source4/kdc/kpasswdd.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    kpasswd Server implementation
   5
   6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2005
   7    Copyright (C) Andrew Tridgell        2005
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  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 "smbd/service_task.h"
  25 #include "auth/gensec/gensec.h"
  26 #include "auth/credentials/credentials.h"
  27 #include "auth/auth.h"
  28 #include "dsdb/samdb/samdb.h"
  29 #include "../lib/util/util_ldb.h"
  30 #include "libcli/security/security.h"
  31 #include "param/param.h"
  32 #include "kdc/kdc-glue.h"
  33 #include "dsdb/common/util.h"
  34
  35 /* Return true if there is a valid error packet formed in the error_blob */
  36 static bool kpasswdd_make_error_reply(struct kdc_server *kdc,
  37                                      TALLOC_CTX *mem_ctx,
  38                                      uint16_t result_code,
  39                                      const char *error_string,
  40                                      DATA_BLOB *error_blob)
  41 {
  42         char *error_string_utf8;
  43         size_t len;
  44
  45         DEBUG(result_code ? 3 : 10, ("kpasswdd: %s\n", error_string));
  46
  47         if (!push_utf8_talloc(mem_ctx, &error_string_utf8, error_string, &len)) {
  48                 return false;
  49         }
  50
  51         *error_blob = data_blob_talloc(mem_ctx, NULL, 2 + len + 1);
  52         if (!error_blob->data) {
  53                 return false;
  54         }
  55         RSSVAL(error_blob->data, 0, result_code);
  56         memcpy(error_blob->data + 2, error_string_utf8, len + 1);
  57         return true;
  58 }
  59
  60 /* Return true if there is a valid error packet formed in the error_blob */
  61 static bool kpasswdd_make_unauth_error_reply(struct kdc_server *kdc,
  62                                             TALLOC_CTX *mem_ctx,
  63                                             uint16_t result_code,
  64                                             const char *error_string,
  65                                             DATA_BLOB *error_blob)
  66 {
  67         bool ret;
  68         int kret;
  69         DATA_BLOB error_bytes;
  70         krb5_data k5_error_bytes, k5_error_blob;
  71         ret = kpasswdd_make_error_reply(kdc, mem_ctx, result_code, error_string,
  72                                        &error_bytes);
  73         if (!ret) {
  74                 return false;
  75         }
  76         k5_error_bytes.data = error_bytes.data;
  77         k5_error_bytes.length = error_bytes.length;
  78         kret = krb5_mk_error(kdc->smb_krb5_context->krb5_context,
  79                              result_code, NULL, &k5_error_bytes,
  80                              NULL, NULL, NULL, NULL, &k5_error_blob);
  81         if (kret) {
  82                 return false;
  83         }
  84         *error_blob = data_blob_talloc(mem_ctx, k5_error_blob.data, k5_error_blob.length);
  85         krb5_data_free(&k5_error_blob);
  86         if (!error_blob->data) {
  87                 return false;
  88         }
  89         return true;
  90 }
  91
  92 static bool kpasswd_make_pwchange_reply(struct kdc_server *kdc,
  93                                         TALLOC_CTX *mem_ctx,
  94                                         NTSTATUS status,
  95                                         enum samPwdChangeReason reject_reason,
  96                                         struct samr_DomInfo1 *dominfo,
  97                                         DATA_BLOB *error_blob)
  98 {
  99         if (NT_STATUS_EQUAL(status, NT_STATUS_NO_SUCH_USER)) {
 100                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 101                                                 KRB5_KPASSWD_ACCESSDENIED,
 102                                                 "No such user when changing password",
 103                                                 error_blob);
 104         }
 105         if (NT_STATUS_EQUAL(status, NT_STATUS_ACCESS_DENIED)) {
 106                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 107                                                 KRB5_KPASSWD_ACCESSDENIED,
 108                                                 "Not permitted to change password",
 109                                                 error_blob);
 110         }
 111         if (dominfo && NT_STATUS_EQUAL(status, NT_STATUS_PASSWORD_RESTRICTION)) {
 112                 const char *reject_string;
 113                 switch (reject_reason) {
 114                 case SAM_PWD_CHANGE_PASSWORD_TOO_SHORT:
 115                         reject_string = talloc_asprintf(mem_ctx, "Password too short, password must be at least %d characters long.",
 116                                                         dominfo->min_password_length);
 117                         break;
