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
  54         assert(argc >= 0);
  55         assert(argc == 0 || argv);
  56
  57         for (i = 0; i < (unsigned) argc; i++) {
  58                 int k;
  59
  60                 if (startswith(argv[i], "kill-session-processes=")) {
  61                         if ((k = parse_boolean(argv[i] + 23)) < 0) {
  62                                 pam_syslog(handle, LOG_ERR, "Failed to parse kill-session-processes= argument.");
  63                                 return k;
  64                         }
  65
  66                         if (kill_processes)
  67                                 *kill_processes = k;
  68
  69                 } else if (startswith(argv[i], "kill-session=")) {
  70                         /* As compatibility for old versions */
  71
  72                         if ((k = parse_boolean(argv[i] + 13)) < 0) {
  73                                 pam_syslog(handle, LOG_ERR, "Failed to parse kill-session= argument.");
  74                                 return k;
  75                         }
  76
  77                         if (kill_processes)
  78                                 *kill_processes = k;
  79
  80                 } else if (startswith(argv[i], "controllers=")) {
  81
  82                         if (controllers) {
  83                                 char **l;
  84
  85                                 if (!(l = strv_split(argv[i] + 12, ","))) {
  86                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
  87                                         return -ENOMEM;
  88                                 }
  89
  90                                 strv_free(*controllers);
  91                                 *controllers = l;
  92                         }
  93
  94                 } else if (startswith(argv[i], "reset-controllers=")) {
  95
  96                         if (reset_controllers) {
  97                                 char **l;
  98
  99                                 if (!(l = strv_split(argv[i] + 18, ","))) {
 100                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
 101                                         return -ENOMEM;
 102                                 }
 103
 104                                 strv_free(*reset_controllers);
 105                                 *reset_controllers = l;
 106                         }
 107
 108                 } else if (startswith(argv[i], "kill-only-users=")) {
 109
 110                         if (kill_only_users) {
 111                                 char **l;
 112
 113                                 if (!(l = strv_split(argv[i] + 16, ","))) {
 114                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
 115                                         return -ENOMEM;
 116                                 }
 117
 118                                 strv_free(*kill_only_users);
 119                                 *kill_only_users = l;
 120                         }
 121
 122                 } else if (startswith(argv[i], "kill-exclude-users=")) {
 123
 124                         if (kill_exclude_users) {
 125                                 char **l;
 126
 127                                 if (!(l = strv_split(argv[i] + 19, ","))) {
 128                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
 129                                         return -ENOMEM;
 130                                 }
 131
 132                                 strv_free(*kill_exclude_users);
 133                                 *kill_exclude_users = l;
 134                         }
 135
 136                 } else if (startswith(argv[i], "debug=")) {
 137                         if ((k = parse_boolean(argv[i] + 6)) < 0) {
 138                                 pam_syslog(handle, LOG_ERR, "Failed to parse debug= argument.");
 139                                 return k;
 140                         }
 141
 142                         if (debug)
 143                                 *debug = k;
 144
 145                 } else if (startswith(argv[i], "create-session=") ||
 146                            startswith(argv[i], "kill-user=")) {
 147
 148                         pam_syslog(handle, LOG_WARNING, "Option %s not supported anymore, ignoring.", argv[i]);
 149
 150                 } else {
