src/login/logind-seat.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright 2011 Lennart Poettering
   4 ***/
   5
   6 #include <errno.h>
   7 #include <fcntl.h>
   8 #include <stdio_ext.h>
   9 #include <string.h>
  10 #include <unistd.h>
  11
  12 #include "sd-messages.h"
  13
  14 #include "alloc-util.h"
  15 #include "fd-util.h"
  16 #include "fileio.h"
  17 #include "format-util.h"
  18 #include "logind-acl.h"
  19 #include "logind-seat.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 "util.h"
  26
  27 Seat *seat_new(Manager *m, const char *id) {
  28         Seat *s;
  29
  30         assert(m);
  31         assert(id);
  32
  33         s = new0(Seat, 1);
  34         if (!s)
  35                 return NULL;
  36
  37         s->state_file = strappend("/run/systemd/seats/", id);
  38         if (!s->state_file)
  39                 return mfree(s);
  40
  41         s->id = basename(s->state_file);
  42         s->manager = m;
  43
  44         if (hashmap_put(m->seats, s->id, s) < 0) {
  45                 free(s->state_file);
  46                 return mfree(s);
  47         }
  48
  49         return s;
  50 }
  51
  52 void seat_free(Seat *s) {
  53         assert(s);
  54
  55         if (s->in_gc_queue)
  56                 LIST_REMOVE(gc_queue, s->manager->seat_gc_queue, s);
  57
  58         while (s->sessions)
  59                 session_free(s->sessions);
  60
  61         assert(!s->active);
  62
  63         while (s->devices)
  64                 device_free(s->devices);
  65
  66         hashmap_remove(s->manager->seats, s->id);
  67
  68         free(s->positions);
  69         free(s->state_file);
  70         free(s);
  71 }
  72
  73 int seat_save(Seat *s) {
  74         _cleanup_free_ char *temp_path = NULL;
  75         _cleanup_fclose_ FILE *f = NULL;
  76         int r;
  77
  78         assert(s);
  79
  80         if (!s->started)
  81                 return 0;
  82
  83         r = mkdir_safe_label("/run/systemd/seats", 0755, 0, 0, MKDIR_WARN_MODE);
  84         if (r < 0)
  85                 goto fail;
  86
  87         r = fopen_temporary(s->state_file, &f, &temp_path);
  88         if (r < 0)
  89                 goto fail;
  90
  91         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
  92         (void) fchmod(fileno(f), 0644);
  93
  94         fprintf(f,
  95                 "# This is private data. Do not parse.\n"
  96                 "IS_SEAT0=%i\n"
  97                 "CAN_MULTI_SESSION=%i\n"
  98                 "CAN_TTY=%i\n"
  99                 "CAN_GRAPHICAL=%i\n",
 100                 seat_is_seat0(s),
 101                 seat_can_multi_session(s),
 102                 seat_can_tty(s),
 103                 seat_can_graphical(s));
 104
 105         if (s->active) {
 106                 assert(s->active->user);
 107
 108                 fprintf(f,
 109                         "ACTIVE=%s\n"
 110                         "ACTIVE_UID="UID_FMT"\n",
 111                         s->active->id,
 112                         s->active->user->uid);
 113         }
 114
 115         if (s->sessions) {
 116                 Session *i;
 117
 118                 fputs("SESSIONS=", f);
 119                 LIST_FOREACH(sessions_by_seat, i, s->sessions) {
 120                         fprintf(f,
 121                                 "%s%c",
 122                                 i->id,
 123                                 i->sessions_by_seat_next ? ' ' : '\n');
 124                 }
 125
 126                 fputs("UIDS=", f);
 127                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 128                         fprintf(f,
 129                                 UID_FMT"%c",
 130                                 i->user->uid,
 131                                 i->sessions_by_seat_next ? ' ' : '\n');
 132         }
 133
 134         r = fflush_and_check(f);
 135         if (r < 0)
 136                 goto fail;
 137
 138         if (rename(temp_path, s->state_file) < 0) {
 139                 r = -errno;
