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                         SAFE_FREE(ktprinc);
 158
 159                         if (compare_ok) {
 160                                 DEBUG(3,("ads_keytab_add_entry: Found old entry for principal: %s (kvno %d) - trying to remove it.\n",
 161                                         princ_s, kt_entry.vno));
 162                                 ret = krb5_kt_end_seq_get(context, keytab, &cursor);
 163                                 cursor = NULL;
 164                                 if (ret) {
 165                                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_end_seq_get() failed (%s)\n",
 166                                                 error_message(ret)));
 167                                         goto out;
 168                                 }
 169                                 ret = krb5_kt_remove_entry(context, keytab, &kt_entry);
 170                                 if (ret) {
 171                                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_remove_entry failed (%s)\n",
 172                                                 error_message(ret)));
 173                                         goto out;
 174                                 }
 175                                 ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 176                                 if (ret) {
 177                                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_start_seq failed (%s)\n",
 178                                                 error_message(ret)));
 179                                         goto out;
 180                                 }
 181                                 ret = krb5_kt_free_entry(context, &kt_entry);
 182                                 ZERO_STRUCT(kt_entry);
 183                                 if (ret) {
 184                                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_remove_entry failed (%s)\n",
 185                                                 error_message(ret)));
 186                                         goto out;
 187                                 }
 188                                 continue;
 189                         }
 190
 191                         /* Not a match, just free this entry and continue. */
 192                         ret = krb5_kt_free_entry(context, &kt_entry);
 193                         ZERO_STRUCT(kt_entry);
 194                         if (ret) {
 195                                 DEBUG(1,("ads_keytab_add_entry: krb5_kt_free_entry failed (%s)\n", error_message(ret)));
 196                                 goto out;
 197                         }
 198                 }
 199
 200                 ret = krb5_kt_end_seq_get(context, keytab, &cursor);
 201                 cursor = NULL;
 202                 if (ret) {
 203                         DEBUG(1,("ads_keytab_add_entry: krb5_kt_end_seq_get failed (%s)\n",error_message(ret)));
 204                         goto out;
 205                 }
 206         }
 207
 208         /* Ensure we don't double free. */
 209         ZERO_STRUCT(kt_entry);
 210         cursor = NULL;
 211
 212         /* If we get here, we have deleted all the old entries with kvno's not equal to the current kvno-1. */
 213
 214         ret = get_kerberos_allowed_etypes(context,&enctypes);
 215         if (ret) {
 216                 DEBUG(1,("ads_keytab_add_entry: get_kerberos_allowed_etypes failed (%s)\n",error_message(ret)));
 217                 goto out;
 218         }
 219
 220         /* Now add keytab entries for all encryption types */
 221         for (i = 0; enctypes[i]; i++) {
 222                 krb5_keyblock *keyp;
 223
 224 #if !defined(HAVE_KRB5_KEYTAB_ENTRY_KEY) && !defined(HAVE_KRB5_KEYTAB_ENTRY_KEYBLOCK)
 225 #error krb5_keytab_entry has no key or keyblock member
 226 #endif
 227 #ifdef HAVE_KRB5_KEYTAB_ENTRY_KEY               /* MIT */
 228                 keyp = &kt_entry.key;
 229 #endif
 230 #ifdef HAVE_KRB5_KEYTAB_ENTRY_KEYBLOCK          /* Heimdal */
 231                 keyp = &kt_entry.keyblock;
 232 #endif
 233                 if (create_kerberos_key_from_string(context, princ, &password, keyp, enctypes[i])) {
 234                         continue;
 235                 }
 236
 237                 kt_entry.principal = princ;
 238                 kt_entry.vno       = kvno;
 239
 240                 DEBUG(3,("ads_keytab_add_entry: adding keytab entry for (%s) with encryption type (%d) and version (%d)\n",
 241                         princ_s, enctypes[i], kt_entry.vno));
 242                 ret = krb5_kt_add_entry(context, keytab, &kt_entry);
 243                 krb5_free_keyblock(context, keyp);
 244                 ZERO_STRUCT(kt_entry);
 245                 if (ret) {
