src/login/logind-session.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 <errno.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include <sys/epoll.h>
  26 #include <fcntl.h>
  27
  28 #include "strv.h"
  29 #include "util.h"
  30 #include "mkdir.h"
  31 #include "cgroup-util.h"
  32 #include "logind-session.h"
  33
  34 #define IDLE_THRESHOLD_USEC (5*USEC_PER_MINUTE)
  35
  36 Session* session_new(Manager *m, User *u, const char *id) {
  37         Session *s;
  38
  39         assert(m);
  40         assert(id);
  41
  42         s = new0(Session, 1);
  43         if (!s)
  44                 return NULL;
  45
  46         s->state_file = strappend("/run/systemd/sessions/", id);
  47         if (!s->state_file) {
  48                 free(s);
  49                 return NULL;
  50         }
  51
  52         s->id = file_name_from_path(s->state_file);
  53
  54         if (hashmap_put(m->sessions, s->id, s) < 0) {
  55                 free(s->state_file);
  56                 free(s);
  57                 return NULL;
  58         }
  59
  60         s->manager = m;
  61         s->fifo_fd = -1;
  62         s->user = u;
  63
  64         LIST_PREPEND(Session, sessions_by_user, u->sessions, s);
  65
  66         return s;
  67 }
  68
  69 void session_free(Session *s) {
  70         assert(s);
  71
  72         if (s->in_gc_queue)
  73                 LIST_REMOVE(Session, gc_queue, s->manager->session_gc_queue, s);
  74
  75         if (s->user) {
  76                 LIST_REMOVE(Session, sessions_by_user, s->user->sessions, s);
  77
  78                 if (s->user->display == s)
  79                         s->user->display = NULL;
  80         }
  81
  82         if (s->seat) {
  83                 if (s->seat->active == s)
  84                         s->seat->active = NULL;
  85
  86                 LIST_REMOVE(Session, sessions_by_seat, s->seat->sessions, s);
  87         }
  88
  89         if (s->cgroup_path)
  90                 hashmap_remove(s->manager->cgroups, s->cgroup_path);
  91
  92         free(s->cgroup_path);
  93         strv_free(s->controllers);
  94
  95         free(s->tty);
  96         free(s->display);
  97         free(s->remote_host);
  98         free(s->remote_user);
  99         free(s->service);
 100
 101         hashmap_remove(s->manager->sessions, s->id);
 102         session_remove_fifo(s);
 103
 104         free(s->state_file);
 105         free(s);
 106 }
 107
 108 int session_save(Session *s) {
 109         FILE *f;
 110         int r = 0;
 111         char *temp_path;
 112
 113         assert(s);
 114
 115         if (!s->started)
 116                 return 0;
 117
 118         r = safe_mkdir("/run/systemd/sessions", 0755, 0, 0);
 119         if (r < 0)
 120                 goto finish;
 121
 122         r = fopen_temporary(s->state_file, &f, &temp_path);
 123         if (r < 0)
 124                 goto finish;
 125
 126         assert(s->user);
 127
 128         fchmod(fileno(f), 0644);
 129
 130         fprintf(f,
 131                 "# This is private data. Do not parse.\n"
 132                 "UID=%lu\n"
 133                 "USER=%s\n"
 134                 "ACTIVE=%i\n"
 135                 "REMOTE=%i\n"
 136                 "KILL_PROCESSES=%i\n",
 137                 (unsigned long) s->user->uid,
 138                 s->user->name,
 139                 session_is_active(s),
 140                 s->remote,
 141                 s->kill_processes);
 142
 143         if (s->type >= 0)
 144                 fprintf(f,
 145                         "TYPE=%s\n",
 146                         session_type_to_string(s->type));
 147
 148         if (s->class >= 0)
 149                 fprintf(f,
 150                         "CLASS=%s\n",
 151                         session_class_to_string(s->class));
 152
 153         if (s->cgroup_path)
 154                 fprintf(f,
 155                         "CGROUP=%s\n",
 156                         s->cgroup_path);
 157
 158         if (s->fifo_path)
 159                 fprintf(f,
 160                         "FIFO=%s\n",
 161                         s->fifo_path);
 162
 163         if (s->seat)
 164                 fprintf(f,
 165                         "SEAT=%s\n",
 166                         s->seat->id);
 167
