crossystem: add a hwid override mechanism from chromeos-config

Devices which do not use chromeos firmware (e.g., reven) do not have a
GBB section nor firmware to expose this data via ACPI/device-tree.
However, a hwid is still required for auto-update, UMA, etc.

CL:3118810 adds a new property to the schema for /:hwid-override.
This CL makes it so when that property is set, ACPI/device-tree is not
probed for the HWID, and it is instead set via cros_config.

BUG=b:195007267
BRANCH=none
TEST=build image for reven with a hwid override
     # crossystem hwid
     REVEN-ANAE A6A-A7I

Signed-off-by: Jack Rosenthal <jrosenth@chromium.org>
Change-Id: I3c1255b257f914b02dfb8ba53dd275892df1a526
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/3119046
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Yong Hong <yhong@chromium.org>

1 files changed, 14 insertions, 1 deletions

diff --git a/host/lib/crossystem.c b/host/lib/crossystem.c
index a2c2104a..02443b15 100644
--- a/host/lib/crossystem.c
+++ b/host/lib/crossystem.c
@@ -13,6 +13,7 @@
 #include "2common.h"
 #include "2nvstorage.h"
 #include "2sysincludes.h"
+#include "chromeos_config.h"
 #include "crossystem_arch.h"
 #include "crossystem.h"
 #include "crossystem_vbnv.h"
@@ -490,7 +491,19 @@ int VbGetSystemPropertyInt(const char *name)
 const char *VbGetSystemPropertyString(const char *name, char *dest,
 				      size_t size)
 {
-	/* Check architecture-dependent properties first */
+	/* Check for HWID override via cros_config */
+	if (!strcasecmp(name, "hwid")) {
+		char *hwid_override;
+
+		if (chromeos_config_get_string("/", "hwid-override",
+					       &hwid_override) == VB2_SUCCESS) {
+			StrCopy(dest, hwid_override, size);
+			free(hwid_override);
+			return dest;
+		}
+	}
+
+	/* Check architecture-dependent properties */
 	if (VbGetArchPropertyString(name, dest, size))
 		return dest;