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#!/bin/bash
# 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 modifies a base image to act as a recovery installer.
# If no kernel image is supplied, it will build a devkeys signed recovery
# kernel. Alternatively, a signed recovery kernel can be used to
# create a Chromium OS recovery image.
SCRIPT_ROOT=$(dirname $(readlink -f "$0"))
. "${SCRIPT_ROOT}/build_library/build_common.sh" || exit 1
. "${SCRIPT_ROOT}/build_library/disk_layout_util.sh" || exit 1
# Default recovery kernel name.
RECOVERY_KERNEL_NAME=recovery_vmlinuz.image
DEFINE_string board "$DEFAULT_BOARD" \
"board for which the image was built" \
b
DEFINE_integer statefulfs_sectors 4096 \
"number of free sectors in stateful filesystem when minimizing"
DEFINE_string kernel_image "" \
"path to a pre-built recovery kernel"
DEFINE_string kernel_outfile "" \
"emit recovery kernel to path/file ($RECOVERY_KERNEL_NAME if empty)"
DEFINE_string image "" \
"source image to use ($CHROMEOS_IMAGE_NAME if empty)"
DEFINE_string to "" \
"emit recovery image to path/file ($CHROMEOS_RECOVERY_IMAGE_NAME if empty)"
DEFINE_boolean kernel_image_only $FLAGS_FALSE \
"only emit recovery kernel"
DEFINE_boolean sync_keys $FLAGS_TRUE \
"update install kernel with the vblock from stateful"
DEFINE_boolean minimize_image $FLAGS_TRUE \
"create a minimized recovery image from source image"
DEFINE_boolean modify_in_place $FLAGS_FALSE \
"modify source image in place"
DEFINE_integer jobs -1 \
"how many packages to build in parallel at maximum" \
j
DEFINE_string build_root "/build" \
"root location for board sysroots"
DEFINE_string keys_dir "${VBOOT_DEVKEYS_DIR}" \
"directory containing the signing keys"
DEFINE_boolean verbose $FLAGS_FALSE \
"log all commands to stdout" v
DEFINE_boolean decrypt_stateful $FLAGS_FALSE \
"request a decryption of the stateful partition (implies --nominimize_image)"
DEFINE_string enable_serial "" \
"Enable serial output (same as build_kernel_image.sh). Example: ttyS0"
# Parse command line
FLAGS "$@" || exit 1
eval set -- "${FLAGS_ARGV}"
# Only now can we die on error. shflags functions leak non-zero error codes,
# so will die prematurely if 'switch_to_strict_mode' is specified before now.
switch_to_strict_mode
if [ $FLAGS_verbose -eq $FLAGS_TRUE ]; then
# Make debugging with -v easy.
set -x
fi
# We need space for copying decrypted files to the recovery image, so force
# --nominimize_image when using --decrypt_stateful.
if [ $FLAGS_decrypt_stateful -eq $FLAGS_TRUE ]; then
FLAGS_minimize_image=$FLAGS_FALSE
fi
# Load board options.
. "${BUILD_LIBRARY_DIR}/board_options.sh" || exit 1
EMERGE_BOARD_CMD="emerge-$BOARD"
# Files to preserve from original stateful, if minimize_image is true.
# If minimize_image is false, everything is always preserved.
WHITELIST="vmlinuz_hd.vblock unencrypted/import_extensions"
get_install_vblock() {
# If it exists, we need to copy the vblock over to stateful
# This is the real vblock and not the recovery vblock.
local partition_num_state=$(get_image_partition_number "${FLAGS_image}" \
"STATE")
IMAGE_DEV=$(loopback_partscan "${FLAGS_image}")
local stateful_mnt=$(mktemp -d)
local out=$(mktemp)
set +e
sudo mount ${IMAGE_DEV}p${partition_num_state} $stateful_mnt
sudo cp "$stateful_mnt/vmlinuz_hd.vblock" "$out"
sudo chown $USER "$out"
safe_umount "$stateful_mnt"
sudo losetup -d ${IMAGE_DEV}
trap - RETURN
rmdir "$stateful_mnt"
switch_to_strict_mode
echo "$out"
}
calculate_kernel_hash() {
local img="$1"
local partition_num_kern_a kern_offset kern_size kern_tmp
partition_num_kern_a="$(get_image_partition_number "${img}" "KERN-A")"
kern_offset="$(partoffset "${img}" "${partition_num_kern_a}")"
kern_size="$(partsize "${img}" "${partition_num_kern_a}")"
kern_tmp=$(mktemp)