 168         if (s->tty)
 169                 fprintf(f,
 170                         "TTY=%s\n",
 171                         s->tty);
 172
 173         if (s->display)
 174                 fprintf(f,
 175                         "DISPLAY=%s\n",
 176                         s->display);
 177
 178         if (s->remote_host)
 179                 fprintf(f,
 180                         "REMOTE_HOST=%s\n",
 181                         s->remote_host);
 182
 183         if (s->remote_user)
 184                 fprintf(f,
 185                         "REMOTE_USER=%s\n",
 186                         s->remote_user);
 187
 188         if (s->service)
 189                 fprintf(f,
 190                         "SERVICE=%s\n",
 191                         s->service);
 192
 193         if (s->seat && seat_can_multi_session(s->seat))
 194                 fprintf(f,
 195                         "VTNR=%i\n",
 196                         s->vtnr);
 197
 198         if (s->leader > 0)
 199                 fprintf(f,
 200                         "LEADER=%lu\n",
 201                         (unsigned long) s->leader);
 202
 203         if (s->audit_id > 0)
 204                 fprintf(f,
 205                         "AUDIT=%llu\n",
 206                         (unsigned long long) s->audit_id);
 207
 208         fflush(f);
 209
 210         if (ferror(f) || rename(temp_path, s->state_file) < 0) {
 211                 r = -errno;
 212                 unlink(s->state_file);
 213                 unlink(temp_path);
 214         }
 215
 216         fclose(f);
 217         free(temp_path);
 218
 219 finish:
 220         if (r < 0)
 221                 log_error("Failed to save session data for %s: %s", s->id, strerror(-r));
 222
 223         return r;
 224 }
 225
 226 int session_load(Session *s) {
 227         char *remote = NULL,
 228                 *kill_processes = NULL,
 229                 *seat = NULL,
 230                 *vtnr = NULL,
 231                 *leader = NULL,
 232                 *audit_id = NULL,
 233                 *type = NULL,
 234                 *class = NULL;
 235
 236         int k, r;
 237
 238         assert(s);
 239
 240         r = parse_env_file(s->state_file, NEWLINE,
 241                            "REMOTE",         &remote,
 242                            "KILL_PROCESSES", &kill_processes,
 243                            "CGROUP",         &s->cgroup_path,
 244                            "FIFO",           &s->fifo_path,
 245                            "SEAT",           &seat,
 246                            "TTY",            &s->tty,
 247                            "DISPLAY",        &s->display,
 248                            "REMOTE_HOST",    &s->remote_host,
 249                            "REMOTE_USER",    &s->remote_user,
 250                            "SERVICE",        &s->service,
 251                            "VTNR",           &vtnr,
 252                            "LEADER",         &leader,
 253                            "TYPE",           &type,
 254                            "CLASS",          &class,
 255                            NULL);
 256
 257         if (r < 0)
 258                 goto finish;
 259
 260         if (remote) {
 261                 k = parse_boolean(remote);
 262                 if (k >= 0)
 263                         s->remote = k;
 264         }
 265
 266         if (kill_processes) {
 267                 k = parse_boolean(kill_processes);
 268                 if (k >= 0)
 269                         s->kill_processes = k;
 270         }
 271
 272         if (seat && !s->seat) {
 273                 Seat *o;
 274
 275                 o = hashmap_get(s->manager->seats, seat);
 276                 if (o)
 277                         seat_attach_session(o, s);
 278         }
 279
 280         if (vtnr && s->seat && seat_can_multi_session(s->seat)) {
 281                 int v;
 282
 283                 k = safe_atoi(vtnr, &v);
 284                 if (k >= 0 && v >= 1)
 285                         s->vtnr = v;
 286         }
 287
 288         if (leader) {
 289                 k = parse_pid(leader, &s->leader);
 290                 if (k >= 0)
 291                         audit_session_from_pid(s->leader, &s->audit_id);
 292         }
 293
 294         if (type) {
