source: trunk-3.0/source/libads/kerberos_verify.c@ 103

Last change on this file since 103 was 22, checked in by Yuri Dario, 19 years ago

Source code upgrade to 3.0.25pre2.
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 2 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, write to the Free Software
24 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
25*/
26
27#include "includes.h"
28
29#ifdef HAVE_KRB5
30
31#if !defined(HAVE_KRB5_PRINC_COMPONENT)
32const krb5_data *krb5_princ_component(krb5_context, krb5_principal, int );
33#endif
34
35/**********************************************************************************
36 Try to verify a ticket using the system keytab... the system keytab has kvno -1 entries, so
37 it's more like what microsoft does... see comment in utils/net_ads.c in the
38 ads_keytab_add_entry function for details.
39***********************************************************************************/
40
41static BOOL ads_keytab_verify_ticket(krb5_context context,
42 krb5_auth_context auth_context,
43 const DATA_BLOB *ticket,
44 krb5_ticket **pp_tkt,
45 krb5_keyblock **keyblock,
46 krb5_error_code *perr)
47{
48 krb5_error_code ret = 0;
49 BOOL auth_ok = False;
50 krb5_keytab keytab = NULL;
51 krb5_kt_cursor kt_cursor;
52 krb5_keytab_entry kt_entry;
53 char *valid_princ_formats[7] = { NULL, NULL, NULL, NULL, NULL, NULL, NULL };
54 char *entry_princ_s = NULL;
55 fstring my_name, my_fqdn;
56 int i;
57 int number_matched_principals = 0;
58 krb5_data packet;
59
60 *pp_tkt = NULL;
61 *keyblock = NULL;
62 *perr = 0;
63
64 /* Generate the list of principal names which we expect
65 * clients might want to use for authenticating to the file
66 * service. We allow name$,{host,cifs}/{name,fqdn,name.REALM}. */
67
68 fstrcpy(my_name, global_myname());
69
70 my_fqdn[0] = '\0';
71 name_to_fqdn(my_fqdn, global_myname());
72
73 asprintf(&valid_princ_formats[0], "%s$@%s", my_name, lp_realm());
74 asprintf(&valid_princ_formats[1], "host/%s@%s", my_name, lp_realm());
75 asprintf(&valid_princ_formats[2], "host/%s@%s", my_fqdn, lp_realm());
76 asprintf(&valid_princ_formats[3], "host/%s.%s@%s", my_name, lp_realm(), lp_realm());
77 asprintf(&valid_princ_formats[4], "cifs/%s@%s", my_name, lp_realm());
78 asprintf(&valid_princ_formats[5], "cifs/%s@%s", my_fqdn, lp_realm());
79 asprintf(&valid_princ_formats[6], "cifs/%s.%s@%s", my_name, lp_realm(), lp_realm());
80
81 ZERO_STRUCT(kt_entry);
82 ZERO_STRUCT(kt_cursor);
83
84 ret = krb5_kt_default(context, &keytab);
85 if (ret) {
86 DEBUG(1, ("ads_keytab_verify_ticket: krb5_kt_default failed (%s)\n", error_message(ret)));
87 goto out;
88 }
89
90 /* Iterate through the keytab. For each key, if the principal
91 * name case-insensitively matches one of the allowed formats,
92 * try verifying the ticket using that principal. */
93
94 ret = krb5_kt_start_seq_get(context, keytab, &kt_cursor);
95 if (ret) {
96 DEBUG(1, ("ads_keytab_verify_ticket: krb5_kt_start_seq_get failed (%s)\n", error_message(ret)));
