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 "lib/events/events.h"
  26 #include "lib/socket/socket.h"
  27 #include "lib/tsocket/tsocket.h"
  28 #include "system/network.h"
  29 #include "../lib/util/dlinklist.h"
  30 #include "lib/ldb/include/ldb.h"
  31 #include "auth/gensec/gensec.h"
  32 #include "auth/credentials/credentials.h"
  33 #include "auth/credentials/credentials_krb5.h"
  34 #include "auth/auth.h"
  35 #include "dsdb/samdb/samdb.h"
  36 #include "../lib/util/util_ldb.h"
  37 #include "rpc_server/dcerpc_server.h"
  38 #include "rpc_server/samr/proto.h"
  39 #include "libcli/security/security.h"
  40 #include "param/param.h"
  41 #include "kdc/kdc.h"
  42
  43 /* TODO: remove all SAMBA4_INTERNAL_HEIMDAL stuff from this file */
  44 #ifdef SAMBA4_INTERNAL_HEIMDAL
  45 #include "heimdal_build/kpasswdd-glue.h"
  46 #endif
  47
  48 /* Return true if there is a valid error packet formed in the error_blob */
  49 static bool kpasswdd_make_error_reply(struct kdc_server *kdc,
  50                                      TALLOC_CTX *mem_ctx,
  51                                      uint16_t result_code,
  52                                      const char *error_string,
  53                                      DATA_BLOB *error_blob)
  54 {
  55         char *error_string_utf8;
  56         size_t len;
  57
  58         DEBUG(result_code ? 3 : 10, ("kpasswdd: %s\n", error_string));
  59
  60         if (!push_utf8_talloc(mem_ctx, &error_string_utf8, error_string, &len)) {
  61                 return false;
  62         }
  63
  64         *error_blob = data_blob_talloc(mem_ctx, NULL, 2 + len + 1);
  65         if (!error_blob->data) {
  66                 return false;
  67         }
  68         RSSVAL(error_blob->data, 0, result_code);
  69         memcpy(error_blob->data + 2, error_string_utf8, len + 1);
  70         return true;
  71 }
  72
  73 /* Return true if there is a valid error packet formed in the error_blob */
  74 static bool kpasswdd_make_unauth_error_reply(struct kdc_server *kdc,
  75                                             TALLOC_CTX *mem_ctx,
  76                                             uint16_t result_code,
  77                                             const char *error_string,
  78                                             DATA_BLOB *error_blob)
  79 {
  80         bool ret;
  81         int kret;
  82         DATA_BLOB error_bytes;
  83         krb5_data k5_error_bytes, k5_error_blob;
  84         ret = kpasswdd_make_error_reply(kdc, mem_ctx, result_code, error_string,
  85                                        &error_bytes);
  86         if (!ret) {
  87                 return false;
  88         }
  89         k5_error_bytes.data = error_bytes.data;
  90         k5_error_bytes.length = error_bytes.length;
  91         kret = krb5_mk_error(kdc->smb_krb5_context->krb5_context,
  92                              result_code, NULL, &k5_error_bytes,
  93                              NULL, NULL, NULL, NULL, &k5_error_blob);
  94         if (kret) {
  95                 return false;
  96         }
  97         *error_blob = data_blob_talloc(mem_ctx, k5_error_blob.data, k5_error_blob.length);
  98         krb5_data_free(&k5_error_blob);
  99         if (!error_blob->data) {
 100                 return false;
 101         }
 102         return true;
 103 }
 104
 105 static bool kpasswd_make_pwchange_reply(struct kdc_server *kdc,
 106                                         TALLOC_CTX *mem_ctx,
 107                                         NTSTATUS status,
 108                                         enum samPwdChangeReason reject_reason,
 109                                         struct samr_DomInfo1 *dominfo,
 110                                         DATA_BLOB *error_blob)
 111 {
 112         if (NT_STATUS_EQUAL(status, NT_STATUS_NO_SUCH_USER)) {
 113                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 114                                                 KRB5_KPASSWD_ACCESSDENIED,
 115                                                 "No such user when changing password",
 116                                                 error_blob);
 117         }
 118         if (NT_STATUS_EQUAL(status, NT_STATUS_ACCESS_DENIED)) {
 119                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 120                                                 KRB5_KPASSWD_ACCESSDENIED,
 121                                                 "Not permitted to change password",
 122                                                 error_blob);
 123         }
 124         if (dominfo && NT_STATUS_EQUAL(status, NT_STATUS_PASSWORD_RESTRICTION)) {
 125                 const char *reject_string;
 126                 switch (reject_reason) {
 127                 case SAM_PWD_CHANGE_PASSWORD_TOO_SHORT:
