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 #if 0 /// UNNEEDED by elogind
 178 static int vt_allocate(unsigned int vtnr) {
 179         char p[sizeof("/dev/tty") + DECIMAL_STR_MAX(unsigned int)];
 180         _cleanup_close_ int fd = -1;
 181
 182         assert(vtnr >= 1);
 183
 184         xsprintf(p, "/dev/tty%u", vtnr);
 185         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 186         if (fd < 0)
 187                 return -errno;
 188
 189         return 0;
 190 }
 191
 192 int seat_preallocate_vts(Seat *s) {
 193         int r = 0;
 194         unsigned i;
 195
 196         assert(s);
 197         assert(s->manager);
 198
 199         log_debug("Preallocating VTs...");
 200
 201         if (s->manager->n_autovts <= 0)
 202                 return 0;
 203
 204         if (!seat_has_vts(s))
 205                 return 0;
 206
 207         for (i = 1; i <= s->manager->n_autovts; i++) {
 208                 int q;
 209
 210                 q = vt_allocate(i);
 211                 if (q < 0) {
 212                         log_error_errno(q, "Failed to preallocate VT %u: %m", i);
 213                         r = q;
 214                 }
 215         }
 216
 217         return r;
 218 }
 219 #endif // 0
 220
 221 int seat_apply_acls(Seat *s, Session *old_active) {
 222         int r;
 223
 224         assert(s);
 225
 226         r = devnode_acl_all(s->manager->udev,
 227                             s->id,
 228                             false,
 229                             !!old_active, old_active ? old_active->user->uid : 0,
 230                             !!s->active, s->active ? s->active->user->uid : 0);
 231
 232         if (r < 0)
 233                 log_error_errno(r, "Failed to apply ACLs: %m");
 234
 235         return r;
 236 }
 237
 238 int seat_set_active(Seat *s, Session *session) {
 239         Session *old_active;
 240
 241         assert(s);
 242         assert(!session || session->seat == s);
 243
 244         if (session == s->active)
 245                 return 0;
 246
 247         old_active = s->active;
 248         s->active = session;
 249
 250         if (old_active) {
 251                 session_device_pause_all(old_active);
 252                 session_send_changed(old_active, "Active", NULL);
 253         }
 254
 255         seat_apply_acls(s, old_active);
 256
 257         if (session && session->started) {
 258                 session_send_changed(session, "Active", NULL);
 259                 session_device_resume_all(session);
 260         }
 261
 262         if (!session || session->started)
 263                 seat_send_changed(s, "ActiveSession", NULL);
 264
 265         seat_save(s);
 266
 267         if (session) {
 268                 session_save(session);
 269                 user_save(session->user);
 270         }
 271
 272         if (old_active) {
 273                 session_save(old_active);
 274                 if (!session || session->user != old_active->user)
 275                         user_save(old_active->user);
 276         }
 277
 278         return 0;
 279 }
 280
 281 int seat_switch_to(Seat *s, unsigned int num) {
 282         /* Public session positions skip 0 (there is only F1-F12). Maybe it
 283          * will get reassigned in the future, so return error for now. */
 284         if (num == 0)
 285                 return -EINVAL;
 286
 287         if (num >= s->position_count || !s->positions[num]) {
 288                 /* allow switching to unused VTs to trigger auto-activate */
 289                 if (seat_has_vts(s) && num < 64)
 290                         return chvt(num);
 291
 292                 return -EINVAL;
 293         }
 294
 295         return session_activate(s->positions[num]);
 296 }
 297
 298 int seat_switch_to_next(Seat *s) {
 299         unsigned int start, i;
 300
 301         if (s->position_count == 0)
 302                 return -EINVAL;
 303
 304         start = 1;
 305         if (s->active && s->active->position > 0)
 306                 start = s->active->position;
 307
 308         for (i = start + 1; i < s->position_count; ++i)
 309                 if (s->positions[i])
 310                         return session_activate(s->positions[i]);
 311
 312         for (i = 1; i < start; ++i)
 313                 if (s->positions[i])
 314                         return session_activate(s->positions[i]);
 315
 316         return -EINVAL;
 317 }
 318
 319 int seat_switch_to_previous(Seat *s) {
 320         unsigned int start, i;
 321
 322         if (s->position_count == 0)
 323                 return -EINVAL;
 324
 325         start = 1;
 326         if (s->active && s->active->position > 0)
 327                 start = s->active->position;
 328
 329         for (i = start - 1; i > 0; --i)
 330                 if (s->positions[i])
 331                         return session_activate(s->positions[i]);
 332
 333         for (i = s->position_count - 1; i > start; --i)
 334                 if (s->positions[i])
 335                         return session_activate(s->positions[i]);
 336
 337         return -EINVAL;
 338 }
 339
 340 int seat_active_vt_changed(Seat *s, unsigned int vtnr) {
 341         Session *i, *new_active = NULL;
 342         int r;
 343
 344         assert(s);
