src/login/logind-seat.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2011 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24
  25 #include "sd-messages.h"
  26
  27 #include "alloc-util.h"
  28 #include "fd-util.h"
  29 #include "fileio.h"
  30 #include "formats-util.h"
  31 #include "logind-acl.h"
  32 #include "logind-seat.h"
  33 #include "mkdir.h"
  34 #include "parse-util.h"
  35 #include "stdio-util.h"
  36 #include "string-util.h"
  37 #include "terminal-util.h"
  38 #include "util.h"
  39
  40 Seat *seat_new(Manager *m, const char *id) {
  41         Seat *s;
  42
  43         assert(m);
  44         assert(id);
  45
  46         s = new0(Seat, 1);
  47         if (!s)
  48                 return NULL;
  49
  50         s->state_file = strappend("/run/systemd/seats/", id);
  51         if (!s->state_file)
  52                 return mfree(s);
  53
  54         s->id = basename(s->state_file);
  55         s->manager = m;
  56
  57         if (hashmap_put(m->seats, s->id, s) < 0) {
  58                 free(s->state_file);
  59                 return mfree(s);
  60         }
  61
  62         return s;
  63 }
  64
  65 void seat_free(Seat *s) {
  66         assert(s);
  67
  68         if (s->in_gc_queue)
  69                 LIST_REMOVE(gc_queue, s->manager->seat_gc_queue, s);
  70
  71         while (s->sessions)
  72                 session_free(s->sessions);
  73
  74         assert(!s->active);
  75
  76         while (s->devices)
  77                 device_free(s->devices);
  78
  79         hashmap_remove(s->manager->seats, s->id);
  80
  81         free(s->positions);
  82         free(s->state_file);
  83         free(s);
  84 }
  85
  86 int seat_save(Seat *s) {
  87         _cleanup_free_ char *temp_path = NULL;
  88         _cleanup_fclose_ FILE *f = NULL;
  89         int r;
  90
  91         assert(s);
  92
  93         if (!s->started)
  94                 return 0;
  95
  96         r = mkdir_safe_label("/run/systemd/seats", 0755, 0, 0);
  97         if (r < 0)
  98                 goto fail;
  99
 100         r = fopen_temporary(s->state_file, &f, &temp_path);
 101         if (r < 0)
 102                 goto fail;
 103
 104         fchmod(fileno(f), 0644);
 105
 106         fprintf(f,
 107                 "# This is private data. Do not parse.\n"
 108                 "IS_SEAT0=%i\n"
 109                 "CAN_MULTI_SESSION=%i\n"
 110                 "CAN_TTY=%i\n"
 111                 "CAN_GRAPHICAL=%i\n",
 112                 seat_is_seat0(s),
 113                 seat_can_multi_session(s),
 114                 seat_can_tty(s),
 115                 seat_can_graphical(s));
 116
 117         if (s->active) {
 118                 assert(s->active->user);
 119
 120                 fprintf(f,
 121                         "ACTIVE=%s\n"
 122                         "ACTIVE_UID="UID_FMT"\n",
 123                         s->active->id,
 124                         s->active->user->uid);
 125         }
 126
 127         if (s->sessions) {
 128                 Session *i;
 129
 130                 fputs("SESSIONS=", f);
 131                 LIST_FOREACH(sessions_by_seat, i, s->sessions) {
 132                         fprintf(f,
 133                                 "%s%c",
 134                                 i->id,
 135                                 i->sessions_by_seat_next ? ' ' : '\n');
 136                 }
 137
 138                 fputs("UIDS=", f);
 139                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 140                         fprintf(f,
 141                                 UID_FMT"%c",
 142                                 i->user->uid,
 143                                 i->sessions_by_seat_next ? ' ' : '\n');
 144         }
 145
 146         r = fflush_and_check(f);
 147         if (r < 0)
 148                 goto fail;
 149
 150         if (rename(temp_path, s->state_file) < 0) {
 151                 r = -errno;
 152                 goto fail;
 153         }
 154
 155         return 0;
 156
 157 fail:
