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 2 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, write to the Free Software Foundation, Inc., 675
  15          * Mass Ave, Cambridge, MA 02139, USA.
  16          */
  17
  18         #include "includes.h"
  19         #include "general.h"
  20
  21         #include "support.h"
  22
  23
  24         #define _pam_overwrite(x)        \
  25         do {                             \
  26              register char *__xx__;      \
  27              if ((__xx__=(x)))           \
  28                   while (*__xx__)        \
  29                        *__xx__++ = '\0'; \
  30         } while (0)
  31
  32         /*
  33          * Don't just free it, forget it too.
  34          */
  35
  36         #define _pam_drop(X) \
  37         do {                 \
  38             if (X) {         \
  39                 free(X);     \
  40                 X=NULL;      \
  41             }                \
  42         } while (0)
  43
  44         #define _pam_drop_reply(/* struct pam_response * */ reply, /* int */ replies) \
  45         do {                                              \
  46             int reply_i;                                  \
  47                                                           \
  48             for (reply_i=0; reply_i<replies; ++reply_i) { \
  49                 if (reply[reply_i].resp) {                \
  50                     _pam_overwrite(reply[reply_i].resp);  \
  51                     free(reply[reply_i].resp);            \
  52                 }                                         \
  53             }                                             \
  54             if (reply)                                    \
  55                 free(reply);                              \
  56         } while (0)
  57
  58
  59         int converse(pam_handle_t *, int, int, struct pam_message **,
  60                                  struct pam_response **);
  61         int make_remark(pam_handle_t *, unsigned int, int, const char *);
  62         void _cleanup(pam_handle_t *, void *, int);
  63         char *_pam_delete(register char *);
  64
  65         /* default configuration file location */
  66
  67         char *servicesf = dyn_CONFIGFILE;
  68
  69         /* syslogging function for errors and other information */
  70
  71         void _log_err( int err, const char *format, ... )
  72         {
  73             va_list args;
  74
  75             va_start( args, format );
  76             openlog( "PAM_smbpass", LOG_CONS | LOG_PID, LOG_AUTH );
  77             vsyslog( err, format, args );
  78             va_end( args );
  79             closelog();
  80         }
  81
  82         /* this is a front-end for module-application conversations */
  83
  84         int converse( pam_handle_t * pamh, int ctrl, int nargs
  85                       , struct pam_message **message
  86                       , struct pam_response **response )
  87         {
  88                 int retval;
  89                 struct pam_conv *conv;
  90
  91                 retval = pam_get_item(pamh, PAM_CONV, (const void **) &conv);
  92                 if (retval == PAM_SUCCESS) {
  93
  94                         retval = conv->conv(nargs, (const struct pam_message **) message
  95                                                                 ,response, conv->appdata_ptr);
  96
  97                         if (retval != PAM_SUCCESS && on(SMB_DEBUG, ctrl)) {
  98                                 _log_err(LOG_DEBUG, "conversation failure [%s]"
  99                                                  ,pam_strerror(pamh, retval));
 100                         }
 101                 } else {
 102                         _log_err(LOG_ERR, "couldn't obtain coversation function [%s]"
 103                                          ,pam_strerror(pamh, retval));
 104                 }
 105
 106                 return retval;                          /* propagate error status */
 107         }
 108
 109         int make_remark( pam_handle_t * pamh, unsigned int ctrl
 110                          , int type, const char *text )
 111         {
 112                 if (off(SMB__QUIET, ctrl)) {
