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 2 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, write to the Free Software
  21    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22 */
  23
  24 #include "includes.h"
  25 #include "smbd/service_task.h"
  26 #include "lib/events/events.h"
  27 #include "lib/socket/socket.h"
  28 #include "kdc/kdc.h"
  29 #include "system/network.h"
  30 #include "dlinklist.h"
  31 #include "lib/ldb/include/ldb.h"
  32 #include "heimdal/lib/krb5/krb5-private.h"
  33 #include "auth/auth.h"
  34 #include "dsdb/samdb/samdb.h"
  35 #include "rpc_server/samr/proto.h"
  36
  37 /* hold information about one kdc socket */
  38 struct kpasswd_socket {
  39         struct socket_context *sock;
  40         struct kdc_server *kdc;
  41         struct fd_event *fde;
  42
  43         /* a queue of outgoing replies that have been deferred */
  44         struct kdc_reply *send_queue;
  45 };
  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         ssize_t len;
  56
  57         DEBUG(result_code ? 3 : 10, ("kpasswdd: %s\n", error_string));
  58
  59         len = push_utf8_talloc(mem_ctx, &error_string_utf8, error_string);
  60         if (len == -1) {
  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 samr_RejectReason 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 (NT_STATUS_EQUAL(status, NT_STATUS_PASSWORD_RESTRICTION)) {
 125                 const char *reject_string;
 126                 switch (reject_reason) {
 127                 case SAMR_REJECT_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 SAMR_REJECT_COMPLEXITY:
 132                         reject_string = "Password does not meet complexity requirements";
 133                         break;
 134                 case SAMR_REJECT_OTHER:
 135                 default:
 136                         reject_string = talloc_asprintf(mem_ctx, "Password must be at least %d characters long, and cannot match any of your %d previous passwords",
 137                                                         dominfo->min_password_length, dominfo->password_history_length);
 138                         break;
 139                 }
 140                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 141                                                 KRB5_KPASSWD_SOFTERROR,
 142                                                 reject_string,
 143                                                 error_blob);
 144         }
 145         if (!NT_STATUS_IS_OK(status)) {
 146                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 147                                                  KRB5_KPASSWD_HARDERROR,
 148                                                  talloc_asprintf(mem_ctx, "failed to set password: %s", nt_errstr(status)),
 149                                                  error_blob);
 150
 151         }
 152         return kpasswdd_make_error_reply(kdc, mem_ctx, KRB5_KPASSWD_SUCCESS,
 153                                         "Password changed",
 154                                         error_blob);
 155 }
 156
 157 /*
 158    A user password change
 159
 160    Return true if there is a valid error packet (or sucess) formed in
 161    the error_blob
 162 */
 163 static BOOL kpasswdd_change_password(struct kdc_server *kdc,
 164                                      TALLOC_CTX *mem_ctx,
 165                                      struct auth_session_info *session_info,
 166                                      const char *password,
 167                                      DATA_BLOB *reply)
 168 {
 169         NTSTATUS status;
 170         enum samr_RejectReason reject_reason;
 171         struct samr_DomInfo1 *dominfo;
 172         struct ldb_context *samdb;
 173
 174         samdb = samdb_connect(mem_ctx, system_session(mem_ctx));
 175         if (!samdb) {
 176                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 177                                                 KRB5_KPASSWD_HARDERROR,
 178                                                 "Failed to open samdb",
 179                                                 reply);
 180         }
 181
 182         DEBUG(3, ("Changing password of %s\\%s (%s)\n",
 183                   session_info->server_info->domain_name,
 184                   session_info->server_info->account_name,
 185                   dom_sid_string(mem_ctx, session_info->security_token->user_sid)));
 186
 187         /* User password change */
 188         status = samdb_set_password_sid(samdb, mem_ctx,
 189                                         session_info->security_token->user_sid,
 190                                         password, NULL, NULL,
 191                                         True, /* this is a user password change */
 192                                         True, /* run restriction tests */
 193                                         &reject_reason,
 194                                         &dominfo);
 195         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 196                                            status,
