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         uid_t uid;
 167         int r;
 168
 169         assert(handle);
 170         assert(ret_username);
 171         assert(ret_pw);
 172
 173         r = audit_loginuid_from_pid(0, &uid);
 174         if (r >= 0)
 175                 pw = pam_modutil_getpwuid(handle, uid);
 176         else {
 177                 r = pam_get_user(handle, &username, NULL);
 178                 if (r != PAM_SUCCESS) {
 179                         pam_syslog(handle, LOG_ERR, "Failed to get user name.");
 180                         return r;
 181                 }
 182
 183                 if (isempty(username)) {
 184                         pam_syslog(handle, LOG_ERR, "User name not valid.");
 185                         return PAM_AUTH_ERR;
 186                 }
 187
 188                 pw = pam_modutil_getpwnam(handle, username);
 189         }
 190
 191         if (!pw) {
 192                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 193                 return PAM_USER_UNKNOWN;
 194         }
 195
 196         *ret_pw = pw;
 197         *ret_username = username ? username : pw->pw_name;
 198
 199         return PAM_SUCCESS;
 200 }
 201
 202 static bool check_user_lists(
 203                 pam_handle_t *handle,
 204                 uid_t uid,
 205                 char **kill_only_users,
 206                 char **kill_exclude_users) {
 207
 208         const char *name = NULL;
 209         char **l;
 210
 211         assert(handle);
 212
 213         if (uid == 0)
 214                 name = "root"; /* Avoid obvious NSS requests, to suppress network traffic */
 215         else {
 216                 struct passwd *pw;
 217
 218                 pw = pam_modutil_getpwuid(handle, uid);
 219                 if (pw)
 220                         name = pw->pw_name;
 221         }
 222
 223         STRV_FOREACH(l, kill_exclude_users) {
 224                 uid_t u;
 225
 226                 if (parse_uid(*l, &u) >= 0)
 227                         if (u == uid)
 228                                 return false;
 229
 230                 if (name && streq(name, *l))
 231                         return false;
 232         }
 233
 234         if (strv_isempty(kill_only_users))
 235                 return true;
 236
 237         STRV_FOREACH(l, kill_only_users) {
 238                 uid_t u;
 239
 240                 if (parse_uid(*l, &u) >= 0)
 241                         if (u == uid)
 242                                 return true;
 243
 244                 if (name && streq(name, *l))
 245                         return true;
 246         }
 247
 248         return false;
 249 }
 250
 251 static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
 252         char *p = NULL;
 253         int r;
 254         int fd;
 255         union sockaddr_union sa;
 256         struct ucred ucred;
 257         socklen_t l;
 258         char *tty;
 259         int v;
 260
 261         assert(display);
 262         assert(seat);
 263         assert(vtnr);
 264
 265         /* We deduce the X11 socket from the display name, then use
 266          * SO_PEERCRED to determine the X11 server process, ask for
 267          * the controlling tty of that and if it's a VC then we know
 268          * the seat and the virtual terminal. Sounds ugly, is only
 269          * semi-ugly. */
 270
 271         r = socket_from_display(display, &p);
 272         if (r < 0)
 273                 return r;
 274
 275         fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
 276         if (fd < 0) {
 277                 free(p);
 278                 return -errno;
 279         }
 280
 281         zero(sa);
 282         sa.un.sun_family = AF_UNIX;
 283         strncpy(sa.un.sun_path, p, sizeof(sa.un.sun_path)-1);
 284         free(p);
 285
 286         if (connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
 287                 close_nointr_nofail(fd);
 288                 return -errno;
 289         }
 290
 291         l = sizeof(ucred);
 292         r = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &ucred, &l);
 293         close_nointr_nofail(fd);
 294
 295         if (r < 0)
 296                 return -errno;
 297
 298         r = get_ctty(ucred.pid, NULL, &tty);
 299         if (r < 0)
 300                 return r;
 301
 302         v = vtnr_from_tty(tty);
 303         free(tty);
 304
 305         if (v < 0)
 306                 return v;
 307         else if (v == 0)
 308                 return -ENOENT;
 309
 310         *seat = "seat0";
 311         *vtnr = (uint32_t) v;
 312
 313         return 0;
 314 }
 315
 316 _public_ PAM_EXTERN int pam_sm_open_session(
 317                 pam_handle_t *handle,
 318                 int flags,
 319                 int argc, const char **argv) {
 320
 321         struct passwd *pw;
 322         bool kill_processes = false, debug = false;
 323         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;
 324         char **controllers = NULL, **reset_controllers = NULL, **kill_only_users = NULL, **kill_exclude_users = NULL;
 325         DBusError error;
 326         uint32_t uid, pid;
 327         DBusMessageIter iter;
 328         dbus_bool_t kp;
 329         int session_fd = -1;
 330         DBusConnection *bus = NULL;
 331         DBusMessage *m = NULL, *reply = NULL;
 332         dbus_bool_t remote;
