src/login/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 <systemd/sd-daemon.h>
  36
  37 #include "util.h"
  38 #include "macro.h"
  39 #include "strv.h"
  40 #include "dbus-common.h"
  41 #include "def.h"
  42 #include "socket-util.h"
  43
  44 static int parse_argv(pam_handle_t *handle,
  45                       int argc, const char **argv,
  46                       char ***controllers,
  47                       char ***reset_controllers,
  48                       bool *kill_processes,
  49                       char ***kill_only_users,
  50                       char ***kill_exclude_users,
  51                       bool *debug) {
  52
  53         unsigned i;
  54
  55         assert(argc >= 0);
  56         assert(argc == 0 || argv);
  57
  58         for (i = 0; i < (unsigned) argc; i++) {
  59                 int k;
  60
  61                 if (startswith(argv[i], "kill-session-processes=")) {
  62                         if ((k = parse_boolean(argv[i] + 23)) < 0) {
  63                                 pam_syslog(handle, LOG_ERR, "Failed to parse kill-session-processes= argument.");
  64                                 return k;
  65                         }
  66
  67                         if (kill_processes)
  68                                 *kill_processes = k;
  69
  70                 } else if (startswith(argv[i], "kill-session=")) {
  71                         /* As compatibility for old versions */
  72
  73                         if ((k = parse_boolean(argv[i] + 13)) < 0) {
  74                                 pam_syslog(handle, LOG_ERR, "Failed to parse kill-session= argument.");
  75                                 return k;
  76                         }
  77
  78                         if (kill_processes)
  79                                 *kill_processes = k;
  80
  81                 } else if (startswith(argv[i], "controllers=")) {
  82
  83                         if (controllers) {
  84                                 char **l;
  85
  86                                 if (!(l = strv_split(argv[i] + 12, ","))) {
  87                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
  88                                         return -ENOMEM;
  89                                 }
  90
  91                                 strv_free(*controllers);
  92                                 *controllers = l;
  93                         }
  94
  95                 } else if (startswith(argv[i], "reset-controllers=")) {
  96
  97                         if (reset_controllers) {
  98                                 char **l;
  99
 100                                 if (!(l = strv_split(argv[i] + 18, ","))) {
 101                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
 102                                         return -ENOMEM;
 103                                 }
 104
 105                                 strv_free(*reset_controllers);
 106                                 *reset_controllers = l;
 107                         }
 108
 109                 } else if (startswith(argv[i], "kill-only-users=")) {
 110
 111                         if (kill_only_users) {
 112                                 char **l;
 113
 114                                 if (!(l = strv_split(argv[i] + 16, ","))) {
 115                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
 116                                         return -ENOMEM;
 117                                 }
 118
 119                                 strv_free(*kill_only_users);
 120                                 *kill_only_users = l;
 121                         }
 122
 123                 } else if (startswith(argv[i], "kill-exclude-users=")) {
 124
 125                         if (kill_exclude_users) {
 126                                 char **l;
 127
 128                                 if (!(l = strv_split(argv[i] + 19, ","))) {
 129                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
 130                                         return -ENOMEM;
 131                                 }
 132
 133                                 strv_free(*kill_exclude_users);
 134                                 *kill_exclude_users = l;
 135                         }
 136
 137                 } else if (startswith(argv[i], "debug=")) {
 138                         if ((k = parse_boolean(argv[i] + 6)) < 0) {
 139                                 pam_syslog(handle, LOG_ERR, "Failed to parse debug= argument.");
