src/login/pam_systemd.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <endian.h>
   4 #include <errno.h>
   5 #include <fcntl.h>
   6 #include <pwd.h>
   7 #include <security/_pam_macros.h>
   8 #include <security/pam_ext.h>
   9 #include <security/pam_misc.h>
  10 #include <security/pam_modules.h>
  11 #include <security/pam_modutil.h>
  12 #include <sys/file.h>
  13
  14 #include "alloc-util.h"
  15 #include "audit-util.h"
  16 #include "bus-common-errors.h"
  17 #include "bus-error.h"
  18 #include "bus-util.h"
  19 #include "cgroup-util.h"
  20 #include "def.h"
  21 #include "fd-util.h"
  22 #include "fileio.h"
  23 #include "format-util.h"
  24 #include "hostname-util.h"
  25 #include "login-util.h"
  26 #include "macro.h"
  27 #include "parse-util.h"
  28 #include "path-util.h"
  29 #include "process-util.h"
  30 #include "socket-util.h"
  31 #include "stdio-util.h"
  32 #include "strv.h"
  33 #include "terminal-util.h"
  34 #include "util.h"
  35
  36 static int parse_argv(
  37                 pam_handle_t *handle,
  38                 int argc, const char **argv,
  39                 const char **class,
  40                 const char **type,
  41                 const char **desktop,
  42                 bool *debug) {
  43
  44         unsigned i;
  45
  46         assert(argc >= 0);
  47         assert(argc == 0 || argv);
  48
  49         for (i = 0; i < (unsigned) argc; i++) {
  50                 if (startswith(argv[i], "class=")) {
  51                         if (class)
  52                                 *class = argv[i] + 6;
  53
  54                 } else if (startswith(argv[i], "type=")) {
  55                         if (type)
  56                                 *type = argv[i] + 5;
  57
  58                 } else if (startswith(argv[i], "desktop=")) {
  59                         if (desktop)
  60                                 *desktop = argv[i] + 8;
  61
  62                 } else if (streq(argv[i], "debug")) {
  63                         if (debug)
  64                                 *debug = true;
  65
  66                 } else if (startswith(argv[i], "debug=")) {
  67                         int k;
  68
  69                         k = parse_boolean(argv[i] + 6);
  70                         if (k < 0)
  71                                 pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring.");
  72                         else if (debug)
  73                                 *debug = k;
  74
  75                 } else
  76                         pam_syslog(handle, LOG_WARNING, "Unknown parameter '%s', ignoring", argv[i]);
  77         }
  78
  79         return 0;
  80 }
  81
  82 static int get_user_data(
  83                 pam_handle_t *handle,
  84                 const char **ret_username,
  85                 struct passwd **ret_pw) {
  86
  87         const char *username = NULL;
  88         struct passwd *pw = NULL;
  89         int r;
  90
  91         assert(handle);
  92         assert(ret_username);
  93         assert(ret_pw);
  94
  95         r = pam_get_user(handle, &username, NULL);
  96         if (r != PAM_SUCCESS) {
  97                 pam_syslog(handle, LOG_ERR, "Failed to get user name.");
  98                 return r;
  99         }
 100
 101         if (isempty(username)) {
 102                 pam_syslog(handle, LOG_ERR, "User name not valid.");
 103                 return PAM_AUTH_ERR;
 104         }
 105
 106         pw = pam_modutil_getpwnam(handle, username);
 107         if (!pw) {
 108                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 109                 return PAM_USER_UNKNOWN;
 110         }
 111
 112         *ret_pw = pw;
 113         *ret_username = username;
 114
 115         return PAM_SUCCESS;
 116 }
 117
 118 static int socket_from_display(const char *display, char **path) {
 119         size_t k;
 120         char *f, *c;
 121
 122         assert(display);
 123         assert(path);
 124
 125         if (!display_is_local(display))
 126                 return -EINVAL;
 127
 128         k = strspn(display+1, "0123456789");
 129
 130         f = new(char, STRLEN("/tmp/.X11-unix/X") + k + 1);
 131         if (!f)
 132                 return -ENOMEM;
 133
 134         c = stpcpy(f, "/tmp/.X11-unix/X");
 135         memcpy(c, display+1, k);
 136         c[k] = 0;
 137
 138         *path = f;
 139
 140         return 0;
 141 }
 142
 143 static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
 144         union sockaddr_union sa = {};
