cryptohome/init/cryptohomed.conf

# Copyright (c) 2012 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.

description     "Start the cryptohome daemon"
author          "chromium-os-dev@chromium.org"

# Starts the cryptohome daemon, which handles mounting and
# unmounting users' encrypted home directories.  Also supports
# offline login checks.
start on started boot-services and started tcsd and started chapsd
stop on stopping boot-services
respawn

# Where we store the attestation-based enterprise enrollment data. The
# daemon will check for this environment variable and read the file at
# startup before forking.
env ABE_DATA_FILE=/run/cryptohomed.abe_data

env OLD_ATTESTATION_PATH="/mnt/stateful_partition/home/.shadow/attestation.epb"
env NEW_ATTESTATION_PATH="/mnt/stateful_partition/unencrypted/preserve/attestation.epb"

# Set in the ebuild.
env DIRENCRYPTION_FLAG=""
env DISTRIBUTED_MODE_FLAG=""

# Directory to store ephemeral cryptohome underlying sparse file.
env CRYPTOHOME_EPHEMERAL_PATH="/run/cryptohome"

# File for passing user data auth flag from pre-start to actual script block.
env USERDATAAUTH_FLAG_STORAGE_FILE="/run/cryptohome/cryptohomed.upstart_userdataauth_flag"

# If attestation.epb still exists in its old location, move it to the new
# location where cryptohome will look for it.
pre-start script
  # Paths under the stateful partition cannot be trusted. Only operate
  # on them after verifying that they don't contain symlinks pointing
  # elsewhere.
  has_symlink() {
    local path="$1"
    [ "$(realpath "${path}")" != "${path}" ]
  }

  if [ -f "${OLD_ATTESTATION_PATH}" ] &&
     ! has_symlink "${OLD_ATTESTATION_PATH}" &&
     ! has_symlink "${NEW_ATTESTATION_PATH}"; then
    mv "${OLD_ATTESTATION_PATH}" "${NEW_ATTESTATION_PATH}"
  fi

  # Read the value of a VPD entry by key, trying all given keys
  # until finding a non-empty value. A default can be specified
  # by passing -d default as two consecutive arguments.
  read_vpd() {
    local default_value=
    local value=
    while [ -z "${value}" -a $# -gt 0 ]; do
      if [ "$1" = -d ]; then
        shift
        default_value="$1"
     else
       # Don't create a VPD cache in this case if the cache file doesn't exist.
       # This prevents a VM from keeping trying and failing to read vendor data
       # from flashrom.
       #
       # It is important to use printf here because the value may
       # have a spurious newline at its end that will then be removed.
       value="$(printf '%s' "$(VPD_NEVER_CREATE_CACHE=1 vpd_get_value "$1")")"
      fi
      shift
    done
    printf '%s' "${value:-${default_value}}"
  }

  # Compute alternate data for attestation-based enrollment.
  compute_alternate_abe_data() {
    read_vpd serial_number Product_S/N |
      openssl sha256 -hmac "$(read_vpd -d '----' rlz_brand_code)" |
      sed 's/^.*= //'
  }

  # Get attestation-based enrollment data from either the default or
  # alternate source.
  get_abe_data() {
    local abe_data="$(read_vpd stable_device_secret_DO_NOT_SHARE)"
    printf '%s' "${abe_data:-$(compute_alternate_abe_data)}"
  }

  # Obtain data for attestation-based enrollment.
  get_abe_data >"${ABE_DATA_FILE}"

  # Create dir for ephemeral mounts while running as root.
  if [ ! -d "${CRYPTOHOME_EPHEMERAL_PATH}" ]; then
    mkdir -m 0700 "${CRYPTOHOME_EPHEMERAL_PATH}"
  fi

  if /usr/libexec/cryptohome/shall-use-userdataauth.sh; then
    # Yes, we are using the new UserDataAuth interface.
    touch "${USERDATAAUTH_FLAG_STORAGE_FILE}"
  else
    rm -rf "${USERDATAAUTH_FLAG_STORAGE_FILE}"
  fi
end script

expect fork

script
  # Note that cat is not used here to prevent confusing upstart's fork
  # tracking.
  set -- "$@" --noclose ${DIRENCRYPTION_FLAG} ${DISTRIBUTED_MODE_FLAG}
  [ -f "${USERDATAAUTH_FLAG_STORAGE_FILE}" ] &&
    set -- "$@" --user_data_auth_interface
  exec cryptohomed "$@"
end script

post-start exec rm -f "${ABE_DATA_FILE}" "${USERDATAAUTH_FLAG_STORAGE_FILE}"