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
 252         seat_apply_acls(s, old_active);
 253
 254         if (session && session->started) {
 255                 session_send_changed(session, "Active\0");
 256                 session_device_resume_all(session);
 257         }
 258
 259         if (!session || session->started)
 260                 seat_send_changed(s, "ActiveSession\0");
 261
 262         seat_save(s);
 263
 264         if (session) {
 265                 session_save(session);
 266                 user_save(session->user);
 267         }
 268
 269         if (old_active) {
 270                 session_save(old_active);
 271                 if (!session || session->user != old_active->user)
 272                         user_save(old_active->user);
 273         }
 274
 275         return 0;
 276 }
 277
 278 int seat_active_vt_changed(Seat *s, int vtnr) {
 279         Session *i, *new_active = NULL;
 280         int r;
 281
 282         assert(s);
 283         assert(vtnr >= 1);
 284
 285         if (!seat_has_vts(s))
 286                 return -EINVAL;
 287
 288         log_debug("VT changed to %i", vtnr);
 289
 290         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 291                 if (i->vtnr == vtnr) {
 292                         new_active = i;
 293                         break;
 294                 }
 295
 296         r = seat_set_active(s, new_active);
 297         manager_spawn_autovt(s->manager, vtnr);
 298
 299         return r;
 300 }
 301
 302 int seat_read_active_vt(Seat *s) {
 303         char t[64];
 304         ssize_t k;
 305         int r, vtnr;
 306
 307         assert(s);
 308
 309         if (!seat_has_vts(s))
 310                 return 0;
 311
 312         lseek(s->manager->console_active_fd, SEEK_SET, 0);
 313
 314         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 315         if (k <= 0) {
 316                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 317                 return k < 0 ? -errno : -EIO;
 318         }
 319
 320         t[k] = 0;
 321         truncate_nl(t);
 322
 323         if (!startswith(t, "tty")) {
 324                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 325                 return -EIO;
 326         }
 327
 328         r = safe_atoi(t+3, &vtnr);
 329         if (r < 0) {
 330                 log_error("Failed to parse VT number %s", t+3);
 331                 return r;
 332         }
 333
 334         if (vtnr <= 0) {
 335                 log_error("VT number invalid: %s", t+3);
 336                 return -EIO;
 337         }
 338
 339         return seat_active_vt_changed(s, vtnr);
 340 }
 341
 342 int seat_start(Seat *s) {
 343         assert(s);
 344
 345         if (s->started)
 346                 return 0;
 347
 348         log_struct(LOG_INFO,
 349                    MESSAGE_ID(SD_MESSAGE_SEAT_START),
 350                    "SEAT_ID=%s", s->id,
 351                    "MESSAGE=New seat %s.", s->id,
 352                    NULL);
 353
 354         /* Initialize VT magic stuff */
 355         seat_preallocate_vts(s);
 356
 357         /* Read current VT */
 358         seat_read_active_vt(s);
 359
 360         s->started = true;
 361
 362         /* Save seat data */
 363         seat_save(s);
 364
 365         seat_send_signal(s, true);
 366
 367         return 0;
 368 }
 369
 370 int seat_stop(Seat *s) {
 371         int r = 0;
 372
 373         assert(s);
 374
 375         if (s->started)
 376                 log_struct(LOG_INFO,
 377                            MESSAGE_ID(SD_MESSAGE_SEAT_STOP),
 378                            "SEAT_ID=%s", s->id,
 379                            "MESSAGE=Removed seat %s.", s->id,
 380                            NULL);
 381
 382         seat_stop_sessions(s);
 383
 384         unlink(s->state_file);
 385         seat_add_to_gc_queue(s);
 386
 387         if (s->started)
 388                 seat_send_signal(s, false);
 389
 390         s->started = false;
 391
 392         return r;
 393 }
 394
 395 int seat_stop_sessions(Seat *s) {
 396         Session *session;
 397         int r = 0, k;
 398
 399         assert(s);
 400
