src/login/logind-seat.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <stdio_ext.h>
   6 #include <string.h>
   7 #include <unistd.h>
   8
   9 #include "sd-messages.h"
  10
  11 #include "alloc-util.h"
  12 #include "fd-util.h"
  13 #include "fileio.h"
  14 #include "format-util.h"
  15 #include "logind-acl.h"
  16 #include "logind-seat.h"
  17 #include "mkdir.h"
  18 #include "parse-util.h"
  19 #include "stdio-util.h"
  20 #include "string-util.h"
  21 #include "terminal-util.h"
  22 #include "util.h"
  23
  24 Seat *seat_new(Manager *m, const char *id) {
  25         Seat *s;
  26
  27         assert(m);
  28         assert(id);
  29
  30         s = new0(Seat, 1);
  31         if (!s)
  32                 return NULL;
  33
  34         s->state_file = strappend("/run/systemd/seats/", id);
  35         if (!s->state_file)
  36                 return mfree(s);
  37
  38         s->id = basename(s->state_file);
  39         s->manager = m;
  40
  41         if (hashmap_put(m->seats, s->id, s) < 0) {
  42                 free(s->state_file);
  43                 return mfree(s);
  44         }
  45
  46         return s;
  47 }
  48
  49 void seat_free(Seat *s) {
  50         assert(s);
  51
  52         if (s->in_gc_queue)
  53                 LIST_REMOVE(gc_queue, s->manager->seat_gc_queue, s);
  54
  55         while (s->sessions)
  56                 session_free(s->sessions);
  57
  58         assert(!s->active);
  59
  60         while (s->devices)
  61                 device_free(s->devices);
  62
  63         hashmap_remove(s->manager->seats, s->id);
  64
  65         free(s->positions);
  66         free(s->state_file);
  67         free(s);
  68 }
  69
  70 int seat_save(Seat *s) {
  71         _cleanup_free_ char *temp_path = NULL;
  72         _cleanup_fclose_ FILE *f = NULL;
  73         int r;
  74
  75         assert(s);
  76
  77         if (!s->started)
  78                 return 0;
  79
  80         r = mkdir_safe_label("/run/systemd/seats", 0755, 0, 0, MKDIR_WARN_MODE);
  81         if (r < 0)
  82                 goto fail;
  83
  84         r = fopen_temporary(s->state_file, &f, &temp_path);
  85         if (r < 0)
  86                 goto fail;
  87
  88         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
  89         (void) fchmod(fileno(f), 0644);
  90
  91         fprintf(f,
  92                 "# This is private data. Do not parse.\n"
  93                 "IS_SEAT0=%i\n"
  94                 "CAN_MULTI_SESSION=%i\n"
  95                 "CAN_TTY=%i\n"
  96                 "CAN_GRAPHICAL=%i\n",
  97                 seat_is_seat0(s),
  98                 seat_can_multi_session(s),
  99                 seat_can_tty(s),
 100                 seat_can_graphical(s));
 101
 102         if (s->active) {
 103                 assert(s->active->user);
 104
 105                 fprintf(f,
 106                         "ACTIVE=%s\n"
 107                         "ACTIVE_UID="UID_FMT"\n",
 108                         s->active->id,
 109                         s->active->user->uid);
 110         }
 111
 112         if (s->sessions) {
 113                 Session *i;
 114
 115                 fputs("SESSIONS=", f);
 116                 LIST_FOREACH(sessions_by_seat, i, s->sessions) {
 117                         fprintf(f,
 118                                 "%s%c",
 119                                 i->id,
 120                                 i->sessions_by_seat_next ? ' ' : '\n');
 121                 }
 122
 123                 fputs("UIDS=", f);
 124                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 125                         fprintf(f,
 126                                 UID_FMT"%c",
 127                                 i->user->uid,
 128                                 i->sessions_by_seat_next ? ' ' : '\n');
 129         }
 130
 131         r = fflush_and_check(f);
 132         if (r < 0)
 133                 goto fail;
 134
 135         if (rename(temp_path, s->state_file) < 0) {
 136                 r = -errno;
