src/login/pam_systemd.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <endian.h>
   4 #include <errno.h>
   5 #include <fcntl.h>
   6 #include <pwd.h>
   7 #include <security/_pam_macros.h>
   8 #include <security/pam_ext.h>
   9 #include <security/pam_misc.h>
  10 #include <security/pam_modules.h>
  11 #include <security/pam_modutil.h>
  12 #include <sys/file.h>
  13
  14 #include "alloc-util.h"
  15 #include "audit-util.h"
  16 #include "bus-common-errors.h"
  17 #include "bus-error.h"
  18 #include "bus-util.h"
  19 #include "cgroup-util.h"
  20 #include "def.h"
  21 #include "fd-util.h"
  22 #include "fileio.h"
  23 #include "format-util.h"
  24 #include "hostname-util.h"
  25 #include "login-util.h"
  26 #include "macro.h"
  27 #include "parse-util.h"
  28 #include "path-util.h"
  29 #include "process-util.h"
  30 #include "socket-util.h"
  31 #include "stdio-util.h"
  32 #include "strv.h"
  33 #include "terminal-util.h"
  34 #include "util.h"
  35
  36 static int parse_argv(
  37                 pam_handle_t *handle,
  38                 int argc, const char **argv,
  39                 const char **class,
  40                 const char **type,
  41                 const char **desktop,
  42                 bool *debug) {
  43
  44         unsigned i;
  45
  46         assert(argc >= 0);
  47         assert(argc == 0 || argv);
  48
  49         for (i = 0; i < (unsigned) argc; i++) {
  50                 if (startswith(argv[i], "class=")) {
  51                         if (class)
  52                                 *class = argv[i] + 6;
  53
  54                 } else if (startswith(argv[i], "type=")) {
  55                         if (type)
  56                                 *type = argv[i] + 5;
  57
  58                 } else if (startswith(argv[i], "desktop=")) {
  59                         if (desktop)
  60                                 *desktop = argv[i] + 8;
  61
  62                 } else if (streq(argv[i], "debug")) {
  63                         if (debug)
  64                                 *debug = true;
  65
  66                 } else if (startswith(argv[i], "debug=")) {
  67                         int k;
  68
  69                         k = parse_boolean(argv[i] + 6);
  70                         if (k < 0)
  71                                 pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring.");
  72                         else if (debug)
  73                                 *debug = k;
  74
  75                 } else
  76                         pam_syslog(handle, LOG_WARNING, "Unknown parameter '%s', ignoring", argv[i]);
  77         }
  78
  79         return 0;
  80 }
  81
  82 static int get_user_data(
  83                 pam_handle_t *handle,
  84                 const char **ret_username,
  85                 struct passwd **ret_pw) {
  86
  87         const char *username = NULL;
  88         struct passwd *pw = NULL;
  89         int r;
  90
  91         assert(handle);
  92         assert(ret_username);
  93         assert(ret_pw);
  94
  95         r = pam_get_user(handle, &username, NULL);
  96         if (r != PAM_SUCCESS) {
  97                 pam_syslog(handle, LOG_ERR, "Failed to get user name.");
  98                 return r;
  99         }
 100
 101         if (isempty(username)) {
 102                 pam_syslog(handle, LOG_ERR, "User name not valid.");
 103                 return PAM_AUTH_ERR;
 104         }
 105
 106         pw = pam_modutil_getpwnam(handle, username);
 107         if (!pw) {
 108                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 109                 return PAM_USER_UNKNOWN;
 110         }
 111
 112         *ret_pw = pw;
 113         *ret_username = username;
 114
 115         return PAM_SUCCESS;
 116 }
 117
 118 static int socket_from_display(const char *display, char **path) {
 119         size_t k;
 120         char *f, *c;
 121
 122         assert(display);
 123         assert(path);
 124
 125         if (!display_is_local(display))
 126                 return -EINVAL;
 127
 128         k = strspn(display+1, "0123456789");
 129
 130         f = new(char, STRLEN("/tmp/.X11-unix/X") + k + 1);
 131         if (!f)
 132                 return -ENOMEM;
 133
 134         c = stpcpy(f, "/tmp/.X11-unix/X");
 135         memcpy(c, display+1, k);
 136         c[k] = 0;
 137
 138         *path = f;
 139
