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