 158         (void) unlink(s->state_file);
 159
 160         if (temp_path)
 161                 (void) unlink(temp_path);
 162
 163         return log_error_errno(r, "Failed to save seat data %s: %m", s->state_file);
 164 }
 165
 166 int seat_load(Seat *s) {
 167         assert(s);
 168
 169         /* There isn't actually anything to read here ... */
 170
 171         return 0;
 172 }
 173
 174 #if 0 /// UNNEEDED by elogind
 175 static int vt_allocate(unsigned int vtnr) {
 176         char p[sizeof("/dev/tty") + DECIMAL_STR_MAX(unsigned int)];
 177         _cleanup_close_ int fd = -1;
 178
 179         assert(vtnr >= 1);
 180
 181         xsprintf(p, "/dev/tty%u", vtnr);
 182         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 183         if (fd < 0)
 184                 return -errno;
 185
 186         return 0;
 187 }
 188
 189 int seat_preallocate_vts(Seat *s) {
 190         int r = 0;
 191         unsigned i;
 192
 193         assert(s);
 194         assert(s->manager);
 195
 196         log_debug("Preallocating VTs...");
 197
 198         if (s->manager->n_autovts <= 0)
 199                 return 0;
 200
 201         if (!seat_has_vts(s))
 202                 return 0;
 203
 204         for (i = 1; i <= s->manager->n_autovts; i++) {
 205                 int q;
 206
 207                 q = vt_allocate(i);
 208                 if (q < 0) {
 209                         log_error_errno(q, "Failed to preallocate VT %u: %m", i);
 210                         r = q;
 211                 }
 212         }
 213
 214         return r;
 215 }
 216 #endif // 0
 217
 218 int seat_apply_acls(Seat *s, Session *old_active) {
 219         int r;
 220
 221         assert(s);
 222
 223         r = devnode_acl_all(s->manager->udev,
 224                             s->id,
 225                             false,
 226                             !!old_active, old_active ? old_active->user->uid : 0,
 227                             !!s->active, s->active ? s->active->user->uid : 0);
 228
 229         if (r < 0)
 230                 log_error_errno(r, "Failed to apply ACLs: %m");
 231
 232         return r;
 233 }
 234
 235 int seat_set_active(Seat *s, Session *session) {
 236         Session *old_active;
 237
 238         assert(s);
 239         assert(!session || session->seat == s);
 240
 241         if (session == s->active)
 242                 return 0;
 243
 244         old_active = s->active;
 245         s->active = session;
 246
 247         if (old_active) {
 248                 session_device_pause_all(old_active);
 249                 session_send_changed(old_active, "Active", NULL);
 250         }
 251
 252         seat_apply_acls(s, old_active);
 253
 254         if (session && session->started) {
 255                 session_send_changed(session, "Active", NULL);
 256                 session_device_resume_all(session);
 257         }
 258
 259         if (!session || session->started)
 260                 seat_send_changed(s, "ActiveSession", NULL);
 261
 262         seat_save(s);
 263
 264         if (session) {
 265                 session_save(session);
 266                 user_save(session->user);
 267         }
 268
 269         if (old_active) {
 270                 session_save(old_active);
 271                 if (!session || session->user != old_active->user)
 272                         user_save(old_active->user);
 273         }
 274
 275         return 0;
 276 }
 277
 278 int seat_switch_to(Seat *s, unsigned int num) {
 279         /* Public session positions skip 0 (there is only F1-F12). Maybe it
 280          * will get reassigned in the future, so return error for now. */
 281         if (num == 0)
 282                 return -EINVAL;
 283
 284         if (num >= s->position_count || !s->positions[num]) {
 285                 /* allow switching to unused VTs to trigger auto-activate */
 286                 if (seat_has_vts(s) && num < 64)
 287                         return chvt(num);
 288
 289                 return -EINVAL;
 290         }
 291
