source/nsswitch/pam_winbind.c

   1 /* pam_winbind module
   2
   3    Copyright Andrew Tridgell <tridge@samba.org> 2000
   4    Copyright Tim Potter <tpot@samba.org> 2000
   5    Copyright Andrew Bartlett <abartlet@samba.org> 2002
   6
   7    largely based on pam_userdb by Christian Gafton <gafton@redhat.com>
   8    also contains large slabs of code from pam_unix by Elliot Lee <sopwith@redhat.com>
   9    (see copyright below for full details)
  10 */
  11
  12 #include "pam_winbind.h"
  13
  14 /* prototypes from common.c */
  15 void init_request(struct winbindd_request *req,int rq_type);
  16 int write_sock(void *buffer, int count);
  17 int read_reply(struct winbindd_response *response);
  18
  19 /* data tokens */
  20
  21 #define MAX_PASSWD_TRIES        3
  22
  23 /* some syslogging */
  24 static void _pam_log(int err, const char *format, ...)
  25 {
  26         va_list args;
  27
  28         va_start(args, format);
  29         openlog(MODULE_NAME, LOG_CONS|LOG_PID, LOG_AUTH);
  30         vsyslog(err, format, args);
  31         va_end(args);
  32         closelog();
  33 }
  34
  35 static int _pam_parse(int argc, const char **argv)
  36 {
  37         int ctrl;
  38         /* step through arguments */
  39         for (ctrl = 0; argc-- > 0; ++argv) {
  40
  41                 /* generic options */
  42
  43                 if (!strcmp(*argv,"debug"))
  44                         ctrl |= WINBIND_DEBUG_ARG;
  45                 else if (!strcasecmp(*argv, "use_authtok"))
  46                         ctrl |= WINBIND_USE_AUTHTOK_ARG;
  47                 else if (!strcasecmp(*argv, "use_first_pass"))
  48                         ctrl |= WINBIND_USE_FIRST_PASS_ARG;
  49                 else if (!strcasecmp(*argv, "try_first_pass"))
  50                         ctrl |= WINBIND_TRY_FIRST_PASS_ARG;
  51                 else if (!strcasecmp(*argv, "unknown_ok"))
  52                         ctrl |= WINBIND_UNKNOWN_OK_ARG;
  53                 else {
  54                         _pam_log(LOG_ERR, "pam_parse: unknown option; %s", *argv);
  55                 }
  56         }
  57
  58         return ctrl;
  59 }
  60
  61 /* --- authentication management functions --- */
  62
  63 /* Attempt a conversation */
  64
  65 static int converse(pam_handle_t *pamh, int nargs,
  66                     struct pam_message **message,
  67                     struct pam_response **response)
  68 {
  69     int retval;
  70     struct pam_conv *conv;
  71
  72     retval = pam_get_item(pamh, PAM_CONV, (const void **) &conv ) ;
  73     if (retval == PAM_SUCCESS) {
  74         retval = conv->conv(nargs, (const struct pam_message **)message,
  75                             response, conv->appdata_ptr);
  76     }
  77
  78     return retval; /* propagate error status */
  79 }
  80
  81
  82 int _make_remark(pam_handle_t * pamh, int type, const char *text)
  83 {
  84         int retval = PAM_SUCCESS;
  85
  86         struct pam_message *pmsg[1], msg[1];
  87         struct pam_response *resp;
  88
  89         pmsg[0] = &msg[0];
  90         msg[0].msg = text;
  91         msg[0].msg_style = type;
  92
  93         resp = NULL;
  94         retval = converse(pamh, 1, pmsg, &resp);
  95
  96         if (resp) {
  97                 _pam_drop_reply(resp, 1);
  98         }
  99         return retval;
 100 }
 101
 102 static int winbind_request(enum winbindd_cmd req_type,
 103                            struct winbindd_request *request,
 104                            struct winbindd_response *response)
 105 {
 106         /* Fill in request and send down pipe */
 107         init_request(request, req_type);
 108
 109         if (write_sock(request, sizeof(*request)) == -1) {
 110                 _pam_log(LOG_ERR, "write to socket failed!");
 111                 return PAM_SERVICE_ERR;
 112         }
 113
 114         /* Wait for reply */
 115         if (read_reply(response) == -1) {
 116                 _pam_log(LOG_ERR, "read from socket failed!");
 117                 return PAM_SERVICE_ERR;
 118         }
 119
 120         /* Copy reply data from socket */
 121         if (response->result != WINBINDD_OK) {
 122                 if (response->data.auth.pam_error != PAM_SUCCESS) {
 123                         _pam_log(LOG_ERR, "request failed, PAM error was %d, NT error was %s",
 124                                  response->data.auth.pam_error,
