Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 940 insertions, 0 deletions

diff --git a/src/login/logind-user.c b/src/login/logind-user.c
new file mode 100644
index 0000000..c613307
--- /dev/null
+++ b/src/login/logind-user.c
@@ -0,0 +1,940 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "bus-common-errors.h"
+#include "bus-error.h"
+#include "bus-locator.h"
+#include "bus-util.h"
+#include "cgroup-util.h"
+#include "clean-ipc.h"
+#include "env-file.h"
+#include "escape.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "format-util.h"
+#include "fs-util.h"
+#include "hashmap.h"
+#include "label-util.h"
+#include "limits-util.h"
+#include "logind-dbus.h"
+#include "logind-user-dbus.h"
+#include "logind-user.h"
+#include "mkdir-label.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "percent-util.h"
+#include "rm-rf.h"
+#include "serialize.h"
+#include "special.h"
+#include "stdio-util.h"
+#include "string-table.h"
+#include "strv.h"
+#include "tmpfile-util.h"
+#include "uid-alloc-range.h"
+#include "unit-name.h"
+#include "user-util.h"
+
+int user_new(User **ret,
+             Manager *m,
+             UserRecord *ur) {
+
+        _cleanup_(user_freep) User *u = NULL;
+        char lu[DECIMAL_STR_MAX(uid_t) + 1];
+        int r;
+
+        assert(ret);
+        assert(m);
+        assert(ur);
+
+        if (!ur->user_name)
+                return -EINVAL;
+
+        if (!uid_is_valid(ur->uid))
+                return -EINVAL;
+
+        u = new(User, 1);
+        if (!u)
+                return -ENOMEM;
+
+        *u = (User) {
+                .manager = m,
+                .user_record = user_record_ref(ur),
+                .last_session_timestamp = USEC_INFINITY,
+        };
+
+        if (asprintf(&u->state_file, "/run/systemd/users/" UID_FMT, ur->uid) < 0)
+                return -ENOMEM;
+
+        if (asprintf(&u->runtime_path, "/run/user/" UID_FMT, ur->uid) < 0)
+                return -ENOMEM;
+
+        xsprintf(lu, UID_FMT, ur->uid);
+        r = slice_build_subslice(SPECIAL_USER_SLICE, lu, &u->slice);
+        if (r < 0)
+                return r;
+
+        r = unit_name_build("user", lu, ".service", &u->service);
+        if (r < 0)
+                return r;
+
+        r = unit_name_build("user-runtime-dir", lu, ".service", &u->runtime_dir_service);
+        if (r < 0)
+                return r;
+
+        r = hashmap_put(m->users, UID_TO_PTR(ur->uid), u);
+        if (r < 0)
+                return r;
+
+        r = hashmap_put(m->user_units, u->slice, u);
+        if (r < 0)
+                return r;
+
+        r = hashmap_put(m->user_units, u->service, u);
+        if (r < 0)
+                return r;
+
+        r = hashmap_put(m->user_units, u->runtime_dir_service, u);
+        if (r < 0)
+                return r;
+
+        *ret = TAKE_PTR(u);
+        return 0;
+}
+
+User *user_free(User *u) {
+        if (!u)
+                return NULL;
+
+        if (u->in_gc_queue)
+                LIST_REMOVE(gc_queue, u->manager->user_gc_queue, u);
+
+        while (u->sessions)
+                session_free(u->sessions);
+
+        if (u->service)
+                hashmap_remove_value(u->manager->user_units, u->service, u);
+
+        if (u->runtime_dir_service)
+                hashmap_remove_value(u->manager->user_units, u->runtime_dir_service, u);
+
+        if (u->slice)
+                hashmap_remove_value(u->manager->user_units, u->slice, u);
+
+        hashmap_remove_value(u->manager->users, UID_TO_PTR(u->user_record->uid), u);
+
+        sd_event_source_unref(u->timer_event_source);
+
+        u->service_job = mfree(u->service_job);
+
+        u->service = mfree(u->service);
+        u->runtime_dir_service = mfree(u->runtime_dir_service);
+        u->slice = mfree(u->slice);
+        u->runtime_path = mfree(u->runtime_path);
+        u->state_file = mfree(u->state_file);
+
+        user_record_unref(u->user_record);
+
+        return mfree(u);
+}
+
+static int user_save_internal(User *u) {
+        _cleanup_(unlink_and_freep) char *temp_path = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
+        int r;
+
+        assert(u);
+        assert(u->state_file);
+
