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 "systemd/sd-id128.h"
  31 #include "systemd/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 = path_get_file_name(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(Seat, 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->state_file);
  83         free(s);
  84 }
  85
  86 int seat_save(Seat *s) {
  87         int r;
  88         FILE *f;
  89         char *temp_path;
  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 finish;
  99
 100         r = fopen_temporary(s->state_file, &f, &temp_path);
 101         if (r < 0)
 102                 goto finish;
 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=%lu\n",
 123                         s->active->id,
 124                         (unsigned long) 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                                 "%lu%c",
 142                                 (unsigned long) i->user->uid,
 143                                 i->sessions_by_seat_next ? ' ' : '\n');
 144         }
 145
 146         fflush(f);
 147
 148         if (ferror(f) || rename(temp_path, s->state_file) < 0) {
 149                 r = -errno;
 150                 unlink(s->state_file);
 151                 unlink(temp_path);
 152         }
 153
 154         fclose(f);
 155         free(temp_path);
 156
 157 finish:
 158         if (r < 0)
 159                 log_error("Failed to save seat data for %s: %s", s->id, strerror(-r));
 160
 161         return r;
 162 }
 163
 164 int seat_load(Seat *s) {
 165         assert(s);
 166
 167         /* There isn't actually anything to read here ... */
 168
 169         return 0;
 170 }
 171
 172 static int vt_allocate(int vtnr) {
 173         int fd, r;
 174         char *p;
 175
 176         assert(vtnr >= 1);
 177
 178         if (asprintf(&p, "/dev/tty%i", vtnr) < 0)
 179                 return -ENOMEM;
 180
 181         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 182         free(p);
 183
 184         r = fd < 0 ? -errno : 0;
 185
 186         if (fd >= 0)
 187                 close_nointr_nofail(fd);
 188
 189         return r;
 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("Failed to preallocate VT %i: %s", i, strerror(-q));
 213                         r = q;
 214                 }
 215         }
 216
 217         return r;
 218 }
 219
 220 int seat_apply_acls(Seat *s, Session *old_active) {
 221         int r;
 222
 223         assert(s);
 224
 225         r = devnode_acl_all(s->manager->udev,
 226                             s->id,
 227                             false,
 228                             !!old_active, old_active ? old_active->user->uid : 0,
 229                             !!s->active, s->active ? s->active->user->uid : 0);
 230
 231         if (r < 0)
 232                 log_error("Failed to apply ACLs: %s", strerror(-r));
 233
 234         return r;
 235 }
 236
 237 int seat_set_active(Seat *s, Session *session) {
 238         Session *old_active;
 239
 240         assert(s);
 241         assert(!session || session->seat == s);
 242
 243         if (session == s->active)
 244                 return 0;
 245
 246         old_active = s->active;
 247         s->active = session;
 248
 249         if (old_active) {
 250                 session_device_pause_all(old_active);
 251                 session_send_changed(old_active, "Active\0");
 252         }
 253
 254         seat_apply_acls(s, old_active);
 255
 256         if (session && session->started) {
 257                 session_send_changed(session, "Active\0");
 258                 session_device_resume_all(session);
 259         }
 260
 261         if (!session || session->started)
 262                 seat_send_changed(s, "ActiveSession\0");
 263
 264         seat_save(s);
 265
 266         if (session) {
 267                 session_save(session);
 268                 user_save(session->user);
 269         }
 270
 271         if (old_active) {
 272                 session_save(old_active);
 273                 if (!session || session->user != old_active->user)
 274                         user_save(old_active->user);
 275         }
 276
 277         return 0;
 278 }
 279
 280 int seat_active_vt_changed(Seat *s, int vtnr) {
 281         Session *i, *new_active = NULL;
 282         int r;
 283
 284         assert(s);
 285         assert(vtnr >= 1);
 286
 287         if (!seat_has_vts(s))
 288                 return -EINVAL;
 289
 290         log_debug("VT changed to %i", vtnr);
 291
 292         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 293                 if (i->vtnr == vtnr) {
 294                         new_active = i;
 295                         break;
 296                 }
 297
 298         r = seat_set_active(s, new_active);
 299         manager_spawn_autovt(s->manager, vtnr);
 300
 301         return r;
 302 }
 303
 304 int seat_read_active_vt(Seat *s) {
 305         char t[64];
 306         ssize_t k;
 307         int r, vtnr;
 308
 309         assert(s);
 310
 311         if (!seat_has_vts(s))
 312                 return 0;
 313
 314         lseek(s->manager->console_active_fd, SEEK_SET, 0);
 315
 316         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 317         if (k <= 0) {
 318                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 319                 return k < 0 ? -errno : -EIO;
 320         }
 321
 322         t[k] = 0;
 323         truncate_nl(t);
 324
 325         if (!startswith(t, "tty")) {
 326                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 327                 return -EIO;
 328         }
 329
 330         r = safe_atoi(t+3, &vtnr);
 331         if (r < 0) {
 332                 log_error("Failed to parse VT number %s", t+3);
 333                 return r;
 334         }
 335
 336         if (vtnr <= 0) {
 337                 log_error("VT number invalid: %s", t+3);
 338                 return -EIO;
 339         }
 340
 341         return seat_active_vt_changed(s, vtnr);
 342 }
 343
 344 int seat_start(Seat *s) {
