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 #include "path-util.h"
  35
  36 Seat *seat_new(Manager *m, const char *id) {
  37         Seat *s;
  38
  39         assert(m);
  40         assert(id);
  41
  42         s = new0(Seat, 1);
  43         if (!s)
  44                 return NULL;
  45
  46         s->state_file = strappend("/run/systemd/seats/", id);
  47         if (!s->state_file) {
  48                 free(s);
  49                 return NULL;
  50         }
  51
  52         s->id = path_get_file_name(s->state_file);
  53         s->manager = m;
  54
  55         if (hashmap_put(m->seats, s->id, s) < 0) {
  56                 free(s->state_file);
  57                 free(s);
  58                 return NULL;
  59         }
  60
  61         return s;
  62 }
  63
  64 void seat_free(Seat *s) {
  65         assert(s);
  66
  67         if (s->in_gc_queue)
  68                 LIST_REMOVE(Seat, gc_queue, s->manager->seat_gc_queue, s);
  69
  70         while (s->sessions)
  71                 session_free(s->sessions);
  72
  73         assert(!s->active);
  74
  75         while (s->devices)
  76                 device_free(s->devices);
  77
  78         hashmap_remove(s->manager->seats, s->id);
  79
  80         free(s->state_file);
  81         free(s);
  82 }
  83
  84 int seat_save(Seat *s) {
  85         int r;
  86         FILE *f;
  87         char *temp_path;
  88
  89         assert(s);
  90
  91         if (!s->started)
  92                 return 0;
  93
  94         r = mkdir_safe_label("/run/systemd/seats", 0755, 0, 0);
  95         if (r < 0)
  96                 goto finish;
  97
  98         r = fopen_temporary(s->state_file, &f, &temp_path);
  99         if (r < 0)
 100                 goto finish;
 101
 102         fchmod(fileno(f), 0644);
 103
 104         fprintf(f,
 105                 "# This is private data. Do not parse.\n"
 106                 "IS_VTCONSOLE=%i\n"
 107                 "CAN_MULTI_SESSION=%i\n",
 108                 seat_is_vtconsole(s),
 109                 seat_can_multi_session(s));
 110
 111         if (s->active) {
 112                 assert(s->active->user);
 113
 114                 fprintf(f,
 115                         "ACTIVE=%s\n"
 116                         "ACTIVE_UID=%lu\n",
 117                         s->active->id,
 118                         (unsigned long) s->active->user->uid);
 119         }
 120
 121         if (s->sessions) {
 122                 Session *i;
 123
 124                 fputs("SESSIONS=", f);
 125                 LIST_FOREACH(sessions_by_seat, i, s->sessions) {
 126                         fprintf(f,
 127                                 "%s%c",
 128                                 i->id,
 129                                 i->sessions_by_seat_next ? ' ' : '\n');
 130                 }
 131
 132                 fputs("UIDS=", f);
 133                 LIST_FOREACH(sessions_by_seat, i, s->sessions)
 134                         fprintf(f,
 135                                 "%lu%c",
 136                                 (unsigned long) i->user->uid,
 137                                 i->sessions_by_seat_next ? ' ' : '\n');
 138         }
 139
 140         fflush(f);
 141
 142         if (ferror(f) || rename(temp_path, s->state_file) < 0) {
 143                 r = -errno;
 144                 unlink(s->state_file);
 145                 unlink(temp_path);
 146         }
 147
 148         fclose(f);
 149         free(temp_path);
 150
 151 finish:
 152         if (r < 0)
 153                 log_error("Failed to save seat data for %s: %s", s->id, strerror(-r));
 154
 155         return r;
 156 }
 157
 158 int seat_load(Seat *s) {
 159         assert(s);
 160
 161         /* There isn't actually anything to read here ... */
 162
 163         return 0;
 164 }
 165
 166 static int vt_allocate(int vtnr) {
 167         int fd, r;
 168         char *p;
 169
 170         assert(vtnr >= 1);
 171
 172         if (asprintf(&p, "/dev/tty%i", vtnr) < 0)
 173                 return -ENOMEM;
 174
 175         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 176         free(p);
 177
 178         r = fd < 0 ? -errno : 0;
 179
 180         if (fd >= 0)
 181                 close_nointr_nofail(fd);
 182
 183         return r;
 184 }
 185
 186 int seat_preallocate_vts(Seat *s) {
 187         int r = 0;
 188         unsigned i;
 189
 190         assert(s);
 191         assert(s->manager);
 192
 193         log_debug("Preallocating VTs...");
 194