 295                 SessionType t;
 296
 297                 t = session_type_from_string(type);
 298                 if (t >= 0)
 299                         s->type = t;
 300         }
 301
 302         if (class) {
 303                 SessionClass c;
 304
 305                 c = session_class_from_string(class);
 306                 if (c >= 0)
 307                         s->class = c;
 308         }
 309
 310         if (s->fifo_path) {
 311                 int fd;
 312
 313                 /* If we open an unopened pipe for reading we will not
 314                    get an EOF. to trigger an EOF we hence open it for
 315                    reading, but close it right-away which then will
 316                    trigger the EOF. */
 317
 318                 fd = session_create_fifo(s);
 319                 if (fd >= 0)
 320                         close_nointr_nofail(fd);
 321         }
 322
 323 finish:
 324         free(remote);
 325         free(kill_processes);
 326         free(seat);
 327         free(vtnr);
 328         free(leader);
 329         free(audit_id);
 330
 331         return r;
 332 }
 333
 334 int session_activate(Session *s) {
 335         int r;
 336
 337         assert(s);
 338
 339         if (s->vtnr < 0)
 340                 return -ENOTSUP;
 341
 342         if (!s->seat)
 343                 return -ENOTSUP;
 344
 345         if (s->seat->active == s)
 346                 return 0;
 347
 348         assert(seat_is_vtconsole(s->seat));
 349
 350         r = chvt(s->vtnr);
 351         if (r < 0)
 352                 return r;
 353
 354         return seat_set_active(s->seat, s);
 355 }
 356
 357 static int session_link_x11_socket(Session *s) {
 358         char *t, *f, *c;
 359         size_t k;
 360
 361         assert(s);
 362         assert(s->user);
 363         assert(s->user->runtime_path);
 364
 365         if (s->user->display)
 366                 return 0;
 367
 368         if (!s->display || !display_is_local(s->display))
 369                 return 0;
 370
 371         k = strspn(s->display+1, "0123456789");
 372         f = new(char, sizeof("/tmp/.X11-unix/X") + k);
 373         if (!f) {
 374                 log_error("Out of memory");
 375                 return -ENOMEM;
 376         }
 377
 378         c = stpcpy(f, "/tmp/.X11-unix/X");
 379         memcpy(c, s->display+1, k);
 380         c[k] = 0;
 381
 382         if (access(f, F_OK) < 0) {
 383                 log_warning("Session %s has display %s with nonexisting socket %s.", s->id, s->display, f);
 384                 free(f);
 385                 return -ENOENT;
 386         }
 387
 388         /* Note that this cannot be in a subdir to avoid
 389          * vulnerabilities since we are privileged but the runtime
 390          * path is owned by the user */
 391
 392         t = strappend(s->user->runtime_path, "/X11-display");
 393         if (!t) {
 394                 log_error("Out of memory");
 395                 free(f);
 396                 return -ENOMEM;
 397         }
 398
 399         if (link(f, t) < 0) {
 400                 if (errno == EEXIST) {
 401                         unlink(t);
 402
 403                         if (link(f, t) >= 0)
 404                                 goto done;
 405                 }
 406
 407                 if (symlink(f, t) < 0) {
 408
 409                         if (errno == EEXIST) {
 410                                 unlink(t);
 411
 412                                 if (symlink(f, t) >= 0)
 413                                         goto done;
 414                         }
 415
 416                         log_error("Failed to link %s to %s: %m", f, t);
 417                         free(f);
 418                         free(t);
 419                         return -errno;
 420                 }
 421         }
 422
 423 done:
 424         log_info("Linked %s to %s.", f, t);
 425         free(f);
 426         free(t);
 427
 428         s->user->display = s;
 429
 430         return 0;
 431 }
 432
 433 static int session_create_one_group(Session *s, const char *controller, const char *path) {
 434         int r;
 435
 436         assert(s);
 437         assert(controller);
 438         assert(path);
 439
 440         if (s->leader > 0) {
 441                 r = cg_create_and_attach(controller, path, s->leader);
