src/pam-module.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <fcntl.h>
  24 #include <sys/file.h>
  25 #include <pwd.h>
  26 #include <endian.h>
  27 #include <sys/capability.h>
  28
  29 #include <security/pam_modules.h>
  30 #include <security/_pam_macros.h>
  31 #include <security/pam_modutil.h>
  32 #include <security/pam_ext.h>
  33 #include <security/pam_misc.h>
  34
  35 #include "util.h"
  36 #include "macro.h"
  37 #include "sd-daemon.h"
  38 #include "strv.h"
  39 #include "dbus-common.h"
  40 #include "def.h"
  41 #include "socket-util.h"
  42
  43 static int parse_argv(pam_handle_t *handle,
  44                       int argc, const char **argv,
  45                       char ***controllers,
  46                       char ***reset_controllers,
  47                       bool *kill_processes,
  48                       char ***kill_only_users,
  49                       char ***kill_exclude_users,
  50                       bool *debug) {
  51
  52         unsigned i;
  53         bool reset_controller_set = false;
  54         bool kill_exclude_users_set = false;
  55
  56         assert(argc >= 0);
  57         assert(argc == 0 || argv);
  58
  59         for (i = 0; i < (unsigned) argc; i++) {
  60                 int k;
  61
  62                 if (startswith(argv[i], "kill-processes=")) {
  63                         if ((k = parse_boolean(argv[i] + 15)) < 0) {
  64                                 pam_syslog(handle, LOG_ERR, "Failed to parse kill-processes= argument.");
  65                                 return k;
  66                         }
  67
  68                         if (kill_processes)
  69                                 *kill_processes = k;
  70
  71                 } else if (startswith(argv[i], "kill-session=")) {
  72                         /* As compatibility for old versions */
  73
  74                         if ((k = parse_boolean(argv[i] + 13)) < 0) {
  75                                 pam_syslog(handle, LOG_ERR, "Failed to parse kill-session= argument.");
  76                                 return k;
  77                         }
  78
  79                         if (kill_processes)
  80                                 *kill_processes = k;
  81
  82                 } else if (startswith(argv[i], "controllers=")) {
  83
  84                         if (controllers) {
  85                                 char **l;
  86
  87                                 if (!(l = strv_split(argv[i] + 12, ","))) {
  88                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
  89                                         return -ENOMEM;
  90                                 }
  91
  92                                 strv_free(*controllers);
  93                                 *controllers = l;
  94                         }
  95
  96                 } else if (startswith(argv[i], "reset-controllers=")) {
  97
  98                         if (reset_controllers) {
  99                                 char **l;
 100
 101                                 if (!(l = strv_split(argv[i] + 18, ","))) {
 102                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
 103                                         return -ENOMEM;
 104                                 }
 105
 106                                 strv_free(*reset_controllers);
 107                                 *reset_controllers = l;
 108                         }
 109
 110                         reset_controller_set = true;
 111
 112                 } else if (startswith(argv[i], "kill-only-users=")) {
 113
 114                         if (kill_only_users) {
 115                                 char **l;
 116
 117                                 if (!(l = strv_split(argv[i] + 16, ","))) {
 118                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
 119                                         return -ENOMEM;
 120                                 }
 121
 122                                 strv_free(*kill_only_users);
 123                                 *kill_only_users = l;
 124                         }
 125
 126                 } else if (startswith(argv[i], "kill-exclude-users=")) {
 127
 128                         if (kill_exclude_users) {
 129                                 char **l;
 130
