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 "lib/ldb/include/ldb.h"
  39 #include "lib/ldb/include/ldb_errors.h"
  40 #include "../lib/crypto/md5.h"
  41 #include "system/network.h"
  42 #include "system/passwd.h"
  43
  44 /*
  45   top level context structure for the ntp_signd server
  46 */
  47 struct ntp_signd_server {
  48         struct task_server *task;
  49         struct ldb_context *samdb;
  50 };
  51
  52 /*
  53   state of an open connection
  54 */
  55 struct ntp_signd_connection {
  56         /* stream connection we belong to */
  57         struct stream_connection *conn;
  58
  59         /* the ntp_signd_server the connection belongs to */
  60         struct ntp_signd_server *ntp_signd;
  61
  62         struct tstream_context *tstream;
  63
  64         struct tevent_queue *send_queue;
  65 };
  66
  67 static void ntp_signd_terminate_connection(struct ntp_signd_connection *ntp_signd_conn, const char *reason)
  68 {
  69         stream_terminate_connection(ntp_signd_conn->conn, reason);
  70 }
  71
  72 static NTSTATUS signing_failure(struct ntp_signd_connection *ntp_signdconn,
  73                                 TALLOC_CTX *mem_ctx,
  74                                 DATA_BLOB *output,
  75                                 uint32_t packet_id)
  76 {
  77         struct signed_reply signed_reply;
  78         enum ndr_err_code ndr_err;
  79
  80         signed_reply.op = SIGNING_FAILURE;
  81         signed_reply.packet_id = packet_id;
  82         signed_reply.signed_packet = data_blob(NULL, 0);
  83
  84         ndr_err = ndr_push_struct_blob(output, mem_ctx, &signed_reply,
  85                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
  86
  87         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
  88                 DEBUG(1,("failed to push ntp error reply\n"));
  89                 return ndr_map_error2ntstatus(ndr_err);
  90         }
  91
  92         return NT_STATUS_OK;
  93 }
  94
  95 /*
  96   receive a full packet on a NTP_SIGND connection
  97 */
  98 static NTSTATUS ntp_signd_process(struct ntp_signd_connection *ntp_signd_conn,
  99                                   TALLOC_CTX *mem_ctx,
 100                                   DATA_BLOB *input,
 101                                   DATA_BLOB *output)
 102 {
 103         const struct dom_sid *domain_sid;
 104         struct dom_sid *sid;
 105         struct sign_request sign_request;
 106         struct signed_reply signed_reply;
 107         enum ndr_err_code ndr_err;
 108         struct ldb_result *res;
 109         const char *attrs[] = { "unicodePwd", "userAccountControl", "cn", NULL };
 110         struct MD5Context ctx;
 111         struct samr_Password *nt_hash;
 112         uint32_t user_account_control;
 113         int ret;
 114
 115         ndr_err = ndr_pull_struct_blob_all(input, mem_ctx,
 116                                            &sign_request,
 117                                            (ndr_pull_flags_fn_t)ndr_pull_sign_request);
 118
 119         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 120                 DEBUG(1,("failed to parse ntp signing request\n"));
 121                 dump_data(1, input->data, input->length);
 122                 return ndr_map_error2ntstatus(ndr_err);
 123         }
 124
 125         /* We need to implement 'check signature' and 'request server
 126          * to sign' operations at some point */
 127         if (sign_request.op != SIGN_TO_CLIENT) {
 128                 return signing_failure(ntp_signd_conn,
 129                                        mem_ctx,
 130                                        output,
 131                                        sign_request.packet_id);
 132         }
 133
 134         /* We need to implement 'check signature' and 'request server
 135          * to sign' operations at some point */
 136         if (sign_request.version != NTP_SIGND_PROTOCOL_VERSION_0) {
 137                 return signing_failure(ntp_signd_conn,
 138                                        mem_ctx,
 139                                        output,
 140                                        sign_request.packet_id);
 141         }
 142
 143         domain_sid = samdb_domain_sid(ntp_signd_conn->ntp_signd->samdb);
 144         if (domain_sid == NULL) {
 145                 return signing_failure(ntp_signd_conn,
 146                                        mem_ctx,
 147                                        output,
 148                                        sign_request.packet_id);
 149         }
 150
 151         /* The top bit is a 'key selector' */
 152         sid = dom_sid_add_rid(mem_ctx, domain_sid,
 153                               sign_request.key_id & 0x7FFFFFFF);
 154         if (sid == NULL) {
 155                 talloc_free(mem_ctx);
 156                 return signing_failure(ntp_signd_conn,
 157                                        mem_ctx,
 158                                        output,
