chiark / gitweb /
logind: get a fresh file descriptor to clean up a VT
[elogind.git] / src / login / logind-session.c
index fa8b515..1a5c76b 100644 (file)
 ***/
 
 #include <errno.h>
+#include <fcntl.h>
+#include <linux/vt.h>
+#include <linux/kd.h>
+#include <signal.h>
 #include <string.h>
+#include <sys/ioctl.h>
 #include <unistd.h>
-#include <sys/epoll.h>
-#include <fcntl.h>
 
-#include <systemd/sd-id128.h>
-#include <systemd/sd-messages.h>
-
-#include "strv.h"
+#include "sd-messages.h"
 #include "util.h"
 #include "mkdir.h"
 #include "path-util.h"
 #include "fileio.h"
-#include "dbus-common.h"
+#include "audit.h"
+#include "bus-util.h"
+#include "bus-error.h"
 #include "logind-session.h"
+#include "formats-util.h"
+#include "terminal-util.h"
+
+#define RELEASE_USEC (20*USEC_PER_SEC)
+
+static void session_remove_fifo(Session *s);
 
 Session* session_new(Manager *m, const char *id) {
         Session *s;
@@ -53,9 +61,17 @@ Session* session_new(Manager *m, const char *id) {
                 return NULL;
         }
 
-        s->id = path_get_file_name(s->state_file);
+        s->devices = hashmap_new(&devt_hash_ops);
+        if (!s->devices) {
+                free(s->state_file);
+                free(s);
+                return NULL;
+        }
+
+        s->id = basename(s->state_file);
 
         if (hashmap_put(m->sessions, s->id, s) < 0) {
+                hashmap_free(s->devices);
                 free(s->state_file);
                 free(s);
                 return NULL;
@@ -63,20 +79,32 @@ Session* session_new(Manager *m, const char *id) {
 
         s->manager = m;
         s->fifo_fd = -1;
+        s->vtfd = -1;
 
         return s;
 }
 
 void session_free(Session *s) {
+        SessionDevice *sd;
+
         assert(s);
 
         if (s->in_gc_queue)
-                LIST_REMOVE(Session, gc_queue, s->manager->session_gc_queue, s);
+                LIST_REMOVE(gc_queue, s->manager->session_gc_queue, s);
+
+        s->timer_event_source = sd_event_source_unref(s->timer_event_source);
+
+        session_remove_fifo(s);
 
         session_drop_controller(s);
 
+        while ((sd = hashmap_first(s->devices)))
+                session_device_free(sd);
+
+        hashmap_free(s->devices);
+
         if (s->user) {
-                LIST_REMOVE(Session, sessions_by_user, s->user->sessions, s);
+                LIST_REMOVE(sessions_by_user, s->user->sessions, s);
 
                 if (s->user->display == s)
                         s->user->display = NULL;
@@ -85,8 +113,11 @@ void session_free(Session *s) {
         if (s->seat) {
                 if (s->seat->active == s)
                         s->seat->active = NULL;
+                if (s->seat->pending_switch == s)
+                        s->seat->pending_switch = NULL;
 
-                LIST_REMOVE(Session, sessions_by_seat, s->seat->sessions, s);
+                seat_evict_position(s->seat, s);
+                LIST_REMOVE(sessions_by_seat, s->seat->sessions, s);
         }
 
         if (s->scope) {
@@ -96,17 +127,16 @@ void session_free(Session *s) {
 
         free(s->scope_job);
 
-        if (s->create_message)
-                dbus_message_unref(s->create_message);
+        sd_bus_message_unref(s->create_message);
 
         free(s->tty);
         free(s->display);
         free(s->remote_host);
         free(s->remote_user);
         free(s->service);
+        free(s->desktop);
 
         hashmap_remove(s->manager->sessions, s->id);
-        session_remove_fifo(s);
 
         free(s->state_file);
         free(s);
@@ -117,12 +147,12 @@ void session_set_user(Session *s, User *u) {
         assert(!s->user);
 
         s->user = u;
-        LIST_PREPEND(Session, sessions_by_user, u->sessions, s);
+        LIST_PREPEND(sessions_by_user, u->sessions, s);
 }
 
 int session_save(Session *s) {
-        _cleanup_fclose_ FILE *f = NULL;
         _cleanup_free_ char *temp_path = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
         int r = 0;
 
         assert(s);
@@ -147,12 +177,12 @@ int session_save(Session *s) {
 
         fprintf(f,
                 "# This is private data. Do not parse.\n"
-                "UID=%lu\n"
+                "UID="UID_FMT"\n"
                 "USER=%s\n"
                 "ACTIVE=%i\n"
                 "STATE=%s\n"
                 "REMOTE=%i\n",
-                (unsigned long) s->user->uid,
+                s->user->uid,
                 s->user->name,
                 session_is_active(s),
                 session_state_to_string(session_get_state(s)),
@@ -166,7 +196,6 @@ int session_save(Session *s) {
 
         if (s->scope)
                 fprintf(f, "SCOPE=%s\n", s->scope);
-
         if (s->scope_job)
                 fprintf(f, "SCOPE_JOB=%s\n", s->scope_job);
 
