Merge pull request #12424 from poettering/logind-brightness

logind: add SetBrightness() bus call as minimal API for setting "leds" and "backlight" kernel class device brightness

32 files changed, 700 insertions, 199 deletions

diff --git a/TODO b/TODO
index 1b91b7c799..57c07bea7a 100644
--- a/TODO
+++ b/TODO
@@ -27,6 +27,13 @@ Features:
 * when killing due to service watchdog timeout maybe detect whether target
   process is under ptracing and then log loudly and continue instead.
 
+* introduce a new group to own TPM devices
+
+* make rfkill uaccess controllable by default, i.e. steal rule from
+  gnome-bluetooth and friends
+
+* warn if udev rules files are marked executable (docker?)
+
 * tweak journald context caching. In addition to caching per-process attributes
   keyed by PID, cache per-cgroup attributes (i.e. the various xattrs we read)
   keyed by cgroup path, and guarded by ctime changes. This should provide us
diff --git a/src/libsystemd/sd-bus/bus-common-errors.c b/src/libsystemd/sd-bus/bus-common-errors.c
index ef53d0a450..edd30bf84d 100644
--- a/src/libsystemd/sd-bus/bus-common-errors.c
+++ b/src/libsystemd/sd-bus/bus-common-errors.c
@@ -56,6 +56,7 @@ BUS_ERROR_MAP_ELF_REGISTER const sd_bus_error_map bus_common_errors[] = {
         SD_BUS_ERROR_MAP(BUS_ERROR_OPERATION_IN_PROGRESS,        EINPROGRESS),
         SD_BUS_ERROR_MAP(BUS_ERROR_SLEEP_VERB_NOT_SUPPORTED,     EOPNOTSUPP),
         SD_BUS_ERROR_MAP(BUS_ERROR_SESSION_BUSY,                 EBUSY),
+        SD_BUS_ERROR_MAP(BUS_ERROR_NOT_YOUR_DEVICE,              EPERM),
 
         SD_BUS_ERROR_MAP(BUS_ERROR_AUTOMATIC_TIME_SYNC_ENABLED,  EALREADY),
         SD_BUS_ERROR_MAP(BUS_ERROR_NO_NTP_SUPPORT,               EOPNOTSUPP),
diff --git a/src/libsystemd/sd-bus/bus-common-errors.h b/src/libsystemd/sd-bus/bus-common-errors.h
index 2544bdebc1..296579116c 100644
--- a/src/libsystemd/sd-bus/bus-common-errors.h
+++ b/src/libsystemd/sd-bus/bus-common-errors.h
@@ -51,6 +51,7 @@
 #define BUS_ERROR_OPERATION_IN_PROGRESS "org.freedesktop.login1.OperationInProgress"
 #define BUS_ERROR_SLEEP_VERB_NOT_SUPPORTED "org.freedesktop.login1.SleepVerbNotSupported"
 #define BUS_ERROR_SESSION_BUSY "org.freedesktop.login1.SessionBusy"
+#define BUS_ERROR_NOT_YOUR_DEVICE "org.freedesktop.login1.NotYourDevice"
 
 #define BUS_ERROR_AUTOMATIC_TIME_SYNC_ENABLED "org.freedesktop.timedate1.AutomaticTimeSyncEnabled"
 #define BUS_ERROR_NO_NTP_SUPPORT "org.freedesktop.timedate1.NoNTPSupport"
diff --git a/src/login/71-seat.rules.in b/src/login/71-seat.rules.in
index b67966cdf6..6010f048ae 100644
--- a/src/login/71-seat.rules.in
+++ b/src/login/71-seat.rules.in
@@ -14,6 +14,10 @@ SUBSYSTEM=="sound", KERNEL=="card*", TAG+="seat"
 SUBSYSTEM=="input", KERNEL=="input*", TAG+="seat"
 SUBSYSTEM=="graphics", KERNEL=="fb[0-9]*", TAG+="seat"
 
+# Assign keyboard and LCD backlights to the seat
+SUBSYSTEM=="leds", TAG+="seat"
+SUBSYSTEM=="backlight", TAG+="seat"
+
 # HyperV currently doesn't do DRM, hence we need to synthesize for HyperV's fb device instead
 SUBSYSTEM=="graphics", KERNEL=="fb[0-9]", DRIVERS=="hyperv_fb", TAG+="master-of-seat"
 
diff --git a/src/login/loginctl.c b/src/login/loginctl.c
index 687a534f7b..2ad9887066 100644
--- a/src/login/loginctl.c
+++ b/src/login/loginctl.c
@@ -846,23 +846,11 @@ static int show_session(int argc, char *argv[], void *userdata) {
         (void) pager_open(arg_pager_flags);
 
         if (argc <= 1) {
-                const char *session, *p = "/org/freedesktop/login1/session/self";
-
+                /* If no argument is specified inspect the manager itself */
                 if (properties)
-                        /* If no argument is specified inspect the manager itself */
                         return show_properties(bus, "/org/freedesktop/login1", &new_line);
 
-                /* And in the pretty case, show data of the calling session */
-                session = getenv("XDG_SESSION_ID");
-                if (session) {
-                        r = get_session_path(bus, session, &error, &path);
-                        if (r < 0)
-                                return log_error_errno(r, "Failed to get session path: %s", bus_error_message(&error, r));
-
-                        p = path;
-                }
-
-                return print_session_status_info(bus, p, &new_line);
+                return print_session_status_info(bus, "/org/freedesktop/login1/session/auto", &new_line);
         }
 
         for (i = 1; i < argc; i++) {
@@ -895,8 +883,7 @@ static int show_user(int argc, char *argv[], void *userdata) {
         (void) pager_open(arg_pager_flags);
 
         if (argc <= 1) {
-                /* If not argument is specified inspect the manager
-                 * itself */
+                /* If no argument is specified inspect the manager itself */
                 if (properties)
                         return show_properties(bus, "/org/freedesktop/login1", &new_line);
 
@@ -953,12 +940,11 @@ static int show_seat(int argc, char *argv[], void *userdata) {
         (void) pager_open(arg_pager_flags);
 
         if (argc <= 1) {
-                /* If not argument is specified inspect the manager
-                 * itself */
+                /* If no argument is specified inspect the manager itself */
                 if (properties)
                         return show_properties(bus, "/org/freedesktop/login1", &new_line);
 
-                return print_seat_status_info(bus, "/org/freedesktop/login1/seat/self", &new_line);
+                return print_seat_status_info(bus, "/org/freedesktop/login1/seat/auto", &new_line);
         }
 
         for (i = 1; i < argc; i++) {
@@ -1005,11 +991,8 @@ static int activate(int argc, char *argv[], void *userdata) {
         polkit_agent_open_if_enabled(arg_transport, arg_ask_password);
 
         if (argc < 2) {
-                /* No argument? Let's either use $XDG_SESSION_ID (if specified), or an empty
-                 * session name, in which case logind will try to guess our session. */
-
                 short_argv[0] = argv[0];
-                short_argv[1] = getenv("XDG_SESSION_ID") ?: (char*) "";
+                short_argv[1] = (char*) "";
                 short_argv[2] = NULL;
 
                 argv = short_argv;
@@ -1030,7 +1013,7 @@ static int activate(int argc, char *argv[], void *userdata) {
                                 &error, NULL,
                                 "s", argv[i]);
                 if (r < 0)
-                        return log_error_errno(r, "Failed to issue method call: %s", bus_error_message(&error, -r));
+                        return log_error_errno(r, "Failed to issue method call: %s", bus_error_message(&error, r));
         }
 
