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 General Public License as published by
  10   the Free Software Foundation; either version 2 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   General Public License for more details.
  17
  18   You should have received a copy of the GNU 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 "logind-seat.h"
  31 #include "logind-acl.h"
  32 #include "util.h"
  33
  34 Seat *seat_new(Manager *m, const char *id) {
  35         Seat *s;
  36
  37         assert(m);
  38         assert(id);
  39
  40         s = new0(Seat, 1);
  41         if (!s)
  42                 return NULL;
  43
  44         s->state_file = strappend("/run/systemd/seats/", id);
  45         if (!s->state_file) {
  46                 free(s);
  47                 return NULL;
  48         }
  49
  50         s->id = file_name_from_path(s->state_file);
  51         s->manager = m;
  52
  53         if (hashmap_put(m->seats, s->id, s) < 0) {
  54                 free(s->state_file);
  55                 free(s);
  56                 return NULL;
  57         }
  58
  59         return s;
  60 }
  61
  62 void seat_free(Seat *s) {
  63         assert(s);
  64
  65         if (s->in_gc_queue)
  66                 LIST_REMOVE(Seat, gc_queue, s->manager->seat_gc_queue, s);
  67
  68         while (s->sessions)
  69                 session_free(s->sessions);
  70
  71         assert(!s->active);
  72
  73         while (s->devices)
  74                 device_free(s->devices);
  75
  76         hashmap_remove(s->manager->seats, s->id);
  77
  78         free(s->state_file);
  79         free(s);
  80 }
  81
  82 int seat_save(Seat *s) {
  83         int r;
  84         FILE *f;
  85         char *temp_path;
  86
  87         assert(s);
  88
  89         if (!s->started)
  90                 return 0;
  91
  92         r = safe_mkdir("/run/systemd/seats", 0755, 0, 0);
  93         if (r < 0)
  94                 goto finish;
  95
  96         r = fopen_temporary(s->state_file, &f, &temp_path);
  97         if (r < 0)
  98                 goto finish;
  99
 100         fchmod(fileno(f), 0644);
 101
 102         fprintf(f,
 103                 "# This is private data. Do not parse.\n"
 104                 "IS_VTCONSOLE=%i\n"
 105                 "CAN_MULTI_SESSION=%i\n",
 106                 seat_is_vtconsole(s),
 107                 seat_can_multi_session(s));
 108
 109         if (s->active) {
 110                 assert(s->active->user);
 111
 112                 fprintf(f,
 113                         "ACTIVE=%s\n"
 114                         "ACTIVE_UID=%lu\n",
 115                         s->active->id,
 116                         (unsigned long) s->active->user->uid);
 117         }
 118
 119         if (s->sessions) {
 120                 Session *i;
 121
 122                 fputs("SESSIONS=", f);
 123                 LIST_FOREACH(sessions_by_seat, i, s->sessions) {
 124                         fprintf(f,
 125                                 "%s%c",
 126                                 i->id,
 127                                 i->sessions_by_seat_next ? ' ' : '\n');
 128                 }
 129
 130                 fputs("UIDS=", f);
 131                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 132                         fprintf(f,
 133                                 "%lu%c",
 134                                 (unsigned long) i->user->uid,
 135                                 i->sessions_by_seat_next ? ' ' : '\n');
 136         }
 137
 138         fflush(f);
 139
 140         if (ferror(f) || rename(temp_path, s->state_file) < 0) {
 141                 r = -errno;
 142                 unlink(s->state_file);
 143                 unlink(temp_path);
 144         }
 145
 146         fclose(f);
 147         free(temp_path);
 148
 149 finish:
 150         if (r < 0)
 151                 log_error("Failed to save seat data for %s: %s", s->id, strerror(-r));
 152
 153         return r;
 154 }
 155
 156 int seat_load(Seat *s) {
 157         assert(s);
 158
 159         /* There isn't actually anything to read here ... */
 160
 161         return 0;
 162 }
 163
 164 static int vt_allocate(int vtnr) {
 165         int fd, r;
 166         char *p;
 167
 168         assert(vtnr >= 1);
 169
 170         if (asprintf(&p, "/dev/tty%i", vtnr) < 0)
 171                 return -ENOMEM;
 172
 173         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 174         free(p);
 175
 176         r = fd < 0 ? -errno : 0;
 177
 178         if (fd >= 0)
