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 static int vt_allocate(unsigned int vtnr) {
 165         char p[sizeof("/dev/tty") + DECIMAL_STR_MAX(unsigned int)];
 166         _cleanup_close_ int fd = -1;
 167
 168         assert(vtnr >= 1);
 169
 170         xsprintf(p, "/dev/tty%u", vtnr);
 171         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 172         if (fd < 0)
 173                 return -errno;
 174
 175         return 0;
 176 }
 177
 178 int seat_preallocate_vts(Seat *s) {
 179         int r = 0;
 180         unsigned i;
 181
 182         assert(s);
 183         assert(s->manager);
 184
 185         log_debug("Preallocating VTs...");
 186
 187         if (s->manager->n_autovts <= 0)
 188                 return 0;
 189
 190         if (!seat_has_vts(s))
 191                 return 0;
 192
 193         for (i = 1; i <= s->manager->n_autovts; i++) {
 194                 int q;
 195
 196                 q = vt_allocate(i);
 197                 if (q < 0) {
 198                         log_error_errno(q, "Failed to preallocate VT %u: %m", i);
 199                         r = q;
 200                 }
 201         }
 202
 203         return r;
 204 }
 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         manager_spawn_autovt(s->manager, vtnr);
 357
 358         return r;
 359 }
 360
 361 int seat_read_active_vt(Seat *s) {
 362         char t[64];
 363         ssize_t k;
 364         unsigned int vtnr;
 365         int r;
 366
 367         assert(s);
 368
 369         if (!seat_has_vts(s))
 370                 return 0;
 371
 372         if (lseek(s->manager->console_active_fd, SEEK_SET, 0) < 0)
 373                 return log_error_errno(errno, "lseek on console_active_fd failed: %m");
 374
 375         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 376         if (k <= 0) {
 377                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 378                 return k < 0 ? -errno : -EIO;
 379         }
 380
 381         t[k] = 0;
 382         truncate_nl(t);
 383
 384         if (!startswith(t, "tty")) {
 385                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 386                 return -EIO;
 387         }
 388
 389         r = safe_atou(t+3, &vtnr);
 390         if (r < 0)
 391                 return log_error_errno(r, "Failed to parse VT number \"%s\": %m", t+3);
 392
 393         if (!vtnr) {
 394                 log_error("VT number invalid: %s", t+3);
 395                 return -EIO;
 396         }
 397
 398         return seat_active_vt_changed(s, vtnr);
 399 }
 400
 401 int seat_start(Seat *s) {
 402         assert(s);
 403
 404         if (s->started)
 405                 return 0;
 406
 407         log_struct(LOG_INFO,
 408                    "MESSAGE_ID=" SD_MESSAGE_SEAT_START_STR,
 409                    "SEAT_ID=%s", s->id,
 410                    LOG_MESSAGE("New seat %s.", s->id));
 411
 412         /* Initialize VT magic stuff */
 413         seat_preallocate_vts(s);
 414
 415         /* Read current VT */
 416         seat_read_active_vt(s);
 417
 418         s->started = true;
 419
 420         /* Save seat data */
 421         seat_save(s);
 422
 423         seat_send_signal(s, true);
 424
 425         return 0;
 426 }
 427
 428 int seat_stop(Seat *s, bool force) {
 429         int r = 0;
 430
 431         assert(s);
 432
 433         if (s->started)
 434                 log_struct(LOG_INFO,
 435                            "MESSAGE_ID=" SD_MESSAGE_SEAT_STOP_STR,
 436                            "SEAT_ID=%s", s->id,
 437                            LOG_MESSAGE("Removed seat %s.", s->id));
 438
 439         seat_stop_sessions(s, force);
 440
 441         unlink(s->state_file);
 442         seat_add_to_gc_queue(s);
 443
 444         if (s->started)
 445                 seat_send_signal(s, false);
 446
 447         s->started = false;
 448
 449         return r;
 450 }
 451
 452 int seat_stop_sessions(Seat *s, bool force) {
 453         Session *session;
 454         int r = 0, k;
 455
 456         assert(s);
 457
 458         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 459                 k = session_stop(session, force);
 460                 if (k < 0)
 461                         r = k;
 462         }
 463
 464         return r;
 465 }
 466
 467 void seat_evict_position(Seat *s, Session *session) {
 468         Session *iter;
 469         unsigned int pos = session->position;
 470
 471         session->position = 0;
 472
 473         if (pos == 0)
 474                 return;
 475
 476         if (pos < s->position_count && s->positions[pos] == session) {
 477                 s->positions[pos] = NULL;
 478
 479                 /* There might be another session claiming the same
 480                  * position (eg., during gdm->session transition), so let's look
 481                  * for it and set it on the free slot. */
 482                 LIST_FOREACH(sessions_by_seat, iter, s->sessions) {
 483                         if (iter->position == pos && session_get_state(iter) != SESSION_CLOSING) {
 484                                 s->positions[pos] = iter;
 485                                 break;
 486                         }
 487                 }
 488         }
 489 }
 490