         return 0;
diff --git a/src/login/logind-action.c b/src/login/logind-action.c
index 6c9366761d..4f97e0d9bb 100644
--- a/src/login/logind-action.c
+++ b/src/login/logind-action.c
@@ -8,6 +8,8 @@
 #include "conf-parser.h"
 #include "format-util.h"
 #include "logind-action.h"
+#include "logind-dbus.h"
+#include "logind-session-dbus.h"
 #include "process-util.h"
 #include "sleep-config.h"
 #include "special.h"
diff --git a/src/login/logind-brightness.c b/src/login/logind-brightness.c
new file mode 100644
index 0000000000..8dfa97d7ae
--- /dev/null
+++ b/src/login/logind-brightness.c
@@ -0,0 +1,256 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include "bus-util.h"
+#include "device-util.h"
+#include "hash-funcs.h"
+#include "logind-brightness.h"
+#include "logind.h"
+#include "process-util.h"
+#include "stdio-util.h"
+
+/* Brightness and LED devices tend to be very slow to write to (often being I2C and such). Writes to the
+ * sysfs attributes are synchronous, and hence will freeze our process on access. We can't really have that,
+ * hence we add some complexity: whenever we need to write to the brightness attribute, we do so in a forked
+ * off process, which terminates when it is done. Watching that process allows us to watch completion of the
+ * write operation.
+ *
+ * To make this even more complex: clients are likely to send us many write requests in a short time-frame
+ * (because they implement reactive brightness sliders on screen). Let's coalesce writes to make this
+ * efficient: whenever we get requests to change brightness while we are still writing to the brightness
+ * attribute, let's remember the request and restart a new one when the initial operation finished. When we
+ * get another request while one is ongoing and one is pending we'll replace the pending one with the new
+ * one.
+ *
+ * The bus messages are answered when the first write operation finishes that started either due to the
+ * request or due to a later request that overrode the requested one.
+ *
+ * Yes, this is complex, but I don't see an easier way if we want to be both efficient and still support
+ * completion notification. */
+
+typedef struct BrightnessWriter {
+        Manager *manager;
+
+        sd_device *device;
+        char *path;
+
+        pid_t child;
+
+        uint32_t brightness;
+        bool again;
+
+        Set *current_messages;
+        Set *pending_messages;
+
+        sd_event_source* child_event_source;
+} BrightnessWriter;
+
+static void brightness_writer_free(BrightnessWriter *w) {
+        if (!w)
+                return;
+
+        if (w->manager && w->path)
+                (void) hashmap_remove_value(w->manager->brightness_writers, w->path, w);
+
+        sd_device_unref(w->device);
+        free(w->path);
+
+        set_free(w->current_messages);
+        set_free(w->pending_messages);
+
+        w->child_event_source = sd_event_source_unref(w->child_event_source);
+
+        free(w);
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(BrightnessWriter*, brightness_writer_free);
+
+DEFINE_PRIVATE_HASH_OPS_WITH_VALUE_DESTRUCTOR(
+                brightness_writer_hash_ops,
+                char,
+                string_hash_func,
+                string_compare_func,
+                BrightnessWriter,
+                brightness_writer_free);
+
+static void brightness_writer_reply(BrightnessWriter *w, int error) {
+        int r;
+
+        assert(w);
+
+        for (;;) {
+                _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
+
+                m = set_steal_first(w->current_messages);
+                if (!m)
+                        break;
+
+                if (error == 0)
+                        r = sd_bus_reply_method_return(m, NULL);
+                else
+                        r = sd_bus_reply_method_errnof(m, error, "Failed to write to brightness device: %m");
+                if (r < 0)
+                        log_warning_errno(r, "Failed to send method reply, ignoring: %m");
+        }
+}
+
+static int brightness_writer_fork(BrightnessWriter *w);
+
+static int on_brightness_writer_exit(sd_event_source *s, const siginfo_t *si, void *userdata) {
+        BrightnessWriter *w = userdata;
+        int r;
+
+        assert(s);
+        assert(si);
+        assert(w);
+
+        assert(si->si_pid == w->child);
+        w->child = 0;
+        w->child_event_source = sd_event_source_unref(w->child_event_source);
+
+        brightness_writer_reply(w,
+                                si->si_code == CLD_EXITED &&
+                                si->si_status == EXIT_SUCCESS ? 0 : -EPROTO);
+
+        if (w->again) {
+                /* Another request to change the brightness has been queued. Act on it, but make the pending
+                 * messages the current ones. */
+                w->again = false;
+                set_free(w->current_messages);
+                w->current_messages = TAKE_PTR(w->pending_messages);
+
+                r = brightness_writer_fork(w);
+                if (r >= 0)
+                        return 0;
+
+                brightness_writer_reply(w, r);
+        }
+
+        brightness_writer_free(w);
+        return 0;
+}
+
+static int brightness_writer_fork(BrightnessWriter *w) {
+        int r;
+
+        assert(w);
+        assert(w->manager);
+        assert(w->child == 0);
+        assert(!w->child_event_source);
+
+        r = safe_fork("(sd-bright)", FORK_DEATHSIG|FORK_NULL_STDIO|FORK_CLOSE_ALL_FDS|FORK_LOG, &w->child);
+        if (r < 0)
+                return r;
+        if (r == 0) {
+                char brs[DECIMAL_STR_MAX(uint32_t)+1];
+
+                /* Child */
+                xsprintf(brs, "%" PRIu32, w->brightness);
+
+                r = sd_device_set_sysattr_value(w->device, "brightness", brs);
+                if (r < 0) {
+                        log_device_error_errno(w->device, r, "Failed to write brightness to device: %m");
+                        _exit(EXIT_FAILURE);
+                }
+
+                _exit(EXIT_SUCCESS);
+        }
+
+        r = sd_event_add_child(w->manager->event, &w->child_event_source, w->child, WEXITED, on_brightness_writer_exit, w);
+        if (r < 0)
+                return log_error_errno(r, "Failed to watch brightness writer child " PID_FMT ": %m", w->child);
+
+        return 0;
+}
+
+static int set_add_message(Set **set, sd_bus_message *message) {
+        int r;
+
+        assert(set);
+
+        if (!message)
+                return 0;
+
+        r = sd_bus_message_get_expect_reply(message);
+        if (r <= 0)
+                return r;
+
+        r = set_ensure_allocated(set, &bus_message_hash_ops);
+        if (r < 0)
+                return r;
+
+        r = set_put(*set, message);
+        if (r < 0)
+                return r;
+
+        sd_bus_message_ref(message);
+        return 1;
+}
+
+int manager_write_brightness(
+                Manager *m,
+                sd_device *device,
+                uint32_t brightness,
+                sd_bus_message *message) {
+
+        _cleanup_(brightness_writer_freep) BrightnessWriter *w = NULL;
+        BrightnessWriter *existing;
+        const char *path;
+        int r;
+
+        assert(m);
+        assert(device);
+
+        r = sd_device_get_syspath(device, &path);
+        if (r < 0)
+                return log_device_error_errno(device, r, "Failed to get sysfs path for brightness device: %m");
+
+        existing = hashmap_get(m->brightness_writers, path);
+        if (existing) {
+                /* There's already a writer for this device. Let's update it with the new brightness, and add
+                 * our message to the set of message to reply when done. */
+
+                r = set_add_message(&existing->pending_messages, message);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to add message to set: %m");
+
+                /* We overide any previously requested brightness here: we coalesce writes, and the newest
+                 * requested brightness is the one we'll put into effect. */
+                existing->brightness = brightness;
+                existing->again = true; /* request another iteration of the writer when the current one is
+                                         * complete */
+                return 0;
+        }
+
+        r = hashmap_ensure_allocated(&m->brightness_writers, &brightness_writer_hash_ops);
+        if (r < 0)
+                return log_oom();
+
+        w = new(BrightnessWriter, 1);
+        if (!w)
+                return log_oom();
+
+        *w = (BrightnessWriter) {
+                .device = sd_device_ref(device),
+                .path = strdup(path),
+                .brightness = brightness,
+        };
+
+        if (!w->path)
+                return log_oom();
+
+        r = hashmap_put(m->brightness_writers, w->path, w);
+        if (r < 0)
+                return log_error_errno(r, "Failed to add brightness writer to hashmap: %m");
+        w->manager = m;
+
+        r = set_add_message(&w->current_messages, message);
+        if (r < 0)
+                return log_error_errno(r, "Failed to add message to set: %m");
+
+        r = brightness_writer_fork(w);
+        if (r < 0)
+                return r;
+
+        TAKE_PTR(w);
+        return 0;
+}
diff --git a/src/login/logind-brightness.h b/src/login/logind-brightness.h
new file mode 100644
index 0000000000..b22ee37ba7
--- /dev/null
+++ b/src/login/logind-brightness.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#include "sd-bus.h"
+#include "sd-device.h"
+
+#include "logind.h"
+
+int manager_write_brightness(Manager *m, sd_device *device, uint32_t brightness, sd_bus_message *message);
diff --git a/src/login/logind-dbus.c b/src/login/logind-dbus.c
index be767186ff..0e8925ab94 100644
--- a/src/login/logind-dbus.c
+++ b/src/login/logind-dbus.c
@@ -27,6 +27,10 @@
 #include "fileio.h"
 #include "format-util.h"
 #include "fs-util.h"
+#include "logind-dbus.h"
+#include "logind-seat-dbus.h"
+#include "logind-session-dbus.h"
+#include "logind-user-dbus.h"
 #include "logind.h"
 #include "missing_capability.h"
 #include "mkdir.h"
@@ -46,47 +50,78 @@
 #include "utmp-wtmp.h"
 #include "virt.h"
 
