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 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 lm_pw[16];
 312     uchar nt_pw[16];
 313     int retval = PAM_AUTH_ERR;
 314     char *data_name;
 315     const char *name;
 316
 317     if (!sampass)
 318         return PAM_ABORT;
 319
 320     name = pdb_get_username(sampass);
 321
 322 #ifdef HAVE_PAM_FAIL_DELAY
 323     if (off( SMB_NODELAY, ctrl )) {
 324         (void) pam_fail_delay( pamh, 1000000 ); /* 1 sec delay for on failure */
 325     }
 326 #endif
 327
 328     if (!pdb_get_lanman_passwd(sampass))
 329     {
 330         _log_err( LOG_DEBUG, "user %s has null SMB password"
 331                   , name );
 332
 333         if (off( SMB__NONULL, ctrl )
 334             && (pdb_get_acct_ctrl(sampass) & ACB_PWNOTREQ))
 335         { /* this means we've succeeded */
 336             return PAM_SUCCESS;
 337         } else {
 338             const char *service;
 339
 340             pam_get_item( pamh, PAM_SERVICE, (const void **)&service );
 341             _log_err( LOG_NOTICE, "failed auth request by %s for service %s as %s",
 342                       uidtoname(getuid()), service ? service : "**unknown**", name);
 343             return PAM_AUTH_ERR;
 344         }
 345     }
 346
 347     data_name = (char *) malloc( sizeof(FAIL_PREFIX) + strlen( name ));
 348     if (data_name == NULL) {
 349         _log_err( LOG_CRIT, "no memory for data-name" );
 350     }
 351     strncpy( data_name, FAIL_PREFIX, sizeof(FAIL_PREFIX) );
 352     strncpy( data_name + sizeof(FAIL_PREFIX) - 1, name, strlen( name ) + 1 );
 353
 354     /*
 355      * The password we were given wasn't an encrypted password, or it
 356      * didn't match the one we have.  We encrypt the password now and try
 357      * again.
 358      */
 359
 360     nt_lm_owf_gen(p, nt_pw, lm_pw);
 361
 362     /* the moment of truth -- do we agree with the password? */
 363
 364     if (!memcmp( nt_pw, pdb_get_nt_passwd(sampass), 16 )) {
 365
 366         retval = PAM_SUCCESS;
 367         if (data_name) {                /* reset failures */
 368             pam_set_data(pamh, data_name, NULL, _cleanup_failures);
 369         }
 370     } else {
 371
 372         const char *service;
 373
 374         pam_get_item( pamh, PAM_SERVICE, (const void **)&service );
 375
 376         if (data_name != NULL) {
 377             struct _pam_failed_auth *new = NULL;
 378             const struct _pam_failed_auth *old = NULL;
 379
 380             /* get a failure recorder */
 381
 382             new = (struct _pam_failed_auth *)
 383                       malloc( sizeof(struct _pam_failed_auth) );
 384
 385             if (new != NULL) {
 386
 387                 /* any previous failures for this user ? */
 388                 pam_get_data(pamh, data_name, (const void **) &old);
 389
 390                 if (old != NULL) {
 391                     new->count = old->count + 1;
 392                     if (new->count >= SMB_MAX_RETRIES) {
 393                         retval = PAM_MAXTRIES;
 394                     }
 395                 } else {
 396                     _log_err(LOG_NOTICE,
 397                       "failed auth request by %s for service %s as %s",
 398                       uidtoname(getuid()),
 399                       service ? service : "**unknown**", name);
 400                     new->count = 1;
 401                 }
 402                 if (!NT_STATUS_IS_OK(sid_to_uid(pdb_get_user_sid(sampass), &(new->id)))) {