 118                 case SAM_PWD_CHANGE_NOT_COMPLEX:
 119                         reject_string = "Password does not meet complexity requirements";
 120                         break;
 121                 case SAM_PWD_CHANGE_PWD_IN_HISTORY:
 122                         reject_string = talloc_asprintf(mem_ctx, "Password is already in password history.  New password must not match any of your %d previous passwords.",
 123                                                         dominfo->password_history_length);
 124                         break;
 125                 default:
 126                         reject_string = "Password change rejected, password changes may not be permitted on this account, or the minimum password age may not have elapsed.";
 127                         break;
 128                 }
 129                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 130                                                 KRB5_KPASSWD_SOFTERROR,
 131                                                 reject_string,
 132                                                 error_blob);
 133         }
 134         if (!NT_STATUS_IS_OK(status)) {
 135                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 136                                                  KRB5_KPASSWD_HARDERROR,
 137                                                  talloc_asprintf(mem_ctx, "failed to set password: %s", nt_errstr(status)),
 138                                                  error_blob);
 139
 140         }
 141         return kpasswdd_make_error_reply(kdc, mem_ctx, KRB5_KPASSWD_SUCCESS,
 142                                         "Password changed",
 143                                         error_blob);
 144 }
 145
 146 /*
 147    A user password change
 148
 149    Return true if there is a valid error packet (or success) formed in
 150    the error_blob
 151 */
 152 static bool kpasswdd_change_password(struct kdc_server *kdc,
 153                                      TALLOC_CTX *mem_ctx,
 154                                      struct auth_session_info *session_info,
 155                                      const DATA_BLOB *password,
 156                                      DATA_BLOB *reply)
 157 {
 158         NTSTATUS status;
 159         enum samPwdChangeReason reject_reason;
 160         struct samr_DomInfo1 *dominfo;
 161         struct samr_Password *oldLmHash, *oldNtHash;
 162         struct ldb_context *samdb;
 163         const char * const attrs[] = { "dBCSPwd", "unicodePwd", NULL };
 164         struct ldb_message *msg;
 165         int ret;
 166
 167         /* Fetch the old hashes to get the old password in order to perform
 168          * the password change operation. Naturally it would be much better to
 169          * have a password hash from an authentication around but this doesn't
 170          * seem to be the case here. */
 171         ret = dsdb_search_one(kdc->samdb, mem_ctx, &msg, ldb_get_default_basedn(kdc->samdb),
 172                               LDB_SCOPE_SUBTREE,
 173                               attrs,
 174                               DSDB_SEARCH_NO_GLOBAL_CATALOG,
 175                               "(&(objectClass=user)(sAMAccountName=%s))",
 176                               session_info->info->account_name);
 177         if (ret != LDB_SUCCESS) {
 178                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 179                                                 KRB5_KPASSWD_ACCESSDENIED,
 180                                                 "No such user when changing password",
 181                                                 reply);
 182         }
 183
 184         /*
 185          * No need to check for password lockout here, the KDC will
 186          * have done that when issuing the ticket, which is not based
 187          * on the user's password
 188          */
 189         status = samdb_result_passwords_no_lockout(mem_ctx, kdc->task->lp_ctx, msg,
 190                                                    &oldLmHash, &oldNtHash);
 191         if (!NT_STATUS_IS_OK(status)) {
 192                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 193                                                 KRB5_KPASSWD_ACCESSDENIED,
 194                                                 "Not permitted to change password",
 195                                                 reply);
 196         }
 197
 198         /* Start a SAM with user privileges for the password change */
 199         samdb = samdb_connect(mem_ctx, kdc->task->event_ctx, kdc->task->lp_ctx,
 200                               session_info, 0);
 201         if (!samdb) {
 202                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 203                                                 KRB5_KPASSWD_HARDERROR,
 204                                                 "Failed to open samdb",
