source4/auth/kerberos/kerberos_util.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Kerberos utility functions for GENSEC
   5
   6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2004-2005
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21 */
  22
  23 #include "includes.h"
  24 #include "system/kerberos.h"
  25 #include "auth/kerberos/kerberos.h"
  26 #include "auth/credentials/credentials.h"
  27 #include "auth/credentials/credentials_krb5.h"
  28
  29 struct principal_container {
  30         struct smb_krb5_context *smb_krb5_context;
  31         krb5_principal principal;
  32 };
  33
  34 static int free_principal(struct principal_container *pc)
  35 {
  36         /* current heimdal - 0.6.3, which we need anyway, fixes segfaults here */
  37         krb5_free_principal(pc->smb_krb5_context->krb5_context, pc->principal);
  38
  39         return 0;
  40 }
  41
  42 static krb5_error_code salt_principal_from_credentials(TALLOC_CTX *parent_ctx,
  43                                                        struct cli_credentials *machine_account,
  44                                                        struct smb_krb5_context *smb_krb5_context,
  45                                                        krb5_principal *salt_princ)
  46 {
  47         krb5_error_code ret;
  48         char *machine_username;
  49         char *salt_body;
  50         char *lower_realm;
  51         const char *salt_principal;
  52         struct principal_container *mem_ctx = talloc(parent_ctx, struct principal_container);
  53         if (!mem_ctx) {
  54                 return ENOMEM;
  55         }
  56
  57         salt_principal = cli_credentials_get_salt_principal(machine_account);
  58         if (salt_principal) {
  59                 ret = krb5_parse_name(smb_krb5_context->krb5_context, salt_principal, salt_princ);
  60         } else {
  61                 machine_username = talloc_strdup(mem_ctx, cli_credentials_get_username(machine_account));
  62
  63                 if (!machine_username) {
  64                         talloc_free(mem_ctx);
  65                         return ENOMEM;
  66                 }
  67
  68                 if (machine_username[strlen(machine_username)-1] == '$') {
  69                         machine_username[strlen(machine_username)-1] = '\0';
  70                 }
  71                 lower_realm = strlower_talloc(mem_ctx, cli_credentials_get_realm(machine_account));
  72                 if (!lower_realm) {
  73                         talloc_free(mem_ctx);
  74                         return ENOMEM;
  75                 }
  76
  77                 salt_body = talloc_asprintf(mem_ctx, "%s.%s", machine_username,
  78                                             lower_realm);
  79                 if (!salt_body) {
  80                         talloc_free(mem_ctx);
  81                 return ENOMEM;
  82                 }
  83
  84                 ret = krb5_make_principal(smb_krb5_context->krb5_context, salt_princ,
  85                                           cli_credentials_get_realm(machine_account),
  86                                           "host", salt_body, NULL);
  87         }
  88
  89         if (ret == 0) {
  90                 /* This song-and-dance effectivly puts the principal
  91                  * into talloc, so we can't loose it. */
  92                 mem_ctx->smb_krb5_context = talloc_reference(mem_ctx, smb_krb5_context);
  93                 mem_ctx->principal = *salt_princ;
  94                 talloc_set_destructor(mem_ctx, free_principal);
  95         }
  96         return ret;
  97 }
  98
  99 /* Obtain the principal set on this context.  Requires a
 100  * smb_krb5_context because we are doing krb5 principal parsing with
 101  * the library routines.  The returned princ is placed in the talloc
 102  * system by means of a destructor (do *not* free). */
 103
 104 krb5_error_code principal_from_credentials(TALLOC_CTX *parent_ctx,
 105                                            struct cli_credentials *credentials,
 106                                            struct smb_krb5_context *smb_krb5_context,
 107                                            krb5_principal *princ)
 108 {
 109         krb5_error_code ret;
 110         const char *princ_string;
 111         struct principal_container *mem_ctx = talloc(parent_ctx, struct principal_container);
 112         if (!mem_ctx) {
 113                 return ENOMEM;
 114         }
 115
 116         princ_string = cli_credentials_get_principal(credentials, mem_ctx);
 117
 118         /* A NULL here has meaning, as the gssapi server case will
 119          * then use the principal from the client */
 120         if (!princ_string) {
 121                 talloc_free(mem_ctx);
 122                 princ = NULL;
 123                 return 0;
 124         }
 125
 126         ret = krb5_parse_name(smb_krb5_context->krb5_context,
 127                               princ_string, princ);
 128
 129         if (ret == 0) {
 130                 /* This song-and-dance effectivly puts the principal
 131                  * into talloc, so we can't loose it. */
 132                 mem_ctx->smb_krb5_context = talloc_reference(mem_ctx, smb_krb5_context);
 133                 mem_ctx->principal = *princ;
