source3/smbd/password.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Password and authentication handling
   4    Copyright (C) Andrew Tridgell 1992-1998
   5    Copyright (C) Jeremy Allison 2007.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "includes.h"
  22
  23 /* users from session setup */
  24 static char *session_userlist = NULL;
  25 /* workgroup from session setup. */
  26 static char *session_workgroup = NULL;
  27
  28 /* this holds info on user ids that are already validated for this VC */
  29 static user_struct *validated_users;
  30 static uint16_t next_vuid = VUID_OFFSET;
  31 static int num_validated_vuids;
  32
  33 enum server_allocated_state { SERVER_ALLOCATED_REQUIRED_YES,
  34                                 SERVER_ALLOCATED_REQUIRED_NO,
  35                                 SERVER_ALLOCATED_REQUIRED_ANY};
  36
  37 static user_struct *get_valid_user_struct_internal(uint16 vuid,
  38                         enum server_allocated_state server_allocated)
  39 {
  40         user_struct *usp;
  41         int count=0;
  42
  43         if (vuid == UID_FIELD_INVALID)
  44                 return NULL;
  45
  46         for (usp=validated_users;usp;usp=usp->next,count++) {
  47                 if (vuid == usp->vuid) {
  48                         switch (server_allocated) {
  49                                 case SERVER_ALLOCATED_REQUIRED_YES:
  50                                         if (usp->server_info == NULL) {
  51                                                 continue;
  52                                         }
  53                                         break;
  54                                 case SERVER_ALLOCATED_REQUIRED_NO:
  55                                         if (usp->server_info != NULL) {
  56                                                 continue;
  57                                         }
  58                                 case SERVER_ALLOCATED_REQUIRED_ANY:
  59                                         break;
  60                         }
  61                         if (count > 10) {
  62                                 DLIST_PROMOTE(validated_users, usp);
  63                         }
  64                         return usp;
  65                 }
  66         }
  67
  68         return NULL;
  69 }
  70
  71 /****************************************************************************
  72  Check if a uid has been validated, and return an pointer to the user_struct
  73  if it has. NULL if not. vuid is biased by an offset. This allows us to
  74  tell random client vuid's (normally zero) from valid vuids.
  75 ****************************************************************************/
  76
  77 user_struct *get_valid_user_struct(uint16 vuid)
  78 {
  79         return get_valid_user_struct_internal(vuid,
  80                         SERVER_ALLOCATED_REQUIRED_YES);
  81 }
  82
  83 bool is_partial_auth_vuid(uint16 vuid)
  84 {
  85         return (get_partial_auth_user_struct(vuid) != NULL);
  86 }
  87
  88 /****************************************************************************
  89  Get the user struct of a partial NTLMSSP login
  90 ****************************************************************************/
  91
  92 user_struct *get_partial_auth_user_struct(uint16 vuid)
  93 {
  94         return get_valid_user_struct_internal(vuid,
  95                         SERVER_ALLOCATED_REQUIRED_NO);
  96 }
  97
  98 /****************************************************************************
  99  Invalidate a uid.
 100 ****************************************************************************/
 101
 102 void invalidate_vuid(uint16 vuid)
 103 {
 104         user_struct *vuser = NULL;
 105
 106         vuser = get_valid_user_struct_internal(vuid,
 107                         SERVER_ALLOCATED_REQUIRED_ANY);
 108         if (vuser == NULL) {
 109                 return;
 110         }
 111
 112         session_yield(vuser);
 113
 114         if (vuser->auth_ntlmssp_state) {
 115                 auth_ntlmssp_end(&vuser->auth_ntlmssp_state);
 116         }
 117
 118         DLIST_REMOVE(validated_users, vuser);
 119
 120         /* clear the vuid from the 'cache' on each connection, and
 121            from the vuid 'owner' of connections */
 122         conn_clear_vuid_caches(vuid);
 123
 124         TALLOC_FREE(vuser);
 125         num_validated_vuids--;
 126 }
 127
 128 /****************************************************************************