 442                 if (r < 0)
 443                         r = cg_create(controller, path);
 444         } else
 445                 r = cg_create(controller, path);
 446
 447         if (r < 0)
 448                 return r;
 449
 450         r = cg_set_task_access(controller, path, 0644, s->user->uid, s->user->gid, -1);
 451         if (r >= 0)
 452                 r = cg_set_group_access(controller, path, 0755, s->user->uid, s->user->gid);
 453
 454         return r;
 455 }
 456
 457 static int session_create_cgroup(Session *s) {
 458         char **k;
 459         char *p;
 460         int r;
 461
 462         assert(s);
 463         assert(s->user);
 464         assert(s->user->cgroup_path);
 465
 466         if (!s->cgroup_path) {
 467                 if (asprintf(&p, "%s/%s", s->user->cgroup_path, s->id) < 0) {
 468                         log_error("Out of memory");
 469                         return -ENOMEM;
 470                 }
 471         } else
 472                 p = s->cgroup_path;
 473
 474         r = session_create_one_group(s, SYSTEMD_CGROUP_CONTROLLER, p);
 475         if (r < 0) {
 476                 log_error("Failed to create "SYSTEMD_CGROUP_CONTROLLER":%s: %s", p, strerror(-r));
 477                 free(p);
 478                 s->cgroup_path = NULL;
 479                 return r;
 480         }
 481
 482         s->cgroup_path = p;
 483
 484         STRV_FOREACH(k, s->controllers) {
 485
 486                 if (strv_contains(s->reset_controllers, *k))
 487                         continue;
 488
 489                 r = session_create_one_group(s, *k, p);
 490                 if (r < 0)
 491                         log_warning("Failed to create %s:%s: %s", *k, p, strerror(-r));
 492         }
 493
 494         STRV_FOREACH(k, s->manager->controllers) {
 495
 496                 if (strv_contains(s->reset_controllers, *k) ||
 497                     strv_contains(s->manager->reset_controllers, *k) ||
 498                     strv_contains(s->controllers, *k))
 499                         continue;
 500
 501                 r = session_create_one_group(s, *k, p);
 502                 if (r < 0)
 503                         log_warning("Failed to create %s:%s: %s", *k, p, strerror(-r));
 504         }
 505
 506         if (s->leader > 0) {
 507
 508                 STRV_FOREACH(k, s->reset_controllers) {
 509                         r = cg_attach(*k, "/", s->leader);
 510                         if (r < 0)
 511                                 log_warning("Failed to reset controller %s: %s", *k, strerror(-r));
 512
 513                 }
 514
 515                 STRV_FOREACH(k, s->manager->reset_controllers) {
 516
 517                         if (strv_contains(s->reset_controllers, *k) ||
 518                             strv_contains(s->controllers, *k))
 519                                 continue;
 520
 521                         r = cg_attach(*k, "/", s->leader);
 522                         if (r < 0)
 523                                 log_warning("Failed to reset controller %s: %s", *k, strerror(-r));
 524
 525                 }
 526         }
 527
 528         hashmap_put(s->manager->cgroups, s->cgroup_path, s);
 529
 530         return 0;
 531 }
 532
 533 int session_start(Session *s) {
 534         int r;
 535
 536         assert(s);
 537         assert(s->user);
 538
 539         if (s->started)
 540                 return 0;
 541
 542         r = user_start(s->user);
 543         if (r < 0)
 544                 return r;
 545
 546         log_full(s->type == SESSION_TTY || s->type == SESSION_X11 ? LOG_INFO : LOG_DEBUG,
 547                  "New session %s of user %s.", s->id, s->user->name);
 548
 549         /* Create cgroup */
 550         r = session_create_cgroup(s);
 551         if (r < 0)
 552                 return r;
 553
 554         /* Create X11 symlink */
 555         session_link_x11_socket(s);
 556
 557         dual_timestamp_get(&s->timestamp);
 558
 559         if (s->seat)
 560                 seat_read_active_vt(s->seat);
 561
 562         s->started = true;
 563
 564         /* Save session data */
 565         session_save(s);
 566         user_save(s->user);
 567
 568         session_send_signal(s, true);
 569
