xref: /illumos-gate/usr/src/lib/smbsrv/libmlsvc/common/netr_auth.c (revision dd72704bd9e794056c558153663c739e2012d721)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
24  * Copyright 2021 Tintri by DDN, Inc. All rights reserved.
25  */
26 
27 /*
28  * NETR challenge/response client functions.
29  *
30  * NT_STATUS_INVALID_PARAMETER
31  * NT_STATUS_NO_TRUST_SAM_ACCOUNT
32  * NT_STATUS_ACCESS_DENIED
33  */
34 
35 #include <stdio.h>
36 #include <stdlib.h>
37 #include <strings.h>
38 #include <unistd.h>
39 #include <ctype.h>
40 #include <security/cryptoki.h>
41 #include <security/pkcs11.h>
42 
43 #include <smbsrv/libsmb.h>
44 #include <smbsrv/libsmbns.h>
45 #include <smbsrv/libmlsvc.h>
46 #include <mlsvc.h>
47 #include <smbsrv/ndl/netlogon.ndl>
48 #include <smbsrv/smbinfo.h>
49 #include <smbsrv/netrauth.h>
50 
51 #define	NETR_SESSKEY_ZEROBUF_SZ		4
52 /* The DES algorithm uses a 56-bit encryption key. */
53 #define	NETR_DESKEY_LEN			7
54 
55 int netr_setup_authenticator(netr_info_t *, struct netr_authenticator *,
56     struct netr_authenticator *);
57 DWORD netr_validate_chain(netr_info_t *, struct netr_authenticator *);
58 
59 static int netr_server_req_challenge(mlsvc_handle_t *, netr_info_t *);
60 static int netr_server_authenticate2(mlsvc_handle_t *, netr_info_t *);
61 static int netr_gen_password(BYTE *, BYTE *, BYTE *);
62 
63 /*
64  * Shared with netr_logon.c
65  */
66 netr_info_t netr_global_info = {
67 	.use_secure_rpc = B_TRUE,
68 	.use_logon_ex = B_TRUE
69 };
70 extern ndr_auth_ctx_t netr_ssp_ctx;
71 
72 /*
73  * These flags control various parts of NetLogon RPC messages.
74  * The default is 0 - setting a bit disables some feature.
75  * They are set in smbd/netlogon_flags in svc:/network/smb/server.
76  * These are set when smbd starts. Changing them requires
77  * restarting smbd.
78  *
79  * These shouldn't be confused with either SamLogonEx's ExtraFlags,
80  * or NetrServerAuthenticate's negotiate_flags.
81  *
82  * DISABLE_SECURE_RPC causes Netlogon to use unauthenticated RPC.
83  * Note that the underlying transport is still authenticated and signed.
84  *
85  * DISABLE_RESP_VERIF instructs RPC authentication to ignore failures
86  * when verifying responses.
87  *
88  * DISABLE_SAMLOGONEX causes Netlogon to always use SamLogon, which
89  * makes use of Netlogon Authenticators.
90  */
91 #define	NETR_CFG_DISABLE_SECURE_RPC	0x00000001
92 #define	NETR_CFG_DISABLE_RESP_VERIF	0x00000002
93 #define	NETR_CFG_DISABLE_SAMLOGONEX	0x00000004
94 
95 void
96 netlogon_init_global(uint32_t flags)
97 {
98 	netr_global_info.use_secure_rpc =
99 	    ((flags & NETR_CFG_DISABLE_SECURE_RPC) == 0);
100 	netr_ssp_ctx.auth_verify_resp =
101 	    ((flags & NETR_CFG_DISABLE_RESP_VERIF) == 0);
102 	netr_global_info.use_logon_ex =
103 	    ((flags & NETR_CFG_DISABLE_SAMLOGONEX) == 0);
104 }
105 
106 /*
107  * AES-CFB8 has the odd property that 1/256 keys will encrypt
108  * a full block of 0s to all 0s. In order to mitigate this, Windows DCs
109  * now reject Challenges and Credentials where "none of the first 5 bytes
110  * are unique" (i.e. [MS-NRPC] 3.1.4.1 "Session-Key Negotiation" Step 7).
111  * This detects that condition so that we can avoid having our connection
112  * rejected unexpectedly.
113  *
114  * I've interpreted this condition as 'amongst the first 5 bytes,
115  * at least one must appear exactly once'.