 140         return 0;
 141 }
 142
 143 static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
 144         union sockaddr_union sa = {};
 145         _cleanup_free_ char *p = NULL, *tty = NULL;
 146         _cleanup_close_ int fd = -1;
 147         struct ucred ucred;
 148         int v, r, salen;
 149
 150         assert(display);
 151         assert(vtnr);
 152
 153         /* We deduce the X11 socket from the display name, then use
 154          * SO_PEERCRED to determine the X11 server process, ask for
 155          * the controlling tty of that and if it's a VC then we know
 156          * the seat and the virtual terminal. Sounds ugly, is only
 157          * semi-ugly. */
 158
 159         r = socket_from_display(display, &p);
 160         if (r < 0)
 161                 return r;
 162         salen = sockaddr_un_set_path(&sa.un, p);
 163         if (salen < 0)
 164                 return salen;
 165
 166         fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
 167         if (fd < 0)
 168                 return -errno;
 169
 170         if (connect(fd, &sa.sa, salen) < 0)
 171                 return -errno;
 172
 173         r = getpeercred(fd, &ucred);
 174         if (r < 0)
 175                 return r;
 176
 177         r = get_ctty(ucred.pid, NULL, &tty);
 178         if (r < 0)
 179                 return r;
 180
 181         v = vtnr_from_tty(tty);
 182         if (v < 0)
 183                 return v;
 184         else if (v == 0)
 185                 return -ENOENT;
 186
 187         if (seat)
 188                 *seat = "seat0";
 189         *vtnr = (uint32_t) v;
 190
 191         return 0;
 192 }
 193
 194 static int export_legacy_dbus_address(
 195                 pam_handle_t *handle,
 196                 uid_t uid,
 197                 const char *runtime) {
 198
 199         _cleanup_free_ char *s = NULL;
 200         int r = PAM_BUF_ERR;
 201
 202         if (asprintf(&s, DEFAULT_USER_BUS_ADDRESS_FMT, runtime) < 0)
 203                 goto error;
 204
 205         r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", s, 0);
 206         if (r != PAM_SUCCESS)
 207                 goto error;
 208
 209         return PAM_SUCCESS;
 210
 211 error:
 212         pam_syslog(handle, LOG_ERR, "Failed to set bus variable.");
 213         return r;
 214 }
 215
 216 static int append_session_memory_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 217         uint64_t val;
 218         int r;
 219
 220         if (isempty(limit))
 221                 return 0;
 222
 223         if (streq(limit, "infinity")) {
 224                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", (uint64_t)-1);
 225                 if (r < 0) {
 226                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 227                         return r;
 228                 }
 229         } else {
 230                 r = parse_permille(limit);
 231                 if (r >= 0) {
 232                         r = sd_bus_message_append(m, "(sv)", "MemoryMaxScale", "u", (uint32_t) (((uint64_t) r * UINT32_MAX) / 1000U));
 233                         if (r < 0) {
 234                                 pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 235                                 return r;
 236                         }
 237                 } else {
 238                         r = parse_size(limit, 1024, &val);
 239                         if (r >= 0) {
 240                                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", val);
 241                                 if (r < 0) {
 242                                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 243                                         return r;
 244                                 }
 245                         } else
 246                                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.limit: %s, ignoring.", limit);
 247                 }
 248         }
 249
 250         return 0;
 251 }
 252
 253 static int append_session_tasks_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 254         uint64_t val;
 255         int r;
 256
 257         /* No need to parse "infinity" here, it will be set unconditionally later in manager_start_scope() */
 258         if (isempty(limit) || streq(limit, "infinity"))
 259                 return 0;
 260
 261         r = safe_atou64(limit, &val);
