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 static int vt_allocate(unsigned int vtnr) {
 160         char p[sizeof("/dev/tty") + DECIMAL_STR_MAX(unsigned int)];
 161         _cleanup_close_ int fd = -1;
 162
 163         assert(vtnr >= 1);
 164
 165         xsprintf(p, "/dev/tty%u", vtnr);
 166         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 167         if (fd < 0)
 168                 return -errno;
 169
 170         return 0;
 171 }
 172
 173 int seat_preallocate_vts(Seat *s) {
 174         int r = 0;
 175         unsigned i;
 176
 177         assert(s);
 178         assert(s->manager);
 179
 180         log_debug("Preallocating VTs...");
 181
 182         if (s->manager->n_autovts <= 0)
 183                 return 0;
 184
 185         if (!seat_has_vts(s))
 186                 return 0;
 187
 188         for (i = 1; i <= s->manager->n_autovts; i++) {
 189                 int q;
 190
 191                 q = vt_allocate(i);
 192                 if (q < 0) {
 193                         log_error_errno(q, "Failed to preallocate VT %u: %m", i);
 194                         r = q;
 195                 }
 196         }
 197
 198         return r;
 199 }
 200
 201 int seat_apply_acls(Seat *s, Session *old_active) {
 202         int r;
 203
 204         assert(s);
 205
 206         r = devnode_acl_all(s->manager->udev,
 207                             s->id,
 208                             false,
 209                             !!old_active, old_active ? old_active->user->uid : 0,
 210                             !!s->active, s->active ? s->active->user->uid : 0);
 211
 212         if (r < 0)
 213                 log_error_errno(r, "Failed to apply ACLs: %m");
 214
 215         return r;
 216 }
 217
 218 int seat_set_active(Seat *s, Session *session) {
 219         Session *old_active;
 220
 221         assert(s);
 222         assert(!session || session->seat == s);
 223
 224         if (session == s->active)
 225                 return 0;
 226
 227         old_active = s->active;
 228         s->active = session;
 229
 230         if (old_active) {
 231                 session_device_pause_all(old_active);
 232                 session_send_changed(old_active, "Active", NULL);
 233         }
 234
 235         seat_apply_acls(s, old_active);
 236
 237         if (session && session->started) {
 238                 session_send_changed(session, "Active", NULL);
 239                 session_device_resume_all(session);
 240         }
 241
 242         if (!session || session->started)
 243                 seat_send_changed(s, "ActiveSession", NULL);
 244
 245         seat_save(s);
 246
 247         if (session) {
 248                 session_save(session);
 249                 user_save(session->user);
 250         }
 251
 252         if (old_active) {
 253                 session_save(old_active);
 254                 if (!session || session->user != old_active->user)
 255                         user_save(old_active->user);
 256         }
 257
 258         return 0;
 259 }
 260
 261 int seat_switch_to(Seat *s, unsigned int num) {
 262         /* Public session positions skip 0 (there is only F1-F12). Maybe it
 263          * will get reassigned in the future, so return error for now. */
 264         if (num == 0)
 265                 return -EINVAL;
 266
 267         if (num >= s->position_count || !s->positions[num]) {
 268                 /* allow switching to unused VTs to trigger auto-activate */
 269                 if (seat_has_vts(s) && num < 64)
 270                         return chvt(num);
 271
 272                 return -EINVAL;
 273         }
 274
 275         return session_activate(s->positions[num]);
 276 }
 277
 278 int seat_switch_to_next(Seat *s) {
 279         unsigned int start, i;
 280
 281         if (s->position_count == 0)
 282                 return -EINVAL;
 283
 284         start = 1;
 285         if (s->active && s->active->position > 0)
 286                 start = s->active->position;
 287
 288         for (i = start + 1; i < s->position_count; ++i)
 289                 if (s->positions[i])
 290                         return session_activate(s->positions[i]);
 291
 292         for (i = 1; i < start; ++i)
 293                 if (s->positions[i])
 294                         return session_activate(s->positions[i]);
 295
 296         return -EINVAL;
 297 }
 298
 299 int seat_switch_to_previous(Seat *s) {
 300         unsigned int start, i;
 301
 302         if (s->position_count == 0)
 303                 return -EINVAL;
 304
 305         start = 1;
 306         if (s->active && s->active->position > 0)
 307                 start = s->active->position;
 308
 309         for (i = start - 1; i > 0; --i)
 310                 if (s->positions[i])
 311                         return session_activate(s->positions[i]);
 312
 313         for (i = s->position_count - 1; i > start; --i)
 314                 if (s->positions[i])
 315                         return session_activate(s->positions[i]);
 316
 317         return -EINVAL;
 318 }
 319
 320 int seat_active_vt_changed(Seat *s, unsigned int vtnr) {
 321         Session *i, *new_active = NULL;