-static int get_sender_session(Manager *m, sd_bus_message *message, sd_bus_error *error, Session **ret) {
+static int get_sender_session(
+                Manager *m,
+                sd_bus_message *message,
+                bool consult_display,
+                sd_bus_error *error,
+                Session **ret) {
 
         _cleanup_(sd_bus_creds_unrefp) sd_bus_creds *creds = NULL;
+        Session *session = NULL;
         const char *name;
-        Session *session;
         int r;
 
-        /* Get client login session.  This is not what you are looking for these days,
-         * as apps may instead belong to a user service unit.  This includes terminal
-         * emulators and hence command-line apps. */
-        r = sd_bus_query_sender_creds(message, SD_BUS_CREDS_SESSION|SD_BUS_CREDS_AUGMENT, &creds);
+        /* Acquire the sender's session. This first checks if the sending process is inside a session itself,
+         * and returns that. If not and 'consult_display' is true, this returns the display session of the
+         * owning user of the caller. */
+
+        r = sd_bus_query_sender_creds(message,
+                                      SD_BUS_CREDS_SESSION|SD_BUS_CREDS_AUGMENT|
+                                      (consult_display ? SD_BUS_CREDS_OWNER_UID : 0), &creds);
         if (r < 0)
                 return r;
 
         r = sd_bus_creds_get_session(creds, &name);
-        if (r == -ENXIO)
-                goto err_no_session;
-        if (r < 0)
-                return r;
+        if (r < 0) {
+                if (r != -ENXIO)
+                        return r;
+
+                if (consult_display) {
+                        uid_t uid;
+
+                        r = sd_bus_creds_get_owner_uid(creds, &uid);
+                        if (r < 0) {
+                                if (r != -ENXIO)
+                                        return r;
+                        } else {
+                                User *user;
+
+                                user = hashmap_get(m->users, UID_TO_PTR(uid));
+                                if (user)
+                                        session = user->display;
+                        }
+                }
+        } else
+                session = hashmap_get(m->sessions, name);
 
-        session = hashmap_get(m->sessions, name);
         if (!session)
-                goto err_no_session;
+                return sd_bus_error_setf(error, BUS_ERROR_NO_SESSION_FOR_PID,
+                                         consult_display ?
+                                         "Caller does not belong to any known session and doesn't own any suitable session." :
+                                         "Caller does not belong to any known session.");
 
         *ret = session;
         return 0;
-
-err_no_session:
-        return sd_bus_error_setf(error, BUS_ERROR_NO_SESSION_FOR_PID,
-                                 "Caller does not belong to any known session");
 }
 
-int manager_get_session_from_creds(Manager *m, sd_bus_message *message, const char *name, sd_bus_error *error, Session **ret) {
+int manager_get_session_from_creds(
+                Manager *m,
+                sd_bus_message *message,
+                const char *name,
+                sd_bus_error *error,
+                Session **ret) {
+
         Session *session;
 
         assert(m);
         assert(message);
         assert(ret);
 
-        if (isempty(name))
-                return get_sender_session(m, message, error, ret);
+        if (SEAT_IS_SELF(name)) /* the caller's own session */
+                return get_sender_session(m, message, false, error, ret);
+        if (SEAT_IS_AUTO(name)) /* The caller's own session if they have one, otherwise their user's display session */
+                return get_sender_session(m, message, true, error, ret);
 
         session = hashmap_get(m->sessions, name);
         if (!session)
@@ -97,7 +132,6 @@ int manager_get_session_from_creds(Manager *m, sd_bus_message *message, const ch
 }
 
 static int get_sender_user(Manager *m, sd_bus_message *message, sd_bus_error *error, User **ret) {
-
         _cleanup_(sd_bus_creds_unrefp) sd_bus_creds *creds = NULL;
         uid_t uid;
         User *user;
@@ -109,21 +143,20 @@ static int get_sender_user(Manager *m, sd_bus_message *message, sd_bus_error *er
                 return r;
 
         r = sd_bus_creds_get_owner_uid(creds, &uid);
-        if (r == -ENXIO)
-                goto err_no_user;
-        if (r < 0)
-                return r;
+        if (r < 0) {
+                if (r != -ENXIO)
+                        return r;
+
+                user = NULL;
+        } else
+                user = hashmap_get(m->users, UID_TO_PTR(uid));
 
-        user = hashmap_get(m->users, UID_TO_PTR(uid));
         if (!user)
-                goto err_no_user;
+                return sd_bus_error_setf(error, BUS_ERROR_NO_USER_FOR_PID,
+                                         "Caller does not belong to any logged in or lingering user");
 
         *ret = user;
         return 0;
-
-err_no_user:
-        return sd_bus_error_setf(error, BUS_ERROR_NO_USER_FOR_PID,
-                                 "Caller does not belong to any logged in user or lingering user");
 }
 
 int manager_get_user_from_creds(Manager *m, sd_bus_message *message, uid_t uid, sd_bus_error *error, User **ret) {
@@ -145,7 +178,13 @@ int manager_get_user_from_creds(Manager *m, sd_bus_message *message, uid_t uid,
         return 0;
 }
 
-int manager_get_seat_from_creds(Manager *m, sd_bus_message *message, const char *name, sd_bus_error *error, Seat **ret) {
+int manager_get_seat_from_creds(
+                Manager *m,
+                sd_bus_message *message,
+                const char *name,
+                sd_bus_error *error,
+                Seat **ret) {
+
         Seat *seat;
         int r;
 
@@ -153,16 +192,17 @@ int manager_get_seat_from_creds(Manager *m, sd_bus_message *message, const char
         assert(message);
         assert(ret);
 
-        if (isempty(name)) {
+        if (SEAT_IS_SELF(name) || SEAT_IS_AUTO(name)) {
                 Session *session;
 
-                r = manager_get_session_from_creds(m, message, NULL, error, &session);
+                /* Use these special seat names as session names */
+                r = manager_get_session_from_creds(m, message, name, error, &session);
                 if (r < 0)
                         return r;
 
                 seat = session->seat;
                 if (!seat)
-                        return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_SEAT, "Session has no seat.");
+                        return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_SEAT, "Session '%s' has no seat.", session->id);
         } else {
                 seat = hashmap_get(m->seats, name);
                 if (!seat)
@@ -809,11 +849,9 @@ static int method_create_session(sd_bus_message *message, void *userdata, sd_bus
                 if (asprintf(&id, "%"PRIu32, audit_id) < 0)
                         return -ENOMEM;
 