 151                         pam_syslog(handle, LOG_ERR, "Unknown parameter '%s'.", argv[i]);
 152                         return -EINVAL;
 153                 }
 154         }
 155
 156         return 0;
 157 }
 158
 159 static int get_user_data(
 160                 pam_handle_t *handle,
 161                 const char **ret_username,
 162                 struct passwd **ret_pw) {
 163
 164         const char *username = NULL;
 165         struct passwd *pw = NULL;
 166         int r;
 167         bool have_loginuid = false;
 168         char *s;
 169
 170         assert(handle);
 171         assert(ret_username);
 172         assert(ret_pw);
 173
 174         if (have_effective_cap(CAP_AUDIT_CONTROL) > 0) {
 175                 /* Only use audit login uid if we are executed with
 176                  * sufficient capabilities so that pam_loginuid could
 177                  * do its job. If we are lacking the CAP_AUDIT_CONTROL
 178                  * capabality we most likely are being run in a
 179                  * container and /proc/self/loginuid is useless since
 180                  * it probably contains a uid of the host system. */
 181
 182                 if (read_one_line_file("/proc/self/loginuid", &s) >= 0) {
 183                         uid_t uid;
 184
 185                         r = parse_uid(s, &uid);
 186                         free(s);
 187
 188                         if (r >= 0 && uid != (uint32_t) -1) {
 189                                 have_loginuid = true;
 190                                 pw = pam_modutil_getpwuid(handle, uid);
 191                         }
 192                 }
 193         }
 194
 195         if (!have_loginuid) {
 196                 if ((r = pam_get_user(handle, &username, NULL)) != PAM_SUCCESS) {
 197                         pam_syslog(handle, LOG_ERR, "Failed to get user name.");
 198                         return r;
 199                 }
 200
 201                 if (!username || !*username) {
 202                         pam_syslog(handle, LOG_ERR, "User name not valid.");
 203                         return PAM_AUTH_ERR;
 204                 }
 205
 206                 pw = pam_modutil_getpwnam(handle, username);
 207         }
 208
 209         if (!pw) {
 210                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 211                 return PAM_USER_UNKNOWN;
 212         }
 213
 214         *ret_pw = pw;
 215         *ret_username = username ? username : pw->pw_name;
 216
 217         return PAM_SUCCESS;
 218 }
 219
 220 static bool check_user_lists(
 221                 pam_handle_t *handle,
 222                 uid_t uid,
 223                 char **kill_only_users,
 224                 char **kill_exclude_users) {
 225
 226         const char *name = NULL;
 227         char **l;
 228
 229         assert(handle);
 230
 231         if (uid == 0)
 232                 name = "root"; /* Avoid obvious NSS requests, to suppress network traffic */
 233         else {
 234                 struct passwd *pw;
 235
 236                 pw = pam_modutil_getpwuid(handle, uid);
 237                 if (pw)
 238                         name = pw->pw_name;
 239         }
 240
 241         STRV_FOREACH(l, kill_exclude_users) {
 242                 uid_t u;
 243
 244                 if (parse_uid(*l, &u) >= 0)
 245                         if (u == uid)
 246                                 return false;
 247
 248                 if (name && streq(name, *l))
 249                         return false;
 250         }
 251
 252         if (strv_isempty(kill_only_users))
 253                 return true;
 254
 255         STRV_FOREACH(l, kill_only_users) {
 256                 uid_t u;
 257
 258                 if (parse_uid(*l, &u) >= 0)
 259                         if (u == uid)
 260                                 return true;
 261
 262                 if (name && streq(name, *l))
 263                         return true;
 264         }
 265
 266         return false;
 267 }
 268
 269 static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
 270         char *p = NULL;
 271         int r;
 272         int fd;
 273         union sockaddr_union sa;
 274         struct ucred ucred;
 275         socklen_t l;
 276         char *tty;
 277         int v;
 278
 279         assert(display);
 280         assert(seat);
 281         assert(vtnr);
