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
  36 /* hold information about one kdc socket */
  37 struct kpasswd_socket {
  38         struct socket_context *sock;
  39         struct kdc_server *kdc;
  40         struct fd_event *fde;
  41
  42         /* a queue of outgoing replies that have been deferred */
  43         struct kdc_reply *send_queue;
  44 };
  45
  46 /* Return true if there is a valid error packet formed in the error_blob */
  47 static BOOL kpasswdd_make_error_reply(struct kdc_server *kdc,
  48                                      TALLOC_CTX *mem_ctx,
  49                                      uint16_t result_code,
  50                                      const char *error_string,
  51                                      DATA_BLOB *error_blob)
  52 {
  53         char *error_string_utf8;
  54         ssize_t len;
  55
  56         DEBUG(result_code ? 3 : 10, ("kpasswdd: %s\n", error_string));
  57
  58         len = push_utf8_talloc(mem_ctx, &error_string_utf8, error_string);
  59         if (len == -1) {
  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 samr_RejectReason 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 (NT_STATUS_EQUAL(status, NT_STATUS_PASSWORD_RESTRICTION)) {
 124                 const char *reject_string;
 125                 switch (reject_reason) {
 126                 case SAMR_REJECT_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 SAMR_REJECT_COMPLEXITY:
 131                         reject_string = "Password does not meet complexity requirements";
 132                         break;
 133                 case SAMR_REJECT_OTHER:
 134                 default:
 135                         reject_string = talloc_asprintf(mem_ctx, "Password must be at least %d characters long, and cannot match any of your %d previous passwords",
 136                                                         dominfo->min_password_length, dominfo->password_history_length);
 137                         break;
 138                 }
 139                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 140                                                 KRB5_KPASSWD_SOFTERROR,
 141                                                 reject_string,
 142                                                 error_blob);
 143         }
 144         if (!NT_STATUS_IS_OK(status)) {
 145                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 146                                                  KRB5_KPASSWD_HARDERROR,
 147                                                  talloc_asprintf(mem_ctx, "failed to set password: %s", nt_errstr(status)),
 148                                                  error_blob);
 149
 150         }
 151         return kpasswdd_make_error_reply(kdc, mem_ctx, KRB5_KPASSWD_SUCCESS,
 152                                         "Password changed",
 153                                         error_blob);
 154 }
 155
 156 /*
 157    A user password change
 158
 159    Return true if there is a valid error packet (or sucess) formed in
 160    the error_blob
 161 */
 162 static BOOL kpasswdd_change_password(struct kdc_server *kdc,
 163                                      TALLOC_CTX *mem_ctx,
 164                                      struct auth_session_info *session_info,
 165                                      const char *password,
 166                                      DATA_BLOB *reply)
 167 {
 168         NTSTATUS status;
 169         enum samr_RejectReason reject_reason;
 170         struct samr_DomInfo1 *dominfo;
 171         struct ldb_context *samdb;
 172
 173         samdb = samdb_connect(mem_ctx, system_session(mem_ctx));
 174         if (!samdb) {
 175                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 176                                                 KRB5_KPASSWD_HARDERROR,
 177                                                 "Failed to open samdb",
 178                                                 reply);
 179         }
 180
 181         DEBUG(3, ("Changing password of %s\\%s (%s)\n",
 182                   session_info->server_info->domain_name,
 183                   session_info->server_info->account_name,
 184                   dom_sid_string(mem_ctx, session_info->security_token->user_sid)));
 185
 186         /* User password change */
 187         status = samdb_set_password_sid(samdb, mem_ctx,
 188                                         session_info->security_token->user_sid,
 189                                         password, NULL, NULL,
 190                                         True, /* this is a user password change */
 191                                         True, /* run restriction tests */
 192                                         &reject_reason,
 193                                         &dominfo);
 194         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 195                                            status,
 196                                            reject_reason,