 131                                 if (!(l = strv_split(argv[i] + 19, ","))) {
 132                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
 133                                         return -ENOMEM;
 134                                 }
 135
 136                                 strv_free(*kill_exclude_users);
 137                                 *kill_exclude_users = l;
 138                         }
 139
 140                         kill_exclude_users_set = true;
 141
 142                 } else if (startswith(argv[i], "debug=")) {
 143                         if ((k = parse_boolean(argv[i] + 6)) < 0) {
 144                                 pam_syslog(handle, LOG_ERR, "Failed to parse debug= argument.");
 145                                 return k;
 146                         }
 147
 148                         if (debug)
 149                                 *debug = k;
 150
 151                 } else if (startswith(argv[i], "create-session=") ||
 152                            startswith(argv[i], "kill-user=")) {
 153
 154                         pam_syslog(handle, LOG_WARNING, "Option %s not supported anymore, ignoring.", argv[i]);
 155
 156                 } else {
 157                         pam_syslog(handle, LOG_ERR, "Unknown parameter '%s'.", argv[i]);
 158                         return -EINVAL;
 159                 }
 160         }
 161
 162         if (!reset_controller_set && reset_controllers) {
 163                 char **l;
 164
 165                 if (!(l = strv_new("cpu", NULL))) {
 166                         pam_syslog(handle, LOG_ERR, "Out of memory");
 167                         return -ENOMEM;
 168                 }
 169
 170                 *reset_controllers = l;
 171         }
 172
 173         if (controllers)
 174                 strv_remove(*controllers, SYSTEMD_CGROUP_CONTROLLER);
 175
 176         if (reset_controllers)
 177                 strv_remove(*reset_controllers, SYSTEMD_CGROUP_CONTROLLER);
 178
 179         if (!kill_exclude_users_set && kill_exclude_users) {
 180                 char **l;
 181
 182                 if (!(l = strv_new("root", NULL))) {
 183                         pam_syslog(handle, LOG_ERR, "Out of memory");
 184                         return -ENOMEM;
 185                 }
 186
 187                 *kill_exclude_users = l;
 188         }
 189
 190         return 0;
 191 }
 192
 193 static int get_user_data(
 194                 pam_handle_t *handle,
 195                 const char **ret_username,
 196                 struct passwd **ret_pw) {
 197
 198         const char *username = NULL;
 199         struct passwd *pw = NULL;
 200         int r;
 201         bool have_loginuid = false;
 202         char *s;
 203
 204         assert(handle);
 205         assert(ret_username);
 206         assert(ret_pw);
 207
 208         if (have_effective_cap(CAP_AUDIT_CONTROL) > 0) {
 209                 /* Only use audit login uid if we are executed with
 210                  * sufficient capabilities so that pam_loginuid could
 211                  * do its job. If we are lacking the CAP_AUDIT_CONTROL
 212                  * capabality we most likely are being run in a
 213                  * container and /proc/self/loginuid is useless since
 214                  * it probably contains a uid of the host system. */
 215
 216                 if (read_one_line_file("/proc/self/loginuid", &s) >= 0) {
 217                         uint32_t u;
 218
 219                         r = safe_atou32(s, &u);
 220                         free(s);
 221
 222                         if (r >= 0 && u != (uint32_t) -1 && u > 0) {
 223                                 have_loginuid = true;
 224                                 pw = pam_modutil_getpwuid(handle, u);
 225                         }
 226                 }
 227         }
 228
 229         if (!have_loginuid) {
 230                 if ((r = pam_get_user(handle, &username, NULL)) != PAM_SUCCESS) {
 231                         pam_syslog(handle, LOG_ERR, "Failed to get user name.");
 232                         return r;
 233                 }
 234
 235                 if (!username || !*username) {
 236                         pam_syslog(handle, LOG_ERR, "User name not valid.");
 237                         return PAM_AUTH_ERR;
 238                 }
 239