@@ -182,30 +211,76 @@ int session_save(Session *s) {
         if (s->display)
                 fprintf(f, "DISPLAY=%s\n", s->display);
 
-        if (s->remote_host)
-                fprintf(f, "REMOTE_HOST=%s\n", s->remote_host);
+        if (s->remote_host) {
+                _cleanup_free_ char *escaped;
+
+                escaped = cescape(s->remote_host);
+                if (!escaped) {
+                        r = -ENOMEM;
+                        goto finish;
+                }
+
+                fprintf(f, "REMOTE_HOST=%s\n", escaped);
+        }
+
+        if (s->remote_user) {
+                _cleanup_free_ char *escaped;
+
+                escaped = cescape(s->remote_user);
+                if (!escaped) {
+                        r = -ENOMEM;
+                        goto finish;
+                }
+
+                fprintf(f, "REMOTE_USER=%s\n", escaped);
+        }
+
+        if (s->service) {
+                _cleanup_free_ char *escaped;
+
+                escaped = cescape(s->service);
+                if (!escaped) {
+                        r = -ENOMEM;
+                        goto finish;
+                }
+
+                fprintf(f, "SERVICE=%s\n", escaped);
+        }
+
+        if (s->desktop) {
+                _cleanup_free_ char *escaped;
 
-        if (s->remote_user)
-                fprintf(f, "REMOTE_USER=%s\n", s->remote_user);
 
-        if (s->service)
-                fprintf(f, "SERVICE=%s\n", s->service);
+                escaped = cescape(s->desktop);
+                if (!escaped) {
+                        r = -ENOMEM;
+                        goto finish;
+                }
 
-        if (s->seat && seat_can_multi_session(s->seat))
-                fprintf(f, "VTNR=%i\n", s->vtnr);
+                fprintf(f, "DESKTOP=%s\n", escaped);
+        }
+
+        if (s->seat && seat_has_vts(s->seat))
+                fprintf(f, "VTNR=%u\n", s->vtnr);
+
+        if (!s->vtnr)
+                fprintf(f, "POSITION=%u\n", s->position);
 
         if (s->leader > 0)
-                fprintf(f, "LEADER=%lu\n", (unsigned long) s->leader);
+                fprintf(f, "LEADER="PID_FMT"\n", s->leader);
 
         if (s->audit_id > 0)
                 fprintf(f, "AUDIT=%"PRIu32"\n", s->audit_id);
 
         if (dual_timestamp_is_set(&s->timestamp))
                 fprintf(f,
-                        "REALTIME=%llu\n"
-                        "MONOTONIC=%llu\n",
-                        (unsigned long long) s->timestamp.realtime,
-                        (unsigned long long) s->timestamp.monotonic);
+                        "REALTIME="USEC_FMT"\n"
+                        "MONOTONIC="USEC_FMT"\n",
+                        s->timestamp.realtime,
+                        s->timestamp.monotonic);
+
+        if (s->controller)
+                fprintf(f, "CONTROLLER=%s\n", s->controller);
 
         fflush(f);
 
@@ -217,7 +292,7 @@ int session_save(Session *s) {
 
 finish:
         if (r < 0)
-                log_error("Failed to save session data for %s: %s", s->id, strerror(-r));
+                log_error_errno(r, "Failed to save session data %s: %m", s->state_file);
 
         return r;
 }
@@ -226,13 +301,15 @@ int session_load(Session *s) {
         _cleanup_free_ char *remote = NULL,
                 *seat = NULL,
                 *vtnr = NULL,
+                *state = NULL,
+                *position = NULL,
                 *leader = NULL,
-                *audit_id = NULL,
                 *type = NULL,
                 *class = NULL,
                 *uid = NULL,
                 *realtime = NULL,
-                *monotonic = NULL;
+                *monotonic = NULL,
+                *controller = NULL;
 
         int k, r;
 
@@ -249,19 +326,21 @@ int session_load(Session *s) {
                            "REMOTE_HOST",    &s->remote_host,
                            "REMOTE_USER",    &s->remote_user,
                            "SERVICE",        &s->service,
+                           "DESKTOP",        &s->desktop,
                            "VTNR",           &vtnr,
+                           "STATE",          &state,
+                           "POSITION",       &position,
                            "LEADER",         &leader,
                            "TYPE",           &type,
                            "CLASS",          &class,
                            "UID",            &uid,
                            "REALTIME",       &realtime,
                            "MONOTONIC",      &monotonic,
+                           "CONTROLLER",     &controller,
                            NULL);
 