dd if="${FLAGS_image}" bs=512 count="${kern_size}" \
skip="${kern_offset}" of="${kern_tmp}" 1>&2
# We're going to use the real signing block.
if [[ "${FLAGS_sync_keys}" -eq "${FLAGS_TRUE}" ]]; then
dd if="${INSTALL_VBLOCK}" of="${kern_tmp}" conv=notrunc 1>&2
fi
sha256sum "${kern_tmp}" | cut -f1 -d' '
rm "${kern_tmp}"
}
create_recovery_kernel_image() {
local sysroot="$FACTORY_ROOT"
local vmlinuz="$sysroot/boot/vmlinuz"
local enable_rootfs_verification_flag=--noenable_rootfs_verification
if grep -q enable_rootfs_verification "${IMAGE_DIR}/boot.desc"; then
enable_rootfs_verification_flag=--enable_rootfs_verification
fi
# Tie the installed recovery kernel to the final kernel. If we don't
# do this, a normal recovery image could be used to drop an unsigned
# kernel on without a key-change check.
# Doing this here means that the kernel and initramfs creation can
# be done independently from the image to be modified as long as the
# chromeos-recovery interfaces are the same. It allows for the signer
# to just compute the new hash and update the kernel command line during
# recovery image generation. (Alternately, it means an image can be created,
# modified for recovery, then passed to a signer which can then sign both
# partitions appropriately without needing any external dependencies.)
local kern_hash
kern_hash="$(calculate_kernel_hash "${FLAGS_image}")"
# TODO(wad) add FLAGS_boot_args support too.
${SCRIPTS_DIR}/build_kernel_image.sh \
--board="${FLAGS_board}" \
--arch="${ARCH}" \
--to="$RECOVERY_KERNEL_IMAGE" \
--vmlinuz="$vmlinuz" \
--working_dir="${IMAGE_DIR}" \
--boot_args="noinitrd panic=60 cros_recovery kern_b_hash=$kern_hash" \
--enable_serial="${FLAGS_enable_serial}" \
--keep_work \
--keys_dir="${FLAGS_keys_dir}" \
${enable_rootfs_verification_flag} \
--public="recovery_key.vbpubk" \
--private="recovery_kernel_data_key.vbprivk" \
--keyblock="recovery_kernel.keyblock" 1>&2 || die "build_kernel_image"
}
update_efi_partition() {
# Update the EFI System Partition configuration so that the kern_hash check
# passes.
RECOVERY_DEV=$(loopback_partscan "${RECOVERY_IMAGE}")
local partition_num_efi_system=$(get_image_partition_number \
"${RECOVERY_IMAGE}" "EFI-SYSTEM")
local efi_size kern_hash
efi_size=$(partsize "${RECOVERY_IMAGE}" "${partition_num_efi_system}")
kern_hash="$(calculate_kernel_hash "${RECOVERY_IMAGE}")"
if [[ ${efi_size} -ne 0 ]]; then
local efi_dir=$(mktemp -d)
sudo mount ${RECOVERY_DEV}p${partition_num_efi_system} "${efi_dir}"
sudo sed -i -e "s/cros_legacy/cros_legacy kern_b_hash=$kern_hash/g" \
"$efi_dir/syslinux/usb.A.cfg" || true
# This will leave the hash in the kernel for all boots, but that should be
# safe.
sudo sed -i -e "s/cros_efi/cros_efi kern_b_hash=$kern_hash/g" \
"$efi_dir/efi/boot/grub.cfg" || true
safe_umount "$efi_dir"
rmdir "$efi_dir"
fi
sudo losetup -d "${RECOVERY_DEV}"
}
install_recovery_kernel() {
local partition_num_kern_a=$(get_image_partition_number "${RECOVERY_IMAGE}" \
"KERN-A")
local kern_a_offset=$(partoffset "$RECOVERY_IMAGE" "${partition_num_kern_a}")
local kern_a_size=$(partsize "$RECOVERY_IMAGE" "${partition_num_kern_a}")
local partition_num_kern_b=$(get_image_partition_number "${RECOVERY_IMAGE}" \
"KERN-B")
local kern_b_offset=$(partoffset "$RECOVERY_IMAGE" "${partition_num_kern_b}")
local kern_b_size=$(partsize "$RECOVERY_IMAGE" "${partition_num_kern_b}")
if [ $kern_b_size -eq 1 ]; then
echo "Image was created with no KERN-B partition reserved!" 1>&2
echo "Cannot proceed." 1>&2
return 1
fi
# We're going to use the real signing block.
if [ $FLAGS_sync_keys -eq $FLAGS_TRUE ]; then
dd if="$INSTALL_VBLOCK" of="$RECOVERY_IMAGE" bs=512 \
seek=$kern_b_offset \
conv=notrunc
fi
local kernel_img_bytes
kernel_img_bytes="$(stat -c %s "${RECOVERY_KERNEL_IMAGE}")"
if [[ "${kernel_img_bytes}" -gt "$(( kern_a_size * 512 ))" ]]; then
die "Kernel image is larger than $(( kern_a_size * 512 / 1048576 )) MiB."
