source3/pam_smbpass/support.c

   1 /* Unix NT password database implementation, version 0.6.
   2  *
   3  * This program is free software; you can redistribute it and/or modify it under
   4  * the terms of the GNU General Public License as published by the Free
   5  * Software Foundation; either version 3 of the License, or (at your option)
   6  * any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, see <http://www.gnu.org/licenses/>.
  15  */
  16
  17 #include "config.h"
  18 #include "includes.h"
  19 #include "general.h"
  20
  21 #include "support.h"
  22 #include "secrets.h"
  23
  24 #include "../libcli/auth/libcli_auth.h"
  25 #if defined(HAVE_SECURITY_PAM_EXT_H)
  26 #include <security/pam_ext.h>
  27 #elif defined(HAVE_PAM_PAM_EXT_H)
  28 #include <pam/pam_ext.h>
  29 #endif
  30
  31 #if defined(HAVE_SECURITY__PAM_MACROS_H)
  32 #include <security/_pam_macros.h>
  33 #elif defined(HAVE_PAM__PAM_MACROS_H)
  34 #include <pam/_pam_macros.h>
  35 #endif
  36
  37 #ifdef HAVE_SYSLOG_H
  38 #include <syslog.h>
  39 #endif
  40
  41 #define _pam_overwrite(x)        \
  42 do {                             \
  43      register char *__xx__;      \
  44      if ((__xx__=(x)))           \
  45           while (*__xx__)        \
  46                *__xx__++ = '\0'; \
  47 } while (0)
  48
  49 /*
  50  * Don't just free it, forget it too.
  51  */
  52
  53 #define _pam_drop(X) \
  54 do {                 \
  55     if (X) {         \
  56         free(X);     \
  57         X=NULL;      \
  58     }                \
  59 } while (0)
  60
  61 #define _pam_drop_reply(/* struct pam_response * */ reply, /* int */ replies) \
  62 do {                                              \
  63     int reply_i;                                  \
  64                                                   \
  65     for (reply_i=0; reply_i<replies; ++reply_i) { \
  66         if (reply[reply_i].resp) {                \
  67             _pam_overwrite(reply[reply_i].resp);  \
  68             free(reply[reply_i].resp);            \
  69         }                                         \
  70     }                                             \
  71     if (reply)                                    \
  72         free(reply);                              \
  73 } while (0)
  74
  75
  76 int converse(pam_handle_t *, int, int, struct pam_message **,
  77                          struct pam_response **);
  78 int make_remark(pam_handle_t *, unsigned int, int, const char *);
  79 void _cleanup(pam_handle_t *, void *, int);
  80 char *_pam_delete(register char *);
  81
  82 /* syslogging function for errors and other information */
  83 #ifdef HAVE_PAM_VSYSLOG
  84 void _log_err( pam_handle_t *pamh, int err, const char *format, ... )
  85 {
  86         va_list args;
  87
  88         va_start(args, format);
  89         pam_vsyslog(pamh, err, format, args);
  90         va_end(args);
  91 }
  92 #else
  93 void _log_err( pam_handle_t *pamh, int err, const char *format, ... )
  94 {
  95         va_list args;
  96         char *mod_format;
  97
  98         if (asprintf(&mod_format, "(pam_smbpass) %s", format) == -1) {
  99                 /*
 100                  * try really, really hard to log something, since
 101                  * this may have been a message about a malloc()
 102                  * failure...