-                /* Wut? There's already a session by this name and we
-                 * didn't find it above? Weird, then let's not trust
-                 * the audit data and let's better register a new
-                 * ID */
-                if (hashmap_get(m->sessions, id)) {
+                /* Wut? There's already a session by this name and we didn't find it above? Weird, then let's
+                 * not trust the audit data and let's better register a new ID */
+                if (hashmap_contains(m->sessions, id)) {
                         log_warning("Existing logind session ID %s used by new audit session, ignoring.", id);
                         audit_id = AUDIT_SESSION_INVALID;
                         id = mfree(id);
@@ -827,9 +865,13 @@ static int method_create_session(sd_bus_message *message, void *userdata, sd_bus
                         if (asprintf(&id, "c%lu", ++m->session_counter) < 0)
                                 return -ENOMEM;
 
-                } while (hashmap_get(m->sessions, id));
+                } while (hashmap_contains(m->sessions, id));
         }
 
+        /* The generated names should not clash with 'auto' or 'self' */
+        assert(!SESSION_IS_SELF(id));
+        assert(!SESSION_IS_AUTO(id));
+
         /* If we are not watching utmp already, try again */
         manager_reconnect_utmp(m);
 
@@ -990,8 +1032,7 @@ static int method_activate_session_on_seat(sd_bus_message *message, void *userda
         assert(message);
         assert(m);
 
-        /* Same as ActivateSession() but refuses to work if
-         * the seat doesn't match */
+        /* Same as ActivateSession() but refuses to work if the seat doesn't match */
 
         r = sd_bus_message_read(message, "ss", &session_name, &seat_name);
         if (r < 0)
@@ -1367,11 +1408,22 @@ static int method_attach_device(sd_bus_message *message, void *userdata, sd_bus_
         if (r < 0)
                 return r;
 
+        if (!path_is_normalized(sysfs))
+                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Path %s is not normalized", sysfs);
         if (!path_startswith(sysfs, "/sys"))
                 return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Path %s is not in /sys", sysfs);
 
-        if (!seat_name_is_valid(seat))
-                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Seat %s is not valid", seat);
+        if (SEAT_IS_SELF(seat) || SEAT_IS_AUTO(seat)) {
+                Seat *found;
+
+                r = manager_get_seat_from_creds(m, message, seat, error, &found);
+                if (r < 0)
+                        return r;
+
+                seat = found->id;
+
+        } else if (!seat_name_is_valid(seat)) /* Note that a seat does not have to exist yet for this operation to succeed */
+                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Seat name %s is not valid", seat);
 
         r = bus_verify_polkit_async(
                         message,
diff --git a/src/login/logind-dbus.h b/src/login/logind-dbus.h
new file mode 100644
index 0000000000..6c73a9654f
--- /dev/null
+++ b/src/login/logind-dbus.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#include "sd-bus.h"
+
+#include "logind.h"
+#include "logind-session.h"
+#include "logind-user.h"
+
+int manager_get_session_from_creds(Manager *m, sd_bus_message *message, const char *name, sd_bus_error *error, Session **ret);
+int manager_get_user_from_creds(Manager *m, sd_bus_message *message, uid_t uid, sd_bus_error *error, User **ret);
+int manager_get_seat_from_creds(Manager *m, sd_bus_message *message, const char *name, sd_bus_error *error, Seat **ret);
+
+int manager_dispatch_delayed(Manager *manager, bool timeout);
+
+int bus_manager_shutdown_or_sleep_now_or_later(Manager *m, const char *unit_name, InhibitWhat w, sd_bus_error *error);
+
+int match_job_removed(sd_bus_message *message, void *userdata, sd_bus_error *error);
+int match_unit_removed(sd_bus_message *message, void *userdata, sd_bus_error *error);
+int match_properties_changed(sd_bus_message *message, void *userdata, sd_bus_error *error);
+int match_reloading(sd_bus_message *message, void *userdata, sd_bus_error *error);
+
+int manager_send_changed(Manager *manager, const char *property, ...) _sentinel_;
+
+int manager_start_scope(Manager *manager, const char *scope, pid_t pid, const char *slice, const char *description, char **wants, char **after, const char *requires_mounts_for, sd_bus_message *more_properties, sd_bus_error *error, char **job);
+int manager_start_unit(Manager *manager, const char *unit, sd_bus_error *error, char **job);
+int manager_stop_unit(Manager *manager, const char *unit, sd_bus_error *error, char **job);
+int manager_abandon_scope(Manager *manager, const char *scope, sd_bus_error *error);
+int manager_kill_unit(Manager *manager, const char *unit, KillWho who, int signo, sd_bus_error *error);
+int manager_unit_is_active(Manager *manager, const char *unit, sd_bus_error *error);
+int manager_job_is_active(Manager *manager, const char *path, sd_bus_error *error);
diff --git a/src/login/logind-device.c b/src/login/logind-device.c
index e724365b13..20108544aa 100644
--- a/src/login/logind-device.c
+++ b/src/login/logind-device.c
@@ -4,6 +4,7 @@
 
 #include "alloc-util.h"
 #include "logind-device.h"
+#include "logind-seat-dbus.h"
 #include "util.h"
 
 Device* device_new(Manager *m, const char *sysfs, bool master) {
diff --git a/src/login/logind-inhibit.c b/src/login/logind-inhibit.c
index d427dcaa01..d963706dce 100644
--- a/src/login/logind-inhibit.c
+++ b/src/login/logind-inhibit.c
@@ -13,6 +13,7 @@
 #include "fd-util.h"
 #include "fileio.h"
 #include "format-util.h"
+#include "logind-dbus.h"
 #include "logind-inhibit.h"
 #include "mkdir.h"
 #include "parse-util.h"
diff --git a/src/login/logind-seat-dbus.c b/src/login/logind-seat-dbus.c
index 6ee5a1c95d..c33a0e0ad4 100644
--- a/src/login/logind-seat-dbus.c
+++ b/src/login/logind-seat-dbus.c
@@ -7,7 +7,10 @@
 #include "bus-common-errors.h"
 #include "bus-label.h"
 #include "bus-util.h"
+#include "logind-dbus.h"
+#include "logind-seat-dbus.h"
 #include "logind-seat.h"
+#include "logind-session-dbus.h"
 #include "logind.h"
 #include "missing_capability.h"
 #include "strv.h"
@@ -255,7 +258,10 @@ const sd_bus_vtable seat_vtable[] = {
 };
 
 int seat_object_find(sd_bus *bus, const char *path, const char *interface, void *userdata, void **found, sd_bus_error *error) {
+        _cleanup_free_ char *e = NULL;
+        sd_bus_message *message;
         Manager *m = userdata;
+        const char *p;
         Seat *seat;
         int r;
 
@@ -265,32 +271,25 @@ int seat_object_find(sd_bus *bus, const char *path, const char *interface, void
         assert(found);
         assert(m);
 
-        if (streq(path, "/org/freedesktop/login1/seat/self")) {
-                sd_bus_message *message;
-
-                message = sd_bus_get_current_message(bus);
-                if (!message)
-                        return 0;
-
-                r = manager_get_seat_from_creds(m, message, NULL, error, &seat);
-                if (r < 0)
-                        return r;
-        } else {
-                _cleanup_free_ char *e = NULL;
-                const char *p;
+        p = startswith(path, "/org/freedesktop/login1/seat/");
+        if (!p)
+                return 0;
 
-                p = startswith(path, "/org/freedesktop/login1/seat/");
-                if (!p)
-                        return 0;
+        e = bus_label_unescape(p);
+        if (!e)
+                return -ENOMEM;
 
-                e = bus_label_unescape(p);
-                if (!e)
-                        return -ENOMEM;
+        message = sd_bus_get_current_message(bus);
+        if (!message)
+                return 0;
 
