Add script for re-signing final firmware images with the correct keys.

scripts/image_signing/resign_firmwarefd.sh

+#!/bin/bash
+
+# Copyright (c) 2010 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.
+
+# Script to resign a firmware image using a different set of keys
+# for use on signing servers.
+#
+# arguments: src_fd, dst_fd, firmware_datakey, and firmware_keyblock
+#
+# src_fd: Input firmware image (in .fd format)
+# dst_fd: output firmware image name
+# firmware_datakey: Key used to sign firmware data (in .vbprivk format)
+# firmware_keyblock: Key block for firmware data key (in .keyblock format)
+#
+# Both the fmap_decode tool and vbutil_firmware should be in the system path.
+#
+# This script parses the output of fmap_decode tool from the Flashmap project
+# http://code.google.com/p/flashmap
+#
+# to determine the regions in the image containing "Firmware [A|B] Data" and
+# "Firmware [A|B] Key", which contain firmware data and firmware vblocks
+# respectively. It will then generate new vblocks using the set of keys
+# passed as arguments and output a new firmware image, with this new firmware
+# vblocks the old ones.
+#
+# Here is an example output of fmap_decode:
+#
+# area_offset="0x001c0000" area_size="0x00040000" area_name="Boot Stub" \
+#   area_flags_raw="0x01" area_flags="static"
+# area_offset="0x001a0000" area_size="0x00020000" area_name="GBB Area" \
+#   area_flags_raw="0x01" area_flags="static"
+# area_offset="0x00008000" area_size="0x00002000" area_name="Firmware A Key" \
+#   area_flags_raw="0x01" area_flags="static"
+# area_offset="0x0000a000" area_size="0x0009e000" area_name="Firmware A Data" \
+#  area_flags_raw="0x03" area_flags="static,compressed"
+# area_offset="0x000a8000" area_size="0x00002000" area_name="Firmware B Key" \
+#  area_flags_raw="0x01" area_flags="static"
+# area_offset="0x000aa000" area_size="0x0002e000" area_name="Firmware B Data" \
+#  area_flags_raw="0x03" area_flags="static,compressed"
+# area_offset="0x00005200" area_size="0x00001000" area_name="RW VPD" \
+#  area_flags_raw="0x00" area_flags=""
+#
+# This shows that Firmware A Data is at offset 0x0000a0000 in the .fd image
+# and is of size 0x0009e000 bytes. This can be extracted to generate new vblocks
+# which can then replace old vblock for Firmware A ("Firmware A Key" region at
+# offset 0x00008000 and size 0x00002000).
+
+# Abort on error
+set -e
+
+# Check arguments
+if [ $# -ne 5 ] ; then
+  echo \
+    "Usage: $0 src_fd dst_fd firmware_datakey firmware_keyblock kernel_subkey"
+  exit 1
+fi
+
+# Make sure the tools we need are available.
+for prog in fmap_decode vbutil_firmware; do
+  type -P "${prog}" &>/dev/null || \
+    { echo "${prog} tool not found."; exit 1; }
+done
+
+src_fd=$1
+dst_fd=$2
+firmware_datakey=$3
+firmware_keyblock=$4
+kernel_subkey=$5
+
+# TODO(gauravsh): Figure out where the version comes from.
+#                 Do we rev it manually?
+VERSION=1
+
+# Parse offsets and size of firmware data and vblocks
+for i in "A" "B"
+do
+  match_str="$i Key"
+  line=$(fmap_decode $1 | grep "$match_str")
+  offset="$(echo $line | sed -e 's/.*area_offset=\"\([a-f0-9x]*\)\".*/\1/')"
+  eval let \
+    fw${i}_vblock_offset="$offset"
+  size="$(echo $line | sed -e 's/.*area_size=\"\([a-f0-9x]*\)\".*/\1/')"
+  eval let \
+    fw${i}_vblock_size="$size"
+
+  match_str="$i Data"
+  line=$(fmap_decode $1 | grep "$match_str")
+  offset="$(echo $line | sed -e 's/.*area_offset=\"\([a-f0-9x]*\)\".*/\1/')"
+  eval let \
+    fw${i}_offset="$offset"
+  size="$(echo $line | sed -e 's/.*area_size=\"\([a-f0-9x]*\)\".*/\1/')"
+  eval let \
+    fw${i}_size="$size"
+done
+
+temp_fwimage=$(mktemp)
+temp_out_vb=$(mktemp)
+trap "rm -f ${temp_fwimage} ${temp_out_vb}" EXIT
+
+# Extract out Firmware A data and generate signature using the right keys
+dd if="${src_fd}" of="${temp_fwimage}" skip="${fwA_offset}" bs=1 \
+  count="${fwA_size}"
+
+echo "Re-calculating Firmware A vblock"
+vbutil_firmware \
+  --vblock "${temp_out_vb}" \
+  --keyblock "${firmware_keyblock}" \
+  --signprivate "${firmware_datakey}" \
+  --version "${VERSION}" \
+  --fv "${temp_fwimage}" \
+  --kernelkey "${kernel_subkey}"
+
+# Create a copy of the input image and put in the new vblock for firmware A
+cp "${src_fd}" "${dst_fd}"
+dd if="${temp_out_vb}" of="${dst_fd}" seek="${fwA_vblock_offset}" bs=1 \
+  count="${fwA_vblock_size}" conv=notrunc
+
+# Repeat for firmware B
+dd if="${src_fd}" of="${temp_fwimage}" skip="${fwB_offset}" bs=1 \
+  count="${fwB_size}"
+echo "Re-calculating Firmware B vblock"
+vbutil_firmware \
+  --vblock "${temp_out_vb}" \
+  --keyblock "${firmware_keyblock}" \
+  --signprivate "${firmware_datakey}" \
+  --version "${VERSION}" \
+  --fv "${temp_fwimage}" \
+  --kernelkey "${kernel_subkey}"
+
+# Destination image has already been created.
+dd if="${temp_out_vb}" of="${dst_fd}" seek="${fwB_vblock_offset}" bs=1 \
+  count="${fwB_vblock_size}" conv=notrunc
+
+echo "New signed image was output to ${dst_fd}"