 103                  */
 104                 va_start(args, format);
 105                 vsyslog(err | LOG_AUTH, format, args);
 106                 va_end(args);
 107                 return;
 108         }
 109
 110         va_start(args, format);
 111         vsyslog(err | LOG_AUTH, mod_format, args);
 112         va_end(args);
 113
 114         free(mod_format);
 115 }
 116 #endif
 117
 118 /* this is a front-end for module-application conversations */
 119
 120 int converse( pam_handle_t * pamh, int ctrl, int nargs
 121               , struct pam_message **message
 122               , struct pam_response **response )
 123 {
 124         int retval;
 125         struct pam_conv *conv;
 126
 127         retval = _pam_get_item(pamh, PAM_CONV, &conv);
 128         if (retval == PAM_SUCCESS) {
 129
 130                 retval = conv->conv(nargs, (const struct pam_message **) message
 131                                                         ,response, conv->appdata_ptr);
 132
 133                 if (retval != PAM_SUCCESS && on(SMB_DEBUG, ctrl)) {
 134                         _log_err(pamh, LOG_DEBUG, "conversation failure [%s]"
 135                                          ,pam_strerror(pamh, retval));
 136                 }
 137         } else {
 138                 _log_err(pamh, LOG_ERR, "couldn't obtain coversation function [%s]"
 139                                  ,pam_strerror(pamh, retval));
 140         }
 141
 142         return retval;                          /* propagate error status */
 143 }
 144
 145 int make_remark( pam_handle_t * pamh, unsigned int ctrl
 146                  , int type, const char *text )
 147 {
 148         if (off(SMB__QUIET, ctrl)) {
 149                 struct pam_message *pmsg[1], msg[1];
 150                 struct pam_response *resp;
 151
 152                 pmsg[0] = &msg[0];
 153                 msg[0].msg = CONST_DISCARD(char *, text);
 154                 msg[0].msg_style = type;
 155                 resp = NULL;
 156
 157                 return converse(pamh, ctrl, 1, pmsg, &resp);
 158         }
 159         return PAM_SUCCESS;
 160 }
 161
 162
 163 /* set the control flags for the SMB module. */
 164
 165 int set_ctrl( pam_handle_t *pamh, int flags, int argc, const char **argv )
 166 {
 167     int i = 0;
 168     const char *service_file = NULL;
 169     unsigned int ctrl;
 170
 171     ctrl = SMB_DEFAULTS;        /* the default selection of options */
 172
 173     /* set some flags manually */
 174
 175     /* A good, sane default (matches Samba's behavior). */
 176     set( SMB__NONULL, ctrl );
 177
 178     /* initialize service file location */
 179     service_file=get_dyn_CONFIGFILE();
 180
 181     if (flags & PAM_SILENT) {
 182         set( SMB__QUIET, ctrl );
 183     }
 184
 185     /* Run through the arguments once, looking for an alternate smb config
 186        file location */
 187     while (i < argc) {
 188         int j;
 189
 190         for (j = 0; j < SMB_CTRLS_; ++j) {
 191             if (smb_args[j].token
 192                 && !strncmp(argv[i], smb_args[j].token, strlen(smb_args[j].token)))
 193             {
 194                 break;
 195             }
 196         }
 197
 198         if (j == SMB_CONF_FILE) {
 199             service_file = argv[i] + 8;
 200         }
 201         i++;
 202     }
 203
 204     /* Read some options from the Samba config. Can be overridden by
 205        the PAM config. */
 206     if(lp_load(service_file,True,False,False,True) == False) {
 207         _log_err(pamh, LOG_ERR, "Error loading service file %s", service_file);
 208     }
 209
 210     secrets_init();
 211
 212     if (lp_null_passwords()) {
 213         set( SMB__NULLOK, ctrl );
 214     }
 215
 216     /* now parse the rest of the arguments to this module */
 217
 218     while (argc-- > 0) {
 219         int j;
 220
 221         for (j = 0; j < SMB_CTRLS_; ++j) {
 222             if (smb_args[j].token
 223                 && !strncmp(*argv, smb_args[j].token, strlen(smb_args[j].token)))
 224             {
 225                 break;
 226             }
 227         }
 228
 229         if (j >= SMB_CTRLS_) {
 230             _log_err(pamh, LOG_ERR, "unrecognized option [%s]", *argv);
 231         } else {
 232             ctrl &= smb_args[j].mask;   /* for turning things off */
 233             ctrl |= smb_args[j].flag;   /* for turning things on  */
 234         }
 235
 236         ++argv;                         /* step to next argument */
 237     }
 238
 239     /* auditing is a more sensitive version of debug */
 240
 241     if (on( SMB_AUDIT, ctrl )) {
 242         set( SMB_DEBUG, ctrl );
 243     }
 244     /* return the set of flags */
 245
 246     return ctrl;
 247 }
 248
 249 /* use this to free strings. ESPECIALLY password strings */
 250
 251 char * _pam_delete( register char *xx )
 252 {
 253     _pam_overwrite( xx );
 254     _pam_drop( xx );
 255     return NULL;
 256 }
 257
 258 void _cleanup( pam_handle_t * pamh, void *x, int error_status )
 259 {
 260     x = _pam_delete( (char *) x );
 261 }
 262
 263 /* JHT
 264  *
 265  * Safe duplication of character strings. "Paranoid"; don't leave
 266  * evidence of old token around for later stack analysis.
