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 "../lib/crypto/md5.h"
  41 #include "system/network.h"
  42 #include "system/passwd.h"
  43
  44 NTSTATUS server_service_ntp_signd_init(TALLOC_CTX *);
  45
  46 /*
  47   top level context structure for the ntp_signd server
  48 */
  49 struct ntp_signd_server {
  50         struct task_server *task;
  51         struct ldb_context *samdb;
  52 };
  53
  54 /*
  55   state of an open connection
  56 */
  57 struct ntp_signd_connection {
  58         /* stream connection we belong to */
  59         struct stream_connection *conn;
  60
  61         /* the ntp_signd_server the connection belongs to */
  62         struct ntp_signd_server *ntp_signd;
  63
  64         struct tstream_context *tstream;
  65
  66         struct tevent_queue *send_queue;
  67 };
  68
  69 static void ntp_signd_terminate_connection(struct ntp_signd_connection *ntp_signd_conn, const char *reason)
  70 {
  71         stream_terminate_connection(ntp_signd_conn->conn, reason);
  72 }
  73
  74 static NTSTATUS signing_failure(struct ntp_signd_connection *ntp_signdconn,
  75                                 TALLOC_CTX *mem_ctx,
  76                                 DATA_BLOB *output,
  77                                 uint32_t packet_id)
  78 {
  79         struct signed_reply signed_reply;
  80         enum ndr_err_code ndr_err;
  81
  82         signed_reply.op = SIGNING_FAILURE;
  83         signed_reply.packet_id = packet_id;
  84         signed_reply.signed_packet = data_blob(NULL, 0);
  85
  86         ndr_err = ndr_push_struct_blob(output, mem_ctx, &signed_reply,
  87                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
  88
  89         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
  90                 DEBUG(1,("failed to push ntp error reply\n"));
  91                 return ndr_map_error2ntstatus(ndr_err);
  92         }
  93
  94         return NT_STATUS_OK;
  95 }
  96
  97 /*
  98   receive a full packet on a NTP_SIGND connection
  99 */
 100 static NTSTATUS ntp_signd_process(struct ntp_signd_connection *ntp_signd_conn,
 101                                   TALLOC_CTX *mem_ctx,
 102                                   DATA_BLOB *input,
 103                                   DATA_BLOB *output)
 104 {
 105         const struct dom_sid *domain_sid;
 106         struct dom_sid *sid;
 107         struct sign_request sign_request;
 108         struct signed_reply signed_reply;
 109         enum ndr_err_code ndr_err;
 110         struct ldb_result *res;
 111         const char *attrs[] = { "unicodePwd", "userAccountControl", "cn", NULL };
 112         MD5_CTX ctx;
 113         struct samr_Password *nt_hash;
 114         uint32_t user_account_control;
 115         struct dom_sid_buf buf;
 116         int ret;
 117
 118         ndr_err = ndr_pull_struct_blob_all(input, mem_ctx,
 119                                            &sign_request,
 120                                            (ndr_pull_flags_fn_t)ndr_pull_sign_request);
 121
 122         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 123                 DEBUG(1,("failed to parse ntp signing request\n"));
 124                 dump_data(1, input->data, input->length);
 125                 return ndr_map_error2ntstatus(ndr_err);
 126         }
 127
 128         /* We need to implement 'check signature' and 'request server
 129          * to sign' operations at some point */
 130         if (sign_request.op != SIGN_TO_CLIENT) {
 131                 return signing_failure(ntp_signd_conn,
 132                                        mem_ctx,
 133                                        output,
 134                                        sign_request.packet_id);
 135         }
 136
 137         /* We need to implement 'check signature' and 'request server
 138          * to sign' operations at some point */
 139         if (sign_request.version != NTP_SIGND_PROTOCOL_VERSION_0) {
 140                 return signing_failure(ntp_signd_conn,
 141                                        mem_ctx,
 142                                        output,
 143                                        sign_request.packet_id);
 144         }
 145
 146         domain_sid = samdb_domain_sid(ntp_signd_conn->ntp_signd->samdb);
 147         if (domain_sid == NULL) {
 148                 return signing_failure(ntp_signd_conn,
 149                                        mem_ctx,
 150                                        output,
 151                                        sign_request.packet_id);
 152         }
 153
 154         /* The top bit is a 'key selector' */
 155         sid = dom_sid_add_rid(mem_ctx, domain_sid,
 156                               sign_request.key_id & 0x7FFFFFFF);
 157         if (sid == NULL) {
 158                 talloc_free(mem_ctx);
 159                 return signing_failure(ntp_signd_conn,
 160                                        mem_ctx,
 161                                        output,
 162                                        sign_request.packet_id);
 163         }
 164
