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(void);
  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         struct MD5Context ctx;
 113         struct samr_Password *nt_hash;
 114         uint32_t user_account_control;
 115         int ret;
 116
 117         ndr_err = ndr_pull_struct_blob_all(input, mem_ctx,
 118                                            &sign_request,
 119                                            (ndr_pull_flags_fn_t)ndr_pull_sign_request);
 120
 121         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 122                 DEBUG(1,("failed to parse ntp signing request\n"));
 123                 dump_data(1, input->data, input->length);
 124                 return ndr_map_error2ntstatus(ndr_err);
 125         }
 126
 127         /* We need to implement 'check signature' and 'request server
 128          * to sign' operations at some point */
 129         if (sign_request.op != SIGN_TO_CLIENT) {
 130                 return signing_failure(ntp_signd_conn,
 131                                        mem_ctx,
 132                                        output,
 133                                        sign_request.packet_id);
 134         }
 135
 136         /* We need to implement 'check signature' and 'request server
 137          * to sign' operations at some point */
 138         if (sign_request.version != NTP_SIGND_PROTOCOL_VERSION_0) {
 139                 return signing_failure(ntp_signd_conn,
 140                                        mem_ctx,
 141                                        output,
 142                                        sign_request.packet_id);
 143         }
 144
 145         domain_sid = samdb_domain_sid(ntp_signd_conn->ntp_signd->samdb);
 146         if (domain_sid == NULL) {
 147                 return signing_failure(ntp_signd_conn,
 148                                        mem_ctx,
 149                                        output,
 150                                        sign_request.packet_id);
 151         }
 152
 153         /* The top bit is a 'key selector' */
 154         sid = dom_sid_add_rid(mem_ctx, domain_sid,
 155                               sign_request.key_id & 0x7FFFFFFF);
 156         if (sid == NULL) {
 157                 talloc_free(mem_ctx);
 158                 return signing_failure(ntp_signd_conn,
 159                                        mem_ctx,
 160                                        output,
 161                                        sign_request.packet_id);
 162         }
 163
 164         ret = ldb_search(ntp_signd_conn->ntp_signd->samdb, mem_ctx,
 165                                  &res,
 166                                  ldb_get_default_basedn(ntp_signd_conn->ntp_signd->samdb),
 167                                  LDB_SCOPE_SUBTREE,
 168                                  attrs,
 169                                  "(&(objectSid=%s)(objectClass=user))",
 170                                  ldap_encode_ndr_dom_sid(mem_ctx, sid));
 171         if (ret != LDB_SUCCESS) {
 172                 DEBUG(2, ("Failed to search for SID %s in SAM for NTP signing: "
 173                           "%s\n",
 174                           dom_sid_string(mem_ctx, sid),
 175                           ldb_errstring(ntp_signd_conn->ntp_signd->samdb)));
 176                 return signing_failure(ntp_signd_conn,
 177                                        mem_ctx,
 178                                        output,
 179                                        sign_request.packet_id);
 180         }
 181
 182         if (res->count == 0) {
 183                 DEBUG(5, ("Failed to find SID %s in SAM for NTP signing\n",
 184                           dom_sid_string(mem_ctx, sid)));
 185         } else if (res->count != 1) {
 186                 DEBUG(1, ("Found SID %s %u times in SAM for NTP signing\n",
 187                           dom_sid_string(mem_ctx, sid), res->count));
 188                 return signing_failure(ntp_signd_conn,
 189                                        mem_ctx,
 190                                        output,
 191                                        sign_request.packet_id);
 192         }
 193
 194         user_account_control = ldb_msg_find_attr_as_uint(res->msgs[0],
 195                                                          "userAccountControl",
 196                                                          0);
 197
 198         if (user_account_control & UF_ACCOUNTDISABLE) {
 199                 DEBUG(1, ("Account %s for SID [%s] is disabled\n",
 200                           ldb_dn_get_linearized(res->msgs[0]->dn),
 201                           dom_sid_string(mem_ctx, sid)));
 202                 return NT_STATUS_ACCESS_DENIED;
 203         }
 204
 205         if (!(user_account_control & (UF_INTERDOMAIN_TRUST_ACCOUNT|UF_SERVER_TRUST_ACCOUNT|UF_WORKSTATION_TRUST_ACCOUNT))) {
 206                 DEBUG(1, ("Account %s for SID [%s] is not a trust account\n",
 207                           ldb_dn_get_linearized(res->msgs[0]->dn),
 208                           dom_sid_string(mem_ctx, sid)));
 209                 return NT_STATUS_ACCESS_DENIED;
 210         }
 211
 212         nt_hash = samdb_result_hash(mem_ctx, res->msgs[0], "unicodePwd");
 213         if (!nt_hash) {
 214                 DEBUG(1, ("No unicodePwd found on record of SID %s "