 246                         DEBUG(1,("ads_keytab_add_entry: adding entry to keytab failed (%s)\n", error_message(ret)));
 247                         goto out;
 248                 }
 249         }
 250
 251         krb5_kt_close(context, keytab);
 252         keytab = NULL; /* Done with keytab now. No double free. */
 253
 254         /* Update the LDAP with the SPN */
 255         DEBUG(3,("ads_keytab_add_entry: Attempting to add/update '%s'\n", princ_s));
 256         if (!ADS_ERR_OK(ads_add_spn(ads, global_myname(), srvPrinc))) {
 257                 DEBUG(1,("ads_keytab_add_entry: ads_add_spn failed.\n"));
 258                 goto out;
 259         }
 260
 261 out:
 262
 263         SAFE_FREE(principal);
 264         SAFE_FREE(password_s);
 265         SAFE_FREE(princ_s);
 266
 267         {
 268                 krb5_keytab_entry zero_kt_entry;
 269                 ZERO_STRUCT(zero_kt_entry);
 270                 if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
 271                         krb5_kt_free_entry(context, &kt_entry);
 272                 }
 273         }
 274         if (princ) {
 275                 krb5_free_principal(context, princ);
 276         }
 277         if (enctypes) {
 278                 free_kerberos_etypes(context, enctypes);
 279         }
 280         if (cursor && keytab) {
 281                 krb5_kt_end_seq_get(context, keytab, &cursor);
 282         }
 283         if (keytab) {
 284                 krb5_kt_close(context, keytab);
 285         }
 286         if (context) {
 287                 krb5_free_context(context);
 288         }
 289         return (int)ret;
 290 }
 291
 292 /**********************************************************************
 293   Flushes all entries from the system keytab.
 294 ***********************************************************************/
 295
 296 int ads_keytab_flush(ADS_STRUCT *ads)
 297 {
 298         krb5_error_code ret;
 299         krb5_context context;
 300         krb5_keytab keytab;
 301         krb5_kt_cursor cursor;
 302         krb5_keytab_entry entry;
 303         krb5_kvno kvno;
 304         char keytab_name[MAX_KEYTAB_NAME_LEN];
 305
 306         initialize_krb5_error_table();
 307         ret = krb5_init_context(&context);
 308         if (ret) {
 309                 DEBUG(1,("could not krb5_init_context: %s\n",error_message(ret)));
 310                 return ret;
 311         }
 312 #ifdef HAVE_WRFILE_KEYTAB
 313         keytab_name[0] = 'W';
 314         keytab_name[1] = 'R';
 315         ret = krb5_kt_default_name(context, (char *) &keytab_name[2], MAX_KEYTAB_NAME_LEN - 4);
 316 #else
 317         ret = krb5_kt_default_name(context, (char *) &keytab_name[0], MAX_KEYTAB_NAME_LEN - 2);
 318 #endif
 319         if (ret) {
 320                 DEBUG(1,("krb5_kt_default failed (%s)\n", error_message(ret)));
 321                 goto out;
 322         }
 323         DEBUG(1,("Using default keytab: %s\n", (char *) &keytab_name));
 324         ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
 325         if (ret) {
 326                 DEBUG(1,("krb5_kt_default failed (%s)\n", error_message(ret)));
 327                 goto out;
 328         }
 329         DEBUG(1,("Using default keytab: %s\n", (char *) &keytab_name));
 330         ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
 331         if (ret) {
 332                 DEBUG(1,("krb5_kt_default failed (%s)\n", error_message(ret)));
 333                 goto out;
 334         }
 335
 336         kvno = (krb5_kvno) ads_get_kvno(ads, global_myname());
 337         if (kvno == -1) {       /* -1 indicates a failure */
 338                 DEBUG(1,("Error determining the system's kvno.\n"));
 339                 goto out;
 340         }
 341
 342         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 343         if (ret != KRB5_KT_END && ret != ENOENT) {
 344                 while (!krb5_kt_next_entry(context, keytab, &entry, &cursor)) {
 345                         ret = krb5_kt_end_seq_get(context, keytab, &cursor);
 346                         if (ret) {
 347                                 DEBUG(1,("krb5_kt_end_seq_get() failed (%s)\n",error_message(ret)));
 348                                 goto out;
 349                         }
 350                         ret = krb5_kt_remove_entry(context, keytab, &entry);
 351                         if (ret) {
 352                                 DEBUG(1,("krb5_kt_remove_entry failed (%s)\n",error_message(ret)));
 353                                 goto out;
 354                         }
 355                         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 356                         if (ret) {
 357                                 DEBUG(1,("krb5_kt_start_seq failed (%s)\n",error_message(ret)));
 358                                 goto out;