 165         ret = ldb_search(ntp_signd_conn->ntp_signd->samdb, mem_ctx,
 166                                  &res,
 167                                  ldb_get_default_basedn(ntp_signd_conn->ntp_signd->samdb),
 168                                  LDB_SCOPE_SUBTREE,
 169                                  attrs,
 170                                  "(&(objectSid=%s)(objectClass=user))",
 171                                  ldap_encode_ndr_dom_sid(mem_ctx, sid));
 172         if (ret != LDB_SUCCESS) {
 173                 DEBUG(2, ("Failed to search for SID %s in SAM for NTP signing: "
 174                           "%s\n",
 175                           dom_sid_str_buf(sid, &buf),
 176                           ldb_errstring(ntp_signd_conn->ntp_signd->samdb)));
 177                 return signing_failure(ntp_signd_conn,
 178                                        mem_ctx,
 179                                        output,
 180                                        sign_request.packet_id);
 181         }
 182
 183         if (res->count == 0) {
 184                 DEBUG(2, ("Failed to find SID %s in SAM for NTP signing\n",
 185                           dom_sid_str_buf(sid, &buf)));
 186                 return signing_failure(ntp_signd_conn,
 187                                        mem_ctx,
 188                                        output,
 189                                        sign_request.packet_id);
 190         } else if (res->count != 1) {
 191                 DEBUG(1, ("Found SID %s %u times in SAM for NTP signing\n",
 192                           dom_sid_str_buf(sid, &buf),
 193                           res->count));
 194                 return signing_failure(ntp_signd_conn,
 195                                        mem_ctx,
 196                                        output,
 197                                        sign_request.packet_id);
 198         }
 199
 200         user_account_control = ldb_msg_find_attr_as_uint(res->msgs[0],
 201                                                          "userAccountControl",
 202                                                          0);
 203
 204         if (user_account_control & UF_ACCOUNTDISABLE) {
 205                 DEBUG(1, ("Account %s for SID [%s] is disabled\n",
 206                           ldb_dn_get_linearized(res->msgs[0]->dn),
 207                           dom_sid_str_buf(sid, &buf)));
 208                 return NT_STATUS_ACCESS_DENIED;
 209         }
 210
 211         if (!(user_account_control & (UF_INTERDOMAIN_TRUST_ACCOUNT|UF_SERVER_TRUST_ACCOUNT|UF_WORKSTATION_TRUST_ACCOUNT))) {
 212                 DEBUG(1, ("Account %s for SID [%s] is not a trust account\n",
 213                           ldb_dn_get_linearized(res->msgs[0]->dn),
 214                           dom_sid_str_buf(sid, &buf)));
 215                 return NT_STATUS_ACCESS_DENIED;
 216         }
 217
 218         nt_hash = samdb_result_hash(mem_ctx, res->msgs[0], "unicodePwd");
 219         if (!nt_hash) {
 220                 DEBUG(1, ("No unicodePwd found on record of SID %s "
 221                           "for NTP signing\n",
 222                           dom_sid_str_buf(sid, &buf)));
 223                 return signing_failure(ntp_signd_conn,
 224                                        mem_ctx,
 225                                        output,
 226                                        sign_request.packet_id);
 227         }
 228
 229         /* Generate the reply packet */
 230         signed_reply.packet_id = sign_request.packet_id;
 231         signed_reply.op = SIGNING_SUCCESS;
 232         signed_reply.signed_packet = data_blob_talloc(mem_ctx,
 233                                                       NULL,
 234                                                       sign_request.packet_to_sign.length + 20);
 235
 236         if (!signed_reply.signed_packet.data) {
 237                 return signing_failure(ntp_signd_conn,
 238                                        mem_ctx,
 239                                        output,
 240                                        sign_request.packet_id);
 241         }
 242
 243         memcpy(signed_reply.signed_packet.data, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 244         SIVAL(signed_reply.signed_packet.data, sign_request.packet_to_sign.length, sign_request.key_id);
 245
 246         /* Sign the NTP response with the unicodePwd */
 247         MD5Init(&ctx);
 248         MD5Update(&ctx, nt_hash->hash, sizeof(nt_hash->hash));
 249         MD5Update(&ctx, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 250         MD5Final(signed_reply.signed_packet.data + sign_request.packet_to_sign.length + 4, &ctx);
 251
 252
 253         /* Place it into the packet for the wire */
 254         ndr_err = ndr_push_struct_blob(output, mem_ctx, &signed_reply,
 255                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
 256
 257         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 258                 DEBUG(1,("failed to push ntp error reply\n"));
 259                 return ndr_map_error2ntstatus(ndr_err);