 267  *
 268  */
 269 char * smbpXstrDup( pam_handle_t *pamh, const char *x )
 270 {
 271     register char *newstr = NULL;
 272
 273     if (x != NULL) {
 274         register int i;
 275
 276         for (i = 0; x[i]; ++i); /* length of string */
 277         if ((newstr = SMB_MALLOC_ARRAY(char, ++i)) == NULL) {
 278             i = 0;
 279             _log_err(pamh, LOG_CRIT, "out of memory in smbpXstrDup");
 280         } else {
 281             while (i-- > 0) {
 282                 newstr[i] = x[i];
 283             }
 284         }
 285         x = NULL;
 286     }
 287     return newstr;                      /* return the duplicate or NULL on error */
 288 }
 289
 290 /* ************************************************************** *
 291  * Useful non-trivial functions                                   *
 292  * ************************************************************** */
 293
 294 void _cleanup_failures( pam_handle_t * pamh, void *fl, int err )
 295 {
 296     int quiet;
 297     const char *service = NULL;
 298     struct _pam_failed_auth *failure;
 299
 300 #ifdef PAM_DATA_SILENT
 301     quiet = err & PAM_DATA_SILENT;      /* should we log something? */
 302 #else
 303     quiet = 0;
 304 #endif
 305 #ifdef PAM_DATA_REPLACE
 306     err &= PAM_DATA_REPLACE;    /* are we just replacing data? */
 307 #endif
 308     failure = (struct _pam_failed_auth *) fl;
 309
 310     if (failure != NULL) {
 311
 312 #ifdef PAM_DATA_SILENT
 313         if (!quiet && !err) {   /* under advisement from Sun,may go away */
 314 #else
 315         if (!quiet) {   /* under advisement from Sun,may go away */
 316 #endif
 317
 318             /* log the number of authentication failures */
 319             if (failure->count != 0) {
 320                 _pam_get_item( pamh, PAM_SERVICE, &service );
 321                 _log_err(pamh, LOG_NOTICE
 322                           , "%d authentication %s "
 323                             "from %s for service %s as %s(%d)"
 324                           , failure->count
 325                           , failure->count == 1 ? "failure" : "failures"
 326                           , failure->agent
 327                           , service == NULL ? "**unknown**" : service
 328                           , failure->user, failure->id );
 329                 if (failure->count > SMB_MAX_RETRIES) {
 330                     _log_err(pamh, LOG_ALERT
 331                               , "service(%s) ignoring max retries; %d > %d"
 332                               , service == NULL ? "**unknown**" : service
 333                               , failure->count
 334                               , SMB_MAX_RETRIES );
 335                 }
 336             }
 337         }
 338         _pam_delete( failure->agent );  /* tidy up */
 339         _pam_delete( failure->user );   /* tidy up */
 340         SAFE_FREE( failure );
 341     }
 342 }
 343
 344 int _smb_verify_password( pam_handle_t * pamh, struct samu *sampass,
 345                           const char *p, unsigned int ctrl )
 346 {
 347     uchar lm_pw[16];
 348     uchar nt_pw[16];
 349     int retval = PAM_AUTH_ERR;
 350     char *data_name;
 351     const char *name;
 352
 353     if (!sampass)
 354         return PAM_ABORT;
 355
 356     name = pdb_get_username(sampass);
 357
 358 #ifdef HAVE_PAM_FAIL_DELAY
 359     if (off( SMB_NODELAY, ctrl )) {
 360         (void) pam_fail_delay( pamh, 1000000 ); /* 1 sec delay for on failure */
 361     }
 362 #endif
 363
 364     if (!pdb_get_nt_passwd(sampass))
 365     {
 366         _log_err(pamh, LOG_DEBUG, "user %s has null SMB password", name);
 367
 368         if (off( SMB__NONULL, ctrl )
 369             && (pdb_get_acct_ctrl(sampass) & ACB_PWNOTREQ))
 370         { /* this means we've succeeded */
 371             return PAM_SUCCESS;
 372         } else {
 373             const char *service;
 374
 375             _pam_get_item( pamh, PAM_SERVICE, &service );
 376             _log_err(pamh, LOG_NOTICE, "failed auth request by %s for service %s as %s",
 377                       uidtoname(getuid()), service ? service : "**unknown**", name);
 378             return PAM_AUTH_ERR;
 379         }
 380     }
 381
 382     if (asprintf(&data_name, "-SMB-FAIL- %s", name) == -1) {
 383         _log_err(pamh, LOG_CRIT, "no memory for data-name" );
 384         return PAM_AUTH_ERR;
 385     }
 386
 387     /*
 388      * The password we were given wasn't an encrypted password, or it
 389      * didn't match the one we have.  We encrypt the password now and try
 390      * again.
