source4/kdc/kdc-heimdal.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    KDC Server startup
   5
   6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2005-2008
   7    Copyright (C) Andrew Tridgell        2005
   8    Copyright (C) Stefan Metzmacher      2005
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  22 */
  23
  24 #include "includes.h"
  25 #include "samba/process_model.h"
  26 #include "lib/tsocket/tsocket.h"
  27 #include "lib/messaging/irpc.h"
  28 #include "librpc/gen_ndr/ndr_irpc.h"
  29 #include "librpc/gen_ndr/ndr_krb5pac.h"
  30 #include "lib/socket/netif.h"
  31 #include "param/param.h"
  32 #include "kdc/kdc-server.h"
  33 #include "kdc/kdc-proxy.h"
  34 #include "kdc/kdc-glue.h"
  35 #include "kdc/pac-glue.h"
  36 #include "kdc/kpasswd-service.h"
  37 #include "dsdb/samdb/samdb.h"
  38 #include "auth/session.h"
  39 #include "libds/common/roles.h"
  40 #include <kdc.h>
  41 #include <hdb.h>
  42
  43 #undef DBGC_CLASS
  44 #define DBGC_CLASS DBGC_KERBEROS
  45
  46 NTSTATUS server_service_kdc_init(TALLOC_CTX *);
  47
  48 extern struct krb5plugin_kdc_ftable kdc_plugin_table;
  49
  50 /**
  51    Wrapper for krb5_kdc_process_krb5_request, converting to/from Samba
  52    calling conventions
  53 */
  54
  55 static kdc_code kdc_process(struct kdc_server *kdc,
  56                             TALLOC_CTX *mem_ctx,
  57                             DATA_BLOB *input,
  58                             DATA_BLOB *reply,
  59                             struct tsocket_address *peer_addr,
  60                             struct tsocket_address *my_addr,
  61                             int datagram_reply)
  62 {
  63         int ret;
  64         char *pa;
  65         struct sockaddr_storage ss;
  66         krb5_data k5_reply;
  67         krb5_kdc_configuration *kdc_config = kdc->private_data;
  68
  69         krb5_data_zero(&k5_reply);
  70
  71         krb5_kdc_update_time(NULL);
  72
  73         ret = tsocket_address_bsd_sockaddr(peer_addr, (struct sockaddr *) &ss,
  74                                 sizeof(struct sockaddr_storage));
  75         if (ret < 0) {
  76                 return KDC_ERROR;
  77         }
  78         pa = tsocket_address_string(peer_addr, mem_ctx);
  79         if (pa == NULL) {
  80                 return KDC_ERROR;
  81         }
  82
  83         DBG_DEBUG("Received KDC packet of length %zu from %s\n",
  84                   input->length, pa);
  85
  86         ret = krb5_kdc_process_krb5_request(kdc->smb_krb5_context->krb5_context,
  87                                             kdc_config,
  88                                             input->data, input->length,
  89                                             &k5_reply,
  90                                             pa,
  91                                             (struct sockaddr *) &ss,
  92                                             datagram_reply);
  93         if (ret == -1) {
  94                 *reply = data_blob(NULL, 0);
  95                 return KDC_ERROR;
  96         }
  97
  98         if (ret == HDB_ERR_NOT_FOUND_HERE) {
  99                 *reply = data_blob(NULL, 0);
 100                 return KDC_PROXY_REQUEST;
 101         }
 102
 103         if (k5_reply.length) {
 104                 *reply = data_blob_talloc(mem_ctx, k5_reply.data, k5_reply.length);
 105                 krb5_data_free(&k5_reply);
 106         } else {
 107                 *reply = data_blob(NULL, 0);
 108         }
 109         return KDC_OK;
 110 }
 111
 112 /*
 113   setup our listening sockets on the configured network interfaces
 114 */
 115 static NTSTATUS kdc_startup_interfaces(struct kdc_server *kdc,
 116                                        struct loadparm_context *lp_ctx,
 117                                        struct interface *ifaces,
 118                                        const struct model_ops *model_ops)
 119 {
 120         int num_interfaces;
 121         TALLOC_CTX *tmp_ctx = talloc_new(kdc);
 122         NTSTATUS status;
 123         int i;
 124         uint16_t kdc_port = lpcfg_krb5_port(lp_ctx);
 125         uint16_t kpasswd_port = lpcfg_kpasswd_port(lp_ctx);
 126         bool done_wildcard = false;
 127
 128         num_interfaces = iface_list_count(ifaces);
 129
 130         /* if we are allowing incoming packets from any address, then
 131            we need to bind to the wildcard address */
 132         if (!lpcfg_bind_interfaces_only(lp_ctx)) {
 133                 size_t num_binds = 0;
 134                 char **wcard = iface_list_wildcard(kdc);
 135                 NT_STATUS_HAVE_NO_MEMORY(wcard);
