src/login/logind-seat.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <sys/stat.h>
   6 #include <unistd.h>
   7
   8 #include "sd-messages.h"
   9
  10 #include "alloc-util.h"
  11 #include "devnode-acl.h"
  12 #include "errno-util.h"
  13 #include "fd-util.h"
  14 #include "fileio.h"
  15 #include "format-util.h"
  16 #include "logind-seat-dbus.h"
  17 #include "logind-seat.h"
  18 #include "logind-session-dbus.h"
  19 #include "mkdir-label.h"
  20 #include "parse-util.h"
  21 #include "path-util.h"
  22 #include "stdio-util.h"
  23 #include "string-util.h"
  24 #include "terminal-util.h"
  25 #include "tmpfile-util.h"
  26
  27 int seat_new(Seat** ret, Manager *m, const char *id) {
  28         _cleanup_(seat_freep) Seat *s = NULL;
  29         int r;
  30
  31         assert(ret);
  32         assert(m);
  33         assert(id);
  34
  35         if (!seat_name_is_valid(id))
  36                 return -EINVAL;
  37
  38         s = new(Seat, 1);
  39         if (!s)
  40                 return -ENOMEM;
  41
  42         *s = (Seat) {
  43                 .manager = m,
  44         };
  45
  46         s->state_file = path_join("/run/systemd/seats", id);
  47         if (!s->state_file)
  48                 return -ENOMEM;
  49
  50         s->id = basename(s->state_file);
  51
  52         r = hashmap_put(m->seats, s->id, s);
  53         if (r < 0)
  54                 return r;
  55
  56         *ret = TAKE_PTR(s);
  57         return 0;
  58 }
  59
  60 Seat* seat_free(Seat *s) {
  61         if (!s)
  62                 return NULL;
  63
  64         if (s->in_gc_queue)
  65                 LIST_REMOVE(gc_queue, s->manager->seat_gc_queue, s);
  66
  67         while (s->sessions)
  68                 session_free(s->sessions);
  69
  70         assert(!s->active);
  71
  72         while (s->devices)
  73                 device_free(s->devices);
  74
  75         hashmap_remove(s->manager->seats, s->id);
  76
  77         free(s->positions);
  78         free(s->state_file);
  79
  80         return mfree(s);
  81 }
  82
  83 int seat_save(Seat *s) {
  84         _cleanup_free_ char *temp_path = NULL;
  85         _cleanup_fclose_ FILE *f = NULL;
  86         int r;
  87
  88         assert(s);
  89
  90         if (!s->started)
  91                 return 0;
  92
  93         r = mkdir_safe_label("/run/systemd/seats", 0755, 0, 0, MKDIR_WARN_MODE);
  94         if (r < 0)
  95                 goto fail;
  96
  97         r = fopen_temporary(s->state_file, &f, &temp_path);
  98         if (r < 0)
  99                 goto fail;
 100
 101         (void) fchmod(fileno(f), 0644);
 102
 103         fprintf(f,
 104                 "# This is private data. Do not parse.\n"
 105                 "IS_SEAT0=%i\n"
 106                 "CAN_MULTI_SESSION=1\n"
 107                 "CAN_TTY=%i\n"
 108                 "CAN_GRAPHICAL=%i\n",
 109                 seat_is_seat0(s),
 110                 seat_can_tty(s),
 111                 seat_can_graphical(s));
 112
 113         if (s->active) {
 114                 assert(s->active->user);
 115
 116                 fprintf(f,
 117                         "ACTIVE=%s\n"
 118                         "ACTIVE_UID="UID_FMT"\n",
 119                         s->active->id,
 120                         s->active->user->user_record->uid);
 121         }
 122
 123         if (s->sessions) {
 124                 fputs("SESSIONS=", f);
 125                 LIST_FOREACH(sessions_by_seat, i, s->sessions) {
 126                         fprintf(f,
 127                                 "%s%c",
 128                                 i->id,
 129                                 i->sessions_by_seat_next ? ' ' : '\n');
 130                 }
 131
 132                 fputs("UIDS=", f);
 133                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 134                         fprintf(f,
 135                                 UID_FMT"%c",
 136                                 i->user->user_record->uid,
 137                                 i->sessions_by_seat_next ? ' ' : '\n');