 391      */
 392
 393     nt_lm_owf_gen(p, nt_pw, lm_pw);
 394
 395     /* the moment of truth -- do we agree with the password? */
 396
 397     if (!memcmp( nt_pw, pdb_get_nt_passwd(sampass), 16 )) {
 398
 399         retval = PAM_SUCCESS;
 400         if (data_name) {                /* reset failures */
 401             pam_set_data(pamh, data_name, NULL, _cleanup_failures);
 402         }
 403     } else {
 404
 405         const char *service;
 406
 407         _pam_get_item( pamh, PAM_SERVICE, &service );
 408
 409         if (data_name != NULL) {
 410             struct _pam_failed_auth *newauth = NULL;
 411             const struct _pam_failed_auth *old = NULL;
 412
 413             /* get a failure recorder */
 414
 415             newauth = SMB_MALLOC_P( struct _pam_failed_auth );
 416
 417             if (newauth != NULL) {
 418
 419                 /* any previous failures for this user ? */
 420                 _pam_get_data(pamh, data_name, &old);
 421
 422                 if (old != NULL) {
 423                     newauth->count = old->count + 1;
 424                     if (newauth->count >= SMB_MAX_RETRIES) {
 425                         retval = PAM_MAXTRIES;
 426                     }
 427                 } else {
 428                     _log_err(pamh, LOG_NOTICE,
 429                       "failed auth request by %s for service %s as %s",
 430                       uidtoname(getuid()),
 431                       service ? service : "**unknown**", name);
 432                     newauth->count = 1;
 433                 }
 434                 if (!sid_to_uid(pdb_get_user_sid(sampass), &(newauth->id))) {
 435                     _log_err(pamh, LOG_NOTICE,
 436                       "failed auth request by %s for service %s as %s",
 437                       uidtoname(getuid()),
 438                       service ? service : "**unknown**", name);
 439                 }
 440                 newauth->user = smbpXstrDup( pamh, name );
 441                 newauth->agent = smbpXstrDup( pamh, uidtoname( getuid() ) );
 442                 pam_set_data( pamh, data_name, newauth, _cleanup_failures );
 443
 444             } else {
 445                 _log_err(pamh, LOG_CRIT, "no memory for failure recorder" );
 446                 _log_err(pamh, LOG_NOTICE,
 447                       "failed auth request by %s for service %s as %s(%d)",
 448                       uidtoname(getuid()),
 449                       service ? service : "**unknown**", name);
 450             }
 451         }
 452         _log_err(pamh, LOG_NOTICE,
 453                   "failed auth request by %s for service %s as %s(%d)",
 454                   uidtoname(getuid()),
 455                   service ? service : "**unknown**", name);
 456         retval = PAM_AUTH_ERR;
 457     }
 458
 459     _pam_delete( data_name );
 460
 461     return retval;
 462 }
 463
 464
 465 /*
 466  * _smb_blankpasswd() is a quick check for a blank password
 467  *
 468  * returns TRUE if user does not have a password
 469  * - to avoid prompting for one in such cases (CG)
 470  */
 471
 472 int _smb_blankpasswd( unsigned int ctrl, struct samu *sampass )
 473 {
 474         int retval;
 475
 476         /*
 477          * This function does not have to be too smart if something goes
 478          * wrong, return FALSE and let this case to be treated somewhere
 479          * else (CG)
 480          */
 481
 482         if (on( SMB__NONULL, ctrl ))
 483                 return 0;               /* will fail but don't let on yet */
 484
 485         if (!(pdb_get_acct_ctrl(sampass) & ACB_PWNOTREQ))
