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 "strv.h"
  32 #include "terminal-util.h"
  33 #include "util.h"
  34
  35 static int parse_argv(
  36                 pam_handle_t *handle,
  37                 int argc, const char **argv,
  38                 const char **class,
  39                 const char **type,
  40                 const char **desktop,
  41                 bool *debug) {
  42
  43         unsigned i;
  44
  45         assert(argc >= 0);
  46         assert(argc == 0 || argv);
  47
  48         for (i = 0; i < (unsigned) argc; i++) {
  49                 if (startswith(argv[i], "class=")) {
  50                         if (class)
  51                                 *class = argv[i] + 6;
  52
  53                 } else if (startswith(argv[i], "type=")) {
  54                         if (type)
  55                                 *type = argv[i] + 5;
  56
  57                 } else if (startswith(argv[i], "desktop=")) {
  58                         if (desktop)
  59                                 *desktop = argv[i] + 8;
  60
  61                 } else if (streq(argv[i], "debug")) {
  62                         if (debug)
  63                                 *debug = true;
  64
  65                 } else if (startswith(argv[i], "debug=")) {
  66                         int k;
  67
  68                         k = parse_boolean(argv[i] + 6);
  69                         if (k < 0)
  70                                 pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring.");
  71                         else if (debug)
  72                                 *debug = k;
  73
  74                 } else
  75                         pam_syslog(handle, LOG_WARNING, "Unknown parameter '%s', ignoring", argv[i]);
  76         }
  77
  78         return 0;
  79 }
  80
  81 static int get_user_data(
  82                 pam_handle_t *handle,
  83                 const char **ret_username,
  84                 struct passwd **ret_pw) {
  85
  86         const char *username = NULL;
  87         struct passwd *pw = NULL;
  88         int r;
  89
  90         assert(handle);
  91         assert(ret_username);
  92         assert(ret_pw);
  93
  94         r = pam_get_user(handle, &username, NULL);
  95         if (r != PAM_SUCCESS) {
  96                 pam_syslog(handle, LOG_ERR, "Failed to get user name.");
  97                 return r;
  98         }
  99
 100         if (isempty(username)) {
 101                 pam_syslog(handle, LOG_ERR, "User name not valid.");
 102                 return PAM_AUTH_ERR;
 103         }
 104
 105         pw = pam_modutil_getpwnam(handle, username);
 106         if (!pw) {
 107                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 108                 return PAM_USER_UNKNOWN;
 109         }
 110
 111         *ret_pw = pw;
 112         *ret_username = username;
 113
 114         return PAM_SUCCESS;
 115 }
 116
 117 static int socket_from_display(const char *display, char **path) {
 118         size_t k;
 119         char *f, *c;
 120
 121         assert(display);
 122         assert(path);
 123
 124         if (!display_is_local(display))
 125                 return -EINVAL;
 126
 127         k = strspn(display+1, "0123456789");
 128
 129         f = new(char, STRLEN("/tmp/.X11-unix/X") + k + 1);
 130         if (!f)
 131                 return -ENOMEM;
 132
 133         c = stpcpy(f, "/tmp/.X11-unix/X");
 134         memcpy(c, display+1, k);
 135         c[k] = 0;
 136
 137         *path = f;
 138
 139         return 0;
 140 }
 141
 142 static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
 143         union sockaddr_union sa = {};
 144         _cleanup_free_ char *p = NULL, *tty = NULL;
 145         _cleanup_close_ int fd = -1;
 146         struct ucred ucred;
 147         int v, r, salen;
 148
 149         assert(display);
 150         assert(vtnr);
 151
 152         /* We deduce the X11 socket from the display name, then use
 153          * SO_PEERCRED to determine the X11 server process, ask for
 154          * the controlling tty of that and if it's a VC then we know
 155          * the seat and the virtual terminal. Sounds ugly, is only
 156          * semi-ugly. */
 157
 158         r = socket_from_display(display, &p);
 159         if (r < 0)
 160                 return r;
 161         salen = sockaddr_un_set_path(&sa.un, p);
 162         if (salen < 0)
 163                 return salen;
 164
 165         fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
 166         if (fd < 0)
 167                 return -errno;
 168
 169         if (connect(fd, &sa.sa, salen) < 0)
 170                 return -errno;
 171
 172         r = getpeercred(fd, &ucred);
 173         if (r < 0)
 174                 return r;
 175
 176         r = get_ctty(ucred.pid, NULL, &tty);
 177         if (r < 0)
 178                 return r;
 179
 180         v = vtnr_from_tty(tty);
 181         if (v < 0)
 182                 return v;
 183         else if (v == 0)
 184                 return -ENOENT;