-        if (r < 0) {
-                log_error("Failed to read %s: %s", s->state_file, strerror(-r));
-                return r;
-        }
+        if (r < 0)
+                return log_error_errno(r, "Failed to read %s: %m", s->state_file);
 
         if (!s->user) {
                 uid_t u;
@@ -278,7 +357,7 @@ int session_load(Session *s) {
                         return r;
                 }
 
-                user = hashmap_get(s->manager->users, ULONG_TO_PTR((unsigned long) u));
+                user = hashmap_get(s->manager->users, UID_TO_PTR(u));
                 if (!user) {
                         log_error("User of session %s not known.", s->id);
                         return -ENOENT;
@@ -293,20 +372,27 @@ int session_load(Session *s) {
                         s->remote = k;
         }
 
+        if (vtnr)
+                safe_atou(vtnr, &s->vtnr);
+
         if (seat && !s->seat) {
                 Seat *o;
 
                 o = hashmap_get(s->manager->seats, seat);
                 if (o)
-                        seat_attach_session(o, s);
+                        r = seat_attach_session(o, s);
+                if (!o || r < 0)
+                        log_error("Cannot attach session %s to seat %s", s->id, seat);
         }
 
-        if (vtnr && s->seat && seat_can_multi_session(s->seat)) {
-                int v;
+        if (!s->seat || !seat_has_vts(s->seat))
+                s->vtnr = 0;
+
+        if (position && s->seat) {
+                unsigned int npos;
 
-                k = safe_atoi(vtnr, &v);
-                if (k >= 0 && v >= 1)
-                        s->vtnr = v;
+                safe_atou(position, &npos);
+                seat_claim_position(s->seat, s, npos);
         }
 
         if (leader) {
@@ -331,17 +417,21 @@ int session_load(Session *s) {
                         s->class = c;
         }
 
+        if (state && streq(state, "closing"))
+                s->stopping = true;
+
         if (s->fifo_path) {
                 int fd;
 
                 /* If we open an unopened pipe for reading we will not
                    get an EOF. to trigger an EOF we hence open it for
-                   reading, but close it right-away which then will
-                   trigger the EOF. */
+                   writing, but close it right away which then will
+                   trigger the EOF. This will happen immediately if no
+                   other process has the FIFO open for writing, i. e.
+                   when the session died before logind (re)started. */
 
                 fd = session_create_fifo(s);
-                if (fd >= 0)
-                        close_nointr_nofail(fd);
+                safe_close(fd);
         }
 
         if (realtime) {
@@ -356,107 +446,64 @@ int session_load(Session *s) {
                         s->timestamp.monotonic = l;
         }
 
+        if (controller) {
+                if (bus_name_has_owner(s->manager->bus, controller, NULL) > 0)
+                        session_set_controller(s, controller, false);
+                else
+                        session_restore_vt(s);
+        }
+
         return r;
 }
 
 int session_activate(Session *s) {
+        unsigned int num_pending;
+
         assert(s);
         assert(s->user);
 
-        if (s->vtnr < 0)
-                return -ENOTSUP;
-
         if (!s->seat)
-                return -ENOTSUP;
+                return -EOPNOTSUPP;
 
         if (s->seat->active == s)
                 return 0;
 
-        assert(seat_is_vtconsole(s->seat));
-
-        return chvt(s->vtnr);
-}
-
-static int session_link_x11_socket(Session *s) {
-        _cleanup_free_ char *t = NULL, *f = NULL;
-        char *c;
-        size_t k;
-
-        assert(s);
-        assert(s->user);
-        assert(s->user->runtime_path);
-
-        if (s->user->display)
-                return 0;
-
-        if (!s->display || !display_is_local(s->display))
-                return 0;
-
-        k = strspn(s->display+1, "0123456789");
-        f = new(char, sizeof("/tmp/.X11-unix/X") + k);
-        if (!f)
-                return log_oom();
-
-        c = stpcpy(f, "/tmp/.X11-unix/X");
-        memcpy(c, s->display+1, k);
-        c[k] = 0;
+        /* on seats with VTs, we let VTs manage session-switching */
+        if (seat_has_vts(s->seat)) {
+                if (!s->vtnr)
+                        return -EOPNOTSUPP;
 
-        if (access(f, F_OK) < 0) {
-                log_warning("Session %s has display %s with non-existing socket %s.", s->id, s->display, f);
-                return -ENOENT;
+                return chvt(s->vtnr);
         }
 