 128                         reject_string = talloc_asprintf(mem_ctx, "Password too short, password must be at least %d characters long",
 129                                                         dominfo->min_password_length);
 130                         break;
 131                 case SAM_PWD_CHANGE_NOT_COMPLEX:
 132                         reject_string = "Password does not meet complexity requirements";
 133                         break;
 134                 case SAM_PWD_CHANGE_PWD_IN_HISTORY:
 135                         reject_string = "Password is already in password history";
 136                         break;
 137                 default:
 138                         reject_string = talloc_asprintf(mem_ctx, "Password must be at least %d characters long, and cannot match any of your %d previous passwords",
 139                                                         dominfo->min_password_length, dominfo->password_history_length);
 140                         break;
 141                 }
 142                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 143                                                 KRB5_KPASSWD_SOFTERROR,
 144                                                 reject_string,
 145                                                 error_blob);
 146         }
 147         if (!NT_STATUS_IS_OK(status)) {
 148                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 149                                                  KRB5_KPASSWD_HARDERROR,
 150                                                  talloc_asprintf(mem_ctx, "failed to set password: %s", nt_errstr(status)),
 151                                                  error_blob);
 152
 153         }
 154         return kpasswdd_make_error_reply(kdc, mem_ctx, KRB5_KPASSWD_SUCCESS,
 155                                         "Password changed",
 156                                         error_blob);
 157 }
 158
 159 /*
 160    A user password change
 161
 162    Return true if there is a valid error packet (or success) formed in
 163    the error_blob
 164 */
 165 static bool kpasswdd_change_password(struct kdc_server *kdc,
 166                                      TALLOC_CTX *mem_ctx,
 167                                      struct auth_session_info *session_info,
 168                                      const DATA_BLOB *password,
 169                                      DATA_BLOB *reply)
 170 {
 171         NTSTATUS status;
 172         enum samPwdChangeReason reject_reason;
 173         struct samr_DomInfo1 *dominfo;
 174         struct samr_Password *oldLmHash, *oldNtHash;
 175         struct ldb_context *samdb;
 176         const char * const attrs[] = { "dBCSPwd", "unicodePwd", NULL };
 177         struct ldb_message **res;
 178         int ret;
 179
 180         /* Connect to a SAMDB with system privileges for fetching the old pw
 181          * hashes. */
 182         samdb = samdb_connect(mem_ctx, kdc->task->event_ctx, kdc->task->lp_ctx,
 183                               system_session(kdc->task->lp_ctx), 0);
 184         if (!samdb) {
 185                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 186                                                 KRB5_KPASSWD_HARDERROR,
 187                                                 "Failed to open samdb",
 188                                                 reply);
 189         }
 190
 191         /* Fetch the old hashes to get the old password in order to perform
 192          * the password change operation. Naturally it would be much better to
 193          * have a password hash from an authentication around but this doesn't
 194          * seem to be the case here. */
 195         ret = gendb_search(samdb, mem_ctx, NULL, &res, attrs,
 196                            "(&(objectClass=user)(sAMAccountName=%s))",
 197                            session_info->server_info->account_name);
 198         if (ret != 1) {
 199                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 200                                                 KRB5_KPASSWD_ACCESSDENIED,
 201                                                 "No such user when changing password",
 202                                                 reply);
 203         }
 204
 205         status = samdb_result_passwords(mem_ctx, kdc->task->lp_ctx, res[0],
 206                                         &oldLmHash, &oldNtHash);
 207         if (!NT_STATUS_IS_OK(status)) {
 208                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 209                                                 KRB5_KPASSWD_ACCESSDENIED,
 210                                                 "Not permitted to change password",
 211                                                 reply);
 212         }
 213
 214         /* Start a SAM with user privileges for the password change */
