source4/librpc/rpc/dcerpc_schannel.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    dcerpc schannel operations
   5
   6    Copyright (C) Andrew Tridgell 2004
   7    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2004-2005
   8    Copyright (C) Rafal Szczesniak 2006
   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 <tevent.h>
  26 #include "auth/auth.h"
  27 #include "libcli/composite/composite.h"
  28 #include "libcli/auth/libcli_auth.h"
  29 #include "librpc/gen_ndr/ndr_netlogon.h"
  30 #include "librpc/gen_ndr/ndr_netlogon_c.h"
  31 #include "auth/credentials/credentials.h"
  32 #include "librpc/rpc/dcerpc_proto.h"
  33 #include "param/param.h"
  34
  35 struct schannel_key_state {
  36         struct dcerpc_pipe *pipe;
  37         struct dcerpc_pipe *pipe2;
  38         struct dcerpc_binding *binding;
  39         bool dcerpc_schannel_auto;
  40         struct cli_credentials *credentials;
  41         struct netlogon_creds_CredentialState *creds;
  42         uint32_t local_negotiate_flags;
  43         uint32_t remote_negotiate_flags;
  44         struct netr_Credential credentials1;
  45         struct netr_Credential credentials2;
  46         struct netr_Credential credentials3;
  47         struct netr_ServerReqChallenge r;
  48         struct netr_ServerAuthenticate2 a;
  49         const struct samr_Password *mach_pwd;
  50 };
  51
  52
  53 static void continue_secondary_connection(struct composite_context *ctx);
  54 static void continue_bind_auth_none(struct composite_context *ctx);
  55 static void continue_srv_challenge(struct tevent_req *subreq);
  56 static void continue_srv_auth2(struct tevent_req *subreq);
  57 static void continue_get_capabilities(struct tevent_req *subreq);
  58
  59
  60 /*
  61   Stage 2 of schannel_key: Receive endpoint mapping and request secondary
  62   rpc connection
  63 */
  64 static void continue_epm_map_binding(struct composite_context *ctx)
  65 {
  66         struct composite_context *c;
  67         struct schannel_key_state *s;
  68         struct composite_context *sec_conn_req;
  69
  70         c = talloc_get_type(ctx->async.private_data, struct composite_context);
  71         s = talloc_get_type(c->private_data, struct schannel_key_state);
  72
  73         /* receive endpoint mapping */
  74         c->status = dcerpc_epm_map_binding_recv(ctx);
  75         if (!NT_STATUS_IS_OK(c->status)) {
  76                 DEBUG(0,("Failed to map DCERPC/TCP NCACN_NP pipe for '%s' - %s\n",
  77                          NDR_NETLOGON_UUID, nt_errstr(c->status)));
  78                 composite_error(c, c->status);
  79                 return;
  80         }
  81
  82         /* send a request for secondary rpc connection */
  83         sec_conn_req = dcerpc_secondary_connection_send(s->pipe,
  84                                                         s->binding);
  85         if (composite_nomem(sec_conn_req, c)) return;
  86
  87         composite_continue(c, sec_conn_req, continue_secondary_connection, c);
  88 }
  89
  90
  91 /*
  92   Stage 3 of schannel_key: Receive secondary rpc connection and perform
  93   non-authenticated bind request
  94 */
  95 static void continue_secondary_connection(struct composite_context *ctx)
  96 {
  97         struct composite_context *c;
  98         struct schannel_key_state *s;
  99         struct composite_context *auth_none_req;
 100
 101         c = talloc_get_type(ctx->async.private_data, struct composite_context);
 102         s = talloc_get_type(c->private_data, struct schannel_key_state);
 103
 104         /* receive secondary rpc connection */
 105         c->status = dcerpc_secondary_connection_recv(ctx, &s->pipe2);
 106         if (!composite_is_ok(c)) return;
 107
 108         talloc_steal(s, s->pipe2);
 109
 110         /* initiate a non-authenticated bind */
 111         auth_none_req = dcerpc_bind_auth_none_send(c, s->pipe2, &ndr_table_netlogon);
 112         if (composite_nomem(auth_none_req, c)) return;
 113
 114         composite_continue(c, auth_none_req, continue_bind_auth_none, c);
 115 }
 116
 117
 118 /*
 119   Stage 4 of schannel_key: Receive non-authenticated bind and get
 120   a netlogon challenge
 121 */
 122 static void continue_bind_auth_none(struct composite_context *ctx)
 123 {
 124         struct composite_context *c;
 125         struct schannel_key_state *s;
 126         struct tevent_req *subreq;
 127
