source/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 2 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, write to the Free Software
  21    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22 */
  23
  24 #include "includes.h"
  25 #include "system/kerberos.h"
  26 #include "system/time.h"
  27 #include "system/network.h"
  28 #include "auth/kerberos/kerberos.h"
  29 #include "auth/auth.h"
  30
  31 struct principal_container {
  32         struct smb_krb5_context *smb_krb5_context;
  33         krb5_principal principal;
  34 };
  35
  36 static int free_principal(void *ptr) {
  37         struct principal_container *pc = ptr;
  38         /* current heimdal - 0.6.3, which we need anyway, fixes segfaults here */
  39         krb5_free_principal(pc->smb_krb5_context->krb5_context, pc->principal);
  40
  41         return 0;
  42 }
  43
  44 krb5_error_code salt_principal_from_credentials(TALLOC_CTX *parent_ctx,
  45                                                 struct cli_credentials *machine_account,
  46                                                 struct smb_krb5_context *smb_krb5_context,
  47                                                 krb5_principal *salt_princ)
  48 {
  49         krb5_error_code ret;
  50         char *machine_username;
  51         char *salt_body;
  52         char *lower_realm;
  53         const char *salt_principal;
  54         struct principal_container *mem_ctx = talloc(parent_ctx, struct principal_container);
  55         if (!mem_ctx) {
  56                 return ENOMEM;
  57         }
  58
  59         salt_principal = cli_credentials_get_salt_principal(machine_account);
  60         if (salt_principal) {
  61                 ret = krb5_parse_name(smb_krb5_context->krb5_context, salt_principal, salt_princ);
  62         } else {
  63                 machine_username = talloc_strdup(mem_ctx, cli_credentials_get_username(machine_account));
  64
  65                 if (!machine_username) {
  66                         talloc_free(mem_ctx);
  67                         return ENOMEM;
  68                 }
  69
  70                 if (machine_username[strlen(machine_username)-1] == '$') {
  71                         machine_username[strlen(machine_username)-1] = '\0';
  72                 }
  73                 lower_realm = strlower_talloc(mem_ctx, cli_credentials_get_realm(machine_account));
  74                 if (!lower_realm) {
  75                         talloc_free(mem_ctx);
  76                         return ENOMEM;
  77                 }
  78
  79                 salt_body = talloc_asprintf(mem_ctx, "%s.%s", machine_username,
  80                                             lower_realm);
  81                 if (!salt_body) {
  82                         talloc_free(mem_ctx);
  83                 return ENOMEM;
  84                 }
  85
  86                 ret = krb5_make_principal(smb_krb5_context->krb5_context, salt_princ,
  87                                           cli_credentials_get_realm(machine_account),
  88                                           "host", salt_body, NULL);
  89         }
  90
  91         if (ret == 0) {
  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 then use the principal from the client */
 119         if (!princ_string) {
 120                 talloc_free(mem_ctx);
 121                 princ = NULL;
 122                 return 0;
 123         }
 124
 125         ret = krb5_parse_name(smb_krb5_context->krb5_context,
 126                               princ_string, princ);
 127
 128         if (ret == 0) {
 129                 /* This song-and-dance effectivly puts the principal
 130                  * into talloc, so we can't loose it. */
 131                 mem_ctx->smb_krb5_context = talloc_reference(mem_ctx, smb_krb5_context);
 132                 mem_ctx->principal = *princ;
 133                 talloc_set_destructor(mem_ctx, free_principal);
 134         }
 135         return ret;
 136 }
 137
 138 /**
 139  * Return a freshly allocated ccache (destroyed by destructor on child
 140  * of parent_ctx), for a given set of client credentials
 141  */
 142
 143  krb5_error_code kinit_to_ccache(TALLOC_CTX *parent_ctx,
 144                                  struct cli_credentials *credentials,
 145                                  struct smb_krb5_context *smb_krb5_context,
 146                                  krb5_ccache ccache)
 147 {
 148         krb5_error_code ret;
 149         const char *password;
 150         time_t kdc_time = 0;
 151         krb5_principal princ;
 152
 153         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 154
 155         if (!mem_ctx) {
 156                 return ENOMEM;
 157         }
 158
 159         ret = principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &princ);
 160         if (ret) {
 161                 talloc_free(mem_ctx);
 162                 return ret;
 163         }
 164
 165         password = cli_credentials_get_password(credentials);
 166
 167         if (password) {
 168                 ret = kerberos_kinit_password_cc(smb_krb5_context->krb5_context, ccache,
 169                                                  princ,
 170                                                  password, NULL, &kdc_time);
 171         } else {