 197                                            reject_reason,
 198                                            dominfo,
 199                                            reply);
 200
 201 }
 202
 203 static BOOL kpasswd_process_request(struct kdc_server *kdc,
 204                                     TALLOC_CTX *mem_ctx,
 205                                     struct gensec_security *gensec_security,
 206                                     uint16_t version,
 207                                     DATA_BLOB *input,
 208                                     DATA_BLOB *reply)
 209 {
 210         struct auth_session_info *session_info;
 211         if (!NT_STATUS_IS_OK(gensec_session_info(gensec_security,
 212                                                  &session_info))) {
 213                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 214                                                 KRB5_KPASSWD_HARDERROR,
 215                                                 "gensec_session_info failed!",
 216                                                 reply);
 217         }
 218
 219         switch (version) {
 220         case KRB5_KPASSWD_VERS_CHANGEPW:
 221         {
 222                 char *password = talloc_strndup(mem_ctx, (const char *)input->data, input->length);
 223                 if (!password) {
 224                         return False;
 225                 }
 226                 return kpasswdd_change_password(kdc, mem_ctx, session_info,
 227                                                 password, reply);
 228                 break;
 229         }
 230         case KRB5_KPASSWD_VERS_SETPW:
 231         {
 232                 NTSTATUS status;
 233                 enum samr_RejectReason reject_reason;
 234                 struct samr_DomInfo1 *dominfo;
 235                 struct ldb_context *samdb;
 236                 struct ldb_message *msg;
 237                 krb5_context context = kdc->smb_krb5_context->krb5_context;
 238
 239                 ChangePasswdDataMS chpw;
 240                 char *password;
 241
 242                 krb5_principal principal;
 243                 char *set_password_on_princ;
 244                 struct ldb_dn *set_password_on_dn;
 245
 246                 size_t len;
 247                 int ret;
 248
 249                 msg = ldb_msg_new(mem_ctx);
 250                 if (!msg) {
 251                         return False;
 252                 }
 253
 254                 ret = decode_ChangePasswdDataMS(input->data, input->length,
 255                                                 &chpw, &len);
 256                 if (ret) {
 257                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 258                                                         KRB5_KPASSWD_MALFORMED,
 259                                                         "failed to decode password change structure",
 260                                                         reply);
 261                 }
 262
 263                 password = talloc_strndup(mem_ctx, chpw.newpasswd.data,
 264                                           chpw.newpasswd.length);
 265                 if (!password) {
 266                         free_ChangePasswdDataMS(&chpw);
 267                         return False;
 268                 }
 269                 if ((chpw.targname && !chpw.targrealm)
 270                     || (!chpw.targname && chpw.targrealm)) {
 271                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 272                                                         KRB5_KPASSWD_MALFORMED,
 273                                                         "Realm and principal must be both present, or neither present",
 274                                                         reply);
 275                 }
 276                 if (chpw.targname && chpw.targrealm) {
 277                         if (_krb5_principalname2krb5_principal(&principal, *chpw.targname,
 278                                                                *chpw.targrealm) != 0) {
 279                                 free_ChangePasswdDataMS(&chpw);
 280                                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 281                                                                 KRB5_KPASSWD_MALFORMED,
 282                                                                 "failed to extract principal to set",
 283                                                                 reply);
 284
 285                         }
 286                 } else {
 287                         free_ChangePasswdDataMS(&chpw);
 288                         return kpasswdd_change_password(kdc, mem_ctx, session_info,
 289                                                         password, reply);
 290                 }
 291                 free_ChangePasswdDataMS(&chpw);
 292
 293                 if (krb5_unparse_name(context, principal, &set_password_on_princ) != 0) {