 140                                 return k;
 141                         }
 142
 143                         if (debug)
 144                                 *debug = k;
 145
 146                 } else if (startswith(argv[i], "create-session=") ||
 147                            startswith(argv[i], "kill-user=")) {
 148
 149                         pam_syslog(handle, LOG_WARNING, "Option %s not supported anymore, ignoring.", argv[i]);
 150
 151                 } else {
 152                         pam_syslog(handle, LOG_ERR, "Unknown parameter '%s'.", argv[i]);
 153                         return -EINVAL;
 154                 }
 155         }
 156
 157         return 0;
 158 }
 159
 160 static int get_user_data(
 161                 pam_handle_t *handle,
 162                 const char **ret_username,
 163                 struct passwd **ret_pw) {
 164
 165         const char *username = NULL;
 166         struct passwd *pw = NULL;
 167         uid_t uid;
 168         int r;
 169
 170         assert(handle);
 171         assert(ret_username);
 172         assert(ret_pw);
 173
 174         r = audit_loginuid_from_pid(0, &uid);
 175         if (r >= 0)
 176                 pw = pam_modutil_getpwuid(handle, uid);
 177         else {
 178                 r = pam_get_user(handle, &username, NULL);
 179                 if (r != PAM_SUCCESS) {
 180                         pam_syslog(handle, LOG_ERR, "Failed to get user name.");
 181                         return r;
 182                 }
 183
 184                 if (isempty(username)) {
 185                         pam_syslog(handle, LOG_ERR, "User name not valid.");
 186                         return PAM_AUTH_ERR;
 187                 }
 188
 189                 pw = pam_modutil_getpwnam(handle, username);
 190         }
 191
 192         if (!pw) {
 193                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 194                 return PAM_USER_UNKNOWN;
 195         }
 196
 197         *ret_pw = pw;
 198         *ret_username = username ? username : pw->pw_name;
 199
 200         return PAM_SUCCESS;
 201 }
 202
 203 static bool check_user_lists(
 204                 pam_handle_t *handle,
 205                 uid_t uid,
 206                 char **kill_only_users,
 207                 char **kill_exclude_users) {
 208
 209         const char *name = NULL;
 210         char **l;
 211
 212         assert(handle);
 213
 214         if (uid == 0)
 215                 name = "root"; /* Avoid obvious NSS requests, to suppress network traffic */
 216         else {
 217                 struct passwd *pw;
 218
 219                 pw = pam_modutil_getpwuid(handle, uid);
 220                 if (pw)
 221                         name = pw->pw_name;
 222         }
 223
 224         STRV_FOREACH(l, kill_exclude_users) {
 225                 uid_t u;
 226
 227                 if (parse_uid(*l, &u) >= 0)
 228                         if (u == uid)
 229                                 return false;
 230
 231                 if (name && streq(name, *l))
 232                         return false;
 233         }
 234
 235         if (strv_isempty(kill_only_users))
 236                 return true;
 237
 238         STRV_FOREACH(l, kill_only_users) {
 239                 uid_t u;
 240
 241                 if (parse_uid(*l, &u) >= 0)
 242                         if (u == uid)
 243                                 return true;
 244
 245                 if (name && streq(name, *l))
 246                         return true;
 247         }
 248
 249         return false;
 250 }
 251
 252 static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
 253         char *p = NULL;
 254         int r;
 255         int fd;
 256         union sockaddr_union sa;
 257         struct ucred ucred;
 258         socklen_t l;
 259         char *tty;
 260         int v;
 261
 262         assert(display);
 263         assert(seat);
 264         assert(vtnr);
 265
 266         /* We deduce the X11 socket from the display name, then use
 267          * SO_PEERCRED to determine the X11 server process, ask for
 268          * the controlling tty of that and if it's a VC then we know
 269          * the seat and the virtual terminal. Sounds ugly, is only
 270          * semi-ugly. */
 271
 272         r = socket_from_display(display, &p);
 273         if (r < 0)
 274                 return r;
 275
 276         fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
