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 #include <sys/stat.h>
  14 #include <sys/types.h>
  15 #include <unistd.h>
  16
  17 #include "alloc-util.h"
  18 #include "audit-util.h"
  19 #include "bus-common-errors.h"
  20 #include "bus-error.h"
  21 #include "bus-internal.h"
  22 #include "bus-util.h"
  23 #include "cgroup-util.h"
  24 #include "fd-util.h"
  25 #include "fileio.h"
  26 #include "format-util.h"
  27 #include "hostname-util.h"
  28 #include "login-util.h"
  29 #include "macro.h"
  30 #include "parse-util.h"
  31 #include "path-util.h"
  32 #include "process-util.h"
  33 #include "socket-util.h"
  34 #include "stdio-util.h"
  35 #include "strv.h"
  36 #include "terminal-util.h"
  37
  38 static int parse_argv(
  39                 pam_handle_t *handle,
  40                 int argc, const char **argv,
  41                 const char **class,
  42                 const char **type,
  43                 const char **desktop,
  44                 bool *debug) {
  45
  46         unsigned i;
  47
  48         assert(argc >= 0);
  49         assert(argc == 0 || argv);
  50
  51         for (i = 0; i < (unsigned) argc; i++) {
  52                 if (startswith(argv[i], "class=")) {
  53                         if (class)
  54                                 *class = argv[i] + 6;
  55
  56                 } else if (startswith(argv[i], "type=")) {
  57                         if (type)
  58                                 *type = argv[i] + 5;
  59
  60                 } else if (startswith(argv[i], "desktop=")) {
  61                         if (desktop)
  62                                 *desktop = argv[i] + 8;
  63
  64                 } else if (streq(argv[i], "debug")) {
  65                         if (debug)
  66                                 *debug = true;
  67
  68                 } else if (startswith(argv[i], "debug=")) {
  69                         int k;
  70
  71                         k = parse_boolean(argv[i] + 6);
  72                         if (k < 0)
  73                                 pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring.");
  74                         else if (debug)
  75                                 *debug = k;
  76
  77                 } else
  78                         pam_syslog(handle, LOG_WARNING, "Unknown parameter '%s', ignoring", argv[i]);
  79         }
  80
  81         return 0;
  82 }
  83
  84 static int get_user_data(
  85                 pam_handle_t *handle,
  86                 const char **ret_username,
  87                 struct passwd **ret_pw) {
  88
  89         const char *username = NULL;
  90         struct passwd *pw = NULL;
  91         int r;
  92
  93         assert(handle);
  94         assert(ret_username);
  95         assert(ret_pw);
  96
  97         r = pam_get_user(handle, &username, NULL);
  98         if (r != PAM_SUCCESS) {
  99                 pam_syslog(handle, LOG_ERR, "Failed to get user name.");
 100                 return r;
 101         }
 102
 103         if (isempty(username)) {
 104                 pam_syslog(handle, LOG_ERR, "User name not valid.");
 105                 return PAM_AUTH_ERR;
 106         }
 107
 108         pw = pam_modutil_getpwnam(handle, username);
 109         if (!pw) {
 110                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 111                 return PAM_USER_UNKNOWN;
 112         }
 113
 114         *ret_pw = pw;
 115         *ret_username = username;
 116
 117         return PAM_SUCCESS;
 118 }
 119
 120 static bool display_is_local(const char *display) {
 121         assert(display);
 122
 123         return
 124                 display[0] == ':' &&
 125                 display[1] >= '0' &&
 126                 display[1] <= '9';
 127 }
 128
 129 static int socket_from_display(const char *display, char **path) {
 130         size_t k;
 131         char *f, *c;
 132
 133         assert(display);
 134         assert(path);
 135
 136         if (!display_is_local(display))
 137                 return -EINVAL;
 138
 139         k = strspn(display+1, "0123456789");
 140
 141         f = new(char, STRLEN("/tmp/.X11-unix/X") + k + 1);
 142         if (!f)
 143                 return -ENOMEM;
 144
 145         c = stpcpy(f, "/tmp/.X11-unix/X");
 146         memcpy(c, display+1, k);
 147         c[k] = 0;
 148
 149         *path = f;
 150
 151         return 0;
 152 }
 153
 154 static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
 155         union sockaddr_union sa = {};
 156         _cleanup_free_ char *p = NULL, *tty = NULL;
 157         _cleanup_close_ int fd = -1;
 158         struct ucred ucred;
