login: receive synthetic events for devices with 'uaccess' tag (#37654)

Fixes #37579.

src/login/logind-seat.c

@@ -30,6 +30,7 @@
 #include "string-util.h"
 #include "terminal-util.h"
 #include "tmpfile-util.h"
+#include "udev-util.h"
 #include "user-record.h"
 
 int seat_new(Manager *m, const char *id, Seat **ret) {
@@ -205,8 +206,10 @@ int seat_preallocate_vts(Seat *s) {
 static void seat_triggered_uevents_done(Seat *s) {
         assert(s);
 
-        if (!set_isempty(s->uevents))
+        if (!set_isempty(s->uevents)) {
+                log_debug("%s: waiting for %u events being processed by udevd.", s->id, set_size(s->uevents));
                 return;
+        }
 
         Session *session = s->active;
 
@@ -244,6 +247,7 @@ int manager_process_device_triggered_by_seat(Manager *m, sd_device *dev) {
         if (!s)
                 return 0;
 
+        log_device_uevent(dev, "Received event processed by udevd");
         free(ASSERT_PTR(set_remove(s->uevents, &uuid)));
         seat_triggered_uevents_done(s);
 
@@ -306,6 +310,8 @@ static int seat_trigger_devices(Seat *s) {
                         continue;
                 }
 
+                log_device_debug(d, "Triggered synthetic event (ACTION=change, UUID=%s).", SD_ID128_TO_UUID_STRING(uuid));
+
                 _cleanup_free_ sd_id128_t *copy = newdup(sd_id128_t, &uuid, 1);
                 if (!copy)
                         return -ENOMEM;

src/login/logind.c

@@ -152,6 +152,7 @@ static Manager* manager_free(Manager *m) {
         sd_device_monitor_unref(m->device_monitor);
         sd_device_monitor_unref(m->device_vcsa_monitor);
         sd_device_monitor_unref(m->device_button_monitor);
+        sd_device_monitor_unref(m->device_uaccess_monitor);
 
         if (m->unlink_nologin)
                 (void) unlink_or_warn("/run/nologin");
@@ -655,6 +656,35 @@ static int manager_dispatch_device_udev(sd_device_monitor *monitor, sd_device *d
         return 0;
 }
 
+static int manager_dispatch_uaccess_udev(sd_device_monitor *monitor, sd_device *device, void *userdata) {
+        Manager *m = ASSERT_PTR(userdata);
+        int r;
+
+        assert(device);
+
+        /* If the device currently has "master-of-seat" tag, then it has been or will be processed by
+         * manager_dispatch_seat_udev(). */
+        r = sd_device_has_current_tag(device, "master-of-seat");
+        if (r < 0)
+                log_device_warning_errno(device, r, "Failed to check if the device currently has master-of-seat tag, ignoring: %m");
+        if (r != 0)
+                return 0;
+
+        /* If the device is in input, graphics, or drm, then the event has been or will be processed by
+         * manager_dispatch_device_udev(). */
+        r = device_in_subsystem(device, "input", "graphics", "drm");
+        if (r < 0)
+                log_device_warning_errno(device, r, "Failed to check device subsystem, ignoring: %m");
+        if (r != 0)
+                return 0;
+
+        r = manager_process_device_triggered_by_seat(m, device);
+        if (r < 0)
+                log_device_warning_errno(device, r, "Failed to process seat device event triggered by us, ignoring: %m");
+
+        return 0;
+}
+
 static int manager_dispatch_vcsa_udev(sd_device_monitor *monitor, sd_device *device, void *userdata) {
         Manager *m = ASSERT_PTR(userdata);
         int r;
@@ -893,6 +923,7 @@ static int manager_connect_udev(Manager *m) {
         assert(m);
         assert(!m->device_seat_monitor);
         assert(!m->device_monitor);
+        assert(!m->device_uaccess_monitor);
         assert(!m->device_vcsa_monitor);
         assert(!m->device_button_monitor);
 
@@ -934,6 +965,24 @@ static int manager_connect_udev(Manager *m) {
 
         (void) sd_device_monitor_set_description(m->device_monitor, "input,graphics,drm");
 
+        r = sd_device_monitor_new(&m->device_uaccess_monitor);
+        if (r < 0)
+                return r;
+
+        r = sd_device_monitor_filter_add_match_tag(m->device_uaccess_monitor, "uaccess");
+        if (r < 0)
+                return r;
+
+        r = sd_device_monitor_attach_event(m->device_uaccess_monitor, m->event);
+        if (r < 0)
+                return r;
+
+        r = sd_device_monitor_start(m->device_uaccess_monitor, manager_dispatch_uaccess_udev, m);
+        if (r < 0)
+                return r;
+
+        (void) sd_device_monitor_set_description(m->device_uaccess_monitor, "uaccess");
+
         /* Don't watch keys if nobody cares */
         if (!manager_all_buttons_ignored(m)) {
                 r = sd_device_monitor_new(&m->device_button_monitor);

src/login/logind.h

@@ -25,7 +25,11 @@ typedef struct Manager {
         LIST_HEAD(Session, session_gc_queue);
         LIST_HEAD(User, user_gc_queue);
 
-        sd_device_monitor *device_seat_monitor, *device_monitor, *device_vcsa_monitor, *device_button_monitor;
+        sd_device_monitor *device_seat_monitor;
+        sd_device_monitor *device_monitor;
+        sd_device_monitor *device_vcsa_monitor;
+        sd_device_monitor *device_button_monitor;
+        sd_device_monitor *device_uaccess_monitor;
 
         sd_event_source *console_active_event_source;