source4/ntp_signd/ntp_signd.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    NTP packet signing server
   5
   6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2005
   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 "smbd/service_task.h"
  26 #include "smbd/service.h"
  27 #include "smbd/service_stream.h"
  28 #include "smbd/process_model.h"
  29 #include "lib/stream/packet.h"
  30 #include "lib/tsocket/tsocket.h"
  31 #include "libcli/util/tstream.h"
  32 #include "librpc/gen_ndr/ndr_ntp_signd.h"
  33 #include "param/param.h"
  34 #include "dsdb/samdb/samdb.h"
  35 #include "auth/auth.h"
  36 #include "libcli/security/security.h"
  37 #include "libcli/ldap/ldap_ndr.h"
  38 #include <ldb.h>
  39 #include <ldb_errors.h>
  40 #include "system/network.h"
  41 #include "system/passwd.h"
  42
  43 #include "lib/crypto/gnutls_helpers.h"
  44 #include <gnutls/gnutls.h>
  45 #include <gnutls/crypto.h>
  46
  47 NTSTATUS server_service_ntp_signd_init(TALLOC_CTX *);
  48
  49 /*
  50   top level context structure for the ntp_signd server
  51 */
  52 struct ntp_signd_server {
  53         struct task_server *task;
  54         struct ldb_context *samdb;
  55 };
  56
  57 /*
  58   state of an open connection
  59 */
  60 struct ntp_signd_connection {
  61         /* stream connection we belong to */
  62         struct stream_connection *conn;
  63
  64         /* the ntp_signd_server the connection belongs to */
  65         struct ntp_signd_server *ntp_signd;
  66
  67         struct tstream_context *tstream;
  68
  69         struct tevent_queue *send_queue;
  70 };
  71
  72 static void ntp_signd_terminate_connection(struct ntp_signd_connection *ntp_signd_conn, const char *reason)
  73 {
  74         stream_terminate_connection(ntp_signd_conn->conn, reason);
  75 }
  76
  77 static NTSTATUS signing_failure(struct ntp_signd_connection *ntp_signdconn,
  78                                 TALLOC_CTX *mem_ctx,
  79                                 DATA_BLOB *output,
  80                                 uint32_t packet_id)
  81 {
  82         struct signed_reply signed_reply;
  83         enum ndr_err_code ndr_err;
  84
  85         signed_reply.op = SIGNING_FAILURE;
  86         signed_reply.packet_id = packet_id;
  87         signed_reply.signed_packet = data_blob(NULL, 0);
  88
  89         ndr_err = ndr_push_struct_blob(output, mem_ctx, &signed_reply,
  90                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
  91
  92         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
  93                 DEBUG(1,("failed to push ntp error reply\n"));
  94                 return ndr_map_error2ntstatus(ndr_err);
  95         }
  96
  97         return NT_STATUS_OK;
  98 }
  99
 100 /*
 101   receive a full packet on a NTP_SIGND connection
 102 */
 103 static NTSTATUS ntp_signd_process(struct ntp_signd_connection *ntp_signd_conn,
 104                                   TALLOC_CTX *mem_ctx,
 105                                   DATA_BLOB *input,
 106                                   DATA_BLOB *output)
 107 {
 108         const struct dom_sid *domain_sid;
 109         struct dom_sid *sid;
 110         struct sign_request sign_request;
 111         struct signed_reply signed_reply;
 112         enum ndr_err_code ndr_err;
 113         struct ldb_result *res;
 114         const char *attrs[] = { "unicodePwd", "userAccountControl", "cn", NULL };
 115         gnutls_hash_hd_t hash_hnd = NULL;
 116         struct samr_Password *nt_hash;
 117         uint32_t user_account_control;
 118         struct dom_sid_buf buf;
 119         int ret;
 120
 121         ndr_err = ndr_pull_struct_blob_all(input, mem_ctx,
 122                                            &sign_request,
 123                                            (ndr_pull_flags_fn_t)ndr_pull_sign_request);
 124
 125         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 126                 DEBUG(1,("failed to parse ntp signing request\n"));
 127                 dump_data(1, input->data, input->length);
 128                 return ndr_map_error2ntstatus(ndr_err);
 129         }
 130
 131         /* We need to implement 'check signature' and 'request server
 132          * to sign' operations at some point */