 134                 talloc_set_destructor(mem_ctx, free_principal);
 135         }
 136         return ret;
 137 }
 138
 139 /**
 140  * Return a freshly allocated ccache (destroyed by destructor on child
 141  * of parent_ctx), for a given set of client credentials
 142  */
 143
 144  krb5_error_code kinit_to_ccache(TALLOC_CTX *parent_ctx,
 145                                  struct cli_credentials *credentials,
 146                                  struct smb_krb5_context *smb_krb5_context,
 147                                  krb5_ccache ccache)
 148 {
 149         krb5_error_code ret;
 150         const char *password;
 151         time_t kdc_time = 0;
 152         krb5_principal princ;
 153         int tries;
 154         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 155
 156         if (!mem_ctx) {
 157                 return ENOMEM;
 158         }
 159
 160         ret = principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &princ);
 161         if (ret) {
 162                 talloc_free(mem_ctx);
 163                 return ret;
 164         }
 165
 166         password = cli_credentials_get_password(credentials);
 167
 168         tries = 2;
 169         while (tries--) {
 170                 if (password) {
 171                         ret = kerberos_kinit_password_cc(smb_krb5_context->krb5_context, ccache,
 172                                                          princ,
 173                                                          password, NULL, &kdc_time);
 174                 } else {
 175                         /* No password available, try to use a keyblock instead */
 176
 177                         krb5_keyblock keyblock;
 178                         const struct samr_Password *mach_pwd;
 179                         mach_pwd = cli_credentials_get_nt_hash(credentials, mem_ctx);
 180                         if (!mach_pwd) {
 181                                 talloc_free(mem_ctx);
 182                                 DEBUG(1, ("kinit_to_ccache: No password available for kinit\n"));
 183                                 return EINVAL;
 184                         }
 185                         ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
 186                                                  ETYPE_ARCFOUR_HMAC_MD5,
 187                                                  mach_pwd->hash, sizeof(mach_pwd->hash),
 188                                                  &keyblock);
 189
 190                         if (ret == 0) {
 191                                 ret = kerberos_kinit_keyblock_cc(smb_krb5_context->krb5_context, ccache,
 192                                                                  princ,
 193                                                                  &keyblock, NULL, &kdc_time);
 194                                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &keyblock);
 195                         }
 196                 }
 197
 198                 if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
 199                         /* Perhaps we have been given an invalid skew, so try again without it */
 200                         time_t t = time(NULL);
 201                         krb5_set_real_time(smb_krb5_context->krb5_context, t, 0);
 202                 } else {
 203                         /* not a skew problem */
 204                         break;
 205                 }
 206         }
 207
 208         if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
 209                 DEBUG(1,("kinit for %s failed (%s)\n",
 210                          cli_credentials_get_principal(credentials, mem_ctx),
 211                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 212                                                     ret, mem_ctx)));
 213                 talloc_free(mem_ctx);
 214                 return ret;
 215         }
 216
 217         /* cope with ticket being in the future due to clock skew */
 218         if ((unsigned)kdc_time > time(NULL)) {
 219                 time_t t = time(NULL);
 220                 int time_offset =(unsigned)kdc_time-t;
 221                 DEBUG(4,("Advancing clock by %d seconds to cope with clock skew\n", time_offset));
 222                 krb5_set_real_time(smb_krb5_context->krb5_context, t + time_offset + 1, 0);
 223         }
 224
 225         if (ret == KRB5KDC_ERR_PREAUTH_FAILED && cli_credentials_wrong_password(credentials)) {
 226                 ret = kinit_to_ccache(parent_ctx,
 227                                       credentials,
 228                                       smb_krb5_context,
 229                                       ccache);
 230         }
 231         if (ret) {
 232                 DEBUG(1,("kinit for %s failed (%s)\n",
 233                          cli_credentials_get_principal(credentials, mem_ctx),
 234                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 235                                                     ret, mem_ctx)));
 236                 talloc_free(mem_ctx);
 237                 return ret;
 238         }
 239         talloc_free(mem_ctx);
 240         return 0;
 241 }
 242
 243 static int free_keytab(struct keytab_container *ktc)
 244 {
 245         krb5_kt_close(ktc->smb_krb5_context->krb5_context, ktc->keytab);
 246
 247         return 0;
 248 }
 249
 250 int smb_krb5_open_keytab(TALLOC_CTX *mem_ctx,
