scripts/image_signing/make_dev_firmware.sh - chromiumos/platform/vboot_reference - Git at Google

 #!/bin/sh
 #
 # Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #
 # This script can change key (usually developer keys) in a firmware binary
 # image or system live firmware (EEPROM), and assign proper HWID, BMPFV as well.

 SCRIPT_BASE="$(dirname "$0")"
 . "$SCRIPT_BASE/common_minimal.sh"
 load_shflags || exit 1

 # Constants used by DEFINE_*
 VBOOT_BASE='/usr/share/vboot'
 DEFAULT_KEYS_FOLDER="$VBOOT_BASE/devkeys"
 DEFAULT_BMPFV_FILE="<auto>"
 DEFAULT_BACKUP_FOLDER='/mnt/stateful_partition/backups'
 DEFAULT_FIRMWARE_UPDATER='/usr/sbin/chromeos-firmwareupdate'

 # DEFINE_string name default_value description flag
 DEFINE_string from "" "Path of input file (empty for system live firmware)" "f"
 DEFINE_string to "" "Path of output file (empty for system live firmware)" "t"
 DEFINE_string keys "$DEFAULT_KEYS_FOLDER" "Path to folder of dev keys" "k"
 DEFINE_string bmpfv "$DEFAULT_BMPFV_FILE" \
   "Path to the new bitmaps, <auto> to extract from system, empty to keep." ""
 DEFINE_boolean force_backup \
   $FLAGS_TRUE "Create backup even if source is not live" ""
 DEFINE_string backup_dir \
   "$DEFAULT_BACKUP_FOLDER" "Path of directory to store firmware backups" ""

 # Parse command line
 FLAGS "$@" || exit 1
 eval set -- "$FLAGS_ARGV"

 # Globals
 # ----------------------------------------------------------------------------
 set -e

 # the image we are (temporary) working with
 IMAGE="$(make_temp_file)"
 IMAGE="$(readlink -f "$IMAGE")"

 # a log file to keep the output results of executed command
 EXEC_LOG="$(make_temp_file)"

 # Functions
 # ----------------------------------------------------------------------------

 # Disables write protection status registers
 disable_write_protection() {
   # No need to change WP status in file mode
   if [ -n "$FLAGS_to" ]; then
     return $FLAGS_TRUE
   fi

   # --wp-disable command may return success even if WP is still enabled,
   # so we should use --wp-status to verify the results.
   echo "Disabling system software write protection status..."
   (flashrom --wp-disable && flashrom --wp-status) 2>&1 |
     tee "$EXEC_LOG" |
     grep -q '^WP: .* is disabled\.$'
 }

 # Reads $IMAGE from $FLAGS_from
 read_image() {
   if [ -z "$FLAGS_from" ]; then
     echo "Reading system live firmware..."
     if is_debug_mode; then
       flashrom -V -r "$IMAGE"
     else
       flashrom -r "$IMAGE" >"$EXEC_LOG" 2>&1
     fi
   else
     debug_msg "reading from file: $FLAGS_from"
     cp -f "$FLAGS_from" "$IMAGE"
   fi
 }

 # Writes $IMAGE to $FLAGS_to
 write_image() {
   if [ -z "$FLAGS_to" ]; then
     echo "Writing system live firmware..."
     # TODO(hungte) we can enable partial write to make this faster
     if is_debug_mode; then
       flashrom -V -w "$IMAGE"
     else
       flashrom -w "$IMAGE" >"$EXEC_LOG" 2>&1
     fi
   else
     debug_msg "writing to file: $FLAGS_to"
     cp -f "$IMAGE" "$FLAGS_to"
     chmod a+r "$FLAGS_to"
   fi
 }

 # Converts HWID from $1 to proper format with "DEV" extension
 echo_dev_hwid() {
   local hwid="$1"
   local hwid_no_dev="${hwid% DEV}"