 145         _cleanup_free_ char *p = NULL, *tty = NULL;
 146         _cleanup_close_ int fd = -1;
 147         struct ucred ucred;
 148         int v, r, salen;
 149
 150         assert(display);
 151         assert(vtnr);
 152
 153         /* We deduce the X11 socket from the display name, then use
 154          * SO_PEERCRED to determine the X11 server process, ask for
 155          * the controlling tty of that and if it's a VC then we know
 156          * the seat and the virtual terminal. Sounds ugly, is only
 157          * semi-ugly. */
 158
 159         r = socket_from_display(display, &p);
 160         if (r < 0)
 161                 return r;
 162         salen = sockaddr_un_set_path(&sa.un, p);
 163         if (salen < 0)
 164                 return salen;
 165
 166         fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
 167         if (fd < 0)
 168                 return -errno;
 169
 170         if (connect(fd, &sa.sa, salen) < 0)
 171                 return -errno;
 172
 173         r = getpeercred(fd, &ucred);
 174         if (r < 0)
 175                 return r;
 176
 177         r = get_ctty(ucred.pid, NULL, &tty);
 178         if (r < 0)
 179                 return r;
 180
 181         v = vtnr_from_tty(tty);
 182         if (v < 0)
 183                 return v;
 184         else if (v == 0)
 185                 return -ENOENT;
 186
 187         if (seat)
 188                 *seat = "seat0";
 189         *vtnr = (uint32_t) v;
 190
 191         return 0;
 192 }
 193
 194 static int export_legacy_dbus_address(
 195                 pam_handle_t *handle,
 196                 uid_t uid,
 197                 const char *runtime) {
 198
 199         const char *s;
 200         _cleanup_free_ char *t = NULL;
 201         int r = PAM_BUF_ERR;
 202
 203         /* We need to export $DBUS_SESSION_BUS_ADDRESS because various applications will not connect
 204          * correctly to the bus without it. This setting matches what dbus.socket does for the user
 205          * session using 'systemctl --user set-environment'. We want to have the same configuration
 206          * in processes started from the PAM session.
 207          *
 208          * The setting of the address is guarded by the access() check because it is also possible to compile
 209          * dbus without --enable-user-session, in which case this socket is not used, and
 210          * $DBUS_SESSION_BUS_ADDRESS should not be set. An alternative approach would to not do the access()
 211          * check here, and let applications try on their own, by using "unix:path=%s/bus;autolaunch:". But we
 212          * expect the socket to be present by the time we do this check, so we can just as well check once
 213          * here. */
 214
 215         s = strjoina(runtime, "/bus");
 216         if (access(s, F_OK) < 0)
 217                 return PAM_SUCCESS;
 218
 219         if (asprintf(&t, DEFAULT_USER_BUS_ADDRESS_FMT, runtime) < 0)
 220                 goto error;
 221
 222         r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", t, 0);
 223         if (r != PAM_SUCCESS)
 224                 goto error;
 225
 226         return PAM_SUCCESS;
 227
 228 error:
 229         pam_syslog(handle, LOG_ERR, "Failed to set bus variable.");
 230         return r;
 231 }
 232
 233 static int append_session_memory_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 234         uint64_t val;
 235         int r;
 236
 237         if (isempty(limit))
 238                 return 0;
 239
 240         if (streq(limit, "infinity")) {
 241                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", (uint64_t)-1);
 242                 if (r < 0) {
 243                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 244                         return r;
 245                 }
 246         } else {
 247                 r = parse_permille(limit);
 248                 if (r >= 0) {
 249                         r = sd_bus_message_append(m, "(sv)", "MemoryMaxScale", "u", (uint32_t) (((uint64_t) r * UINT32_MAX) / 1000U));
 250                         if (r < 0) {
 251                                 pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 252                                 return r;
 253                         }
 254                 } else {
 255                         r = parse_size(limit, 1024, &val);
 256                         if (r >= 0) {
 257                                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", val);