 251                          struct smb_krb5_context *smb_krb5_context,
 252                          const char *keytab_name, struct keytab_container **ktc)
 253 {
 254         krb5_keytab keytab;
 255         int ret;
 256         ret = krb5_kt_resolve(smb_krb5_context->krb5_context, keytab_name, &keytab);
 257         if (ret) {
 258                 DEBUG(1,("failed to open krb5 keytab: %s\n",
 259                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 260                                                     ret, mem_ctx)));
 261                 return ret;
 262         }
 263
 264         *ktc = talloc(mem_ctx, struct keytab_container);
 265         if (!*ktc) {
 266                 return ENOMEM;
 267         }
 268
 269         (*ktc)->smb_krb5_context = talloc_reference(*ktc, smb_krb5_context);
 270         (*ktc)->keytab = keytab;
 271         talloc_set_destructor(*ktc, free_keytab);
 272
 273         return 0;
 274 }
 275
 276 static krb5_error_code keytab_add_keys(TALLOC_CTX *parent_ctx,
 277                                        const char *princ_string,
 278                                        krb5_principal princ,
 279                                        krb5_principal salt_princ,
 280                                        int kvno,
 281                                        const char *password_s,
 282                                        struct smb_krb5_context *smb_krb5_context,
 283                                        const char **enctype_strings,
 284                                        krb5_keytab keytab)
 285 {
 286         int i;
 287         krb5_error_code ret;
 288         krb5_data password;
 289         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 290         if (!mem_ctx) {
 291                 return ENOMEM;
 292         }
 293
 294         password.data = discard_const_p(char *, password_s);
 295         password.length = strlen(password_s);
 296
 297         for (i=0; enctype_strings[i]; i++) {
 298                 krb5_keytab_entry entry;
 299                 krb5_enctype enctype;
 300                 ret = krb5_string_to_enctype(smb_krb5_context->krb5_context, enctype_strings[i], &enctype);
 301                 if (ret != 0) {
 302                         DEBUG(1, ("Failed to interpret %s as a krb5 encryption type: %s\n",
 303                                   enctype_strings[i],
 304                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 305                                                              ret, mem_ctx)));
 306                         talloc_free(mem_ctx);
 307                         return ret;
 308                 }
 309                 ret = create_kerberos_key_from_string(smb_krb5_context->krb5_context,
 310                                                       salt_princ, &password, &entry.keyblock, enctype);
 311                 if (ret != 0) {
 312                         talloc_free(mem_ctx);
 313                         return ret;
 314                 }
 315
 316                 entry.principal = princ;
 317                 entry.vno       = kvno;
 318                 ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
 319                 if (ret != 0) {
 320                         DEBUG(1, ("Failed to add %s entry for %s(kvno %d) to keytab: %s\n",
 321                                   enctype_strings[i],
 322                                   princ_string,
 323                                   kvno,
 324                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 325                                                              ret, mem_ctx)));
 326                         talloc_free(mem_ctx);
 327                         krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 328                         return ret;
 329                 }
 330
 331                 DEBUG(5, ("Added %s(kvno %d) to keytab (%s)\n",
 332                           princ_string, kvno,
 333                           enctype_strings[i]));
 334
 335                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 336         }
 337         talloc_free(mem_ctx);
 338         return 0;
 339 }
 340
 341 static int create_keytab(TALLOC_CTX *parent_ctx,
 342                          struct cli_credentials *machine_account,
 343                          struct smb_krb5_context *smb_krb5_context,
 344                          const char **enctype_strings,
 345                          krb5_keytab keytab,
 346                          BOOL add_old)
 347 {
 348         krb5_error_code ret;
 349         const char *password_s;
 350         const char *old_secret;
 351         int kvno;
 352         krb5_principal salt_princ;
 353         krb5_principal princ;
 354         const char *princ_string;
 355
 356         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 357         if (!mem_ctx) {
 358                 return ENOMEM;
 359         }
 360
 361         princ_string = cli_credentials_get_principal(machine_account, mem_ctx);
 362         /* Get the principal we will store the new keytab entries under */
 363         ret = principal_from_credentials(mem_ctx, machine_account, smb_krb5_context, &princ);
 364         if (ret) {
 365                 DEBUG(1,("create_keytab: makeing krb5 principal failed (%s)\n",