 205                                                 reply);
 206         }
 207
 208         DEBUG(3, ("Changing password of %s\\%s (%s)\n",
 209                   session_info->info->domain_name,
 210                   session_info->info->account_name,
 211                   dom_sid_string(mem_ctx, &session_info->security_token->sids[PRIMARY_USER_SID_INDEX])));
 212
 213         /* Performs the password change */
 214         status = samdb_set_password_sid(samdb, mem_ctx,
 215                                         &session_info->security_token->sids[PRIMARY_USER_SID_INDEX],
 216                                         password, NULL, NULL,
 217                                         oldLmHash, oldNtHash, /* this is a user password change */
 218                                         &reject_reason,
 219                                         &dominfo);
 220         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 221                                            status,
 222                                            reject_reason,
 223                                            dominfo,
 224                                            reply);
 225
 226 }
 227
 228 static bool kpasswd_process_request(struct kdc_server *kdc,
 229                                     TALLOC_CTX *mem_ctx,
 230                                     struct gensec_security *gensec_security,
 231                                     uint16_t version,
 232                                     DATA_BLOB *input,
 233                                     DATA_BLOB *reply)
 234 {
 235         struct auth_session_info *session_info;
 236         size_t pw_len;
 237
 238         if (!NT_STATUS_IS_OK(gensec_session_info(gensec_security,
 239                                                  mem_ctx,
 240                                                  &session_info))) {
 241                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 242                                                 KRB5_KPASSWD_HARDERROR,
 243                                                 "gensec_session_info failed!",
 244                                                 reply);
 245         }
 246
 247         switch (version) {
 248         case KRB5_KPASSWD_VERS_CHANGEPW:
 249         {
 250                 DATA_BLOB password;
 251                 if (!convert_string_talloc_handle(mem_ctx, lpcfg_iconv_handle(kdc->task->lp_ctx),
 252                                                CH_UTF8, CH_UTF16,
 253                                                (const char *)input->data,
 254                                                input->length,
 255                                                (void **)&password.data, &pw_len)) {
 256                         return false;
 257                 }
 258                 password.length = pw_len;
 259
 260                 return kpasswdd_change_password(kdc, mem_ctx, session_info,
 261                                                 &password, reply);
 262         }
 263         case KRB5_KPASSWD_VERS_SETPW:
 264         {
 265                 NTSTATUS status;
 266                 enum samPwdChangeReason reject_reason = SAM_PWD_CHANGE_NO_ERROR;
 267                 struct samr_DomInfo1 *dominfo = NULL;
 268                 struct ldb_context *samdb;
 269                 krb5_context context = kdc->smb_krb5_context->krb5_context;
 270
 271                 ChangePasswdDataMS chpw;
 272                 DATA_BLOB password;
 273
 274                 krb5_principal principal;
 275                 char *set_password_on_princ;
 276                 struct ldb_dn *set_password_on_dn;
 277                 bool service_principal_name = false;
 278
 279                 size_t len;
 280                 int ret;
 281
 282                 ret = decode_ChangePasswdDataMS(input->data, input->length,
 283                                                 &chpw, &len);
 284                 if (ret) {
 285                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 286                                                         KRB5_KPASSWD_MALFORMED,
 287                                                         "failed to decode password change structure",
 288                                                         reply);
 289                 }
 290
 291                 if (!convert_string_talloc_handle(mem_ctx, lpcfg_iconv_handle(kdc->task->lp_ctx),
 292                                                CH_UTF8, CH_UTF16,
 293                                                (const char *)chpw.newpasswd.data,
 294                                                chpw.newpasswd.length,
 295                                                (void **)&password.data, &pw_len)) {
 296                         free_ChangePasswdDataMS(&chpw);
 297                         return false;
 298                 }
 299
 300                 password.length = pw_len;
 301
 302                 if ((chpw.targname && !chpw.targrealm)
