Make signing script re-sign Firmware AU payload, and update rootfs hash.

scripts/image_signing/sign_official_build.sh

Index: scripts/image_signing/sign_official_build.sh
diff --git a/scripts/image_signing/sign_official_build.sh b/scripts/image_signing/sign_official_build.sh
index 01e581badb54e3775a47d1e39b0749d2cc2e60b3..143d945acdbf61f35550bf61e729e33e98f50a27 100755
--- a/scripts/image_signing/sign_official_build.sh
+++ b/scripts/image_signing/sign_official_build.sh
@@ -5,7 +5,15 @@
 # found in the LICENSE file.
 
 # Sign the final build image using the "official" keys.
-
+#
+# Prerequisite tools needed in the system path:
+#
+#  gbb_utility (from src/platform/vboot_reference)
+#  vbutil_kernel (from src/platform/vboot_reference)
+#  cgpt (from src/platform/vboot_reference)
+#  dump_kernel_config (from src/platform/vboot_reference)
+#  verity (from src/platform/verity)
+#
 # Usage: sign_for_ssd.sh <type> input_image /path/to/keys/dir output_image
 # 
 # where <type> is one of:
@@ -35,6 +43,129 @@ INPUT_IMAGE=$2
 KEY_DIR=$3
 OUTPUT_IMAGE=$4
 
+# Re-calculate rootfs hash, update rootfs and kernel command line.
+# Args: IMAGE KEYBLOCK PRIVATEKEY
+recalculate_rootfs_hash() {
+  local image=$1  # Input image.
+  local keyblock=$2  # Keyblock for re-generating signed kernel partition
+  local signprivate=$3  # Private key to use for signing.
+
+  # First, grab the existing kernel partition and get the kernel config.
+  temp_kimage=$(make_temp_file)
+  extract_image_partition ${image} 2 ${temp_kimage}
+  local kernel_config=$(sudo dump_kernel_config ${temp_kimage})
+  local dm_config=$(echo $kernel_config |
+    sed -e 's/.*dm="\([^"]*\)".*/\1/g' |
+    cut -f2- -d,)
+  # We extract dm=... portion of the config command line. Here's an example:
+  #
+  # dm="0 2097152 verity ROOT_DEV HASH_DEV 2097152 1 \
+  # sha1 63b7ad16cb9db4b70b28593f825aa6b7825fdcf2"
+  #
+
+  if [ -z ${dm_config} ]; then
+    echo "WARNING: Couldn't grab dm_config. Aborting rootfs hash calculation"
+    return
+  fi
+  local rootfs_sectors=$(echo ${dm_config} | cut -f2 -d' ')
+  local root_dev=$(echo ${dm_config} | cut -f4 -d ' ')
+  local hash_dev=$(echo ${dm_config} | cut -f5 -d ' ')
+  local verity_depth=$(echo ${dm_config} | cut -f7 -d' ')
+  local verity_algorithm=$(echo ${dm_config} | cut -f8 -d' ')
+
+  # Mount the rootfs and run the verity tool on it.
+  local hash_image=$(make_temp_file)
+  local rootfs_img=$(make_temp_file)
+  extract_image_partition ${image} 3 ${rootfs_img}
+  local table="vroot none ro,"$(sudo verity create \
+    ${verity_depth} \
+    ${verity_algorithm} \
+    ${rootfs_img} \
+    $((rootfs_sectors / 8)) \
+    ${hash_image})
+  # Reconstruct new kernel config command line and replace placeholders.
+  table="$(echo "$table" |
+    sed -s "s|ROOT_DEV|${root_dev}|g;s|HASH_DEV|${hash_dev}|")"
+  kernel_config=$(echo ${kernel_config} |
+    sed -e 's#\(.*dm="\)\([^"]*\)\(".*\)'"#\1${table}\3#g")
+
+  # Overwrite the appended hashes in the rootfs
+  local temp_config=$(make_temp_file)
+  echo ${kernel_config} >${temp_config}
+  dd if=${hash_image} of=${rootfs_img} bs=512 \
+    seek=${rootfs_sectors} conv=notrunc
+
+  # Re-calculate kernel partition signature and command line.
+  local updated_kimage=$(make_temp_file)
+  vbutil_kernel --repack ${updated_kimage} \
+    --keyblock ${keyblock} \
+    --signprivate ${signprivate} \
+    --oldblob ${temp_kimage} \
+    --config ${temp_config}
+  
+  replace_image_partition ${image} 2 ${updated_kimage}
+  replace_image_partition ${image} 3 ${rootfs_img}
+}
+
+# Extracts the firmware update binaries from the a firmware update
+# shell ball (generated by src/platform/firmware/pack_firmware.sh)
+# Args: INPUT_SCRIPT OUTPUT_DIR
+get_firmwarebin_from_shellball() {
+  local input=$1
+  local output_dir=$2  
+  uudecode -o - ${input} | tar -C ${output_dir} -zxf - 2>/dev/null || \
+    echo "Extracting firmware autoupdate failed.
+Try re-running with FW_NOUPDATE=1." && exit 1
+}
+
+# Re-sign the firmware AU payload inside the image rootfs with a new keys.
+# Args: IMAGE
+resign_firmware_payload() {
+  local image=$1
+
+  # Grab firmware image from the autoupdate shellball.
+  local rootfs_dir=$(make_temp_dir)
+  mount_image_partition ${image} 3 ${rootfs_dir}
+  
+  local shellball_dir=$(make_temp_dir)
+  get_firmwarebin_from_shellball \
+    ${rootfs_dir}/usr/sbin/chromeos-firmwareupdate ${shellball_dir}
+
+  temp_outfd=$(make_temp_file)
+  # Replace the root key in the GBB
+  # TODO(gauravsh): Remove when we lock down the R/O portion of firmware.
+  gbb_utility -s \
+    --rootkey=${KEY_DIR}/root_key.vbpubk \
+    --recoverykey=${KEY_DIR}/recovery_key.vbpubk \
+    ${shellball_dir}/bios.bin ${temp_outfd}
+
+  # Resign the firmware with new keys
+  ${SCRIPT_DIR}/resign_firmwarefd.sh ${temp_outfd} ${temp_dir}/bios.bin \
+    ${KEY_DIR}/firmware_data_key.vbprivk \
+    ${KEY_DIR}/firmware.keyblock \
+    ${KEY_DIR}/kernel_subkey.vbpubk
+
+  # Replace MD5 checksum in the firmware update payload
+  newfd_checksum=$(md5sum ${shellball_dir}/bios.bin | cut -f 1 -d ' ')
+  temp_version=$(make_temp_file)
+  cat ${shellball_dir}/VERSION | 
+  sed -e "s#\(.*\)\ \(.*bios.bin.*\)#${newfd_checksum}\ \2#" > ${temp_version}
+  sudo cp ${temp_version} ${shellball_dir}/VERSION
+
+  # Re-generate firmware_update.tgz and copy over encoded archive in
+  # the original shell ball.
+  new_fwblob=$(make_temp_file)
+  tar zcf - -C ${shellball_dir} . | \
+    uuencode firmware_package.tgz > ${new_fwblob}
+  new_shellball=$(make_temp_file)
+  cat ${rootfs_dir}/usr/sbin/chromeos-firmwareupdate | \
+    sed -e '/^begin .*firmware_package/,/end/D' | \
+    cat - ${new_fwblob} >${new_shellball}
+  sudo cp ${new_shellball} ${rootfs_dir}/usr/sbin/chromeos-firmwareupdate
+  # Force unmount of the image as it is needed later.
+  sudo umount -d ${rootfs_dir}
+  echo "Re-signed firmware AU payload in $image"
+}
 