97 goto out;
98 }
99
100 while (!auth_ok && (krb5_kt_next_entry(context, keytab, &kt_entry, &kt_cursor) == 0)) {
101 ret = smb_krb5_unparse_name(context, kt_entry.principal, &entry_princ_s);
102 if (ret) {
103 DEBUG(1, ("ads_keytab_verify_ticket: smb_krb5_unparse_name failed (%s)\n",
104 error_message(ret)));
105 goto out;
106 }
107
108 for (i = 0; i < ARRAY_SIZE(valid_princ_formats); i++) {
109
110 if (!strequal(entry_princ_s, valid_princ_formats[i])) {
111 continue;
112 }
113
114 number_matched_principals++;
115 packet.length = ticket->length;
116 packet.data = (char *)ticket->data;
117 *pp_tkt = NULL;
118
119 ret = krb5_rd_req_return_keyblock_from_keytab(context, &auth_context, &packet,
120 kt_entry.principal, keytab,
121 NULL, pp_tkt, keyblock);
122
123 if (ret) {
124 DEBUG(10,("ads_keytab_verify_ticket: "
125 "krb5_rd_req_return_keyblock_from_keytab(%s) failed: %s\n",
126 entry_princ_s, error_message(ret)));
127
128 /* workaround for MIT:
129 * as krb5_ktfile_get_entry will explicitly
130 * close the krb5_keytab as soon as krb5_rd_req
131 * has sucessfully decrypted the ticket but the
132 * ticket is not valid yet (due to clockskew)
133 * there is no point in querying more keytab
134 * entries - Guenther */
135
136 if (ret == KRB5KRB_AP_ERR_TKT_NYV ||
137 ret == KRB5KRB_AP_ERR_TKT_EXPIRED ||
138 ret == KRB5KRB_AP_ERR_SKEW) {
139 break;
140 }
141 } else {
142 DEBUG(3,("ads_keytab_verify_ticket: "
143 "krb5_rd_req_return_keyblock_from_keytab succeeded for principal %s\n",
144 entry_princ_s));
145 auth_ok = True;
146 break;
147 }
148 }
149
150 /* Free the name we parsed. */
151 SAFE_FREE(entry_princ_s);
152
153 /* Free the entry we just read. */
154 smb_krb5_kt_free_entry(context, &kt_entry);
155 ZERO_STRUCT(kt_entry);
156 }
157 krb5_kt_end_seq_get(context, keytab, &kt_cursor);
158
159 ZERO_STRUCT(kt_cursor);
160
161 out:
162
163 for (i = 0; i < ARRAY_SIZE(valid_princ_formats); i++) {
164 SAFE_FREE(valid_princ_formats[i]);
165 }
166
167 if (!auth_ok) {
168 if (!number_matched_principals) {
169 DEBUG(3, ("ads_keytab_verify_ticket: no keytab principals matched expected file service name.\n"));
170 } else {
171 DEBUG(3, ("ads_keytab_verify_ticket: krb5_rd_req failed for all %d matched keytab principals\n",
172 number_matched_principals));
173 }
174 }
175
176 SAFE_FREE(entry_princ_s);
177
178 {
179 krb5_keytab_entry zero_kt_entry;
180 ZERO_STRUCT(zero_kt_entry);
181 if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
182 smb_krb5_kt_free_entry(context, &kt_entry);
183 }
184 }
185
186 {
187 krb5_kt_cursor zero_csr;
188 ZERO_STRUCT(zero_csr);
189 if ((memcmp(&kt_cursor, &zero_csr, sizeof(krb5_kt_cursor)) != 0) && keytab) {
190 krb5_kt_end_seq_get(context, keytab, &kt_cursor);
191 }
192 }
193
194 if (keytab) {
195 krb5_kt_close(context, keytab);
196 }
197 *perr = ret;
198 return auth_ok;
199}
200
201/**********************************************************************************
