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From: Josh Zimmerman via tpmdd-devel <tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>
To: Jarkko Sakkinen
	<jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Cc: tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
	jmorris-gx6/JNMH7DfYtjvyW6yDsg@public.gmane.org
Subject: Re: [PATCH v7 0/2] Run TPM2_Shutdown on system shutdown
Date: Thu, 29 Jun 2017 08:18:13 -0700	[thread overview]
Message-ID: <CAHSjozC=QHx52oUpO8Vuf2-DusGAqHpxjo1W2TvmXmuaS7hgJg@mail.gmail.com> (raw)
In-Reply-To: <1498742891.30068.1.camel-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>

On Thu, Jun 29, 2017 at 6:28 AM, Jarkko Sakkinen
<jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> wrote:
> On Sun, 2017-06-25 at 14:53 -0700, Josh Zimmerman wrote:
>> This patchset causes all devices in the tpm class to issue TPM2_Shutdown
>> when the system is shutting down.
>>
>> As a prerequisite, it adds a "shutdown" method to "struct class".
>>
>> Since this bug can cause users to be locked out of their TPMs, I'd like
>> this patch included in at least 4.4 and 4.9. 4.1 is nice-to-have but not
>> essential.
>>
>> gregkh Acked the proposal for stable in v3 of this patch.
>>
>>  drivers/base/core.c          |  6 +++++-
>>  drivers/char/tpm/tpm-chip.c  | 34 ++++++++++++++++++++++++++++++++++
>>  drivers/char/tpm/tpm-sysfs.c |  3 +++
>>  include/linux/device.h       |  2 ++
>>  4 files changed, 44 insertions(+), 1 deletion(-
>
> Josh,
>
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
>
> I'll rebase my next after testing (and add also Tested-by).
>
> I have one question as you are more familiar with the issue a hand.
> What if you just cut the power from the device, does this affect
> DA counter?

Just cut power without a TPM2_Shutdown, you mean? Yes, it does.

"To prevent this type of attack, at TPM2_Startup(), the TPM checks if
it is starting after an orderly shutdown. If not, and failedTries is
not already equal to maxTries, then the TPM will increment failedTries
by one"

The key, I think, is that shutdowns are assumed to be disorderly
unless there's an explicit TPM2_Shutdown that indicates otherwise.

(this is from 19.8.6 of
https://trustedcomputinggroup.org/wp-content/uploads/TPM-Rev-2.0-Part-1-Architecture-01.38.pdf)

> /Jarkko

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  parent reply	other threads:[~2017-06-29 15:18 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-25 21:53 Josh Zimmerman via tpmdd-devel
     [not found] ` <20170625215324.17467-1-joshz-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2017-06-25 21:53   ` [PATCH v7 1/2] Add "shutdown" to "struct class" Josh Zimmerman via tpmdd-devel
2017-06-25 21:53   ` [PATCH v7 2/2] tpm: Issue a TPM2_Shutdown for TPM2 devices Josh Zimmerman via tpmdd-devel
2017-06-29 13:28   ` [PATCH v7 0/2] Run TPM2_Shutdown on system shutdown Jarkko Sakkinen
     [not found]     ` <1498742891.30068.1.camel-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-06-29 15:18       ` Josh Zimmerman via tpmdd-devel [this message]
2017-06-29 19:54       ` Jarkko Sakkinen
     [not found]         ` <20170629195423.fmh5mxhwbh7aaexa-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-07-10 19:14           ` Josh Zimmerman via tpmdd-devel

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