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\n", dom_sid_string(mem_ctx, session_info->security_token->user_sid)));
 182
 183         /* User password change */
 184         status = samdb_set_password_sid(samdb, mem_ctx,
 185                                         session_info->security_token->user_sid,
 186                                         password, NULL, NULL,
 187                                         True, /* this is a user password change */
 188                                         True, /* run restriction tests */
 189                                         &reject_reason,
 190                                         &dominfo);
 191         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 192                                            status,
 193                                            reject_reason,
 194                                            dominfo,
 195                                            reply);
 196
 197 }
 198
 199 static BOOL kpasswd_process_request(struct kdc_server *kdc,
 200                                     TALLOC_CTX *mem_ctx,
 201                                     struct gensec_security *gensec_security,
 202                                     uint16_t version,
 203                                     DATA_BLOB *input,
 204                                     DATA_BLOB *reply)
 205 {
 206         NTSTATUS status;
 207         enum samr_RejectReason reject_reason;
 208         struct samr_DomInfo1 *dominfo;
 209         struct ldb_context *samdb;
 210         struct auth_session_info *session_info;
 211         struct ldb_message *msg = ldb_msg_new(gensec_security);
 212         krb5_context context = kdc->smb_krb5_context->krb5_context;
 213         int ret;
 214         if (!msg) {
 215                 return False;
 216         }
 217
 218         if (!NT_STATUS_IS_OK(gensec_session_info(gensec_security,
 219                                                  &session_info))) {
 220                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 221                                                 KRB5_KPASSWD_HARDERROR,
 222                                                 "gensec_session_info failed!",
 223                                                 reply);
 224         }
 225
 226         switch (version) {
 227         case KRB5_KPASSWD_VERS_CHANGEPW:
 228         {
 229                 char *password = talloc_strndup(mem_ctx, (const char *)input->data, input->length);
 230                 if (!password) {
 231                         return False;
 232                 }
 233                 return kpasswdd_change_password(kdc, mem_ctx, session_info,
 234                                                 password, reply);
 235                 break;
 236         }
 237         case KRB5_KPASSWD_VERS_SETPW:
 238         {
 239                 size_t len;
 240                 ChangePasswdDataMS chpw;
 241                 char *password;
 242                 krb5_principal principal;
 243                 char *set_password_on_princ;
 244                 struct ldb_dn *set_password_on_dn;
 245
 246                 samdb = samdb_connect(gensec_security, session_info);
 247
 248                 ret = decode_ChangePasswdDataMS(input->data, input->length,
 249                                                 &chpw, &len);
 250                 if (ret) {
 251                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 252                                                         KRB5_KPASSWD_MALFORMED,
 253                                                         "failed to decode password change structure",
 254                                                         reply);
 255                 }
 256
 257                 password = talloc_strndup(mem_ctx, chpw.newpasswd.data,
 258                                           chpw.newpasswd.length);
 259                 if (!password) {
 260                         free_ChangePasswdDataMS(&chpw);
 261                         return False;
 262                 }
 263                 if ((chpw.targname && !chpw.targrealm)
 264                     || (!chpw.targname && chpw.targrealm)) {
 265                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 266                                                         KRB5_KPASSWD_MALFORMED,
 267                                                         "Realm and principal must be both present, or neither present",
 268                                                         reply);
 269                 }
 270                 if (chpw.targname && chpw.targrealm) {
 271                         if (_krb5_principalname2krb5_principal(&principal, *chpw.targname,
 272                                                                *chpw.targrealm) != 0) {
 273                                 free_ChangePasswdDataMS(&chpw);
 274                                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 275                                                                 KRB5_KPASSWD_MALFORMED,
 276                                                                 "failed to extract principal to set",
 277                                                                 reply);
 278
 279                         }