-        /* Note that this cannot be in a subdir to avoid
-         * vulnerabilities since we are privileged but the runtime
-         * path is owned by the user */
+        /* On seats without VTs, we implement session-switching in logind. We
+         * try to pause all session-devices and wait until the session
+         * controller acknowledged them. Once all devices are asleep, we simply
+         * switch the active session and be done.
+         * We save the session we want to switch to in seat->pending_switch and
+         * seat_complete_switch() will perform the final switch. */
 
-        t = strappend(s->user->runtime_path, "/X11-display");
-        if (!t)
-                return log_oom();
+        s->seat->pending_switch = s;
 
-        if (link(f, t) < 0) {
-                if (errno == EEXIST) {
-                        unlink(t);
-
-                        if (link(f, t) >= 0)
-                                goto done;
-                }
-
-                if (symlink(f, t) < 0) {
-
-                        if (errno == EEXIST) {
-                                unlink(t);
-
-                                if (symlink(f, t) >= 0)
-                                        goto done;
-                        }
-
-                        log_error("Failed to link %s to %s: %m", f, t);
-                        return -errno;
-                }
-        }
-
-done:
-        log_info("Linked %s to %s.", f, t);
-        s->user->display = s;
+        /* if no devices are running, immediately perform the session switch */
+        num_pending = session_device_try_pause_all(s);
+        if (!num_pending)
+                seat_complete_switch(s->seat);
 
         return 0;
 }
 
 static int session_start_scope(Session *s) {
-        DBusError error;
         int r;
 
         assert(s);
         assert(s->user);
         assert(s->user->slice);
 
-        dbus_error_init(&error);
-
         if (!s->scope) {
+                _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
                 _cleanup_free_ char *description = NULL;
-                const char *kill_mode;
-                char *scope, *job;
+                char *scope, *job = NULL;
 
                 description = strjoin("Session ", s->id, " of user ", s->user->name, NULL);
                 if (!description)
@@ -466,14 +513,10 @@ static int session_start_scope(Session *s) {
                 if (!scope)
                         return log_oom();
 
-                kill_mode = manager_shall_kill(s->manager, s->user->name) ? "control-group" : "none";
-
-                r = manager_start_scope(s->manager, scope, s->leader, s->user->slice, description, "systemd-user-sessions.service", kill_mode, &error, &job);
+                r = manager_start_scope(s->manager, scope, s->leader, s->user->slice, description, "systemd-logind.service", "systemd-user-sessions.service", &error, &job);
                 if (r < 0) {
                         log_error("Failed to start session scope %s: %s %s",
-                                  scope, bus_error(&error, r), error.name);
-                        dbus_error_free(&error);
-
+                                  scope, bus_error_message(&error, r), error.name);
                         free(scope);
                         return r;
                 } else {
@@ -510,17 +553,14 @@ int session_start(Session *s) {
         if (r < 0)
                 return r;
 
-        log_struct(s->type == SESSION_TTY || s->type == SESSION_X11 ? LOG_INFO : LOG_DEBUG,
-                   MESSAGE_ID(SD_MESSAGE_SESSION_START),
+        log_struct(s->class == SESSION_BACKGROUND ? LOG_DEBUG : LOG_INFO,
+                   LOG_MESSAGE_ID(SD_MESSAGE_SESSION_START),
                    "SESSION_ID=%s", s->id,
                    "USER_ID=%s", s->user->name,
-                   "LEADER=%lu", (unsigned long) s->leader,
-                   "MESSAGE=New session %s of user %s.", s->id, s->user->name,
+                   "LEADER="PID_FMT, s->leader,
+                   LOG_MESSAGE("New session %s of user %s.", s->id, s->user->name),
                    NULL);
 
-        /* Create X11 symlink */
-        session_link_x11_socket(s);
-
         if (!dual_timestamp_is_set(&s->timestamp))
                 dual_timestamp_get(&s->timestamp);
 
@@ -529,89 +569,89 @@ int session_start(Session *s) {
 
         s->started = true;
 
-        /* Save session data */
+        user_elect_display(s->user);
+
+        /* Save data */
         session_save(s);
         user_save(s->user);
+        if (s->seat)
+                seat_save(s->seat);
 
+        /* Send signals */
         session_send_signal(s, true);
-
+        user_send_changed(s->user, "Sessions", "Display", NULL);
         if (s->seat) {
-                seat_save(s->seat);
-
                 if (s->seat->active == s)
-                        seat_send_changed(s->seat, "Sessions\0ActiveSession\0");
+                        seat_send_changed(s->seat, "Sessions", "ActiveSession", NULL);
                 else
-                        seat_send_changed(s->seat, "Sessions\0");
+                        seat_send_changed(s->seat, "Sessions", NULL);
         }
 
-        user_send_changed(s->user, "Sessions\0");
-
         return 0;
 }
 
-static int session_stop_scope(Session *s) {
-        DBusError error;
-        char *job;
+static int session_stop_scope(Session *s, bool force) {
+        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
+        char *job = NULL;
         int r;
 
         assert(s);
 
