summaryrefslogtreecommitdiffstats
path: root/source3/libads/kerberos_keytab.c
blob: 80d11d434b4061aab5ad13590396a17baaeaa098 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
/*
   Unix SMB/CIFS implementation.
   kerberos keytab utility library
   Copyright (C) Andrew Tridgell 2001
   Copyright (C) Remus Koos 2001
   Copyright (C) Luke Howard 2003
   Copyright (C) Jim McDonough (jmcd@us.ibm.com) 2003
   Copyright (C) Guenther Deschner 2003
   Copyright (C) Rakesh Patel 2004
   Copyright (C) Dan Perry 2004
   Copyright (C) Jeremy Allison 2004
   Copyright (C) Gerald Carter 2006

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

#ifdef HAVE_KRB5

/* This MAX_NAME_LEN is a constant defined in krb5.h */
#ifndef MAX_KEYTAB_NAME_LEN
#define MAX_KEYTAB_NAME_LEN 1100
#endif


/**********************************************************************
**********************************************************************/

static int smb_krb5_kt_add_entry( krb5_context context, krb5_keytab keytab,
                                  krb5_kvno kvno, const char *princ_s, 
				  krb5_enctype *enctypes, krb5_data password )
{
	krb5_error_code ret = 0;
	krb5_kt_cursor cursor;
	krb5_keytab_entry kt_entry;
	krb5_principal princ = NULL;
	int i;
	char *ktprinc = NULL;

	ZERO_STRUCT(kt_entry);
	ZERO_STRUCT(cursor);
	
	ret = smb_krb5_parse_name(context, princ_s, &princ);
	if (ret) {
		DEBUG(1,("ads_keytab_add_entry: smb_krb5_parse_name(%s) failed (%s)\n", princ_s, error_message(ret)));
		goto out;
	}

	/* Seek and delete old keytab entries */
	ret = krb5_kt_start_seq_get(context, keytab, &cursor);
	if (ret != KRB5_KT_END && ret != ENOENT ) {
		DEBUG(3,("ads_keytab_add_entry: Will try to delete old keytab entries\n"));
		while(!krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) {
			BOOL compare_name_ok = False;

			ret = smb_krb5_unparse_name(context, kt_entry.principal, &ktprinc);
			if (ret) {
				DEBUG(1,("ads_keytab_add_entry: smb_krb5_unparse_name failed (%s)\n",
					error_message(ret)));
				goto out;
			}

			/*---------------------------------------------------------------------------
			 * Save the entries with kvno - 1.   This is what microsoft does
			 * to allow people with existing sessions that have kvno - 1 to still
			 * work.   Otherwise, when the password for the machine changes, all
			 * kerberizied sessions will 'break' until either the client reboots or
			 * the client's session key expires and they get a new session ticket
			 * with the new kvno.
			 */

#ifdef HAVE_KRB5_KT_COMPARE
			compare_name_ok = (krb5_kt_compare(context, &kt_entry, princ, 0, 0) == True);
#else
			compare_name_ok = (strcmp(ktprinc, princ_s) == 0);
#endif

			if (!compare_name_ok) {
				DEBUG(10,("ads_keytab_add_entry: ignoring keytab entry principal %s, kvno = %d\n",
					ktprinc, kt_entry.vno));
			}

			SAFE_FREE(ktprinc);

			if (compare_name_ok) {
				if (kt_entry.vno == kvno - 1) {
					DEBUG(5,("ads_keytab_add_entry: Saving previous (kvno %d) entry for principal: %s.\n",
						kvno - 1, princ_s));
				} else {

					DEBUG(5,("ads_keytab_add_entry: Found old entry for principal: %s (kvno %d) - trying to remove it.\n",
						princ_s, kt_entry.vno));
					ret = krb5_kt_end_seq_get(context, keytab, &cursor);
					ZERO_STRUCT(cursor);
					if (ret) {
						DEBUG(1,("ads_keytab_add_entry: krb5_kt_end_seq_get() failed (%s)\n",
							error_message(ret)));
						goto out;
					}
					ret = krb5_kt_remove_entry(context, keytab, &kt_entry);
					if (ret) {
						DEBUG(1,("ads_keytab_add_entry: krb5_kt_remove_entry failed (%s)\n",
							error_message(ret)));
						goto out;
					}