+        r = mkdir_safe_label("/run/systemd/users", 0755, 0, 0, MKDIR_WARN_MODE);
+        if (r < 0)
+                goto fail;
+
+        r = fopen_temporary(u->state_file, &f, &temp_path);
+        if (r < 0)
+                goto fail;
+
+        (void) fchmod(fileno(f), 0644);
+
+        fprintf(f,
+                "# This is private data. Do not parse.\n"
+                "NAME=%s\n"
+                "STATE=%s\n"         /* friendly user-facing state */
+                "STOPPING=%s\n",     /* low-level state */
+                u->user_record->user_name,
+                user_state_to_string(user_get_state(u)),
+                yes_no(u->stopping));
+
+        /* LEGACY: no-one reads RUNTIME= anymore, drop it at some point */
+        if (u->runtime_path)
+                fprintf(f, "RUNTIME=%s\n", u->runtime_path);
+
+        if (u->service_job)
+                fprintf(f, "SERVICE_JOB=%s\n", u->service_job);
+
+        if (u->display)
+                fprintf(f, "DISPLAY=%s\n", u->display->id);
+
+        if (dual_timestamp_is_set(&u->timestamp))
+                fprintf(f,
+                        "REALTIME="USEC_FMT"\n"
+                        "MONOTONIC="USEC_FMT"\n",
+                        u->timestamp.realtime,
+                        u->timestamp.monotonic);
+
+        if (u->last_session_timestamp != USEC_INFINITY)
+                fprintf(f, "LAST_SESSION_TIMESTAMP=" USEC_FMT "\n",
+                        u->last_session_timestamp);
+
+        if (u->sessions) {
+                bool first;
+
+                fputs("SESSIONS=", f);
+                first = true;
+                LIST_FOREACH(sessions_by_user, i, u->sessions) {
+                        if (first)
+                                first = false;
+                        else
+                                fputc(' ', f);
+
+                        fputs(i->id, f);
+                }
+
+                fputs("\nSEATS=", f);
+                first = true;
+                LIST_FOREACH(sessions_by_user, i, u->sessions) {
+                        if (!i->seat)
+                                continue;
+
+                        if (first)
+                                first = false;
+                        else
+                                fputc(' ', f);
+
+                        fputs(i->seat->id, f);
+                }
+
+                fputs("\nACTIVE_SESSIONS=", f);
+                first = true;
+                LIST_FOREACH(sessions_by_user, i, u->sessions) {
+                        if (!session_is_active(i))
+                                continue;
+
+                        if (first)
+                                first = false;
+                        else
+                                fputc(' ', f);
+
+                        fputs(i->id, f);
+                }
+
+                fputs("\nONLINE_SESSIONS=", f);
+                first = true;
+                LIST_FOREACH(sessions_by_user, i, u->sessions) {
+                        if (session_get_state(i) == SESSION_CLOSING)
+                                continue;
+
+                        if (first)
+                                first = false;
+                        else
+                                fputc(' ', f);
+
+                        fputs(i->id, f);
+                }
+
+                fputs("\nACTIVE_SEATS=", f);
+                first = true;
+                LIST_FOREACH(sessions_by_user, i, u->sessions) {
+                        if (!session_is_active(i) || !i->seat)
+                                continue;
+
+                        if (first)
+                                first = false;
+                        else
+                                fputc(' ', f);
+
+                        fputs(i->seat->id, f);
+                }
+
+                fputs("\nONLINE_SEATS=", f);
+                first = true;
+                LIST_FOREACH(sessions_by_user, i, u->sessions) {
+                        if (session_get_state(i) == SESSION_CLOSING || !i->seat)
+                                continue;
+
+                        if (first)
+                                first = false;
+                        else
+                                fputc(' ', f);
+
