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                                  struct tevent_context *event_ctx,
 336                                  krb5_ccache ccache,
 337                                  enum credentials_obtained *obtained,
 338                                  const char **error_string)
 339 {
 340         krb5_error_code ret;
 341         const char *password, *target_service;
 342         time_t kdc_time = 0;
 343         krb5_principal princ;
 344         krb5_principal impersonate_principal;
 345         int tries;
 346         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 347         krb5_get_init_creds_opt *krb_options;
 348
 349         if (!mem_ctx) {
 350                 (*error_string) = strerror(ENOMEM);
 351                 return ENOMEM;
 352         }
 353
 354         ret = principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &princ, obtained, error_string);
 355         if (ret) {
 356                 talloc_free(mem_ctx);
 357                 return ret;
 358         }
 359
 360         ret = impersonate_principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &impersonate_principal, error_string);
 361         if (ret) {
 362                 talloc_free(mem_ctx);
 363                 return ret;
 364         }
 365
 366         target_service = cli_credentials_get_target_service(credentials);
 367
 368         password = cli_credentials_get_password(credentials);
 369
 370         /* setup the krb5 options we want */
 371         if ((ret = krb5_get_init_creds_opt_alloc(smb_krb5_context->krb5_context, &krb_options))) {
 372                 (*error_string) = talloc_asprintf(credentials, "krb5_get_init_creds_opt_alloc failed (%s)\n",
 373                                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 374                                                                              ret, mem_ctx));
 375                 talloc_free(mem_ctx);
 376                 return ret;
 377         }
 378
 379         /* get the defaults */
 380         krb5_get_init_creds_opt_set_default_flags(smb_krb5_context->krb5_context, NULL, NULL, krb_options);
 381
 382         /* set if we want a forwardable ticket */
 383         switch (cli_credentials_get_krb_forwardable(credentials)) {
 384         case CRED_AUTO_KRB_FORWARDABLE:
 385                 break;
 386         case CRED_NO_KRB_FORWARDABLE:
 387                 krb5_get_init_creds_opt_set_forwardable(krb_options, FALSE);
 388                 break;
 389         case CRED_FORCE_KRB_FORWARDABLE:
 390                 krb5_get_init_creds_opt_set_forwardable(krb_options, TRUE);
 391                 break;
 392         }
 393
 394         tries = 2;
 395         while (tries--) {
 396                 struct tevent_context *previous_ev;
 397                 /* Do this every time, in case we have weird recursive issues here */
 398                 ret = smb_krb5_context_set_event_ctx(smb_krb5_context, event_ctx, &previous_ev);
 399                 if (ret) {
 400                         talloc_free(mem_ctx);
 401                         return ret;
 402                 }
 403                 if (password) {
 404                         ret = kerberos_kinit_password_cc(smb_krb5_context->krb5_context, ccache,
 405                                                          princ, password,
 406                                                          impersonate_principal, target_service,
 407                                                          krb_options,
 408                                                          NULL, &kdc_time);
 409                 } else if (impersonate_principal) {
 410                         talloc_free(mem_ctx);
 411                         (*error_string) = "INTERNAL error: Cannot impersonate principal with just a keyblock.  A password must be specified in the credentials";
 412                         return EINVAL;
 413                 } else {
 414                         /* No password available, try to use a keyblock instead */
 415
 416                         krb5_keyblock keyblock;
 417                         const struct samr_Password *mach_pwd;
 418                         mach_pwd = cli_credentials_get_nt_hash(credentials, mem_ctx);
 419                         if (!mach_pwd) {
 420                                 talloc_free(mem_ctx);
 421                                 (*error_string) = "kinit_to_ccache: No password available for kinit\n";
 422                                 krb5_get_init_creds_opt_free(smb_krb5_context->krb5_context, krb_options);
 423                                 smb_krb5_context_remove_event_ctx(smb_krb5_context, previous_ev, event_ctx);
 424                                 return EINVAL;
 425                         }
 426                         ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
 427                                                  ENCTYPE_ARCFOUR_HMAC,
 428                                                  mach_pwd->hash, sizeof(mach_pwd->hash),
 429                                                  &keyblock);
 430
 431                         if (ret == 0) {
 432                                 ret = kerberos_kinit_keyblock_cc(smb_krb5_context->krb5_context, ccache,
 433                                                                  princ, &keyblock,
 434                                                                  target_service, krb_options,
