source/libads/kerberos_keytab.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    kerberos keytab utility library
   4    Copyright (C) Andrew Tridgell 2001
   5    Copyright (C) Remus Koos 2001
   6    Copyright (C) Luke Howard 2003
   7    Copyright (C) Jim McDonough (jmcd@us.ibm.com) 2003
   8    Copyright (C) Guenther Deschner 2003
   9    Copyright (C) Rakesh Patel 2004
  10    Copyright (C) Dan Perry 2004
  11    Copyright (C) Jeremy Allison 2004
  12
  13    This program is free software; you can redistribute it and/or modify
  14    it under the terms of the GNU General Public License as published by
  15    the Free Software Foundation; either version 2 of the License, or
  16    (at your option) any later version.
  17
  18    This program is distributed in the hope that it will be useful,
  19    but WITHOUT ANY WARRANTY; without even the implied warranty of
  20    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21    GNU General Public License for more details.
  22
  23    You should have received a copy of the GNU General Public License
  24    along with this program; if not, write to the Free Software
  25    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  26 */
  27
  28 #include "includes.h"
  29
  30 #ifdef HAVE_KRB5
  31
  32 /**********************************************************************
  33  Adds a single service principal, i.e. 'host' to the system keytab
  34 ***********************************************************************/
  35
  36 int ads_keytab_add_entry(ADS_STRUCT *ads, const char *srvPrinc)
  37 {
  38         krb5_error_code ret = 0;
  39         krb5_context context = NULL;
  40         krb5_keytab keytab = NULL;
  41         krb5_kt_cursor cursor = NULL;
  42         krb5_keytab_entry kt_entry;
  43         krb5_principal princ = NULL;
  44         krb5_data password;
  45         krb5_enctype *enctypes = NULL;
  46         krb5_kvno kvno;
  47
  48         char *principal = NULL;
  49         char *princ_s = NULL;
  50         char *password_s = NULL;
  51         char keytab_name[MAX_KEYTAB_NAME_LEN];          /* This MAX_NAME_LEN is a constant defined in krb5.h */
  52         fstring my_fqdn;
  53         int i;
  54         char *ktprinc = NULL;
  55
  56         ZERO_STRUCT(kt_entry);
  57         initialize_krb5_error_table();
  58         ret = krb5_init_context(&context);
  59         if (ret) {
  60                 DEBUG(1,("ads_keytab_add_entry: could not krb5_init_context: %s\n",error_message(ret)));
  61                 return -1;
  62         }
  63 #ifdef HAVE_WRFILE_KEYTAB       /* MIT */
  64         keytab_name[0] = 'W';
  65         keytab_name[1] = 'R';
  66         ret = krb5_kt_default_name(context, (char *) &keytab_name[2], MAX_KEYTAB_NAME_LEN - 4);
  67 #else                           /* Heimdal */
  68         ret = krb5_kt_default_name(context, (char *) &keytab_name[0], MAX_KEYTAB_NAME_LEN - 2);
  69 #endif
  70         if (ret) {
  71                 DEBUG(1,("ads_keytab_add_entry: krb5_kt_default_name failed (%s)\n", error_message(ret)));
  72                 goto out;
  73         }
  74         DEBUG(2,("ads_keytab_add_entry: Using default system keytab: %s\n", (char *) &keytab_name));
  75         ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
  76         if (ret) {
  77                 DEBUG(1,("ads_keytab_add_entry: krb5_kt_resolve failed (%s)\n", error_message(ret)));
  78                 goto out;
  79         }
  80
  81         /* retrieve the password */
  82         if (!secrets_init()) {
  83                 DEBUG(1,("ads_keytab_add_entry: secrets_init failed\n"));
  84                 ret = -1;
  85                 goto out;
  86         }
  87         password_s = secrets_fetch_machine_password(lp_workgroup(), NULL, NULL);
  88         if (!password_s) {
  89                 DEBUG(1,("ads_keytab_add_entry: failed to fetch machine password\n"));
  90                 ret = -1;
  91                 goto out;
  92         }
  93         password.data = password_s;
  94         password.length = strlen(password_s);
  95
  96         /* Construct our principal */
  97         name_to_fqdn(my_fqdn, global_myname());
  98         strlower_m(my_fqdn);
  99         asprintf(&princ_s, "%s/%s@%s", srvPrinc, my_fqdn, lp_realm());
 100
 101         ret = krb5_parse_name(context, princ_s, &princ);
 102         if (ret) {