 258                                 if (r < 0) {
 259                                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 260                                         return r;
 261                                 }
 262                         } else
 263                                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.limit: %s, ignoring.", limit);
 264                 }
 265         }
 266
 267         return 0;
 268 }
 269
 270 static int append_session_tasks_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 271         uint64_t val;
 272         int r;
 273
 274         /* No need to parse "infinity" here, it will be set unconditionally later in manager_start_scope() */
 275         if (isempty(limit) || streq(limit, "infinity"))
 276                 return 0;
 277
 278         r = safe_atou64(limit, &val);
 279         if (r >= 0) {
 280                 r = sd_bus_message_append(m, "(sv)", "TasksMax", "t", val);
 281                 if (r < 0) {
 282                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 283                         return r;
 284                 }
 285         } else
 286                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.limit: %s, ignoring.", limit);
 287
 288         return 0;
 289 }
 290
 291 static int append_session_cg_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit, const char *field) {
 292         uint64_t val;
 293         int r;
 294
 295         if (isempty(limit))
 296                 return 0;
 297
 298         r = cg_weight_parse(limit, &val);
 299         if (r >= 0) {
 300                 r = sd_bus_message_append(m, "(sv)", field, "t", val);
 301                 if (r < 0) {
 302                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 303                         return r;
 304                 }
 305         } else if (streq(field, "CPUWeight"))
 306                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.cpu_weight: %s, ignoring.", limit);
 307         else
 308                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.io_weight: %s, ignoring.", limit);
 309
 310         return 0;
 311 }
 312
 313 static const char* getenv_harder(pam_handle_t *handle, const char *key, const char *fallback) {
 314         const char *v;
 315
 316         assert(handle);
 317         assert(key);
 318
 319         /* Looks for an environment variable, preferrably in the environment block associated with the specified PAM
 320          * handle, falling back to the process' block instead. */
 321
 322         v = pam_getenv(handle, key);
 323         if (!isempty(v))
 324                 return v;
 325
 326         v = getenv(key);
 327         if (!isempty(v))
 328                 return v;
 329
 330         return fallback;
 331 }
 332
 333 static int update_environment(pam_handle_t *handle, const char *key, const char *value) {
 334         int r;
 335
 336         assert(handle);
 337         assert(key);
 338
 339         /* Updates the environment, but only if there's actually a value set. Also, log about errors */
 340
 341         if (isempty(value))
 342                 return PAM_SUCCESS;
 343
 344         r = pam_misc_setenv(handle, key, value, 0);
 345         if (r != PAM_SUCCESS)
 346                 pam_syslog(handle, LOG_ERR, "Failed to set environment variable %s.", key);
 347
 348         return r;
 349 }
 350
 351 static bool validate_runtime_directory(pam_handle_t *handle, const char *path, uid_t uid) {
 352         struct stat st;
 353
 354         assert(path);
 355
 356         /* Just some extra paranoia: let's not set $XDG_RUNTIME_DIR if the directory we'd set it to isn't actually set
 357          * up properly for us. */
 358
 359         if (lstat(path, &st) < 0) {
 360                 pam_syslog(handle, LOG_ERR, "Failed to stat() runtime directory '%s': %s", path, strerror(errno));
 361                 goto fail;
 362         }
 363
 364         if (!S_ISDIR(st.st_mode)) {
 365                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not actually a directory.", path);
 366                 goto fail;
 367         }
 368
 369         if (st.st_uid != uid) {
 370                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not owned by UID " UID_FMT ", as it should.", path, uid);
 371                 goto fail;
 372         }
 373
 374         return true;
 375
 376 fail:
 377         pam_syslog(handle, LOG_WARNING, "Not setting $XDG_RUNTIME_DIR, as the directory is not in order.");
