Re: [PATCH v3] tpm: Issue a TPM2_Shutdown for TPM2 devices.

[Josh Zimmerman <joshz-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>]

Yes, will do. Can you mark a Reviewed-by on this version of the patch
as well? You marked v2 already, but this is probably the version that
should be submitted.
Josh


On Sat, May 20, 2017 at 6:20 AM, Jarkko Sakkinen
<jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> wrote:
> Yes. Can you ping me once it is in? I can merge this after that.
>
> /Jarkko
>
> On Thu, May 18, 2017 at 08:21:32AM -0700, Josh Zimmerman wrote:
>> Are there any other changes I should make to this patch, or is it good
>> to go once the patch it depends on is in?
>>
>> Thanks!
>> Josh
>>
>>
>> On Mon, May 15, 2017 at 5:08 PM, Josh Zimmerman <joshz-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> wrote:
>> > If a TPM2 loses power without a TPM2_Shutdown command being issued (a
>> > "disorderly reboot"), it may lose some state that has yet to be
>> > persisted to NVRam, and will increment the DA counter (eventually, this
>> > will cause the TPM to lock the user out.)
>> >
>> > NOTE: This only changes behavior on TPM2 devices. Since TPM1 uses sysfs,
>> > and sysfs relies on implicit locking on chip->ops, it is not safe to
>> > allow this code to run in TPM1, or to add sysfs support to TPM2, until
>> > that locking is made explicit.
>> >
>> > This patch is dependent on '[PATCH] Add "shutdown" to "struct class".'
>> > http://marc.info/?l=linux-kernel&m=149463235025420&w=2
>> >
>> > Signed-off-by: Josh Zimmerman <joshz-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
>> >
>> > ----
>> > v2:
>> >   - Properly split changes between this and another commit
>> >   - Use proper locking primitive.
>> >   - Fix commenting style
>> > v3:
>> >   - Re-fix commenting style
>> > ---
>> >  drivers/char/tpm/tpm-chip.c  | 20 ++++++++++++++++++++
>> >  drivers/char/tpm/tpm-sysfs.c |  3 +++
>> >  2 files changed, 23 insertions(+)
>> >
>> > diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
>> > index 9dec9f551b83..272a42e77574 100644
>> > --- a/drivers/char/tpm/tpm-chip.c
>> > +++ b/drivers/char/tpm/tpm-chip.c
>> > @@ -142,6 +142,25 @@ static void tpm_devs_release(struct device *dev)
>> >         put_device(&chip->dev);
>> >  }
>> >
>> > +static void tpm_shutdown(struct device *dev)
>> > +{
>> > +       struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev);
>> > +       /* TPM 2.0 requires that the TPM2_Shutdown() command be issued prior to
>> > +        * loss of power. If it is not, the DA counter will be incremented and,
>> > +        * eventually, the user will be locked out of their TPM.
>> > +        * XXX: This codepath relies on the fact that sysfs is not enabled for
>> > +        * TPM2: sysfs uses an implicit lock on chip->ops, so this use could
>> > +        * race if TPM2 has sysfs support enabled before TPM sysfs's implicit
>> > +        * locking is fixed.
>> > +        */
>> > +       if (chip->flags & TPM_CHIP_FLAG_TPM2) {
>> > +               down_write(&chip->ops_sem);
>> > +               tpm2_shutdown(chip, TPM_SU_CLEAR);
>> > +               chip->ops = NULL;
>> > +               up_write(&chip->ops_sem);
>> > +       }
>> > +}
>> > +
>> >  /**
>> >   * tpm_chip_alloc() - allocate a new struct tpm_chip instance
>> >   * @pdev: device to which the chip is associated
>> > @@ -181,6 +200,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
>> >         device_initialize(&chip->devs);
>> >
>> >         chip->dev.class = tpm_class;
>> > +       chip->dev.class.shutdown = tpm_shutdown;
>> >         chip->dev.release = tpm_dev_release;
>> >         chip->dev.parent = pdev;
>> >         chip->dev.groups = chip->groups;
>> > diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
>> > index 55405dbe43fa..5e5ff7eb6f7e 100644
>> > --- a/drivers/char/tpm/tpm-sysfs.c
>> > +++ b/drivers/char/tpm/tpm-sysfs.c
>> > @@ -294,6 +294,9 @@ static const struct attribute_group tpm_dev_group = {
>> >
>> >  void tpm_sysfs_add_device(struct tpm_chip *chip)
>> >  {
>> > +       /* XXX: Before this restriction is removed, tpm_sysfs must be updated
>> > +        * to explicitly lock chip->ops.
>> > +        */
>> >         if (chip->flags & TPM_CHIP_FLAG_TPM2)
>> >                 return;
>> >
>> > --
>> > 2.13.0.303.g4ebf302169-goog
>> >

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