 366                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 367                                                     ret, mem_ctx)));
 368                 talloc_free(mem_ctx);
 369                 return ret;
 370         }
 371
 372         /* The salt used to generate these entries may be different however, fetch that */
 373         ret = salt_principal_from_credentials(mem_ctx, machine_account,
 374                                               smb_krb5_context,
 375                                               &salt_princ);
 376         if (ret) {
 377                 DEBUG(1,("create_keytab: makeing salt principal failed (%s)\n",
 378                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 379                                                     ret, mem_ctx)));
 380                 talloc_free(mem_ctx);
 381                 return ret;
 382         }
 383
 384         /* Finally, do the dance to get the password to put in the entry */
 385         password_s = cli_credentials_get_password(machine_account);
 386         if (!password_s) {
 387                 krb5_keytab_entry entry;
 388                 const struct samr_Password *mach_pwd;
 389
 390                 if (!str_list_check(enctype_strings, "arcfour-hmac-md5")) {
 391                         DEBUG(1, ("Asked to create keytab, but with only an NT hash supplied, "
 392                                   "but not listing arcfour-hmac-md5 as an enc type to include in the keytab!\n"));
 393                         talloc_free(mem_ctx);
 394                         return EINVAL;
 395                 }
 396
 397                 /* If we don't have the plaintext password, try for
 398                  * the MD4 password hash */
 399                 mach_pwd = cli_credentials_get_nt_hash(machine_account, mem_ctx);
 400                 if (!mach_pwd) {
 401                         /* OK, nothing to do here */
 402                         talloc_free(mem_ctx);
 403                         return 0;
 404                 }
 405                 ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
 406                                          ETYPE_ARCFOUR_HMAC_MD5,
 407                                          mach_pwd->hash, sizeof(mach_pwd->hash),
 408                                          &entry.keyblock);
 409                 if (ret) {
 410                         DEBUG(1, ("create_keytab: krb5_keyblock_init failed: %s\n",
 411                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 412                                                              ret, mem_ctx)));
 413                         talloc_free(mem_ctx);
 414                         return ret;
 415                 }
 416
 417                 entry.principal = princ;
 418                 entry.vno       = cli_credentials_get_kvno(machine_account);
 419                 ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
 420                 if (ret) {
 421                         DEBUG(1, ("Failed to add ARCFOUR_HMAC (only) entry for %s to keytab: %s",
 422                                   cli_credentials_get_principal(machine_account, mem_ctx),
 423                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 424                                                              ret, mem_ctx)));
 425                         talloc_free(mem_ctx);
 426                         krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 427                         return ret;
 428                 }
 429
 430                 DEBUG(5, ("Added %s(kvno %d) to keytab (arcfour-hmac-md5)\n",
 431                           cli_credentials_get_principal(machine_account, mem_ctx),
 432                           cli_credentials_get_kvno(machine_account)));
 433
 434                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 435
 436                 /* Can't go any further, we only have this one key */
 437                 talloc_free(mem_ctx);
 438                 return 0;
 439         }
 440
 441         kvno = cli_credentials_get_kvno(machine_account);
 442         /* good, we actually have the real plaintext */
 443         ret = keytab_add_keys(mem_ctx, princ_string, princ, salt_princ,
 444                               kvno, password_s, smb_krb5_context,
 445                               enctype_strings, keytab);
 446         if (!ret) {
 447                 talloc_free(mem_ctx);
 448                 return ret;
 449         }
 450
 451         if (!add_old || kvno == 0) {
 452                 talloc_free(mem_ctx);
 453                 return 0;
 454         }
 455
 456         old_secret = cli_credentials_get_old_password(machine_account);
 457         if (!old_secret) {
 458                 talloc_free(mem_ctx);
 459                 return 0;
 460         }
 461
 462         ret = keytab_add_keys(mem_ctx, princ_string, princ, salt_princ,
 463                               kvno - 1, old_secret, smb_krb5_context,
 464                               enctype_strings, keytab);
 465         if (!ret) {
 466                 talloc_free(mem_ctx);
 467                 return ret;
 468         }
 469
 470         talloc_free(mem_ctx);
 471         return 0;
 472 }
 473
 474
 475 /*
 476  * Walk the keytab, looking for entries of this principal name, with KVNO other than current kvno -1.
