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 "logind-seat.h"
  31 #include "logind-acl.h"
  32 #include "util.h"
  33 #include "mkdir.h"
  34
  35 Seat *seat_new(Manager *m, const char *id) {
  36         Seat *s;
  37
  38         assert(m);
  39         assert(id);
  40
  41         s = new0(Seat, 1);
  42         if (!s)
  43                 return NULL;
  44
  45         s->state_file = strappend("/run/systemd/seats/", id);
  46         if (!s->state_file) {
  47                 free(s);
  48                 return NULL;
  49         }
  50
  51         s->id = file_name_from_path(s->state_file);
  52         s->manager = m;
  53
  54         if (hashmap_put(m->seats, s->id, s) < 0) {
  55                 free(s->state_file);
  56                 free(s);
  57                 return NULL;
  58         }
  59
  60         return s;
  61 }
  62
  63 void seat_free(Seat *s) {
  64         assert(s);
  65
  66         if (s->in_gc_queue)
  67                 LIST_REMOVE(Seat, gc_queue, s->manager->seat_gc_queue, s);
  68
  69         while (s->sessions)
  70                 session_free(s->sessions);
  71
  72         assert(!s->active);
  73
  74         while (s->devices)
  75                 device_free(s->devices);
  76
  77         hashmap_remove(s->manager->seats, s->id);
  78
  79         free(s->state_file);
  80         free(s);
  81 }
  82
  83 int seat_save(Seat *s) {
  84         int r;
  85         FILE *f;
  86         char *temp_path;
  87
  88         assert(s);
  89
  90         if (!s->started)
  91                 return 0;
  92
  93         r = safe_mkdir("/run/systemd/seats", 0755, 0, 0);
  94         if (r < 0)
  95                 goto finish;
  96
  97         r = fopen_temporary(s->state_file, &f, &temp_path);
  98         if (r < 0)
  99                 goto finish;
 100
 101         fchmod(fileno(f), 0644);
 102
 103         fprintf(f,
 104                 "# This is private data. Do not parse.\n"
 105                 "IS_VTCONSOLE=%i\n"
 106                 "CAN_MULTI_SESSION=%i\n",
 107                 seat_is_vtconsole(s),
 108                 seat_can_multi_session(s));
 109
 110         if (s->active) {
 111                 assert(s->active->user);
 112
 113                 fprintf(f,
 114                         "ACTIVE=%s\n"
 115                         "ACTIVE_UID=%lu\n",
 116                         s->active->id,
 117                         (unsigned long) s->active->user->uid);
 118         }
 119
 120         if (s->sessions) {
 121                 Session *i;
 122
 123                 fputs("SESSIONS=", f);
 124                 LIST_FOREACH(sessions_by_seat, i, s->sessions) {
 125                         fprintf(f,
 126                                 "%s%c",
 127                                 i->id,
 128                                 i->sessions_by_seat_next ? ' ' : '\n');
 129                 }
 130
 131                 fputs("UIDS=", f);
 132                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 133                         fprintf(f,
 134                                 "%lu%c",
 135                                 (unsigned long) i->user->uid,
 136                                 i->sessions_by_seat_next ? ' ' : '\n');
 137         }
 138
 139         fflush(f);
 140
 141         if (ferror(f) || rename(temp_path, s->state_file) < 0) {
 142                 r = -errno;
 143                 unlink(s->state_file);
 144                 unlink(temp_path);
 145         }
 146
 147         fclose(f);
 148         free(temp_path);
 149
 150 finish:
 151         if (r < 0)
 152                 log_error("Failed to save seat data for %s: %s", s->id, strerror(-r));
 153
 154         return r;
 155 }
 156
 157 int seat_load(Seat *s) {
 158         assert(s);
 159
 160         /* There isn't actually anything to read here ... */
 161
 162         return 0;
 163 }
 164
 165 static int vt_allocate(int vtnr) {
 166         int fd, r;
 167         char *p;
 168
 169         assert(vtnr >= 1);
 170
 171         if (asprintf(&p, "/dev/tty%i", vtnr) < 0)
 172                 return -ENOMEM;
 173
 174         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 175         free(p);
 176
 177         r = fd < 0 ? -errno : 0;
 178
 179         if (fd >= 0)
 180                 close_nointr_nofail(fd);
 181
 182         return r;
 183 }
 184
 185 int seat_preallocate_vts(Seat *s) {
 186         int r = 0;
 187         unsigned i;
 188
 189         assert(s);
 190         assert(s->manager);
 191