 322         int r;
 323
 324         assert(s);
 325         assert(vtnr >= 1);
 326
 327         if (!seat_has_vts(s))
 328                 return -EINVAL;
 329
 330         log_debug("VT changed to %u", vtnr);
 331
 332         /* we might have earlier closing sessions on the same VT, so try to
 333          * find a running one first */
 334         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 335                 if (i->vtnr == vtnr && !i->stopping) {
 336                         new_active = i;
 337                         break;
 338                 }
 339
 340         if (!new_active) {
 341                 /* no running one? then we can't decide which one is the
 342                  * active one, let the first one win */
 343                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 344                         if (i->vtnr == vtnr) {
 345                                 new_active = i;
 346                                 break;
 347                         }
 348         }
 349
 350         r = seat_set_active(s, new_active);
 351         manager_spawn_autovt(s->manager, vtnr);
 352
 353         return r;
 354 }
 355
 356 int seat_read_active_vt(Seat *s) {
 357         char t[64];
 358         ssize_t k;
 359         unsigned int vtnr;
 360         int r;
 361
 362         assert(s);
 363
 364         if (!seat_has_vts(s))
 365                 return 0;
 366
 367         if (lseek(s->manager->console_active_fd, SEEK_SET, 0) < 0)
 368                 return log_error_errno(errno, "lseek on console_active_fd failed: %m");
 369
 370         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 371         if (k <= 0) {
 372                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 373                 return k < 0 ? -errno : -EIO;
 374         }
 375
 376         t[k] = 0;
 377         truncate_nl(t);
 378
 379         if (!startswith(t, "tty")) {
 380                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 381                 return -EIO;
 382         }
 383
 384         r = safe_atou(t+3, &vtnr);
 385         if (r < 0)
 386                 return log_error_errno(r, "Failed to parse VT number \"%s\": %m", t+3);
 387
 388         if (!vtnr) {
 389                 log_error("VT number invalid: %s", t+3);
 390                 return -EIO;
 391         }
 392
 393         return seat_active_vt_changed(s, vtnr);
 394 }
 395
 396 int seat_start(Seat *s) {
 397         assert(s);
 398
 399         if (s->started)
 400                 return 0;
 401
 402         log_struct(LOG_INFO,
 403                    "MESSAGE_ID=" SD_MESSAGE_SEAT_START_STR,
 404                    "SEAT_ID=%s", s->id,
 405                    LOG_MESSAGE("New seat %s.", s->id));
 406
 407         /* Initialize VT magic stuff */
 408         seat_preallocate_vts(s);
 409
 410         /* Read current VT */
 411         seat_read_active_vt(s);
 412
 413         s->started = true;
 414
 415         /* Save seat data */
 416         seat_save(s);
 417
 418         seat_send_signal(s, true);
 419
 420         return 0;
 421 }
 422
 423 int seat_stop(Seat *s, bool force) {
 424         int r = 0;
 425
 426         assert(s);
 427
 428         if (s->started)
 429                 log_struct(LOG_INFO,
 430                            "MESSAGE_ID=" SD_MESSAGE_SEAT_STOP_STR,
 431                            "SEAT_ID=%s", s->id,
 432                            LOG_MESSAGE("Removed seat %s.", s->id));
 433
 434         seat_stop_sessions(s, force);
 435
 436         unlink(s->state_file);
 437         seat_add_to_gc_queue(s);
 438
 439         if (s->started)
 440                 seat_send_signal(s, false);
 441
 442         s->started = false;
 443
 444         return r;
 445 }
 446
 447 int seat_stop_sessions(Seat *s, bool force) {
 448         Session *session;
 449         int r = 0, k;
 450
 451         assert(s);
 452
 453         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 454                 k = session_stop(session, force);
 455                 if (k < 0)
 456                         r = k;
 457         }
 458
 459         return r;
 460 }
 461
 462 void seat_evict_position(Seat *s, Session *session) {
 463         Session *iter;
 464         unsigned int pos = session->position;
 465
 466         session->position = 0;
 467
 468         if (pos == 0)
 469                 return;
 470
 471         if (pos < s->position_count && s->positions[pos] == session) {
 472                 s->positions[pos] = NULL;
 473
 474                 /* There might be another session claiming the same
 475                  * position (eg., during gdm->session transition), so let's look
 476                  * for it and set it on the free slot. */
 477                 LIST_FOREACH(sessions_by_seat, iter, s->sessions) {
 478                         if (iter->position == pos && session_get_state(iter) != SESSION_CLOSING) {
 479                                 s->positions[pos] = iter;
 480                                 break;
 481                         }
 482                 }
 483         }
 484 }
 485
 486 void seat_claim_position(Seat *s, Session *session, unsigned int pos) {