 195         if (s->manager->n_autovts <= 0)
 196                 return 0;
 197
 198         if (!seat_can_multi_session(s))
 199                 return 0;
 200
 201         for (i = 1; i <= s->manager->n_autovts; i++) {
 202                 int q;
 203
 204                 q = vt_allocate(i);
 205                 if (q < 0) {
 206                         log_error("Failed to preallocate VT %i: %s", i, strerror(-q));
 207                         r = q;
 208                 }
 209         }
 210
 211         return r;
 212 }
 213
 214 int seat_apply_acls(Seat *s, Session *old_active) {
 215         int r;
 216
 217         assert(s);
 218
 219         r = devnode_acl_all(s->manager->udev,
 220                             s->id,
 221                             false,
 222                             !!old_active, old_active ? old_active->user->uid : 0,
 223                             !!s->active, s->active ? s->active->user->uid : 0);
 224
 225         if (r < 0)
 226                 log_error("Failed to apply ACLs: %s", strerror(-r));
 227
 228         return r;
 229 }
 230
 231 int seat_set_active(Seat *s, Session *session) {
 232         Session *old_active;
 233
 234         assert(s);
 235         assert(!session || session->seat == s);
 236
 237         if (session == s->active)
 238                 return 0;
 239
 240         old_active = s->active;
 241         s->active = session;
 242
 243         seat_apply_acls(s, old_active);
 244
 245         if (session && session->started)
 246                 session_send_changed(session, "Active\0");
 247
 248         if (!session || session->started)
 249                 seat_send_changed(s, "ActiveSession\0");
 250
 251         seat_save(s);
 252
 253         if (session) {
 254                 session_save(session);
 255                 user_save(session->user);
 256         }
 257
 258         if (old_active) {
 259                 session_save(old_active);
 260                 user_save(old_active->user);
 261         }
 262
 263         return 0;
 264 }
 265
 266 int seat_active_vt_changed(Seat *s, int vtnr) {
 267         Session *i, *new_active = NULL;
 268         int r;
 269
 270         assert(s);
 271         assert(vtnr >= 1);
 272
 273         if (!seat_can_multi_session(s))
 274                 return -EINVAL;
 275
 276         log_debug("VT changed to %i", vtnr);
 277
 278         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 279                 if (i->vtnr == vtnr) {
 280                         new_active = i;
 281                         break;
 282                 }
 283
 284         r = seat_set_active(s, new_active);
 285         manager_spawn_autovt(s->manager, vtnr);
 286
 287         return r;
 288 }
 289
 290 int seat_read_active_vt(Seat *s) {
 291         char t[64];
 292         ssize_t k;
 293         int r, vtnr;
 294
 295         assert(s);
 296
 297         if (!seat_can_multi_session(s))
 298                 return 0;
 299
 300         lseek(s->manager->console_active_fd, SEEK_SET, 0);
 301
 302         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 303         if (k <= 0) {
 304                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 305                 return k < 0 ? -errno : -EIO;
 306         }
 307
 308         t[k] = 0;
 309         truncate_nl(t);
 310
 311         if (!startswith(t, "tty")) {
 312                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 313                 return -EIO;
 314         }
 315
 316         r = safe_atoi(t+3, &vtnr);
 317         if (r < 0) {
 318                 log_error("Failed to parse VT number %s", t+3);
 319                 return r;
 320         }
 321
 322         if (vtnr <= 0) {
 323                 log_error("VT number invalid: %s", t+3);
 324                 return -EIO;
 325         }
 326
 327         return seat_active_vt_changed(s, vtnr);
 328 }
 329
 330 int seat_start(Seat *s) {
 331         assert(s);
 332
 333         if (s->started)
 334                 return 0;
 335
 336         log_info("New seat %s.", s->id);
 337
 338         /* Initialize VT magic stuff */
 339         seat_preallocate_vts(s);
 340
 341         /* Read current VT */
 342         seat_read_active_vt(s);
 343
 344         s->started = true;
 345
 346         /* Save seat data */
 347         seat_save(s);
 348
 349         seat_send_signal(s, true);
 350
 351         return 0;
 352 }
 353
 354 int seat_stop(Seat *s) {
 355         int r = 0;
 356
 357         assert(s);
 358