 192         log_debug("Preallocating VTs...");
 193
 194         if (s->manager->n_autovts <= 0)
 195                 return 0;
 196
 197         if (!seat_can_multi_session(s))
 198                 return 0;
 199
 200         for (i = 1; i <= s->manager->n_autovts; i++) {
 201                 int q;
 202
 203                 q = vt_allocate(i);
 204                 if (q < 0) {
 205                         log_error("Failed to preallocate VT %i: %s", i, strerror(-q));
 206                         r = q;
 207                 }
 208         }
 209
 210         return r;
 211 }
 212
 213 int seat_apply_acls(Seat *s, Session *old_active) {
 214         int r;
 215
 216         assert(s);
 217
 218         r = devnode_acl_all(s->manager->udev,
 219                             s->id,
 220                             false,
 221                             !!old_active, old_active ? old_active->user->uid : 0,
 222                             !!s->active, s->active ? s->active->user->uid : 0);
 223
 224         if (r < 0)
 225                 log_error("Failed to apply ACLs: %s", strerror(-r));
 226
 227         return r;
 228 }
 229
 230 int seat_set_active(Seat *s, Session *session) {
 231         Session *old_active;
 232
 233         assert(s);
 234         assert(!session || session->seat == s);
 235
 236         if (session == s->active)
 237                 return 0;
 238
 239         old_active = s->active;
 240         s->active = session;
 241
 242         seat_apply_acls(s, old_active);
 243
 244         if (session && session->started)
 245                 session_send_changed(session, "Active\0");
 246
 247         if (!session || session->started)
 248                 seat_send_changed(s, "ActiveSession\0");
 249
 250         seat_save(s);
 251
 252         if (session) {
 253                 session_save(session);
 254                 user_save(session->user);
 255         }
 256
 257         if (old_active) {
 258                 session_save(old_active);
 259                 user_save(old_active->user);
 260         }
 261
 262         return 0;
 263 }
 264
 265 int seat_active_vt_changed(Seat *s, int vtnr) {
 266         Session *i, *new_active = NULL;
 267         int r;
 268
 269         assert(s);
 270         assert(vtnr >= 1);
 271
 272         if (!seat_can_multi_session(s))
 273                 return -EINVAL;
 274
 275         log_debug("VT changed to %i", vtnr);
 276
 277         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 278                 if (i->vtnr == vtnr) {
 279                         new_active = i;
 280                         break;
 281                 }
 282
 283         r = seat_set_active(s, new_active);
 284         manager_spawn_autovt(s->manager, vtnr);
 285
 286         return r;
 287 }
 288
 289 int seat_read_active_vt(Seat *s) {
 290         char t[64];
 291         ssize_t k;
 292         int r, vtnr;
 293
 294         assert(s);
 295
 296         if (!seat_can_multi_session(s))
 297                 return 0;
 298
 299         lseek(s->manager->console_active_fd, SEEK_SET, 0);
 300
 301         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 302         if (k <= 0) {
 303                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 304                 return k < 0 ? -errno : -EIO;
 305         }
 306
 307         t[k] = 0;
 308         truncate_nl(t);
 309
 310         if (!startswith(t, "tty")) {
 311                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 312                 return -EIO;
 313         }
 314
 315         r = safe_atoi(t+3, &vtnr);
 316         if (r < 0) {
 317                 log_error("Failed to parse VT number %s", t+3);
 318                 return r;
 319         }
 320
 321         if (vtnr <= 0) {
 322                 log_error("VT number invalid: %s", t+3);
 323                 return -EIO;
 324         }
 325
 326         return seat_active_vt_changed(s, vtnr);
 327 }
 328
 329 int seat_start(Seat *s) {
 330         assert(s);
 331
 332         if (s->started)
 333                 return 0;
 334
 335         log_info("New seat %s.", s->id);
 336
 337         /* Initialize VT magic stuff */
 338         seat_preallocate_vts(s);
 339
 340         /* Read current VT */
 341         seat_read_active_vt(s);
 342
 343         s->started = true;
 344
 345         /* Save seat data */
 346         seat_save(s);
 347
 348         seat_send_signal(s, true);
 349
 350         return 0;
 351 }
 352
 353 int seat_stop(Seat *s) {
 354         int r = 0;
 355
 356         assert(s);
