tree eadb9fffdea849c8ca8547e8dfc344287dca563e
parent eedd4293582b86a43eab6400d0a967bccf14f1fe
author Andrey Pronin <apronin@chromium.org> 1478916023 -0800
committer chrome-bot <chrome-bot@chromium.org> 1479260546 -0800

tpm2_lite: use null password authorization for ReadLock

Most of the indexes used in practice, have AUTHREAD set with null
password authentication. The only index, for which READ_STCLEAR is
set and TlclReadLock() is called is the one used by mount-encrypted.
It has AUTHREAD with empty password and should be lockable after
platform hierarchy is disabled. So, use null password authorization
instead of platform authorization in TlclReadLock().

BUG=chrome-os-partner:54708
BRANCH=none
TEST=Start with OOBE, corporate enroll, reboot, verify that the system
     doesn't go back to OOBE. Check mount-encrypted.log on start: it
     should contain "Read-locking NVRAM area succeeded".

Change-Id: Iaac78ba4dd048edac992adfab6fb94b69b2e989a
Reviewed-on: https://chromium-review.googlesource.com/410780
Commit-Ready: Andrey Pronin <apronin@chromium.org>
Tested-by: Andrey Pronin <apronin@chromium.org>
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>