116  *
117  * NOTE: Win2012r2 seems to only reject challenges whose first 5 bytes are 0.
118  */
119 boolean_t
120 passes_dc_mitigation(uint8_t *buf)
121 {
122 	int i, j;
123 
124 	for (i = 0; i < 5; i++) {
125 		for (j = 0; j < 5; j++) {
126 			if (i != j && buf[i] == buf[j])
127 				break;
128 		}
129 
130 		/* if this byte didn't match any other byte, this passes */
131 		if (j == 5)
132 			return (B_TRUE);
133 	}
134 
135 	/* None of the bytes were unique - the check fails */
136 	return (B_FALSE);
137 }
138 
139 /*
140  * netlogon_auth
141  *
142  * This is the core of the NETLOGON authentication protocol.
143  * Do the challenge response authentication.
144  *
145  * Prior to calling this function, an anonymous session to the NETLOGON
146  * pipe on a domain controller(server) should have already been opened.
147  *
148  * Upon a successful NETLOGON credential chain establishment, the
149  * netlogon sequence number will be set to match the kpasswd sequence
150  * number.
151  *
152  */
153 DWORD
154 netlogon_auth(char *server, char *domain, DWORD flags)
155 {
156 	mlsvc_handle_t netr_handle;
157 	netr_info_t *netr_info;
158 	int rc;
159 	DWORD leout_rc[2];
160 	boolean_t retry;
161 	DWORD status;
162 
163 	/*
164 	 * [MS-NRPC] 3.1.4.1 "Session-Key Negotiation"
165 	 * Negotiation happens on an 'unprotected RPC channel'
166 	 * (no RPC-level auth).
167 	 */
168 	status = netr_open(server, domain, &netr_handle);
169 
170 	if (status != 0) {
171 		syslog(LOG_ERR, "netlogon_auth remote open failed (%s)",
172 		    xlate_nt_status(status));
173 		return (status);
174 	}
175 
176 	netr_info = &netr_global_info;
177 	bzero(&netr_info->session_key, sizeof (netr_info->session_key));
178 	netr_info->flags = flags;
179 
180 	rc = smb_getnetbiosname(netr_info->hostname, NETBIOS_NAME_SZ);
181 	if (rc != 0)
182 		goto errout;
183 
184 	/* server is our DC.  Note: normally an FQDN. */
185 	(void) snprintf(netr_info->server, sizeof (netr_info->server),
186 	    "\\\\%s", server);
187 
188 	/*
189 	 * Domain (FQDN and NetBIOS) Name needed for Netlogon SSP-based
190 	 * Secure RPC.
191 	 */
192 	rc = smb_getdomainname(netr_info->nb_domain,
193 	    sizeof (netr_info->nb_domain));
194 	if (rc != 0)
195 		goto errout;
196 
197 	rc = smb_getfqdomainname(netr_info->fqdn_domain,
198 	    sizeof (netr_info->fqdn_domain));
199 	if (rc != 0)
200 		goto errout;
201 
202 	/*
203 	 * [MS-NRPC] 3.1.4.1 "Session-Key Negotiation" Step 7
204 	 * Windows DCs will reject negotiate attempts if none of the first
205 	 * 5 bytes of the Challenge are unique.
206 	 * Keep retrying until we've generated one that satisfies this.
207 	 */
208 	do {
209 		retry = B_FALSE;
210 		LE_OUT32(&leout_rc[0], arc4random());
211 		LE_OUT32(&leout_rc[1], arc4random());
212 		(void) memcpy(&netr_info->client_challenge, leout_rc,
213 		    sizeof (struct netr_credential));
214 
215 		if (!passes_dc_mitigation(netr_info->client_challenge.data))
216 			retry = B_TRUE;
217 	} while (retry);
218 
219 	if ((rc = netr_server_req_challenge(&netr_handle, netr_info)) == 0) {
220 		rc = netr_server_authenticate2(&netr_handle, netr_info);
221 		if (rc == 0) {
222 			/*
223 			 * TODO: (later)  When joining a domain using a
224 			 * pre-created machine account, should do:
225 			 * netr_server_password_set(&netr_handle, netr_info);
226 			 * Nexenta issue 11960
227 			 */
228 			smb_update_netlogon_seqnum();
229 			netr_info->flags |= NETR_FLG_VALID;
230 
231 		}
232 	}
233 
234 errout:
235 	(void) netr_close(&netr_handle);
236 
237 	return ((rc) ? NT_STATUS_UNSUCCESSFUL : NT_STATUS_SUCCESS);
238 }
239 
240 /*
241  * netr_open
242  *
243  * Open an anonymous session to the NETLOGON pipe on a domain controller
244  * and bind to the NETR RPC interface.