 103                 DEBUG(1,("ads_keytab_add_entry: krb5_parse_name(%s) failed (%s)\n", princ_s, error_message(ret)));
 104                 goto out;
 105         }
 106
 107         kvno = (krb5_kvno) ads_get_kvno(ads, global_myname());
 108         if (kvno == -1) {       /* -1 indicates failure, everything else is OK */
 109                 DEBUG(1,("ads_keytab_add_entry: ads_get_kvno failed to determine the system's kvno.\n"));
 110                 ret = -1;
 111                 goto out;
 112         }
 113
 114         /* Seek and delete old keytab entries */
 115         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 116         if (ret != KRB5_KT_END && ret != ENOENT ) {
 117                 DEBUG(3,("ads_keytab_add_entry: Will try to delete old keytab entries\n"));
 118                 while(!krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) {
 119                         BOOL compare_ok = False;
 120
 121                         ret = krb5_unparse_name(context, kt_entry.principal, &ktprinc);
 122                         if (ret) {
 123                                 DEBUG(1,("ads_keytab_add_entry: krb5_unparse_name failed (%s)\n", error_message(ret)));
 124                                 goto out;
 125                         }
 126
 127                         /*---------------------------------------------------------------------------
 128                          * Save the entries with kvno - 1.   This is what microsoft does
 129                          * to allow people with existing sessions that have kvno - 1 to still
 130                          * work.   Otherwise, when the password for the machine changes, all
 131                          * kerberizied sessions will 'break' until either the client reboots or
 132                          * the client's session key expires and they get a new session ticket
 133                          * with the new kvno.
 134                          */
 135
 136 #ifdef HAVE_KRB5_KT_COMPARE
 137                         compare_ok = ((krb5_kt_compare(context, &kt_entry, princ, 0, 0) == True) && (kt_entry.vno != kvno - 1));
 138 #else
 139                         compare_ok = ((strcmp(ktprinc, princ_s) == 0) && (kt_entry.vno != kvno - 1));
 140 #endif
 141                         krb5_free_unparsed_name(context, ktprinc);
 142                         ktprinc = NULL;
 143
 144                         if (compare_ok) {
 145                                 DEBUG(3,("ads_keytab_add_entry: Found old entry for principal: %s (kvno %d) - trying to remove it.\n",
 146                                         princ_s, kt_entry.vno));
 147                                 ret = krb5_kt_end_seq_get(context, keytab, &cursor);
 148                                 cursor = NULL;
 149                                 if (ret) {
 150                                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_end_seq_get() failed (%s)\n",
 151                                                 error_message(ret)));
 152                                         goto out;
 153                                 }
 154                                 ret = krb5_kt_remove_entry(context, keytab, &kt_entry);
 155                                 if (ret) {
 156                                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_remove_entry failed (%s)\n",
 157                                                 error_message(ret)));
 158                                         goto out;
 159                                 }
 160                                 ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 161                                 if (ret) {
 162                                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_start_seq failed (%s)\n",
 163                                                 error_message(ret)));
 164                                         goto out;
 165                                 }
 166                                 ret = krb5_free_keytab_entry_contents(context, &kt_entry);
 167                                 ZERO_STRUCT(kt_entry);
 168                                 if (ret) {
 169                                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_remove_entry failed (%s)\n",
 170                                                 error_message(ret)));
 171                                         goto out;