 345         assert(vtnr >= 1);
 346
 347         if (!seat_has_vts(s))
 348                 return -EINVAL;
 349
 350         log_debug("VT changed to %u", vtnr);
 351
 352         /* we might have earlier closing sessions on the same VT, so try to
 353          * find a running one first */
 354         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 355                 if (i->vtnr == vtnr && !i->stopping) {
 356                         new_active = i;
 357                         break;
 358                 }
 359
 360         if (!new_active) {
 361                 /* no running one? then we can't decide which one is the
 362                  * active one, let the first one win */
 363                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 364                         if (i->vtnr == vtnr) {
 365                                 new_active = i;
 366                                 break;
 367                         }
 368         }
 369
 370         r = seat_set_active(s, new_active);
 371 #if 0 /// elogind does not spawn autovt
 372         manager_spawn_autovt(s->manager, vtnr);
 373 #endif // 0
 374
 375         return r;
 376 }
 377
 378 int seat_read_active_vt(Seat *s) {
 379         char t[64];
 380         ssize_t k;
 381         unsigned int vtnr;
 382         int r;
 383
 384         assert(s);
 385
 386         if (!seat_has_vts(s))
 387                 return 0;
 388
 389         lseek(s->manager->console_active_fd, SEEK_SET, 0);
 390
 391         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 392         if (k <= 0) {
 393                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 394                 return k < 0 ? -errno : -EIO;
 395         }
 396
 397         t[k] = 0;
 398         truncate_nl(t);
 399
 400         if (!startswith(t, "tty")) {
 401                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 402                 return -EIO;
 403         }
 404
 405         r = safe_atou(t+3, &vtnr);
 406         if (r < 0) {
 407                 log_error("Failed to parse VT number %s", t+3);
 408                 return r;
 409         }
 410
 411         if (!vtnr) {
 412                 log_error("VT number invalid: %s", t+3);
 413                 return -EIO;
 414         }
 415
 416         return seat_active_vt_changed(s, vtnr);
 417 }
 418
 419 int seat_start(Seat *s) {
 420         assert(s);
 421
 422         if (s->started)
 423                 return 0;
 424
 425         log_struct(LOG_INFO,
 426                    LOG_MESSAGE_ID(SD_MESSAGE_SEAT_START),
 427                    "SEAT_ID=%s", s->id,
 428                    LOG_MESSAGE("New seat %s.", s->id),
 429                    NULL);
 430
 431         /* Initialize VT magic stuff */
 432 #if 0 /// elogind does not support autospawning vts
 433         seat_preallocate_vts(s);
 434 #endif // 0
 435
 436         /* Read current VT */
 437         seat_read_active_vt(s);
 438
 439         s->started = true;
 440
 441         /* Save seat data */
 442         seat_save(s);
 443
 444         seat_send_signal(s, true);
 445
 446         return 0;
 447 }
 448
 449 int seat_stop(Seat *s, bool force) {
 450         int r = 0;
 451
 452         assert(s);
 453
 454         if (s->started)
 455                 log_struct(LOG_INFO,
 456                            LOG_MESSAGE_ID(SD_MESSAGE_SEAT_STOP),
 457                            "SEAT_ID=%s", s->id,
 458                            LOG_MESSAGE("Removed seat %s.", s->id),
 459                            NULL);
 460
 461         seat_stop_sessions(s, force);
 462
 463         unlink(s->state_file);
 464         seat_add_to_gc_queue(s);
 465
 466         if (s->started)
 467                 seat_send_signal(s, false);
 468
 469         s->started = false;
 470
 471         return r;
 472 }
 473
 474 int seat_stop_sessions(Seat *s, bool force) {
 475         Session *session;
 476         int r = 0, k;
 477
 478         assert(s);
 479
 480         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 481                 k = session_stop(session, force);
 482                 if (k < 0)
 483                         r = k;
 484         }
 485
 486         return r;
 487 }
 488
 489 void seat_evict_position(Seat *s, Session *session) {
 490         Session *iter;
 491         unsigned int pos = session->position;
 492
 493         session->position = 0;
 494
 495         if (pos == 0)
 496                 return;
 497
 498         if (pos < s->position_count && s->positions[pos] == session) {
 499                 s->positions[pos] = NULL;
 500
 501                 /* There might be another session claiming the same
 502                  * position (eg., during gdm->session transition), so let's look
 503                  * for it and set it on the free slot. */
 504                 LIST_FOREACH(sessions_by_seat, iter, s->sessions) {
 505                         if (iter->position == pos && session_get_state(iter) != SESSION_CLOSING) {
 506                                 s->positions[pos] = iter;
 507                                 break;
 508                         }
 509                 }
 510         }
 511 }
 512
 513 void seat_claim_position(Seat *s, Session *session, unsigned int pos) {
 514         /* with VTs, the position is always the same as the VTnr */
