flatcar-scripts/bin/cros_make_image_bootable

#!/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 which ensures that a given image has an up-to-date
# kernel partition, rootfs integrity hashes, and legacy bootloader configs.

# --- BEGIN COMMON.SH BOILERPLATE ---
# Load common CrOS utilities.  Inside the chroot this file is installed in
# /usr/lib/crosutils.  Outside the chroot we find it relative to the script's
# location.
find_common_sh() {
  local common_paths=(/usr/lib/crosutils "$(dirname "$(readlink -f "$0")")/..")
  local path

  SCRIPT_ROOT=
  for path in "${common_paths[@]}"; do
    if [ -r "${path}/common.sh" ]; then
      SCRIPT_ROOT=${path}
      break
    fi
  done
}

find_common_sh
. "${SCRIPT_ROOT}/common.sh" || (echo "Unable to load common.sh" && exit 1)
# --- END COMMON.SH BOILERPLATE ---

# Need to be inside the chroot to load chromeos-common.sh
assert_inside_chroot

# Load functions and constants for chromeos-install
. "/usr/lib/installer/chromeos-common.sh" || \
  die "Unable to load /usr/lib/installer/chromeos-common.sh"

set -e

if [ $# -lt 2 ]; then
  echo "Usage: ${0} /PATH/TO/IMAGE IMAGE.BIN [shflags overrides]"
  exit 1
fi

IMAGE_DIR="$(readlink -f "${1}")"
BOOT_DESC_FILE="${IMAGE_DIR}/boot.desc"
IMAGE="${IMAGE_DIR}/${2}"
shift
shift
FLAG_OVERRIDES="${@}"

if [ ! -r "${BOOT_DESC_FILE}" ]; then
  warn "${BOOT_DESC_FILE} cannot be read!"
  warn "Falling back to command line parsing"
  BOOT_DESC="${@}"
else
  BOOT_DESC="$(cat ${BOOT_DESC_FILE} | tr -s '\n' ' ')"
  info "Boot-time configuration for $(dirname "${IMAGE}"): "
  cat ${BOOT_DESC_FILE} | while read line; do
    info "  ${line}"
  done
fi

if [ ! -r "${IMAGE}" ]; then
  die "${IMAGE} cannot be read!"
fi


locate_gpt
set +e

# Now parse the build settings from ${OUTPUT_DIR}/boot.desc

DEFINE_string output_dir "/tmp" \
  "Directory to place output in."
DEFINE_string image "chromiumos_base.img" \
  "Full path to the chromiumos image to make bootable."
DEFINE_string arch "x86" \
  "Architecture to make bootable for: arm or x86"
DEFINE_string usb_disk "/dev/sdb3" \
  "Path syslinux should use to do a usb boot."
DEFINE_boolean cleanup_dirs ${FLAGS_TRUE} \
  "Whether the mount dirs should be removed on completion."

DEFINE_string boot_args "noinitrd" \
  "Additional boot arguments to pass to the commandline"

DEFINE_integer rootfs_size 720 \
  "rootfs filesystem size in MBs."
# ceil(0.1 * rootfs_size) is a good minimum.
DEFINE_integer rootfs_hash_pad 8 \
  "MBs reserved at the end of the rootfs image."

DEFINE_string rootfs_hash "/tmp/rootfs.hash" \
  "Path where the rootfs hash should be stored."
DEFINE_boolean enable_rootfs_verification ${FLAGS_FALSE} \
  "Default all bootloaders to use kernel-based root fs integrity checking."
DEFINE_integer verity_error_behavior 2 \
  "Kernel verified boot error behavior (0: I/O errors, 1: reboot, 2: nothing)"
DEFINE_integer verity_max_ios 1024 \
  "Number of outstanding I/O operations dm-verity caps at."
DEFINE_string verity_algorithm "sha1" \
  "Cryptographic hash algorithm used for kernel vboot."

DEFINE_string keys_dir "/usr/share/vboot/devkeys" \
  "Directory containing the signing keys."

DEFINE_string rootfs_mountpoint "/tmp/rootfs" \
  "Path where the rootfs can be safely mounted"
DEFINE_string statefulfs_mountpoint "/tmp/statefulfs" \
  "Path where the statefulfs can be safely mounted"
DEFINE_string espfs_mountpoint "/tmp/espfs" \
  "Path where the espfs can be safely mounted"

DEFINE_boolean use_dev_keys ${FLAGS_FALSE} \
  "Use developer keys for signing. (Default: false)"

# TODO(clchiou): Remove this flag after arm verified boot is stable
DEFINE_boolean crosbug12352_arm_kernel_signing ${FLAGS_TRUE} \
  "Sign kernel partition for ARM images (temporary hack)."

# TODO(sosa):  Remove once known images no longer use this in their config.
DEFINE_string arm_extra_bootargs "" "DEPRECATED FLAG.  Do not use."