 125                                  response->data.auth.nt_status_string);
 126                         return response->data.auth.pam_error;
 127                 } else {
 128                         _pam_log(LOG_ERR, "request failed, but PAM error 0!");
 129                         return PAM_SERVICE_ERR;
 130                 }
 131         }
 132
 133         return PAM_SUCCESS;
 134 }
 135
 136 /* talk to winbindd */
 137 static int winbind_auth_request(const char *user, const char *pass, int ctrl)
 138 {
 139         struct winbindd_request request;
 140         struct winbindd_response response;
 141         int retval;
 142
 143         ZERO_STRUCT(request);
 144
 145         strncpy(request.data.auth.user, user,
 146                 sizeof(request.data.auth.user)-1);
 147
 148         strncpy(request.data.auth.pass, pass,
 149                 sizeof(request.data.auth.pass)-1);
 150
 151         retval = winbind_request(WINBINDD_PAM_AUTH, &request, &response);
 152
 153         switch (retval) {
 154         case PAM_AUTH_ERR:
 155                 /* incorrect password */
 156                 _pam_log(LOG_WARNING, "user `%s' denied access (incorrect password)", user);
 157                 return retval;
 158         case PAM_USER_UNKNOWN:
 159                 /* the user does not exist */
 160                 if (ctrl & WINBIND_DEBUG_ARG)
 161                         _pam_log(LOG_NOTICE, "user `%s' not found",
 162                                  user);
 163                 if (ctrl & WINBIND_UNKNOWN_OK_ARG) {
 164                         return PAM_IGNORE;
 165                 }
 166                 return retval;
 167         case PAM_SUCCESS:
 168                 /* Otherwise, the authentication looked good */
 169                 _pam_log(LOG_NOTICE, "user '%s' granted acces", user);
 170                 return retval;
 171         default:
 172                 /* we don't know anything about this return value */
 173                 _pam_log(LOG_ERR, "internal module error (retval = %d, user = `%s'",
 174                          retval, user);
 175                 return retval;
 176         }
 177      /* should not be reached */
 178 }
 179
 180 /* talk to winbindd */
 181 static int winbind_chauthtok_request(const char *user, const char *oldpass,
 182                                      const char *newpass)
 183 {
 184         struct winbindd_request request;
 185         struct winbindd_response response;
 186
 187         ZERO_STRUCT(request);
 188
 189         if (request.data.chauthtok.user == NULL) return -2;
 190
 191         strncpy(request.data.chauthtok.user, user,
 192                 sizeof(request.data.chauthtok.user) - 1);
 193
 194         if (oldpass != NULL) {
 195             strncpy(request.data.chauthtok.oldpass, oldpass,
 196                     sizeof(request.data.chauthtok.oldpass) - 1);
 197         } else {
 198             request.data.chauthtok.oldpass[0] = '\0';
 199         }
 200
 201         if (newpass != NULL) {
 202             strncpy(request.data.chauthtok.newpass, newpass,
 203                     sizeof(request.data.chauthtok.newpass) - 1);
 204         } else {
 205             request.data.chauthtok.newpass[0] = '\0';
 206         }
 207
 208         return winbind_request(WINBINDD_PAM_CHAUTHTOK, &request, &response);
 209 }
 210
 211 /*
 212  * Checks if a user has an account
 213  *
 214  * return values:
 215  *       1  = User not found
 216  *       0  = OK
 217  *      -1  = System error
 218  */
 219 static int valid_user(const char *user)
 220 {
 221         if (getpwnam(user)) return 0;
 222         return 1;
 223 }
 224
 225 static char *_pam_delete(register char *xx)
 226 {
 227     _pam_overwrite(xx);
 228     _pam_drop(xx);
 229     return NULL;
 230 }
 231
 232 /*
 233  * obtain a password from the user
 234  */
 235
 236 int _winbind_read_password(pam_handle_t * pamh
 237                         ,unsigned int ctrl
 238                         ,const char *comment
 239                         ,const char *prompt1
 240                         ,const char *prompt2
 241                         ,const char **pass)
 242 {
 243         int authtok_flag;
 244         int retval;
 245         const char *item;
 246         char *token;
 247
 248         /*
 249          * make sure nothing inappropriate gets returned
 250          */
 251
 252         *pass = token = NULL;
 253
 254         /*
 255          * which authentication token are we getting?