 570         if (s->seat) {
 571                 seat_save(s->seat);
 572
 573                 if (s->seat->active == s)
 574                         seat_send_changed(s->seat, "Sessions\0ActiveSession\0");
 575                 else
 576                         seat_send_changed(s->seat, "Sessions\0");
 577         }
 578
 579         user_send_changed(s->user, "Sessions\0");
 580
 581         return 0;
 582 }
 583
 584 static bool session_shall_kill(Session *s) {
 585         assert(s);
 586
 587         if (!s->kill_processes)
 588                 return false;
 589
 590         if (strv_contains(s->manager->kill_exclude_users, s->user->name))
 591                 return false;
 592
 593         if (strv_isempty(s->manager->kill_only_users))
 594                 return true;
 595
 596         return strv_contains(s->manager->kill_only_users, s->user->name);
 597 }
 598
 599 static int session_terminate_cgroup(Session *s) {
 600         int r;
 601         char **k;
 602
 603         assert(s);
 604
 605         if (!s->cgroup_path)
 606                 return 0;
 607
 608         cg_trim(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_path, false);
 609
 610         if (session_shall_kill(s)) {
 611
 612                 r = cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_path, true);
 613                 if (r < 0)
 614                         log_error("Failed to kill session cgroup: %s", strerror(-r));
 615
 616         } else {
 617                 if (s->leader > 0) {
 618                         Session *t;
 619
 620                         /* We still send a HUP to the leader process,
 621                          * even if we are not supposed to kill the
 622                          * whole cgroup. But let's first check the
 623                          * leader still exists and belongs to our
 624                          * session... */
 625
 626                         r = manager_get_session_by_pid(s->manager, s->leader, &t);
 627                         if (r > 0 && t == s) {
 628                                 kill(s->leader, SIGTERM); /* for normal processes */
 629                                 kill(s->leader, SIGHUP);  /* for shells */
 630                                 kill(s->leader, SIGCONT); /* in case they are stopped */
 631                         }
 632                 }
 633
 634                 r = cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_path, true);
 635                 if (r < 0)
 636                         log_error("Failed to check session cgroup: %s", strerror(-r));
 637                 else if (r > 0) {
 638                         r = cg_delete(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_path);
 639                         if (r < 0)
 640                                 log_error("Failed to delete session cgroup: %s", strerror(-r));
 641                 }
 642         }
 643
 644         STRV_FOREACH(k, s->user->manager->controllers)
 645                 cg_trim(*k, s->cgroup_path, true);
 646
 647         hashmap_remove(s->manager->cgroups, s->cgroup_path);
 648
 649         free(s->cgroup_path);
 650         s->cgroup_path = NULL;
 651
 652         return 0;
 653 }
 654
 655 static int session_unlink_x11_socket(Session *s) {
 656         char *t;
 657         int r;
 658
 659         assert(s);
 660         assert(s->user);
 661
 662         if (s->user->display != s)
 663                 return 0;
 664
 665         s->user->display = NULL;
 666
 667         t = strappend(s->user->runtime_path, "/X11-display");
 668         if (!t) {
 669                 log_error("Out of memory");
 670                 return -ENOMEM;
 671         }
 672
 673         r = unlink(t);
 674         free(t);
 675
 676         return r < 0 ? -errno : 0;
 677 }
 678
 679 int session_stop(Session *s) {
 680         int r = 0, k;
 681
 682         assert(s);
 683
 684         if (s->started)
 685                 log_full(s->type == SESSION_TTY || s->type == SESSION_X11 ? LOG_INFO : LOG_DEBUG,
 686                          "Removed session %s.", s->id);
 687
 688         /* Kill cgroup */
 689         k = session_terminate_cgroup(s);
 690         if (k < 0)
 691                 r = k;
 692
 693         /* Remove X11 symlink */
 694         session_unlink_x11_socket(s);
 695