 128         c = talloc_get_type(ctx->async.private_data, struct composite_context);
 129         s = talloc_get_type(c->private_data, struct schannel_key_state);
 130
 131         /* receive result of non-authenticated bind request */
 132         c->status = dcerpc_bind_auth_none_recv(ctx);
 133         if (!composite_is_ok(c)) return;
 134
 135         /* prepare a challenge request */
 136         s->r.in.server_name   = talloc_asprintf(c, "\\\\%s", dcerpc_server_name(s->pipe));
 137         if (composite_nomem(s->r.in.server_name, c)) return;
 138         s->r.in.computer_name = cli_credentials_get_workstation(s->credentials);
 139         s->r.in.credentials   = &s->credentials1;
 140         s->r.out.return_credentials  = &s->credentials2;
 141
 142         generate_random_buffer(s->credentials1.data, sizeof(s->credentials1.data));
 143
 144         /*
 145           request a netlogon challenge - a rpc request over opened secondary pipe
 146         */
 147         subreq = dcerpc_netr_ServerReqChallenge_r_send(s, c->event_ctx,
 148                                                        s->pipe2->binding_handle,
 149                                                        &s->r);
 150         if (composite_nomem(subreq, c)) return;
 151
 152         tevent_req_set_callback(subreq, continue_srv_challenge, c);
 153 }
 154
 155
 156 /*
 157   Stage 5 of schannel_key: Receive a challenge and perform authentication
 158   on the netlogon pipe
 159 */
 160 static void continue_srv_challenge(struct tevent_req *subreq)
 161 {
 162         struct composite_context *c;
 163         struct schannel_key_state *s;
 164
 165         c = tevent_req_callback_data(subreq, struct composite_context);
 166         s = talloc_get_type(c->private_data, struct schannel_key_state);
 167
 168         /* receive rpc request result - netlogon challenge */
 169         c->status = dcerpc_netr_ServerReqChallenge_r_recv(subreq, s);
 170         TALLOC_FREE(subreq);
 171         if (!composite_is_ok(c)) return;
 172
 173         /* prepare credentials for auth2 request */
 174         s->mach_pwd = cli_credentials_get_nt_hash(s->credentials, c);
 175
 176         /* auth2 request arguments */
 177         s->a.in.server_name      = s->r.in.server_name;
 178         s->a.in.account_name     = cli_credentials_get_username(s->credentials);
 179         s->a.in.secure_channel_type =
 180                 cli_credentials_get_secure_channel_type(s->credentials);
 181         s->a.in.computer_name    = cli_credentials_get_workstation(s->credentials);
 182         s->a.in.negotiate_flags  = &s->local_negotiate_flags;
 183         s->a.in.credentials      = &s->credentials3;
 184         s->a.out.negotiate_flags = &s->remote_negotiate_flags;
 185         s->a.out.return_credentials     = &s->credentials3;
 186
 187         s->creds = netlogon_creds_client_init(s,
 188                                               s->a.in.account_name,
 189                                               s->a.in.computer_name,
 190                                               s->a.in.secure_channel_type,
 191                                               &s->credentials1, &s->credentials2,
 192                                               s->mach_pwd, &s->credentials3,
 193                                               s->local_negotiate_flags);
 194         if (composite_nomem(s->creds, c)) {
 195                 return;
 196         }
 197         /*
 198           authenticate on the netlogon pipe - a rpc request over secondary pipe
 199         */
 200         subreq = dcerpc_netr_ServerAuthenticate2_r_send(s, c->event_ctx,
 201                                                         s->pipe2->binding_handle,
 202                                                         &s->a);
 203         if (composite_nomem(subreq, c)) return;
 204
 205         tevent_req_set_callback(subreq, continue_srv_auth2, c);
 206 }
 207
 208
 209 /*
 210   Stage 6 of schannel_key: Receive authentication request result and verify
 211   received credentials
 212 */
 213 static void continue_srv_auth2(struct tevent_req *subreq)
 214 {
 215         struct composite_context *c;
 216         struct schannel_key_state *s;
 217
 218         c = tevent_req_callback_data(subreq, struct composite_context);
 219         s = talloc_get_type(c->private_data, struct schannel_key_state);
 220
 221         /* receive rpc request result - auth2 credentials */
