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         if (asprintf(&s, DEFAULT_USER_BUS_ADDRESS_FMT, runtime) < 0)
 202                 goto error;
 203
 204         r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", s, 0);
 205         if (r != PAM_SUCCESS)
 206                 goto error;
 207
 208         return PAM_SUCCESS;
 209
 210 error:
 211         pam_syslog(handle, LOG_ERR, "Failed to set bus variable.");
 212         return r;
 213 }
 214
 215 static int append_session_memory_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 216         uint64_t val;
 217         int r;
 218
 219         if (isempty(limit))
 220                 return 0;
 221
 222         if (streq(limit, "infinity")) {
 223                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", (uint64_t)-1);
 224                 if (r < 0) {
 225                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 226                         return r;
 227                 }
 228         } else {
 229                 r = parse_permille(limit);
 230                 if (r >= 0) {
 231                         r = sd_bus_message_append(m, "(sv)", "MemoryMaxScale", "u", (uint32_t) (((uint64_t) r * UINT32_MAX) / 1000U));
 232                         if (r < 0) {
 233                                 pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 234                                 return r;
 235                         }
 236                 } else {
 237                         r = parse_size(limit, 1024, &val);
 238                         if (r >= 0) {
 239                                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", val);
 240                                 if (r < 0) {
 241                                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 242                                         return r;
 243                                 }
 244                         } else
 245                                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.limit: %s, ignoring.", limit);
 246                 }
 247         }
 248
 249         return 0;
 250 }
 251
 252 static int append_session_tasks_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 253         uint64_t val;
 254         int r;
 255
 256         /* No need to parse "infinity" here, it will be set unconditionally later in manager_start_scope() */
 257         if (isempty(limit) || streq(limit, "infinity"))
 258                 return 0;
 259
 260         r = safe_atou64(limit, &val);
 261         if (r >= 0) {
 262                 r = sd_bus_message_append(m, "(sv)", "TasksMax", "t", val);
 263                 if (r < 0) {
 264                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 265                         return r;
 266                 }
 267         } else
 268                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.limit: %s, ignoring.", limit);
 269
 270         return 0;
 271 }
 272
 273 static int append_session_cg_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit, const char *field) {
 274         uint64_t val;
 275         int r;
 276
 277         if (isempty(limit))
 278                 return 0;
 279
 280         r = cg_weight_parse(limit, &val);
 281         if (r >= 0) {
 282                 r = sd_bus_message_append(m, "(sv)", field, "t", val);
 283                 if (r < 0) {
 284                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 285                         return r;
 286                 }
 287         } else if (streq(field, "CPUWeight"))
 288                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.cpu_weight: %s, ignoring.", limit);
 289         else
 290                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.io_weight: %s, ignoring.", limit);
 291
 292         return 0;
 293 }
 294
 295 static const char* getenv_harder(pam_handle_t *handle, const char *key, const char *fallback) {
 296         const char *v;
 297
 298         assert(handle);
 299         assert(key);
 300
 301         /* Looks for an environment variable, preferrably in the environment block associated with the specified PAM
 302          * handle, falling back to the process' block instead. */
 303
 304         v = pam_getenv(handle, key);
 305         if (!isempty(v))
 306                 return v;
 307
 308         v = getenv(key);
 309         if (!isempty(v))
 310                 return v;
 311
 312         return fallback;
 313 }
 314
 315 static int update_environment(pam_handle_t *handle, const char *key, const char *value) {
 316         int r;
 317
 318         assert(handle);
 319         assert(key);
 320
 321         /* Updates the environment, but only if there's actually a value set. Also, log about errors */
 322
 323         if (isempty(value))
 324                 return PAM_SUCCESS;
 325