   # NOTE: Some DEV firmware image files may put GUID in HWID.
   # These are not officially supported and they will see "{GUID} DEV".
   # Also there's some length limitation in chromeos_acpi/HWID, so
   # a "{GUID} DEV" will become "{GUID} " in that case.

   if [ "$hwid" != "$hwid_no_dev" ]; then
     hwid="$hwid_no_dev"
   fi
   local hwid_dev="$hwid DEV"
   debug_msg "echo_dev_hwid: [$1] -> [$hwid_dev]"
   echo "$hwid_dev"
 }

 # Explores compatible firmware bitmaps
 explore_bmpfv() {
   local tmp_folder=""

   if [ -s "$DEFAULT_FIRMWARE_UPDATER" ]; then
     # try to extract from built-in firmware updater
     debug_msg "found default firmware updater, trying to fetch bitmap..."
     tmp_folder=$("$DEFAULT_FIRMWARE_UPDATER" --sb_extract | sed "s'[^/]*''")
     debug_msg "updater resources extrated to: $tmp_folder"

     if [ -d "$tmp_folder" -a -s "$tmp_folder/bios.bin" ]; then
       new_bmpfv="$tmp_folder/bmpfv.bin"
       echo "$new_bmpfv"
       gbb_utility --bmpfv="$new_bmpfv" "$tmp_folder/bios.bin" >/dev/null 2>&1
     else
       debug_msg "failed to find valid BIOS image file."
     fi
   else
     debug_msg "no firmware updater in system. not changing bitmaps."
   fi
 }

 # Main
 # ----------------------------------------------------------------------------
 main() {
   # Check parameters
   local root_pubkey="$FLAGS_keys/root_key.vbpubk"
   local recovery_pubkey="$FLAGS_keys/recovery_key.vbpubk"
   local firmware_keyblock="$FLAGS_keys/firmware.keyblock"
   local firmware_prvkey="$FLAGS_keys/firmware_data_key.vbprivk"
   local dev_firmware_keyblock="$FLAGS_keys/dev_firmware.keyblock"
   local dev_firmware_prvkey="$FLAGS_keys/dev_firmware_data_key.vbprivk"
   local kernel_sub_pubkey="$FLAGS_keys/kernel_subkey.vbpubk"
   local new_bmpfv="$FLAGS_bmpfv"
   local is_from_live=0
   local backup_image=
   local opt_bmpfv=""

   if [ "$new_bmpfv" = "$DEFAULT_BMPFV_FILE" ]; then
     new_bmpfv=$(explore_bmpfv) &&
       debug_msg "Using bitmaps from $new_bmpfv"
   fi

   debug_msg "Prerequisite check"
   ensure_files_exist \
     "$root_pubkey" \
     "$recovery_pubkey" \
     "$firmware_keyblock" \
     "$firmware_prvkey" \
     "$kernel_sub_pubkey" ||
     exit 1

   if [ -n "$new_bmpfv" ]; then
     opt_bmpfv="--bmpfv=$new_bmpfv"
     ensure_files_exist "$new_bmpfv" || exit 1
   fi

   if [ -z "$FLAGS_from" ]; then
     is_from_live=1
   else
     ensure_files_exist "$FLAGS_from" || exit 1
   fi

   debug_msg "Checking software write protection status"
   disable_write_protection ||
     if is_debug_mode; then
       err_die "Failed to disable WP. Diagnose Message: $(cat "$EXEC_LOG")"
     else
       err_die "Write protection is still enabled. " \
               "Please verify that hardware write protection is disabled."
     fi

   debug_msg "Pulling image to $IMAGE"
   (read_image && [ -s "$IMAGE" ]) ||
     err_die "Failed to read image. Error message: $(cat "$EXEC_LOG")"

   debug_msg "Prepare to backup the file"
   if [ -n "$is_from_live" -o $FLAGS_force_backup = $FLAGS_TRUE ]; then
     backup_image="$(make_temp_file)"
     debug_msg "Creating backup file to $backup_image..."
     cp -f "$IMAGE" "$backup_image"
   fi