 172                 /* No password available, try to use a keyblock instead */
 173
 174                 krb5_keyblock keyblock;
 175                 const struct samr_Password *mach_pwd;
 176                 mach_pwd = cli_credentials_get_nt_hash(credentials, mem_ctx);
 177                 if (!mach_pwd) {
 178                         talloc_free(mem_ctx);
 179                         DEBUG(1, ("kinit_to_ccache: No password available for kinit\n"));
 180                         return EINVAL;
 181                 }
 182                 ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
 183                                          ENCTYPE_ARCFOUR_HMAC,
 184                                          mach_pwd->hash, sizeof(mach_pwd->hash),
 185                                          &keyblock);
 186
 187                 if (ret == 0) {
 188                         ret = kerberos_kinit_keyblock_cc(smb_krb5_context->krb5_context, ccache,
 189                                                          princ,
 190                                                          &keyblock, NULL, &kdc_time);
 191                         krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &keyblock);
 192                 }
 193         }
 194
 195         /* cope with ticket being in the future due to clock skew */
 196         if ((unsigned)kdc_time > time(NULL)) {
 197                 time_t t = time(NULL);
 198                 int time_offset =(unsigned)kdc_time-t;
 199                 DEBUG(4,("Advancing clock by %d seconds to cope with clock skew\n", time_offset));
 200                 krb5_set_real_time(smb_krb5_context->krb5_context, t + time_offset + 1, 0);
 201         }
 202
 203         if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
 204                 DEBUG(1,("kinit for %s failed (%s)\n",
 205                          cli_credentials_get_principal(credentials, mem_ctx),
 206                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 207                                                     ret, mem_ctx)));
 208                 talloc_free(mem_ctx);
 209                 return ret;
 210         }
 211         if (ret) {
 212                 DEBUG(1,("kinit for %s failed (%s)\n",
 213                          cli_credentials_get_principal(credentials, mem_ctx),
 214                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 215                                                     ret, mem_ctx)));
 216                 talloc_free(mem_ctx);
 217                 return ret;
 218         }
 219         return 0;
 220 }
 221
 222 static int free_keytab(void *ptr) {
 223         struct keytab_container *ktc = ptr;
 224         krb5_kt_close(ktc->smb_krb5_context->krb5_context, ktc->keytab);
 225
 226         return 0;
 227 }
 228
 229 int smb_krb5_open_keytab(TALLOC_CTX *mem_ctx,
 230                          struct smb_krb5_context *smb_krb5_context,
 231                          const char *keytab_name, struct keytab_container **ktc)
 232 {
 233         krb5_keytab keytab;
 234         int ret;
 235         ret = krb5_kt_resolve(smb_krb5_context->krb5_context, keytab_name, &keytab);
 236         if (ret) {
 237                 DEBUG(1,("failed to open krb5 keytab: %s\n",
 238                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 239                                                     ret, mem_ctx)));
 240                 return ret;
 241         }
 242
 243         *ktc = talloc(mem_ctx, struct keytab_container);
 244         if (!*ktc) {
 245                 return ENOMEM;
 246         }
 247
 248         (*ktc)->smb_krb5_context = talloc_reference(*ktc, smb_krb5_context);
 249         (*ktc)->keytab = keytab;
 250         talloc_set_destructor(*ktc, free_keytab);
 251
 252         return 0;
 253 }
 254
 255 struct enctypes_container {
 256         struct smb_krb5_context *smb_krb5_context;
 257         krb5_enctype *enctypes;
 258 };
 259
 260 static int free_enctypes(void *ptr) {
 261         struct enctypes_container *etc = ptr;
 262         free_kerberos_etypes(etc->smb_krb5_context->krb5_context, etc->enctypes);
 263         return 0;
 264 }
 265
 266 static krb5_error_code keytab_add_keys(TALLOC_CTX *parent_ctx,
 267                                        const char *princ_string,
 268                                        krb5_principal princ,
 269                                        krb5_principal salt_princ,
 270                                        int kvno,
 271                                        const char *password_s,
 272                                        struct smb_krb5_context *smb_krb5_context,
 273                                        krb5_keytab keytab)
 274 {
 275         int i;
 276         krb5_error_code ret;
 277         krb5_enctype *enctypes;
 278         char *enctype_string;
 279         struct enctypes_container *etc;
 280         krb5_data password;
 281         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 282         if (!mem_ctx) {
 283                 return ENOMEM;
 284         }
 285
 286         etc = talloc(mem_ctx, struct enctypes_container);
 287         if (!etc) {
 288                 talloc_free(mem_ctx);
 289                 return ENOMEM;
 290         }
 291         ret = get_kerberos_allowed_etypes(smb_krb5_context->krb5_context,
