src/login/logind-session.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2011 Lennart Poettering
   6
   7   systemd is free software; you can redistribute it and/or modify it
   8   under the terms of the GNU Lesser General Public License as published by
   9   the Free Software Foundation; either version 2.1 of the License, or
  10   (at your option) any later version.
  11
  12   systemd is distributed in the hope that it will be useful, but
  13   WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15   Lesser General Public License for more details.
  16
  17   You should have received a copy of the GNU Lesser General Public License
  18   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  19 ***/
  20
  21 #include <errno.h>
  22 #include <fcntl.h>
  23 #include <linux/kd.h>
  24 #include <linux/vt.h>
  25 #include <signal.h>
  26 #include <string.h>
  27 #include <sys/ioctl.h>
  28 #include <unistd.h>
  29
  30 #include "sd-messages.h"
  31
  32 #include "alloc-util.h"
  33 #include "audit-util.h"
  34 #include "bus-error.h"
  35 #include "bus-util.h"
  36 #include "escape.h"
  37 #include "fd-util.h"
  38 #include "fileio.h"
  39 #include "format-util.h"
  40 #include "io-util.h"
  41 #include "logind-session.h"
  42 #include "mkdir.h"
  43 #include "parse-util.h"
  44 #include "path-util.h"
  45 #include "string-table.h"
  46 #include "terminal-util.h"
  47 #include "user-util.h"
  48 #include "util.h"
  49
  50 /// Additional includes needed by elogind
  51 #include "extract-word.h"
  52 #include "process-util.h"
  53
  54 #define RELEASE_USEC (20*USEC_PER_SEC)
  55
  56 static void session_remove_fifo(Session *s);
  57
  58 Session* session_new(Manager *m, const char *id) {
  59         Session *s;
  60
  61         assert(m);
  62         assert(id);
  63         assert(session_id_valid(id));
  64
  65         s = new0(Session, 1);
  66         if (!s)
  67                 return NULL;
  68
  69         s->state_file = strappend("/run/systemd/sessions/", id);
  70         if (!s->state_file)
  71                 return mfree(s);
  72
  73         s->devices = hashmap_new(&devt_hash_ops);
  74         if (!s->devices) {
  75                 free(s->state_file);
  76                 return mfree(s);
  77         }
  78
  79         s->id = basename(s->state_file);
  80
  81         if (hashmap_put(m->sessions, s->id, s) < 0) {
  82                 hashmap_free(s->devices);
  83                 free(s->state_file);
  84                 return mfree(s);
  85         }
  86
  87         s->manager = m;
  88         s->fifo_fd = -1;
  89         s->vtfd = -1;
  90         s->audit_id = AUDIT_SESSION_INVALID;
  91
  92         return s;
  93 }
  94
  95 void session_free(Session *s) {
  96         SessionDevice *sd;
  97
  98         assert(s);
  99
 100         if (s->in_gc_queue)
 101                 LIST_REMOVE(gc_queue, s->manager->session_gc_queue, s);
 102
 103         s->timer_event_source = sd_event_source_unref(s->timer_event_source);
 104
 105         session_remove_fifo(s);
 106
 107         session_drop_controller(s);
 108
 109         while ((sd = hashmap_first(s->devices)))
 110                 session_device_free(sd);
 111
 112         hashmap_free(s->devices);
 113
 114         if (s->user) {
 115                 LIST_REMOVE(sessions_by_user, s->user->sessions, s);
 116
 117                 if (s->user->display == s)
 118                         s->user->display = NULL;
 119         }
 120
 121         if (s->seat) {
 122                 if (s->seat->active == s)
 123                         s->seat->active = NULL;
 124                 if (s->seat->pending_switch == s)
 125                         s->seat->pending_switch = NULL;
 126
 127                 seat_evict_position(s->seat, s);
 128                 LIST_REMOVE(sessions_by_seat, s->seat->sessions, s);
 129         }
 130
 131         if (s->scope) {
 132                 hashmap_remove(s->manager->session_units, s->scope);
 133                 free(s->scope);
 134         }
 135
 136 #if 0 /// elogind does not support systemd scope_jobs
 137         free(s->scope_job);
 138 #endif // 0
 139
 140         sd_bus_message_unref(s->create_message);
 141
 142         free(s->tty);
 143         free(s->display);
 144         free(s->remote_host);
 145         free(s->remote_user);
 146         free(s->service);
 147         free(s->desktop);
 148
 149         hashmap_remove(s->manager->sessions, s->id);
 150
 151         free(s->state_file);
 152         free(s);
 153 }
 154
 155 void session_set_user(Session *s, User *u) {
 156         assert(s);
 157         assert(!s->user);
 158
 159         s->user = u;
 160         LIST_PREPEND(sessions_by_user, u->sessions, s);
 161 }
 162
 163 static void session_save_devices(Session *s, FILE *f) {
 164         SessionDevice *sd;
 165         Iterator i;
 166
 167         if (!hashmap_isempty(s->devices)) {
 168                 fprintf(f, "DEVICES=");
 169                 HASHMAP_FOREACH(sd, s->devices, i)
 170                         fprintf(f, "%u:%u ", major(sd->dev), minor(sd->dev));
 171                 fprintf(f, "\n");
 172         }
 173 }
 174
 175 int session_save(Session *s) {
 176         _cleanup_free_ char *temp_path = NULL;
 177         _cleanup_fclose_ FILE *f = NULL;
 178         int r = 0;
 179
 180         assert(s);
 181
 182         if (!s->user)
 183                 return -ESTALE;
 184
 185         if (!s->started)
 186                 return 0;
 187