fi
# Install the recovery kernel as primary.
dd if="$RECOVERY_KERNEL_IMAGE" of="$RECOVERY_IMAGE" bs=512 \
seek=$kern_a_offset \
count=$kern_a_size \
conv=notrunc
# Force all of the file writes to complete, in case it's necessary for
# crbug.com/954188
sync
# Set the 'Success' flag to 1 (to prevent the firmware from updating
# the 'Tries' flag).
sudo $GPT add -i "${partition_num_kern_a}" -S 1 "$RECOVERY_IMAGE"
# Repeat for the legacy bioses.
# Replace vmlinuz.A with the recovery version we built.
# TODO(wad): Extract the $RECOVERY_KERNEL_IMAGE and grab vmlinuz from there.
local sysroot="$FACTORY_ROOT"
local vmlinuz="$sysroot/boot/vmlinuz"
local failed=0
if [ "$ARCH" = "x86" ]; then
RECOVERY_DEV=$(loopback_partscan "${RECOVERY_IMAGE}")
# There is no syslinux on ARM, so this copy only makes sense for x86.
set +e
local partition_num_efi_system=$(get_image_partition_number \
"${RECOVERY_IMAGE}" "EFI-SYSTEM")
local esp_mnt=$(mktemp -d)
sudo mount ${RECOVERY_DEV}p${partition_num_efi_system} "$esp_mnt"
sudo cp "$vmlinuz" "$esp_mnt/syslinux/vmlinuz.A" || failed=1
safe_umount "$esp_mnt"
rmdir "$esp_mnt"
sudo losetup -d ${RECOVERY_DEV}
trap - RETURN
switch_to_strict_mode
fi
if [ $failed -eq 1 ]; then
echo "Failed to copy recovery kernel to ESP"
return 1
fi
return 0
}
find_sectors_needed() {
# Find the minimum disk sectors needed for a file system to hold a list of
# files or directories.
local base_dir="$1"
local file_list="$2"
# Calculate space needed by the files we'll be copying, plus
# a reservation for recovery logs or other runtime data.
local in_use=$(cd "${base_dir}"
du -s -B512 ${file_list} |
awk '{ sum += $1 } END { print sum }')
local sectors_needed=$(( in_use + FLAGS_statefulfs_sectors ))
# Add 10% overhead for the FS, rounded down. There's some
# empirical justification for this number, but at heart, it's a
# wild guess.
echo $(( sectors_needed + sectors_needed / 10 ))
}
# Copy the given list of files from old stateful partition to new stateful
# partition.
# Args:
# $1: source image filename
# $2: destination image filename
copy_stateful() {
local src_img="$1"
local dst_img="$2"
local old_stateful_offset old_stateful_mnt sectors_needed
local small_stateful new_stateful_mnt
# Mount the old stateful partition so we can copy selected values
# off of it.
local partition_num_state
partition_num_state=$(get_image_partition_number "${dst_img}" "STATE")
old_stateful_mnt=$(mktemp -d)
IMAGE_DEV=$(loopback_partscan "${src_img}")
sudo mount "${IMAGE_DEV}p${partition_num_state}" "${old_stateful_mnt}"
sectors_needed="$(cgpt show -i "${partition_num_state}" -n -s "${dst_img}")"
# Rebuild the image with stateful partition sized by sectors_needed.
small_stateful=$(mktemp)