 292         return session_activate(s->positions[num]);
 293 }
 294
 295 int seat_switch_to_next(Seat *s) {
 296         unsigned int start, i;
 297
 298         if (s->position_count == 0)
 299                 return -EINVAL;
 300
 301         start = 1;
 302         if (s->active && s->active->position > 0)
 303                 start = s->active->position;
 304
 305         for (i = start + 1; i < s->position_count; ++i)
 306                 if (s->positions[i])
 307                         return session_activate(s->positions[i]);
 308
 309         for (i = 1; i < start; ++i)
 310                 if (s->positions[i])
 311                         return session_activate(s->positions[i]);
 312
 313         return -EINVAL;
 314 }
 315
 316 int seat_switch_to_previous(Seat *s) {
 317         unsigned int start, i;
 318
 319         if (s->position_count == 0)
 320                 return -EINVAL;
 321
 322         start = 1;
 323         if (s->active && s->active->position > 0)
 324                 start = s->active->position;
 325
 326         for (i = start - 1; i > 0; --i)
 327                 if (s->positions[i])
 328                         return session_activate(s->positions[i]);
 329
 330         for (i = s->position_count - 1; i > start; --i)
 331                 if (s->positions[i])
 332                         return session_activate(s->positions[i]);
 333
 334         return -EINVAL;
 335 }
 336
 337 int seat_active_vt_changed(Seat *s, unsigned int vtnr) {
 338         Session *i, *new_active = NULL;
 339         int r;
 340
 341         assert(s);
 342         assert(vtnr >= 1);
 343
 344         if (!seat_has_vts(s))
 345                 return -EINVAL;
 346
 347         log_debug("VT changed to %u", vtnr);
 348
 349         /* we might have earlier closing sessions on the same VT, so try to
 350          * find a running one first */
 351         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 352                 if (i->vtnr == vtnr && !i->stopping) {
 353                         new_active = i;
 354                         break;
 355                 }
 356
 357         if (!new_active) {
 358                 /* no running one? then we can't decide which one is the
 359                  * active one, let the first one win */
 360                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 361                         if (i->vtnr == vtnr) {
 362                                 new_active = i;
 363                                 break;
 364                         }
 365         }
 366
 367         r = seat_set_active(s, new_active);
 368 #if 0 /// elogind does not spawn autovt
 369         manager_spawn_autovt(s->manager, vtnr);
 370 #endif // 0
 371
 372         return r;
 373 }
 374
 375 int seat_read_active_vt(Seat *s) {
 376         char t[64];
 377         ssize_t k;
 378         unsigned int vtnr;
 379         int r;
 380
 381         assert(s);
 382
 383         if (!seat_has_vts(s))
 384                 return 0;
 385
 386         lseek(s->manager->console_active_fd, SEEK_SET, 0);
 387
 388         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 389         if (k <= 0) {
 390                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 391                 return k < 0 ? -errno : -EIO;
 392         }
 393
 394         t[k] = 0;
 395         truncate_nl(t);
 396
 397         if (!startswith(t, "tty")) {
 398                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 399                 return -EIO;
 400         }
 401
 402         r = safe_atou(t+3, &vtnr);
 403         if (r < 0) {
 404                 log_error("Failed to parse VT number %s", t+3);
 405                 return r;
 406         }
 407
 408         if (!vtnr) {
 409                 log_error("VT number invalid: %s", t+3);
 410                 return -EIO;
 411         }
 412
 413         return seat_active_vt_changed(s, vtnr);
 414 }
 415
 416 int seat_start(Seat *s) {
 417         assert(s);
 418
 419         if (s->started)
 420                 return 0;
 421
