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_nt_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         return PAM_AUTH_ERR;
 346     }
 347     strncpy( data_name, FAIL_PREFIX, sizeof(FAIL_PREFIX) );
 348     strncpy( data_name + sizeof(FAIL_PREFIX) - 1, name, strlen( name ) + 1 );
 349
 350     /*
 351      * The password we were given wasn't an encrypted password, or it
 352      * didn't match the one we have.  We encrypt the password now and try
 353      * again.
 354      */
 355
 356     nt_lm_owf_gen(p, nt_pw, lm_pw);
 357
 358     /* the moment of truth -- do we agree with the password? */
 359
 360     if (!memcmp( nt_pw, pdb_get_nt_passwd(sampass), 16 )) {
 361
 362         retval = PAM_SUCCESS;
 363         if (data_name) {                /* reset failures */
 364             pam_set_data(pamh, data_name, NULL, _cleanup_failures);
 365         }
 366     } else {
 367
 368         const char *service;
 369
 370         pam_get_item( pamh, PAM_SERVICE, (const void **)&service );
 371
 372         if (data_name != NULL) {
 373             struct _pam_failed_auth *newauth = NULL;
 374             const struct _pam_failed_auth *old = NULL;
 375
 376             /* get a failure recorder */
 377
 378             newauth = SMB_MALLOC_P( struct _pam_failed_auth );
 379
 380             if (newauth != NULL) {
 381
 382                 /* any previous failures for this user ? */
 383                 pam_get_data(pamh, data_name, (const void **) &old);
 384
 385                 if (old != NULL) {
 386                     newauth->count = old->count + 1;
 387                     if (newauth->count >= SMB_MAX_RETRIES) {
 388                         retval = PAM_MAXTRIES;
 389                     }
 390                 } else {
 391                     _log_err(LOG_NOTICE,
 392                       "failed auth request by %s for service %s as %s",
 393                       uidtoname(getuid()),
 394                       service ? service : "**unknown**", name);
 395                     newauth->count = 1;
 396                 }
 397                 if (!sid_to_uid(pdb_get_user_sid(sampass), &(newauth->id))) {
 398                     _log_err(LOG_NOTICE,
 399                       "failed auth request by %s for service %s as %s",
 400                       uidtoname(getuid()),
 401                       service ? service : "**unknown**", name);
 402                 }
 403                 newauth->user = smbpXstrDup( name );
 404                 newauth->agent = smbpXstrDup( uidtoname( getuid() ) );
 405                 pam_set_data( pamh, data_name, newauth, _cleanup_failures );
 406
 407             } else {
 408                 _log_err( LOG_CRIT, "no memory for failure recorder" );
 409                 _log_err(LOG_NOTICE,
 410                       "failed auth request by %s for service %s as %s(%d)",
 411                       uidtoname(getuid()),
 412                       service ? service : "**unknown**", name);
 413             }
 414         }
 415         _log_err(LOG_NOTICE,
 416                   "failed auth request by %s for service %s as %s(%d)",
 417                   uidtoname(getuid()),
 418                   service ? service : "**unknown**", name);
 419         retval = PAM_AUTH_ERR;
 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_acct_ctrl(sampass) & ACB_PWNOTREQ))
 449                 return 0;
 450
 451         if (pdb_get_nt_passwd(sampass) == NULL)
 452                 retval = 1;
 453         else
 454                 retval = 0;
 455
 456         return retval;
 457 }
 458
 459 /*
 460  * obtain a password from the user
 461  */
 462
 463 int _smb_read_password( pam_handle_t * pamh, unsigned int ctrl,
 464                         const char *comment, const char *prompt1,
 465                         const char *prompt2, const char *data_name, char **pass )
 466 {
 467     int authtok_flag;
 468     int retval;
 469     char *item = NULL;
 470     char *token;
 471
 472     struct pam_message msg[3], *pmsg[3];
 473     struct pam_response *resp;
 474     int i, expect;
 475
 476
 477     /* make sure nothing inappropriate gets returned */
 478
 479     *pass = token = NULL;
 480
 481     /* which authentication token are we getting? */
 482
 483     authtok_flag = on(SMB__OLD_PASSWD, ctrl) ? PAM_OLDAUTHTOK : PAM_AUTHTOK;
 484
 485     /* should we obtain the password from a PAM item ? */
 486
 487     if (on(SMB_TRY_FIRST_PASS, ctrl) || on(SMB_USE_FIRST_PASS, ctrl)) {
 488         retval = pam_get_item( pamh, authtok_flag, (const void **) &item );
 489         if (retval != PAM_SUCCESS) {
 490             /* very strange. */
 491             _log_err( LOG_ALERT
 492                       , "pam_get_item returned error to smb_read_password" );
 493             return retval;
 494         } else if (item != NULL) {      /* we have a password! */
 495             *pass = item;
 496             item = NULL;
 497             return PAM_SUCCESS;
 498         } else if (on( SMB_USE_FIRST_PASS, ctrl )) {
 499             return PAM_AUTHTOK_RECOVER_ERR;             /* didn't work */
 500         } else if (on( SMB_USE_AUTHTOK, ctrl )
 501                    && off( SMB__OLD_PASSWD, ctrl ))
 502         {
 503             return PAM_AUTHTOK_RECOVER_ERR;
 504         }
 505     }
 506
 507     /*
 508      * getting here implies we will have to get the password from the
 509      * user directly.