 359                         }
 360                         ret = krb5_kt_free_entry(context, &entry);
 361                         if (ret) {
 362                                 DEBUG(1,("krb5_kt_remove_entry failed (%s)\n",error_message(ret)));
 363                                 goto out;
 364                         }
 365                 }
 366         }
 367         if (!ADS_ERR_OK(ads_clear_spns(ads, global_myname()))) {
 368                 DEBUG(1,("Error while clearing service principal listings in LDAP.\n"));
 369                 goto out;
 370         }
 371
 372 out:
 373
 374         krb5_kt_close(context, keytab);
 375         return ret;
 376 }
 377
 378
 379 int ads_keytab_create_default(ADS_STRUCT *ads)
 380 {
 381         krb5_error_code ret;
 382         krb5_context context;
 383         krb5_keytab keytab;
 384         krb5_kt_cursor cursor;
 385         krb5_keytab_entry entry;
 386         krb5_kvno kvno;
 387         char *ktprinc;
 388         int i, found = 0;
 389         char **oldEntries;
 390
 391         ret = ads_keytab_add_entry("host", ads);
 392         if (ret) {
 393                 DEBUG(1,("ads_keytab_add_entry failed while adding 'host'.\n"));
 394                 return ret;
 395         }
 396         ret = ads_keytab_add_entry("cifs", ads);
 397         if (ret) {
 398                 DEBUG(1,("ads_keytab_add_entry failed while adding 'cifs'.\n"));
 399                 return ret;
 400         }
 401
 402         kvno = (krb5_kvno) ads_get_kvno(ads, global_myname());
 403         if (kvno == -1) {
 404                 DEBUG(1,("ads_get_kvno failed to determine the system's kvno.\n"));
 405                 return -1;
 406         }
 407
 408         DEBUG(1,("Searching for keytab entries to preserve and update.\n"));
 409         /* Now loop through the keytab and update any other existing entries... */
 410         initialize_krb5_error_table();
 411         ret = krb5_init_context(&context);
 412         if (ret) {
 413                 DEBUG(1,("could not krb5_init_context: %s\n",error_message(ret)));
 414                 return ret;
 415         }
 416         ret = krb5_kt_default(context, &keytab);
 417         if (ret) {
 418                 DEBUG(1,("krb5_kt_default failed (%s)\n",error_message(ret)));
 419                 return ret;
 420         }
 421
 422         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 423         if (ret != KRB5_KT_END && ret != ENOENT ) {
 424                 while ((ret = krb5_kt_next_entry(context, keytab, &entry, &cursor)) == 0) {
 425                         found++;
 426                 }
 427         }
 428
 429         DEBUG(1, ("Found %d entries in the keytab.\n", found));
 430         if (!found) {
 431                 goto done;
 432         }
 433         oldEntries = (char **) malloc(found * sizeof(char *));
 434         if (!oldEntries) {
 435                 DEBUG(1,("Failed to allocate space to store the old keytab entries (malloc failed?).\n"));
 436                 return ENOMEM;
 437         }
 438         memset(oldEntries, 0, found * sizeof(char *));
 439
 440         ret = krb5_kt_start_seq_get(context, keytab, &cursor);
 441         if (ret != KRB5_KT_END && ret != ENOENT ) {
 442                 while ((ret = krb5_kt_next_entry(context, keytab, &entry, &cursor)) == 0) {
 443                         if (entry.vno != kvno) {
 444                                 krb5_unparse_name(context, entry.principal, &ktprinc);
 445                                 for (i = 0; *(ktprinc + i); i++) {
 446                                         if (*(ktprinc + i) == '/') {
 447                                                 *(ktprinc + i) = (char) NULL;
 448                                                 break;
 449                                         }
 450                                 }
 451                                 for (i = 0; i < found; i++) {
 452                                         if (!oldEntries[i]) {
 453                                                 oldEntries[i] = ktprinc;
 454                                                 break;
 455                                         }
 456                                         if (!strcmp(oldEntries[i], ktprinc)) {
 457                                                 break;
 458                                         }
 459                                 }
 460                         }
 461                 }
 462                 for (i = 0; oldEntries[i]; i++) {
 463                         ret |= ads_keytab_add_entry(oldEntries[i], ads);
 464                         free(oldEntries[i]);
 465                 }
 466         }
 467         free(oldEntries);
 468
 469 done:
 470
 471         krb5_kt_close(context, keytab);
 472         return ret;
 473 }
 474 #endif /* HAVE_KRB5 */