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/sysmacros.h>
  15 #include <sys/types.h>
  16 #include <unistd.h>
  17
  18 #include "alloc-util.h"
  19 #include "audit-util.h"
  20 #include "bus-common-errors.h"
  21 #include "bus-error.h"
  22 #include "bus-internal.h"
  23 #include "bus-locator.h"
  24 #include "cgroup-setup.h"
  25 #include "errno-util.h"
  26 #include "fd-util.h"
  27 #include "fileio.h"
  28 #include "format-util.h"
  29 #include "fs-util.h"
  30 #include "hostname-util.h"
  31 #include "locale-util.h"
  32 #include "login-util.h"
  33 #include "macro.h"
  34 #include "pam-util.h"
  35 #include "parse-util.h"
  36 #include "path-util.h"
  37 #include "process-util.h"
  38 #include "rlimit-util.h"
  39 #include "socket-util.h"
  40 #include "stdio-util.h"
  41 #include "strv.h"
  42 #include "terminal-util.h"
  43 #include "user-util.h"
  44 #include "userdb.h"
  45
  46 #define LOGIN_SLOW_BUS_CALL_TIMEOUT_USEC (2*USEC_PER_MINUTE)
  47
  48 static int parse_argv(
  49                 pam_handle_t *handle,
  50                 int argc, const char **argv,
  51                 const char **class,
  52                 const char **type,
  53                 const char **desktop,
  54                 bool *debug) {
  55
  56         unsigned i;
  57
  58         assert(argc >= 0);
  59         assert(argc == 0 || argv);
  60
  61         for (i = 0; i < (unsigned) argc; i++) {
  62                 const char *p;
  63
  64                 if ((p = startswith(argv[i], "class="))) {
  65                         if (class)
  66                                 *class = p;
  67
  68                 } else if ((p = startswith(argv[i], "type="))) {
  69                         if (type)
  70                                 *type = p;
  71
  72                 } else if ((p = startswith(argv[i], "desktop="))) {
  73                         if (desktop)
  74                                 *desktop = p;
  75
  76                 } else if (streq(argv[i], "debug")) {
  77                         if (debug)
  78                                 *debug = true;
  79
  80                 } else if ((p = startswith(argv[i], "debug="))) {
  81                         int k;
  82
  83                         k = parse_boolean(p);
  84                         if (k < 0)
  85                                 pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring: %s", p);
  86                         else if (debug)
  87                                 *debug = k;
  88
  89                 } else
  90                         pam_syslog(handle, LOG_WARNING, "Unknown parameter '%s', ignoring", argv[i]);
  91         }
  92
  93         return 0;
  94 }
  95
  96 static int acquire_user_record(
  97                 pam_handle_t *handle,
  98                 UserRecord **ret_record) {
  99
 100         _cleanup_(user_record_unrefp) UserRecord *ur = NULL;
 101         const char *username = NULL, *json = NULL;
 102         _cleanup_free_ char *field = NULL;
 103         int r;
 104
 105         assert(handle);
 106
 107         r = pam_get_user(handle, &username, NULL);
 108         if (r != PAM_SUCCESS) {
 109                 pam_syslog(handle, LOG_ERR, "Failed to get user name: %s", pam_strerror(handle, r));
 110                 return r;
 111         }
 112
 113         if (isempty(username)) {
 114                 pam_syslog(handle, LOG_ERR, "User name not valid.");
 115                 return PAM_SERVICE_ERR;
 116         }
 117
 118         /* If pam_systemd_homed (or some other module) already acquired the user record we can reuse it
 119          * here. */
 120         field = strjoin("systemd-user-record-", username);
 121         if (!field)
 122                 return pam_log_oom(handle);
 123
 124         r = pam_get_data(handle, field, (const void**) &json);
 125         if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) {
 126                 pam_syslog(handle, LOG_ERR, "Failed to get PAM user record data: %s", pam_strerror(handle, r));
 127                 return r;
 128         }
 129         if (r == PAM_SUCCESS && json) {
 130                 _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
 131
 132                 /* Parse cached record */
 133                 r = json_parse(json, JSON_PARSE_SENSITIVE, &v, NULL, NULL);
 134                 if (r < 0) {
 135                         pam_syslog(handle, LOG_ERR, "Failed to parse JSON user record: %s", strerror_safe(r));
 136                         return PAM_SERVICE_ERR;
 137                 }
 138
 139                 ur = user_record_new();
 140                 if (!ur)
 141                         return pam_log_oom(handle);
 142
 143                 r = user_record_load(ur, v, USER_RECORD_LOAD_REFUSE_SECRET);
 144                 if (r < 0) {
 145                         pam_syslog(handle, LOG_ERR, "Failed to load user record: %s", strerror_safe(r));
 146                         return PAM_SERVICE_ERR;
 147                 }
 148
 149                 /* Safety check if cached record actually matches what we are looking for */
 150                 if (!streq_ptr(username, ur->user_name)) {
