resourced/init/resourced.conf

# Copyright 2021 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 Chromium OS Resource Manager daemon"
author        "chromium-os-dev@chromium.org"

start on started system-services
stop on stopping system-services

pre-start script
# Set permissions for resourced to write to sysfs EPP entries if they exist.
CPUFREQ_GLOB="/sys/devices/system/cpu/cpufreq/policy*/energy_performance_pref*"
if ls ${CPUFREQ_GLOB} >/dev/null 2>&1;
  then
    chown resourced:resourced $CPUFREQ_GLOB;
fi
end script

# Minijail forks off the desired process.
expect fork

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

# resourced handles low memory situations and shall not be OOM-killed.
oom score never

# Let the daemon crash if it grows too much. "as" is "address space" (VM
# size). The typical VM size of resourced is about 3MB. Set the limit to
# 5x typical VM size.
limit as 15000000 unlimited

# Comments to the args in order:
# - Exit immediately after fork. The jailed process will run in the background.
# - Create and enter new UTS namespace (hostname/NIS domain name).
# - Create and enter new cgroup namespace.
# - Create and enter new PID namespace.
# - Use the minimal mountns profile to start.
# - Get a writeable and empty /run tmpfs path.
# - Need access to /run/dbus for DBus communications.
# - Get a writeable and empty /sys tmpfs path.
# - Need access to /sys/kernel/mm/chromeos-low_mem for checking memory configs.
# - Need write access to energy_performance_preference sysfs entries.
# - Need write access to gpu sysfs entries.
# - Run as resourced user and group.
# - Inherit supplementary groups from user resourced.
# - Grant no caps.
# - No new privileges (no_new_privs).
# - Use the resourced seccomp policy.
# - Execute the daemon.
#
# NOTE: We don't add "-e" since we want to receive udev events.
script
  # card# depends on driver load order
  GT_CARD_PATHS="/sys/class/drm/card[0-9]"
  for card in $GT_CARD_PATHS; do
      BIND_MOUNT_LIST="$BIND_MOUNT_LIST-b $card,,1 "
  done

  exec minijail0                                                               \
    -i                                                                         \
    --uts                                                                      \
    -N                                                                         \
    -p                                                                         \
    --profile minimalistic-mountns                                             \
    -k 'tmpfs,/run,tmpfs,MS_NOSUID|MS_NODEV|MS_NOEXEC'                         \
    -b /run/dbus                                                               \
    -k 'tmpfs,/sys,tmpfs,MS_NODEV|MS_NOEXEC|MS_NOSUID,mode=755,size=10M'       \
    -b /sys/kernel/mm/chromeos-low_mem                                         \
    -b /sys/devices/system/cpu/cpufreq,,1                                      \
    ${BIND_MOUNT_LIST}                                                         \
    -u resourced -g resourced                                                  \
    -G                                                                         \
    -c 0                                                                       \
    -n                                                                         \
    -S /usr/share/policy/resourced-seccomp.policy                              \
    -- /usr/bin/resourced
end script