src/login/pam_systemd.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <endian.h>
   4 #include <errno.h>
   5 #include <fcntl.h>
   6 #include <pwd.h>
   7 #include <security/_pam_macros.h>
   8 #include <security/pam_ext.h>
   9 #include <security/pam_misc.h>
  10 #include <security/pam_modules.h>
  11 #include <security/pam_modutil.h>
  12 #include <sys/file.h>
  13 #include <sys/stat.h>
  14 #include <sys/types.h>
  15 #include <unistd.h>
  16
  17 #include "alloc-util.h"
  18 #include "audit-util.h"
  19 #include "bus-common-errors.h"
  20 #include "bus-error.h"
  21 #include "bus-internal.h"
  22 #include "bus-util.h"
  23 #include "cgroup-util.h"
  24 #include "errno-util.h"
  25 #include "fd-util.h"
  26 #include "fileio.h"
  27 #include "format-util.h"
  28 #include "hostname-util.h"
  29 #include "login-util.h"
  30 #include "macro.h"
  31 #include "parse-util.h"
  32 #include "path-util.h"
  33 #include "process-util.h"
  34 #include "socket-util.h"
  35 #include "stdio-util.h"
  36 #include "strv.h"
  37 #include "terminal-util.h"
  38
  39 static int parse_argv(
  40                 pam_handle_t *handle,
  41                 int argc, const char **argv,
  42                 const char **class,
  43                 const char **type,
  44                 const char **desktop,
  45                 bool *debug) {
  46
  47         unsigned i;
  48
  49         assert(argc >= 0);
  50         assert(argc == 0 || argv);
  51
  52         for (i = 0; i < (unsigned) argc; i++) {
  53                 if (startswith(argv[i], "class=")) {
  54                         if (class)
  55                                 *class = argv[i] + 6;
  56
  57                 } else if (startswith(argv[i], "type=")) {
  58                         if (type)
  59                                 *type = argv[i] + 5;
  60
  61                 } else if (startswith(argv[i], "desktop=")) {
  62                         if (desktop)
  63                                 *desktop = argv[i] + 8;
  64
  65                 } else if (streq(argv[i], "debug")) {
  66                         if (debug)
  67                                 *debug = true;
  68
  69                 } else if (startswith(argv[i], "debug=")) {
  70                         int k;
  71
  72                         k = parse_boolean(argv[i] + 6);
  73                         if (k < 0)
  74                                 pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring.");
  75                         else if (debug)
  76                                 *debug = k;
  77
  78                 } else
  79                         pam_syslog(handle, LOG_WARNING, "Unknown parameter '%s', ignoring", argv[i]);
  80         }
  81
  82         return 0;
  83 }
  84
  85 static int get_user_data(
  86                 pam_handle_t *handle,
  87                 const char **ret_username,
  88                 struct passwd **ret_pw) {
  89
  90         const char *username = NULL;
  91         struct passwd *pw = NULL;
  92         int r;
  93
  94         assert(handle);
  95         assert(ret_username);
  96         assert(ret_pw);
  97
  98         r = pam_get_user(handle, &username, NULL);
  99         if (r != PAM_SUCCESS) {
 100                 pam_syslog(handle, LOG_ERR, "Failed to get user name.");
 101                 return r;
 102         }
 103
 104         if (isempty(username)) {
 105                 pam_syslog(handle, LOG_ERR, "User name not valid.");
 106                 return PAM_AUTH_ERR;
 107         }
 108
 109         pw = pam_modutil_getpwnam(handle, username);
 110         if (!pw) {
 111                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 112                 return PAM_USER_UNKNOWN;
 113         }
 114
 115         *ret_pw = pw;
 116         *ret_username = username;
 117
 118         return PAM_SUCCESS;
 119 }
 120
 121 static bool display_is_local(const char *display) {
 122         assert(display);
 123
 124         return
 125                 display[0] == ':' &&
 126                 display[1] >= '0' &&
 127                 display[1] <= '9';
 128 }
 129
 130 static int socket_from_display(const char *display, char **path) {
 131         size_t k;
 132         char *f, *c;
 133
 134         assert(display);
 135         assert(path);
 136
 137         if (!display_is_local(display))
 138                 return -EINVAL;
 139
 140         k = strspn(display+1, "0123456789");
 141
 142         f = new(char, STRLEN("/tmp/.X11-unix/X") + k + 1);
 143         if (!f)
 144                 return -ENOMEM;
 145
 146         c = stpcpy(f, "/tmp/.X11-unix/X");
 147         memcpy(c, display+1, k);
 148         c[k] = 0;
 149
 150         *path = f;
 151
 152         return 0;
 153 }
 154
 155 static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
 156         union sockaddr_union sa = {};