 422         log_struct(LOG_INFO,
 423                    LOG_MESSAGE_ID(SD_MESSAGE_SEAT_START),
 424                    "SEAT_ID=%s", s->id,
 425                    LOG_MESSAGE("New seat %s.", s->id),
 426                    NULL);
 427
 428         /* Initialize VT magic stuff */
 429 #if 0 /// elogind does not support autospawning vts
 430         seat_preallocate_vts(s);
 431 #endif // 0
 432
 433         /* Read current VT */
 434         seat_read_active_vt(s);
 435
 436         s->started = true;
 437
 438         /* Save seat data */
 439         seat_save(s);
 440
 441         seat_send_signal(s, true);
 442
 443         return 0;
 444 }
 445
 446 int seat_stop(Seat *s, bool force) {
 447         int r = 0;
 448
 449         assert(s);
 450
 451         if (s->started)
 452                 log_struct(LOG_INFO,
 453                            LOG_MESSAGE_ID(SD_MESSAGE_SEAT_STOP),
 454                            "SEAT_ID=%s", s->id,
 455                            LOG_MESSAGE("Removed seat %s.", s->id),
 456                            NULL);
 457
 458         seat_stop_sessions(s, force);
 459
 460         unlink(s->state_file);
 461         seat_add_to_gc_queue(s);
 462
 463         if (s->started)
 464                 seat_send_signal(s, false);
 465
 466         s->started = false;
 467
 468         return r;
 469 }
 470
 471 int seat_stop_sessions(Seat *s, bool force) {
 472         Session *session;
 473         int r = 0, k;
 474
 475         assert(s);
 476
 477         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 478                 k = session_stop(session, force);
 479                 if (k < 0)
 480                         r = k;
 481         }
 482
 483         return r;
 484 }
 485
 486 void seat_evict_position(Seat *s, Session *session) {
 487         Session *iter;
 488         unsigned int pos = session->position;
 489
 490         session->position = 0;
 491
 492         if (pos == 0)
 493                 return;
 494
 495         if (pos < s->position_count && s->positions[pos] == session) {
 496                 s->positions[pos] = NULL;
 497
 498                 /* There might be another session claiming the same
 499                  * position (eg., during gdm->session transition), so let's look
 500                  * for it and set it on the free slot. */
 501                 LIST_FOREACH(sessions_by_seat, iter, s->sessions) {
 502                         if (iter->position == pos && session_get_state(iter) != SESSION_CLOSING) {
 503                                 s->positions[pos] = iter;
 504                                 break;
 505                         }
 506                 }
 507         }
 508 }
 509
 510 void seat_claim_position(Seat *s, Session *session, unsigned int pos) {
 511         /* with VTs, the position is always the same as the VTnr */
 512         if (seat_has_vts(s))
 513                 pos = session->vtnr;
 514
 515         if (!GREEDY_REALLOC0(s->positions, s->position_count, pos + 1))
 516                 return;
 517
 518         seat_evict_position(s, session);
 519
 520         session->position = pos;
 521         if (pos > 0)
 522                 s->positions[pos] = session;
 523 }
 524
 525 static void seat_assign_position(Seat *s, Session *session) {
 526         unsigned int pos;
 527
 528         if (session->position > 0)
 529                 return;
 530
 531         for (pos = 1; pos < s->position_count; ++pos)
 532                 if (!s->positions[pos])
 533                         break;
 534
 535         seat_claim_position(s, session, pos);
 536 }
 537
 538 int seat_attach_session(Seat *s, Session *session) {
 539         assert(s);
 540         assert(session);
 541         assert(!session->seat);
 542
 543         if (!seat_has_vts(s) != !session->vtnr)
 544                 return -EINVAL;
 545
 546         session->seat = s;
 547         LIST_PREPEND(sessions_by_seat, s->sessions, session);
 548         seat_assign_position(s, session);
 549
 550         seat_send_changed(s, "Sessions", NULL);
