src/login/logind-seat.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2011 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <assert.h>
  23 #include <errno.h>
  24 #include <unistd.h>
  25 #include <fcntl.h>
  26 #include <sys/ioctl.h>
  27 #include <linux/vt.h>
  28 #include <string.h>
  29
  30 #include "sd-id128.h"
  31 #include "sd-messages.h"
  32 #include "logind-seat.h"
  33 #include "logind-acl.h"
  34 #include "util.h"
  35 #include "mkdir.h"
  36 #include "path-util.h"
  37
  38 Seat *seat_new(Manager *m, const char *id) {
  39         Seat *s;
  40
  41         assert(m);
  42         assert(id);
  43
  44         s = new0(Seat, 1);
  45         if (!s)
  46                 return NULL;
  47
  48         s->state_file = strappend("/run/systemd/seats/", id);
  49         if (!s->state_file) {
  50                 free(s);
  51                 return NULL;
  52         }
  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                 free(s);
  60                 return NULL;
  61         }
  62
  63         return s;
  64 }
  65
  66 void seat_free(Seat *s) {
  67         assert(s);
  68
  69         if (s->in_gc_queue)
  70                 LIST_REMOVE(gc_queue, s->manager->seat_gc_queue, s);
  71
  72         while (s->sessions)
  73                 session_free(s->sessions);
  74
  75         assert(!s->active);
  76
  77         while (s->devices)
  78                 device_free(s->devices);
  79
  80         hashmap_remove(s->manager->seats, s->id);
  81
  82         free(s->positions);
  83         free(s->state_file);
  84         free(s);
  85 }
  86
  87 int seat_save(Seat *s) {
  88         _cleanup_free_ char *temp_path = NULL;
  89         _cleanup_fclose_ FILE *f = NULL;
  90         int r;
  91
  92         assert(s);
  93
  94         if (!s->started)
  95                 return 0;
  96
  97         r = mkdir_safe_label("/run/systemd/seats", 0755, 0, 0);
  98         if (r < 0)
  99                 goto finish;
 100
 101         r = fopen_temporary(s->state_file, &f, &temp_path);
 102         if (r < 0)
 103                 goto finish;
 104
 105         fchmod(fileno(f), 0644);
 106
 107         fprintf(f,
 108                 "# This is private data. Do not parse.\n"
 109                 "IS_SEAT0=%i\n"
 110                 "CAN_MULTI_SESSION=%i\n"
 111                 "CAN_TTY=%i\n"
 112                 "CAN_GRAPHICAL=%i\n",
 113                 seat_is_seat0(s),
 114                 seat_can_multi_session(s),
 115                 seat_can_tty(s),
 116                 seat_can_graphical(s));
 117
 118         if (s->active) {
 119                 assert(s->active->user);
 120
 121                 fprintf(f,
 122                         "ACTIVE=%s\n"
 123                         "ACTIVE_UID=%lu\n",
 124                         s->active->id,
 125                         (unsigned long) s->active->user->uid);
 126         }
 127
 128         if (s->sessions) {
 129                 Session *i;
 130
 131                 fputs("SESSIONS=", f);
 132                 LIST_FOREACH(sessions_by_seat, i, s->sessions) {
 133                         fprintf(f,
 134                                 "%s%c",
 135                                 i->id,
 136                                 i->sessions_by_seat_next ? ' ' : '\n');
 137                 }
 138
 139                 fputs("UIDS=", f);
 140                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 141                         fprintf(f,
 142                                 "%lu%c",
 143                                 (unsigned long) i->user->uid,
 144                                 i->sessions_by_seat_next ? ' ' : '\n');
 145         }
 146
 147         fflush(f);
 148
 149         if (ferror(f) || rename(temp_path, s->state_file) < 0) {
 150                 r = -errno;
 151                 unlink(s->state_file);
 152                 unlink(temp_path);
 153         }
 154
 155 finish:
 156         if (r < 0)
 157                 log_error("Failed to save seat data for %s: %s", s->id, strerror(-r));
 158
 159         return r;
 160 }
 161
 162 int seat_load(Seat *s) {
 163         assert(s);
 164
 165         /* There isn't actually anything to read here ... */
 166
 167         return 0;
 168 }
 169
 170 static int vt_allocate(unsigned int vtnr) {
 171         _cleanup_free_ char *p = NULL;
 172         _cleanup_close_ int fd = -1;
 173
 174         assert(vtnr >= 1);
 175
 176         if (asprintf(&p, "/dev/tty%u", vtnr) < 0)
 177                 return -ENOMEM;
 178
 179         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 180         if (fd < 0)