 185
 186         if (seat)
 187                 *seat = "seat0";
 188         *vtnr = (uint32_t) v;
 189
 190         return 0;
 191 }
 192
 193 static int export_legacy_dbus_address(
 194                 pam_handle_t *handle,
 195                 uid_t uid,
 196                 const char *runtime) {
 197
 198         _cleanup_free_ char *s = NULL;
 199         int r = PAM_BUF_ERR;
 200
 201         /* FIXME: We *really* should move the access() check into the
 202          * daemons that spawn dbus-daemon, instead of forcing
 203          * DBUS_SESSION_BUS_ADDRESS= here. */
 204
 205         s = strjoin(runtime, "/bus");
 206         if (!s)
 207                 goto error;
 208
 209         if (access(s, F_OK) < 0)
 210                 return PAM_SUCCESS;
 211
 212         s = mfree(s);
 213         if (asprintf(&s, DEFAULT_USER_BUS_ADDRESS_FMT, runtime) < 0)
 214                 goto error;
 215
 216         r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", s, 0);
 217         if (r != PAM_SUCCESS)
 218                 goto error;
 219
 220         return PAM_SUCCESS;
 221
 222 error:
 223         pam_syslog(handle, LOG_ERR, "Failed to set bus variable.");
 224         return r;
 225 }
 226
 227 static int append_session_memory_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 228         uint64_t val;
 229         int r;
 230
 231         if (isempty(limit))
 232                 return 0;
 233
 234         if (streq(limit, "infinity")) {
 235                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", (uint64_t)-1);
 236                 if (r < 0) {
 237                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 238                         return r;
 239                 }
 240         } else {
 241                 r = parse_permille(limit);
 242                 if (r >= 0) {
 243                         r = sd_bus_message_append(m, "(sv)", "MemoryMaxScale", "u", (uint32_t) (((uint64_t) r * UINT32_MAX) / 1000U));
 244                         if (r < 0) {
 245                                 pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 246                                 return r;
 247                         }
 248                 } else {
 249                         r = parse_size(limit, 1024, &val);
 250                         if (r >= 0) {
 251                                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", val);
 252                                 if (r < 0) {
 253                                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 254                                         return r;
 255                                 }
 256                         } else
 257                                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.limit: %s, ignoring.", limit);
 258                 }
 259         }
 260
 261         return 0;
 262 }
 263
 264 static int append_session_tasks_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 265         uint64_t val;
 266         int r;
 267
 268         /* No need to parse "infinity" here, it will be set unconditionally later in manager_start_scope() */
 269         if (isempty(limit) || streq(limit, "infinity"))
 270                 return 0;
 271
 272         r = safe_atou64(limit, &val);
 273         if (r >= 0) {
 274                 r = sd_bus_message_append(m, "(sv)", "TasksMax", "t", val);
 275                 if (r < 0) {
 276                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 277                         return r;
 278                 }
 279         } else
 280                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.limit: %s, ignoring.", limit);
 281
 282         return 0;
 283 }
 284
 285 static int append_session_cg_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit, const char *field) {
 286         uint64_t val;
 287         int r;
 288
 289         if (isempty(limit))
 290                 return 0;
 291
 292         r = cg_weight_parse(limit, &val);
 293         if (r >= 0) {
 294                 r = sd_bus_message_append(m, "(sv)", field, "t", val);
 295                 if (r < 0) {
 296                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 297                         return r;
 298                 }
 299         } else if (streq(field, "CPUWeight"))
 300                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.cpu_weight: %s, ignoring.", limit);
 301         else
 302                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.io_weight: %s, ignoring.", limit);
 303
 304         return 0;
 305 }
 306
 307 static const char* getenv_harder(pam_handle_t *handle, const char *key, const char *fallback) {
 308         const char *v;
 309
 310         assert(handle);
 311         assert(key);
 312
 313         /* Looks for an environment variable, preferrably in the environment block associated with the specified PAM
 314          * handle, falling back to the process' block instead. */
 315