-        dbus_error_init(&error);
-
         if (!s->scope)
                 return 0;
 
-        r = manager_stop_unit(s->manager, s->scope, &error, &job);
-        if (r < 0) {
-                log_error("Failed to stop session scope: %s", bus_error(&error, r));
-                dbus_error_free(&error);
-                return r;
-        }
+        if (force || manager_shall_kill(s->manager, s->user->name)) {
+                r = manager_stop_unit(s->manager, s->scope, &error, &job);
+                if (r < 0) {
+                        log_error("Failed to stop session scope: %s", bus_error_message(&error, r));
+                        return r;
+                }
 
-        free(s->scope_job);
-        s->scope_job = job;
+                free(s->scope_job);
+                s->scope_job = job;
+        } else {
+                r = manager_abandon_scope(s->manager, s->scope, &error);
+                if (r < 0) {
+                        log_error("Failed to abandon session scope: %s", bus_error_message(&error, r));
+                        return r;
+                }
+        }
 
         return 0;
 }
 
-static int session_unlink_x11_socket(Session *s) {
-        _cleanup_free_ char *t = NULL;
+int session_stop(Session *s, bool force) {
         int r;
 
         assert(s);
-        assert(s->user);
 
-        if (s->user->display != s)
-                return 0;
-
-        s->user->display = NULL;
+        if (!s->user)
+                return -ESTALE;
 
-        t = strappend(s->user->runtime_path, "/X11-display");
-        if (!t)
-                return log_oom();
+        s->timer_event_source = sd_event_source_unref(s->timer_event_source);
 
-        r = unlink(t);
-        return r < 0 ? -errno : 0;
-}
+        if (s->seat)
+                seat_evict_position(s->seat, s);
 
-int session_stop(Session *s) {
-        int r;
+        /* We are going down, don't care about FIFOs anymore */
+        session_remove_fifo(s);
 
-        assert(s);
+        /* Kill cgroup */
+        r = session_stop_scope(s, force);
 
-        if (!s->user)
-                return -ESTALE;
+        s->stopping = true;
 
-        /* Kill cgroup */
-        r = session_stop_scope(s);
+        user_elect_display(s->user);
 
         session_save(s);
+        user_save(s->user);
 
         return r;
 }
 
 int session_finalize(Session *s) {
         int r = 0;
+        SessionDevice *sd;
 
         assert(s);
 
@@ -619,16 +659,22 @@ int session_finalize(Session *s) {
                 return -ESTALE;
 
         if (s->started)
-                log_struct(s->type == SESSION_TTY || s->type == SESSION_X11 ? LOG_INFO : LOG_DEBUG,
-                           MESSAGE_ID(SD_MESSAGE_SESSION_STOP),
+                log_struct(s->class == SESSION_BACKGROUND ? LOG_DEBUG : LOG_INFO,
+                           LOG_MESSAGE_ID(SD_MESSAGE_SESSION_STOP),
                            "SESSION_ID=%s", s->id,
                            "USER_ID=%s", s->user->name,
-                           "LEADER=%lu", (unsigned long) s->leader,
-                           "MESSAGE=Removed session %s.", s->id,
+                           "LEADER="PID_FMT, s->leader,
+                           LOG_MESSAGE("Removed session %s.", s->id),
                            NULL);
 
-        /* Remove X11 symlink */
-        session_unlink_x11_socket(s);
+        s->timer_event_source = sd_event_source_unref(s->timer_event_source);
+
+        if (s->seat)
+                seat_evict_position(s->seat, s);
+
+        /* Kill session devices */
+        while ((sd = hashmap_first(s->devices)))
+                session_device_free(sd);
 
         unlink(s->state_file);
         session_add_to_gc_queue(s);
@@ -643,16 +689,42 @@ int session_finalize(Session *s) {
                 if (s->seat->active == s)
                         seat_set_active(s->seat, NULL);
 
-                seat_send_changed(s->seat, "Sessions\0");
                 seat_save(s->seat);
+                seat_send_changed(s->seat, "Sessions", NULL);
         }
 
-        user_send_changed(s->user, "Sessions\0");
         user_save(s->user);
+        user_send_changed(s->user, "Sessions", "Display", NULL);
 
         return r;
 }
 
+static int release_timeout_callback(sd_event_source *es, uint64_t usec, void *userdata) {
+        Session *s = userdata;
+
+        assert(es);
+        assert(s);
+
+        session_stop(s, false);
+        return 0;
+}
+
+int session_release(Session *s) {
+        assert(s);
+
+        if (!s->started || s->stopping)
+                return 0;
+
+        if (s->timer_event_source)
+                return 0;
+
+        return sd_event_add_time(s->manager->event,
+                                 &s->timer_event_source,
+                                 CLOCK_MONOTONIC,
+                                 now(CLOCK_MONOTONIC) + RELEASE_USEC, 0,
+                                 release_timeout_callback, s);
+}
+
 bool session_is_active(Session *s) {
         assert(s);
 