 294                         krb5_free_principal(context, principal);
 295                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 296                                                         KRB5_KPASSWD_MALFORMED,
 297                                                         "krb5_unparse_name failed!",
 298                                                         reply);
 299                 }
 300
 301                 krb5_free_principal(context, principal);
 302
 303                 samdb = samdb_connect(mem_ctx, session_info);
 304                 if (!samdb) {
 305                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 306                                                          KRB5_KPASSWD_HARDERROR,
 307                                                          "Unable to open database!",
 308                                                          reply);
 309                 }
 310
 311                 DEBUG(3, ("%s\\%s (%s) is changing password of %s\n",
 312                           session_info->server_info->domain_name,
 313                           session_info->server_info->account_name,
 314                           dom_sid_string(mem_ctx, session_info->security_token->user_sid),
 315                           set_password_on_princ));
 316                 ret = ldb_transaction_start(samdb);
 317                 if (ret) {
 318                         status = NT_STATUS_TRANSACTION_ABORTED;
 319                         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 320                                                            status,
 321                                                            reject_reason,
 322                                                            dominfo,
 323                                                            reply);
 324                 }
 325
 326                 status = crack_user_principal_name(samdb, mem_ctx,
 327                                                    set_password_on_princ,
 328                                                    &set_password_on_dn, NULL);
 329                 free(set_password_on_princ);
 330                 if (!NT_STATUS_IS_OK(status)) {
 331                         ldb_transaction_cancel(samdb);
 332                         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 333                                                            status,
 334                                                            reject_reason,
 335                                                            dominfo,
 336                                                            reply);
 337                 }
 338
 339                 msg = ldb_msg_new(mem_ctx);
 340                 if (msg == NULL) {
 341                         ldb_transaction_cancel(samdb);
 342                         status = NT_STATUS_NO_MEMORY;
 343                 } else {
 344                         msg->dn = ldb_dn_copy(msg, set_password_on_dn);
 345                         if (!msg->dn) {
 346                                 status = NT_STATUS_NO_MEMORY;
 347                         }
 348                 }
 349
 350                 if (NT_STATUS_IS_OK(status)) {
 351                         /* Admin password set */
 352                         status = samdb_set_password(samdb, mem_ctx,
 353                                                     set_password_on_dn, NULL,
 354                                                     msg, password, NULL, NULL,
 355                                                     False, /* this is not a user password change */
 356                                                     True, /* run restriction tests */
 357                                                     &reject_reason, &dominfo);
 358                 }
 359
 360                 if (NT_STATUS_IS_OK(status)) {
 361                         /* modify the samdb record */
 362                         ret = samdb_replace(samdb, mem_ctx, msg);
 363                         if (ret != 0) {
 364                                 DEBUG(2,("Failed to modify record to set password on %s: %s\n",
 365                                          ldb_dn_linearize(mem_ctx, msg->dn),
 366                                          ldb_errstring(samdb)));
 367                                 status = NT_STATUS_ACCESS_DENIED;
 368                         }
 369                 }
 370                 if (NT_STATUS_IS_OK(status)) {
 371                         ret = ldb_transaction_commit(samdb);
 372                         if (ret != 0) {
 373                                 DEBUG(1,("Failed to commit transaction to set password on %s: %s\n",
 374                                          ldb_dn_linearize(mem_ctx, msg->dn),
 375                                          ldb_errstring(samdb)));
 376                                 status = NT_STATUS_TRANSACTION_ABORTED;
 377                         }
 378                 } else {
 379                         ldb_transaction_cancel(samdb);
 380                 }
