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_proto.h"
  28 #include "auth/credentials/credentials_krb5.h"
  29
  30 struct principal_container {
  31         struct smb_krb5_context *smb_krb5_context;
  32         krb5_principal principal;
  33 };
  34
  35 static krb5_error_code free_principal(struct principal_container *pc)
  36 {
  37         /* current heimdal - 0.6.3, which we need anyway, fixes segfaults here */
  38         krb5_free_principal(pc->smb_krb5_context->krb5_context, pc->principal);
  39
  40         return 0;
  41 }
  42
  43 static krb5_error_code salt_principal_from_credentials(TALLOC_CTX *parent_ctx,
  44                                                        struct cli_credentials *machine_account,
  45                                                        struct smb_krb5_context *smb_krb5_context,
  46                                                        krb5_principal *salt_princ)
  47 {
  48         krb5_error_code ret;
  49         char *machine_username;
  50         char *salt_body;
  51         char *lower_realm;
  52         const char *salt_principal;
  53         struct principal_container *mem_ctx = talloc(parent_ctx, struct principal_container);
  54         if (!mem_ctx) {
  55                 return ENOMEM;
  56         }
  57
  58         salt_principal = cli_credentials_get_salt_principal(machine_account);
  59         if (salt_principal) {
  60                 ret = krb5_parse_name(smb_krb5_context->krb5_context, salt_principal, salt_princ);
  61         } else {
  62                 machine_username = talloc_strdup(mem_ctx, cli_credentials_get_username(machine_account));
  63
  64                 if (!machine_username) {
  65                         talloc_free(mem_ctx);
  66                         return ENOMEM;
  67                 }
  68
  69                 if (machine_username[strlen(machine_username)-1] == '$') {
  70                         machine_username[strlen(machine_username)-1] = '\0';
  71                 }
  72                 lower_realm = strlower_talloc(mem_ctx, cli_credentials_get_realm(machine_account));
  73                 if (!lower_realm) {
  74                         talloc_free(mem_ctx);
  75                         return ENOMEM;
  76                 }
  77
  78                 salt_body = talloc_asprintf(mem_ctx, "%s.%s", machine_username,
  79                                             lower_realm);
  80                 if (!salt_body) {
  81                         talloc_free(mem_ctx);
  82                 return ENOMEM;
  83                 }
  84
  85                 ret = krb5_make_principal(smb_krb5_context->krb5_context, salt_princ,
  86                                           cli_credentials_get_realm(machine_account),
  87                                           "host", salt_body, NULL);
  88         }
  89
  90         if (ret == 0) {
  91                 /* This song-and-dance effectivly puts the principal
  92                  * into talloc, so we can't loose it. */
  93                 mem_ctx->smb_krb5_context = talloc_reference(mem_ctx, smb_krb5_context);
  94                 mem_ctx->principal = *salt_princ;
  95                 talloc_set_destructor(mem_ctx, free_principal);
  96         }
  97         return ret;
  98 }
  99
 100 /* Obtain the principal set on this context.  Requires a
 101  * smb_krb5_context because we are doing krb5 principal parsing with
 102  * the library routines.  The returned princ is placed in the talloc
 103  * system by means of a destructor (do *not* free). */
 104
 105  krb5_error_code principal_from_credentials(TALLOC_CTX *parent_ctx,
 106                                             struct cli_credentials *credentials,
 107                                             struct smb_krb5_context *smb_krb5_context,
 108                                             krb5_principal *princ,
 109                                             const char **error_string)
 110 {
 111         krb5_error_code ret;
 112         const char *princ_string;
 113         struct principal_container *mem_ctx = talloc(parent_ctx, struct principal_container);
 114         if (!mem_ctx) {
 115                 (*error_string) = error_message(ENOMEM);
 116                 return ENOMEM;
 117         }
 118
 119         princ_string = cli_credentials_get_principal(credentials, mem_ctx);
 120
 121         /* A NULL here has meaning, as the gssapi server case will
 122          * then use the principal from the client */
 123         if (!princ_string) {
 124                 talloc_free(mem_ctx);
 125                 princ = NULL;
 126                 return 0;
 127         }
 128
 129         ret = krb5_parse_name(smb_krb5_context->krb5_context,
 130                               princ_string, princ);
 131
 132         if (ret) {
 133                 (*error_string) = smb_get_krb5_error_message(smb_krb5_context->krb5_context, ret, parent_ctx);
 134                 return ret;
 135         }
 136
 137         /* This song-and-dance effectivly puts the principal
 138          * into talloc, so we can't loose it. */
 139         mem_ctx->smb_krb5_context = talloc_reference(mem_ctx, smb_krb5_context);
 140         mem_ctx->principal = *princ;
 141         talloc_set_destructor(mem_ctx, free_principal);
 142         return 0;
 143 }
 144
 145 /**
 146  * Return a freshly allocated ccache (destroyed by destructor on child