					DEBUG(5,("ads_keytab_add_entry: removed old entry for principal: %s (kvno %d).\n",
						princ_s, kt_entry.vno));

					ret = krb5_kt_start_seq_get(context, keytab, &cursor);
					if (ret) {
						DEBUG(1,("ads_keytab_add_entry: krb5_kt_start_seq failed (%s)\n",
							error_message(ret)));
						goto out;
					}
					ret = smb_krb5_kt_free_entry(context, &kt_entry);
					ZERO_STRUCT(kt_entry);
					if (ret) {
						DEBUG(1,("ads_keytab_add_entry: krb5_kt_remove_entry failed (%s)\n",
							error_message(ret)));
						goto out;
					}
					continue;
				}
			}

			/* Not a match, just free this entry and continue. */
			ret = smb_krb5_kt_free_entry(context, &kt_entry);
			ZERO_STRUCT(kt_entry);
			if (ret) {
				DEBUG(1,("ads_keytab_add_entry: smb_krb5_kt_free_entry failed (%s)\n", error_message(ret)));
				goto out;
			}
		}

		ret = krb5_kt_end_seq_get(context, keytab, &cursor);
		ZERO_STRUCT(cursor);
		if (ret) {
			DEBUG(1,("ads_keytab_add_entry: krb5_kt_end_seq_get failed (%s)\n",error_message(ret)));
			goto out;
		}
	}

	/* Ensure we don't double free. */
	ZERO_STRUCT(kt_entry);
	ZERO_STRUCT(cursor);

	/* If we get here, we have deleted all the old entries with kvno's not equal to the current kvno-1. */

	/* Now add keytab entries for all encryption types */
	for (i = 0; enctypes[i]; i++) {
		krb5_keyblock *keyp;

#if !defined(HAVE_KRB5_KEYTAB_ENTRY_KEY) && !defined(HAVE_KRB5_KEYTAB_ENTRY_KEYBLOCK)
#error krb5_keytab_entry has no key or keyblock member
#endif
#ifdef HAVE_KRB5_KEYTAB_ENTRY_KEY               /* MIT */
		keyp = &kt_entry.key;
#endif
#ifdef HAVE_KRB5_KEYTAB_ENTRY_KEYBLOCK          /* Heimdal */
		keyp = &kt_entry.keyblock;
#endif
		if (create_kerberos_key_from_string(context, princ, &password, keyp, enctypes[i])) {
			continue;
		}

		kt_entry.principal = princ;
		kt_entry.vno       = kvno;

		DEBUG(3,("ads_keytab_add_entry: adding keytab entry for (%s) with encryption type (%d) and version (%d)\n",
			princ_s, enctypes[i], kt_entry.vno));
		ret = krb5_kt_add_entry(context, keytab, &kt_entry);
		krb5_free_keyblock_contents(context, keyp);
		ZERO_STRUCT(kt_entry);
		if (ret) {
			DEBUG(1,("ads_keytab_add_entry: adding entry to keytab failed (%s)\n", error_message(ret)));
			goto out;
		}
	}


out:
	{
		krb5_keytab_entry zero_kt_entry;
		ZERO_STRUCT(zero_kt_entry);
		if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
			smb_krb5_kt_free_entry(context, &kt_entry);
		}
	}
	if (princ) {
		krb5_free_principal(context, princ);
	}
	
	{
		krb5_kt_cursor zero_csr;
		ZERO_STRUCT(zero_csr);
		if ((memcmp(&cursor, &zero_csr, sizeof(krb5_kt_cursor)) != 0) && keytab) {
			krb5_kt_end_seq_get(context, keytab, &cursor);	
		}
	}
	
	return (int)ret;
}


/**********************************************************************
 Adds a single service principal, i.e. 'host' to the system keytab
***********************************************************************/

int ads_keytab_add_entry(ADS_STRUCT *ads, const char *srvPrinc)
{
	krb5_error_code ret = 0;
	krb5_context context = NULL;
	krb5_keytab keytab = NULL;
	krb5_data password;
	krb5_kvno kvno;
        krb5_enctype enctypes[4] = { ENCTYPE_DES_CBC_CRC, ENCTYPE_DES_CBC_MD5, 0, 0 };
	char *princ_s = NULL, *short_princ_s = NULL;
	char *password_s = NULL;
	char *my_fqdn;
	char keytab_name[MAX_KEYTAB_NAME_LEN];          
	TALLOC_CTX *ctx = NULL;
	char *machine_name;

