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 #include "auth/kerberos/kerberos_credentials.h"
  30
  31 struct principal_container {
  32         struct smb_krb5_context *smb_krb5_context;
  33         krb5_principal principal;
  34 };
  35
  36 static krb5_error_code free_principal(struct principal_container *pc)
  37 {
  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
  45 static krb5_error_code parse_principal(TALLOC_CTX *parent_ctx,
  46                                        const char *princ_string,
  47                                        struct smb_krb5_context *smb_krb5_context,
  48                                        krb5_principal *princ,
  49                                        const char **error_string)
  50 {
  51         int ret;
  52         struct principal_container *mem_ctx;
  53         if (princ_string == NULL) {
  54                  *princ = NULL;
  55                  return 0;
  56         }
  57
  58         ret = krb5_parse_name(smb_krb5_context->krb5_context,
  59                               princ_string, princ);
  60
  61         if (ret) {
  62                 (*error_string) = smb_get_krb5_error_message(smb_krb5_context->krb5_context, ret, parent_ctx);
  63                 return ret;
  64         }
  65
  66         mem_ctx = talloc(parent_ctx, struct principal_container);
  67         if (!mem_ctx) {
  68                 (*error_string) = error_message(ENOMEM);
  69                 return ENOMEM;
  70         }
  71
  72         /* This song-and-dance effectivly puts the principal
  73          * into talloc, so we can't loose it. */
  74         mem_ctx->smb_krb5_context = talloc_reference(mem_ctx, smb_krb5_context);
  75         mem_ctx->principal = *princ;
  76         talloc_set_destructor(mem_ctx, free_principal);
  77         return 0;
  78 }
  79
  80 static krb5_error_code salt_principal_from_credentials(TALLOC_CTX *parent_ctx,
  81                                                        struct cli_credentials *machine_account,
  82                                                        struct smb_krb5_context *smb_krb5_context,
  83                                                        krb5_principal *salt_princ)
  84 {
  85         krb5_error_code ret;
  86         char *machine_username;
  87         char *salt_body;
  88         char *lower_realm;
  89         const char *salt_principal;
  90         const char *error_string;
  91         struct principal_container *mem_ctx = talloc(parent_ctx, struct principal_container);
  92         if (!mem_ctx) {
  93                 return ENOMEM;
  94         }
  95
  96         salt_principal = cli_credentials_get_salt_principal(machine_account);
  97         if (salt_principal) {
  98                 ret = parse_principal(parent_ctx, salt_principal, smb_krb5_context, salt_princ, &error_string);
  99         } else {
 100                 machine_username = talloc_strdup(mem_ctx, cli_credentials_get_username(machine_account));
 101
 102                 if (!machine_username) {
 103                         talloc_free(mem_ctx);
 104                         return ENOMEM;
 105                 }
 106
 107                 if (machine_username[strlen(machine_username)-1] == '$') {
 108                         machine_username[strlen(machine_username)-1] = '\0';
 109                 }
 110                 lower_realm = strlower_talloc(mem_ctx, cli_credentials_get_realm(machine_account));
 111                 if (!lower_realm) {
 112                         talloc_free(mem_ctx);
 113                         return ENOMEM;
 114                 }
 115
 116                 salt_body = talloc_asprintf(mem_ctx, "%s.%s", machine_username,
 117                                             lower_realm);
 118                 if (!salt_body) {
 119                         talloc_free(mem_ctx);
 120                 return ENOMEM;
 121                 }
 122
 123                 ret = krb5_make_principal(smb_krb5_context->krb5_context, salt_princ,
 124                                           cli_credentials_get_realm(machine_account),
 125                                           "host", salt_body, NULL);
 126                 if (ret == 0) {
 127                         /* This song-and-dance effectivly puts the principal
 128                          * into talloc, so we can't loose it. */
 129                         mem_ctx->smb_krb5_context = talloc_reference(mem_ctx, smb_krb5_context);
 130                         mem_ctx->principal = *salt_princ;
 131                         talloc_set_destructor(mem_ctx, free_principal);
 132                 }
 133         }
 134
 135         return ret;
 136 }
 137
 138 /* Obtain the principal set on this context.  Requires a
 139  * smb_krb5_context because we are doing krb5 principal parsing with
 140  * the library routines.  The returned princ is placed in the talloc
 141  * system by means of a destructor (do *not* free). */
 142
 143  krb5_error_code principal_from_credentials(TALLOC_CTX *parent_ctx,
 144                                             struct cli_credentials *credentials,
 145                                             struct smb_krb5_context *smb_krb5_context,
 146                                             krb5_principal *princ,
 147                                             enum credentials_obtained *obtained,
 148                                             const char **error_string)
 149 {
 150         krb5_error_code ret;
 151         const char *princ_string;
