source: branches/samba-3.2.x/source/libads/kerberos_verify.c

Last change on this file was 133, checked in by Paul Smedley, 17 years ago

Update trunk to 3.2.0pre3
File size: 15.8 KB
Line 
1/*
2 Unix SMB/CIFS implementation.
3 kerberos utility library
4 Copyright (C) Andrew Tridgell 2001
5 Copyright (C) Remus Koos 2001
6 Copyright (C) Luke Howard 2003
7 Copyright (C) Guenther Deschner 2003, 2005
8 Copyright (C) Jim McDonough (jmcd@us.ibm.com) 2003
9 Copyright (C) Andrew Bartlett <abartlet@samba.org> 2004-2005
10 Copyright (C) Jeremy Allison 2007
11
12 This program is free software; you can redistribute it and/or modify
13 it under the terms of the GNU General Public License as published by
14 the Free Software Foundation; either version 3 of the License, or
15 (at your option) any later version.
16
17 This program is distributed in the hope that it will be useful,
18 but WITHOUT ANY WARRANTY; without even the implied warranty of
19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 GNU General Public License for more details.
21
22 You should have received a copy of the GNU General Public License
23 along with this program. If not, see <http://www.gnu.org/licenses/>.
24*/
25
26#include "includes.h"
27
28#ifdef HAVE_KRB5
29
30#if !defined(HAVE_KRB5_PRINC_COMPONENT)
31const krb5_data *krb5_princ_component(krb5_context, krb5_principal, int );
32#endif
33
34/**********************************************************************************
35 Try to verify a ticket using the system keytab... the system keytab has kvno -1 entries, so
36 it's more like what microsoft does... see comment in utils/net_ads.c in the
37 ads_keytab_add_entry function for details.
38***********************************************************************************/
39
40static bool ads_keytab_verify_ticket(krb5_context context,
41 krb5_auth_context auth_context,
42 const DATA_BLOB *ticket,
43 krb5_ticket **pp_tkt,
44 krb5_keyblock **keyblock,
45 krb5_error_code *perr)
46{
47 krb5_error_code ret = 0;
48 bool auth_ok = False;
49 krb5_keytab keytab = NULL;
50 krb5_kt_cursor kt_cursor;
51 krb5_keytab_entry kt_entry;
52 char *valid_princ_formats[7] = { NULL, NULL, NULL, NULL, NULL, NULL, NULL };
53 char *entry_princ_s = NULL;
54 fstring my_name, my_fqdn;
55 int i;
56 int number_matched_principals = 0;
57 krb5_data packet;
58
59 *pp_tkt = NULL;
60 *keyblock = NULL;
61 *perr = 0;
62
63 /* Generate the list of principal names which we expect
64 * clients might want to use for authenticating to the file
65 * service. We allow name$,{host,cifs}/{name,fqdn,name.REALM}. */
66
67 fstrcpy(my_name, global_myname());
68
69 my_fqdn[0] = '\0';
70 name_to_fqdn(my_fqdn, global_myname());
71
72 asprintf(&valid_princ_formats[0], "%s$@%s", my_name, lp_realm());
73 asprintf(&valid_princ_formats[1], "host/%s@%s", my_name, lp_realm());
74 asprintf(&valid_princ_formats[2], "host/%s@%s", my_fqdn, lp_realm());
75 asprintf(&valid_princ_formats[3], "host/%s.%s@%s", my_name, lp_realm(), lp_realm());
76 asprintf(&valid_princ_formats[4], "cifs/%s@%s", my_name, lp_realm());
77 asprintf(&valid_princ_formats[5], "cifs/%s@%s", my_fqdn, lp_realm());
78 asprintf(&valid_princ_formats[6], "cifs/%s.%s@%s", my_name, lp_realm(), lp_realm());
79
80 ZERO_STRUCT(kt_entry);
81 ZERO_STRUCT(kt_cursor);
82
83 ret = smb_krb5_open_keytab(context, NULL, False, &keytab);
84 if (ret) {