 282
 283         /* We deduce the X11 socket from the display name, then use
 284          * SO_PEERCRED to determine the X11 server process, ask for
 285          * the controlling tty of that and if it's a VC then we know
 286          * the seat and the virtual terminal. Sounds ugly, is only
 287          * semi-ugly. */
 288
 289         r = socket_from_display(display, &p);
 290         if (r < 0)
 291                 return r;
 292
 293         fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
 294         if (fd < 0) {
 295                 free(p);
 296                 return -errno;
 297         }
 298
 299         zero(sa);
 300         sa.un.sun_family = AF_UNIX;
 301         strncpy(sa.un.sun_path, p, sizeof(sa.un.sun_path)-1);
 302         free(p);
 303
 304         if (connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
 305                 close_nointr_nofail(fd);
 306                 return -errno;
 307         }
 308
 309         l = sizeof(ucred);
 310         r = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &ucred, &l);
 311         close_nointr_nofail(fd);
 312
 313         if (r < 0)
 314                 return -errno;
 315
 316         r = get_ctty(ucred.pid, NULL, &tty);
 317         if (r < 0)
 318                 return r;
 319
 320         v = vtnr_from_tty(tty);
 321         free(tty);
 322
 323         if (v < 0)
 324                 return v;
 325         else if (v == 0)
 326                 return -ENOENT;
 327
 328         *seat = "seat0";
 329         *vtnr = (uint32_t) v;
 330
 331         return 0;
 332 }
 333
 334 _public_ PAM_EXTERN int pam_sm_open_session(
 335                 pam_handle_t *handle,
 336                 int flags,
 337                 int argc, const char **argv) {
 338
 339         struct passwd *pw;
 340         bool kill_processes = false, debug = false;
 341         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;
 342         char **controllers = NULL, **reset_controllers = NULL, **kill_only_users = NULL, **kill_exclude_users = NULL;
 343         DBusError error;
 344         uint32_t uid, pid;
 345         DBusMessageIter iter;
 346         dbus_bool_t kp;
 347         int session_fd = -1;
 348         DBusConnection *bus = NULL;
 349         DBusMessage *m = NULL, *reply = NULL;
 350         dbus_bool_t remote;
 351         int r;
 352         uint32_t vtnr = 0;
 353
 354         assert(handle);
 355
 356         dbus_error_init(&error);
 357
 358         /* pam_syslog(handle, LOG_INFO, "pam-systemd initializing"); */
 359
 360         /* Make this a NOP on non-systemd systems */
 361         if (sd_booted() <= 0)
 362                 return PAM_SUCCESS;
 363
 364         if (parse_argv(handle,
 365                        argc, argv,
 366                        &controllers, &reset_controllers,
 367                        &kill_processes, &kill_only_users, &kill_exclude_users,
 368                        &debug) < 0) {
 369                 r = PAM_SESSION_ERR;
 370                 goto finish;
 371         }
 372
 373         r = get_user_data(handle, &username, &pw);
 374         if (r != PAM_SUCCESS)
 375                 goto finish;
 376
 377         /* Make sure we don't enter a loop by talking to
 378          * systemd-logind when it is actually waiting for the
 379          * background to finish start-up. If the service is
 380          * "systemd-shared" we simply set XDG_RUNTIME_DIR and
 381          * leave. */
 382
 383         pam_get_item(handle, PAM_SERVICE, (const void**) &service);
 384         if (streq_ptr(service, "systemd-shared")) {
 385                 char *p, *rt = NULL;
 386
 387                 if (asprintf(&p, "/run/systemd/users/%lu", (unsigned long) pw->pw_uid) < 0) {
 388                         r = PAM_BUF_ERR;
 389                         goto finish;
 390                 }
 391
 392                 r = parse_env_file(p, NEWLINE,
 393                                    "RUNTIME", &rt,
 394                                    NULL);
 395                 free(p);
 396
 397                 if (r < 0 && r != -ENOENT) {
 398                         r = PAM_SESSION_ERR;
 399                         free(rt);
 400                         goto finish;
 401                 }
 402
 403                 if (rt)  {
 404                         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