 256          */
 257
 258         authtok_flag = on(WINBIND__OLD_PASSWORD, ctrl) ? PAM_OLDAUTHTOK : PAM_AUTHTOK;
 259
 260         /*
 261          * should we obtain the password from a PAM item ?
 262          */
 263
 264         if (on(WINBIND_TRY_FIRST_PASS_ARG, ctrl) || on(WINBIND_USE_FIRST_PASS_ARG, ctrl)) {
 265                 retval = pam_get_item(pamh, authtok_flag, (const void **) &item);
 266                 if (retval != PAM_SUCCESS) {
 267                         /* very strange. */
 268                         _pam_log(LOG_ALERT,
 269                                  "pam_get_item returned error to unix-read-password"
 270                             );
 271                         return retval;
 272                 } else if (item != NULL) {      /* we have a password! */
 273                         *pass = item;
 274                         item = NULL;
 275                         return PAM_SUCCESS;
 276                 } else if (on(WINBIND_USE_FIRST_PASS_ARG, ctrl)) {
 277                         return PAM_AUTHTOK_RECOVER_ERR;         /* didn't work */
 278                 } else if (on(WINBIND_USE_AUTHTOK_ARG, ctrl)
 279                            && off(WINBIND__OLD_PASSWORD, ctrl)) {
 280                         return PAM_AUTHTOK_RECOVER_ERR;
 281                 }
 282         }
 283         /*
 284          * getting here implies we will have to get the password from the
 285          * user directly.
 286          */
 287
 288         {
 289                 struct pam_message msg[3], *pmsg[3];
 290                 struct pam_response *resp;
 291                 int i, replies;
 292
 293                 /* prepare to converse */
 294
 295                 if (comment != NULL) {
 296                         pmsg[0] = &msg[0];
 297                         msg[0].msg_style = PAM_TEXT_INFO;
 298                         msg[0].msg = comment;
 299                         i = 1;
 300                 } else {
 301                         i = 0;
 302                 }
 303
 304                 pmsg[i] = &msg[i];
 305                 msg[i].msg_style = PAM_PROMPT_ECHO_OFF;
 306                 msg[i++].msg = prompt1;
 307                 replies = 1;
 308
 309                 if (prompt2 != NULL) {
 310                         pmsg[i] = &msg[i];
 311                         msg[i].msg_style = PAM_PROMPT_ECHO_OFF;
 312                         msg[i++].msg = prompt2;
 313                         ++replies;
 314                 }
 315                 /* so call the conversation expecting i responses */
 316                 resp = NULL;
 317                 retval = converse(pamh, i, pmsg, &resp);
 318
 319                 if (resp != NULL) {
 320
 321                         /* interpret the response */
 322
 323                         if (retval == PAM_SUCCESS) {    /* a good conversation */
 324
 325                                 token = x_strdup(resp[i - replies].resp);
 326                                 if (token != NULL) {
 327                                         if (replies == 2) {
 328
 329                                                 /* verify that password entered correctly */
 330                                                 if (!resp[i - 1].resp
 331                                                     || strcmp(token, resp[i - 1].resp)) {
 332                                                         _pam_delete(token);     /* mistyped */
 333                                                         retval = PAM_AUTHTOK_RECOVER_ERR;
 334                                                         _make_remark(pamh                                                                   ,PAM_ERROR_MSG, MISTYPED_PASS);
 335                                                 }
 336                                         }
 337                                 } else {
 338                                         _pam_log(LOG_NOTICE
 339                                                  ,"could not recover authentication token");
 340                                 }
 341
 342                         }
 343                         /*
 344                          * tidy up the conversation (resp_retcode) is ignored
 345                          * -- what is it for anyway? AGM
 346                          */
 347
 348                         _pam_drop_reply(resp, i);
 349
 350                 } else {
 351                         retval = (retval == PAM_SUCCESS)
 352                             ? PAM_AUTHTOK_RECOVER_ERR : retval;