 345         assert(s);
 346
 347         if (s->started)
 348                 return 0;
 349
 350         log_struct(LOG_INFO,
 351                    MESSAGE_ID(SD_MESSAGE_SEAT_START),
 352                    "SEAT_ID=%s", s->id,
 353                    "MESSAGE=New seat %s.", s->id,
 354                    NULL);
 355
 356         /* Initialize VT magic stuff */
 357         seat_preallocate_vts(s);
 358
 359         /* Read current VT */
 360         seat_read_active_vt(s);
 361
 362         s->started = true;
 363
 364         /* Save seat data */
 365         seat_save(s);
 366
 367         seat_send_signal(s, true);
 368
 369         return 0;
 370 }
 371
 372 int seat_stop(Seat *s) {
 373         int r = 0;
 374
 375         assert(s);
 376
 377         if (s->started)
 378                 log_struct(LOG_INFO,
 379                            MESSAGE_ID(SD_MESSAGE_SEAT_STOP),
 380                            "SEAT_ID=%s", s->id,
 381                            "MESSAGE=Removed seat %s.", s->id,
 382                            NULL);
 383
 384         seat_stop_sessions(s);
 385
 386         unlink(s->state_file);
 387         seat_add_to_gc_queue(s);
 388
 389         if (s->started)
 390                 seat_send_signal(s, false);
 391
 392         s->started = false;
 393
 394         return r;
 395 }
 396
 397 int seat_stop_sessions(Seat *s) {
 398         Session *session;
 399         int r = 0, k;
 400
 401         assert(s);
 402
 403         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 404                 k = session_stop(session);
 405                 if (k < 0)
 406                         r = k;
 407         }
 408
 409         return r;
 410 }
 411
 412 int seat_attach_session(Seat *s, Session *session) {
 413         assert(s);
 414         assert(session);
 415         assert(!session->seat);
 416
 417         session->seat = s;
 418         LIST_PREPEND(Session, sessions_by_seat, s->sessions, session);
 419
 420         seat_send_changed(s, "Sessions\0");
 421
 422         /* On seats with VTs, the VT logic defines which session is active. On
 423          * seats without VTs, we automatically activate the first session. */
 424         if (!seat_has_vts(s) && !s->active)
 425                 seat_set_active(s, session);
 426
 427         return 0;
 428 }
 429
 430 void seat_complete_switch(Seat *s) {
 431         Session *session;
 432
 433         assert(s);
 434
 435         /* if no session-switch is pending or if it got canceled, do nothing */
 436         if (!s->pending_switch)
 437                 return;
 438
 439         session = s->pending_switch;
 440         s->pending_switch = NULL;
 441
 442         seat_set_active(s, session);
 443 }
 444
 445 bool seat_has_vts(Seat *s) {
 446         assert(s);
 447
 448         return seat_is_seat0(s) && s->manager->console_active_fd >= 0;
 449 }
 450
 451 bool seat_is_seat0(Seat *s) {
 452         assert(s);
 453
 454         return s->manager->seat0 == s;
 455 }
 456
 457 bool seat_can_multi_session(Seat *s) {
 458         assert(s);
 459
 460         return seat_has_vts(s);
 461 }
 462
 463 bool seat_can_tty(Seat *s) {
 464         assert(s);
 465
 466         return seat_has_vts(s);
 467 }
 468
 469 bool seat_has_master_device(Seat *s) {
 470         assert(s);
 471
 472         /* device list is ordered by "master" flag */
 473         return !!s->devices && s->devices->master;
 474 }
 475
 476 bool seat_can_graphical(Seat *s) {
 477         assert(s);
 478
 479         return seat_has_master_device(s);
 480 }
 481
 482 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 483         Session *session;
 484         bool idle_hint = true;
 485         dual_timestamp ts = { 0, 0 };
 486
 487         assert(s);
 488
 489         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 490                 dual_timestamp k;
 491                 int ih;
 492
 493                 ih = session_get_idle_hint(session, &k);
 494                 if (ih < 0)
 495                         return ih;
 496
 497                 if (!ih) {
 498                         if (!idle_hint) {
 499                                 if (k.monotonic > ts.monotonic)
 500                                         ts = k;
 501                         } else {
 502                                 idle_hint = false;
 503                                 ts = k;
 504                         }
 505                 } else if (idle_hint) {
 506
 507                         if (k.monotonic > ts.monotonic)
 508                                 ts = k;
 509                 }
 510         }
 511
 512         if (t)
 513                 *t = ts;
 514
 515         return idle_hint;
 516 }
 517
 518 int seat_check_gc(Seat *s, bool drop_not_started) {
 519         assert(s);
 520
 521         if (drop_not_started && !s->started)
 522                 return 0;
 523
 524         if (seat_is_seat0(s))
 525                 return 1;
 526
 527         return seat_has_master_device(s);
 528 }
 529
 530 void seat_add_to_gc_queue(Seat *s) {
 531         assert(s);
 532
 533         if (s->in_gc_queue)
 534                 return;
 535
 536         LIST_PREPEND(Seat, gc_queue, s->manager->seat_gc_queue, s);
 537         s->in_gc_queue = true;
 538 }
 539
 540 static bool seat_name_valid_char(char c) {
 541         return
 542                 (c >= 'a' && c <= 'z') ||
 543                 (c >= 'A' && c <= 'Z') ||
 544                 (c >= '0' && c <= '9') ||
 545                 c == '-' ||
 546                 c == '_';
 547 }
 548
 549 bool seat_name_is_valid(const char *name) {
 550         const char *p;
 551
 552         assert(name);
 553
 554         if (!startswith(name, "seat"))
 555                 return false;
 556
 557         if (!name[4])
 558                 return false;
 559
 560         for (p = name; *p; p++)
 561                 if (!seat_name_valid_char(*p))
 562                         return false;
 563
 564         if (strlen(name) > 255)
 565                 return false;
 566
 567         return true;
 568 }