[PATCH v2] tpm_crb: request and relinquish locality 0

On Mon, Mar 13, 2017 at 10:34:52AM -0600, Jason Gunthorpe wrote:

On Sat, Mar 11, 2017 at 03:02:14PM +0200, Jarkko Sakkinen wrote:

quoted

Added two new callbacks to struct tpm_class_ops:

- request_locality
- relinquish_locality

These are called before sending and receiving data from the TPM.  We
update also tpm_tis_core to use these callbacks. Small modification to
request_locality() is done so that it returns -EBUSY instead of locality
number when check_locality() fails.

Make sense

I think you may as well do the other two drivers, even though you
can't run them the transformation looks safe enough to me.

quoted

Signed-off-by: Jarkko Sakkinen <redacted>
 drivers/char/tpm/tpm-interface.c |  9 +++++++++
 drivers/char/tpm/tpm_crb.c       | 41 +++++++++++++++++++++++++++++++++++++++-
 drivers/char/tpm/tpm_tis_core.c  | 12 ++++--------
 include/linux/tpm.h              |  3 ++-
 4 files changed, 55 insertions(+), 10 deletions(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index e38c792..9c56581 100644
+++ b/drivers/char/tpm/tpm-interface.c

@@ -407,6 +407,12 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
 	if (chip->dev.parent)
 		pm_runtime_get_sync(chip->dev.parent);
 
+	if (chip->ops->request_locality)  {
+		rc = chip->ops->request_locality(chip, 0);
+		if (rc)
+			goto out;

If request_locality fails we probably shouldn't call
relinquish_locality on the unwind path..

I think you should also put a relinquish_locality inside tpm_remove ?

Right. I was wondering why release_locality is called inside
tpm_tis_remove().

So is the idea of checking pendingRequest such that the release
part is "lazy" and not like what I'm doing in tpm_crb (always
relinquish).

Is that done for performance reasons? Should I do the same (pr
similar in tpm_crb?

quoted

+	int (*request_locality)(struct tpm_chip *chip, int loc);
+	void (*relinquish_locality)(struct tpm_chip *chip, int loc,
bool force);

Let us document what force is supposed to do...

I'm not sure why we have it?

Jason

I guess since it is lazy in tpm_tis_core the force is done in
tpm_tis_remove so that you always relinquish the locality even
if someone is not requesting it, right?

Where should this be documented, to the header?

/Jarkko
--
To unsubscribe from this list: send the line "unsubscribe linux-security-module" in
the body of a message to majordomo at vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html