 159         int v, r, salen;
 160
 161         assert(display);
 162         assert(vtnr);
 163
 164         /* We deduce the X11 socket from the display name, then use
 165          * SO_PEERCRED to determine the X11 server process, ask for
 166          * the controlling tty of that and if it's a VC then we know
 167          * the seat and the virtual terminal. Sounds ugly, is only
 168          * semi-ugly. */
 169
 170         r = socket_from_display(display, &p);
 171         if (r < 0)
 172                 return r;
 173         salen = sockaddr_un_set_path(&sa.un, p);
 174         if (salen < 0)
 175                 return salen;
 176
 177         fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
 178         if (fd < 0)
 179                 return -errno;
 180
 181         if (connect(fd, &sa.sa, salen) < 0)
 182                 return -errno;
 183
 184         r = getpeercred(fd, &ucred);
 185         if (r < 0)
 186                 return r;
 187
 188         r = get_ctty(ucred.pid, NULL, &tty);
 189         if (r < 0)
 190                 return r;
 191
 192         v = vtnr_from_tty(tty);
 193         if (v < 0)
 194                 return v;
 195         else if (v == 0)
 196                 return -ENOENT;
 197
 198         if (seat)
 199                 *seat = "seat0";
 200         *vtnr = (uint32_t) v;
 201
 202         return 0;
 203 }
 204
 205 static int export_legacy_dbus_address(
 206                 pam_handle_t *handle,
 207                 uid_t uid,
 208                 const char *runtime) {
 209
 210         const char *s;
 211         _cleanup_free_ char *t = NULL;
 212         int r = PAM_BUF_ERR;
 213
 214         /* We need to export $DBUS_SESSION_BUS_ADDRESS because various applications will not connect
 215          * correctly to the bus without it. This setting matches what dbus.socket does for the user
 216          * session using 'systemctl --user set-environment'. We want to have the same configuration
 217          * in processes started from the PAM session.
 218          *
 219          * The setting of the address is guarded by the access() check because it is also possible to compile
 220          * dbus without --enable-user-session, in which case this socket is not used, and
 221          * $DBUS_SESSION_BUS_ADDRESS should not be set. An alternative approach would to not do the access()
 222          * check here, and let applications try on their own, by using "unix:path=%s/bus;autolaunch:". But we
 223          * expect the socket to be present by the time we do this check, so we can just as well check once
 224          * here. */
 225
 226         s = strjoina(runtime, "/bus");
 227         if (access(s, F_OK) < 0)
 228                 return PAM_SUCCESS;
 229
 230         if (asprintf(&t, DEFAULT_USER_BUS_ADDRESS_FMT, runtime) < 0)
 231                 goto error;
 232
 233         r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", t, 0);
 234         if (r != PAM_SUCCESS)
 235                 goto error;
 236
 237         return PAM_SUCCESS;
 238
 239 error:
 240         pam_syslog(handle, LOG_ERR, "Failed to set bus variable.");
 241         return r;
 242 }
 243
 244 static int append_session_memory_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 245         uint64_t val;
 246         int r;
 247
 248         if (isempty(limit))
 249                 return 0;
 250
 251         if (streq(limit, "infinity")) {
 252                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", (uint64_t)-1);
 253                 if (r < 0) {
 254                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 255                         return r;
 256                 }
 257         } else {
 258                 r = parse_permille(limit);
 259                 if (r >= 0) {
 260                         r = sd_bus_message_append(m, "(sv)", "MemoryMaxScale", "u", (uint32_t) (((uint64_t) r * UINT32_MAX) / 1000U));
 261                         if (r < 0) {
 262                                 pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 263                                 return r;
 264                         }
 265                 } else {
 266                         r = parse_size(limit, 1024, &val);
 267                         if (r >= 0) {
 268                                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", val);
 269                                 if (r < 0) {
 270                                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 271                                         return r;
 272                                 }