 151                         pam_syslog(handle, LOG_ERR, "Acquired user record does not match user name.");
 152                         return PAM_SERVICE_ERR;
 153                 }
 154         } else {
 155                 _cleanup_free_ char *formatted = NULL;
 156
 157                 /* Request the record ourselves */
 158                 r = userdb_by_name(username, 0, &ur);
 159                 if (r < 0) {
 160                         pam_syslog(handle, LOG_ERR, "Failed to get user record: %s", strerror_safe(r));
 161                         return PAM_USER_UNKNOWN;
 162                 }
 163
 164                 r = json_variant_format(ur->json, 0, &formatted);
 165                 if (r < 0) {
 166                         pam_syslog(handle, LOG_ERR, "Failed to format user JSON: %s", strerror_safe(r));
 167                         return PAM_SERVICE_ERR;
 168                 }
 169
 170                 /* And cache it for everyone else */
 171                 r = pam_set_data(handle, field, formatted, pam_cleanup_free);
 172                 if (r < 0) {
 173                         pam_syslog(handle, LOG_ERR, "Failed to set PAM user record data '%s': %s",
 174                                    field, pam_strerror(handle, r));
 175                         return r;
 176                 }
 177
 178                 TAKE_PTR(formatted);
 179         }
 180
 181         if (!uid_is_valid(ur->uid)) {
 182                 pam_syslog(handle, LOG_ERR, "Acquired user record does not have a UID.");
 183                 return PAM_SERVICE_ERR;
 184         }
 185
 186         if (ret_record)
 187                 *ret_record = TAKE_PTR(ur);
 188
 189         return PAM_SUCCESS;
 190 }
 191
 192 static bool display_is_local(const char *display) {
 193         assert(display);
 194
 195         return
 196                 display[0] == ':' &&
 197                 display[1] >= '0' &&
 198                 display[1] <= '9';
 199 }
 200
 201 static int socket_from_display(const char *display, char **path) {
 202         size_t k;
 203         char *f, *c;
 204
 205         assert(display);
 206         assert(path);
 207
 208         if (!display_is_local(display))
 209                 return -EINVAL;
 210
 211         k = strspn(display+1, "0123456789");
 212
 213         f = new(char, STRLEN("/tmp/.X11-unix/X") + k + 1);
 214         if (!f)
 215                 return -ENOMEM;
 216
 217         c = stpcpy(f, "/tmp/.X11-unix/X");
 218         memcpy(c, display+1, k);
 219         c[k] = 0;
 220
 221         *path = f;
 222
 223         return 0;
 224 }
 225
 226 static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
 227         union sockaddr_union sa;
 228         socklen_t sa_len;
 229         _cleanup_free_ char *p = NULL, *sys_path = NULL, *tty = NULL;
 230         _cleanup_close_ int fd = -1;
 231         struct ucred ucred;
 232         int v, r;
 233         dev_t display_ctty;
 234
 235         assert(display);
 236         assert(vtnr);
 237
 238         /* We deduce the X11 socket from the display name, then use
 239          * SO_PEERCRED to determine the X11 server process, ask for
 240          * the controlling tty of that and if it's a VC then we know
 241          * the seat and the virtual terminal. Sounds ugly, is only
 242          * semi-ugly. */
 243
 244         r = socket_from_display(display, &p);
 245         if (r < 0)
 246                 return r;
 247         r = sockaddr_un_set_path(&sa.un, p);
 248         if (r < 0)
 249                 return r;
 250         sa_len = r;
 251
 252         fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
 253         if (fd < 0)
 254                 return -errno;
 255
 256         if (connect(fd, &sa.sa, sa_len) < 0)
 257                 return -errno;
 258
 259         r = getpeercred(fd, &ucred);
 260         if (r < 0)
 261                 return r;
 262
 263         r = get_ctty_devnr(ucred.pid, &display_ctty);
 264         if (r < 0)
 265                 return r;
 266
 267         if (asprintf(&sys_path, "/sys/dev/char/%d:%d", major(display_ctty), minor(display_ctty)) < 0)
 268                 return -ENOMEM;
 269         r = readlink_value(sys_path, &tty);
 270         if (r < 0)
 271                 return r;
 272
 273         v = vtnr_from_tty(tty);
 274         if (v < 0)
 275                 return v;
 276         else if (v == 0)
 277                 return -ENOENT;
 278
 279         if (seat)
 280                 *seat = "seat0";
 281         *vtnr = (uint32_t) v;
 282
 283         return 0;
 284 }
 285
 286 static int export_legacy_dbus_address(
 287                 pam_handle_t *handle,
 288                 const char *runtime) {
 289
 290         const char *s;
 291         _cleanup_free_ char *t = NULL;
 292         int r = PAM_BUF_ERR;
 293
 294         /* We need to export $DBUS_SESSION_BUS_ADDRESS because various applications will not connect
 295          * correctly to the bus without it. This setting matches what dbus.socket does for the user
 296          * session using 'systemctl --user set-environment'. We want to have the same configuration
 297          * in processes started from the PAM session.