 188         r = mkdir_safe_label("/run/systemd/sessions", 0755, 0, 0, false);
 189         if (r < 0)
 190                 goto fail;
 191
 192         r = fopen_temporary(s->state_file, &f, &temp_path);
 193         if (r < 0)
 194                 goto fail;
 195
 196         assert(s->user);
 197
 198         fchmod(fileno(f), 0644);
 199
 200         fprintf(f,
 201                 "# This is private data. Do not parse.\n"
 202                 "UID="UID_FMT"\n"
 203                 "USER=%s\n"
 204                 "ACTIVE=%i\n"
 205                 "STATE=%s\n"
 206                 "REMOTE=%i\n",
 207                 s->user->uid,
 208                 s->user->name,
 209                 session_is_active(s),
 210                 session_state_to_string(session_get_state(s)),
 211                 s->remote);
 212
 213         if (s->type >= 0)
 214                 fprintf(f, "TYPE=%s\n", session_type_to_string(s->type));
 215
 216         if (s->class >= 0)
 217                 fprintf(f, "CLASS=%s\n", session_class_to_string(s->class));
 218
 219         if (s->scope)
 220                 fprintf(f, "SCOPE=%s\n", s->scope);
 221 #if 0 /// elogind does not support systemd scope_jobs
 222         if (s->scope_job)
 223                 fprintf(f, "SCOPE_JOB=%s\n", s->scope_job);
 224 #endif // 0
 225
 226         if (s->fifo_path)
 227                 fprintf(f, "FIFO=%s\n", s->fifo_path);
 228
 229         if (s->seat)
 230                 fprintf(f, "SEAT=%s\n", s->seat->id);
 231
 232         if (s->tty)
 233                 fprintf(f, "TTY=%s\n", s->tty);
 234
 235         if (s->display)
 236                 fprintf(f, "DISPLAY=%s\n", s->display);
 237
 238         if (s->remote_host) {
 239                 _cleanup_free_ char *escaped;
 240
 241                 escaped = cescape(s->remote_host);
 242                 if (!escaped) {
 243                         r = -ENOMEM;
 244                         goto fail;
 245                 }
 246
 247                 fprintf(f, "REMOTE_HOST=%s\n", escaped);
 248         }
 249
 250         if (s->remote_user) {
 251                 _cleanup_free_ char *escaped;
 252
 253                 escaped = cescape(s->remote_user);
 254                 if (!escaped) {
 255                         r = -ENOMEM;
 256                         goto fail;
 257                 }
 258
 259                 fprintf(f, "REMOTE_USER=%s\n", escaped);
 260         }
 261
 262         if (s->service) {
 263                 _cleanup_free_ char *escaped;
 264
 265                 escaped = cescape(s->service);
 266                 if (!escaped) {
 267                         r = -ENOMEM;
 268                         goto fail;
 269                 }
 270
 271                 fprintf(f, "SERVICE=%s\n", escaped);
 272         }
 273
 274         if (s->desktop) {
 275                 _cleanup_free_ char *escaped;
 276
 277
 278                 escaped = cescape(s->desktop);
 279                 if (!escaped) {
 280                         r = -ENOMEM;
 281                         goto fail;
 282                 }
 283
 284                 fprintf(f, "DESKTOP=%s\n", escaped);
 285         }
 286
 287         if (s->seat && seat_has_vts(s->seat))
 288                 fprintf(f, "VTNR=%u\n", s->vtnr);
 289
 290         if (!s->vtnr)
 291                 fprintf(f, "POSITION=%u\n", s->position);
 292
 293         if (pid_is_valid(s->leader))
 294                 fprintf(f, "LEADER="PID_FMT"\n", s->leader);
 295
 296         if (audit_session_is_valid(s->audit_id))
 297                 fprintf(f, "AUDIT=%"PRIu32"\n", s->audit_id);
 298
 299         if (dual_timestamp_is_set(&s->timestamp))
 300                 fprintf(f,
 301                         "REALTIME="USEC_FMT"\n"
 302                         "MONOTONIC="USEC_FMT"\n",
 303                         s->timestamp.realtime,
 304                         s->timestamp.monotonic);
 305
 306         if (s->controller) {
 307                 fprintf(f, "CONTROLLER=%s\n", s->controller);
 308                 session_save_devices(s, f);
 309         }
 310
 311         r = fflush_and_check(f);
 312         if (r < 0)
 313                 goto fail;
 314
 315         if (rename(temp_path, s->state_file) < 0) {
 316                 r = -errno;
 317                 goto fail;
 318         }
 319
 320         return 0;
 321
 322 fail:
 323         (void) unlink(s->state_file);
 324
 325         if (temp_path)
 326                 (void) unlink(temp_path);
 327
 328         return log_error_errno(r, "Failed to save session data %s: %m", s->state_file);
 329 }
 330
 331 static int session_load_devices(Session *s, const char *devices) {
 332         const char *p;
 333         int r = 0;
 334
 335         assert(s);
 336
 337         for (p = devices;;) {
 338                 _cleanup_free_ char *word = NULL;
 339                 SessionDevice *sd;
 340                 dev_t dev;
 341                 int k;
 342
 343                 k = extract_first_word(&p, &word, NULL, 0);
 344                 if (k == 0)
 345                         break;
 346                 if (k < 0) {
 347                         r = k;
 348                         break;
 349                 }
 350
 351                 k = parse_dev(word, &dev);
 352                 if (k < 0) {
 353                         r = k;
 354                         continue;
 355                 }
 356
 357                 /* The file descriptors for loaded devices will be reattached later. */
 358                 k = session_device_new(s, dev, false, &sd);