@@ -761,26 +833,27 @@ void session_set_idle_hint(Session *s, bool b) {
         s->idle_hint = b;
         dual_timestamp_get(&s->idle_hint_timestamp);
 
-        session_send_changed(s,
-                             "IdleHint\0"
-                             "IdleSinceHint\0"
-                             "IdleSinceHintMonotonic\0");
+        session_send_changed(s, "IdleHint", "IdleSinceHint", "IdleSinceHintMonotonic", NULL);
 
         if (s->seat)
-                seat_send_changed(s->seat,
-                                  "IdleHint\0"
-                                  "IdleSinceHint\0"
-                                  "IdleSinceHintMonotonic\0");
+                seat_send_changed(s->seat, "IdleHint", "IdleSinceHint", "IdleSinceHintMonotonic", NULL);
 
-        user_send_changed(s->user,
-                          "IdleHint\0"
-                          "IdleSinceHint\0"
-                          "IdleSinceHintMonotonic\0");
+        user_send_changed(s->user, "IdleHint", "IdleSinceHint", "IdleSinceHintMonotonic", NULL);
+        manager_send_changed(s->manager, "IdleHint", "IdleSinceHint", "IdleSinceHintMonotonic", NULL);
+}
 
-        manager_send_changed(s->manager,
-                             "IdleHint\0"
-                             "IdleSinceHint\0"
-                             "IdleSinceHintMonotonic\0");
+static int session_dispatch_fifo(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
+        Session *s = userdata;
+
+        assert(s);
+        assert(s->fifo_fd == fd);
+
+        /* EOF on the FIFO means the session died abnormally. */
+
+        session_remove_fifo(s);
+        session_stop(s, false);
+
+        return 1;
 }
 
 int session_create_fifo(Session *s) {
@@ -803,21 +876,20 @@ int session_create_fifo(Session *s) {
 
         /* Open reading side */
         if (s->fifo_fd < 0) {
-                struct epoll_event ev = {};
-
                 s->fifo_fd = open(s->fifo_path, O_RDONLY|O_CLOEXEC|O_NDELAY);
                 if (s->fifo_fd < 0)
                         return -errno;
 
-                r = hashmap_put(s->manager->session_fds, INT_TO_PTR(s->fifo_fd + 1), s);
+        }
+
+        if (!s->fifo_event_source) {
+                r = sd_event_add_io(s->manager->event, &s->fifo_event_source, s->fifo_fd, 0, session_dispatch_fifo, s);
                 if (r < 0)
                         return r;
 
-                ev.events = 0;
-                ev.data.u32 = FD_OTHER_BASE + s->fifo_fd;
-
-                if (epoll_ctl(s->manager->epoll_fd, EPOLL_CTL_ADD, s->fifo_fd, &ev) < 0)
-                        return -errno;
+                r = sd_event_source_set_priority(s->fifo_event_source, SD_EVENT_PRIORITY_IDLE);
+                if (r < 0)
+                        return r;
         }
 
         /* Open writing side */
@@ -828,18 +900,11 @@ int session_create_fifo(Session *s) {
         return r;
 }
 
-void session_remove_fifo(Session *s) {
+static void session_remove_fifo(Session *s) {
         assert(s);
 
-        if (s->fifo_fd >= 0) {
-                assert_se(hashmap_remove(s->manager->session_fds, INT_TO_PTR(s->fifo_fd + 1)) == s);
-                assert_se(epoll_ctl(s->manager->epoll_fd, EPOLL_CTL_DEL, s->fifo_fd, NULL) == 0);
-                close_nointr_nofail(s->fifo_fd);
-                s->fifo_fd = -1;
-
-                session_save(s);
-                user_save(s->user);
-        }
+        s->fifo_event_source = sd_event_source_unref(s->fifo_event_source);
+        s->fifo_fd = safe_close(s->fifo_fd);
 
         if (s->fifo_path) {
                 unlink(s->fifo_path);
@@ -848,33 +913,27 @@ void session_remove_fifo(Session *s) {
         }
 }
 
-int session_check_gc(Session *s, bool drop_not_started) {
-        int r;
-
+bool session_check_gc(Session *s, bool drop_not_started) {
         assert(s);
 
         if (drop_not_started && !s->started)
-                return 0;
+                return false;
 
         if (!s->user)
-                return 0;
+                return false;
 
         if (s->fifo_fd >= 0) {
-                r = pipe_eof(s->fifo_fd);
-                if (r < 0)
-                        return r;
-
-                if (r == 0)
-                        return 1;
+                if (pipe_eof(s->fifo_fd) <= 0)
+                        return true;
         }
 