 157         _cleanup_free_ char *p = NULL, *tty = NULL;
 158         _cleanup_close_ int fd = -1;
 159         struct ucred ucred;
 160         int v, r, salen;
 161
 162         assert(display);
 163         assert(vtnr);
 164
 165         /* We deduce the X11 socket from the display name, then use
 166          * SO_PEERCRED to determine the X11 server process, ask for
 167          * the controlling tty of that and if it's a VC then we know
 168          * the seat and the virtual terminal. Sounds ugly, is only
 169          * semi-ugly. */
 170
 171         r = socket_from_display(display, &p);
 172         if (r < 0)
 173                 return r;
 174         salen = sockaddr_un_set_path(&sa.un, p);
 175         if (salen < 0)
 176                 return salen;
 177
 178         fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
 179         if (fd < 0)
 180                 return -errno;
 181
 182         if (connect(fd, &sa.sa, salen) < 0)
 183                 return -errno;
 184
 185         r = getpeercred(fd, &ucred);
 186         if (r < 0)
 187                 return r;
 188
 189         r = get_ctty(ucred.pid, NULL, &tty);
 190         if (r < 0)
 191                 return r;
 192
 193         v = vtnr_from_tty(tty);
 194         if (v < 0)
 195                 return v;
 196         else if (v == 0)
 197                 return -ENOENT;
 198
 199         if (seat)
 200                 *seat = "seat0";
 201         *vtnr = (uint32_t) v;
 202
 203         return 0;
 204 }
 205
 206 static int export_legacy_dbus_address(
 207                 pam_handle_t *handle,
 208                 uid_t uid,
 209                 const char *runtime) {
 210
 211         const char *s;
 212         _cleanup_free_ char *t = NULL;
 213         int r = PAM_BUF_ERR;
 214
 215         /* We need to export $DBUS_SESSION_BUS_ADDRESS because various applications will not connect
 216          * correctly to the bus without it. This setting matches what dbus.socket does for the user
 217          * session using 'systemctl --user set-environment'. We want to have the same configuration
 218          * in processes started from the PAM session.
 219          *
 220          * The setting of the address is guarded by the access() check because it is also possible to compile
 221          * dbus without --enable-user-session, in which case this socket is not used, and
 222          * $DBUS_SESSION_BUS_ADDRESS should not be set. An alternative approach would to not do the access()
 223          * check here, and let applications try on their own, by using "unix:path=%s/bus;autolaunch:". But we
 224          * expect the socket to be present by the time we do this check, so we can just as well check once
 225          * here. */
 226
 227         s = strjoina(runtime, "/bus");
 228         if (access(s, F_OK) < 0)
 229                 return PAM_SUCCESS;
 230
 231         if (asprintf(&t, DEFAULT_USER_BUS_ADDRESS_FMT, runtime) < 0)
 232                 goto error;
 233
 234         r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", t, 0);
 235         if (r != PAM_SUCCESS)
 236                 goto error;
 237
 238         return PAM_SUCCESS;
 239
 240 error:
 241         pam_syslog(handle, LOG_ERR, "Failed to set bus variable.");
 242         return r;
 243 }
 244
 245 static int append_session_memory_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 246         uint64_t val;
 247         int r;
 248
 249         if (isempty(limit))
 250                 return 0;
 251
 252         if (streq(limit, "infinity")) {
 253                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", (uint64_t)-1);
 254                 if (r < 0) {
 255                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror_safe(r));
 256                         return r;
 257                 }
 258         } else {
 259                 r = parse_permille(limit);
 260                 if (r >= 0) {
 261                         r = sd_bus_message_append(m, "(sv)", "MemoryMaxScale", "u", (uint32_t) (((uint64_t) r * UINT32_MAX) / 1000U));
 262                         if (r < 0) {
 263                                 pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror_safe(r));
 264                                 return r;
 265                         }
 266                 } else {
 267                         r = parse_size(limit, 1024, &val);
 268                         if (r >= 0) {
 269                                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", val);
 270                                 if (r < 0) {
 271                                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror_safe(r));
 272                                         return r;
 273                                 }
 274                         } else