 359                 if (k < 0)
 360                         r = k;
 361         }
 362
 363         if (r < 0)
 364                 log_error_errno(r, "Loading session devices for session %s failed: %m", s->id);
 365
 366         return r;
 367 }
 368
 369 int session_load(Session *s) {
 370         _cleanup_free_ char *remote = NULL,
 371                 *seat = NULL,
 372                 *vtnr = NULL,
 373                 *state = NULL,
 374                 *position = NULL,
 375                 *leader = NULL,
 376                 *type = NULL,
 377                 *class = NULL,
 378                 *uid = NULL,
 379                 *realtime = NULL,
 380                 *monotonic = NULL,
 381                 *controller = NULL,
 382                 *active = NULL,
 383                 *devices = NULL;
 384
 385         int k, r;
 386
 387         assert(s);
 388
 389         r = parse_env_file(s->state_file, NEWLINE,
 390                            "REMOTE",         &remote,
 391                            "SCOPE",          &s->scope,
 392 #if 0 /// elogind does not support systemd scope_jobs
 393                            "SCOPE_JOB",      &s->scope_job,
 394 #endif // 0
 395                            "FIFO",           &s->fifo_path,
 396                            "SEAT",           &seat,
 397                            "TTY",            &s->tty,
 398                            "DISPLAY",        &s->display,
 399                            "REMOTE_HOST",    &s->remote_host,
 400                            "REMOTE_USER",    &s->remote_user,
 401                            "SERVICE",        &s->service,
 402                            "DESKTOP",        &s->desktop,
 403                            "VTNR",           &vtnr,
 404                            "STATE",          &state,
 405                            "POSITION",       &position,
 406                            "LEADER",         &leader,
 407                            "TYPE",           &type,
 408                            "CLASS",          &class,
 409                            "UID",            &uid,
 410                            "REALTIME",       &realtime,
 411                            "MONOTONIC",      &monotonic,
 412                            "CONTROLLER",     &controller,
 413                            "ACTIVE",         &active,
 414                            "DEVICES",        &devices,
 415                            NULL);
 416
 417         if (r < 0)
 418                 return log_error_errno(r, "Failed to read %s: %m", s->state_file);
 419
 420         if (!s->user) {
 421                 uid_t u;
 422                 User *user;
 423
 424                 if (!uid) {
 425                         log_error("UID not specified for session %s", s->id);
 426                         return -ENOENT;
 427                 }
 428
 429                 r = parse_uid(uid, &u);
 430                 if (r < 0)  {
 431                         log_error("Failed to parse UID value %s for session %s.", uid, s->id);
 432                         return r;
 433                 }
 434
 435                 user = hashmap_get(s->manager->users, UID_TO_PTR(u));
 436                 if (!user) {
 437                         log_error("User of session %s not known.", s->id);
 438                         return -ENOENT;
 439                 }
 440
 441                 session_set_user(s, user);
 442         }
 443
 444         if (remote) {
 445                 k = parse_boolean(remote);
 446                 if (k >= 0)
 447                         s->remote = k;
 448         }
 449
 450         if (vtnr)
 451                 safe_atou(vtnr, &s->vtnr);
 452
 453         if (seat && !s->seat) {
 454                 Seat *o;
 455
 456                 o = hashmap_get(s->manager->seats, seat);
 457                 if (o)
 458                         r = seat_attach_session(o, s);
 459                 if (!o || r < 0)
 460                         log_error("Cannot attach session %s to seat %s", s->id, seat);
 461         }
 462
 463         if (!s->seat || !seat_has_vts(s->seat))
 464                 s->vtnr = 0;
 465
 466         if (position && s->seat) {
 467                 unsigned int npos;
 468
 469                 safe_atou(position, &npos);
 470                 seat_claim_position(s->seat, s, npos);
 471         }
 472
 473         if (leader) {
 474                 if (parse_pid(leader, &s->leader) >= 0)
 475                         (void) audit_session_from_pid(s->leader, &s->audit_id);
 476         }
 477
 478         if (type) {
 479                 SessionType t;
 480
 481                 t = session_type_from_string(type);
 482                 if (t >= 0)
 483                         s->type = t;
 484         }
 485
 486         if (class) {
 487                 SessionClass c;
 488
 489                 c = session_class_from_string(class);
 490                 if (c >= 0)
 491                         s->class = c;
 492         }
 493
 494         if (state && streq(state, "closing"))
 495                 s->stopping = true;
 496
 497         if (s->fifo_path) {
 498                 int fd;
 499
 500                 /* If we open an unopened pipe for reading we will not
 501                    get an EOF. to trigger an EOF we hence open it for
 502                    writing, but close it right away which then will
 503                    trigger the EOF. This will happen immediately if no
 504                    other process has the FIFO open for writing, i. e.