 140                 goto fail;
 141         }
 142
 143         return 0;
 144
 145 fail:
 146         (void) unlink(s->state_file);
 147
 148         if (temp_path)
 149                 (void) unlink(temp_path);
 150
 151         return log_error_errno(r, "Failed to save seat data %s: %m", s->state_file);
 152 }
 153
 154 int seat_load(Seat *s) {
 155         assert(s);
 156
 157         /* There isn't actually anything to read here ... */
 158
 159         return 0;
 160 }
 161
 162 #if 0 /// UNNEEDED by elogind
 163 static int vt_allocate(unsigned int vtnr) {
 164         char p[sizeof("/dev/tty") + DECIMAL_STR_MAX(unsigned int)];
 165         _cleanup_close_ int fd = -1;
 166
 167         assert(vtnr >= 1);
 168
 169         xsprintf(p, "/dev/tty%u", vtnr);
 170         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 171         if (fd < 0)
 172                 return -errno;
 173
 174         return 0;
 175 }
 176
 177 int seat_preallocate_vts(Seat *s) {
 178         int r = 0;
 179         unsigned i;
 180
 181         assert(s);
 182         assert(s->manager);
 183
 184         log_debug("Preallocating VTs...");
 185
 186         if (s->manager->n_autovts <= 0)
 187                 return 0;
 188
 189         if (!seat_has_vts(s))
 190                 return 0;
 191
 192         for (i = 1; i <= s->manager->n_autovts; i++) {
 193                 int q;
 194
 195                 q = vt_allocate(i);
 196                 if (q < 0) {
 197                         log_error_errno(q, "Failed to preallocate VT %u: %m", i);
 198                         r = q;
 199                 }
 200         }
 201
 202         return r;
 203 }
 204 #endif // 0
 205
 206 int seat_apply_acls(Seat *s, Session *old_active) {
 207         int r;
 208
 209         assert(s);
 210
 211         r = devnode_acl_all(s->manager->udev,
 212                             s->id,
 213                             false,
 214                             !!old_active, old_active ? old_active->user->uid : 0,
 215                             !!s->active, s->active ? s->active->user->uid : 0);
 216
 217         if (r < 0)
 218                 log_error_errno(r, "Failed to apply ACLs: %m");
 219
 220         return r;
 221 }
 222
 223 int seat_set_active(Seat *s, Session *session) {
 224         Session *old_active;
 225
 226         assert(s);
 227         assert(!session || session->seat == s);
 228
 229         if (session == s->active)
 230                 return 0;
 231
 232         old_active = s->active;
 233         s->active = session;
 234
 235         if (old_active) {
 236                 session_device_pause_all(old_active);
 237                 session_send_changed(old_active, "Active", NULL);
 238         }
 239
 240         seat_apply_acls(s, old_active);
 241
 242         if (session && session->started) {
 243                 session_send_changed(session, "Active", NULL);
 244                 session_device_resume_all(session);
 245         }
 246
 247         if (!session || session->started)
 248                 seat_send_changed(s, "ActiveSession", NULL);
 249
 250         seat_save(s);
 251
 252         if (session) {
 253                 session_save(session);
 254                 user_save(session->user);
 255         }
 256
 257         if (old_active) {
 258                 session_save(old_active);
 259                 if (!session || session->user != old_active->user)
 260                         user_save(old_active->user);
 261         }
 262
 263         return 0;
 264 }
 265
 266 int seat_switch_to(Seat *s, unsigned int num) {
 267         /* Public session positions skip 0 (there is only F1-F12). Maybe it
 268          * will get reassigned in the future, so return error for now. */
 269         if (num == 0)
 270                 return -EINVAL;
 271
 272         if (num >= s->position_count || !s->positions[num]) {
 273                 /* allow switching to unused VTs to trigger auto-activate */
 274                 if (seat_has_vts(s) && num < 64)
 275                         return chvt(num);
