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 #include "auth/kerberos/kerberos_util.h"
  31 #include <ldb.h>
  32 #include "param/secrets.h"
  33
  34 struct principal_container {
  35         struct smb_krb5_context *smb_krb5_context;
  36         krb5_principal principal;
  37         const char *string_form; /* Optional */
  38 };
  39
  40 static krb5_error_code free_principal(struct principal_container *pc)
  41 {
  42         /* current heimdal - 0.6.3, which we need anyway, fixes segfaults here */
  43         krb5_free_principal(pc->smb_krb5_context->krb5_context, pc->principal);
  44
  45         return 0;
  46 }
  47
  48
  49 static krb5_error_code parse_principal(TALLOC_CTX *parent_ctx,
  50                                        const char *princ_string,
  51                                        struct smb_krb5_context *smb_krb5_context,
  52                                        krb5_principal *princ,
  53                                        const char **error_string)
  54 {
  55         int ret;
  56         struct principal_container *mem_ctx;
  57         if (princ_string == NULL) {
  58                  *princ = NULL;
  59                  return 0;
  60         }
  61
  62         ret = krb5_parse_name(smb_krb5_context->krb5_context,
  63                               princ_string, princ);
  64
  65         if (ret) {
  66                 (*error_string) = smb_get_krb5_error_message(smb_krb5_context->krb5_context, ret, parent_ctx);
  67                 return ret;
  68         }
  69
  70         mem_ctx = talloc(parent_ctx, struct principal_container);
  71         if (!mem_ctx) {
  72                 (*error_string) = error_message(ENOMEM);
  73                 return ENOMEM;
  74         }
  75
  76         /* This song-and-dance effectivly puts the principal
  77          * into talloc, so we can't loose it. */
  78         mem_ctx->smb_krb5_context = talloc_reference(mem_ctx, smb_krb5_context);
  79         mem_ctx->principal = *princ;
  80         talloc_set_destructor(mem_ctx, free_principal);
  81         return 0;
  82 }
  83
  84 static krb5_error_code principals_from_msg(TALLOC_CTX *parent_ctx,
  85                                            struct ldb_message *msg,
  86                                            struct smb_krb5_context *smb_krb5_context,
  87                                            struct principal_container ***principals_out,
  88                                            const char **error_string)
  89 {
  90         unsigned int i;
  91         krb5_error_code ret;
  92         char *upper_realm;
  93         const char *realm = ldb_msg_find_attr_as_string(msg, "realm", NULL);
  94         const char *samAccountName = ldb_msg_find_attr_as_string(msg, "samAccountName", NULL);
  95         struct ldb_message_element *spn_el = ldb_msg_find_element(msg, "servicePrincipalName");
  96         TALLOC_CTX *tmp_ctx;
  97         struct principal_container **principals;
  98         tmp_ctx = talloc_new(parent_ctx);
  99         if (!tmp_ctx) {
 100                 *error_string = "Cannot allocate tmp_ctx";
 101                 return ENOMEM;
 102         }
 103
 104         if (!realm) {
 105                 *error_string = "Cannot have a kerberos secret in secrets.ldb without a realm";
 106                 return EINVAL;
 107         }
 108
 109         upper_realm = strupper_talloc(tmp_ctx, realm);
 110         if (!upper_realm) {
 111                 talloc_free(tmp_ctx);
 112                 *error_string = "Cannot allocate full upper case realm";
 113                 return ENOMEM;
 114         }
 115
 116         principals = talloc_array(tmp_ctx, struct principal_container *, spn_el ? (spn_el->num_values + 2) : 2);
 117
 118         spn_el = ldb_msg_find_element(msg, "servicePrincipalName");
 119         for (i=0; spn_el && i < spn_el->num_values; i++) {
 120                 principals[i] = talloc(principals, struct principal_container);
 121                 if (!principals[i]) {
 122                         talloc_free(tmp_ctx);
 123                         *error_string = "Cannot allocate mem_ctx";
 124                         return ENOMEM;
 125                 }
 126
 127                 principals[i]->smb_krb5_context = talloc_reference(principals[i], smb_krb5_context);
 128                 principals[i]->string_form = talloc_asprintf(principals[i], "%*.*s@%s",
 129                                                              (int)spn_el->values[i].length,
 130                                                              (int)spn_el->values[i].length,
 131                                                              (const char *)spn_el->values[i].data, upper_realm);
 132                 if (!principals[i]->string_form) {
 133                         talloc_free(tmp_ctx);
 134                         *error_string = "Cannot allocate full samAccountName";
 135                         return ENOMEM;
 136                 }
 137
 138                 ret = krb5_parse_name(smb_krb5_context->krb5_context,
 139                                       principals[i]->string_form, &principals[i]->principal);
 140
 141                 if (ret) {
 142                         talloc_free(tmp_ctx);
 143                         (*error_string) = smb_get_krb5_error_message(smb_krb5_context->krb5_context, ret, parent_ctx);
 144                         return ret;
 145                 }
 146
 147                 /* This song-and-dance effectivly puts the principal
 148                  * into talloc, so we can't loose it. */
 149                 talloc_set_destructor(principals[i], free_principal);
