Add clear TPM owner request

This adds two new flags to crossystem:
   clear_tpm_owner_request
   clear_tpm_owner_done

The first one requests that the firmware clear the TPM owner on the
next boot.  When the firmware does this, it will set
clear_tpm_owner_request=0, and set clear_tpm_owner_done=1.  The OS can
use the done-flag as a hint that trusted things guarded by the TPM are
no longer trustable.

BUG=chromium-os:31974
TEST=manual

crossystem
  // both flags initially 0
crossystem clear_tpm_owner_request=1
crossystem clear_tpm_owner_done=1
  // request=1, done=0; done can be cleared but not set by crossystem
reboot
tpmc getownership
  // owned=no
crossystem
  // request=0, done=1
crossystem clear_tpm_owner_done=0
crossystem
  // both flags 0 again

Signed-off-by: Randall Spangler <rspangler@chromium.org>
Change-Id: I49f83f3c39c3efc3945116c51a241d255c2e42cd
Reviewed-on: https://gerrit.chromium.org/gerrit/25646

firmware/lib/include/rollback_index.h

@@ -1,4 +1,4 @@
-/* Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  *
@@ -70,6 +70,7 @@ uint32_t RollbackS3Resume(void);
 /* This must be called. */
 uint32_t RollbackFirmwareSetup(int recovery_mode, int is_hw_dev,
                                int disable_dev_request,
+                               int clear_tpm_owner_request,
                                /* two outputs on success */
                                int *is_virt_dev, uint32_t *tpm_version);
 
@@ -118,7 +119,8 @@ uint32_t OneTimeInitializeTPM(RollbackSpaceFirmware* rsf,
 /* SetupTPM starts the TPM and establishes the root of trust for the
  * anti-rollback mechanism. */
 uint32_t SetupTPM(int recovery_mode, int developer_mode,
-                  int disable_dev_request, RollbackSpaceFirmware* rsf);
+                  int disable_dev_request, int clear_tpm_owner_request,
+                  RollbackSpaceFirmware* rsf);
 
 /* Utility function to turn the virtual dev-mode flag on or off. 0=off, 1=on */
 uint32_t SetVirtualDevMode(int val);