 401         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 402                 k = session_stop(session);
 403                 if (k < 0)
 404                         r = k;
 405         }
 406
 407         return r;
 408 }
 409
 410 int seat_attach_session(Seat *s, Session *session) {
 411         assert(s);
 412         assert(session);
 413         assert(!session->seat);
 414
 415         session->seat = s;
 416         LIST_PREPEND(Session, sessions_by_seat, s->sessions, session);
 417
 418         seat_send_changed(s, "Sessions\0");
 419
 420         /* On seats with VTs, the VT logic defines which session is active. On
 421          * seats without VTs, we automatically activate the first session. */
 422         if (!seat_has_vts(s) && !s->active)
 423                 seat_set_active(s, session);
 424
 425         return 0;
 426 }
 427
 428 bool seat_has_vts(Seat *s) {
 429         assert(s);
 430
 431         return seat_is_seat0(s) && s->manager->console_active_fd >= 0;
 432 }
 433
 434 bool seat_is_seat0(Seat *s) {
 435         assert(s);
 436
 437         return s->manager->seat0 == s;
 438 }
 439
 440 bool seat_can_multi_session(Seat *s) {
 441         assert(s);
 442
 443         return seat_has_vts(s);
 444 }
 445
 446 bool seat_can_tty(Seat *s) {
 447         assert(s);
 448
 449         return seat_has_vts(s);
 450 }
 451
 452 bool seat_has_master_device(Seat *s) {
 453         assert(s);
 454
 455         /* device list is ordered by "master" flag */
 456         return !!s->devices && s->devices->master;
 457 }
 458
 459 bool seat_can_graphical(Seat *s) {
 460         assert(s);
 461
 462         return seat_has_master_device(s);
 463 }
 464
 465 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 466         Session *session;
 467         bool idle_hint = true;
 468         dual_timestamp ts = { 0, 0 };
 469
 470         assert(s);
 471
 472         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 473                 dual_timestamp k;
 474                 int ih;
 475
 476                 ih = session_get_idle_hint(session, &k);
 477                 if (ih < 0)
 478                         return ih;
 479
 480                 if (!ih) {
 481                         if (!idle_hint) {
 482                                 if (k.monotonic > ts.monotonic)
 483                                         ts = k;
 484                         } else {
 485                                 idle_hint = false;
 486                                 ts = k;
 487                         }
 488                 } else if (idle_hint) {
 489
 490                         if (k.monotonic > ts.monotonic)
 491                                 ts = k;
 492                 }
 493         }
 494
 495         if (t)
 496                 *t = ts;
 497
 498         return idle_hint;
 499 }
 500
 501 int seat_check_gc(Seat *s, bool drop_not_started) {
 502         assert(s);
 503
 504         if (drop_not_started && !s->started)
 505                 return 0;
 506
 507         if (seat_is_seat0(s))
 508                 return 1;
 509
 510         return seat_has_master_device(s);
 511 }
 512
 513 void seat_add_to_gc_queue(Seat *s) {
 514         assert(s);
 515
 516         if (s->in_gc_queue)
 517                 return;
 518
 519         LIST_PREPEND(Seat, gc_queue, s->manager->seat_gc_queue, s);
 520         s->in_gc_queue = true;
 521 }
 522
 523 static bool seat_name_valid_char(char c) {
 524         return
 525                 (c >= 'a' && c <= 'z') ||
 526                 (c >= 'A' && c <= 'Z') ||
 527                 (c >= '0' && c <= '9') ||
 528                 c == '-' ||
 529                 c == '_';
 530 }
 531
 532 bool seat_name_is_valid(const char *name) {
 533         const char *p;
 534
 535         assert(name);
 536
 537         if (!startswith(name, "seat"))
 538                 return false;
 539
 540         if (!name[4])
 541                 return false;
 542
 543         for (p = name; *p; p++)
 544                 if (!seat_name_valid_char(*p))
 545                         return false;
 546
 547         if (strlen(name) > 255)
 548                 return false;
 549
 550         return true;
 551 }