shill/init/shill-sandboxing-kill-switch.conf

#
# Copyright 2018 The Chromium OS Authors. All rights reserved.
#
# Micah Morton <mortonm@chromium.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#

description     "Write kill switch file for sandboxing shill."
author          "chromium-os-dev@chromium.org"

# NOTE: Since Chrome feature flags only get updated through Finch during
# browser startup, we need to relay the message from Chrome to shill whenever
# the ShillSandboxing flag is disabled. We do this by writing a file in
# /var/lib/shill that is queried by the shill.sh init script next time shill
# spawns. In this way, after updating Finch server configs (and waiting the
# necessary time to push configs to clients), going from shill sandboxing
# enabled to disabled requires first a reboot (which will trigger this script
# under the updated feature flag, since Chrome has been restarted by the
# reboot) followed by restarting shill (e.g. another reboot or "restart shill"
# command).

# Use 'start on started system-services' to ensure Chrome is running and we can
# query the "IsShillSandboxingEnabled" feature flag.
# TODO(mortonm): Remove this file completely when removing the kill switch for
# shill sandboxing.
start on started system-services

pre-start exec mkdir -p /var/lib/shill

script
  status=0
  reply=$(minijail0 -u chronos /usr/bin/dbus-send --system --type=method_call \
    --print-reply \
    --dest=org.chromium.ChromeFeaturesService \
    /org/chromium/ChromeFeaturesService \
    "org.chromium.ChromeFeaturesServiceInterface.IsShillSandboxingEnabled" \
    2>/dev/null) || status=$?
  if [ ${status} -eq 0 -a "${reply##* }" = "false" ] ; then
    # Disable sandboxing.
    echo "1" > /var/lib/shill/shill_sandboxing_disabled
  else
    # Either "${reply##* }" equals "true" or something went wrong in parsing
    # response. Regardless, remove the file that disables sandboxing since
    # shill running in a sandbox is the default/expected behavior.
    rm -f /var/lib/shill/shill_sandboxing_disabled
  fi
end script