 298          *
 299          * The setting of the address is guarded by the access() check because it is also possible to compile
 300          * dbus without --enable-user-session, in which case this socket is not used, and
 301          * $DBUS_SESSION_BUS_ADDRESS should not be set. An alternative approach would to not do the access()
 302          * check here, and let applications try on their own, by using "unix:path=%s/bus;autolaunch:". But we
 303          * expect the socket to be present by the time we do this check, so we can just as well check once
 304          * here. */
 305
 306         s = strjoina(runtime, "/bus");
 307         if (access(s, F_OK) < 0)
 308                 return PAM_SUCCESS;
 309
 310         if (asprintf(&t, DEFAULT_USER_BUS_ADDRESS_FMT, runtime) < 0)
 311                 return pam_log_oom(handle);
 312
 313         r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", t, 0);
 314         if (r != PAM_SUCCESS) {
 315                 pam_syslog(handle, LOG_ERR, "Failed to set bus variable: %s", pam_strerror(handle, r));
 316                 return r;
 317         }
 318
 319         return PAM_SUCCESS;
 320 }
 321
 322 static int append_session_memory_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 323         uint64_t val;
 324         int r;
 325
 326         if (isempty(limit))
 327                 return PAM_SUCCESS;
 328
 329         if (streq(limit, "infinity")) {
 330                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", (uint64_t)-1);
 331                 if (r < 0)
 332                         return pam_bus_log_create_error(handle, r);
 333
 334                 return PAM_SUCCESS;
 335         }
 336
 337         r = parse_permille(limit);
 338         if (r >= 0) {
 339                 r = sd_bus_message_append(m, "(sv)", "MemoryMaxScale", "u", (uint32_t) (((uint64_t) r * UINT32_MAX) / 1000U));
 340                 if (r < 0)
 341                         return pam_bus_log_create_error(handle, r);
 342
 343                 return PAM_SUCCESS;
 344         }
 345
 346         r = parse_size(limit, 1024, &val);
 347         if (r >= 0) {
 348                 r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", val);
 349                 if (r < 0)
 350                         return pam_bus_log_create_error(handle, r);
 351
 352                 return PAM_SUCCESS;
 353         }
 354
 355         pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.memory_max, ignoring: %s", limit);
 356         return PAM_SUCCESS;
 357 }
 358
 359 static int append_session_runtime_max_sec(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 360         usec_t val;
 361         int r;
 362
 363         /* No need to parse "infinity" here, it will be set by default later in scope_init() */
 364         if (isempty(limit) || streq(limit, "infinity"))
 365                 return PAM_SUCCESS;
 366
 367         r = parse_sec(limit, &val);
 368         if (r >= 0) {
 369                 r = sd_bus_message_append(m, "(sv)", "RuntimeMaxUSec", "t", (uint64_t) val);
 370                 if (r < 0)
 371                         return pam_bus_log_create_error(handle, r);
 372         } else
 373                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.runtime_max_sec: %s, ignoring.", limit);
 374
 375         return PAM_SUCCESS;
 376 }
 377
 378 static int append_session_tasks_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
 379         uint64_t val;
 380         int r;
 381
 382         /* No need to parse "infinity" here, it will be set unconditionally later in manager_start_scope() */
 383         if (isempty(limit) || streq(limit, "infinity"))
 384                 return PAM_SUCCESS;
 385
 386         r = safe_atou64(limit, &val);
 387         if (r >= 0) {
 388                 r = sd_bus_message_append(m, "(sv)", "TasksMax", "t", val);
 389                 if (r < 0)
 390                         return pam_bus_log_create_error(handle, r);
 391         } else
 392                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.tasks_max, ignoring: %s", limit);
 393
 394         return PAM_SUCCESS;
 395 }
 396
 397 static int append_session_cg_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit, const char *field) {
 398         uint64_t val;
 399         int r;
 400
 401         if (isempty(limit))
 402                 return PAM_SUCCESS;
 403
 404         r = cg_weight_parse(limit, &val);
 405         if (r >= 0) {
 406                 r = sd_bus_message_append(m, "(sv)", field, "t", val);
 407                 if (r < 0)
 408                         return pam_bus_log_create_error(handle, r);
 409         } else if (streq(field, "CPUWeight"))
 410                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.cpu_weight, ignoring: %s", limit);
 411         else
 412                 pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.io_weight, ignoring: %s", limit);
 413
 414         return PAM_SUCCESS;
 415 }
 416
 417 static const char* getenv_harder(pam_handle_t *handle, const char *key, const char *fallback) {
 418         const char *v;
 419
 420         assert(handle);
 421         assert(key);
 422
 423         /* Looks for an environment variable, preferably in the environment block associated with the
 424          * specified PAM handle, falling back to the process' block instead. Why check both? Because we want
