vboot/secdata: rewrite rollback_index and centralize reads/writes

In current kernel verification code, secdata reads and writes
are spread throughout the code.  vboot2's design is to use
vb2_context.secdata_* for storing the state of secdata spaces,
and have the caller (depthcharge) read/save this field when
necessary.

Centralize secdata reads/writes into the functions of
secdata_tpm.c, previously known as rollback_index.c.
Functions which directly read/write to the TPM space are modified
to use vb2_secdata_*_get and vb2_secdata_*_set.

The secure spaces get read/flushed by functions in
vboot_api_kernel.c.  These calls and the underlying functions
from secdata_tpm.c will eventually be relocated to depthcharge.

Create a new external function vb2ex_commit_data, which commits
any modified nvdata/secdata.  Currently the depthcharge
implementation of this function only writes nvdata, but once
secdata TPM drivers have been migrated from vboot_reference to
depthcharge, it will also commit these data spaces.

This CL also removes the VbExNvStorageRead call from
vb2_kernel_setup, and the data is instead read in depthcharge
CL:1819379, right before calling VbSelectAndLoadKernel.

As such, both the VbExNvStorageRead and VbExNvStorageWrite
functions may be removed.

Finally, create a vb2_secdata_kernel_lock function, which should
be used right before attempting to leave vboot (by booting an OS
or chainloading to another firmware).  This should eventually be
exposed as a vb2ex_ API function and relocated to depthcharge.

BUG=b:124141368, chromium:972956, chromium:1006689
TEST=make clean && make runtests
BRANCH=none

Change-Id: Ifbfb21122af0bf85e22a6d3a0d48a1db7f7c25b7
Signed-off-by: Joel Kitching <kitching@google.com>
Cq-Depend: chromium:1819380, chromium:1939168
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1728298
Tested-by: Joel Kitching <kitching@chromium.org>
Reviewed-by: Andrey Pronin <apronin@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Commit-Queue: Joel Kitching <kitching@chromium.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/firmware/lib/vboot_display.c b/firmware/lib/vboot_display.c
index d3daf658..0c62a86d 100644
--- a/firmware/lib/vboot_display.c
+++ b/firmware/lib/vboot_display.c
@@ -383,11 +383,11 @@ vb2_error_t VbCheckDisplayKey(struct vb2_context *ctx, uint32_t key,
 		/*
 		 * Non-manual recovery mode is meant to be left via three-finger
 		 * salute (into manual recovery mode). Need to commit nvdata
-		 * changes immediately.
+		 * changes immediately.  Ignore commit errors in recovery mode.
 		 */
 		if ((ctx->flags & VB2_CONTEXT_RECOVERY_MODE) &&
 		    !vb2_allow_recovery(ctx))
-			vb2_nv_commit(ctx);
+			 vb2_commit_data(ctx);
 
 		/* Force redraw of current screen */
 		return VbDisplayScreen(ctx, disp_current_screen, 1, data);