 435                                                                  NULL, &kdc_time);
 436                                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &keyblock);
 437                         }
 438                 }
 439
 440                 smb_krb5_context_remove_event_ctx(smb_krb5_context, previous_ev, event_ctx);
 441
 442                 if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
 443                         /* Perhaps we have been given an invalid skew, so try again without it */
 444                         time_t t = time(NULL);
 445                         krb5_set_real_time(smb_krb5_context->krb5_context, t, 0);
 446                 } else {
 447                         /* not a skew problem */
 448                         break;
 449                 }
 450         }
 451
 452         krb5_get_init_creds_opt_free(smb_krb5_context->krb5_context, krb_options);
 453
 454         if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
 455                 (*error_string) = talloc_asprintf(credentials, "kinit for %s failed (%s)\n",
 456                                                   cli_credentials_get_principal(credentials, mem_ctx),
 457                                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 458                                                                              ret, mem_ctx));
 459                 talloc_free(mem_ctx);
 460                 return ret;
 461         }
 462
 463         /* cope with ticket being in the future due to clock skew */
 464         if ((unsigned)kdc_time > time(NULL)) {
 465                 time_t t = time(NULL);
 466                 int time_offset =(unsigned)kdc_time-t;
 467                 DEBUG(4,("Advancing clock by %d seconds to cope with clock skew\n", time_offset));
 468                 krb5_set_real_time(smb_krb5_context->krb5_context, t + time_offset + 1, 0);
 469         }
 470
 471         if (ret == KRB5KDC_ERR_PREAUTH_FAILED && cli_credentials_wrong_password(credentials)) {
 472                 ret = kinit_to_ccache(parent_ctx,
 473                                       credentials,
 474                                       smb_krb5_context,
 475                                       event_ctx,
 476                                       ccache, obtained,
 477                                       error_string);
 478         }
 479
 480         if (ret) {
 481                 (*error_string) = talloc_asprintf(credentials, "kinit for %s failed (%s)\n",
 482                                                   cli_credentials_get_principal(credentials, mem_ctx),
 483                                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 484                                                                              ret, mem_ctx));
 485                 talloc_free(mem_ctx);
 486                 return ret;
 487         }
 488         talloc_free(mem_ctx);
 489         return 0;
 490 }
 491
 492 static krb5_error_code free_keytab_container(struct keytab_container *ktc)
 493 {
 494         return krb5_kt_close(ktc->smb_krb5_context->krb5_context, ktc->keytab);
 495 }
 496
 497 krb5_error_code smb_krb5_get_keytab_container(TALLOC_CTX *mem_ctx,
 498                                               struct smb_krb5_context *smb_krb5_context,
 499                                               const char *keytab_name, struct keytab_container **ktc)
 500 {
 501         krb5_keytab keytab;
 502         krb5_error_code ret;
 503         ret = krb5_kt_resolve(smb_krb5_context->krb5_context, keytab_name, &keytab);
 504         if (ret) {
 505                 DEBUG(1,("failed to open krb5 keytab: %s\n",
 506                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 507                                                     ret, mem_ctx)));
 508                 return ret;
 509         }
 510
 511         *ktc = talloc(mem_ctx, struct keytab_container);
 512         if (!*ktc) {
 513                 return ENOMEM;
 514         }
 515
 516         (*ktc)->smb_krb5_context = talloc_reference(*ktc, smb_krb5_context);
 517         (*ktc)->keytab = keytab;
 518         talloc_set_destructor(*ktc, free_keytab_container);
 519
 520         return 0;
 521 }
 522
 523 static krb5_error_code keytab_add_keys(TALLOC_CTX *parent_ctx,
 524                                        struct principal_container **principals,
 525                                        krb5_principal salt_princ,
 526                                        int kvno,
 527                                        const char *password_s,
 528                                        struct smb_krb5_context *smb_krb5_context,
 529                                        krb5_enctype *enctypes,
 530                                        krb5_keytab keytab,
 531                                        const char **error_string)
 532 {
 533         unsigned int i, p;
 534         krb5_error_code ret;
 535         krb5_data password;
 536
 537         password.data = discard_const_p(char *, password_s);
 538         password.length = strlen(password_s);
 539
 540         for (i=0; enctypes[i]; i++) {
 541                 krb5_keytab_entry entry;
 542
 543                 ZERO_STRUCT(entry);
 544
 545                 ret = create_kerberos_key_from_string_direct(smb_krb5_context->krb5_context,
 546                                                              salt_princ, &password, &entry.keyblock, enctypes[i]);