   debug_msg "Detecting developer firmware keyblock"
   local expanded_firmware_dir="$(make_temp_dir)"
   local use_devfw_keyblock="$FLAGS_FALSE"
   (cd "$expanded_firmware_dir"; dump_fmap -x "$IMAGE" >/dev/null 2>&1) ||
     err_die "Failed to extract firmware image."
   if [ -f "$expanded_firmware_dir/VBLOCK_A" ]; then
     local has_dev=$FLAGS_TRUE has_norm=$FLAGS_TRUE
     # In output of vbutil_keyblock, "!DEV" means "bootable on normal mode" and
     # "DEV" means "bootable on developer mode". Here we try to match the pattern
     # in output of vbutil_block, and disable the flags (has_dev, has_norm) if
     # the pattern was not found.
     vbutil_keyblock --unpack "$expanded_firmware_dir/VBLOCK_A" |
       grep -qw '!DEV' || has_norm=$FLAGS_FALSE
     vbutil_keyblock --unpack "$expanded_firmware_dir/VBLOCK_A" |
       grep -qw '[^!]DEV' || has_dev=$FLAGS_FALSE
     if [ "$has_norm" = "$FLAGS_FALSE" -a "$has_dev" = "$FLAGS_TRUE" ]; then
       use_devfw_keyblock=$FLAGS_TRUE
     fi
   fi

   if [ "$use_devfw_keyblock" = "$FLAGS_TRUE" ]; then
     echo "Using keyblocks (developer, normal)..."
   else
     echo "Using keyblocks (normal, normal)..."
     dev_firmware_prvkey="$firmware_prvkey"
     dev_firmware_keyblock="$firmware_keyblock"
   fi

   # TODO(hungte) We can use vbutil_firmware to check if the current firmware is
   # valid so that we know keys and vbutil_firmware are all working fine.

   echo "Preparing new firmware image..."
   debug_msg "Extract current HWID and rootkey"
   local old_hwid
   old_hwid="$(gbb_utility --get --hwid "$IMAGE" 2>"$EXEC_LOG" |
               grep '^hardware_id:' |
               sed 's/^hardware_id: //')"

   debug_msg "Decide new HWID"
   if [ -z "$old_hwid" ]; then
     err_die "Cannot find current HWID. (message: $(cat "$EXEC_LOG"))"
   fi
   local new_hwid="$(echo_dev_hwid "$old_hwid")"

   debug_msg "Replace GBB parts (gbb_utility allows changing on-the-fly)"
   gbb_utility --set \
     --hwid="$new_hwid" \
     --rootkey="$root_pubkey" \
     --recoverykey="$recovery_pubkey" \
     $opt_bmpfv \
     "$IMAGE" >"$EXEC_LOG" 2>&1 ||
     err_die "Failed to change GBB Data. (message: $(cat "$EXEC_LOG"))"

   debug_msg "Resign the firmware code (A/B) with new keys"
   local unsigned_image="$(make_temp_file)"
   cp -f "$IMAGE" "$unsigned_image"
   # TODO(hungte) derive kernel key and preamble flag from existing firmware
   "$SCRIPT_BASE/resign_firmwarefd.sh" \
     "$unsigned_image" \
     "$IMAGE" \
     "$firmware_prvkey" \
     "$firmware_keyblock" \
     "$dev_firmware_prvkey" \
     "$dev_firmware_keyblock" \
     "$kernel_sub_pubkey" >"$EXEC_LOG" 2>&1 ||
     err_die "Failed to re-sign firmware. (message: $(cat "$EXEC_LOG"))"
     if is_debug_mode; then
       cat "$EXEC_LOG"
     fi

