units: introduce systemd-tmpfiles-setup-dev-early.service

This makes tmpfiles, sysusers, and udevd invoked in the following order:
1. systemd-tmpfiles-setup-dev-early.service
   Create device nodes gracefully, that is, create device nodes anyway
   by ignoring unknown users and groups.
2. systemd-sysusers.service
   Create users and groups, to make later invocations of tmpfiles and
   udevd can resolve necessary users and groups.
3. systemd-tmpfiles-setup-dev.service
   Adjust owners of previously created device nodes.
4. systemd-udevd.service
   Process all devices. Especially to make block devices active and can
   be mountable.
5. systemd-tmpfiles-setup.service
   Setup basic filesystem.

Follow-up for b42482af90.

Fixes #28653.
Replaces #28681 and #28732.

man/systemd-tmpfiles.xml

@@ -19,6 +19,7 @@
   <refnamediv>
     <refname>systemd-tmpfiles</refname>
     <refname>systemd-tmpfiles-setup.service</refname>
+    <refname>systemd-tmpfiles-setup-dev-early.service</refname>
     <refname>systemd-tmpfiles-setup-dev.service</refname>
     <refname>systemd-tmpfiles-clean.service</refname>
     <refname>systemd-tmpfiles-clean.timer</refname>
@@ -35,6 +36,7 @@
 
     <para>System units:
 <literallayout><filename>systemd-tmpfiles-setup.service</filename>
+<filename>systemd-tmpfiles-setup-dev-early.service</filename>
 <filename>systemd-tmpfiles-setup-dev.service</filename>
 <filename>systemd-tmpfiles-clean.service</filename>
 <filename>systemd-tmpfiles-clean.timer</filename></literallayout></para>
@@ -64,6 +66,7 @@
     searched for a matching file and the file found that has the highest priority is executed.</para>
 
     <para>System services (<filename>systemd-tmpfiles-setup.service</filename>,
+    <filename>systemd-tmpfiles-setup-dev-early.service</filename>,
     <filename>systemd-tmpfiles-setup-dev.service</filename>,
     <filename>systemd-tmpfiles-clean.service</filename>) invoke <command>systemd-tmpfiles</command> to create
     system files and to perform system wide cleanup. Those services read administrator-controlled

test/TEST-17-UDEV/test.sh

@@ -8,5 +8,9 @@ TEST_NO_NSPAWN=1
 # shellcheck source=test/test-functions
 . "${TEST_BASE_DIR:?}/test-functions"
 
+test_append_files() {
+    instmods snd_seq snd_timer tun
+    generate_module_dependencies
+}
 
 do_test "$@"

test/units/testsuite-17.00.sh

@@ -0,0 +1,57 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: LGPL-2.1-or-later
+set -ex
+set -o pipefail
+
+# shellcheck source=test/units/util.sh
+. "$(dirname "$0")"/util.sh
+
+# Tests for issue #28588 and #28653.
+
+# On boot, services need to be started in the following order:
+# 1. systemd-tmpfiles-setup-dev-early.service
+# 2. systemd-sysusers.service
+# 3. systemd-tmpfiles-setup-dev.service
+# 4. systemd-udevd.service
+
+output="$(systemctl show --property After --value systemd-udevd.service)"
+assert_in "systemd-tmpfiles-setup-dev-early.service" "$output"
+assert_in "systemd-sysusers.service" "$output"
+assert_in "systemd-tmpfiles-setup-dev.service" "$output"
+
+output="$(systemctl show --property After --value systemd-tmpfiles-setup-dev.service)"
+assert_in "systemd-tmpfiles-setup-dev-early.service" "$output"
+assert_in "systemd-sysusers.service" "$output"
+
+output="$(systemctl show --property After --value systemd-sysusers.service)"
+assert_in "systemd-tmpfiles-setup-dev-early.service" "$output"
+
+check_owner_and_mode() {
+    local dev=${1?}
+    local user=${2?}
+    local group=${3?}
+    local mode=${4:-}
+
+    if [[ -e "$dev" ]]; then
+        assert_in "$user" "$(stat --format=%U "$dev")"
+        assert_in "$group" "$(stat --format=%G "$dev")"
+        if [[ -n "$mode" ]]; then
+            assert_in "$mode" "$(stat --format=%#0a "$dev")"
+        fi
+    fi
+
+    return 0
+}
+
+# Check owner and access mode specified in static-nodes-permissions.conf
+check_owner_and_mode /dev/snd/seq      root audio 0660
+check_owner_and_mode /dev/snd/timer    root audio 0660
+check_owner_and_mode /dev/loop-control root disk  0660
+check_owner_and_mode /dev/net/tun      root root  0666
+check_owner_and_mode /dev/fuse         root root  0666
+check_owner_and_mode /dev/vfio/vfio    root root  0666
+check_owner_and_mode /dev/kvm          root kvm
+check_owner_and_mode /dev/vhost-net    root kvm
+check_owner_and_mode /dev/vhost-vsock  root kvm
+
+exit 0