 326         r = pam_misc_setenv(handle, key, value, 0);
 327         if (r != PAM_SUCCESS)
 328                 pam_syslog(handle, LOG_ERR, "Failed to set environment variable %s.", key);
 329
 330         return r;
 331 }
 332
 333 static bool validate_runtime_directory(pam_handle_t *handle, const char *path, uid_t uid) {
 334         struct stat st;
 335
 336         assert(path);
 337
 338         /* Just some extra paranoia: let's not set $XDG_RUNTIME_DIR if the directory we'd set it to isn't actually set
 339          * up properly for us. */
 340
 341         if (lstat(path, &st) < 0) {
 342                 pam_syslog(handle, LOG_ERR, "Failed to stat() runtime directory '%s': %s", path, strerror(errno));
 343                 goto fail;
 344         }
 345
 346         if (!S_ISDIR(st.st_mode)) {
 347                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not actually a directory.", path);
 348                 goto fail;
 349         }
 350
 351         if (st.st_uid != uid) {
 352                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not owned by UID " UID_FMT ", as it should.", path, uid);
 353                 goto fail;
 354         }
 355
 356         return true;
 357
 358 fail:
 359         pam_syslog(handle, LOG_WARNING, "Not setting $XDG_RUNTIME_DIR, as the directory is not in order.");
 360         return false;
 361 }
 362
 363 _public_ PAM_EXTERN int pam_sm_open_session(
 364                 pam_handle_t *handle,
 365                 int flags,
 366                 int argc, const char **argv) {
 367
 368         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 369         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL, *reply = NULL;
 370         const char
 371                 *username, *id, *object_path, *runtime_path,
 372                 *service = NULL,
 373                 *tty = NULL, *display = NULL,
 374                 *remote_user = NULL, *remote_host = NULL,
 375                 *seat = NULL,
 376                 *type = NULL, *class = NULL,
 377                 *class_pam = NULL, *type_pam = NULL, *cvtnr = NULL, *desktop = NULL, *desktop_pam = NULL,
 378                 *memory_max = NULL, *tasks_max = NULL, *cpu_weight = NULL, *io_weight = NULL;
 379         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 380         int session_fd = -1, existing, r;
 381         bool debug = false, remote;
 382         struct passwd *pw;
 383         uint32_t vtnr = 0;
 384         uid_t original_uid;
 385
 386         assert(handle);
 387
 388         /* Make this a NOP on non-logind systems */
 389         if (!logind_running())
 390                 return PAM_SUCCESS;
 391
 392         if (parse_argv(handle,
 393                        argc, argv,
 394                        &class_pam,
 395                        &type_pam,
 396                        &desktop_pam,
 397                        &debug) < 0)
 398                 return PAM_SESSION_ERR;
 399
 400         if (debug)
 401                 pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing");
 402
 403         r = get_user_data(handle, &username, &pw);
 404         if (r != PAM_SUCCESS) {
 405                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 406                 return r;
 407         }
 408
 409         /* Make sure we don't enter a loop by talking to
 410          * systemd-logind when it is actually waiting for the
 411          * background to finish start-up. If the service is
 412          * "systemd-user" we simply set XDG_RUNTIME_DIR and
 413          * leave. */
 414
 415         pam_get_item(handle, PAM_SERVICE, (const void**) &service);
 416         if (streq_ptr(service, "systemd-user")) {
 417                 _cleanup_free_ char *rt = NULL;
 418
 419                 if (asprintf(&rt, "/run/user/"UID_FMT, pw->pw_uid) < 0)
 420                         return PAM_BUF_ERR;
 421
 422                 if (validate_runtime_directory(handle, rt, pw->pw_uid)) {
 423                         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
 424                         if (r != PAM_SUCCESS) {
 425                                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 426                                 return r;
 427                         }
 428                 }
 429
 430                 r = export_legacy_dbus_address(handle, pw->pw_uid, rt);
 431                 if (r != PAM_SUCCESS)
 432                         return r;
 433
 434                 return PAM_SUCCESS;
 435         }
 436
 437         /* Otherwise, we ask logind to create a session for us */
 438
 439         pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
 440         pam_get_item(handle, PAM_TTY, (const void**) &tty);
 441         pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
 442         pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
 443