 505                    when the session died before logind (re)started. */
 506
 507                 fd = session_create_fifo(s);
 508                 safe_close(fd);
 509         }
 510
 511         if (realtime)
 512                 timestamp_deserialize(realtime, &s->timestamp.realtime);
 513         if (monotonic)
 514                 timestamp_deserialize(monotonic, &s->timestamp.monotonic);
 515
 516         if (active) {
 517                 k = parse_boolean(active);
 518                 if (k >= 0)
 519                         s->was_active = k;
 520         }
 521
 522         if (controller) {
 523                 if (bus_name_has_owner(s->manager->bus, controller, NULL) > 0) {
 524                         session_set_controller(s, controller, false, false);
 525                         session_load_devices(s, devices);
 526                 } else
 527                         session_restore_vt(s);
 528         }
 529
 530         return r;
 531 }
 532
 533 int session_activate(Session *s) {
 534         unsigned int num_pending;
 535
 536         assert(s);
 537         assert(s->user);
 538
 539         if (!s->seat)
 540                 return -EOPNOTSUPP;
 541
 542         if (s->seat->active == s)
 543                 return 0;
 544
 545         /* on seats with VTs, we let VTs manage session-switching */
 546         if (seat_has_vts(s->seat)) {
 547                 if (!s->vtnr)
 548                         return -EOPNOTSUPP;
 549
 550                 return chvt(s->vtnr);
 551         }
 552
 553         /* On seats without VTs, we implement session-switching in logind. We
 554          * try to pause all session-devices and wait until the session
 555          * controller acknowledged them. Once all devices are asleep, we simply
 556          * switch the active session and be done.
 557          * We save the session we want to switch to in seat->pending_switch and
 558          * seat_complete_switch() will perform the final switch. */
 559
 560         s->seat->pending_switch = s;
 561
 562         /* if no devices are running, immediately perform the session switch */
 563         num_pending = session_device_try_pause_all(s);
 564         if (!num_pending)
 565                 seat_complete_switch(s->seat);
 566
 567         return 0;
 568 }
 569
 570 #if 0 /// UNNEEDED by elogind
 571 static int session_start_scope(Session *s) {
 572         int r;
 573
 574         assert(s);
 575         assert(s->user);
 576
 577         if (!s->scope) {
 578                 _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 579                 char *scope, *job = NULL;
 580                 const char *description;
 581
 582                 scope = strjoin("session-", s->id, ".scope");
 583                 if (!scope)
 584                         return log_oom();
 585
 586                 description = strjoina("Session ", s->id, " of user ", s->user->name);
 587
 588                 r = manager_start_scope(
 589                                 s->manager,
 590                                 scope,
 591                                 s->leader,
 592                                 s->user->slice,
 593                                 description,
 594                                 "systemd-logind.service",
 595                                 "systemd-user-sessions.service",
 596                                 (uint64_t) -1, /* disable TasksMax= for the scope, rely on the slice setting for it */
 597                                 &error,
 598                                 &job);
 599                 if (r < 0) {
 600                         log_error_errno(r, "Failed to start session scope %s: %s", scope, bus_error_message(&error, r));
 601                         free(scope);
 602                         return r;
 603                 } else {
 604                         s->scope = scope;
 605
 606                         free(s->scope_job);
 607                         s->scope_job = job;
 608                 }
 609         }
 610
 611         if (s->scope)
 612                 (void) hashmap_put(s->manager->session_units, s->scope, s);
 613
 614         return 0;
 615 }
 616 #else
 617 static int session_start_cgroup(Session *s) {
 618         int r;
 619
 620         assert(s);
 621         assert(s->user);
 622         assert(s->leader > 0);
 623
 624         /* First, create our own group */
 625         r = cg_create(SYSTEMD_CGROUP_CONTROLLER, s->id);
 626         if (r < 0)
 627                 return log_error_errno(r, "Failed to create cgroup %s: %m", s->id);
 628
 629         r = cg_attach(SYSTEMD_CGROUP_CONTROLLER, s->id, s->leader);
 630         if (r < 0)
 631                 log_warning_errno(r, "Failed to attach PID %d to cgroup %s: %m", s->leader, s->id);
 632
 633         return 0;
 634 }
 635 #endif // 0
 636
 637 int session_start(Session *s) {
 638         int r;
 639
 640         assert(s);
 641
 642         if (!s->user)
 643                 return -ESTALE;
 644
 645         if (s->started)
 646                 return 0;
 647
 648         r = user_start(s->user);
 649         if (r < 0)
 650                 return r;
 651
 652         /* Create cgroup */
 653 #if 0 /// elogind does its own session management
 654         r = session_start_scope(s);
 655 #else
 656         r = session_start_cgroup(s);
 657 #endif // 0
 658         if (r < 0)
 659                 return r;
 660
 661         log_struct(s->class == SESSION_BACKGROUND ? LOG_DEBUG : LOG_INFO,
 662                    "MESSAGE_ID=" SD_MESSAGE_SESSION_START_STR,
 663                    "SESSION_ID=%s", s->id,
 664                    "USER_ID=%s", s->user->name,
 665                    "LEADER="PID_FMT, s->leader,
 666                    LOG_MESSAGE("New session %s of user %s.", s->id, s->user->name),