   # TODO(hungte) compare if the image really needs to be changed.

   debug_msg "Check if we need to make backup file(s)"
   if [ -n "$backup_image" ]; then
     local backup_hwid_name="$(echo "$old_hwid" | sed 's/ /_/g')"
     local backup_date_time="$(date +'%Y%m%d_%H%M%S')"
     local backup_file_name="firmware_${backup_hwid_name}_${backup_date_time}.fd"
     local backup_file_path="$FLAGS_backup_dir/$backup_file_name"
     if mkdir -p "$FLAGS_backup_dir" &&
        cp -f "$backup_image" "$backup_file_path"; then
       true
     elif cp -f "$backup_image" "/tmp/$backup_file_name"; then
       backup_file_path="/tmp/$backup_file_name"
     else
       backup_file_path=''
     fi
     if [ -n "$backup_file_path" -a -s "$backup_file_path" ]; then
       # TODO(hungte) maybe we can wrap the flashrom by 'make_dev_firmware.sh -r'
       # so that the only command to remember would be make_dev_firmware.sh.
       echo "
       Backup of current firmware image is stored in:
         $backup_file_path
       Please copy the backup file to a safe place ASAP.

       To stop using devkeys and restore original firmware, execute command:
         flashrom -w [PATH_TO_BACKUP_IMAGE]
       Ex: flashrom -w $backup_file_path
       "
     else
       echo "WARNING: Cannot create file in $FLAGS_backup_dir... Ignore backups."
     fi
   fi

   # TODO(hungte) use vbutil_firmware to check if the new firmware is valid.
   # Or, do verification in resign_firmwarefd.sh and trust it.

   debug_msg "Write the image"
   write_image ||
     err_die "Failed to write image. Error message: $(cat "$EXEC_LOG")"

   debug_msg "Complete."
   if [ -z "$FLAGS_to" ]; then
     echo "Successfully changed firmware to Developer Keys. New HWID: $new_hwid"
   else
     echo "Firmware '$FLAGS_to' now uses Developer Keys. New HWID: $new_hwid"
   fi
 }

 main
	#!/bin/sh
	#
	# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
	# Use of this source code is governed by a BSD-style license that can be
	# found in the LICENSE file.
	#
	# This script can change key (usually developer keys) in a firmware binary
	# image or system live firmware (EEPROM), and assign proper HWID, BMPFV as well.

	SCRIPT_BASE="$(dirname "$0")"
	. "$SCRIPT_BASE/common_minimal.sh"
	load_shflags \|\| exit 1

	# Constants used by DEFINE_*
	VBOOT_BASE='/usr/share/vboot'
	DEFAULT_KEYS_FOLDER="$VBOOT_BASE/devkeys"
	DEFAULT_BMPFV_FILE="<auto>"
	DEFAULT_BACKUP_FOLDER='/mnt/stateful_partition/backups'
	DEFAULT_FIRMWARE_UPDATER='/usr/sbin/chromeos-firmwareupdate'

	# DEFINE_string name default_value description flag
	DEFINE_string from "" "Path of input file (empty for system live firmware)" "f"
	DEFINE_string to "" "Path of output file (empty for system live firmware)" "t"
	DEFINE_string keys "$DEFAULT_KEYS_FOLDER" "Path to folder of dev keys" "k"
	DEFINE_string bmpfv "$DEFAULT_BMPFV_FILE" \
	"Path to the new bitmaps, <auto> to extract from system, empty to keep." ""
	DEFINE_boolean force_backup \
	$FLAGS_TRUE "Create backup even if source is not live" ""
	DEFINE_string backup_dir \
	"$DEFAULT_BACKUP_FOLDER" "Path of directory to store firmware backups" ""

	# Parse command line
	FLAGS "$@" \|\| exit 1
	eval set -- "$FLAGS_ARGV"

	# Globals
	# ----------------------------------------------------------------------------
	set -e

	# the image we are (temporary) working with
	IMAGE="$(make_temp_file)"
	IMAGE="$(readlink -f "$IMAGE")"

	# a log file to keep the output results of executed command
	EXEC_LOG="$(make_temp_file)"

	# Functions
	# ----------------------------------------------------------------------------

	# Disables write protection status registers
	disable_write_protection() {
	# No need to change WP status in file mode
	if [ -n "$FLAGS_to" ]; then
	return $FLAGS_TRUE
	fi

