source3/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  Converts a name to a fully qalified domain name.
  34 ***********************************************************************/
  35
  36 void name_to_fqdn(fstring fqdn, const char *name)
  37 {
  38         struct hostent *hp = sys_gethostbyname(name);
  39         if ( hp && hp->h_name && *hp->h_name ) {
  40                 DEBUG(10,("name_to_fqdn: lookup for %s -> %s.\n", name, hp->h_name));
  41                 fstrcpy(fqdn,hp->h_name);
  42         } else {
  43                 DEBUG(10,("name_to_fqdn: lookup for %s failed.\n", name));
  44                 fstrcpy(fqdn, name);
  45         }
  46 }
  47
  48 /**********************************************************************
  49  Adds a single service principal, i.e. 'host' to the system keytab
  50 ***********************************************************************/
  51
  52 int ads_keytab_add_entry(const char *srvPrinc, ADS_STRUCT *ads)
  53 {
  54         krb5_error_code ret = 0;
  55         krb5_context context = NULL;
  56         krb5_keytab keytab = NULL;
  57         krb5_kt_cursor cursor = NULL;
  58         krb5_keytab_entry kt_entry;
  59         krb5_principal princ = NULL;
  60         krb5_data password;
  61         krb5_enctype *enctypes = NULL;
  62         krb5_kvno kvno;
  63
  64         char *principal = NULL;
  65         char *princ_s = NULL;
  66         char *password_s = NULL;
  67         char keytab_name[MAX_KEYTAB_NAME_LEN];          /* This MAX_NAME_LEN is a constant defined in krb5.h */
  68         fstring my_fqdn;
  69         int i;
  70         char *ktprinc = NULL;
  71
  72         ZERO_STRUCT(kt_entry);
  73         initialize_krb5_error_table();
  74         ret = krb5_init_context(&context);
  75         if (ret) {
  76                 DEBUG(1,("ads_keytab_add_entry: could not krb5_init_context: %s\n",error_message(ret)));
  77                 return -1;
  78         }
  79 #ifdef HAVE_WRFILE_KEYTAB       /* MIT */
  80         keytab_name[0] = 'W';
  81         keytab_name[1] = 'R';
  82         ret = krb5_kt_default_name(context, (char *) &keytab_name[2], MAX_KEYTAB_NAME_LEN - 4);
  83 #else                           /* Heimdal */
  84         ret = krb5_kt_default_name(context, (char *) &keytab_name[0], MAX_KEYTAB_NAME_LEN - 2);
  85 #endif
  86         if (ret) {
  87                 DEBUG(1,("ads_keytab_add_entry: krb5_kt_default_name failed (%s)\n", error_message(ret)));
  88                 goto out;
  89         }
  90         DEBUG(2,("ads_keytab_add_entry: Using default system keytab: %s\n", (char *) &keytab_name));
  91         ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
  92         if (ret) {
  93                 DEBUG(1,("ads_keytab_add_entry: krb5_kt_resolve failed (%s)\n", error_message(ret)));
  94                 goto out;
  95         }
  96
  97         /* retrieve the password */
  98         if (!secrets_init()) {
  99                 DEBUG(1,("ads_keytab_add_entry: secrets_init failed\n"));
 100                 ret = -1;
 101                 goto out;
 102         }
 103         password_s = secrets_fetch_machine_password(lp_workgroup(), NULL, NULL);
 104         if (!password_s) {
 105                 DEBUG(1,("ads_keytab_add_entry: failed to fetch machine password\n"));
 106                 ret = -1;
 107                 goto out;
 108         }
 109         password.data = password_s;
 110         password.length = strlen(password_s);
 111
 112         /* Construct our principal */
 113         name_to_fqdn(my_fqdn, global_myname());
 114         strlower_m(my_fqdn);
 115         asprintf(&princ_s, "%s/%s@%s", srvPrinc, my_fqdn, lp_realm());
 116
 117         ret = krb5_parse_name(context, princ_s, &princ);
 118         if (ret) {
 119                 DEBUG(1,("ads_keytab_add_entry: krb5_parse_name(%s) failed (%s)\n", princ_s, error_message(ret)));
 120                 goto out;
 121         }
 122
 123         kvno = (krb5_kvno) ads_get_kvno(ads, global_myname());
 124         if (kvno == -1) {       /* -1 indicates failure, everything else is OK */
 125                 DEBUG(1,("ads_keytab_add_entry: ads_get_kvno failed to determine the system's kvno.\n"));
 126                 ret = -1;
 127                 goto out;
 128         }
 129
 130         /* Seek and delete old keytab entries */
 131         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 132         if (ret != KRB5_KT_END && ret != ENOENT ) {
 133                 DEBUG(3,("ads_keytab_add_entry: Will try to delete old keytab entries\n"));
 134                 while(!krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) {
 135                         BOOL compare_ok = False;
 136
 137                         ret = krb5_unparse_name(context, kt_entry.principal, &ktprinc);
 138                         if (ret) {
 139                                 DEBUG(1,("ads_keytab_add_entry: krb5_unparse_name failed (%s)\n", error_message(ret)));
 140                                 goto out;
 141                         }
 142
 143                         /*---------------------------------------------------------------------------
 144                          * Save the entries with kvno - 1.   This is what microsoft does
 145                          * to allow people with existing sessions that have kvno - 1 to still
 146                          * work.   Otherwise, when the password for the machine changes, all
 147                          * kerberizied sessions will 'break' until either the client reboots or
 148                          * the client's session key expires and they get a new session ticket
 149                          * with the new kvno.