units/kmod-static-nodes.service.in

@@ -10,7 +10,7 @@
 [Unit]
 Description=Create List of Static Device Nodes
 DefaultDependencies=no
-Before=sysinit.target systemd-tmpfiles-setup-dev.service
+Before=sysinit.target systemd-tmpfiles-setup-dev-early.service
 ConditionCapability=CAP_SYS_MODULE
 ConditionFileNotEmpty=/lib/modules/%v/modules.devname
 

units/meson.build

@@ -544,6 +544,11 @@ units = [
           'conditions' : ['ENABLE_TMPFILES'],
           'symlinks' : ['timers.target.wants/'],
         },
+        {
+          'file' : 'systemd-tmpfiles-setup-dev-early.service',
+          'conditions' : ['ENABLE_TMPFILES'],
+          'symlinks' : ['sysinit.target.wants/'],
+        },
         {
           'file' : 'systemd-tmpfiles-setup-dev.service',
           'conditions' : ['ENABLE_TMPFILES'],

units/systemd-sysusers.service

@@ -16,6 +16,8 @@ ConditionCredential=|sysusers.extra
 
 DefaultDependencies=no
 After=systemd-remount-fs.service
+After=systemd-tmpfiles-setup-dev-early.service
+Before=systemd-tmpfiles-setup-dev.service
 Before=sysinit.target systemd-update-done.service
 Conflicts=shutdown.target initrd-switch-root.target
 Before=shutdown.target initrd-switch-root.target

units/systemd-tmpfiles-setup-dev-early.service

@@ -0,0 +1,25 @@
+#  SPDX-License-Identifier: LGPL-2.1-or-later
+#
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=Create Static Device Nodes in /dev gracefully
+Documentation=man:tmpfiles.d(5) man:systemd-tmpfiles(8)
+
+DefaultDependencies=no
+Before=sysinit.target local-fs-pre.target systemd-udevd.service
+Wants=local-fs-pre.target
+Conflicts=shutdown.target initrd-switch-root.target
+Before=shutdown.target initrd-switch-root.target
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=systemd-tmpfiles --prefix=/dev --create --boot --graceful
+SuccessExitStatus=DATAERR CANTCREAT
+ImportCredential=tmpfiles.*

units/systemd-tmpfiles-setup-dev.service

@@ -12,6 +12,7 @@ Description=Create Static Device Nodes in /dev
 Documentation=man:tmpfiles.d(5) man:systemd-tmpfiles(8)
 
 DefaultDependencies=no
+After=systemd-tmpfiles-setup-dev-early.service
 Before=sysinit.target local-fs-pre.target systemd-udevd.service
 Wants=local-fs-pre.target
 Conflicts=shutdown.target initrd-switch-root.target
@@ -20,6 +21,6 @@ Before=shutdown.target initrd-switch-root.target
 [Service]
 Type=oneshot
 RemainAfterExit=yes
-ExecStart=systemd-tmpfiles --prefix=/dev --create --boot --graceful
+ExecStart=systemd-tmpfiles --prefix=/dev --create --boot
 SuccessExitStatus=DATAERR CANTCREAT
 ImportCredential=tmpfiles.*

units/systemd-tmpfiles-setup.service

@@ -21,7 +21,7 @@ RefuseManualStop=yes
 [Service]
 Type=oneshot
 RemainAfterExit=yes
-ExecStart=systemd-tmpfiles --create --remove --boot
+ExecStart=systemd-tmpfiles --create --remove --boot --exclude-prefix=/dev
 SuccessExitStatus=DATAERR CANTCREAT
 ImportCredential=tmpfiles.*
 ImportCredential=login.motd