245  *
246  * We store the remote server information, which is used to drive Windows
247  * version specific behavior.
248  *
249  * Returns 0 or NT status
250  */
251 DWORD
252 netr_open(char *server, char *domain, mlsvc_handle_t *netr_handle)
253 {
254 	char user[SMB_USERNAME_MAXLEN];
255 	DWORD status;
256 
257 	smb_ipc_get_user(user, SMB_USERNAME_MAXLEN);
258 
259 	status = ndr_rpc_bind(netr_handle, server, domain, user, "NETR");
260 
261 	return (status);
262 }
263 
264 uint32_t auth_context_id = 1;
265 
266 DWORD
267 netr_open_secure(char *server, char *domain, mlsvc_handle_t *netr_handle)
268 {
269 	char user[SMB_USERNAME_MAXLEN];
270 	DWORD status;
271 
272 	smb_ipc_get_user(user, SMB_USERNAME_MAXLEN);
273 
274 	/*
275 	 * If the server doesn't support SECURE_RPC_FLAG, or we've disabled
276 	 * secure rpc (netr_global_info.use_secure_rpc), then SECURE_RPC_FLAG
277 	 * won't be in the set of negotiated flags. Don't use SecureRPC if
278 	 * that's the case.
279 	 */
280 	if ((netr_global_info.nego_flags & NETR_NEGO_SECURE_RPC_FLAG) != 0) {
281 		netr_ssp_ctx.auth_context_id = auth_context_id++;
282 		status = ndr_rpc_bind_secure(netr_handle, server, domain, user,
283 		    "NETR", &netr_ssp_ctx);
284 	} else {
285 		status = ndr_rpc_bind(netr_handle, server, domain, user,
286 		    "NETR");
287 	}
288 
289 	return (status);
290 }
291 
292 /*
293  * netr_close
294  *
295  * Close a NETLOGON pipe and free the RPC context.
296  */
297 int
298 netr_close(mlsvc_handle_t *netr_handle)
299 {
300 	ndr_rpc_unbind(netr_handle);
301 	return (0);
302 }
303 
304 /*
305  * netr_server_req_challenge
306  */
307 static int
308 netr_server_req_challenge(mlsvc_handle_t *netr_handle, netr_info_t *netr_info)
309 {
310 	struct netr_ServerReqChallenge arg;
311 	int opnum;
312 
313 	bzero(&arg, sizeof (struct netr_ServerReqChallenge));
314 	opnum = NETR_OPNUM_ServerReqChallenge;
315 
316 	arg.servername = (unsigned char *)netr_info->server;
317 	arg.hostname = (unsigned char *)netr_info->hostname;
318 
319 	(void) memcpy(&arg.client_challenge, &netr_info->client_challenge,
320 	    sizeof (struct netr_credential));
321 
322 	if (ndr_rpc_call(netr_handle, opnum, &arg) != 0)
323 		return (-1);
324 
325 	if (arg.status != 0) {
326 		ndr_rpc_status(netr_handle, opnum, arg.status);
327 		ndr_rpc_release(netr_handle);
328 		return (-1);
329 	}
330 
331 	(void) memcpy(&netr_info->server_challenge, &arg.server_challenge,
332 	    sizeof (struct netr_credential));
333 
334 	ndr_rpc_release(netr_handle);
335 	return (0);
336 }
337 
338 uint32_t netr_server_auth2_flags =
339     NETR_NEGO_BASE_FLAGS |
340     NETR_NEGO_STRONGKEY_FLAG |
341     NETR_NEGO_SECURE_RPC_FLAG;
342 
343 /*
344  * netr_server_authenticate2
345  */
346 static int
347 netr_server_authenticate2(mlsvc_handle_t *netr_handle, netr_info_t *netr_info)
348 {
349 	struct netr_ServerAuthenticate2 arg;
350 	/* sizeof netr_info->hostname, + 1 for the '$' */
351 	char account_name[(NETBIOS_NAME_SZ * 2) + 1];
352 	int opnum;
353 	int rc;
354 
355 	bzero(&arg, sizeof (struct netr_ServerAuthenticate2));
356 	opnum = NETR_OPNUM_ServerAuthenticate2;
357 
358 	(void) snprintf(account_name, sizeof (account_name), "%s$",
359 	    netr_info->hostname);
360 
361 	smb_tracef("server=[%s] account_name=[%s] hostname=[%s]\n",
362 	    netr_info->server, account_name, netr_info->hostname);
363 
364 	arg.servername = (unsigned char *)netr_info->server;
365 	arg.account_name = (unsigned char *)account_name;
366 	arg.account_type = NETR_WKSTA_TRUST_ACCOUNT_TYPE;
367 	arg.hostname = (unsigned char *)netr_info->hostname;
368 	arg.negotiate_flags = netr_server_auth2_flags;
369 
370 	/*
371 	 * If we've disabled SecureRPC, remove it from our negotiate_flags
372 	 * so that the returned flags don't include it. We won't later use
373 	 * SecureRPC if the returned flags don't include the flag.