 547                 if (ret != 0) {
 548                         return ret;
 549                 }
 550
 551                 entry.vno = kvno;
 552
 553                 for (p=0; principals[p]; p++) {
 554                         entry.principal = principals[p]->principal;
 555                         ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
 556                         if (ret != 0) {
 557                                 char *k5_error_string = smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 558                                                                                    ret, NULL);
 559                                 *error_string = talloc_asprintf(parent_ctx, "Failed to add enctype %d entry for %s(kvno %d) to keytab: %s\n",
 560                                                                 (int)enctypes[i],
 561                                                                 principals[p]->string_form,
 562                                                                 kvno,
 563                                                                 k5_error_string);
 564                                 talloc_free(k5_error_string);
 565                                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 566                                 return ret;
 567                         }
 568
 569                         DEBUG(5, ("Added %s(kvno %d) to keytab (enctype %d)\n",
 570                                   principals[p]->string_form, kvno,
 571                                   (int)enctypes[i]));
 572                 }
 573                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 574         }
 575         return 0;
 576 }
 577
 578 static krb5_error_code create_keytab(TALLOC_CTX *parent_ctx,
 579                                      struct ldb_message *msg,
 580                                      struct principal_container **principals,
 581                                      struct smb_krb5_context *smb_krb5_context,
 582                                      krb5_keytab keytab,
 583                                      bool add_old,
 584                                      const char **error_string)
 585 {
 586         krb5_error_code ret;
 587         const char *password_s;
 588         const char *old_secret;
 589         int kvno;
 590         uint32_t enctype_bitmap;
 591         krb5_principal salt_princ;
 592         krb5_enctype *enctypes;
 593         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 594         if (!mem_ctx) {
 595                 *error_string = "unable to allocate tmp_ctx for create_keytab";
 596                 return ENOMEM;
 597         }
 598
 599         /* The salt used to generate these entries may be different however, fetch that */
 600         ret = salt_principal_from_msg(mem_ctx, msg,
 601                                       smb_krb5_context,
 602                                       &salt_princ, error_string);
 603         if (ret) {
 604                 talloc_free(mem_ctx);
 605                 return ret;
 606         }
 607
 608         kvno = ldb_msg_find_attr_as_int(msg, "msDS-KeyVersionNumber", 0);
 609
 610         /* Finally, do the dance to get the password to put in the entry */
 611         password_s =  ldb_msg_find_attr_as_string(msg, "secret", NULL);
 612
 613         if (!password_s) {
 614                 /* There is no password here, so nothing to do */
 615                 talloc_free(mem_ctx);
 616                 return 0;
 617         }
 618
 619         if (add_old && kvno != 0) {
 620                 old_secret = ldb_msg_find_attr_as_string(msg, "priorSecret", NULL);
 621         } else {
 622                 old_secret = NULL;
 623         }
 624
 625         enctype_bitmap = (uint32_t)ldb_msg_find_attr_as_int(msg, "msDS-SupportedEncryptionTypes", ENC_ALL_TYPES);
 626
 627         ret = kerberos_enctype_bitmap_to_enctypes(mem_ctx, enctype_bitmap, &enctypes);
 628         if (ret) {
 629                 *error_string = talloc_asprintf(parent_ctx, "create_keytab: generating list of encryption types failed (%s)\n",
 630                                                 smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 631                                                                            ret, mem_ctx));
 632                 talloc_free(mem_ctx);
 633                 return ret;
 634         }
 635
 636         ret = keytab_add_keys(mem_ctx, principals,
 637                               salt_princ,
 638                               kvno, password_s, smb_krb5_context,
 639                               enctypes, keytab, error_string);
 640         if (ret) {
 641                 talloc_free(mem_ctx);
 642                 return ret;
 643         }
 644
 645         if (old_secret) {
 646                 ret = keytab_add_keys(mem_ctx, principals,
 647                                       salt_princ,
 648                                       kvno - 1, old_secret, smb_krb5_context,
 649                                       enctypes, keytab, error_string);
 650                 if (ret) {
 651                         talloc_free(mem_ctx);
 652                         return ret;
 653                 }
 654         }
 655
 656         talloc_free(mem_ctx);
 657         return ret;
 658 }
 659
 660 /*
 661  * Walk the keytab, looking for entries of this principal name, with KVNO other than current kvno -1.