 159                                        sign_request.packet_id);
 160         }
 161
 162         ret = ldb_search(ntp_signd_conn->ntp_signd->samdb, mem_ctx,
 163                                  &res,
 164                                  ldb_get_default_basedn(ntp_signd_conn->ntp_signd->samdb),
 165                                  LDB_SCOPE_SUBTREE,
 166                                  attrs,
 167                                  "(&(objectSid=%s)(objectClass=user))",
 168                                  ldap_encode_ndr_dom_sid(mem_ctx, sid));
 169         if (ret != LDB_SUCCESS) {
 170                 DEBUG(2, ("Failed to search for SID %s in SAM for NTP signing: "
 171                           "%s\n",
 172                           dom_sid_string(mem_ctx, sid),
 173                           ldb_errstring(ntp_signd_conn->ntp_signd->samdb)));
 174                 return signing_failure(ntp_signd_conn,
 175                                        mem_ctx,
 176                                        output,
 177                                        sign_request.packet_id);
 178         }
 179
 180         if (res->count == 0) {
 181                 DEBUG(5, ("Failed to find SID %s in SAM for NTP signing\n",
 182                           dom_sid_string(mem_ctx, sid)));
 183         } else if (res->count != 1) {
 184                 DEBUG(1, ("Found SID %s %u times in SAM for NTP signing\n",
 185                           dom_sid_string(mem_ctx, sid), res->count));
 186                 return signing_failure(ntp_signd_conn,
 187                                        mem_ctx,
 188                                        output,
 189                                        sign_request.packet_id);
 190         }
 191
 192         user_account_control = ldb_msg_find_attr_as_uint(res->msgs[0],
 193                                                          "userAccountControl",
 194                                                          0);
 195
 196         if (user_account_control & UF_ACCOUNTDISABLE) {
 197                 DEBUG(1, ("Account %s for SID [%s] is disabled\n",
 198                           ldb_dn_get_linearized(res->msgs[0]->dn),
 199                           dom_sid_string(mem_ctx, sid)));
 200                 return NT_STATUS_ACCESS_DENIED;
 201         }
 202
 203         if (!(user_account_control & (UF_INTERDOMAIN_TRUST_ACCOUNT|UF_SERVER_TRUST_ACCOUNT|UF_WORKSTATION_TRUST_ACCOUNT))) {
 204                 DEBUG(1, ("Account %s for SID [%s] is not a trust account\n",
 205                           ldb_dn_get_linearized(res->msgs[0]->dn),
 206                           dom_sid_string(mem_ctx, sid)));
 207                 return NT_STATUS_ACCESS_DENIED;
 208         }
 209
 210         nt_hash = samdb_result_hash(mem_ctx, res->msgs[0], "unicodePwd");
 211         if (!nt_hash) {
 212                 DEBUG(1, ("No unicodePwd found on record of SID %s "
 213                           "for NTP signing\n", dom_sid_string(mem_ctx, sid)));
 214                 return signing_failure(ntp_signd_conn,
 215                                        mem_ctx,
 216                                        output,
 217                                        sign_request.packet_id);
 218         }
 219
 220         /* Generate the reply packet */
 221         signed_reply.packet_id = sign_request.packet_id;
 222         signed_reply.op = SIGNING_SUCCESS;
 223         signed_reply.signed_packet = data_blob_talloc(mem_ctx,
 224                                                       NULL,
 225                                                       sign_request.packet_to_sign.length + 20);
 226
 227         if (!signed_reply.signed_packet.data) {
 228                 return signing_failure(ntp_signd_conn,
 229                                        mem_ctx,
 230                                        output,
 231                                        sign_request.packet_id);
 232         }
 233
 234         memcpy(signed_reply.signed_packet.data, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 235         SIVAL(signed_reply.signed_packet.data, sign_request.packet_to_sign.length, sign_request.key_id);
 236
 237         /* Sign the NTP response with the unicodePwd */
 238         MD5Init(&ctx);
 239         MD5Update(&ctx, nt_hash->hash, sizeof(nt_hash->hash));
 240         MD5Update(&ctx, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 241         MD5Final(signed_reply.signed_packet.data + sign_request.packet_to_sign.length + 4, &ctx);
 242
 243
 244         /* Place it into the packet for the wire */
 245         ndr_err = ndr_push_struct_blob(output, mem_ctx, &signed_reply,
 246                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
 247
 248         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 249                 DEBUG(1,("failed to push ntp error reply\n"));
 250                 return ndr_map_error2ntstatus(ndr_err);
 251         }
 252
 253         return NT_STATUS_OK;
 254 }
 255
 256 /*