 378         return false;
 379 }
 380
 381 _public_ PAM_EXTERN int pam_sm_open_session(
 382                 pam_handle_t *handle,
 383                 int flags,
 384                 int argc, const char **argv) {
 385
 386         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 387         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL, *reply = NULL;
 388         const char
 389                 *username, *id, *object_path, *runtime_path,
 390                 *service = NULL,
 391                 *tty = NULL, *display = NULL,
 392                 *remote_user = NULL, *remote_host = NULL,
 393                 *seat = NULL,
 394                 *type = NULL, *class = NULL,
 395                 *class_pam = NULL, *type_pam = NULL, *cvtnr = NULL, *desktop = NULL, *desktop_pam = NULL,
 396                 *memory_max = NULL, *tasks_max = NULL, *cpu_weight = NULL, *io_weight = NULL;
 397         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 398         int session_fd = -1, existing, r;
 399         bool debug = false, remote;
 400         struct passwd *pw;
 401         uint32_t vtnr = 0;
 402         uid_t original_uid;
 403
 404         assert(handle);
 405
 406         /* Make this a NOP on non-logind systems */
 407         if (!logind_running())
 408                 return PAM_SUCCESS;
 409
 410         if (parse_argv(handle,
 411                        argc, argv,
 412                        &class_pam,
 413                        &type_pam,
 414                        &desktop_pam,
 415                        &debug) < 0)
 416                 return PAM_SESSION_ERR;
 417
 418         if (debug)
 419                 pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing");
 420
 421         r = get_user_data(handle, &username, &pw);
 422         if (r != PAM_SUCCESS) {
 423                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 424                 return r;
 425         }
 426
 427         /* Make sure we don't enter a loop by talking to
 428          * systemd-logind when it is actually waiting for the
 429          * background to finish start-up. If the service is
 430          * "systemd-user" we simply set XDG_RUNTIME_DIR and
 431          * leave. */
 432
 433         pam_get_item(handle, PAM_SERVICE, (const void**) &service);
 434         if (streq_ptr(service, "systemd-user")) {
 435                 char rt[STRLEN("/run/user/") + DECIMAL_STR_MAX(uid_t)];
 436
 437                 xsprintf(rt, "/run/user/"UID_FMT, pw->pw_uid);
 438                 if (validate_runtime_directory(handle, rt, pw->pw_uid)) {
 439                         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
 440                         if (r != PAM_SUCCESS) {
 441                                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 442                                 return r;
 443                         }
 444                 }
 445
 446                 r = export_legacy_dbus_address(handle, pw->pw_uid, rt);
 447                 if (r != PAM_SUCCESS)
 448                         return r;
 449
 450                 return PAM_SUCCESS;
 451         }
 452
 453         /* Otherwise, we ask logind to create a session for us */
 454
 455         pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
 456         pam_get_item(handle, PAM_TTY, (const void**) &tty);
 457         pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
 458         pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
 459
 460         seat = getenv_harder(handle, "XDG_SEAT", NULL);
 461         cvtnr = getenv_harder(handle, "XDG_VTNR", NULL);
 462         type = getenv_harder(handle, "XDG_SESSION_TYPE", type_pam);
 463         class = getenv_harder(handle, "XDG_SESSION_CLASS", class_pam);
 464         desktop = getenv_harder(handle, "XDG_SESSION_DESKTOP", desktop_pam);
 465
 466         tty = strempty(tty);
 467
 468         if (strchr(tty, ':')) {
 469                 /* A tty with a colon is usually an X11 display, placed there to show up in utmp. We rearrange things
 470                  * and don't pretend that an X display was a tty. */
 471                 if (isempty(display))
 472                         display = tty;
 473                 tty = NULL;
 474
 475         } else if (streq(tty, "cron")) {
 476                 /* cron is setting PAM_TTY to "cron" for some reason (the commit carries no information why, but
 477                  * probably because it wants to set it to something as pam_time/pam_access/… require PAM_TTY to be set