 # Generate the SSD image
 sign_for_ssd() {
@@ -51,18 +182,15 @@ sign_for_recovery() {
     ${KEY_DIR}/recovery_kernel.keyblock 
 
   # Now generate the installer vblock with the SSD keys.
-  temp_kimage=$(mktemp)
-  trap "rm -f ${temp_kimage}" EXIT
-  temp_out_vb=$(mktemp)
-  trap "rm -f ${temp_out_vb}" EXIT
+  temp_kimage=$(make_temp_file)
+  temp_out_vb=$(make_temp_file)
   extract_image_partition ${OUTPUT_IMAGE} 2 ${temp_kimage}
   ${SCRIPT_DIR}/resign_kernel_partition.sh ${temp_kimage} ${temp_out_vb} \
     ${KEY_DIR}/kernel_data_key.vbprivk \
     ${KEY_DIR}/kernel.keyblock
 
   # Copy the installer vblock to the stateful partition.
-  local stateful_dir=$(mktemp -d)
-  trap "sudo umount -d $stateful_dir; rm -rf $stateful_dir" EXIT
+  local stateful_dir=$(make_temp_dir)
   mount_image_partition ${OUTPUT_IMAGE} 1 ${stateful_dir}
   sudo cp ${temp_out_vb} ${stateful_dir}/vmlinuz_hd.vblock
 
@@ -77,15 +205,26 @@ sign_for_factory_install() {
   echo "Output signed factory install image to ${OUTPUT_IMAGE}"
 }
 
+if [ ! "${FW_NOUPDATE}" == "1" ]; then
+  resign_firmware_payload ${INPUT_IMAGE}
+fi
+
 if [ "${TYPE}" == "ssd" ]; then
+  recalculate_rootfs_hash ${INPUT_IMAGE} \
+    ${KEY_DIR}/kernel.keyblock \
+    ${KEY_DIR}/kernel_data_key.vbprivk
   sign_for_ssd
 elif [ "${TYPE}" == "recovery" ]; then
+  recalculate_rootfs_hash ${INPUT_IMAGE} \
+    ${KEY_DIR}/recovery_kernel.keyblock \
+    ${KEY_DIR}/recovery_kernel_data_key.vbprivk
   sign_for_recovery
 elif [ "${TYPE}" == "install" ]; then
+  recalculate_rootfs_hash ${INPUT_IMAGE} \
+    ${KEY_DIR}/installer_kernel.keyblock \
+    ${KEY_DIR}/recovery_kernel_data_key.vbprivk
   sign_for_factory_install
 else
   echo "Invalid type ${TYPE}"
   exit 1
 fi
-  
-