 257   called on a tcp recv
 258 */
 259 static void ntp_signd_recv(struct stream_connection *conn, uint16_t flags)
 260 {
 261         struct ntp_signd_connection *ntp_signd_conn = talloc_get_type(conn->private_data,
 262                                                         struct ntp_signd_connection);
 263         ntp_signd_terminate_connection(ntp_signd_conn,
 264                                        "ntp_signd_recv: called");
 265 }
 266
 267 /*
 268   called when we can write to a connection
 269 */
 270 static void ntp_signd_send(struct stream_connection *conn, uint16_t flags)
 271 {
 272         struct ntp_signd_connection *ntp_signd_conn = talloc_get_type(conn->private_data,
 273                                                         struct ntp_signd_connection);
 274         /* this should never be triggered! */
 275         ntp_signd_terminate_connection(ntp_signd_conn,
 276                                        "ntp_signd_send: called");
 277 }
 278
 279 struct ntp_signd_call {
 280         struct ntp_signd_connection *ntp_signd_conn;
 281         DATA_BLOB in;
 282         DATA_BLOB out;
 283         uint8_t out_hdr[4];
 284         struct iovec out_iov[2];
 285 };
 286
 287 static void ntp_signd_call_writev_done(struct tevent_req *subreq);
 288
 289 static void ntp_signd_call_loop(struct tevent_req *subreq)
 290 {
 291         struct ntp_signd_connection *ntp_signd_conn = tevent_req_callback_data(subreq,
 292                                       struct ntp_signd_connection);
 293         struct ntp_signd_call *call;
 294         NTSTATUS status;
 295
 296         call = talloc(ntp_signd_conn, struct ntp_signd_call);
 297         if (call == NULL) {
 298                 ntp_signd_terminate_connection(ntp_signd_conn,
 299                                 "ntp_signd_call_loop: "
 300                                 "no memory for ntp_signd_call");
 301                 return;
 302         }
 303         call->ntp_signd_conn = ntp_signd_conn;
 304
 305         status = tstream_read_pdu_blob_recv(subreq,
 306                                             call,
 307                                             &call->in);
 308         TALLOC_FREE(subreq);
 309         if (!NT_STATUS_IS_OK(status)) {
 310                 const char *reason;
 311
 312                 reason = talloc_asprintf(call, "ntp_signd_call_loop: "
 313                                          "tstream_read_pdu_blob_recv() - %s",
 314                                          nt_errstr(status));
 315                 if (reason == NULL) {
 316                         reason = nt_errstr(status);
 317                 }
 318
 319                 ntp_signd_terminate_connection(ntp_signd_conn, reason);
 320                 return;
 321         }
 322
 323         DEBUG(10,("Received NTP TCP packet of length %lu from %s\n",
 324                  (long) call->in.length,
 325                  tsocket_address_string(ntp_signd_conn->conn->remote_address, call)));
 326
 327         /* skip length header */
 328         call->in.data +=4;
 329         call->in.length -= 4;
 330
 331         status = ntp_signd_process(ntp_signd_conn,
 332                                      call,
 333                                      &call->in,
 334                                      &call->out);
 335         if (! NT_STATUS_IS_OK(status)) {
 336                 const char *reason;
 337
 338                 reason = talloc_asprintf(call, "ntp_signd_process failed: %s",
 339                                          nt_errstr(status));
 340                 if (reason == NULL) {
 341                         reason = nt_errstr(status);
 342                 }
 343
 344                 ntp_signd_terminate_connection(ntp_signd_conn, reason);
 345                 return;
 346         }
 347
 348         /* First add the length of the out buffer */
 349         RSIVAL(call->out_hdr, 0, call->out.length);
 350         call->out_iov[0].iov_base = (char *) call->out_hdr;
 351         call->out_iov[0].iov_len = 4;
 352
 353         call->out_iov[1].iov_base = (char *) call->out.data;
 354         call->out_iov[1].iov_len = call->out.length;
 355
 356         subreq = tstream_writev_queue_send(call,
 357                                            ntp_signd_conn->conn->event.ctx,
 358                                            ntp_signd_conn->tstream,
 359                                            ntp_signd_conn->send_queue,
 360                                            call->out_iov, 2);
 361         if (subreq == NULL) {
 362                 ntp_signd_terminate_connection(ntp_signd_conn, "ntp_signd_call_loop: "
 363                                 "no memory for tstream_writev_queue_send");
 364                 return;
 365         }
 366
 367         tevent_req_set_callback(subreq, ntp_signd_call_writev_done, call);
 368
 369         /*
 370          * The NTP tcp pdu's has the length as 4 byte (initial_read_size),
 371          * packet_full_request_u32 provides the pdu length then.