+                        fputs(i->seat->id, f);
+                }
+                fputc('\n', f);
+        }
+
+        r = fflush_and_check(f);
+        if (r < 0)
+                goto fail;
+
+        if (rename(temp_path, u->state_file) < 0) {
+                r = -errno;
+                goto fail;
+        }
+
+        temp_path = mfree(temp_path);
+        return 0;
+
+fail:
+        (void) unlink(u->state_file);
+
+        return log_error_errno(r, "Failed to save user data %s: %m", u->state_file);
+}
+
+int user_save(User *u) {
+        assert(u);
+
+        if (!u->started)
+                return 0;
+
+        return user_save_internal(u);
+}
+
+int user_load(User *u) {
+        _cleanup_free_ char *realtime = NULL, *monotonic = NULL, *stopping = NULL, *last_session_timestamp = NULL;
+        int r;
+
+        assert(u);
+
+        r = parse_env_file(NULL, u->state_file,
+                           "SERVICE_JOB",            &u->service_job,
+                           "STOPPING",               &stopping,
+                           "REALTIME",               &realtime,
+                           "MONOTONIC",              &monotonic,
+                           "LAST_SESSION_TIMESTAMP", &last_session_timestamp);
+        if (r == -ENOENT)
+                return 0;
+        if (r < 0)
+                return log_error_errno(r, "Failed to read %s: %m", u->state_file);
+
+        if (stopping) {
+                r = parse_boolean(stopping);
+                if (r < 0)
+                        log_debug_errno(r, "Failed to parse 'STOPPING' boolean: %s", stopping);
+                else
+                        u->stopping = r;
+        }
+
+        if (realtime)
+                (void) deserialize_usec(realtime, &u->timestamp.realtime);
+        if (monotonic)
+                (void) deserialize_usec(monotonic, &u->timestamp.monotonic);
+        if (last_session_timestamp)
+                (void) deserialize_usec(last_session_timestamp, &u->last_session_timestamp);
+
+        return 0;
+}
+
+static void user_start_service(User *u) {
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        int r;
+
+        assert(u);
+
+        /* Start the service containing the "systemd --user" instance (user@.service). Note that we don't explicitly
+         * start the per-user slice or the systemd-runtime-dir@.service instance, as those are pulled in both by
+         * user@.service and the session scopes as dependencies. */
+
+        u->service_job = mfree(u->service_job);
+
+        r = manager_start_unit(u->manager, u->service, &error, &u->service_job);
+        if (r < 0)
+                log_full_errno(sd_bus_error_has_name(&error, BUS_ERROR_UNIT_MASKED) ? LOG_DEBUG : LOG_WARNING, r,
+                               "Failed to start user service '%s', ignoring: %s", u->service, bus_error_message(&error, r));
+}
+
+static int update_slice_callback(sd_bus_message *m, void *userdata, sd_bus_error *ret_error) {
+        _cleanup_(user_record_unrefp) UserRecord *ur = ASSERT_PTR(userdata);
+        const sd_bus_error *e;
+        int r;
+
+        assert(m);
+
+        e = sd_bus_message_get_error(m);
+        if (e) {
+                r = sd_bus_error_get_errno(e);
+                log_warning_errno(r,
+                                  "Failed to update slice of %s, ignoring: %s",
+                                  ur->user_name,
+                                  bus_error_message(e, r));
+
+                return 0;
+        }
+
+        log_debug("Successfully set slice parameters of %s.", ur->user_name);
+        return 0;
+}
+
+static int user_update_slice(User *u) {
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
+        int r;
+
+        assert(u);
+
+        if (u->user_record->tasks_max == UINT64_MAX &&
+            u->user_record->memory_high == UINT64_MAX &&
+            u->user_record->memory_max == UINT64_MAX &&
+            u->user_record->cpu_weight == UINT64_MAX &&
+            u->user_record->io_weight == UINT64_MAX)
+                return 0;
+
+        r = bus_message_new_method_call(u->manager->bus, &m, bus_systemd_mgr, "SetUnitProperties");