 129  Invalidate all vuid entries for this process.
 130 ****************************************************************************/
 131
 132 void invalidate_all_vuids(void)
 133 {
 134         while (validated_users != NULL) {
 135                 invalidate_vuid(validated_users->vuid);
 136         }
 137 }
 138
 139 static void increment_next_vuid(uint16_t *vuid)
 140 {
 141         *vuid += 1;
 142
 143         /* Check for vuid wrap. */
 144         if (*vuid == UID_FIELD_INVALID) {
 145                 *vuid = VUID_OFFSET;
 146         }
 147 }
 148
 149 /****************************************************
 150  Create a new partial auth user struct.
 151 *****************************************************/
 152
 153 int register_initial_vuid(void)
 154 {
 155         user_struct *vuser;
 156
 157         /* Paranoia check. */
 158         if(lp_security() == SEC_SHARE) {
 159                 smb_panic("register_initial_vuid: "
 160                         "Tried to register uid in security=share");
 161         }
 162
 163         /* Limit allowed vuids to 16bits - VUID_OFFSET. */
 164         if (num_validated_vuids >= 0xFFFF-VUID_OFFSET) {
 165                 return UID_FIELD_INVALID;
 166         }
 167
 168         if((vuser = talloc_zero(NULL, user_struct)) == NULL) {
 169                 DEBUG(0,("register_initial_vuid: "
 170                                 "Failed to talloc users struct!\n"));
 171                 return UID_FIELD_INVALID;
 172         }
 173
 174         /* Allocate a free vuid. Yes this is a linear search... */
 175         while( get_valid_user_struct_internal(next_vuid,
 176                         SERVER_ALLOCATED_REQUIRED_ANY) != NULL ) {
 177                 increment_next_vuid(&next_vuid);
 178         }
 179
 180         DEBUG(10,("register_initial_vuid: allocated vuid = %u\n",
 181                 (unsigned int)next_vuid ));
 182
 183         vuser->vuid = next_vuid;
 184
 185         /*
 186          * This happens in an unfinished NTLMSSP session setup. We
 187          * need to allocate a vuid between the first and second calls
 188          * to NTLMSSP.
 189          */
 190         increment_next_vuid(&next_vuid);
 191         num_validated_vuids++;
 192
 193         DLIST_ADD(validated_users, vuser);
 194         return vuser->vuid;
 195 }
 196
 197 static int register_homes_share(const char *username)
 198 {
 199         int result;
 200         struct passwd *pwd;
 201
 202         result = lp_servicenumber(username);
 203         if (result != -1) {
 204                 DEBUG(3, ("Using static (or previously created) service for "
 205                           "user '%s'; path = '%s'\n", username,
 206                           lp_pathname(result)));
 207                 return result;
 208         }
 209
 210         pwd = getpwnam_alloc(talloc_tos(), username);
 211
 212         if ((pwd == NULL) || (pwd->pw_dir[0] == '\0')) {
 213                 DEBUG(3, ("No home directory defined for user '%s'\n",
 214                           username));
 215                 TALLOC_FREE(pwd);
 216                 return -1;
 217         }
 218
 219         DEBUG(3, ("Adding homes service for user '%s' using home directory: "
 220                   "'%s'\n", username, pwd->pw_dir));
 221
 222         result = add_home_service(username, username, pwd->pw_dir);
 223
 224         TALLOC_FREE(pwd);
 225         return result;
 226 }
 227
 228 /**
 229  *  register that a valid login has been performed, establish 'session'.
 230  *  @param server_info The token returned from the authentication process.
 231  *   (now 'owned' by register_existing_vuid)
 232  *
 233  *  @param session_key The User session key for the login session (now also
 234  *  'owned' by register_existing_vuid)
 235  *
 236  *  @param respose_blob The NT challenge-response, if available.  (May be
 237  *  freed after this call)
 238  *
 239  *  @param smb_name The untranslated name of the user
 240  *
 241  *  @return Newly allocated vuid, biased by an offset. (This allows us to
 242  *   tell random client vuid's (normally zero) from valid vuids.)