 372          */
 373         subreq = tstream_read_pdu_blob_send(ntp_signd_conn,
 374                                             ntp_signd_conn->conn->event.ctx,
 375                                             ntp_signd_conn->tstream,
 376                                             4, /* initial_read_size */
 377                                             packet_full_request_u32,
 378                                             ntp_signd_conn);
 379         if (subreq == NULL) {
 380                 ntp_signd_terminate_connection(ntp_signd_conn, "ntp_signd_call_loop: "
 381                                 "no memory for tstream_read_pdu_blob_send");
 382                 return;
 383         }
 384         tevent_req_set_callback(subreq, ntp_signd_call_loop, ntp_signd_conn);
 385 }
 386
 387 static void ntp_signd_call_writev_done(struct tevent_req *subreq)
 388 {
 389         struct ntp_signd_call *call = tevent_req_callback_data(subreq,
 390                         struct ntp_signd_call);
 391         int sys_errno;
 392         int rc;
 393
 394         rc = tstream_writev_queue_recv(subreq, &sys_errno);
 395         TALLOC_FREE(subreq);
 396         if (rc == -1) {
 397                 const char *reason;
 398
 399                 reason = talloc_asprintf(call, "ntp_signd_call_writev_done: "
 400                                          "tstream_writev_queue_recv() - %d:%s",
 401                                          sys_errno, strerror(sys_errno));
 402                 if (!reason) {
 403                         reason = "ntp_signd_call_writev_done: "
 404                                  "tstream_writev_queue_recv() failed";
 405                 }
 406
 407                 ntp_signd_terminate_connection(call->ntp_signd_conn, reason);
 408                 return;
 409         }
 410
 411         /* We don't care about errors */
 412
 413         talloc_free(call);
 414 }
 415
 416 /*
 417   called when we get a new connection
 418 */
 419 static void ntp_signd_accept(struct stream_connection *conn)
 420 {
 421         struct ntp_signd_server *ntp_signd = talloc_get_type(conn->private_data,
 422                                                 struct ntp_signd_server);
 423         struct ntp_signd_connection *ntp_signd_conn;
 424         struct tevent_req *subreq;
 425         int rc;
 426
 427         ntp_signd_conn = talloc_zero(conn, struct ntp_signd_connection);
 428         if (ntp_signd_conn == NULL) {
 429                 stream_terminate_connection(conn,
 430                                 "ntp_signd_accept: out of memory");
 431                 return;
 432         }
 433
 434         ntp_signd_conn->send_queue = tevent_queue_create(conn,
 435                         "ntp_signd_accept");
 436         if (ntp_signd_conn->send_queue == NULL) {
 437                 stream_terminate_connection(conn,
 438                                 "ntp_signd_accept: out of memory");
 439                 return;
 440         }
 441
 442         TALLOC_FREE(conn->event.fde);
 443
 444         rc = tstream_bsd_existing_socket(ntp_signd_conn,
 445                         socket_get_fd(conn->socket),
 446                         &ntp_signd_conn->tstream);
 447         if (rc < 0) {
 448                 stream_terminate_connection(conn,
 449                                 "ntp_signd_accept: out of memory");
 450                 return;
 451         }
 452
 453         ntp_signd_conn->conn = conn;
 454         ntp_signd_conn->ntp_signd = ntp_signd;
 455         conn->private_data = ntp_signd_conn;
 456
 457         /*
 458          * The NTP tcp pdu's has the length as 4 byte (initial_read_size),
 459          * packet_full_request_u32 provides the pdu length then.