 147  * of parent_ctx), for a given set of client credentials
 148  */
 149
 150  krb5_error_code kinit_to_ccache(TALLOC_CTX *parent_ctx,
 151                                  struct cli_credentials *credentials,
 152                                  struct smb_krb5_context *smb_krb5_context,
 153                                  krb5_ccache ccache,
 154                                  const char **error_string)
 155 {
 156         krb5_error_code ret;
 157         const char *password;
 158         time_t kdc_time = 0;
 159         krb5_principal princ;
 160         int tries;
 161         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 162
 163         if (!mem_ctx) {
 164                 (*error_string) = strerror(ENOMEM);
 165                 return ENOMEM;
 166         }
 167
 168         ret = principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &princ, error_string);
 169         if (ret) {
 170                 talloc_free(mem_ctx);
 171                 return ret;
 172         }
 173
 174         password = cli_credentials_get_password(credentials);
 175
 176         tries = 2;
 177         while (tries--) {
 178                 if (password) {
 179                         ret = kerberos_kinit_password_cc(smb_krb5_context->krb5_context, ccache,
 180                                                          princ,
 181                                                          password, NULL, &kdc_time);
 182                 } else {
 183                         /* No password available, try to use a keyblock instead */
 184
 185                         krb5_keyblock keyblock;
 186                         const struct samr_Password *mach_pwd;
 187                         mach_pwd = cli_credentials_get_nt_hash(credentials, mem_ctx);
 188                         if (!mach_pwd) {
 189                                 talloc_free(mem_ctx);
 190                                 (*error_string) = "kinit_to_ccache: No password available for kinit\n";
 191                                 return EINVAL;
 192                         }
 193                         ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
 194                                                  ENCTYPE_ARCFOUR_HMAC,
 195                                                  mach_pwd->hash, sizeof(mach_pwd->hash),
 196                                                  &keyblock);
 197
 198                         if (ret == 0) {
 199                                 ret = kerberos_kinit_keyblock_cc(smb_krb5_context->krb5_context, ccache,
 200                                                                  princ,
 201                                                                  &keyblock, NULL, &kdc_time);
 202                                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &keyblock);
 203                         }
 204                 }
 205
 206                 if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
 207                         /* Perhaps we have been given an invalid skew, so try again without it */
 208                         time_t t = time(NULL);
 209                         krb5_set_real_time(smb_krb5_context->krb5_context, t, 0);
 210                 } else {
 211                         /* not a skew problem */
 212                         break;
 213                 }
 214         }
 215
 216         if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
 217                 (*error_string) = talloc_asprintf(credentials, "kinit for %s failed (%s)\n",
 218                                                   cli_credentials_get_principal(credentials, mem_ctx),
 219                                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 220                                                                              ret, mem_ctx));
 221                 talloc_free(mem_ctx);
 222                 return ret;
 223         }
 224
 225         /* cope with ticket being in the future due to clock skew */
 226         if ((unsigned)kdc_time > time(NULL)) {
 227                 time_t t = time(NULL);
 228                 int time_offset =(unsigned)kdc_time-t;
 229                 DEBUG(4,("Advancing clock by %d seconds to cope with clock skew\n", time_offset));
 230                 krb5_set_real_time(smb_krb5_context->krb5_context, t + time_offset + 1, 0);
 231         }
 232
 233         if (ret == KRB5KDC_ERR_PREAUTH_FAILED && cli_credentials_wrong_password(credentials)) {
 234                 ret = kinit_to_ccache(parent_ctx,
 235                                       credentials,
 236                                       smb_krb5_context,
 237                                       ccache, error_string);
 238         }
 239         if (ret) {
 240                 (*error_string) = talloc_asprintf(credentials, "kinit for %s failed (%s)\n",
 241                                                   cli_credentials_get_principal(credentials, mem_ctx),
 242                                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 243                                                                              ret, mem_ctx));
 244                 talloc_free(mem_ctx);
 245                 return ret;
 246         }
 247         talloc_free(mem_ctx);
 248         return 0;
 249 }
 250
 251 static krb5_error_code free_keytab(struct keytab_container *ktc)