 215                           "for NTP signing\n", dom_sid_string(mem_ctx, sid)));
 216                 return signing_failure(ntp_signd_conn,
 217                                        mem_ctx,
 218                                        output,
 219                                        sign_request.packet_id);
 220         }
 221
 222         /* Generate the reply packet */
 223         signed_reply.packet_id = sign_request.packet_id;
 224         signed_reply.op = SIGNING_SUCCESS;
 225         signed_reply.signed_packet = data_blob_talloc(mem_ctx,
 226                                                       NULL,
 227                                                       sign_request.packet_to_sign.length + 20);
 228
 229         if (!signed_reply.signed_packet.data) {
 230                 return signing_failure(ntp_signd_conn,
 231                                        mem_ctx,
 232                                        output,
 233                                        sign_request.packet_id);
 234         }
 235
 236         memcpy(signed_reply.signed_packet.data, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 237         SIVAL(signed_reply.signed_packet.data, sign_request.packet_to_sign.length, sign_request.key_id);
 238
 239         /* Sign the NTP response with the unicodePwd */
 240         MD5Init(&ctx);
 241         MD5Update(&ctx, nt_hash->hash, sizeof(nt_hash->hash));
 242         MD5Update(&ctx, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 243         MD5Final(signed_reply.signed_packet.data + sign_request.packet_to_sign.length + 4, &ctx);
 244
 245
 246         /* Place it into the packet for the wire */
 247         ndr_err = ndr_push_struct_blob(output, mem_ctx, &signed_reply,
 248                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
 249
 250         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 251                 DEBUG(1,("failed to push ntp error reply\n"));
 252                 return ndr_map_error2ntstatus(ndr_err);
 253         }
 254
 255         return NT_STATUS_OK;
 256 }
 257
 258 /*
 259   called on a tcp recv
 260 */
 261 static void ntp_signd_recv(struct stream_connection *conn, uint16_t flags)
 262 {
 263         struct ntp_signd_connection *ntp_signd_conn = talloc_get_type(conn->private_data,
 264                                                         struct ntp_signd_connection);
 265         ntp_signd_terminate_connection(ntp_signd_conn,
 266                                        "ntp_signd_recv: called");
 267 }
 268
 269 /*
 270   called when we can write to a connection
 271 */
 272 static void ntp_signd_send(struct stream_connection *conn, uint16_t flags)
 273 {
 274         struct ntp_signd_connection *ntp_signd_conn = talloc_get_type(conn->private_data,
 275                                                         struct ntp_signd_connection);
 276         /* this should never be triggered! */
 277         ntp_signd_terminate_connection(ntp_signd_conn,
 278                                        "ntp_signd_send: called");
 279 }
 280
 281 struct ntp_signd_call {
 282         struct ntp_signd_connection *ntp_signd_conn;
 283         DATA_BLOB in;
 284         DATA_BLOB out;
 285         uint8_t out_hdr[4];
 286         struct iovec out_iov[2];
 287 };
 288
 289 static void ntp_signd_call_writev_done(struct tevent_req *subreq);
 290
 291 static void ntp_signd_call_loop(struct tevent_req *subreq)
 292 {
 293         struct ntp_signd_connection *ntp_signd_conn = tevent_req_callback_data(subreq,
 294                                       struct ntp_signd_connection);
 295         struct ntp_signd_call *call;
 296         NTSTATUS status;
 297
 298         call = talloc(ntp_signd_conn, struct ntp_signd_call);
 299         if (call == NULL) {
 300                 ntp_signd_terminate_connection(ntp_signd_conn,
 301                                 "ntp_signd_call_loop: "
 302                                 "no memory for ntp_signd_call");
 303                 return;
 304         }
 305         call->ntp_signd_conn = ntp_signd_conn;
 306
 307         status = tstream_read_pdu_blob_recv(subreq,
 308                                             call,
 309                                             &call->in);
 310         TALLOC_FREE(subreq);
 311         if (!NT_STATUS_IS_OK(status)) {
 312                 const char *reason;
 313
 314                 reason = talloc_asprintf(call, "ntp_signd_call_loop: "
 315                                          "tstream_read_pdu_blob_recv() - %s",
 316                                          nt_errstr(status));
 317                 if (reason == NULL) {
 318                         reason = nt_errstr(status);
 319                 }
 320
 321                 ntp_signd_terminate_connection(ntp_signd_conn, reason);
 322                 return;
 323         }
 324
 325         DEBUG(10,("Received NTP TCP packet of length %lu from %s\n",
 326                  (long) call->in.length,
 327                  tsocket_address_string(ntp_signd_conn->conn->remote_address, call)));
 328
 329         /* skip length header */
 330         call->in.data +=4;
 331         call->in.length -= 4;
 332
 333         status = ntp_signd_process(ntp_signd_conn,
 334                                      call,
 335                                      &call->in,
 336                                      &call->out);
 337         if (! NT_STATUS_IS_OK(status)) {