 113                         struct pam_message *pmsg[1], msg[1];
 114                         struct pam_response *resp;
 115
 116                         pmsg[0] = &msg[0];
 117                         msg[0].msg = text;
 118                         msg[0].msg_style = type;
 119                         resp = NULL;
 120
 121                         return converse(pamh, ctrl, 1, pmsg, &resp);
 122                 }
 123                 return PAM_SUCCESS;
 124         }
 125
 126
 127         /* set the control flags for the SMB module. */
 128
 129 int set_ctrl( int flags, int argc, const char **argv )
 130 {
 131     int i = 0;
 132     const char *service_file = dyn_CONFIGFILE;
 133     unsigned int ctrl;
 134
 135     ctrl = SMB_DEFAULTS;        /* the default selection of options */
 136
 137     /* set some flags manually */
 138
 139     /* A good, sane default (matches Samba's behavior). */
 140     set( SMB__NONULL, ctrl );
 141
 142     /* initialize service file location */
 143     service_file=servicesf;
 144
 145     if (flags & PAM_SILENT) {
 146         set( SMB__QUIET, ctrl );
 147     }
 148
 149     /* Run through the arguments once, looking for an alternate smb config
 150        file location */
 151     while (i < argc) {
 152         int j;
 153
 154         for (j = 0; j < SMB_CTRLS_; ++j) {
 155             if (smb_args[j].token
 156                 && !strncmp(argv[i], smb_args[j].token, strlen(smb_args[j].token)))
 157             {
 158                 break;
 159             }
 160         }
 161
 162         if (j == SMB_CONF_FILE) {
 163             service_file = argv[i] + 8;
 164         }
 165         i++;
 166     }
 167
 168     /* Read some options from the Samba config. Can be overridden by
 169        the PAM config. */
 170     if(lp_load(service_file,True,False,False) == False) {
 171         _log_err( LOG_ERR, "Error loading service file %s", service_file );
 172     }
 173
 174     secrets_init();
 175
 176     if (lp_null_passwords()) {
 177         set( SMB__NULLOK, ctrl );
 178     }
 179
 180     /* now parse the rest of the arguments to this module */
 181
 182     while (argc-- > 0) {
 183         int j;
 184
 185         for (j = 0; j < SMB_CTRLS_; ++j) {
 186             if (smb_args[j].token
 187                 && !strncmp(*argv, smb_args[j].token, strlen(smb_args[j].token)))
 188             {
 189                 break;
 190             }
 191         }
 192
 193         if (j >= SMB_CTRLS_) {
 194             _log_err( LOG_ERR, "unrecognized option [%s]", *argv );
 195         } else {
 196             ctrl &= smb_args[j].mask;   /* for turning things off */
 197             ctrl |= smb_args[j].flag;   /* for turning things on  */
 198         }
 199
 200         ++argv;                         /* step to next argument */
 201     }
 202
 203     /* auditing is a more sensitive version of debug */
 204
 205     if (on( SMB_AUDIT, ctrl )) {
 206         set( SMB_DEBUG, ctrl );
 207     }
 208     /* return the set of flags */
 209
 210     return ctrl;
 211 }
 212
 213 /* use this to free strings. ESPECIALLY password strings */
 214
 215 char * _pam_delete( register char *xx )
 216 {
 217     _pam_overwrite( xx );
 218     _pam_drop( xx );
 219     return NULL;
 220 }
 221
 222 void _cleanup( pam_handle_t * pamh, void *x, int error_status )
 223 {
 224     x = _pam_delete( (char *) x );
 225 }
 226
 227 /* JHT
 228  *
 229  * Safe duplication of character strings. "Paranoid"; don't leave
 230  * evidence of old token around for later stack analysis.
 231  *
 232  */
 233 char * smbpXstrDup( const char *x )
 234 {
 235     register char *new = NULL;
 236
 237     if (x != NULL) {
 238         register int i;
 239
 240         for (i = 0; x[i]; ++i); /* length of string */
 241         if ((new = malloc(++i)) == NULL) {
 242             i = 0;
 243             _log_err( LOG_CRIT, "out of memory in smbpXstrDup" );
 244         } else {
 245             while (i-- > 0) {
 246                 new[i] = x[i];
 247             }
 248         }
 249         x = NULL;
 250     }
 251     return new;                 /* return the duplicate or NULL on error */
 252 }
 253
