diagnostics/init/wilco_dtc_supportd.conf

# Copyright 2018 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 wilco_dtc_supportd daemon"
author         "chromium-os-dev@chromium.org"

# Start the wilco_dtc_supportd daemon, which is responsible for collecting
# telemetry and diagnostics information, and communicating with the wilco_dtc
# daemon.
start on starting wilco_dtc_dispatcher
stop stopped wilco_dtc_dispatcher

respawn
# If the job respawns 3 times in 10 seconds, stop trying.
respawn limit 3 10

expect fork

pre-start script
  # Create a directory for gRPC socket files - see the comment about the jailing
  # parameters below.
  mkdir -p -m 755 /run/wilco_dtc/grpc_sockets
  chown -R wilco_dtc:wilco_dtc /run/wilco_dtc/
end script

# Used jailing parameters:
#   -e: new network namespace;
#   -i: exit after forking;
#   -l: new IPC namespace;
#   -n: the no_new_privs bit;
#   -p: new PID namespace;
#   -r: remount /proc readonly;
#   -t: a new tmpfs filesystem for /tmp;
#   -v: new VFS namespace;
#   --uts: new UTS/hostname namespace;
#   -u, -g: user account and group;
#   --mount-dev: a new /dev mount;
#   --profile: minimalistic mount namespace;
#   -k /run: a new tmpfs filesystem for /run, with the subsequent parameters
#       mounting specific files into this directory;
#   -b /run/wilco_dtc/grpc_sockets: shared directory with gRPC socket files,
#       some of which are owned by wilco_dtc_supportd and some by the wilco_dtc
#       daemon (note: no other daemon will use this directory);
#   -b /run/dbus: shared socket file for talking with the D-Bus daemon;
#   -k /sys: a new tmpfs filesystem for /sys, with the subsequent parameters
#       mounting specific files into this directory;
#   -b /sys/class: symlinks to /sys/devices, categorized by device type;
#   -b /sys/devices: files with devices details exposed by the kernel;
#   -b /sys/firmware: files with details about ACPI, VPD, DMI/SMBIOS, etc.;
#   -b /dev/wilco_event0: file with EC events;
#   -b /dev/wilco_telem0: file with EC telemetry data;
#   -S: apply seccomp filters.
script
  # Evaluate which directories are present for binding. Do this without starting
  # subshells, to avoid breaking upstart's PID tracking.
  set --
  if [ -e /sys/class/power_supply/BAT0 ]; then
    set -- "$@" -b /sys/class/power_supply/BAT0
  fi
  if [ -e /sys/devices/platform/coretemp.0 ]; then
    set -- "$@" -b /sys/devices/platform/coretemp.0
  fi
  if [ -e /sys/devices/virtual/hwmon ]; then
    set -- "$@" -b /sys/devices/virtual/hwmon
  fi
  if [ -e /sys/devices/virtual/thermal ]; then
    set -- "$@" -b /sys/devices/virtual/thermal
  fi
  if [ -e /sys/firmware/dmi/tables ]; then
    set -- "$@" -b /sys/firmware/dmi/tables
  fi
  if [ -e /dev/wilco_event0 ]; then
    set -- "$@" -b /dev/wilco_event0
  fi
  if [ -e /dev/wilco_telem0 ]; then
    set -- "$@" -b /dev/wilco_telem0
  fi

  exec minijail0 -e -i -l -n -p -r -t -v --uts \
    -u wilco_dtc -g wilco_dtc \
    --mount-dev \
    --profile=minimalistic-mountns \
    -k 'tmpfs,/run,tmpfs,MS_NODEV|MS_NOSUID|MS_NOEXEC,mode=755,size=10M' \
    -b /run/wilco_dtc/grpc_sockets,,1 \
    -b /run/dbus \
    -k 'tmpfs,/sys,tmpfs,MS_NODEV|MS_NOSUID|MS_NOEXEC,mode=755,size=10M' \
    -b /sys/class/hwmon \
    -b /sys/class/thermal \
    "$@" \
    -S /usr/share/policy/wilco_dtc_supportd-seccomp.policy \
    -- /usr/bin/wilco_dtc_supportd
end script