 152         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 153         if (!mem_ctx) {
 154                 (*error_string) = error_message(ENOMEM);
 155                 return ENOMEM;
 156         }
 157         princ_string = cli_credentials_get_principal_and_obtained(credentials, mem_ctx, obtained);
 158         if (!princ_string) {
 159                 (*error_string) = error_message(ENOMEM);
 160                 return ENOMEM;
 161         }
 162
 163         ret = parse_principal(parent_ctx, princ_string,
 164                               smb_krb5_context, princ, error_string);
 165         talloc_free(mem_ctx);
 166         return ret;
 167 }
 168
 169 /* Obtain the principal set on this context.  Requires a
 170  * smb_krb5_context because we are doing krb5 principal parsing with
 171  * the library routines.  The returned princ is placed in the talloc
 172  * system by means of a destructor (do *not* free). */
 173
 174  krb5_error_code impersonate_principal_from_credentials(TALLOC_CTX *parent_ctx,
 175                                                         struct cli_credentials *credentials,
 176                                                         struct smb_krb5_context *smb_krb5_context,
 177                                                         krb5_principal *princ,
 178                                                         const char **error_string)
 179 {
 180         return parse_principal(parent_ctx, cli_credentials_get_impersonate_principal(credentials),
 181                                smb_krb5_context, princ, error_string);
 182 }
 183
 184 /**
 185  * Return a freshly allocated ccache (destroyed by destructor on child
 186  * of parent_ctx), for a given set of client credentials
 187  */
 188
 189  krb5_error_code kinit_to_ccache(TALLOC_CTX *parent_ctx,
 190                                  struct cli_credentials *credentials,
 191                                  struct smb_krb5_context *smb_krb5_context,
 192                                  krb5_ccache ccache,
 193                                  enum credentials_obtained *obtained,
 194                                  const char **error_string)
 195 {
 196         krb5_error_code ret;
 197         const char *password, *target_service;
 198         time_t kdc_time = 0;
 199         krb5_principal princ;
 200         krb5_principal impersonate_principal;
 201         int tries;
 202         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 203
 204         if (!mem_ctx) {
 205                 (*error_string) = strerror(ENOMEM);
 206                 return ENOMEM;
 207         }
 208
 209         ret = principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &princ, obtained, error_string);
 210         if (ret) {
 211                 talloc_free(mem_ctx);
 212                 return ret;
 213         }
 214
 215         ret = impersonate_principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &impersonate_principal, error_string);
 216         if (ret) {
 217                 talloc_free(mem_ctx);
 218                 return ret;
 219         }
 220
 221         target_service = cli_credentials_get_target_service(credentials);
 222
 223         password = cli_credentials_get_password(credentials);
 224
 225         tries = 2;
 226         while (tries--) {
 227                 if (password) {
 228                         ret = kerberos_kinit_password_cc(smb_krb5_context->krb5_context, ccache,
 229                                                          princ, password,
 230                                                          impersonate_principal, target_service,
 231                                                          NULL, &kdc_time);
 232                 } else if (impersonate_principal) {
 233                         (*error_string) = "INTERNAL error: Cannot impersonate principal with just a keyblock.  A password must be specified in the credentials";
 234                         return EINVAL;
 235                 } else {
 236                         /* No password available, try to use a keyblock instead */
 237
 238                         krb5_keyblock keyblock;
 239                         const struct samr_Password *mach_pwd;
 240                         mach_pwd = cli_credentials_get_nt_hash(credentials, mem_ctx);
 241                         if (!mach_pwd) {
 242                                 talloc_free(mem_ctx);
 243                                 (*error_string) = "kinit_to_ccache: No password available for kinit\n";
 244                                 return EINVAL;
 245                         }
 246                         ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
 247                                                  ENCTYPE_ARCFOUR_HMAC,
 248                                                  mach_pwd->hash, sizeof(mach_pwd->hash),
 249                                                  &keyblock);
 250
 251                         if (ret == 0) {
 252                                 ret = kerberos_kinit_keyblock_cc(smb_krb5_context->krb5_context, ccache,
 253                                                                  princ, &keyblock,
 254                                                                  target_service,
 255                                                                  NULL, &kdc_time);
 256                                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &keyblock);
 257                         }
 258                 }
 259
 260                 if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