 262         if (r >= 0) {
 263                 r = sd_bus_message_append(m, "(sv)", "TasksMax", "t", val);
 264                 if (r < 0) {
 265                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 266                         return r;
 267                 }
 268         } else
 269                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.limit: %s, ignoring.", limit);
 270
 271         return 0;
 272 }
 273
 274 static int append_session_cg_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit, const char *field) {
 275         uint64_t val;
 276         int r;
 277
 278         if (isempty(limit))
 279                 return 0;
 280
 281         r = cg_weight_parse(limit, &val);
 282         if (r >= 0) {
 283                 r = sd_bus_message_append(m, "(sv)", field, "t", val);
 284                 if (r < 0) {
 285                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 286                         return r;
 287                 }
 288         } else if (streq(field, "CPUWeight"))
 289                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.cpu_weight: %s, ignoring.", limit);
 290         else
 291                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.io_weight: %s, ignoring.", limit);
 292
 293         return 0;
 294 }
 295
 296 static const char* getenv_harder(pam_handle_t *handle, const char *key, const char *fallback) {
 297         const char *v;
 298
 299         assert(handle);
 300         assert(key);
 301
 302         /* Looks for an environment variable, preferrably in the environment block associated with the specified PAM
 303          * handle, falling back to the process' block instead. */
 304
 305         v = pam_getenv(handle, key);
 306         if (!isempty(v))
 307                 return v;
 308
 309         v = getenv(key);
 310         if (!isempty(v))
 311                 return v;
 312
 313         return fallback;
 314 }
 315
 316 static int update_environment(pam_handle_t *handle, const char *key, const char *value) {
 317         int r;
 318
 319         assert(handle);
 320         assert(key);
 321
 322         /* Updates the environment, but only if there's actually a value set. Also, log about errors */
 323
 324         if (isempty(value))
 325                 return PAM_SUCCESS;
 326
 327         r = pam_misc_setenv(handle, key, value, 0);
 328         if (r != PAM_SUCCESS)
 329                 pam_syslog(handle, LOG_ERR, "Failed to set environment variable %s.", key);
 330
 331         return r;
 332 }
 333
 334 static bool validate_runtime_directory(pam_handle_t *handle, const char *path, uid_t uid) {
 335         struct stat st;
 336
 337         assert(path);
 338
 339         /* Just some extra paranoia: let's not set $XDG_RUNTIME_DIR if the directory we'd set it to isn't actually set
 340          * up properly for us. */
 341
 342         if (lstat(path, &st) < 0) {
 343                 pam_syslog(handle, LOG_ERR, "Failed to stat() runtime directory '%s': %s", path, strerror(errno));
 344                 goto fail;
 345         }
 346
 347         if (!S_ISDIR(st.st_mode)) {
 348                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not actually a directory.", path);
 349                 goto fail;
 350         }
 351
 352         if (st.st_uid != uid) {
 353                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not owned by UID " UID_FMT ", as it should.", path, uid);
 354                 goto fail;
 355         }
 356
 357         return true;
 358
 359 fail:
 360         pam_syslog(handle, LOG_WARNING, "Not setting $XDG_RUNTIME_DIR, as the directory is not in order.");
 361         return false;
 362 }
 363
 364 _public_ PAM_EXTERN int pam_sm_open_session(
 365                 pam_handle_t *handle,
 366                 int flags,
 367                 int argc, const char **argv) {
 368
 369         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 370         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL, *reply = NULL;
 371         const char
 372                 *username, *id, *object_path, *runtime_path,
 373                 *service = NULL,
 374                 *tty = NULL, *display = NULL,
 375                 *remote_user = NULL, *remote_host = NULL,
 376                 *seat = NULL,
 377                 *type = NULL, *class = NULL,
