arc/adbd/init/arcvm-adbd.conf

# Copyright 2020 The ChromiumOS Authors
# 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"

# Note: Lifecycle of this job is managed by Chrome.
# Stop this job when stopping ui job via arcvm-post-vm-start-services.
# If Chrome crashes, Chrome stops arcvm-post-vm-start-services before
# starting the mini-VM.
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
env CONFIG=/etc/arc/adbd.json
env HAS_DBC_SUPPORT=0

# 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 dev mode.
  if ! crossystem "cros_debug?1"; then
    logger -t "${UPSTART_JOB}" "Don't start arcvm-adbd in verified mode."
    stop
    exit 0
  fi

  # 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

  # Check for DbC and run DbC-specific configuration.
  if [ $(grep -ic '"adbOverDbcSupport":[^"]*true' ${CONFIG}) -ge 1 ]; then
    logger -t "${UPSTART_JOB}" "DbC support indicated in adbd.json."
    HAS_DBC_SUPPORT=1
  else
    logger -t "${UPSTART_JOB}" "DbC support not indicated in adbd.json. \
      Assuming gadget mode."
    HAS_DBC_SUPPORT=0
  fi

  if [ "$HAS_DBC_SUPPORT" -eq 1 ]; then
    # Fetch USB-C PCI bus id from adb config file.
    DEVICE_ID=$(grep -o '"pciBusDeviceId": "[^"]*' ${CONFIG} | grep -o '[^"]*$')

    # Write Google Vendor ID to DbC device if no yet set.
    GOOGLE_VENDOR_ID="18d1"
    DBC_VENDOR_ID="$(cat /sys/bus/pci/devices/$DEVICE_ID/dbc_idVendor)"
    if [ ${DBC_VENDOR_ID} != ${GOOGLE_VENDOR_ID} ]; then
      # First disable DbC, and then change the vendor id.
      echo disable > /sys/bus/pci/devices/$DEVICE_ID/dbc
      echo "0x$GOOGLE_VENDOR_ID" > /sys/bus/pci/devices/$DEVICE_ID/dbc_idVendor
    fi

    # Enable DbC if needed.
    if [ $(cat /sys/bus/pci/devices/$DEVICE_ID/dbc) = "disabled" ]; then
      logger -t "${UPSTART_JOB}" "About to enable dbc on ${DEVICE_ID}."
      echo enable > /sys/bus/pci/devices/$DEVICE_ID/dbc
    fi
  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="${args} -k \
    tmpfs,/sys,tmpfs,MS_NOSUID|MS_NODEV|MS_NOEXEC,mode=755,size=10M"
  args="${args} -b /sys,/sys"

  # DbC-specific configuration.
  if [ $(grep -ic '"adbOverDbcSupport":[^"]*true' ${CONFIG}) -ge 1 ]; then
    # For DbC, need write permissions for usb role.
    for f in $(find /sys/class/usb_role -type l -exec readlink -f {} +); do
      args="${args} -b $f/role,,1";
    done;

    # For accessing DbC device node.
    args="${args} -b /dev/dbc,/dev/dbc"

    # For udev monitor.
    args="${args} -k \
      tmpfs,/run,tmpfs,MS_NOSUID|MS_NODEV|MS_NOEXEC,mode=755,size=10M"
    args="${args} -b /run/udev,/run/udev"
  fi

  # 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