 260         }
 261
 262         return NT_STATUS_OK;
 263 }
 264
 265 /*
 266   called on a tcp recv
 267 */
 268 static void ntp_signd_recv(struct stream_connection *conn, uint16_t flags)
 269 {
 270         struct ntp_signd_connection *ntp_signd_conn = talloc_get_type(conn->private_data,
 271                                                         struct ntp_signd_connection);
 272         ntp_signd_terminate_connection(ntp_signd_conn,
 273                                        "ntp_signd_recv: called");
 274 }
 275
 276 /*
 277   called when we can write to a connection
 278 */
 279 static void ntp_signd_send(struct stream_connection *conn, uint16_t flags)
 280 {
 281         struct ntp_signd_connection *ntp_signd_conn = talloc_get_type(conn->private_data,
 282                                                         struct ntp_signd_connection);
 283         /* this should never be triggered! */
 284         ntp_signd_terminate_connection(ntp_signd_conn,
 285                                        "ntp_signd_send: called");
 286 }
 287
 288 struct ntp_signd_call {
 289         struct ntp_signd_connection *ntp_signd_conn;
 290         DATA_BLOB in;
 291         DATA_BLOB out;
 292         uint8_t out_hdr[4];
 293         struct iovec out_iov[2];
 294 };
 295
 296 static void ntp_signd_call_writev_done(struct tevent_req *subreq);
 297
 298 static void ntp_signd_call_loop(struct tevent_req *subreq)
 299 {
 300         struct ntp_signd_connection *ntp_signd_conn = tevent_req_callback_data(subreq,
 301                                       struct ntp_signd_connection);
 302         struct ntp_signd_call *call;
 303         NTSTATUS status;
 304
 305         call = talloc(ntp_signd_conn, struct ntp_signd_call);
 306         if (call == NULL) {
 307                 ntp_signd_terminate_connection(ntp_signd_conn,
 308                                 "ntp_signd_call_loop: "
 309                                 "no memory for ntp_signd_call");
 310                 return;
 311         }
 312         call->ntp_signd_conn = ntp_signd_conn;
 313
 314         status = tstream_read_pdu_blob_recv(subreq,
 315                                             call,
 316                                             &call->in);
 317         TALLOC_FREE(subreq);
 318         if (!NT_STATUS_IS_OK(status)) {
 319                 const char *reason;
 320
 321                 reason = talloc_asprintf(call, "ntp_signd_call_loop: "
 322                                          "tstream_read_pdu_blob_recv() - %s",
 323                                          nt_errstr(status));
 324                 if (reason == NULL) {
 325                         reason = nt_errstr(status);
 326                 }
 327
 328                 ntp_signd_terminate_connection(ntp_signd_conn, reason);
 329                 return;
 330         }
 331
 332         DEBUG(10,("Received NTP TCP packet of length %lu from %s\n",
 333                  (long) call->in.length,
 334                  tsocket_address_string(ntp_signd_conn->conn->remote_address, call)));
 335
 336         /* skip length header */
 337         call->in.data +=4;
 338         call->in.length -= 4;
 339
 340         status = ntp_signd_process(ntp_signd_conn,
 341                                      call,
 342                                      &call->in,
 343                                      &call->out);
 344         if (! NT_STATUS_IS_OK(status)) {
 345                 const char *reason;
 346
 347                 reason = talloc_asprintf(call, "ntp_signd_process failed: %s",
 348                                          nt_errstr(status));
 349                 if (reason == NULL) {
 350                         reason = nt_errstr(status);
 351                 }
 352
 353                 ntp_signd_terminate_connection(ntp_signd_conn, reason);
 354                 return;
 355         }
 356
 357         /* First add the length of the out buffer */
 358         RSIVAL(call->out_hdr, 0, call->out.length);
 359         call->out_iov[0].iov_base = (char *) call->out_hdr;
 360         call->out_iov[0].iov_len = 4;
 361
 362         call->out_iov[1].iov_base = (char *) call->out.data;
 363         call->out_iov[1].iov_len = call->out.length;
 364
 365         subreq = tstream_writev_queue_send(call,
 366                                            ntp_signd_conn->conn->event.ctx,
 367                                            ntp_signd_conn->tstream,
 368                                            ntp_signd_conn->send_queue,
 369                                            call->out_iov, 2);
 370         if (subreq == NULL) {
 371                 ntp_signd_terminate_connection(ntp_signd_conn, "ntp_signd_call_loop: "
 372                                 "no memory for tstream_writev_queue_send");
 373                 return;
 374         }
 375
 376         tevent_req_set_callback(subreq, ntp_signd_call_writev_done, call);
 377
 378         /*
 379          * The NTP tcp pdu's has the length as 4 byte (initial_read_size),
 380          * packet_full_request_u32 provides the pdu length then.