 222         c->status = dcerpc_netr_ServerAuthenticate2_r_recv(subreq, s);
 223         TALLOC_FREE(subreq);
 224         if (!composite_is_ok(c)) return;
 225
 226         if (!NT_STATUS_EQUAL(s->a.out.result, NT_STATUS_ACCESS_DENIED) &&
 227             !NT_STATUS_IS_OK(s->a.out.result)) {
 228                 composite_error(c, s->a.out.result);
 229                 return;
 230         }
 231
 232         /*
 233          * Strong keys could be unsupported (NT4) or disables. So retry with the
 234          * flags returned by the server. - asn
 235          */
 236         if (NT_STATUS_EQUAL(s->a.out.result, NT_STATUS_ACCESS_DENIED)) {
 237                 uint32_t lf = s->local_negotiate_flags;
 238                 const char *ln = NULL;
 239                 uint32_t rf = s->remote_negotiate_flags;
 240                 const char *rn = NULL;
 241
 242                 if (!s->dcerpc_schannel_auto) {
 243                         composite_error(c, s->a.out.result);
 244                         return;
 245                 }
 246                 s->dcerpc_schannel_auto = false;
 247
 248                 if (lf & NETLOGON_NEG_SUPPORTS_AES)  {
 249                         ln = "aes";
 250                         if (rf & NETLOGON_NEG_SUPPORTS_AES) {
 251                                 composite_error(c, s->a.out.result);
 252                                 return;
 253                         }
 254                 } else if (lf & NETLOGON_NEG_STRONG_KEYS) {
 255                         ln = "strong";
 256                         if (rf & NETLOGON_NEG_STRONG_KEYS) {
 257                                 composite_error(c, s->a.out.result);
 258                                 return;
 259                         }
 260                 } else {
 261                         ln = "des";
 262                 }
 263
 264                 if (rf & NETLOGON_NEG_SUPPORTS_AES)  {
 265                         rn = "aes";
 266                 } else if (rf & NETLOGON_NEG_STRONG_KEYS) {
 267                         rn = "strong";
 268                 } else {
 269                         rn = "des";
 270                 }
 271
 272                 DEBUG(3, ("Server doesn't support %s keys, downgrade to %s"
 273                           "and retry! local[0x%08X] remote[0x%08X]\n",
 274                           ln, rn, lf, rf));
 275
 276                 s->local_negotiate_flags = s->remote_negotiate_flags;
 277
 278                 generate_random_buffer(s->credentials1.data,
 279                                        sizeof(s->credentials1.data));
 280
 281                 subreq = dcerpc_netr_ServerReqChallenge_r_send(s,
 282                                                                c->event_ctx,
 283                                                                s->pipe2->binding_handle,
 284                                                                &s->r);
 285                 if (composite_nomem(subreq, c)) return;
 286
 287                 tevent_req_set_callback(subreq, continue_srv_challenge, c);
 288                 return;
 289         }
 290
 291         s->creds->negotiate_flags = s->remote_negotiate_flags;
 292
 293         /* verify credentials */
 294         if (!netlogon_creds_client_check(s->creds, s->a.out.return_credentials)) {
 295                 composite_error(c, NT_STATUS_UNSUCCESSFUL);
 296                 return;
 297         }
 298
 299         /* setup current netlogon credentials */
 300         cli_credentials_set_netlogon_creds(s->credentials, s->creds);
 301
 302         composite_done(c);
 303 }
 304
 305 /*
 306   Initiate establishing a schannel key using netlogon challenge
 307   on a secondary pipe
 308 */
 309 struct composite_context *dcerpc_schannel_key_send(TALLOC_CTX *mem_ctx,
 310                                                    struct dcerpc_pipe *p,
 311                                                    struct cli_credentials *credentials,
 312                                                    struct loadparm_context *lp_ctx)
 313 {
 314         struct composite_context *c;
 315         struct schannel_key_state *s;
 316         struct composite_context *epm_map_req;
 317         enum netr_SchannelType schannel_type = cli_credentials_get_secure_channel_type(credentials);
 318
 319         /* composite context allocation and setup */
 320         c = composite_create(mem_ctx, p->conn->event_ctx);
 321         if (c == NULL) return NULL;
 322