 137                 goto fail;
 138         }
 139
 140         return 0;
 141
 142 fail:
 143         (void) unlink(s->state_file);
 144
 145         if (temp_path)
 146                 (void) unlink(temp_path);
 147
 148         return log_error_errno(r, "Failed to save seat data %s: %m", s->state_file);
 149 }
 150
 151 int seat_load(Seat *s) {
 152         assert(s);
 153
 154         /* There isn't actually anything to read here ... */
 155
 156         return 0;
 157 }
 158
 159 #if 0 /// UNNEEDED by elogind
 160 static int vt_allocate(unsigned int vtnr) {
 161         char p[sizeof("/dev/tty") + DECIMAL_STR_MAX(unsigned int)];
 162         _cleanup_close_ int fd = -1;
 163
 164         assert(vtnr >= 1);
 165
 166         xsprintf(p, "/dev/tty%u", vtnr);
 167         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 168         if (fd < 0)
 169                 return -errno;
 170
 171         return 0;
 172 }
 173
 174 int seat_preallocate_vts(Seat *s) {
 175         int r = 0;
 176         unsigned i;
 177
 178         assert(s);
 179         assert(s->manager);
 180
 181         log_debug("Preallocating VTs...");
 182
 183         if (s->manager->n_autovts <= 0)
 184                 return 0;
 185
 186         if (!seat_has_vts(s))
 187                 return 0;
 188
 189         for (i = 1; i <= s->manager->n_autovts; i++) {
 190                 int q;
 191
 192                 q = vt_allocate(i);
 193                 if (q < 0) {
 194                         log_error_errno(q, "Failed to preallocate VT %u: %m", i);
 195                         r = q;
 196                 }
 197         }
 198
 199         return r;
 200 }
 201 #endif // 0
 202
 203 int seat_apply_acls(Seat *s, Session *old_active) {
 204         int r;
 205
 206         assert(s);
 207
 208         r = devnode_acl_all(s->manager->udev,
 209                             s->id,
 210                             false,
 211                             !!old_active, old_active ? old_active->user->uid : 0,
 212                             !!s->active, s->active ? s->active->user->uid : 0);
 213
 214         if (r < 0)
 215                 log_error_errno(r, "Failed to apply ACLs: %m");
 216
 217         return r;
 218 }
 219
 220 int seat_set_active(Seat *s, Session *session) {
 221         Session *old_active;
 222
 223         assert(s);
 224         assert(!session || session->seat == s);
 225
 226         if (session == s->active)
 227                 return 0;
 228
 229         old_active = s->active;
 230         s->active = session;
 231
 232         if (old_active) {
 233                 session_device_pause_all(old_active);
 234                 session_send_changed(old_active, "Active", NULL);
 235         }
 236
 237         seat_apply_acls(s, old_active);
 238
 239         if (session && session->started) {
 240                 session_send_changed(session, "Active", NULL);
 241                 session_device_resume_all(session);
 242         }
 243
 244         if (!session || session->started)
 245                 seat_send_changed(s, "ActiveSession", NULL);
 246
 247         seat_save(s);
 248
 249         if (session) {
 250                 session_save(session);
 251                 user_save(session->user);
 252         }
 253
 254         if (old_active) {
 255                 session_save(old_active);
 256                 if (!session || session->user != old_active->user)
 257                         user_save(old_active->user);
 258         }
 259
 260         return 0;
 261 }
 262
 263 int seat_switch_to(Seat *s, unsigned int num) {
 264         /* Public session positions skip 0 (there is only F1-F12). Maybe it
 265          * will get reassigned in the future, so return error for now. */
 266         if (num == 0)
 267                 return -EINVAL;
 268
 269         if (num >= s->position_count || !s->positions[num]) {
 270                 /* allow switching to unused VTs to trigger auto-activate */
 271                 if (seat_has_vts(s) && num < 64)
 272                         return chvt(num);