 510      */
 511
 512     /* prepare to converse */
 513     if (comment != NULL && off(SMB__QUIET, ctrl)) {
 514         pmsg[0] = &msg[0];
 515         msg[0].msg_style = PAM_TEXT_INFO;
 516         msg[0].msg = CONST_DISCARD(char *, comment);
 517         i = 1;
 518     } else {
 519         i = 0;
 520     }
 521
 522     pmsg[i] = &msg[i];
 523     msg[i].msg_style = PAM_PROMPT_ECHO_OFF;
 524     msg[i++].msg = CONST_DISCARD(char *, prompt1);
 525
 526     if (prompt2 != NULL) {
 527         pmsg[i] = &msg[i];
 528         msg[i].msg_style = PAM_PROMPT_ECHO_OFF;
 529         msg[i++].msg = CONST_DISCARD(char *, prompt2);
 530         expect = 2;
 531     } else
 532         expect = 1;
 533
 534     resp = NULL;
 535
 536     retval = converse( pamh, ctrl, i, pmsg, &resp );
 537
 538     if (resp != NULL) {
 539         int j = comment ? 1 : 0;
 540         /* interpret the response */
 541
 542         if (retval == PAM_SUCCESS) {    /* a good conversation */
 543
 544             token = smbpXstrDup(resp[j++].resp);
 545             if (token != NULL) {
 546                 if (expect == 2) {
 547                     /* verify that password entered correctly */
 548                     if (!resp[j].resp || strcmp( token, resp[j].resp )) {
 549                         _pam_delete( token );
 550                         retval = PAM_AUTHTOK_RECOVER_ERR;
 551                         make_remark( pamh, ctrl, PAM_ERROR_MSG
 552                                      , MISTYPED_PASS );
 553                     }
 554                 }
 555             } else {
 556                 _log_err(LOG_NOTICE, "could not recover authentication token");
 557             }
 558         }
 559
 560         /* tidy up */
 561         _pam_drop_reply( resp, expect );
 562
 563     } else {
 564         retval = (retval == PAM_SUCCESS) ? PAM_AUTHTOK_RECOVER_ERR : retval;
 565     }
 566
 567     if (retval != PAM_SUCCESS) {
 568         if (on( SMB_DEBUG, ctrl ))
 569             _log_err( LOG_DEBUG, "unable to obtain a password" );
 570         return retval;
 571     }
 572     /* 'token' is the entered password */
 573
 574     if (off( SMB_NOT_SET_PASS, ctrl )) {
 575
 576         /* we store this password as an item */
 577
 578         retval = pam_set_item( pamh, authtok_flag, (const void *)token );
 579         _pam_delete( token );           /* clean it up */
 580         if (retval != PAM_SUCCESS
 581             || (retval = pam_get_item( pamh, authtok_flag
 582                             ,(const void **)&item )) != PAM_SUCCESS)
 583         {
 584             _log_err( LOG_CRIT, "error manipulating password" );
 585             return retval;
 586         }
 587     } else {
 588         /*
 589          * then store it as data specific to this module. pam_end()
 590          * will arrange to clean it up.
 591          */
 592
 593         retval = pam_set_data( pamh, data_name, (void *) token, _cleanup );
 594         if (retval != PAM_SUCCESS
 595             || (retval = pam_get_data( pamh, data_name, (const void **)&item ))
 596                              != PAM_SUCCESS)
 597         {
 598             _log_err( LOG_CRIT, "error manipulating password data [%s]"
 599                       , pam_strerror( pamh, retval ));
 600             _pam_delete( token );
 601             item = NULL;
 602             return retval;
 603         }
 604         token = NULL;                   /* break link to password */
 605     }
 606
 607     *pass = item;
 608     item = NULL;                        /* break link to password */
 609
 610     return PAM_SUCCESS;
 611 }
 612
 613 int _pam_smb_approve_pass(pam_handle_t * pamh,
 614                 unsigned int ctrl,
 615                 const char *pass_old,
 616                 const char *pass_new )
 617 {
 618
 619     /* Further checks should be handled through module stacking. -SRL */
 620     if (pass_new == NULL || (pass_old && !strcmp( pass_old, pass_new )))
 621     {
 622         if (on(SMB_DEBUG, ctrl)) {
 623             _log_err( LOG_DEBUG,
 624                       "passwd: bad authentication token (null or unchanged)" );
 625         }
 626         make_remark( pamh, ctrl, PAM_ERROR_MSG, pass_new == NULL ?
 627                                 "No password supplied" : "Password unchanged" );
 628         return PAM_AUTHTOK_ERR;
 629     }
 630
 631     return PAM_SUCCESS;
 632 }