 303                     || (!chpw.targname && chpw.targrealm)) {
 304                         free_ChangePasswdDataMS(&chpw);
 305                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 306                                                         KRB5_KPASSWD_MALFORMED,
 307                                                         "Realm and principal must be both present, or neither present",
 308                                                         reply);
 309                 }
 310                 if (chpw.targname && chpw.targrealm) {
 311                         ret = krb5_build_principal_ext(kdc->smb_krb5_context->krb5_context,
 312                                                        &principal,
 313                                                        strlen(*chpw.targrealm),
 314                                                        *chpw.targrealm, 0);
 315                         if (ret) {
 316                                 free_ChangePasswdDataMS(&chpw);
 317                                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 318                                                                 KRB5_KPASSWD_MALFORMED,
 319                                                                 "failed to get principal",
 320                                                                 reply);
 321                         }
 322                         if (copy_PrincipalName(chpw.targname, &principal->name)) {
 323                                 free_ChangePasswdDataMS(&chpw);
 324                                 krb5_free_principal(context, principal);
 325                                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 326                                                                 KRB5_KPASSWD_MALFORMED,
 327                                                                 "failed to extract principal to set",
 328                                                                 reply);
 329                         }
 330                 } else {
 331                         free_ChangePasswdDataMS(&chpw);
 332                         return kpasswdd_change_password(kdc, mem_ctx, session_info,
 333                                                         &password, reply);
 334                 }
 335                 free_ChangePasswdDataMS(&chpw);
 336
 337                 if (principal->name.name_string.len >= 2) {
 338                         service_principal_name = true;
 339
 340                         /* We use this, rather than 'no realm' flag,
 341                          * as we don't want to accept a password
 342                          * change on a principal from another realm */
 343
 344                         if (krb5_unparse_name_short(context, principal, &set_password_on_princ) != 0) {
 345                                 krb5_free_principal(context, principal);
 346                                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 347                                                                  KRB5_KPASSWD_MALFORMED,
 348                                                                  "krb5_unparse_name failed!",
 349                                                                  reply);
 350                         }
 351                 } else {
 352                         if (krb5_unparse_name(context, principal, &set_password_on_princ) != 0) {
 353                                 krb5_free_principal(context, principal);
 354                                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 355                                                                  KRB5_KPASSWD_MALFORMED,
 356                                                                  "krb5_unparse_name failed!",
 357                                                                  reply);
 358                         }
 359                 }
 360                 krb5_free_principal(context, principal);
 361
 362                 samdb = samdb_connect(mem_ctx, kdc->task->event_ctx, kdc->task->lp_ctx, session_info, 0);
 363                 if (!samdb) {
 364                         free(set_password_on_princ);
 365                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 366                                                          KRB5_KPASSWD_HARDERROR,
 367                                                          "Unable to open database!",
 368                                                          reply);
 369                 }
 370
 371                 DEBUG(3, ("%s\\%s (%s) is changing password of %s\n",
 372                           session_info->info->domain_name,
 373                           session_info->info->account_name,
 374                           dom_sid_string(mem_ctx, &session_info->security_token->sids[PRIMARY_USER_SID_INDEX]),
 375                           set_password_on_princ));