 240                 pw = pam_modutil_getpwnam(handle, username);
 241         }
 242
 243         if (!pw) {
 244                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 245                 return PAM_USER_UNKNOWN;
 246         }
 247
 248         *ret_pw = pw;
 249         *ret_username = username ? username : pw->pw_name;
 250
 251         return PAM_SUCCESS;
 252 }
 253
 254 static bool check_user_lists(
 255                 pam_handle_t *handle,
 256                 uid_t uid,
 257                 char **kill_only_users,
 258                 char **kill_exclude_users) {
 259
 260         const char *name = NULL;
 261         char **l;
 262
 263         assert(handle);
 264
 265         if (uid == 0)
 266                 name = "root"; /* Avoid obvious NSS requests, to suppress network traffic */
 267         else {
 268                 struct passwd *pw;
 269
 270                 pw = pam_modutil_getpwuid(handle, uid);
 271                 if (pw)
 272                         name = pw->pw_name;
 273         }
 274
 275         STRV_FOREACH(l, kill_exclude_users) {
 276                 uint32_t id;
 277
 278                 if (safe_atou32(*l, &id) >= 0)
 279                         if ((uid_t) id == uid)
 280                                 return false;
 281
 282                 if (name && streq(name, *l))
 283                         return false;
 284         }
 285
 286         if (strv_isempty(kill_only_users))
 287                 return true;
 288
 289         STRV_FOREACH(l, kill_only_users) {
 290                 uint32_t id;
 291
 292                 if (safe_atou32(*l, &id) >= 0)
 293                         if ((uid_t) id == uid)
 294                                 return true;
 295
 296                 if (name && streq(name, *l))
 297                         return true;
 298         }
 299
 300         return false;
 301 }
 302
 303 static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
 304         char *p = NULL;
 305         int r;
 306         int fd;
 307         union sockaddr_union sa;
 308         struct ucred ucred;
 309         socklen_t l;
 310         char *tty;
 311         int v;
 312
 313         assert(display);
 314         assert(seat);
 315         assert(vtnr);
 316
 317         /* We deduce the X11 socket from the display name, then use
 318          * SO_PEERCRED to determine the X11 server process, ask for
 319          * the controlling tty of that and if it's a VC then we know
 320          * the seat and the virtual terminal. Sounds ugly, is only
 321          * semi-ugly. */
 322
 323         r = socket_from_display(display, &p);
 324         if (r < 0)
 325                 return r;
 326
 327         fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
 328         if (fd < 0) {
 329                 free(p);
 330                 return -errno;
 331         }
 332
 333         zero(sa);
 334         sa.un.sun_family = AF_UNIX;
 335         strncpy(sa.un.sun_path, p, sizeof(sa.un.sun_path)-1);
 336         free(p);
 337
 338         if (connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
 339                 close_nointr_nofail(fd);
 340                 return -errno;
 341         }
 342
 343         l = sizeof(ucred);
 344         r = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &ucred, &l);
 345         close_nointr_nofail(fd);
 346
 347         if (r < 0)
 348                 return -errno;
 349
 350         r = get_ctty(ucred.pid, NULL, &tty);
 351         if (r < 0)
 352                 return r;
 353
 354         v = vtnr_from_tty(tty);
 355         free(tty);
 356
 357         if (v < 0)
 358                 return v;
 359         else if (v == 0)
 360                 return -ENOENT;
 361
 362         *seat = "seat0";
 363         *vtnr = (uint32_t) v;
 364
 365         return 0;
 366 }
 367
 368 _public_ PAM_EXTERN int pam_sm_open_session(
 369                 pam_handle_t *handle,
 370                 int flags,
 371                 int argc, const char **argv) {
 372
 373         struct passwd *pw;
 374         bool kill_processes = false, debug = false;
 375         const char *username, *id, *object_path, *runtime_path, *service = NULL, *tty = NULL, *display = NULL, *remote_user = NULL, *remote_host = NULL, *seat = NULL, *type, *cvtnr = NULL;