 252 {
 253         return krb5_kt_close(ktc->smb_krb5_context->krb5_context, ktc->keytab);
 254 }
 255
 256 krb5_error_code smb_krb5_open_keytab(TALLOC_CTX *mem_ctx,
 257                          struct smb_krb5_context *smb_krb5_context,
 258                          const char *keytab_name, struct keytab_container **ktc)
 259 {
 260         krb5_keytab keytab;
 261         krb5_error_code ret;
 262         ret = krb5_kt_resolve(smb_krb5_context->krb5_context, keytab_name, &keytab);
 263         if (ret) {
 264                 DEBUG(1,("failed to open krb5 keytab: %s\n",
 265                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 266                                                     ret, mem_ctx)));
 267                 return ret;
 268         }
 269
 270         *ktc = talloc(mem_ctx, struct keytab_container);
 271         if (!*ktc) {
 272                 return ENOMEM;
 273         }
 274
 275         (*ktc)->smb_krb5_context = talloc_reference(*ktc, smb_krb5_context);
 276         (*ktc)->keytab = keytab;
 277         talloc_set_destructor(*ktc, free_keytab);
 278
 279         return 0;
 280 }
 281
 282 static krb5_error_code keytab_add_keys(TALLOC_CTX *parent_ctx,
 283                                        const char *princ_string,
 284                                        krb5_principal princ,
 285                                        krb5_principal salt_princ,
 286                                        int kvno,
 287                                        const char *password_s,
 288                                        struct smb_krb5_context *smb_krb5_context,
 289                                        const char **enctype_strings,
 290                                        krb5_keytab keytab)
 291 {
 292         int i;
 293         krb5_error_code ret;
 294         krb5_data password;
 295         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 296         if (!mem_ctx) {
 297                 return ENOMEM;
 298         }
 299
 300         password.data = discard_const_p(char *, password_s);
 301         password.length = strlen(password_s);
 302
 303         for (i=0; enctype_strings[i]; i++) {
 304                 krb5_keytab_entry entry;
 305                 krb5_enctype enctype;
 306                 ret = krb5_string_to_enctype(smb_krb5_context->krb5_context, enctype_strings[i], &enctype);
 307                 if (ret != 0) {
 308                         DEBUG(1, ("Failed to interpret %s as a krb5 encryption type: %s\n",
 309                                   enctype_strings[i],
 310                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 311                                                              ret, mem_ctx)));
 312                         talloc_free(mem_ctx);
 313                         return ret;
 314                 }
 315                 ret = create_kerberos_key_from_string(smb_krb5_context->krb5_context,
 316                                                       salt_princ, &password, &entry.keyblock, enctype);
 317                 if (ret != 0) {
 318                         talloc_free(mem_ctx);
 319                         return ret;
 320                 }
 321
 322                 entry.principal = princ;
 323                 entry.vno       = kvno;
 324                 ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
 325                 if (ret != 0) {
 326                         DEBUG(1, ("Failed to add %s entry for %s(kvno %d) to keytab: %s\n",
 327                                   enctype_strings[i],
 328                                   princ_string,
 329                                   kvno,
 330                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 331                                                              ret, mem_ctx)));
 332                         talloc_free(mem_ctx);
 333                         krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 334                         return ret;
 335                 }
 336
 337                 DEBUG(5, ("Added %s(kvno %d) to keytab (%s)\n",
 338                           princ_string, kvno,
 339                           enctype_strings[i]));
 340
 341                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 342         }
 343         talloc_free(mem_ctx);
 344         return 0;
 345 }
 346
 347 static krb5_error_code create_keytab(TALLOC_CTX *parent_ctx,
 348                          struct cli_credentials *machine_account,
 349                          struct smb_krb5_context *smb_krb5_context,
 350                          const char **enctype_strings,
 351                          krb5_keytab keytab,
 352                          bool add_old)
 353 {
 354         krb5_error_code ret;
 355         const char *password_s;
 356         const char *old_secret;
 357         int kvno;
 358         krb5_principal salt_princ;
 359         krb5_principal princ;
 360         const char *princ_string;
 361         const char *error_string;
 362
 363         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 364         if (!mem_ctx) {
 365                 return ENOMEM;
 366         }
 367
 368         princ_string = cli_credentials_get_principal(machine_account, mem_ctx);
 369         /* Get the principal we will store the new keytab entries under */