85 DEBUG(1, ("ads_keytab_verify_ticket: smb_krb5_open_keytab failed (%s)\n", error_message(ret)));
86 goto out;
87 }
88
89 /* Iterate through the keytab. For each key, if the principal
90 * name case-insensitively matches one of the allowed formats,
91 * try verifying the ticket using that principal. */
92
93 ret = krb5_kt_start_seq_get(context, keytab, &kt_cursor);
94 if (ret) {
95 DEBUG(1, ("ads_keytab_verify_ticket: krb5_kt_start_seq_get failed (%s)\n", error_message(ret)));
96 goto out;
97 }
98
99 while (!auth_ok && (krb5_kt_next_entry(context, keytab, &kt_entry, &kt_cursor) == 0)) {
100 ret = smb_krb5_unparse_name(context, kt_entry.principal, &entry_princ_s);
101 if (ret) {
102 DEBUG(1, ("ads_keytab_verify_ticket: smb_krb5_unparse_name failed (%s)\n",
103 error_message(ret)));
104 goto out;
105 }
106
107 for (i = 0; i < ARRAY_SIZE(valid_princ_formats); i++) {
108
109 if (!strequal(entry_princ_s, valid_princ_formats[i])) {
110 continue;
111 }
112
113 number_matched_principals++;
114 packet.length = ticket->length;
115 packet.data = (char *)ticket->data;
116 *pp_tkt = NULL;
117
118 ret = krb5_rd_req_return_keyblock_from_keytab(context, &auth_context, &packet,
119 kt_entry.principal, keytab,
120 NULL, pp_tkt, keyblock);
121
122 if (ret) {
123 DEBUG(10,("ads_keytab_verify_ticket: "
124 "krb5_rd_req_return_keyblock_from_keytab(%s) failed: %s\n",
125 entry_princ_s, error_message(ret)));
126
127 /* workaround for MIT:
128 * as krb5_ktfile_get_entry will explicitly
129 * close the krb5_keytab as soon as krb5_rd_req
130 * has successfully decrypted the ticket but the
131 * ticket is not valid yet (due to clockskew)
132 * there is no point in querying more keytab
133 * entries - Guenther */
134
135 if (ret == KRB5KRB_AP_ERR_TKT_NYV ||
136 ret == KRB5KRB_AP_ERR_TKT_EXPIRED ||
137 ret == KRB5KRB_AP_ERR_SKEW) {
138 break;
139 }
140 } else {
141 DEBUG(3,("ads_keytab_verify_ticket: "
142 "krb5_rd_req_return_keyblock_from_keytab succeeded for principal %s\n",
143 entry_princ_s));
144 auth_ok = True;
145 break;
146 }
147 }
148
149 /* Free the name we parsed. */
150 SAFE_FREE(entry_princ_s);
151
152 /* Free the entry we just read. */
153 smb_krb5_kt_free_entry(context, &kt_entry);
154 ZERO_STRUCT(kt_entry);
155 }
156 krb5_kt_end_seq_get(context, keytab, &kt_cursor);
157
158 ZERO_STRUCT(kt_cursor);
159
160 out:
161
162 for (i = 0; i < ARRAY_SIZE(valid_princ_formats); i++) {
163 SAFE_FREE(valid_princ_formats[i]);
164 }
165
166 if (!auth_ok) {
167 if (!number_matched_principals) {
168 DEBUG(3, ("ads_keytab_verify_ticket: no keytab principals matched expected file service name.\n"));
169 } else {
170 DEBUG(3, ("ads_keytab_verify_ticket: krb5_rd_req failed for all %d matched keytab principals\n",
171 number_matched_principals));
172 }
173 }
174
175 SAFE_FREE(entry_princ_s);
176
177 {
178 krb5_keytab_entry zero_kt_entry;
179 ZERO_STRUCT(zero_kt_entry);
180 if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
181 smb_krb5_kt_free_entry(context, &kt_entry);
182 }
183 }
184
185 {
186 krb5_kt_cursor zero_csr;
187 ZERO_STRUCT(zero_csr);
188 if ((memcmp(&kt_cursor, &zero_csr, sizeof(krb5_kt_cursor)) != 0) && keytab) {
189 krb5_kt_end_seq_get(context, keytab, &kt_cursor);
190 }
191 }
192
193 if (keytab) {
194 krb5_kt_close(context, keytab);
195 }
196 *perr = ret;
197 return auth_ok;
198}
199
200/**********************************************************************************