-        if (s->scope_job)
-                return 1;
+        if (s->scope_job && manager_job_is_active(s->manager, s->scope_job))
+                return true;
 
-        if (s->scope)
-                return manager_unit_is_active(s->manager, s->scope) != 0;
+        if (s->scope && manager_unit_is_active(s->manager, s->scope))
+                return true;
 
-        return 0;
+        return false;
 }
 
 void session_add_to_gc_queue(Session *s) {
@@ -883,22 +942,20 @@ void session_add_to_gc_queue(Session *s) {
         if (s->in_gc_queue)
                 return;
 
-        LIST_PREPEND(Session, gc_queue, s->manager->session_gc_queue, s);
+        LIST_PREPEND(gc_queue, s->manager->session_gc_queue, s);
         s->in_gc_queue = true;
 }
 
 SessionState session_get_state(Session *s) {
         assert(s);
 
-        if (s->closing)
+        /* always check closing first */
+        if (s->stopping || s->timer_event_source)
                 return SESSION_CLOSING;
 
-        if (s->scope_job)
+        if (s->scope_job || s->fifo_fd < 0)
                 return SESSION_OPENING;
 
-        if (s->fifo_fd < 0)
-                return SESSION_CLOSING;
-
         if (session_is_active(s))
                 return SESSION_ACTIVE;
 
@@ -914,15 +971,165 @@ int session_kill(Session *s, KillWho who, int signo) {
         return manager_kill_unit(s->manager, s->scope, who, signo, NULL);
 }
 
-bool session_is_controller(Session *s, const char *sender)
-{
+static int session_open_vt(Session *s) {
+        char path[sizeof("/dev/tty") + DECIMAL_STR_MAX(s->vtnr)];
+
+        if (s->vtnr < 1)
+                return -ENODEV;
+
+        if (s->vtfd >= 0)
+                return s->vtfd;
+
+        sprintf(path, "/dev/tty%u", s->vtnr);
+        s->vtfd = open_terminal(path, O_RDWR | O_CLOEXEC | O_NONBLOCK | O_NOCTTY);
+        if (s->vtfd < 0)
+                return log_error_errno(errno, "cannot open VT %s of session %s: %m", path, s->id);
+
+        return s->vtfd;
+}
+
+int session_prepare_vt(Session *s) {
+        int vt, r;
+        struct vt_mode mode = { 0 };
+
+        if (s->vtnr < 1)
+                return 0;
+
+        vt = session_open_vt(s);
+        if (vt < 0)
+                return vt;
+
+        r = fchown(vt, s->user->uid, -1);
+        if (r < 0) {
+                r = -errno;
+                log_error_errno(errno, "Cannot change owner of /dev/tty%u: %m", s->vtnr);
+                goto error;
+        }
+
+        r = ioctl(vt, KDSKBMODE, K_OFF);
+        if (r < 0) {
+                r = -errno;
+                log_error_errno(errno, "Cannot set K_OFF on /dev/tty%u: %m", s->vtnr);
+                goto error;
+        }
+
+        r = ioctl(vt, KDSETMODE, KD_GRAPHICS);
+        if (r < 0) {
+                r = -errno;
+                log_error_errno(errno, "Cannot set KD_GRAPHICS on /dev/tty%u: %m", s->vtnr);
+                goto error;
+        }
+
+        /* Oh, thanks to the VT layer, VT_AUTO does not work with KD_GRAPHICS.
+         * So we need a dummy handler here which just acknowledges *all* VT
+         * switch requests. */
+        mode.mode = VT_PROCESS;
+        mode.relsig = SIGRTMIN;
+        mode.acqsig = SIGRTMIN + 1;
+        r = ioctl(vt, VT_SETMODE, &mode);
+        if (r < 0) {
+                r = -errno;
+                log_error_errno(errno, "Cannot set VT_PROCESS on /dev/tty%u: %m", s->vtnr);
+                goto error;
+        }
+
+        return 0;
+
+error:
+        session_restore_vt(s);
+        return r;
+}
+
+void session_restore_vt(Session *s) {
+        _cleanup_free_ char *utf8 = NULL;
+        int vt, kb = K_XLATE;
+        struct vt_mode mode = { 0 };
+
+        /* We need to get a fresh handle to the virtual terminal,
+         * since the old file-descriptor is potentially in a hung-up
+         * state after the controlling process exited; we do a
+         * little dance to avoid having the terminal be available
+         * for reuse before we've cleaned it up.
+         */
+        int old_fd = s->vtfd;
+        s->vtfd = -1;
+
+        vt = session_open_vt(s);
+        safe_close(old_fd);
+
+        if (vt < 0)
+                return;
+
+        (void) ioctl(vt, KDSETMODE, KD_TEXT);
+
+        if (read_one_line_file("/sys/module/vt/parameters/default_utf8", &utf8) >= 0 && *utf8 == '1')
+                kb = K_UNICODE;
+
+        (void) ioctl(vt, KDSKBMODE, kb);
+
+        mode.mode = VT_AUTO;
+        (void) ioctl(vt, VT_SETMODE, &mode);
+
+        fchown(vt, 0, -1);
+
+        s->vtfd = safe_close(s->vtfd);
+}
+
+void session_leave_vt(Session *s) {
+        int r;
+
+        assert(s);
+
+        /* This is called whenever we get a VT-switch signal from the kernel.
+         * We acknowledge all of them unconditionally. Note that session are
+         * free to overwrite those handlers and we only register them for
+         * sessions with controllers. Legacy sessions are not affected.
+         * However, if we switch from a non-legacy to a legacy session, we must
+         * make sure to pause all device before acknowledging the switch. We
+         * process the real switch only after we are notified via sysfs, so the
+         * legacy session might have already started using the devices. If we
+         * don't pause the devices before the switch, we might confuse the
+         * session we switch to. */
+
+        if (s->vtfd < 0)
+                return;
+
+        session_device_pause_all(s);
+        r = ioctl(s->vtfd, VT_RELDISP, 1);
+        if (r < 0)
+                log_debug_errno(errno, "Cannot release VT of session %s: %m", s->id);
+}
+
+bool session_is_controller(Session *s, const char *sender) {
         assert(s);
 