 150                          */
 151
 152 #ifdef HAVE_KRB5_KT_COMPARE
 153                         compare_ok = ((krb5_kt_compare(context, &kt_entry, princ, 0, 0) == True) && (kt_entry.vno != kvno - 1));
 154 #else
 155                         compare_ok = ((strcmp(ktprinc, princ_s) == 0) && (kt_entry.vno != kvno - 1));
 156 #endif
 157                         krb5_free_unparsed_name(context, ktprinc);
 158                         ktprinc = NULL;
 159
 160                         if (compare_ok) {
 161                                 DEBUG(3,("ads_keytab_add_entry: Found old entry for principal: %s (kvno %d) - trying to remove it.\n",
 162                                         princ_s, kt_entry.vno));
 163                                 ret = krb5_kt_end_seq_get(context, keytab, &cursor);
 164                                 cursor = NULL;
 165                                 if (ret) {
 166                                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_end_seq_get() failed (%s)\n",
 167                                                 error_message(ret)));
 168                                         goto out;
 169                                 }
 170                                 ret = krb5_kt_remove_entry(context, keytab, &kt_entry);
 171                                 if (ret) {
 172                                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_remove_entry failed (%s)\n",
 173                                                 error_message(ret)));
 174                                         goto out;
 175                                 }
 176                                 ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 177                                 if (ret) {
 178                                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_start_seq failed (%s)\n",
 179                                                 error_message(ret)));
 180                                         goto out;
 181                                 }
 182                                 ret = krb5_free_keytab_entry_contents(context, &kt_entry);
 183                                 ZERO_STRUCT(kt_entry);
 184                                 if (ret) {
 185                                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_remove_entry failed (%s)\n",
 186                                                 error_message(ret)));
 187                                         goto out;
 188                                 }
 189                                 continue;
 190                         }
 191
 192                         /* Not a match, just free this entry and continue. */
 193                         ret = krb5_free_keytab_entry_contents(context, &kt_entry);
 194                         ZERO_STRUCT(kt_entry);
 195                         if (ret) {
 196                                 DEBUG(1,("ads_keytab_add_entry: krb5_free_keytab_entry_contents failed (%s)\n", error_message(ret)));
 197                                 goto out;
 198                         }
 199                 }
 200
 201                 ret = krb5_kt_end_seq_get(context, keytab, &cursor);
 202                 cursor = NULL;
 203                 if (ret) {
 204                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_end_seq_get failed (%s)\n",error_message(ret)));
 205                         goto out;
 206                 }
 207         }
 208
 209         /* Ensure we don't double free. */
 210         ZERO_STRUCT(kt_entry);
 211         cursor = NULL;
 212
 213         /* If we get here, we have deleted all the old entries with kvno's not equal to the current kvno-1. */
 214
 215         ret = get_kerberos_allowed_etypes(context,&enctypes);
 216         if (ret) {
 217                 DEBUG(1,("ads_keytab_add_entry: get_kerberos_allowed_etypes failed (%s)\n",error_message(ret)));
 218                 goto out;
 219         }
 220
 221         /* Now add keytab entries for all encryption types */
 222         for (i = 0; enctypes[i]; i++) {
 223                 krb5_keyblock *keyp;
 224
 225 #if !defined(HAVE_KRB5_KEYTAB_ENTRY_KEY) && !defined(HAVE_KRB5_KEYTAB_ENTRY_KEYBLOCK)
 226 #error krb5_keytab_entry has no key or keyblock member
 227 #endif
 228 #ifdef HAVE_KRB5_KEYTAB_ENTRY_KEY               /* MIT */
 229                 keyp = &kt_entry.key;
 230 #endif
 231 #ifdef HAVE_KRB5_KEYTAB_ENTRY_KEYBLOCK          /* Heimdal */
 232                 keyp = &kt_entry.keyblock;
 233 #endif
 234                 if (create_kerberos_key_from_string(context, princ, &password, keyp, enctypes[i])) {
 235                         continue;
 236                 }
 237
 238                 kt_entry.principal = princ;
 239                 kt_entry.vno       = kvno;
 240
 241                 DEBUG(3,("ads_keytab_add_entry: adding keytab entry for (%s) with encryption type (%d) and version (%d)\n",