	# --wp-disable command may return success even if WP is still enabled,
	# so we should use --wp-status to verify the results.
	echo "Disabling system software write protection status..."
	(flashrom --wp-disable && flashrom --wp-status) 2>&1 \|
	tee "$EXEC_LOG" \|
	grep -q '^WP: .* is disabled\.$'
	}

	# Reads $IMAGE from $FLAGS_from
	read_image() {
	if [ -z "$FLAGS_from" ]; then
	echo "Reading system live firmware..."
	if is_debug_mode; then
	flashrom -V -r "$IMAGE"
	else
	flashrom -r "$IMAGE" >"$EXEC_LOG" 2>&1
	fi
	else
	debug_msg "reading from file: $FLAGS_from"
	cp -f "$FLAGS_from" "$IMAGE"
	fi
	}

	# Writes $IMAGE to $FLAGS_to
	write_image() {
	if [ -z "$FLAGS_to" ]; then
	echo "Writing system live firmware..."
	# TODO(hungte) we can enable partial write to make this faster
	if is_debug_mode; then
	flashrom -V -w "$IMAGE"
	else
	flashrom -w "$IMAGE" >"$EXEC_LOG" 2>&1
	fi
	else
	debug_msg "writing to file: $FLAGS_to"
	cp -f "$IMAGE" "$FLAGS_to"
	chmod a+r "$FLAGS_to"
	fi
	}

	# Converts HWID from $1 to proper format with "DEV" extension
	echo_dev_hwid() {
	local hwid="$1"
	local hwid_no_dev="${hwid% DEV}"

	# NOTE: Some DEV firmware image files may put GUID in HWID.
	# These are not officially supported and they will see "{GUID} DEV".
	# Also there's some length limitation in chromeos_acpi/HWID, so
	# a "{GUID} DEV" will become "{GUID} " in that case.

	if [ "$hwid" != "$hwid_no_dev" ]; then
	hwid="$hwid_no_dev"
	fi
	local hwid_dev="$hwid DEV"
	debug_msg "echo_dev_hwid: [$1] -> [$hwid_dev]"
	echo "$hwid_dev"
	}

	# Explores compatible firmware bitmaps
	explore_bmpfv() {
	local tmp_folder=""

	if [ -s "$DEFAULT_FIRMWARE_UPDATER" ]; then
	# try to extract from built-in firmware updater
	debug_msg "found default firmware updater, trying to fetch bitmap..."
	tmp_folder=$("$DEFAULT_FIRMWARE_UPDATER" --sb_extract \| sed "s'[^/]*''")
	debug_msg "updater resources extrated to: $tmp_folder"

	if [ -d "$tmp_folder" -a -s "$tmp_folder/bios.bin" ]; then
	new_bmpfv="$tmp_folder/bmpfv.bin"
	echo "$new_bmpfv"
	gbb_utility --bmpfv="$new_bmpfv" "$tmp_folder/bios.bin" >/dev/null 2>&1
	else
	debug_msg "failed to find valid BIOS image file."
	fi
	else
	debug_msg "no firmware updater in system. not changing bitmaps."
	fi
	}