 273                         } else
 274                                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.memory_max: %s, ignoring.", limit);
 275                 }
 276         }
 277
 278         return 0;
 279 }
 280
 281 static int append_session_tasks_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 282         uint64_t val;
 283         int r;
 284
 285         /* No need to parse "infinity" here, it will be set unconditionally later in manager_start_scope() */
 286         if (isempty(limit) || streq(limit, "infinity"))
 287                 return 0;
 288
 289         r = safe_atou64(limit, &val);
 290         if (r >= 0) {
 291                 r = sd_bus_message_append(m, "(sv)", "TasksMax", "t", val);
 292                 if (r < 0) {
 293                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 294                         return r;
 295                 }
 296         } else
 297                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.tasks_max: %s, ignoring.", limit);
 298
 299         return 0;
 300 }
 301
 302 static int append_session_cg_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit, const char *field) {
 303         uint64_t val;
 304         int r;
 305
 306         if (isempty(limit))
 307                 return 0;
 308
 309         r = cg_weight_parse(limit, &val);
 310         if (r >= 0) {
 311                 r = sd_bus_message_append(m, "(sv)", field, "t", val);
 312                 if (r < 0) {
 313                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 314                         return r;
 315                 }
 316         } else if (streq(field, "CPUWeight"))
 317                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.cpu_weight: %s, ignoring.", limit);
 318         else
 319                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.io_weight: %s, ignoring.", limit);
 320
 321         return 0;
 322 }
 323
 324 static const char* getenv_harder(pam_handle_t *handle, const char *key, const char *fallback) {
 325         const char *v;
 326
 327         assert(handle);
 328         assert(key);
 329
 330         /* Looks for an environment variable, preferably in the environment block associated with the
 331          * specified PAM handle, falling back to the process' block instead. Why check both? Because we want
 332          * to permit configuration of session properties from unit files that invoke PAM services, so that
 333          * PAM services don't have to be reworked to set systemd-specific properties, but these properties
 334          * can still be set from the unit file Environment= block. */
 335
 336         v = pam_getenv(handle, key);
 337         if (!isempty(v))
 338                 return v;
 339
 340         /* We use secure_getenv() here, since we might get loaded into su/sudo, which are SUID. Ideally
 341          * they'd clean up the environment before invoking foreign code (such as PAM modules), but alas they
 342          * currently don't (to be precise, they clean up the environment they pass to their children, but
 343          * not their own environ[]). */
 344         v = secure_getenv(key);
 345         if (!isempty(v))
 346                 return v;
 347
 348         return fallback;
 349 }
 350
 351 static int update_environment(pam_handle_t *handle, const char *key, const char *value) {
 352         int r;
 353
 354         assert(handle);
 355         assert(key);
 356
 357         /* Updates the environment, but only if there's actually a value set. Also, log about errors */
 358
 359         if (isempty(value))
 360                 return PAM_SUCCESS;
 361
 362         r = pam_misc_setenv(handle, key, value, 0);
 363         if (r != PAM_SUCCESS)
 364                 pam_syslog(handle, LOG_ERR, "Failed to set environment variable %s.", key);
 365
 366         return r;
 367 }
 368
 369 static bool validate_runtime_directory(pam_handle_t *handle, const char *path, uid_t uid) {
 370         struct stat st;
 371
 372         assert(path);
 373
 374         /* Just some extra paranoia: let's not set $XDG_RUNTIME_DIR if the directory we'd set it to isn't actually set
 375          * up properly for us. */
 376
 377         if (lstat(path, &st) < 0) {
 378                 pam_syslog(handle, LOG_ERR, "Failed to stat() runtime directory '%s': %s", path, strerror(errno));
 379                 goto fail;
 380         }
 381
 382         if (!S_ISDIR(st.st_mode)) {
 383                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not actually a directory.", path);
 384                 goto fail;