 486                 return 0;
 487
 488         if (pdb_get_nt_passwd(sampass) == NULL)
 489                 retval = 1;
 490         else
 491                 retval = 0;
 492
 493         return retval;
 494 }
 495
 496 /*
 497  * obtain a password from the user
 498  */
 499
 500 int _smb_read_password( pam_handle_t * pamh, unsigned int ctrl,
 501                         const char *comment, const char *prompt1,
 502                         const char *prompt2, const char *data_name, char **pass )
 503 {
 504     int authtok_flag;
 505     int retval;
 506     char *item = NULL;
 507     char *token;
 508
 509     struct pam_message msg[3], *pmsg[3];
 510     struct pam_response *resp;
 511     int i, expect;
 512
 513
 514     /* make sure nothing inappropriate gets returned */
 515
 516     *pass = token = NULL;
 517
 518     /* which authentication token are we getting? */
 519
 520     authtok_flag = on(SMB__OLD_PASSWD, ctrl) ? PAM_OLDAUTHTOK : PAM_AUTHTOK;
 521
 522     /* should we obtain the password from a PAM item ? */
 523
 524     if (on(SMB_TRY_FIRST_PASS, ctrl) || on(SMB_USE_FIRST_PASS, ctrl)) {
 525         retval = _pam_get_item( pamh, authtok_flag, &item );
 526         if (retval != PAM_SUCCESS) {
 527             /* very strange. */
 528             _log_err(pamh, LOG_ALERT,
 529                      "pam_get_item returned error to smb_read_password");
 530             return retval;
 531         } else if (item != NULL) {      /* we have a password! */
 532             *pass = item;
 533             item = NULL;
 534             return PAM_SUCCESS;
 535         } else if (on( SMB_USE_FIRST_PASS, ctrl )) {
 536             return PAM_AUTHTOK_RECOVER_ERR;             /* didn't work */
 537         } else if (on( SMB_USE_AUTHTOK, ctrl )
 538                    && off( SMB__OLD_PASSWD, ctrl ))
 539         {
 540             return PAM_AUTHTOK_RECOVER_ERR;
 541         }
 542     }
 543
 544     /*
 545      * getting here implies we will have to get the password from the
 546      * user directly.
 547      */
 548
 549     /* prepare to converse */
 550     if (comment != NULL && off(SMB__QUIET, ctrl)) {
 551         pmsg[0] = &msg[0];
 552         msg[0].msg_style = PAM_TEXT_INFO;
 553         msg[0].msg = CONST_DISCARD(char *, comment);
 554         i = 1;
 555     } else {
 556         i = 0;
 557     }
 558
 559     pmsg[i] = &msg[i];
 560     msg[i].msg_style = PAM_PROMPT_ECHO_OFF;
 561     msg[i++].msg = CONST_DISCARD(char *, prompt1);
 562
 563     if (prompt2 != NULL) {
 564         pmsg[i] = &msg[i];
 565         msg[i].msg_style = PAM_PROMPT_ECHO_OFF;
 566         msg[i++].msg = CONST_DISCARD(char *, prompt2);
 567         expect = 2;
 568     } else
 569         expect = 1;
 570
 571     resp = NULL;
 572
 573     retval = converse( pamh, ctrl, i, pmsg, &resp );
 574
 575     if (resp != NULL) {
 576         int j = comment ? 1 : 0;
 577         /* interpret the response */
 578
 579         if (retval == PAM_SUCCESS) {    /* a good conversation */
 580
 581             token = smbpXstrDup(pamh, resp[j++].resp);
 582             if (token != NULL) {
 583                 if (expect == 2) {
 584                     /* verify that password entered correctly */
 585                     if (!resp[j].resp || strcmp( token, resp[j].resp )) {
 586                         _pam_delete( token );
 587                         retval = PAM_AUTHTOK_RECOVER_ERR;
 588                         make_remark( pamh, ctrl, PAM_ERROR_MSG
 589                                      , MISTYPED_PASS );
 590                     }