	# Main
	# ----------------------------------------------------------------------------
	main() {
	# Check parameters
	local root_pubkey="$FLAGS_keys/root_key.vbpubk"
	local recovery_pubkey="$FLAGS_keys/recovery_key.vbpubk"
	local firmware_keyblock="$FLAGS_keys/firmware.keyblock"
	local firmware_prvkey="$FLAGS_keys/firmware_data_key.vbprivk"
	local dev_firmware_keyblock="$FLAGS_keys/dev_firmware.keyblock"
	local dev_firmware_prvkey="$FLAGS_keys/dev_firmware_data_key.vbprivk"
	local kernel_sub_pubkey="$FLAGS_keys/kernel_subkey.vbpubk"
	local new_bmpfv="$FLAGS_bmpfv"
	local is_from_live=0
	local backup_image=
	local opt_bmpfv=""

	if [ "$new_bmpfv" = "$DEFAULT_BMPFV_FILE" ]; then
	new_bmpfv=$(explore_bmpfv) &&
	debug_msg "Using bitmaps from $new_bmpfv"
	fi

	debug_msg "Prerequisite check"
	ensure_files_exist \
	"$root_pubkey" \
	"$recovery_pubkey" \
	"$firmware_keyblock" \
	"$firmware_prvkey" \
	"$kernel_sub_pubkey" \|\|
	exit 1

	if [ -n "$new_bmpfv" ]; then
	opt_bmpfv="--bmpfv=$new_bmpfv"
	ensure_files_exist "$new_bmpfv" \|\| exit 1
	fi

	if [ -z "$FLAGS_from" ]; then
	is_from_live=1
	else
	ensure_files_exist "$FLAGS_from" \|\| exit 1
	fi

	debug_msg "Checking software write protection status"
	disable_write_protection \|\|
	if is_debug_mode; then
	err_die "Failed to disable WP. Diagnose Message: $(cat "$EXEC_LOG")"
	else
	err_die "Write protection is still enabled. " \
	"Please verify that hardware write protection is disabled."
	fi

	debug_msg "Pulling image to $IMAGE"
	(read_image && [ -s "$IMAGE" ]) \|\|
	err_die "Failed to read image. Error message: $(cat "$EXEC_LOG")"

	debug_msg "Prepare to backup the file"
	if [ -n "$is_from_live" -o $FLAGS_force_backup = $FLAGS_TRUE ]; then
	backup_image="$(make_temp_file)"
	debug_msg "Creating backup file to $backup_image..."
	cp -f "$IMAGE" "$backup_image"
	fi

	debug_msg "Detecting developer firmware keyblock"
	local expanded_firmware_dir="$(make_temp_dir)"
	local use_devfw_keyblock="$FLAGS_FALSE"
	(cd "$expanded_firmware_dir"; dump_fmap -x "$IMAGE" >/dev/null 2>&1) \|\|
	err_die "Failed to extract firmware image."
	if [ -f "$expanded_firmware_dir/VBLOCK_A" ]; then
	local has_dev=$FLAGS_TRUE has_norm=$FLAGS_TRUE
	# In output of vbutil_keyblock, "!DEV" means "bootable on normal mode" and
	# "DEV" means "bootable on developer mode". Here we try to match the pattern
	# in output of vbutil_block, and disable the flags (has_dev, has_norm) if
	# the pattern was not found.
	vbutil_keyblock --unpack "$expanded_firmware_dir/VBLOCK_A" \|
	grep -qw '!DEV' \|\| has_norm=$FLAGS_FALSE
	vbutil_keyblock --unpack "$expanded_firmware_dir/VBLOCK_A" \|
	grep -qw '[^!]DEV' \|\| has_dev=$FLAGS_FALSE
	if [ "$has_norm" = "$FLAGS_FALSE" -a "$has_dev" = "$FLAGS_TRUE" ]; then
	use_devfw_keyblock=$FLAGS_TRUE
	fi
	fi

	if [ "$use_devfw_keyblock" = "$FLAGS_TRUE" ]; then
	echo "Using keyblocks (developer, normal)..."
	else
	echo "Using keyblocks (normal, normal)..."
	dev_firmware_prvkey="$firmware_prvkey"
	dev_firmware_keyblock="$firmware_keyblock"
	fi

	# TODO(hungte) We can use vbutil_firmware to check if the current firmware is
	# valid so that we know keys and vbutil_firmware are all working fine.