 370         ret = principal_from_credentials(mem_ctx, machine_account, smb_krb5_context, &princ, &error_string);
 371         if (ret) {
 372                 DEBUG(1,("create_keytab: makeing krb5 principal failed (%s)\n", error_string));
 373                 talloc_free(mem_ctx);
 374                 return ret;
 375         }
 376
 377         /* The salt used to generate these entries may be different however, fetch that */
 378         ret = salt_principal_from_credentials(mem_ctx, machine_account,
 379                                               smb_krb5_context,
 380                                               &salt_princ);
 381         if (ret) {
 382                 DEBUG(1,("create_keytab: makeing salt principal failed (%s)\n",
 383                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 384                                                     ret, mem_ctx)));
 385                 talloc_free(mem_ctx);
 386                 return ret;
 387         }
 388
 389         /* Finally, do the dance to get the password to put in the entry */
 390         password_s = cli_credentials_get_password(machine_account);
 391         if (!password_s) {
 392                 krb5_keytab_entry entry;
 393                 const struct samr_Password *mach_pwd;
 394
 395                 if (!str_list_check(enctype_strings, "arcfour-hmac-md5")) {
 396                         DEBUG(1, ("Asked to create keytab, but with only an NT hash supplied, "
 397                                   "but not listing arcfour-hmac-md5 as an enc type to include in the keytab!\n"));
 398                         talloc_free(mem_ctx);
 399                         return EINVAL;
 400                 }
 401
 402                 /* If we don't have the plaintext password, try for
 403                  * the MD4 password hash */
 404                 mach_pwd = cli_credentials_get_nt_hash(machine_account, mem_ctx);
 405                 if (!mach_pwd) {
 406                         /* OK, nothing to do here */
 407                         talloc_free(mem_ctx);
 408                         return 0;
 409                 }
 410                 ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
 411                                          ETYPE_ARCFOUR_HMAC_MD5,
 412                                          mach_pwd->hash, sizeof(mach_pwd->hash),
 413                                          &entry.keyblock);
 414                 if (ret) {
 415                         DEBUG(1, ("create_keytab: krb5_keyblock_init failed: %s\n",
 416                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 417                                                              ret, mem_ctx)));
 418                         talloc_free(mem_ctx);
 419                         return ret;
 420                 }
 421
 422                 entry.principal = princ;
 423                 entry.vno       = cli_credentials_get_kvno(machine_account);
 424                 ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
 425                 if (ret) {
 426                         DEBUG(1, ("Failed to add ARCFOUR_HMAC (only) entry for %s to keytab: %s",
 427                                   cli_credentials_get_principal(machine_account, mem_ctx),
 428                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 429                                                              ret, mem_ctx)));
 430                         talloc_free(mem_ctx);
 431                         krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 432                         return ret;
 433                 }
 434
 435                 DEBUG(5, ("Added %s(kvno %d) to keytab (arcfour-hmac-md5)\n",
 436                           cli_credentials_get_principal(machine_account, mem_ctx),
 437                           cli_credentials_get_kvno(machine_account)));
 438
 439                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 440
 441                 /* Can't go any further, we only have this one key */
 442                 talloc_free(mem_ctx);
 443                 return 0;
 444         }
 445
 446         kvno = cli_credentials_get_kvno(machine_account);
 447         /* good, we actually have the real plaintext */
 448         ret = keytab_add_keys(mem_ctx, princ_string, princ, salt_princ,
 449                               kvno, password_s, smb_krb5_context,
 450                               enctype_strings, keytab);
 451         if (!ret) {
 452                 talloc_free(mem_ctx);
 453                 return ret;
 454         }
 455
 456         if (!add_old || kvno == 0) {
 457                 talloc_free(mem_ctx);
 458                 return 0;
 459         }
 460
 461         old_secret = cli_credentials_get_old_password(machine_account);
 462         if (!old_secret) {
 463                 talloc_free(mem_ctx);
 464                 return 0;
 465         }
 466
 467         ret = keytab_add_keys(mem_ctx, princ_string, princ, salt_princ,
 468                               kvno - 1, old_secret, smb_krb5_context,
 469                               enctype_strings, keytab);
 470         if (!ret) {
 471                 talloc_free(mem_ctx);
 472                 return ret;
 473         }
 474
 475         talloc_free(mem_ctx);
 476         return 0;
 477 }
 478
 479
 480 /*
 481  * Walk the keytab, looking for entries of this principal name, with KVNO other than current kvno -1.