202 Try to verify a ticket using the secrets.tdb.
203***********************************************************************************/
204
205static krb5_error_code ads_secrets_verify_ticket(krb5_context context,
206 krb5_auth_context auth_context,
207 krb5_principal host_princ,
208 const DATA_BLOB *ticket,
209 krb5_ticket **pp_tkt,
210 krb5_keyblock **keyblock,
211 krb5_error_code *perr)
212{
213 krb5_error_code ret = 0;
214 BOOL auth_ok = False;
215 char *password_s = NULL;
216 krb5_data password;
217 krb5_enctype enctypes[4] = { ENCTYPE_DES_CBC_CRC, ENCTYPE_DES_CBC_MD5, 0, 0 };
218 krb5_data packet;
219 int i;
220
221 *pp_tkt = NULL;
222 *keyblock = NULL;
223 *perr = 0;
224
225#if defined(ENCTYPE_ARCFOUR_HMAC)
226 enctypes[2] = ENCTYPE_ARCFOUR_HMAC;
227#endif
228
229 if (!secrets_init()) {
230 DEBUG(1,("ads_secrets_verify_ticket: secrets_init failed\n"));
231 *perr = KRB5_CONFIG_CANTOPEN;
232 return False;
233 }
234
235 password_s = secrets_fetch_machine_password(lp_workgroup(), NULL, NULL);
236 if (!password_s) {
237 DEBUG(1,("ads_secrets_verify_ticket: failed to fetch machine password\n"));
238 *perr = KRB5_LIBOS_CANTREADPWD;
239 return False;
240 }
241
242 password.data = password_s;
243 password.length = strlen(password_s);
244
245 /* CIFS doesn't use addresses in tickets. This would break NAT. JRA */
246
247 packet.length = ticket->length;
248 packet.data = (char *)ticket->data;
249
250 /* We need to setup a auth context with each possible encoding type in turn. */
251 for (i=0;enctypes[i];i++) {
252 krb5_keyblock *key = NULL;
253
254 if (!(key = SMB_MALLOC_P(krb5_keyblock))) {
255 ret = ENOMEM;
256 goto out;
257 }
258
259 if (create_kerberos_key_from_string(context, host_princ, &password, key, enctypes[i])) {
260 SAFE_FREE(key);
261 continue;
262 }
263
264 krb5_auth_con_setuseruserkey(context, auth_context, key);
265
266 if (!(ret = krb5_rd_req(context, &auth_context, &packet,
267 NULL,
268 NULL, NULL, pp_tkt))) {
269 DEBUG(10,("ads_secrets_verify_ticket: enc type [%u] decrypted message !\n",
270 (unsigned int)enctypes[i] ));
271 auth_ok = True;
272 krb5_copy_keyblock(context, key, keyblock);
273 krb5_free_keyblock(context, key);
274 break;
275 }
276
277 DEBUG((ret != KRB5_BAD_ENCTYPE) ? 3 : 10,
278 ("ads_secrets_verify_ticket: enc type [%u] failed to decrypt with error %s\n",
279 (unsigned int)enctypes[i], error_message(ret)));
280
281 /* successfully decrypted but ticket is just not valid at the moment */
282 if (ret == KRB5KRB_AP_ERR_TKT_NYV ||
283 ret == KRB5KRB_AP_ERR_TKT_EXPIRED ||
284 ret == KRB5KRB_AP_ERR_SKEW) {
285 break;
286 }
287
288 krb5_free_keyblock(context, key);
289
290 }
291
292 out:
293 SAFE_FREE(password_s);
294 *perr = ret;
295 return auth_ok;
296}
297
298/**********************************************************************************
299 Verify an incoming ticket and parse out the principal name and
300 authorization_data if available.
