src/login/logind-seat.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2011 Lennart Poettering
   6 ***/
   7
   8 #include <errno.h>
   9 #include <fcntl.h>
  10 #include <stdio_ext.h>
  11 #include <string.h>
  12 #include <unistd.h>
  13
  14 #include "sd-messages.h"
  15
  16 #include "alloc-util.h"
  17 #include "fd-util.h"
  18 #include "fileio.h"
  19 #include "format-util.h"
  20 #include "logind-acl.h"
  21 #include "logind-seat.h"
  22 #include "mkdir.h"
  23 #include "parse-util.h"
  24 #include "stdio-util.h"
  25 #include "string-util.h"
  26 #include "terminal-util.h"
  27 #include "util.h"
  28
  29 Seat *seat_new(Manager *m, const char *id) {
  30         Seat *s;
  31
  32         assert(m);
  33         assert(id);
  34
  35         s = new0(Seat, 1);
  36         if (!s)
  37                 return NULL;
  38
  39         s->state_file = strappend("/run/systemd/seats/", id);
  40         if (!s->state_file)
  41                 return mfree(s);
  42
  43         s->id = basename(s->state_file);
  44         s->manager = m;
  45
  46         if (hashmap_put(m->seats, s->id, s) < 0) {
  47                 free(s->state_file);
  48                 return mfree(s);
  49         }
  50
  51         return s;
  52 }
  53
  54 void seat_free(Seat *s) {
  55         assert(s);
  56
  57         if (s->in_gc_queue)
  58                 LIST_REMOVE(gc_queue, s->manager->seat_gc_queue, s);
  59
  60         while (s->sessions)
  61                 session_free(s->sessions);
  62
  63         assert(!s->active);
  64
  65         while (s->devices)
  66                 device_free(s->devices);
  67
  68         hashmap_remove(s->manager->seats, s->id);
  69
  70         free(s->positions);
  71         free(s->state_file);
  72         free(s);
  73 }
  74
  75 int seat_save(Seat *s) {
  76         _cleanup_free_ char *temp_path = NULL;
  77         _cleanup_fclose_ FILE *f = NULL;
  78         int r;
  79
  80         assert(s);
  81
  82         if (!s->started)
  83                 return 0;
  84
  85         r = mkdir_safe_label("/run/systemd/seats", 0755, 0, 0, MKDIR_WARN_MODE);
  86         if (r < 0)
  87                 goto fail;
  88
  89         r = fopen_temporary(s->state_file, &f, &temp_path);
  90         if (r < 0)
  91                 goto fail;
  92
  93         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
  94         (void) fchmod(fileno(f), 0644);
  95
  96         fprintf(f,
  97                 "# This is private data. Do not parse.\n"
  98                 "IS_SEAT0=%i\n"
  99                 "CAN_MULTI_SESSION=%i\n"
 100                 "CAN_TTY=%i\n"
 101                 "CAN_GRAPHICAL=%i\n",
 102                 seat_is_seat0(s),
 103                 seat_can_multi_session(s),
 104                 seat_can_tty(s),
 105                 seat_can_graphical(s));
 106
 107         if (s->active) {
 108                 assert(s->active->user);
 109
 110                 fprintf(f,
 111                         "ACTIVE=%s\n"
 112                         "ACTIVE_UID="UID_FMT"\n",
 113                         s->active->id,
 114                         s->active->user->uid);
 115         }
 116
 117         if (s->sessions) {
 118                 Session *i;
 119
 120                 fputs("SESSIONS=", f);
 121                 LIST_FOREACH(sessions_by_seat, i, s->sessions) {
 122                         fprintf(f,
 123                                 "%s%c",
 124                                 i->id,
 125                                 i->sessions_by_seat_next ? ' ' : '\n');
 126                 }
 127
 128                 fputs("UIDS=", f);
 129                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 130                         fprintf(f,
 131                                 UID_FMT"%c",
 132                                 i->user->uid,
 133                                 i->sessions_by_seat_next ? ' ' : '\n');
 134         }
 135
 136         r = fflush_and_check(f);
 137         if (r < 0)
 138                 goto fail;
 139
 140         if (rename(temp_path, s->state_file) < 0) {
 141                 r = -errno;
 142                 goto fail;
 143         }
 144
 145         return 0;
 146
 147 fail:
 148         (void) unlink(s->state_file);
 149
 150         if (temp_path)
 151                 (void) unlink(temp_path);
 152
 153         return log_error_errno(r, "Failed to save seat data %s: %m", s->state_file);
 154 }
 155
 156 int seat_load(Seat *s) {
 157         assert(s);
 158
 159         /* There isn't actually anything to read here ... */
 160
 161         return 0;
 162 }
 163
 164 #if 0 /// UNNEEDED by elogind
 165 static int vt_allocate(unsigned int vtnr) {
 166         char p[sizeof("/dev/tty") + DECIMAL_STR_MAX(unsigned int)];
 167         _cleanup_close_ int fd = -1;