 261                         /* Perhaps we have been given an invalid skew, so try again without it */
 262                         time_t t = time(NULL);
 263                         krb5_set_real_time(smb_krb5_context->krb5_context, t, 0);
 264                 } else {
 265                         /* not a skew problem */
 266                         break;
 267                 }
 268         }
 269
 270         if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
 271                 (*error_string) = talloc_asprintf(credentials, "kinit for %s failed (%s)\n",
 272                                                   cli_credentials_get_principal(credentials, mem_ctx),
 273                                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 274                                                                              ret, mem_ctx));
 275                 talloc_free(mem_ctx);
 276                 return ret;
 277         }
 278
 279         /* cope with ticket being in the future due to clock skew */
 280         if ((unsigned)kdc_time > time(NULL)) {
 281                 time_t t = time(NULL);
 282                 int time_offset =(unsigned)kdc_time-t;
 283                 DEBUG(4,("Advancing clock by %d seconds to cope with clock skew\n", time_offset));
 284                 krb5_set_real_time(smb_krb5_context->krb5_context, t + time_offset + 1, 0);
 285         }
 286
 287         if (ret == KRB5KDC_ERR_PREAUTH_FAILED && cli_credentials_wrong_password(credentials)) {
 288                 ret = kinit_to_ccache(parent_ctx,
 289                                       credentials,
 290                                       smb_krb5_context,
 291                                       ccache, obtained,
 292                                       error_string);
 293         }
 294         if (ret) {
 295                 (*error_string) = talloc_asprintf(credentials, "kinit for %s failed (%s)\n",
 296                                                   cli_credentials_get_principal(credentials, mem_ctx),
 297                                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 298                                                                              ret, mem_ctx));
 299                 talloc_free(mem_ctx);
 300                 return ret;
 301         }
 302         talloc_free(mem_ctx);
 303         return 0;
 304 }
 305
 306 static krb5_error_code free_keytab(struct keytab_container *ktc)
 307 {
 308         return krb5_kt_close(ktc->smb_krb5_context->krb5_context, ktc->keytab);
 309 }
 310
 311 krb5_error_code smb_krb5_open_keytab(TALLOC_CTX *mem_ctx,
 312                          struct smb_krb5_context *smb_krb5_context,
 313                          const char *keytab_name, struct keytab_container **ktc)
 314 {
 315         krb5_keytab keytab;
 316         krb5_error_code ret;
 317         ret = krb5_kt_resolve(smb_krb5_context->krb5_context, keytab_name, &keytab);
 318         if (ret) {
 319                 DEBUG(1,("failed to open krb5 keytab: %s\n",
 320                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 321                                                     ret, mem_ctx)));
 322                 return ret;
 323         }
 324
 325         *ktc = talloc(mem_ctx, struct keytab_container);
 326         if (!*ktc) {
 327                 return ENOMEM;
 328         }
 329
 330         (*ktc)->smb_krb5_context = talloc_reference(*ktc, smb_krb5_context);
 331         (*ktc)->keytab = keytab;
 332         talloc_set_destructor(*ktc, free_keytab);
 333
 334         return 0;
 335 }
 336
 337 static krb5_error_code keytab_add_keys(TALLOC_CTX *parent_ctx,
 338                                        const char *princ_string,
 339                                        krb5_principal princ,
 340                                        krb5_principal salt_princ,
 341                                        int kvno,
 342                                        const char *password_s,
 343                                        struct smb_krb5_context *smb_krb5_context,
 344                                        const char **enctype_strings,
 345                                        krb5_keytab keytab)
 346 {
 347         int i;
 348         krb5_error_code ret;
 349         krb5_data password;
 350         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 351         if (!mem_ctx) {
 352                 return ENOMEM;
 353         }
 354
 355         password.data = discard_const_p(char *, password_s);
 356         password.length = strlen(password_s);
 357
 358         for (i=0; enctype_strings[i]; i++) {
 359                 krb5_keytab_entry entry;
 360                 krb5_enctype enctype;
 361                 ret = krb5_string_to_enctype(smb_krb5_context->krb5_context, enctype_strings[i], &enctype);
 362                 if (ret != 0) {
 363                         DEBUG(1, ("Failed to interpret %s as a krb5 encryption type: %s\n",
 364                                   enctype_strings[i],
 365                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 366                                                              ret, mem_ctx)));
 367                         talloc_free(mem_ctx);
 368                         return ret;
 369                 }
 370                 ret = create_kerberos_key_from_string(smb_krb5_context->krb5_context,
 371                                                       salt_princ, &password, &entry.keyblock, enctype);
 372                 if (ret != 0) {
 373                         talloc_free(mem_ctx);