301***********************************************************************************/
302
303NTSTATUS ads_verify_ticket(TALLOC_CTX *mem_ctx,
304 const char *realm,
305 time_t time_offset,
306 const DATA_BLOB *ticket,
307 char **principal,
308 PAC_DATA **pac_data,
309 DATA_BLOB *ap_rep,
310 DATA_BLOB *session_key)
311{
312 NTSTATUS sret = NT_STATUS_LOGON_FAILURE;
313 NTSTATUS pac_ret;
314 DATA_BLOB auth_data;
315 krb5_context context = NULL;
316 krb5_auth_context auth_context = NULL;
317 krb5_data packet;
318 krb5_ticket *tkt = NULL;
319 krb5_rcache rcache = NULL;
320 krb5_keyblock *keyblock = NULL;
321 time_t authtime;
322 krb5_error_code ret = 0;
323
324 krb5_principal host_princ = NULL;
325 krb5_const_principal client_principal = NULL;
326 char *host_princ_s = NULL;
327 BOOL auth_ok = False;
328 BOOL got_replay_mutex = False;
329 BOOL got_auth_data = False;
330
331 ZERO_STRUCT(packet);
332 ZERO_STRUCT(auth_data);
333
334 *principal = NULL;
335 *pac_data = NULL;
336 *ap_rep = data_blob(NULL,0);
337 *session_key = data_blob(NULL,0);
338
339 initialize_krb5_error_table();
340 ret = krb5_init_context(&context);
341 if (ret) {
342 DEBUG(1,("ads_verify_ticket: krb5_init_context failed (%s)\n", error_message(ret)));
343 return NT_STATUS_LOGON_FAILURE;
344 }
345
346 if (time_offset != 0) {
347 krb5_set_real_time(context, time(NULL) + time_offset, 0);
348 }
349
350 ret = krb5_set_default_realm(context, realm);
351 if (ret) {
352 DEBUG(1,("ads_verify_ticket: krb5_set_default_realm failed (%s)\n", error_message(ret)));
353 goto out;
354 }
355
356 /* This whole process is far more complex than I would
357 like. We have to go through all this to allow us to store
358 the secret internally, instead of using /etc/krb5.keytab */
359
360 ret = krb5_auth_con_init(context, &auth_context);
361 if (ret) {
362 DEBUG(1,("ads_verify_ticket: krb5_auth_con_init failed (%s)\n", error_message(ret)));
363 goto out;
364 }
365
366 asprintf(&host_princ_s, "%s$", global_myname());
367 if (!host_princ_s) {
368 goto out;
369 }
370
371 strlower_m(host_princ_s);
372 ret = smb_krb5_parse_name(context, host_princ_s, &host_princ);
373 if (ret) {
374 DEBUG(1,("ads_verify_ticket: smb_krb5_parse_name(%s) failed (%s)\n",
375 host_princ_s, error_message(ret)));
376 goto out;
377 }
378
379
380 /* Lock a mutex surrounding the replay as there is no locking in the MIT krb5
381 * code surrounding the replay cache... */
382
383 if (!grab_server_mutex("replay cache mutex")) {
384 DEBUG(1,("ads_verify_ticket: unable to protect replay cache with mutex.\n"));
385 ret = KRB5_CC_IO;
386 goto out;
387 }
388
389 got_replay_mutex = True;
390
391 /*
392 * JRA. We must set the rcache here. This will prevent replay attacks.
393 */
394
395 ret = krb5_get_server_rcache(context, krb5_princ_component(context, host_princ, 0), &rcache);
396 if (ret) {
397 DEBUG(1,("ads_verify_ticket: krb5_get_server_rcache failed (%s)\n", error_message(ret)));
398 goto out;
399 }
400
401 ret = krb5_auth_con_setrcache(context, auth_context, rcache);
402 if (ret) {
403 DEBUG(1,("ads_verify_ticket: krb5_auth_con_setrcache failed (%s)\n", error_message(ret)));
404 goto out;
405 }
406
407 if (lp_use_kerberos_keytab()) {
408 auth_ok = ads_keytab_verify_ticket(context, auth_context, ticket, &tkt, &keyblock, &ret);
409 }
410 if (!auth_ok) {
411 auth_ok = ads_secrets_verify_ticket(context, auth_context, host_princ,
412 ticket, &tkt, &keyblock, &ret);
413 }
414
415 release_server_mutex();
416 got_replay_mutex = False;
417
418#if 0
419 /* Heimdal leaks here, if we fix the leak, MIT crashes */
420 if (rcache) {
421 krb5_rc_close(context, rcache);
422 }
423#endif
424
425 if (!auth_ok) {
426 DEBUG(3,("ads_verify_ticket: krb5_rd_req with auth failed (%s)\n",
427 error_message(ret)));
428 /* Try map the error return in case it's something like
429 * a clock skew error.