 477  *
 478  * These entries are now stale, we only keep the current, and previous entries around.
 479  *
 480  * Inspired by the code in Samba3 for 'use kerberos keytab'.
 481  *
 482  */
 483
 484 static krb5_error_code remove_old_entries(TALLOC_CTX *parent_ctx,
 485                                           struct cli_credentials *machine_account,
 486                                           struct smb_krb5_context *smb_krb5_context,
 487                                           krb5_keytab keytab, BOOL *found_previous)
 488 {
 489         krb5_error_code ret, ret2;
 490         krb5_kt_cursor cursor;
 491         krb5_principal princ;
 492         int kvno;
 493         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 494         const char *princ_string;
 495         if (!mem_ctx) {
 496                 return ENOMEM;
 497         }
 498
 499         *found_previous = False;
 500         princ_string = cli_credentials_get_principal(machine_account, mem_ctx);
 501
 502         /* Get the principal we will store the new keytab entries under */
 503         ret = principal_from_credentials(mem_ctx, machine_account, smb_krb5_context, &princ);
 504         if (ret) {
 505                 DEBUG(1,("update_keytab: makeing krb5 principal failed (%s)\n",
 506                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 507                                                     ret, mem_ctx)));
 508                 talloc_free(mem_ctx);
 509                 return ret;
 510         }
 511
 512         kvno = cli_credentials_get_kvno(machine_account);
 513
 514         /* for each entry in the keytab */
 515         ret = krb5_kt_start_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 516         switch (ret) {
 517         case 0:
 518                 break;
 519         case HEIM_ERR_OPNOTSUPP:
 520         case ENOENT:
 521         case KRB5_KT_END:
 522                 /* no point enumerating if there isn't anything here */
 523                 talloc_free(mem_ctx);
 524                 return 0;
 525         default:
 526                 DEBUG(1,("failed to open keytab for read of old entries: %s\n",
 527                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 528                                                     ret, mem_ctx)));
 529                 talloc_free(mem_ctx);
 530                 return ret;
 531         }
 532
 533         while (!ret) {
 534                 krb5_keytab_entry entry;
 535                 ret = krb5_kt_next_entry(smb_krb5_context->krb5_context, keytab, &entry, &cursor);
 536                 if (ret) {
 537                         break;
 538                 }
 539                 /* if it matches our principal */
 540                 if (!krb5_kt_compare(smb_krb5_context->krb5_context, &entry, princ, 0, 0)) {
 541                         /* Free the entry, it wasn't the one we were looking for anyway */
 542                         krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 543                         continue;
 544                 }
 545
 546                 /* delete it, if it is not kvno -1 */
 547                 if (entry.vno != (kvno - 1 )) {
 548                         /* Release the enumeration.  We are going to
 549                          * have to start this from the top again,
 550                          * because deletes during enumeration may not
 551                          * always be consistant.