 277         if (fd < 0) {
 278                 free(p);
 279                 return -errno;
 280         }
 281
 282         zero(sa);
 283         sa.un.sun_family = AF_UNIX;
 284         strncpy(sa.un.sun_path, p, sizeof(sa.un.sun_path)-1);
 285         free(p);
 286
 287         if (connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
 288                 close_nointr_nofail(fd);
 289                 return -errno;
 290         }
 291
 292         l = sizeof(ucred);
 293         r = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &ucred, &l);
 294         close_nointr_nofail(fd);
 295
 296         if (r < 0)
 297                 return -errno;
 298
 299         r = get_ctty(ucred.pid, NULL, &tty);
 300         if (r < 0)
 301                 return r;
 302
 303         v = vtnr_from_tty(tty);
 304         free(tty);
 305
 306         if (v < 0)
 307                 return v;
 308         else if (v == 0)
 309                 return -ENOENT;
 310
 311         *seat = "seat0";
 312         *vtnr = (uint32_t) v;
 313
 314         return 0;
 315 }
 316
 317 _public_ PAM_EXTERN int pam_sm_open_session(
 318                 pam_handle_t *handle,
 319                 int flags,
 320                 int argc, const char **argv) {
 321
 322         struct passwd *pw;
 323         bool kill_processes = false, debug = false;
 324         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;
 325         char **controllers = NULL, **reset_controllers = NULL, **kill_only_users = NULL, **kill_exclude_users = NULL;
 326         DBusError error;
 327         uint32_t uid, pid;
 328         DBusMessageIter iter;
 329         dbus_bool_t kp;
 330         int session_fd = -1;
 331         DBusConnection *bus = NULL;
 332         DBusMessage *m = NULL, *reply = NULL;
 333         dbus_bool_t remote;
 334         int r;
 335         uint32_t vtnr = 0;
 336
 337         assert(handle);
 338
 339         dbus_error_init(&error);
 340
 341         /* pam_syslog(handle, LOG_INFO, "pam-systemd initializing"); */
 342
 343         /* Make this a NOP on non-systemd systems */
 344         if (sd_booted() <= 0)
 345                 return PAM_SUCCESS;
 346
 347         if (parse_argv(handle,
 348                        argc, argv,
 349                        &controllers, &reset_controllers,
 350                        &kill_processes, &kill_only_users, &kill_exclude_users,
 351                        &debug) < 0) {
 352                 r = PAM_SESSION_ERR;
 353                 goto finish;
 354         }
 355
 356         r = get_user_data(handle, &username, &pw);
 357         if (r != PAM_SUCCESS)
 358                 goto finish;
 359
 360         /* Make sure we don't enter a loop by talking to
 361          * systemd-logind when it is actually waiting for the
 362          * background to finish start-up. If the service is
 363          * "systemd-shared" we simply set XDG_RUNTIME_DIR and
 364          * leave. */
 365
 366         pam_get_item(handle, PAM_SERVICE, (const void**) &service);
 367         if (streq_ptr(service, "systemd-shared")) {
 368                 char *p, *rt = NULL;
 369
 370                 if (asprintf(&p, "/run/systemd/users/%lu", (unsigned long) pw->pw_uid) < 0) {
 371                         r = PAM_BUF_ERR;
 372                         goto finish;
 373                 }
 374
 375                 r = parse_env_file(p, NEWLINE,
 376                                    "RUNTIME", &rt,
 377                                    NULL);
 378                 free(p);
 379
 380                 if (r < 0 && r != -ENOENT) {
 381                         r = PAM_SESSION_ERR;
 382                         free(rt);
 383                         goto finish;
 384                 }
 385
 386                 if (rt)  {
 387                         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
 388                         free(rt);
 389
 390                         if (r != PAM_SUCCESS) {
 391                                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 392                                 goto finish;
 393                         }
 394                 }
 395
 396                 r = PAM_SUCCESS;
 397                 goto finish;
 398         }
 399
 400         if (kill_processes)
 401                 kill_processes = check_user_lists(handle, pw->pw_uid, kill_only_users, kill_exclude_users);
 402
 403         dbus_connection_set_change_sigpipe(FALSE);
 404