 136                 for (i=0; wcard[i]; i++) {
 137                         if (kdc_port) {
 138                                 status = kdc_add_socket(kdc, model_ops,
 139                                                         "kdc", wcard[i], kdc_port,
 140                                                         kdc_process, false);
 141                                 if (NT_STATUS_IS_OK(status)) {
 142                                         num_binds++;
 143                                 }
 144                         }
 145
 146                         if (kpasswd_port) {
 147                                 status = kdc_add_socket(kdc, model_ops,
 148                                                         "kpasswd", wcard[i], kpasswd_port,
 149                                                         kpasswd_process, false);
 150                                 if (NT_STATUS_IS_OK(status)) {
 151                                         num_binds++;
 152                                 }
 153                         }
 154                 }
 155                 talloc_free(wcard);
 156                 if (num_binds == 0) {
 157                         return NT_STATUS_INVALID_PARAMETER_MIX;
 158                 }
 159                 done_wildcard = true;
 160         }
 161
 162         for (i=0; i<num_interfaces; i++) {
 163                 const char *address = talloc_strdup(tmp_ctx, iface_list_n_ip(ifaces, i));
 164
 165                 if (kdc_port) {
 166                         status = kdc_add_socket(kdc, model_ops,
 167                                                 "kdc", address, kdc_port,
 168                                                 kdc_process, done_wildcard);
 169                         NT_STATUS_NOT_OK_RETURN(status);
 170                 }
 171
 172                 if (kpasswd_port) {
 173                         status = kdc_add_socket(kdc, model_ops,
 174                                                 "kpasswd", address, kpasswd_port,
 175                                                 kpasswd_process, done_wildcard);
 176                         NT_STATUS_NOT_OK_RETURN(status);
 177                 }
 178         }
 179
 180         talloc_free(tmp_ctx);
 181
 182         return NT_STATUS_OK;
 183 }
 184
 185 static NTSTATUS kdc_check_generic_kerberos(struct irpc_message *msg,
 186                                  struct kdc_check_generic_kerberos *r)
 187 {
 188         struct PAC_Validate pac_validate;
 189         DATA_BLOB srv_sig;
 190         struct PAC_SIGNATURE_DATA kdc_sig;
 191         struct kdc_server *kdc = talloc_get_type(msg->private_data, struct kdc_server);
 192         krb5_kdc_configuration *kdc_config =
 193                 (krb5_kdc_configuration *)kdc->private_data;
 194         enum ndr_err_code ndr_err;
 195         int ret;
 196         hdb_entry ent;
 197         krb5_principal principal;
 198
 199
 200         /* There is no reply to this request */
 201         r->out.generic_reply = data_blob(NULL, 0);
 202
 203         ndr_err = ndr_pull_struct_blob(&r->in.generic_request, msg, &pac_validate,
 204                                        (ndr_pull_flags_fn_t)ndr_pull_PAC_Validate);
 205         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 206                 return NT_STATUS_INVALID_PARAMETER;
 207         }
 208
 209         if (pac_validate.MessageType != NETLOGON_GENERIC_KRB5_PAC_VALIDATE) {
 210                 /* We don't implement any other message types - such as certificate validation - yet */
 211                 return NT_STATUS_INVALID_PARAMETER;
 212         }
 213
 214         if (pac_validate.ChecksumAndSignature.length != (pac_validate.ChecksumLength + pac_validate.SignatureLength)
 215             || pac_validate.ChecksumAndSignature.length < pac_validate.ChecksumLength
 216             || pac_validate.ChecksumAndSignature.length < pac_validate.SignatureLength ) {
 217                 return NT_STATUS_INVALID_PARAMETER;
 218         }
 219
 220         srv_sig = data_blob_const(pac_validate.ChecksumAndSignature.data,
 221                                   pac_validate.ChecksumLength);
 222
 223         ret = krb5_make_principal(kdc->smb_krb5_context->krb5_context, &principal,
 224                                   lpcfg_realm(kdc->task->lp_ctx),
 225                                   "krbtgt", lpcfg_realm(kdc->task->lp_ctx),
 226                                   NULL);
 227
 228         if (ret != 0) {
 229                 return NT_STATUS_NO_MEMORY;
 230         }
 231
 232         ret = kdc_config->db[0]->hdb_fetch_kvno(kdc->smb_krb5_context->krb5_context,
