src/login/logind-seat.c

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