 172                                 }
 173                                 continue;
 174                         }
 175
 176                         /* Not a match, just free this entry and continue. */
 177                         ret = krb5_free_keytab_entry_contents(context, &kt_entry);
 178                         ZERO_STRUCT(kt_entry);
 179                         if (ret) {
 180                                 DEBUG(1,("ads_keytab_add_entry: krb5_free_keytab_entry_contents failed (%s)\n", error_message(ret)));
 181                                 goto out;
 182                         }
 183                 }
 184
 185                 ret = krb5_kt_end_seq_get(context, keytab, &cursor);
 186                 cursor = NULL;
 187                 if (ret) {
 188                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_end_seq_get failed (%s)\n",error_message(ret)));
 189                         goto out;
 190                 }
 191         }
 192
 193         /* Ensure we don't double free. */
 194         ZERO_STRUCT(kt_entry);
 195         cursor = NULL;
 196
 197         /* If we get here, we have deleted all the old entries with kvno's not equal to the current kvno-1. */
 198
 199         ret = get_kerberos_allowed_etypes(context,&enctypes);
 200         if (ret) {
 201                 DEBUG(1,("ads_keytab_add_entry: get_kerberos_allowed_etypes failed (%s)\n",error_message(ret)));
 202                 goto out;
 203         }
 204
 205         /* Now add keytab entries for all encryption types */
 206         for (i = 0; enctypes[i]; i++) {
 207                 krb5_keyblock *keyp;
 208
 209 #if !defined(HAVE_KRB5_KEYTAB_ENTRY_KEY) && !defined(HAVE_KRB5_KEYTAB_ENTRY_KEYBLOCK)
 210 #error krb5_keytab_entry has no key or keyblock member
 211 #endif
 212 #ifdef HAVE_KRB5_KEYTAB_ENTRY_KEY               /* MIT */
 213                 keyp = &kt_entry.key;
 214 #endif
 215 #ifdef HAVE_KRB5_KEYTAB_ENTRY_KEYBLOCK          /* Heimdal */
 216                 keyp = &kt_entry.keyblock;
 217 #endif
 218                 if (create_kerberos_key_from_string(context, princ, &password, keyp, enctypes[i])) {
 219                         continue;
 220                 }
 221
 222                 kt_entry.principal = princ;
 223                 kt_entry.vno       = kvno;
 224
 225                 DEBUG(3,("ads_keytab_add_entry: adding keytab entry for (%s) with encryption type (%d) and version (%d)\n",
 226                         princ_s, enctypes[i], kt_entry.vno));
 227                 ret = krb5_kt_add_entry(context, keytab, &kt_entry);
 228                 krb5_free_keyblock(context, keyp);
 229                 ZERO_STRUCT(kt_entry);
 230                 if (ret) {
 231                         DEBUG(1,("ads_keytab_add_entry: adding entry to keytab failed (%s)\n", error_message(ret)));
 232                         goto out;
 233                 }
 234         }
 235
 236         krb5_kt_close(context, keytab);
 237         keytab = NULL; /* Done with keytab now. No double free. */
 238
 239         /* Update the LDAP with the SPN */
 240         DEBUG(3,("ads_keytab_add_entry: Attempting to add/update '%s'\n", princ_s));
 241         if (!ADS_ERR_OK(ads_add_service_principal_name(ads, global_myname(), srvPrinc))) {
 242                 DEBUG(1,("ads_keytab_add_entry: ads_add_service_principcal_name failed.\n"));
 243                 goto out;
 244         }
 245
 246 out:
 247
 248         SAFE_FREE(principal);
 249         SAFE_FREE(password_s);
 250         SAFE_FREE(princ_s);
 251
 252         {
 253                 krb5_keytab_entry zero_kt_entry;
 254                 ZERO_STRUCT(zero_kt_entry);
 255                 if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
 256                         krb5_free_keytab_entry_contents(context, &kt_entry);
 257                 }
 258         }
 259         if (princ) {
 260                 krb5_free_principal(context, princ);
 261         }
 262         if (enctypes) {
 263                 free_kerberos_etypes(context, enctypes);
 264         }
 265         if (cursor && keytab) {
 266                 krb5_kt_end_seq_get(context, keytab, &cursor);
 267         }
 268         if (keytab) {
 269                 krb5_kt_close(context, keytab);
 270         }
 271         if (context) {
 272                 krb5_free_context(context);
 273         }
 274         return (int)ret;