 378                 *class_pam = NULL, *type_pam = NULL, *cvtnr = NULL, *desktop = NULL, *desktop_pam = NULL,
 379                 *memory_max = NULL, *tasks_max = NULL, *cpu_weight = NULL, *io_weight = NULL;
 380         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 381         int session_fd = -1, existing, r;
 382         bool debug = false, remote;
 383         struct passwd *pw;
 384         uint32_t vtnr = 0;
 385         uid_t original_uid;
 386
 387         assert(handle);
 388
 389         /* Make this a NOP on non-logind systems */
 390         if (!logind_running())
 391                 return PAM_SUCCESS;
 392
 393         if (parse_argv(handle,
 394                        argc, argv,
 395                        &class_pam,
 396                        &type_pam,
 397                        &desktop_pam,
 398                        &debug) < 0)
 399                 return PAM_SESSION_ERR;
 400
 401         if (debug)
 402                 pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing");
 403
 404         r = get_user_data(handle, &username, &pw);
 405         if (r != PAM_SUCCESS) {
 406                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 407                 return r;
 408         }
 409
 410         /* Make sure we don't enter a loop by talking to
 411          * systemd-logind when it is actually waiting for the
 412          * background to finish start-up. If the service is
 413          * "systemd-user" we simply set XDG_RUNTIME_DIR and
 414          * leave. */
 415
 416         pam_get_item(handle, PAM_SERVICE, (const void**) &service);
 417         if (streq_ptr(service, "systemd-user")) {
 418                 char rt[STRLEN("/run/user/") + DECIMAL_STR_MAX(uid_t)];
 419
 420                 xsprintf(rt, "/run/user/"UID_FMT, pw->pw_uid);
 421                 if (validate_runtime_directory(handle, rt, pw->pw_uid)) {
 422                         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
 423                         if (r != PAM_SUCCESS) {
 424                                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 425                                 return r;
 426                         }
 427                 }
 428
 429                 r = export_legacy_dbus_address(handle, pw->pw_uid, rt);
 430                 if (r != PAM_SUCCESS)
 431                         return r;
 432
 433                 return PAM_SUCCESS;
 434         }
 435
 436         /* Otherwise, we ask logind to create a session for us */
 437
 438         pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
 439         pam_get_item(handle, PAM_TTY, (const void**) &tty);
 440         pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
 441         pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
 442
 443         seat = getenv_harder(handle, "XDG_SEAT", NULL);
 444         cvtnr = getenv_harder(handle, "XDG_VTNR", NULL);
 445         type = getenv_harder(handle, "XDG_SESSION_TYPE", type_pam);
 446         class = getenv_harder(handle, "XDG_SESSION_CLASS", class_pam);
 447         desktop = getenv_harder(handle, "XDG_SESSION_DESKTOP", desktop_pam);
 448
 449         tty = strempty(tty);
 450
 451         if (strchr(tty, ':')) {
 452                 /* A tty with a colon is usually an X11 display, placed there to show up in utmp. We rearrange things
 453                  * and don't pretend that an X display was a tty. */
 454                 if (isempty(display))
 455                         display = tty;
 456                 tty = NULL;
 457
 458         } else if (streq(tty, "cron")) {
 459                 /* cron is setting PAM_TTY to "cron" for some reason (the commit carries no information why, but
 460                  * probably because it wants to set it to something as pam_time/pam_access/… require PAM_TTY to be set
 461                  * (as they otherwise even try to update it!) — but cron doesn't actually allocate a TTY for its forked
 462                  * off processes.) */
 463                 type = "unspecified";
 464                 class = "background";
 465                 tty = NULL;
 466
 467         } else if (streq(tty, "ssh")) {
 468                 /* ssh has been setting PAM_TTY to "ssh" (for the same reason as cron does this, see above. For further
 469                  * details look for "PAM_TTY_KLUDGE" in the openssh sources). */