 215         samdb = samdb_connect(mem_ctx, kdc->task->event_ctx, kdc->task->lp_ctx,
 216                               session_info, 0);
 217         if (!samdb) {
 218                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 219                                                 KRB5_KPASSWD_HARDERROR,
 220                                                 "Failed to open samdb",
 221                                                 reply);
 222         }
 223
 224         DEBUG(3, ("Changing password of %s\\%s (%s)\n",
 225                   session_info->server_info->domain_name,
 226                   session_info->server_info->account_name,
 227                   dom_sid_string(mem_ctx, &session_info->security_token->sids[PRIMARY_USER_SID_INDEX])));
 228
 229         /* Performs the password change */
 230         status = samdb_set_password_sid(samdb, mem_ctx,
 231                                         &session_info->security_token->sids[PRIMARY_USER_SID_INDEX],
 232                                         password, NULL, NULL,
 233                                         oldLmHash, oldNtHash, /* this is a user password change */
 234                                         &reject_reason,
 235                                         &dominfo);
 236         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 237                                            status,
 238                                            reject_reason,
 239                                            dominfo,
 240                                            reply);
 241
 242 }
 243
 244 static bool kpasswd_process_request(struct kdc_server *kdc,
 245                                     TALLOC_CTX *mem_ctx,
 246                                     struct gensec_security *gensec_security,
 247                                     uint16_t version,
 248                                     DATA_BLOB *input,
 249                                     DATA_BLOB *reply)
 250 {
 251         struct auth_session_info *session_info;
 252         size_t pw_len;
 253
 254         if (!NT_STATUS_IS_OK(gensec_session_info(gensec_security,
 255                                                  &session_info))) {
 256                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 257                                                 KRB5_KPASSWD_HARDERROR,
 258                                                 "gensec_session_info failed!",
 259                                                 reply);
 260         }
 261
 262         switch (version) {
 263         case KRB5_KPASSWD_VERS_CHANGEPW:
 264         {
 265                 DATA_BLOB password;
 266                 if (!convert_string_talloc_convenience(mem_ctx, lpcfg_iconv_convenience(kdc->task->lp_ctx),
 267                                                CH_UTF8, CH_UTF16,
 268                                                (const char *)input->data,
 269                                                input->length,
 270                                                (void **)&password.data, &pw_len, false)) {
 271                         return false;
 272                 }
 273                 password.length = pw_len;
 274
 275                 return kpasswdd_change_password(kdc, mem_ctx, session_info,
 276                                                 &password, reply);
 277         }
 278         case KRB5_KPASSWD_VERS_SETPW:
 279         {
 280                 NTSTATUS status;
 281                 enum samPwdChangeReason reject_reason = SAM_PWD_CHANGE_NO_ERROR;
 282                 struct samr_DomInfo1 *dominfo = NULL;
 283                 struct ldb_context *samdb;
 284                 krb5_context context = kdc->smb_krb5_context->krb5_context;
 285
 286                 ChangePasswdDataMS chpw;
 287                 DATA_BLOB password;
 288
 289                 krb5_principal principal;
 290                 char *set_password_on_princ;
 291                 struct ldb_dn *set_password_on_dn;
 292                 bool service_principal_name = false;
 293
 294                 size_t len;
 295                 int ret;
 296
 297                 ret = decode_ChangePasswdDataMS(input->data, input->length,
 298                                                 &chpw, &len);
 299                 if (ret) {
 300                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 301                                                         KRB5_KPASSWD_MALFORMED,
 302                                                         "failed to decode password change structure",
 303                                                         reply);
 304                 }
 305
 306                 if (!convert_string_talloc_convenience(mem_ctx, lpcfg_iconv_convenience(kdc->task->lp_ctx),
