chromeos/vboot: provide support for x86 memory init verification

For x86 systems which resume through the reset vector one needs to
ensure the the RW slot taken at resume time matches the one at
boot time. The reason is that any assets pulled out of the boot
media need to match how the platform previously booted. To do
that one needs obtain the hash digest of the chosen slot, and it
needs to be saved in a secure place on the normal boot path. On
resume one needs to retrieve the hash digest back to compare it
with the chosen slot. If they don't match resuming won't be
possible.

BUG=chrome-os-partner:46049
BRANCH=glados
TEST=Suspended and resumed on chell. Also, tested with an EC build
     which returns a bad hash to ensure that is properly caught.
CQ-DEPEND=CL:323460

Change-Id: I90ce26813b67f46913aa4026b42d9490a564bb6c
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 01a42c0ecfc6d60d1d2e5e36a86781d91d5c47a9
Original-Change-Id: I6c6bdce7e06712bc06cc620a3d7a6a6250c59c95
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/323500
Original-Reviewed-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/13574
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/vendorcode/google/chromeos/vboot_common.h b/src/vendorcode/google/chromeos/vboot_common.h
index fbffc29d54..a658d62ab4 100644
--- a/src/vendorcode/google/chromeos/vboot_common.h
+++ b/src/vendorcode/google/chromeos/vboot_common.h
@@ -46,6 +46,24 @@ int vboot_recovery_reason(void);
 
 void vboot_reboot(void);
 
+/*
+ * Save the provided hash digest to a secure location to check against in
+ * the resume path. Returns 0 on success, < 0 on error.
+ */
+int vboot_save_hash(void *digest, size_t digest_size);
+
+/*
+ * Retrieve the previously saved hash digest.  Returns 0 on success,
+ * < 0 on error.
+ */
+int vboot_retrieve_hash(void *digest, size_t digest_size);
+
+/*
+ * Determine if the platform is resuming from suspend. Returns 0 when
+ * not resuming, > 0 if resuming, and < 0 on error.
+ */
+int vboot_platform_is_resuming(void);
+
 /* Main logic for verified boot. verstage() is the stage entry point
  * while the verstage_main() is just the core logic. */
 void verstage_main(void);