 374                         return ret;
 375                 }
 376
 377                 entry.principal = princ;
 378                 entry.vno       = kvno;
 379                 ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
 380                 if (ret != 0) {
 381                         DEBUG(1, ("Failed to add %s entry for %s(kvno %d) to keytab: %s\n",
 382                                   enctype_strings[i],
 383                                   princ_string,
 384                                   kvno,
 385                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 386                                                              ret, mem_ctx)));
 387                         talloc_free(mem_ctx);
 388                         krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 389                         return ret;
 390                 }
 391
 392                 DEBUG(5, ("Added %s(kvno %d) to keytab (%s)\n",
 393                           princ_string, kvno,
 394                           enctype_strings[i]));
 395
 396                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 397         }
 398         talloc_free(mem_ctx);
 399         return 0;
 400 }
 401
 402 static krb5_error_code create_keytab(TALLOC_CTX *parent_ctx,
 403                          struct cli_credentials *machine_account,
 404                          struct smb_krb5_context *smb_krb5_context,
 405                          const char **enctype_strings,
 406                          krb5_keytab keytab,
 407                          bool add_old)
 408 {
 409         krb5_error_code ret;
 410         const char *password_s;
 411         const char *old_secret;
 412         int kvno;
 413         krb5_principal salt_princ;
 414         krb5_principal princ;
 415         const char *princ_string;
 416         const char *error_string;
 417         enum credentials_obtained obtained;
 418
 419         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 420         if (!mem_ctx) {
 421                 return ENOMEM;
 422         }
 423
 424         princ_string = cli_credentials_get_principal(machine_account, mem_ctx);
 425         /* Get the principal we will store the new keytab entries under */
 426         ret = principal_from_credentials(mem_ctx, machine_account, smb_krb5_context, &princ, &obtained, &error_string);
 427         if (ret) {
 428                 DEBUG(1,("create_keytab: makeing krb5 principal failed (%s)\n", error_string));
 429                 talloc_free(mem_ctx);
 430                 return ret;
 431         }
 432
 433         /* The salt used to generate these entries may be different however, fetch that */
 434         ret = salt_principal_from_credentials(mem_ctx, machine_account,
 435                                               smb_krb5_context,
 436                                               &salt_princ);
 437         if (ret) {
 438                 DEBUG(1,("create_keytab: makeing salt principal failed (%s)\n",
 439                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 440                                                     ret, mem_ctx)));
 441                 talloc_free(mem_ctx);
 442                 return ret;
 443         }
 444
 445         /* Finally, do the dance to get the password to put in the entry */
 446         password_s = cli_credentials_get_password(machine_account);
 447         if (!password_s) {
 448                 krb5_keytab_entry entry;
 449                 const struct samr_Password *mach_pwd;
 450
 451                 if (!str_list_check(enctype_strings, "arcfour-hmac-md5")) {
 452                         DEBUG(1, ("Asked to create keytab, but with only an NT hash supplied, "
 453                                   "but not listing arcfour-hmac-md5 as an enc type to include in the keytab!\n"));
 454                         talloc_free(mem_ctx);
 455                         return EINVAL;
 456                 }
 457
 458                 /* If we don't have the plaintext password, try for
 459                  * the MD4 password hash */
 460                 mach_pwd = cli_credentials_get_nt_hash(machine_account, mem_ctx);
 461                 if (!mach_pwd) {
 462                         /* OK, nothing to do here */
 463                         talloc_free(mem_ctx);
 464                         return 0;
 465                 }
 466                 ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
 467                                          ETYPE_ARCFOUR_HMAC_MD5,
 468                                          mach_pwd->hash, sizeof(mach_pwd->hash),
 469                                          &entry.keyblock);
 470                 if (ret) {
 471                         DEBUG(1, ("create_keytab: krb5_keyblock_init failed: %s\n",
 472                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 473                                                              ret, mem_ctx)));
 474                         talloc_free(mem_ctx);
 475                         return ret;
 476                 }
 477
 478                 entry.principal = princ;
 479                 entry.vno       = cli_credentials_get_kvno(machine_account);
 480                 ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
 481                 if (ret) {
 482                         DEBUG(1, ("Failed to add ARCFOUR_HMAC (only) entry for %s to keytab: %s",
 483                                   cli_credentials_get_principal(machine_account, mem_ctx),