 138         }
 139
 140         r = fflush_and_check(f);
 141         if (r < 0)
 142                 goto fail;
 143
 144         if (rename(temp_path, s->state_file) < 0) {
 145                 r = -errno;
 146                 goto fail;
 147         }
 148
 149         return 0;
 150
 151 fail:
 152         (void) unlink(s->state_file);
 153
 154         if (temp_path)
 155                 (void) unlink(temp_path);
 156
 157         return log_error_errno(r, "Failed to save seat data %s: %m", s->state_file);
 158 }
 159
 160 int seat_load(Seat *s) {
 161         assert(s);
 162
 163         /* There isn't actually anything to read here ... */
 164
 165         return 0;
 166 }
 167
 168 static int vt_allocate(unsigned vtnr) {
 169         char p[sizeof("/dev/tty") + DECIMAL_STR_MAX(unsigned)];
 170         _cleanup_close_ int fd = -EBADF;
 171
 172         assert(vtnr >= 1);
 173
 174         xsprintf(p, "/dev/tty%u", vtnr);
 175         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 176         if (fd < 0)
 177                 return fd;
 178
 179         return 0;
 180 }
 181
 182 int seat_preallocate_vts(Seat *s) {
 183         int r = 0;
 184         unsigned i;
 185
 186         assert(s);
 187         assert(s->manager);
 188
 189         if (s->manager->n_autovts <= 0)
 190                 return 0;
 191
 192         if (!seat_has_vts(s))
 193                 return 0;
 194
 195         log_debug("Preallocating VTs...");
 196
 197         for (i = 1; i <= s->manager->n_autovts; i++) {
 198                 int q;
 199
 200                 q = vt_allocate(i);
 201                 if (q < 0)
 202                         r = log_error_errno(q, "Failed to preallocate VT %u: %m", i);
 203         }
 204
 205         return r;
 206 }
 207
 208 int seat_apply_acls(Seat *s, Session *old_active) {
 209         int r;
 210
 211         assert(s);
 212
 213         r = devnode_acl_all(s->id,
 214                             false,
 215                             !!old_active, old_active ? old_active->user->user_record->uid : 0,
 216                             !!s->active, s->active ? s->active->user->user_record->uid : 0);
 217
 218         if (r < 0)
 219                 return log_error_errno(r, "Failed to apply ACLs: %m");
 220
 221         return 0;
 222 }
 223
 224 int seat_set_active(Seat *s, Session *session) {
 225         Session *old_active;
 226
 227         assert(s);
 228         assert(!session || session->seat == s);
 229
 230         if (session == s->active)
 231                 return 0;
 232
 233         old_active = s->active;
 234         s->active = session;
 235
 236         if (old_active) {
 237                 session_device_pause_all(old_active);
 238                 session_send_changed(old_active, "Active", NULL);
 239         }
 240
 241         (void) seat_apply_acls(s, old_active);
 242
 243         if (session && session->started) {
 244                 session_send_changed(session, "Active", NULL);
 245                 session_device_resume_all(session);
 246         }
 247
 248         if (!session || session->started)
 249                 seat_send_changed(s, "ActiveSession", NULL);
 250
 251         seat_save(s);
 252
 253         if (session) {
 254                 session_save(session);
 255                 user_save(session->user);
 256         }
 257
 258         if (old_active) {
 259                 session_save(old_active);
 260                 if (!session || session->user != old_active->user)
 261                         user_save(old_active->user);
 262         }
 263
 264         return 0;
 265 }
 266
 267 static Session* seat_get_position(Seat *s, unsigned pos) {
 268         assert(s);
 269
 270         if (pos >= MALLOC_ELEMENTSOF(s->positions))
 271                 return NULL;
 272
 273         return s->positions[pos];
 274 }
 275
 276 int seat_switch_to(Seat *s, unsigned num) {
 277         Session *session;
 278
 279         /* Public session positions skip 0 (there is only F1-F12). Maybe it