dd if=/dev/zero of="${small_stateful}" bs=512 \
count="${sectors_needed}" 1>&2
trap "rm ${small_stateful}; sudo losetup -d ${IMAGE_DEV} || true" RETURN
# Don't bother with ext3 for such a small image.
/sbin/mkfs.ext2 -F -b 4096 "${small_stateful}" 1>&2
# If it exists, we need to copy the vblock over to stateful
# This is the real vblock and not the recovery vblock.
new_stateful_mnt=$(mktemp -d)
# Force all of the file writes to complete, in case it's necessary for
# crbug.com/954188
sync
sudo mount -o loop $small_stateful $new_stateful_mnt
# Create the directories that are going to be needed below. With correct
# permissions and ownership.
sudo mkdir --mode=755 "${new_stateful_mnt}/unencrypted"
# Copy over any files that need to be preserved.
for name in ${WHITELIST}; do
if [ -e "${old_stateful_mnt}/${name}" ]; then
sudo cp -a "${old_stateful_mnt}/${name}" "${new_stateful_mnt}/${name}"
fi
done
# Cleanup everything.
safe_umount "$old_stateful_mnt"
safe_umount "$new_stateful_mnt"
rmdir "$old_stateful_mnt"
rmdir "$new_stateful_mnt"
sudo losetup -d ${IMAGE_DEV}
trap - RETURN
switch_to_strict_mode
local dst_start
dst_start="$(cgpt show -i "${partition_num_state}" -b "${dst_img}")"
dd if="${small_stateful}" of="${dst_img}" conv=notrunc bs=512 \
seek="${dst_start}" count="${sectors_needed}" status=none
return 0
}
# Calculates the number of sectors required for stateful partition.
# or returns the source stateful partition size if --minimize_image not present.
calculate_stateful_blocks() {
local partition_num_state
partition_num_state="$(get_image_partition_number "${FLAGS_image}" "STATE")"
# If --minimize_image not present, use the partition size from source image,
# (not recovery image, it's hard-coded to 2MiB).
if [[ "${FLAGS_minimize_image}" -eq "${FLAGS_FALSE}" ]]; then
cgpt show -i "${partition_num_state}" -n -s "${FLAGS_image}"
return 0
fi
local old_stateful_mnt
old_stateful_mnt="$(mktemp -d)"
IMAGE_DEV=$(loopback_partscan "${FLAGS_image}")
sudo mount "${IMAGE_DEV}p${partition_num_state}" "${old_stateful_mnt}"
# Print the minimum number of sectors needed.
find_sectors_needed "${old_stateful_mnt}" "${WHITELIST}"
# Cleanup everything.
safe_umount "${old_stateful_mnt}"
rmdir "${old_stateful_mnt}"
sudo losetup -d "${IMAGE_DEV}"
return 0
}
# Creates an empty image using the recovery layout and calculated stateful size.
create_image() {
local dst_img="$1"
local stateful_blocks
stateful_blocks="$(calculate_stateful_blocks)"
# Remove dst_img first otherwise build_gpt_image won't create a new one
# with correct layout.
rm -f "${dst_img}"
# Build the partition table.
local partition_script_path
partition_script_path="$(dirname "${dst_img}")/partition_script.sh"
write_partition_script recovery "${partition_script_path}" \
"STATE:=$(( stateful_blocks * 512 ))"
run_partition_script "${dst_img}" "${partition_script_path}"
}
# Copy the partitions one by one from source image to destination image,
# except that KERN-A is moved to KERN-B.
# Args:
# $1: source image filename
# $2: destination image filename
copy_partitions() {
local src_img="$1"
local dst_img="$2"
local part=0
while :; do
: $(( part += 1 ))
local src_start
src_start="$(cgpt show -i "${part}" -b "${src_img}")"
if [[ "${src_start}" -eq 0 ]]; then
# No more partitions to copy.
break
fi
# Load source partition details.
local size label
size="$(cgpt show -i "${part}" -s "${src_img}")"
label="$(cgpt show -i "${part}" -l "${src_img}")"
if [[ "${size}" -eq 0 ]]; then
continue
fi
local dst_part="${part}"
# Move KERN-A to KERN-B.
if [[ ${label} == 'KERN-A' ]]; then
dst_part="$(get_image_partition_number "${dst_img}" 'KERN-B')"
fi
local dst_start dst_size
dst_start="$(cgpt show -i "${dst_part}" -b "${dst_img}")"
dst_size="$(cgpt show -i "${dst_part}" -s "${dst_img}")"
if [[ "${label}" == 'STATE' && \
"${FLAGS_minimize_image}" -eq "${FLAGS_TRUE}" ]]; then
copy_stateful "${src_img}" "${dst_img}"
elif [[ ${label} == 'KERN-B' ]]; then
: # Skip KERN-B.