374 	 */
375 	if (!netr_global_info.use_secure_rpc)
376 		arg.negotiate_flags &= ~NETR_NEGO_SECURE_RPC_FLAG;
377 
378 	if (arg.negotiate_flags & NETR_NEGO_STRONGKEY_FLAG) {
379 		if (netr_gen_skey128(netr_info) != SMBAUTH_SUCCESS)
380 			return (-1);
381 	} else {
382 		if (netr_gen_skey64(netr_info) != SMBAUTH_SUCCESS)
383 			return (-1);
384 	}
385 
386 	/*
387 	 * We can't 'fiddle' with anything here to prevent getting bitten by
388 	 * ClientStoredCredential-based mitigations.
389 	 *
390 	 * If we're using SamLogonEx, we won't use authenticators unless
391 	 * some other NetLogon command is implemented and used.
392 	 */
393 	if (netr_gen_credentials(netr_info->session_key.key,
394 	    &netr_info->client_challenge, 0,
395 	    &netr_info->client_credential, B_FALSE) != SMBAUTH_SUCCESS) {
396 		return (-1);
397 	}
398 
399 	if (netr_gen_credentials(netr_info->session_key.key,
400 	    &netr_info->server_challenge, 0,
401 	    &netr_info->server_credential, B_FALSE) != SMBAUTH_SUCCESS) {
402 		return (-1);
403 	}
404 
405 	(void) memcpy(&arg.client_credential, &netr_info->client_credential,
406 	    sizeof (struct netr_credential));
407 
408 	if (ndr_rpc_call(netr_handle, opnum, &arg) != 0)
409 		return (-1);
410 
411 	if (arg.status != 0) {
412 		ndr_rpc_status(netr_handle, opnum, arg.status);
413 		ndr_rpc_release(netr_handle);
414 		return (-1);
415 	}
416 
417 	/* The server returns the intersection of our flags and their flags. */
418 	netr_info->nego_flags = arg.negotiate_flags;
419 
420 	rc = memcmp(&netr_info->server_credential, &arg.server_credential,
421 	    sizeof (struct netr_credential));
422 
423 	ndr_rpc_release(netr_handle);
424 	return (rc);
425 }
426 
427 /*
428  * netr_gen_skey128
429  *
430  * Generate a 128-bit session key from the client and server challenges.
431  * See "Session-Key Computation" section of MS-NRPC document.
432  */
433 int
434 netr_gen_skey128(netr_info_t *netr_info)
435 {
436 	unsigned char ntlmhash[SMBAUTH_HASH_SZ];
437 	int rc = SMBAUTH_FAILURE;
438 	CK_RV rv;
439 	CK_MECHANISM mechanism;
440 	CK_SESSION_HANDLE hSession;
441 	CK_ULONG diglen = MD_DIGEST_LEN;
442 	unsigned char md5digest[MD_DIGEST_LEN];
443 	unsigned char zerobuf[NETR_SESSKEY_ZEROBUF_SZ];
444 
445 	bzero(ntlmhash, SMBAUTH_HASH_SZ);
446 	/*
447 	 * We should check (netr_info->flags & NETR_FLG_INIT) and use
448 	 * the appropriate password but it isn't working yet.  So we
449 	 * always use the default one for now.