 275                                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.memory_max: %s, ignoring.", limit);
 276                 }
 277         }
 278
 279         return 0;
 280 }
 281
 282 static int append_session_runtime_max_sec(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 283         usec_t val;
 284         int r;
 285
 286         /* No need to parse "infinity" here, it will be set by default later in scope_init() */
 287         if (isempty(limit) || streq(limit, "infinity"))
 288                 return 0;
 289
 290         r = parse_sec(limit, &val);
 291         if (r >= 0) {
 292                 r = sd_bus_message_append(m, "(sv)", "RuntimeMaxUSec", "t", (uint64_t) val);
 293                 if (r < 0) {
 294                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror_safe(r));
 295                         return r;
 296                 }
 297         } else
 298                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.runtime_max_sec: %s, ignoring.", limit);
 299
 300         return 0;
 301 }
 302
 303 static int append_session_tasks_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 304         uint64_t val;
 305         int r;
 306
 307         /* No need to parse "infinity" here, it will be set unconditionally later in manager_start_scope() */
 308         if (isempty(limit) || streq(limit, "infinity"))
 309                 return 0;
 310
 311         r = safe_atou64(limit, &val);
 312         if (r >= 0) {
 313                 r = sd_bus_message_append(m, "(sv)", "TasksMax", "t", val);
 314                 if (r < 0) {
 315                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror_safe(r));
 316                         return r;
 317                 }
 318         } else
 319                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.tasks_max: %s, ignoring.", limit);
 320
 321         return 0;
 322 }
 323
 324 static int append_session_cg_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit, const char *field) {
 325         uint64_t val;
 326         int r;
 327
 328         if (isempty(limit))
 329                 return 0;
 330
 331         r = cg_weight_parse(limit, &val);
 332         if (r >= 0) {
 333                 r = sd_bus_message_append(m, "(sv)", field, "t", val);
 334                 if (r < 0) {
 335                         pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror_safe(r));
 336                         return r;
 337                 }
 338         } else if (streq(field, "CPUWeight"))
 339                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.cpu_weight: %s, ignoring.", limit);
 340         else
 341                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.io_weight: %s, ignoring.", limit);
 342
 343         return 0;
 344 }
 345
 346 static const char* getenv_harder(pam_handle_t *handle, const char *key, const char *fallback) {
 347         const char *v;
 348
 349         assert(handle);
 350         assert(key);
 351
 352         /* Looks for an environment variable, preferably in the environment block associated with the
 353          * specified PAM handle, falling back to the process' block instead. Why check both? Because we want
 354          * to permit configuration of session properties from unit files that invoke PAM services, so that
 355          * PAM services don't have to be reworked to set systemd-specific properties, but these properties
 356          * can still be set from the unit file Environment= block. */
 357
 358         v = pam_getenv(handle, key);
 359         if (!isempty(v))
 360                 return v;
 361
 362         /* We use secure_getenv() here, since we might get loaded into su/sudo, which are SUID. Ideally
 363          * they'd clean up the environment before invoking foreign code (such as PAM modules), but alas they
 364          * currently don't (to be precise, they clean up the environment they pass to their children, but
 365          * not their own environ[]). */
 366         v = secure_getenv(key);
 367         if (!isempty(v))
 368                 return v;
 369
 370         return fallback;
 371 }
 372
 373 static int update_environment(pam_handle_t *handle, const char *key, const char *value) {
 374         int r;
 375
 376         assert(handle);
 377         assert(key);
 378
 379         /* Updates the environment, but only if there's actually a value set. Also, log about errors */
 380
 381         if (isempty(value))
 382                 return PAM_SUCCESS;
 383
 384         r = pam_misc_setenv(handle, key, value, 0);
 385         if (r != PAM_SUCCESS)
 386                 pam_syslog(handle, LOG_ERR, "Failed to set environment variable %s.", key);
 387
 388         return r;
 389 }
 390
 391 static bool validate_runtime_directory(pam_handle_t *handle, const char *path, uid_t uid) {
 392         struct stat st;
 393