 243  *
 244  */
 245
 246 int register_existing_vuid(uint16 vuid,
 247                         auth_serversupplied_info *server_info,
 248                         DATA_BLOB response_blob,
 249                         const char *smb_name)
 250 {
 251         fstring tmp;
 252         user_struct *vuser;
 253
 254         vuser = get_partial_auth_user_struct(vuid);
 255         if (!vuser) {
 256                 goto fail;
 257         }
 258
 259         /* Use this to keep tabs on all our info from the authentication */
 260         vuser->server_info = talloc_move(vuser, &server_info);
 261
 262         /* This is a potentially untrusted username */
 263         alpha_strcpy(tmp, smb_name, ". _-$", sizeof(tmp));
 264
 265         vuser->server_info->sanitized_username = talloc_strdup(
 266                 vuser->server_info, tmp);
 267
 268         DEBUG(10,("register_existing_vuid: (%u,%u) %s %s %s guest=%d\n",
 269                   (unsigned int)vuser->server_info->utok.uid,
 270                   (unsigned int)vuser->server_info->utok.gid,
 271                   vuser->server_info->unix_name,
 272                   vuser->server_info->sanitized_username,
 273                   pdb_get_domain(vuser->server_info->sam_account),
 274                   vuser->server_info->guest ));
 275
 276         DEBUG(3, ("register_existing_vuid: User name: %s\t"
 277                   "Real name: %s\n", vuser->server_info->unix_name,
 278                   pdb_get_fullname(vuser->server_info->sam_account)));
 279
 280         if (!vuser->server_info->ptok) {
 281                 DEBUG(1, ("register_existing_vuid: server_info does not "
 282                         "contain a user_token - cannot continue\n"));
 283                 goto fail;
 284         }
 285
 286         DEBUG(3,("register_existing_vuid: UNIX uid %d is UNIX user %s, "
 287                 "and will be vuid %u\n", (int)vuser->server_info->utok.uid,
 288                  vuser->server_info->unix_name, vuser->vuid));
 289
 290         if (!session_claim(vuser)) {
 291                 DEBUG(1, ("register_existing_vuid: Failed to claim session "
 292                         "for vuid=%d\n",
 293                         vuser->vuid));
 294                 goto fail;
 295         }
 296
 297         /* Register a home dir service for this user if
 298         (a) This is not a guest connection,
 299         (b) we have a home directory defined
 300         (c) there s not an existing static share by that name
 301         If a share exists by this name (autoloaded or not) reuse it . */
 302
 303         vuser->homes_snum = -1;
 304
 305         if (!vuser->server_info->guest) {
 306                 vuser->homes_snum = register_homes_share(
 307                         vuser->server_info->unix_name);
 308         }
 309
 310         if (srv_is_signing_negotiated() && !vuser->server_info->guest &&
 311                         !srv_signing_started()) {
 312                 /* Try and turn on server signing on the first non-guest
 313                  * sessionsetup. */
 314                 srv_set_signing(vuser->server_info->user_session_key, response_blob);
 315         }
 316
 317         /* fill in the current_user_info struct */
 318         set_current_user_info(
 319                 vuser->server_info->sanitized_username,
 320                 vuser->server_info->unix_name,
 321                 pdb_get_fullname(vuser->server_info->sam_account),
 322                 pdb_get_domain(vuser->server_info->sam_account));
 323
 324         return vuser->vuid;
 325
 326   fail:
 327
 328         if (vuser) {
 329                 invalidate_vuid(vuid);
 330         }
 331         return UID_FIELD_INVALID;
 332 }
 333
 334 /****************************************************************************
