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