 197                                            dominfo,
 198                                            reply);
 199
 200 }
 201
 202 static BOOL kpasswd_process_request(struct kdc_server *kdc,
 203                                     TALLOC_CTX *mem_ctx,
 204                                     struct gensec_security *gensec_security,
 205                                     uint16_t version,
 206                                     DATA_BLOB *input,
 207                                     DATA_BLOB *reply)
 208 {
 209         struct auth_session_info *session_info;
 210         if (!NT_STATUS_IS_OK(gensec_session_info(gensec_security,
 211                                                  &session_info))) {
 212                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 213                                                 KRB5_KPASSWD_HARDERROR,
 214                                                 "gensec_session_info failed!",
 215                                                 reply);
 216         }
 217
 218         switch (version) {
 219         case KRB5_KPASSWD_VERS_CHANGEPW:
 220         {
 221                 char *password = talloc_strndup(mem_ctx, (const char *)input->data, input->length);
 222                 if (!password) {
 223                         return False;
 224                 }
 225                 return kpasswdd_change_password(kdc, mem_ctx, session_info,
 226                                                 password, reply);
 227                 break;
 228         }
 229         case KRB5_KPASSWD_VERS_SETPW:
 230         {
 231                 NTSTATUS status;
 232                 enum samr_RejectReason reject_reason;
 233                 struct samr_DomInfo1 *dominfo;
 234                 struct ldb_context *samdb;
 235                 struct ldb_message *msg;
 236                 krb5_context context = kdc->smb_krb5_context->krb5_context;
 237
 238                 ChangePasswdDataMS chpw;
 239                 char *password;
 240
 241                 krb5_principal principal;
 242                 char *set_password_on_princ;
 243                 struct ldb_dn *set_password_on_dn;
 244
 245                 size_t len;
 246                 int ret;
 247
 248                 msg = ldb_msg_new(mem_ctx);
 249                 if (!msg) {
 250                         return False;
 251                 }
 252
 253                 ret = decode_ChangePasswdDataMS(input->data, input->length,
 254                                                 &chpw, &len);
 255                 if (ret) {
 256                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 257                                                         KRB5_KPASSWD_MALFORMED,
 258                                                         "failed to decode password change structure",
 259                                                         reply);
 260                 }
 261
 262                 password = talloc_strndup(mem_ctx, chpw.newpasswd.data,
 263                                           chpw.newpasswd.length);
 264                 if (!password) {
 265                         free_ChangePasswdDataMS(&chpw);
 266                         return False;
 267                 }
 268                 if ((chpw.targname && !chpw.targrealm)
 269                     || (!chpw.targname && chpw.targrealm)) {
 270                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 271                                                         KRB5_KPASSWD_MALFORMED,
 272                                                         "Realm and principal must be both present, or neither present",
 273                                                         reply);
 274                 }
 275                 if (chpw.targname && chpw.targrealm) {
 276                         if (_krb5_principalname2krb5_principal(&principal, *chpw.targname,
 277                                                                *chpw.targrealm) != 0) {
 278                                 free_ChangePasswdDataMS(&chpw);
 279                                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 280                                                                 KRB5_KPASSWD_MALFORMED,
 281                                                                 "failed to extract principal to set",
 282                                                                 reply);
 283
 284                         }
 285                 } else {
 286                         free_ChangePasswdDataMS(&chpw);
 287                         return kpasswdd_change_password(kdc, mem_ctx, session_info,
 288                                                         password, reply);
 289                 }
 290                 free_ChangePasswdDataMS(&chpw);
 291
 292                 if (krb5_unparse_name(context, principal, &set_password_on_princ) != 0) {
 293                         krb5_free_principal(context, principal);