-                seat = hashmap_get(m->seats, e);
-                if (!seat)
-                        return 0;
+        r = manager_get_seat_from_creds(m, message, e, error, &seat);
+        if (r == -ENXIO) {
+                sd_bus_error_free(error);
+                return 0;
         }
+        if (r < 0)
+                return r;
 
         *found = seat;
         return 1;
@@ -335,25 +334,47 @@ int seat_node_enumerator(sd_bus *bus, const char *path, void *userdata, char ***
         message = sd_bus_get_current_message(bus);
         if (message) {
                 _cleanup_(sd_bus_creds_unrefp) sd_bus_creds *creds = NULL;
-                const char *name;
-                Session *session;
 
-                r = sd_bus_query_sender_creds(message, SD_BUS_CREDS_SESSION|SD_BUS_CREDS_AUGMENT, &creds);
+                r = sd_bus_query_sender_creds(message, SD_BUS_CREDS_SESSION|SD_BUS_CREDS_OWNER_UID|SD_BUS_CREDS_AUGMENT, &creds);
                 if (r >= 0) {
+                        bool may_auto = false;
+                        const char *name;
+
                         r = sd_bus_creds_get_session(creds, &name);
                         if (r >= 0) {
+                                Session *session;
+
                                 session = hashmap_get(m->sessions, name);
                                 if (session && session->seat) {
                                         r = strv_extend(&l, "/org/freedesktop/login1/seat/self");
                                         if (r < 0)
                                                 return r;
+
+                                        may_auto = true;
                                 }
                         }
+
+                        if (!may_auto) {
+                                uid_t uid;
+
+                                r = sd_bus_creds_get_owner_uid(creds, &uid);
+                                if (r >= 0) {
+                                        User *user;
+
+                                        user = hashmap_get(m->users, UID_TO_PTR(uid));
+                                        may_auto = user && user->display && user->display->seat;
+                                }
+                        }
+
+                        if (may_auto) {
+                                r = strv_extend(&l, "/org/freedesktop/login1/seat/auto");
+                                if (r < 0)
+                                        return r;
+                        }
                 }
         }
 
         *nodes = TAKE_PTR(l);
-
         return 1;
 }
 
diff --git a/src/login/logind-seat-dbus.h b/src/login/logind-seat-dbus.h
new file mode 100644
index 0000000000..2590f64922
--- /dev/null
+++ b/src/login/logind-seat-dbus.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#include "sd-bus.h"
+
+#include "logind-seat.h"
+
+extern const sd_bus_vtable seat_vtable[];
+
+int seat_node_enumerator(sd_bus *bus, const char *path, void *userdata, char ***nodes, sd_bus_error *error);
+int seat_object_find(sd_bus *bus, const char *path, const char *interface, void *userdata, void **found, sd_bus_error *error);
+char *seat_bus_path(Seat *s);
+
+int seat_send_signal(Seat *s, bool new_seat);
+int seat_send_changed(Seat *s, const char *properties, ...) _sentinel_;
+
+int bus_seat_method_terminate(sd_bus_message *message, void *userdata, sd_bus_error *error);
diff --git a/src/login/logind-seat.c b/src/login/logind-seat.c
index f5ffb68238..dc578adf63 100644
--- a/src/login/logind-seat.c
+++ b/src/login/logind-seat.c
@@ -13,7 +13,9 @@
 #include "fileio.h"
 #include "format-util.h"
 #include "logind-acl.h"
+#include "logind-seat-dbus.h"
 #include "logind-seat.h"
+#include "logind-session-dbus.h"
 #include "mkdir.h"
 #include "parse-util.h"
 #include "stdio-util.h"
diff --git a/src/login/logind-seat.h b/src/login/logind-seat.h
index 6236f1360b..64cdf2f25a 100644
--- a/src/login/logind-seat.h
+++ b/src/login/logind-seat.h
@@ -67,13 +67,10 @@ void seat_add_to_gc_queue(Seat *s);
 
 bool seat_name_is_valid(const char *name);
 
-extern const sd_bus_vtable seat_vtable[];
+static inline bool SEAT_IS_SELF(const char *name) {
+        return isempty(name) || streq(name, "self");
+}
 
-int seat_node_enumerator(sd_bus *bus, const char *path, void *userdata, char ***nodes, sd_bus_error *error);
-int seat_object_find(sd_bus *bus, const char *path, const char *interface, void *userdata, void **found, sd_bus_error *error);
-char *seat_bus_path(Seat *s);
-
-int seat_send_signal(Seat *s, bool new_seat);
-int seat_send_changed(Seat *s, const char *properties, ...) _sentinel_;
-
-int bus_seat_method_terminate(sd_bus_message *message, void *userdata, sd_bus_error *error);
+static inline bool SEAT_IS_AUTO(const char *name) {
+        return streq_ptr(name, "auto");
+}
diff --git a/src/login/logind-session-dbus.c b/src/login/logind-session-dbus.c
index df5bfba982..c297f62cdf 100644
--- a/src/login/logind-session-dbus.c
+++ b/src/login/logind-session-dbus.c
@@ -8,13 +8,20 @@
 #include "bus-label.h"
 #include "bus-util.h"
 #include "fd-util.h"
+#include "logind-brightness.h"
+#include "logind-dbus.h"
+#include "logind-seat-dbus.h"
+#include "logind-session-dbus.h"
 #include "logind-session-device.h"
 #include "logind-session.h"
+#include "logind-user-dbus.h"
 #include "logind.h"
 #include "missing_capability.h"
+#include "path-util.h"
 #include "signal-util.h"
 #include "stat-util.h"
 #include "strv.h"
+#include "user-util.h"
 #include "util.h"
 
 static int property_get_user(
@@ -479,6 +486,57 @@ static int method_pause_device_complete(sd_bus_message *message, void *userdata,
         return sd_bus_reply_method_return(message, NULL);
 }
 
+static int method_set_brightness(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        _cleanup_(sd_bus_creds_unrefp) sd_bus_creds *creds = NULL;
+        _cleanup_(sd_device_unrefp) sd_device *d = NULL;
+        const char *subsystem, *name, *seat;
+        Session *s = userdata;
+        uint32_t brightness;
+        uid_t uid;
+        int r;
+
+        assert(message);
+        assert(s);
+
+        r = sd_bus_message_read(message, "ssu", &subsystem, &name, &brightness);
+        if (r < 0)
+                return r;
+
+        if (!STR_IN_SET(subsystem, "backlight", "leds"))
+                return sd_bus_error_setf(error, SD_BUS_ERROR_NOT_SUPPORTED, "Subsystem type %s not supported, must be one of 'backlight' or 'leds'.", subsystem);
+        if (!filename_is_valid(name))
+                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Not a valid device name %s, refusing.", name);
+
+        if (!s->seat)
+                return sd_bus_error_setf(error, BUS_ERROR_NOT_YOUR_DEVICE, "Your session has no seat, refusing.");
+        if (s->seat->active != s)
+                return sd_bus_error_setf(error, BUS_ERROR_NOT_YOUR_DEVICE, "Session is not in foreground, refusing.");
+
+        r = sd_bus_query_sender_creds(message, SD_BUS_CREDS_EUID, &creds);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_creds_get_euid(creds, &uid);
+        if (r < 0)
+                return r;
+
+        if (uid != 0 && uid != s->user->uid)
+                return sd_bus_error_setf(error, SD_BUS_ERROR_ACCESS_DENIED, "Only owner of session may change brightness.");
+
+        r = sd_device_new_from_subsystem_sysname(&d, subsystem, name);
+        if (r < 0)
+                return sd_bus_error_set_errnof(error, r, "Failed to open device %s:%s: %m", subsystem, name);
+
+        if (sd_device_get_property_value(d, "ID_SEAT", &seat) >= 0 && !streq_ptr(seat, s->seat->id))
+                return sd_bus_error_setf(error, BUS_ERROR_NOT_YOUR_DEVICE, "Device %s:%s does not belong to your seat %s, refusing.", subsystem, name, s->seat->id);
+
+        r = manager_write_brightness(s->manager, d, brightness, message);
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
 const sd_bus_vtable session_vtable[] = {
         SD_BUS_VTABLE_START(0),
 