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = sd_bus_message_append(m, "sb", u->slice, true);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = sd_bus_message_open_container(m, 'a', "(sv)");
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        const struct {
+                const char *name;
+                uint64_t value;
+        } settings[] = {
+                { "TasksMax",   u->user_record->tasks_max   },
+                { "MemoryMax",  u->user_record->memory_max  },
+                { "MemoryHigh", u->user_record->memory_high },
+                { "CPUWeight",  u->user_record->cpu_weight  },
+                { "IOWeight",   u->user_record->io_weight   },
+        };
+
+        for (size_t i = 0; i < ELEMENTSOF(settings); i++)
+                if (settings[i].value != UINT64_MAX) {
+                        r = sd_bus_message_append(m, "(sv)", settings[i].name, "t", settings[i].value);
+                        if (r < 0)
+                                return bus_log_create_error(r);
+                }
+
+        r = sd_bus_message_close_container(m);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = sd_bus_call_async(u->manager->bus, NULL, m, update_slice_callback, u->user_record, 0);
+        if (r < 0)
+                return log_error_errno(r, "Failed to change user slice properties: %m");
+
+        /* Ref the user record pointer, so that the slot keeps it pinned */
+        user_record_ref(u->user_record);
+
+        return 0;
+}
+
+int user_start(User *u) {
+        assert(u);
+
+        if (u->started && !u->stopping)
+                return 0;
+
+        /* If u->stopping is set, the user is marked for removal and service stop-jobs are queued. We have to clear
+         * that flag before queueing the start-jobs again. If they succeed, the user object can be re-used just fine
+         * (pid1 takes care of job-ordering and proper restart), but if they fail, we want to force another user_stop()
+         * so possibly pending units are stopped. */
+        u->stopping = false;
+
+        if (!u->started)
+                log_debug("Starting services for new user %s.", u->user_record->user_name);
+
+        /* Save the user data so far, because pam_systemd will read the XDG_RUNTIME_DIR out of it while starting up
+         * systemd --user.  We need to do user_save_internal() because we have not "officially" started yet. */
+        user_save_internal(u);
+
+        /* Set slice parameters */
+        (void) user_update_slice(u);
+
+        /* Start user@UID.service */
+        user_start_service(u);
+
+        if (!u->started) {
+                if (!dual_timestamp_is_set(&u->timestamp))
+                        dual_timestamp_now(&u->timestamp);
+                user_send_signal(u, true);
+                u->started = true;
+        }
+
+        /* Save new user data */
+        user_save(u);
+
+        return 0;
+}
+
+static void user_stop_service(User *u, bool force) {
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        int r;
+
+        assert(u);
+        assert(u->service);
+
+        /* The reverse of user_start_service(). Note that we only stop user@UID.service here, and let StopWhenUnneeded=
+         * deal with the slice and the user-runtime-dir@.service instance. */
+
+        u->service_job = mfree(u->service_job);
+
+        r = manager_stop_unit(u->manager, u->service, force ? "replace" : "fail", &error, &u->service_job);
+        if (r < 0)
+                log_warning_errno(r, "Failed to stop user service '%s', ignoring: %s", u->service, bus_error_message(&error, r));
+}
+
+int user_stop(User *u, bool force) {
+        int r = 0;
+
+        assert(u);
+
+        /* This is called whenever we begin with tearing down a user record. It's called in two cases: explicit API
+         * request to do so via the bus (in which case 'force' is true) and automatically due to GC, if there's no
+         * session left pinning it (in which case 'force' is false). Note that this just initiates tearing down of the
+         * user, the User object will remain in memory until user_finalize() is called, see below. */
+
+        if (!u->started)
+                return 0;
+
+        if (u->stopping) { /* Stop jobs have already been queued */
+                user_save(u);