 478                  * (as they otherwise even try to update it!) — but cron doesn't actually allocate a TTY for its forked
 479                  * off processes.) */
 480                 type = "unspecified";
 481                 class = "background";
 482                 tty = NULL;
 483
 484         } else if (streq(tty, "ssh")) {
 485                 /* ssh has been setting PAM_TTY to "ssh" (for the same reason as cron does this, see above. For further
 486                  * details look for "PAM_TTY_KLUDGE" in the openssh sources). */
 487                 type ="tty";
 488                 class = "user";
 489                 tty = NULL; /* This one is particularly sad, as this means that ssh sessions — even though usually
 490                              * associated with a pty — won't be tracked by their tty in logind. This is because ssh
 491                              * does the PAM session registration early for new connections, and registers a pty only
 492                              * much later (this is because it doesn't know yet if it needs one at all, as whether to
 493                              * register a pty or not is negotiated much later in the protocol). */
 494
 495         } else
 496                 /* Chop off leading /dev prefix that some clients specify, but others do not. */
 497                 tty = skip_dev_prefix(tty);
 498
 499         /* If this fails vtnr will be 0, that's intended */
 500         if (!isempty(cvtnr))
 501                 (void) safe_atou32(cvtnr, &vtnr);
 502
 503         if (!isempty(display) && !vtnr) {
 504                 if (isempty(seat))
 505                         (void) get_seat_from_display(display, &seat, &vtnr);
 506                 else if (streq(seat, "seat0"))
 507                         (void) get_seat_from_display(display, NULL, &vtnr);
 508         }
 509
 510         if (seat && !streq(seat, "seat0") && vtnr != 0) {
 511                 if (debug)
 512                         pam_syslog(handle, LOG_DEBUG, "Ignoring vtnr %"PRIu32" for %s which is not seat0", vtnr, seat);
 513                 vtnr = 0;
 514         }
 515
 516         if (isempty(type))
 517                 type = !isempty(display) ? "x11" :
 518                            !isempty(tty) ? "tty" : "unspecified";
 519
 520         if (isempty(class))
 521                 class = streq(type, "unspecified") ? "background" : "user";
 522
 523         remote = !isempty(remote_host) && !is_localhost(remote_host);
 524
 525         (void) pam_get_data(handle, "systemd.memory_max", (const void **)&memory_max);
 526         (void) pam_get_data(handle, "systemd.tasks_max",  (const void **)&tasks_max);
 527         (void) pam_get_data(handle, "systemd.cpu_weight", (const void **)&cpu_weight);
 528         (void) pam_get_data(handle, "systemd.io_weight",  (const void **)&io_weight);
 529
 530         /* Talk to logind over the message bus */
 531
 532         r = sd_bus_open_system(&bus);
 533         if (r < 0) {
 534                 pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r));
 535                 return PAM_SESSION_ERR;
 536         }
 537
 538         if (debug) {
 539                 pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: "
 540                            "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",
 541                            pw->pw_uid, getpid_cached(),
 542                            strempty(service),
 543                            type, class, strempty(desktop),
 544                            strempty(seat), vtnr, strempty(tty), strempty(display),
 545                            yes_no(remote), strempty(remote_user), strempty(remote_host));
 546                 pam_syslog(handle, LOG_DEBUG, "Session limits: "
 547                            "memory_max=%s tasks_max=%s cpu_weight=%s io_weight=%s",
 548                            strna(memory_max), strna(tasks_max), strna(cpu_weight), strna(io_weight));
 549         }
 550
 551         r = sd_bus_message_new_method_call(
 552                         bus,
 553                         &m,
 554                         "org.freedesktop.login1",
 555                         "/org/freedesktop/login1",
 556                         "org.freedesktop.login1.Manager",
 557                         "CreateSession");
 558         if (r < 0) {
 559                 pam_syslog(handle, LOG_ERR, "Failed to create CreateSession method call: %s", strerror(-r));
 560                 return PAM_SESSION_ERR;
 561         }
 562