 333         int r;
 334         uint32_t vtnr = 0;
 335
 336         assert(handle);
 337
 338         dbus_error_init(&error);
 339
 340         /* pam_syslog(handle, LOG_INFO, "pam-systemd initializing"); */
 341
 342         /* Make this a NOP on non-systemd systems */
 343         if (sd_booted() <= 0)
 344                 return PAM_SUCCESS;
 345
 346         if (parse_argv(handle,
 347                        argc, argv,
 348                        &controllers, &reset_controllers,
 349                        &kill_processes, &kill_only_users, &kill_exclude_users,
 350                        &debug) < 0) {
 351                 r = PAM_SESSION_ERR;
 352                 goto finish;
 353         }
 354
 355         r = get_user_data(handle, &username, &pw);
 356         if (r != PAM_SUCCESS)
 357                 goto finish;
 358
 359         /* Make sure we don't enter a loop by talking to
 360          * systemd-logind when it is actually waiting for the
 361          * background to finish start-up. If the service is
 362          * "systemd-shared" we simply set XDG_RUNTIME_DIR and
 363          * leave. */
 364
 365         pam_get_item(handle, PAM_SERVICE, (const void**) &service);
 366         if (streq_ptr(service, "systemd-shared")) {
 367                 char *p, *rt = NULL;
 368
 369                 if (asprintf(&p, "/run/systemd/users/%lu", (unsigned long) pw->pw_uid) < 0) {
 370                         r = PAM_BUF_ERR;
 371                         goto finish;
 372                 }
 373
 374                 r = parse_env_file(p, NEWLINE,
 375                                    "RUNTIME", &rt,
 376                                    NULL);
 377                 free(p);
 378
 379                 if (r < 0 && r != -ENOENT) {
 380                         r = PAM_SESSION_ERR;
 381                         free(rt);
 382                         goto finish;
 383                 }
 384
 385                 if (rt)  {
 386                         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
 387                         free(rt);
 388
 389                         if (r != PAM_SUCCESS) {
 390                                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 391                                 goto finish;
 392                         }
 393                 }
 394
 395                 r = PAM_SUCCESS;
 396                 goto finish;
 397         }
 398
 399         if (kill_processes)
 400                 kill_processes = check_user_lists(handle, pw->pw_uid, kill_only_users, kill_exclude_users);
 401
 402         dbus_connection_set_change_sigpipe(FALSE);
 403
 404         bus = dbus_bus_get_private(DBUS_BUS_SYSTEM, &error);
 405         if (!bus) {
 406                 pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", bus_error_message(&error));
 407                 r = PAM_SESSION_ERR;
 408                 goto finish;
 409         }
 410
 411         m = dbus_message_new_method_call(
 412                         "org.freedesktop.login1",
 413                         "/org/freedesktop/login1",
 414                         "org.freedesktop.login1.Manager",
 415                         "CreateSession");
 416
 417         if (!m) {
 418                 pam_syslog(handle, LOG_ERR, "Could not allocate create session message.");
 419                 r = PAM_BUF_ERR;
 420                 goto finish;
 421         }
 422
 423         uid = pw->pw_uid;
 424         pid = getpid();
 425
 426         pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
 427         pam_get_item(handle, PAM_TTY, (const void**) &tty);
 428         pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
 429         pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
 430         seat = pam_getenv(handle, "XDG_SEAT");
 431         cvtnr = pam_getenv(handle, "XDG_VTNR");
 432
 433         service = strempty(service);
 434         tty = strempty(tty);
 435         display = strempty(display);
 436         remote_user = strempty(remote_user);
 437         remote_host = strempty(remote_host);
 438         seat = strempty(seat);
 439
 440         if (strchr(tty, ':')) {
 441                 /* A tty with a colon is usually an X11 display, place
 442                  * there to show up in utmp. We rearrange things and
 443                  * don't pretend that an X display was a tty */
 444
 445                 if (isempty(display))
 446                         display = tty;
 447                 tty = "";
 448         }
 449
 450         if (!isempty(cvtnr))
 451                 safe_atou32(cvtnr, &vtnr);
 452
 453         if (!isempty(display) && isempty(seat) && vtnr <= 0)
 454                 get_seat_from_display(display, &seat, &vtnr);
 455
 456         type = !isempty(display) ? "x11" :
 457                    !isempty(tty) ? "tty" : "other";
 458
 459         remote = !isempty(remote_host) && !streq(remote_host, "localhost") && !streq(remote_host, "localhost.localdomain");
 460
 461         if (!dbus_message_append_args(m,
 462                                       DBUS_TYPE_UINT32, &uid,
 463                                       DBUS_TYPE_UINT32, &pid,
 464                                       DBUS_TYPE_STRING, &service,
 465                                       DBUS_TYPE_STRING, &type,
 466                                       DBUS_TYPE_STRING, &seat,