@@ -519,6 +577,7 @@ const sd_bus_vtable session_vtable[] = {
         SD_BUS_METHOD("TakeDevice", "uu", "hb", method_take_device, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("ReleaseDevice", "uu", NULL, method_release_device, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("PauseDeviceComplete", "uu", NULL, method_pause_device_complete, SD_BUS_VTABLE_UNPRIVILEGED),
+        SD_BUS_METHOD("SetBrightness", "ssu", NULL, method_set_brightness, SD_BUS_VTABLE_UNPRIVILEGED),
 
         SD_BUS_SIGNAL("PauseDevice", "uus", 0),
         SD_BUS_SIGNAL("ResumeDevice", "uuh", 0),
@@ -529,8 +588,11 @@ const sd_bus_vtable session_vtable[] = {
 };
 
 int session_object_find(sd_bus *bus, const char *path, const char *interface, void *userdata, void **found, sd_bus_error *error) {
+        _cleanup_free_ char *e = NULL;
+        sd_bus_message *message;
         Manager *m = userdata;
         Session *session;
+        const char *p;
         int r;
 
         assert(bus);
@@ -539,32 +601,25 @@ int session_object_find(sd_bus *bus, const char *path, const char *interface, vo
         assert(found);
         assert(m);
 
-        if (streq(path, "/org/freedesktop/login1/session/self")) {
-                sd_bus_message *message;
-
-                message = sd_bus_get_current_message(bus);
-                if (!message)
-                        return 0;
-
-                r = manager_get_session_from_creds(m, message, NULL, error, &session);
-                if (r < 0)
-                        return r;
-        } else {
-                _cleanup_free_ char *e = NULL;
-                const char *p;
+        p = startswith(path, "/org/freedesktop/login1/session/");
+        if (!p)
+                return 0;
 
-                p = startswith(path, "/org/freedesktop/login1/session/");
-                if (!p)
-                        return 0;
+        e = bus_label_unescape(p);
+        if (!e)
+                return -ENOMEM;
 
-                e = bus_label_unescape(p);
-                if (!e)
-                        return -ENOMEM;
+        message = sd_bus_get_current_message(bus);
+        if (!message)
+                return 0;
 
-                session = hashmap_get(m->sessions, e);
-                if (!session)
-                        return 0;
+        r = manager_get_session_from_creds(m, message, e, error, &session);
+        if (r == -ENXIO) {
+                sd_bus_error_free(error);
+                return 0;
         }
+        if (r < 0)
+                return r;
 
         *found = session;
         return 1;
@@ -609,10 +664,12 @@ int session_node_enumerator(sd_bus *bus, const char *path, void *userdata, char
         message = sd_bus_get_current_message(bus);
         if (message) {
                 _cleanup_(sd_bus_creds_unrefp) sd_bus_creds *creds = NULL;
-                const char *name;
 
-                r = sd_bus_query_sender_creds(message, SD_BUS_CREDS_SESSION|SD_BUS_CREDS_AUGMENT, &creds);
+                r = sd_bus_query_sender_creds(message, SD_BUS_CREDS_SESSION|SD_BUS_CREDS_OWNER_UID|SD_BUS_CREDS_AUGMENT, &creds);
                 if (r >= 0) {
+                        bool may_auto = false;
+                        const char *name;
+
                         r = sd_bus_creds_get_session(creds, &name);
                         if (r >= 0) {
                                 session = hashmap_get(m->sessions, name);
@@ -620,13 +677,32 @@ int session_node_enumerator(sd_bus *bus, const char *path, void *userdata, char
                                         r = strv_extend(&l, "/org/freedesktop/login1/session/self");
                                         if (r < 0)
                                                 return r;
+
+                                        may_auto = true;
+                                }
+                        }
+
+                        if (!may_auto) {
+                                uid_t uid;
+
+                                r = sd_bus_creds_get_owner_uid(creds, &uid);
+                                if (r >= 0) {
+                                        User *user;
+
+                                        user = hashmap_get(m->users, UID_TO_PTR(uid));
+                                        may_auto = user && user->display;
                                 }
                         }
+
+                        if (may_auto) {
+                                r = strv_extend(&l, "/org/freedesktop/login1/session/auto");
+                                if (r < 0)
+                                        return r;
+                        }
                 }
         }
 
         *nodes = TAKE_PTR(l);
-
         return 1;
 }
 
diff --git a/src/login/logind-session-dbus.h b/src/login/logind-session-dbus.h
new file mode 100644
index 0000000000..9d2315cc60
--- /dev/null
+++ b/src/login/logind-session-dbus.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#include "sd-bus.h"
+
+#include "logind-session.h"
+
+extern const sd_bus_vtable session_vtable[];
+int session_node_enumerator(sd_bus *bus, const char *path,void *userdata, char ***nodes, sd_bus_error *error);
+int session_object_find(sd_bus *bus, const char *path, const char *interface, void *userdata, void **found, sd_bus_error *error);
+char *session_bus_path(Session *s);
+
+int session_send_signal(Session *s, bool new_session);
+int session_send_changed(Session *s, const char *properties, ...) _sentinel_;
+int session_send_lock(Session *s, bool lock);
+int session_send_lock_all(Manager *m, bool lock);
+
+int session_send_create_reply(Session *s, sd_bus_error *error);
+
+int bus_session_method_activate(sd_bus_message *message, void *userdata, sd_bus_error *error);
+int bus_session_method_lock(sd_bus_message *message, void *userdata, sd_bus_error *error);
+int bus_session_method_terminate(sd_bus_message *message, void *userdata, sd_bus_error *error);
+int bus_session_method_kill(sd_bus_message *message, void *userdata, sd_bus_error *error);
diff --git a/src/login/logind-session-device.c b/src/login/logind-session-device.c
index 3e2ff6d5b8..3057e72394 100644
--- a/src/login/logind-session-device.c
+++ b/src/login/logind-session-device.c
@@ -7,14 +7,15 @@
 #include <sys/types.h>
 
 #include "sd-device.h"
+#include "sd-daemon.h"
 
 #include "alloc-util.h"
 #include "bus-util.h"
 #include "fd-util.h"
+#include "logind-session-dbus.h"
 #include "logind-session-device.h"
 #include "missing.h"
 #include "parse-util.h"
-#include "sd-daemon.h"
 #include "util.h"
 
 enum SessionDeviceNotifications {
diff --git a/src/login/logind-session.c b/src/login/logind-session.c
index f1efeb0e01..17700c6921 100644
--- a/src/login/logind-session.c
+++ b/src/login/logind-session.c
@@ -22,7 +22,11 @@
 #include "fileio.h"
 #include "format-util.h"
 #include "io-util.h"
+#include "logind-dbus.h"
+#include "logind-seat-dbus.h"
+#include "logind-session-dbus.h"
 #include "logind-session.h"
+#include "logind-user-dbus.h"
 #include "mkdir.h"
 #include "parse-util.h"
 #include "path-util.h"
diff --git a/src/login/logind-session.h b/src/login/logind-session.h
index f3c17a8d91..50fe29e797 100644
--- a/src/login/logind-session.h
+++ b/src/login/logind-session.h
@@ -7,6 +7,7 @@ typedef enum KillWho KillWho;
 #include "list.h"
 #include "login-util.h"
 #include "logind-user.h"
+#include "string-util.h"
 
 typedef enum SessionState {
         SESSION_OPENING,  /* Session scope is being created */
@@ -145,18 +146,6 @@ int session_kill(Session *s, KillWho who, int signo);
 
 SessionState session_get_state(Session *u);
 