 696         unlink(s->state_file);
 697         session_add_to_gc_queue(s);
 698         user_add_to_gc_queue(s->user);
 699
 700         if (s->started)
 701                 session_send_signal(s, false);
 702
 703         if (s->seat) {
 704                 if (s->seat->active == s)
 705                         seat_set_active(s->seat, NULL);
 706
 707                 seat_send_changed(s->seat, "Sessions\0");
 708         }
 709
 710         user_send_changed(s->user, "Sessions\0");
 711
 712         s->started = false;
 713
 714         return r;
 715 }
 716
 717 bool session_is_active(Session *s) {
 718         assert(s);
 719
 720         if (!s->seat)
 721                 return true;
 722
 723         return s->seat->active == s;
 724 }
 725
 726 int session_get_idle_hint(Session *s, dual_timestamp *t) {
 727         char *p;
 728         struct stat st;
 729         usec_t u, n;
 730         bool b;
 731         int k;
 732
 733         assert(s);
 734
 735         if (s->idle_hint) {
 736                 if (t)
 737                         *t = s->idle_hint_timestamp;
 738
 739                 return s->idle_hint;
 740         }
 741
 742         if (isempty(s->tty))
 743                 goto dont_know;
 744
 745         if (s->tty[0] != '/') {
 746                 p = strappend("/dev/", s->tty);
 747                 if (!p)
 748                         return -ENOMEM;
 749         } else
 750                 p = NULL;
 751
 752         if (!startswith(p ? p : s->tty, "/dev/")) {
 753                 free(p);
 754                 goto dont_know;
 755         }
 756
 757         k = lstat(p ? p : s->tty, &st);
 758         free(p);
 759
 760         if (k < 0)
 761                 goto dont_know;
 762
 763         u = timespec_load(&st.st_atim);
 764         n = now(CLOCK_REALTIME);
 765         b = u + IDLE_THRESHOLD_USEC < n;
 766
 767         if (t)
 768                 dual_timestamp_from_realtime(t, u + b ? IDLE_THRESHOLD_USEC : 0);
 769
 770         return b;
 771
 772 dont_know:
 773         if (t)
 774                 *t = s->idle_hint_timestamp;
 775
 776         return 0;
 777 }
 778
 779 void session_set_idle_hint(Session *s, bool b) {
 780         assert(s);
 781
 782         if (s->idle_hint == b)
 783                 return;
 784
 785         s->idle_hint = b;
 786         dual_timestamp_get(&s->idle_hint_timestamp);
 787
 788         session_send_changed(s,
 789                              "IdleHint\0"
 790                              "IdleSinceHint\0"
 791                              "IdleSinceHintMonotonic\0");
 792
 793         if (s->seat)
 794                 seat_send_changed(s->seat,
 795                                   "IdleHint\0"
 796                                   "IdleSinceHint\0"
 797                                   "IdleSinceHintMonotonic\0");
 798
 799         user_send_changed(s->user,
 800                           "IdleHint\0"
 801                           "IdleSinceHint\0"
 802                           "IdleSinceHintMonotonic\0");
 803
 804         manager_send_changed(s->manager,
 805                              "IdleHint\0"
 806                              "IdleSinceHint\0"
 807                              "IdleSinceHintMonotonic\0");
 808 }
 809
 810 int session_create_fifo(Session *s) {
 811         int r;
 812
 813         assert(s);
 814
 815         /* Create FIFO */
 816         if (!s->fifo_path) {
 817                 r = safe_mkdir("/run/systemd/sessions", 0755, 0, 0);
 818                 if (r < 0)
 819                         return r;
 820
 821                 if (asprintf(&s->fifo_path, "/run/systemd/sessions/%s.ref", s->id) < 0)
 822                         return -ENOMEM;
 823
 824                 if (mkfifo(s->fifo_path, 0600) < 0 && errno != EEXIST)
 825                         return -errno;
 826         }
 827
 828         /* Open reading side */
 829         if (s->fifo_fd < 0) {
 830                 struct epoll_event ev;
 831
 832                 s->fifo_fd = open(s->fifo_path, O_RDONLY|O_CLOEXEC|O_NDELAY);
 833                 if (s->fifo_fd < 0)
 834                         return -errno;
 835
 836                 r = hashmap_put(s->manager->session_fds, INT_TO_PTR(s->fifo_fd + 1), s);
 837                 if (r < 0)