 150         }
 151
 152         if (samAccountName) {
 153                 principals[i] = talloc(principals, struct principal_container);
 154                 if (!principals[i]) {
 155                         talloc_free(tmp_ctx);
 156                         *error_string = "Cannot allocate mem_ctx";
 157                         return ENOMEM;
 158                 }
 159
 160                 principals[i]->smb_krb5_context = talloc_reference(principals[i], smb_krb5_context);
 161                 principals[i]->string_form = talloc_asprintf(parent_ctx, "%s@%s", samAccountName, upper_realm);
 162                 if (!principals[i]->string_form) {
 163                         talloc_free(tmp_ctx);
 164                         *error_string = "Cannot allocate full samAccountName";
 165                         return ENOMEM;
 166                 }
 167
 168                 ret = krb5_make_principal(smb_krb5_context->krb5_context, &principals[i]->principal, upper_realm, samAccountName,
 169                                           NULL);
 170                 if (ret) {
 171                         talloc_free(tmp_ctx);
 172                         (*error_string) = smb_get_krb5_error_message(smb_krb5_context->krb5_context, ret, parent_ctx);
 173                         return ret;
 174                 }
 175
 176                 /* This song-and-dance effectivly puts the principal
 177                  * into talloc, so we can't loose it. */
 178                 talloc_set_destructor(principals[i], free_principal);
 179                 i++;
 180         }
 181
 182         principals[i] = NULL;
 183         *principals_out = talloc_steal(parent_ctx, principals);
 184
 185         talloc_free(tmp_ctx);
 186         return ret;
 187 }
 188
 189 static krb5_error_code salt_principal_from_msg(TALLOC_CTX *parent_ctx,
 190                                                struct ldb_message *msg,
 191                                                struct smb_krb5_context *smb_krb5_context,
 192                                                krb5_principal *salt_princ,
 193                                                const char **error_string)
 194 {
 195         const char *salt_principal = ldb_msg_find_attr_as_string(msg, "saltPrincipal", NULL);
 196         const char *samAccountName = ldb_msg_find_attr_as_string(msg, "samAccountName", NULL);
 197         const char *realm = ldb_msg_find_attr_as_string(msg, "realm", NULL);
 198         if (salt_principal) {
 199                 return parse_principal(parent_ctx, salt_principal, smb_krb5_context, salt_princ, error_string);
 200         } else if (samAccountName) {
 201                 krb5_error_code ret;
 202                 char *machine_username;
 203                 char *salt_body;
 204                 char *lower_realm;
 205                 char *upper_realm;
 206
 207                 TALLOC_CTX *tmp_ctx;
 208                 struct principal_container *mem_ctx = talloc(parent_ctx, struct principal_container);
 209                 if (!mem_ctx) {
 210                         *error_string = "Cannot allocate mem_ctx";
 211                         return ENOMEM;
 212                 }
 213
 214                 tmp_ctx = talloc_new(mem_ctx);
 215                 if (!tmp_ctx) {
 216                         talloc_free(mem_ctx);
 217                         *error_string = "Cannot allocate tmp_ctx";
 218                         return ENOMEM;
 219                 }
 220
 221                 if (!realm) {
 222                         *error_string = "Cannot have a kerberos secret in secrets.ldb without a realm";
 223                         return EINVAL;
 224                 }
 225
 226                 machine_username = talloc_strdup(tmp_ctx, samAccountName);
 227                 if (!machine_username) {
 228                         talloc_free(mem_ctx);
 229                         *error_string = "Cannot duplicate samAccountName";
 230                         return ENOMEM;
 231                 }
 232
 233                 if (machine_username[strlen(machine_username)-1] == '$') {
 234                         machine_username[strlen(machine_username)-1] = '\0';
 235                 }
 236
 237                 lower_realm = strlower_talloc(tmp_ctx, realm);
 238                 if (!lower_realm) {
 239                         talloc_free(mem_ctx);
 240                         *error_string = "Cannot allocate to lower case realm";
 241                         return ENOMEM;
 242                 }
 243
 244                 upper_realm = strupper_talloc(tmp_ctx, realm);
 245                 if (!upper_realm) {
 246                         talloc_free(mem_ctx);
 247                         *error_string = "Cannot allocate to upper case realm";
 248                         return ENOMEM;
 249                 }
 250
 251                 salt_body = talloc_asprintf(tmp_ctx, "%s.%s", machine_username,
 252                                             lower_realm);
 253                 talloc_free(lower_realm);
 254                 talloc_free(machine_username);
 255                 if (!salt_body) {
 256                         talloc_free(mem_ctx);
 257                         *error_string = "Cannot form salt principal body";
 258                         return ENOMEM;
 259                 }
 260
 261                 ret = krb5_make_principal(smb_krb5_context->krb5_context, salt_princ,
 262                                           upper_realm,
 263                                           "host", salt_body, NULL);
 264                 if (ret == 0) {