 662  *
 663  * These entries are now stale, we only keep the current, and previous entries around.
 664  *
 665  * Inspired by the code in Samba3 for 'use kerberos keytab'.
 666  *
 667  */
 668
 669 static krb5_error_code remove_old_entries(TALLOC_CTX *parent_ctx,
 670                                           struct ldb_message *msg,
 671                                           struct principal_container **principals,
 672                                           bool delete_all_kvno,
 673                                           struct smb_krb5_context *smb_krb5_context,
 674                                           krb5_keytab keytab, bool *found_previous,
 675                                           const char **error_string)
 676 {
 677         krb5_error_code ret, ret2;
 678         krb5_kt_cursor cursor;
 679         int kvno;
 680         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 681
 682         if (!mem_ctx) {
 683                 return ENOMEM;
 684         }
 685
 686         *found_previous = false;
 687
 688         kvno = ldb_msg_find_attr_as_int(msg, "msDS-KeyVersionNumber", 0);
 689
 690         /* for each entry in the keytab */
 691         ret = krb5_kt_start_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 692         switch (ret) {
 693         case 0:
 694                 break;
 695         case HEIM_ERR_OPNOTSUPP:
 696         case ENOENT:
 697         case KRB5_KT_END:
 698                 /* no point enumerating if there isn't anything here */
 699                 talloc_free(mem_ctx);
 700                 return 0;
 701         default:
 702                 *error_string = talloc_asprintf(parent_ctx, "failed to open keytab for read of old entries: %s\n",
 703                                                 smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 704                                                                            ret, mem_ctx));
 705                 talloc_free(mem_ctx);
 706                 return ret;
 707         }
 708
 709         while (!ret) {
 710                 unsigned int i;
 711                 bool matched = false;
 712                 krb5_keytab_entry entry;
 713                 ret = krb5_kt_next_entry(smb_krb5_context->krb5_context, keytab, &entry, &cursor);
 714                 if (ret) {
 715                         break;
 716                 }
 717                 for (i = 0; principals[i]; i++) {
 718                         /* if it matches our principal */
 719                         if (krb5_kt_compare(smb_krb5_context->krb5_context, &entry, principals[i]->principal, 0, 0)) {
 720                                 matched = true;
 721                                 break;
 722                         }
 723                 }
 724
 725                 if (!matched) {
 726                         /* Free the entry, it wasn't the one we were looking for anyway */
 727                         krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 728                         continue;
 729                 }
 730
 731                 /* delete it, if it is not kvno -1 */
 732                 if (entry.vno != (kvno - 1 )) {
 733                         /* Release the enumeration.  We are going to
 734                          * have to start this from the top again,
 735                          * because deletes during enumeration may not
 736                          * always be consistant.