 563         r = sd_bus_message_append(m, "uusssssussbss",
 564                         (uint32_t) pw->pw_uid,
 565                         0,
 566                         service,
 567                         type,
 568                         class,
 569                         desktop,
 570                         seat,
 571                         vtnr,
 572                         tty,
 573                         display,
 574                         remote,
 575                         remote_user,
 576                         remote_host);
 577         if (r < 0) {
 578                 pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
 579                 return PAM_SESSION_ERR;
 580         }
 581
 582         r = sd_bus_message_open_container(m, 'a', "(sv)");
 583         if (r < 0) {
 584                 pam_syslog(handle, LOG_ERR, "Failed to open message container: %s", strerror(-r));
 585                 return PAM_SYSTEM_ERR;
 586         }
 587
 588         r = append_session_memory_max(handle, m, memory_max);
 589         if (r < 0)
 590                 return PAM_SESSION_ERR;
 591
 592         r = append_session_tasks_max(handle, m, tasks_max);
 593         if (r < 0)
 594                 return PAM_SESSION_ERR;
 595
 596         r = append_session_cg_weight(handle, m, cpu_weight, "CPUWeight");
 597         if (r < 0)
 598                 return PAM_SESSION_ERR;
 599
 600         r = append_session_cg_weight(handle, m, io_weight, "IOWeight");
 601         if (r < 0)
 602                 return PAM_SESSION_ERR;
 603
 604         r = sd_bus_message_close_container(m);
 605         if (r < 0) {
 606                 pam_syslog(handle, LOG_ERR, "Failed to close message container: %s", strerror(-r));
 607                 return PAM_SYSTEM_ERR;
 608         }
 609
 610         r = sd_bus_call(bus, m, 0, &error, &reply);
 611         if (r < 0) {
 612                 if (sd_bus_error_has_name(&error, BUS_ERROR_SESSION_BUSY)) {
 613                         if (debug)
 614                                 pam_syslog(handle, LOG_DEBUG, "Not creating session: %s", bus_error_message(&error, r));
 615                         return PAM_SUCCESS;
 616                 } else {
 617                         pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r));
 618                         return PAM_SYSTEM_ERR;
 619                 }
 620         }
 621
 622         r = sd_bus_message_read(reply,
 623                                 "soshusub",
 624                                 &id,
 625                                 &object_path,
 626                                 &runtime_path,
 627                                 &session_fd,
 628                                 &original_uid,
 629                                 &seat,
 630                                 &vtnr,
 631                                 &existing);
 632         if (r < 0) {
 633                 pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", strerror(-r));
 634                 return PAM_SESSION_ERR;
 635         }
 636
 637         if (debug)
 638                 pam_syslog(handle, LOG_DEBUG, "Reply from logind: "
 639                            "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u original_uid=%u",
 640                            id, object_path, runtime_path, session_fd, seat, vtnr, original_uid);
 641
 642         r = update_environment(handle, "XDG_SESSION_ID", id);
 643         if (r != PAM_SUCCESS)
 644                 return r;
 645
 646         if (original_uid == pw->pw_uid) {
 647                 /* Don't set $XDG_RUNTIME_DIR if the user we now
 648                  * authenticated for does not match the original user
 649                  * of the session. We do this in order not to result
 650                  * in privileged apps clobbering the runtime directory
 651                  * unnecessarily. */
 652
 653                 if (validate_runtime_directory(handle, runtime_path, pw->pw_uid)) {
 654                         r = update_environment(handle, "XDG_RUNTIME_DIR", runtime_path);
 655                         if (r != PAM_SUCCESS)
 656                                 return r;
 657                 }
 658
 659                 r = export_legacy_dbus_address(handle, pw->pw_uid, runtime_path);
 660                 if (r != PAM_SUCCESS)
 661                         return r;
 662         }
 663
 664         /* Most likely we got the session/type/class from environment variables, but might have gotten the data