 181                 return -errno;
 182
 183         return 0;
 184 }
 185
 186 int seat_preallocate_vts(Seat *s) {
 187         int r = 0;
 188         unsigned i;
 189
 190         assert(s);
 191         assert(s->manager);
 192
 193         log_debug("Preallocating VTs...");
 194
 195         if (s->manager->n_autovts <= 0)
 196                 return 0;
 197
 198         if (!seat_has_vts(s))
 199                 return 0;
 200
 201         for (i = 1; i <= s->manager->n_autovts; i++) {
 202                 int q;
 203
 204                 q = vt_allocate(i);
 205                 if (q < 0) {
 206                         log_error("Failed to preallocate VT %i: %s", i, strerror(-q));
 207                         r = q;
 208                 }
 209         }
 210
 211         return r;
 212 }
 213
 214 int seat_apply_acls(Seat *s, Session *old_active) {
 215         int r;
 216
 217         assert(s);
 218
 219         r = devnode_acl_all(s->manager->udev,
 220                             s->id,
 221                             false,
 222                             !!old_active, old_active ? old_active->user->uid : 0,
 223                             !!s->active, s->active ? s->active->user->uid : 0);
 224
 225         if (r < 0)
 226                 log_error("Failed to apply ACLs: %s", strerror(-r));
 227
 228         return r;
 229 }
 230
 231 int seat_set_active(Seat *s, Session *session) {
 232         Session *old_active;
 233
 234         assert(s);
 235         assert(!session || session->seat == s);
 236
 237         if (session == s->active)
 238                 return 0;
 239
 240         old_active = s->active;
 241         s->active = session;
 242
 243         if (old_active) {
 244                 session_device_pause_all(old_active);
 245                 session_send_changed(old_active, "Active", NULL);
 246         }
 247
 248         seat_apply_acls(s, old_active);
 249
 250         if (session && session->started) {
 251                 session_send_changed(session, "Active", NULL);
 252                 session_device_resume_all(session);
 253         }
 254
 255         if (!session || session->started)
 256                 seat_send_changed(s, "ActiveSession", NULL);
 257
 258         seat_save(s);
 259
 260         if (session) {
 261                 session_save(session);
 262                 user_save(session->user);
 263         }
 264
 265         if (old_active) {
 266                 session_save(old_active);
 267                 if (!session || session->user != old_active->user)
 268                         user_save(old_active->user);
 269         }
 270
 271         return 0;
 272 }
 273
 274 int seat_switch_to(Seat *s, unsigned int num) {
 275         /* Public session positions skip 0 (there is only F1-F12). Maybe it
 276          * will get reassigned in the future, so return error for now. */
 277         if (!num)
 278                 return -EINVAL;
 279
 280         if (num >= s->position_count || !s->positions[num])
 281                 return -EINVAL;
 282
 283         return session_activate(s->positions[num]);
 284 }
 285
 286 int seat_switch_to_next(Seat *s) {
 287         unsigned int start, i;
 288
 289         if (!s->position_count)
 290                 return -EINVAL;
 291
 292         start = 1;
 293         if (s->active && s->active->pos > 0)
 294                 start = s->active->pos;
 295
 296         for (i = start + 1; i < s->position_count; ++i)
 297                 if (s->positions[i])
 298                         return session_activate(s->positions[i]);
 299
 300         for (i = 1; i < start; ++i)
 301                 if (s->positions[i])
 302                         return session_activate(s->positions[i]);
 303
 304         return -EINVAL;
 305 }
 306
 307 int seat_switch_to_previous(Seat *s) {
 308         unsigned int start, i;
 309
 310         if (!s->position_count)
 311                 return -EINVAL;
 312
 313         start = 1;
 314         if (s->active && s->active->pos > 0)
 315                 start = s->active->pos;
 316
 317         for (i = start - 1; i > 0; --i)
 318                 if (s->positions[i])
 319                         return session_activate(s->positions[i]);
 320
 321         for (i = s->position_count - 1; i > start; --i)
 322                 if (s->positions[i])
 323                         return session_activate(s->positions[i]);
 324
 325         return -EINVAL;
 326 }
 327
 328 int seat_active_vt_changed(Seat *s, unsigned int vtnr) {
 329         Session *i, *new_active = NULL;