 335  Add a name to the session users list.
 336 ****************************************************************************/
 337
 338 void add_session_user(const char *user)
 339 {
 340         struct passwd *pw;
 341         char *tmp;
 342
 343         pw = Get_Pwnam_alloc(talloc_tos(), user);
 344
 345         if (pw == NULL) {
 346                 return;
 347         }
 348
 349         if (session_userlist == NULL) {
 350                 session_userlist = SMB_STRDUP(pw->pw_name);
 351                 goto done;
 352         }
 353
 354         if (in_list(pw->pw_name,session_userlist,False) ) {
 355                 goto done;
 356         }
 357
 358         if (strlen(session_userlist) > 128 * 1024) {
 359                 DEBUG(3,("add_session_user: session userlist already "
 360                          "too large.\n"));
 361                 goto done;
 362         }
 363
 364         if (asprintf(&tmp, "%s %s", session_userlist, pw->pw_name) == -1) {
 365                 DEBUG(3, ("asprintf failed\n"));
 366                 goto done;
 367         }
 368
 369         SAFE_FREE(session_userlist);
 370         session_userlist = tmp;
 371  done:
 372         TALLOC_FREE(pw);
 373 }
 374
 375 /****************************************************************************
 376  In security=share mode we need to store the client workgroup, as that's
 377   what Vista uses for the NTLMv2 calculation.
 378 ****************************************************************************/
 379
 380 void add_session_workgroup(const char *workgroup)
 381 {
 382         if (session_workgroup) {
 383                 SAFE_FREE(session_workgroup);
 384         }
 385         session_workgroup = smb_xstrdup(workgroup);
 386 }
 387
 388 /****************************************************************************
 389  In security=share mode we need to return the client workgroup, as that's
 390   what Vista uses for the NTLMv2 calculation.
 391 ****************************************************************************/
 392
 393 const char *get_session_workgroup(void)
 394 {
 395         return session_workgroup;
 396 }
 397
 398 /****************************************************************************
 399  Check if a user is in a netgroup user list. If at first we don't succeed,
 400  try lower case.
 401 ****************************************************************************/
 402
 403 bool user_in_netgroup(const char *user, const char *ngname)
 404 {
 405 #ifdef HAVE_NETGROUP
 406         static char *mydomain = NULL;
 407         fstring lowercase_user;
 408
 409         if (mydomain == NULL)
 410                 yp_get_default_domain(&mydomain);
 411
 412         if(mydomain == NULL) {
 413                 DEBUG(5,("Unable to get default yp domain, "
 414                         "let's try without specifying it\n"));
 415         }
 416
 417         DEBUG(5,("looking for user %s of domain %s in netgroup %s\n",
 418                 user, mydomain?mydomain:"(ANY)", ngname));
 419
 420         if (innetgr(ngname, NULL, user, mydomain)) {
 421                 DEBUG(5,("user_in_netgroup: Found\n"));
 422                 return (True);
 423         } else {
 424
 425                 /*
 426                  * Ok, innetgr is case sensitive. Try once more with lowercase
 427                  * just in case. Attempt to fix #703. JRA.
 428                  */
 429
 430                 fstrcpy(lowercase_user, user);
 431                 strlower_m(lowercase_user);
 432
 433                 DEBUG(5,("looking for user %s of domain %s in netgroup %s\n",
 434                         lowercase_user, mydomain?mydomain:"(ANY)", ngname));
 435
 436                 if (innetgr(ngname, NULL, lowercase_user, mydomain)) {
 437                         DEBUG(5,("user_in_netgroup: Found\n"));
 438                         return (True);
 439                 }
 440         }
 441 #endif /* HAVE_NETGROUP */
 442         return False;
 443 }
 444
 445 /****************************************************************************
 446  Check if a user is in a user list - can check combinations of UNIX
 447  and netgroup lists.
 448 ****************************************************************************/
 449
 450 bool user_in_list(const char *user,const char **list)
 451 {
 452         if (!list || !*list)
 453                 return False;
 454
 455         DEBUG(10,("user_in_list: checking user %s in list\n", user));
 456
 457         while (*list) {
 458
 459                 DEBUG(10,("user_in_list: checking user |%s| against |%s|\n",
 460                           user, *list));
 461
 462                 /*
 463                  * Check raw username.