 425          * to permit configuration of session properties from unit files that invoke PAM services, so that
 426          * PAM services don't have to be reworked to set systemd-specific properties, but these properties
 427          * can still be set from the unit file Environment= block. */
 428
 429         v = pam_getenv(handle, key);
 430         if (!isempty(v))
 431                 return v;
 432
 433         /* We use secure_getenv() here, since we might get loaded into su/sudo, which are SUID. Ideally
 434          * they'd clean up the environment before invoking foreign code (such as PAM modules), but alas they
 435          * currently don't (to be precise, they clean up the environment they pass to their children, but
 436          * not their own environ[]). */
 437         v = secure_getenv(key);
 438         if (!isempty(v))
 439                 return v;
 440
 441         return fallback;
 442 }
 443
 444 static int update_environment(pam_handle_t *handle, const char *key, const char *value) {
 445         int r;
 446
 447         assert(handle);
 448         assert(key);
 449
 450         /* Updates the environment, but only if there's actually a value set. Also, log about errors */
 451
 452         if (isempty(value))
 453                 return PAM_SUCCESS;
 454
 455         r = pam_misc_setenv(handle, key, value, 0);
 456         if (r != PAM_SUCCESS)
 457                 pam_syslog(handle, LOG_ERR, "Failed to set environment variable %s: %s", key, pam_strerror(handle, r));
 458
 459         return r;
 460 }
 461
 462 static bool validate_runtime_directory(pam_handle_t *handle, const char *path, uid_t uid) {
 463         struct stat st;
 464
 465         assert(handle);
 466         assert(path);
 467
 468         /* Some extra paranoia: let's not set $XDG_RUNTIME_DIR if the directory we'd set it to isn't actually
 469          * set up properly for us. This is supposed to provide a careful safety net for supporting su/sudo
 470          * type transitions: in that case the UID changes, but the session and thus the user owning it
 471          * doesn't change. Since the $XDG_RUNTIME_DIR life-cycle is bound to the session's user being logged
 472          * in at least once we should be particularly careful when setting the environment variable, since
 473          * otherwise we might end up setting $XDG_RUNTIME_DIR to some directory owned by the wrong user. */
 474
 475         if (!path_is_absolute(path)) {
 476                 pam_syslog(handle, LOG_ERR, "Provided runtime directory '%s' is not absolute.", path);
 477                 goto fail;
 478         }
 479
 480         if (lstat(path, &st) < 0) {
 481                 pam_syslog(handle, LOG_ERR, "Failed to stat() runtime directory '%s': %s", path, strerror_safe(errno));
 482                 goto fail;
 483         }
 484
 485         if (!S_ISDIR(st.st_mode)) {
 486                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not actually a directory.", path);
 487                 goto fail;
 488         }
 489
 490         if (st.st_uid != uid) {
 491                 pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not owned by UID " UID_FMT ", as it should.", path, uid);
 492                 goto fail;
 493         }
 494
 495         return true;
 496
 497 fail:
 498         pam_syslog(handle, LOG_WARNING, "Not setting $XDG_RUNTIME_DIR, as the directory is not in order.");
 499         return false;
 500 }
 501
 502 static int pam_putenv_and_log(pam_handle_t *handle, const char *e, bool debug) {
 503         int r;
 504
 505         assert(handle);
 506         assert(e);
 507
 508         r = pam_putenv(handle, e);
 509         if (r != PAM_SUCCESS) {
 510                 pam_syslog(handle, LOG_ERR, "Failed to set PAM environment variable %s: %s", e, pam_strerror(handle, r));
 511                 return r;
 512         }
 513
 514         if (debug)
 515                 pam_syslog(handle, LOG_DEBUG, "PAM environment variable %s set based on user record.", e);
 516
 517         return PAM_SUCCESS;
 518 }
 519
 520 static int apply_user_record_settings(pam_handle_t *handle, UserRecord *ur, bool debug) {
 521         char **i;
 522         int r;
 523
 524         assert(handle);
 525         assert(ur);
 526
 527         if (ur->umask != MODE_INVALID) {
 528                 umask(ur->umask);
 529
 530                 if (debug)
 531                         pam_syslog(handle, LOG_DEBUG, "Set user umask to %04o based on user record.", ur->umask);
 532         }
 533
 534         STRV_FOREACH(i, ur->environment) {
 535                 _cleanup_free_ char *n = NULL;
 536                 const char *e;
 537
 538                 assert_se(e = strchr(*i, '=')); /* environment was already validated while parsing JSON record, this thus must hold */
 539
 540                 n = strndup(*i, e - *i);
 541                 if (!n)
 542                         return pam_log_oom(handle);
 543
 544                 if (pam_getenv(handle, n)) {
 545                         if (debug)
 546                                 pam_syslog(handle, LOG_DEBUG, "PAM environment variable $%s already set, not changing based on record.", *i);
 547                         continue;
 548                 }
 549
 550                 r = pam_putenv_and_log(handle, *i, debug);
 551                 if (r != PAM_SUCCESS)
 552                         return r;
 553         }
 554
 555         if (ur->email_address) {
 556                 if (pam_getenv(handle, "EMAIL")) {