#if defined(ENCTYPE_ARCFOUR_HMAC)
        enctypes[2] = ENCTYPE_ARCFOUR_HMAC;
#endif

	initialize_krb5_error_table();
	ret = krb5_init_context(&context);
	if (ret) {
		DEBUG(1,("ads_keytab_add_entry: could not krb5_init_context: %s\n",error_message(ret)));
		return -1;
	}
	
#ifdef HAVE_WRFILE_KEYTAB       /* MIT */
	keytab_name[0] = 'W';
	keytab_name[1] = 'R';
	ret = krb5_kt_default_name(context, (char *) &keytab_name[2], MAX_KEYTAB_NAME_LEN - 4);
#else                           /* Heimdal */
	ret = krb5_kt_default_name(context, (char *) &keytab_name[0], MAX_KEYTAB_NAME_LEN - 2);
#endif
	if (ret) {
		DEBUG(1,("ads_keytab_add_entry: krb5_kt_default_name failed (%s)\n", error_message(ret)));
		goto out;
	}
	DEBUG(2,("ads_keytab_add_entry: Using default system keytab: %s\n", (char *) &keytab_name));
	ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
	if (ret) {
		DEBUG(1,("ads_keytab_add_entry: krb5_kt_resolve failed (%s)\n", error_message(ret)));
		goto out;
	}

	/* retrieve the password */
	if (!secrets_init()) {
		DEBUG(1,("ads_keytab_add_entry: secrets_init failed\n"));
		ret = -1;
		goto out;
	}
	password_s = secrets_fetch_machine_password(lp_workgroup(), NULL, NULL);
	if (!password_s) {
		DEBUG(1,("ads_keytab_add_entry: failed to fetch machine password\n"));
		ret = -1;
		goto out;
	}
	password.data = password_s;
	password.length = strlen(password_s);

	/* we need the dNSHostName value here */
	
	if ( (ctx = talloc_init("ads_keytab_add_entry")) == NULL ) {
		DEBUG(0,("ads_keytab_add_entry: talloc() failed!\n"));
		ret = -1;
		goto out;
	}
	
	if ( (my_fqdn = ads_get_dnshostname( ads, ctx, global_myname())) == NULL ) {
		DEBUG(0,("ads_keytab_add_entry: unable to determine machine account's dns name in AD!\n"));
		ret = -1;
		goto out;	
	}
	
	if ( (machine_name = ads_get_samaccountname( ads, ctx, global_myname())) == NULL ) {
		DEBUG(0,("ads_keytab_add_entry: unable to determine machine account's short name in AD!\n"));
		ret = -1;
		goto out;	
	}
	/*strip the trailing '$' */
	machine_name[strlen(machine_name)-1] = '\0';
		
	/* Construct our principal */

	if (strchr_m(srvPrinc, '@')) {
		/* It's a fully-named principal. */
		asprintf(&princ_s, "%s", srvPrinc);
	} else if (srvPrinc[strlen(srvPrinc)-1] == '$') {
		/* It's the machine account, as used by smbclient clients. */
		asprintf(&princ_s, "%s@%s", srvPrinc, lp_realm());
	} else {
		/* It's a normal service principal.  Add the SPN now so that we
		 * can obtain credentials for it and double-check the salt value
		 * used to generate the service's keys. */
		 
		asprintf(&princ_s, "%s/%s@%s", srvPrinc, my_fqdn, lp_realm());
		asprintf(&short_princ_s, "%s/%s@%s", srvPrinc, machine_name, lp_realm());
		
		/* According to http://support.microsoft.com/kb/326985/en-us, 
		   certain principal names are automatically mapped to the host/...
		   principal in the AD account.  So only create these in the 
		   keytab, not in AD.  --jerry */
		   
		if ( !strequal( srvPrinc, "cifs" ) && !strequal(srvPrinc, "host" ) ) {
			DEBUG(3,("ads_keytab_add_entry: Attempting to add/update '%s'\n", princ_s));
			
			if (!ADS_ERR_OK(ads_add_service_principal_name(ads, global_myname(), my_fqdn, srvPrinc))) {
				DEBUG(1,("ads_keytab_add_entry: ads_add_service_principal_name failed.\n"));
				goto out;
			}
		}
	}

	kvno = (krb5_kvno) ads_get_kvno(ads, global_myname());
	if (kvno == -1) {       /* -1 indicates failure, everything else is OK */
		DEBUG(1,("ads_keytab_add_entry: ads_get_kvno failed to determine the system's kvno.\n"));
		ret = -1;
		goto out;
	}
	