 470                 type ="tty";
 471                 class = "user";
 472                 tty = NULL; /* This one is particularly sad, as this means that ssh sessions — even though usually
 473                              * associated with a pty — won't be tracked by their tty in logind. This is because ssh
 474                              * does the PAM session registration early for new connections, and registers a pty only
 475                              * much later (this is because it doesn't know yet if it needs one at all, as whether to
 476                              * register a pty or not is negotiated much later in the protocol). */
 477
 478         } else
 479                 /* Chop off leading /dev prefix that some clients specify, but others do not. */
 480                 tty = skip_dev_prefix(tty);
 481
 482         /* If this fails vtnr will be 0, that's intended */
 483         if (!isempty(cvtnr))
 484                 (void) safe_atou32(cvtnr, &vtnr);
 485
 486         if (!isempty(display) && !vtnr) {
 487                 if (isempty(seat))
 488                         (void) get_seat_from_display(display, &seat, &vtnr);
 489                 else if (streq(seat, "seat0"))
 490                         (void) get_seat_from_display(display, NULL, &vtnr);
 491         }
 492
 493         if (seat && !streq(seat, "seat0") && vtnr != 0) {
 494                 if (debug)
 495                         pam_syslog(handle, LOG_DEBUG, "Ignoring vtnr %"PRIu32" for %s which is not seat0", vtnr, seat);
 496                 vtnr = 0;
 497         }
 498
 499         if (isempty(type))
 500                 type = !isempty(display) ? "x11" :
 501                            !isempty(tty) ? "tty" : "unspecified";
 502
 503         if (isempty(class))
 504                 class = streq(type, "unspecified") ? "background" : "user";
 505
 506         remote = !isempty(remote_host) && !is_localhost(remote_host);
 507
 508         (void) pam_get_data(handle, "systemd.memory_max", (const void **)&memory_max);
 509         (void) pam_get_data(handle, "systemd.tasks_max",  (const void **)&tasks_max);
 510         (void) pam_get_data(handle, "systemd.cpu_weight", (const void **)&cpu_weight);
 511         (void) pam_get_data(handle, "systemd.io_weight",  (const void **)&io_weight);
 512
 513         /* Talk to logind over the message bus */
 514
 515         r = sd_bus_open_system(&bus);
 516         if (r < 0) {
 517                 pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r));
 518                 return PAM_SESSION_ERR;
 519         }
 520
 521         if (debug) {
 522                 pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: "
 523                            "uid="UID_FMT" pid="PID_FMT" service=%s type=%s class=%s desktop=%s seat=%s vtnr=%"PRIu32" tty=%s display=%s remote=%s remote_user=%s remote_host=%s",
 524                            pw->pw_uid, getpid_cached(),
 525                            strempty(service),
 526                            type, class, strempty(desktop),
 527                            strempty(seat), vtnr, strempty(tty), strempty(display),
 528                            yes_no(remote), strempty(remote_user), strempty(remote_host));
 529                 pam_syslog(handle, LOG_DEBUG, "Session limits: "
 530                            "memory_max=%s tasks_max=%s cpu_weight=%s io_weight=%s",
 531                            strna(memory_max), strna(tasks_max), strna(cpu_weight), strna(io_weight));
 532         }
 533
 534         r = sd_bus_message_new_method_call(
 535                         bus,
 536                         &m,
 537                         "org.freedesktop.login1",
 538                         "/org/freedesktop/login1",
 539                         "org.freedesktop.login1.Manager",
 540                         "CreateSession");
 541         if (r < 0) {
 542                 pam_syslog(handle, LOG_ERR, "Failed to create CreateSession method call: %s", strerror(-r));
 543                 return PAM_SESSION_ERR;
 544         }
 545
 546         r = sd_bus_message_append(m, "uusssssussbss",
 547                         (uint32_t) pw->pw_uid,
 548                         0,
 549                         service,
 550                         type,
 551                         class,
 552                         desktop,
