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