make_dev_firmware.sh supports switching EC RO key

For the EC supporting EFS boot, the RO section contains a
public key, and the RW is signed. For running FAFT, should
replace the RO key to a known one (the dev key under
vboot_reference), such that FAFT tests can resign the RW
using a known private key.

For BIOS image, we use make_dev_firmware.sh to do a similar
job to replace the key in BIOS. This CL makes the
make_dev_firmware script support changing EC key.

BUG=b:71769443
BRANCH=none
TEST=Modify files
$ # Check the original BIOS and EC images
$ futility show ec.bin
$ futility show bios.bin
$ ./make_dev_firmware.sh --change_ec -f bios.bin -t new_bios.bin \
  -e ec.bin -o new_ec.bin --backup_dir backup
$ # Check the new images, using new keys and verification succeeded
$ futility show new_ec.bin
$ futility show new_bios.bin

TEST=Modify live firmware
$ ./make_dev_firmware.sh --change_ec
And then run firmware_ECUpdateId with a Type-C charger.

TEST=Run sign_official_build.sh
$ sign_official_build.sh recovery recovery_image.bin \
~/trunk/src/platform/vboot_reference/tests/devkeys /tmp/out.bin

TEST=make runalltests

Change-Id: Id51e2c411a4e6d016e619cec91453ce918b7fff7
Reviewed-on: https://chromium-review.googlesource.com/889406
Commit-Ready: Wai-Hong Tam <waihong@google.com>
Tested-by: Wai-Hong Tam <waihong@google.com>
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>

1 files changed, 32 insertions, 1 deletions

diff --git a/scripts/image_signing/common_minimal.sh b/scripts/image_signing/common_minimal.sh
index c130b918..43dfd109 100644
--- a/scripts/image_signing/common_minimal.sh
+++ b/scripts/image_signing/common_minimal.sh
@@ -10,7 +10,8 @@
 # Determine script directory
 SCRIPT_DIR=$(dirname $0)
 PROG=$(basename $0)
-GPT=${GPT:-"cgpt"}
+: ${GPT:=cgpt}
+: ${FUTILITY:=futility}
 
 # The tag when the rootfs is changed.
 TAG_NEEDS_TO_BE_SIGNED="/root/.need_to_be_signed"
@@ -349,6 +350,31 @@ rw_mount_disabled() {
   return 1
 }
 
+# Functions for CBFS management
+# ----------------------------------------------------------------------------
+
+# Get the compression algorithm used for the given CBFS file.
+# Args: INPUT_CBFS_IMAGE CBFS_FILE_NAME
+get_cbfs_compression() {
+  cbfstool "$1" print -r "FW_MAIN_A" | awk -vname="$2" '$1 == name {print $5}'
+}
+
+# Store a file in CBFS.
+# Args: INPUT_CBFS_IMAGE INPUT_FILE CBFS_FILE_NAME
+store_file_in_cbfs() {
+  local image="$1"
+  local file="$2"
+  local name="$3"
+  local compression=$(get_cbfs_compression "$1" "${name}")
+  cbfstool "${image}" remove -r "FW_MAIN_A,FW_MAIN_B" -n "${name}" || return
+  # This add can fail if
+  # 1. Size of a signature after compression is larger
+  # 2. CBFS is full
+  # These conditions extremely unlikely become true at the same time.
+  cbfstool "${image}" add -r "FW_MAIN_A,FW_MAIN_B" -t "raw" \
+    -c "${compression}" -f "${file}" -n "${name}" || return
+}
+
 # Misc functions
 # ----------------------------------------------------------------------------
 
@@ -385,4 +411,9 @@ no_chronos_password() {
   fi
 }
 
+# Returns true if given ec.bin is signed or false if not.
+is_ec_rw_signed() {
+  ${FUTILITY} dump_fmap "$1" | grep -q KEY_RO
+}
+
 trap "cleanup_temps_and_mounts" EXIT