 233                                                  kdc_config->db[0],
 234                                                  principal,
 235                                                  HDB_F_GET_KRBTGT | HDB_F_DECRYPT,
 236                                                  0,
 237                                                  &ent);
 238
 239         if (ret != 0) {
 240                 hdb_free_entry(kdc->smb_krb5_context->krb5_context, kdc_config->db[0], &ent);
 241                 krb5_free_principal(kdc->smb_krb5_context->krb5_context, principal);
 242
 243                 return NT_STATUS_LOGON_FAILURE;
 244         }
 245
 246         kdc_sig.type = pac_validate.SignatureType;
 247         kdc_sig.signature = data_blob_const(&pac_validate.ChecksumAndSignature.data[pac_validate.ChecksumLength],
 248                                             pac_validate.SignatureLength);
 249
 250         ret = kdc_check_pac(kdc->smb_krb5_context->krb5_context, srv_sig, &kdc_sig, &ent);
 251
 252         hdb_free_entry(kdc->smb_krb5_context->krb5_context, kdc_config->db[0], &ent);
 253         krb5_free_principal(kdc->smb_krb5_context->krb5_context, principal);
 254
 255         if (ret != 0) {
 256                 return NT_STATUS_LOGON_FAILURE;
 257         }
 258
 259         return NT_STATUS_OK;
 260 }
 261
 262
 263 /*
 264   startup the kdc task
 265 */
 266 static NTSTATUS kdc_task_init(struct task_server *task)
 267 {
 268         struct kdc_server *kdc;
 269         NTSTATUS status;
 270         struct interface *ifaces;
 271
 272         switch (lpcfg_server_role(task->lp_ctx)) {
 273         case ROLE_STANDALONE:
 274                 task_server_terminate(task, "kdc: no KDC required in standalone configuration", false);
 275                 return NT_STATUS_INVALID_DOMAIN_ROLE;
 276         case ROLE_DOMAIN_MEMBER:
 277                 task_server_terminate(task, "kdc: no KDC required in member server configuration", false);
 278                 return NT_STATUS_INVALID_DOMAIN_ROLE;
 279         case ROLE_DOMAIN_PDC:
 280         case ROLE_DOMAIN_BDC:
 281         case ROLE_IPA_DC:
 282                 task_server_terminate(
 283                     task, "Cannot start KDC as a 'classic Samba' DC", false);
 284                 return NT_STATUS_INVALID_DOMAIN_ROLE;
 285         case ROLE_ACTIVE_DIRECTORY_DC:
 286                 /* Yes, we want a KDC */
 287                 break;
 288         }
 289
 290         load_interface_list(task, task->lp_ctx, &ifaces);
 291
 292         if (iface_list_count(ifaces) == 0) {
 293                 task_server_terminate(task, "kdc: no network interfaces configured", false);
 294                 return NT_STATUS_UNSUCCESSFUL;
 295         }
 296
 297         task_server_set_title(task, "task[kdc]");
 298
 299         kdc = talloc_zero(task, struct kdc_server);
 300         if (kdc == NULL) {
 301                 task_server_terminate(task, "kdc: out of memory", true);
 302                 return NT_STATUS_NO_MEMORY;
 303         }
 304
 305         kdc->task = task;
 306         task->private_data = kdc;
 307
 308         /* start listening on the configured network interfaces */
 309         status = kdc_startup_interfaces(kdc, task->lp_ctx, ifaces,
 310                                         task->model_ops);
 311         if (!NT_STATUS_IS_OK(status)) {
 312                 task_server_terminate(task, "kdc failed to setup interfaces", true);
 313                 return status;
 314         }
 315
 316
 317         return NT_STATUS_OK;
 318 }
 319
 320 /*
 321   initialise the kdc task after a fork
 322 */
 323 static void kdc_post_fork(struct task_server *task, struct process_details *pd)
 324 {
 325         struct kdc_server *kdc;
 326         krb5_kdc_configuration *kdc_config = NULL;
 327         NTSTATUS status;
 328         krb5_error_code ret;
 329         int ldb_ret;
 330
 331         if (task == NULL) {
 332                 task_server_terminate(task, "kdc: Null task", true);
 333                 return;
 334         }
 335         if (task->private_data == NULL) {
 336                 task_server_terminate(task, "kdc: No kdc_server info", true);
 337                 return;
 338         }
 339         kdc = talloc_get_type_abort(task->private_data, struct kdc_server);
 340
 341         /* get a samdb connection */
 342         kdc->samdb = samdb_connect(kdc,
 343                                    kdc->task->event_ctx,
 344                                    kdc->task->lp_ctx,
 345                                    system_session(kdc->task->lp_ctx),
 346                                    NULL,
 347                                    0);