450 	 */
451 	bzero(netr_info->password, sizeof (netr_info->password));
452 	rc = smb_config_getstr(SMB_CI_MACHINE_PASSWD,
453 	    (char *)netr_info->password, sizeof (netr_info->password));
454 
455 	if ((rc != SMBD_SMF_OK) || *netr_info->password == '\0') {
456 		return (SMBAUTH_FAILURE);
457 	}
458 
459 	rc = smb_auth_ntlm_hash((char *)netr_info->password, ntlmhash);
460 	if (rc != SMBAUTH_SUCCESS) {
461 		explicit_bzero(&netr_info->password,
462 		    sizeof (netr_info->password));
463 		return (SMBAUTH_FAILURE);
464 	}
465 
466 	bzero(zerobuf, NETR_SESSKEY_ZEROBUF_SZ);
467 
468 	mechanism.mechanism = CKM_MD5;
469 	mechanism.pParameter = 0;
470 	mechanism.ulParameterLen = 0;
471 
472 	rv = SUNW_C_GetMechSession(mechanism.mechanism, &hSession);
473 	if (rv != CKR_OK) {
474 		rc = SMBAUTH_FAILURE;
475 		goto errout;
476 	}
477 
478 	rv = C_DigestInit(hSession, &mechanism);
479 	if (rv != CKR_OK)
480 		goto cleanup;
481 
482 	rv = C_DigestUpdate(hSession, (CK_BYTE_PTR)zerobuf,
483 	    NETR_SESSKEY_ZEROBUF_SZ);
484 	if (rv != CKR_OK)
485 		goto cleanup;
486 
487 	rv = C_DigestUpdate(hSession,
488 	    (CK_BYTE_PTR)netr_info->client_challenge.data, NETR_CRED_DATA_SZ);
489 	if (rv != CKR_OK)
490 		goto cleanup;
491 
492 	rv = C_DigestUpdate(hSession,
493 	    (CK_BYTE_PTR)netr_info->server_challenge.data, NETR_CRED_DATA_SZ);
494 	if (rv != CKR_OK)
495 		goto cleanup;
496 
497 	rv = C_DigestFinal(hSession, (CK_BYTE_PTR)md5digest, &diglen);
498 	if (rv != CKR_OK)
499 		goto cleanup;
500 
501 	rc = smb_auth_hmac_md5(md5digest, diglen, ntlmhash, SMBAUTH_HASH_SZ,
502 	    netr_info->session_key.key);
503 
504 	netr_info->session_key.len = NETR_SESSKEY128_SZ;
505 cleanup:
506 	(void) C_CloseSession(hSession);
507 
508 errout:
509 	explicit_bzero(&netr_info->password, sizeof (netr_info->password));
510 	explicit_bzero(ntlmhash, sizeof (ntlmhash));
511 
512 	return (rc);
513 
514 }
515 /*
516  * netr_gen_skey64
517  *
518  * Generate a 64-bit session key from the client and server challenges.
519  * See "Session-Key Computation" section of MS-NRPC document.
520  *
521  * The algorithm is a two stage hash. For the first hash, the input is
522  * the combination of the client and server challenges, the key is
523  * the first 7 bytes of the password. The initial password is formed
524  * using the NT password hash on the local hostname in lower case.
525  * The result is stored in a temporary buffer.
526  *
527  *		input:	challenge
528  *		key:	passwd lower 7 bytes
529  *		output:	intermediate result
530  *
531  * For the second hash, the input is the result of the first hash and
532  * the key is the last 7 bytes of the password.
533  *
534  *		input:	result of first hash
535  *		key:	passwd upper 7 bytes
536  *		output:	session_key
537  *
538  * The final output should be the session key.
539  *
540  *		FYI: smb_auth_DES(output, key, input)
541  *
542  * If any difficulties occur using the cryptographic framework, the
543  * function returns SMBAUTH_FAILURE.  Otherwise SMBAUTH_SUCCESS is
544  * returned.
545  */
546 int
547 netr_gen_skey64(netr_info_t *netr_info)
548 {
549 	unsigned char md4hash[32];
550 	unsigned char buffer[8];
551 	DWORD data[2];
552 	DWORD *client_challenge;
553 	DWORD *server_challenge;
554 	int rc;
555 	DWORD le_data[2];
556 
557 	client_challenge = (DWORD *)(uintptr_t)&netr_info->client_challenge;
558 	server_challenge = (DWORD *)(uintptr_t)&netr_info->server_challenge;
559 	bzero(md4hash, 32);
560 
561 	/*
562 	 * We should check (netr_info->flags & NETR_FLG_INIT) and use
563 	 * the appropriate password but it isn't working yet.  So we
564 	 * always use the default one for now.