 353                 }
 354         }
 355
 356         if (retval != PAM_SUCCESS) {
 357                 if (on(WINBIND_DEBUG_ARG, ctrl))
 358                         _pam_log(LOG_DEBUG,
 359                                  "unable to obtain a password");
 360                 return retval;
 361         }
 362         /* 'token' is the entered password */
 363
 364         /* we store this password as an item */
 365
 366         retval = pam_set_item(pamh, authtok_flag, token);
 367         _pam_delete(token);     /* clean it up */
 368         if (retval != PAM_SUCCESS
 369             || (retval = pam_get_item(pamh, authtok_flag
 370                                       ,(const void **) &item))
 371             != PAM_SUCCESS) {
 372
 373                 _pam_log(LOG_CRIT, "error manipulating password");
 374                 return retval;
 375
 376         }
 377
 378         *pass = item;
 379         item = NULL;            /* break link to password */
 380
 381         return PAM_SUCCESS;
 382 }
 383
 384 PAM_EXTERN
 385 int pam_sm_authenticate(pam_handle_t *pamh, int flags,
 386                         int argc, const char **argv)
 387 {
 388      const char *username;
 389      const char *password;
 390      int retval = PAM_AUTH_ERR;
 391
 392      /* parse arguments */
 393      int ctrl = _pam_parse(argc, argv);
 394
 395      /* Get the username */
 396      retval = pam_get_user(pamh, &username, NULL);
 397      if ((retval != PAM_SUCCESS) || (!username)) {
 398         if (ctrl & WINBIND_DEBUG_ARG)
 399             _pam_log(LOG_DEBUG,"can not get the username");
 400         return PAM_SERVICE_ERR;
 401      }
 402
 403      retval = _winbind_read_password(pamh, ctrl, NULL,
 404                                      "Password: ", NULL,
 405                                      &password);
 406
 407      if (retval != PAM_SUCCESS) {
 408          _pam_log(LOG_ERR, "Could not retrieve user's password");
 409          return PAM_AUTHTOK_ERR;
 410      }
 411
 412      if (ctrl & WINBIND_DEBUG_ARG) {
 413
 414              /* Let's not give too much away in the log file */
 415
 416 #ifdef DEBUG_PASSWORD
 417          _pam_log(LOG_INFO, "Verify user `%s' with password `%s'",
 418                   username, password);
 419 #else
 420          _pam_log(LOG_INFO, "Verify user `%s'", username);
 421 #endif
 422      }
 423
 424      /* Now use the username to look up password */
 425      return winbind_auth_request(username, password, ctrl);
 426 }
 427
 428 PAM_EXTERN
 429 int pam_sm_setcred(pam_handle_t *pamh, int flags,
 430                    int argc, const char **argv)
 431 {
 432     return PAM_SUCCESS;
 433 }
 434
 435 /*
 436  * Account management. We want to verify that the account exists
 437  * before returning PAM_SUCCESS
 438  */
 439 PAM_EXTERN
 440 int pam_sm_acct_mgmt(pam_handle_t *pamh, int flags,
 441                    int argc, const char **argv)
 442 {
 443     const char *username;
 444     int retval = PAM_USER_UNKNOWN;
 445
 446     /* parse arguments */
 447     int ctrl = _pam_parse(argc, argv);
 448
 449     /* Get the username */
 450     retval = pam_get_user(pamh, &username, NULL);
 451     if ((retval != PAM_SUCCESS) || (!username)) {
 452         if (ctrl & WINBIND_DEBUG_ARG)
 453             _pam_log(LOG_DEBUG,"can not get the username");
 454         return PAM_SERVICE_ERR;
 455     }
 456
 457     /* Verify the username */
 458     retval = valid_user(username);
 459     switch (retval) {
 460         case -1:
 461             /* some sort of system error. The log was already printed */
 462             return PAM_SERVICE_ERR;
 463         case 1:
 464             /* the user does not exist */
 465             if (ctrl & WINBIND_DEBUG_ARG)
 466                 _pam_log(LOG_NOTICE, "user `%s' not found",
 467                          username);
 468             if (ctrl & WINBIND_UNKNOWN_OK_ARG)
 469                 return PAM_IGNORE;
 470             return PAM_USER_UNKNOWN;
 471         case 0:
 472             /* Otherwise, the authentication looked good */
 473             _pam_log(LOG_NOTICE, "user '%s' granted acces", username);
 474             return PAM_SUCCESS;
 475         default:
 476             /* we don't know anything about this return value */
 477             _pam_log(LOG_ERR, "internal module error (retval = %d, user = `%s'",
 478                      retval, username);
 479             return PAM_SERVICE_ERR;
 480     }
 481
 482     /* should not be reached */
 483     return PAM_IGNORE;