 307                                                CH_UTF8, CH_UTF16,
 308                                                (const char *)chpw.newpasswd.data,
 309                                                chpw.newpasswd.length,
 310                                                (void **)&password.data, &pw_len, false)) {
 311                         free_ChangePasswdDataMS(&chpw);
 312                         return false;
 313                 }
 314
 315                 password.length = pw_len;
 316
 317                 if ((chpw.targname && !chpw.targrealm)
 318                     || (!chpw.targname && chpw.targrealm)) {
 319                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 320                                                         KRB5_KPASSWD_MALFORMED,
 321                                                         "Realm and principal must be both present, or neither present",
 322                                                         reply);
 323                 }
 324                 if (chpw.targname && chpw.targrealm) {
 325 #ifdef SAMBA4_INTERNAL_HEIMDAL
 326                         if (_krb5_principalname2krb5_principal(kdc->smb_krb5_context->krb5_context,
 327                                                                &principal, *chpw.targname,
 328                                                                *chpw.targrealm) != 0) {
 329                                 free_ChangePasswdDataMS(&chpw);
 330                                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 331                                                                 KRB5_KPASSWD_MALFORMED,
 332                                                                 "failed to extract principal to set",
 333                                                                 reply);
 334
 335                         }
 336 #else /* SAMBA4_INTERNAL_HEIMDAL */
 337                                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 338                                                                 KRB5_KPASSWD_BAD_VERSION,
 339                                                                 "Operation Not Implemented",
 340                                                                 reply);
 341 #endif /* SAMBA4_INTERNAL_HEIMDAL */
 342                 } else {
 343                         free_ChangePasswdDataMS(&chpw);
 344                         return kpasswdd_change_password(kdc, mem_ctx, session_info,
 345                                                         &password, reply);
 346                 }
 347                 free_ChangePasswdDataMS(&chpw);
 348
 349                 if (principal->name.name_string.len >= 2) {
 350                         service_principal_name = true;
 351
 352                         /* We use this, rather than 'no realm' flag,
 353                          * as we don't want to accept a password
 354                          * change on a principal from another realm */
 355
 356                         if (krb5_unparse_name_short(context, principal, &set_password_on_princ) != 0) {
 357                                 krb5_free_principal(context, principal);
 358                                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 359                                                                  KRB5_KPASSWD_MALFORMED,
 360                                                                  "krb5_unparse_name failed!",
 361                                                                  reply);
 362                         }
 363                 } else {
 364                         if (krb5_unparse_name(context, principal, &set_password_on_princ) != 0) {
 365                                 krb5_free_principal(context, principal);
 366                                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 367                                                                  KRB5_KPASSWD_MALFORMED,
 368                                                                  "krb5_unparse_name failed!",
 369                                                                  reply);
 370                         }
 371                 }
 372                 krb5_free_principal(context, principal);
 373
 374                 samdb = samdb_connect(mem_ctx, kdc->task->event_ctx, kdc->task->lp_ctx, session_info, 0);
 375                 if (!samdb) {
 376                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 377                                                          KRB5_KPASSWD_HARDERROR,
 378                                                          "Unable to open database!",
 379                                                          reply);
 380                 }
 381
 382                 DEBUG(3, ("%s\\%s (%s) is changing password of %s\n",