	/* add the fqdn principal to the keytab */
	
	ret = smb_krb5_kt_add_entry( context, keytab, kvno, princ_s, enctypes, password );
	if ( ret ) {
		DEBUG(1,("ads_keytab_add_entry: Failed to add entry to keytab file\n"));
		goto out;
	}
	
	/* add the short principal name if we have one */
	
	if ( short_princ_s ) {
		ret = smb_krb5_kt_add_entry( context, keytab, kvno, short_princ_s, enctypes, password );
		if ( ret ) {
			DEBUG(1,("ads_keytab_add_entry: Failed to add short entry to keytab file\n"));
			goto out;
		}
	}

out:
	SAFE_FREE( princ_s );
	SAFE_FREE( short_princ_s );
	TALLOC_FREE( ctx );
	
	if (keytab) {
		krb5_kt_close(context, keytab);
	}
	if (context) {
		krb5_free_context(context);
	}
	return (int)ret;
}

/**********************************************************************
 Flushes all entries from the system keytab.
***********************************************************************/

int ads_keytab_flush(ADS_STRUCT *ads)
{
	krb5_error_code ret = 0;
	krb5_context context = NULL;
	krb5_keytab keytab = NULL;
	krb5_kt_cursor cursor;
	krb5_keytab_entry kt_entry;
	krb5_kvno kvno;
	char keytab_name[MAX_KEYTAB_NAME_LEN];

	ZERO_STRUCT(kt_entry);
	ZERO_STRUCT(cursor);

	initialize_krb5_error_table();
	ret = krb5_init_context(&context);
	if (ret) {
		DEBUG(1,("ads_keytab_flush: could not krb5_init_context: %s\n",error_message(ret)));
		return ret;
	}
#ifdef HAVE_WRFILE_KEYTAB
	keytab_name[0] = 'W';
	keytab_name[1] = 'R';
	ret = krb5_kt_default_name(context, (char *) &keytab_name[2], MAX_KEYTAB_NAME_LEN - 4);
#else
	ret = krb5_kt_default_name(context, (char *) &keytab_name[0], MAX_KEYTAB_NAME_LEN - 2);
#endif
	if (ret) {
		DEBUG(1,("ads_keytab_flush: krb5_kt_default failed (%s)\n", error_message(ret)));
		goto out;
	}
	DEBUG(3,("ads_keytab_flush: Using default keytab: %s\n", (char *) &keytab_name));
	ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
	if (ret) {
		DEBUG(1,("ads_keytab_flush: krb5_kt_default failed (%s)\n", error_message(ret)));
		goto out;
	}
	ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
	if (ret) {
		DEBUG(1,("ads_keytab_flush: krb5_kt_default failed (%s)\n", error_message(ret)));
		goto out;
	}

	kvno = (krb5_kvno) ads_get_kvno(ads, global_myname());
	if (kvno == -1) {       /* -1 indicates a failure */
		DEBUG(1,("ads_keytab_flush: Error determining the system's kvno.\n"));
		goto out;
	}

	ret = krb5_kt_start_seq_get(context, keytab, &cursor);
	if (ret != KRB5_KT_END && ret != ENOENT) {
		while (!krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) {
			ret = krb5_kt_end_seq_get(context, keytab, &cursor);
			ZERO_STRUCT(cursor);
			if (ret) {
				DEBUG(1,("ads_keytab_flush: krb5_kt_end_seq_get() failed (%s)\n",error_message(ret)));
				goto out;
			}
			ret = krb5_kt_remove_entry(context, keytab, &kt_entry);
			if (ret) {
				DEBUG(1,("ads_keytab_flush: krb5_kt_remove_entry failed (%s)\n",error_message(ret)));
				goto out;
			}
			ret = krb5_kt_start_seq_get(context, keytab, &cursor);
			if (ret) {
				DEBUG(1,("ads_keytab_flush: krb5_kt_start_seq failed (%s)\n",error_message(ret)));
				goto out;
			}
			ret = smb_krb5_kt_free_entry(context, &kt_entry);
			ZERO_STRUCT(kt_entry);
			if (ret) {
				DEBUG(1,("ads_keytab_flush: krb5_kt_remove_entry failed (%s)\n",error_message(ret)));
				goto out;
			}
		}
	}