 394         assert(path);
 395
 396         /* Just some extra paranoia: let's not set $XDG_RUNTIME_DIR if the directory we'd set it to isn't actually set
 397          * up properly for us. */
 398
 399         if (lstat(path, &st) < 0) {
 400                 pam_syslog(handle, LOG_ERR, "Failed to stat() runtime directory '%s': %s", path, strerror_safe(errno));
 401                 goto fail;
 402         }
 403
 404         if (!S_ISDIR(st.st_mode)) {
 405                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not actually a directory.", path);
 406                 goto fail;
 407         }
 408
 409         if (st.st_uid != uid) {
 410                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not owned by UID " UID_FMT ", as it should.", path, uid);
 411                 goto fail;
 412         }
 413
 414         return true;
 415
 416 fail:
 417         pam_syslog(handle, LOG_WARNING, "Not setting $XDG_RUNTIME_DIR, as the directory is not in order.");
 418         return false;
 419 }
 420
 421 _public_ PAM_EXTERN int pam_sm_open_session(
 422                 pam_handle_t *handle,
 423                 int flags,
 424                 int argc, const char **argv) {
 425
 426         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 427         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL, *reply = NULL;
 428         const char
 429                 *username, *id, *object_path, *runtime_path,
 430                 *service = NULL,
 431                 *tty = NULL, *display = NULL,
 432                 *remote_user = NULL, *remote_host = NULL,
 433                 *seat = NULL,
 434                 *type = NULL, *class = NULL,
 435                 *class_pam = NULL, *type_pam = NULL, *cvtnr = NULL, *desktop = NULL, *desktop_pam = NULL,
 436                 *memory_max = NULL, *tasks_max = NULL, *cpu_weight = NULL, *io_weight = NULL, *runtime_max_sec = NULL;
 437         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 438         int session_fd = -1, existing, r;
 439         bool debug = false, remote;
 440         struct passwd *pw;
 441         uint32_t vtnr = 0;
 442         uid_t original_uid;
 443
 444         assert(handle);
 445
 446         /* Make this a NOP on non-logind systems */
 447         if (!logind_running())
 448                 return PAM_SUCCESS;
 449
 450         if (parse_argv(handle,
 451                        argc, argv,
 452                        &class_pam,
 453                        &type_pam,
 454                        &desktop_pam,
 455                        &debug) < 0)
 456                 return PAM_SESSION_ERR;
 457
 458         if (debug)
 459                 pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing");
 460
 461         r = get_user_data(handle, &username, &pw);
 462         if (r != PAM_SUCCESS) {
 463                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 464                 return r;
 465         }
 466
 467         /* Make sure we don't enter a loop by talking to
 468          * systemd-logind when it is actually waiting for the
 469          * background to finish start-up. If the service is
 470          * "systemd-user" we simply set XDG_RUNTIME_DIR and
 471          * leave. */
 472
 473         pam_get_item(handle, PAM_SERVICE, (const void**) &service);
 474         if (streq_ptr(service, "systemd-user")) {
 475                 char rt[STRLEN("/run/user/") + DECIMAL_STR_MAX(uid_t)];
 476
 477                 xsprintf(rt, "/run/user/"UID_FMT, pw->pw_uid);
 478                 if (validate_runtime_directory(handle, rt, pw->pw_uid)) {
 479                         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
 480                         if (r != PAM_SUCCESS) {
 481                                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 482                                 return r;
 483                         }
 484                 }
 485
 486                 r = export_legacy_dbus_address(handle, pw->pw_uid, rt);
 487                 if (r != PAM_SUCCESS)
 488                         return r;
 489
 490                 return PAM_SUCCESS;
 491         }
 492
 493         /* Otherwise, we ask logind to create a session for us */
 494
 495         pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
 496         pam_get_item(handle, PAM_TTY, (const void**) &tty);
 497         pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
 498         pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
 499
 500         seat = getenv_harder(handle, "XDG_SEAT", NULL);
 501         cvtnr = getenv_harder(handle, "XDG_VTNR", NULL);
 502         type = getenv_harder(handle, "XDG_SESSION_TYPE", type_pam);
 503         class = getenv_harder(handle, "XDG_SESSION_CLASS", class_pam);
 504         desktop = getenv_harder(handle, "XDG_SESSION_DESKTOP", desktop_pam);
 505