 265                         /* This song-and-dance effectivly puts the principal
 266                          * into talloc, so we can't loose it. */
 267                         mem_ctx->smb_krb5_context = talloc_reference(mem_ctx, smb_krb5_context);
 268                         mem_ctx->principal = *salt_princ;
 269                         talloc_set_destructor(mem_ctx, free_principal);
 270                 } else {
 271                         (*error_string) = smb_get_krb5_error_message(smb_krb5_context->krb5_context, ret, parent_ctx);
 272                 }
 273                 talloc_free(tmp_ctx);
 274                 return ret;
 275         } else {
 276                 (*error_string) = "Cannot determine salt principal, no saltPrincipal or samAccountName specified";
 277                 return EINVAL;
 278         }
 279 }
 280
 281 /* Obtain the principal set on this context.  Requires a
 282  * smb_krb5_context because we are doing krb5 principal parsing with
 283  * the library routines.  The returned princ is placed in the talloc
 284  * system by means of a destructor (do *not* free). */
 285
 286 krb5_error_code principal_from_credentials(TALLOC_CTX *parent_ctx,
 287                                             struct cli_credentials *credentials,
 288                                             struct smb_krb5_context *smb_krb5_context,
 289                                             krb5_principal *princ,
 290                                             enum credentials_obtained *obtained,
 291                                             const char **error_string)
 292 {
 293         krb5_error_code ret;
 294         const char *princ_string;
 295         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 296         if (!mem_ctx) {
 297                 (*error_string) = error_message(ENOMEM);
 298                 return ENOMEM;
 299         }
 300         princ_string = cli_credentials_get_principal_and_obtained(credentials, mem_ctx, obtained);
 301         if (!princ_string) {
 302                 (*error_string) = error_message(ENOMEM);
 303                 return ENOMEM;
 304         }
 305
 306         ret = parse_principal(parent_ctx, princ_string,
 307                               smb_krb5_context, princ, error_string);
 308         talloc_free(mem_ctx);
 309         return ret;
 310 }
 311
 312 /* Obtain the principal set on this context.  Requires a
 313  * smb_krb5_context because we are doing krb5 principal parsing with
 314  * the library routines.  The returned princ is placed in the talloc
 315  * system by means of a destructor (do *not* free). */
 316
 317  krb5_error_code impersonate_principal_from_credentials(TALLOC_CTX *parent_ctx,
 318                                                         struct cli_credentials *credentials,
 319                                                         struct smb_krb5_context *smb_krb5_context,
 320                                                         krb5_principal *princ,
 321                                                         const char **error_string)
 322 {
 323         return parse_principal(parent_ctx, cli_credentials_get_impersonate_principal(credentials),
 324                                smb_krb5_context, princ, error_string);
 325 }
 326
 327 /**
 328  * Return a freshly allocated ccache (destroyed by destructor on child
 329  * of parent_ctx), for a given set of client credentials
 330  */
 331
 332  krb5_error_code kinit_to_ccache(TALLOC_CTX *parent_ctx,
 333                                  struct cli_credentials *credentials,
 334                                  struct smb_krb5_context *smb_krb5_context,
 335                                  krb5_ccache ccache,
 336                                  enum credentials_obtained *obtained,
 337                                  const char **error_string)
 338 {
 339         krb5_error_code ret;
 340         const char *password, *target_service;
 341         time_t kdc_time = 0;
 342         krb5_principal princ;
 343         krb5_principal impersonate_principal;
 344         int tries;
 345         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 346         krb5_get_init_creds_opt *krb_options;
 347
 348         if (!mem_ctx) {
 349                 (*error_string) = strerror(ENOMEM);
 350                 return ENOMEM;
 351         }
 352
 353         ret = principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &princ, obtained, error_string);
 354         if (ret) {
 355                 talloc_free(mem_ctx);
 356                 return ret;
 357         }
 358
 359         ret = impersonate_principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &impersonate_principal, error_string);
 360         if (ret) {
 361                 talloc_free(mem_ctx);
 362                 return ret;
 363         }
 364
 365         target_service = cli_credentials_get_target_service(credentials);
 366
 367         password = cli_credentials_get_password(credentials);
 368
 369         /* setup the krb5 options we want */
 370         if ((ret = krb5_get_init_creds_opt_alloc(smb_krb5_context->krb5_context, &krb_options))) {
 371                 (*error_string) = talloc_asprintf(credentials, "krb5_get_init_creds_opt_alloc failed (%s)\n",
 372                                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 373                                                                              ret, mem_ctx));
 374                 talloc_free(mem_ctx);
 375                 return ret;
 376         }
 377
 378         /* get the defaults */
 379         krb5_get_init_creds_opt_set_default_flags(smb_krb5_context->krb5_context, NULL, NULL, krb_options);
