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