 464                  */
 465                 if (strequal(user, *list))
 466                         return(True);
 467
 468                 /*
 469                  * Now check to see if any combination
 470                  * of UNIX and netgroups has been specified.
 471                  */
 472
 473                 if(**list == '@') {
 474                         /*
 475                          * Old behaviour. Check netgroup list
 476                          * followed by UNIX list.
 477                          */
 478                         if(user_in_netgroup(user, *list +1))
 479                                 return True;
 480                         if(user_in_group(user, *list +1))
 481                                 return True;
 482                 } else if (**list == '+') {
 483
 484                         if((*(*list +1)) == '&') {
 485                                 /*
 486                                  * Search UNIX list followed by netgroup.
 487                                  */
 488                                 if(user_in_group(user, *list +2))
 489                                         return True;
 490                                 if(user_in_netgroup(user, *list +2))
 491                                         return True;
 492
 493                         } else {
 494
 495                                 /*
 496                                  * Just search UNIX list.
 497                                  */
 498
 499                                 if(user_in_group(user, *list +1))
 500                                         return True;
 501                         }
 502
 503                 } else if (**list == '&') {
 504
 505                         if(*(*list +1) == '+') {
 506                                 /*
 507                                  * Search netgroup list followed by UNIX list.
 508                                  */
 509                                 if(user_in_netgroup(user, *list +2))
 510                                         return True;
 511                                 if(user_in_group(user, *list +2))
 512                                         return True;
 513                         } else {
 514                                 /*
 515                                  * Just search netgroup list.
 516                                  */
 517                                 if(user_in_netgroup(user, *list +1))
 518                                         return True;
 519                         }
 520                 }
 521
 522                 list++;
 523         }
 524         return(False);
 525 }
 526
 527 /****************************************************************************
 528  Check if a username is valid.
 529 ****************************************************************************/
 530
 531 static bool user_ok(const char *user, int snum)
 532 {
 533         char **valid, **invalid;
 534         bool ret;
 535
 536         valid = invalid = NULL;
 537         ret = True;
 538
 539         if (lp_invalid_users(snum)) {
 540                 invalid = str_list_copy(talloc_tos(), lp_invalid_users(snum));
 541                 if (invalid &&
 542                     str_list_substitute(invalid, "%S", lp_servicename(snum))) {
 543
 544                         /* This is used in sec=share only, so no current user
 545                          * around to pass to str_list_sub_basic() */
 546
 547                         if ( invalid && str_list_sub_basic(invalid, "", "") ) {
 548                                 ret = !user_in_list(user,
 549                                                     (const char **)invalid);
 550                         }
 551                 }
 552         }
 553         TALLOC_FREE(invalid);
 554
 555         if (ret && lp_valid_users(snum)) {
 556                 valid = str_list_copy(talloc_tos(), lp_valid_users(snum));
 557                 if ( valid &&
 558                      str_list_substitute(valid, "%S", lp_servicename(snum)) ) {
 559
 560                         /* This is used in sec=share only, so no current user
 561                          * around to pass to str_list_sub_basic() */
 562
 563                         if ( valid && str_list_sub_basic(valid, "", "") ) {
 564                                 ret = user_in_list(user, (const char **)valid);
 565                         }
 566                 }
 567         }
 568         TALLOC_FREE(valid);
 569
 570         if (ret && lp_onlyuser(snum)) {
 571                 char **user_list = str_list_make_v3(
 572                         talloc_tos(), lp_username(snum), NULL);
 573                 if (user_list &&
 574                     str_list_substitute(user_list, "%S",
 575                                         lp_servicename(snum))) {
 576                         ret = user_in_list(user, (const char **)user_list);
 577                 }
 578                 TALLOC_FREE(user_list);
 579         }
 580
 581         return(ret);
 582 }
 583
 584 /****************************************************************************