 444         seat = getenv_harder(handle, "XDG_SEAT", NULL);
 445         cvtnr = getenv_harder(handle, "XDG_VTNR", NULL);
 446         type = getenv_harder(handle, "XDG_SESSION_TYPE", type_pam);
 447         class = getenv_harder(handle, "XDG_SESSION_CLASS", class_pam);
 448         desktop = getenv_harder(handle, "XDG_SESSION_DESKTOP", desktop_pam);
 449
 450         tty = strempty(tty);
 451
 452         if (strchr(tty, ':')) {
 453                 /* A tty with a colon is usually an X11 display, placed there to show up in utmp. We rearrange things
 454                  * and don't pretend that an X display was a tty. */
 455                 if (isempty(display))
 456                         display = tty;
 457                 tty = NULL;
 458
 459         } else if (streq(tty, "cron")) {
 460                 /* cron is setting PAM_TTY to "cron" for some reason (the commit carries no information why, but
 461                  * probably because it wants to set it to something as pam_time/pam_access/… require PAM_TTY to be set
 462                  * (as they otherwise even try to update it!) — but cron doesn't actually allocate a TTY for its forked
 463                  * off processes.) */
 464                 type = "unspecified";
 465                 class = "background";
 466                 tty = NULL;
 467
 468         } else if (streq(tty, "ssh")) {
 469                 /* ssh has been setting PAM_TTY to "ssh" (for the same reason as cron does this, see above. For further
 470                  * details look for "PAM_TTY_KLUDGE" in the openssh sources). */
 471                 type ="tty";
 472                 class = "user";
 473                 tty = NULL; /* This one is particularly sad, as this means that ssh sessions — even though usually
 474                              * associated with a pty — won't be tracked by their tty in logind. This is because ssh
 475                              * does the PAM session registration early for new connections, and registers a pty only
 476                              * much later (this is because it doesn't know yet if it needs one at all, as whether to
 477                              * register a pty or not is negotiated much later in the protocol). */
 478
 479         } else
 480                 /* Chop off leading /dev prefix that some clients specify, but others do not. */
 481                 tty = skip_dev_prefix(tty);
 482
 483         /* If this fails vtnr will be 0, that's intended */
 484         if (!isempty(cvtnr))
 485                 (void) safe_atou32(cvtnr, &vtnr);
 486
 487         if (!isempty(display) && !vtnr) {
 488                 if (isempty(seat))
 489                         (void) get_seat_from_display(display, &seat, &vtnr);
 490                 else if (streq(seat, "seat0"))
 491                         (void) get_seat_from_display(display, NULL, &vtnr);
 492         }
 493
 494         if (seat && !streq(seat, "seat0") && vtnr != 0) {
 495                 if (debug)
 496                         pam_syslog(handle, LOG_DEBUG, "Ignoring vtnr %"PRIu32" for %s which is not seat0", vtnr, seat);
 497                 vtnr = 0;
 498         }
 499
 500         if (isempty(type))
 501                 type = !isempty(display) ? "x11" :
 502                            !isempty(tty) ? "tty" : "unspecified";
 503
 504         if (isempty(class))
 505                 class = streq(type, "unspecified") ? "background" : "user";
 506
 507         remote = !isempty(remote_host) && !is_localhost(remote_host);
 508
 509         (void) pam_get_data(handle, "systemd.memory_max", (const void **)&memory_max);
 510         (void) pam_get_data(handle, "systemd.tasks_max",  (const void **)&tasks_max);
 511         (void) pam_get_data(handle, "systemd.cpu_weight", (const void **)&cpu_weight);
 512         (void) pam_get_data(handle, "systemd.io_weight",  (const void **)&io_weight);
 513
 514         /* Talk to logind over the message bus */
 515
 516         r = sd_bus_open_system(&bus);
 517         if (r < 0) {
 518                 pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r));
 519                 return PAM_SESSION_ERR;
 520         }
 521
 522         if (debug) {
 523                 pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: "
 524                            "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",
 525                            pw->pw_uid, getpid_cached(),
 526                            strempty(service),
 527                            type, class, strempty(desktop),
 528                            strempty(seat), vtnr, strempty(tty), strempty(display),
 529                            yes_no(remote), strempty(remote_user), strempty(remote_host));
 530                 pam_syslog(handle, LOG_DEBUG, "Session limits: "
 531                            "memory_max=%s tasks_max=%s cpu_weight=%s io_weight=%s",