 557                         if (debug)
 558                                 pam_syslog(handle, LOG_DEBUG, "PAM environment variable $EMAIL already set, not changing based on user record.");
 559                 } else {
 560                         _cleanup_free_ char *joined = NULL;
 561
 562                         joined = strjoin("EMAIL=", ur->email_address);
 563                         if (!joined)
 564                                 return pam_log_oom(handle);
 565
 566                         r = pam_putenv_and_log(handle, joined, debug);
 567                         if (r != PAM_SUCCESS)
 568                                 return r;
 569                 }
 570         }
 571
 572         if (ur->time_zone) {
 573                 if (pam_getenv(handle, "TZ")) {
 574                         if (debug)
 575                                 pam_syslog(handle, LOG_DEBUG, "PAM environment variable $TZ already set, not changing based on user record.");
 576                 } else if (!timezone_is_valid(ur->time_zone, LOG_DEBUG)) {
 577                         if (debug)
 578                                 pam_syslog(handle, LOG_DEBUG, "Time zone specified in user record is not valid locally, not setting $TZ.");
 579                 } else {
 580                         _cleanup_free_ char *joined = NULL;
 581
 582                         joined = strjoin("TZ=:", ur->time_zone);
 583                         if (!joined)
 584                                 return pam_log_oom(handle);
 585
 586                         r = pam_putenv_and_log(handle, joined, debug);
 587                         if (r != PAM_SUCCESS)
 588                                 return r;
 589                 }
 590         }
 591
 592         if (ur->preferred_language) {
 593                 if (pam_getenv(handle, "LANG")) {
 594                         if (debug)
 595                                 pam_syslog(handle, LOG_DEBUG, "PAM environment variable $LANG already set, not changing based on user record.");
 596                 } else if (locale_is_installed(ur->preferred_language) <= 0) {
 597                         if (debug)
 598                                 pam_syslog(handle, LOG_DEBUG, "Preferred language specified in user record is not valid or not installed, not setting $LANG.");
 599                 } else {
 600                         _cleanup_free_ char *joined = NULL;
 601
 602                         joined = strjoin("LANG=", ur->preferred_language);
 603                         if (!joined)
 604                                 return pam_log_oom(handle);
 605
 606                         r = pam_putenv_and_log(handle, joined, debug);
 607                         if (r != PAM_SUCCESS)
 608                                 return r;
 609                 }
 610         }
 611
 612         if (nice_is_valid(ur->nice_level)) {
 613                 if (nice(ur->nice_level) < 0)
 614                         pam_syslog(handle, LOG_ERR, "Failed to set nice level to %i, ignoring: %s", ur->nice_level, strerror_safe(errno));
 615                 else if (debug)
 616                         pam_syslog(handle, LOG_DEBUG, "Nice level set, based on user record.");
 617         }
 618
 619         for (int rl = 0; rl < _RLIMIT_MAX; rl++) {
 620
 621                 if (!ur->rlimits[rl])
 622                         continue;
 623
 624                 r = setrlimit_closest(rl, ur->rlimits[rl]);
 625                 if (r < 0)
 626                         pam_syslog(handle, LOG_ERR, "Failed to set resource limit %s, ignoring: %s", rlimit_to_string(rl), strerror_safe(r));
 627                 else if (debug)
 628                         pam_syslog(handle, LOG_DEBUG, "Resource limit %s set, based on user record.", rlimit_to_string(rl));
 629         }
 630
 631         return PAM_SUCCESS;
 632 }
 633
 634 static int configure_runtime_directory(
 635                 pam_handle_t *handle,
 636                 UserRecord *ur,
 637                 const char *rt) {
 638
 639         int r;
 640
 641         assert(handle);
 642         assert(ur);
 643         assert(rt);
 644
 645         if (!validate_runtime_directory(handle, rt, ur->uid))
 646                 return PAM_SUCCESS;
 647
 648         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
 649         if (r != PAM_SUCCESS) {
 650                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir: %s", pam_strerror(handle, r));
 651                 return r;
 652         }
 653
 654         return export_legacy_dbus_address(handle, rt);
 655 }
 656
 657 _public_ PAM_EXTERN int pam_sm_open_session(
 658                 pam_handle_t *handle,
 659                 int flags,
 660                 int argc, const char **argv) {
 661
 662         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 663         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL, *reply = NULL;
 664         const char
 665                 *id, *object_path, *runtime_path,
 666                 *service = NULL,
 667                 *tty = NULL, *display = NULL,
 668                 *remote_user = NULL, *remote_host = NULL,
 669                 *seat = NULL,
 670                 *type = NULL, *class = NULL,
 671                 *class_pam = NULL, *type_pam = NULL, *cvtnr = NULL, *desktop = NULL, *desktop_pam = NULL,
 672                 *memory_max = NULL, *tasks_max = NULL, *cpu_weight = NULL, *io_weight = NULL, *runtime_max_sec = NULL;