 381                 return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 382                                                    status,
 383                                                    reject_reason,
 384                                                    dominfo,
 385                                                    reply);
 386         }
 387         default:
 388                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 389                                                  KRB5_KPASSWD_BAD_VERSION,
 390                                                  talloc_asprintf(mem_ctx,
 391                                                                  "Protocol version %u not supported",
 392                                                                  version),
 393                                                  reply);
 394         }
 395         return True;
 396 }
 397
 398 BOOL kpasswdd_process(struct kdc_server *kdc,
 399                       TALLOC_CTX *mem_ctx,
 400                       DATA_BLOB *input,
 401                       DATA_BLOB *reply,
 402                       struct socket_address *peer_addr,
 403                       struct socket_address *my_addr)
 404 {
 405         BOOL ret;
 406         const uint16_t header_len = 6;
 407         uint16_t len;
 408         uint16_t ap_req_len;
 409         uint16_t krb_priv_len;
 410         uint16_t version;
 411         NTSTATUS nt_status;
 412         DATA_BLOB ap_req, krb_priv_req, krb_priv_rep, ap_rep;
 413         DATA_BLOB kpasswd_req, kpasswd_rep;
 414         struct cli_credentials *server_credentials;
 415         struct gensec_security *gensec_security;
 416         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 417
 418         if (!tmp_ctx) {
 419                 return False;
 420         }
 421
 422         /* Be parinoid.  We need to ensure we don't just let the
 423          * caller lead us into a buffer overflow */
 424         if (input->length <= header_len) {
 425                 talloc_free(tmp_ctx);
 426                 return False;
 427         }
 428
 429         len = RSVAL(input->data, 0);
 430         if (input->length != len) {
 431                 talloc_free(tmp_ctx);
 432                 return False;
 433         }
 434
 435         /* There are two different versions of this protocol so far,
 436          * plus others in the standards pipe.  Fortunetly they all
 437          * take a very similar framing */
 438         version = RSVAL(input->data, 2);
 439         ap_req_len = RSVAL(input->data, 4);
 440         if ((ap_req_len >= len) || (ap_req_len + header_len) >= len) {
 441                 talloc_free(tmp_ctx);
 442                 return False;
 443         }
 444
 445         krb_priv_len = len - ap_req_len;
 446         ap_req = data_blob_const(&input->data[header_len], ap_req_len);
 447         krb_priv_req = data_blob_const(&input->data[header_len + ap_req_len], krb_priv_len);
 448
 449         nt_status = gensec_server_start(tmp_ctx, &gensec_security, kdc->task->event_ctx);
 450         if (!NT_STATUS_IS_OK(nt_status)) {
 451                 talloc_free(tmp_ctx);
 452                 return False;
 453         }
 454
 455         server_credentials
 456                 = cli_credentials_init(tmp_ctx);
 457         if (!server_credentials) {
 458                 DEBUG(1, ("Failed to init server credentials\n"));
 459                 return False;
 460         }
 461
 462         /* We want the credentials subsystem to use the krb5 context
 463          * we already have, rather than a new context */
 464         cli_credentials_set_krb5_context(server_credentials, kdc->smb_krb5_context);
 465         cli_credentials_set_conf(server_credentials);
 466         nt_status = cli_credentials_set_stored_principal(server_credentials, "kadmin/changepw");
 467         if (!NT_STATUS_IS_OK(nt_status)) {
 468                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 469                                                        KRB5_KPASSWD_HARDERROR,
 470                                                        talloc_asprintf(mem_ctx,
 471                                                                        "Failed to obtain server credentials for kadmin/changepw: %s\n",
 472                                                                        nt_errstr(nt_status)),
 473                                                        &krb_priv_rep);
 474                 ap_rep.length = 0;
 475                 if (ret) {
 476                         goto reply;
 477                 }
 478                 talloc_free(tmp_ctx);
 479                 return ret;
 480         }
 481
 482         nt_status = gensec_set_credentials(gensec_security, server_credentials);
 483         if (!NT_STATUS_IS_OK(nt_status)) {
 484                 talloc_free(tmp_ctx);
 485                 return False;
 486         }
 487
 488         /* The kerberos PRIV packets include these addresses.  MIT
 489          * clients check that they are present */