 506         tty = strempty(tty);
 507
 508         if (strchr(tty, ':')) {
 509                 /* A tty with a colon is usually an X11 display, placed there to show up in utmp. We rearrange things
 510                  * and don't pretend that an X display was a tty. */
 511                 if (isempty(display))
 512                         display = tty;
 513                 tty = NULL;
 514
 515         } else if (streq(tty, "cron")) {
 516                 /* cron is setting PAM_TTY to "cron" for some reason (the commit carries no information why, but
 517                  * probably because it wants to set it to something as pam_time/pam_access/… require PAM_TTY to be set
 518                  * (as they otherwise even try to update it!) — but cron doesn't actually allocate a TTY for its forked
 519                  * off processes.) */
 520                 type = "unspecified";
 521                 class = "background";
 522                 tty = NULL;
 523
 524         } else if (streq(tty, "ssh")) {
 525                 /* ssh has been setting PAM_TTY to "ssh" (for the same reason as cron does this, see above. For further
 526                  * details look for "PAM_TTY_KLUDGE" in the openssh sources). */
 527                 type ="tty";
 528                 class = "user";
 529                 tty = NULL; /* This one is particularly sad, as this means that ssh sessions — even though usually
 530                              * associated with a pty — won't be tracked by their tty in logind. This is because ssh
 531                              * does the PAM session registration early for new connections, and registers a pty only
 532                              * much later (this is because it doesn't know yet if it needs one at all, as whether to
 533                              * register a pty or not is negotiated much later in the protocol). */
 534
 535         } else
 536                 /* Chop off leading /dev prefix that some clients specify, but others do not. */
 537                 tty = skip_dev_prefix(tty);
 538
 539         /* If this fails vtnr will be 0, that's intended */
 540         if (!isempty(cvtnr))
 541                 (void) safe_atou32(cvtnr, &vtnr);
 542
 543         if (!isempty(display) && !vtnr) {
 544                 if (isempty(seat))
 545                         (void) get_seat_from_display(display, &seat, &vtnr);
 546                 else if (streq(seat, "seat0"))
 547                         (void) get_seat_from_display(display, NULL, &vtnr);
 548         }
 549
 550         if (seat && !streq(seat, "seat0") && vtnr != 0) {
 551                 if (debug)
 552                         pam_syslog(handle, LOG_DEBUG, "Ignoring vtnr %"PRIu32" for %s which is not seat0", vtnr, seat);
 553                 vtnr = 0;
 554         }
 555
 556         if (isempty(type))
 557                 type = !isempty(display) ? "x11" :
 558                            !isempty(tty) ? "tty" : "unspecified";
 559
 560         if (isempty(class))
 561                 class = streq(type, "unspecified") ? "background" : "user";
 562
 563         remote = !isempty(remote_host) && !is_localhost(remote_host);
 564
 565         (void) pam_get_data(handle, "systemd.memory_max", (const void **)&memory_max);
 566         (void) pam_get_data(handle, "systemd.tasks_max",  (const void **)&tasks_max);
 567         (void) pam_get_data(handle, "systemd.cpu_weight", (const void **)&cpu_weight);
 568         (void) pam_get_data(handle, "systemd.io_weight",  (const void **)&io_weight);
 569         (void) pam_get_data(handle, "systemd.runtime_max_sec", (const void **)&runtime_max_sec);
 570
 571         /* Talk to logind over the message bus */
 572
 573         r = sd_bus_open_system(&bus);
 574         if (r < 0) {
 575                 pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror_safe(r));
 576                 return PAM_SESSION_ERR;
 577         }
 578
 579         if (debug) {
 580                 pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: "
 581                            "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",
 582                            pw->pw_uid, getpid_cached(),
 583                            strempty(service),
 584                            type, class, strempty(desktop),
 585                            strempty(seat), vtnr, strempty(tty), strempty(display),
 586                            yes_no(remote), strempty(remote_user), strempty(remote_host));
 587                 pam_syslog(handle, LOG_DEBUG, "Session limits: "
 588                            "memory_max=%s tasks_max=%s cpu_weight=%s io_weight=%s runtime_max_sec=%s",
 589                            strna(memory_max), strna(tasks_max), strna(cpu_weight), strna(io_weight), strna(runtime_max_sec));
 590         }
 591
 592         r = sd_bus_message_new_method_call(