 381          */
 382         subreq = tstream_read_pdu_blob_send(ntp_signd_conn,
 383                                             ntp_signd_conn->conn->event.ctx,
 384                                             ntp_signd_conn->tstream,
 385                                             4, /* initial_read_size */
 386                                             packet_full_request_u32,
 387                                             ntp_signd_conn);
 388         if (subreq == NULL) {
 389                 ntp_signd_terminate_connection(ntp_signd_conn, "ntp_signd_call_loop: "
 390                                 "no memory for tstream_read_pdu_blob_send");
 391                 return;
 392         }
 393         tevent_req_set_callback(subreq, ntp_signd_call_loop, ntp_signd_conn);
 394 }
 395
 396 static void ntp_signd_call_writev_done(struct tevent_req *subreq)
 397 {
 398         struct ntp_signd_call *call = tevent_req_callback_data(subreq,
 399                         struct ntp_signd_call);
 400         int sys_errno;
 401         int rc;
 402
 403         rc = tstream_writev_queue_recv(subreq, &sys_errno);
 404         TALLOC_FREE(subreq);
 405         if (rc == -1) {
 406                 const char *reason;
 407
 408                 reason = talloc_asprintf(call, "ntp_signd_call_writev_done: "
 409                                          "tstream_writev_queue_recv() - %d:%s",
 410                                          sys_errno, strerror(sys_errno));
 411                 if (!reason) {
 412                         reason = "ntp_signd_call_writev_done: "
 413                                  "tstream_writev_queue_recv() failed";
 414                 }
 415
 416                 ntp_signd_terminate_connection(call->ntp_signd_conn, reason);
 417                 return;
 418         }
 419
 420         /* We don't care about errors */
 421
 422         talloc_free(call);
 423 }
 424
 425 /*
 426   called when we get a new connection
 427 */
 428 static void ntp_signd_accept(struct stream_connection *conn)
 429 {
 430         struct ntp_signd_server *ntp_signd = talloc_get_type(conn->private_data,
 431                                                 struct ntp_signd_server);
 432         struct ntp_signd_connection *ntp_signd_conn;
 433         struct tevent_req *subreq;
 434         int rc;
 435
 436         ntp_signd_conn = talloc_zero(conn, struct ntp_signd_connection);
 437         if (ntp_signd_conn == NULL) {
 438                 stream_terminate_connection(conn,
 439                                 "ntp_signd_accept: out of memory");
 440                 return;
 441         }
 442
 443         ntp_signd_conn->send_queue = tevent_queue_create(conn,
 444                         "ntp_signd_accept");
 445         if (ntp_signd_conn->send_queue == NULL) {
 446                 stream_terminate_connection(conn,
 447                                 "ntp_signd_accept: out of memory");
 448                 return;
 449         }
 450
 451         TALLOC_FREE(conn->event.fde);
 452
 453         rc = tstream_bsd_existing_socket(ntp_signd_conn,
 454                         socket_get_fd(conn->socket),
 455                         &ntp_signd_conn->tstream);
 456         if (rc < 0) {
 457                 stream_terminate_connection(conn,
 458                                 "ntp_signd_accept: out of memory");
 459                 return;
 460         }
 461
 462         ntp_signd_conn->conn = conn;
 463         ntp_signd_conn->ntp_signd = ntp_signd;
 464         conn->private_data = ntp_signd_conn;
 465
 466         /*
 467          * The NTP tcp pdu's has the length as 4 byte (initial_read_size),
 468          * packet_full_request_u32 provides the pdu length then.