 591                 }
 592             } else {
 593                 _log_err(pamh, LOG_NOTICE,
 594                          "could not recover authentication token");
 595             }
 596         }
 597
 598         /* tidy up */
 599         _pam_drop_reply( resp, expect );
 600
 601     } else {
 602         retval = (retval == PAM_SUCCESS) ? PAM_AUTHTOK_RECOVER_ERR : retval;
 603     }
 604
 605     if (retval != PAM_SUCCESS) {
 606         if (on( SMB_DEBUG, ctrl ))
 607             _log_err(pamh, LOG_DEBUG, "unable to obtain a password");
 608         return retval;
 609     }
 610     /* 'token' is the entered password */
 611
 612     if (off( SMB_NOT_SET_PASS, ctrl )) {
 613
 614         /* we store this password as an item */
 615
 616         retval = pam_set_item( pamh, authtok_flag, (const void *)token );
 617         _pam_delete( token );           /* clean it up */
 618         if (retval != PAM_SUCCESS
 619             || (retval = _pam_get_item( pamh, authtok_flag
 620                             ,&item )) != PAM_SUCCESS)
 621         {
 622             _log_err(pamh, LOG_CRIT, "error manipulating password");
 623             return retval;
 624         }
 625     } else {
 626         /*
 627          * then store it as data specific to this module. pam_end()
 628          * will arrange to clean it up.
 629          */
 630
 631         retval = pam_set_data( pamh, data_name, (void *) token, _cleanup );
 632         if (retval != PAM_SUCCESS
 633             || (retval = _pam_get_data( pamh, data_name, &item ))
 634                              != PAM_SUCCESS)
 635         {
 636             _log_err(pamh, LOG_CRIT, "error manipulating password data [%s]",
 637                      pam_strerror( pamh, retval ));
 638             _pam_delete( token );
 639             item = NULL;
 640             return retval;
 641         }
 642         token = NULL;                   /* break link to password */
 643     }
 644
 645     *pass = item;
 646     item = NULL;                        /* break link to password */
 647
 648     return PAM_SUCCESS;
 649 }
 650
 651 int _pam_smb_approve_pass(pam_handle_t * pamh,
 652                 unsigned int ctrl,
 653                 const char *pass_old,
 654                 const char *pass_new )
 655 {
 656
 657     /* Further checks should be handled through module stacking. -SRL */
 658     if (pass_new == NULL || (pass_old && !strcmp( pass_old, pass_new )))
 659     {
 660         if (on(SMB_DEBUG, ctrl)) {
 661             _log_err(pamh, LOG_DEBUG,
 662                      "passwd: bad authentication token (null or unchanged)");
 663         }
 664         make_remark( pamh, ctrl, PAM_ERROR_MSG, pass_new == NULL ?
 665                                 "No password supplied" : "Password unchanged" );
 666         return PAM_AUTHTOK_ERR;
 667     }
 668
 669     return PAM_SUCCESS;
 670 }
 671
 672 /*
 673  * Work around the pam API that has functions with void ** as parameters
 674  * These lead to strict aliasing warnings with gcc.
 675  */
 676 int _pam_get_item(const pam_handle_t *pamh,
 677                   int item_type,
 678                   const void *_item)
 679 {
 680         const void **item = (const void **)_item;
 681         return pam_get_item(pamh, item_type, item);
 682 }
 683
 684 int _pam_get_data(const pam_handle_t *pamh,
 685                   const char *module_data_name,
 686                   const void *_data)
 687 {
 688         const void **data = (const void **)_data;
 689         return pam_get_data(pamh, module_data_name, data);
 690 }