 376                 ret = ldb_transaction_start(samdb);
 377                 if (ret != LDB_SUCCESS) {
 378                         free(set_password_on_princ);
 379                         status = NT_STATUS_TRANSACTION_ABORTED;
 380                         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 381                                                            status,
 382                                                            SAM_PWD_CHANGE_NO_ERROR,
 383                                                            NULL,
 384                                                            reply);
 385                 }
 386
 387                 if (service_principal_name) {
 388                         status = crack_service_principal_name(samdb, mem_ctx,
 389                                                               set_password_on_princ,
 390                                                               &set_password_on_dn, NULL);
 391                 } else {
 392                         status = crack_user_principal_name(samdb, mem_ctx,
 393                                                            set_password_on_princ,
 394                                                            &set_password_on_dn, NULL);
 395                 }
 396                 free(set_password_on_princ);
 397                 if (!NT_STATUS_IS_OK(status)) {
 398                         ldb_transaction_cancel(samdb);
 399                         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 400                                                            status,
 401                                                            SAM_PWD_CHANGE_NO_ERROR,
 402                                                            NULL,
 403                                                            reply);
 404                 }
 405
 406                 if (NT_STATUS_IS_OK(status)) {
 407                         /* Admin password set */
 408                         status = samdb_set_password(samdb, mem_ctx,
 409                                                     set_password_on_dn, NULL,
 410                                                     &password, NULL, NULL,
 411                                                     NULL, NULL, /* this is not a user password change */
 412                                                     &reject_reason, &dominfo);
 413                 }
 414
 415                 if (NT_STATUS_IS_OK(status)) {
 416                         ret = ldb_transaction_commit(samdb);
 417                         if (ret != LDB_SUCCESS) {
 418                                 DEBUG(1,("Failed to commit transaction to set password on %s: %s\n",
 419                                          ldb_dn_get_linearized(set_password_on_dn),
 420                                          ldb_errstring(samdb)));
 421                                 status = NT_STATUS_TRANSACTION_ABORTED;
 422                         }
 423                 } else {
 424                         ldb_transaction_cancel(samdb);
 425                 }
 426                 return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 427                                                    status,
 428                                                    reject_reason,
 429                                                    dominfo,
 430                                                    reply);
 431         }
 432         default:
 433                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 434                                                  KRB5_KPASSWD_BAD_VERSION,
 435                                                  talloc_asprintf(mem_ctx,
 436                                                                  "Protocol version %u not supported",
 437                                                                  version),
 438                                                  reply);
 439         }
 440 }
 441
 442 enum kdc_process_ret kpasswdd_process(struct kdc_server *kdc,
 443                                       TALLOC_CTX *mem_ctx,
 444                                       DATA_BLOB *input,
 445                                       DATA_BLOB *reply,
 446                                       struct tsocket_address *peer_addr,
 447                                       struct tsocket_address *my_addr,
 448                                       int datagram_reply)
 449 {
 450         bool ret;
 451         const uint16_t header_len = 6;
 452         uint16_t len;
 453         uint16_t ap_req_len;
 454         uint16_t krb_priv_len;
 455         uint16_t version;
 456         NTSTATUS nt_status;
 457         DATA_BLOB ap_req, krb_priv_req;
 458         DATA_BLOB krb_priv_rep = data_blob(NULL, 0);
 459         DATA_BLOB ap_rep = data_blob(NULL, 0);
 460         DATA_BLOB kpasswd_req, kpasswd_rep;
 461         struct cli_credentials *server_credentials;