 280          * will get reassigned in the future, so return error for now. */
 281         if (num == 0)
 282                 return -EINVAL;
 283
 284         session = seat_get_position(s, num);
 285         if (!session) {
 286                 /* allow switching to unused VTs to trigger auto-activate */
 287                 if (seat_has_vts(s) && num < 64)
 288                         return chvt(num);
 289
 290                 return -EINVAL;
 291         }
 292
 293         return session_activate(session);
 294 }
 295
 296 int seat_switch_to_next(Seat *s) {
 297         unsigned start, i;
 298         Session *session;
 299
 300         if (MALLOC_ELEMENTSOF(s->positions) == 0)
 301                 return -EINVAL;
 302
 303         start = 1;
 304         if (s->active && s->active->position > 0)
 305                 start = s->active->position;
 306
 307         for (i = start + 1; i < MALLOC_ELEMENTSOF(s->positions); ++i) {
 308                 session = seat_get_position(s, i);
 309                 if (session)
 310                         return session_activate(session);
 311         }
 312
 313         for (i = 1; i < start; ++i) {
 314                 session = seat_get_position(s, i);
 315                 if (session)
 316                         return session_activate(session);
 317         }
 318
 319         return -EINVAL;
 320 }
 321
 322 int seat_switch_to_previous(Seat *s) {
 323         if (MALLOC_ELEMENTSOF(s->positions) == 0)
 324                 return -EINVAL;
 325
 326         size_t start = s->active && s->active->position > 0 ? s->active->position : 1;
 327
 328         for (size_t i = start - 1; i > 0; i--) {
 329                 Session *session = seat_get_position(s, i);
 330                 if (session)
 331                         return session_activate(session);
 332         }
 333
 334         for (size_t i = MALLOC_ELEMENTSOF(s->positions) - 1; i > start; i--) {
 335                 Session *session = seat_get_position(s, i);
 336                 if (session)
 337                         return session_activate(session);
 338         }
 339
 340         return -EINVAL;
 341 }
 342
 343 int seat_active_vt_changed(Seat *s, unsigned vtnr) {
 344         Session *new_active = NULL;
 345         int r;
 346
 347         assert(s);
 348         assert(vtnr >= 1);
 349
 350         if (!seat_has_vts(s))
 351                 return -EINVAL;
 352
 353         log_debug("VT changed to %u", vtnr);
 354
 355         /* we might have earlier closing sessions on the same VT, so try to
 356          * find a running one first */
 357         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 358                 if (i->vtnr == vtnr && !i->stopping) {
 359                         new_active = i;
 360                         break;
 361                 }
 362
 363         if (!new_active)
 364                 /* no running one? then we can't decide which one is the
 365                  * active one, let the first one win */
 366                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 367                         if (i->vtnr == vtnr) {
 368                                 new_active = i;
 369                                 break;
 370                         }
 371
 372         r = seat_set_active(s, new_active);
 373         manager_spawn_autovt(s->manager, vtnr);
 374
 375         return r;
 376 }
 377
 378 int seat_read_active_vt(Seat *s) {
 379         char t[64];
 380         ssize_t k;
 381         int vtnr;
 382
 383         assert(s);
 384
 385         if (!seat_has_vts(s))
 386                 return 0;
 387
 388         if (lseek(s->manager->console_active_fd, SEEK_SET, 0) < 0)
 389                 return log_error_errno(errno, "lseek on console_active_fd failed: %m");
 390
 391         errno = 0;
 392         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 393         if (k <= 0)
 394                 return log_error_errno(errno ?: EIO,
 395                                        "Failed to read current console: %s", STRERROR_OR_EOF(errno));