 385         }
 386
 387         if (st.st_uid != uid) {
 388                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not owned by UID " UID_FMT ", as it should.", path, uid);
 389                 goto fail;
 390         }
 391
 392         return true;
 393
 394 fail:
 395         pam_syslog(handle, LOG_WARNING, "Not setting $XDG_RUNTIME_DIR, as the directory is not in order.");
 396         return false;
 397 }
 398
 399 _public_ PAM_EXTERN int pam_sm_open_session(
 400                 pam_handle_t *handle,
 401                 int flags,
 402                 int argc, const char **argv) {
 403
 404         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 405         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL, *reply = NULL;
 406         const char
 407                 *username, *id, *object_path, *runtime_path,
 408                 *service = NULL,
 409                 *tty = NULL, *display = NULL,
 410                 *remote_user = NULL, *remote_host = NULL,
 411                 *seat = NULL,
 412                 *type = NULL, *class = NULL,
 413                 *class_pam = NULL, *type_pam = NULL, *cvtnr = NULL, *desktop = NULL, *desktop_pam = NULL,
 414                 *memory_max = NULL, *tasks_max = NULL, *cpu_weight = NULL, *io_weight = NULL;
 415         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 416         int session_fd = -1, existing, r;
 417         bool debug = false, remote;
 418         struct passwd *pw;
 419         uint32_t vtnr = 0;
 420         uid_t original_uid;
 421
 422         assert(handle);
 423
 424         /* Make this a NOP on non-logind systems */
 425         if (!logind_running())
 426                 return PAM_SUCCESS;
 427
 428         if (parse_argv(handle,
 429                        argc, argv,
 430                        &class_pam,
 431                        &type_pam,
 432                        &desktop_pam,
 433                        &debug) < 0)
 434                 return PAM_SESSION_ERR;
 435
 436         if (debug)
 437                 pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing");
 438
 439         r = get_user_data(handle, &username, &pw);
 440         if (r != PAM_SUCCESS) {
 441                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 442                 return r;
 443         }
 444
 445         /* Make sure we don't enter a loop by talking to
 446          * systemd-logind when it is actually waiting for the
 447          * background to finish start-up. If the service is
 448          * "systemd-user" we simply set XDG_RUNTIME_DIR and
 449          * leave. */
 450
 451         pam_get_item(handle, PAM_SERVICE, (const void**) &service);
 452         if (streq_ptr(service, "systemd-user")) {
 453                 char rt[STRLEN("/run/user/") + DECIMAL_STR_MAX(uid_t)];
 454
 455                 xsprintf(rt, "/run/user/"UID_FMT, pw->pw_uid);
 456                 if (validate_runtime_directory(handle, rt, pw->pw_uid)) {
 457                         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
 458                         if (r != PAM_SUCCESS) {
 459                                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 460                                 return r;
 461                         }
 462                 }
 463
 464                 r = export_legacy_dbus_address(handle, pw->pw_uid, rt);
 465                 if (r != PAM_SUCCESS)
 466                         return r;
 467
 468                 return PAM_SUCCESS;
 469         }
 470
 471         /* Otherwise, we ask logind to create a session for us */
 472
 473         pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
 474         pam_get_item(handle, PAM_TTY, (const void**) &tty);
 475         pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
 476         pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
 477
 478         seat = getenv_harder(handle, "XDG_SEAT", NULL);
 479         cvtnr = getenv_harder(handle, "XDG_VTNR", NULL);
 480         type = getenv_harder(handle, "XDG_SESSION_TYPE", type_pam);
 481         class = getenv_harder(handle, "XDG_SESSION_CLASS", class_pam);
 482         desktop = getenv_harder(handle, "XDG_SESSION_DESKTOP", desktop_pam);
 483
 484         tty = strempty(tty);
 485
 486         if (strchr(tty, ':')) {
 487                 /* A tty with a colon is usually an X11 display, placed there to show up in utmp. We rearrange things
 488                  * and don't pretend that an X display was a tty. */
 489                 if (isempty(display))
 490                         display = tty;
 491                 tty = NULL;