 553                         seat,
 554                         vtnr,
 555                         tty,
 556                         display,
 557                         remote,
 558                         remote_user,
 559                         remote_host);
 560         if (r < 0) {
 561                 pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 562                 return PAM_SESSION_ERR;
 563         }
 564
 565         r = sd_bus_message_open_container(m, 'a', "(sv)");
 566         if (r < 0) {
 567                 pam_syslog(handle, LOG_ERR, "Failed to open message container: %s", strerror(-r));
 568                 return PAM_SYSTEM_ERR;
 569         }
 570
 571         r = append_session_memory_max(handle, m, memory_max);
 572         if (r < 0)
 573                 return PAM_SESSION_ERR;
 574
 575         r = append_session_tasks_max(handle, m, tasks_max);
 576         if (r < 0)
 577                 return PAM_SESSION_ERR;
 578
 579         r = append_session_cg_weight(handle, m, cpu_weight, "CPUWeight");
 580         if (r < 0)
 581                 return PAM_SESSION_ERR;
 582
 583         r = append_session_cg_weight(handle, m, io_weight, "IOWeight");
 584         if (r < 0)
 585                 return PAM_SESSION_ERR;
 586
 587         r = sd_bus_message_close_container(m);
 588         if (r < 0) {
 589                 pam_syslog(handle, LOG_ERR, "Failed to close message container: %s", strerror(-r));
 590                 return PAM_SYSTEM_ERR;
 591         }
 592
 593         r = sd_bus_call(bus, m, 0, &error, &reply);
 594         if (r < 0) {
 595                 if (sd_bus_error_has_name(&error, BUS_ERROR_SESSION_BUSY)) {
 596                         if (debug)
 597                                 pam_syslog(handle, LOG_DEBUG, "Cannot create session: %s", bus_error_message(&error, r));
 598                         return PAM_SUCCESS;
 599                 } else {
 600                         pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r));
 601                         return PAM_SYSTEM_ERR;
 602                 }
 603         }
 604
 605         r = sd_bus_message_read(reply,
 606                                 "soshusub",
 607                                 &id,
 608                                 &object_path,
 609                                 &runtime_path,
 610                                 &session_fd,
 611                                 &original_uid,
 612                                 &seat,
 613                                 &vtnr,
 614                                 &existing);
 615         if (r < 0) {
 616                 pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", strerror(-r));
 617                 return PAM_SESSION_ERR;
 618         }
 619
 620         if (debug)
 621                 pam_syslog(handle, LOG_DEBUG, "Reply from logind: "
 622                            "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u original_uid=%u",
 623                            id, object_path, runtime_path, session_fd, seat, vtnr, original_uid);
 624
 625         r = update_environment(handle, "XDG_SESSION_ID", id);
 626         if (r != PAM_SUCCESS)
 627                 return r;
 628
 629         if (original_uid == pw->pw_uid) {
 630                 /* Don't set $XDG_RUNTIME_DIR if the user we now
 631                  * authenticated for does not match the original user
 632                  * of the session. We do this in order not to result
 633                  * in privileged apps clobbering the runtime directory
 634                  * unnecessarily. */
 635
 636                 if (validate_runtime_directory(handle, runtime_path, pw->pw_uid)) {
 637                         r = update_environment(handle, "XDG_RUNTIME_DIR", runtime_path);
 638                         if (r != PAM_SUCCESS)
 639                                 return r;
 640                 }
 641
 642                 r = export_legacy_dbus_address(handle, pw->pw_uid, runtime_path);
 643                 if (r != PAM_SUCCESS)
 644                         return r;
 645         }
 646
 647         /* Most likely we got the session/type/class from environment variables, but might have gotten the data
 648          * somewhere else (for example PAM module parameters). Let's now update the environment variables, so that this