 484                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 485                                                              ret, mem_ctx)));
 486                         talloc_free(mem_ctx);
 487                         krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 488                         return ret;
 489                 }
 490
 491                 DEBUG(5, ("Added %s(kvno %d) to keytab (arcfour-hmac-md5)\n",
 492                           cli_credentials_get_principal(machine_account, mem_ctx),
 493                           cli_credentials_get_kvno(machine_account)));
 494
 495                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 496
 497                 /* Can't go any further, we only have this one key */
 498                 talloc_free(mem_ctx);
 499                 return 0;
 500         }
 501
 502         kvno = cli_credentials_get_kvno(machine_account);
 503         /* good, we actually have the real plaintext */
 504         ret = keytab_add_keys(mem_ctx, princ_string, princ, salt_princ,
 505                               kvno, password_s, smb_krb5_context,
 506                               enctype_strings, keytab);
 507         if (!ret) {
 508                 talloc_free(mem_ctx);
 509                 return ret;
 510         }
 511
 512         if (!add_old || kvno == 0) {
 513                 talloc_free(mem_ctx);
 514                 return 0;
 515         }
 516
 517         old_secret = cli_credentials_get_old_password(machine_account);
 518         if (!old_secret) {
 519                 talloc_free(mem_ctx);
 520                 return 0;
 521         }
 522
 523         ret = keytab_add_keys(mem_ctx, princ_string, princ, salt_princ,
 524                               kvno - 1, old_secret, smb_krb5_context,
 525                               enctype_strings, keytab);
 526         if (!ret) {
 527                 talloc_free(mem_ctx);
 528                 return ret;
 529         }
 530
 531         talloc_free(mem_ctx);
 532         return 0;
 533 }
 534
 535
 536 /*
 537  * Walk the keytab, looking for entries of this principal name, with KVNO other than current kvno -1.
 538  *
 539  * These entries are now stale, we only keep the current, and previous entries around.
 540  *
 541  * Inspired by the code in Samba3 for 'use kerberos keytab'.
 542  *
 543  */
 544
 545 static krb5_error_code remove_old_entries(TALLOC_CTX *parent_ctx,
 546                                           struct cli_credentials *machine_account,
 547                                           struct smb_krb5_context *smb_krb5_context,
 548                                           krb5_keytab keytab, bool *found_previous)
 549 {
 550         krb5_error_code ret, ret2;
 551         krb5_kt_cursor cursor;
 552         krb5_principal princ;
 553         int kvno;
 554         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 555         const char *princ_string;
 556         const char *error_string;
 557         enum credentials_obtained obtained;
 558
 559         if (!mem_ctx) {
 560                 return ENOMEM;
 561         }
 562
 563         *found_previous = false;
 564         princ_string = cli_credentials_get_principal(machine_account, mem_ctx);
 565
 566         /* Get the principal we will store the new keytab entries under */
 567         ret = principal_from_credentials(mem_ctx, machine_account, smb_krb5_context, &princ, &obtained, &error_string);
 568         if (ret) {
 569                 DEBUG(1,("update_keytab: makeing krb5 principal failed (%s)\n", error_string));
 570                 talloc_free(mem_ctx);
 571                 return ret;
 572         }
 573
 574         kvno = cli_credentials_get_kvno(machine_account);
 575
 576         /* for each entry in the keytab */
 577         ret = krb5_kt_start_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 578         switch (ret) {
 579         case 0:
 580                 break;
 581         case HEIM_ERR_OPNOTSUPP:
 582         case ENOENT:
 583         case KRB5_KT_END:
 584                 /* no point enumerating if there isn't anything here */
 585                 talloc_free(mem_ctx);
 586                 return 0;
 587         default:
 588                 DEBUG(1,("failed to open keytab for read of old entries: %s\n",
 589                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 590                                                     ret, mem_ctx)));
 591                 talloc_free(mem_ctx);
 592                 return ret;
 593         }
 594
 595         while (!ret) {
 596                 krb5_keytab_entry entry;
 597                 ret = krb5_kt_next_entry(smb_krb5_context->krb5_context, keytab, &entry, &cursor);
 598                 if (ret) {
 599                         break;
 600                 }
 601                 /* if it matches our principal */
 602                 if (!krb5_kt_compare(smb_krb5_context->krb5_context, &entry, princ, 0, 0)) {
 603                         /* Free the entry, it wasn't the one we were looking for anyway */
 604                         krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 605                         continue;
 606                 }
 607
 608                 /* delete it, if it is not kvno -1 */
 609                 if (entry.vno != (kvno - 1 )) {
 610                         /* Release the enumeration.  We are going to
 611                          * have to start this from the top again,
 612                          * because deletes during enumeration may not
 613                          * always be consistant.