	echo "Preparing new firmware image..."
	debug_msg "Extract current HWID and rootkey"
	local old_hwid
	old_hwid="$(gbb_utility --get --hwid "$IMAGE" 2>"$EXEC_LOG" \|
	grep '^hardware_id:' \|
	sed 's/^hardware_id: //')"

	debug_msg "Decide new HWID"
	if [ -z "$old_hwid" ]; then
	err_die "Cannot find current HWID. (message: $(cat "$EXEC_LOG"))"
	fi
	local new_hwid="$(echo_dev_hwid "$old_hwid")"

	debug_msg "Replace GBB parts (gbb_utility allows changing on-the-fly)"
	gbb_utility --set \
	--hwid="$new_hwid" \
	--rootkey="$root_pubkey" \
	--recoverykey="$recovery_pubkey" \
	$opt_bmpfv \
	"$IMAGE" >"$EXEC_LOG" 2>&1 \|\|
	err_die "Failed to change GBB Data. (message: $(cat "$EXEC_LOG"))"

	debug_msg "Resign the firmware code (A/B) with new keys"
	local unsigned_image="$(make_temp_file)"
	cp -f "$IMAGE" "$unsigned_image"
	# TODO(hungte) derive kernel key and preamble flag from existing firmware
	"$SCRIPT_BASE/resign_firmwarefd.sh" \
	"$unsigned_image" \
	"$IMAGE" \
	"$firmware_prvkey" \
	"$firmware_keyblock" \
	"$dev_firmware_prvkey" \
	"$dev_firmware_keyblock" \
	"$kernel_sub_pubkey" >"$EXEC_LOG" 2>&1 \|\|
	err_die "Failed to re-sign firmware. (message: $(cat "$EXEC_LOG"))"
	if is_debug_mode; then
	cat "$EXEC_LOG"
	fi

	# TODO(hungte) compare if the image really needs to be changed.

	debug_msg "Check if we need to make backup file(s)"
	if [ -n "$backup_image" ]; then
	local backup_hwid_name="$(echo "$old_hwid" \| sed 's/ /_/g')"
	local backup_date_time="$(date +'%Y%m%d_%H%M%S')"
	local backup_file_name="firmware_${backup_hwid_name}_${backup_date_time}.fd"
	local backup_file_path="$FLAGS_backup_dir/$backup_file_name"
	if mkdir -p "$FLAGS_backup_dir" &&
	cp -f "$backup_image" "$backup_file_path"; then
	true
	elif cp -f "$backup_image" "/tmp/$backup_file_name"; then
	backup_file_path="/tmp/$backup_file_name"
	else
	backup_file_path=''
	fi
	if [ -n "$backup_file_path" -a -s "$backup_file_path" ]; then
	# TODO(hungte) maybe we can wrap the flashrom by 'make_dev_firmware.sh -r'
	# so that the only command to remember would be make_dev_firmware.sh.
	echo "
	Backup of current firmware image is stored in:
	$backup_file_path
	Please copy the backup file to a safe place ASAP.

	To stop using devkeys and restore original firmware, execute command:
	flashrom -w [PATH_TO_BACKUP_IMAGE]
	Ex: flashrom -w $backup_file_path
	"
	else
	echo "WARNING: Cannot create file in $FLAGS_backup_dir... Ignore backups."
	fi
	fi

	# TODO(hungte) use vbutil_firmware to check if the new firmware is valid.
	# Or, do verification in resign_firmwarefd.sh and trust it.

	debug_msg "Write the image"
	write_image \|\|
	err_die "Failed to write image. Error message: $(cat "$EXEC_LOG")"

	debug_msg "Complete."
	if [ -z "$FLAGS_to" ]; then
	echo "Successfully changed firmware to Developer Keys. New HWID: $new_hwid"
	else
	echo "Firmware '$FLAGS_to' now uses Developer Keys. New HWID: $new_hwid"
	fi
	}

	main