 348         if (!kdc->samdb) {
 349                 DBG_WARNING("kdc_task_init: unable to connect to samdb\n");
 350                 task_server_terminate(task, "kdc: krb5_init_context samdb connect failed", true);
 351                 return;
 352         }
 353
 354         ldb_ret = samdb_rodc(kdc->samdb, &kdc->am_rodc);
 355         if (ldb_ret != LDB_SUCCESS) {
 356                 DBG_WARNING("kdc_task_init: "
 357                             "Cannot determine if we are an RODC: %s\n",
 358                             ldb_errstring(kdc->samdb));
 359                 task_server_terminate(task, "kdc: krb5_init_context samdb RODC connect failed", true);
 360                 return;
 361         }
 362
 363         kdc->proxy_timeout = lpcfg_parm_int(kdc->task->lp_ctx, NULL, "kdc", "proxy timeout", 5);
 364
 365         initialize_krb5_error_table();
 366
 367         ret = smb_krb5_init_context(kdc, task->lp_ctx, &kdc->smb_krb5_context);
 368         if (ret) {
 369                 DBG_WARNING("kdc_task_init: krb5_init_context failed (%s)\n",
 370                             error_message(ret));
 371                 task_server_terminate(task, "kdc: krb5_init_context failed", true);
 372                 return;
 373         }
 374
 375         krb5_add_et_list(kdc->smb_krb5_context->krb5_context, initialize_hdb_error_table_r);
 376
 377         ret = krb5_kdc_get_config(kdc->smb_krb5_context->krb5_context,
 378                                   &kdc_config);
 379         if(ret) {
 380                 task_server_terminate(task, "kdc: failed to get KDC configuration", true);
 381                 return;
 382         }
 383
 384         kdc_config->logf = (krb5_log_facility *)kdc->smb_krb5_context->pvt_log_data;
 385         kdc_config->db = talloc(kdc, struct HDB *);
 386         if (!kdc_config->db) {
 387                 task_server_terminate(task, "kdc: out of memory", true);
 388                 return;
 389         }
 390         kdc_config->num_db = 1;
 391
 392         /*
 393          * Note with the CVE-2022-37966 patches,
 394          * see https://bugzilla.samba.org/show_bug.cgi?id=15219
 395          * and https://bugzilla.samba.org/show_bug.cgi?id=15237
 396          * we want to use the strongest keys for everything.
 397          *
 398          * Some of these don't have any real effect anymore,
 399          * but it is better to have them as true...
 400          */
 401         kdc_config->tgt_use_strongest_session_key = true;
 402         kdc_config->preauth_use_strongest_session_key = true;
 403         kdc_config->svc_use_strongest_session_key = true;
 404         kdc_config->use_strongest_server_key = true;
 405
 406         kdc_config->force_include_pa_etype_salt = true;
 407
 408         /*
 409          * For Samba CVE-2020-25719 Require PAC to be present
 410          * This instructs Heimdal to match AD behaviour,
 411          * as seen after Microsoft's CVE-2021-42287 when
 412          * PacRequestorEnforcement is set to 2.
 413          *
 414          * Samba BUG: https://bugzilla.samba.org/show_bug.cgi?id=14686
 415          * REF: https://support.microsoft.com/en-au/topic/kb5008380-authentication-updates-cve-2021-42287-9dafac11-e0d0-4cb8-959a-143bd0201041
 416          */
 417
 418         kdc_config->require_pac = true;
 419
 420         /*
 421          * By default we enable RFC6113/FAST support,
 422          * but we have an option to disable in order to
 423          * test against a KDC with FAST support.
 424          */
 425         kdc_config->enable_fast = lpcfg_kdc_enable_fast(task->lp_ctx);
 426
 427         {
 428                 static const char *dummy_string = "Microsoft";
 429
 430                 /*
 431                  * The FAST cookie is not cryptographically required,
 432                  * provided that the non-AD gss-preauth authentication
 433                  * method is removed (as this is the only multi-step
 434                  * authentication method).
 435                  *
 436                  * gss-preauth has been disabled both by not being
 437                  * configured and by being made dependent
 438                  * configuration for a "real" fast cookie.
 439                  *
 440                  * The hide_client_names feature in Heimdal is the
 441                  * only other state that is persisted in the cookie,
 442                  * and this does not need to be in the cookie for
 443                  * single-shot authentication protocols such as ENC-TS
 444                  * and ENC-CHAL, the standard password protocols in
 445                  * AD.