 667                    NULL);
 668
 669         if (!dual_timestamp_is_set(&s->timestamp))
 670                 dual_timestamp_get(&s->timestamp);
 671
 672         if (s->seat)
 673                 seat_read_active_vt(s->seat);
 674
 675         s->started = true;
 676
 677         user_elect_display(s->user);
 678
 679         /* Save data */
 680         session_save(s);
 681         user_save(s->user);
 682         if (s->seat)
 683                 seat_save(s->seat);
 684
 685         /* Send signals */
 686         session_send_signal(s, true);
 687         user_send_changed(s->user, "Display", NULL);
 688         if (s->seat) {
 689                 if (s->seat->active == s)
 690                         seat_send_changed(s->seat, "ActiveSession", NULL);
 691         }
 692
 693         return 0;
 694 }
 695
 696 #if 0 /// UNNEEDED by elogind
 697 static int session_stop_scope(Session *s, bool force) {
 698         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 699         int r;
 700
 701         assert(s);
 702
 703         if (!s->scope)
 704                 return 0;
 705
 706         /* Let's always abandon the scope first. This tells systemd that we are not interested anymore, and everything
 707          * that is left in the scope is "left-over". Informing systemd about this has the benefit that it will log
 708          * when killing any processes left after this point. */
 709         r = manager_abandon_scope(s->manager, s->scope, &error);
 710         if (r < 0)
 711                 log_warning_errno(r, "Failed to abandon session scope, ignoring: %s", bus_error_message(&error, r));
 712
 713         /* Optionally, let's kill everything that's left now. */
 714         if (force || manager_shall_kill(s->manager, s->user->name)) {
 715                 char *job = NULL;
 716
 717                 r = manager_stop_unit(s->manager, s->scope, &error, &job);
 718                 if (r < 0)
 719                         return log_error_errno(r, "Failed to stop session scope: %s", bus_error_message(&error, r));
 720
 721                 free(s->scope_job);
 722                 s->scope_job = job;
 723         } else
 724                 s->scope_job = mfree(s->scope_job);
 725
 726         return 0;
 727 }
 728 #else
 729 static int session_stop_cgroup(Session *s, bool force) {
 730         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 731         int r;
 732
 733         assert(s);
 734
 735
 736 int session_stop(Session *s, bool force) {
 737         int r;
 738
 739         assert(s);
 740
 741         if (!s->user)
 742                 return -ESTALE;
 743
 744         s->timer_event_source = sd_event_source_unref(s->timer_event_source);
 745
 746         if (s->seat)
 747                 seat_evict_position(s->seat, s);
 748
 749         /* We are going down, don't care about FIFOs anymore */
 750         session_remove_fifo(s);
 751
 752         /* Kill cgroup */
 753         r = session_stop_scope(s, force);
 754
 755         s->stopping = true;
 756
 757         user_elect_display(s->user);
 758
 759         session_save(s);
 760         user_save(s->user);
 761
 762         return r;
 763 }
 764
 765 int session_finalize(Session *s) {
 766         SessionDevice *sd;
 767
 768         assert(s);
 769
 770         if (!s->user)
 771                 return -ESTALE;
 772
 773         if (s->started)
 774                 log_struct(s->class == SESSION_BACKGROUND ? LOG_DEBUG : LOG_INFO,
 775                            "MESSAGE_ID=" SD_MESSAGE_SESSION_STOP_STR,
 776                            "SESSION_ID=%s", s->id,
 777                            "USER_ID=%s", s->user->name,
 778                            "LEADER="PID_FMT, s->leader,
 779                            LOG_MESSAGE("Removed session %s.", s->id),
 780                            NULL);
 781
 782         s->timer_event_source = sd_event_source_unref(s->timer_event_source);
 783
 784         if (s->seat)
 785                 seat_evict_position(s->seat, s);
 786
 787         /* Kill session devices */
 788         while ((sd = hashmap_first(s->devices)))
 789                 session_device_free(sd);
 790
 791         (void) unlink(s->state_file);
 792         session_add_to_gc_queue(s);
 793         user_add_to_gc_queue(s->user);
 794
 795         if (s->started) {
 796                 session_send_signal(s, false);
 797                 s->started = false;
 798         }
 799
 800         if (s->seat) {
 801                 if (s->seat->active == s)
 802                         seat_set_active(s->seat, NULL);
 803
 804                 seat_save(s->seat);
 805         }
 806
 807         user_save(s->user);
 808         user_send_changed(s->user, "Display", NULL);
 809
 810         return 0;
 811 }
 812
 813 static int release_timeout_callback(sd_event_source *es, uint64_t usec, void *userdata) {
 814         Session *s = userdata;
 815
 816         assert(es);
 817         assert(s);
 818
 819         session_stop(s, false);
 820         return 0;
 821 }
 822
 823 int session_release(Session *s) {
 824         assert(s);
 825
 826         if (!s->started || s->stopping)
 827                 return 0;
 828
 829         if (s->timer_event_source)
 830                 return 0;
 831
 832         return sd_event_add_time(s->manager->event,
 833                                  &s->timer_event_source,
 834                                  CLOCK_MONOTONIC,
 835                                  now(CLOCK_MONOTONIC) + RELEASE_USEC, 0,
 836                                  release_timeout_callback, s);
 837 }
 838
 839 bool session_is_active(Session *s) {
 840         assert(s);
 841
 842         if (!s->seat)
 843                 return true;
 844
 845         return s->seat->active == s;