 383                           session_info->server_info->domain_name,
 384                           session_info->server_info->account_name,
 385                           dom_sid_string(mem_ctx, &session_info->security_token->sids[PRIMARY_USER_SID_INDEX]),
 386                           set_password_on_princ));
 387                 ret = ldb_transaction_start(samdb);
 388                 if (ret != LDB_SUCCESS) {
 389                         status = NT_STATUS_TRANSACTION_ABORTED;
 390                         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 391                                                            status,
 392                                                            SAM_PWD_CHANGE_NO_ERROR,
 393                                                            NULL,
 394                                                            reply);
 395                 }
 396
 397                 if (service_principal_name) {
 398                         status = crack_service_principal_name(samdb, mem_ctx,
 399                                                               set_password_on_princ,
 400                                                               &set_password_on_dn, NULL);
 401                 } else {
 402                         status = crack_user_principal_name(samdb, mem_ctx,
 403                                                            set_password_on_princ,
 404                                                            &set_password_on_dn, NULL);
 405                 }
 406                 free(set_password_on_princ);
 407                 if (!NT_STATUS_IS_OK(status)) {
 408                         ldb_transaction_cancel(samdb);
 409                         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 410                                                            status,
 411                                                            SAM_PWD_CHANGE_NO_ERROR,
 412                                                            NULL,
 413                                                            reply);
 414                 }
 415
 416                 if (NT_STATUS_IS_OK(status)) {
 417                         /* Admin password set */
 418                         status = samdb_set_password(samdb, mem_ctx,
 419                                                     set_password_on_dn, NULL,
 420                                                     &password, NULL, NULL,
 421                                                     NULL, NULL, /* this is not a user password change */
 422                                                     &reject_reason, &dominfo);
 423                 }
 424
 425                 if (NT_STATUS_IS_OK(status)) {
 426                         ret = ldb_transaction_commit(samdb);
 427                         if (ret != LDB_SUCCESS) {
 428                                 DEBUG(1,("Failed to commit transaction to set password on %s: %s\n",
 429                                          ldb_dn_get_linearized(set_password_on_dn),
 430                                          ldb_errstring(samdb)));
 431                                 status = NT_STATUS_TRANSACTION_ABORTED;
 432                         }
 433                 } else {
 434                         ldb_transaction_cancel(samdb);
 435                 }
 436                 return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 437                                                    status,
 438                                                    reject_reason,
 439                                                    dominfo,
 440                                                    reply);
 441         }
 442         default:
 443                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 444                                                  KRB5_KPASSWD_BAD_VERSION,
 445                                                  talloc_asprintf(mem_ctx,
 446                                                                  "Protocol version %u not supported",
 447                                                                  version),
 448                                                  reply);
 449         }
 450 }
 451
 452 bool kpasswdd_process(struct kdc_server *kdc,
 453                       TALLOC_CTX *mem_ctx,
 454                       DATA_BLOB *input,
 455                       DATA_BLOB *reply,
 456                       struct tsocket_address *peer_addr,
 457                       struct tsocket_address *my_addr,
 458                       int datagram_reply)
 459 {
 460         bool ret;
 461         const uint16_t header_len = 6;
 462         uint16_t len;
 463         uint16_t ap_req_len;
 464         uint16_t krb_priv_len;
 465         uint16_t version;
 466         NTSTATUS nt_status;
 467         DATA_BLOB ap_req, krb_priv_req;