 838                         return r;
 839
 840                 zero(ev);
 841                 ev.events = 0;
 842                 ev.data.u32 = FD_FIFO_BASE + s->fifo_fd;
 843
 844                 if (epoll_ctl(s->manager->epoll_fd, EPOLL_CTL_ADD, s->fifo_fd, &ev) < 0)
 845                         return -errno;
 846         }
 847
 848         /* Open writing side */
 849         r = open(s->fifo_path, O_WRONLY|O_CLOEXEC|O_NDELAY);
 850         if (r < 0)
 851                 return -errno;
 852
 853         return r;
 854 }
 855
 856 void session_remove_fifo(Session *s) {
 857         assert(s);
 858
 859         if (s->fifo_fd >= 0) {
 860                 assert_se(hashmap_remove(s->manager->session_fds, INT_TO_PTR(s->fifo_fd + 1)) == s);
 861                 assert_se(epoll_ctl(s->manager->epoll_fd, EPOLL_CTL_DEL, s->fifo_fd, NULL) == 0);
 862                 close_nointr_nofail(s->fifo_fd);
 863                 s->fifo_fd = -1;
 864         }
 865
 866         if (s->fifo_path) {
 867                 unlink(s->fifo_path);
 868                 free(s->fifo_path);
 869                 s->fifo_path = NULL;
 870         }
 871 }
 872
 873 int session_check_gc(Session *s, bool drop_not_started) {
 874         int r;
 875
 876         assert(s);
 877
 878         if (drop_not_started && !s->started)
 879                 return 0;
 880
 881         if (s->fifo_fd >= 0) {
 882
 883                 r = pipe_eof(s->fifo_fd);
 884                 if (r < 0)
 885                         return r;
 886
 887                 if (r == 0)
 888                         return 1;
 889         }
 890
 891         if (s->cgroup_path) {
 892
 893                 r = cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_path, false);
 894                 if (r < 0)
 895                         return r;
 896
 897                 if (r <= 0)
 898                         return 1;
 899         }
 900
 901         return 0;
 902 }
 903
 904 void session_add_to_gc_queue(Session *s) {
 905         assert(s);
 906
 907         if (s->in_gc_queue)
 908                 return;
 909
 910         LIST_PREPEND(Session, gc_queue, s->manager->session_gc_queue, s);
 911         s->in_gc_queue = true;
 912 }
 913
 914 int session_kill(Session *s, KillWho who, int signo) {
 915         int r = 0;
 916         Set *pid_set = NULL;
 917
 918         assert(s);
 919
 920         if (!s->cgroup_path)
 921                 return -ESRCH;
 922
 923         if (s->leader <= 0 && who == KILL_LEADER)
 924                 return -ESRCH;
 925
 926         if (s->leader > 0)
 927                 if (kill(s->leader, signo) < 0)
 928                         r = -errno;
 929
 930         if (who == KILL_ALL) {
 931                 int q;
 932
 933                 pid_set = set_new(trivial_hash_func, trivial_compare_func);
 934                 if (!pid_set)
 935                         return -ENOMEM;
 936
 937                 if (s->leader > 0) {
 938                         q = set_put(pid_set, LONG_TO_PTR(s->leader));
 939                         if (q < 0)
 940                                 r = q;
 941                 }
 942
 943                 q = cg_kill_recursive(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_path, signo, false, true, false, pid_set);
 944                 if (q < 0)
 945                         if (q != -EAGAIN && q != -ESRCH && q != -ENOENT)
 946                                 r = q;
 947         }
 948
 949         if (pid_set)
 950                 set_free(pid_set);
 951
 952         return r;
 953 }
 954
 955 static const char* const session_type_table[_SESSION_TYPE_MAX] = {
 956         [SESSION_TTY] = "tty",
 957         [SESSION_X11] = "x11",
 958         [SESSION_UNSPECIFIED] = "unspecified"
 959 };
 960
 961 DEFINE_STRING_TABLE_LOOKUP(session_type, SessionType);
 962
 963 static const char* const session_class_table[_SESSION_CLASS_MAX] = {
 964         [SESSION_USER] = "user",
 965         [SESSION_GREETER] = "greeter",
 966         [SESSION_LOCK_SCREEN] = "lock-screen"
 967 };
 968
 969 DEFINE_STRING_TABLE_LOOKUP(session_class, SessionClass);
 970
 971 static const char* const kill_who_table[_KILL_WHO_MAX] = {
 972         [KILL_LEADER] = "leader",
 973         [KILL_ALL] = "all"
 974 };
 975
 976 DEFINE_STRING_TABLE_LOOKUP(kill_who, KillWho);