 673         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 674         _cleanup_(user_record_unrefp) UserRecord *ur = NULL;
 675         int session_fd = -1, existing, r;
 676         bool debug = false, remote;
 677         uint32_t vtnr = 0;
 678         uid_t original_uid;
 679
 680         assert(handle);
 681
 682         if (parse_argv(handle,
 683                        argc, argv,
 684                        &class_pam,
 685                        &type_pam,
 686                        &desktop_pam,
 687                        &debug) < 0)
 688                 return PAM_SESSION_ERR;
 689
 690         if (debug)
 691                 pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing");
 692
 693         r = acquire_user_record(handle, &ur);
 694         if (r != PAM_SUCCESS)
 695                 return r;
 696
 697         /* Make most of this a NOP on non-logind systems */
 698         if (!logind_running())
 699                 goto success;
 700
 701         /* Make sure we don't enter a loop by talking to
 702          * systemd-logind when it is actually waiting for the
 703          * background to finish start-up. If the service is
 704          * "systemd-user" we simply set XDG_RUNTIME_DIR and
 705          * leave. */
 706
 707         (void) pam_get_item(handle, PAM_SERVICE, (const void**) &service);
 708         if (streq_ptr(service, "systemd-user")) {
 709                 char rt[STRLEN("/run/user/") + DECIMAL_STR_MAX(uid_t)];
 710
 711                 xsprintf(rt, "/run/user/"UID_FMT, ur->uid);
 712                 r = configure_runtime_directory(handle, ur, rt);
 713                 if (r != PAM_SUCCESS)
 714                         return r;
 715
 716                 goto success;
 717         }
 718
 719         /* Otherwise, we ask logind to create a session for us */
 720
 721         (void) pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
 722         (void) pam_get_item(handle, PAM_TTY, (const void**) &tty);
 723         (void) pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
 724         (void) pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
 725
 726         seat = getenv_harder(handle, "XDG_SEAT", NULL);
 727         cvtnr = getenv_harder(handle, "XDG_VTNR", NULL);
 728         type = getenv_harder(handle, "XDG_SESSION_TYPE", type_pam);
 729         class = getenv_harder(handle, "XDG_SESSION_CLASS", class_pam);
 730         desktop = getenv_harder(handle, "XDG_SESSION_DESKTOP", desktop_pam);
 731
 732         tty = strempty(tty);
 733
 734         if (strchr(tty, ':')) {
 735                 /* A tty with a colon is usually an X11 display, placed there to show up in utmp. We rearrange things
 736                  * and don't pretend that an X display was a tty. */
 737                 if (isempty(display))
 738                         display = tty;
 739                 tty = NULL;
 740
 741         } else if (streq(tty, "cron")) {
 742                 /* cron is setting PAM_TTY to "cron" for some reason (the commit carries no information why, but
 743                  * probably because it wants to set it to something as pam_time/pam_access/… require PAM_TTY to be set
 744                  * (as they otherwise even try to update it!) — but cron doesn't actually allocate a TTY for its forked
 745                  * off processes.) */
 746                 type = "unspecified";
 747                 class = "background";
 748                 tty = NULL;
 749
 750         } else if (streq(tty, "ssh")) {
 751                 /* ssh has been setting PAM_TTY to "ssh" (for the same reason as cron does this, see above. For further
 752                  * details look for "PAM_TTY_KLUDGE" in the openssh sources). */
 753                 type ="tty";
 754                 class = "user";
 755                 tty = NULL; /* This one is particularly sad, as this means that ssh sessions — even though usually
 756                              * associated with a pty — won't be tracked by their tty in logind. This is because ssh
 757                              * does the PAM session registration early for new connections, and registers a pty only
 758                              * much later (this is because it doesn't know yet if it needs one at all, as whether to
 759                              * register a pty or not is negotiated much later in the protocol). */
 760
 761         } else
 762                 /* Chop off leading /dev prefix that some clients specify, but others do not. */
 763                 tty = skip_dev_prefix(tty);
 764
 765         /* If this fails vtnr will be 0, that's intended */
 766         if (!isempty(cvtnr))
 767                 (void) safe_atou32(cvtnr, &vtnr);
 768
 769         if (!isempty(display) && !vtnr) {
 770                 if (isempty(seat))
 771                         (void) get_seat_from_display(display, &seat, &vtnr);
 772                 else if (streq(seat, "seat0"))
 773                         (void) get_seat_from_display(display, NULL, &vtnr);
 774         }
 775
 776         if (seat && !streq(seat, "seat0") && vtnr != 0) {
 777                 if (debug)
 778                         pam_syslog(handle, LOG_DEBUG, "Ignoring vtnr %"PRIu32" for %s which is not seat0", vtnr, seat);
 779                 vtnr = 0;
 780         }
 781
 782         if (isempty(type))
 783                 type = !isempty(display) ? "x11" :
 784                            !isempty(tty) ? "tty" : "unspecified";