 380
 381         /* set if we want a forwardable ticket */
 382         switch (cli_credentials_get_krb_forwardable(credentials)) {
 383         case CRED_AUTO_KRB_FORWARDABLE:
 384                 break;
 385         case CRED_NO_KRB_FORWARDABLE:
 386                 krb5_get_init_creds_opt_set_forwardable(krb_options, FALSE);
 387                 break;
 388         case CRED_FORCE_KRB_FORWARDABLE:
 389                 krb5_get_init_creds_opt_set_forwardable(krb_options, TRUE);
 390                 break;
 391         }
 392
 393         tries = 2;
 394         while (tries--) {
 395                 if (password) {
 396                         ret = kerberos_kinit_password_cc(smb_krb5_context->krb5_context, ccache,
 397                                                          princ, password,
 398                                                          impersonate_principal, target_service,
 399                                                          krb_options,
 400                                                          NULL, &kdc_time);
 401                 } else if (impersonate_principal) {
 402                         (*error_string) = "INTERNAL error: Cannot impersonate principal with just a keyblock.  A password must be specified in the credentials";
 403                         return EINVAL;
 404                 } else {
 405                         /* No password available, try to use a keyblock instead */
 406
 407                         krb5_keyblock keyblock;
 408                         const struct samr_Password *mach_pwd;
 409                         mach_pwd = cli_credentials_get_nt_hash(credentials, mem_ctx);
 410                         if (!mach_pwd) {
 411                                 talloc_free(mem_ctx);
 412                                 (*error_string) = "kinit_to_ccache: No password available for kinit\n";
 413                                 krb5_get_init_creds_opt_free(smb_krb5_context->krb5_context, krb_options);
 414                                 return EINVAL;
 415                         }
 416                         ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
 417                                                  ENCTYPE_ARCFOUR_HMAC,
 418                                                  mach_pwd->hash, sizeof(mach_pwd->hash),
 419                                                  &keyblock);
 420
 421                         if (ret == 0) {
 422                                 ret = kerberos_kinit_keyblock_cc(smb_krb5_context->krb5_context, ccache,
 423                                                                  princ, &keyblock,
 424                                                                  target_service, krb_options,
 425                                                                  NULL, &kdc_time);
 426                                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &keyblock);
 427                         }
 428                 }
 429
 430                 if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
 431                         /* Perhaps we have been given an invalid skew, so try again without it */
 432                         time_t t = time(NULL);
 433                         krb5_set_real_time(smb_krb5_context->krb5_context, t, 0);
 434                 } else {
 435                         /* not a skew problem */
 436                         break;
 437                 }
 438         }
 439
 440         krb5_get_init_creds_opt_free(smb_krb5_context->krb5_context, krb_options);
 441
 442         if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
 443                 (*error_string) = talloc_asprintf(credentials, "kinit for %s failed (%s)\n",
 444                                                   cli_credentials_get_principal(credentials, mem_ctx),
 445                                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 446                                                                              ret, mem_ctx));
 447                 talloc_free(mem_ctx);
 448                 return ret;
 449         }
 450
 451         /* cope with ticket being in the future due to clock skew */
 452         if ((unsigned)kdc_time > time(NULL)) {
 453                 time_t t = time(NULL);
 454                 int time_offset =(unsigned)kdc_time-t;
 455                 DEBUG(4,("Advancing clock by %d seconds to cope with clock skew\n", time_offset));
 456                 krb5_set_real_time(smb_krb5_context->krb5_context, t + time_offset + 1, 0);
 457         }
 458
 459         if (ret == KRB5KDC_ERR_PREAUTH_FAILED && cli_credentials_wrong_password(credentials)) {
 460                 ret = kinit_to_ccache(parent_ctx,
 461                                       credentials,
 462                                       smb_krb5_context,
 463                                       ccache, obtained,
 464                                       error_string);
 465         }
 466
 467         if (ret) {
 468                 (*error_string) = talloc_asprintf(credentials, "kinit for %s failed (%s)\n",
 469                                                   cli_credentials_get_principal(credentials, mem_ctx),
 470                                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 471                                                                              ret, mem_ctx));
 472                 talloc_free(mem_ctx);
 473                 return ret;
 474         }
 475         talloc_free(mem_ctx);
 476         return 0;
 477 }
 478
 479 static krb5_error_code free_keytab(struct keytab_container *ktc)