 376         char **controllers = NULL, **reset_controllers = NULL, **kill_only_users = NULL, **kill_exclude_users = NULL;
 377         DBusError error;
 378         uint32_t uid, pid;
 379         DBusMessageIter iter;
 380         dbus_bool_t kp;
 381         int session_fd = -1;
 382         DBusConnection *bus = NULL;
 383         DBusMessage *m = NULL, *reply = NULL;
 384         dbus_bool_t remote;
 385         int r;
 386         uint32_t vtnr = 0;
 387
 388         assert(handle);
 389
 390         dbus_error_init(&error);
 391
 392         /* pam_syslog(handle, LOG_INFO, "pam-systemd initializing"); */
 393
 394         /* Make this a NOP on non-systemd systems */
 395         if (sd_booted() <= 0)
 396                 return PAM_SUCCESS;
 397
 398         if (parse_argv(handle,
 399                        argc, argv,
 400                        &controllers, &reset_controllers,
 401                        &kill_processes, &kill_only_users, &kill_exclude_users,
 402                        &debug) < 0) {
 403                 r = PAM_SESSION_ERR;
 404                 goto finish;
 405         }
 406
 407         r = get_user_data(handle, &username, &pw);
 408         if (r != PAM_SUCCESS)
 409                 goto finish;
 410
 411         if (kill_processes)
 412                 kill_processes = check_user_lists(handle, pw->pw_uid, kill_only_users, kill_exclude_users);
 413
 414         dbus_connection_set_change_sigpipe(FALSE);
 415
 416         bus = dbus_bus_get_private(DBUS_BUS_SYSTEM, &error);
 417         if (!bus) {
 418                 pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", bus_error_message(&error));
 419                 r = PAM_SESSION_ERR;
 420                 goto finish;
 421         }
 422
 423         m = dbus_message_new_method_call(
 424                         "org.freedesktop.login1",
 425                         "/org/freedesktop/login1",
 426                         "org.freedesktop.login1.Manager",
 427                         "CreateSession");
 428
 429         if (!m) {
 430                 pam_syslog(handle, LOG_ERR, "Could not allocate create session message.");
 431                 r = PAM_BUF_ERR;
 432                 goto finish;
 433         }
 434
 435         uid = pw->pw_uid;
 436         pid = getpid();
 437
 438         pam_get_item(handle, PAM_SERVICE, (const void**) &service);
 439         pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
 440         pam_get_item(handle, PAM_TTY, (const void**) &tty);
 441         pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
 442         pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
 443         seat = pam_getenv(handle, "LOGIN_SEAT");
 444         cvtnr = pam_getenv(handle, "LOGIN_VTNR");
 445
 446         service = strempty(service);
 447         tty = strempty(tty);
 448         display = strempty(display);
 449         remote_user = strempty(remote_user);
 450         remote_host = strempty(remote_host);
 451         seat = strempty(seat);
 452
 453         if (strchr(tty, ':')) {
 454                 /* A tty with a colon is usually an X11 display, place
 455                  * there to show up in utmp. We rearrange things and
 456                  * don't pretend that an X display was a tty */
 457
 458                 if (isempty(display))
 459                         display = tty;
 460                 tty = "";
 461         }
 462
 463         if (!isempty(cvtnr))
 464                 safe_atou32(cvtnr, &vtnr);
 465
 466         if (!isempty(display) && isempty(seat) && vtnr <= 0)
 467                 get_seat_from_display(display, &seat, &vtnr);
 468
 469         type = !isempty(display) ? "x11" :
 470                    !isempty(tty) ? "tty" : "other";
 471
 472         remote = !isempty(remote_host) && !streq(remote_host, "localhost") && !streq(remote_host, "localhost.localdomain");
 473
 474         if (!dbus_message_append_args(m,
 475                                       DBUS_TYPE_UINT32, &uid,
 476                                       DBUS_TYPE_UINT32, &pid,
 477                                       DBUS_TYPE_STRING, &service,
 478                                       DBUS_TYPE_STRING, &type,
 479                                       DBUS_TYPE_STRING, &seat,
 480                                       DBUS_TYPE_UINT32, &vtnr,
 481                                       DBUS_TYPE_STRING, &tty,