 532                            strna(memory_max), strna(tasks_max), strna(cpu_weight), strna(io_weight));
 533         }
 534
 535         r = sd_bus_message_new_method_call(
 536                         bus,
 537                         &m,
 538                         "org.freedesktop.login1",
 539                         "/org/freedesktop/login1",
 540                         "org.freedesktop.login1.Manager",
 541                         "CreateSession");
 542         if (r < 0) {
 543                 pam_syslog(handle, LOG_ERR, "Failed to create CreateSession method call: %s", strerror(-r));
 544                 return PAM_SESSION_ERR;
 545         }
 546
 547         r = sd_bus_message_append(m, "uusssssussbss",
 548                         (uint32_t) pw->pw_uid,
 549                         0,
 550                         service,
 551                         type,
 552                         class,
 553                         desktop,
 554                         seat,
 555                         vtnr,
 556                         tty,
 557                         display,
 558                         remote,
 559                         remote_user,
 560                         remote_host);
 561         if (r < 0) {
 562                 pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 563                 return PAM_SESSION_ERR;
 564         }
 565
 566         r = sd_bus_message_open_container(m, 'a', "(sv)");
 567         if (r < 0) {
 568                 pam_syslog(handle, LOG_ERR, "Failed to open message container: %s", strerror(-r));
 569                 return PAM_SYSTEM_ERR;
 570         }
 571
 572         r = append_session_memory_max(handle, m, memory_max);
 573         if (r < 0)
 574                 return PAM_SESSION_ERR;
 575
 576         r = append_session_tasks_max(handle, m, tasks_max);
 577         if (r < 0)
 578                 return PAM_SESSION_ERR;
 579
 580         r = append_session_cg_weight(handle, m, cpu_weight, "CPUWeight");
 581         if (r < 0)
 582                 return PAM_SESSION_ERR;
 583
 584         r = append_session_cg_weight(handle, m, io_weight, "IOWeight");
 585         if (r < 0)
 586                 return PAM_SESSION_ERR;
 587
 588         r = sd_bus_message_close_container(m);
 589         if (r < 0) {
 590                 pam_syslog(handle, LOG_ERR, "Failed to close message container: %s", strerror(-r));
 591                 return PAM_SYSTEM_ERR;
 592         }
 593
 594         r = sd_bus_call(bus, m, 0, &error, &reply);
 595         if (r < 0) {
 596                 if (sd_bus_error_has_name(&error, BUS_ERROR_SESSION_BUSY)) {
 597                         if (debug)
 598                                 pam_syslog(handle, LOG_DEBUG, "Not creating session: %s", bus_error_message(&error, r));
 599                         return PAM_SUCCESS;
 600                 } else {
 601                         pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r));
 602                         return PAM_SYSTEM_ERR;
 603                 }
 604         }
 605
 606         r = sd_bus_message_read(reply,
 607                                 "soshusub",
 608                                 &id,
 609                                 &object_path,
 610                                 &runtime_path,
 611                                 &session_fd,
 612                                 &original_uid,
 613                                 &seat,
 614                                 &vtnr,
 615                                 &existing);
 616         if (r < 0) {
 617                 pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", strerror(-r));
 618                 return PAM_SESSION_ERR;
 619         }
 620
 621         if (debug)
 622                 pam_syslog(handle, LOG_DEBUG, "Reply from logind: "
 623                            "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u original_uid=%u",
 624                            id, object_path, runtime_path, session_fd, seat, vtnr, original_uid);
 625
 626         r = update_environment(handle, "XDG_SESSION_ID", id);
 627         if (r != PAM_SUCCESS)
 628                 return r;
 629
 630         if (original_uid == pw->pw_uid) {
 631                 /* Don't set $XDG_RUNTIME_DIR if the user we now
 632                  * authenticated for does not match the original user
 633                  * of the session. We do this in order not to result
 634                  * in privileged apps clobbering the runtime directory
 635                  * unnecessarily. */
 636
 637                 if (validate_runtime_directory(handle, runtime_path, pw->pw_uid)) {
 638                         r = update_environment(handle, "XDG_RUNTIME_DIR", runtime_path);
 639                         if (r != PAM_SUCCESS)
 640                                 return r;
 641                 }