 168
 169         assert(vtnr >= 1);
 170
 171         xsprintf(p, "/dev/tty%u", vtnr);
 172         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 173         if (fd < 0)
 174                 return -errno;
 175
 176         return 0;
 177 }
 178
 179 int seat_preallocate_vts(Seat *s) {
 180         int r = 0;
 181         unsigned i;
 182
 183         assert(s);
 184         assert(s->manager);
 185
 186         log_debug("Preallocating VTs...");
 187
 188         if (s->manager->n_autovts <= 0)
 189                 return 0;
 190
 191         if (!seat_has_vts(s))
 192                 return 0;
 193
 194         for (i = 1; i <= s->manager->n_autovts; i++) {
 195                 int q;
 196
 197                 q = vt_allocate(i);
 198                 if (q < 0) {
 199                         log_error_errno(q, "Failed to preallocate VT %u: %m", i);
 200                         r = q;
 201                 }
 202         }
 203
 204         return r;
 205 }
 206 #endif // 0
 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->manager->udev,
 214                             s->id,
 215                             false,
 216                             !!old_active, old_active ? old_active->user->uid : 0,
 217                             !!s->active, s->active ? s->active->user->uid : 0);
 218
 219         if (r < 0)
 220                 log_error_errno(r, "Failed to apply ACLs: %m");
 221
 222         return r;
 223 }
 224
 225 int seat_set_active(Seat *s, Session *session) {
 226         Session *old_active;
 227
 228         assert(s);
 229         assert(!session || session->seat == s);
 230
 231         if (session == s->active)
 232                 return 0;
 233
 234         old_active = s->active;
 235         s->active = session;
 236
 237         if (old_active) {
 238                 session_device_pause_all(old_active);
 239                 session_send_changed(old_active, "Active", NULL);
 240         }
 241
 242         seat_apply_acls(s, old_active);
 243
 244         if (session && session->started) {
 245                 session_send_changed(session, "Active", NULL);
 246                 session_device_resume_all(session);
 247         }
 248
 249         if (!session || session->started)
 250                 seat_send_changed(s, "ActiveSession", NULL);
 251
 252         seat_save(s);
 253
 254         if (session) {
 255                 session_save(session);
 256                 user_save(session->user);
 257         }
 258
 259         if (old_active) {
 260                 session_save(old_active);
 261                 if (!session || session->user != old_active->user)
 262                         user_save(old_active->user);
 263         }
 264
 265         return 0;
 266 }
 267
 268 int seat_switch_to(Seat *s, unsigned int num) {
 269         /* Public session positions skip 0 (there is only F1-F12). Maybe it
 270          * will get reassigned in the future, so return error for now. */
 271         if (num == 0)
 272                 return -EINVAL;
 273
 274         if (num >= s->position_count || !s->positions[num]) {
 275                 /* allow switching to unused VTs to trigger auto-activate */
 276                 if (seat_has_vts(s) && num < 64)
 277                         return chvt(num);
 278
 279                 return -EINVAL;
 280         }
 281
 282         return session_activate(s->positions[num]);
 283 }
 284
 285 int seat_switch_to_next(Seat *s) {
 286         unsigned int start, i;
 287
 288         if (s->position_count == 0)
 289                 return -EINVAL;
 290
 291         start = 1;
 292         if (s->active && s->active->position > 0)
 293                 start = s->active->position;
 294
 295         for (i = start + 1; i < s->position_count; ++i)
 296                 if (s->positions[i])
 297                         return session_activate(s->positions[i]);
 298
 299         for (i = 1; i < start; ++i)
 300                 if (s->positions[i])
 301                         return session_activate(s->positions[i]);
 302
 303         return -EINVAL;
 304 }
 305
 306 int seat_switch_to_previous(Seat *s) {
 307         unsigned int start, i;
 308
 309         if (s->position_count == 0)
 310                 return -EINVAL;
 311
 312         start = 1;
 313         if (s->active && s->active->position > 0)
 314                 start = s->active->position;
 315
 316         for (i = start - 1; i > 0; --i)
 317                 if (s->positions[i])
 318                         return session_activate(s->positions[i]);
 319
 320         for (i = s->position_count - 1; i > start; --i)
 321                 if (s->positions[i])
 322                         return session_activate(s->positions[i]);
 323
 324         return -EINVAL;
 325 }
 326