 292                                           &enctypes);
 293         if (ret != 0) {
 294                 DEBUG(1,("keytab_add_keys: getting encrption types failed (%s)\n",
 295                          error_message(ret)));
 296                 talloc_free(mem_ctx);
 297                 return ret;
 298         }
 299
 300         etc->smb_krb5_context = talloc_reference(etc, smb_krb5_context);
 301         etc->enctypes = enctypes;
 302
 303         talloc_set_destructor(etc, free_enctypes);
 304
 305         password.data = discard_const_p(char *, password_s);
 306         password.length = strlen(password_s);
 307
 308         for (i=0; enctypes[i]; i++) {
 309                 krb5_keytab_entry entry;
 310                 ret = create_kerberos_key_from_string(smb_krb5_context->krb5_context,
 311                                                       salt_princ, &password, &entry.keyblock, enctypes[i]);
 312                 if (ret != 0) {
 313                         talloc_free(mem_ctx);
 314                         return ret;
 315                 }
 316
 317                 entry.principal = princ;
 318                 entry.vno       = kvno;
 319                 ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
 320                 enctype_string = NULL;
 321                 krb5_enctype_to_string(smb_krb5_context->krb5_context, enctypes[i], &enctype_string);
 322                 if (ret != 0) {
 323                         DEBUG(1, ("Failed to add %s entry for %s(kvno %d) to keytab: %s\n",
 324                                   enctype_string,
 325                                   princ_string,
 326                                   kvno,
 327                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 328                                                              ret, mem_ctx)));
 329                         talloc_free(mem_ctx);
 330                         free(enctype_string);
 331                         krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 332                         return ret;
 333                 }
 334
 335                 DEBUG(5, ("Added %s(kvno %d) to keytab (%s)\n",
 336                           princ_string, kvno,
 337                           enctype_string));
 338                 free(enctype_string);
 339
 340                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 341         }
 342         talloc_free(mem_ctx);
 343         return 0;
 344 }
 345
 346 static int create_keytab(TALLOC_CTX *parent_ctx,
 347                          struct cli_credentials *machine_account,
 348                          struct smb_krb5_context *smb_krb5_context,
 349                          krb5_keytab keytab,
 350                          BOOL add_old)
 351 {
 352         krb5_error_code ret;
 353         const char *password_s;
 354         char *enctype_string;
 355         const char *old_secret;
 356         int kvno;
 357         krb5_principal salt_princ;
 358         krb5_principal princ;
 359         const char *princ_string;
 360
 361         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 362         if (!mem_ctx) {
 363                 return ENOMEM;
 364         }
 365
 366         princ_string = cli_credentials_get_principal(machine_account, mem_ctx);
 367         /* Get the principal we will store the new keytab entries under */
 368         ret = principal_from_credentials(mem_ctx, machine_account, smb_krb5_context, &princ);
 369         if (ret) {
 370                 DEBUG(1,("create_keytab: makeing krb5 principal failed (%s)\n",
 371                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 372                                                     ret, mem_ctx)));
 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                 /* If we don't have the plaintext password, try for
 393                  * the MD4 password hash */
 394
 395                 krb5_keytab_entry entry;
 396                 const struct samr_Password *mach_pwd;
 397                 mach_pwd = cli_credentials_get_nt_hash(machine_account, mem_ctx);
 398                 if (!mach_pwd) {
 399                         talloc_free(mem_ctx);
 400                         DEBUG(1, ("create_keytab: Domain trust informaton for account %s not available\n",
 401                                   cli_credentials_get_principal(machine_account, mem_ctx)));
 402                         return EINVAL;
 403                 }
 404                 ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
 405                                          ENCTYPE_ARCFOUR_HMAC,
 406                                          mach_pwd->hash, sizeof(mach_pwd->hash),
 407                                          &entry.keyblock);
 408                 if (ret) {
 409                         DEBUG(1, ("create_keytab: krb5_keyblock_init failed: %s\n",
 410                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 411                                                              ret, mem_ctx)));
 412                         return ret;
 413                 }
 414
 415                 entry.principal = princ;
 416                 entry.vno       = cli_credentials_get_kvno(machine_account);
 417                 ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
 418                 if (ret) {