 323         s = talloc_zero(c, struct schannel_key_state);
 324         if (composite_nomem(s, c)) return c;
 325         c->private_data = s;
 326
 327         /* store parameters in the state structure */
 328         s->pipe        = p;
 329         s->credentials = credentials;
 330         s->local_negotiate_flags = NETLOGON_NEG_AUTH2_FLAGS;
 331
 332         /* allocate credentials */
 333         if (s->pipe->conn->flags & DCERPC_SCHANNEL_128) {
 334                 s->local_negotiate_flags = NETLOGON_NEG_AUTH2_ADS_FLAGS;
 335         }
 336         if (s->pipe->conn->flags & DCERPC_SCHANNEL_AES) {
 337                 s->local_negotiate_flags = NETLOGON_NEG_AUTH2_ADS_FLAGS;
 338                 s->local_negotiate_flags |= NETLOGON_NEG_SUPPORTS_AES;
 339         }
 340         if (s->pipe->conn->flags & DCERPC_SCHANNEL_AUTO) {
 341                 s->local_negotiate_flags = NETLOGON_NEG_AUTH2_ADS_FLAGS;
 342                 s->local_negotiate_flags |= NETLOGON_NEG_SUPPORTS_AES;
 343                 s->dcerpc_schannel_auto = true;
 344         }
 345
 346         /* type of authentication depends on schannel type */
 347         if (schannel_type == SEC_CHAN_RODC) {
 348                 s->local_negotiate_flags |= NETLOGON_NEG_RODC_PASSTHROUGH;
 349         }
 350
 351         /* allocate binding structure */
 352         s->binding = talloc_zero(c, struct dcerpc_binding);
 353         if (composite_nomem(s->binding, c)) return c;
 354
 355         *s->binding = *s->pipe->binding;
 356
 357         /* request the netlogon endpoint mapping */
 358         epm_map_req = dcerpc_epm_map_binding_send(c, s->binding,
 359                                                   &ndr_table_netlogon,
 360                                                   s->pipe->conn->event_ctx,
 361                                                   lp_ctx);
 362         if (composite_nomem(epm_map_req, c)) return c;
 363
 364         composite_continue(c, epm_map_req, continue_epm_map_binding, c);
 365         return c;
 366 }
 367
 368
 369 /*
 370   Receive result of schannel key request
 371  */
 372 NTSTATUS dcerpc_schannel_key_recv(struct composite_context *c)
 373 {
 374         NTSTATUS status = composite_wait(c);
 375
 376         talloc_free(c);
 377         return status;
 378 }
 379
 380
 381 struct auth_schannel_state {
 382         struct dcerpc_pipe *pipe;
 383         struct cli_credentials *credentials;
 384         const struct ndr_interface_table *table;
 385         struct loadparm_context *lp_ctx;
 386         uint8_t auth_level;
 387         struct netlogon_creds_CredentialState *creds_state;
 388         struct netr_Authenticator auth;
 389         struct netr_Authenticator return_auth;
 390         union netr_Capabilities capabilities;
 391         struct netr_LogonGetCapabilities c;
 392 };
 393
 394
 395 static void continue_bind_auth(struct composite_context *ctx);
 396
 397
 398 /*
 399   Stage 2 of auth_schannel: Receive schannel key and intitiate an
 400   authenticated bind using received credentials
 401  */
 402 static void continue_schannel_key(struct composite_context *ctx)
 403 {
 404         struct composite_context *auth_req;
 405         struct composite_context *c = talloc_get_type(ctx->async.private_data,
 406                                                       struct composite_context);
 407         struct auth_schannel_state *s = talloc_get_type(c->private_data,
 408                                                         struct auth_schannel_state);
 409         NTSTATUS status;
 410
 411         /* receive schannel key */
 412         status = c->status = dcerpc_schannel_key_recv(ctx);
 413         if (!composite_is_ok(c)) {
 414                 DEBUG(1, ("Failed to setup credentials: %s\n", nt_errstr(status)));
 415                 return;
 416         }
 417
 418         /* send bind auth request with received creds */
 419         auth_req = dcerpc_bind_auth_send(c, s->pipe, s->table, s->credentials,
 420                                          lpcfg_gensec_settings(c, s->lp_ctx),
 421                                          DCERPC_AUTH_TYPE_SCHANNEL, s->auth_level,
 422                                          NULL);
 423         if (composite_nomem(auth_req, c)) return;
 424
 425         composite_continue(c, auth_req, continue_bind_auth, c);
 426 }
 427
 428
 429 /*
 430   Stage 3 of auth_schannel: Receivce result of authenticated bind
 431   and say if we're done ok.