 357
 358         if (s->started)
 359                 log_info("Removed seat %s.", s->id);
 360
 361         seat_stop_sessions(s);
 362
 363         unlink(s->state_file);
 364         seat_add_to_gc_queue(s);
 365
 366         if (s->started)
 367                 seat_send_signal(s, false);
 368
 369         s->started = false;
 370
 371         return r;
 372 }
 373
 374 int seat_stop_sessions(Seat *s) {
 375         Session *session;
 376         int r = 0, k;
 377
 378         assert(s);
 379
 380         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 381                 k = session_stop(session);
 382                 if (k < 0)
 383                         r = k;
 384         }
 385
 386         return r;
 387 }
 388
 389 int seat_attach_session(Seat *s, Session *session) {
 390         assert(s);
 391         assert(session);
 392         assert(!session->seat);
 393
 394         session->seat = s;
 395         LIST_PREPEND(Session, sessions_by_seat, s->sessions, session);
 396
 397         seat_send_changed(s, "Sessions\0");
 398
 399         /* Note that even if a seat is not multi-session capable it
 400          * still might have multiple sessions on it since old, dead
 401          * sessions might continue to be tracked until all their
 402          * processes are gone. The most recently added session
 403          * (i.e. the first in s->sessions) is the one that matters. */
 404
 405         if (!seat_can_multi_session(s))
 406                 seat_set_active(s, session);
 407
 408         return 0;
 409 }
 410
 411 bool seat_is_vtconsole(Seat *s) {
 412         assert(s);
 413
 414         return s->manager->vtconsole == s;
 415 }
 416
 417 bool seat_can_multi_session(Seat *s) {
 418         assert(s);
 419
 420         if (!seat_is_vtconsole(s))
 421                 return false;
 422
 423         /* If we can't watch which VT is in the foreground, we don't
 424          * support VT switching */
 425
 426         return s->manager->console_active_fd >= 0;
 427 }
 428
 429 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 430         Session *session;
 431         bool idle_hint = true;
 432         dual_timestamp ts = { 0, 0 };
 433
 434         assert(s);
 435
 436         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 437                 dual_timestamp k;
 438                 int ih;
 439
 440                 ih = session_get_idle_hint(session, &k);
 441                 if (ih < 0)
 442                         return ih;
 443
 444                 if (!ih) {
 445                         if (!idle_hint) {
 446                                 if (k.monotonic < ts.monotonic)
 447                                         ts = k;
 448                         } else {
 449                                 idle_hint = false;
 450                                 ts = k;
 451                         }
 452                 } else if (idle_hint) {
 453
 454                         if (k.monotonic > ts.monotonic)
 455                                 ts = k;
 456                 }
 457         }
 458
 459         if (t)
 460                 *t = ts;
 461
 462         return idle_hint;
 463 }
 464
 465 int seat_check_gc(Seat *s, bool drop_not_started) {
 466         assert(s);
 467
 468         if (drop_not_started && !s->started)
 469                 return 0;
 470
 471         if (seat_is_vtconsole(s))
 472                 return 1;
 473
 474         return !!s->devices;
 475 }
 476
 477 void seat_add_to_gc_queue(Seat *s) {
 478         assert(s);
 479
 480         if (s->in_gc_queue)
 481                 return;
 482
 483         LIST_PREPEND(Seat, gc_queue, s->manager->seat_gc_queue, s);
 484         s->in_gc_queue = true;
 485 }
 486
 487 static bool seat_name_valid_char(char c) {
 488         return
 489                 (c >= 'a' && c <= 'z') ||
 490                 (c >= 'A' && c <= 'Z') ||
 491                 (c >= '0' && c <= '9') ||
 492                 c == '-' ||
 493                 c == '_';
 494 }
 495
 496 bool seat_name_is_valid(const char *name) {
 497         const char *p;
 498
 499         assert(name);
 500
 501         if (!startswith(name, "seat"))
 502                 return false;
 503
 504         if (!name[4])
 505                 return false;
 506
 507         for (p = name; *p; p++)
 508                 if (!seat_name_valid_char(*p))
 509                         return false;
 510
 511         if (strlen(name) > 255)
 512                 return false;
 513
 514         return true;
 515 }