 467                                       DBUS_TYPE_UINT32, &vtnr,
 468                                       DBUS_TYPE_STRING, &tty,
 469                                       DBUS_TYPE_STRING, &display,
 470                                       DBUS_TYPE_BOOLEAN, &remote,
 471                                       DBUS_TYPE_STRING, &remote_user,
 472                                       DBUS_TYPE_STRING, &remote_host,
 473                                       DBUS_TYPE_INVALID)) {
 474                 pam_syslog(handle, LOG_ERR, "Could not attach parameters to message.");
 475                 r = PAM_BUF_ERR;
 476                 goto finish;
 477         }
 478
 479         dbus_message_iter_init_append(m, &iter);
 480
 481         r = bus_append_strv_iter(&iter, controllers);
 482         if (r < 0) {
 483                 pam_syslog(handle, LOG_ERR, "Could not attach parameter to message.");
 484                 r = PAM_BUF_ERR;
 485                 goto finish;
 486         }
 487
 488         r = bus_append_strv_iter(&iter, reset_controllers);
 489         if (r < 0) {
 490                 pam_syslog(handle, LOG_ERR, "Could not attach parameter to message.");
 491                 r = PAM_BUF_ERR;
 492                 goto finish;
 493         }
 494
 495         kp = kill_processes;
 496         if (!dbus_message_iter_append_basic(&iter, DBUS_TYPE_BOOLEAN, &kp)) {
 497                 pam_syslog(handle, LOG_ERR, "Could not attach parameter to message.");
 498                 r = PAM_BUF_ERR;
 499                 goto finish;
 500         }
 501
 502         reply = dbus_connection_send_with_reply_and_block(bus, m, -1, &error);
 503         if (!reply) {
 504                 pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error));
 505                 r = PAM_SESSION_ERR;
 506                 goto finish;
 507         }
 508
 509         if (!dbus_message_get_args(reply, &error,
 510                                    DBUS_TYPE_STRING, &id,
 511                                    DBUS_TYPE_OBJECT_PATH, &object_path,
 512                                    DBUS_TYPE_STRING, &runtime_path,
 513                                    DBUS_TYPE_UNIX_FD, &session_fd,
 514                                    DBUS_TYPE_STRING, &seat,
 515                                    DBUS_TYPE_UINT32, &vtnr,
 516                                    DBUS_TYPE_INVALID)) {
 517                 pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", bus_error_message(&error));
 518                 r = PAM_SESSION_ERR;
 519                 goto finish;
 520         }
 521
 522         r = pam_misc_setenv(handle, "XDG_SESSION_ID", id, 0);
 523         if (r != PAM_SUCCESS) {
 524                 pam_syslog(handle, LOG_ERR, "Failed to set session id.");
 525                 goto finish;
 526         }
 527
 528         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", runtime_path, 0);
 529         if (r != PAM_SUCCESS) {
 530                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 531                 goto finish;
 532         }
 533
 534         if (!isempty(seat)) {
 535                 r = pam_misc_setenv(handle, "XDG_SEAT", seat, 0);
 536                 if (r != PAM_SUCCESS) {
 537                         pam_syslog(handle, LOG_ERR, "Failed to set seat.");
 538                         goto finish;
 539                 }
 540         }
 541
 542         if (vtnr > 0) {
 543                 char buf[11];
 544                 snprintf(buf, sizeof(buf), "%u", vtnr);
 545                 char_array_0(buf);
 546
 547                 r = pam_misc_setenv(handle, "XDG_VTNR", buf, 0);
 548                 if (r != PAM_SUCCESS) {
 549                         pam_syslog(handle, LOG_ERR, "Failed to set virtual terminal number.");
 550                         goto finish;
 551                 }
 552         }
 553
 554         if (session_fd >= 0) {
 555                 r = pam_set_data(handle, "systemd.session-fd", INT_TO_PTR(session_fd+1), NULL);
 556                 if (r != PAM_SUCCESS) {
 557                         pam_syslog(handle, LOG_ERR, "Failed to install session fd.");
 558                         return r;
 559                 }
 560         }
 561
 562         session_fd = -1;
 563
 564         r = PAM_SUCCESS;
 565
 566 finish:
 567         strv_free(controllers);
 568         strv_free(reset_controllers);
 569         strv_free(kill_only_users);
 570         strv_free(kill_exclude_users);
 571
 572         dbus_error_free(&error);
 573
 574         if (bus) {
 575                 dbus_connection_close(bus);
 576                 dbus_connection_unref(bus);
 577         }
 578
 579         if (m)
 580                 dbus_message_unref(m);
 581
 582         if (reply)
 583                 dbus_message_unref(reply);
 584
 585         if (session_fd >= 0)
 586                 close_nointr_nofail(session_fd);
 587
 588         return r;
 589 }
 590
 591 _public_ PAM_EXTERN int pam_sm_close_session(
 592                 pam_handle_t *handle,
 593                 int flags,
 594                 int argc, const char **argv) {
 595
 596         const void *p = NULL;
 597
 598         pam_get_data(handle, "systemd.session-fd", &p);
 599
 600         if (p)
 601                 close_nointr(PTR_TO_INT(p) - 1);
 602
 603         return PAM_SUCCESS;
 604 }