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

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Message-ID: <CAD=FV=UBOWHrEFQRhxsnK-PmVkFjcvnEruuy0sYHh0p-Qnk8pA@mail.gmail.com>
Date:   Fri, 12 Jul 2019 08:00:12 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Jason Gunthorpe <jgg@...pe.ca>, "# 4.0+" <stable@...r.kernel.org>,
        Guenter Roeck <groeck@...omium.org>,
        Vadim Sukhomlinov <sukhomlinov@...gle.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Arnd Bergmann <arnd@...db.de>, Peter Huewe <peterhuewe@....de>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-integrity@...r.kernel.org
Subject: Re: [PATCH] tpm: Fix TPM 1.2 Shutdown sequence to prevent future TPM operations

Hi,

On Fri, Jul 12, 2019 at 4:50 AM Greg KH <gregkh@...uxfoundation.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@...uxfoundation.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@...gle.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@...r.kernel.org
> > > > > > > Signed-off-by: Vadim Sukhomlinov <sukhomlinov@...gle.com>
> > > > > > > [dianders: resolved merge conflicts with mainline]
> > > > > > > Signed-off-by: Douglas Anderson <dianders@...omium.org>
> > > > > > > Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > > > > > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.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@...ux.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.

-Doug