 254 /* ************************************************************** *
 255  * Useful non-trivial functions                                   *
 256  * ************************************************************** */
 257
 258 void _cleanup_failures( pam_handle_t * pamh, void *fl, int err )
 259 {
 260     int quiet;
 261     const char *service = NULL;
 262     struct _pam_failed_auth *failure;
 263
 264 #ifdef PAM_DATA_SILENT
 265     quiet = err & PAM_DATA_SILENT;      /* should we log something? */
 266 #else
 267     quiet = 0;
 268 #endif
 269 #ifdef PAM_DATA_REPLACE
 270     err &= PAM_DATA_REPLACE;    /* are we just replacing data? */
 271 #endif
 272     failure = (struct _pam_failed_auth *) fl;
 273
 274     if (failure != NULL) {
 275
 276 #ifdef PAM_DATA_SILENT
 277         if (!quiet && !err) {   /* under advisement from Sun,may go away */
 278 #else
 279         if (!quiet) {   /* under advisement from Sun,may go away */
 280 #endif
 281
 282             /* log the number of authentication failures */
 283             if (failure->count != 0) {
 284                 pam_get_item( pamh, PAM_SERVICE, (const void **) &service );
 285                 _log_err( LOG_NOTICE
 286                           , "%d authentication %s "
 287                             "from %s for service %s as %s(%d)"
 288                           , failure->count
 289                           , failure->count == 1 ? "failure" : "failures"
 290                           , failure->agent
 291                           , service == NULL ? "**unknown**" : service
 292                           , failure->user, failure->id );
 293                 if (failure->count > SMB_MAX_RETRIES) {
 294                     _log_err( LOG_ALERT
 295                               , "service(%s) ignoring max retries; %d > %d"
 296                               , service == NULL ? "**unknown**" : service
 297                               , failure->count
 298                               , SMB_MAX_RETRIES );
 299                 }
 300             }
 301         }
 302         _pam_delete( failure->agent );  /* tidy up */
 303         _pam_delete( failure->user );   /* tidy up */
 304         SAFE_FREE( failure );
 305     }
 306 }
 307
 308 int _smb_verify_password( pam_handle_t * pamh, SAM_ACCOUNT *sampass,
 309                           const char *p, unsigned int ctrl )
 310 {
 311     uchar hash_pass[16];
 312     uchar lm_pw[16];
 313     uchar nt_pw[16];
 314     int retval = PAM_AUTH_ERR;
 315     char *data_name;
 316     const char *name;
 317
 318     if (!sampass)
 319         return PAM_ABORT;
 320
 321     name = pdb_get_username(sampass);
 322
 323 #ifdef HAVE_PAM_FAIL_DELAY
 324     if (off( SMB_NODELAY, ctrl )) {
 325         (void) pam_fail_delay( pamh, 1000000 ); /* 1 sec delay for on failure */
 326     }
 327 #endif
 328
 329     if (!pdb_get_lanman_passwd(sampass))
 330     {
 331         _log_err( LOG_DEBUG, "user %s has null SMB password"
 332                   , name );
 333
 334         if (off( SMB__NONULL, ctrl )
 335             && (pdb_get_acct_ctrl(sampass) & ACB_PWNOTREQ))
 336         { /* this means we've succeeded */
 337             return PAM_SUCCESS;
 338         } else {
 339             const char *service;
 340
 341             pam_get_item( pamh, PAM_SERVICE, (const void **)&service );
 342             _log_err( LOG_NOTICE
 343                       , "failed auth request by %s for service %s as %s(%d)"
 344                       , uidtoname( getuid() )
 345                       , service ? service : "**unknown**", name
 346                       , pdb_get_uid(sampass) );
 347             return PAM_AUTH_ERR;
 348         }
 349     }
 350
 351     data_name = (char *) malloc( sizeof(FAIL_PREFIX) + strlen( name ));
 352     if (data_name == NULL) {
 353         _log_err( LOG_CRIT, "no memory for data-name" );
 354     }
 355     strncpy( data_name, FAIL_PREFIX, sizeof(FAIL_PREFIX) );
 356     strncpy( data_name + sizeof(FAIL_PREFIX) - 1, name, strlen( name ) + 1 );
 357
 358     /*
 359      * The password we were given wasn't an encrypted password, or it
 360      * didn't match the one we have.  We encrypt the password now and try
 361      * again.