 482  *
 483  * These entries are now stale, we only keep the current, and previous entries around.
 484  *
 485  * Inspired by the code in Samba3 for 'use kerberos keytab'.
 486  *
 487  */
 488
 489 static krb5_error_code remove_old_entries(TALLOC_CTX *parent_ctx,
 490                                           struct cli_credentials *machine_account,
 491                                           struct smb_krb5_context *smb_krb5_context,
 492                                           krb5_keytab keytab, bool *found_previous)
 493 {
 494         krb5_error_code ret, ret2;
 495         krb5_kt_cursor cursor;
 496         krb5_principal princ;
 497         int kvno;
 498         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 499         const char *princ_string;
 500         const char *error_string;
 501
 502         if (!mem_ctx) {
 503                 return ENOMEM;
 504         }
 505
 506         *found_previous = false;
 507         princ_string = cli_credentials_get_principal(machine_account, mem_ctx);
 508
 509         /* Get the principal we will store the new keytab entries under */
 510         ret = principal_from_credentials(mem_ctx, machine_account, smb_krb5_context, &princ, &error_string);
 511         if (ret) {
 512                 DEBUG(1,("update_keytab: makeing krb5 principal failed (%s)\n", error_string));
 513                 talloc_free(mem_ctx);
 514                 return ret;
 515         }
 516
 517         kvno = cli_credentials_get_kvno(machine_account);
 518
 519         /* for each entry in the keytab */
 520         ret = krb5_kt_start_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 521         switch (ret) {
 522         case 0:
 523                 break;
 524         case HEIM_ERR_OPNOTSUPP:
 525         case ENOENT:
 526         case KRB5_KT_END:
 527                 /* no point enumerating if there isn't anything here */
 528                 talloc_free(mem_ctx);
 529                 return 0;
 530         default:
 531                 DEBUG(1,("failed to open keytab for read of old entries: %s\n",
 532                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 533                                                     ret, mem_ctx)));
 534                 talloc_free(mem_ctx);
 535                 return ret;
 536         }
 537
 538         while (!ret) {
 539                 krb5_keytab_entry entry;
 540                 ret = krb5_kt_next_entry(smb_krb5_context->krb5_context, keytab, &entry, &cursor);
 541                 if (ret) {
 542                         break;
 543                 }
 544                 /* if it matches our principal */
 545                 if (!krb5_kt_compare(smb_krb5_context->krb5_context, &entry, princ, 0, 0)) {
 546                         /* Free the entry, it wasn't the one we were looking for anyway */
 547                         krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 548                         continue;
 549                 }
 550
 551                 /* delete it, if it is not kvno -1 */
 552                 if (entry.vno != (kvno - 1 )) {
 553                         /* Release the enumeration.  We are going to
 554                          * have to start this from the top again,
 555                          * because deletes during enumeration may not
 556                          * always be consistant.