-extern const sd_bus_vtable session_vtable[];
-int session_node_enumerator(sd_bus *bus, const char *path,void *userdata, char ***nodes, sd_bus_error *error);
-int session_object_find(sd_bus *bus, const char *path, const char *interface, void *userdata, void **found, sd_bus_error *error);
-char *session_bus_path(Session *s);
-
-int session_send_signal(Session *s, bool new_session);
-int session_send_changed(Session *s, const char *properties, ...) _sentinel_;
-int session_send_lock(Session *s, bool lock);
-int session_send_lock_all(Manager *m, bool lock);
-
-int session_send_create_reply(Session *s, sd_bus_error *error);
-
 const char* session_state_to_string(SessionState t) _const_;
 SessionState session_state_from_string(const char *s) _pure_;
 
@@ -179,7 +168,10 @@ bool session_is_controller(Session *s, const char *sender);
 int session_set_controller(Session *s, const char *sender, bool force, bool prepare);
 void session_drop_controller(Session *s);
 
-int bus_session_method_activate(sd_bus_message *message, void *userdata, sd_bus_error *error);
-int bus_session_method_lock(sd_bus_message *message, void *userdata, sd_bus_error *error);
-int bus_session_method_terminate(sd_bus_message *message, void *userdata, sd_bus_error *error);
-int bus_session_method_kill(sd_bus_message *message, void *userdata, sd_bus_error *error);
+static inline bool SESSION_IS_SELF(const char *name) {
+        return isempty(name) || streq(name, "self");
+}
+
+static inline bool SESSION_IS_AUTO(const char *name) {
+        return streq_ptr(name, "auto");
+}
diff --git a/src/login/logind-user-dbus.c b/src/login/logind-user-dbus.c
index fcaeba13f6..beb97362e7 100644
--- a/src/login/logind-user-dbus.c
+++ b/src/login/logind-user-dbus.c
@@ -6,6 +6,9 @@
 #include "alloc-util.h"
 #include "bus-util.h"
 #include "format-util.h"
+#include "logind-dbus.h"
+#include "logind-session-dbus.h"
+#include "logind-user-dbus.h"
 #include "logind-user.h"
 #include "logind.h"
 #include "missing_capability.h"
@@ -245,6 +248,10 @@ int user_object_find(sd_bus *bus, const char *path, const char *interface, void
                         return 0;
 
                 r = manager_get_user_from_creds(m, message, UID_INVALID, error, &user);
+                if (r == -ENXIO) {
+                        sd_bus_error_free(error);
+                        return 0;
+                }
                 if (r < 0)
                         return r;
         } else {
@@ -305,10 +312,11 @@ int user_node_enumerator(sd_bus *bus, const char *path, void *userdata, char ***
         message = sd_bus_get_current_message(bus);
         if (message) {
                 _cleanup_(sd_bus_creds_unrefp) sd_bus_creds *creds = NULL;
-                uid_t uid;
 
                 r = sd_bus_query_sender_creds(message, SD_BUS_CREDS_OWNER_UID|SD_BUS_CREDS_AUGMENT, &creds);
                 if (r >= 0) {
+                        uid_t uid;
+
                         r = sd_bus_creds_get_owner_uid(creds, &uid);
                         if (r >= 0) {
                                 user = hashmap_get(m->users, UID_TO_PTR(uid));
diff --git a/src/login/logind-user-dbus.h b/src/login/logind-user-dbus.h
new file mode 100644
index 0000000000..acfcb981cf
--- /dev/null
+++ b/src/login/logind-user-dbus.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#include "sd-bus.h"
+
+#include "logind-user.h"
+
+extern const sd_bus_vtable user_vtable[];
+int user_node_enumerator(sd_bus *bus, const char *path, void *userdata, char ***nodes, sd_bus_error *error);
+int user_object_find(sd_bus *bus, const char *path, const char *interface, void *userdata, void **found, sd_bus_error *error);
+char *user_bus_path(User *s);
+
+int user_send_signal(User *u, bool new_user);
+int user_send_changed(User *u, const char *properties, ...) _sentinel_;
+
+int bus_user_method_terminate(sd_bus_message *message, void *userdata, sd_bus_error *error);
+int bus_user_method_kill(sd_bus_message *message, void *userdata, sd_bus_error *error);
diff --git a/src/login/logind-user.c b/src/login/logind-user.c
index c5d442865c..b17fb2e322 100644
--- a/src/login/logind-user.c
+++ b/src/login/logind-user.c
@@ -19,7 +19,9 @@
 #include "hashmap.h"
 #include "label.h"
 #include "limits-util.h"
+#include "logind-dbus.h"
 #include "logind-user.h"
+#include "logind-user-dbus.h"
 #include "mkdir.h"
 #include "parse-util.h"
 #include "path-util.h"
@@ -663,12 +665,12 @@ static bool elect_display_filter(Session *s) {
         /* Return true if the session is a candidate for the user’s ‘primary session’ or ‘display’. */
         assert(s);
 
-        return s->class == SESSION_USER && s->started && !s->stopping;
+        return IN_SET(s->class, SESSION_USER, SESSION_GREETER) && s->started && !s->stopping;
 }
 
 static int elect_display_compare(Session *s1, Session *s2) {
         /* Indexed by SessionType. Lower numbers mean more preferred. */
-        const int type_ranks[_SESSION_TYPE_MAX] = {
+        static const int type_ranks[_SESSION_TYPE_MAX] = {
                 [SESSION_UNSPECIFIED] = 0,
                 [SESSION_TTY] = -2,
                 [SESSION_X11] = -3,
diff --git a/src/login/logind-user.h b/src/login/logind-user.h
index c41973e27d..4bd65d8373 100644
--- a/src/login/logind-user.h
+++ b/src/login/logind-user.h
@@ -69,18 +69,7 @@ int user_check_linger_file(User *u);
 void user_elect_display(User *u);
 void user_update_last_session_timer(User *u);
 
-extern const sd_bus_vtable user_vtable[];
-int user_node_enumerator(sd_bus *bus, const char *path, void *userdata, char ***nodes, sd_bus_error *error);
-int user_object_find(sd_bus *bus, const char *path, const char *interface, void *userdata, void **found, sd_bus_error *error);
-char *user_bus_path(User *s);
-
-int user_send_signal(User *u, bool new_user);
-int user_send_changed(User *u, const char *properties, ...) _sentinel_;
-
 const char* user_state_to_string(UserState s) _const_;
 UserState user_state_from_string(const char *s) _pure_;
 
-int bus_user_method_terminate(sd_bus_message *message, void *userdata, sd_bus_error *error);
-int bus_user_method_kill(sd_bus_message *message, void *userdata, sd_bus_error *error);
-
 CONFIG_PARSER_PROTOTYPE(config_parse_compat_user_tasks_max);
diff --git a/src/login/logind.c b/src/login/logind.c
index 4c0e8ce6b1..d60223db68 100644
--- a/src/login/logind.c
+++ b/src/login/logind.c
@@ -18,6 +18,10 @@
 #include "fd-util.h"
 #include "format-util.h"
 #include "fs-util.h"
+#include "logind-dbus.h"
+#include "logind-seat-dbus.h"
+#include "logind-session-dbus.h"
+#include "logind-user-dbus.h"
 #include "logind.h"
 #include "main-func.h"
 #include "parse-util.h"
@@ -44,10 +48,9 @@ static int manager_new(Manager **ret) {
         *m = (Manager) {
                 .console_active_fd = -1,
                 .reserve_vt_fd = -1,
+                .idle_action_not_before_usec = now(CLOCK_MONOTONIC),
         };
 
