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