 487         /* with VTs, the position is always the same as the VTnr */
 488         if (seat_has_vts(s))
 489                 pos = session->vtnr;
 490
 491         if (!GREEDY_REALLOC0(s->positions, s->position_count, pos + 1))
 492                 return;
 493
 494         seat_evict_position(s, session);
 495
 496         session->position = pos;
 497         if (pos > 0)
 498                 s->positions[pos] = session;
 499 }
 500
 501 static void seat_assign_position(Seat *s, Session *session) {
 502         unsigned int pos;
 503
 504         if (session->position > 0)
 505                 return;
 506
 507         for (pos = 1; pos < s->position_count; ++pos)
 508                 if (!s->positions[pos])
 509                         break;
 510
 511         seat_claim_position(s, session, pos);
 512 }
 513
 514 int seat_attach_session(Seat *s, Session *session) {
 515         assert(s);
 516         assert(session);
 517         assert(!session->seat);
 518
 519         if (!seat_has_vts(s) != !session->vtnr)
 520                 return -EINVAL;
 521
 522         session->seat = s;
 523         LIST_PREPEND(sessions_by_seat, s->sessions, session);
 524         seat_assign_position(s, session);
 525
 526         /* On seats with VTs, the VT logic defines which session is active. On
 527          * seats without VTs, we automatically activate new sessions. */
 528         if (!seat_has_vts(s))
 529                 seat_set_active(s, session);
 530
 531         return 0;
 532 }
 533
 534 void seat_complete_switch(Seat *s) {
 535         Session *session;
 536
 537         assert(s);
 538
 539         /* if no session-switch is pending or if it got canceled, do nothing */
 540         if (!s->pending_switch)
 541                 return;
 542
 543         session = TAKE_PTR(s->pending_switch);
 544
 545         seat_set_active(s, session);
 546 }
 547
 548 bool seat_has_vts(Seat *s) {
 549         assert(s);
 550
 551         return seat_is_seat0(s) && s->manager->console_active_fd >= 0;
 552 }
 553
 554 bool seat_is_seat0(Seat *s) {
 555         assert(s);
 556
 557         return s->manager->seat0 == s;
 558 }
 559
 560 bool seat_can_multi_session(Seat *s) {
 561         assert(s);
 562
 563         return seat_has_vts(s);
 564 }
 565
 566 bool seat_can_tty(Seat *s) {
 567         assert(s);
 568
 569         return seat_has_vts(s);
 570 }
 571
 572 bool seat_has_master_device(Seat *s) {
 573         assert(s);
 574
 575         /* device list is ordered by "master" flag */
 576         return !!s->devices && s->devices->master;
 577 }
 578
 579 bool seat_can_graphical(Seat *s) {
 580         assert(s);
 581
 582         return seat_has_master_device(s);
 583 }
 584
 585 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 586         Session *session;
 587         bool idle_hint = true;
 588         dual_timestamp ts = DUAL_TIMESTAMP_NULL;
 589
 590         assert(s);
 591
 592         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 593                 dual_timestamp k;
 594                 int ih;
 595
 596                 ih = session_get_idle_hint(session, &k);
 597                 if (ih < 0)
 598                         return ih;
 599
 600                 if (!ih) {
 601                         if (!idle_hint) {
 602                                 if (k.monotonic > ts.monotonic)
 603                                         ts = k;
 604                         } else {
 605                                 idle_hint = false;
 606                                 ts = k;
 607                         }
 608                 } else if (idle_hint) {
 609
 610                         if (k.monotonic > ts.monotonic)
 611                                 ts = k;
 612                 }
 613         }
 614
 615         if (t)
 616                 *t = ts;
 617
 618         return idle_hint;
 619 }
 620
 621 bool seat_may_gc(Seat *s, bool drop_not_started) {
 622         assert(s);
 623
 624         if (drop_not_started && !s->started)
 625                 return true;
 626
 627         if (seat_is_seat0(s))
 628                 return false;
 629
 630         return !seat_has_master_device(s);
 631 }
 632
 633 void seat_add_to_gc_queue(Seat *s) {
 634         assert(s);
 635
 636         if (s->in_gc_queue)
 637                 return;
 638
 639         LIST_PREPEND(gc_queue, s->manager->seat_gc_queue, s);
 640         s->in_gc_queue = true;
 641 }
 642
 643 static bool seat_name_valid_char(char c) {
 644         return
 645                 (c >= 'a' && c <= 'z') ||
 646                 (c >= 'A' && c <= 'Z') ||
 647                 (c >= '0' && c <= '9') ||
 648                 IN_SET(c, '-', '_');
 649 }
 650
 651 bool seat_name_is_valid(const char *name) {
 652         const char *p;
 653
 654         assert(name);
 655
 656         if (!startswith(name, "seat"))
 657                 return false;
 658
 659         if (!name[4])
 660                 return false;
 661
 662         for (p = name; *p; p++)
 663                 if (!seat_name_valid_char(*p))
 664                         return false;
 665
 666         if (strlen(name) > 255)
 667                 return false;
 668
 669         return true;
 670 }