-        m->idle_action_not_before_usec = now(CLOCK_MONOTONIC);
-
         m->devices = hashmap_new(&string_hash_ops);
         m->seats = hashmap_new(&string_hash_ops);
         m->sessions = hashmap_new(&string_hash_ops);
@@ -118,6 +121,7 @@ static Manager* manager_unref(Manager *m) {
         hashmap_free(m->users);
         hashmap_free(m->inhibitors);
         hashmap_free(m->buttons);
+        hashmap_free(m->brightness_writers);
 
         hashmap_free(m->user_units);
         hashmap_free(m->session_units);
@@ -1215,7 +1219,7 @@ static int run(int argc, char *argv[]) {
         (void) mkdir_label("/run/systemd/users", 0755);
         (void) mkdir_label("/run/systemd/sessions", 0755);
 
-        assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGHUP, SIGTERM, SIGINT, -1) >= 0);
+        assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGHUP, SIGTERM, SIGINT, SIGCHLD, -1) >= 0);
 
         r = manager_new(&m);
         if (r < 0)
diff --git a/src/login/logind.h b/src/login/logind.h
index 7b6f73c6ec..f260f2dc96 100644
--- a/src/login/logind.h
+++ b/src/login/logind.h
@@ -31,6 +31,7 @@ struct Manager {
         Hashmap *users;
         Hashmap *inhibitors;
         Hashmap *buttons;
+        Hashmap *brightness_writers;
 
         LIST_HEAD(Seat, seat_gc_queue);
         LIST_HEAD(Session, session_gc_queue);
@@ -158,24 +159,6 @@ void manager_reconnect_utmp(Manager *m);
 
 extern const sd_bus_vtable manager_vtable[];
 
-int match_job_removed(sd_bus_message *message, void *userdata, sd_bus_error *error);
-int match_unit_removed(sd_bus_message *message, void *userdata, sd_bus_error *error);
-int match_properties_changed(sd_bus_message *message, void *userdata, sd_bus_error *error);
-int match_reloading(sd_bus_message *message, void *userdata, sd_bus_error *error);
-int match_name_owner_changed(sd_bus_message *message, void *userdata, sd_bus_error *error);
-
-int bus_manager_shutdown_or_sleep_now_or_later(Manager *m, const char *unit_name, InhibitWhat w, sd_bus_error *error);
-
-int manager_send_changed(Manager *manager, const char *property, ...) _sentinel_;
-
-int manager_start_scope(Manager *manager, const char *scope, pid_t pid, const char *slice, const char *description, char **wants, char **after, const char *requires_mounts_for, sd_bus_message *more_properties, sd_bus_error *error, char **job);
-int manager_start_unit(Manager *manager, const char *unit, sd_bus_error *error, char **job);
-int manager_stop_unit(Manager *manager, const char *unit, sd_bus_error *error, char **job);
-int manager_abandon_scope(Manager *manager, const char *scope, sd_bus_error *error);
-int manager_kill_unit(Manager *manager, const char *unit, KillWho who, int signo, sd_bus_error *error);
-int manager_unit_is_active(Manager *manager, const char *unit, sd_bus_error *error);
-int manager_job_is_active(Manager *manager, const char *path, sd_bus_error *error);
-
 /* gperf lookup function */
 const struct ConfigPerfItem* logind_gperf_lookup(const char *key, GPERF_LEN_TYPE length);
 
@@ -184,11 +167,5 @@ int manager_set_lid_switch_ignore(Manager *m, usec_t until);
 CONFIG_PARSER_PROTOTYPE(config_parse_n_autovts);
 CONFIG_PARSER_PROTOTYPE(config_parse_tmpfs_size);
 
-int manager_get_session_from_creds(Manager *m, sd_bus_message *message, const char *name, sd_bus_error *error, Session **ret);
-int manager_get_user_from_creds(Manager *m, sd_bus_message *message, uid_t uid, sd_bus_error *error, User **ret);
-int manager_get_seat_from_creds(Manager *m, sd_bus_message *message, const char *name, sd_bus_error *error, Seat **ret);
-
 int manager_setup_wall_message_timer(Manager *m);
 bool logind_wall_tty_filter(const char *tty, void *userdata);
-
-int manager_dispatch_delayed(Manager *manager, bool timeout);
diff --git a/src/login/meson.build b/src/login/meson.build
index 1cc75fd1cf..832274af78 100644
--- a/src/login/meson.build
+++ b/src/login/meson.build
@@ -12,29 +12,35 @@ logind_gperf_c = custom_target(
         command : [gperf, '@INPUT@', '--output-file', '@OUTPUT@'])
 
 liblogind_core_sources = files('''
+        logind-acl.h
+        logind-action.c
+        logind-action.h
+        logind-brightness.c
+        logind-brightness.h
+        logind-button.c
+        logind-button.h
         logind-core.c
+        logind-dbus.c
+        logind-dbus.h
         logind-device.c
         logind-device.h
-        logind-button.c
-        logind-button.h
-        logind-action.c
-        logind-action.h
+        logind-inhibit.c
+        logind-inhibit.h
+        logind-seat-dbus.c
+        logind-seat-dbus.h
         logind-seat.c
         logind-seat.h
-        logind-session.c
-        logind-session.h
+        logind-session-dbus.c
+        logind-session-dbus.h
         logind-session-device.c
         logind-session-device.h
+        logind-session.c
+        logind-session.h
+        logind-user-dbus.c
+        logind-user-dbus.h
         logind-user.c
         logind-user.h
-        logind-inhibit.c
-        logind-inhibit.h
-        logind-dbus.c
-        logind-session-dbus.c
-        logind-seat-dbus.c
-        logind-user-dbus.c
         logind-utmp.c
-        logind-acl.h
 '''.split())
 
 liblogind_core_sources += [logind_gperf_c]
diff --git a/src/login/org.freedesktop.login1.conf b/src/login/org.freedesktop.login1.conf
index f3c13ad89a..124a25810e 100644
--- a/src/login/org.freedesktop.login1.conf
+++ b/src/login/org.freedesktop.login1.conf
@@ -303,6 +303,10 @@
                        send_member="PauseDeviceComplete"/>
 
                 <allow send_destination="org.freedesktop.login1"
+                       send_interface="org.freedesktop.login1.Session"
+                       send_member="SetBrightness"/>
+
+                <allow send_destination="org.freedesktop.login1"
                        send_interface="org.freedesktop.login1.User"
                        send_member="Terminate"/>
 
diff --git a/src/shared/bus-util.c b/src/shared/bus-util.c
index c2440271fe..81acff4602 100644
--- a/src/shared/bus-util.c
+++ b/src/shared/bus-util.c
@@ -1767,3 +1767,13 @@ int bus_reply_pair_array(sd_bus_message *m, char **l) {
 
         return sd_bus_send(NULL, reply, NULL);
 }
+
+static void bus_message_unref_wrapper(void *m) {
+        sd_bus_message_unref(m);
+}
+
+const struct hash_ops bus_message_hash_ops = {
+        .hash = trivial_hash_func,
+        .compare = trivial_compare_func,
+        .free_value = bus_message_unref_wrapper,
+};
diff --git a/src/shared/bus-util.h b/src/shared/bus-util.h
index 59bfdb2398..3216b0c37a 100644
--- a/src/shared/bus-util.h
+++ b/src/shared/bus-util.h
@@ -179,3 +179,5 @@ static inline int bus_open_system_watch_bind(sd_bus **ret) {
 }
 
 int bus_reply_pair_array(sd_bus_message *m, char **l);
+
+extern const struct hash_ops bus_message_hash_ops;
diff --git a/units/systemd-logind.service.in b/units/systemd-logind.service.in
index 3eef95c661..8a7262776f 100644
--- a/units/systemd-logind.service.in
+++ b/units/systemd-logind.service.in
@@ -43,6 +43,7 @@ RestrictRealtime=yes
 RestrictSUIDSGID=yes
 RuntimeDirectory=systemd/sessions systemd/seats systemd/users systemd/inhibit systemd/shutdown
 RuntimeDirectoryPreserve=yes
+StateDirectory=systemd/linger
 SystemCallArchitectures=native
 SystemCallErrorNumber=EPERM
 SystemCallFilter=@system-service