 462         struct gensec_security *gensec_security;
 463         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 464
 465         char *keytab_name;
 466
 467         if (!tmp_ctx) {
 468                 return KDC_PROCESS_FAILED;
 469         }
 470
 471         if (kdc->am_rodc) {
 472                 talloc_free(tmp_ctx);
 473                 return KDC_PROCESS_PROXY;
 474         }
 475
 476         /* Be parinoid.  We need to ensure we don't just let the
 477          * caller lead us into a buffer overflow */
 478         if (input->length <= header_len) {
 479                 talloc_free(tmp_ctx);
 480                 return KDC_PROCESS_FAILED;
 481         }
 482
 483         len = RSVAL(input->data, 0);
 484         if (input->length != len) {
 485                 talloc_free(tmp_ctx);
 486                 return KDC_PROCESS_FAILED;
 487         }
 488
 489         /* There are two different versions of this protocol so far,
 490          * plus others in the standards pipe.  Fortunetly they all
 491          * take a very similar framing */
 492         version = RSVAL(input->data, 2);
 493         ap_req_len = RSVAL(input->data, 4);
 494         if ((ap_req_len >= len) || (ap_req_len + header_len) >= len) {
 495                 talloc_free(tmp_ctx);
 496                 return KDC_PROCESS_FAILED;
 497         }
 498
 499         krb_priv_len = len - ap_req_len;
 500         ap_req = data_blob_const(&input->data[header_len], ap_req_len);
 501         krb_priv_req = data_blob_const(&input->data[header_len + ap_req_len], krb_priv_len);
 502
 503         server_credentials = cli_credentials_init(tmp_ctx);
 504         if (!server_credentials) {
 505                 DEBUG(1, ("Failed to init server credentials\n"));
 506                 talloc_free(tmp_ctx);
 507                 return KDC_PROCESS_FAILED;
 508         }
 509
 510         /* We want the credentials subsystem to use the krb5 context
 511          * we already have, rather than a new context */
 512         cli_credentials_set_krb5_context(server_credentials, kdc->smb_krb5_context);
 513         cli_credentials_set_conf(server_credentials, kdc->task->lp_ctx);
 514
 515         keytab_name = talloc_asprintf(server_credentials, "HDB:samba4&%p", kdc->base_ctx);
 516
 517         cli_credentials_set_username(server_credentials, "kadmin/changepw", CRED_SPECIFIED);
 518         ret = cli_credentials_set_keytab_name(server_credentials, kdc->task->lp_ctx, keytab_name, CRED_SPECIFIED);
 519         if (ret != 0) {
 520                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 521                                                        KRB5_KPASSWD_HARDERROR,
 522                                                        talloc_asprintf(mem_ctx,
 523                                                                        "Failed to obtain server credentials for kadmin/changepw!"),
 524                                                        &krb_priv_rep);
 525                 ap_rep.length = 0;
 526                 if (ret) {
 527                         goto reply;
 528                 }
 529                 talloc_free(tmp_ctx);
 530                 return ret;
 531         }
 532
 533         /* We don't strictly need to call this wrapper, and could call
 534          * gensec_server_start directly, as we have no need for NTLM
 535          * and we have a PAC, but this ensures that the wrapper can be
 536          * safely extended for other helpful things in future */
 537         nt_status = samba_server_gensec_start(tmp_ctx, kdc->task->event_ctx,
 538                                               kdc->task->msg_ctx,
 539                                               kdc->task->lp_ctx,
 540                                               server_credentials,
 541                                               "kpasswd",
 542                                               &gensec_security);
 543         if (!NT_STATUS_IS_OK(nt_status)) {
 544                 talloc_free(tmp_ctx);
 545                 return KDC_PROCESS_FAILED;
 546         }
 547
 548         /* The kerberos PRIV packets include these addresses.  MIT
 549          * clients check that they are present */
 550 #if 0
 551         /* Skip this part for now, it breaks with a NetAPP filer and
 552          * in any case where the client address is behind NAT.  If
 553          * older MIT clients need this, we might have to insert more
 554          * complex code */
 555
 556         nt_status = gensec_set_remote_address(gensec_security, peer_addr);
 557         if (!NT_STATUS_IS_OK(nt_status)) {
 558                 talloc_free(tmp_ctx);
 559                 return KDC_PROCESS_FAILED;
 560         }
 561 #endif
 562
 563         nt_status = gensec_set_local_address(gensec_security, my_addr);
 564         if (!NT_STATUS_IS_OK(nt_status)) {
 565                 talloc_free(tmp_ctx);