 484 }
 485 PAM_EXTERN
 486 int pam_sm_open_session(pam_handle_t *pamh, int flags,
 487                 int argc, const char **argv)
 488 {
 489         /* parse arguments */
 490         int ctrl = _pam_parse(argc, argv);
 491         if (ctrl & WINBIND_DEBUG_ARG)
 492               _pam_log(LOG_DEBUG,"libpam_winbind:pam_sm_open_session handler");
 493         return PAM_SUCCESS;
 494 }
 495 PAM_EXTERN
 496 int pam_sm_close_session(pam_handle_t *pamh, int flags,
 497                 int argc, const char **argv)
 498 {
 499         /* parse arguments */
 500         int ctrl = _pam_parse(argc, argv);
 501         if (ctrl & WINBIND_DEBUG_ARG)
 502               _pam_log(LOG_DEBUG,"libpam_winbind:pam_sm_close_session handler");
 503         return PAM_SUCCESS;
 504 }
 505
 506
 507
 508 PAM_EXTERN int pam_sm_chauthtok(pam_handle_t * pamh, int flags,
 509                                 int argc, const char **argv)
 510 {
 511         unsigned int lctrl;
 512         int retval;
 513         unsigned int ctrl = _pam_parse(argc, argv);
 514
 515         /* <DO NOT free() THESE> */
 516         const char *user;
 517         char *pass_old, *pass_new;
 518         /* </DO NOT free() THESE> */
 519
 520         char *Announce;
 521
 522         int retry = 0;
 523
 524         /*
 525          * First get the name of a user
 526          */
 527         retval = pam_get_user(pamh, &user, "Username: ");
 528         if (retval == PAM_SUCCESS) {
 529                 if (user == NULL) {
 530                         _pam_log(LOG_ERR, "username was NULL!");
 531                         return PAM_USER_UNKNOWN;
 532                 }
 533                 if (retval == PAM_SUCCESS && on(WINBIND_DEBUG_ARG, ctrl))
 534                         _pam_log(LOG_DEBUG, "username [%s] obtained",
 535                                  user);
 536         } else {
 537                 if (on(WINBIND_DEBUG_ARG, ctrl))
 538                         _pam_log(LOG_DEBUG,
 539                                  "password - could not identify user");
 540                 return retval;
 541         }
 542
 543         /*
 544          * obtain and verify the current password (OLDAUTHTOK) for
 545          * the user.
 546          */
 547
 548         if (flags & PAM_PRELIM_CHECK) {
 549
 550                 /* instruct user what is happening */
 551 #define greeting "Changing password for "
 552                 Announce = (char *) malloc(sizeof(greeting) + strlen(user));
 553                 if (Announce == NULL) {
 554                 _pam_log(LOG_CRIT,
 555                          "password - out of memory");
 556                 return PAM_BUF_ERR;
 557                 }
 558                 (void) strcpy(Announce, greeting);
 559                 (void) strcpy(Announce + sizeof(greeting) - 1, user);
 560 #undef greeting
 561
 562                 lctrl = ctrl | WINBIND__OLD_PASSWORD;
 563                 retval = _winbind_read_password(pamh, lctrl
 564                                                 ,Announce
 565                                                 ,"(current) NT password: "
 566                                                 ,NULL
 567                                                 ,(const char **) &pass_old);
 568                 free(Announce);
 569
 570                 if (retval != PAM_SUCCESS) {
 571                         _pam_log(LOG_NOTICE
 572                                  ,"password - (old) token not obtained");
 573                         return retval;
 574                 }
 575                 /* verify that this is the password for this user */
 576
 577                 retval = winbind_auth_request(user, pass_old, ctrl);
 578
 579                 if (retval != PAM_ACCT_EXPIRED
 580                     && retval != PAM_NEW_AUTHTOK_REQD
 581                     && retval != PAM_SUCCESS) {
 582                         pass_old = NULL;
 583                         return retval;
 584                 }
 585
 586                 retval = pam_set_item(pamh, PAM_OLDAUTHTOK, (const void *) pass_old);
 587                 pass_old = NULL;
 588                 if (retval != PAM_SUCCESS) {
 589                         _pam_log(LOG_CRIT,
 590                                  "failed to set PAM_OLDAUTHTOK");
 591                 }
 592         } else if (flags & PAM_UPDATE_AUTHTOK) {
 593
 594                 /*
 595                  * obtain the proposed password
 596                  */
 597
 598                 /*
 599                  * get the old token back.