# Parse the boot.desc and any overrides
eval set -- "${BOOT_DESC} ${FLAG_OVERRIDES}"
FLAGS "${@}" || exit 1

# Only now can we die on error.  shflags functions leak non-zero error codes,
# so will die prematurely if 'set -e' is specified before now.
set -e -u

if [[ ${FLAGS_crosbug12352_arm_kernel_signing} -eq ${FLAGS_TRUE} ]]; then
  crosbug12352_flag="--crosbug12352_arm_kernel_signing"
else
  crosbug12352_flag="--nocrosbug12352_arm_kernel_signing"
fi

# $1 - Directory where developer rootfs is mounted.
# $2 - Directory where developer stateful_partition is mounted.
# $3 - Directory where the ESP partition is mounted.
mount_gpt_cleanup() {
  local rootfs="${1-$FLAGS_rootfs_mountpoint}"
  local statefs="${2-$FLAGS_statefulfs_mountpoint}"
  local espfs="${3-$FLAGS_espfs_mountpoint}"
  "${SCRIPTS_DIR}/mount_gpt_image.sh" \
    -u -r "${rootfs}" -s "${statefs}" -e "${espfs}"
}

make_image_bootable() {
  local image="$1"
  local use_dev_keys=

  # Default to non-verified, non-UUID boot unless verified.
  # Long term we want root=PARTUUID=uuid+1.
  cros_root=/dev/sd%D%P
  if [[ "${FLAGS_arch}" = "arm" ]]; then
    cros_root='/dev/${devname}${rootpart}'
  fi
  if [[ ${FLAGS_enable_rootfs_verification} -eq ${FLAGS_TRUE} ]]; then
    cros_root=/dev/dm-0
  fi

  trap "mount_gpt_cleanup" EXIT
  "${SCRIPTS_DIR}/mount_gpt_image.sh" --from "$(dirname "${image}")" \
    --image "$(basename ${image})" -r "${FLAGS_rootfs_mountpoint}" \
    -s "${FLAGS_statefulfs_mountpoint}"

  # The rootfs should never be mounted rw again after this point without
  # re-calling make_image_bootable.
  sudo mount -o remount,ro "${FLAGS_rootfs_mountpoint}"
  root_dev=$(mount | grep -- "on ${FLAGS_rootfs_mountpoint} type" |
             cut -f1 -d' ' | tail -1)

  # Make the filesystem un-mountable as read-write.
  # mount_gpt_image.sh will undo this as needed.
  # TODO(wad) make sure there is parity in the signing scripts.
  if [ ${FLAGS_enable_rootfs_verification} -eq ${FLAGS_TRUE} ]; then
    # TODO(wad) this would be a good place to reset any other ext2 metadata.
    warn "Disabling r/w mount of the root filesystem"
    disable_rw_mount "$root_dev"
  fi

  if [ ${FLAGS_use_dev_keys} -eq ${FLAGS_TRUE} ]; then
    use_dev_keys="--use_dev_keys"
  fi

  # Builds the kernel partition image.  The temporary files are kept around
  # so that we can perform a load_kernel_test later on the final image.
  ${SCRIPTS_DIR}/build_kernel_image.sh \
    --arch="${FLAGS_arch}" \
    --to="${FLAGS_output_dir}/vmlinuz.image" \
    --hd_vblock="${FLAGS_output_dir}/vmlinuz_hd.vblock" \
    --vmlinuz="${FLAGS_rootfs_mountpoint}/boot/vmlinuz" \
    --working_dir="${FLAGS_output_dir}" \
    --boot_args="${FLAGS_boot_args}" \
    --keep_work \
    --rootfs_image=${root_dev} \
    --rootfs_hash=${FLAGS_rootfs_hash} \
    --verity_hash_alg=${FLAGS_verity_algorithm} \
    --verity_max_ios=${FLAGS_verity_max_ios} \
    --verity_error_behavior=${FLAGS_verity_error_behavior} \
    --root=${cros_root} \
    --keys_dir="${FLAGS_keys_dir}" \
    ${crosbug12352_flag} \
    ${use_dev_keys}

  local rootfs_hash_size=$(stat -c '%s' ${FLAGS_rootfs_hash})
  info "Appending rootfs.hash (${rootfs_hash_size} bytes) to the root fs"
  if [[ ${rootfs_hash_size} -gt $((FLAGS_rootfs_hash_pad * 1024 * 1024)) ]]
  then
    die "--rootfs_hash_pad reserves less than the needed ${rootfs_hash_size}"
  fi
  # Unfortunately, mount_gpt_image uses mount and not losetup to create the
  # loop devices.  This means that they are not the correct size.  We have to
  # write directly to the image to append the hash tree data.
  local hash_offset="$(partoffset ${image} 3)"
  hash_offset=$((hash_offset + ((1024 * 1024 * ${FLAGS_rootfs_size}) / 512)))
  sudo dd bs=512 \
          seek=${hash_offset} \
          if="${FLAGS_rootfs_hash}" \
          of="${image}" \
          conv=notrunc
  # We don't need to keep the file around anymore.
  sudo rm "${FLAGS_rootfs_hash}"