 327 int seat_active_vt_changed(Seat *s, unsigned int vtnr) {
 328         Session *i, *new_active = NULL;
 329         int r;
 330
 331         assert(s);
 332         assert(vtnr >= 1);
 333
 334         if (!seat_has_vts(s))
 335                 return -EINVAL;
 336
 337         log_debug("VT changed to %u", vtnr);
 338
 339         /* we might have earlier closing sessions on the same VT, so try to
 340          * find a running one first */
 341         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 342                 if (i->vtnr == vtnr && !i->stopping) {
 343                         new_active = i;
 344                         break;
 345                 }
 346
 347         if (!new_active) {
 348                 /* no running one? then we can't decide which one is the
 349                  * active one, let the first one win */
 350                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 351                         if (i->vtnr == vtnr) {
 352                                 new_active = i;
 353                                 break;
 354                         }
 355         }
 356
 357         r = seat_set_active(s, new_active);
 358 #if 0 /// elogind does not spawn autovt
 359         manager_spawn_autovt(s->manager, vtnr);
 360 #endif // 0
 361
 362         return r;
 363 }
 364
 365 int seat_read_active_vt(Seat *s) {
 366         char t[64];
 367         ssize_t k;
 368         unsigned int vtnr;
 369         int r;
 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(-errno) : "EOF");
 382                 return k < 0 ? -errno : -EIO;
 383         }
 384
 385         t[k] = 0;
 386         truncate_nl(t);
 387
 388         if (!startswith(t, "tty")) {
 389                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 390                 return -EIO;
 391         }
 392
 393         r = safe_atou(t+3, &vtnr);
 394         if (r < 0)
 395                 return log_error_errno(r, "Failed to parse VT number \"%s\": %m", t+3);
 396
 397         if (!vtnr) {
 398                 log_error("VT number invalid: %s", t+3);
 399                 return -EIO;
 400         }
 401
 402         return seat_active_vt_changed(s, vtnr);
 403 }
 404
 405 int seat_start(Seat *s) {
 406         assert(s);
 407
 408         if (s->started)
 409                 return 0;
 410
 411         log_struct(LOG_INFO,
 412                    "MESSAGE_ID=" SD_MESSAGE_SEAT_START_STR,
 413                    "SEAT_ID=%s", s->id,
 414                    LOG_MESSAGE("New seat %s.", s->id));
 415
 416         /* Initialize VT magic stuff */
 417 #if 0 /// elogind does not support autospawning vts
 418         seat_preallocate_vts(s);
 419 #endif // 0
 420
 421         /* Read current VT */
 422         seat_read_active_vt(s);
 423
 424         s->started = true;
 425
 426         /* Save seat data */
 427         seat_save(s);
 428
 429         seat_send_signal(s, true);
 430
 431         return 0;
 432 }
 433
 434 int seat_stop(Seat *s, bool force) {
 435         int r = 0;
 436
 437         assert(s);
 438
 439         if (s->started)
 440                 log_struct(LOG_INFO,
 441                            "MESSAGE_ID=" SD_MESSAGE_SEAT_STOP_STR,
 442                            "SEAT_ID=%s", s->id,
 443                            LOG_MESSAGE("Removed seat %s.", s->id));
 444
 445         seat_stop_sessions(s, force);
 446
 447         unlink(s->state_file);
 448         seat_add_to_gc_queue(s);
 449
 450         if (s->started)
 451                 seat_send_signal(s, false);
 452
 453         s->started = false;
 454
 455         return r;
 456 }
 457
 458 int seat_stop_sessions(Seat *s, bool force) {
 459         Session *session;
 460         int r = 0, k;
 461
 462         assert(s);
 463
 464         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 465                 k = session_stop(session, force);
 466                 if (k < 0)
 467                         r = k;
 468         }
 469
 470         return r;
 471 }
 472
 473 void seat_evict_position(Seat *s, Session *session) {
 474         Session *iter;
 475         unsigned int pos = session->position;
 476
 477         session->position = 0;
 478
 479         if (pos == 0)
 480                 return;
 481
 482         if (pos < s->position_count && 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
 497 void seat_claim_position(Seat *s, Session *session, unsigned int pos) {
 498         /* with VTs, the position is always the same as the VTnr */
 499         if (seat_has_vts(s))
 500                 pos = session->vtnr;
 501
 502         if (!GREEDY_REALLOC0(s->positions, s->position_count, pos + 1))
 503                 return;
 504
 505         seat_evict_position(s, session);
 506
 507         session->position = pos;
 508         if (pos > 0)