 275 }
 276
 277 /**********************************************************************
 278  Flushes all entries from the system keytab.
 279 ***********************************************************************/
 280
 281 int ads_keytab_flush(ADS_STRUCT *ads)
 282 {
 283         krb5_error_code ret = 0;
 284         krb5_context context = NULL;
 285         krb5_keytab keytab = NULL;
 286         krb5_kt_cursor cursor = NULL;
 287         krb5_keytab_entry kt_entry;
 288         krb5_kvno kvno;
 289         char keytab_name[MAX_KEYTAB_NAME_LEN];
 290
 291         ZERO_STRUCT(kt_entry);
 292         initialize_krb5_error_table();
 293         ret = krb5_init_context(&context);
 294         if (ret) {
 295                 DEBUG(1,("ads_keytab_flush: could not krb5_init_context: %s\n",error_message(ret)));
 296                 return ret;
 297         }
 298 #ifdef HAVE_WRFILE_KEYTAB
 299         keytab_name[0] = 'W';
 300         keytab_name[1] = 'R';
 301         ret = krb5_kt_default_name(context, (char *) &keytab_name[2], MAX_KEYTAB_NAME_LEN - 4);
 302 #else
 303         ret = krb5_kt_default_name(context, (char *) &keytab_name[0], MAX_KEYTAB_NAME_LEN - 2);
 304 #endif
 305         if (ret) {
 306                 DEBUG(1,("ads_keytab_flush: krb5_kt_default failed (%s)\n", error_message(ret)));
 307                 goto out;
 308         }
 309         DEBUG(3,("ads_keytab_flush: Using default keytab: %s\n", (char *) &keytab_name));
 310         ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
 311         if (ret) {
 312                 DEBUG(1,("ads_keytab_flush: krb5_kt_default failed (%s)\n", error_message(ret)));
 313                 goto out;
 314         }
 315         ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
 316         if (ret) {
 317                 DEBUG(1,("ads_keytab_flush: krb5_kt_default failed (%s)\n", error_message(ret)));
 318                 goto out;
 319         }
 320
 321         kvno = (krb5_kvno) ads_get_kvno(ads, global_myname());
 322         if (kvno == -1) {       /* -1 indicates a failure */
 323                 DEBUG(1,("ads_keytab_flush: Error determining the system's kvno.\n"));
 324                 goto out;
 325         }
 326
 327         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 328         if (ret != KRB5_KT_END && ret != ENOENT) {
 329                 while (!krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) {
 330                         ret = krb5_kt_end_seq_get(context, keytab, &cursor);
 331                         cursor = NULL;
 332                         if (ret) {
 333                                 DEBUG(1,("ads_keytab_flush: krb5_kt_end_seq_get() failed (%s)\n",error_message(ret)));
 334                                 goto out;
 335                         }
 336                         ret = krb5_kt_remove_entry(context, keytab, &kt_entry);
 337                         if (ret) {
 338                                 DEBUG(1,("ads_keytab_flush: krb5_kt_remove_entry failed (%s)\n",error_message(ret)));
 339                                 goto out;
 340                         }
 341                         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 342                         if (ret) {
 343                                 DEBUG(1,("ads_keytab_flush: krb5_kt_start_seq failed (%s)\n",error_message(ret)));
 344                                 goto out;
 345                         }
 346                         ret = krb5_free_keytab_entry_contents(context, &kt_entry);
 347                         ZERO_STRUCT(kt_entry);
 348                         if (ret) {
 349                                 DEBUG(1,("ads_keytab_flush: krb5_kt_remove_entry failed (%s)\n",error_message(ret)));
 350                                 goto out;
 351                         }
 352                 }
 353         }
 354
 355         /* Ensure we don't double free. */
 356         ZERO_STRUCT(kt_entry);
 357         cursor = NULL;
 358
 359         if (!ADS_ERR_OK(ads_clear_service_principal_names(ads, global_myname()))) {
 360                 DEBUG(1,("ads_keytab_flush: Error while clearing service principal listings in LDAP.\n"));
 361                 goto out;
 362         }
 363
 364 out:
 365
 366         {
 367                 krb5_keytab_entry zero_kt_entry;
 368                 ZERO_STRUCT(zero_kt_entry);
 369                 if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
 370                         krb5_free_keytab_entry_contents(context, &kt_entry);
 371                 }
 372         }
 373         if (cursor && keytab) {
 374                 krb5_kt_end_seq_get(context, keytab, &cursor);
 375         }
 376         if (keytab) {
 377                 krb5_kt_close(context, keytab);
 378         }
 379         if (context) {
 380                 krb5_free_context(context);
 381         }
 382         return ret;