 785
 786         if (isempty(class))
 787                 class = streq(type, "unspecified") ? "background" : "user";
 788
 789         remote = !isempty(remote_host) && !is_localhost(remote_host);
 790
 791         (void) pam_get_data(handle, "systemd.memory_max", (const void **)&memory_max);
 792         (void) pam_get_data(handle, "systemd.tasks_max",  (const void **)&tasks_max);
 793         (void) pam_get_data(handle, "systemd.cpu_weight", (const void **)&cpu_weight);
 794         (void) pam_get_data(handle, "systemd.io_weight",  (const void **)&io_weight);
 795         (void) pam_get_data(handle, "systemd.runtime_max_sec", (const void **)&runtime_max_sec);
 796
 797         /* Talk to logind over the message bus */
 798
 799         r = pam_acquire_bus_connection(handle, &bus);
 800         if (r != PAM_SUCCESS)
 801                 return r;
 802
 803         if (debug) {
 804                 pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: "
 805                            "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",
 806                            ur->uid, getpid_cached(),
 807                            strempty(service),
 808                            type, class, strempty(desktop),
 809                            strempty(seat), vtnr, strempty(tty), strempty(display),
 810                            yes_no(remote), strempty(remote_user), strempty(remote_host));
 811                 pam_syslog(handle, LOG_DEBUG, "Session limits: "
 812                            "memory_max=%s tasks_max=%s cpu_weight=%s io_weight=%s runtime_max_sec=%s",
 813                            strna(memory_max), strna(tasks_max), strna(cpu_weight), strna(io_weight), strna(runtime_max_sec));
 814         }
 815
 816         r = bus_message_new_method_call(bus, &m, bus_login_mgr, "CreateSession");
 817         if (r < 0)
 818                 return pam_bus_log_create_error(handle, r);
 819
 820         r = sd_bus_message_append(m, "uusssssussbss",
 821                         (uint32_t) ur->uid,
 822                         0,
 823                         service,
 824                         type,
 825                         class,
 826                         desktop,
 827                         seat,
 828                         vtnr,
 829                         tty,
 830                         display,
 831                         remote,
 832                         remote_user,
 833                         remote_host);
 834         if (r < 0)
 835                 return pam_bus_log_create_error(handle, r);
 836
 837         r = sd_bus_message_open_container(m, 'a', "(sv)");
 838         if (r < 0)
 839                 return pam_bus_log_create_error(handle, r);
 840
 841         r = append_session_memory_max(handle, m, memory_max);
 842         if (r != PAM_SUCCESS)
 843                 return r;
 844
 845         r = append_session_runtime_max_sec(handle, m, runtime_max_sec);
 846         if (r != PAM_SUCCESS)
 847                 return r;
 848
 849         r = append_session_tasks_max(handle, m, tasks_max);
 850         if (r != PAM_SUCCESS)
 851                 return r;
 852
 853         r = append_session_cg_weight(handle, m, cpu_weight, "CPUWeight");
 854         if (r != PAM_SUCCESS)
 855                 return r;
 856
 857         r = append_session_cg_weight(handle, m, io_weight, "IOWeight");
 858         if (r != PAM_SUCCESS)
 859                 return r;
 860
 861         r = sd_bus_message_close_container(m);
 862         if (r < 0)
 863                 return pam_bus_log_create_error(handle, r);
 864
 865         r = sd_bus_call(bus, m, LOGIN_SLOW_BUS_CALL_TIMEOUT_USEC, &error, &reply);
 866         if (r < 0) {
 867                 if (sd_bus_error_has_name(&error, BUS_ERROR_SESSION_BUSY)) {
 868                         if (debug)
 869                                 pam_syslog(handle, LOG_DEBUG, "Not creating session: %s", bus_error_message(&error, r));
 870
 871                         /* We are already in a session, don't do anything */
 872                         goto success;
 873                 } else {
 874                         pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r));
 875                         return PAM_SESSION_ERR;
 876                 }
 877         }
 878
 879         r = sd_bus_message_read(reply,
 880                                 "soshusub",
 881                                 &id,
 882                                 &object_path,
 883                                 &runtime_path,
 884                                 &session_fd,
 885                                 &original_uid,
 886                                 &seat,
 887                                 &vtnr,
 888                                 &existing);
 889         if (r < 0)
 890                 return pam_bus_log_parse_error(handle, r);
 891
 892         if (debug)
 893                 pam_syslog(handle, LOG_DEBUG, "Reply from logind: "
 894                            "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u original_uid=%u",
 895                            id, object_path, runtime_path, session_fd, seat, vtnr, original_uid);
 896
 897         r = update_environment(handle, "XDG_SESSION_ID", id);
 898         if (r != PAM_SUCCESS)
 899                 return r;
 900
 901         if (original_uid == ur->uid) {
 902                 /* Don't set $XDG_RUNTIME_DIR if the user we now authenticated for does not match the