 242                         princ_s, enctypes[i], kt_entry.vno));
 243                 ret = krb5_kt_add_entry(context, keytab, &kt_entry);
 244                 krb5_free_keyblock(context, keyp);
 245                 ZERO_STRUCT(kt_entry);
 246                 if (ret) {
 247                         DEBUG(1,("ads_keytab_add_entry: adding entry to keytab failed (%s)\n", error_message(ret)));
 248                         goto out;
 249                 }
 250         }
 251
 252         krb5_kt_close(context, keytab);
 253         keytab = NULL; /* Done with keytab now. No double free. */
 254
 255         /* Update the LDAP with the SPN */
 256         DEBUG(3,("ads_keytab_add_entry: Attempting to add/update '%s'\n", princ_s));
 257         if (!ADS_ERR_OK(ads_add_spn(ads, global_myname(), srvPrinc))) {
 258                 DEBUG(1,("ads_keytab_add_entry: ads_add_spn failed.\n"));
 259                 goto out;
 260         }
 261
 262 out:
 263
 264         SAFE_FREE(principal);
 265         SAFE_FREE(password_s);
 266         SAFE_FREE(princ_s);
 267
 268         {
 269                 krb5_keytab_entry zero_kt_entry;
 270                 ZERO_STRUCT(zero_kt_entry);
 271                 if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
 272                         krb5_free_keytab_entry_contents(context, &kt_entry);
 273                 }
 274         }
 275         if (princ) {
 276                 krb5_free_principal(context, princ);
 277         }
 278         if (enctypes) {
 279                 free_kerberos_etypes(context, enctypes);
 280         }
 281         if (cursor && keytab) {
 282                 krb5_kt_end_seq_get(context, keytab, &cursor);
 283         }
 284         if (keytab) {
 285                 krb5_kt_close(context, keytab);
 286         }
 287         if (context) {
 288                 krb5_free_context(context);
 289         }
 290         return (int)ret;
 291 }
 292
 293 /**********************************************************************
 294  Flushes all entries from the system keytab.
 295 ***********************************************************************/
 296
 297 int ads_keytab_flush(ADS_STRUCT *ads)
 298 {
 299         krb5_error_code ret = 0;
 300         krb5_context context = NULL;
 301         krb5_keytab keytab = NULL;
 302         krb5_kt_cursor cursor = NULL;
 303         krb5_keytab_entry kt_entry;
 304         krb5_kvno kvno;
 305         char keytab_name[MAX_KEYTAB_NAME_LEN];
 306
 307         ZERO_STRUCT(kt_entry);
 308         initialize_krb5_error_table();
 309         ret = krb5_init_context(&context);
 310         if (ret) {
 311                 DEBUG(1,("ads_keytab_flush: could not krb5_init_context: %s\n",error_message(ret)));
 312                 return ret;
 313         }
 314 #ifdef HAVE_WRFILE_KEYTAB
 315         keytab_name[0] = 'W';
 316         keytab_name[1] = 'R';
 317         ret = krb5_kt_default_name(context, (char *) &keytab_name[2], MAX_KEYTAB_NAME_LEN - 4);
 318 #else
 319         ret = krb5_kt_default_name(context, (char *) &keytab_name[0], MAX_KEYTAB_NAME_LEN - 2);
 320 #endif
 321         if (ret) {
 322                 DEBUG(1,("ads_keytab_flush: krb5_kt_default failed (%s)\n", error_message(ret)));
 323                 goto out;
 324         }
 325         DEBUG(3,("ads_keytab_flush: Using default keytab: %s\n", (char *) &keytab_name));
 326         ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
 327         if (ret) {
 328                 DEBUG(1,("ads_keytab_flush: krb5_kt_default failed (%s)\n", error_message(ret)));
 329                 goto out;
 330         }
 331         ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
 332         if (ret) {
 333                 DEBUG(1,("ads_keytab_flush: krb5_kt_default failed (%s)\n", error_message(ret)));
 334                 goto out;
 335         }
 336
 337         kvno = (krb5_kvno) ads_get_kvno(ads, global_myname());
 338         if (kvno == -1) {       /* -1 indicates a failure */
 339                 DEBUG(1,("ads_keytab_flush: Error determining the system's kvno.\n"));
 340                 goto out;
 341         }
 342
 343         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 344         if (ret != KRB5_KT_END && ret != ENOENT) {
 345                 while (!krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) {
 346                         ret = krb5_kt_end_seq_get(context, keytab, &cursor);
 347                         cursor = NULL;
 348                         if (ret) {
 349                                 DEBUG(1,("ads_keytab_flush: krb5_kt_end_seq_get() failed (%s)\n",error_message(ret)));
 350                                 goto out;
 351                         }
 352                         ret = krb5_kt_remove_entry(context, keytab, &kt_entry);