 338                 const char *reason;
 339
 340                 reason = talloc_asprintf(call, "ntp_signd_process failed: %s",
 341                                          nt_errstr(status));
 342                 if (reason == NULL) {
 343                         reason = nt_errstr(status);
 344                 }
 345
 346                 ntp_signd_terminate_connection(ntp_signd_conn, reason);
 347                 return;
 348         }
 349
 350         /* First add the length of the out buffer */
 351         RSIVAL(call->out_hdr, 0, call->out.length);
 352         call->out_iov[0].iov_base = (char *) call->out_hdr;
 353         call->out_iov[0].iov_len = 4;
 354
 355         call->out_iov[1].iov_base = (char *) call->out.data;
 356         call->out_iov[1].iov_len = call->out.length;
 357
 358         subreq = tstream_writev_queue_send(call,
 359                                            ntp_signd_conn->conn->event.ctx,
 360                                            ntp_signd_conn->tstream,
 361                                            ntp_signd_conn->send_queue,
 362                                            call->out_iov, 2);
 363         if (subreq == NULL) {
 364                 ntp_signd_terminate_connection(ntp_signd_conn, "ntp_signd_call_loop: "
 365                                 "no memory for tstream_writev_queue_send");
 366                 return;
 367         }
 368
 369         tevent_req_set_callback(subreq, ntp_signd_call_writev_done, call);
 370
 371         /*
 372          * The NTP tcp pdu's has the length as 4 byte (initial_read_size),
 373          * packet_full_request_u32 provides the pdu length then.
 374          */
 375         subreq = tstream_read_pdu_blob_send(ntp_signd_conn,
 376                                             ntp_signd_conn->conn->event.ctx,
 377                                             ntp_signd_conn->tstream,
 378                                             4, /* initial_read_size */
 379                                             packet_full_request_u32,
 380                                             ntp_signd_conn);
 381         if (subreq == NULL) {
 382                 ntp_signd_terminate_connection(ntp_signd_conn, "ntp_signd_call_loop: "
 383                                 "no memory for tstream_read_pdu_blob_send");
 384                 return;
 385         }
 386         tevent_req_set_callback(subreq, ntp_signd_call_loop, ntp_signd_conn);
 387 }
 388
 389 static void ntp_signd_call_writev_done(struct tevent_req *subreq)
 390 {
 391         struct ntp_signd_call *call = tevent_req_callback_data(subreq,
 392                         struct ntp_signd_call);
 393         int sys_errno;
 394         int rc;
 395
 396         rc = tstream_writev_queue_recv(subreq, &sys_errno);
 397         TALLOC_FREE(subreq);
 398         if (rc == -1) {
 399                 const char *reason;
 400
 401                 reason = talloc_asprintf(call, "ntp_signd_call_writev_done: "
 402                                          "tstream_writev_queue_recv() - %d:%s",
 403                                          sys_errno, strerror(sys_errno));
 404                 if (!reason) {
 405                         reason = "ntp_signd_call_writev_done: "
 406                                  "tstream_writev_queue_recv() failed";
 407                 }
 408
 409                 ntp_signd_terminate_connection(call->ntp_signd_conn, reason);
 410                 return;
 411         }
 412
 413         /* We don't care about errors */
 414
 415         talloc_free(call);
 416 }
 417
 418 /*
 419   called when we get a new connection
 420 */
 421 static void ntp_signd_accept(struct stream_connection *conn)
 422 {
 423         struct ntp_signd_server *ntp_signd = talloc_get_type(conn->private_data,
 424                                                 struct ntp_signd_server);
 425         struct ntp_signd_connection *ntp_signd_conn;
 426         struct tevent_req *subreq;
 427         int rc;
 428
 429         ntp_signd_conn = talloc_zero(conn, struct ntp_signd_connection);
 430         if (ntp_signd_conn == NULL) {
 431                 stream_terminate_connection(conn,
 432                                 "ntp_signd_accept: out of memory");
 433                 return;
 434         }
 435
 436         ntp_signd_conn->send_queue = tevent_queue_create(conn,
 437                         "ntp_signd_accept");
 438         if (ntp_signd_conn->send_queue == NULL) {
 439                 stream_terminate_connection(conn,
 440                                 "ntp_signd_accept: out of memory");
 441                 return;
 442         }
 443
 444         TALLOC_FREE(conn->event.fde);
 445
 446         rc = tstream_bsd_existing_socket(ntp_signd_conn,
 447                         socket_get_fd(conn->socket),
 448                         &ntp_signd_conn->tstream);
 449         if (rc < 0) {
 450                 stream_terminate_connection(conn,
 451                                 "ntp_signd_accept: out of memory");
 452                 return;
 453         }
 454
 455         ntp_signd_conn->conn = conn;
 456         ntp_signd_conn->ntp_signd = ntp_signd;
 457         conn->private_data = ntp_signd_conn;
 458
 459         /*
 460          * The NTP tcp pdu's has the length as 4 byte (initial_read_size),
 461          * packet_full_request_u32 provides the pdu length then.