 179                 close_nointr_nofail(fd);
 180
 181         return r;
 182 }
 183
 184 int seat_preallocate_vts(Seat *s) {
 185         int r = 0;
 186         unsigned i;
 187
 188         assert(s);
 189         assert(s->manager);
 190
 191         log_debug("Preallocating VTs...");
 192
 193         if (s->manager->n_autovts <= 0)
 194                 return 0;
 195
 196         if (!seat_can_multi_session(s))
 197                 return 0;
 198
 199         for (i = 1; i <= s->manager->n_autovts; i++) {
 200                 int q;
 201
 202                 q = vt_allocate(i);
 203                 if (q < 0) {
 204                         log_error("Failed to preallocate VT %i: %s", i, strerror(-q));
 205                         r = q;
 206                 }
 207         }
 208
 209         return r;
 210 }
 211
 212 int seat_apply_acls(Seat *s, Session *old_active) {
 213         int r;
 214
 215         assert(s);
 216
 217         r = devnode_acl_all(s->manager->udev,
 218                             s->id,
 219                             false,
 220                             !!old_active, old_active ? old_active->user->uid : 0,
 221                             !!s->active, s->active ? s->active->user->uid : 0);
 222
 223         if (r < 0)
 224                 log_error("Failed to apply ACLs: %s", strerror(-r));
 225
 226         return r;
 227 }
 228
 229 int seat_set_active(Seat *s, Session *session) {
 230         Session *old_active;
 231
 232         assert(s);
 233         assert(!session || session->seat == s);
 234
 235         if (session == s->active)
 236                 return 0;
 237
 238         old_active = s->active;
 239         s->active = session;
 240
 241         seat_apply_acls(s, old_active);
 242
 243         if (session && session->started)
 244                 session_send_changed(session, "Active\0");
 245
 246         if (!session || session->started)
 247                 seat_send_changed(s, "ActiveSession\0");
 248
 249         seat_save(s);
 250
 251         if (session) {
 252                 session_save(session);
 253                 user_save(session->user);
 254         }
 255
 256         if (old_active) {
 257                 session_save(old_active);
 258                 user_save(old_active->user);
 259         }
 260
 261         return 0;
 262 }
 263
 264 int seat_active_vt_changed(Seat *s, int vtnr) {
 265         Session *i, *new_active = NULL;
 266         int r;
 267
 268         assert(s);
 269         assert(vtnr >= 1);
 270
 271         if (!seat_can_multi_session(s))
 272                 return -EINVAL;
 273
 274         log_debug("VT changed to %i", vtnr);
 275
 276         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 277                 if (i->vtnr == vtnr) {
 278                         new_active = i;
 279                         break;
 280                 }
 281
 282         r = seat_set_active(s, new_active);
 283         manager_spawn_autovt(s->manager, vtnr);
 284
 285         return r;
 286 }
 287
 288 int seat_read_active_vt(Seat *s) {
 289         char t[64];
 290         ssize_t k;
 291         int r, vtnr;
 292
 293         assert(s);
 294
 295         if (!seat_can_multi_session(s))
 296                 return 0;
 297
 298         lseek(s->manager->console_active_fd, SEEK_SET, 0);
 299
 300         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 301         if (k <= 0) {
 302                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 303                 return k < 0 ? -errno : -EIO;
 304         }
 305
 306         t[k] = 0;
 307         truncate_nl(t);
 308
 309         if (!startswith(t, "tty")) {
 310                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 311                 return -EIO;
 312         }
 313
 314         r = safe_atoi(t+3, &vtnr);
 315         if (r < 0) {
 316                 log_error("Failed to parse VT number %s", t+3);
 317                 return r;
 318         }
 319
 320         if (vtnr <= 0) {
 321                 log_error("VT number invalid: %s", t+3);
 322                 return -EIO;
 323         }
 324
 325         return seat_active_vt_changed(s, vtnr);
 326 }
 327
 328 int seat_start(Seat *s) {
 329         assert(s);
 330
 331         if (s->started)
 332                 return 0;
 333
 334         log_info("New seat %s.", s->id);
 335
 336         /* Initialize VT magic stuff */
 337         seat_preallocate_vts(s);
 338
 339         /* Read current VT */
 340         seat_read_active_vt(s);
 341
 342         s->started = true;