565 	 */
566 	bzero(netr_info->password, sizeof (netr_info->password));
567 	rc = smb_config_getstr(SMB_CI_MACHINE_PASSWD,
568 	    (char *)netr_info->password, sizeof (netr_info->password));
569 
570 	if ((rc != SMBD_SMF_OK) || *netr_info->password == '\0') {
571 		return (SMBAUTH_FAILURE);
572 	}
573 
574 	rc = smb_auth_ntlm_hash((char *)netr_info->password, md4hash);
575 
576 	if (rc != SMBAUTH_SUCCESS) {
577 		rc = SMBAUTH_FAILURE;
578 		goto out;
579 	}
580 
581 	data[0] = LE_IN32(&client_challenge[0]) + LE_IN32(&server_challenge[0]);
582 	data[1] = LE_IN32(&client_challenge[1]) + LE_IN32(&server_challenge[1]);
583 	LE_OUT32(&le_data[0], data[0]);
584 	LE_OUT32(&le_data[1], data[1]);
585 	rc = smb_auth_DES(buffer, 8, md4hash, NETR_DESKEY_LEN,
586 	    (unsigned char *)le_data, 8);
587 
588 	if (rc != SMBAUTH_SUCCESS)
589 		goto out;
590 
591 	netr_info->session_key.len = NETR_SESSKEY64_SZ;
592 	rc = smb_auth_DES(netr_info->session_key.key,
593 	    netr_info->session_key.len, &md4hash[9], NETR_DESKEY_LEN, buffer,
594 	    8);
595 
596 out:
597 	explicit_bzero(&netr_info->password, sizeof (netr_info->password));
598 	explicit_bzero(md4hash, sizeof (md4hash));
599 	explicit_bzero(buffer, sizeof (buffer));
600 	return (rc);
601 }
602 
603 /*
604  * netr_gen_credentials
605  *
606  * Generate a set of credentials from a challenge and a session key.
607  * The algorithm is a two stage hash. For the first hash, the
608  * timestamp is added to the challenge and the result is stored in a
609  * temporary buffer:
610  *
611  *		input:	challenge (including timestamp)
612  *		key:	session_key
613  *		output:	intermediate result
614  *
615  * For the second hash, the input is the result of the first hash and
616  * a strange partial key is used:
617  *
618  *		input:	result of first hash
619  *		key:	funny partial key
620  *		output:	credentiails
621  *
622  * The final output should be an encrypted set of credentials.
623  *
624  *		FYI: smb_auth_DES(output, key, input)
625  *
626  * If any difficulties occur using the cryptographic framework, the
627  * function returns SMBAUTH_FAILURE.  Otherwise SMBAUTH_SUCCESS is
628  * returned.
629  */
630 int
631 netr_gen_credentials(BYTE *session_key, netr_cred_t *challenge,
632     DWORD timestamp, netr_cred_t *out_cred, boolean_t retry)
633 {
634 	unsigned char buffer[8];
635 	DWORD data[2];
636 	DWORD le_data[2];
637 	DWORD *p;
638 	int rc;
639 
640 	p = (DWORD *)(uintptr_t)challenge;
641 	data[0] = LE_IN32(&p[0]) + timestamp;
642 	data[1] = LE_IN32(&p[1]);
643 
644 	LE_OUT32(&le_data[0], data[0]);
645 	LE_OUT32(&le_data[1], data[1]);
646 
647 	if (smb_auth_DES(buffer, 8, session_key, NETR_DESKEY_LEN,
648 	    (unsigned char *)le_data, 8) != SMBAUTH_SUCCESS)
649 		return (SMBAUTH_FAILURE);
650 
651 	rc = smb_auth_DES(out_cred->data, 8, &session_key[NETR_DESKEY_LEN],
652 	    NETR_DESKEY_LEN, buffer, 8);
653 
654 	/*
655 	 * [MS-NRPC] 3.1.4.6 "Calling Methods Requiring Session-Key
656 	 * Establishment" Step 6
657 	 *
658 	 * Windows DCs will reject authenticators if none of the first
659 	 * 5 bytes of the ClientStoredCredential are unique.
660 	 * Keep retrying until we've generated one that satisfies this,
661 	 * but only if the caller can handle retries.