 133         if (sign_request.op != SIGN_TO_CLIENT) {
 134                 return signing_failure(ntp_signd_conn,
 135                                        mem_ctx,
 136                                        output,
 137                                        sign_request.packet_id);
 138         }
 139
 140         /* We need to implement 'check signature' and 'request server
 141          * to sign' operations at some point */
 142         if (sign_request.version != NTP_SIGND_PROTOCOL_VERSION_0) {
 143                 return signing_failure(ntp_signd_conn,
 144                                        mem_ctx,
 145                                        output,
 146                                        sign_request.packet_id);
 147         }
 148
 149         domain_sid = samdb_domain_sid(ntp_signd_conn->ntp_signd->samdb);
 150         if (domain_sid == NULL) {
 151                 return signing_failure(ntp_signd_conn,
 152                                        mem_ctx,
 153                                        output,
 154                                        sign_request.packet_id);
 155         }
 156
 157         /* The top bit is a 'key selector' */
 158         sid = dom_sid_add_rid(mem_ctx, domain_sid,
 159                               sign_request.key_id & 0x7FFFFFFF);
 160         if (sid == NULL) {
 161                 talloc_free(mem_ctx);
 162                 return signing_failure(ntp_signd_conn,
 163                                        mem_ctx,
 164                                        output,
 165                                        sign_request.packet_id);
 166         }
 167
 168         ret = ldb_search(ntp_signd_conn->ntp_signd->samdb, mem_ctx,
 169                                  &res,
 170                                  ldb_get_default_basedn(ntp_signd_conn->ntp_signd->samdb),
 171                                  LDB_SCOPE_SUBTREE,
 172                                  attrs,
 173                                  "(&(objectSid=%s)(objectClass=user))",
 174                                  ldap_encode_ndr_dom_sid(mem_ctx, sid));
 175         if (ret != LDB_SUCCESS) {
 176                 DEBUG(2, ("Failed to search for SID %s in SAM for NTP signing: "
 177                           "%s\n",
 178                           dom_sid_str_buf(sid, &buf),
 179                           ldb_errstring(ntp_signd_conn->ntp_signd->samdb)));
 180                 return signing_failure(ntp_signd_conn,
 181                                        mem_ctx,
 182                                        output,
 183                                        sign_request.packet_id);
 184         }
 185
 186         if (res->count == 0) {
 187                 DEBUG(2, ("Failed to find SID %s in SAM for NTP signing\n",
 188                           dom_sid_str_buf(sid, &buf)));
 189                 return signing_failure(ntp_signd_conn,
 190                                        mem_ctx,
 191                                        output,
 192                                        sign_request.packet_id);
 193         } else if (res->count != 1) {
 194                 DEBUG(1, ("Found SID %s %u times in SAM for NTP signing\n",
 195                           dom_sid_str_buf(sid, &buf),
 196                           res->count));
 197                 return signing_failure(ntp_signd_conn,
 198                                        mem_ctx,
 199                                        output,
 200                                        sign_request.packet_id);
 201         }
 202
 203         user_account_control = ldb_msg_find_attr_as_uint(res->msgs[0],
 204                                                          "userAccountControl",
 205                                                          0);
 206
 207         if (user_account_control & UF_ACCOUNTDISABLE) {
 208                 DEBUG(1, ("Account %s for SID [%s] is disabled\n",
 209                           ldb_dn_get_linearized(res->msgs[0]->dn),
 210                           dom_sid_str_buf(sid, &buf)));
 211                 return NT_STATUS_ACCESS_DENIED;
 212         }
 213
 214         if (!(user_account_control & (UF_INTERDOMAIN_TRUST_ACCOUNT|UF_SERVER_TRUST_ACCOUNT|UF_WORKSTATION_TRUST_ACCOUNT))) {