 353                         if (ret) {
 354                                 DEBUG(1,("ads_keytab_flush: krb5_kt_remove_entry failed (%s)\n",error_message(ret)));
 355                                 goto out;
 356                         }
 357                         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 358                         if (ret) {
 359                                 DEBUG(1,("ads_keytab_flush: krb5_kt_start_seq failed (%s)\n",error_message(ret)));
 360                                 goto out;
 361                         }
 362                         ret = krb5_free_keytab_entry_contents(context, &kt_entry);
 363                         ZERO_STRUCT(kt_entry);
 364                         if (ret) {
 365                                 DEBUG(1,("ads_keytab_flush: krb5_kt_remove_entry failed (%s)\n",error_message(ret)));
 366                                 goto out;
 367                         }
 368                 }
 369         }
 370
 371         /* Ensure we don't double free. */
 372         ZERO_STRUCT(kt_entry);
 373         cursor = NULL;
 374
 375         if (!ADS_ERR_OK(ads_clear_spns(ads, global_myname()))) {
 376                 DEBUG(1,("ads_keytab_flush: Error while clearing service principal listings in LDAP.\n"));
 377                 goto out;
 378         }
 379
 380 out:
 381
 382         {
 383                 krb5_keytab_entry zero_kt_entry;
 384                 ZERO_STRUCT(zero_kt_entry);
 385                 if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
 386                         krb5_free_keytab_entry_contents(context, &kt_entry);
 387                 }
 388         }
 389         if (cursor && keytab) {
 390                 krb5_kt_end_seq_get(context, keytab, &cursor);
 391         }
 392         if (keytab) {
 393                 krb5_kt_close(context, keytab);
 394         }
 395         if (context) {
 396                 krb5_free_context(context);
 397         }
 398         return ret;
 399 }
 400
 401 /**********************************************************************
 402  Adds all the required service principals to the system keytab.
 403 ***********************************************************************/
 404
 405 int ads_keytab_create_default(ADS_STRUCT *ads)
 406 {
 407         krb5_error_code ret = 0;
 408         krb5_context context = NULL;
 409         krb5_keytab keytab = NULL;
 410         krb5_kt_cursor cursor = NULL;
 411         krb5_keytab_entry kt_entry;
 412         krb5_kvno kvno;
 413         int i, found = 0;
 414         char **oldEntries = NULL;
 415
 416         ret = ads_keytab_add_entry("host", ads);
 417         if (ret) {
 418                 DEBUG(1,("ads_keytab_create_default: ads_keytab_add_entry failed while adding 'host'.\n"));
 419                 return ret;
 420         }
 421         ret = ads_keytab_add_entry("cifs", ads);
 422         if (ret) {
 423                 DEBUG(1,("ads_keytab_create_default: ads_keytab_add_entry failed while adding 'cifs'.\n"));
 424                 return ret;
 425         }
 426
 427         kvno = (krb5_kvno) ads_get_kvno(ads, global_myname());
 428         if (kvno == -1) {
 429                 DEBUG(1,("ads_keytab_create_default: ads_get_kvno failed to determine the system's kvno.\n"));
 430                 return -1;
 431         }
 432
 433         DEBUG(3,("ads_keytab_create_default: Searching for keytab entries to preserve and update.\n"));
 434         /* Now loop through the keytab and update any other existing entries... */
 435
 436         ZERO_STRUCT(kt_entry);
 437
 438         initialize_krb5_error_table();
 439         ret = krb5_init_context(&context);
 440         if (ret) {
 441                 DEBUG(1,("ads_keytab_create_default: could not krb5_init_context: %s\n",error_message(ret)));
 442                 return ret;
 443         }
 444         ret = krb5_kt_default(context, &keytab);
 445         if (ret) {
 446                 DEBUG(1,("ads_keytab_create_default: krb5_kt_default failed (%s)\n",error_message(ret)));
 447                 goto done;
 448         }
 449
 450         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 451         if (ret != KRB5_KT_END && ret != ENOENT ) {
 452                 while ((ret = krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) == 0) {
 453                         krb5_free_keytab_entry_contents(context, &kt_entry);
 454                         ZERO_STRUCT(kt_entry);
 455                         found++;
 456                 }
 457         }
 458         krb5_kt_end_seq_get(context, keytab, &cursor);
 459         cursor = NULL;
 460
 461         /*
 462          * Hmmm. There is no "rewind" function for the keytab. This means we have a race condition
 463          * where someone else could add entries after we've counted them. Re-open asap to minimise
 464          * the race. JRA.
