arc/adbd/init/arcvm-adbd.conf

# Copyright 2020 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   "Run /system/bin/adbd (bridge)"
author        "chromium-os-dev@chromium.org"

start on starting arcvm-post-vm-start-services
stop on stopping arcvm-post-vm-start-services

# There is no point to have this service when the VM it talks to has
# been killed in oom case, so the value should be higher than the VM
# instance.
oom score -100

# The service will allocate some buffers.
limit as 150000000 150000000

env PIDFILE=/run/arc/adbd.pid
env RUNTIME_DIR=/run/arc/adbd

# The following environment variables are passed from Chrome.
import SERIALNUMBER
import ARCVM_CID

pre-start script
  logger -t "${UPSTART_JOB}" "Pre-start arcvm-adbd"

  # Validity check against serial number is derived from Android CTS.
  if ! echo "${SERIALNUMBER}" | grep -q -E '^[0-9A-Za-z]{6,20}$'; then
    logger -t "${UPSTART_JOB}" "ERROR: Serial number is invalid."
    stop
    exit 0
  fi

  # Validity check cid of VM that is defined as unsigned integer.
  # In arc-adbd service the CID is for guest VM so it should start
  # from 3. (Refer to the man page of vsock)
  if ! echo "${ARCVM_CID}" | grep -q -E '^(([3-9])|([1-9][0-9]+))$'; then
    logger -t "${UPSTART_JOB}" "ERROR: CID of ARCVM is invalid."
    stop
    exit 0
  fi

  # Clean up a stale pid file if exists.
  if ! rm -f "${PIDFILE}"; then
    logger -t "${UPSTART_JOB}" "ERROR: Failed to remove ${PIDFILE}"
    stop
    exit 0
  fi
end script

script
  # Start constructing minijail0 args...
  args="minijail0"

  # Use a minimalistic mount namespace.
  args="${args} --profile minimalistic-mountns"

  # Enter a new mount namespace.
  args="${args} -v"

  # Enter a new PID namespace.
  args="${args} -p"

  # Skip remounting as private.
  args="${args} -K"

  # Enter a new IPC namespace.
  args="${args} -l"

  # Create PID file at $PIDFILE.
  args="${args} -f $PIDFILE"

  # Set up mount points.
  args="${args} -b /sys,/sys"
  args="${args} -k tmpfs,/run,tmpfs,MS_NOSUID|MS_NODEV|MS_NOEXEC"

  # Set up seccomp-bpf.
  args="${args} -S /usr/share/policy/arcvm-adbd-seccomp.policy"

  # Allow only CAP_CHOWN, CAP_DAC_OVERRIDE, CAP_DAC_READ_SEARCH,
  # CAP_SYS_MODULE, CAP_SYS_ADMIN.
  args="${args} -n -c 210007 --ambient"

  # Finally, specify the command line arguments.
  args="${args} -- /usr/sbin/arc-adbd \
    --serialnumber=${SERIALNUMBER} \
    --arcvm_cid=${ARCVM_CID}"

  logger -t "${UPSTART_JOB}" "Executing: ${args}"
  exec ${args}
end script

post-stop script
  {
    echo "Post-stop arcvm-adbd"
    set +e -x

    # Perform best-effort unmounting of the bulk endpoints.
    umount --lazy "${RUNTIME_DIR}"/ep1
    umount --lazy "${RUNTIME_DIR}"/ep2
    exec rm -f "${RUNTIME_DIR}/"*
  } 2>&1 | logger -t "${UPSTART_JOB}"
end script