 316         v = pam_getenv(handle, key);
 317         if (!isempty(v))
 318                 return v;
 319
 320         v = getenv(key);
 321         if (!isempty(v))
 322                 return v;
 323
 324         return fallback;
 325 }
 326
 327 static int update_environment(pam_handle_t *handle, const char *key, const char *value) {
 328         int r;
 329
 330         assert(handle);
 331         assert(key);
 332
 333         /* Updates the environment, but only if there's actually a value set. Also, log about errors */
 334
 335         if (isempty(value))
 336                 return PAM_SUCCESS;
 337
 338         r = pam_misc_setenv(handle, key, value, 0);
 339         if (r != PAM_SUCCESS)
 340                 pam_syslog(handle, LOG_ERR, "Failed to set environment variable %s.", key);
 341
 342         return r;
 343 }
 344
 345 static bool validate_runtime_directory(pam_handle_t *handle, const char *path, uid_t uid) {
 346         struct stat st;
 347
 348         assert(path);
 349
 350         /* Just some extra paranoia: let's not set $XDG_RUNTIME_DIR if the directory we'd set it to isn't actually set
 351          * up properly for us. */
 352
 353         if (lstat(path, &st) < 0) {
 354                 pam_syslog(handle, LOG_ERR, "Failed to stat() runtime directory '%s': %s", path, strerror(errno));
 355                 goto fail;
 356         }
 357
 358         if (!S_ISDIR(st.st_mode)) {
 359                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not actually a directory.", path);
 360                 goto fail;
 361         }
 362
 363         if (st.st_uid != uid) {
 364                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not owned by UID " UID_FMT ", as it should.", path, uid);
 365                 goto fail;
 366         }
 367
 368         return true;
 369
 370 fail:
 371         pam_syslog(handle, LOG_WARNING, "Not setting $XDG_RUNTIME_DIR, as the directory is not in order.");
 372         return false;
 373 }
 374
 375 _public_ PAM_EXTERN int pam_sm_open_session(
 376                 pam_handle_t *handle,
 377                 int flags,
 378                 int argc, const char **argv) {
 379
 380         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 381         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL, *reply = NULL;
 382         const char
 383                 *username, *id, *object_path, *runtime_path,
 384                 *service = NULL,
 385                 *tty = NULL, *display = NULL,
 386                 *remote_user = NULL, *remote_host = NULL,
 387                 *seat = NULL,
 388                 *type = NULL, *class = NULL,
 389                 *class_pam = NULL, *type_pam = NULL, *cvtnr = NULL, *desktop = NULL, *desktop_pam = NULL,
 390                 *memory_max = NULL, *tasks_max = NULL, *cpu_weight = NULL, *io_weight = NULL;
 391         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 392         int session_fd = -1, existing, r;
 393         bool debug = false, remote;
 394         struct passwd *pw;
 395         uint32_t vtnr = 0;
 396         uid_t original_uid;
 397
 398         assert(handle);
 399
 400         /* Make this a NOP on non-logind systems */
 401         if (!logind_running())
 402                 return PAM_SUCCESS;
 403
 404         if (parse_argv(handle,
 405                        argc, argv,
 406                        &class_pam,
 407                        &type_pam,
 408                        &desktop_pam,
 409                        &debug) < 0)
 410                 return PAM_SESSION_ERR;
 411
 412         if (debug)
 413                 pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing");
 414
 415         r = get_user_data(handle, &username, &pw);
 416         if (r != PAM_SUCCESS) {
 417                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 418                 return r;
 419         }
 420
 421         /* Make sure we don't enter a loop by talking to
 422          * systemd-logind when it is actually waiting for the
 423          * background to finish start-up. If the service is
 424          * "systemd-user" we simply set XDG_RUNTIME_DIR and
 425          * leave. */
 426
 427         pam_get_item(handle, PAM_SERVICE, (const void**) &service);
 428         if (streq_ptr(service, "systemd-user")) {
 429                 _cleanup_free_ char *rt = NULL;
 430
 431                 if (asprintf(&rt, "/run/user/"UID_FMT, pw->pw_uid) < 0)
 432                         return PAM_BUF_ERR;
 433
 434                 if (validate_runtime_directory(handle, rt, pw->pw_uid)) {
 435                         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
 436                         if (r != PAM_SUCCESS) {
 437                                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 438                                 return r;
 439                         }
 440                 }
 441
 442                 r = export_legacy_dbus_address(handle, pw->pw_uid, rt);
 443                 if (r != PAM_SUCCESS)