 462          */
 463         subreq = tstream_read_pdu_blob_send(ntp_signd_conn,
 464                                             ntp_signd_conn->conn->event.ctx,
 465                                             ntp_signd_conn->tstream,
 466                                             4, /* initial_read_size */
 467                                             packet_full_request_u32,
 468                                             ntp_signd_conn);
 469         if (subreq == NULL) {
 470                 ntp_signd_terminate_connection(ntp_signd_conn,
 471                                 "ntp_signd_accept: "
 472                                 "no memory for tstream_read_pdu_blob_send");
 473                 return;
 474         }
 475         tevent_req_set_callback(subreq, ntp_signd_call_loop, ntp_signd_conn);
 476 }
 477
 478 static const struct stream_server_ops ntp_signd_stream_ops = {
 479         .name                   = "ntp_signd",
 480         .accept_connection      = ntp_signd_accept,
 481         .recv_handler           = ntp_signd_recv,
 482         .send_handler           = ntp_signd_send
 483 };
 484
 485 /*
 486   startup the ntp_signd task
 487 */
 488 static void ntp_signd_task_init(struct task_server *task)
 489 {
 490         struct ntp_signd_server *ntp_signd;
 491         NTSTATUS status;
 492
 493         const struct model_ops *model_ops;
 494
 495         const char *address;
 496
 497         if (!directory_create_or_exist(lpcfg_ntp_signd_socket_directory(task->lp_ctx), geteuid(), 0755)) {
 498                 char *error = talloc_asprintf(task, "Cannot create NTP signd pipe directory: %s",
 499                                               lpcfg_ntp_signd_socket_directory(task->lp_ctx));
 500                 task_server_terminate(task,
 501                                       error, true);
 502                 return;
 503         }
 504
 505         /* within the ntp_signd task we want to be a single process, so
 506            ask for the single process model ops and pass these to the
 507            stream_setup_socket() call. */
 508         model_ops = process_model_startup("single");
 509         if (!model_ops) {
 510                 DEBUG(0,("Can't find 'single' process model_ops\n"));
 511                 return;
 512         }
 513
 514         task_server_set_title(task, "task[ntp_signd]");
 515
 516         ntp_signd = talloc(task, struct ntp_signd_server);
 517         if (ntp_signd == NULL) {
 518                 task_server_terminate(task, "ntp_signd: out of memory", true);
 519                 return;
 520         }
 521
 522         ntp_signd->task = task;
 523
 524         /* Must be system to get at the password hashes */
 525         ntp_signd->samdb = samdb_connect(ntp_signd, task->event_ctx, task->lp_ctx, system_session(task->lp_ctx), 0);
 526         if (ntp_signd->samdb == NULL) {
 527                 task_server_terminate(task, "ntp_signd failed to open samdb", true);
 528                 return;
 529         }
 530
 531         address = talloc_asprintf(ntp_signd, "%s/socket", lpcfg_ntp_signd_socket_directory(task->lp_ctx));
 532
 533         status = stream_setup_socket(ntp_signd->task,
 534                                      ntp_signd->task->event_ctx,
 535                                      ntp_signd->task->lp_ctx,
 536                                      model_ops,
 537                                      &ntp_signd_stream_ops,
 538                                      "unix", address, NULL,
 539                                      lpcfg_socket_options(ntp_signd->task->lp_ctx),
 540                                      ntp_signd);
 541         if (!NT_STATUS_IS_OK(status)) {
 542                 DEBUG(0,("Failed to bind to %s - %s\n",
 543                          address, nt_errstr(status)));
 544                 return;
 545         }
 546
 547 }
 548
 549
 550 /* called at smbd startup - register ourselves as a server service */
 551 NTSTATUS server_service_ntp_signd_init(void)
 552 {
 553         return register_server_service("ntp_signd", ntp_signd_task_init);
 554 }