 362      */
 363
 364     nt_lm_owf_gen(p, nt_pw, lm_pw);
 365
 366     /* the moment of truth -- do we agree with the password? */
 367
 368     if (!memcmp( nt_pw, pdb_get_nt_passwd(sampass), 16 )) {
 369
 370         retval = PAM_SUCCESS;
 371         if (data_name) {                /* reset failures */
 372             pam_set_data(pamh, data_name, NULL, _cleanup_failures);
 373         }
 374     } else {
 375
 376         const char *service;
 377
 378         pam_get_item( pamh, PAM_SERVICE, (const void **)&service );
 379
 380         if (data_name != NULL) {
 381             struct _pam_failed_auth *new = NULL;
 382             const struct _pam_failed_auth *old = NULL;
 383
 384             /* get a failure recorder */
 385
 386             new = (struct _pam_failed_auth *)
 387                       malloc( sizeof(struct _pam_failed_auth) );
 388
 389             if (new != NULL) {
 390
 391                 /* any previous failures for this user ? */
 392                 pam_get_data(pamh, data_name, (const void **) &old);
 393
 394                 if (old != NULL) {
 395                     new->count = old->count + 1;
 396                     if (new->count >= SMB_MAX_RETRIES) {
 397                         retval = PAM_MAXTRIES;
 398                     }
 399                 } else {
 400                     _log_err( LOG_NOTICE
 401                       , "failed auth request by %s for service %s as %s(%d)"
 402                       , uidtoname( getuid() )
 403                       , service ? service : "**unknown**", name
 404                       , pdb_get_uid(sampass) );
 405                     new->count = 1;
 406                 }
 407                 new->user = smbpXstrDup( name );
 408                 new->id = pdb_get_uid(sampass);
 409                 new->agent = smbpXstrDup( uidtoname( getuid() ) );
 410                 pam_set_data( pamh, data_name, new, _cleanup_failures );
 411
 412             } else {
 413                 _log_err( LOG_CRIT, "no memory for failure recorder" );
 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                       , pdb_get_uid(sampass) );
 419             }
 420         } else {
 421             _log_err( LOG_NOTICE
 422                       , "failed auth request by %s for service %s as %s(%d)"
 423                       , uidtoname( getuid() )
 424                       , service ? service : "**unknown**", name
 425                       , pdb_get_uid(sampass) );
 426             retval = PAM_AUTH_ERR;
 427         }
 428     }
 429
 430     _pam_delete( data_name );
 431
 432     return retval;
 433 }
 434
 435
 436 /*
 437  * _smb_blankpasswd() is a quick check for a blank password
 438  *
 439  * returns TRUE if user does not have a password
 440  * - to avoid prompting for one in such cases (CG)
 441  */
 442
 443 int _smb_blankpasswd( unsigned int ctrl, SAM_ACCOUNT *sampass )
 444 {
 445         int retval;
 446
 447         /*
 448          * This function does not have to be too smart if something goes
 449          * wrong, return FALSE and let this case to be treated somewhere
 450          * else (CG)
 451          */
 452
 453         if (on( SMB__NONULL, ctrl ))
 454                 return 0;               /* will fail but don't let on yet */
 455
 456         if (pdb_get_lanman_passwd(sampass) == NULL)
 457                 retval = 1;
 458         else
 459                 retval = 0;
 460
 461         return retval;
 462 }
 463
 464 /*
 465  * obtain a password from the user
 466  */
 467
 468 int _smb_read_password( pam_handle_t * pamh, unsigned int ctrl,
 469                         const char *comment, const char *prompt1,
 470                         const char *prompt2, const char *data_name, char **pass )
 471 {
 472     int authtok_flag;
 473     int retval;
 474     char *item = NULL;
 475     char *token;
 476
 477     struct pam_message msg[3], *pmsg[3];
 478     struct pam_response *resp;
 479     int i, expect;
 480
 481
 482     /* make sure nothing inappropriate gets returned */
 483
 484     *pass = token = NULL;
 485
 486     /* which authentication token are we getting? */
 487
 488     authtok_flag = on(SMB__OLD_PASSWD, ctrl) ? PAM_OLDAUTHTOK : PAM_AUTHTOK;
 489
 490     /* should we obtain the password from a PAM item ? */
 491
 492     if (on(SMB_TRY_FIRST_PASS, ctrl) || on(SMB_USE_FIRST_PASS, ctrl)) {
 493         retval = pam_get_item( pamh, authtok_flag, (const void **) &item );
 494         if (retval != PAM_SUCCESS) {
 495             /* very strange. */
 496             _log_err( LOG_ALERT
 497                       , "pam_get_item returned error to smb_read_password" );
 498             return retval;
 499         } else if (item != NULL) {      /* we have a password! */
 500             *pass = item;
 501             item = NULL;
 502             return PAM_SUCCESS;
 503         } else if (on( SMB_USE_FIRST_PASS, ctrl )) {
 504             return PAM_AUTHTOK_RECOVER_ERR;             /* didn't work */
 505         } else if (on( SMB_USE_AUTHTOK, ctrl )
 506                    && off( SMB__OLD_PASSWD, ctrl ))
 507         {
 508             return PAM_AUTHTOK_RECOVER_ERR;
 509         }
 510     }
 511
 512     /*
 513      * getting here implies we will have to get the password from the
 514      * user directly.