 465          */
 466
 467         DEBUG(3, ("ads_keytab_create_default: Found %d entries in the keytab.\n", found));
 468         if (!found) {
 469                 goto done;
 470         }
 471         oldEntries = (char **) malloc(found * sizeof(char *));
 472         if (!oldEntries) {
 473                 DEBUG(1,("ads_keytab_create_default: Failed to allocate space to store the old keytab entries (malloc failed?).\n"));
 474                 ret = -1;
 475                 goto done;
 476         }
 477         memset(oldEntries, '\0', found * sizeof(char *));
 478
 479         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 480         if (ret != KRB5_KT_END && ret != ENOENT ) {
 481                 while ((ret = krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) == 0) {
 482                         if (kt_entry.vno != kvno) {
 483                                 char *ktprinc = NULL;
 484                                 char *p;
 485
 486                                 /* This returns a malloc'ed string in ktprinc. */
 487                                 ret = krb5_unparse_name(context, kt_entry.principal, &ktprinc);
 488                                 if (ret) {
 489                                         DEBUG(1,("krb5_unparse_name failed (%s)\n", error_message(ret)));
 490                                         goto done;
 491                                 }
 492                                 /*
 493                                  * From looking at the krb5 source they don't seem to take locale
 494                                  * or mb strings into account. Maybe this is because they assume utf8 ?
 495                                  * In this case we may need to convert from utf8 to mb charset here ? JRA.
 496                                  */
 497                                 p = strchr_m(ktprinc, '/');
 498                                 if (p) {
 499                                         *p = '\0';
 500                                 }
 501                                 for (i = 0; i < found; i++) {
 502                                         if (!oldEntries[i]) {
 503                                                 oldEntries[i] = ktprinc;
 504                                                 break;
 505                                         }
 506                                         if (!strcmp(oldEntries[i], ktprinc)) {
 507                                                 break;
 508                                         }
 509                                 }
 510                         }
 511                         krb5_free_keytab_entry_contents(context, &kt_entry);
 512                         ZERO_STRUCT(kt_entry);
 513                 }
 514                 for (i = 0; oldEntries[i]; i++) {
 515                         ret |= ads_keytab_add_entry(oldEntries[i], ads);
 516                         krb5_free_unparsed_name(context, oldEntries[i]);
 517                 }
 518                 krb5_kt_end_seq_get(context, keytab, &cursor);
 519         }
 520         cursor = NULL;
 521
 522 done:
 523
 524         SAFE_FREE(oldEntries);
 525
 526         {
 527                 krb5_keytab_entry zero_kt_entry;
 528                 ZERO_STRUCT(zero_kt_entry);
 529                 if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
 530                         krb5_free_keytab_entry_contents(context, &kt_entry);
 531                 }
 532         }
 533         if (cursor && keytab) {
 534                 krb5_kt_end_seq_get(context, keytab, &cursor);
 535         }
 536         if (keytab) {
 537                 krb5_kt_close(context, keytab);
 538         }
 539         if (context) {
 540                 krb5_free_context(context);
 541         }
 542         return ret;
 543 }
 544 #endif /* HAVE_KRB5 */