 480 {
 481         return krb5_kt_close(ktc->smb_krb5_context->krb5_context, ktc->keytab);
 482 }
 483
 484 krb5_error_code smb_krb5_open_keytab(TALLOC_CTX *mem_ctx,
 485                          struct smb_krb5_context *smb_krb5_context,
 486                          const char *keytab_name, struct keytab_container **ktc)
 487 {
 488         krb5_keytab keytab;
 489         krb5_error_code ret;
 490         ret = krb5_kt_resolve(smb_krb5_context->krb5_context, keytab_name, &keytab);
 491         if (ret) {
 492                 DEBUG(1,("failed to open krb5 keytab: %s\n",
 493                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 494                                                     ret, mem_ctx)));
 495                 return ret;
 496         }
 497
 498         *ktc = talloc(mem_ctx, struct keytab_container);
 499         if (!*ktc) {
 500                 return ENOMEM;
 501         }
 502
 503         (*ktc)->smb_krb5_context = talloc_reference(*ktc, smb_krb5_context);
 504         (*ktc)->keytab = keytab;
 505         talloc_set_destructor(*ktc, free_keytab);
 506
 507         return 0;
 508 }
 509
 510 static krb5_error_code keytab_add_keys(TALLOC_CTX *parent_ctx,
 511                                        struct principal_container **principals,
 512                                        krb5_principal salt_princ,
 513                                        int kvno,
 514                                        const char *password_s,
 515                                        struct smb_krb5_context *smb_krb5_context,
 516                                        krb5_enctype *enctypes,
 517                                        krb5_keytab keytab,
 518                                        const char **error_string)
 519 {
 520         unsigned int i, p;
 521         krb5_error_code ret;
 522         krb5_data password;
 523
 524         password.data = discard_const_p(char *, password_s);
 525         password.length = strlen(password_s);
 526
 527         for (i=0; enctypes[i]; i++) {
 528                 krb5_keytab_entry entry;
 529
 530                 ZERO_STRUCT(entry);
 531
 532                 ret = create_kerberos_key_from_string(smb_krb5_context->krb5_context,
 533                                                       salt_princ, &password, &entry.keyblock, enctypes[i]);
 534                 if (ret != 0) {
 535                         return ret;
 536                 }
 537
 538                 entry.vno = kvno;
 539
 540                 for (p=0; principals[p]; p++) {
 541                         entry.principal = principals[p]->principal;
 542                         ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
 543                         if (ret != 0) {
 544                                 char *k5_error_string = smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 545                                                                                    ret, NULL);
 546                                 *error_string = talloc_asprintf(parent_ctx, "Failed to add enctype %d entry for %s(kvno %d) to keytab: %s\n",
 547                                                                 (int)enctypes[i],
 548                                                                 principals[p]->string_form,
 549                                                                 kvno,
 550                                                                 k5_error_string);
 551                                 talloc_free(k5_error_string);
 552                                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 553                                 return ret;
 554                         }
 555
 556                         DEBUG(5, ("Added %s(kvno %d) to keytab (enctype %d)\n",
 557                                   principals[p]->string_form, kvno,
 558                                   (int)enctypes[i]));
 559                 }
 560                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 561         }
 562         return 0;
 563 }
 564
 565 static krb5_error_code create_keytab(TALLOC_CTX *parent_ctx,
 566                                      struct ldb_message *msg,
 567                                      struct principal_container **principals,
 568                                      struct smb_krb5_context *smb_krb5_context,
 569                                      krb5_keytab keytab,
 570                                      bool add_old,
 571                                      const char **error_string)
 572 {
 573         krb5_error_code ret;
 574         const char *password_s;
 575         const char *old_secret;
 576         int kvno;
 577         uint32_t enctype_bitmap;
 578         krb5_principal salt_princ;
 579         krb5_enctype *enctypes;
 580         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 581         if (!mem_ctx) {
 582                 *error_string = "unable to allocate tmp_ctx for create_keytab";
 583                 return ENOMEM;
 584         }
 585
 586         /* The salt used to generate these entries may be different however, fetch that */
 587         ret = salt_principal_from_msg(mem_ctx, msg,
 588                                       smb_krb5_context,
 589                                       &salt_princ, error_string);
 590         if (ret) {
 591                 talloc_free(mem_ctx);
 592                 return ret;
 593         }
 594
 595         kvno = ldb_msg_find_attr_as_int(msg, "msDS-KeyVersionNumber", 0);
 596
 597         /* Finally, do the dance to get the password to put in the entry */