 903                  * original user of the session. We do this in order not to result in privileged apps
 904                  * clobbering the runtime directory unnecessarily. */
 905
 906                 r = configure_runtime_directory(handle, ur, runtime_path);
 907                 if (r != PAM_SUCCESS)
 908                         return r;
 909         }
 910
 911         /* Most likely we got the session/type/class from environment variables, but might have gotten the data
 912          * somewhere else (for example PAM module parameters). Let's now update the environment variables, so that this
 913          * data is inherited into the session processes, and programs can rely on them to be initialized. */
 914
 915         r = update_environment(handle, "XDG_SESSION_TYPE", type);
 916         if (r != PAM_SUCCESS)
 917                 return r;
 918
 919         r = update_environment(handle, "XDG_SESSION_CLASS", class);
 920         if (r != PAM_SUCCESS)
 921                 return r;
 922
 923         r = update_environment(handle, "XDG_SESSION_DESKTOP", desktop);
 924         if (r != PAM_SUCCESS)
 925                 return r;
 926
 927         r = update_environment(handle, "XDG_SEAT", seat);
 928         if (r != PAM_SUCCESS)
 929                 return r;
 930
 931         if (vtnr > 0) {
 932                 char buf[DECIMAL_STR_MAX(vtnr)];
 933                 sprintf(buf, "%u", vtnr);
 934
 935                 r = update_environment(handle, "XDG_VTNR", buf);
 936                 if (r != PAM_SUCCESS)
 937                         return r;
 938         }
 939
 940         r = pam_set_data(handle, "systemd.existing", INT_TO_PTR(!!existing), NULL);
 941         if (r != PAM_SUCCESS) {
 942                 pam_syslog(handle, LOG_ERR, "Failed to install existing flag: %s", pam_strerror(handle, r));
 943                 return r;
 944         }
 945
 946         if (session_fd >= 0) {
 947                 session_fd = fcntl(session_fd, F_DUPFD_CLOEXEC, 3);
 948                 if (session_fd < 0) {
 949                         pam_syslog(handle, LOG_ERR, "Failed to dup session fd: %m");
 950                         return PAM_SESSION_ERR;
 951                 }
 952
 953                 r = pam_set_data(handle, "systemd.session-fd", FD_TO_PTR(session_fd), NULL);
 954                 if (r != PAM_SUCCESS) {
 955                         pam_syslog(handle, LOG_ERR, "Failed to install session fd: %s", pam_strerror(handle, r));
 956                         safe_close(session_fd);
 957                         return r;
 958                 }
 959         }
 960
 961 success:
 962         r = apply_user_record_settings(handle, ur, debug);
 963         if (r != PAM_SUCCESS)
 964                 return r;
 965
 966         /* Let's release the D-Bus connection, after all the session might live quite a long time, and we are
 967          * not going to use the bus connection in that time, so let's better close before the daemon kicks us
 968          * off because we are not processing anything. */
 969         (void) pam_release_bus_connection(handle);
 970         return PAM_SUCCESS;
 971 }
 972
 973 _public_ PAM_EXTERN int pam_sm_close_session(
 974                 pam_handle_t *handle,
 975                 int flags,
 976                 int argc, const char **argv) {
 977
 978         const void *existing = NULL;
 979         bool debug = false;
 980         const char *id;
 981         int r;
 982
 983         assert(handle);
 984
 985         if (parse_argv(handle,
 986                        argc, argv,
 987                        NULL,
 988                        NULL,
 989                        NULL,
 990                        &debug) < 0)
 991                 return PAM_SESSION_ERR;
 992
 993         if (debug)
 994                 pam_syslog(handle, LOG_DEBUG, "pam-systemd shutting down");
 995
 996         /* Only release session if it wasn't pre-existing when we
 997          * tried to create it */
 998         (void) pam_get_data(handle, "systemd.existing", &existing);
 999
1000         id = pam_getenv(handle, "XDG_SESSION_ID");
1001         if (id && !existing) {
1002                 _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
1003                 _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
1004
1005                 /* Before we go and close the FIFO we need to tell logind that this is a clean session
1006                  * shutdown, so that it doesn't just go and slaughter us immediately after closing the fd */
1007
1008                 r = pam_acquire_bus_connection(handle, &bus);
1009                 if (r != PAM_SUCCESS)
1010                         return r;
1011
1012                 r = bus_call_method(bus, bus_login_mgr, "ReleaseSession", &error, NULL, "s", id);
1013                 if (r < 0) {
1014                         pam_syslog(handle, LOG_ERR, "Failed to release session: %s", bus_error_message(&error, r));
1015                         return PAM_SESSION_ERR;
1016                 }
1017         }
1018
1019         /* Note that we are knowingly leaking the FIFO fd here. This way, logind can watch us die. If we
1020          * closed it here it would not have any clue when that is completed. Given that one cannot really
1021          * have multiple PAM sessions open from the same process this means we will leak one FD at max. */
1022
1023         return PAM_SUCCESS;
1024 }