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_VTCONSOLE=%i\n"
 109                 "CAN_MULTI_SESSION=%i\n"
 110                 "CAN_TTY=%i\n"
 111                 "CAN_GRAPHICAL=%i\n",
 112                 seat_is_vtconsole(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_can_multi_session(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         seat_apply_acls(s, old_active);
 250
 251         if (session && session->started)
 252                 session_send_changed(session, "Active\0");
 253
 254         if (!session || session->started)
 255                 seat_send_changed(s, "ActiveSession\0");
 256
 257         seat_save(s);
 258
 259         if (session) {
 260                 session_save(session);
 261                 user_save(session->user);
 262         }
 263
 264         if (old_active) {
 265                 session_save(old_active);
 266                 if (!session || session->user != old_active->user)
 267                         user_save(old_active->user);
 268         }
 269
 270         return 0;
 271 }
 272
 273 int seat_active_vt_changed(Seat *s, int vtnr) {
 274         Session *i, *new_active = NULL;
 275         int r;
 276
 277         assert(s);
 278         assert(vtnr >= 1);
 279
 280         if (!seat_can_multi_session(s))
 281                 return -EINVAL;
 282
 283         log_debug("VT changed to %i", vtnr);
 284
 285         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 286                 if (i->vtnr == vtnr) {
 287                         new_active = i;
 288                         break;
 289                 }
 290
 291         r = seat_set_active(s, new_active);
 292         manager_spawn_autovt(s->manager, vtnr);
 293
 294         return r;
 295 }
 296
 297 int seat_read_active_vt(Seat *s) {
 298         char t[64];
 299         ssize_t k;
 300         int r, vtnr;
 301
 302         assert(s);
 303
 304         if (!seat_can_multi_session(s))
 305                 return 0;
 306
 307         lseek(s->manager->console_active_fd, SEEK_SET, 0);
 308
 309         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 310         if (k <= 0) {
 311                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 312                 return k < 0 ? -errno : -EIO;
 313         }
 314
 315         t[k] = 0;
 316         truncate_nl(t);
 317
 318         if (!startswith(t, "tty")) {
 319                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 320                 return -EIO;
 321         }
 322
 323         r = safe_atoi(t+3, &vtnr);
 324         if (r < 0) {
 325                 log_error("Failed to parse VT number %s", t+3);
 326                 return r;
 327         }
 328
 329         if (vtnr <= 0) {
 330                 log_error("VT number invalid: %s", t+3);
 331                 return -EIO;
 332         }
 333
 334         return seat_active_vt_changed(s, vtnr);
 335 }
 336
 337 int seat_start(Seat *s) {
 338         assert(s);
 339
 340         if (s->started)
 341                 return 0;
 342
 343         log_struct(LOG_INFO,
 344                    MESSAGE_ID(SD_MESSAGE_SEAT_START),
 345                    "SEAT_ID=%s", s->id,
 346                    "MESSAGE=New seat %s.", s->id,
 347                    NULL);
 348
 349         /* Initialize VT magic stuff */
 350         seat_preallocate_vts(s);
 351
 352         /* Read current VT */
 353         seat_read_active_vt(s);
 354
 355         s->started = true;
 356
 357         /* Save seat data */
 358         seat_save(s);
 359
 360         seat_send_signal(s, true);
 361
 362         return 0;
 363 }
 364
 365 int seat_stop(Seat *s) {
 366         int r = 0;
 367
 368         assert(s);
 369
 370         if (s->started)
 371                 log_struct(LOG_INFO,
 372                            MESSAGE_ID(SD_MESSAGE_SEAT_STOP),
 373                            "SEAT_ID=%s", s->id,
 374                            "MESSAGE=Removed seat %s.", s->id,
 375                            NULL);
 376
 377         seat_stop_sessions(s);
 378
 379         unlink(s->state_file);
 380         seat_add_to_gc_queue(s);
 381
 382         if (s->started)
 383                 seat_send_signal(s, false);
 384
 385         s->started = false;
 386
 387         return r;
 388 }
 389
 390 int seat_stop_sessions(Seat *s) {