+                return 0;
+        }
+
+        LIST_FOREACH(sessions_by_user, s, u->sessions) {
+                int k;
+
+                k = session_stop(s, force);
+                if (k < 0)
+                        r = k;
+        }
+
+        user_stop_service(u, force);
+
+        u->stopping = true;
+
+        user_save(u);
+
+        return r;
+}
+
+int user_finalize(User *u) {
+        int r = 0, k;
+
+        assert(u);
+
+        /* Called when the user is really ready to be freed, i.e. when all unit stop jobs and suchlike for it are
+         * done. This is called as a result of an earlier user_done() when all jobs are completed. */
+
+        if (u->started)
+                log_debug("User %s logged out.", u->user_record->user_name);
+
+        LIST_FOREACH(sessions_by_user, s, u->sessions) {
+                k = session_finalize(s);
+                if (k < 0)
+                        r = k;
+        }
+
+        /* Clean SysV + POSIX IPC objects, but only if this is not a system user. Background: in many setups cronjobs
+         * are run in full PAM and thus logind sessions, even if the code run doesn't belong to actual users but to
+         * system components. Since enable RemoveIPC= globally for all users, we need to be a bit careful with such
+         * cases, as we shouldn't accidentally remove a system service's IPC objects while it is running, just because
+         * a cronjob running as the same user just finished. Hence: exclude system users generally from IPC clean-up,
+         * and do it only for normal users. */
+        if (u->manager->remove_ipc && !uid_is_system(u->user_record->uid)) {
+                k = clean_ipc_by_uid(u->user_record->uid);
+                if (k < 0)
+                        r = k;
+        }
+
+        (void) unlink(u->state_file);
+        user_add_to_gc_queue(u);
+
+        if (u->started) {
+                user_send_signal(u, false);
+                u->started = false;
+        }
+
+        return r;
+}
+
+int user_get_idle_hint(User *u, dual_timestamp *t) {
+        bool idle_hint = true;
+        dual_timestamp ts = DUAL_TIMESTAMP_NULL;
+
+        assert(u);
+
+        LIST_FOREACH(sessions_by_user, s, u->sessions) {
+                dual_timestamp k;
+                int ih;
+
+                ih = session_get_idle_hint(s, &k);
+                if (ih < 0)
+                        return ih;
+
+                if (!ih) {
+                        if (!idle_hint) {
+                                if (k.monotonic < ts.monotonic)
+                                        ts = k;
+                        } else {
+                                idle_hint = false;
+                                ts = k;
+                        }
+                } else if (idle_hint) {
+
+                        if (k.monotonic > ts.monotonic)
+                                ts = k;
+                }
+        }
+
+        if (t)
+                *t = ts;
+
+        return idle_hint;
+}
+
+int user_check_linger_file(User *u) {
+        _cleanup_free_ char *cc = NULL;
+        char *p = NULL;
+
+        cc = cescape(u->user_record->user_name);
+        if (!cc)
+                return -ENOMEM;
+
+        p = strjoina("/var/lib/systemd/linger/", cc);
+        if (access(p, F_OK) < 0) {
+                if (errno != ENOENT)
+                        return -errno;
+
+                return false;
+        }
+
+        return true;
+}
+
+static bool user_unit_active(User *u) {
+        int r;
+
+        assert(u->service);
+        assert(u->runtime_dir_service);
+        assert(u->slice);
+
+        FOREACH_STRING(i, u->service, u->runtime_dir_service, u->slice) {
+                _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+
+                r = manager_unit_is_active(u->manager, i, &error);
+                if (r < 0)
+                        log_debug_errno(r, "Failed to determine whether unit '%s' is active, ignoring: %s", i, bus_error_message(&error, r));
+                if (r != 0)
+                        return true;
+        }
+
+        return false;
+}
+
+static usec_t user_get_stop_delay(User *u) {
+        assert(u);
+