 515         if (seat_has_vts(s))
 516                 pos = session->vtnr;
 517
 518         if (!GREEDY_REALLOC0(s->positions, s->position_count, pos + 1))
 519                 return;
 520
 521         seat_evict_position(s, session);
 522
 523         session->position = pos;
 524         if (pos > 0)
 525                 s->positions[pos] = session;
 526 }
 527
 528 static void seat_assign_position(Seat *s, Session *session) {
 529         unsigned int pos;
 530
 531         if (session->position > 0)
 532                 return;
 533
 534         for (pos = 1; pos < s->position_count; ++pos)
 535                 if (!s->positions[pos])
 536                         break;
 537
 538         seat_claim_position(s, session, pos);
 539 }
 540
 541 int seat_attach_session(Seat *s, Session *session) {
 542         assert(s);
 543         assert(session);
 544         assert(!session->seat);
 545
 546         if (!seat_has_vts(s) != !session->vtnr)
 547                 return -EINVAL;
 548
 549         session->seat = s;
 550         LIST_PREPEND(sessions_by_seat, s->sessions, session);
 551         seat_assign_position(s, session);
 552
 553         seat_send_changed(s, "Sessions", NULL);
 554
 555         /* On seats with VTs, the VT logic defines which session is active. On
 556          * seats without VTs, we automatically activate new sessions. */
 557         if (!seat_has_vts(s))
 558                 seat_set_active(s, session);
 559
 560         return 0;
 561 }
 562
 563 void seat_complete_switch(Seat *s) {
 564         Session *session;
 565
 566         assert(s);
 567
 568         /* if no session-switch is pending or if it got canceled, do nothing */
 569         if (!s->pending_switch)
 570                 return;
 571
 572         session = s->pending_switch;
 573         s->pending_switch = NULL;
 574
 575         seat_set_active(s, session);
 576 }
 577
 578 bool seat_has_vts(Seat *s) {
 579         assert(s);
 580
 581         return seat_is_seat0(s) && s->manager->console_active_fd >= 0;
 582 }
 583
 584 bool seat_is_seat0(Seat *s) {
 585         assert(s);
 586
 587         return s->manager->seat0 == s;
 588 }
 589
 590 bool seat_can_multi_session(Seat *s) {
 591         assert(s);
 592
 593         return seat_has_vts(s);
 594 }
 595
 596 bool seat_can_tty(Seat *s) {
 597         assert(s);
 598
 599         return seat_has_vts(s);
 600 }
 601
 602 bool seat_has_master_device(Seat *s) {
 603         assert(s);
 604
 605         /* device list is ordered by "master" flag */
 606         return !!s->devices && s->devices->master;
 607 }
 608
 609 bool seat_can_graphical(Seat *s) {
 610         assert(s);
 611
 612         return seat_has_master_device(s);
 613 }
 614
 615 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 616         Session *session;
 617         bool idle_hint = true;
 618         dual_timestamp ts = DUAL_TIMESTAMP_NULL;
 619
 620         assert(s);
 621
 622         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 623                 dual_timestamp k;
 624                 int ih;
 625
 626                 ih = session_get_idle_hint(session, &k);
 627                 if (ih < 0)
 628                         return ih;
 629
 630                 if (!ih) {
 631                         if (!idle_hint) {
 632                                 if (k.monotonic > ts.monotonic)
 633                                         ts = k;
 634                         } else {
 635                                 idle_hint = false;
 636                                 ts = k;
 637                         }
 638                 } else if (idle_hint) {
 639
 640                         if (k.monotonic > ts.monotonic)
 641                                 ts = k;
 642                 }
 643         }
 644
 645         if (t)
 646                 *t = ts;
 647
 648         return idle_hint;
 649 }
 650
 651 bool seat_check_gc(Seat *s, bool drop_not_started) {
 652         assert(s);
 653
 654         if (drop_not_started && !s->started)
 655                 return false;
 656
 657         if (seat_is_seat0(s))
 658                 return true;
 659
 660         return seat_has_master_device(s);
 661 }
 662
 663 void seat_add_to_gc_queue(Seat *s) {
 664         assert(s);
 665
 666         if (s->in_gc_queue)
 667                 return;
 668
 669         LIST_PREPEND(gc_queue, s->manager->seat_gc_queue, s);
 670         s->in_gc_queue = true;
 671 }
 672
 673 static bool seat_name_valid_char(char c) {
 674         return
 675                 (c >= 'a' && c <= 'z') ||
 676                 (c >= 'A' && c <= 'Z') ||
 677                 (c >= '0' && c <= '9') ||
 678                 c == '-' ||
 679                 c == '_';
 680 }
 681
 682 bool seat_name_is_valid(const char *name) {
 683         const char *p;
 684
 685         assert(name);
 686
 687         if (!startswith(name, "seat"))
 688                 return false;
 689
 690         if (!name[4])
 691                 return false;
 692
 693         for (p = name; *p; p++)
 694                 if (!seat_name_valid_char(*p))
 695                         return false;
 696
 697         if (strlen(name) > 255)
 698                 return false;
 699
 700         return true;
 701 }