 405                         free(rt);
 406
 407                         if (r != PAM_SUCCESS) {
 408                                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 409                                 goto finish;
 410                         }
 411                 }
 412
 413                 r = PAM_SUCCESS;
 414                 goto finish;
 415         }
 416
 417         if (kill_processes)
 418                 kill_processes = check_user_lists(handle, pw->pw_uid, kill_only_users, kill_exclude_users);
 419
 420         dbus_connection_set_change_sigpipe(FALSE);
 421
 422         bus = dbus_bus_get_private(DBUS_BUS_SYSTEM, &error);
 423         if (!bus) {
 424                 pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", bus_error_message(&error));
 425                 r = PAM_SESSION_ERR;
 426                 goto finish;
 427         }
 428
 429         m = dbus_message_new_method_call(
 430                         "org.freedesktop.login1",
 431                         "/org/freedesktop/login1",
 432                         "org.freedesktop.login1.Manager",
 433                         "CreateSession");
 434
 435         if (!m) {
 436                 pam_syslog(handle, LOG_ERR, "Could not allocate create session message.");
 437                 r = PAM_BUF_ERR;
 438                 goto finish;
 439         }
 440
 441         uid = pw->pw_uid;
 442         pid = getpid();
 443
 444         pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
 445         pam_get_item(handle, PAM_TTY, (const void**) &tty);
 446         pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
 447         pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
 448         seat = pam_getenv(handle, "XDG_SEAT");
 449         cvtnr = pam_getenv(handle, "XDG_VTNR");
 450
 451         service = strempty(service);
 452         tty = strempty(tty);
 453         display = strempty(display);
 454         remote_user = strempty(remote_user);
 455         remote_host = strempty(remote_host);
 456         seat = strempty(seat);
 457
 458         if (strchr(tty, ':')) {
 459                 /* A tty with a colon is usually an X11 display, place
 460                  * there to show up in utmp. We rearrange things and
 461                  * don't pretend that an X display was a tty */
 462
 463                 if (isempty(display))
 464                         display = tty;
 465                 tty = "";
 466         }
 467
 468         if (!isempty(cvtnr))
 469                 safe_atou32(cvtnr, &vtnr);
 470
 471         if (!isempty(display) && isempty(seat) && vtnr <= 0)
 472                 get_seat_from_display(display, &seat, &vtnr);
 473
 474         type = !isempty(display) ? "x11" :
 475                    !isempty(tty) ? "tty" : "other";
 476
 477         remote = !isempty(remote_host) && !streq(remote_host, "localhost") && !streq(remote_host, "localhost.localdomain");
 478
 479         if (!dbus_message_append_args(m,
 480                                       DBUS_TYPE_UINT32, &uid,
 481                                       DBUS_TYPE_UINT32, &pid,
 482                                       DBUS_TYPE_STRING, &service,
 483                                       DBUS_TYPE_STRING, &type,
 484                                       DBUS_TYPE_STRING, &seat,
 485                                       DBUS_TYPE_UINT32, &vtnr,
 486                                       DBUS_TYPE_STRING, &tty,
 487                                       DBUS_TYPE_STRING, &display,
 488                                       DBUS_TYPE_BOOLEAN, &remote,
 489                                       DBUS_TYPE_STRING, &remote_user,
 490                                       DBUS_TYPE_STRING, &remote_host,
 491                                       DBUS_TYPE_INVALID)) {
 492                 pam_syslog(handle, LOG_ERR, "Could not attach parameters to message.");
 493                 r = PAM_BUF_ERR;
 494                 goto finish;
 495         }
 496
 497         dbus_message_iter_init_append(m, &iter);
 498
 499         r = bus_append_strv_iter(&iter, controllers);
 500         if (r < 0) {
 501                 pam_syslog(handle, LOG_ERR, "Could not attach parameter to message.");
 502                 r = PAM_BUF_ERR;
 503                 goto finish;
 504         }