 273
 274                 return -EINVAL;
 275         }
 276
 277         return session_activate(s->positions[num]);
 278 }
 279
 280 int seat_switch_to_next(Seat *s) {
 281         unsigned int start, i;
 282
 283         if (s->position_count == 0)
 284                 return -EINVAL;
 285
 286         start = 1;
 287         if (s->active && s->active->position > 0)
 288                 start = s->active->position;
 289
 290         for (i = start + 1; i < s->position_count; ++i)
 291                 if (s->positions[i])
 292                         return session_activate(s->positions[i]);
 293
 294         for (i = 1; i < start; ++i)
 295                 if (s->positions[i])
 296                         return session_activate(s->positions[i]);
 297
 298         return -EINVAL;
 299 }
 300
 301 int seat_switch_to_previous(Seat *s) {
 302         unsigned int start, i;
 303
 304         if (s->position_count == 0)
 305                 return -EINVAL;
 306
 307         start = 1;
 308         if (s->active && s->active->position > 0)
 309                 start = s->active->position;
 310
 311         for (i = start - 1; i > 0; --i)
 312                 if (s->positions[i])
 313                         return session_activate(s->positions[i]);
 314
 315         for (i = s->position_count - 1; i > start; --i)
 316                 if (s->positions[i])
 317                         return session_activate(s->positions[i]);
 318
 319         return -EINVAL;
 320 }
 321
 322 int seat_active_vt_changed(Seat *s, unsigned int vtnr) {
 323         Session *i, *new_active = NULL;
 324         int r;
 325
 326         assert(s);
 327         assert(vtnr >= 1);
 328
 329         if (!seat_has_vts(s))
 330                 return -EINVAL;
 331
 332         log_debug("VT changed to %u", vtnr);
 333
 334         /* we might have earlier closing sessions on the same VT, so try to
 335          * find a running one first */
 336         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 337                 if (i->vtnr == vtnr && !i->stopping) {
 338                         new_active = i;
 339                         break;
 340                 }
 341
 342         if (!new_active) {
 343                 /* no running one? then we can't decide which one is the
 344                  * active one, let the first one win */
 345                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 346                         if (i->vtnr == vtnr) {
 347                                 new_active = i;
 348                                 break;
 349                         }
 350         }
 351
 352         r = seat_set_active(s, new_active);
 353 #if 0 /// elogind does not spawn autovt
 354         manager_spawn_autovt(s->manager, vtnr);
 355 #endif // 0
 356
 357         return r;
 358 }
 359
 360 int seat_read_active_vt(Seat *s) {
 361         char t[64];
 362         ssize_t k;
 363         unsigned int vtnr;
 364         int r;
 365
 366         assert(s);
 367
 368         if (!seat_has_vts(s))
 369                 return 0;
 370
 371         if (lseek(s->manager->console_active_fd, SEEK_SET, 0) < 0)
 372                 return log_error_errno(errno, "lseek on console_active_fd failed: %m");
 373
 374         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 375         if (k <= 0) {
 376                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 377                 return k < 0 ? -errno : -EIO;
 378         }
 379
 380         t[k] = 0;
 381         truncate_nl(t);
 382
 383         if (!startswith(t, "tty")) {
 384                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 385                 return -EIO;
 386         }
 387
 388         r = safe_atou(t+3, &vtnr);
 389         if (r < 0)
 390                 return log_error_errno(r, "Failed to parse VT number \"%s\": %m", t+3);
 391
 392         if (!vtnr) {
 393                 log_error("VT number invalid: %s", t+3);
 394                 return -EIO;
 395         }
 396