 468         DATA_BLOB krb_priv_rep = data_blob(NULL, 0);
 469         DATA_BLOB ap_rep = data_blob(NULL, 0);
 470         DATA_BLOB kpasswd_req, kpasswd_rep;
 471         struct cli_credentials *server_credentials;
 472         struct gensec_security *gensec_security;
 473         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 474
 475         char *keytab_name;
 476
 477         if (!tmp_ctx) {
 478                 return false;
 479         }
 480
 481         /* Be parinoid.  We need to ensure we don't just let the
 482          * caller lead us into a buffer overflow */
 483         if (input->length <= header_len) {
 484                 talloc_free(tmp_ctx);
 485                 return false;
 486         }
 487
 488         len = RSVAL(input->data, 0);
 489         if (input->length != len) {
 490                 talloc_free(tmp_ctx);
 491                 return false;
 492         }
 493
 494         /* There are two different versions of this protocol so far,
 495          * plus others in the standards pipe.  Fortunetly they all
 496          * take a very similar framing */
 497         version = RSVAL(input->data, 2);
 498         ap_req_len = RSVAL(input->data, 4);
 499         if ((ap_req_len >= len) || (ap_req_len + header_len) >= len) {
 500                 talloc_free(tmp_ctx);
 501                 return false;
 502         }
 503
 504         krb_priv_len = len - ap_req_len;
 505         ap_req = data_blob_const(&input->data[header_len], ap_req_len);
 506         krb_priv_req = data_blob_const(&input->data[header_len + ap_req_len], krb_priv_len);
 507
 508         server_credentials = cli_credentials_init(tmp_ctx);
 509         if (!server_credentials) {
 510                 DEBUG(1, ("Failed to init server credentials\n"));
 511                 return false;
 512         }
 513
 514         /* We want the credentials subsystem to use the krb5 context
 515          * we already have, rather than a new context */
 516         cli_credentials_set_krb5_context(server_credentials, kdc->smb_krb5_context);
 517         cli_credentials_set_conf(server_credentials, kdc->task->lp_ctx);
 518
 519         keytab_name = talloc_asprintf(server_credentials, "HDB:samba4&%p", kdc->base_ctx);
 520
 521         cli_credentials_set_username(server_credentials, "kadmin/changepw", CRED_SPECIFIED);
 522         ret = cli_credentials_set_keytab_name(server_credentials, kdc->task->lp_ctx, keytab_name, CRED_SPECIFIED);
 523         if (ret != 0) {
 524                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 525                                                        KRB5_KPASSWD_HARDERROR,
 526                                                        talloc_asprintf(mem_ctx,
 527                                                                        "Failed to obtain server credentials for kadmin/changepw: %s\n",
 528                                                                        nt_errstr(nt_status)),
 529                                                        &krb_priv_rep);
 530                 ap_rep.length = 0;
 531                 if (ret) {
 532                         goto reply;
 533                 }
 534                 talloc_free(tmp_ctx);
 535                 return ret;
 536         }
 537
 538         /* We don't strictly need to call this wrapper, and could call
 539          * gensec_server_start directly, as we have no need for NTLM
 540          * and we have a PAC, but this ensures that the wrapper can be
 541          * safely extended for other helpful things in future */
 542         nt_status = samba_server_gensec_start(tmp_ctx, kdc->task->event_ctx,
 543                                               kdc->task->msg_ctx,
 544                                               kdc->task->lp_ctx,
 545                                               server_credentials,
 546                                               "kpasswd",
 547                                               &gensec_security);
 548         if (!NT_STATUS_IS_OK(nt_status)) {
 549                 talloc_free(tmp_ctx);
 550                 return false;
 551         }
 552
 553         /* The kerberos PRIV packets include these addresses.  MIT
 554          * clients check that they are present */
 555 #if 0
 556         /* Skip this part for now, it breaks with a NetAPP filer and
 557          * in any case where the client address is behind NAT.  If
 558          * older MIT clients need this, we might have to insert more
 559          * complex code */
 560
 561         nt_status = gensec_set_local_address(gensec_security, peer_addr);
 562         if (!NT_STATUS_IS_OK(nt_status)) {
 563                 talloc_free(tmp_ctx);
 564                 return false;
 565         }
 566 #endif
 567