 460          */
 461         subreq = tstream_read_pdu_blob_send(ntp_signd_conn,
 462                                             ntp_signd_conn->conn->event.ctx,
 463                                             ntp_signd_conn->tstream,
 464                                             4, /* initial_read_size */
 465                                             packet_full_request_u32,
 466                                             ntp_signd_conn);
 467         if (subreq == NULL) {
 468                 ntp_signd_terminate_connection(ntp_signd_conn,
 469                                 "ntp_signd_accept: "
 470                                 "no memory for tstream_read_pdu_blob_send");
 471                 return;
 472         }
 473         tevent_req_set_callback(subreq, ntp_signd_call_loop, ntp_signd_conn);
 474 }
 475
 476 static const struct stream_server_ops ntp_signd_stream_ops = {
 477         .name                   = "ntp_signd",
 478         .accept_connection      = ntp_signd_accept,
 479         .recv_handler           = ntp_signd_recv,
 480         .send_handler           = ntp_signd_send
 481 };
 482
 483 /*
 484   startup the ntp_signd task
 485 */
 486 static void ntp_signd_task_init(struct task_server *task)
 487 {
 488         struct ntp_signd_server *ntp_signd;
 489         NTSTATUS status;
 490
 491         const struct model_ops *model_ops;
 492
 493         const char *address;
 494
 495         if (!directory_create_or_exist(lpcfg_ntp_signd_socket_directory(task->lp_ctx), geteuid(), 0755)) {
 496                 char *error = talloc_asprintf(task, "Cannot create NTP signd pipe directory: %s",
 497                                               lpcfg_ntp_signd_socket_directory(task->lp_ctx));
 498                 task_server_terminate(task,
 499                                       error, true);
 500                 return;
 501         }
 502
 503         /* within the ntp_signd task we want to be a single process, so
 504            ask for the single process model ops and pass these to the
 505            stream_setup_socket() call. */
 506         model_ops = process_model_startup("single");
 507         if (!model_ops) {
 508                 DEBUG(0,("Can't find 'single' process model_ops\n"));
 509                 return;
 510         }
 511
 512         task_server_set_title(task, "task[ntp_signd]");
 513
 514         ntp_signd = talloc(task, struct ntp_signd_server);
 515         if (ntp_signd == NULL) {
 516                 task_server_terminate(task, "ntp_signd: out of memory", true);
 517                 return;
 518         }
 519
 520         ntp_signd->task = task;
 521
 522         /* Must be system to get at the password hashes */
 523         ntp_signd->samdb = samdb_connect(ntp_signd, task->event_ctx, task->lp_ctx, system_session(task->lp_ctx), 0);
 524         if (ntp_signd->samdb == NULL) {
 525                 task_server_terminate(task, "ntp_signd failed to open samdb", true);
 526                 return;
 527         }
 528
 529         address = talloc_asprintf(ntp_signd, "%s/socket", lpcfg_ntp_signd_socket_directory(task->lp_ctx));
 530
 531         status = stream_setup_socket(ntp_signd->task,
 532                                      ntp_signd->task->event_ctx,
 533                                      ntp_signd->task->lp_ctx,
 534                                      model_ops,
 535                                      &ntp_signd_stream_ops,
 536                                      "unix", address, NULL,
 537                                      lpcfg_socket_options(ntp_signd->task->lp_ctx),
 538                                      ntp_signd);
 539         if (!NT_STATUS_IS_OK(status)) {
 540                 DEBUG(0,("Failed to bind to %s - %s\n",
 541                          address, nt_errstr(status)));
 542                 return;
 543         }
 544
 545 }
 546
 547
 548 /* called at smbd startup - register ourselves as a server service */
 549 NTSTATUS server_service_ntp_signd_init(void)
 550 {
 551         return register_server_service("ntp_signd", ntp_signd_task_init);
 552 }