201 Try to verify a ticket using the secrets.tdb.
202***********************************************************************************/
203
204static krb5_error_code ads_secrets_verify_ticket(krb5_context context,
205 krb5_auth_context auth_context,
206 krb5_principal host_princ,
207 const DATA_BLOB *ticket,
208 krb5_ticket **pp_tkt,
209 krb5_keyblock **keyblock,
210 krb5_error_code *perr)
211{
212 krb5_error_code ret = 0;
213 bool auth_ok = False;
214 char *password_s = NULL;
215 krb5_data password;
216 krb5_enctype enctypes[] = {
217#if defined(ENCTYPE_ARCFOUR_HMAC)
218 ENCTYPE_ARCFOUR_HMAC,
219#endif
220 ENCTYPE_DES_CBC_CRC,
221 ENCTYPE_DES_CBC_MD5,
222 ENCTYPE_NULL
223 };
224 krb5_data packet;
225 int i;
226
227 *pp_tkt = NULL;
228 *keyblock = NULL;
229 *perr = 0;
230
231
232 if (!secrets_init()) {
233 DEBUG(1,("ads_secrets_verify_ticket: secrets_init failed\n"));
234 *perr = KRB5_CONFIG_CANTOPEN;
235 return False;
236 }
237
238 password_s = secrets_fetch_machine_password(lp_workgroup(), NULL, NULL);
239 if (!password_s) {
240 DEBUG(1,("ads_secrets_verify_ticket: failed to fetch machine password\n"));
241 *perr = KRB5_LIBOS_CANTREADPWD;
242 return False;
243 }
244
245 password.data = password_s;
246 password.length = strlen(password_s);
247
248 /* CIFS doesn't use addresses in tickets. This would break NAT. JRA */
249
250 packet.length = ticket->length;
251 packet.data = (char *)ticket->data;
252
253 /* We need to setup a auth context with each possible encoding type in turn. */
254 for (i=0;enctypes[i];i++) {
255 krb5_keyblock *key = NULL;
256
257 if (!(key = SMB_MALLOC_P(krb5_keyblock))) {
258 ret = ENOMEM;
259 goto out;
260 }
261
262 if (create_kerberos_key_from_string(context, host_princ, &password, key, enctypes[i])) {
263 SAFE_FREE(key);
264 continue;
265 }
266
267 krb5_auth_con_setuseruserkey(context, auth_context, key);
268
269 if (!(ret = krb5_rd_req(context, &auth_context, &packet,
270 NULL,
271 NULL, NULL, pp_tkt))) {
272 DEBUG(10,("ads_secrets_verify_ticket: enc type [%u] decrypted message !\n",
273 (unsigned int)enctypes[i] ));
274 auth_ok = True;
275 krb5_copy_keyblock(context, key, keyblock);
276 krb5_free_keyblock(context, key);
277 break;
278 }
279
280 DEBUG((ret != KRB5_BAD_ENCTYPE) ? 3 : 10,
281 ("ads_secrets_verify_ticket: enc type [%u] failed to decrypt with error %s\n",
282 (unsigned int)enctypes[i], error_message(ret)));
283
284 /* successfully decrypted but ticket is just not valid at the moment */
285 if (ret == KRB5KRB_AP_ERR_TKT_NYV ||
286 ret == KRB5KRB_AP_ERR_TKT_EXPIRED ||
287 ret == KRB5KRB_AP_ERR_SKEW) {
288 krb5_free_keyblock(context, key);
289 break;
290 }
291
292 krb5_free_keyblock(context, key);
293
294 }
295
296 out:
297 SAFE_FREE(password_s);
298 *perr = ret;
299 return auth_ok;
300}
301
302/**********************************************************************************
303 Verify an incoming ticket and parse out the principal name and
304 authorization_data if available.