 396
 397         t[k] = 0;
 398         truncate_nl(t);
 399
 400         vtnr = vtnr_from_tty(t);
 401         if (vtnr < 0) {
 402                 log_error_errno(vtnr, "Hm, /sys/class/tty/tty0/active is badly formatted: %m");
 403                 return -EIO;
 404         }
 405
 406         return seat_active_vt_changed(s, vtnr);
 407 }
 408
 409 int seat_start(Seat *s) {
 410         assert(s);
 411
 412         if (s->started)
 413                 return 0;
 414
 415         log_struct(LOG_INFO,
 416                    "MESSAGE_ID=" SD_MESSAGE_SEAT_START_STR,
 417                    "SEAT_ID=%s", s->id,
 418                    LOG_MESSAGE("New seat %s.", s->id));
 419
 420         /* Initialize VT magic stuff */
 421         seat_preallocate_vts(s);
 422
 423         /* Read current VT */
 424         seat_read_active_vt(s);
 425
 426         s->started = true;
 427
 428         /* Save seat data */
 429         seat_save(s);
 430
 431         seat_send_signal(s, true);
 432
 433         return 0;
 434 }
 435
 436 int seat_stop(Seat *s, bool force) {
 437         int r;
 438
 439         assert(s);
 440
 441         if (s->started)
 442                 log_struct(LOG_INFO,
 443                            "MESSAGE_ID=" SD_MESSAGE_SEAT_STOP_STR,
 444                            "SEAT_ID=%s", s->id,
 445                            LOG_MESSAGE("Removed seat %s.", s->id));
 446
 447         r = seat_stop_sessions(s, force);
 448
 449         (void) unlink(s->state_file);
 450         seat_add_to_gc_queue(s);
 451
 452         if (s->started)
 453                 seat_send_signal(s, false);
 454
 455         s->started = false;
 456
 457         return r;
 458 }
 459
 460 int seat_stop_sessions(Seat *s, bool force) {
 461         int r = 0, k;
 462
 463         assert(s);
 464
 465         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 466                 k = session_stop(session, force);
 467                 if (k < 0)
 468                         r = k;
 469         }
 470
 471         return r;
 472 }
 473
 474 void seat_evict_position(Seat *s, Session *session) {
 475         unsigned pos = session->position;
 476
 477         session->position = 0;
 478
 479         if (pos == 0)
 480                 return;
 481
 482         if (pos < MALLOC_ELEMENTSOF(s->positions) && s->positions[pos] == session) {
 483                 s->positions[pos] = NULL;
 484
 485                 /* There might be another session claiming the same
 486                  * position (eg., during gdm->session transition), so let's look
 487                  * for it and set it on the free slot. */
 488                 LIST_FOREACH(sessions_by_seat, iter, s->sessions)
 489                         if (iter->position == pos && session_get_state(iter) != SESSION_CLOSING) {
 490                                 s->positions[pos] = iter;
 491                                 break;
 492                         }
 493         }
 494 }
 495
 496 void seat_claim_position(Seat *s, Session *session, unsigned pos) {
 497         /* with VTs, the position is always the same as the VTnr */
 498         if (seat_has_vts(s))
 499                 pos = session->vtnr;
 500
 501         if (!GREEDY_REALLOC0(s->positions, pos + 1))
 502                 return;
 503
 504         seat_evict_position(s, session);
 505
 506         session->position = pos;
 507         if (pos > 0)
 508                 s->positions[pos] = session;
 509 }
 510
 511 static void seat_assign_position(Seat *s, Session *session) {
 512         unsigned pos;
 513
 514         if (session->position > 0)
 515                 return;
 516
 517         for (pos = 1; pos < MALLOC_ELEMENTSOF(s->positions); ++pos)
 518                 if (!s->positions[pos])
 519                         break;
 520
 521         seat_claim_position(s, session, pos);
 522 }
 523
 524 int seat_attach_session(Seat *s, Session *session) {
 525         assert(s);
 526         assert(session);
 527         assert(!session->seat);