 276
 277                 return -EINVAL;
 278         }
 279
 280         return session_activate(s->positions[num]);
 281 }
 282
 283 int seat_switch_to_next(Seat *s) {
 284         unsigned int start, i;
 285
 286         if (s->position_count == 0)
 287                 return -EINVAL;
 288
 289         start = 1;
 290         if (s->active && s->active->position > 0)
 291                 start = s->active->position;
 292
 293         for (i = start + 1; i < s->position_count; ++i)
 294                 if (s->positions[i])
 295                         return session_activate(s->positions[i]);
 296
 297         for (i = 1; i < start; ++i)
 298                 if (s->positions[i])
 299                         return session_activate(s->positions[i]);
 300
 301         return -EINVAL;
 302 }
 303
 304 int seat_switch_to_previous(Seat *s) {
 305         unsigned int start, i;
 306
 307         if (s->position_count == 0)
 308                 return -EINVAL;
 309
 310         start = 1;
 311         if (s->active && s->active->position > 0)
 312                 start = s->active->position;
 313
 314         for (i = start - 1; i > 0; --i)
 315                 if (s->positions[i])
 316                         return session_activate(s->positions[i]);
 317
 318         for (i = s->position_count - 1; i > start; --i)
 319                 if (s->positions[i])
 320                         return session_activate(s->positions[i]);
 321
 322         return -EINVAL;
 323 }
 324
 325 int seat_active_vt_changed(Seat *s, unsigned int vtnr) {
 326         Session *i, *new_active = NULL;
 327         int r;
 328
 329         assert(s);
 330         assert(vtnr >= 1);
 331
 332         if (!seat_has_vts(s))
 333                 return -EINVAL;
 334
 335         log_debug("VT changed to %u", vtnr);
 336
 337         /* we might have earlier closing sessions on the same VT, so try to
 338          * find a running one first */
 339         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 340                 if (i->vtnr == vtnr && !i->stopping) {
 341                         new_active = i;
 342                         break;
 343                 }
 344
 345         if (!new_active) {
 346                 /* no running one? then we can't decide which one is the
 347                  * active one, let the first one win */
 348                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 349                         if (i->vtnr == vtnr) {
 350                                 new_active = i;
 351                                 break;
 352                         }
 353         }
 354
 355         r = seat_set_active(s, new_active);
 356 #if 0 /// elogind does not spawn autovt
 357         manager_spawn_autovt(s->manager, vtnr);
 358 #endif // 0
 359
 360         return r;
 361 }
 362
 363 int seat_read_active_vt(Seat *s) {
 364         char t[64];
 365         ssize_t k;
 366         unsigned int vtnr;
 367         int r;
 368
 369         assert(s);
 370
 371         if (!seat_has_vts(s))
 372                 return 0;
 373
 374         if (lseek(s->manager->console_active_fd, SEEK_SET, 0) < 0)
 375                 return log_error_errno(errno, "lseek on console_active_fd failed: %m");
 376
 377         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 378         if (k <= 0) {
 379                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 380                 return k < 0 ? -errno : -EIO;
 381         }
 382
 383         t[k] = 0;
 384         truncate_nl(t);
 385
 386         if (!startswith(t, "tty")) {
 387                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 388                 return -EIO;
 389         }
 390
 391         r = safe_atou(t+3, &vtnr);
 392         if (r < 0)
 393                 return log_error_errno(r, "Failed to parse VT number \"%s\": %m", t+3);
 394
 395         if (!vtnr) {
 396                 log_error("VT number invalid: %s", t+3);
 397                 return -EIO;
 398         }
 399