         return streq_ptr(s->controller, sender);
 }
 
+static void session_release_controller(Session *s, bool notify) {
+        _cleanup_free_ char *name = NULL;
+        SessionDevice *sd;
+
+        if (!s->controller)
+                return;
+
+        name = s->controller;
+
+        /* By resetting the controller before releasing the devices, we won't
+         * send notification signals. This avoids sending useless notifications
+         * if the controller is released on disconnects. */
+        if (!notify)
+                s->controller = NULL;
+
+        while ((sd = hashmap_first(s->devices)))
+                session_device_free(sd);
+
+        s->controller = NULL;
+        manager_drop_busname(s->manager, name);
+}
+
 int session_set_controller(Session *s, const char *sender, bool force) {
-        char *t;
+        _cleanup_free_ char *name = NULL;
         int r;
 
         assert(s);
@@ -933,19 +1140,33 @@ int session_set_controller(Session *s, const char *sender, bool force) {
         if (s->controller && !force)
                 return -EBUSY;
 
-        t = strdup(sender);
-        if (!t)
+        name = strdup(sender);
+        if (!name)
                 return -ENOMEM;
 
-        r = manager_watch_busname(s->manager, sender);
-        if (r) {
-                free(t);
+        r = manager_watch_busname(s->manager, name);
+        if (r)
+                return r;
+
+        /* When setting a session controller, we forcibly mute the VT and set
+         * it into graphics-mode. Applications can override that by changing
+         * VT state after calling TakeControl(). However, this serves as a good
+         * default and well-behaving controllers can now ignore VTs entirely.
+         * Note that we reset the VT on ReleaseControl() and if the controller
+         * exits.
+         * If logind crashes/restarts, we restore the controller during restart
+         * or reset the VT in case it crashed/exited, too. */
+        r = session_prepare_vt(s);
+        if (r < 0) {
+                manager_drop_busname(s->manager, name);
                 return r;
         }
 
-        session_drop_controller(s);
+        session_release_controller(s, true);
+        s->controller = name;
+        name = NULL;
+        session_save(s);
 
-        s->controller = t;
         return 0;
 }
 
@@ -955,9 +1176,9 @@ void session_drop_controller(Session *s) {
         if (!s->controller)
                 return;
 
-        manager_drop_busname(s->manager, s->controller);
-        free(s->controller);
-        s->controller = NULL;
+        session_release_controller(s, false);
+        session_save(s);
+        session_restore_vt(s);
 }
 
 static const char* const session_state_table[_SESSION_STATE_MAX] = {
@@ -970,9 +1191,12 @@ static const char* const session_state_table[_SESSION_STATE_MAX] = {
 DEFINE_STRING_TABLE_LOOKUP(session_state, SessionState);
 
 static const char* const session_type_table[_SESSION_TYPE_MAX] = {
+        [SESSION_UNSPECIFIED] = "unspecified",
         [SESSION_TTY] = "tty",
         [SESSION_X11] = "x11",
-        [SESSION_UNSPECIFIED] = "unspecified"
+        [SESSION_WAYLAND] = "wayland",
+        [SESSION_MIR] = "mir",
+        [SESSION_WEB] = "web",
 };
 
 DEFINE_STRING_TABLE_LOOKUP(session_type, SessionType);