	/* Ensure we don't double free. */
	ZERO_STRUCT(kt_entry);
	ZERO_STRUCT(cursor);

	if (!ADS_ERR_OK(ads_clear_service_principal_names(ads, global_myname()))) {
		DEBUG(1,("ads_keytab_flush: Error while clearing service principal listings in LDAP.\n"));
		goto out;
	}

out:

	{
		krb5_keytab_entry zero_kt_entry;
		ZERO_STRUCT(zero_kt_entry);
		if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
			smb_krb5_kt_free_entry(context, &kt_entry);
		}
	}
	{
		krb5_kt_cursor zero_csr;
		ZERO_STRUCT(zero_csr);
		if ((memcmp(&cursor, &zero_csr, sizeof(krb5_kt_cursor)) != 0) && keytab) {
			krb5_kt_end_seq_get(context, keytab, &cursor);	
		}
	}
	if (keytab) {
		krb5_kt_close(context, keytab);
	}
	if (context) {
		krb5_free_context(context);
	}
	return ret;
}

/**********************************************************************
 Adds all the required service principals to the system keytab.
***********************************************************************/

int ads_keytab_create_default(ADS_STRUCT *ads)
{
	krb5_error_code ret = 0;
	krb5_context context = NULL;
	krb5_keytab keytab = NULL;
	krb5_kt_cursor cursor;
	krb5_keytab_entry kt_entry;
	krb5_kvno kvno;
	int i, found = 0;
	char *sam_account_name, *upn;
	char **oldEntries = NULL, *princ_s[26];
	TALLOC_CTX *ctx = NULL;
	fstring machine_name;

	memset(princ_s, '\0', sizeof(princ_s));

	fstrcpy( machine_name, global_myname() );

	/* these are the main ones we need */
	
	if ( (ret = ads_keytab_add_entry(ads, "host") ) != 0 ) {
		DEBUG(1,("ads_keytab_create_default: ads_keytab_add_entry failed while adding 'host'.\n"));
		return ret;
	}


#if 0	/* don't create the CIFS/... keytab entries since no one except smbd 
	   really needs them and we will fall back to verifying against secrets.tdb */
	   
	if ( (ret = ads_keytab_add_entry(ads, "cifs")) != 0 ) {
		DEBUG(1,("ads_keytab_create_default: ads_keytab_add_entry failed while adding 'cifs'.\n"));
		return ret;
	}
#endif

	if ( (ctx = talloc_init("ads_keytab_create_default")) == NULL ) {
		DEBUG(0,("ads_keytab_create_default: talloc() failed!\n"));
		return -1;
	}

	/* now add the userPrincipalName and sAMAccountName entries */
	
	if ( (sam_account_name = ads_get_samaccountname( ads, ctx, machine_name)) == NULL ) {
		DEBUG(0,("ads_keytab_add_entry: unable to determine machine account's name in AD!\n"));
		TALLOC_FREE( ctx );
		return -1;	
	}

	if ( (ret = ads_keytab_add_entry(ads, sam_account_name )) != 0 ) {
		DEBUG(1,("ads_keytab_create_default: ads_keytab_add_entry failed while adding sAMAccountName (%s)\n",
			sam_account_name));
		return ret;
	}
	
	/* remember that not every machine account will have a upn */
		
	upn = ads_get_upn( ads, ctx, machine_name);
	if ( upn ) {
		if ( (ret = ads_keytab_add_entry(ads, upn)) != 0 ) {
			DEBUG(1,("ads_keytab_create_default: ads_keytab_add_entry failed while adding UPN (%s)\n",
				upn));
			TALLOC_FREE( ctx );
			return ret;
		}
	}

	TALLOC_FREE( ctx );

	/* Now loop through the keytab and update any other existing entries... */
	
	kvno = (krb5_kvno) ads_get_kvno(ads, machine_name);
	if (kvno == -1) {
		DEBUG(1,("ads_keytab_create_default: ads_get_kvno failed to determine the system's kvno.\n"));
		return -1;
	}
	
	DEBUG(3,("ads_keytab_create_default: Searching for keytab entries to "
		"preserve and update.\n"));