 566                 return KDC_PROCESS_FAILED;
 567         }
 568
 569         /* We want the GENSEC wrap calls to generate PRIV tokens */
 570         gensec_want_feature(gensec_security, GENSEC_FEATURE_SEAL);
 571
 572         nt_status = gensec_start_mech_by_name(gensec_security, "krb5");
 573         if (!NT_STATUS_IS_OK(nt_status)) {
 574                 talloc_free(tmp_ctx);
 575                 return KDC_PROCESS_FAILED;
 576         }
 577
 578         /* Accept the AP-REQ and generate teh AP-REP we need for the reply */
 579         nt_status = gensec_update_ev(gensec_security, tmp_ctx, kdc->task->event_ctx, ap_req, &ap_rep);
 580         if (!NT_STATUS_IS_OK(nt_status) && !NT_STATUS_EQUAL(nt_status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
 581
 582                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 583                                                        KRB5_KPASSWD_HARDERROR,
 584                                                        talloc_asprintf(mem_ctx,
 585                                                                        "gensec_update failed: %s",
 586                                                                        nt_errstr(nt_status)),
 587                                                        &krb_priv_rep);
 588                 ap_rep.length = 0;
 589                 if (ret) {
 590                         goto reply;
 591                 }
 592                 talloc_free(tmp_ctx);
 593                 return KDC_PROCESS_FAILED;
 594         }
 595
 596         /* Extract the data from the KRB-PRIV half of the message */
 597         nt_status = gensec_unwrap(gensec_security, tmp_ctx, &krb_priv_req, &kpasswd_req);
 598         if (!NT_STATUS_IS_OK(nt_status)) {
 599                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 600                                                        KRB5_KPASSWD_HARDERROR,
 601                                                        talloc_asprintf(mem_ctx,
 602                                                                        "gensec_unwrap failed: %s",
 603                                                                        nt_errstr(nt_status)),
 604                                                        &krb_priv_rep);
 605                 ap_rep.length = 0;
 606                 if (ret) {
 607                         goto reply;
 608                 }
 609                 talloc_free(tmp_ctx);
 610                 return KDC_PROCESS_FAILED;
 611         }
 612
 613         /* Figure out something to do with it (probably changing a password...) */
 614         ret = kpasswd_process_request(kdc, tmp_ctx,
 615                                       gensec_security,
 616                                       version,
 617                                       &kpasswd_req, &kpasswd_rep);
 618         if (!ret) {
 619                 /* Argh! */
 620                 talloc_free(tmp_ctx);
 621                 return KDC_PROCESS_FAILED;
 622         }
 623
 624         /* And wrap up the reply: This ensures that the error message
 625          * or success can be verified by the client */
 626         nt_status = gensec_wrap(gensec_security, tmp_ctx,
 627                                 &kpasswd_rep, &krb_priv_rep);
 628         if (!NT_STATUS_IS_OK(nt_status)) {
 629                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 630                                                        KRB5_KPASSWD_HARDERROR,
 631                                                        talloc_asprintf(mem_ctx,
 632                                                                        "gensec_wrap failed: %s",
 633                                                                        nt_errstr(nt_status)),
 634                                                        &krb_priv_rep);
 635                 ap_rep.length = 0;
 636                 if (ret) {
 637                         goto reply;
 638                 }
 639                 talloc_free(tmp_ctx);
 640                 return KDC_PROCESS_FAILED;
 641         }
 642
 643 reply:
 644         *reply = data_blob_talloc(mem_ctx, NULL, krb_priv_rep.length + ap_rep.length + header_len);
 645         if (!reply->data) {
 646                 talloc_free(tmp_ctx);
 647                 return KDC_PROCESS_FAILED;
 648         }
 649
 650         RSSVAL(reply->data, 0, reply->length);
 651         RSSVAL(reply->data, 2, 1); /* This is a version 1 reply, MS change/set or otherwise */
 652         RSSVAL(reply->data, 4, ap_rep.length);
 653         memcpy(reply->data + header_len,
 654                ap_rep.data,
 655                ap_rep.length);
 656         memcpy(reply->data + header_len + ap_rep.length,
 657                krb_priv_rep.data,
 658                krb_priv_rep.length);
 659
 660         talloc_free(tmp_ctx);
 661         return KDC_PROCESS_OK;
 662 }
 663