430 */
431 sret = krb5_to_nt_status(ret);
432 if (NT_STATUS_IS_OK(sret) || NT_STATUS_EQUAL(sret,NT_STATUS_UNSUCCESSFUL)) {
433 sret = NT_STATUS_LOGON_FAILURE;
434 }
435 DEBUG(10,("ads_verify_ticket: returning error %s\n",
436 nt_errstr(sret) ));
437 goto out;
438 }
439
440 authtime = get_authtime_from_tkt(tkt);
441 client_principal = get_principal_from_tkt(tkt);
442
443 ret = krb5_mk_rep(context, auth_context, &packet);
444 if (ret) {
445 DEBUG(3,("ads_verify_ticket: Failed to generate mutual authentication reply (%s)\n",
446 error_message(ret)));
447 goto out;
448 }
449
450 *ap_rep = data_blob(packet.data, packet.length);
451 if (packet.data) {
452 kerberos_free_data_contents(context, &packet);
453 ZERO_STRUCT(packet);
454 }
455
456 get_krb5_smb_session_key(context, auth_context, session_key, True);
457 dump_data_pw("SMB session key (from ticket)\n", session_key->data, session_key->length);
458
459#if 0
460 file_save("/tmp/ticket.dat", ticket->data, ticket->length);
461#endif
462
463 /* continue when no PAC is retrieved or we couldn't decode the PAC
464 (like accounts that have the UF_NO_AUTH_DATA_REQUIRED flag set, or
465 Kerberos tickets encrypted using a DES key) - Guenther */
466
467 got_auth_data = get_auth_data_from_tkt(mem_ctx, &auth_data, tkt);
468 if (!got_auth_data) {
469 DEBUG(3,("ads_verify_ticket: did not retrieve auth data. continuing without PAC\n"));
470 }
471
472 if (got_auth_data && pac_data != NULL) {
473
474 pac_ret = decode_pac_data(mem_ctx, &auth_data, context, keyblock, client_principal, authtime, pac_data);
475 if (!NT_STATUS_IS_OK(pac_ret)) {
476 DEBUG(3,("ads_verify_ticket: failed to decode PAC_DATA: %s\n", nt_errstr(pac_ret)));
477 *pac_data = NULL;
478 }
479 data_blob_free(&auth_data);
480 }
481
482#if 0
483#if defined(HAVE_KRB5_TKT_ENC_PART2)
484 /* MIT */
485 if (tkt->enc_part2) {
486 file_save("/tmp/authdata.dat",
487 tkt->enc_part2->authorization_data[0]->contents,
488 tkt->enc_part2->authorization_data[0]->length);
489 }
490#else
491 /* Heimdal */
492 if (tkt->ticket.authorization_data) {
493 file_save("/tmp/authdata.dat",
494 tkt->ticket.authorization_data->val->ad_data.data,
495 tkt->ticket.authorization_data->val->ad_data.length);
496 }
497#endif
498#endif
499
500 if ((ret = smb_krb5_unparse_name(context, client_principal, principal))) {
501 DEBUG(3,("ads_verify_ticket: smb_krb5_unparse_name failed (%s)\n",
502 error_message(ret)));
503 sret = NT_STATUS_LOGON_FAILURE;
504 goto out;
505 }
506
507 sret = NT_STATUS_OK;
508
509 out:
510
511 if (got_replay_mutex) {
512 release_server_mutex();
513 }
514
515 if (!NT_STATUS_IS_OK(sret)) {
516 data_blob_free(&auth_data);
517 }
518
519 if (!NT_STATUS_IS_OK(sret)) {
520 data_blob_free(ap_rep);
521 }
522
523 if (host_princ) {
524 krb5_free_principal(context, host_princ);
525 }
526
527 if (keyblock) {
528 krb5_free_keyblock(context, keyblock);
529 }
530
531 if (tkt != NULL) {
532 krb5_free_ticket(context, tkt);
533 }
534
535 SAFE_FREE(host_princ_s);
536
537 if (auth_context) {
538 krb5_auth_con_free(context, auth_context);
539 }
540
541 if (context) {
542 krb5_free_context(context);
543 }
544
545 return sret;
546}
547
548#endif /* HAVE_KRB5 */
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