 737                          *
 738                          * Also, the enumeration locks a FILE: keytab
 739                          */
 740
 741                         krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 742
 743                         ret = krb5_kt_remove_entry(smb_krb5_context->krb5_context, keytab, &entry);
 744                         krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 745
 746                         /* Deleted: Restart from the top */
 747                         ret2 = krb5_kt_start_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 748                         if (ret2) {
 749                                 krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 750                                 DEBUG(1,("failed to restart enumeration of keytab: %s\n",
 751                                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 752                                                                     ret, mem_ctx)));
 753
 754                                 talloc_free(mem_ctx);
 755                                 return ret2;
 756                         }
 757
 758                         if (ret) {
 759                                 break;
 760                         }
 761
 762                 } else {
 763                         *found_previous = true;
 764                 }
 765
 766                 /* Free the entry, we don't need it any more */
 767                 krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
 768
 769
 770         }
 771         krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
 772
 773         switch (ret) {
 774         case 0:
 775                 break;
 776         case ENOENT:
 777         case KRB5_KT_END:
 778                 ret = 0;
 779                 break;
 780         default:
 781                 *error_string = talloc_asprintf(parent_ctx, "failed in deleting old entries for principal: %s\n",
 782                                                 smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 783                                                                            ret, mem_ctx));
 784         }
 785         talloc_free(mem_ctx);
 786         return ret;
 787 }
 788
 789 krb5_error_code smb_krb5_update_keytab(TALLOC_CTX *parent_ctx,
 790                                        struct smb_krb5_context *smb_krb5_context,
 791                                        struct ldb_context *ldb,
 792                                        struct ldb_message *msg,
 793                                        bool delete_all_kvno,
 794                                        const char **error_string)
 795 {
 796         krb5_error_code ret;
 797         bool found_previous;
 798         TALLOC_CTX *mem_ctx = talloc_new(NULL);
 799         struct keytab_container *keytab_container;
 800         struct principal_container **principals;
 801         const char *keytab_name;
 802
 803         if (!mem_ctx) {
 804                 return ENOMEM;
 805         }
 806
 807         keytab_name = keytab_name_from_msg(mem_ctx, ldb, msg);
 808         if (!keytab_name) {
 809                 return ENOENT;
 810         }
 811
 812         ret = smb_krb5_get_keytab_container(mem_ctx, smb_krb5_context, keytab_name, &keytab_container);
 813
 814         if (ret != 0) {
 815                 talloc_free(mem_ctx);
 816                 return ret;
 817         }
 818
 819         DEBUG(5, ("Opened keytab %s\n", keytab_name));
 820
 821         /* Get the principal we will store the new keytab entries under */
 822         ret = principals_from_msg(mem_ctx, msg, smb_krb5_context, &principals, error_string);
 823
 824         if (ret != 0) {
 825                 *error_string = talloc_asprintf(parent_ctx, "Failed to load principals from ldb message: %s\n", *error_string);
 826                 talloc_free(mem_ctx);
 827                 return ret;
 828         }
 829
 830         ret = remove_old_entries(mem_ctx, msg, principals, delete_all_kvno,
 831                                  smb_krb5_context, keytab_container->keytab, &found_previous, error_string);
 832         if (ret != 0) {
 833                 *error_string = talloc_asprintf(parent_ctx, "Failed to remove old principals from keytab: %s\n", *error_string);
 834                 talloc_free(mem_ctx);
 835                 return ret;
 836         }
 837
 838         if (!delete_all_kvno) {
 839                 /* Create a new keytab.  If during the cleanout we found
 840                  * entires for kvno -1, then don't try and duplicate them.
 841                  * Otherwise, add kvno, and kvno -1 */
 842
 843                 ret = create_keytab(mem_ctx, msg, principals,
 844                                     smb_krb5_context,
 845                                     keytab_container->keytab,
 846                                     found_previous ? false : true, error_string);
 847         }
 848         talloc_free(mem_ctx);
 849         return ret;