 598         password_s =  ldb_msg_find_attr_as_string(msg, "secret", NULL);
 599
 600         if (!password_s) {
 601                 /* There is no password here, so nothing to do */
 602                 talloc_free(mem_ctx);
 603                 return 0;
 604         }
 605
 606         if (add_old && kvno != 0) {
 607                 old_secret = ldb_msg_find_attr_as_string(msg, "priorSecret", NULL);
 608         } else {
 609                 old_secret = NULL;
 610         }
 611
 612         enctype_bitmap = (uint32_t)ldb_msg_find_attr_as_int(msg, "msDS-SupportedEncryptionTypes", ENC_ALL_TYPES);
 613
 614         ret = kerberos_enctype_bitmap_to_enctypes(mem_ctx, enctype_bitmap, &enctypes);
 615         if (ret) {
 616                 *error_string = talloc_asprintf(parent_ctx, "create_keytab: generating list of encryption types failed (%s)\n",
 617                                                 smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 618                                                                            ret, mem_ctx));
 619                 talloc_free(mem_ctx);
 620                 return ret;
 621         }
 622
 623         ret = keytab_add_keys(mem_ctx, principals,
 624                               salt_princ,
 625                               kvno, password_s, smb_krb5_context,
 626                               enctypes, keytab, error_string);
 627         if (ret) {
 628                 talloc_free(mem_ctx);
 629                 return ret;
 630         }
 631
 632         if (old_secret) {
 633                 ret = keytab_add_keys(mem_ctx, principals,
 634                                       salt_princ,
 635                                       kvno - 1, old_secret, smb_krb5_context,
 636                                       enctypes, keytab, error_string);
 637                 if (ret) {
 638                         talloc_free(mem_ctx);
 639                         return ret;
 640                 }
 641         }
 642
 643         talloc_free(mem_ctx);
 644         return ret;
 645 }
 646
 647 /*
 648  * Walk the keytab, looking for entries of this principal name, with KVNO other than current kvno -1.
 649  *
 650  * These entries are now stale, we only keep the current, and previous entries around.
 651  *
 652  * Inspired by the code in Samba3 for 'use kerberos keytab'.
 653  *
 654  */
 655
 656 static krb5_error_code remove_old_entries(TALLOC_CTX *parent_ctx,
 657                                           struct ldb_message *msg,
 658                                           struct principal_container **principals,
 659                                           bool delete_all_kvno,
 660                                           struct smb_krb5_context *smb_krb5_context,
 661                                           krb5_keytab keytab, bool *found_previous,
 662                                           const char **error_string)
 663 {
 664         krb5_error_code ret, ret2;
 665         krb5_kt_cursor cursor;
 666         int kvno;
 667         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 668
 669         if (!mem_ctx) {
 670                 return ENOMEM;
 671         }
 672
 673         *found_previous = false;
 674
 675         kvno = ldb_msg_find_attr_as_int(msg, "msDS-KeyVersionNumber", 0);
 676
 677         /* for each entry in the keytab */
 678         ret = krb5_kt_start_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 679         switch (ret) {
 680         case 0:
 681                 break;
 682         case HEIM_ERR_OPNOTSUPP:
 683         case ENOENT:
 684         case KRB5_KT_END:
 685                 /* no point enumerating if there isn't anything here */
 686                 talloc_free(mem_ctx);
 687                 return 0;
 688         default:
 689                 *error_string = talloc_asprintf(parent_ctx, "failed to open keytab for read of old entries: %s\n",
 690                                                 smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 691                                                                            ret, mem_ctx));
 692                 talloc_free(mem_ctx);
 693                 return ret;
 694         }
 695
 696         while (!ret) {
 697                 unsigned int i;
 698                 bool matched = false;
 699                 krb5_keytab_entry entry;
 700                 ret = krb5_kt_next_entry(smb_krb5_context->krb5_context, keytab, &entry, &cursor);
 701                 if (ret) {
 702                         break;
 703                 }
 704                 for (i = 0; principals[i]; i++) {
 705                         /* if it matches our principal */
 706                         if (krb5_kt_compare(smb_krb5_context->krb5_context, &entry, principals[i]->principal, 0, 0)) {
 707                                 matched = true;
 708                                 break;
 709                         }
 710                 }
 711
 712                 if (!matched) {
 713                         /* Free the entry, it wasn't the one we were looking for anyway */
 714                         krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 715                         continue;
 716                 }
 717
 718                 /* delete it, if it is not kvno -1 */
 719                 if (entry.vno != (kvno - 1 )) {
 720                         /* Release the enumeration.  We are going to
 721                          * have to start this from the top again,
 722                          * because deletes during enumeration may not
 723                          * always be consistant.