	ZERO_STRUCT(kt_entry);
	ZERO_STRUCT(cursor);

	initialize_krb5_error_table();
	ret = krb5_init_context(&context);
	if (ret) {
		DEBUG(1,("ads_keytab_create_default: could not krb5_init_context: %s\n",error_message(ret)));
		return ret;
	}
	ret = krb5_kt_default(context, &keytab);
	if (ret) {
		DEBUG(1,("ads_keytab_create_default: krb5_kt_default failed (%s)\n",error_message(ret)));
		goto done;
	}

	ret = krb5_kt_start_seq_get(context, keytab, &cursor);
	if (ret != KRB5_KT_END && ret != ENOENT ) {
		while ((ret = krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) == 0) {
			smb_krb5_kt_free_entry(context, &kt_entry);
			ZERO_STRUCT(kt_entry);
			found++;
		}
	}
	krb5_kt_end_seq_get(context, keytab, &cursor);
	ZERO_STRUCT(cursor);

	/*
	 * Hmmm. There is no "rewind" function for the keytab. This means we have a race condition
	 * where someone else could add entries after we've counted them. Re-open asap to minimise
	 * the race. JRA.
	 */
	
	DEBUG(3, ("ads_keytab_create_default: Found %d entries in the keytab.\n", found));
	if (!found) {
		goto done;
	}
	oldEntries = SMB_MALLOC_ARRAY(char *, found );
	if (!oldEntries) {
		DEBUG(1,("ads_keytab_create_default: Failed to allocate space to store the old keytab entries (malloc failed?).\n"));
		ret = -1;
		goto done;
	}
	memset(oldEntries, '\0', found * sizeof(char *));

	ret = krb5_kt_start_seq_get(context, keytab, &cursor);
	if (ret != KRB5_KT_END && ret != ENOENT ) {
		while (krb5_kt_next_entry(context, keytab, &kt_entry, &cursor) == 0) {
			if (kt_entry.vno != kvno) {
				char *ktprinc = NULL;
				char *p;

				/* This returns a malloc'ed string in ktprinc. */
				ret = smb_krb5_unparse_name(context, kt_entry.principal, &ktprinc);
				if (ret) {
					DEBUG(1,("smb_krb5_unparse_name failed (%s)\n", error_message(ret)));
					goto done;
				}
				/*
				 * From looking at the krb5 source they don't seem to take locale
				 * or mb strings into account. Maybe this is because they assume utf8 ?
				 * In this case we may need to convert from utf8 to mb charset here ? JRA.
				 */
				p = strchr_m(ktprinc, '@');
				if (p) {
					*p = '\0';
				}

				p = strchr_m(ktprinc, '/');
				if (p) {
					*p = '\0';
				}
				for (i = 0; i < found; i++) {
					if (!oldEntries[i]) {
						oldEntries[i] = ktprinc;
						break;
					}
					if (!strcmp(oldEntries[i], ktprinc)) {
						SAFE_FREE(ktprinc);
						break;
					}
				}
				if (i == found) {
					SAFE_FREE(ktprinc);
				}
			}
			smb_krb5_kt_free_entry(context, &kt_entry);
			ZERO_STRUCT(kt_entry);
		}
		ret = 0;
		for (i = 0; oldEntries[i]; i++) {
			ret |= ads_keytab_add_entry(ads, oldEntries[i]);
			SAFE_FREE(oldEntries[i]);
		}
		krb5_kt_end_seq_get(context, keytab, &cursor);
	}
	ZERO_STRUCT(cursor);

done:

	SAFE_FREE(oldEntries);

	{
		krb5_keytab_entry zero_kt_entry;
		ZERO_STRUCT(zero_kt_entry);
		if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
			smb_krb5_kt_free_entry(context, &kt_entry);
		}
	}
	{
		krb5_kt_cursor zero_csr;
		ZERO_STRUCT(zero_csr);
		if ((memcmp(&cursor, &zero_csr, sizeof(krb5_kt_cursor)) != 0) && keytab) {
			krb5_kt_end_seq_get(context, keytab, &cursor);	
		}
	}
	if (keytab) {
		krb5_kt_close(context, keytab);
	}
	if (context) {
		krb5_free_context(context);
	}
	return ret;
}
#endif /* HAVE_KRB5 */