 405         bus = dbus_bus_get_private(DBUS_BUS_SYSTEM, &error);
 406         if (!bus) {
 407                 pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", bus_error_message(&error));
 408                 r = PAM_SESSION_ERR;
 409                 goto finish;
 410         }
 411
 412         m = dbus_message_new_method_call(
 413                         "org.freedesktop.login1",
 414                         "/org/freedesktop/login1",
 415                         "org.freedesktop.login1.Manager",
 416                         "CreateSession");
 417
 418         if (!m) {
 419                 pam_syslog(handle, LOG_ERR, "Could not allocate create session message.");
 420                 r = PAM_BUF_ERR;
 421                 goto finish;
 422         }
 423
 424         uid = pw->pw_uid;
 425         pid = getpid();
 426
 427         pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
 428         pam_get_item(handle, PAM_TTY, (const void**) &tty);
 429         pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
 430         pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
 431         seat = pam_getenv(handle, "XDG_SEAT");
 432         cvtnr = pam_getenv(handle, "XDG_VTNR");
 433
 434         service = strempty(service);
 435         tty = strempty(tty);
 436         display = strempty(display);
 437         remote_user = strempty(remote_user);
 438         remote_host = strempty(remote_host);
 439         seat = strempty(seat);
 440
 441         if (strchr(tty, ':')) {
 442                 /* A tty with a colon is usually an X11 display, place
 443                  * there to show up in utmp. We rearrange things and
 444                  * don't pretend that an X display was a tty */
 445
 446                 if (isempty(display))
 447                         display = tty;
 448                 tty = "";
 449         } else if (streq(tty, "cron")) {
 450                 /* cron has been setting PAM_TTY to "cron" for a very long time
 451                  * and it cannot stop doing that for compatibility reasons. */
 452                 tty = "";
 453         }
 454
 455         if (!isempty(cvtnr))
 456                 safe_atou32(cvtnr, &vtnr);
 457
 458         if (!isempty(display) && isempty(seat) && vtnr <= 0)
 459                 get_seat_from_display(display, &seat, &vtnr);
 460
 461         type = !isempty(display) ? "x11" :
 462                    !isempty(tty) ? "tty" : "unspecified";
 463
 464         remote = !isempty(remote_host) && !streq(remote_host, "localhost") && !streq(remote_host, "localhost.localdomain");
 465
 466         if (!dbus_message_append_args(m,
 467                                       DBUS_TYPE_UINT32, &uid,
 468                                       DBUS_TYPE_UINT32, &pid,
 469                                       DBUS_TYPE_STRING, &service,
 470                                       DBUS_TYPE_STRING, &type,
 471                                       DBUS_TYPE_STRING, &seat,
 472                                       DBUS_TYPE_UINT32, &vtnr,
 473                                       DBUS_TYPE_STRING, &tty,
 474                                       DBUS_TYPE_STRING, &display,
 475                                       DBUS_TYPE_BOOLEAN, &remote,
 476                                       DBUS_TYPE_STRING, &remote_user,
 477                                       DBUS_TYPE_STRING, &remote_host,
 478                                       DBUS_TYPE_INVALID)) {
 479                 pam_syslog(handle, LOG_ERR, "Could not attach parameters to message.");
 480                 r = PAM_BUF_ERR;
 481                 goto finish;
 482         }
 483
 484         dbus_message_iter_init_append(m, &iter);
 485
 486         r = bus_append_strv_iter(&iter, controllers);
 487         if (r < 0) {
 488                 pam_syslog(handle, LOG_ERR, "Could not attach parameter to message.");
 489                 r = PAM_BUF_ERR;
 490                 goto finish;
 491         }
 492
 493         r = bus_append_strv_iter(&iter, reset_controllers);
 494         if (r < 0) {
 495                 pam_syslog(handle, LOG_ERR, "Could not attach parameter to message.");
 496                 r = PAM_BUF_ERR;
 497                 goto finish;
 498         }
 499
 500         kp = kill_processes;
 501         if (!dbus_message_iter_append_basic(&iter, DBUS_TYPE_BOOLEAN, &kp)) {
 502                 pam_syslog(handle, LOG_ERR, "Could not attach parameter to message.");
 503                 r = PAM_BUF_ERR;
