712152734.GA13940@kroah.com>

On Fri, Jul 12, 2019 at 05:27:34PM +0200, Greg KH wrote:
> On Fri, Jul 12, 2019 at 08:00:12AM -0700, Doug Anderson wrote:
> > Hi,
> > 
> > On Fri, Jul 12, 2019 at 4:50 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Thu, Jul 11, 2019 at 10:28:01AM -0700, Doug Anderson wrote:
> > > > Hi,
> > > >
> > > > On Thu, Jul 11, 2019 at 10:26 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> > > > >
> > > > > On Thu, Jul 11, 2019 at 02:17:26PM -0300, Jason Gunthorpe wrote:
> > > > > > On Thu, Jul 11, 2019 at 07:04:37PM +0200, Greg KH wrote:
> > > > > > > On Thu, Jul 11, 2019 at 01:39:15PM -0300, Jason Gunthorpe wrote:
> > > > > > > > On Thu, Jul 11, 2019 at 09:29:19AM -0700, Douglas Anderson wrote:
> > > > > > > > > From: Vadim Sukhomlinov <sukhomlinov@google.com>
> > > > > > > > >
> > > > > > > > > commit db4d8cb9c9f2af71c4d087817160d866ed572cc9 upstream.
> > > > > > > > >
> > > > > > > > > TPM 2.0 Shutdown involve sending TPM2_Shutdown to TPM chip and disabling
> > > > > > > > > future TPM operations. TPM 1.2 behavior was different, future TPM
> > > > > > > > > operations weren't disabled, causing rare issues. This patch ensures
> > > > > > > > > that future TPM operations are disabled.
> > > > > > > > >
> > > > > > > > > Fixes: d1bd4a792d39 ("tpm: Issue a TPM2_Shutdown for TPM2 devices.")
> > > > > > > > > Cc: stable@vger.kernel.org
> > > > > > > > > Signed-off-by: Vadim Sukhomlinov <sukhomlinov@google.com>
> > > > > > > > > [dianders: resolved merge conflicts with mainline]
> > > > > > > > > Signed-off-by: Douglas Anderson <dianders@chromium.org>
> > > > > > > > > Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > > > > > > > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > > > > > > > > This is the backport of the patch referenced above to 4.19 as was done
> > > > > > > > > in Chrome OS.  See <https://crrev.com/c/1495114> for details.  It
> > > > > > > > > presumably applies to some older kernels.  NOTE that the problem
> > > > > > > > > itself has existed for a long time, but continuing to backport this
> > > > > > > > > exact solution to super old kernels is out of scope for me.  For those
> > > > > > > > > truly interested feel free to reference the past discussion [1].
> > > > > > > > >
> > > > > > > > > Reason for backport: mainline has commit a3fbfae82b4c ("tpm: take TPM
> > > > > > > > > chip power gating out of tpm_transmit()") and commit 719b7d81f204
> > > > > > > > > ("tpm: introduce tpm_chip_start() and tpm_chip_stop()") and it didn't
> > > > > > > > > seem like a good idea to backport 17 patches to avoid the conflict.
> > > > > > > >
> > > > > > > > Careful with this, you can't backport this to any kernels that don't
> > > > > > > > have the sysfs ops locking changes or they will crash in sysfs code.
> > > > > > >
> > > > > > > And what commit added that?
> > > > > >
> > > > > > commit 2677ca98ae377517930c183248221f69f771c921
> > > > > > Author: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > > > > > Date:   Sun Nov 4 11:38:27 2018 +0200
> > > > > >
> > > > > >     tpm: use tpm_try_get_ops() in tpm-sysfs.c.
> > > > > >
> > > > > >     Use tpm_try_get_ops() in tpm-sysfs.c so that we can consider moving
> > > > > >     other decorations (locking, localities, power management for example)
> > > > > >     inside it. This direction can be of course taken only after other call
> > > > > >     sites for tpm_transmit() have been treated in the same way.
> > > > > >
> > > > > > The last sentence suggests there are other patches needed too though..
> > > > >
> > > > > So 5.1.  So does this original patch need to go into the 5.2 and 5.1
> > > > > kernels?
> > > >
> > > > The patch ("Fix TPM 1.2 Shutdown sequence to prevent future TPM
> > > > operations")?  It's already done.  It just got merge conflicts when
> > > > going back to 4.19 which is why I sent the backport.
> > >
> > > But the sysfs comment means I should not apply this backport then?
> > >
> > > Totally confused by this long thread, sorry.
> > >
> > > What am I supposed to do for the stable trees here?
> > 
> > I think the answer is to drop my backport for now and Jarkko says
> > he'll take a fresh look at it in 2 weeks when he's back from his
> > leave.  Thus my understanding:
> > 
> > * On mainline: fixed
> > 
> > * On 5.2 / 5.1: you've already got this picked to stable.  Good
> > 
> > * On 4.14 / 4.19: Jarkko will look at in 2 weeks.
> > 
> > * On 4.9 and older: I'd propose skipping unless someone is known to
> > need a solution here.
> 
> Thanks, that makes sense now.
> 
> greg k-h

I have not forgotten this but might have to postpone the backport after
Linux Plumbers. Just have lots of stuff in my queue ATM but right after
the conference I have good slot to do the backports.

/Jarkko