 294                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 295                                                         KRB5_KPASSWD_MALFORMED,
 296                                                         "krb5_unparse_name failed!",
 297                                                         reply);
 298                 }
 299
 300                 krb5_free_principal(context, principal);
 301
 302                 samdb = samdb_connect(mem_ctx, session_info);
 303                 if (!samdb) {
 304                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 305                                                          KRB5_KPASSWD_HARDERROR,
 306                                                          "Unable to open database!",
 307                                                          reply);
 308                 }
 309
 310                 DEBUG(3, ("%s\\%s (%s) is changing password of %s\n",
 311                           session_info->server_info->domain_name,
 312                           session_info->server_info->account_name,
 313                           dom_sid_string(mem_ctx, session_info->security_token->user_sid),
 314                           set_password_on_princ));
 315                 ret = ldb_transaction_start(samdb);
 316                 if (ret) {
 317                         status = NT_STATUS_TRANSACTION_ABORTED;
 318                         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 319                                                            status,
 320                                                            reject_reason,
 321                                                            dominfo,
 322                                                            reply);
 323                 }
 324
 325                 status = crack_user_principal_name(samdb, mem_ctx,
 326                                                    set_password_on_princ,
 327                                                    &set_password_on_dn, NULL);
 328                 free(set_password_on_princ);
 329                 if (!NT_STATUS_IS_OK(status)) {
 330                         ldb_transaction_cancel(samdb);
 331                         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 332                                                            status,
 333                                                            reject_reason,
 334                                                            dominfo,
 335                                                            reply);
 336                 }
 337
 338                 msg = ldb_msg_new(mem_ctx);
 339                 if (msg == NULL) {
 340                         ldb_transaction_cancel(samdb);
 341                         status = NT_STATUS_NO_MEMORY;
 342                 } else {
 343                         msg->dn = ldb_dn_copy(msg, set_password_on_dn);
 344                         if (!msg->dn) {
 345                                 status = NT_STATUS_NO_MEMORY;
 346                         }
 347                 }
 348
 349                 if (NT_STATUS_IS_OK(status)) {
 350                         /* Admin password set */
 351                         status = samdb_set_password(samdb, mem_ctx,
 352                                                     set_password_on_dn, NULL,
 353                                                     msg, password, NULL, NULL,
 354                                                     False, /* this is not a user password change */
 355                                                     True, /* run restriction tests */
 356                                                     &reject_reason, &dominfo);
 357                 }
 358
 359                 if (NT_STATUS_IS_OK(status)) {
 360                         /* modify the samdb record */
 361                         ret = samdb_replace(samdb, mem_ctx, msg);
 362                         if (ret != 0) {
 363                                 DEBUG(2,("Failed to modify record to set password on %s: %s\n",
 364                                          ldb_dn_linearize(mem_ctx, msg->dn),
 365                                          ldb_errstring(samdb)));
 366                                 status = NT_STATUS_ACCESS_DENIED;
 367                         }
 368                 }
 369                 if (NT_STATUS_IS_OK(status)) {
 370                         ret = ldb_transaction_commit(samdb);
 371                         if (ret != 0) {
 372                                 DEBUG(1,("Failed to commit transaction to set password on %s: %s\n",
 373                                          ldb_dn_linearize(mem_ctx, msg->dn),
 374                                          ldb_errstring(samdb)));
 375                                 status = NT_STATUS_TRANSACTION_ABORTED;
 376                         }
 377                 } else {
 378                         ldb_transaction_cancel(samdb);
 379                 }
 380                 return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 381                                                    status,