 846 }
 847
 848 static int get_tty_atime(const char *tty, usec_t *atime) {
 849         _cleanup_free_ char *p = NULL;
 850         struct stat st;
 851
 852         assert(tty);
 853         assert(atime);
 854
 855         if (!path_is_absolute(tty)) {
 856                 p = strappend("/dev/", tty);
 857                 if (!p)
 858                         return -ENOMEM;
 859
 860                 tty = p;
 861         } else if (!path_startswith(tty, "/dev/"))
 862                 return -ENOENT;
 863
 864         if (lstat(tty, &st) < 0)
 865                 return -errno;
 866
 867         *atime = timespec_load(&st.st_atim);
 868         return 0;
 869 }
 870
 871 static int get_process_ctty_atime(pid_t pid, usec_t *atime) {
 872         _cleanup_free_ char *p = NULL;
 873         int r;
 874
 875         assert(pid > 0);
 876         assert(atime);
 877
 878         r = get_ctty(pid, NULL, &p);
 879         if (r < 0)
 880                 return r;
 881
 882         return get_tty_atime(p, atime);
 883 }
 884
 885 int session_get_idle_hint(Session *s, dual_timestamp *t) {
 886         usec_t atime = 0, n;
 887         int r;
 888
 889         assert(s);
 890
 891         /* Explicit idle hint is set */
 892         if (s->idle_hint) {
 893                 if (t)
 894                         *t = s->idle_hint_timestamp;
 895
 896                 return s->idle_hint;
 897         }
 898
 899         /* Graphical sessions should really implement a real
 900          * idle hint logic */
 901         if (SESSION_TYPE_IS_GRAPHICAL(s->type))
 902                 goto dont_know;
 903
 904         /* For sessions with an explicitly configured tty, let's check
 905          * its atime */
 906         if (s->tty) {
 907                 r = get_tty_atime(s->tty, &atime);
 908                 if (r >= 0)
 909                         goto found_atime;
 910         }
 911
 912         /* For sessions with a leader but no explicitly configured
 913          * tty, let's check the controlling tty of the leader */
 914         if (s->leader > 0) {
 915                 r = get_process_ctty_atime(s->leader, &atime);
 916                 if (r >= 0)
 917                         goto found_atime;
 918         }
 919
 920 dont_know:
 921         if (t)
 922                 *t = s->idle_hint_timestamp;
 923
 924         return 0;
 925
 926 found_atime:
 927         if (t)
 928                 dual_timestamp_from_realtime(t, atime);
 929
 930         n = now(CLOCK_REALTIME);
 931
 932         if (s->manager->idle_action_usec <= 0)
 933                 return 0;
 934
 935         return atime + s->manager->idle_action_usec <= n;
 936 }
 937
 938 void session_set_idle_hint(Session *s, bool b) {
 939         assert(s);
 940
 941         if (s->idle_hint == b)
 942                 return;
 943
 944         s->idle_hint = b;
 945         dual_timestamp_get(&s->idle_hint_timestamp);
 946
 947         session_send_changed(s, "IdleHint", "IdleSinceHint", "IdleSinceHintMonotonic", NULL);
 948
 949         if (s->seat)
 950                 seat_send_changed(s->seat, "IdleHint", "IdleSinceHint", "IdleSinceHintMonotonic", NULL);
 951
 952         user_send_changed(s->user, "IdleHint", "IdleSinceHint", "IdleSinceHintMonotonic", NULL);
 953         manager_send_changed(s->manager, "IdleHint", "IdleSinceHint", "IdleSinceHintMonotonic", NULL);
 954 }
 955
 956 int session_get_locked_hint(Session *s) {
 957         assert(s);
 958
 959         return s->locked_hint;
 960 }
 961
 962 void session_set_locked_hint(Session *s, bool b) {
 963         assert(s);
 964
 965         if (s->locked_hint == b)
 966                 return;
 967
 968         s->locked_hint = b;
 969
 970         session_send_changed(s, "LockedHint", NULL);
 971 }
 972
 973 static int session_dispatch_fifo(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
 974         Session *s = userdata;
 975
 976         assert(s);
 977         assert(s->fifo_fd == fd);
 978
 979         /* EOF on the FIFO means the session died abnormally. */
 980
 981         session_remove_fifo(s);
 982         session_stop(s, false);
 983
 984         return 1;
 985 }
 986
 987 int session_create_fifo(Session *s) {
 988         int r;
 989
 990         assert(s);
 991
 992         /* Create FIFO */
 993         if (!s->fifo_path) {
 994                 r = mkdir_safe_label("/run/systemd/sessions", 0755, 0, 0, false);
 995                 if (r < 0)
 996                         return r;
 997
 998                 if (asprintf(&s->fifo_path, "/run/systemd/sessions/%s.ref", s->id) < 0)
 999                         return -ENOMEM;
1000
1001                 if (mkfifo(s->fifo_path, 0600) < 0 && errno != EEXIST)
1002                         return -errno;
1003         }
1004
1005         /* Open reading side */
1006         if (s->fifo_fd < 0) {
1007                 s->fifo_fd = open(s->fifo_path, O_RDONLY|O_CLOEXEC|O_NONBLOCK);
1008                 if (s->fifo_fd < 0)
1009                         return -errno;
1010
1011         }
1012
1013         if (!s->fifo_event_source) {
1014                 r = sd_event_add_io(s->manager->event, &s->fifo_event_source, s->fifo_fd, 0, session_dispatch_fifo, s);
1015                 if (r < 0)
1016                         return r;
1017
1018                 /* Let's make sure we noticed dead sessions before we process new bus requests (which might create new
1019                  * sessions). */
1020                 r = sd_event_source_set_priority(s->fifo_event_source, SD_EVENT_PRIORITY_NORMAL-10);
1021                 if (r < 0)
1022                         return r;
1023         }
1024
1025         /* Open writing side */
1026         r = open(s->fifo_path, O_WRONLY|O_CLOEXEC|O_NONBLOCK);
1027         if (r < 0)