 432 */
 433 static void continue_bind_auth(struct composite_context *ctx)
 434 {
 435         struct composite_context *c = talloc_get_type(ctx->async.private_data,
 436                                                       struct composite_context);
 437         struct auth_schannel_state *s = talloc_get_type(c->private_data,
 438                                                         struct auth_schannel_state);
 439         struct tevent_req *subreq;
 440
 441         c->status = dcerpc_bind_auth_recv(ctx);
 442         if (!composite_is_ok(c)) return;
 443
 444         /* if we have a AES encrypted connection, verify the capabilities */
 445         if (ndr_syntax_id_equal(&s->table->syntax_id,
 446                                 &ndr_table_netlogon.syntax_id)) {
 447                 ZERO_STRUCT(s->return_auth);
 448
 449                 s->creds_state = cli_credentials_get_netlogon_creds(s->credentials);
 450                 if (composite_nomem(s->creds_state, c)) return;
 451
 452                 netlogon_creds_client_authenticator(s->creds_state, &s->auth);
 453
 454                 s->c.in.server_name = talloc_asprintf(c,
 455                                                       "\\\\%s",
 456                                                       dcerpc_server_name(s->pipe));
 457                 if (composite_nomem(s->c.in.server_name, c)) return;
 458                 s->c.in.computer_name         = cli_credentials_get_workstation(s->credentials);
 459                 s->c.in.credential            = &s->auth;
 460                 s->c.in.return_authenticator  = &s->return_auth;
 461                 s->c.in.query_level           = 1;
 462
 463                 s->c.out.capabilities         = &s->capabilities;
 464                 s->c.out.return_authenticator = &s->return_auth;
 465
 466                 DEBUG(5, ("We established a AES connection, verifying logon "
 467                           "capabilities\n"));
 468
 469                 subreq = dcerpc_netr_LogonGetCapabilities_r_send(s,
 470                                                                  c->event_ctx,
 471                                                                  s->pipe->binding_handle,
 472                                                                  &s->c);
 473                 if (composite_nomem(subreq, c)) return;
 474
 475                 tevent_req_set_callback(subreq, continue_get_capabilities, c);
 476                 return;
 477         }
 478
 479         composite_done(c);