 446                  *
 447                  * Furthermore, the Heimdal KDC does not fail if the
 448                  * client does not supply a FAST cookie, showing that
 449                  * the presence of the cookie is not required.
 450                  */
 451                 kdc_config->enable_fast_cookie = false;
 452                 kdc_config->dummy_fast_cookie = smb_krb5_make_data(discard_const_p(char, dummy_string),
 453                                                                    strlen(dummy_string));
 454         }
 455
 456         /*
 457          * Match Windows and RFC6113 and Windows but break older
 458          * Heimdal clients.
 459          */
 460         kdc_config->enable_armored_pa_enc_timestamp = false;
 461
 462         /* Register hdb-samba4 hooks for use as a keytab */
 463
 464         kdc->base_ctx = talloc_zero(kdc, struct samba_kdc_base_context);
 465         if (!kdc->base_ctx) {
 466                 task_server_terminate(task, "kdc: out of memory", true);
 467                 return;
 468         }
 469
 470         kdc->base_ctx->ev_ctx = task->event_ctx;
 471         kdc->base_ctx->lp_ctx = task->lp_ctx;
 472         kdc->base_ctx->msg_ctx = task->msg_ctx;
 473
 474         status = hdb_samba4_create_kdc(kdc->base_ctx,
 475                                        kdc->smb_krb5_context->krb5_context,
 476                                        &kdc_config->db[0]);
 477         if (!NT_STATUS_IS_OK(status)) {
 478                 task_server_terminate(task, "kdc: hdb_samba4_create_kdc (setup KDC database) failed", true);
 479                 return;
 480         }
 481
 482         ret = krb5_plugin_register(kdc->smb_krb5_context->krb5_context,
 483                                    PLUGIN_TYPE_DATA, "hdb_samba4_interface",
 484                                    &hdb_samba4_interface);
 485         if(ret) {
 486                 task_server_terminate(task, "kdc: failed to register hdb plugin", true);
 487                 return;
 488         }
 489
 490         kdc->kpasswd_keytab_name = talloc_asprintf(kdc, "HDBGET:samba4:&%p", kdc->base_ctx);
 491         if (kdc->kpasswd_keytab_name == NULL) {
 492                 task_server_terminate(task,
 493                                       "kdc: Failed to set keytab name",
 494                                       true);
 495                 return;
 496         }
 497
 498         ret = krb5_kt_register(kdc->smb_krb5_context->krb5_context, &hdb_get_kt_ops);
 499         if(ret) {
 500                 task_server_terminate(task, "kdc: failed to register keytab plugin", true);
 501                 return;
 502         }
 503
 504         /* Register KDC hooks */
 505         ret = krb5_plugin_register(kdc->smb_krb5_context->krb5_context,
 506                                    PLUGIN_TYPE_DATA, "kdc",
 507                                    &kdc_plugin_table);
 508         if(ret) {
 509                 task_server_terminate(task, "kdc: failed to register kdc plugin", true);
 510                 return;
 511         }
 512
 513         ret = krb5_kdc_plugin_init(kdc->smb_krb5_context->krb5_context);
 514
 515         if(ret) {
 516                 task_server_terminate(task, "kdc: failed to init kdc plugin", true);
 517                 return;
 518         }
 519
 520         ret = krb5_kdc_pkinit_config(kdc->smb_krb5_context->krb5_context, kdc_config);
 521
 522         if(ret) {
 523                 task_server_terminate(task, "kdc: failed to init kdc pkinit subsystem", true);
 524                 return;
 525         }
 526         kdc->private_data = kdc_config;
 527
 528         status = IRPC_REGISTER(task->msg_ctx, irpc, KDC_CHECK_GENERIC_KERBEROS,
 529                                kdc_check_generic_kerberos, kdc);
 530         if (!NT_STATUS_IS_OK(status)) {
 531                 task_server_terminate(task, "kdc failed to setup monitoring", true);
 532                 return;
 533         }
 534
 535         irpc_add_name(task->msg_ctx, "kdc_server");
 536 }
 537
 538
 539 /* called at smbd startup - register ourselves as a server service */
 540 NTSTATUS server_service_kdc_init(TALLOC_CTX *ctx)
 541 {
 542         static const struct service_details details = {
 543                 .inhibit_fork_on_accept = true,
 544                 .inhibit_pre_fork = false,
 545                 .task_init = kdc_task_init,
 546                 .post_fork = kdc_post_fork
 547         };
 548         return register_server_service(ctx, "kdc", &details);
 549 }