 491 void seat_claim_position(Seat *s, Session *session, unsigned int pos) {
 492         /* with VTs, the position is always the same as the VTnr */
 493         if (seat_has_vts(s))
 494                 pos = session->vtnr;
 495
 496         if (!GREEDY_REALLOC0(s->positions, s->position_count, pos + 1))
 497                 return;
 498
 499         seat_evict_position(s, session);
 500
 501         session->position = pos;
 502         if (pos > 0)
 503                 s->positions[pos] = session;
 504 }
 505
 506 static void seat_assign_position(Seat *s, Session *session) {
 507         unsigned int pos;
 508
 509         if (session->position > 0)
 510                 return;
 511
 512         for (pos = 1; pos < s->position_count; ++pos)
 513                 if (!s->positions[pos])
 514                         break;
 515
 516         seat_claim_position(s, session, pos);
 517 }
 518
 519 int seat_attach_session(Seat *s, Session *session) {
 520         assert(s);
 521         assert(session);
 522         assert(!session->seat);
 523
 524         if (!seat_has_vts(s) != !session->vtnr)
 525                 return -EINVAL;
 526
 527         session->seat = s;
 528         LIST_PREPEND(sessions_by_seat, s->sessions, session);
 529         seat_assign_position(s, session);
 530
 531         /* On seats with VTs, the VT logic defines which session is active. On
 532          * seats without VTs, we automatically activate new sessions. */
 533         if (!seat_has_vts(s))
 534                 seat_set_active(s, session);
 535
 536         return 0;
 537 }
 538
 539 void seat_complete_switch(Seat *s) {
 540         Session *session;
 541
 542         assert(s);
 543
 544         /* if no session-switch is pending or if it got canceled, do nothing */
 545         if (!s->pending_switch)
 546                 return;
 547
 548         session = TAKE_PTR(s->pending_switch);
 549
 550         seat_set_active(s, session);
 551 }
 552
 553 bool seat_has_vts(Seat *s) {
 554         assert(s);
 555
 556         return seat_is_seat0(s) && s->manager->console_active_fd >= 0;
 557 }
 558
 559 bool seat_is_seat0(Seat *s) {
 560         assert(s);
 561
 562         return s->manager->seat0 == s;
 563 }
 564
 565 bool seat_can_multi_session(Seat *s) {
 566         assert(s);
 567
 568         return seat_has_vts(s);
 569 }
 570
 571 bool seat_can_tty(Seat *s) {
 572         assert(s);
 573
 574         return seat_has_vts(s);
 575 }
 576
 577 bool seat_has_master_device(Seat *s) {
 578         assert(s);
 579
 580         /* device list is ordered by "master" flag */
 581         return !!s->devices && s->devices->master;
 582 }
 583
 584 bool seat_can_graphical(Seat *s) {
 585         assert(s);
 586
 587         return seat_has_master_device(s);
 588 }
 589
 590 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 591         Session *session;
 592         bool idle_hint = true;
 593         dual_timestamp ts = DUAL_TIMESTAMP_NULL;
 594
 595         assert(s);
 596
 597         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 598                 dual_timestamp k;
 599                 int ih;
 600
 601                 ih = session_get_idle_hint(session, &k);
 602                 if (ih < 0)
 603                         return ih;
 604
 605                 if (!ih) {
 606                         if (!idle_hint) {
 607                                 if (k.monotonic > ts.monotonic)
 608                                         ts = k;
 609                         } else {
 610                                 idle_hint = false;
 611                                 ts = k;
 612                         }
 613                 } else if (idle_hint) {
 614
 615                         if (k.monotonic > ts.monotonic)
 616                                 ts = k;
 617                 }
 618         }
 619
 620         if (t)
 621                 *t = ts;
 622
 623         return idle_hint;
 624 }
 625
 626 bool seat_may_gc(Seat *s, bool drop_not_started) {
 627         assert(s);
 628
 629         if (drop_not_started && !s->started)
 630                 return true;
 631
 632         if (seat_is_seat0(s))
 633                 return false;
 634
 635         return !seat_has_master_device(s);
 636 }
 637
 638 void seat_add_to_gc_queue(Seat *s) {
 639         assert(s);
 640
 641         if (s->in_gc_queue)
 642                 return;
 643
 644         LIST_PREPEND(gc_queue, s->manager->seat_gc_queue, s);
 645         s->in_gc_queue = true;
 646 }
 647
 648 static bool seat_name_valid_char(char c) {
 649         return
 650                 (c >= 'a' && c <= 'z') ||
 651                 (c >= 'A' && c <= 'Z') ||
 652                 (c >= '0' && c <= '9') ||
 653                 IN_SET(c, '-', '_');
 654 }
 655
 656 bool seat_name_is_valid(const char *name) {
 657         const char *p;
 658
 659         assert(name);
 660
 661         if (!startswith(name, "seat"))
 662                 return false;
 663
 664         if (!name[4])
 665                 return false;
 666
 667         for (p = name; *p; p++)
 668                 if (!seat_name_valid_char(*p))
 669                         return false;
 670
 671         if (strlen(name) > 255)
 672                 return false;
 673
 674         return true;
 675 }