 280                 } else {
 281                         free_ChangePasswdDataMS(&chpw);
 282                         return kpasswdd_change_password(kdc, mem_ctx, session_info,
 283                                                         password, reply);
 284                 }
 285                 free_ChangePasswdDataMS(&chpw);
 286
 287                 if (krb5_unparse_name(context, principal, &set_password_on_princ) != 0) {
 288                         krb5_free_principal(context, principal);
 289                         return kpasswdd_make_error_reply(kdc, mem_ctx,
 290                                                         KRB5_KPASSWD_MALFORMED,
 291                                                         "krb5_unparse_name failed!",
 292                                                         reply);
 293                 }
 294
 295                 krb5_free_principal(context, principal);
 296
 297                 status = crack_user_principal_name(samdb, mem_ctx,
 298                                                    set_password_on_princ,
 299                                                    &set_password_on_dn, NULL);
 300                 free(set_password_on_princ);
 301                 if (!NT_STATUS_IS_OK(status)) {
 302                         return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 303                                                            status,
 304                                                            reject_reason,
 305                                                            dominfo,
 306                                                            reply);
 307                 }
 308
 309                 /* Admin password set */
 310                 status = samdb_set_password(samdb, mem_ctx,
 311                                             set_password_on_dn, NULL,
 312                                             msg, password, NULL, NULL,
 313                                             False, /* this is not a user password change */
 314                                             True, /* run restriction tests */
 315                                             &reject_reason, &dominfo);
 316
 317                 return kpasswd_make_pwchange_reply(kdc, mem_ctx,
 318                                                    status,
 319                                                    reject_reason,
 320                                                    dominfo,
 321                                                    reply);
 322         }
 323         default:
 324                 return kpasswdd_make_error_reply(kdc, mem_ctx,
 325                                                 KRB5_KPASSWD_BAD_VERSION,
 326                                                 talloc_asprintf(mem_ctx,
 327                                                                 "Protocol version %u not supported",
 328                                                                 version),
 329                                                 reply);
 330         }
 331         return True;
 332 }
 333
 334 BOOL kpasswdd_process(struct kdc_server *kdc,
 335                       TALLOC_CTX *mem_ctx,
 336                       DATA_BLOB *input,
 337                       DATA_BLOB *reply,
 338                       const char *from,
 339                       int src_port)
 340 {
 341         BOOL ret;
 342         const uint16_t header_len = 6;
 343         uint16_t len;
 344         uint16_t ap_req_len;
 345         uint16_t krb_priv_len;
 346         uint16_t version;
 347         NTSTATUS nt_status;
 348         DATA_BLOB ap_req, krb_priv_req, krb_priv_rep, ap_rep;
 349         DATA_BLOB kpasswd_req, kpasswd_rep;
 350         struct cli_credentials *server_credentials;
 351         struct gensec_security *gensec_security;
 352         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 353
 354         if (!tmp_ctx) {
 355                 return False;
 356         }
 357
 358         if (input->length <= header_len) {
 359                 talloc_free(tmp_ctx);
 360                 return False;
 361         }
 362
 363         len = RSVAL(input->data, 0);
 364         if (input->length != len) {
 365                 talloc_free(tmp_ctx);
 366                 return False;
 367         }
 368
 369         version = RSVAL(input->data, 2);
 370         ap_req_len = RSVAL(input->data, 4);
 371         if ((ap_req_len >= len) || (ap_req_len + header_len) >= len) {
 372                 talloc_free(tmp_ctx);
 373                 return False;
 374         }
 375
 376         krb_priv_len = len - ap_req_len;
 377         ap_req = data_blob_const(&input->data[header_len], ap_req_len);
 378         krb_priv_req = data_blob_const(&input->data[header_len + ap_req_len], krb_priv_len);
 379
 380         nt_status = gensec_server_start(tmp_ctx, &gensec_security, kdc->task->event_ctx);
 381         if (!NT_STATUS_IS_OK(nt_status)) {
 382                 talloc_free(tmp_ctx);
 383                 return False;
 384         }
 385
 386         server_credentials
 387                 = cli_credentials_init(tmp_ctx);
 388         if (!server_credentials) {
 389                 DEBUG(1, ("Failed to init server credentials\n"));
 390                 return False;