+        if (u->user_record->stop_delay_usec != UINT64_MAX)
+                return u->user_record->stop_delay_usec;
+
+        if (user_record_removable(u->user_record) > 0)
+                return 0; /* For removable users lower the stop delay to zero */
+
+        return u->manager->user_stop_delay;
+}
+
+bool user_may_gc(User *u, bool drop_not_started) {
+        int r;
+
+        assert(u);
+
+        if (drop_not_started && !u->started)
+                return true;
+
+        if (u->sessions)
+                return false;
+
+        if (u->last_session_timestamp != USEC_INFINITY) {
+                usec_t user_stop_delay;
+
+                /* All sessions have been closed. Let's see if we shall leave the user record around for a bit */
+
+                user_stop_delay = user_get_stop_delay(u);
+
+                if (user_stop_delay == USEC_INFINITY)
+                        return false; /* Leave it around forever! */
+                if (user_stop_delay > 0 &&
+                    now(CLOCK_MONOTONIC) < usec_add(u->last_session_timestamp, user_stop_delay))
+                        return false; /* Leave it around for a bit longer. */
+        }
+
+        /* Is this a user that shall stay around forever ("linger")? Before we say "no" to GC'ing for lingering users, let's check
+         * if any of the three units that we maintain for this user is still around. If none of them is,
+         * there's no need to keep this user around even if lingering is enabled. */
+        if (user_check_linger_file(u) > 0 && user_unit_active(u))
+                return false;
+
+        /* Check if our job is still pending */
+        if (u->service_job) {
+                _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+
+                r = manager_job_is_active(u->manager, u->service_job, &error);
+                if (r < 0)
+                        log_debug_errno(r, "Failed to determine whether job '%s' is pending, ignoring: %s", u->service_job, bus_error_message(&error, r));
+                if (r != 0)
+                        return false;
+        }
+
+        /* Note that we don't care if the three units we manage for each user object are up or not, as we are managing
+         * their state rather than tracking it. */
+
+        return true;
+}
+
+void user_add_to_gc_queue(User *u) {
+        assert(u);
+
+        if (u->in_gc_queue)
+                return;
+
+        LIST_PREPEND(gc_queue, u->manager->user_gc_queue, u);
+        u->in_gc_queue = true;
+}
+
+UserState user_get_state(User *u) {
+        assert(u);
+
+        if (u->stopping)
+                return USER_CLOSING;
+
+        if (!u->started || u->service_job)
+                return USER_OPENING;
+
+        if (u->sessions) {
+                bool all_closing = true;
+
+                LIST_FOREACH(sessions_by_user, i, u->sessions) {
+                        SessionState state;
+
+                        state = session_get_state(i);
+                        if (state == SESSION_ACTIVE)
+                                return USER_ACTIVE;
+                        if (state != SESSION_CLOSING)
+                                all_closing = false;
+                }
+
+                return all_closing ? USER_CLOSING : USER_ONLINE;
+        }
+
+        if (user_check_linger_file(u) > 0 && user_unit_active(u))
+                return USER_LINGERING;
+
+        return USER_CLOSING;
+}
+
+int user_kill(User *u, int signo) {
+        assert(u);
+
+        return manager_kill_unit(u->manager, u->slice, KILL_ALL, signo, NULL);
+}
+
+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 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. */
+        static const int type_ranks[_SESSION_TYPE_MAX] = {
+                [SESSION_UNSPECIFIED] = 0,
+                [SESSION_TTY] = -2,
+                [SESSION_X11] = -3,
+                [SESSION_WAYLAND] = -3,
+                [SESSION_MIR] = -3,
+                [SESSION_WEB] = -1,
+        };
+
+        /* Calculate the partial order relationship between s1 and s2,
+         * returning < 0 if s1 is preferred as the user’s ‘primary session’,
+         * 0 if s1 and s2 are equally preferred or incomparable, or > 0 if s2
+         * is preferred.