 585  Validate a group username entry. Return the username or NULL.
 586 ****************************************************************************/
 587
 588 static char *validate_group(char *group, DATA_BLOB password,int snum)
 589 {
 590 #ifdef HAVE_NETGROUP
 591         {
 592                 char *host, *user, *domain;
 593                 setnetgrent(group);
 594                 while (getnetgrent(&host, &user, &domain)) {
 595                         if (user) {
 596                                 if (user_ok(user, snum) &&
 597                                     password_ok(user,password)) {
 598                                         endnetgrent();
 599                                         return(user);
 600                                 }
 601                         }
 602                 }
 603                 endnetgrent();
 604         }
 605 #endif
 606
 607 #ifdef HAVE_GETGRENT
 608         {
 609                 struct group *gptr;
 610                 setgrent();
 611                 while ((gptr = (struct group *)getgrent())) {
 612                         if (strequal(gptr->gr_name,group))
 613                                 break;
 614                 }
 615
 616                 /*
 617                  * As user_ok can recurse doing a getgrent(), we must
 618                  * copy the member list onto the heap before
 619                  * use. Bug pointed out by leon@eatworms.swmed.edu.
 620                  */
 621
 622                 if (gptr) {
 623                         char *member_list = NULL;
 624                         size_t list_len = 0;
 625                         char *member;
 626                         int i;
 627
 628                         for(i = 0; gptr->gr_mem && gptr->gr_mem[i]; i++) {
 629                                 list_len += strlen(gptr->gr_mem[i])+1;
 630                         }
 631                         list_len++;
 632
 633                         member_list = (char *)SMB_MALLOC(list_len);
 634                         if (!member_list) {
 635                                 endgrent();
 636                                 return NULL;
 637                         }
 638
 639                         *member_list = '\0';
 640                         member = member_list;
 641
 642                         for(i = 0; gptr->gr_mem && gptr->gr_mem[i]; i++) {
 643                                 size_t member_len = strlen(gptr->gr_mem[i])+1;
 644
 645                                 DEBUG(10,("validate_group: = gr_mem = "
 646                                           "%s\n", gptr->gr_mem[i]));
 647
 648                                 safe_strcpy(member, gptr->gr_mem[i],
 649                                         list_len - (member-member_list));
 650                                 member += member_len;
 651                         }
 652
 653                         endgrent();
 654
 655                         member = member_list;
 656                         while (*member) {
 657                                 if (user_ok(member,snum) &&
 658                                     password_ok(member,password)) {
 659                                         char *name = talloc_strdup(talloc_tos(),
 660                                                                 member);
 661                                         SAFE_FREE(member_list);
 662                                         return name;
 663                                 }
 664
 665                                 DEBUG(10,("validate_group = member = %s\n",
 666                                           member));
 667
 668                                 member += strlen(member) + 1;
 669                         }
 670
 671                         SAFE_FREE(member_list);
 672                 } else {
 673                         endgrent();
 674                         return NULL;
 675                 }
 676         }
 677 #endif
 678         return(NULL);
 679 }
 680
 681 /****************************************************************************