 724                          *
 725                          * Also, the enumeration locks a FILE: keytab
 726                          */
 727
 728                         krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 729
 730                         ret = krb5_kt_remove_entry(smb_krb5_context->krb5_context, keytab, &entry);
 731                         krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 732
 733                         /* Deleted: Restart from the top */
 734                         ret2 = krb5_kt_start_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 735                         if (ret2) {
 736                                 krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 737                                 DEBUG(1,("failed to restart enumeration of keytab: %s\n",
 738                                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 739                                                                     ret, mem_ctx)));
 740
 741                                 talloc_free(mem_ctx);
 742                                 return ret2;
 743                         }
 744
 745                         if (ret) {
 746                                 break;
 747                         }
 748
 749                 } else {
 750                         *found_previous = true;
 751                 }
 752
 753                 /* Free the entry, we don't need it any more */
 754                 krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 755
 756
 757         }
 758         krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 759
 760         switch (ret) {
 761         case 0:
 762                 break;
 763         case ENOENT:
 764         case KRB5_KT_END:
 765                 ret = 0;
 766                 break;
 767         default:
 768                 *error_string = talloc_asprintf(parent_ctx, "failed in deleting old entries for principal: %s\n",
 769                                                 smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 770                                                                            ret, mem_ctx));
 771         }
 772         talloc_free(mem_ctx);
 773         return ret;
 774 }
 775
 776 krb5_error_code smb_krb5_update_keytab(TALLOC_CTX *parent_ctx,
 777                                        struct smb_krb5_context *smb_krb5_context,
 778                                        struct ldb_context *ldb,
 779                                        struct ldb_message *msg,
 780                                        bool delete_all_kvno,
 781                                        const char **error_string)
 782 {
 783         krb5_error_code ret;
 784         bool found_previous;
 785         TALLOC_CTX *mem_ctx = talloc_new(NULL);
 786         struct keytab_container *keytab_container;
 787         struct principal_container **principals;
 788         const char *keytab_name;
 789
 790         if (!mem_ctx) {
 791                 return ENOMEM;
 792         }
 793
 794         keytab_name = keytab_name_from_msg(mem_ctx, ldb, msg);
 795         if (!keytab_name) {
 796                 return ENOENT;
 797         }
 798
 799         ret = smb_krb5_open_keytab(mem_ctx, smb_krb5_context, keytab_name, &keytab_container);
 800
 801         if (ret != 0) {
 802                 talloc_free(mem_ctx);
 803                 return ret;
 804         }
 805
 806         DEBUG(5, ("Opened keytab %s\n", keytab_name));
 807
 808         /* Get the principal we will store the new keytab entries under */
 809         ret = principals_from_msg(mem_ctx, msg, smb_krb5_context, &principals, error_string);
 810
 811         if (ret != 0) {
 812                 *error_string = talloc_asprintf(parent_ctx, "Failed to load principals from ldb message: %s\n", *error_string);
 813                 talloc_free(mem_ctx);
 814                 return ret;
 815         }
 816
 817         ret = remove_old_entries(mem_ctx, msg, principals, delete_all_kvno,
 818                                  smb_krb5_context, keytab_container->keytab, &found_previous, error_string);
 819         if (ret != 0) {
 820                 *error_string = talloc_asprintf(parent_ctx, "Failed to remove old principals from keytab: %s\n", *error_string);
 821                 talloc_free(mem_ctx);
 822                 return ret;
 823         }
 824
 825         if (!delete_all_kvno) {
 826                 /* Create a new keytab.  If during the cleanout we found
 827                  * entires for kvno -1, then don't try and duplicate them.