 391         }
 392
 393         cli_credentials_set_conf(server_credentials);
 394         nt_status = cli_credentials_set_stored_principal(server_credentials, "kadmin/changepw");
 395         if (!NT_STATUS_IS_OK(nt_status)) {
 396                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 397                                                        KRB5_KPASSWD_HARDERROR,
 398                                                        talloc_asprintf(mem_ctx,
 399                                                                        "Failed to obtain server credentials for kadmin/changepw: %s\n",
 400                                                                        nt_errstr(nt_status)),
 401                                                        &krb_priv_rep);
 402                 ap_rep.length = 0;
 403                 if (ret) {
 404                         goto reply;
 405                 }
 406                 talloc_free(tmp_ctx);
 407                 return ret;
 408         }
 409
 410         gensec_set_credentials(gensec_security, server_credentials);
 411         gensec_want_feature(gensec_security, GENSEC_FEATURE_SEAL);
 412
 413         nt_status = gensec_start_mech_by_name(gensec_security, "krb5");
 414         if (!NT_STATUS_IS_OK(nt_status)) {
 415                 talloc_free(tmp_ctx);
 416                 return False;
 417         }
 418
 419         nt_status = gensec_update(gensec_security, tmp_ctx, ap_req, &ap_rep);
 420         if (!NT_STATUS_IS_OK(nt_status) && !NT_STATUS_EQUAL(nt_status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
 421
 422                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 423                                                        KRB5_KPASSWD_HARDERROR,
 424                                                        talloc_asprintf(mem_ctx,
 425                                                                        "gensec_update failed: %s",
 426                                                                        nt_errstr(nt_status)),
 427                                                        &krb_priv_rep);
 428                 ap_rep.length = 0;
 429                 if (ret) {
 430                         goto reply;
 431                 }
 432                 talloc_free(tmp_ctx);
 433                 return ret;
 434         }
 435
 436         nt_status = gensec_unwrap(gensec_security, tmp_ctx, &krb_priv_req, &kpasswd_req);
 437         if (!NT_STATUS_IS_OK(nt_status)) {
 438                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 439                                                        KRB5_KPASSWD_HARDERROR,
 440                                                        talloc_asprintf(mem_ctx,
 441                                                                        "gensec_unwrap failed: %s",
 442                                                                        nt_errstr(nt_status)),
 443                                                        &krb_priv_rep);
 444                 ap_rep.length = 0;
 445                 if (ret) {
 446                         goto reply;
 447                 }
 448                 talloc_free(tmp_ctx);
 449                 return ret;
 450         }
 451
 452         ret = kpasswd_process_request(kdc, tmp_ctx,
 453                                       gensec_security,
 454                                       version,
 455                                       &kpasswd_req, &kpasswd_rep);
 456         if (!ret) {
 457                 /* Argh! */
 458                 return False;
 459         }
 460
 461         nt_status = gensec_wrap(gensec_security, tmp_ctx,
 462                                 &kpasswd_rep, &krb_priv_rep);
 463         if (!NT_STATUS_IS_OK(nt_status)) {
 464                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx,
 465                                                        KRB5_KPASSWD_HARDERROR,
 466                                                        talloc_asprintf(mem_ctx,
 467                                                                        "gensec_wrap failed: %s",
 468                                                                        nt_errstr(nt_status)),
 469                                                        &krb_priv_rep);
 470                 ap_rep.length = 0;
 471                 if (ret) {
 472                         goto reply;
 473                 }
 474                 talloc_free(tmp_ctx);
 475                 return ret;
 476         }
 477
 478 reply:
 479         *reply = data_blob_talloc(mem_ctx, NULL, krb_priv_rep.length + ap_rep.length + header_len);
 480         if (!reply->data) {
 481                 return False;
 482         }
 483
 484         RSSVAL(reply->data, 0, reply->length);
 485         RSSVAL(reply->data, 2, 1); /* This is a version 1 reply, MS change/set or otherwise */
 486         RSSVAL(reply->data, 4, ap_rep.length);
 487         memcpy(reply->data + header_len,
 488                ap_rep.data,
 489                ap_rep.length);
 490         memcpy(reply->data + header_len + ap_rep.length,
 491                krb_priv_rep.data,
 492                krb_priv_rep.length);
 493
 494         talloc_free(tmp_ctx);
 495         return ret;
 496 }
 497