else
# Copy other partition as-is.
if [[ "${size}" -gt "${dst_size}" ]]; then
die "Partition #${part} larger than the destination partition"
fi
dd if="${src_img}" of="${dst_img}" conv=notrunc bs=512 \
skip="${src_start}" seek="${dst_start}" count="${size}" \
status=none
sync
fi
done
return 0
}
cleanup() {
set +e
if [[ -n "${RECOVERY_DEV}" ]]; then
sudo losetup -d "${RECOVERY_DEV}"
fi
if [[ -n "${IMAGE_DEV}" ]]; then
sudo losetup -d "${IMAGE_DEV}"
fi
if [[ "${FLAGS_image}" != "${RECOVERY_IMAGE}" ]]; then
rm "${RECOVERY_IMAGE}"
fi
rm "${INSTALL_VBLOCK}"
}
# Main process begins here.
set -u
# No image was provided, use standard latest image path.
if [ -z "$FLAGS_image" ]; then
FLAGS_image="${IMAGES_DIR}/${BOARD}/latest/${CHROMEOS_IMAGE_NAME}"
fi
# Turn path into an absolute path.
FLAGS_image=$(readlink -f "$FLAGS_image")
# Abort early if we can't find the image.
if [ ! -f "$FLAGS_image" ]; then
die_notrace "Image not found: $FLAGS_image"
fi
IMAGE_DIR="$(dirname "$FLAGS_image")"
IMAGE_NAME="$(basename "$FLAGS_image")"
RECOVERY_IMAGE="${FLAGS_to:-$IMAGE_DIR/$CHROMEOS_RECOVERY_IMAGE_NAME}"
RECOVERY_KERNEL_IMAGE=\
"${FLAGS_kernel_outfile:-$IMAGE_DIR/$RECOVERY_KERNEL_NAME}"
STATEFUL_DIR="$IMAGE_DIR/stateful_partition"
SCRIPTS_DIR=${SCRIPT_ROOT}
RECOVERY_DEV=""
IMAGE_DEV=""
if [ $FLAGS_kernel_image_only -eq $FLAGS_TRUE -a \
-n "$FLAGS_kernel_image" ]; then
die_notrace "Cannot use --kernel_image_only with --kernel_image"
fi
echo "Creating recovery image from ${FLAGS_image}"
INSTALL_VBLOCK=$(get_install_vblock)
if [ -z "$INSTALL_VBLOCK" ]; then
die "Could not copy the vblock from stateful."
fi
FACTORY_ROOT="${BOARD_ROOT}/factory-root"
if [ -z "${FLAGS_kernel_image}" ]; then
# Build the recovery kernel.
RECOVERY_KERNEL_FLAGS="recovery_ramfs tpm i2cdev vfat kernel_compress_xz"
RECOVERY_KERNEL_FLAGS="${RECOVERY_KERNEL_FLAGS} -kernel_afdo"
USE="${USE} ${RECOVERY_KERNEL_FLAGS}" emerge_custom_kernel "$FACTORY_ROOT" ||
die "Cannot emerge custom kernel"
create_recovery_kernel_image
echo "Recovery kernel created at $RECOVERY_KERNEL_IMAGE"
else
RECOVERY_KERNEL_IMAGE="$FLAGS_kernel_image"
fi
if [ $FLAGS_kernel_image_only -eq $FLAGS_TRUE ]; then
echo "Kernel emitted. Stopping there."
rm "$INSTALL_VBLOCK"
exit 0
fi
trap cleanup EXIT
if [[ "${FLAGS_modify_in_place}" -eq "${FLAGS_TRUE}" ]]; then
# Implement in-place modification by creating a temp image and copy it back
# to the source image path later.
RECOVERY_IMAGE="$(mktemp)"
fi
create_image "${RECOVERY_IMAGE}"
copy_partitions "${FLAGS_image}" "${RECOVERY_IMAGE}"
sync
if [ $FLAGS_decrypt_stateful -eq $FLAGS_TRUE ]; then
stateful_mnt=$(mktemp -d)
RECOVERY_DEV=$(loopback_partscan "${RECOVERY_IMAGE}")
partition_num_state=$(get_image_partition_number \
"${RECOVERY_IMAGE}" "STATE")
sudo mount ${RECOVERY_DEV}p${partition_num_state} "${stateful_mnt}"
echo -n "1" | sudo tee "${stateful_mnt}"/decrypt_stateful >/dev/null
sudo umount "$stateful_mnt"
rmdir "$stateful_mnt"
sudo losetup -d ${RECOVERY_DEV}
fi
install_recovery_kernel
update_efi_partition
if [[ "${FLAGS_modify_in_place}" -eq "${FLAGS_TRUE}" ]]; then
mv "${RECOVERY_IMAGE}" "${FLAGS_image}"
fi
echo "Recovery image created at $RECOVERY_IMAGE"
command_completed
trap - EXIT