 330         int r;
 331
 332         assert(s);
 333         assert(vtnr >= 1);
 334
 335         if (!seat_has_vts(s))
 336                 return -EINVAL;
 337
 338         log_debug("VT changed to %u", vtnr);
 339
 340         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 341                 if (i->vtnr == vtnr) {
 342                         new_active = i;
 343                         break;
 344                 }
 345
 346         r = seat_set_active(s, new_active);
 347         manager_spawn_autovt(s->manager, vtnr);
 348
 349         return r;
 350 }
 351
 352 int seat_read_active_vt(Seat *s) {
 353         char t[64];
 354         ssize_t k;
 355         unsigned int vtnr;
 356         int r;
 357
 358         assert(s);
 359
 360         if (!seat_has_vts(s))
 361                 return 0;
 362
 363         lseek(s->manager->console_active_fd, SEEK_SET, 0);
 364
 365         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 366         if (k <= 0) {
 367                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 368                 return k < 0 ? -errno : -EIO;
 369         }
 370
 371         t[k] = 0;
 372         truncate_nl(t);
 373
 374         if (!startswith(t, "tty")) {
 375                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 376                 return -EIO;
 377         }
 378
 379         r = safe_atou(t+3, &vtnr);
 380         if (r < 0) {
 381                 log_error("Failed to parse VT number %s", t+3);
 382                 return r;
 383         }
 384
 385         if (!vtnr) {
 386                 log_error("VT number invalid: %s", t+3);
 387                 return -EIO;
 388         }
 389
 390         return seat_active_vt_changed(s, vtnr);
 391 }
 392
 393 int seat_start(Seat *s) {
 394         assert(s);
 395
 396         if (s->started)
 397                 return 0;
 398
 399         log_struct(LOG_INFO,
 400                    MESSAGE_ID(SD_MESSAGE_SEAT_START),
 401                    "SEAT_ID=%s", s->id,
 402                    "MESSAGE=New seat %s.", s->id,
 403                    NULL);
 404
 405         /* Initialize VT magic stuff */
 406         seat_preallocate_vts(s);
 407
 408         /* Read current VT */
 409         seat_read_active_vt(s);
 410
 411         s->started = true;
 412
 413         /* Save seat data */
 414         seat_save(s);
 415
 416         seat_send_signal(s, true);
 417
 418         return 0;
 419 }
 420
 421 int seat_stop(Seat *s) {
 422         int r = 0;
 423
 424         assert(s);
 425
 426         if (s->started)
 427                 log_struct(LOG_INFO,
 428                            MESSAGE_ID(SD_MESSAGE_SEAT_STOP),
 429                            "SEAT_ID=%s", s->id,
 430                            "MESSAGE=Removed seat %s.", s->id,
 431                            NULL);
 432
 433         seat_stop_sessions(s);
 434
 435         unlink(s->state_file);
 436         seat_add_to_gc_queue(s);
 437
 438         if (s->started)
 439                 seat_send_signal(s, false);
 440
 441         s->started = false;
 442
 443         return r;
 444 }
 445
 446 int seat_stop_sessions(Seat *s) {
 447         Session *session;
 448         int r = 0, k;
 449
 450         assert(s);
 451
 452         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 453                 k = session_stop(session);
 454                 if (k < 0)
 455                         r = k;
 456         }
 457
 458         return r;
 459 }
 460
 461 void seat_evict_position(Seat *s, Session *session) {
 462         unsigned int pos = session->pos;
 463
 464         session->pos = 0;
 465
 466         if (!pos)
 467                 return;
 468
 469         if (pos < s->position_count && s->positions[pos] == session)
 470                 s->positions[pos] = NULL;
 471 }
 472
 473 void seat_claim_position(Seat *s, Session *session, unsigned int pos) {
 474         /* with VTs, the position is always the same as the VTnr */
 475         if (seat_has_vts(s))
 476                 pos = session->vtnr;
 477
 478         if (!GREEDY_REALLOC0(s->positions, s->position_count, pos + 1))
 479                 return;
 480
 481         seat_evict_position(s, session);
 482
 483         session->pos = pos;
 484         if (pos > 0 && !s->positions[pos])
 485                 s->positions[pos] = session;
 486 }
 487
 488 static void seat_assign_position(Seat *s, Session *session) {
 489         unsigned int pos;
 490
 491         if (session->pos > 0)
 492                 return;
 493
 494         for (pos = 1; pos < s->position_count; ++pos)
 495                 if (!s->positions[pos])