 382                                                    reject_reason,
 383                                                    dominfo,
 384                                                    reply);
 385         }
 386         default:
 387                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 388                                                  KRB5_KPASSWD_BAD_VERSION,
 389                                                  talloc_asprintf(mem_ctx,
 390                                                                  "Protocol version %u not supported",
 391                                                                  version),
 392                                                  reply);
 393         }
 394         return True;
 395 }
 396
 397 BOOL kpasswdd_process(struct kdc_server *kdc,
 398                       TALLOC_CTX *mem_ctx,
 399                       DATA_BLOB *input,
 400                       DATA_BLOB *reply,
 401                       struct socket_address *peer_addr,
 402                       struct socket_address *my_addr)
 403 {
 404         BOOL ret;
 405         const uint16_t header_len = 6;
 406         uint16_t len;
 407         uint16_t ap_req_len;
 408         uint16_t krb_priv_len;
 409         uint16_t version;
 410         NTSTATUS nt_status;
 411         DATA_BLOB ap_req, krb_priv_req, krb_priv_rep, ap_rep;
 412         DATA_BLOB kpasswd_req, kpasswd_rep;
 413         struct cli_credentials *server_credentials;
 414         struct gensec_security *gensec_security;
 415         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 416
 417         if (!tmp_ctx) {
 418                 return False;
 419         }
 420
 421         /* Be parinoid.  We need to ensure we don't just let the
 422          * caller lead us into a buffer overflow */
 423         if (input->length <= header_len) {
 424                 talloc_free(tmp_ctx);
 425                 return False;
 426         }
 427
 428         len = RSVAL(input->data, 0);
 429         if (input->length != len) {
 430                 talloc_free(tmp_ctx);
 431                 return False;
 432         }
 433
 434         /* There are two different versions of this protocol so far,
 435          * plus others in the standards pipe.  Fortunetly they all
 436          * take a very similar framing */
 437         version = RSVAL(input->data, 2);
 438         ap_req_len = RSVAL(input->data, 4);
 439         if ((ap_req_len >= len) || (ap_req_len + header_len) >= len) {
 440                 talloc_free(tmp_ctx);
 441                 return False;
 442         }
 443
 444         krb_priv_len = len - ap_req_len;
 445         ap_req = data_blob_const(&input->data[header_len], ap_req_len);
 446         krb_priv_req = data_blob_const(&input->data[header_len + ap_req_len], krb_priv_len);
 447
 448         nt_status = gensec_server_start(tmp_ctx, &gensec_security, kdc->task->event_ctx);
 449         if (!NT_STATUS_IS_OK(nt_status)) {
 450                 talloc_free(tmp_ctx);
 451                 return False;
 452         }
 453
 454         server_credentials
 455                 = cli_credentials_init(tmp_ctx);
 456         if (!server_credentials) {
 457                 DEBUG(1, ("Failed to init server credentials\n"));
 458                 return False;
 459         }
 460
 461         /* We want the credentials subsystem to use the krb5 context
 462          * we already have, rather than a new context */
 463         cli_credentials_set_krb5_context(server_credentials, kdc->smb_krb5_context);
 464         cli_credentials_set_conf(server_credentials);
 465         nt_status = cli_credentials_set_stored_principal(server_credentials, "kadmin/changepw");
 466         if (!NT_STATUS_IS_OK(nt_status)) {
 467                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 468                                                        KRB5_KPASSWD_HARDERROR,
 469                                                        talloc_asprintf(mem_ctx,
 470                                                                        "Failed to obtain server credentials for kadmin/changepw: %s\n",
 471                                                                        nt_errstr(nt_status)),
 472                                                        &krb_priv_rep);
 473                 ap_rep.length = 0;
 474                 if (ret) {
 475                         goto reply;
 476                 }
 477                 talloc_free(tmp_ctx);
 478                 return ret;
 479         }
 480
 481         nt_status = gensec_set_credentials(gensec_security, server_credentials);
 482         if (!NT_STATUS_IS_OK(nt_status)) {
 483                 talloc_free(tmp_ctx);
 484                 return False;
 485         }
 486
 487         /* The kerberos PRIV packets include these addresses.  MIT
 488          * clients check that they are present */
 489         nt_status = gensec_set_peer_addr(gensec_security, peer_addr);