 509                 s->positions[pos] = session;
 510 }
 511
 512 static void seat_assign_position(Seat *s, Session *session) {
 513         unsigned int pos;
 514
 515         if (session->position > 0)
 516                 return;
 517
 518         for (pos = 1; pos < s->position_count; ++pos)
 519                 if (!s->positions[pos])
 520                         break;
 521
 522         seat_claim_position(s, session, pos);
 523 }
 524
 525 int seat_attach_session(Seat *s, Session *session) {
 526         assert(s);
 527         assert(session);
 528         assert(!session->seat);
 529
 530         if (!seat_has_vts(s) != !session->vtnr)
 531                 return -EINVAL;
 532
 533         session->seat = s;
 534         LIST_PREPEND(sessions_by_seat, s->sessions, session);
 535         seat_assign_position(s, session);
 536
 537         /* On seats with VTs, the VT logic defines which session is active. On
 538          * seats without VTs, we automatically activate new sessions. */
 539         if (!seat_has_vts(s))
 540                 seat_set_active(s, session);
 541
 542         return 0;
 543 }
 544
 545 void seat_complete_switch(Seat *s) {
 546         Session *session;
 547
 548         assert(s);
 549
 550         /* if no session-switch is pending or if it got canceled, do nothing */
 551         if (!s->pending_switch)
 552                 return;
 553
 554         session = TAKE_PTR(s->pending_switch);
 555
 556         seat_set_active(s, session);
 557 }
 558
 559 bool seat_has_vts(Seat *s) {
 560         assert(s);
 561
 562         return seat_is_seat0(s) && s->manager->console_active_fd >= 0;
 563 }
 564
 565 bool seat_is_seat0(Seat *s) {
 566         assert(s);
 567
 568         return s->manager->seat0 == s;
 569 }
 570
 571 bool seat_can_multi_session(Seat *s) {
 572         assert(s);
 573
 574         return seat_has_vts(s);
 575 }
 576
 577 bool seat_can_tty(Seat *s) {
 578         assert(s);
 579
 580         return seat_has_vts(s);
 581 }
 582
 583 bool seat_has_master_device(Seat *s) {
 584         assert(s);
 585
 586         /* device list is ordered by "master" flag */
 587         return !!s->devices && s->devices->master;
 588 }
 589
 590 bool seat_can_graphical(Seat *s) {
 591         assert(s);
 592
 593         return seat_has_master_device(s);
 594 }
 595
 596 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 597         Session *session;
 598         bool idle_hint = true;
 599         dual_timestamp ts = DUAL_TIMESTAMP_NULL;
 600
 601         assert(s);
 602
 603         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 604                 dual_timestamp k;
 605                 int ih;
 606
 607                 ih = session_get_idle_hint(session, &k);
 608                 if (ih < 0)
 609                         return ih;
 610
 611                 if (!ih) {
 612                         if (!idle_hint) {
 613                                 if (k.monotonic > ts.monotonic)
 614                                         ts = k;
 615                         } else {
 616                                 idle_hint = false;
 617                                 ts = k;
 618                         }
 619                 } else if (idle_hint) {
 620
 621                         if (k.monotonic > ts.monotonic)
 622                                 ts = k;
 623                 }
 624         }
 625
 626         if (t)
 627                 *t = ts;
 628
 629         return idle_hint;
 630 }
 631
 632 bool seat_may_gc(Seat *s, bool drop_not_started) {
 633         assert(s);
 634
 635         if (drop_not_started && !s->started)
 636                 return true;
 637
 638         if (seat_is_seat0(s))
 639                 return false;
 640
 641         return !seat_has_master_device(s);
 642 }
 643
 644 void seat_add_to_gc_queue(Seat *s) {
 645         assert(s);
 646
 647         if (s->in_gc_queue)
 648                 return;
 649
 650         LIST_PREPEND(gc_queue, s->manager->seat_gc_queue, s);
 651         s->in_gc_queue = true;
 652 }
 653
 654 static bool seat_name_valid_char(char c) {
 655         return
 656                 (c >= 'a' && c <= 'z') ||
 657                 (c >= 'A' && c <= 'Z') ||
 658                 (c >= '0' && c <= '9') ||
 659                 IN_SET(c, '-', '_');
 660 }
 661
 662 bool seat_name_is_valid(const char *name) {
 663         const char *p;
 664
 665         assert(name);
 666
 667         if (!startswith(name, "seat"))
 668                 return false;
 669
 670         if (!name[4])
 671                 return false;
 672
 673         for (p = name; *p; p++)
 674                 if (!seat_name_valid_char(*p))
 675                         return false;
 676
 677         if (strlen(name) > 255)
 678                 return false;
 679
 680         return true;
 681 }