 593                         bus,
 594                         &m,
 595                         "org.freedesktop.login1",
 596                         "/org/freedesktop/login1",
 597                         "org.freedesktop.login1.Manager",
 598                         "CreateSession");
 599         if (r < 0) {
 600                 pam_syslog(handle, LOG_ERR, "Failed to create CreateSession method call: %s", strerror_safe(r));
 601                 return PAM_SESSION_ERR;
 602         }
 603
 604         r = sd_bus_message_append(m, "uusssssussbss",
 605                         (uint32_t) pw->pw_uid,
 606                         0,
 607                         service,
 608                         type,
 609                         class,
 610                         desktop,
 611                         seat,
 612                         vtnr,
 613                         tty,
 614                         display,
 615                         remote,
 616                         remote_user,
 617                         remote_host);
 618         if (r < 0) {
 619                 pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror_safe(r));
 620                 return PAM_SESSION_ERR;
 621         }
 622
 623         r = sd_bus_message_open_container(m, 'a', "(sv)");
 624         if (r < 0) {
 625                 pam_syslog(handle, LOG_ERR, "Failed to open message container: %s", strerror_safe(r));
 626                 return PAM_SYSTEM_ERR;
 627         }
 628
 629         r = append_session_memory_max(handle, m, memory_max);
 630         if (r < 0)
 631                 return PAM_SESSION_ERR;
 632
 633         r = append_session_runtime_max_sec(handle, m, runtime_max_sec);
 634         if (r < 0)
 635                 return PAM_SESSION_ERR;
 636
 637         r = append_session_tasks_max(handle, m, tasks_max);
 638         if (r < 0)
 639                 return PAM_SESSION_ERR;
 640
 641         r = append_session_cg_weight(handle, m, cpu_weight, "CPUWeight");
 642         if (r < 0)
 643                 return PAM_SESSION_ERR;
 644
 645         r = append_session_cg_weight(handle, m, io_weight, "IOWeight");
 646         if (r < 0)
 647                 return PAM_SESSION_ERR;
 648
 649         r = sd_bus_message_close_container(m);
 650         if (r < 0) {
 651                 pam_syslog(handle, LOG_ERR, "Failed to close message container: %s", strerror_safe(r));
 652                 return PAM_SYSTEM_ERR;
 653         }
 654
 655         r = sd_bus_call(bus, m, 0, &error, &reply);
 656         if (r < 0) {
 657                 if (sd_bus_error_has_name(&error, BUS_ERROR_SESSION_BUSY)) {
 658                         if (debug)
 659                                 pam_syslog(handle, LOG_DEBUG, "Not creating session: %s", bus_error_message(&error, r));
 660                         return PAM_SUCCESS;
 661                 } else {
 662                         pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r));
 663                         return PAM_SYSTEM_ERR;
 664                 }
 665         }
 666
 667         r = sd_bus_message_read(reply,
 668                                 "soshusub",
 669                                 &id,
 670                                 &object_path,
 671                                 &runtime_path,
 672                                 &session_fd,
 673                                 &original_uid,
 674                                 &seat,
 675                                 &vtnr,
 676                                 &existing);
 677         if (r < 0) {
 678                 pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", strerror_safe(r));
 679                 return PAM_SESSION_ERR;
 680         }
 681
 682         if (debug)
 683                 pam_syslog(handle, LOG_DEBUG, "Reply from logind: "
 684                            "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u original_uid=%u",
 685                            id, object_path, runtime_path, session_fd, seat, vtnr, original_uid);
 686
 687         r = update_environment(handle, "XDG_SESSION_ID", id);
 688         if (r != PAM_SUCCESS)
 689                 return r;
 690
 691         if (original_uid == pw->pw_uid) {
 692                 /* Don't set $XDG_RUNTIME_DIR if the user we now
 693                  * authenticated for does not match the original user
 694                  * of the session. We do this in order not to result
 695                  * in privileged apps clobbering the runtime directory
 696                  * unnecessarily. */
 697
 698                 if (validate_runtime_directory(handle, runtime_path, pw->pw_uid)) {
 699                         r = update_environment(handle, "XDG_RUNTIME_DIR", runtime_path);
 700                         if (r != PAM_SUCCESS)
 701                                 return r;
 702                 }
 703