 850 }
 851
 852 krb5_error_code smb_krb5_create_memory_keytab(TALLOC_CTX *parent_ctx,
 853                                            struct cli_credentials *machine_account,
 854                                            struct smb_krb5_context *smb_krb5_context,
 855                                            struct keytab_container **keytab_container)
 856 {
 857         krb5_error_code ret;
 858         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 859         const char *rand_string;
 860         const char *keytab_name;
 861         struct ldb_message *msg;
 862         const char *error_string;
 863         if (!mem_ctx) {
 864                 return ENOMEM;
 865         }
 866
 867         *keytab_container = talloc(mem_ctx, struct keytab_container);
 868
 869         rand_string = generate_random_str(mem_ctx, 16);
 870         if (!rand_string) {
 871                 talloc_free(mem_ctx);
 872                 return ENOMEM;
 873         }
 874
 875         keytab_name = talloc_asprintf(mem_ctx, "MEMORY:%s",
 876                                       rand_string);
 877         if (!keytab_name) {
 878                 talloc_free(mem_ctx);
 879                 return ENOMEM;
 880         }
 881
 882         ret = smb_krb5_get_keytab_container(mem_ctx, smb_krb5_context, keytab_name, keytab_container);
 883         if (ret) {
 884                 return ret;
 885         }
 886
 887         msg = ldb_msg_new(mem_ctx);
 888         if (!msg) {
 889                 talloc_free(mem_ctx);
 890                 return ENOMEM;
 891         }
 892         ldb_msg_add_string(msg, "krb5Keytab", keytab_name);
 893         ldb_msg_add_string(msg, "secret", cli_credentials_get_password(machine_account));
 894         ldb_msg_add_string(msg, "samAccountName", cli_credentials_get_username(machine_account));
 895         ldb_msg_add_string(msg, "realm", cli_credentials_get_realm(machine_account));
 896         ldb_msg_add_fmt(msg, "msDS-KeyVersionNumber", "%d", (int)cli_credentials_get_kvno(machine_account));
 897
 898         ret = smb_krb5_update_keytab(mem_ctx, smb_krb5_context, NULL, msg, false, &error_string);
 899         if (ret == 0) {
 900                 talloc_steal(parent_ctx, *keytab_container);
 901         } else {
 902                 DEBUG(0, ("Failed to create in-memory keytab: %s\n", error_string));
 903                 *keytab_container = NULL;
 904         }
 905         talloc_free(mem_ctx);
 906         return ret;
 907 }
 908 /* Translate between the IETF encryption type values and the Microsoft msDS-SupportedEncryptionTypes values */
 909 uint32_t kerberos_enctype_to_bitmap(krb5_enctype enc_type_enum)
 910 {
 911         switch (enc_type_enum) {
 912         case ENCTYPE_DES_CBC_CRC:
 913                 return ENC_CRC32;
 914         case ENCTYPE_DES_CBC_MD5:
 915                 return ENC_RSA_MD5;
 916         case ENCTYPE_ARCFOUR_HMAC_MD5:
 917                 return ENC_RC4_HMAC_MD5;
 918         case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
 919                 return ENC_HMAC_SHA1_96_AES128;
 920         case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
 921                 return ENC_HMAC_SHA1_96_AES256;
 922         default:
 923                 return 0;
 924         }
 925 }
 926
 927 /* Translate between the Microsoft msDS-SupportedEncryptionTypes values and the IETF encryption type values */
 928 krb5_enctype kerberos_enctype_bitmap_to_enctype(uint32_t enctype_bitmap)
 929 {
 930         switch (enctype_bitmap) {
 931         case ENC_CRC32:
 932                 return ENCTYPE_DES_CBC_CRC;
 933         case ENC_RSA_MD5:
 934                 return ENCTYPE_DES_CBC_MD5;
 935         case ENC_RC4_HMAC_MD5:
 936                 return ENCTYPE_ARCFOUR_HMAC_MD5;
 937         case ENC_HMAC_SHA1_96_AES128:
 938                 return ENCTYPE_AES128_CTS_HMAC_SHA1_96;
 939         case ENC_HMAC_SHA1_96_AES256:
 940                 return ENCTYPE_AES256_CTS_HMAC_SHA1_96;
 941         default:
 942                 return 0;
 943         }
 944 }
 945
 946 /* Return an array of krb5_enctype values */
 947 krb5_error_code kerberos_enctype_bitmap_to_enctypes(TALLOC_CTX *mem_ctx, uint32_t enctype_bitmap, krb5_enctype **enctypes)
 948 {
 949         unsigned int i, j = 0;
 950         *enctypes = talloc_zero_array(mem_ctx, krb5_enctype, (8*sizeof(enctype_bitmap))+1);
 951         if (!*enctypes) {
 952                 return ENOMEM;
 953         }
 954         for (i=0; i<(8*sizeof(enctype_bitmap)); i++) {
 955                 uint32_t bit_value = (1 << i) & enctype_bitmap;
 956                 if (bit_value & enctype_bitmap) {
 957                         (*enctypes)[j] = kerberos_enctype_bitmap_to_enctype(bit_value);
 958                         if (!(*enctypes)[j]) {
 959                                 continue;
 960                         }
 961                         j++;
 962                 }
 963         }
 964         (*enctypes)[j] = 0;
 965         return 0;
 966 }