 215                 DEBUG(1, ("Account %s for SID [%s] is not a trust account\n",
 216                           ldb_dn_get_linearized(res->msgs[0]->dn),
 217                           dom_sid_str_buf(sid, &buf)));
 218                 return NT_STATUS_ACCESS_DENIED;
 219         }
 220
 221         nt_hash = samdb_result_hash(mem_ctx, res->msgs[0], "unicodePwd");
 222         if (!nt_hash) {
 223                 DEBUG(1, ("No unicodePwd found on record of SID %s "
 224                           "for NTP signing\n",
 225                           dom_sid_str_buf(sid, &buf)));
 226                 return signing_failure(ntp_signd_conn,
 227                                        mem_ctx,
 228                                        output,
 229                                        sign_request.packet_id);
 230         }
 231
 232         /* Generate the reply packet */
 233         signed_reply.packet_id = sign_request.packet_id;
 234         signed_reply.op = SIGNING_SUCCESS;
 235         signed_reply.signed_packet = data_blob_talloc(mem_ctx,
 236                                                       NULL,
 237                                                       sign_request.packet_to_sign.length + 20);
 238
 239         if (!signed_reply.signed_packet.data) {
 240                 return signing_failure(ntp_signd_conn,
 241                                        mem_ctx,
 242                                        output,
 243                                        sign_request.packet_id);
 244         }
 245
 246         memcpy(signed_reply.signed_packet.data, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 247         SIVAL(signed_reply.signed_packet.data, sign_request.packet_to_sign.length, sign_request.key_id);
 248
 249         /* Sign the NTP response with the unicodePwd */
 250         ret = gnutls_hash_init(&hash_hnd, GNUTLS_DIG_MD5);
 251         if (ret < 0) {
 252                 return gnutls_error_to_ntstatus(ret, NT_STATUS_HASH_NOT_SUPPORTED);
 253         }
 254
 255         ret = gnutls_hash(hash_hnd,
 256                           nt_hash->hash,
 257                           sizeof(nt_hash->hash));
 258         if (ret < 0) {
 259                 gnutls_hash_deinit(hash_hnd, NULL);
 260                 return gnutls_error_to_ntstatus(ret, NT_STATUS_HASH_NOT_SUPPORTED);
 261         }
 262         ret = gnutls_hash(hash_hnd,
 263                           sign_request.packet_to_sign.data,
 264                           sign_request.packet_to_sign.length);
 265         if (ret < 0) {
 266                 gnutls_hash_deinit(hash_hnd, NULL);
 267                 return gnutls_error_to_ntstatus(ret, NT_STATUS_HASH_NOT_SUPPORTED);
 268         }
 269
 270         gnutls_hash_deinit(hash_hnd,
 271                            signed_reply.signed_packet.data +
 272                            sign_request.packet_to_sign.length + 4);
 273
 274         /* Place it into the packet for the wire */
 275         ndr_err = ndr_push_struct_blob(output, mem_ctx, &signed_reply,
 276                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
 277
 278         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 279                 DEBUG(1,("failed to push ntp error reply\n"));
 280                 return ndr_map_error2ntstatus(ndr_err);
 281         }
 282
 283         return NT_STATUS_OK;
 284 }
 285
 286 /*
 287   called on a tcp recv
 288 */
 289 static void ntp_signd_recv(struct stream_connection *conn, uint16_t flags)
 290 {
 291         struct ntp_signd_connection *ntp_signd_conn = talloc_get_type(conn->private_data,
 292                                                         struct ntp_signd_connection);
 293         ntp_signd_terminate_connection(ntp_signd_conn,
 294                                        "ntp_signd_recv: called");
 295 }
 296
 297 /*
 298   called when we can write to a connection
 299 */
 300 static void ntp_signd_send(struct stream_connection *conn, uint16_t flags)
 301 {
 302         struct ntp_signd_connection *ntp_signd_conn = talloc_get_type(conn->private_data,
 303                                                         struct ntp_signd_connection);