 400         return seat_active_vt_changed(s, vtnr);
 401 }
 402
 403 int seat_start(Seat *s) {
 404         assert(s);
 405
 406         if (s->started)
 407                 return 0;
 408
 409         log_struct(LOG_INFO,
 410                    "MESSAGE_ID=" SD_MESSAGE_SEAT_START_STR,
 411                    "SEAT_ID=%s", s->id,
 412                    LOG_MESSAGE("New seat %s.", s->id));
 413
 414         /* Initialize VT magic stuff */
 415 #if 0 /// elogind does not support autospawning vts
 416         seat_preallocate_vts(s);
 417 #endif // 0
 418
 419         /* Read current VT */
 420         seat_read_active_vt(s);
 421
 422         s->started = true;
 423
 424         /* Save seat data */
 425         seat_save(s);
 426
 427         seat_send_signal(s, true);
 428
 429         return 0;
 430 }
 431
 432 int seat_stop(Seat *s, bool force) {
 433         int r = 0;
 434
 435         assert(s);
 436
 437         if (s->started)
 438                 log_struct(LOG_INFO,
 439                            "MESSAGE_ID=" SD_MESSAGE_SEAT_STOP_STR,
 440                            "SEAT_ID=%s", s->id,
 441                            LOG_MESSAGE("Removed seat %s.", s->id));
 442
 443         seat_stop_sessions(s, force);
 444
 445         unlink(s->state_file);
 446         seat_add_to_gc_queue(s);
 447
 448         if (s->started)
 449                 seat_send_signal(s, false);
 450
 451         s->started = false;
 452
 453         return r;
 454 }
 455
 456 int seat_stop_sessions(Seat *s, bool force) {
 457         Session *session;
 458         int r = 0, k;
 459
 460         assert(s);
 461
 462         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 463                 k = session_stop(session, force);
 464                 if (k < 0)
 465                         r = k;
 466         }
 467
 468         return r;
 469 }
 470
 471 void seat_evict_position(Seat *s, Session *session) {
 472         Session *iter;
 473         unsigned int pos = session->position;
 474
 475         session->position = 0;
 476
 477         if (pos == 0)
 478                 return;
 479
 480         if (pos < s->position_count && s->positions[pos] == session) {
 481                 s->positions[pos] = NULL;
 482
 483                 /* There might be another session claiming the same
 484                  * position (eg., during gdm->session transition), so let's look
 485                  * for it and set it on the free slot. */
 486                 LIST_FOREACH(sessions_by_seat, iter, s->sessions) {
 487                         if (iter->position == pos && session_get_state(iter) != SESSION_CLOSING) {
 488                                 s->positions[pos] = iter;
 489                                 break;
 490                         }
 491                 }
 492         }
 493 }
 494
 495 void seat_claim_position(Seat *s, Session *session, unsigned int pos) {
 496         /* with VTs, the position is always the same as the VTnr */
 497         if (seat_has_vts(s))
 498                 pos = session->vtnr;
 499
 500         if (!GREEDY_REALLOC0(s->positions, s->position_count, pos + 1))
 501                 return;
 502
 503         seat_evict_position(s, session);
 504
 505         session->position = pos;
 506         if (pos > 0)
 507                 s->positions[pos] = session;
 508 }
 509
 510 static void seat_assign_position(Seat *s, Session *session) {
 511         unsigned int pos;
 512
 513         if (session->position > 0)
 514                 return;
 515
 516         for (pos = 1; pos < s->position_count; ++pos)
 517                 if (!s->positions[pos])
 518                         break;
 519
 520         seat_claim_position(s, session, pos);
 521 }
 522
 523 int seat_attach_session(Seat *s, Session *session) {
 524         assert(s);
 525         assert(session);
 526         assert(!session->seat);
 527
 528         if (!seat_has_vts(s) != !session->vtnr)
 529                 return -EINVAL;
 530
 531         session->seat = s;
 532         LIST_PREPEND(sessions_by_seat, s->sessions, session);