662 	 */
663 	if (retry && !passes_dc_mitigation(out_cred->data))
664 		return (SMBAUTH_RETRY);
665 
666 	return (rc);
667 }
668 
669 /*
670  * netr_server_password_set
671  *
672  * Attempt to change the trust account password for this system.
673  *
674  * Note that this call may legitimately fail if the registry on the
675  * domain controller has been setup to deny attempts to change the
676  * trust account password. In this case we should just continue to
677  * use the original password.
678  *
679  * Possible status values:
680  *	NT_STATUS_ACCESS_DENIED
681  */
682 int
683 netr_server_password_set(mlsvc_handle_t *netr_handle, netr_info_t *netr_info)
684 {
685 	struct netr_PasswordSet  arg;
686 	int opnum;
687 	BYTE new_password[NETR_OWF_PASSWORD_SZ];
688 	char account_name[NETBIOS_NAME_SZ * 2];
689 
690 	bzero(&arg, sizeof (struct netr_PasswordSet));
691 	opnum = NETR_OPNUM_ServerPasswordSet;
692 
693 	(void) snprintf(account_name, sizeof (account_name), "%s$",
694 	    netr_info->hostname);
695 
696 	arg.servername = (unsigned char *)netr_info->server;
697 	arg.account_name = (unsigned char *)account_name;
698 	arg.sec_chan_type = NETR_WKSTA_TRUST_ACCOUNT_TYPE;
699 	arg.hostname = (unsigned char *)netr_info->hostname;
700 
701 	/*
702 	 * Set up the client side authenticator.
703 	 */
704 	if (netr_setup_authenticator(netr_info, &arg.auth, 0) !=
705 	    SMBAUTH_SUCCESS) {
706 		return (-1);
707 	}
708 
709 	/*
710 	 * Generate a new password from the old password.
711 	 */
712 	if (netr_gen_password(netr_info->session_key.key,
713 	    netr_info->password, new_password) == SMBAUTH_FAILURE) {
714 		return (-1);
715 	}
716 
717 	(void) memcpy(&arg.owf_password, &new_password,
718 	    NETR_OWF_PASSWORD_SZ);
719 
720 	if (ndr_rpc_call(netr_handle, opnum, &arg) != 0)
721 		return (-1);
722 
723 	if (arg.status != 0) {
724 		ndr_rpc_status(netr_handle, opnum, arg.status);
725 		ndr_rpc_release(netr_handle);
726 		return (-1);
727 	}
728 
729 	/*
730 	 * Check the returned credentials.  The server returns the new
731 	 * client credential rather than the new server credentiali,
732 	 * as documented elsewhere.
733 	 *
734 	 * Generate the new seed for the credential chain.  Increment
735 	 * the timestamp and add it to the client challenge.  Then we
736 	 * need to copy the challenge to the credential field in
737 	 * preparation for the next cycle.
738 	 */
739 	if (netr_validate_chain(netr_info, &arg.auth) == 0) {
740 		/*
741 		 * Save the new password.
742 		 */
743 		(void) memcpy(netr_info->password, new_password,
744 		    NETR_OWF_PASSWORD_SZ);
745 	}
746 
747 	ndr_rpc_release(netr_handle);
748 	return (0);
749 }
750 
751 /*
752  * netr_gen_password
753  *
754  * Generate a new pasword from the old password  and the session key.
755  * The algorithm is a two stage hash. The session key is used in the
756  * first hash but only part of the session key is used in the second
757  * hash.
758  *
759  * If any difficulties occur using the cryptographic framework, the
760  * function returns SMBAUTH_FAILURE.  Otherwise SMBAUTH_SUCCESS is
761  * returned.
762  */
763 static int
764 netr_gen_password(BYTE *session_key, BYTE *old_password, BYTE *new_password)
765 {
766 	int rv;
767 
768 	rv = smb_auth_DES(new_password, 8, session_key, NETR_DESKEY_LEN,
769 	    old_password, 8);
770 	if (rv != SMBAUTH_SUCCESS)
771 		return (rv);
772 
773 	rv = smb_auth_DES(&new_password[8], 8, &session_key[NETR_DESKEY_LEN],
774 	    NETR_DESKEY_LEN, &old_password[8], 8);
775 	return (rv);
776 }
777 
778 /*
779  * Todo: need netr_server_password_set2()
780  * used by "unsecure join". (NX 11960)
781  */
782