 480 }
 481
 482 /*
 483   Stage 4 of auth_schannel: Get the Logon Capablities and verify them.
 484 */
 485 static void continue_get_capabilities(struct tevent_req *subreq)
 486 {
 487         struct composite_context *c;
 488         struct auth_schannel_state *s;
 489
 490         c = tevent_req_callback_data(subreq, struct composite_context);
 491         s = talloc_get_type(c->private_data, struct auth_schannel_state);
 492
 493         /* receive rpc request result */
 494         c->status = dcerpc_netr_LogonGetCapabilities_r_recv(subreq, s);
 495         TALLOC_FREE(subreq);
 496         if (NT_STATUS_EQUAL(c->status, NT_STATUS_RPC_PROCNUM_OUT_OF_RANGE)) {
 497                 if (s->creds_state->negotiate_flags & NETLOGON_NEG_SUPPORTS_AES) {
 498                         composite_error(c, NT_STATUS_INVALID_NETWORK_RESPONSE);
 499                         return;
 500                 } else {
 501                         /* This is probably NT */
 502                         composite_done(c);
 503                         return;
 504                 }
 505         } else if (!composite_is_ok(c)) {
 506                 return;
 507         }
 508
 509         if (NT_STATUS_EQUAL(s->c.out.result, NT_STATUS_NOT_IMPLEMENTED)) {
 510                 if (s->creds_state->negotiate_flags & NETLOGON_NEG_SUPPORTS_AES) {
 511                         /* This means AES isn't supported. */
 512                         composite_error(c, NT_STATUS_INVALID_NETWORK_RESPONSE);
 513                         return;
 514                 }
 515
 516                 /* This is probably an old Samba version */
 517                 composite_done(c);
 518                 return;
 519         }
 520
 521         /* verify credentials */
 522         if (!netlogon_creds_client_check(s->creds_state,
 523                                          &s->c.out.return_authenticator->cred)) {
 524                 composite_error(c, NT_STATUS_UNSUCCESSFUL);
 525                 return;
 526         }
 527
 528         if (!NT_STATUS_IS_OK(s->c.out.result)) {
 529                 composite_error(c, s->c.out.result);
 530                 return;
 531         }
 532
 533         /* compare capabilities */
 534         if (s->creds_state->negotiate_flags != s->capabilities.server_capabilities) {
 535                 DEBUG(2, ("The client capabilities don't match the server "
 536                           "capabilities: local[0x%08X] remote[0x%08X]\n",
 537                           s->creds_state->negotiate_flags,
 538                           s->capabilities.server_capabilities));
 539                 composite_error(c, NT_STATUS_INVALID_NETWORK_RESPONSE);
 540                 return;
 541         }
 542
 543         /* TODO: Add downgrade dectection. */
 544
 545         composite_done(c);
 546 }
 547
 548
 549 /*
 550   Initiate schannel authentication request
 551 */
 552 struct composite_context *dcerpc_bind_auth_schannel_send(TALLOC_CTX *tmp_ctx,
 553                                                          struct dcerpc_pipe *p,
 554                                                          const struct ndr_interface_table *table,
 555                                                          struct cli_credentials *credentials,
 556                                                          struct loadparm_context *lp_ctx,
 557                                                          uint8_t auth_level)
 558 {
 559         struct composite_context *c;
 560         struct auth_schannel_state *s;
 561         struct composite_context *schan_key_req;
 562
 563         /* composite context allocation and setup */
 564         c = composite_create(tmp_ctx, p->conn->event_ctx);
 565         if (c == NULL) return NULL;
 566
 567         s = talloc_zero(c, struct auth_schannel_state);
 568         if (composite_nomem(s, c)) return c;
 569         c->private_data = s;
 570
 571         /* store parameters in the state structure */
 572         s->pipe        = p;
 573         s->credentials = credentials;
 574         s->table       = table;
 575         s->auth_level  = auth_level;
 576         s->lp_ctx      = lp_ctx;
 577
 578         /* start getting schannel key first */
 579         schan_key_req = dcerpc_schannel_key_send(c, p, credentials, lp_ctx);
 580         if (composite_nomem(schan_key_req, c)) return c;
 581
 582         composite_continue(c, schan_key_req, continue_schannel_key, c);
 583         return c;
 584 }
 585
 586
 587 /*
 588   Receive result of schannel authentication request
 589 */
 590 NTSTATUS dcerpc_bind_auth_schannel_recv(struct composite_context *c)
 591 {
 592         NTSTATUS status = composite_wait(c);
 593
 594         talloc_free(c);
 595         return status;
 596 }
 597
 598
 599 /*
 600   Perform schannel authenticated bind - sync version
 601  */
 602 _PUBLIC_ NTSTATUS dcerpc_bind_auth_schannel(TALLOC_CTX *tmp_ctx,
 603                                    struct dcerpc_pipe *p,
 604                                    const struct ndr_interface_table *table,
 605                                    struct cli_credentials *credentials,
 606                                    struct loadparm_context *lp_ctx,
 607                                    uint8_t auth_level)
 608 {
 609         struct composite_context *c;
 610
 611         c = dcerpc_bind_auth_schannel_send(tmp_ctx, p, table, credentials, lp_ctx,
 612                                            auth_level);
 613         return dcerpc_bind_auth_schannel_recv(c);
 614 }