 403                     _log_err(LOG_NOTICE,
 404                       "failed auth request by %s for service %s as %s",
 405                       uidtoname(getuid()),
 406                       service ? service : "**unknown**", name);
 407                 }
 408                 new->user = smbpXstrDup( name );
 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             }
 419         } else {
 420             _log_err(LOG_NOTICE,
 421                       "failed auth request by %s for service %s as %s(%d)",
 422                       uidtoname(getuid()),
 423                       service ? service : "**unknown**", name);
 424             retval = PAM_AUTH_ERR;
 425         }
 426     }
 427
 428     _pam_delete( data_name );
 429
 430     return retval;
 431 }
 432
 433
 434 /*
 435  * _smb_blankpasswd() is a quick check for a blank password
 436  *
 437  * returns TRUE if user does not have a password
 438  * - to avoid prompting for one in such cases (CG)
 439  */
 440
 441 int _smb_blankpasswd( unsigned int ctrl, SAM_ACCOUNT *sampass )
 442 {
 443         int retval;
 444
 445         /*
 446          * This function does not have to be too smart if something goes
 447          * wrong, return FALSE and let this case to be treated somewhere
 448          * else (CG)
 449          */
 450
 451         if (on( SMB__NONULL, ctrl ))
 452                 return 0;               /* will fail but don't let on yet */
 453
 454         if (pdb_get_lanman_passwd(sampass) == NULL)
 455                 retval = 1;
 456         else
 457                 retval = 0;
 458
 459         return retval;
 460 }
 461
 462 /*
 463  * obtain a password from the user
 464  */
 465
 466 int _smb_read_password( pam_handle_t * pamh, unsigned int ctrl,
 467                         const char *comment, const char *prompt1,
 468                         const char *prompt2, const char *data_name, char **pass )
 469 {
 470     int authtok_flag;
 471     int retval;
 472     char *item = NULL;
 473     char *token;
 474
 475     struct pam_message msg[3], *pmsg[3];
 476     struct pam_response *resp;
 477     int i, expect;
 478
 479
 480     /* make sure nothing inappropriate gets returned */
 481
 482     *pass = token = NULL;
 483
 484     /* which authentication token are we getting? */
 485
 486     authtok_flag = on(SMB__OLD_PASSWD, ctrl) ? PAM_OLDAUTHTOK : PAM_AUTHTOK;
 487
 488     /* should we obtain the password from a PAM item ? */
 489
 490     if (on(SMB_TRY_FIRST_PASS, ctrl) || on(SMB_USE_FIRST_PASS, ctrl)) {
 491         retval = pam_get_item( pamh, authtok_flag, (const void **) &item );
 492         if (retval != PAM_SUCCESS) {
 493             /* very strange. */
 494             _log_err( LOG_ALERT
 495                       , "pam_get_item returned error to smb_read_password" );
 496             return retval;
 497         } else if (item != NULL) {      /* we have a password! */
 498             *pass = item;
 499             item = NULL;
 500             return PAM_SUCCESS;
 501         } else if (on( SMB_USE_FIRST_PASS, ctrl )) {
 502             return PAM_AUTHTOK_RECOVER_ERR;             /* didn't work */
 503         } else if (on( SMB_USE_AUTHTOK, ctrl )
 504                    && off( SMB__OLD_PASSWD, ctrl ))
 505         {
 506             return PAM_AUTHTOK_RECOVER_ERR;
 507         }
 508     }
 509
 510     /*
 511      * getting here implies we will have to get the password from the
 512      * user directly.