 492
 493         } else if (streq(tty, "cron")) {
 494                 /* cron is setting PAM_TTY to "cron" for some reason (the commit carries no information why, but
 495                  * probably because it wants to set it to something as pam_time/pam_access/… require PAM_TTY to be set
 496                  * (as they otherwise even try to update it!) — but cron doesn't actually allocate a TTY for its forked
 497                  * off processes.) */
 498                 type = "unspecified";
 499                 class = "background";
 500                 tty = NULL;
 501
 502         } else if (streq(tty, "ssh")) {
 503                 /* ssh has been setting PAM_TTY to "ssh" (for the same reason as cron does this, see above. For further
 504                  * details look for "PAM_TTY_KLUDGE" in the openssh sources). */
 505                 type ="tty";
 506                 class = "user";
 507                 tty = NULL; /* This one is particularly sad, as this means that ssh sessions — even though usually
 508                              * associated with a pty — won't be tracked by their tty in logind. This is because ssh
 509                              * does the PAM session registration early for new connections, and registers a pty only
 510                              * much later (this is because it doesn't know yet if it needs one at all, as whether to
 511                              * register a pty or not is negotiated much later in the protocol). */
 512
 513         } else
 514                 /* Chop off leading /dev prefix that some clients specify, but others do not. */
 515                 tty = skip_dev_prefix(tty);
 516
 517         /* If this fails vtnr will be 0, that's intended */
 518         if (!isempty(cvtnr))
 519                 (void) safe_atou32(cvtnr, &vtnr);
 520
 521         if (!isempty(display) && !vtnr) {
 522                 if (isempty(seat))
 523                         (void) get_seat_from_display(display, &seat, &vtnr);
 524                 else if (streq(seat, "seat0"))
 525                         (void) get_seat_from_display(display, NULL, &vtnr);
 526         }
 527
 528         if (seat && !streq(seat, "seat0") && vtnr != 0) {
 529                 if (debug)
 530                         pam_syslog(handle, LOG_DEBUG, "Ignoring vtnr %"PRIu32" for %s which is not seat0", vtnr, seat);
 531                 vtnr = 0;
 532         }
 533
 534         if (isempty(type))
 535                 type = !isempty(display) ? "x11" :
 536                            !isempty(tty) ? "tty" : "unspecified";
 537
 538         if (isempty(class))
 539                 class = streq(type, "unspecified") ? "background" : "user";
 540
 541         remote = !isempty(remote_host) && !is_localhost(remote_host);
 542
 543         (void) pam_get_data(handle, "systemd.memory_max", (const void **)&memory_max);
 544         (void) pam_get_data(handle, "systemd.tasks_max",  (const void **)&tasks_max);
 545         (void) pam_get_data(handle, "systemd.cpu_weight", (const void **)&cpu_weight);
 546         (void) pam_get_data(handle, "systemd.io_weight",  (const void **)&io_weight);
 547
 548         /* Talk to logind over the message bus */
 549
 550         r = sd_bus_open_system(&bus);
 551         if (r < 0) {
 552                 pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r));
 553                 return PAM_SESSION_ERR;
 554         }
 555
 556         if (debug) {
 557                 pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: "
 558                            "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",
 559                            pw->pw_uid, getpid_cached(),
 560                            strempty(service),
 561                            type, class, strempty(desktop),
 562                            strempty(seat), vtnr, strempty(tty), strempty(display),
 563                            yes_no(remote), strempty(remote_user), strempty(remote_host));
 564                 pam_syslog(handle, LOG_DEBUG, "Session limits: "
 565                            "memory_max=%s tasks_max=%s cpu_weight=%s io_weight=%s",
 566                            strna(memory_max), strna(tasks_max), strna(cpu_weight), strna(io_weight));
 567         }
 568
 569         r = sd_bus_message_new_method_call(
 570                         bus,
 571                         &m,
 572                         "org.freedesktop.login1",
 573                         "/org/freedesktop/login1",
 574                         "org.freedesktop.login1.Manager",
 575                         "CreateSession");