 304         /* this should never be triggered! */
 305         ntp_signd_terminate_connection(ntp_signd_conn,
 306                                        "ntp_signd_send: called");
 307 }
 308
 309 struct ntp_signd_call {
 310         struct ntp_signd_connection *ntp_signd_conn;
 311         DATA_BLOB in;
 312         DATA_BLOB out;
 313         uint8_t out_hdr[4];
 314         struct iovec out_iov[2];
 315 };
 316
 317 static void ntp_signd_call_writev_done(struct tevent_req *subreq);
 318
 319 static void ntp_signd_call_loop(struct tevent_req *subreq)
 320 {
 321         struct ntp_signd_connection *ntp_signd_conn = tevent_req_callback_data(subreq,
 322                                       struct ntp_signd_connection);
 323         struct ntp_signd_call *call;
 324         NTSTATUS status;
 325
 326         call = talloc(ntp_signd_conn, struct ntp_signd_call);
 327         if (call == NULL) {
 328                 ntp_signd_terminate_connection(ntp_signd_conn,
 329                                 "ntp_signd_call_loop: "
 330                                 "no memory for ntp_signd_call");
 331                 return;
 332         }
 333         call->ntp_signd_conn = ntp_signd_conn;
 334
 335         status = tstream_read_pdu_blob_recv(subreq,
 336                                             call,
 337                                             &call->in);
 338         TALLOC_FREE(subreq);
 339         if (!NT_STATUS_IS_OK(status)) {
 340                 const char *reason;
 341
 342                 reason = talloc_asprintf(call, "ntp_signd_call_loop: "
 343                                          "tstream_read_pdu_blob_recv() - %s",
 344                                          nt_errstr(status));
 345                 if (reason == NULL) {
 346                         reason = nt_errstr(status);
 347                 }
 348
 349                 ntp_signd_terminate_connection(ntp_signd_conn, reason);
 350                 return;
 351         }
 352
 353         DEBUG(10,("Received NTP TCP packet of length %lu from %s\n",
 354                  (long) call->in.length,
 355                  tsocket_address_string(ntp_signd_conn->conn->remote_address, call)));
 356
 357         /* skip length header */
 358         call->in.data +=4;
 359         call->in.length -= 4;
 360
 361         status = ntp_signd_process(ntp_signd_conn,
 362                                      call,
 363                                      &call->in,
 364                                      &call->out);
 365         if (! NT_STATUS_IS_OK(status)) {
 366                 const char *reason;
 367
 368                 reason = talloc_asprintf(call, "ntp_signd_process failed: %s",
 369                                          nt_errstr(status));
 370                 if (reason == NULL) {
 371                         reason = nt_errstr(status);
 372                 }
 373
 374                 ntp_signd_terminate_connection(ntp_signd_conn, reason);
 375                 return;
 376         }
 377
 378         /* First add the length of the out buffer */
 379         RSIVAL(call->out_hdr, 0, call->out.length);
 380         call->out_iov[0].iov_base = (char *) call->out_hdr;
 381         call->out_iov[0].iov_len = 4;
 382
 383         call->out_iov[1].iov_base = (char *) call->out.data;
 384         call->out_iov[1].iov_len = call->out.length;
 385
 386         subreq = tstream_writev_queue_send(call,
 387                                            ntp_signd_conn->conn->event.ctx,
 388                                            ntp_signd_conn->tstream,
 389                                            ntp_signd_conn->send_queue,
 390                                            call->out_iov, 2);
 391         if (subreq == NULL) {
 392                 ntp_signd_terminate_connection(ntp_signd_conn, "ntp_signd_call_loop: "
 393                                 "no memory for tstream_writev_queue_send");
 394                 return;
 395         }
 396
 397         tevent_req_set_callback(subreq, ntp_signd_call_writev_done, call);
 398
 399         /*
 400          * The NTP tcp pdu's has the length as 4 byte (initial_read_size),
 401          * packet_full_request_u32 provides the pdu length then.