+         *
+         * s1 or s2 may be NULL. */
+        if (!s1 && !s2)
+                return 0;
+
+        if ((s1 == NULL) != (s2 == NULL))
+                return (s1 == NULL) - (s2 == NULL);
+
+        if (s1->stopping != s2->stopping)
+                return s1->stopping - s2->stopping;
+
+        if ((s1->class != SESSION_USER) != (s2->class != SESSION_USER))
+                return (s1->class != SESSION_USER) - (s2->class != SESSION_USER);
+
+        if ((s1->type == _SESSION_TYPE_INVALID) != (s2->type == _SESSION_TYPE_INVALID))
+                return (s1->type == _SESSION_TYPE_INVALID) - (s2->type == _SESSION_TYPE_INVALID);
+
+        if (s1->type != s2->type)
+                return type_ranks[s1->type] - type_ranks[s2->type];
+
+        return 0;
+}
+
+void user_elect_display(User *u) {
+        assert(u);
+
+        /* This elects a primary session for each user, which we call the "display". We try to keep the assignment
+         * stable, but we "upgrade" to better choices. */
+        log_debug("Electing new display for user %s", u->user_record->user_name);
+
+        LIST_FOREACH(sessions_by_user, s, u->sessions) {
+                if (!elect_display_filter(s)) {
+                        log_debug("Ignoring session %s", s->id);
+                        continue;
+                }
+
+                if (elect_display_compare(s, u->display) < 0) {
+                        log_debug("Choosing session %s in preference to %s", s->id, u->display ? u->display->id : "-");
+                        u->display = s;
+                }
+        }
+}
+
+static int user_stop_timeout_callback(sd_event_source *es, uint64_t usec, void *userdata) {
+        User *u = ASSERT_PTR(userdata);
+
+        user_add_to_gc_queue(u);
+
+        return 0;
+}
+
+void user_update_last_session_timer(User *u) {
+        usec_t user_stop_delay;
+        int r;
+
+        assert(u);
+
+        if (u->sessions) {
+                /* There are sessions, turn off the timer */
+                u->last_session_timestamp = USEC_INFINITY;
+                u->timer_event_source = sd_event_source_unref(u->timer_event_source);
+                return;
+        }
+
+        if (u->last_session_timestamp != USEC_INFINITY)
+                return; /* Timer already started */
+
+        u->last_session_timestamp = now(CLOCK_MONOTONIC);
+
+        assert(!u->timer_event_source);
+
+        user_stop_delay = user_get_stop_delay(u);
+        if (!timestamp_is_set(user_stop_delay))
+                return;
+
+        if (sd_event_get_state(u->manager->event) == SD_EVENT_FINISHED) {
+                log_debug("Not allocating user stop timeout, since we are already exiting.");
+                return;
+        }
+
+        r = sd_event_add_time(u->manager->event,
+                              &u->timer_event_source,
+                              CLOCK_MONOTONIC,
+                              usec_add(u->last_session_timestamp, user_stop_delay), 0,
+                              user_stop_timeout_callback, u);
+        if (r < 0)
+                log_warning_errno(r, "Failed to enqueue user stop event source, ignoring: %m");
+
+        if (DEBUG_LOGGING)
+                log_debug("Last session of user '%s' logged out, terminating user context in %s.",
+                          u->user_record->user_name,
+                          FORMAT_TIMESPAN(user_stop_delay, USEC_PER_MSEC));
+}
+
+static const char* const user_state_table[_USER_STATE_MAX] = {
+        [USER_OFFLINE]   = "offline",
+        [USER_OPENING]   = "opening",
+        [USER_LINGERING] = "lingering",
+        [USER_ONLINE]    = "online",
+        [USER_ACTIVE]    = "active",
+        [USER_CLOSING]   = "closing"
+};
+
+DEFINE_STRING_TABLE_LOOKUP(user_state, UserState);
+
+int config_parse_tmpfs_size(
+                const char* unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        uint64_t *sz = ASSERT_PTR(data);
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+
+        /* First, try to parse as percentage */
+        r = parse_permyriad(rvalue);
+        if (r > 0)
+                *sz = physical_memory_scale(r, 10000U);
+        else {
+                uint64_t k;
+
+                /* If the passed argument was not a percentage, or out of range, parse as byte size */
+
+                r = parse_size(rvalue, 1024, &k);
+                if (r >= 0 && (k <= 0 || (uint64_t) (size_t) k != k))
+                        r = -ERANGE;
+                if (r < 0) {
+                        log_syntax(unit, LOG_WARNING, filename, line, r, "Failed to parse size value '%s', ignoring: %m", rvalue);
+                        return 0;
+                }
+
+                *sz = PAGE_ALIGN((size_t) k);
+        }
+
+        return 0;
+}
+
+int config_parse_compat_user_tasks_max(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+
+        log_syntax(unit, LOG_NOTICE, filename, line, 0,
+                   "Support for option %s= has been removed.",
+                   lvalue);
+        log_info("Hint: try creating /etc/systemd/system/user-.slice.d/50-limits.conf with:\n"
+                 "        [Slice]\n"
+                 "        TasksMax=%s",
+                 rvalue);
+        return 0;
+}