 576         if (r < 0) {
 577                 pam_syslog(handle, LOG_ERR, "Failed to create CreateSession method call: %s", strerror(-r));
 578                 return PAM_SESSION_ERR;
 579         }
 580
 581         r = sd_bus_message_append(m, "uusssssussbss",
 582                         (uint32_t) pw->pw_uid,
 583                         0,
 584                         service,
 585                         type,
 586                         class,
 587                         desktop,
 588                         seat,
 589                         vtnr,
 590                         tty,
 591                         display,
 592                         remote,
 593                         remote_user,
 594                         remote_host);
 595         if (r < 0) {
 596                 pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 597                 return PAM_SESSION_ERR;
 598         }
 599
 600         r = sd_bus_message_open_container(m, 'a', "(sv)");
 601         if (r < 0) {
 602                 pam_syslog(handle, LOG_ERR, "Failed to open message container: %s", strerror(-r));
 603                 return PAM_SYSTEM_ERR;
 604         }
 605
 606         r = append_session_memory_max(handle, m, memory_max);
 607         if (r < 0)
 608                 return PAM_SESSION_ERR;
 609
 610         r = append_session_tasks_max(handle, m, tasks_max);
 611         if (r < 0)
 612                 return PAM_SESSION_ERR;
 613
 614         r = append_session_cg_weight(handle, m, cpu_weight, "CPUWeight");
 615         if (r < 0)
 616                 return PAM_SESSION_ERR;
 617
 618         r = append_session_cg_weight(handle, m, io_weight, "IOWeight");
 619         if (r < 0)
 620                 return PAM_SESSION_ERR;
 621
 622         r = sd_bus_message_close_container(m);
 623         if (r < 0) {
 624                 pam_syslog(handle, LOG_ERR, "Failed to close message container: %s", strerror(-r));
 625                 return PAM_SYSTEM_ERR;
 626         }
 627
 628         r = sd_bus_call(bus, m, 0, &error, &reply);
 629         if (r < 0) {
 630                 if (sd_bus_error_has_name(&error, BUS_ERROR_SESSION_BUSY)) {
 631                         if (debug)
 632                                 pam_syslog(handle, LOG_DEBUG, "Not creating session: %s", bus_error_message(&error, r));
 633                         return PAM_SUCCESS;
 634                 } else {
 635                         pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r));
 636                         return PAM_SYSTEM_ERR;
 637                 }
 638         }
 639
 640         r = sd_bus_message_read(reply,
 641                                 "soshusub",
 642                                 &id,
 643                                 &object_path,
 644                                 &runtime_path,
 645                                 &session_fd,
 646                                 &original_uid,
 647                                 &seat,
 648                                 &vtnr,
 649                                 &existing);
 650         if (r < 0) {
 651                 pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", strerror(-r));
 652                 return PAM_SESSION_ERR;
 653         }
 654
 655         if (debug)
 656                 pam_syslog(handle, LOG_DEBUG, "Reply from logind: "
 657                            "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u original_uid=%u",
 658                            id, object_path, runtime_path, session_fd, seat, vtnr, original_uid);
 659
 660         r = update_environment(handle, "XDG_SESSION_ID", id);
 661         if (r != PAM_SUCCESS)
 662                 return r;
 663
 664         if (original_uid == pw->pw_uid) {
 665                 /* Don't set $XDG_RUNTIME_DIR if the user we now
 666                  * authenticated for does not match the original user
 667                  * of the session. We do this in order not to result
 668                  * in privileged apps clobbering the runtime directory
 669                  * unnecessarily. */
 670
 671                 if (validate_runtime_directory(handle, runtime_path, pw->pw_uid)) {
 672                         r = update_environment(handle, "XDG_RUNTIME_DIR", runtime_path);
 673                         if (r != PAM_SUCCESS)
 674                                 return r;
 675                 }
 676
 677                 r = export_legacy_dbus_address(handle, pw->pw_uid, runtime_path);
 678                 if (r != PAM_SUCCESS)
 679                         return r;
 680         }
 681