 343
 344         /* Save seat data */
 345         seat_save(s);
 346
 347         seat_send_signal(s, true);
 348
 349         return 0;
 350 }
 351
 352 int seat_stop(Seat *s) {
 353         int r = 0;
 354
 355         assert(s);
 356
 357         if (s->started)
 358                 log_info("Removed seat %s.", s->id);
 359
 360         seat_stop_sessions(s);
 361
 362         unlink(s->state_file);
 363         seat_add_to_gc_queue(s);
 364
 365         if (s->started)
 366                 seat_send_signal(s, false);
 367
 368         s->started = false;
 369
 370         return r;
 371 }
 372
 373 int seat_stop_sessions(Seat *s) {
 374         Session *session;
 375         int r = 0, k;
 376
 377         assert(s);
 378
 379         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 380                 k = session_stop(session);
 381                 if (k < 0)
 382                         r = k;
 383         }
 384
 385         return r;
 386 }
 387
 388 int seat_attach_session(Seat *s, Session *session) {
 389         assert(s);
 390         assert(session);
 391         assert(!session->seat);
 392
 393         if (!seat_can_multi_session(s) && s->sessions)
 394                 return -EEXIST;
 395
 396         session->seat = s;
 397         LIST_PREPEND(Session, sessions_by_seat, s->sessions, session);
 398
 399         seat_send_changed(s, "Sessions\0");
 400
 401         if (!seat_can_multi_session(s)) {
 402                 assert(!s->active);
 403                 seat_set_active(s, session);
 404         }
 405
 406         return 0;
 407 }
 408
 409 bool seat_is_vtconsole(Seat *s) {
 410         assert(s);
 411
 412         return s->manager->vtconsole == s;
 413 }
 414
 415 bool seat_can_multi_session(Seat *s) {
 416         assert(s);
 417
 418         if (!seat_is_vtconsole(s))
 419                 return false;
 420
 421         /* If we can't watch which VT is in the foreground, we don't
 422          * support VT switching */
 423
 424         return s->manager->console_active_fd >= 0;
 425 }
 426
 427 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 428         Session *session;
 429         bool idle_hint = true;
 430         dual_timestamp ts = { 0, 0 };
 431
 432         assert(s);
 433
 434         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 435                 dual_timestamp k;
 436                 int ih;
 437
 438                 ih = session_get_idle_hint(session, &k);
 439                 if (ih < 0)
 440                         return ih;
 441
 442                 if (!ih) {
 443                         if (!idle_hint) {
 444                                 if (k.monotonic < ts.monotonic)
 445                                         ts = k;
 446                         } else {
 447                                 idle_hint = false;
 448                                 ts = k;
 449                         }
 450                 } else if (idle_hint) {
 451
 452                         if (k.monotonic > ts.monotonic)
 453                                 ts = k;
 454                 }
 455         }
 456
 457         if (t)
 458                 *t = ts;
 459
 460         return idle_hint;
 461 }
 462
 463 int seat_check_gc(Seat *s, bool drop_not_started) {
 464         assert(s);
 465
 466         if (drop_not_started && !s->started)
 467                 return 0;
 468
 469         if (seat_is_vtconsole(s))
 470                 return 1;
 471
 472         return !!s->devices;
 473 }
 474
 475 void seat_add_to_gc_queue(Seat *s) {
 476         assert(s);
 477
 478         if (s->in_gc_queue)
 479                 return;
 480
 481         LIST_PREPEND(Seat, gc_queue, s->manager->seat_gc_queue, s);
 482         s->in_gc_queue = true;
 483 }
 484
 485 static bool seat_name_valid_char(char c) {
 486         return
 487                 (c >= 'a' && c <= 'z') ||
 488                 (c >= 'A' && c <= 'Z') ||
 489                 (c >= '0' && c <= '9') ||
 490                 c == '-' ||
 491                 c == '_';
 492 }
 493
 494 bool seat_name_is_valid(const char *name) {
 495         const char *p;
 496
 497         assert(name);
 498
 499         if (!startswith(name, "seat"))
 500                 return false;
 501
 502         if (!name[4])
 503                 return false;
 504
 505         for (p = name; *p; p++)
 506                 if (!seat_name_valid_char(*p))
 507                         return false;
 508
 509         if (strlen(name) > 255)
 510                 return false;
 511
 512         return true;
 513 }