 665          * somewhere else (for example PAM module parameters). Let's now update the environment variables, so that this
 666          * data is inherited into the session processes, and programs can rely on them to be initialized. */
 667
 668         r = update_environment(handle, "XDG_SESSION_TYPE", type);
 669         if (r != PAM_SUCCESS)
 670                 return r;
 671
 672         r = update_environment(handle, "XDG_SESSION_CLASS", class);
 673         if (r != PAM_SUCCESS)
 674                 return r;
 675
 676         r = update_environment(handle, "XDG_SESSION_DESKTOP", desktop);
 677         if (r != PAM_SUCCESS)
 678                 return r;
 679
 680         r = update_environment(handle, "XDG_SEAT", seat);
 681         if (r != PAM_SUCCESS)
 682                 return r;
 683
 684         if (vtnr > 0) {
 685                 char buf[DECIMAL_STR_MAX(vtnr)];
 686                 sprintf(buf, "%u", vtnr);
 687
 688                 r = update_environment(handle, "XDG_VTNR", buf);
 689                 if (r != PAM_SUCCESS)
 690                         return r;
 691         }
 692
 693         r = pam_set_data(handle, "systemd.existing", INT_TO_PTR(!!existing), NULL);
 694         if (r != PAM_SUCCESS) {
 695                 pam_syslog(handle, LOG_ERR, "Failed to install existing flag.");
 696                 return r;
 697         }
 698
 699         if (session_fd >= 0) {
 700                 session_fd = fcntl(session_fd, F_DUPFD_CLOEXEC, 3);
 701                 if (session_fd < 0) {
 702                         pam_syslog(handle, LOG_ERR, "Failed to dup session fd: %m");
 703                         return PAM_SESSION_ERR;
 704                 }
 705
 706                 r = pam_set_data(handle, "systemd.session-fd", FD_TO_PTR(session_fd), NULL);
 707                 if (r != PAM_SUCCESS) {
 708                         pam_syslog(handle, LOG_ERR, "Failed to install session fd.");
 709                         safe_close(session_fd);
 710                         return r;
 711                 }
 712         }
 713
 714         return PAM_SUCCESS;
 715 }
 716
 717 _public_ PAM_EXTERN int pam_sm_close_session(
 718                 pam_handle_t *handle,
 719                 int flags,
 720                 int argc, const char **argv) {
 721
 722         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 723         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 724         const void *existing = NULL;
 725         const char *id;
 726         int r;
 727
 728         assert(handle);
 729
 730         /* Only release session if it wasn't pre-existing when we
 731          * tried to create it */
 732         (void) pam_get_data(handle, "systemd.existing", &existing);
 733
 734         id = pam_getenv(handle, "XDG_SESSION_ID");
 735         if (id && !existing) {
 736
 737                 /* Before we go and close the FIFO we need to tell
 738                  * logind that this is a clean session shutdown, so
 739                  * that it doesn't just go and slaughter us
 740                  * immediately after closing the fd */
 741
 742                 r = sd_bus_open_system(&bus);
 743                 if (r < 0) {
 744                         pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r));
 745                         return PAM_SESSION_ERR;
 746                 }
 747
 748                 r = sd_bus_call_method(bus,
 749                                        "org.freedesktop.login1",
 750                                        "/org/freedesktop/login1",
 751                                        "org.freedesktop.login1.Manager",
 752                                        "ReleaseSession",
 753                                        &error,
 754                                        NULL,
 755                                        "s",
 756                                        id);
 757                 if (r < 0) {
 758                         pam_syslog(handle, LOG_ERR, "Failed to release session: %s", bus_error_message(&error, r));
 759                         return PAM_SESSION_ERR;
 760                 }
 761         }
 762
 763         /* Note that we are knowingly leaking the FIFO fd here. This
 764          * way, logind can watch us die. If we closed it here it would
 765          * not have any clue when that is completed. Given that one
 766          * cannot really have multiple PAM sessions open from the same
 767          * process this means we will leak one FD at max. */
 768
 769         return PAM_SUCCESS;
 770 }