 528
 529         if (!seat_has_vts(s) != !session->vtnr)
 530                 return -EINVAL;
 531
 532         session->seat = s;
 533         LIST_PREPEND(sessions_by_seat, s->sessions, session);
 534         seat_assign_position(s, session);
 535
 536         /* On seats with VTs, the VT logic defines which session is active. On
 537          * seats without VTs, we automatically activate new sessions. */
 538         if (!seat_has_vts(s))
 539                 seat_set_active(s, session);
 540
 541         return 0;
 542 }
 543
 544 void seat_complete_switch(Seat *s) {
 545         Session *session;
 546
 547         assert(s);
 548
 549         /* if no session-switch is pending or if it got canceled, do nothing */
 550         if (!s->pending_switch)
 551                 return;
 552
 553         session = TAKE_PTR(s->pending_switch);
 554
 555         seat_set_active(s, session);
 556 }
 557
 558 bool seat_has_vts(Seat *s) {
 559         assert(s);
 560
 561         return seat_is_seat0(s) && s->manager->console_active_fd >= 0;
 562 }
 563
 564 bool seat_is_seat0(Seat *s) {
 565         assert(s);
 566
 567         return s->manager->seat0 == s;
 568 }
 569
 570 bool seat_can_tty(Seat *s) {
 571         assert(s);
 572
 573         return seat_has_vts(s);
 574 }
 575
 576 bool seat_has_master_device(Seat *s) {
 577         assert(s);
 578
 579         /* device list is ordered by "master" flag */
 580         return !!s->devices && s->devices->master;
 581 }
 582
 583 bool seat_can_graphical(Seat *s) {
 584         assert(s);
 585
 586         return seat_has_master_device(s);
 587 }
 588
 589 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 590         bool idle_hint = true;
 591         dual_timestamp ts = DUAL_TIMESTAMP_NULL;
 592
 593         assert(s);
 594
 595         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 596                 dual_timestamp k;
 597                 int ih;
 598
 599                 ih = session_get_idle_hint(session, &k);
 600                 if (ih < 0)
 601                         return ih;
 602
 603                 if (!ih) {
 604                         if (!idle_hint) {
 605                                 if (k.monotonic > ts.monotonic)
 606                                         ts = k;
 607                         } else {
 608                                 idle_hint = false;
 609                                 ts = k;
 610                         }
 611                 } else if (idle_hint) {
 612
 613                         if (k.monotonic > ts.monotonic)
 614                                 ts = k;
 615                 }
 616         }
 617
 618         if (t)
 619                 *t = ts;
 620
 621         return idle_hint;
 622 }
 623
 624 bool seat_may_gc(Seat *s, bool drop_not_started) {
 625         assert(s);
 626
 627         if (drop_not_started && !s->started)
 628                 return true;
 629
 630         if (seat_is_seat0(s))
 631                 return false;
 632
 633         return !seat_has_master_device(s);
 634 }
 635
 636 void seat_add_to_gc_queue(Seat *s) {
 637         assert(s);
 638
 639         if (s->in_gc_queue)
 640                 return;
 641
 642         LIST_PREPEND(gc_queue, s->manager->seat_gc_queue, s);
 643         s->in_gc_queue = true;
 644 }
 645
 646 static bool seat_name_valid_char(char c) {
 647         return
 648                 ascii_isalpha(c) ||
 649                 ascii_isdigit(c) ||
 650                 IN_SET(c, '-', '_');
 651 }
 652
 653 bool seat_name_is_valid(const char *name) {
 654         const char *p;
 655
 656         assert(name);
 657
 658         if (!startswith(name, "seat"))
 659                 return false;
 660
 661         if (!name[4])
 662                 return false;
 663
 664         for (p = name; *p; p++)
 665                 if (!seat_name_valid_char(*p))
 666                         return false;
 667
 668         if (strlen(name) > 255)
 669                 return false;
 670
 671         return true;
 672 }