 402          */
 403         subreq = tstream_read_pdu_blob_send(ntp_signd_conn,
 404                                             ntp_signd_conn->conn->event.ctx,
 405                                             ntp_signd_conn->tstream,
 406                                             4, /* initial_read_size */
 407                                             packet_full_request_u32,
 408                                             ntp_signd_conn);
 409         if (subreq == NULL) {
 410                 ntp_signd_terminate_connection(ntp_signd_conn, "ntp_signd_call_loop: "
 411                                 "no memory for tstream_read_pdu_blob_send");
 412                 return;
 413         }
 414         tevent_req_set_callback(subreq, ntp_signd_call_loop, ntp_signd_conn);
 415 }
 416
 417 static void ntp_signd_call_writev_done(struct tevent_req *subreq)
 418 {
 419         struct ntp_signd_call *call = tevent_req_callback_data(subreq,
 420                         struct ntp_signd_call);
 421         int sys_errno;
 422         int rc;
 423
 424         rc = tstream_writev_queue_recv(subreq, &sys_errno);
 425         TALLOC_FREE(subreq);
 426         if (rc == -1) {
 427                 const char *reason;
 428
 429                 reason = talloc_asprintf(call, "ntp_signd_call_writev_done: "
 430                                          "tstream_writev_queue_recv() - %d:%s",
 431                                          sys_errno, strerror(sys_errno));
 432                 if (!reason) {
 433                         reason = "ntp_signd_call_writev_done: "
 434                                  "tstream_writev_queue_recv() failed";
 435                 }
 436
 437                 ntp_signd_terminate_connection(call->ntp_signd_conn, reason);
 438                 return;
 439         }
 440
 441         /* We don't care about errors */
 442
 443         talloc_free(call);
 444 }
 445
 446 /*
 447   called when we get a new connection
 448 */
 449 static void ntp_signd_accept(struct stream_connection *conn)
 450 {
 451         struct ntp_signd_server *ntp_signd = talloc_get_type(conn->private_data,
 452                                                 struct ntp_signd_server);
 453         struct ntp_signd_connection *ntp_signd_conn;
 454         struct tevent_req *subreq;
 455         int rc;
 456
 457         ntp_signd_conn = talloc_zero(conn, struct ntp_signd_connection);
 458         if (ntp_signd_conn == NULL) {
 459                 stream_terminate_connection(conn,
 460                                 "ntp_signd_accept: out of memory");
 461                 return;
 462         }
 463
 464         ntp_signd_conn->send_queue = tevent_queue_create(conn,
 465                         "ntp_signd_accept");
 466         if (ntp_signd_conn->send_queue == NULL) {
 467                 stream_terminate_connection(conn,
 468                                 "ntp_signd_accept: out of memory");
 469                 return;
 470         }
 471
 472         TALLOC_FREE(conn->event.fde);
 473
 474         rc = tstream_bsd_existing_socket(ntp_signd_conn,
 475                         socket_get_fd(conn->socket),
 476                         &ntp_signd_conn->tstream);
 477         if (rc < 0) {
 478                 stream_terminate_connection(conn,
 479                                 "ntp_signd_accept: out of memory");
 480                 return;
 481         }
 482
 483         ntp_signd_conn->conn = conn;
 484         ntp_signd_conn->ntp_signd = ntp_signd;
 485         conn->private_data = ntp_signd_conn;
 486
 487         /*
 488          * The NTP tcp pdu's has the length as 4 byte (initial_read_size),
 489          * packet_full_request_u32 provides the pdu length then.
