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 #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 }