 600                  */
 601
 602                 retval = pam_get_item(pamh, PAM_OLDAUTHTOK
 603                                       ,(const void **) &pass_old);
 604
 605                 if (retval != PAM_SUCCESS) {
 606                         _pam_log(LOG_NOTICE, "user not authenticated");
 607                         return retval;
 608                 }
 609
 610                 lctrl = ctrl;
 611
 612                 if (on(WINBIND_USE_AUTHTOK_ARG, lctrl)) {
 613                         ctrl = WINBIND_USE_FIRST_PASS_ARG | lctrl;
 614                 }
 615                 retry = 0;
 616                 retval = PAM_AUTHTOK_ERR;
 617                 while ((retval != PAM_SUCCESS) && (retry++ < MAX_PASSWD_TRIES)) {
 618                         /*
 619                          * use_authtok is to force the use of a previously entered
 620                          * password -- needed for pluggable password strength checking
 621                          */
 622
 623                         retval = _winbind_read_password(pamh, lctrl
 624                                                         ,NULL
 625                                                         ,"Enter new NT password: "
 626                                                         ,"Retype new NT password: "
 627                                                         ,(const char **) &pass_new);
 628
 629                         if (retval != PAM_SUCCESS) {
 630                                 if (on(WINBIND_DEBUG_ARG, ctrl)) {
 631                                         _pam_log(LOG_ALERT
 632                                                  ,"password - new password not obtained");
 633                                 }
 634                                 pass_old = NULL;/* tidy up */
 635                                 return retval;
 636                         }
 637
 638                         /*
 639                          * At this point we know who the user is and what they
 640                          * propose as their new password. Verify that the new
 641                          * password is acceptable.
 642                          */
 643
 644                         if (pass_new[0] == '\0') {/* "\0" password = NULL */
 645                                 pass_new = NULL;
 646                         }
 647                 }
 648
 649                 /*
 650                  * By reaching here we have approved the passwords and must now
 651                  * rebuild the password database file.
 652                  */
 653
 654                 retval = winbind_chauthtok_request(user, pass_old, pass_new);
 655                 _pam_overwrite(pass_new);
 656                 _pam_overwrite(pass_old);
 657                 pass_old = pass_new = NULL;
 658         } else {
 659                 retval = PAM_SERVICE_ERR;
 660         }
 661
 662         return retval;
 663 }
 664
 665 #ifdef PAM_STATIC
 666
 667 /* static module data */
 668
 669 struct pam_module _pam_winbind_modstruct = {
 670      MODULE_NAME,
 671      pam_sm_authenticate,
 672      pam_sm_setcred,
 673      pam_sm_acct_mgmt,
 674      pam_sm_open_session,
 675      pam_sm_close_session,
 676      pam_sm_chauthtok
 677 };
 678
 679 #endif
 680
 681 /*
 682  * Copyright (c) Andrew Tridgell  <tridge@samba.org>   2000
 683  * Copyright (c) Tim Potter       <tpot@samba.org>     2000
 684  * Copyright (c) Andrew Bartlettt <abartlet@samba.org> 2002
 685  * Copyright (c) Jan Rêkorajski 1999.
 686  * Copyright (c) Andrew G. Morgan 1996-8.
 687  * Copyright (c) Alex O. Yuriev, 1996.
 688  * Copyright (c) Cristian Gafton 1996.
 689  * Copyright (C) Elliot Lee <sopwith@redhat.com> 1996, Red Hat Software.
 690  *
 691  * Redistribution and use in source and binary forms, with or without
 692  * modification, are permitted provided that the following conditions
 693  * are met:
 694  * 1. Redistributions of source code must retain the above copyright
 695  *    notice, and the entire permission notice in its entirety,
 696  *    including the disclaimer of warranties.
 697  * 2. Redistributions in binary form must reproduce the above copyright
 698  *    notice, this list of conditions and the following disclaimer in the
 699  *    documentation and/or other materials provided with the distribution.
 700  * 3. The name of the author may not be used to endorse or promote
 701  *    products derived from this software without specific prior
 702  *    written permission.
 703  *
 704  * ALTERNATIVELY, this product may be distributed under the terms of
 705  * the GNU Public License, in which case the provisions of the GPL are
 706  * required INSTEAD OF the above restrictions.  (This clause is
 707  * necessary due to a potential bad interaction between the GPL and
 708  * the restrictions contained in a BSD-style copyright.)
 709  *
 710  * THIS SOFTWARE IS PROVIDED `AS IS'' AND ANY EXPRESS OR IMPLIED
 711  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 712  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 713  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 714  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 715  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 716  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 717  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 718  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 719  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 720  * OF THE POSSIBILITY OF SUCH DAMAGE.
 721  */