 533         seat_assign_position(s, session);
 534
 535         /* On seats with VTs, the VT logic defines which session is active. On
 536          * seats without VTs, we automatically activate new sessions. */
 537         if (!seat_has_vts(s))
 538                 seat_set_active(s, session);
 539
 540         return 0;
 541 }
 542
 543 void seat_complete_switch(Seat *s) {
 544         Session *session;
 545
 546         assert(s);
 547
 548         /* if no session-switch is pending or if it got canceled, do nothing */
 549         if (!s->pending_switch)
 550                 return;
 551
 552         session = TAKE_PTR(s->pending_switch);
 553
 554         seat_set_active(s, session);
 555 }
 556
 557 bool seat_has_vts(Seat *s) {
 558         assert(s);
 559
 560         return seat_is_seat0(s) && s->manager->console_active_fd >= 0;
 561 }
 562
 563 bool seat_is_seat0(Seat *s) {
 564         assert(s);
 565
 566         return s->manager->seat0 == s;
 567 }
 568
 569 bool seat_can_multi_session(Seat *s) {
 570         assert(s);
 571
 572         return seat_has_vts(s);
 573 }
 574
 575 bool seat_can_tty(Seat *s) {
 576         assert(s);
 577
 578         return seat_has_vts(s);
 579 }
 580
 581 bool seat_has_master_device(Seat *s) {
 582         assert(s);
 583
 584         /* device list is ordered by "master" flag */
 585         return !!s->devices && s->devices->master;
 586 }
 587
 588 bool seat_can_graphical(Seat *s) {
 589         assert(s);
 590
 591         return seat_has_master_device(s);
 592 }
 593
 594 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 595         Session *session;
 596         bool idle_hint = true;
 597         dual_timestamp ts = DUAL_TIMESTAMP_NULL;
 598
 599         assert(s);
 600
 601         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 602                 dual_timestamp k;
 603                 int ih;
 604
 605                 ih = session_get_idle_hint(session, &k);
 606                 if (ih < 0)
 607                         return ih;
 608
 609                 if (!ih) {
 610                         if (!idle_hint) {
 611                                 if (k.monotonic > ts.monotonic)
 612                                         ts = k;
 613                         } else {
 614                                 idle_hint = false;
 615                                 ts = k;
 616                         }
 617                 } else if (idle_hint) {
 618
 619                         if (k.monotonic > ts.monotonic)
 620                                 ts = k;
 621                 }
 622         }
 623
 624         if (t)
 625                 *t = ts;
 626
 627         return idle_hint;
 628 }
 629
 630 bool seat_may_gc(Seat *s, bool drop_not_started) {
 631         assert(s);
 632
 633         if (drop_not_started && !s->started)
 634                 return true;
 635
 636         if (seat_is_seat0(s))
 637                 return false;
 638
 639         return !seat_has_master_device(s);
 640 }
 641
 642 void seat_add_to_gc_queue(Seat *s) {
 643         assert(s);
 644
 645         if (s->in_gc_queue)
 646                 return;
 647
 648         LIST_PREPEND(gc_queue, s->manager->seat_gc_queue, s);
 649         s->in_gc_queue = true;
 650 }
 651
 652 static bool seat_name_valid_char(char c) {
 653         return
 654                 (c >= 'a' && c <= 'z') ||
 655                 (c >= 'A' && c <= 'Z') ||
 656                 (c >= '0' && c <= '9') ||
 657                 IN_SET(c, '-', '_');
 658 }
 659
 660 bool seat_name_is_valid(const char *name) {
 661         const char *p;
 662
 663         assert(name);
 664
 665         if (!startswith(name, "seat"))
 666                 return false;
 667
 668         if (!name[4])
 669                 return false;
 670
 671         for (p = name; *p; p++)
 672                 if (!seat_name_valid_char(*p))
 673                         return false;
 674
 675         if (strlen(name) > 255)
 676                 return false;
 677
 678         return true;
 679 }