 383 }
 384
 385 /**********************************************************************
 386  Adds all the required service principals to the system keytab.
 387 ***********************************************************************/
 388
 389 int ads_keytab_create_default(ADS_STRUCT *ads)
 390 {
 391         krb5_error_code ret = 0;
 392         krb5_context context = NULL;
 393         krb5_keytab keytab = NULL;
 394         krb5_kt_cursor cursor = NULL;
 395         krb5_keytab_entry kt_entry;
 396         krb5_kvno kvno;
 397         int i, found = 0;
 398         char **oldEntries = NULL;
 399
 400         ret = ads_keytab_add_entry(ads, "host");
 401         if (ret) {
 402                 DEBUG(1,("ads_keytab_create_default: ads_keytab_add_entry failed while adding 'host'.\n"));
 403                 return ret;
 404         }
 405         ret = ads_keytab_add_entry(ads, "cifs");
 406         if (ret) {
 407                 DEBUG(1,("ads_keytab_create_default: ads_keytab_add_entry failed while adding 'cifs'.\n"));
 408                 return ret;
 409         }
 410
 411         kvno = (krb5_kvno) ads_get_kvno(ads, global_myname());
 412         if (kvno == -1) {
 413                 DEBUG(1,("ads_keytab_create_default: ads_get_kvno failed to determine the system's kvno.\n"));
 414                 return -1;
 415         }
 416
 417         DEBUG(3,("ads_keytab_create_default: Searching for keytab entries to preserve and update.\n"));
 418         /* Now loop through the keytab and update any other existing entries... */
 419
 420         ZERO_STRUCT(kt_entry);
 421
 422         initialize_krb5_error_table();
 423         ret = krb5_init_context(&context);
 424         if (ret) {
 425                 DEBUG(1,("ads_keytab_create_default: could not krb5_init_context: %s\n",error_message(ret)));
 426                 return ret;
 427         }
 428         ret = krb5_kt_default(context, &keytab);
 429         if (ret) {
 430                 DEBUG(1,("ads_keytab_create_default: krb5_kt_default failed (%s)\n",error_message(ret)));
 431                 goto done;
 432         }
 433
 434         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 435         if (ret != KRB5_KT_END && ret != ENOENT ) {
 436                 while ((ret = krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) == 0) {
 437                         krb5_free_keytab_entry_contents(context, &kt_entry);
 438                         ZERO_STRUCT(kt_entry);
 439                         found++;
 440                 }
 441         }
 442         krb5_kt_end_seq_get(context, keytab, &cursor);
 443         cursor = NULL;
 444
 445         /*
 446          * Hmmm. There is no "rewind" function for the keytab. This means we have a race condition
 447          * where someone else could add entries after we've counted them. Re-open asap to minimise
 448          * the race. JRA.
 449          */
 450
 451         DEBUG(3, ("ads_keytab_create_default: Found %d entries in the keytab.\n", found));
 452         if (!found) {
 453                 goto done;
 454         }
 455         oldEntries = (char **) malloc(found * sizeof(char *));
 456         if (!oldEntries) {
 457                 DEBUG(1,("ads_keytab_create_default: Failed to allocate space to store the old keytab entries (malloc failed?).\n"));
 458                 ret = -1;
 459                 goto done;
 460         }
 461         memset(oldEntries, '\0', found * sizeof(char *));
 462
 463         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 464         if (ret != KRB5_KT_END && ret != ENOENT ) {
 465                 while ((ret = krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) == 0) {
 466                         if (kt_entry.vno != kvno) {
 467                                 char *ktprinc = NULL;
 468                                 char *p;
 469
 470                                 /* This returns a malloc'ed string in ktprinc. */
 471                                 ret = krb5_unparse_name(context, kt_entry.principal, &ktprinc);
 472                                 if (ret) {
 473                                         DEBUG(1,("krb5_unparse_name failed (%s)\n", error_message(ret)));
 474                                         goto done;
 475                                 }
 476                                 /*
 477                                  * From looking at the krb5 source they don't seem to take locale
 478                                  * or mb strings into account. Maybe this is because they assume utf8 ?
 479                                  * In this case we may need to convert from utf8 to mb charset here ? JRA.
 480                                  */
 481                                 p = strchr_m(ktprinc, '/');
 482                                 if (p) {
 483                                         *p = '\0';
 484                                 }
 485                                 for (i = 0; i < found; i++) {
 486                                         if (!oldEntries[i]) {
 487                                                 oldEntries[i] = ktprinc;
 488                                                 break;
 489                                         }
 490                                         if (!strcmp(oldEntries[i], ktprinc)) {
 491                                                 break;
 492                                         }
 493                                 }
 494                         }
 495                         krb5_free_keytab_entry_contents(context, &kt_entry);
 496                         ZERO_STRUCT(kt_entry);
 497                 }
 498                 for (i = 0; oldEntries[i]; i++) {
 499                         ret |= ads_keytab_add_entry(ads, oldEntries[i]);
 500                         krb5_free_unparsed_name(context, oldEntries[i]);
 501                 }
 502                 krb5_kt_end_seq_get(context, keytab, &cursor);
 503         }
 504         cursor = NULL;
 505
 506 done:
 507
 508         SAFE_FREE(oldEntries);
 509
 510         {
 511                 krb5_keytab_entry zero_kt_entry;
 512                 ZERO_STRUCT(zero_kt_entry);
 513                 if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
 514                         krb5_free_keytab_entry_contents(context, &kt_entry);
 515                 }
 516         }
 517         if (cursor && keytab) {
 518                 krb5_kt_end_seq_get(context, keytab, &cursor);
 519         }
 520         if (keytab) {
 521                 krb5_kt_close(context, keytab);
 522         }
 523         if (context) {
 524                 krb5_free_context(context);
 525         }
 526         return ret;
 527 }
 528 #endif /* HAVE_KRB5 */