  # Move the verification block needed for the hard disk install to the
  # stateful partition. Mount stateful fs, copy file, and umount fs.
  # In original CL: http://codereview.chromium.org/2868044, this was done in
  # create_base_image(). However, it could break the build if it is a clean
  # build because vmlinuz_hd.vblock hasn't been created by build_kernel_image.sh
  sudo cp "${FLAGS_output_dir}/vmlinuz_hd.vblock" \
          "${FLAGS_statefulfs_mountpoint}"

  # START_KERN_A is set by the first call to install the gpt.
  local koffset="$(partoffset ${image} 2)"
  sudo dd if="${FLAGS_output_dir}/vmlinuz.image" of="${image}" \
    conv=notrunc bs=512 seek=${koffset}

  # Update the bootloaders.  The EFI system partition will be updated.
  local kernel_part=
  local usb_disk="${FLAGS_usb_disk}"

  # We should update the esp in place in the image.
  local bootloader_to="${image}"
  local esp_offset="$(partoffset ${image} 12)"
  esp_offset=$((esp_offset * 512))  # sectors to bytes
  local esp_size="$(partsize ${image} 12)"
  esp_size=$((esp_size * 512))  # sectors to bytes
  local bootloader_to_flags="--to_offset=${esp_offset} --to_size=${esp_size}"

  if [[ "${FLAGS_arch}" = "x86" ]]; then
    # Use the kernel partition to acquire configuration flags.
    kernel_part="--kernel_partition='${FLAGS_output_dir}/vmlinuz.image'"
    # Install syslinux on the EFI System Partition.
    kernel_part="${kernel_part} --install_syslinux"
  elif [[ "${FLAGS_arch}" = "arm" ]]; then
    # These flags are not used for ARM update_bootloaders.sh
    kernel_part=""
  fi

  # Update partition 12
  ${SCRIPTS_DIR}/update_bootloaders.sh \
    --arch=${FLAGS_arch} \
    --to="${bootloader_to}" \
    --from="${FLAGS_rootfs_mountpoint}"/boot \
    --vmlinuz="${FLAGS_rootfs_mountpoint}"/boot/vmlinuz \
    --usb_disk="${usb_disk}" \
    ${bootloader_to_flags} \
    $kernel_part

  trap - EXIT
  ${SCRIPTS_DIR}/mount_gpt_image.sh -u -r "${FLAGS_rootfs_mountpoint}" \
    -s "${FLAGS_statefulfs_mountpoint}"
}

verify_image_rootfs() {
  local image=$1
  local rootfs_offset="$(partoffset ${image} 3)"
  local rootfs_size="$(partsize ${image} 3)"

  local rootfs_tmp_file=$(mktemp)
  trap "rm ${rootfs_tmp_file}" EXIT
  sudo dd if="${image}" of="${rootfs_tmp_file}" bs=512 skip="${rootfs_offset}"

  # This flips the read-only compatibility flag, so that
  # e2fsck does not complain about unknown file system capabilities.
  enable_rw_mount "${rootfs_tmp_file}"
  info "Running e2fsck to check root file system for errors"
  sudo e2fsck -fn "${rootfs_tmp_file}" ||
    die "Root file system has errors, please ensure boot.desc and/or \
command line parameters are correct"
}

# Use default of current image location if the output dir doesn't exist.
if [ ! -d ${FLAGS_output_dir} ]; then
  warn "Output dir not found, using ${IMAGE_DIR}."
  FLAGS_output_dir="${IMAGE_DIR}"
  FLAGS_rootfs_hash="${IMAGE_DIR}/rootfs.hash"
  FLAGS_rootfs_mountpoint="${IMAGE_DIR}/rootfs_dir"
  FLAGS_statefulfs_mountpoint="${IMAGE_DIR}/stateful_dir"
  FLAGS_espfs_mountpoint="${IMAGE_DIR}/esp"
fi

# Create the directories if they don't exist.
mkdir -p ${FLAGS_rootfs_mountpoint}
mkdir -p ${FLAGS_statefulfs_mountpoint}
mkdir -p ${FLAGS_espfs_mountpoint}

make_image_bootable "${IMAGE}"
verify_image_rootfs "${IMAGE}"

if [ ${FLAGS_cleanup_dirs} -eq ${FLAGS_TRUE} ]; then
  rmdir ${FLAGS_rootfs_mountpoint}
  rmdir ${FLAGS_statefulfs_mountpoint}
  rmdir ${FLAGS_espfs_mountpoint}
fi