 513      */
 514
 515     /* prepare to converse */
 516     if (comment != NULL && off(SMB__QUIET, ctrl)) {
 517         pmsg[0] = &msg[0];
 518         msg[0].msg_style = PAM_TEXT_INFO;
 519         msg[0].msg = comment;
 520         i = 1;
 521     } else {
 522         i = 0;
 523     }
 524
 525     pmsg[i] = &msg[i];
 526     msg[i].msg_style = PAM_PROMPT_ECHO_OFF;
 527     msg[i++].msg = prompt1;
 528
 529     if (prompt2 != NULL) {
 530         pmsg[i] = &msg[i];
 531         msg[i].msg_style = PAM_PROMPT_ECHO_OFF;
 532         msg[i++].msg = prompt2;
 533         expect = 2;
 534     } else
 535         expect = 1;
 536
 537     resp = NULL;
 538
 539     retval = converse( pamh, ctrl, i, pmsg, &resp );
 540
 541     if (resp != NULL) {
 542         int j = comment ? 1 : 0;
 543         /* interpret the response */
 544
 545         if (retval == PAM_SUCCESS) {    /* a good conversation */
 546
 547             token = smbpXstrDup(resp[j++].resp);
 548             if (token != NULL) {
 549                 if (expect == 2) {
 550                     /* verify that password entered correctly */
 551                     if (!resp[j].resp || strcmp( token, resp[j].resp )) {
 552                         _pam_delete( token );
 553                         retval = PAM_AUTHTOK_RECOVER_ERR;
 554                         make_remark( pamh, ctrl, PAM_ERROR_MSG
 555                                      , MISTYPED_PASS );
 556                     }
 557                 }
 558             } else {
 559                 _log_err(LOG_NOTICE, "could not recover authentication token");
 560             }
 561         }
 562
 563         /* tidy up */
 564         _pam_drop_reply( resp, expect );
 565
 566     } else {
 567         retval = (retval == PAM_SUCCESS) ? PAM_AUTHTOK_RECOVER_ERR : retval;
 568     }
 569
 570     if (retval != PAM_SUCCESS) {
 571         if (on( SMB_DEBUG, ctrl ))
 572             _log_err( LOG_DEBUG, "unable to obtain a password" );
 573         return retval;
 574     }
 575     /* 'token' is the entered password */
 576
 577     if (off( SMB_NOT_SET_PASS, ctrl )) {
 578
 579         /* we store this password as an item */
 580
 581         retval = pam_set_item( pamh, authtok_flag, (const void *)token );
 582         _pam_delete( token );           /* clean it up */
 583         if (retval != PAM_SUCCESS
 584             || (retval = pam_get_item( pamh, authtok_flag
 585                             ,(const void **)&item )) != PAM_SUCCESS)
 586         {
 587             _log_err( LOG_CRIT, "error manipulating password" );
 588             return retval;
 589         }
 590     } else {
 591         /*
 592          * then store it as data specific to this module. pam_end()
 593          * will arrange to clean it up.
 594          */
 595
 596         retval = pam_set_data( pamh, data_name, (void *) token, _cleanup );
 597         if (retval != PAM_SUCCESS
 598             || (retval = pam_get_data( pamh, data_name, (const void **)&item ))
 599                              != PAM_SUCCESS)
 600         {
 601             _log_err( LOG_CRIT, "error manipulating password data [%s]"
 602                       , pam_strerror( pamh, retval ));
 603             _pam_delete( token );
 604             item = NULL;
 605             return retval;
 606         }
 607         token = NULL;                   /* break link to password */
 608     }
 609
 610     *pass = item;
 611     item = NULL;                        /* break link to password */
 612
 613     return PAM_SUCCESS;
 614 }
 615
 616 int _pam_smb_approve_pass(pam_handle_t * pamh,
 617                 unsigned int ctrl,
 618                 const char *pass_old,
 619                 const char *pass_new )
 620 {
 621
 622     /* Further checks should be handled through module stacking. -SRL */
 623     if (pass_new == NULL || (pass_old && !strcmp( pass_old, pass_new )))
 624     {
 625         if (on(SMB_DEBUG, ctrl)) {
 626             _log_err( LOG_DEBUG,
 627                       "passwd: bad authentication token (null or unchanged)" );
 628         }
 629         make_remark( pamh, ctrl, PAM_ERROR_MSG, pass_new == NULL ?
 630                                 "No password supplied" : "Password unchanged" );
 631         return PAM_AUTHTOK_ERR;
 632     }
 633
 634     return PAM_SUCCESS;
 635 }