 359         if (s->started)
 360                 log_info("Removed seat %s.", s->id);
 361
 362         seat_stop_sessions(s);
 363
 364         unlink(s->state_file);
 365         seat_add_to_gc_queue(s);
 366
 367         if (s->started)
 368                 seat_send_signal(s, false);
 369
 370         s->started = false;
 371
 372         return r;
 373 }
 374
 375 int seat_stop_sessions(Seat *s) {
 376         Session *session;
 377         int r = 0, k;
 378
 379         assert(s);
 380
 381         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 382                 k = session_stop(session);
 383                 if (k < 0)
 384                         r = k;
 385         }
 386
 387         return r;
 388 }
 389
 390 int seat_attach_session(Seat *s, Session *session) {
 391         assert(s);
 392         assert(session);
 393         assert(!session->seat);
 394
 395         session->seat = s;
 396         LIST_PREPEND(Session, sessions_by_seat, s->sessions, session);
 397
 398         seat_send_changed(s, "Sessions\0");
 399
 400         /* Note that even if a seat is not multi-session capable it
 401          * still might have multiple sessions on it since old, dead
 402          * sessions might continue to be tracked until all their
 403          * processes are gone. The most recently added session
 404          * (i.e. the first in s->sessions) is the one that matters. */
 405
 406         if (!seat_can_multi_session(s))
 407                 seat_set_active(s, session);
 408
 409         return 0;
 410 }
 411
 412 bool seat_is_vtconsole(Seat *s) {
 413         assert(s);
 414
 415         return s->manager->vtconsole == s;
 416 }
 417
 418 bool seat_can_multi_session(Seat *s) {
 419         assert(s);
 420
 421         if (!seat_is_vtconsole(s))
 422                 return false;
 423
 424         /* If we can't watch which VT is in the foreground, we don't
 425          * support VT switching */
 426
 427         return s->manager->console_active_fd >= 0;
 428 }
 429
 430 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 431         Session *session;
 432         bool idle_hint = true;
 433         dual_timestamp ts = { 0, 0 };
 434
 435         assert(s);
 436
 437         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 438                 dual_timestamp k;
 439                 int ih;
 440
 441                 ih = session_get_idle_hint(session, &k);
 442                 if (ih < 0)
 443                         return ih;
 444
 445                 if (!ih) {
 446                         if (!idle_hint) {
 447                                 if (k.monotonic < ts.monotonic)
 448                                         ts = k;
 449                         } else {
 450                                 idle_hint = false;
 451                                 ts = k;
 452                         }
 453                 } else if (idle_hint) {
 454
 455                         if (k.monotonic > ts.monotonic)
 456                                 ts = k;
 457                 }
 458         }
 459
 460         if (t)
 461                 *t = ts;
 462
 463         return idle_hint;
 464 }
 465
 466 int seat_check_gc(Seat *s, bool drop_not_started) {
 467         assert(s);
 468
 469         if (drop_not_started && !s->started)
 470                 return 0;
 471
 472         if (seat_is_vtconsole(s))
 473                 return 1;
 474
 475         return !!s->devices;
 476 }
 477
 478 void seat_add_to_gc_queue(Seat *s) {
 479         assert(s);
 480
 481         if (s->in_gc_queue)
 482                 return;
 483
 484         LIST_PREPEND(Seat, gc_queue, s->manager->seat_gc_queue, s);
 485         s->in_gc_queue = true;
 486 }
 487
 488 static bool seat_name_valid_char(char c) {
 489         return
 490                 (c >= 'a' && c <= 'z') ||
 491                 (c >= 'A' && c <= 'Z') ||
 492                 (c >= '0' && c <= '9') ||
 493                 c == '-' ||
 494                 c == '_';
 495 }
 496
 497 bool seat_name_is_valid(const char *name) {
 498         const char *p;
 499
 500         assert(name);
 501
 502         if (!startswith(name, "seat"))
 503                 return false;
 504
 505         if (!name[4])
 506                 return false;
 507
 508         for (p = name; *p; p++)
 509                 if (!seat_name_valid_char(*p))
 510                         return false;
 511
 512         if (strlen(name) > 255)
 513                 return false;
 514
 515         return true;
 516 }