1028                 return -errno;
1029
1030         return r;
1031 }
1032
1033 static void session_remove_fifo(Session *s) {
1034         assert(s);
1035
1036         s->fifo_event_source = sd_event_source_unref(s->fifo_event_source);
1037         s->fifo_fd = safe_close(s->fifo_fd);
1038
1039         if (s->fifo_path) {
1040                 unlink(s->fifo_path);
1041                 s->fifo_path = mfree(s->fifo_path);
1042         }
1043 }
1044
1045 bool session_may_gc(Session *s, bool drop_not_started) {
1046         assert(s);
1047
1048         if (drop_not_started && !s->started)
1049                 return true;
1050
1051         if (!s->user)
1052                 return true;
1053
1054         if (s->fifo_fd >= 0) {
1055                 if (pipe_eof(s->fifo_fd) <= 0)
1056                         return false;
1057         }
1058
1059         if (s->scope_job && manager_job_is_active(s->manager, s->scope_job))
1060                 return false;
1061
1062         if (s->scope && manager_unit_is_active(s->manager, s->scope))
1063                 return false;
1064
1065         return true;
1066 }
1067
1068 void session_add_to_gc_queue(Session *s) {
1069         assert(s);
1070
1071         if (s->in_gc_queue)
1072                 return;
1073
1074         LIST_PREPEND(gc_queue, s->manager->session_gc_queue, s);
1075         s->in_gc_queue = true;
1076 }
1077
1078 SessionState session_get_state(Session *s) {
1079         assert(s);
1080
1081         /* always check closing first */
1082         if (s->stopping || s->timer_event_source)
1083                 return SESSION_CLOSING;
1084
1085         if (s->scope_job || s->fifo_fd < 0)
1086                 return SESSION_OPENING;
1087
1088         if (session_is_active(s))
1089                 return SESSION_ACTIVE;
1090
1091         return SESSION_ONLINE;
1092 }
1093
1094 int session_kill(Session *s, KillWho who, int signo) {
1095         assert(s);
1096
1097         if (!s->scope)
1098                 return -ESRCH;
1099
1100         return manager_kill_unit(s->manager, s->scope, who, signo, NULL);
1101 }
1102
1103 static int session_open_vt(Session *s) {
1104         char path[sizeof("/dev/tty") + DECIMAL_STR_MAX(s->vtnr)];
1105
1106         if (s->vtnr < 1)
1107                 return -ENODEV;
1108
1109         if (s->vtfd >= 0)
1110                 return s->vtfd;
1111
1112         sprintf(path, "/dev/tty%u", s->vtnr);
1113         s->vtfd = open_terminal(path, O_RDWR | O_CLOEXEC | O_NONBLOCK | O_NOCTTY);
1114         if (s->vtfd < 0)
1115                 return log_error_errno(s->vtfd, "cannot open VT %s of session %s: %m", path, s->id);
1116
1117         return s->vtfd;
1118 }
1119
1120 int session_prepare_vt(Session *s) {
1121         int vt, r;
1122         struct vt_mode mode = { 0 };
1123
1124         if (s->vtnr < 1)
1125                 return 0;
1126
1127         vt = session_open_vt(s);
1128         if (vt < 0)
1129                 return vt;
1130
1131         r = fchown(vt, s->user->uid, -1);
1132         if (r < 0) {
1133                 r = log_error_errno(errno,
1134                                     "Cannot change owner of /dev/tty%u: %m",
1135                                     s->vtnr);
1136                 goto error;
1137         }
1138
1139         r = ioctl(vt, KDSKBMODE, K_OFF);
1140         if (r < 0) {
1141                 r = log_error_errno(errno,
1142                                     "Cannot set K_OFF on /dev/tty%u: %m",
1143                                     s->vtnr);
1144                 goto error;
1145         }
1146
1147         r = ioctl(vt, KDSETMODE, KD_GRAPHICS);
1148         if (r < 0) {
1149                 r = log_error_errno(errno,
1150                                     "Cannot set KD_GRAPHICS on /dev/tty%u: %m",
1151                                     s->vtnr);
1152                 goto error;
1153         }
1154
1155         /* Oh, thanks to the VT layer, VT_AUTO does not work with KD_GRAPHICS.
1156          * So we need a dummy handler here which just acknowledges *all* VT
1157          * switch requests. */
1158         mode.mode = VT_PROCESS;
1159         mode.relsig = SIGRTMIN;
1160         mode.acqsig = SIGRTMIN + 1;
1161         r = ioctl(vt, VT_SETMODE, &mode);
1162         if (r < 0) {
1163                 r = log_error_errno(errno,
1164                                     "Cannot set VT_PROCESS on /dev/tty%u: %m",
1165                                     s->vtnr);
1166                 goto error;
1167         }
1168
1169         return 0;
1170
1171 error:
1172         session_restore_vt(s);
1173         return r;
1174 }
1175
1176 void session_restore_vt(Session *s) {
1177
1178         static const struct vt_mode mode = {
1179                 .mode = VT_AUTO,
1180         };
1181
1182         int vt, old_fd;
1183
1184         /* We need to get a fresh handle to the virtual terminal,
1185          * since the old file-descriptor is potentially in a hung-up
1186          * state after the controlling process exited; we do a
1187          * little dance to avoid having the terminal be available
1188          * for reuse before we've cleaned it up.
1189          */
1190         old_fd = s->vtfd;
1191         s->vtfd = -1;
1192
1193         vt = session_open_vt(s);
1194         safe_close(old_fd);
1195
1196         if (vt < 0)
1197                 return;
1198
1199         (void) ioctl(vt, KDSETMODE, KD_TEXT);
1200
1201         (void) vt_reset_keyboard(vt);
1202
1203         (void) ioctl(vt, VT_SETMODE, &mode);
1204         (void) fchown(vt, 0, (gid_t) -1);
1205
1206         s->vtfd = safe_close(s->vtfd);
1207 }
1208
1209 void session_leave_vt(Session *s) {
1210         int r;
1211
1212         assert(s);
1213
1214         /* This is called whenever we get a VT-switch signal from the kernel.