 568         nt_status = gensec_set_local_address(gensec_security, my_addr);
 569         if (!NT_STATUS_IS_OK(nt_status)) {
 570                 talloc_free(tmp_ctx);
 571                 return false;
 572         }
 573
 574         /* We want the GENSEC wrap calls to generate PRIV tokens */
 575         gensec_want_feature(gensec_security, GENSEC_FEATURE_SEAL);
 576
 577         nt_status = gensec_start_mech_by_name(gensec_security, "krb5");
 578         if (!NT_STATUS_IS_OK(nt_status)) {
 579                 talloc_free(tmp_ctx);
 580                 return false;
 581         }
 582
 583         /* Accept the AP-REQ and generate teh AP-REP we need for the reply */
 584         nt_status = gensec_update(gensec_security, tmp_ctx, ap_req, &ap_rep);
 585         if (!NT_STATUS_IS_OK(nt_status) && !NT_STATUS_EQUAL(nt_status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
 586
 587                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 588                                                        KRB5_KPASSWD_HARDERROR,
 589                                                        talloc_asprintf(mem_ctx,
 590                                                                        "gensec_update failed: %s",
 591                                                                        nt_errstr(nt_status)),
 592                                                        &krb_priv_rep);
 593                 ap_rep.length = 0;
 594                 if (ret) {
 595                         goto reply;
 596                 }
 597                 talloc_free(tmp_ctx);
 598                 return ret;
 599         }
 600
 601         /* Extract the data from the KRB-PRIV half of the message */
 602         nt_status = gensec_unwrap(gensec_security, tmp_ctx, &krb_priv_req, &kpasswd_req);
 603         if (!NT_STATUS_IS_OK(nt_status)) {
 604                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 605                                                        KRB5_KPASSWD_HARDERROR,
 606                                                        talloc_asprintf(mem_ctx,
 607                                                                        "gensec_unwrap failed: %s",
 608                                                                        nt_errstr(nt_status)),
 609                                                        &krb_priv_rep);
 610                 ap_rep.length = 0;
 611                 if (ret) {
 612                         goto reply;
 613                 }
 614                 talloc_free(tmp_ctx);
 615                 return ret;
 616         }
 617
 618         /* Figure out something to do with it (probably changing a password...) */
 619         ret = kpasswd_process_request(kdc, tmp_ctx,
 620                                       gensec_security,
 621                                       version,
 622                                       &kpasswd_req, &kpasswd_rep);
 623         if (!ret) {
 624                 /* Argh! */
 625                 return false;
 626         }
 627
 628         /* And wrap up the reply: This ensures that the error message
 629          * or success can be verified by the client */
 630         nt_status = gensec_wrap(gensec_security, tmp_ctx,
 631                                 &kpasswd_rep, &krb_priv_rep);
 632         if (!NT_STATUS_IS_OK(nt_status)) {
 633                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 634                                                        KRB5_KPASSWD_HARDERROR,
 635                                                        talloc_asprintf(mem_ctx,
 636                                                                        "gensec_wrap failed: %s",
 637                                                                        nt_errstr(nt_status)),
 638                                                        &krb_priv_rep);
 639                 ap_rep.length = 0;
 640                 if (ret) {
 641                         goto reply;
 642                 }
 643                 talloc_free(tmp_ctx);
 644                 return ret;
 645         }
 646
 647 reply:
 648         *reply = data_blob_talloc(mem_ctx, NULL, krb_priv_rep.length + ap_rep.length + header_len);
 649         if (!reply->data) {
 650                 return false;
 651         }
 652
 653         RSSVAL(reply->data, 0, reply->length);
 654         RSSVAL(reply->data, 2, 1); /* This is a version 1 reply, MS change/set or otherwise */
 655         RSSVAL(reply->data, 4, ap_rep.length);
 656         memcpy(reply->data + header_len,
 657                ap_rep.data,
 658                ap_rep.length);
 659         memcpy(reply->data + header_len + ap_rep.length,
 660                krb_priv_rep.data,
 661                krb_priv_rep.length);
 662
 663         talloc_free(tmp_ctx);
 664         return ret;
 665 }
 666