 444                         return r;
 445
 446                 return PAM_SUCCESS;
 447         }
 448
 449         /* Otherwise, we ask logind to create a session for us */
 450
 451         pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
 452         pam_get_item(handle, PAM_TTY, (const void**) &tty);
 453         pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
 454         pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
 455
 456         seat = getenv_harder(handle, "XDG_SEAT", NULL);
 457         cvtnr = getenv_harder(handle, "XDG_VTNR", NULL);
 458         type = getenv_harder(handle, "XDG_SESSION_TYPE", type_pam);
 459         class = getenv_harder(handle, "XDG_SESSION_CLASS", class_pam);
 460         desktop = getenv_harder(handle, "XDG_SESSION_DESKTOP", desktop_pam);
 461
 462         tty = strempty(tty);
 463
 464         if (strchr(tty, ':')) {
 465                 /* A tty with a colon is usually an X11 display, placed there to show up in utmp. We rearrange things
 466                  * and don't pretend that an X display was a tty. */
 467                 if (isempty(display))
 468                         display = tty;
 469                 tty = NULL;
 470
 471         } else if (streq(tty, "cron")) {
 472                 /* cron is setting PAM_TTY to "cron" for some reason (the commit carries no information why, but
 473                  * probably because it wants to set it to something as pam_time/pam_access/… require PAM_TTY to be set
 474                  * (as they otherwise even try to update it!) — but cron doesn't actually allocate a TTY for its forked
 475                  * off processes.) */
 476                 type = "unspecified";
 477                 class = "background";
 478                 tty = NULL;
 479
 480         } else if (streq(tty, "ssh")) {
 481                 /* ssh has been setting PAM_TTY to "ssh" (for the same reason as cron does this, see above. For further
 482                  * details look for "PAM_TTY_KLUDGE" in the openssh sources). */
 483                 type ="tty";
 484                 class = "user";
 485                 tty = NULL; /* This one is particularly sad, as this means that ssh sessions — even though usually
 486                              * associated with a pty — won't be tracked by their tty in logind. This is because ssh
 487                              * does the PAM session registration early for new connections, and registers a pty only
 488                              * much later (this is because it doesn't know yet if it needs one at all, as whether to
 489                              * register a pty or not is negotiated much later in the protocol). */
 490
 491         } else
 492                 /* Chop off leading /dev prefix that some clients specify, but others do not. */
 493                 tty = skip_dev_prefix(tty);
 494
 495         /* If this fails vtnr will be 0, that's intended */
 496         if (!isempty(cvtnr))
 497                 (void) safe_atou32(cvtnr, &vtnr);
 498
 499         if (!isempty(display) && !vtnr) {
 500                 if (isempty(seat))
 501                         (void) get_seat_from_display(display, &seat, &vtnr);
 502                 else if (streq(seat, "seat0"))
 503                         (void) get_seat_from_display(display, NULL, &vtnr);
 504         }
 505
 506         if (seat && !streq(seat, "seat0") && vtnr != 0) {
 507                 if (debug)
 508                         pam_syslog(handle, LOG_DEBUG, "Ignoring vtnr %"PRIu32" for %s which is not seat0", vtnr, seat);
 509                 vtnr = 0;
 510         }
 511
 512         if (isempty(type))
 513                 type = !isempty(display) ? "x11" :
 514                            !isempty(tty) ? "tty" : "unspecified";
 515
 516         if (isempty(class))
 517                 class = streq(type, "unspecified") ? "background" : "user";
 518
 519         remote = !isempty(remote_host) && !is_localhost(remote_host);
 520
 521         (void) pam_get_data(handle, "systemd.memory_max", (const void **)&memory_max);
 522         (void) pam_get_data(handle, "systemd.tasks_max",  (const void **)&tasks_max);
 523         (void) pam_get_data(handle, "systemd.cpu_weight", (const void **)&cpu_weight);
 524         (void) pam_get_data(handle, "systemd.io_weight",  (const void **)&io_weight);
 525
 526         /* Talk to logind over the message bus */
 527
 528         r = sd_bus_open_system(&bus);
 529         if (r < 0) {
 530                 pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r));
 531                 return PAM_SESSION_ERR;
 532         }
 533
 534         if (debug) {
 535                 pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: "
 536                            "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",
 537                            pw->pw_uid, getpid_cached(),
 538                            strempty(service),
 539                            type, class, strempty(desktop),