 391         Session *session;
 392         int r = 0, k;
 393
 394         assert(s);
 395
 396         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 397                 k = session_stop(session);
 398                 if (k < 0)
 399                         r = k;
 400         }
 401
 402         return r;
 403 }
 404
 405 int seat_attach_session(Seat *s, Session *session) {
 406         assert(s);
 407         assert(session);
 408         assert(!session->seat);
 409
 410         session->seat = s;
 411         LIST_PREPEND(Session, sessions_by_seat, s->sessions, session);
 412
 413         seat_send_changed(s, "Sessions\0");
 414
 415         /* Note that even if a seat is not multi-session capable it
 416          * still might have multiple sessions on it since old, dead
 417          * sessions might continue to be tracked until all their
 418          * processes are gone. The most recently added session
 419          * (i.e. the first in s->sessions) is the one that matters. */
 420
 421         if (!seat_can_multi_session(s))
 422                 seat_set_active(s, session);
 423
 424         return 0;
 425 }
 426
 427 bool seat_is_vtconsole(Seat *s) {
 428         assert(s);
 429
 430         return s->manager->vtconsole == s;
 431 }
 432
 433 bool seat_can_multi_session(Seat *s) {
 434         assert(s);
 435
 436         if (!seat_is_vtconsole(s))
 437                 return false;
 438
 439         /* If we can't watch which VT is in the foreground, we don't
 440          * support VT switching */
 441
 442         return s->manager->console_active_fd >= 0;
 443 }
 444
 445 bool seat_can_tty(Seat *s) {
 446         assert(s);
 447
 448         return seat_is_vtconsole(s);
 449 }
 450
 451 bool seat_can_graphical(Seat *s) {
 452         assert(s);
 453
 454         return !!s->devices;
 455 }
 456
 457 int seat_get_idle_hint(Seat *s, dual_timestamp *t) {
 458         Session *session;
 459         bool idle_hint = true;
 460         dual_timestamp ts = { 0, 0 };
 461
 462         assert(s);
 463
 464         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 465                 dual_timestamp k;
 466                 int ih;
 467
 468                 ih = session_get_idle_hint(session, &k);
 469                 if (ih < 0)
 470                         return ih;
 471
 472                 if (!ih) {
 473                         if (!idle_hint) {
 474                                 if (k.monotonic > ts.monotonic)
 475                                         ts = k;
 476                         } else {
 477                                 idle_hint = false;
 478                                 ts = k;
 479                         }
 480                 } else if (idle_hint) {
 481
 482                         if (k.monotonic > ts.monotonic)
 483                                 ts = k;
 484                 }
 485         }
 486
 487         if (t)
 488                 *t = ts;
 489
 490         return idle_hint;
 491 }
 492
 493 int seat_check_gc(Seat *s, bool drop_not_started) {
 494         assert(s);
 495
 496         if (drop_not_started && !s->started)
 497                 return 0;
 498
 499         if (seat_is_vtconsole(s))
 500                 return 1;
 501
 502         return !!s->devices;
 503 }
 504
 505 void seat_add_to_gc_queue(Seat *s) {
 506         assert(s);
 507
 508         if (s->in_gc_queue)
 509                 return;
 510
 511         LIST_PREPEND(Seat, gc_queue, s->manager->seat_gc_queue, s);
 512         s->in_gc_queue = true;
 513 }
 514
 515 static bool seat_name_valid_char(char c) {
 516         return
 517                 (c >= 'a' && c <= 'z') ||
 518                 (c >= 'A' && c <= 'Z') ||
 519                 (c >= '0' && c <= '9') ||
 520                 c == '-' ||
 521                 c == '_';
 522 }
 523
 524 bool seat_name_is_valid(const char *name) {
 525         const char *p;
 526
 527         assert(name);
 528
 529         if (!startswith(name, "seat"))
 530                 return false;
 531
 532         if (!name[4])
 533                 return false;
 534
 535         for (p = name; *p; p++)
 536                 if (!seat_name_valid_char(*p))
 537                         return false;
 538
 539         if (strlen(name) > 255)
 540                 return false;
 541
 542         return true;
 543 }