 704                 r = export_legacy_dbus_address(handle, pw->pw_uid, runtime_path);
 705                 if (r != PAM_SUCCESS)
 706                         return r;
 707         }
 708
 709         /* Most likely we got the session/type/class from environment variables, but might have gotten the data
 710          * somewhere else (for example PAM module parameters). Let's now update the environment variables, so that this
 711          * data is inherited into the session processes, and programs can rely on them to be initialized. */
 712
 713         r = update_environment(handle, "XDG_SESSION_TYPE", type);
 714         if (r != PAM_SUCCESS)
 715                 return r;
 716
 717         r = update_environment(handle, "XDG_SESSION_CLASS", class);
 718         if (r != PAM_SUCCESS)
 719                 return r;
 720
 721         r = update_environment(handle, "XDG_SESSION_DESKTOP", desktop);
 722         if (r != PAM_SUCCESS)
 723                 return r;
 724
 725         r = update_environment(handle, "XDG_SEAT", seat);
 726         if (r != PAM_SUCCESS)
 727                 return r;
 728
 729         if (vtnr > 0) {
 730                 char buf[DECIMAL_STR_MAX(vtnr)];
 731                 sprintf(buf, "%u", vtnr);
 732
 733                 r = update_environment(handle, "XDG_VTNR", buf);
 734                 if (r != PAM_SUCCESS)
 735                         return r;
 736         }
 737
 738         r = pam_set_data(handle, "systemd.existing", INT_TO_PTR(!!existing), NULL);
 739         if (r != PAM_SUCCESS) {
 740                 pam_syslog(handle, LOG_ERR, "Failed to install existing flag.");
 741                 return r;
 742         }
 743
 744         if (session_fd >= 0) {
 745                 session_fd = fcntl(session_fd, F_DUPFD_CLOEXEC, 3);
 746                 if (session_fd < 0) {
 747                         pam_syslog(handle, LOG_ERR, "Failed to dup session fd: %m");
 748                         return PAM_SESSION_ERR;
 749                 }
 750
 751                 r = pam_set_data(handle, "systemd.session-fd", FD_TO_PTR(session_fd), NULL);
 752                 if (r != PAM_SUCCESS) {
 753                         pam_syslog(handle, LOG_ERR, "Failed to install session fd.");
 754                         safe_close(session_fd);
 755                         return r;
 756                 }
 757         }
 758
 759         return PAM_SUCCESS;
 760 }
 761
 762 _public_ PAM_EXTERN int pam_sm_close_session(
 763                 pam_handle_t *handle,
 764                 int flags,
 765                 int argc, const char **argv) {
 766
 767         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 768         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 769         const void *existing = NULL;
 770         const char *id;
 771         int r;
 772
 773         assert(handle);
 774
 775         /* Only release session if it wasn't pre-existing when we
 776          * tried to create it */
 777         (void) pam_get_data(handle, "systemd.existing", &existing);
 778
 779         id = pam_getenv(handle, "XDG_SESSION_ID");
 780         if (id && !existing) {
 781
 782                 /* Before we go and close the FIFO we need to tell
 783                  * logind that this is a clean session shutdown, so
 784                  * that it doesn't just go and slaughter us
 785                  * immediately after closing the fd */
 786
 787                 r = sd_bus_open_system(&bus);
 788                 if (r < 0) {
 789                         pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror_safe(r));
 790                         return PAM_SESSION_ERR;
 791                 }
 792
 793                 r = sd_bus_call_method(bus,
 794                                        "org.freedesktop.login1",
 795                                        "/org/freedesktop/login1",
 796                                        "org.freedesktop.login1.Manager",
 797                                        "ReleaseSession",
 798                                        &error,
 799                                        NULL,
 800                                        "s",
 801                                        id);
 802                 if (r < 0) {
 803                         pam_syslog(handle, LOG_ERR, "Failed to release session: %s", bus_error_message(&error, r));
 804                         return PAM_SESSION_ERR;
 805                 }
 806         }
 807
 808         /* Note that we are knowingly leaking the FIFO fd here. This
 809          * way, logind can watch us die. If we closed it here it would
 810          * not have any clue when that is completed. Given that one
 811          * cannot really have multiple PAM sessions open from the same
 812          * process this means we will leak one FD at max. */
 813
 814         return PAM_SUCCESS;
 815 }