 540                            strempty(seat), vtnr, strempty(tty), strempty(display),
 541                            yes_no(remote), strempty(remote_user), strempty(remote_host));
 542                 pam_syslog(handle, LOG_DEBUG, "Session limits: "
 543                            "memory_max=%s tasks_max=%s cpu_weight=%s io_weight=%s",
 544                            strna(memory_max), strna(tasks_max), strna(cpu_weight), strna(io_weight));
 545         }
 546
 547         r = sd_bus_message_new_method_call(
 548                         bus,
 549                         &m,
 550                         "org.freedesktop.login1",
 551                         "/org/freedesktop/login1",
 552                         "org.freedesktop.login1.Manager",
 553                         "CreateSession");
 554         if (r < 0) {
 555                 pam_syslog(handle, LOG_ERR, "Failed to create CreateSession method call: %s", strerror(-r));
 556                 return PAM_SESSION_ERR;
 557         }
 558
 559         r = sd_bus_message_append(m, "uusssssussbss",
 560                         (uint32_t) pw->pw_uid,
 561                         0,
 562                         service,
 563                         type,
 564                         class,
 565                         desktop,
 566                         seat,
 567                         vtnr,
 568                         tty,
 569                         display,
 570                         remote,
 571                         remote_user,
 572                         remote_host);
 573         if (r < 0) {
 574                 pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 575                 return PAM_SESSION_ERR;
 576         }
 577
 578         r = sd_bus_message_open_container(m, 'a', "(sv)");
 579         if (r < 0) {
 580                 pam_syslog(handle, LOG_ERR, "Failed to open message container: %s", strerror(-r));
 581                 return PAM_SYSTEM_ERR;
 582         }
 583
 584         r = append_session_memory_max(handle, m, memory_max);
 585         if (r < 0)
 586                 return PAM_SESSION_ERR;
 587
 588         r = append_session_tasks_max(handle, m, tasks_max);
 589         if (r < 0)
 590                 return PAM_SESSION_ERR;
 591
 592         r = append_session_cg_weight(handle, m, cpu_weight, "CPUWeight");
 593         if (r < 0)
 594                 return PAM_SESSION_ERR;
 595
 596         r = append_session_cg_weight(handle, m, io_weight, "IOWeight");
 597         if (r < 0)
 598                 return PAM_SESSION_ERR;
 599
 600         r = sd_bus_message_close_container(m);
 601         if (r < 0) {
 602                 pam_syslog(handle, LOG_ERR, "Failed to close message container: %s", strerror(-r));
 603                 return PAM_SYSTEM_ERR;
 604         }
 605
 606         r = sd_bus_call(bus, m, 0, &error, &reply);
 607         if (r < 0) {
 608                 if (sd_bus_error_has_name(&error, BUS_ERROR_SESSION_BUSY)) {
 609                         if (debug)
 610                                 pam_syslog(handle, LOG_DEBUG, "Cannot create session: %s", bus_error_message(&error, r));
 611                         return PAM_SUCCESS;
 612                 } else {
 613                         pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r));
 614                         return PAM_SYSTEM_ERR;
 615                 }
 616         }
 617
 618         r = sd_bus_message_read(reply,
 619                                 "soshusub",
 620                                 &id,
 621                                 &object_path,
 622                                 &runtime_path,
 623                                 &session_fd,
 624                                 &original_uid,
 625                                 &seat,
 626                                 &vtnr,
 627                                 &existing);
 628         if (r < 0) {
 629                 pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", strerror(-r));
 630                 return PAM_SESSION_ERR;
 631         }
 632
 633         if (debug)
 634                 pam_syslog(handle, LOG_DEBUG, "Reply from logind: "
 635                            "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u original_uid=%u",
 636                            id, object_path, runtime_path, session_fd, seat, vtnr, original_uid);
 637
 638         r = update_environment(handle, "XDG_SESSION_ID", id);
 639         if (r != PAM_SUCCESS)
 640                 return r;
 641
 642         if (original_uid == pw->pw_uid) {
 643                 /* Don't set $XDG_RUNTIME_DIR if the user we now
 644                  * authenticated for does not match the original user
 645                  * of the session. We do this in order not to result
 646                  * in privileged apps clobbering the runtime directory
 647                  * unnecessarily. */
 648
 649                 if (validate_runtime_directory(handle, runtime_path, pw->pw_uid)) {
 650                         r = update_environment(handle, "XDG_RUNTIME_DIR", runtime_path);