305***********************************************************************************/
306
307NTSTATUS ads_verify_ticket(TALLOC_CTX *mem_ctx,
308 const char *realm,
309 time_t time_offset,
310 const DATA_BLOB *ticket,
311 char **principal,
312 struct PAC_DATA **pac_data,
313 DATA_BLOB *ap_rep,
314 DATA_BLOB *session_key,
315 bool use_replay_cache)
316{
317 NTSTATUS sret = NT_STATUS_LOGON_FAILURE;
318 NTSTATUS pac_ret;
319 DATA_BLOB auth_data;
320 krb5_context context = NULL;
321 krb5_auth_context auth_context = NULL;
322 krb5_data packet;
323 krb5_ticket *tkt = NULL;
324 krb5_rcache rcache = NULL;
325 krb5_keyblock *keyblock = NULL;
326 time_t authtime;
327 krb5_error_code ret = 0;
328 int flags = 0;
329 krb5_principal host_princ = NULL;
330 krb5_const_principal client_principal = NULL;
331 char *host_princ_s = NULL;
332 bool auth_ok = False;
333 bool got_auth_data = False;
334 struct named_mutex *mutex = NULL;
335
336 ZERO_STRUCT(packet);
337 ZERO_STRUCT(auth_data);
338
339 *principal = NULL;
340 *pac_data = NULL;
341 *ap_rep = data_blob_null;
342 *session_key = data_blob_null;
343
344 initialize_krb5_error_table();
345 ret = krb5_init_context(&context);
346 if (ret) {
347 DEBUG(1,("ads_verify_ticket: krb5_init_context failed (%s)\n", error_message(ret)));
348 return NT_STATUS_LOGON_FAILURE;
349 }
350
351 if (time_offset != 0) {
352 krb5_set_real_time(context, time(NULL) + time_offset, 0);
353 }
354
355 ret = krb5_set_default_realm(context, realm);
356 if (ret) {
357 DEBUG(1,("ads_verify_ticket: krb5_set_default_realm failed (%s)\n", error_message(ret)));
358 goto out;
359 }
360
361 /* This whole process is far more complex than I would
362 like. We have to go through all this to allow us to store
363 the secret internally, instead of using /etc/krb5.keytab */
364
365 ret = krb5_auth_con_init(context, &auth_context);
366 if (ret) {
367 DEBUG(1,("ads_verify_ticket: krb5_auth_con_init failed (%s)\n", error_message(ret)));
368 goto out;
369 }
370
371 krb5_auth_con_getflags( context, auth_context, &flags );
372 if ( !use_replay_cache ) {
373 /* Disable default use of a replay cache */
374 flags &= ~KRB5_AUTH_CONTEXT_DO_TIME;
375 krb5_auth_con_setflags( context, auth_context, flags );
376 }
377
378 asprintf(&host_princ_s, "%s$", global_myname());
379 if (!host_princ_s) {
380 goto out;
381 }
382
383 strlower_m(host_princ_s);
384 ret = smb_krb5_parse_name(context, host_princ_s, &host_princ);
385 if (ret) {
386 DEBUG(1,("ads_verify_ticket: smb_krb5_parse_name(%s) failed (%s)\n",
387 host_princ_s, error_message(ret)));
388 goto out;
389 }
390
391
392 if ( use_replay_cache ) {
393
394 /* Lock a mutex surrounding the replay as there is no
395 locking in the MIT krb5 code surrounding the replay
396 cache... */
397
398 mutex = grab_named_mutex(talloc_tos(), "replay cache mutex",
399 10);
400 if (mutex == NULL) {
401 DEBUG(1,("ads_verify_ticket: unable to protect "
402 "replay cache with mutex.\n"));
403 ret = KRB5_CC_IO;
404 goto out;
405 }
406
407 /* JRA. We must set the rcache here. This will prevent
408 replay attacks. */
409
410 ret = krb5_get_server_rcache(context,
411 krb5_princ_component(context, host_princ, 0),
412 &rcache);
413 if (ret) {
414 DEBUG(1,("ads_verify_ticket: krb5_get_server_rcache "
415 "failed (%s)\n", error_message(ret)));
416 goto out;
417 }
418
419 ret = krb5_auth_con_setrcache(context, auth_context, rcache);
420 if (ret) {
421 DEBUG(1,("ads_verify_ticket: krb5_auth_con_setrcache "
422 "failed (%s)\n", error_message(ret)));
423 goto out;
424 }
425 }
426
427 /* Try secrets.tdb first and fallback to the krb5.keytab if
428 necessary */
429
430 auth_ok = ads_secrets_verify_ticket(context, auth_context, host_princ,
431 ticket, &tkt, &keyblock, &ret);
432
433 if (!auth_ok &&
434 (ret == KRB5KRB_AP_ERR_TKT_NYV ||
435 ret == KRB5KRB_AP_ERR_TKT_EXPIRED ||
436 ret == KRB5KRB_AP_ERR_SKEW)) {
437 goto auth_failed;
438 }
439
440 if (!auth_ok && lp_use_kerberos_keytab()) {
441 auth_ok = ads_keytab_verify_ticket(context, auth_context,
442 ticket, &tkt, &keyblock, &ret);
443 }
444
445 if ( use_replay_cache ) {
446 TALLOC_FREE(mutex);
447#if 0
448 /* Heimdal leaks here, if we fix the leak, MIT crashes */
449 if (rcache) {
450 krb5_rc_close(context, rcache);
451 }
452#endif
453 }
454
455 auth_failed:
456 if (!auth_ok) {
457 DEBUG(3,("ads_verify_ticket: krb5_rd_req with auth failed (%s)\n",
458 error_message(ret)));
459 /* Try map the error return in case it's something like
460 * a clock skew error.