 552                          *
 553                          * Also, the enumeration locks a FILE: keytab
 554                          */
 555
 556                         krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 557
 558                         ret = krb5_kt_remove_entry(smb_krb5_context->krb5_context, keytab, &entry);
 559                         krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 560
 561                         /* Deleted: Restart from the top */
 562                         ret2 = krb5_kt_start_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 563                         if (ret2) {
 564                                 krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 565                                 DEBUG(1,("failed to restart enumeration of keytab: %s\n",
 566                                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 567                                                                     ret, mem_ctx)));
 568
 569                                 talloc_free(mem_ctx);
 570                                 return ret2;
 571                         }
 572
 573                         if (ret) {
 574                                 break;
 575                         }
 576
 577                 } else {
 578                         *found_previous = True;
 579                 }
 580
 581                 /* Free the entry, we don't need it any more */
 582                 krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 583
 584
 585         }
 586         krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 587
 588         switch (ret) {
 589         case 0:
 590                 break;
 591         case ENOENT:
 592         case KRB5_KT_END:
 593                 ret = 0;
 594                 break;
 595         default:
 596                 DEBUG(1,("failed in deleting old entries for principal: %s: %s\n",
 597                          princ_string,
 598                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 599                                                     ret, mem_ctx)));
 600         }
 601         talloc_free(mem_ctx);
 602         return ret;
 603 }
 604
 605 int smb_krb5_update_keytab(TALLOC_CTX *parent_ctx,
 606                            struct cli_credentials *machine_account,
 607                            struct smb_krb5_context *smb_krb5_context,
 608                            const char **enctype_strings,
 609                            struct keytab_container *keytab_container)
 610 {
 611         krb5_error_code ret;
 612         BOOL found_previous;
 613         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 614         if (!mem_ctx) {
 615                 return ENOMEM;
 616         }
 617
 618         ret = remove_old_entries(mem_ctx, machine_account,
 619                                  smb_krb5_context, keytab_container->keytab, &found_previous);
 620         if (ret != 0) {
 621                 talloc_free(mem_ctx);
 622                 return ret;
 623         }
 624
 625         /* Create a new keytab.  If during the cleanout we found
 626          * entires for kvno -1, then don't try and duplicate them.
 627          * Otherwise, add kvno, and kvno -1 */
 628
 629         ret = create_keytab(mem_ctx, machine_account, smb_krb5_context,
 630                             enctype_strings,
 631                             keytab_container->keytab,
 632                             found_previous ? False : True);
 633         talloc_free(mem_ctx);
 634         return ret;
 635 }
 636
 637 _PUBLIC_ int smb_krb5_create_memory_keytab(TALLOC_CTX *parent_ctx,
 638                                            struct cli_credentials *machine_account,
 639                                            struct smb_krb5_context *smb_krb5_context,
 640                                            const char **enctype_strings,
 641                                            struct keytab_container **keytab_container)
 642 {
 643         krb5_error_code ret;
 644         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 645         const char *rand_string;
 646         const char *keytab_name;
 647         if (!mem_ctx) {
 648                 return ENOMEM;
 649         }
 650
 651         *keytab_container = talloc(mem_ctx, struct keytab_container);
 652
 653         rand_string = generate_random_str(mem_ctx, 16);
 654         if (!rand_string) {
 655                 talloc_free(mem_ctx);
 656                 return ENOMEM;
 657         }
 658
 659         keytab_name = talloc_asprintf(mem_ctx, "MEMORY:%s",
 660                                       rand_string);
 661         if (!keytab_name) {
 662                 talloc_free(mem_ctx);
 663                 return ENOMEM;
 664         }
 665
 666         ret = smb_krb5_open_keytab(mem_ctx, smb_krb5_context, keytab_name, keytab_container);
 667         if (ret) {
 668                 return ret;
 669         }
 670
 671         ret = smb_krb5_update_keytab(mem_ctx, machine_account, smb_krb5_context, enctype_strings, *keytab_container);
 672         if (ret == 0) {
 673                 talloc_steal(parent_ctx, *keytab_container);
 674         } else {
 675                 *keytab_container = NULL;
 676         }
 677         talloc_free(mem_ctx);
 678         return ret;
 679 }
 680