 651                         if (r != PAM_SUCCESS)
 652                                 return r;
 653                 }
 654
 655                 r = export_legacy_dbus_address(handle, pw->pw_uid, runtime_path);
 656                 if (r != PAM_SUCCESS)
 657                         return r;
 658         }
 659
 660         /* Most likely we got the session/type/class from environment variables, but might have gotten the data
 661          * somewhere else (for example PAM module parameters). Let's now update the environment variables, so that this
 662          * data is inherited into the session processes, and programs can rely on them to be initialized. */
 663
 664         r = update_environment(handle, "XDG_SESSION_TYPE", type);
 665         if (r != PAM_SUCCESS)
 666                 return r;
 667
 668         r = update_environment(handle, "XDG_SESSION_CLASS", class);
 669         if (r != PAM_SUCCESS)
 670                 return r;
 671
 672         r = update_environment(handle, "XDG_SESSION_DESKTOP", desktop);
 673         if (r != PAM_SUCCESS)
 674                 return r;
 675
 676         r = update_environment(handle, "XDG_SEAT", seat);
 677         if (r != PAM_SUCCESS)
 678                 return r;
 679
 680         if (vtnr > 0) {
 681                 char buf[DECIMAL_STR_MAX(vtnr)];
 682                 sprintf(buf, "%u", vtnr);
 683
 684                 r = update_environment(handle, "XDG_VTNR", buf);
 685                 if (r != PAM_SUCCESS)
 686                         return r;
 687         }
 688
 689         r = pam_set_data(handle, "systemd.existing", INT_TO_PTR(!!existing), NULL);
 690         if (r != PAM_SUCCESS) {
 691                 pam_syslog(handle, LOG_ERR, "Failed to install existing flag.");
 692                 return r;
 693         }
 694
 695         if (session_fd >= 0) {
 696                 session_fd = fcntl(session_fd, F_DUPFD_CLOEXEC, 3);
 697                 if (session_fd < 0) {
 698                         pam_syslog(handle, LOG_ERR, "Failed to dup session fd: %m");
 699                         return PAM_SESSION_ERR;
 700                 }
 701
 702                 r = pam_set_data(handle, "systemd.session-fd", FD_TO_PTR(session_fd), NULL);
 703                 if (r != PAM_SUCCESS) {
 704                         pam_syslog(handle, LOG_ERR, "Failed to install session fd.");
 705                         safe_close(session_fd);
 706                         return r;
 707                 }
 708         }
 709
 710         return PAM_SUCCESS;
 711 }
 712
 713 _public_ PAM_EXTERN int pam_sm_close_session(
 714                 pam_handle_t *handle,
 715                 int flags,
 716                 int argc, const char **argv) {
 717
 718         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 719         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 720         const void *existing = NULL;
 721         const char *id;
 722         int r;
 723
 724         assert(handle);
 725
 726         /* Only release session if it wasn't pre-existing when we
 727          * tried to create it */
 728         (void) pam_get_data(handle, "systemd.existing", &existing);
 729
 730         id = pam_getenv(handle, "XDG_SESSION_ID");
 731         if (id && !existing) {
 732
 733                 /* Before we go and close the FIFO we need to tell
 734                  * logind that this is a clean session shutdown, so
 735                  * that it doesn't just go and slaughter us
 736                  * immediately after closing the fd */
 737
 738                 r = sd_bus_open_system(&bus);
 739                 if (r < 0) {
 740                         pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r));
 741                         return PAM_SESSION_ERR;
 742                 }
 743
 744                 r = sd_bus_call_method(bus,
 745                                        "org.freedesktop.login1",
 746                                        "/org/freedesktop/login1",
 747                                        "org.freedesktop.login1.Manager",
 748                                        "ReleaseSession",
 749                                        &error,
 750                                        NULL,
 751                                        "s",
 752                                        id);
 753                 if (r < 0) {
 754                         pam_syslog(handle, LOG_ERR, "Failed to release session: %s", bus_error_message(&error, r));
 755                         return PAM_SESSION_ERR;
 756                 }
 757         }
 758
 759         /* Note that we are knowingly leaking the FIFO fd here. This
 760          * way, logind can watch us die. If we closed it here it would
 761          * not have any clue when that is completed. Given that one
 762          * cannot really have multiple PAM sessions open from the same
 763          * process this means we will leak one FD at max. */
 764
 765         return PAM_SUCCESS;
 766 }