 642
 643                 r = export_legacy_dbus_address(handle, pw->pw_uid, runtime_path);
 644                 if (r != PAM_SUCCESS)
 645                         return r;
 646         }
 647
 648         /* Most likely we got the session/type/class from environment variables, but might have gotten the data
 649          * somewhere else (for example PAM module parameters). Let's now update the environment variables, so that this
 650          * data is inherited into the session processes, and programs can rely on them to be initialized. */
 651
 652         r = update_environment(handle, "XDG_SESSION_TYPE", type);
 653         if (r != PAM_SUCCESS)
 654                 return r;
 655
 656         r = update_environment(handle, "XDG_SESSION_CLASS", class);
 657         if (r != PAM_SUCCESS)
 658                 return r;
 659
 660         r = update_environment(handle, "XDG_SESSION_DESKTOP", desktop);
 661         if (r != PAM_SUCCESS)
 662                 return r;
 663
 664         r = update_environment(handle, "XDG_SEAT", seat);
 665         if (r != PAM_SUCCESS)
 666                 return r;
 667
 668         if (vtnr > 0) {
 669                 char buf[DECIMAL_STR_MAX(vtnr)];
 670                 sprintf(buf, "%u", vtnr);
 671
 672                 r = update_environment(handle, "XDG_VTNR", buf);
 673                 if (r != PAM_SUCCESS)
 674                         return r;
 675         }
 676
 677         r = pam_set_data(handle, "systemd.existing", INT_TO_PTR(!!existing), NULL);
 678         if (r != PAM_SUCCESS) {
 679                 pam_syslog(handle, LOG_ERR, "Failed to install existing flag.");
 680                 return r;
 681         }
 682
 683         if (session_fd >= 0) {
 684                 session_fd = fcntl(session_fd, F_DUPFD_CLOEXEC, 3);
 685                 if (session_fd < 0) {
 686                         pam_syslog(handle, LOG_ERR, "Failed to dup session fd: %m");
 687                         return PAM_SESSION_ERR;
 688                 }
 689
 690                 r = pam_set_data(handle, "systemd.session-fd", FD_TO_PTR(session_fd), NULL);
 691                 if (r != PAM_SUCCESS) {
 692                         pam_syslog(handle, LOG_ERR, "Failed to install session fd.");
 693                         safe_close(session_fd);
 694                         return r;
 695                 }
 696         }
 697
 698         return PAM_SUCCESS;
 699 }
 700
 701 _public_ PAM_EXTERN int pam_sm_close_session(
 702                 pam_handle_t *handle,
 703                 int flags,
 704                 int argc, const char **argv) {
 705
 706         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 707         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 708         const void *existing = NULL;
 709         const char *id;
 710         int r;
 711
 712         assert(handle);
 713
 714         /* Only release session if it wasn't pre-existing when we
 715          * tried to create it */
 716         (void) pam_get_data(handle, "systemd.existing", &existing);
 717
 718         id = pam_getenv(handle, "XDG_SESSION_ID");
 719         if (id && !existing) {
 720
 721                 /* Before we go and close the FIFO we need to tell
 722                  * logind that this is a clean session shutdown, so
 723                  * that it doesn't just go and slaughter us
 724                  * immediately after closing the fd */
 725
 726                 r = sd_bus_open_system(&bus);
 727                 if (r < 0) {
 728                         pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r));
 729                         return PAM_SESSION_ERR;
 730                 }
 731
 732                 r = sd_bus_call_method(bus,
 733                                        "org.freedesktop.login1",
 734                                        "/org/freedesktop/login1",
 735                                        "org.freedesktop.login1.Manager",
 736                                        "ReleaseSession",
 737                                        &error,
 738                                        NULL,
 739                                        "s",
 740                                        id);
 741                 if (r < 0) {
 742                         pam_syslog(handle, LOG_ERR, "Failed to release session: %s", bus_error_message(&error, r));
 743                         return PAM_SESSION_ERR;
 744                 }
 745         }
 746
 747         /* Note that we are knowingly leaking the FIFO fd here. This
 748          * way, logind can watch us die. If we closed it here it would
 749          * not have any clue when that is completed. Given that one
 750          * cannot really have multiple PAM sessions open from the same
 751          * process this means we will leak one FD at max. */
 752
 753         return PAM_SUCCESS;
 754 }