 397         return seat_active_vt_changed(s, vtnr);
 398 }
 399
 400 int seat_start(Seat *s) {
 401         assert(s);
 402
 403         if (s->started)
 404                 return 0;
 405
 406         log_struct(LOG_INFO,
 407                    "MESSAGE_ID=" SD_MESSAGE_SEAT_START_STR,
 408                    "SEAT_ID=%s", s->id,
 409                    LOG_MESSAGE("New seat %s.", s->id));
 410
 411         /* Initialize VT magic stuff */
 412 #if 0 /// elogind does not support autospawning vts
 413         seat_preallocate_vts(s);
 414 #endif // 0
 415
 416         /* Read current VT */
 417         seat_read_active_vt(s);
 418
 419         s->started = true;
 420
 421         /* Save seat data */
 422         seat_save(s);
 423
 424         seat_send_signal(s, true);
 425
 426         return 0;
 427 }
 428
 429 int seat_stop(Seat *s, bool force) {
 430         int r = 0;
 431
 432         assert(s);
 433
 434         if (s->started)
 435                 log_struct(LOG_INFO,
 436                            "MESSAGE_ID=" SD_MESSAGE_SEAT_STOP_STR,
 437                            "SEAT_ID=%s", s->id,
 438                            LOG_MESSAGE("Removed seat %s.", s->id));
 439
 440         seat_stop_sessions(s, force);
 441
 442         unlink(s->state_file);
 443         seat_add_to_gc_queue(s);
 444
 445         if (s->started)
 446                 seat_send_signal(s, false);
 447
 448         s->started = false;
 449
 450         return r;
 451 }
 452
 453 int seat_stop_sessions(Seat *s, bool force) {
 454         Session *session;
 455         int r = 0, k;
 456
 457         assert(s);
 458
 459         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 460                 k = session_stop(session, force);
 461                 if (k < 0)
 462                         r = k;
 463         }
 464
 465         return r;
 466 }
 467
 468 void seat_evict_position(Seat *s, Session *session) {
 469         Session *iter;
 470         unsigned int pos = session->position;
 471
 472         session->position = 0;
 473
 474         if (pos == 0)
 475                 return;
 476
 477         if (pos < s->position_count && s->positions[pos] == session) {
 478                 s->positions[pos] = NULL;
 479
 480                 /* There might be another session claiming the same
 481                  * position (eg., during gdm->session transition), so let's look
 482                  * for it and set it on the free slot. */
 483                 LIST_FOREACH(sessions_by_seat, iter, s->sessions) {
 484                         if (iter->position == pos && session_get_state(iter) != SESSION_CLOSING) {
 485                                 s->positions[pos] = iter;
 486                                 break;
 487                         }
 488                 }
 489         }
 490 }
 491
 492 void seat_claim_position(Seat *s, Session *session, unsigned int pos) {
 493         /* with VTs, the position is always the same as the VTnr */
 494         if (seat_has_vts(s))
 495                 pos = session->vtnr;
 496
 497         if (!GREEDY_REALLOC0(s->positions, s->position_count, pos + 1))
 498                 return;
 499
 500         seat_evict_position(s, session);
 501
 502         session->position = pos;
 503         if (pos > 0)
 504                 s->positions[pos] = session;
 505 }
 506
 507 static void seat_assign_position(Seat *s, Session *session) {
 508         unsigned int pos;
 509
 510         if (session->position > 0)
 511                 return;
 512
 513         for (pos = 1; pos < s->position_count; ++pos)
 514                 if (!s->positions[pos])
 515                         break;
 516
 517         seat_claim_position(s, session, pos);
 518 }
 519
 520 int seat_attach_session(Seat *s, Session *session) {
 521         assert(s);
 522         assert(session);
 523         assert(!session->seat);
 524
 525         if (!seat_has_vts(s) != !session->vtnr)
 526                 return -EINVAL;
 527
 528         session->seat = s;
 529         LIST_PREPEND(sessions_by_seat, s->sessions, session);