 515      */
 516
 517     /* prepare to converse */
 518     if (comment != NULL && off(SMB__QUIET, ctrl)) {
 519         pmsg[0] = &msg[0];
 520         msg[0].msg_style = PAM_TEXT_INFO;
 521         msg[0].msg = comment;
 522         i = 1;
 523     } else {
 524         i = 0;
 525     }
 526
 527     pmsg[i] = &msg[i];
 528     msg[i].msg_style = PAM_PROMPT_ECHO_OFF;
 529     msg[i++].msg = prompt1;
 530
 531     if (prompt2 != NULL) {
 532         pmsg[i] = &msg[i];
 533         msg[i].msg_style = PAM_PROMPT_ECHO_OFF;
 534         msg[i++].msg = prompt2;
 535         expect = 2;
 536     } else
 537         expect = 1;
 538
 539     resp = NULL;
 540
 541     retval = converse( pamh, ctrl, i, pmsg, &resp );
 542
 543     if (resp != NULL) {
 544         int j = comment ? 1 : 0;
 545         /* interpret the response */
 546
 547         if (retval == PAM_SUCCESS) {    /* a good conversation */
 548
 549             token = smbpXstrDup(resp[j++].resp);
 550             if (token != NULL) {
 551                 if (expect == 2) {
 552                     /* verify that password entered correctly */
 553                     if (!resp[j].resp || strcmp( token, resp[j].resp )) {
 554                         _pam_delete( token );
 555                         retval = PAM_AUTHTOK_RECOVER_ERR;
 556                         make_remark( pamh, ctrl, PAM_ERROR_MSG
 557                                      , MISTYPED_PASS );
 558                     }
 559                 }
 560             } else {
 561                 _log_err(LOG_NOTICE, "could not recover authentication token");
 562             }
 563         }
 564
 565         /* tidy up */
 566         _pam_drop_reply( resp, expect );
 567
 568     } else {
 569         retval = (retval == PAM_SUCCESS) ? PAM_AUTHTOK_RECOVER_ERR : retval;
 570     }
 571
 572     if (retval != PAM_SUCCESS) {
 573         if (on( SMB_DEBUG, ctrl ))
 574             _log_err( LOG_DEBUG, "unable to obtain a password" );
 575         return retval;
 576     }
 577     /* 'token' is the entered password */
 578
 579     if (off( SMB_NOT_SET_PASS, ctrl )) {
 580
 581         /* we store this password as an item */
 582
 583         retval = pam_set_item( pamh, authtok_flag, (const void *)token );
 584         _pam_delete( token );           /* clean it up */
 585         if (retval != PAM_SUCCESS
 586             || (retval = pam_get_item( pamh, authtok_flag
 587                             ,(const void **)&item )) != PAM_SUCCESS)
 588         {
 589             _log_err( LOG_CRIT, "error manipulating password" );
 590             return retval;
 591         }
 592     } else {
 593         /*
 594          * then store it as data specific to this module. pam_end()
 595          * will arrange to clean it up.
 596          */
 597
 598         retval = pam_set_data( pamh, data_name, (void *) token, _cleanup );
 599         if (retval != PAM_SUCCESS
 600             || (retval = pam_get_data( pamh, data_name, (const void **)&item ))
 601                              != PAM_SUCCESS)
 602         {
 603             _log_err( LOG_CRIT, "error manipulating password data [%s]"
 604                       , pam_strerror( pamh, retval ));
 605             _pam_delete( token );
 606             item = NULL;
 607             return retval;
 608         }
 609         token = NULL;                   /* break link to password */
 610     }
 611
 612     *pass = item;
 613     item = NULL;                        /* break link to password */
 614
 615     return PAM_SUCCESS;
 616 }
 617
 618 int _pam_smb_approve_pass(pam_handle_t * pamh,
 619                 unsigned int ctrl,
 620                 const char *pass_old,
 621                 const char *pass_new )
 622 {
 623
 624     /* Further checks should be handled through module stacking. -SRL */
 625     if (pass_new == NULL || (pass_old && !strcmp( pass_old, pass_new )))
 626     {
 627         if (on(SMB_DEBUG, ctrl)) {
 628             _log_err( LOG_DEBUG,
 629                       "passwd: bad authentication token (null or unchanged)" );
 630         }
 631         make_remark( pamh, ctrl, PAM_ERROR_MSG, pass_new == NULL ?
 632                                 "No password supplied" : "Password unchanged" );
 633         return PAM_AUTHTOK_ERR;
 634     }
 635
 636     return PAM_SUCCESS;
 637 }