461 */
462 sret = krb5_to_nt_status(ret);
463 if (NT_STATUS_IS_OK(sret) || NT_STATUS_EQUAL(sret,NT_STATUS_UNSUCCESSFUL)) {
464 sret = NT_STATUS_LOGON_FAILURE;
465 }
466 DEBUG(10,("ads_verify_ticket: returning error %s\n",
467 nt_errstr(sret) ));
468 goto out;
469 }
470
471 authtime = get_authtime_from_tkt(tkt);
472 client_principal = get_principal_from_tkt(tkt);
473
474 ret = krb5_mk_rep(context, auth_context, &packet);
475 if (ret) {
476 DEBUG(3,("ads_verify_ticket: Failed to generate mutual authentication reply (%s)\n",
477 error_message(ret)));
478 goto out;
479 }
480
481 *ap_rep = data_blob(packet.data, packet.length);
482 if (packet.data) {
483 kerberos_free_data_contents(context, &packet);
484 ZERO_STRUCT(packet);
485 }
486
487 get_krb5_smb_session_key(context, auth_context, session_key, True);
488 dump_data_pw("SMB session key (from ticket)\n", session_key->data, session_key->length);
489
490#if 0
491 file_save("/tmp/ticket.dat", ticket->data, ticket->length);
492#endif
493
494 /* continue when no PAC is retrieved or we couldn't decode the PAC
495 (like accounts that have the UF_NO_AUTH_DATA_REQUIRED flag set, or
496 Kerberos tickets encrypted using a DES key) - Guenther */
497
498 got_auth_data = get_auth_data_from_tkt(mem_ctx, &auth_data, tkt);
499 if (!got_auth_data) {
500 DEBUG(3,("ads_verify_ticket: did not retrieve auth data. continuing without PAC\n"));
501 }
502
503 if (got_auth_data) {
504 pac_ret = decode_pac_data(mem_ctx, &auth_data, context, keyblock, client_principal, authtime, pac_data);
505 if (!NT_STATUS_IS_OK(pac_ret)) {
506 DEBUG(3,("ads_verify_ticket: failed to decode PAC_DATA: %s\n", nt_errstr(pac_ret)));
507 *pac_data = NULL;
508 }
509 data_blob_free(&auth_data);
510 }
511
512#if 0
513#if defined(HAVE_KRB5_TKT_ENC_PART2)
514 /* MIT */
515 if (tkt->enc_part2) {
516 file_save("/tmp/authdata.dat",
517 tkt->enc_part2->authorization_data[0]->contents,
518 tkt->enc_part2->authorization_data[0]->length);
519 }
520#else
521 /* Heimdal */
522 if (tkt->ticket.authorization_data) {
523 file_save("/tmp/authdata.dat",
524 tkt->ticket.authorization_data->val->ad_data.data,
525 tkt->ticket.authorization_data->val->ad_data.length);
526 }
527#endif
528#endif
529
530 if ((ret = smb_krb5_unparse_name(context, client_principal, principal))) {
531 DEBUG(3,("ads_verify_ticket: smb_krb5_unparse_name failed (%s)\n",
532 error_message(ret)));
533 sret = NT_STATUS_LOGON_FAILURE;
534 goto out;
535 }
536
537 sret = NT_STATUS_OK;
538
539 out:
540
541 TALLOC_FREE(mutex);
542
543 if (!NT_STATUS_IS_OK(sret)) {
544 data_blob_free(&auth_data);
545 }
546
547 if (!NT_STATUS_IS_OK(sret)) {
548 data_blob_free(ap_rep);
549 }
550
551 if (host_princ) {
552 krb5_free_principal(context, host_princ);
553 }
554
555 if (keyblock) {
556 krb5_free_keyblock(context, keyblock);
557 }
558
559 if (tkt != NULL) {
560 krb5_free_ticket(context, tkt);
561 }
562
563 SAFE_FREE(host_princ_s);
564
565 if (auth_context) {
566 krb5_auth_con_free(context, auth_context);
567 }
568
569 if (context) {
570 krb5_free_context(context);
571 }
572
573 return sret;
574}
575
576#endif /* HAVE_KRB5 */
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