 557                          *
 558                          * Also, the enumeration locks a FILE: keytab
 559                          */
 560
 561                         krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 562
 563                         ret = krb5_kt_remove_entry(smb_krb5_context->krb5_context, keytab, &entry);
 564                         krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 565
 566                         /* Deleted: Restart from the top */
 567                         ret2 = krb5_kt_start_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 568                         if (ret2) {
 569                                 krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 570                                 DEBUG(1,("failed to restart enumeration of keytab: %s\n",
 571                                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 572                                                                     ret, mem_ctx)));
 573
 574                                 talloc_free(mem_ctx);
 575                                 return ret2;
 576                         }
 577
 578                         if (ret) {
 579                                 break;
 580                         }
 581
 582                 } else {
 583                         *found_previous = true;
 584                 }
 585
 586                 /* Free the entry, we don't need it any more */
 587                 krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 588
 589
 590         }
 591         krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 592
 593         switch (ret) {
 594         case 0:
 595                 break;
 596         case ENOENT:
 597         case KRB5_KT_END:
 598                 ret = 0;
 599                 break;
 600         default:
 601                 DEBUG(1,("failed in deleting old entries for principal: %s: %s\n",
 602                          princ_string,
 603                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 604                                                     ret, mem_ctx)));
 605         }
 606         talloc_free(mem_ctx);
 607         return ret;
 608 }
 609
 610 krb5_error_code smb_krb5_update_keytab(TALLOC_CTX *parent_ctx,
 611                            struct cli_credentials *machine_account,
 612                            struct smb_krb5_context *smb_krb5_context,
 613                            const char **enctype_strings,
 614                            struct keytab_container *keytab_container)
 615 {
 616         krb5_error_code ret;
 617         bool found_previous;
 618         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 619         if (!mem_ctx) {
 620                 return ENOMEM;
 621         }
 622
 623         ret = remove_old_entries(mem_ctx, machine_account,
 624                                  smb_krb5_context, keytab_container->keytab, &found_previous);
 625         if (ret != 0) {
 626                 talloc_free(mem_ctx);
 627                 return ret;
 628         }
 629
 630         /* Create a new keytab.  If during the cleanout we found
 631          * entires for kvno -1, then don't try and duplicate them.
 632          * Otherwise, add kvno, and kvno -1 */
 633
 634         ret = create_keytab(mem_ctx, machine_account, smb_krb5_context,
 635                             enctype_strings,
 636                             keytab_container->keytab,
 637                             found_previous ? false : true);
 638         talloc_free(mem_ctx);
 639         return ret;
 640 }
 641
 642 krb5_error_code smb_krb5_create_memory_keytab(TALLOC_CTX *parent_ctx,
 643                                            struct cli_credentials *machine_account,
 644                                            struct smb_krb5_context *smb_krb5_context,
 645                                            const char **enctype_strings,
 646                                            struct keytab_container **keytab_container)
 647 {
 648         krb5_error_code ret;
 649         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 650         const char *rand_string;
 651         const char *keytab_name;
 652         if (!mem_ctx) {
 653                 return ENOMEM;
 654         }
 655
 656         *keytab_container = talloc(mem_ctx, struct keytab_container);
 657
 658         rand_string = generate_random_str(mem_ctx, 16);
 659         if (!rand_string) {
 660                 talloc_free(mem_ctx);
 661                 return ENOMEM;
 662         }
 663
 664         keytab_name = talloc_asprintf(mem_ctx, "MEMORY:%s",
 665                                       rand_string);
 666         if (!keytab_name) {
 667                 talloc_free(mem_ctx);
 668                 return ENOMEM;
 669         }
 670
 671         ret = smb_krb5_open_keytab(mem_ctx, smb_krb5_context, keytab_name, keytab_container);
 672         if (ret) {
 673                 return ret;
 674         }
 675
 676         ret = smb_krb5_update_keytab(mem_ctx, machine_account, smb_krb5_context, enctype_strings, *keytab_container);
 677         if (ret == 0) {
 678                 talloc_steal(parent_ctx, *keytab_container);
 679         } else {
 680                 *keytab_container = NULL;
 681         }
 682         talloc_free(mem_ctx);
 683         return ret;
 684 }
 685