 828                  * Otherwise, add kvno, and kvno -1 */
 829
 830                 ret = create_keytab(mem_ctx, msg, principals,
 831                                     smb_krb5_context,
 832                                     keytab_container->keytab,
 833                                     found_previous ? false : true, error_string);
 834         }
 835         talloc_free(mem_ctx);
 836         return ret;
 837 }
 838
 839 krb5_error_code smb_krb5_create_memory_keytab(TALLOC_CTX *parent_ctx,
 840                                            struct cli_credentials *machine_account,
 841                                            struct smb_krb5_context *smb_krb5_context,
 842                                            struct keytab_container **keytab_container)
 843 {
 844         krb5_error_code ret;
 845         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 846         const char *rand_string;
 847         const char *keytab_name;
 848         struct ldb_message *msg;
 849         const char *error_string;
 850         if (!mem_ctx) {
 851                 return ENOMEM;
 852         }
 853
 854         *keytab_container = talloc(mem_ctx, struct keytab_container);
 855
 856         rand_string = generate_random_str(mem_ctx, 16);
 857         if (!rand_string) {
 858                 talloc_free(mem_ctx);
 859                 return ENOMEM;
 860         }
 861
 862         keytab_name = talloc_asprintf(mem_ctx, "MEMORY:%s",
 863                                       rand_string);
 864         if (!keytab_name) {
 865                 talloc_free(mem_ctx);
 866                 return ENOMEM;
 867         }
 868
 869         ret = smb_krb5_open_keytab(mem_ctx, smb_krb5_context, keytab_name, keytab_container);
 870         if (ret) {
 871                 return ret;
 872         }
 873
 874         msg = ldb_msg_new(mem_ctx);
 875         if (!msg) {
 876                 talloc_free(mem_ctx);
 877                 return ENOMEM;
 878         }
 879         ldb_msg_add_string(msg, "krb5Keytab", keytab_name);
 880         ldb_msg_add_string(msg, "secret", cli_credentials_get_password(machine_account));
 881         ldb_msg_add_string(msg, "samAccountName", cli_credentials_get_username(machine_account));
 882         ldb_msg_add_string(msg, "realm", cli_credentials_get_realm(machine_account));
 883         ldb_msg_add_fmt(msg, "msDS-KeyVersionNumber", "%d", (int)cli_credentials_get_kvno(machine_account));
 884
 885         ret = smb_krb5_update_keytab(mem_ctx, smb_krb5_context, NULL, msg, false, &error_string);
 886         if (ret == 0) {
 887                 talloc_steal(parent_ctx, *keytab_container);
 888         } else {
 889                 DEBUG(0, ("Failed to create in-memory keytab: %s\n", error_string));
 890                 *keytab_container = NULL;
 891         }
 892         talloc_free(mem_ctx);
 893         return ret;
 894 }
 895 /* Translate between the IETF encryption type values and the Microsoft msDS-SupportedEncryptionTypes values */
 896 uint32_t kerberos_enctype_to_bitmap(krb5_enctype enc_type_enum)
 897 {
 898         switch (enc_type_enum) {
 899         case ENCTYPE_DES_CBC_CRC:
 900                 return ENC_CRC32;
 901         case ENCTYPE_DES_CBC_MD5:
 902                 return ENC_RSA_MD5;
 903         case ENCTYPE_ARCFOUR_HMAC_MD5:
 904                 return ENC_RC4_HMAC_MD5;
 905         case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
 906                 return ENC_HMAC_SHA1_96_AES128;
 907         case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
 908                 return ENC_HMAC_SHA1_96_AES256;
 909         default:
 910                 return 0;
 911         }
 912 }
 913
 914 /* Translate between the Microsoft msDS-SupportedEncryptionTypes values and the IETF encryption type values */
 915 krb5_enctype kerberos_enctype_bitmap_to_enctype(uint32_t enctype_bitmap)
 916 {
 917         switch (enctype_bitmap) {
 918         case ENC_CRC32:
 919                 return ENCTYPE_DES_CBC_CRC;
 920         case ENC_RSA_MD5:
 921                 return ENCTYPE_DES_CBC_MD5;
 922         case ENC_RC4_HMAC_MD5:
 923                 return ENCTYPE_ARCFOUR_HMAC_MD5;
 924         case ENC_HMAC_SHA1_96_AES128:
 925                 return ENCTYPE_AES128_CTS_HMAC_SHA1_96;
 926         case ENC_HMAC_SHA1_96_AES256:
 927                 return ENCTYPE_AES256_CTS_HMAC_SHA1_96;
 928         default:
 929                 return 0;
 930         }
 931 }
 932
 933 /* Return an array of krb5_enctype values */
 934 krb5_error_code kerberos_enctype_bitmap_to_enctypes(TALLOC_CTX *mem_ctx, uint32_t enctype_bitmap, krb5_enctype **enctypes)
 935 {
 936         unsigned int i, j = 0;
 937         *enctypes = talloc_zero_array(mem_ctx, krb5_enctype, (8*sizeof(enctype_bitmap))+1);
 938         if (!*enctypes) {
 939                 return ENOMEM;
 940         }
 941         for (i=0; i<(8*sizeof(enctype_bitmap)); i++) {
 942                 uint32_t bit_value = (1 << i) & enctype_bitmap;
 943                 if (bit_value & enctype_bitmap) {
 944                         (*enctypes)[j] = kerberos_enctype_bitmap_to_enctype(bit_value);
 945                         if (!(*enctypes)[j]) {
 946                                 continue;
 947                         }
 948                         j++;
 949                 }
 950         }
 951         (*enctypes)[j] = 0;
 952         return 0;
 953 }