 682  Check for authority to login to a service with a given username/password.
 683  Note this is *NOT* used when logging on using sessionsetup_and_X.
 684 ****************************************************************************/
 685
 686 bool authorise_login(int snum, fstring user, DATA_BLOB password,
 687                      bool *guest)
 688 {
 689         bool ok = False;
 690
 691 #ifdef DEBUG_PASSWORD
 692         DEBUG(100,("authorise_login: checking authorisation on "
 693                    "user=%s pass=%s\n", user,password.data));
 694 #endif
 695
 696         *guest = False;
 697
 698         /* there are several possibilities:
 699                 1) login as the given user with given password
 700                 2) login as a previously registered username with the given
 701                    password
 702                 3) login as a session list username with the given password
 703                 4) login as a previously validated user/password pair
 704                 5) login as the "user =" user with given password
 705                 6) login as the "user =" user with no password
 706                    (guest connection)
 707                 7) login as guest user with no password
 708
 709                 if the service is guest_only then steps 1 to 5 are skipped
 710         */
 711
 712         /* now check the list of session users */
 713         if (!ok) {
 714                 char *auser;
 715                 char *user_list = NULL;
 716                 char *saveptr;
 717
 718                 if ( session_userlist )
 719                         user_list = SMB_STRDUP(session_userlist);
 720                 else
 721                         user_list = SMB_STRDUP("");
 722
 723                 if (!user_list)
 724                         return(False);
 725
 726                 for (auser = strtok_r(user_list, LIST_SEP, &saveptr);
 727                      !ok && auser;
 728                      auser = strtok_r(NULL, LIST_SEP, &saveptr)) {
 729                         fstring user2;
 730                         fstrcpy(user2,auser);
 731                         if (!user_ok(user2,snum))
 732                                 continue;
 733
 734                         if (password_ok(user2,password)) {
 735                                 ok = True;
 736                                 fstrcpy(user,user2);
 737                                 DEBUG(3,("authorise_login: ACCEPTED: session "
 738                                          "list username (%s) and given "
 739                                          "password ok\n", user));
 740                         }
 741                 }
 742
 743                 SAFE_FREE(user_list);
 744         }
 745
 746         /* check the user= fields and the given password */
 747         if (!ok && lp_username(snum)) {
 748                 TALLOC_CTX *ctx = talloc_tos();
 749                 char *auser;
 750                 char *user_list = talloc_strdup(ctx, lp_username(snum));
 751                 char *saveptr;
 752
 753                 if (!user_list) {
 754                         goto check_guest;
 755                 }
 756
 757                 user_list = talloc_string_sub(ctx,
 758                                 user_list,
 759                                 "%S",
 760                                 lp_servicename(snum));
 761
 762                 if (!user_list) {
 763                         goto check_guest;
 764                 }
 765
 766                 for (auser = strtok_r(user_list, LIST_SEP, &saveptr);
 767                      auser && !ok;
 768                      auser = strtok_r(NULL, LIST_SEP, &saveptr)) {
 769                         if (*auser == '@') {
 770                                 auser = validate_group(auser+1,password,snum);
 771                                 if (auser) {
 772                                         ok = True;
 773                                         fstrcpy(user,auser);
 774                                         DEBUG(3,("authorise_login: ACCEPTED: "
 775                                                  "group username and given "
 776                                                  "password ok (%s)\n", user));
 777                                 }
 778                         } else {
 779                                 fstring user2;
 780                                 fstrcpy(user2,auser);
 781                                 if (user_ok(user2,snum) &&
 782                                     password_ok(user2,password)) {
 783                                         ok = True;
 784                                         fstrcpy(user,user2);
 785                                         DEBUG(3,("authorise_login: ACCEPTED: "
 786                                                  "user list username and "
 787                                                  "given password ok (%s)\n",
 788                                                  user));
 789                                 }
 790                         }
 791                 }
 792         }
 793
 794   check_guest:
 795
 796         /* check for a normal guest connection */
 797         if (!ok && GUEST_OK(snum)) {
 798                 struct passwd *guest_pw;
 799                 fstring guestname;
 800                 fstrcpy(guestname,lp_guestaccount());
 801                 guest_pw = Get_Pwnam_alloc(talloc_tos(), guestname);
 802                 if (guest_pw != NULL) {
 803                         fstrcpy(user,guestname);
 804                         ok = True;
 805                         DEBUG(3,("authorise_login: ACCEPTED: guest account "
 806                                  "and guest ok (%s)\n", user));
 807                 } else {
 808                         DEBUG(0,("authorise_login: Invalid guest account "
 809                                  "%s??\n",guestname));
 810                 }
 811                 TALLOC_FREE(guest_pw);
 812                 *guest = True;
 813         }
 814
 815         if (ok && !user_ok(user, snum)) {
 816                 DEBUG(0,("authorise_login: rejected invalid user %s\n",user));
 817                 ok = False;
 818         }
 819
 820         return(ok);
 821 }