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