 490         if (!NT_STATUS_IS_OK(nt_status)) {
 491                 talloc_free(tmp_ctx);
 492                 return False;
 493         }
 494         nt_status = gensec_set_my_addr(gensec_security, my_addr);
 495         if (!NT_STATUS_IS_OK(nt_status)) {
 496                 talloc_free(tmp_ctx);
 497                 return False;
 498         }
 499
 500         /* We want the GENSEC wrap calls to generate PRIV tokens */
 501         gensec_want_feature(gensec_security, GENSEC_FEATURE_SEAL);
 502
 503         nt_status = gensec_start_mech_by_name(gensec_security, "krb5");
 504         if (!NT_STATUS_IS_OK(nt_status)) {
 505                 talloc_free(tmp_ctx);
 506                 return False;
 507         }
 508
 509         /* Accept the AP-REQ and generate teh AP-REP we need for the reply */
 510         nt_status = gensec_update(gensec_security, tmp_ctx, ap_req, &ap_rep);
 511         if (!NT_STATUS_IS_OK(nt_status) && !NT_STATUS_EQUAL(nt_status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
 512
 513                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 514                                                        KRB5_KPASSWD_HARDERROR,
 515                                                        talloc_asprintf(mem_ctx,
 516                                                                        "gensec_update failed: %s",
 517                                                                        nt_errstr(nt_status)),
 518                                                        &krb_priv_rep);
 519                 ap_rep.length = 0;
 520                 if (ret) {
 521                         goto reply;
 522                 }
 523                 talloc_free(tmp_ctx);
 524                 return ret;
 525         }
 526
 527         /* Extract the data from the KRB-PRIV half of the message */
 528         nt_status = gensec_unwrap(gensec_security, tmp_ctx, &krb_priv_req, &kpasswd_req);
 529         if (!NT_STATUS_IS_OK(nt_status)) {
 530                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 531                                                        KRB5_KPASSWD_HARDERROR,
 532                                                        talloc_asprintf(mem_ctx,
 533                                                                        "gensec_unwrap failed: %s",
 534                                                                        nt_errstr(nt_status)),
 535                                                        &krb_priv_rep);
 536                 ap_rep.length = 0;
 537                 if (ret) {
 538                         goto reply;
 539                 }
 540                 talloc_free(tmp_ctx);
 541                 return ret;
 542         }
 543
 544         /* Figure out something to do with it (probably changing a password...) */
 545         ret = kpasswd_process_request(kdc, tmp_ctx,
 546                                       gensec_security,
 547                                       version,
 548                                       &kpasswd_req, &kpasswd_rep);
 549         if (!ret) {
 550                 /* Argh! */
 551                 return False;
 552         }
 553
 554         /* And wrap up the reply: This ensures that the error message
 555          * or success can be verified by the client */
 556         nt_status = gensec_wrap(gensec_security, tmp_ctx,
 557                                 &kpasswd_rep, &krb_priv_rep);
 558         if (!NT_STATUS_IS_OK(nt_status)) {
 559                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 560                                                        KRB5_KPASSWD_HARDERROR,
 561                                                        talloc_asprintf(mem_ctx,
 562                                                                        "gensec_wrap failed: %s",
 563                                                                        nt_errstr(nt_status)),
 564                                                        &krb_priv_rep);
 565                 ap_rep.length = 0;
 566                 if (ret) {
 567                         goto reply;
 568                 }
 569                 talloc_free(tmp_ctx);
 570                 return ret;
 571         }
 572
 573 reply:
 574         *reply = data_blob_talloc(mem_ctx, NULL, krb_priv_rep.length + ap_rep.length + header_len);
 575         if (!reply->data) {
 576                 return False;
 577         }
 578
 579         RSSVAL(reply->data, 0, reply->length);
 580         RSSVAL(reply->data, 2, 1); /* This is a version 1 reply, MS change/set or otherwise */
 581         RSSVAL(reply->data, 4, ap_rep.length);
 582         memcpy(reply->data + header_len,
 583                ap_rep.data,
 584                ap_rep.length);
 585         memcpy(reply->data + header_len + ap_rep.length,
 586                krb_priv_rep.data,
 587                krb_priv_rep.length);
 588
 589         talloc_free(tmp_ctx);
 590         return ret;
 591 }
 592