 614                          *
 615                          * Also, the enumeration locks a FILE: keytab
 616                          */
 617
 618                         krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 619
 620                         ret = krb5_kt_remove_entry(smb_krb5_context->krb5_context, keytab, &entry);
 621                         krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 622
 623                         /* Deleted: Restart from the top */
 624                         ret2 = krb5_kt_start_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 625                         if (ret2) {
 626                                 krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 627                                 DEBUG(1,("failed to restart enumeration of keytab: %s\n",
 628                                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 629                                                                     ret, mem_ctx)));
 630
 631                                 talloc_free(mem_ctx);
 632                                 return ret2;
 633                         }
 634
 635                         if (ret) {
 636                                 break;
 637                         }
 638
 639                 } else {
 640                         *found_previous = true;
 641                 }
 642
 643                 /* Free the entry, we don't need it any more */
 644                 krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 645
 646
 647         }
 648         krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 649
 650         switch (ret) {
 651         case 0:
 652                 break;
 653         case ENOENT:
 654         case KRB5_KT_END:
 655                 ret = 0;
 656                 break;
 657         default:
 658                 DEBUG(1,("failed in deleting old entries for principal: %s: %s\n",
 659                          princ_string,
 660                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 661                                                     ret, mem_ctx)));
 662         }
 663         talloc_free(mem_ctx);
 664         return ret;
 665 }
 666
 667 krb5_error_code smb_krb5_update_keytab(TALLOC_CTX *parent_ctx,
 668                            struct cli_credentials *machine_account,
 669                            struct smb_krb5_context *smb_krb5_context,
 670                            const char **enctype_strings,
 671                            struct keytab_container *keytab_container)
 672 {
 673         krb5_error_code ret;
 674         bool found_previous;
 675         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 676         if (!mem_ctx) {
 677                 return ENOMEM;
 678         }
 679
 680         ret = remove_old_entries(mem_ctx, machine_account,
 681                                  smb_krb5_context, keytab_container->keytab, &found_previous);
 682         if (ret != 0) {
 683                 talloc_free(mem_ctx);
 684                 return ret;
 685         }
 686
 687         /* Create a new keytab.  If during the cleanout we found
 688          * entires for kvno -1, then don't try and duplicate them.
 689          * Otherwise, add kvno, and kvno -1 */
 690
 691         ret = create_keytab(mem_ctx, machine_account, smb_krb5_context,
 692                             enctype_strings,
 693                             keytab_container->keytab,
 694                             found_previous ? false : true);
 695         talloc_free(mem_ctx);
 696         return ret;
 697 }
 698
 699 krb5_error_code smb_krb5_create_memory_keytab(TALLOC_CTX *parent_ctx,
 700                                            struct cli_credentials *machine_account,
 701                                            struct smb_krb5_context *smb_krb5_context,
 702                                            const char **enctype_strings,
 703                                            struct keytab_container **keytab_container)
 704 {
 705         krb5_error_code ret;
 706         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 707         const char *rand_string;
 708         const char *keytab_name;
 709         if (!mem_ctx) {
 710                 return ENOMEM;
 711         }
 712
 713         *keytab_container = talloc(mem_ctx, struct keytab_container);
 714
 715         rand_string = generate_random_str(mem_ctx, 16);
 716         if (!rand_string) {
 717                 talloc_free(mem_ctx);
 718                 return ENOMEM;
 719         }
 720
 721         keytab_name = talloc_asprintf(mem_ctx, "MEMORY:%s",
 722                                       rand_string);
 723         if (!keytab_name) {
 724                 talloc_free(mem_ctx);
 725                 return ENOMEM;
 726         }
 727
 728         ret = smb_krb5_open_keytab(mem_ctx, smb_krb5_context, keytab_name, keytab_container);
 729         if (ret) {
 730                 return ret;
 731         }
 732
 733         ret = smb_krb5_update_keytab(mem_ctx, machine_account, smb_krb5_context, enctype_strings, *keytab_container);
 734         if (ret == 0) {
 735                 talloc_steal(parent_ctx, *keytab_container);
 736         } else {
 737                 *keytab_container = NULL;
 738         }
 739         talloc_free(mem_ctx);
 740         return ret;
 741 }
 742