 551
 552         /* On seats with VTs, the VT logic defines which session is active. On
 553          * seats without VTs, we automatically activate new sessions. */
 554         if (!seat_has_vts(s))
 555                 seat_set_active(s, session);
 556
 557         return 0;
 558 }
 559
 560 void seat_complete_switch(Seat *s) {
 561         Session *session;
 562
 563         assert(s);
 564
 565         /* if no session-switch is pending or if it got canceled, do nothing */
 566         if (!s->pending_switch)
 567                 return;
 568
 569         session = s->pending_switch;
 570         s->pending_switch = NULL;
 571
 572         seat_set_active(s, session);
 573 }
 574
 575 bool seat_has_vts(Seat *s) {
 576         assert(s);
 577
 578         return seat_is_seat0(s) && s->manager->console_active_fd >= 0;
 579 }
 580
 581 bool seat_is_seat0(Seat *s) {
 582         assert(s);
 583
 584         return s->manager->seat0 == s;
 585 }
 586
 587 bool seat_can_multi_session(Seat *s) {
 588         assert(s);
 589
 590         return seat_has_vts(s);
 591 }
 592
 593 bool seat_can_tty(Seat *s) {
 594         assert(s);
 595
 596         return seat_has_vts(s);
 597 }
 598
 599 bool seat_has_master_device(Seat *s) {
 600         assert(s);
 601
 602         /* device list is ordered by "master" flag */
 603         return !!s->devices && s->devices->master;
 604 }
 605
 606 bool seat_can_graphical(Seat *s) {
 607         assert(s);
 608
 609         return seat_has_master_device(s);
 610 }
 611
 612 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 613         Session *session;
 614         bool idle_hint = true;
 615         dual_timestamp ts = DUAL_TIMESTAMP_NULL;
 616
 617         assert(s);
 618
 619         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 620                 dual_timestamp k;
 621                 int ih;
 622
 623                 ih = session_get_idle_hint(session, &k);
 624                 if (ih < 0)
 625                         return ih;
 626
 627                 if (!ih) {
 628                         if (!idle_hint) {
 629                                 if (k.monotonic > ts.monotonic)
 630                                         ts = k;
 631                         } else {
 632                                 idle_hint = false;
 633                                 ts = k;
 634                         }
 635                 } else if (idle_hint) {
 636
 637                         if (k.monotonic > ts.monotonic)
 638                                 ts = k;
 639                 }
 640         }
 641
 642         if (t)
 643                 *t = ts;
 644
 645         return idle_hint;
 646 }
 647
 648 bool seat_check_gc(Seat *s, bool drop_not_started) {
 649         assert(s);
 650
 651         if (drop_not_started && !s->started)
 652                 return false;
 653
 654         if (seat_is_seat0(s))
 655                 return true;
 656
 657         return seat_has_master_device(s);
 658 }
 659
 660 void seat_add_to_gc_queue(Seat *s) {
 661         assert(s);
 662
 663         if (s->in_gc_queue)
 664                 return;
 665
 666         LIST_PREPEND(gc_queue, s->manager->seat_gc_queue, s);
 667         s->in_gc_queue = true;
 668 }
 669
 670 static bool seat_name_valid_char(char c) {
 671         return
 672                 (c >= 'a' && c <= 'z') ||
 673                 (c >= 'A' && c <= 'Z') ||
 674                 (c >= '0' && c <= '9') ||
 675                 c == '-' ||
 676                 c == '_';
 677 }
 678
 679 bool seat_name_is_valid(const char *name) {
 680         const char *p;
 681
 682         assert(name);
 683
 684         if (!startswith(name, "seat"))
 685                 return false;
 686
 687         if (!name[4])
 688                 return false;
 689
 690         for (p = name; *p; p++)
 691                 if (!seat_name_valid_char(*p))
 692                         return false;
 693
 694         if (strlen(name) > 255)
 695                 return false;
 696
 697         return true;
 698 }