 505
 506         r = bus_append_strv_iter(&iter, reset_controllers);
 507         if (r < 0) {
 508                 pam_syslog(handle, LOG_ERR, "Could not attach parameter to message.");
 509                 r = PAM_BUF_ERR;
 510                 goto finish;
 511         }
 512
 513         kp = kill_processes;
 514         if (!dbus_message_iter_append_basic(&iter, DBUS_TYPE_BOOLEAN, &kp)) {
 515                 pam_syslog(handle, LOG_ERR, "Could not attach parameter to message.");
 516                 r = PAM_BUF_ERR;
 517                 goto finish;
 518         }
 519
 520         reply = dbus_connection_send_with_reply_and_block(bus, m, -1, &error);
 521         if (!reply) {
 522                 pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error));
 523                 r = PAM_SESSION_ERR;
 524                 goto finish;
 525         }
 526
 527         if (!dbus_message_get_args(reply, &error,
 528                                    DBUS_TYPE_STRING, &id,
 529                                    DBUS_TYPE_OBJECT_PATH, &object_path,
 530                                    DBUS_TYPE_STRING, &runtime_path,
 531                                    DBUS_TYPE_UNIX_FD, &session_fd,
 532                                    DBUS_TYPE_STRING, &seat,
 533                                    DBUS_TYPE_UINT32, &vtnr,
 534                                    DBUS_TYPE_INVALID)) {
 535                 pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", bus_error_message(&error));
 536                 r = PAM_SESSION_ERR;
 537                 goto finish;
 538         }
 539
 540         r = pam_misc_setenv(handle, "XDG_SESSION_ID", id, 0);
 541         if (r != PAM_SUCCESS) {
 542                 pam_syslog(handle, LOG_ERR, "Failed to set session id.");
 543                 goto finish;
 544         }
 545
 546         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", runtime_path, 0);
 547         if (r != PAM_SUCCESS) {
 548                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 549                 goto finish;
 550         }
 551
 552         if (!isempty(seat)) {
 553                 r = pam_misc_setenv(handle, "XDG_SEAT", seat, 0);
 554                 if (r != PAM_SUCCESS) {
 555                         pam_syslog(handle, LOG_ERR, "Failed to set seat.");
 556                         goto finish;
 557                 }
 558         }
 559
 560         if (vtnr > 0) {
 561                 char buf[11];
 562                 snprintf(buf, sizeof(buf), "%u", vtnr);
 563                 char_array_0(buf);
 564
 565                 r = pam_misc_setenv(handle, "XDG_VTNR", buf, 0);
 566                 if (r != PAM_SUCCESS) {
 567                         pam_syslog(handle, LOG_ERR, "Failed to set virtual terminal number.");
 568                         goto finish;
 569                 }
 570         }
 571
 572         if (session_fd >= 0) {
 573                 r = pam_set_data(handle, "systemd.session-fd", INT_TO_PTR(session_fd+1), NULL);
 574                 if (r != PAM_SUCCESS) {
 575                         pam_syslog(handle, LOG_ERR, "Failed to install session fd.");
 576                         return r;
 577                 }
 578         }
 579
 580         session_fd = -1;
 581
 582         r = PAM_SUCCESS;
 583
 584 finish:
 585         strv_free(controllers);
 586         strv_free(reset_controllers);
 587         strv_free(kill_only_users);
 588         strv_free(kill_exclude_users);
 589
 590         dbus_error_free(&error);
 591
 592         if (bus) {
 593                 dbus_connection_close(bus);
 594                 dbus_connection_unref(bus);
 595         }
 596
 597         if (m)
 598                 dbus_message_unref(m);
 599
 600         if (reply)
 601                 dbus_message_unref(reply);
 602
 603         if (session_fd >= 0)
 604                 close_nointr_nofail(session_fd);
 605
 606         return r;
 607 }
 608
 609 _public_ PAM_EXTERN int pam_sm_close_session(
 610                 pam_handle_t *handle,
 611                 int flags,
 612                 int argc, const char **argv) {
 613
 614         const void *p = NULL;
 615
 616         pam_get_data(handle, "systemd.session-fd", &p);
 617
 618         if (p)
 619                 close_nointr(PTR_TO_INT(p) - 1);
 620
 621         return PAM_SUCCESS;
 622 }