 649          * data is inherited into the session processes, and programs can rely on them to be initialized. */
 650
 651         r = update_environment(handle, "XDG_SESSION_TYPE", type);
 652         if (r != PAM_SUCCESS)
 653                 return r;
 654
 655         r = update_environment(handle, "XDG_SESSION_CLASS", class);
 656         if (r != PAM_SUCCESS)
 657                 return r;
 658
 659         r = update_environment(handle, "XDG_SESSION_DESKTOP", desktop);
 660         if (r != PAM_SUCCESS)
 661                 return r;
 662
 663         r = update_environment(handle, "XDG_SEAT", seat);
 664         if (r != PAM_SUCCESS)
 665                 return r;
 666
 667         if (vtnr > 0) {
 668                 char buf[DECIMAL_STR_MAX(vtnr)];
 669                 sprintf(buf, "%u", vtnr);
 670
 671                 r = update_environment(handle, "XDG_VTNR", buf);
 672                 if (r != PAM_SUCCESS)
 673                         return r;
 674         }
 675
 676         r = pam_set_data(handle, "systemd.existing", INT_TO_PTR(!!existing), NULL);
 677         if (r != PAM_SUCCESS) {
 678                 pam_syslog(handle, LOG_ERR, "Failed to install existing flag.");
 679                 return r;
 680         }
 681
 682         if (session_fd >= 0) {
 683                 session_fd = fcntl(session_fd, F_DUPFD_CLOEXEC, 3);
 684                 if (session_fd < 0) {
 685                         pam_syslog(handle, LOG_ERR, "Failed to dup session fd: %m");
 686                         return PAM_SESSION_ERR;
 687                 }
 688
 689                 r = pam_set_data(handle, "systemd.session-fd", FD_TO_PTR(session_fd), NULL);
 690                 if (r != PAM_SUCCESS) {
 691                         pam_syslog(handle, LOG_ERR, "Failed to install session fd.");
 692                         safe_close(session_fd);
 693                         return r;
 694                 }
 695         }
 696
 697         return PAM_SUCCESS;
 698 }
 699
 700 _public_ PAM_EXTERN int pam_sm_close_session(
 701                 pam_handle_t *handle,
 702                 int flags,
 703                 int argc, const char **argv) {
 704
 705         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 706         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 707         const void *existing = NULL;
 708         const char *id;
 709         int r;
 710
 711         assert(handle);
 712
 713         /* Only release session if it wasn't pre-existing when we
 714          * tried to create it */
 715         (void) pam_get_data(handle, "systemd.existing", &existing);
 716
 717         id = pam_getenv(handle, "XDG_SESSION_ID");
 718         if (id && !existing) {
 719
 720                 /* Before we go and close the FIFO we need to tell
 721                  * logind that this is a clean session shutdown, so
 722                  * that it doesn't just go and slaughter us
 723                  * immediately after closing the fd */
 724
 725                 r = sd_bus_open_system(&bus);
 726                 if (r < 0) {
 727                         pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r));
 728                         return PAM_SESSION_ERR;
 729                 }
 730
 731                 r = sd_bus_call_method(bus,
 732                                        "org.freedesktop.login1",
 733                                        "/org/freedesktop/login1",
 734                                        "org.freedesktop.login1.Manager",
 735                                        "ReleaseSession",
 736                                        &error,
 737                                        NULL,
 738                                        "s",
 739                                        id);
 740                 if (r < 0) {
 741                         pam_syslog(handle, LOG_ERR, "Failed to release session: %s", bus_error_message(&error, r));
 742                         return PAM_SESSION_ERR;
 743                 }
 744         }
 745
 746         /* Note that we are knowingly leaking the FIFO fd here. This
 747          * way, logind can watch us die. If we closed it here it would
 748          * not have any clue when that is completed. Given that one
 749          * cannot really have multiple PAM sessions open from the same
 750          * process this means we will leak one FD at max. */
 751
 752         return PAM_SUCCESS;
 753 }