 530         seat_assign_position(s, session);
 531
 532         /* On seats with VTs, the VT logic defines which session is active. On
 533          * seats without VTs, we automatically activate new sessions. */
 534         if (!seat_has_vts(s))
 535                 seat_set_active(s, session);
 536
 537         return 0;
 538 }
 539
 540 void seat_complete_switch(Seat *s) {
 541         Session *session;
 542
 543         assert(s);
 544
 545         /* if no session-switch is pending or if it got canceled, do nothing */
 546         if (!s->pending_switch)
 547                 return;
 548
 549         session = TAKE_PTR(s->pending_switch);
 550
 551         seat_set_active(s, session);
 552 }
 553
 554 bool seat_has_vts(Seat *s) {
 555         assert(s);
 556
 557         return seat_is_seat0(s) && s->manager->console_active_fd >= 0;
 558 }
 559
 560 bool seat_is_seat0(Seat *s) {
 561         assert(s);
 562
 563         return s->manager->seat0 == s;
 564 }
 565
 566 bool seat_can_multi_session(Seat *s) {
 567         assert(s);
 568
 569         return seat_has_vts(s);
 570 }
 571
 572 bool seat_can_tty(Seat *s) {
 573         assert(s);
 574
 575         return seat_has_vts(s);
 576 }
 577
 578 bool seat_has_master_device(Seat *s) {
 579         assert(s);
 580
 581         /* device list is ordered by "master" flag */
 582         return !!s->devices && s->devices->master;
 583 }
 584
 585 bool seat_can_graphical(Seat *s) {
 586         assert(s);
 587
 588         return seat_has_master_device(s);
 589 }
 590
 591 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 592         Session *session;
 593         bool idle_hint = true;
 594         dual_timestamp ts = DUAL_TIMESTAMP_NULL;
 595
 596         assert(s);
 597
 598         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 599                 dual_timestamp k;
 600                 int ih;
 601
 602                 ih = session_get_idle_hint(session, &k);
 603                 if (ih < 0)
 604                         return ih;
 605
 606                 if (!ih) {
 607                         if (!idle_hint) {
 608                                 if (k.monotonic > ts.monotonic)
 609                                         ts = k;
 610                         } else {
 611                                 idle_hint = false;
 612                                 ts = k;
 613                         }
 614                 } else if (idle_hint) {
 615
 616                         if (k.monotonic > ts.monotonic)
 617                                 ts = k;
 618                 }
 619         }
 620
 621         if (t)
 622                 *t = ts;
 623
 624         return idle_hint;
 625 }
 626
 627 bool seat_may_gc(Seat *s, bool drop_not_started) {
 628         assert(s);
 629
 630         if (drop_not_started && !s->started)
 631                 return true;
 632
 633         if (seat_is_seat0(s))
 634                 return false;
 635
 636         return !seat_has_master_device(s);
 637 }
 638
 639 void seat_add_to_gc_queue(Seat *s) {
 640         assert(s);
 641
 642         if (s->in_gc_queue)
 643                 return;
 644
 645         LIST_PREPEND(gc_queue, s->manager->seat_gc_queue, s);
 646         s->in_gc_queue = true;
 647 }
 648
 649 static bool seat_name_valid_char(char c) {
 650         return
 651                 (c >= 'a' && c <= 'z') ||
 652                 (c >= 'A' && c <= 'Z') ||
 653                 (c >= '0' && c <= '9') ||
 654                 IN_SET(c, '-', '_');
 655 }
 656
 657 bool seat_name_is_valid(const char *name) {
 658         const char *p;
 659
 660         assert(name);
 661
 662         if (!startswith(name, "seat"))
 663                 return false;
 664
 665         if (!name[4])
 666                 return false;
 667
 668         for (p = name; *p; p++)
 669                 if (!seat_name_valid_char(*p))
 670                         return false;
 671
 672         if (strlen(name) > 255)
 673                 return false;
 674
 675         return true;
 676 }