 490         nt_status = gensec_set_peer_addr(gensec_security, peer_addr);
 491         if (!NT_STATUS_IS_OK(nt_status)) {
 492                 talloc_free(tmp_ctx);
 493                 return False;
 494         }
 495         nt_status = gensec_set_my_addr(gensec_security, my_addr);
 496         if (!NT_STATUS_IS_OK(nt_status)) {
 497                 talloc_free(tmp_ctx);
 498                 return False;
 499         }
 500
 501         /* We want the GENSEC wrap calls to generate PRIV tokens */
 502         gensec_want_feature(gensec_security, GENSEC_FEATURE_SEAL);
 503
 504         nt_status = gensec_start_mech_by_name(gensec_security, "krb5");
 505         if (!NT_STATUS_IS_OK(nt_status)) {
 506                 talloc_free(tmp_ctx);
 507                 return False;
 508         }
 509
 510         /* Accept the AP-REQ and generate teh AP-REP we need for the reply */
 511         nt_status = gensec_update(gensec_security, tmp_ctx, ap_req, &ap_rep);
 512         if (!NT_STATUS_IS_OK(nt_status) && !NT_STATUS_EQUAL(nt_status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
 513
 514                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 515                                                        KRB5_KPASSWD_HARDERROR,
 516                                                        talloc_asprintf(mem_ctx,
 517                                                                        "gensec_update failed: %s",
 518                                                                        nt_errstr(nt_status)),
 519                                                        &krb_priv_rep);
 520                 ap_rep.length = 0;
 521                 if (ret) {
 522                         goto reply;
 523                 }
 524                 talloc_free(tmp_ctx);
 525                 return ret;
 526         }
 527
 528         /* Extract the data from the KRB-PRIV half of the message */
 529         nt_status = gensec_unwrap(gensec_security, tmp_ctx, &krb_priv_req, &kpasswd_req);
 530         if (!NT_STATUS_IS_OK(nt_status)) {
 531                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 532                                                        KRB5_KPASSWD_HARDERROR,
 533                                                        talloc_asprintf(mem_ctx,
 534                                                                        "gensec_unwrap failed: %s",
 535                                                                        nt_errstr(nt_status)),
 536                                                        &krb_priv_rep);
 537                 ap_rep.length = 0;
 538                 if (ret) {
 539                         goto reply;
 540                 }
 541                 talloc_free(tmp_ctx);
 542                 return ret;
 543         }
 544
 545         /* Figure out something to do with it (probably changing a password...) */
 546         ret = kpasswd_process_request(kdc, tmp_ctx,
 547                                       gensec_security,
 548                                       version,
 549                                       &kpasswd_req, &kpasswd_rep);
 550         if (!ret) {
 551                 /* Argh! */
 552                 return False;
 553         }
 554
 555         /* And wrap up the reply: This ensures that the error message
 556          * or success can be verified by the client */
 557         nt_status = gensec_wrap(gensec_security, tmp_ctx,
 558                                 &kpasswd_rep, &krb_priv_rep);
 559         if (!NT_STATUS_IS_OK(nt_status)) {
 560                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 561                                                        KRB5_KPASSWD_HARDERROR,
 562                                                        talloc_asprintf(mem_ctx,
 563                                                                        "gensec_wrap failed: %s",
 564                                                                        nt_errstr(nt_status)),
 565                                                        &krb_priv_rep);
 566                 ap_rep.length = 0;
 567                 if (ret) {
 568                         goto reply;
 569                 }
 570                 talloc_free(tmp_ctx);
 571                 return ret;
 572         }
 573
 574 reply:
 575         *reply = data_blob_talloc(mem_ctx, NULL, krb_priv_rep.length + ap_rep.length + header_len);
 576         if (!reply->data) {
 577                 return False;
 578         }
 579
 580         RSSVAL(reply->data, 0, reply->length);
 581         RSSVAL(reply->data, 2, 1); /* This is a version 1 reply, MS change/set or otherwise */
 582         RSSVAL(reply->data, 4, ap_rep.length);
 583         memcpy(reply->data + header_len,
 584                ap_rep.data,
 585                ap_rep.length);
 586         memcpy(reply->data + header_len + ap_rep.length,
 587                krb_priv_rep.data,
 588                krb_priv_rep.length);
 589
 590         talloc_free(tmp_ctx);
 591         return ret;
 592 }
 593