 504                 goto finish;
 505         }
 506
 507         if (debug)
 508                 pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: "
 509                            "uid=%u pid=%u service=%s type=%s seat=%s vtnr=%u tty=%s display=%s remote=%s remote_user=%s remote_host=%s",
 510                            uid, pid, service, type, seat, vtnr, tty, display, yes_no(remote), remote_user, remote_host);
 511
 512         reply = dbus_connection_send_with_reply_and_block(bus, m, -1, &error);
 513         if (!reply) {
 514                 pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error));
 515                 r = PAM_SESSION_ERR;
 516                 goto finish;
 517         }
 518
 519         if (!dbus_message_get_args(reply, &error,
 520                                    DBUS_TYPE_STRING, &id,
 521                                    DBUS_TYPE_OBJECT_PATH, &object_path,
 522                                    DBUS_TYPE_STRING, &runtime_path,
 523                                    DBUS_TYPE_UNIX_FD, &session_fd,
 524                                    DBUS_TYPE_STRING, &seat,
 525                                    DBUS_TYPE_UINT32, &vtnr,
 526                                    DBUS_TYPE_INVALID)) {
 527                 pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", bus_error_message(&error));
 528                 r = PAM_SESSION_ERR;
 529                 goto finish;
 530         }
 531
 532         if (debug)
 533                 pam_syslog(handle, LOG_DEBUG, "Reply from logind: "
 534                            "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u",
 535                            id, object_path, runtime_path, session_fd, seat, vtnr);
 536
 537         r = pam_misc_setenv(handle, "XDG_SESSION_ID", id, 0);
 538         if (r != PAM_SUCCESS) {
 539                 pam_syslog(handle, LOG_ERR, "Failed to set session id.");
 540                 goto finish;
 541         }
 542
 543         r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", runtime_path, 0);
 544         if (r != PAM_SUCCESS) {
 545                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 546                 goto finish;
 547         }
 548
 549         if (!isempty(seat)) {
 550                 r = pam_misc_setenv(handle, "XDG_SEAT", seat, 0);
 551                 if (r != PAM_SUCCESS) {
 552                         pam_syslog(handle, LOG_ERR, "Failed to set seat.");
 553                         goto finish;
 554                 }
 555         }
 556
 557         if (vtnr > 0) {
 558                 char buf[11];
 559                 snprintf(buf, sizeof(buf), "%u", vtnr);
 560                 char_array_0(buf);
 561
 562                 r = pam_misc_setenv(handle, "XDG_VTNR", buf, 0);
 563                 if (r != PAM_SUCCESS) {
 564                         pam_syslog(handle, LOG_ERR, "Failed to set virtual terminal number.");
 565                         goto finish;
 566                 }
 567         }
 568
 569         if (session_fd >= 0) {
 570                 r = pam_set_data(handle, "systemd.session-fd", INT_TO_PTR(session_fd+1), NULL);
 571                 if (r != PAM_SUCCESS) {
 572                         pam_syslog(handle, LOG_ERR, "Failed to install session fd.");
 573                         return r;
 574                 }
 575         }
 576
 577         session_fd = -1;
 578
 579         r = PAM_SUCCESS;
 580
 581 finish:
 582         strv_free(controllers);
 583         strv_free(reset_controllers);
 584         strv_free(kill_only_users);
 585         strv_free(kill_exclude_users);
 586
 587         dbus_error_free(&error);
 588
 589         if (bus) {
 590                 dbus_connection_close(bus);
 591                 dbus_connection_unref(bus);
 592         }
 593
 594         if (m)
 595                 dbus_message_unref(m);
 596
 597         if (reply)
 598                 dbus_message_unref(reply);
 599
 600         if (session_fd >= 0)
 601                 close_nointr_nofail(session_fd);
 602
 603         return r;
 604 }
 605
 606 _public_ PAM_EXTERN int pam_sm_close_session(
 607                 pam_handle_t *handle,
 608                 int flags,
 609                 int argc, const char **argv) {
 610
 611         const void *p = NULL;
 612
 613         pam_get_data(handle, "systemd.session-fd", &p);
 614
 615         if (p)
 616                 close_nointr(PTR_TO_INT(p) - 1);
 617
 618         return PAM_SUCCESS;
 619 }