 469          */
 470         subreq = tstream_read_pdu_blob_send(ntp_signd_conn,
 471                                             ntp_signd_conn->conn->event.ctx,
 472                                             ntp_signd_conn->tstream,
 473                                             4, /* initial_read_size */
 474                                             packet_full_request_u32,
 475                                             ntp_signd_conn);
 476         if (subreq == NULL) {
 477                 ntp_signd_terminate_connection(ntp_signd_conn,
 478                                 "ntp_signd_accept: "
 479                                 "no memory for tstream_read_pdu_blob_send");
 480                 return;
 481         }
 482         tevent_req_set_callback(subreq, ntp_signd_call_loop, ntp_signd_conn);
 483 }
 484
 485 static const struct stream_server_ops ntp_signd_stream_ops = {
 486         .name                   = "ntp_signd",
 487         .accept_connection      = ntp_signd_accept,
 488         .recv_handler           = ntp_signd_recv,
 489         .send_handler           = ntp_signd_send
 490 };
 491
 492 /*
 493   startup the ntp_signd task
 494 */
 495 static NTSTATUS ntp_signd_task_init(struct task_server *task)
 496 {
 497         struct ntp_signd_server *ntp_signd;
 498         NTSTATUS status;
 499
 500         const char *address;
 501
 502         if (!directory_create_or_exist_strict(lpcfg_ntp_signd_socket_directory(task->lp_ctx), geteuid(), 0750)) {
 503                 char *error = talloc_asprintf(task, "Cannot create NTP signd pipe directory: %s",
 504                                               lpcfg_ntp_signd_socket_directory(task->lp_ctx));
 505                 task_server_terminate(task,
 506                                       error, true);
 507                 return NT_STATUS_UNSUCCESSFUL;
 508         }
 509
 510         task_server_set_title(task, "task[ntp_signd]");
 511
 512         ntp_signd = talloc(task, struct ntp_signd_server);
 513         if (ntp_signd == NULL) {
 514                 task_server_terminate(task, "ntp_signd: out of memory", true);
 515                 return NT_STATUS_NO_MEMORY;
 516         }
 517
 518         ntp_signd->task = task;
 519
 520         /* Must be system to get at the password hashes */
 521         ntp_signd->samdb = samdb_connect(ntp_signd,
 522                                          task->event_ctx,
 523                                          task->lp_ctx,
 524                                          system_session(task->lp_ctx),
 525                                          NULL,
 526                                          0);
 527         if (ntp_signd->samdb == NULL) {
 528                 task_server_terminate(task, "ntp_signd failed to open samdb", true);
 529                 return NT_STATUS_UNSUCCESSFUL;
 530         }
 531
 532         address = talloc_asprintf(ntp_signd, "%s/socket", lpcfg_ntp_signd_socket_directory(task->lp_ctx));
 533         if (address == NULL) {
 534                 task_server_terminate(
 535                     task, "ntp_signd out of memory in talloc_asprintf()", true);
 536                 return NT_STATUS_NO_MEMORY;
 537         }
 538
 539         status = stream_setup_socket(ntp_signd->task,
 540                                      ntp_signd->task->event_ctx,
 541                                      ntp_signd->task->lp_ctx,
 542                                      task->model_ops,
 543                                      &ntp_signd_stream_ops,
 544                                      "unix", address, NULL,
 545                                      lpcfg_socket_options(ntp_signd->task->lp_ctx),
 546                                      ntp_signd,
 547                                      ntp_signd->task->process_context);
 548         if (!NT_STATUS_IS_OK(status)) {
 549                 DEBUG(0,("Failed to bind to %s - %s\n",
 550                          address, nt_errstr(status)));
 551                 return status;
 552         }
 553
 554         return NT_STATUS_OK;
 555
 556 }
 557
 558
 559 /* called at smbd startup - register ourselves as a server service */
 560 NTSTATUS server_service_ntp_signd_init(TALLOC_CTX *ctx)
 561 {
 562         static const struct service_details details = {
 563                 .inhibit_fork_on_accept = true,
 564                 .inhibit_pre_fork = true,
 565                 .task_init = ntp_signd_task_init,
 566                 .post_fork = NULL
 567         };
 568         return register_server_service(ctx, "ntp_signd", &details);
 569 }