 682         /* Most likely we got the session/type/class from environment variables, but might have gotten the data
 683          * somewhere else (for example PAM module parameters). Let's now update the environment variables, so that this
 684          * data is inherited into the session processes, and programs can rely on them to be initialized. */
 685
 686         r = update_environment(handle, "XDG_SESSION_TYPE", type);
 687         if (r != PAM_SUCCESS)
 688                 return r;
 689
 690         r = update_environment(handle, "XDG_SESSION_CLASS", class);
 691         if (r != PAM_SUCCESS)
 692                 return r;
 693
 694         r = update_environment(handle, "XDG_SESSION_DESKTOP", desktop);
 695         if (r != PAM_SUCCESS)
 696                 return r;
 697
 698         r = update_environment(handle, "XDG_SEAT", seat);
 699         if (r != PAM_SUCCESS)
 700                 return r;
 701
 702         if (vtnr > 0) {
 703                 char buf[DECIMAL_STR_MAX(vtnr)];
 704                 sprintf(buf, "%u", vtnr);
 705
 706                 r = update_environment(handle, "XDG_VTNR", buf);
 707                 if (r != PAM_SUCCESS)
 708                         return r;
 709         }
 710
 711         r = pam_set_data(handle, "systemd.existing", INT_TO_PTR(!!existing), NULL);
 712         if (r != PAM_SUCCESS) {
 713                 pam_syslog(handle, LOG_ERR, "Failed to install existing flag.");
 714                 return r;
 715         }
 716
 717         if (session_fd >= 0) {
 718                 session_fd = fcntl(session_fd, F_DUPFD_CLOEXEC, 3);
 719                 if (session_fd < 0) {
 720                         pam_syslog(handle, LOG_ERR, "Failed to dup session fd: %m");
 721                         return PAM_SESSION_ERR;
 722                 }
 723
 724                 r = pam_set_data(handle, "systemd.session-fd", FD_TO_PTR(session_fd), NULL);
 725                 if (r != PAM_SUCCESS) {
 726                         pam_syslog(handle, LOG_ERR, "Failed to install session fd.");
 727                         safe_close(session_fd);
 728                         return r;
 729                 }
 730         }
 731
 732         return PAM_SUCCESS;
 733 }
 734
 735 _public_ PAM_EXTERN int pam_sm_close_session(
 736                 pam_handle_t *handle,
 737                 int flags,
 738                 int argc, const char **argv) {
 739
 740         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 741         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 742         const void *existing = NULL;
 743         const char *id;
 744         int r;
 745
 746         assert(handle);
 747
 748         /* Only release session if it wasn't pre-existing when we
 749          * tried to create it */
 750         (void) pam_get_data(handle, "systemd.existing", &existing);
 751
 752         id = pam_getenv(handle, "XDG_SESSION_ID");
 753         if (id && !existing) {
 754
 755                 /* Before we go and close the FIFO we need to tell
 756                  * logind that this is a clean session shutdown, so
 757                  * that it doesn't just go and slaughter us
 758                  * immediately after closing the fd */
 759
 760                 r = sd_bus_open_system(&bus);
 761                 if (r < 0) {
 762                         pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r));
 763                         return PAM_SESSION_ERR;
 764                 }
 765
 766                 r = sd_bus_call_method(bus,
 767                                        "org.freedesktop.login1",
 768                                        "/org/freedesktop/login1",
 769                                        "org.freedesktop.login1.Manager",
 770                                        "ReleaseSession",
 771                                        &error,
 772                                        NULL,
 773                                        "s",
 774                                        id);
 775                 if (r < 0) {
 776                         pam_syslog(handle, LOG_ERR, "Failed to release session: %s", bus_error_message(&error, r));
 777                         return PAM_SESSION_ERR;
 778                 }
 779         }
 780
 781         /* Note that we are knowingly leaking the FIFO fd here. This
 782          * way, logind can watch us die. If we closed it here it would
 783          * not have any clue when that is completed. Given that one
 784          * cannot really have multiple PAM sessions open from the same
 785          * process this means we will leak one FD at max. */
 786
 787         return PAM_SUCCESS;
 788 }