 419                         DEBUG(1, ("Failed to add ARCFOUR_HMAC (only) entry for %s to keytab: %s",
 420                                   cli_credentials_get_principal(machine_account, mem_ctx),
 421                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 422                                                              ret, mem_ctx)));
 423                         talloc_free(mem_ctx);
 424                         krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 425                         return ret;
 426                 }
 427
 428                 krb5_enctype_to_string(smb_krb5_context->krb5_context, ENCTYPE_ARCFOUR_HMAC, &enctype_string);
 429                 DEBUG(5, ("Added %s(kvno %d) to keytab (%s)\n",
 430                           cli_credentials_get_principal(machine_account, mem_ctx),
 431                           cli_credentials_get_kvno(machine_account),
 432                           enctype_string));
 433                 free(enctype_string);
 434
 435                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 436
 437                 /* Can't go any further, we only have this one key */
 438                 talloc_free(mem_ctx);
 439                 return 0;
 440         }
 441
 442         kvno = cli_credentials_get_kvno(machine_account);
 443         /* good, we actually have the real plaintext */
 444         ret = keytab_add_keys(mem_ctx, princ_string, princ, salt_princ,
 445                               kvno, password_s, smb_krb5_context, 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, keytab);
 464         if (!ret) {
 465                 talloc_free(mem_ctx);
 466                 return ret;
 467         }
 468
 469         talloc_free(mem_ctx);
 470         return 0;
 471 }
 472
 473
 474 /*
 475  * Walk the keytab, looking for entries of this principal name, with KVNO other than current kvno -1.
 476  *
 477  * These entries are now stale, we only keep the current, and previous entries around.
 478  *
 479  * Inspired by the code in Samba3 for 'use kerberos keytab'.
 480  *
 481  */
 482
 483 static krb5_error_code remove_old_entries(TALLOC_CTX *parent_ctx,
 484                                           struct cli_credentials *machine_account,
 485                                           struct smb_krb5_context *smb_krb5_context,
 486                                           krb5_keytab keytab, BOOL *found_previous)
 487 {
 488         krb5_error_code ret, ret2;
 489         krb5_kt_cursor cursor;
 490         krb5_principal princ;
 491         int kvno;
 492         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 493         const char *princ_string;
 494         if (!mem_ctx) {
 495                 return ENOMEM;
 496         }
 497
 498         *found_previous = False;
 499         princ_string = cli_credentials_get_principal(machine_account, mem_ctx);
 500
 501         /* Get the principal we will store the new keytab entries under */
 502         ret = principal_from_credentials(mem_ctx, machine_account, smb_krb5_context, &princ);
 503         if (ret) {
 504                 DEBUG(1,("update_keytab: makeing krb5 principal failed (%s)\n",
 505                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 506                                                     ret, mem_ctx)));
 507                 talloc_free(mem_ctx);
 508                 return ret;
 509         }
 510
 511         kvno = cli_credentials_get_kvno(machine_account);
 512
 513         /* for each entry in the keytab */
 514         ret = krb5_kt_start_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 515         switch (ret) {
 516         case 0:
 517                 break;
 518         case ENOENT:
 519         case KRB5_KT_END:
 520                 /* no point enumerating if there isn't anything here */
 521                 talloc_free(mem_ctx);
 522                 return 0;
 523         default:
 524                 DEBUG(1,("failed to open keytab for read of old entries: %s\n",
 525                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 526                                                     ret, mem_ctx)));
 527                 talloc_free(mem_ctx);
 528                 return ret;
 529         }
 530
 531         while (!ret) {
 532                 krb5_keytab_entry entry;
 533                 ret = krb5_kt_next_entry(smb_krb5_context->krb5_context, keytab, &entry, &cursor);
 534                 if (ret) {
 535                         break;
 536                 }
 537                 /* if it matches our principal */
 538                 if (!krb5_kt_compare(smb_krb5_context->krb5_context, &entry, princ, 0, 0)) {
 539                         /* Free the entry, it wasn't the one we were looking for anyway */
 540                         krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 541                         continue;
 542                 }
 543
 544                 /* delete it, if it is not kvno -1 */
 545                 if (entry.vno != (kvno - 1 )) {
 546                         /* Release the enumeration.  We are going to
 547                          * have to start this from the top again,
 548                          * because deletes during enumeration may not
 549                          * always be consistant.