1215          * We acknowledge all of them unconditionally. Note that session are
1216          * free to overwrite those handlers and we only register them for
1217          * sessions with controllers. Legacy sessions are not affected.
1218          * However, if we switch from a non-legacy to a legacy session, we must
1219          * make sure to pause all device before acknowledging the switch. We
1220          * process the real switch only after we are notified via sysfs, so the
1221          * legacy session might have already started using the devices. If we
1222          * don't pause the devices before the switch, we might confuse the
1223          * session we switch to. */
1224
1225         if (s->vtfd < 0)
1226                 return;
1227
1228         session_device_pause_all(s);
1229         r = ioctl(s->vtfd, VT_RELDISP, 1);
1230         if (r < 0)
1231                 log_debug_errno(errno, "Cannot release VT of session %s: %m", s->id);
1232 }
1233
1234 bool session_is_controller(Session *s, const char *sender) {
1235         assert(s);
1236
1237         return streq_ptr(s->controller, sender);
1238 }
1239
1240 static void session_release_controller(Session *s, bool notify) {
1241         _cleanup_free_ char *name = NULL;
1242         SessionDevice *sd;
1243
1244         if (!s->controller)
1245                 return;
1246
1247         name = s->controller;
1248
1249         /* By resetting the controller before releasing the devices, we won't
1250          * send notification signals. This avoids sending useless notifications
1251          * if the controller is released on disconnects. */
1252         if (!notify)
1253                 s->controller = NULL;
1254
1255         while ((sd = hashmap_first(s->devices)))
1256                 session_device_free(sd);
1257
1258         s->controller = NULL;
1259         s->track = sd_bus_track_unref(s->track);
1260 }
1261
1262 static int on_bus_track(sd_bus_track *track, void *userdata) {
1263         Session *s = userdata;
1264
1265         assert(track);
1266         assert(s);
1267
1268         session_drop_controller(s);
1269
1270         return 0;
1271 }
1272
1273 int session_set_controller(Session *s, const char *sender, bool force, bool prepare) {
1274         _cleanup_free_ char *name = NULL;
1275         int r;
1276
1277         assert(s);
1278         assert(sender);
1279
1280         if (session_is_controller(s, sender))
1281                 return 0;
1282         if (s->controller && !force)
1283                 return -EBUSY;
1284
1285         name = strdup(sender);
1286         if (!name)
1287                 return -ENOMEM;
1288
1289         s->track = sd_bus_track_unref(s->track);
1290         r = sd_bus_track_new(s->manager->bus, &s->track, on_bus_track, s);
1291         if (r < 0)
1292                 return r;
1293
1294         r = sd_bus_track_add_name(s->track, name);
1295         if (r < 0)
1296                 return r;
1297
1298         /* When setting a session controller, we forcibly mute the VT and set
1299          * it into graphics-mode. Applications can override that by changing
1300          * VT state after calling TakeControl(). However, this serves as a good
1301          * default and well-behaving controllers can now ignore VTs entirely.
1302          * Note that we reset the VT on ReleaseControl() and if the controller
1303          * exits.
1304          * If logind crashes/restarts, we restore the controller during restart
1305          * (without preparing the VT since the controller has probably overridden
1306          * VT state by now) or reset the VT in case it crashed/exited, too. */
1307         if (prepare) {
1308                 r = session_prepare_vt(s);
1309                 if (r < 0) {
1310                         s->track = sd_bus_track_unref(s->track);
1311                         return r;
1312                 }
1313         }
1314
1315         session_release_controller(s, true);
1316         s->controller = name;
1317         name = NULL;
1318         s->controller = TAKE_PTR(name);
1319         session_save(s);
1320
1321         return 0;
1322 }
1323
1324 void session_drop_controller(Session *s) {
1325         assert(s);
1326
1327         if (!s->controller)
1328                 return;
1329
1330         s->track = sd_bus_track_unref(s->track);
1331         session_release_controller(s, false);
1332         session_save(s);
1333         session_restore_vt(s);
1334 }
1335
1336 static const char* const session_state_table[_SESSION_STATE_MAX] = {
1337         [SESSION_OPENING] = "opening",
1338         [SESSION_ONLINE] = "online",
1339         [SESSION_ACTIVE] = "active",
1340         [SESSION_CLOSING] = "closing"
1341 };
1342
1343 DEFINE_STRING_TABLE_LOOKUP(session_state, SessionState);
1344
1345 static const char* const session_type_table[_SESSION_TYPE_MAX] = {
1346         [SESSION_UNSPECIFIED] = "unspecified",
1347         [SESSION_TTY] = "tty",
1348         [SESSION_X11] = "x11",
1349         [SESSION_WAYLAND] = "wayland",
1350         [SESSION_MIR] = "mir",
1351         [SESSION_WEB] = "web",
1352 };
1353
1354 DEFINE_STRING_TABLE_LOOKUP(session_type, SessionType);
1355
1356 static const char* const session_class_table[_SESSION_CLASS_MAX] = {
1357         [SESSION_USER] = "user",
1358         [SESSION_GREETER] = "greeter",
1359         [SESSION_LOCK_SCREEN] = "lock-screen",
1360         [SESSION_BACKGROUND] = "background"
1361 };
1362
1363 DEFINE_STRING_TABLE_LOOKUP(session_class, SessionClass);
1364
1365 static const char* const kill_who_table[_KILL_WHO_MAX] = {
1366         [KILL_LEADER] = "leader",
1367         [KILL_ALL] = "all"
1368 };
1369
1370 DEFINE_STRING_TABLE_LOOKUP(kill_who, KillWho);