 482                                       DBUS_TYPE_STRING, &display,
 483                                       DBUS_TYPE_BOOLEAN, &remote,
 484                                       DBUS_TYPE_STRING, &remote_user,
 485                                       DBUS_TYPE_STRING, &remote_host,
 486                                       DBUS_TYPE_INVALID)) {
 487                 pam_syslog(handle, LOG_ERR, "Could not attach parameters to message.");
 488                 r = PAM_BUF_ERR;
 489                 goto finish;
 490         }
 491
 492         dbus_message_iter_init_append(m, &iter);
 493
 494         r = bus_append_strv_iter(&iter, controllers);
 495         if (r < 0) {
 496                 pam_syslog(handle, LOG_ERR, "Could not attach parameter to message.");
 497                 r = PAM_BUF_ERR;
 498                 goto finish;
 499         }
 500
 501         r = bus_append_strv_iter(&iter, reset_controllers);
 502         if (r < 0) {
 503                 pam_syslog(handle, LOG_ERR, "Could not attach parameter to message.");
 504                 r = PAM_BUF_ERR;
 505                 goto finish;
 506         }
 507
 508         kp = kill_processes;
 509         if (!dbus_message_iter_append_basic(&iter, DBUS_TYPE_BOOLEAN, &kp)) {
 510                 pam_syslog(handle, LOG_ERR, "Could not attach parameter to message.");
 511                 r = PAM_BUF_ERR;
 512                 goto finish;
 513         }
 514
 515         reply = dbus_connection_send_with_reply_and_block(bus, m, -1, &error);
 516         if (!reply) {
 517                 pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error));
 518                 r = PAM_SESSION_ERR;
 519                 goto finish;
 520         }
 521
 522         if (!dbus_message_get_args(reply, &error,
 523                                    DBUS_TYPE_STRING, &id,
 524                                    DBUS_TYPE_OBJECT_PATH, &object_path,
 525                                    DBUS_TYPE_STRING, &runtime_path,
 526                                    DBUS_TYPE_UNIX_FD, &session_fd,
 527                                    DBUS_TYPE_INVALID)) {
 528                 pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", bus_error_message(&error));
 529                 r = PAM_SESSION_ERR;
 530                 goto finish;
 531         }
 532
 533         r = pam_misc_setenv(handle, "XDG_SESSION_ID", id, 0);
 534         if (r != PAM_SUCCESS) {
 535                 pam_syslog(handle, LOG_ERR, "Failed to set session id.");
 536                 goto finish;
 537         }
 538
 539         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", runtime_path, 0);
 540         if (r != PAM_SUCCESS) {
 541                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 542                 goto finish;
 543         }
 544
 545         if (session_fd >= 0) {
 546                 r = pam_set_data(handle, "systemd.session-fd", INT_TO_PTR(session_fd+1), NULL);
 547                 if (r != PAM_SUCCESS) {
 548                         pam_syslog(handle, LOG_ERR, "Failed to install session fd.");
 549                         return r;
 550                 }
 551         }
 552
 553         session_fd = -1;
 554
 555         r = PAM_SUCCESS;
 556
 557 finish:
 558         strv_free(controllers);
 559         strv_free(reset_controllers);
 560         strv_free(kill_only_users);
 561         strv_free(kill_exclude_users);
 562
 563         dbus_error_free(&error);
 564
 565         if (bus) {
 566                 dbus_connection_close(bus);
 567                 dbus_connection_unref(bus);
 568         }
 569
 570         if (m)
 571                 dbus_message_unref(m);
 572
 573         if (reply)
 574                 dbus_message_unref(reply);
 575
 576         if (session_fd >= 0)
 577                 close_nointr_nofail(session_fd);
 578
 579         return r;
 580 }
 581
 582 _public_ PAM_EXTERN int pam_sm_close_session(
 583                 pam_handle_t *handle,
 584                 int flags,
 585                 int argc, const char **argv) {
 586
 587         const void *p = NULL;
 588
 589         pam_get_data(handle, "systemd.session-fd", &p);
 590
 591         if (p)
 592                 close_nointr(PTR_TO_INT(p) - 1);
 593
 594         return PAM_SUCCESS;
 595 }