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.

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