 496                         break;
 497
 498         seat_claim_position(s, session, pos);
 499 }
 500
 501 int seat_attach_session(Seat *s, Session *session) {
 502         assert(s);
 503         assert(session);
 504         assert(!session->seat);
 505
 506         if (!seat_has_vts(s) != !session->vtnr)
 507                 return -EINVAL;
 508
 509         session->seat = s;
 510         LIST_PREPEND(sessions_by_seat, s->sessions, session);
 511         seat_assign_position(s, session);
 512
 513         seat_send_changed(s, "Sessions", NULL);
 514
 515         /* On seats with VTs, the VT logic defines which session is active. On
 516          * seats without VTs, we automatically activate new sessions. */
 517         if (!seat_has_vts(s))
 518                 seat_set_active(s, session);
 519
 520         return 0;
 521 }
 522
 523 void seat_complete_switch(Seat *s) {
 524         Session *session;
 525
 526         assert(s);
 527
 528         /* if no session-switch is pending or if it got canceled, do nothing */
 529         if (!s->pending_switch)
 530                 return;
 531
 532         session = s->pending_switch;
 533         s->pending_switch = NULL;
 534
 535         seat_set_active(s, session);
 536 }
 537
 538 bool seat_has_vts(Seat *s) {
 539         assert(s);
 540
 541         return seat_is_seat0(s) && s->manager->console_active_fd >= 0;
 542 }
 543
 544 bool seat_is_seat0(Seat *s) {
 545         assert(s);
 546
 547         return s->manager->seat0 == s;
 548 }
 549
 550 bool seat_can_multi_session(Seat *s) {
 551         assert(s);
 552
 553         return seat_has_vts(s);
 554 }
 555
 556 bool seat_can_tty(Seat *s) {
 557         assert(s);
 558
 559         return seat_has_vts(s);
 560 }
 561
 562 bool seat_has_master_device(Seat *s) {
 563         assert(s);
 564
 565         /* device list is ordered by "master" flag */
 566         return !!s->devices && s->devices->master;
 567 }
 568
 569 bool seat_can_graphical(Seat *s) {
 570         assert(s);
 571
 572         return seat_has_master_device(s);
 573 }
 574
 575 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 576         Session *session;
 577         bool idle_hint = true;
 578         dual_timestamp ts = { 0, 0 };
 579
 580         assert(s);
 581
 582         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 583                 dual_timestamp k;
 584                 int ih;
 585
 586                 ih = session_get_idle_hint(session, &k);
 587                 if (ih < 0)
 588                         return ih;
 589
 590                 if (!ih) {
 591                         if (!idle_hint) {
 592                                 if (k.monotonic > ts.monotonic)
 593                                         ts = k;
 594                         } else {
 595                                 idle_hint = false;
 596                                 ts = k;
 597                         }
 598                 } else if (idle_hint) {
 599
 600                         if (k.monotonic > ts.monotonic)
 601                                 ts = k;
 602                 }
 603         }
 604
 605         if (t)
 606                 *t = ts;
 607
 608         return idle_hint;
 609 }
 610
 611 bool seat_check_gc(Seat *s, bool drop_not_started) {
 612         assert(s);
 613
 614         if (drop_not_started && !s->started)
 615                 return false;
 616
 617         if (seat_is_seat0(s))
 618                 return true;
 619
 620         return seat_has_master_device(s);
 621 }
 622
 623 void seat_add_to_gc_queue(Seat *s) {
 624         assert(s);
 625
 626         if (s->in_gc_queue)
 627                 return;
 628
 629         LIST_PREPEND(gc_queue, s->manager->seat_gc_queue, s);
 630         s->in_gc_queue = true;
 631 }
 632
 633 static bool seat_name_valid_char(char c) {
 634         return
 635                 (c >= 'a' && c <= 'z') ||
 636                 (c >= 'A' && c <= 'Z') ||
 637                 (c >= '0' && c <= '9') ||
 638                 c == '-' ||
 639                 c == '_';
 640 }
 641
 642 bool seat_name_is_valid(const char *name) {
 643         const char *p;
 644
 645         assert(name);
 646
 647         if (!startswith(name, "seat"))
 648                 return false;
 649
 650         if (!name[4])
 651                 return false;
 652
 653         for (p = name; *p; p++)
 654                 if (!seat_name_valid_char(*p))
 655                         return false;
 656
 657         if (strlen(name) > 255)
 658                 return false;
 659
 660         return true;
 661 }