 550                          *
 551                          * Also, the enumeration locks the keytab
 552                          */
 553
 554                         krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 555
 556                         ret = krb5_kt_remove_entry(smb_krb5_context->krb5_context, keytab, &entry);
 557                         krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 558
 559                         /* Deleted: Restart from the top */
 560                         ret2 = krb5_kt_start_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 561                         if (ret2) {
 562                                 krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 563                                 DEBUG(1,("failed to restart enumeration of keytab: %s\n",
 564                                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 565                                                                     ret, mem_ctx)));
 566
 567                                 talloc_free(mem_ctx);
 568                                 return ret2;
 569                         }
 570
 571                         if (ret) {
 572                                 break;
 573                         }
 574
 575                 } else {
 576                         *found_previous = True;
 577                 }
 578
 579                 /* Free the entry, we don't need it any more */
 580                 krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 581
 582
 583         }
 584         krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 585
 586         switch (ret) {
 587         case 0:
 588                 break;
 589         case ENOENT:
 590         case KRB5_KT_END:
 591                 ret = 0;
 592                 break;
 593         default:
 594                 DEBUG(1,("failed in deleting old entries for principal: %s: %s\n",
 595                          princ_string,
 596                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 597                                                     ret, mem_ctx)));
 598         }
 599         talloc_free(mem_ctx);
 600         return ret;
 601 }
 602
 603 int smb_krb5_update_keytab(TALLOC_CTX *parent_ctx,
 604                            struct cli_credentials *machine_account,
 605                            struct smb_krb5_context *smb_krb5_context,
 606                            struct keytab_container *keytab_container)
 607 {
 608         krb5_error_code ret;
 609         BOOL found_previous;
 610         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 611         if (!mem_ctx) {
 612                 return ENOMEM;
 613         }
 614
 615         ret = remove_old_entries(mem_ctx, machine_account,
 616                                  smb_krb5_context, keytab_container->keytab, &found_previous);
 617         if (ret != 0) {
 618                 talloc_free(mem_ctx);
 619                 return ret;
 620         }
 621
 622         /* Create a new keytab.  If during the cleanout we found
 623          * entires for kvno -1, then don't try and duplicate them.
 624          * Otherwise, add kvno, and kvno -1 */
 625
 626         ret = create_keytab(mem_ctx, machine_account, smb_krb5_context,
 627                             keytab_container->keytab,
 628                             found_previous ? False : True);
 629         talloc_free(mem_ctx);
 630         return ret;
 631 }
 632
 633 int smb_krb5_create_memory_keytab(TALLOC_CTX *parent_ctx,
 634                                   struct cli_credentials *machine_account,
 635                                   struct smb_krb5_context *smb_krb5_context,
 636                                   struct keytab_container **keytab_container)
 637 {
 638         krb5_error_code ret;
 639         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 640         const char *rand_string;
 641         const char *keytab_name;
 642         if (!mem_ctx) {
 643                 return ENOMEM;
 644         }
 645
 646         *keytab_container = talloc(mem_ctx, struct keytab_container);
 647
 648         rand_string = generate_random_str(mem_ctx, 16);
 649         if (!rand_string) {
 650                 talloc_free(mem_ctx);
 651                 return ENOMEM;
 652         }
 653
 654         keytab_name = talloc_asprintf(mem_ctx, "MEMORY:%s",
 655                                       rand_string);
 656         if (!keytab_name) {
 657                 talloc_free(mem_ctx);
 658                 return ENOMEM;
 659         }
 660
 661         ret = smb_krb5_open_keytab(mem_ctx, smb_krb5_context, keytab_name, keytab_container);
 662         if (ret) {
 663                 return ret;
 664         }
 665
 666         ret = smb_krb5_update_keytab(mem_ctx, machine_account, smb_krb5_context, *keytab_container);
 667         if (ret == 0) {
 668                 talloc_steal(parent_ctx, *keytab_container);
 669         } else {
 670                 *keytab_container = NULL;
 671         }
 672         talloc_free(mem_ctx);
 673         return ret;
 674 }
 675