 490          */
 491         subreq = tstream_read_pdu_blob_send(ntp_signd_conn,
 492                                             ntp_signd_conn->conn->event.ctx,
 493                                             ntp_signd_conn->tstream,
 494                                             4, /* initial_read_size */
 495                                             packet_full_request_u32,
 496                                             ntp_signd_conn);
 497         if (subreq == NULL) {
 498                 ntp_signd_terminate_connection(ntp_signd_conn,
 499                                 "ntp_signd_accept: "
 500                                 "no memory for tstream_read_pdu_blob_send");
 501                 return;
 502         }
 503         tevent_req_set_callback(subreq, ntp_signd_call_loop, ntp_signd_conn);
 504 }
 505
 506 static const struct stream_server_ops ntp_signd_stream_ops = {
 507         .name                   = "ntp_signd",
 508         .accept_connection      = ntp_signd_accept,
 509         .recv_handler           = ntp_signd_recv,
 510         .send_handler           = ntp_signd_send
 511 };
 512
 513 /*
 514   startup the ntp_signd task
 515 */
 516 static NTSTATUS ntp_signd_task_init(struct task_server *task)
 517 {
 518         struct ntp_signd_server *ntp_signd;
 519         NTSTATUS status;
 520
 521         const char *address;
 522
 523         if (!directory_create_or_exist_strict(lpcfg_ntp_signd_socket_directory(task->lp_ctx), geteuid(), 0750)) {
 524                 char *error = talloc_asprintf(task, "Cannot create NTP signd pipe directory: %s",
 525                                               lpcfg_ntp_signd_socket_directory(task->lp_ctx));
 526                 task_server_terminate(task,
 527                                       error, true);
 528                 return NT_STATUS_UNSUCCESSFUL;
 529         }
 530
 531         task_server_set_title(task, "task[ntp_signd]");
 532
 533         ntp_signd = talloc(task, struct ntp_signd_server);
 534         if (ntp_signd == NULL) {
 535                 task_server_terminate(task, "ntp_signd: out of memory", true);
 536                 return NT_STATUS_NO_MEMORY;
 537         }
 538
 539         ntp_signd->task = task;
 540
 541         /* Must be system to get at the password hashes */
 542         ntp_signd->samdb = samdb_connect(ntp_signd,
 543                                          task->event_ctx,
 544                                          task->lp_ctx,
 545                                          system_session(task->lp_ctx),
 546                                          NULL,
 547                                          0);
 548         if (ntp_signd->samdb == NULL) {
 549                 task_server_terminate(task, "ntp_signd failed to open samdb", true);
 550                 return NT_STATUS_UNSUCCESSFUL;
 551         }
 552
 553         address = talloc_asprintf(ntp_signd, "%s/socket", lpcfg_ntp_signd_socket_directory(task->lp_ctx));
 554         if (address == NULL) {
 555                 task_server_terminate(
 556                     task, "ntp_signd out of memory in talloc_asprintf()", true);
 557                 return NT_STATUS_NO_MEMORY;
 558         }
 559
 560         status = stream_setup_socket(ntp_signd->task,
 561                                      ntp_signd->task->event_ctx,
 562                                      ntp_signd->task->lp_ctx,
 563                                      task->model_ops,
 564                                      &ntp_signd_stream_ops,
 565                                      "unix", address, NULL,
 566                                      lpcfg_socket_options(ntp_signd->task->lp_ctx),
 567                                      ntp_signd,
 568                                      ntp_signd->task->process_context);
 569         if (!NT_STATUS_IS_OK(status)) {
 570                 DEBUG(0,("Failed to bind to %s - %s\n",
 571                          address, nt_errstr(status)));
 572                 return status;
 573         }
 574
 575         return NT_STATUS_OK;
 576
 577 }
 578
 579
 580 /* called at smbd startup - register ourselves as a server service */
 581 NTSTATUS server_service_ntp_signd_init(TALLOC_CTX *ctx)
 582 {
 583         static const struct service_details details = {
 584                 .inhibit_fork_on_accept = true,
 585                 .inhibit_pre_fork = true,
 586                 .task_init = ntp_signd_task_init,
 587                 .post_fork = NULL
 588         };
 589         return register_server_service(ctx, "ntp_signd", &details);
 590 }