summaryrefslogtreecommitdiff
path: root/source4/auth/credentials/credentials_krb5.c
blob: ce0ae7e323acec26d7ecb4aec541b18f1633a2ea (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
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
/* 
   Unix SMB/CIFS implementation.

   Handle user credentials (as regards krb5)

   Copyright (C) Jelmer Vernooij 2005
   Copyright (C) Tim Potter 2001
   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2005
   
   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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "system/kerberos.h"
#include "auth/kerberos/kerberos.h"
#include "auth/credentials/credentials.h"
#include "auth/credentials/credentials_proto.h"
#include "auth/credentials/credentials_krb5.h"
#include "auth/kerberos/kerberos_credentials.h"
#include "auth/kerberos/kerberos_util.h"
#include "param/param.h"

_PUBLIC_ int cli_credentials_get_krb5_context(struct cli_credentials *cred, 
				     struct loadparm_context *lp_ctx,
				     struct smb_krb5_context **smb_krb5_context) 
{
	int ret;
	if (cred->smb_krb5_context) {
		*smb_krb5_context = cred->smb_krb5_context;
		return 0;
	}

	ret = smb_krb5_init_context(cred, NULL, lp_ctx,
				    &cred->smb_krb5_context);
	if (ret) {
		cred->smb_krb5_context = NULL;
		return ret;
	}
	*smb_krb5_context = cred->smb_krb5_context;
	return 0;
}

/* For most predictable behaviour, this needs to be called directly after the cli_credentials_init(),
 * otherwise we may still have references to the old smb_krb5_context in a credential cache etc
 */
_PUBLIC_ NTSTATUS cli_credentials_set_krb5_context(struct cli_credentials *cred, 
					  struct smb_krb5_context *smb_krb5_context)
{
	if (smb_krb5_context == NULL) {
		talloc_unlink(cred, cred->smb_krb5_context);
		cred->smb_krb5_context = NULL;
		return NT_STATUS_OK;
	}

	if (!talloc_reference(cred, smb_krb5_context)) {
		return NT_STATUS_NO_MEMORY;
	}
	cred->smb_krb5_context = smb_krb5_context;
	return NT_STATUS_OK;
}

static int cli_credentials_set_from_ccache(struct cli_credentials *cred, 
					   struct ccache_container *ccache,
					   enum credentials_obtained obtained,
					   const char **error_string)
{
	
	krb5_principal princ;
	krb5_error_code ret;
	char *name;

	if (cred->ccache_obtained > obtained) {
		return 0;
	}

	ret = krb5_cc_get_principal(ccache->smb_krb5_context->krb5_context, 
				    ccache->ccache, &princ);

	if (ret) {
		(*error_string) = talloc_asprintf(cred, "failed to get principal from ccache: %s\n",
						  smb_get_krb5_error_message(ccache->smb_krb5_context->krb5_context,
									     ret, cred));
		return ret;
	}
	
	ret = krb5_unparse_name(ccache->smb_krb5_context->krb5_context, princ, &name);
	if (ret) {
		(*error_string) = talloc_asprintf(cred, "failed to unparse principal from ccache: %s\n",
						  smb_get_krb5_error_message(ccache->smb_krb5_context->krb5_context,
									     ret, cred));
		return ret;
	}

	cli_credentials_set_principal(cred, name, obtained);

	free(name);

	krb5_free_principal(ccache->smb_krb5_context->krb5_context, princ);

	/* set the ccache_obtained here, as it just got set to UNINITIALISED by the calls above */
	cred->ccache_obtained = obtained;

	return 0;
}

/* Free a memory ccache */
static int free_mccache(struct ccache_container *ccc)
{
	krb5_cc_destroy(ccc->smb_krb5_context->krb5_context, ccc->ccache);

	return 0;
}

/* Free a disk-based ccache */
static int free_dccache(struct ccache_container *ccc) {
	krb5_cc_close(ccc->smb_krb5_context->krb5_context, ccc->ccache);

	return 0;
}

_PUBLIC_ int cli_credentials_set_ccache(struct cli_credentials *cred, 
					struct loadparm_context *lp_ctx,
					const char *name,
					enum credentials_obtained obtained,
					const char **error_string)
{
	krb5_error_code ret;
	krb5_principal princ;
	struct ccache_container *ccc;
	if (cred->ccache_obtained > obtained) {
		return 0;
	}

	ccc = talloc(cred, struct ccache_container);
	if (!ccc) {
		(*error_string) = error_message(ENOMEM);
		return ENOMEM;
	}

	ret = cli_credentials_get_krb5_context(cred, lp_ctx,
					       &ccc->smb_krb5_context);
	if (ret) {
		(*error_string) = error_message(ret);
		talloc_free(ccc);
		return ret;
	}
	if (!talloc_reference(ccc, ccc->smb_krb5_context)) {
		talloc_free(ccc);
		(*error_string) = error_message(ENOMEM);
		return ENOMEM;
	}

	if (name) {
		ret = krb5_cc_resolve(ccc->smb_krb5_context->krb5_context, name, &ccc->ccache);
		if (ret) {
			(*error_string) = talloc_asprintf(cred, "failed to read krb5 ccache: %s: %s\n",
							  name,
							  smb_get_krb5_error_message(ccc->smb_krb5_context->krb5_context,
										     ret, ccc));
			talloc_free(ccc);
			return ret;
		}
	} else {
		ret = krb5_cc_default(ccc->smb_krb5_context->krb5_context, &ccc->ccache);
		if (ret) {
			(*error_string) = talloc_asprintf(cred, "failed to read default krb5 ccache: %s\n",
							  smb_get_krb5_error_message(ccc->smb_krb5_context->krb5_context,
										     ret, ccc));
			talloc_free(ccc);
			return ret;
		}
	}

	talloc_set_destructor(ccc, free_dccache);

	ret = krb5_cc_get_principal(ccc->smb_krb5_context->krb5_context, ccc->ccache, &princ);

	if (ret == 0) {
		krb5_free_principal(ccc->smb_krb5_context->krb5_context, princ);
		ret = cli_credentials_set_from_ccache(cred, ccc, obtained, error_string);

		if (ret) {
			(*error_string) = error_message(ret);
			return ret;
		}

		cred->ccache = ccc;
		cred->ccache_obtained = obtained;
		talloc_steal(cred, ccc);

		cli_credentials_invalidate_client_gss_creds(cred, cred->ccache_obtained);
		return 0;
	}
	return 0;
}


static int cli_credentials_new_ccache(struct cli_credentials *cred, 
				      struct loadparm_context *lp_ctx,
				      char *ccache_name,
				      struct ccache_container **_ccc,
				      const char **error_string)
{
	bool must_free_cc_name = false;
	krb5_error_code ret;
	struct ccache_container *ccc = talloc(cred, struct ccache_container);
	if (!ccc) {
		return ENOMEM;
	}

	ret = cli_credentials_get_krb5_context(cred, lp_ctx,
					       &ccc->smb_krb5_context);
	if (ret) {
		talloc_free(ccc);
		(*error_string) = talloc_asprintf(cred, "Failed to get krb5_context: %s",
						  error_message(ret));
		return ret;
	}
	if (!talloc_reference(ccc, ccc->smb_krb5_context)) {
		talloc_free(ccc);
		(*error_string) = strerror(ENOMEM);
		return ENOMEM;
	}

	if (!ccache_name) {
		must_free_cc_name = true;
		ccache_name = talloc_asprintf(ccc, "MEMORY:%p", 
					      ccc);
		
		if (!ccache_name) {
			talloc_free(ccc);
			(*error_string) = strerror(ENOMEM);
			return ENOMEM;
		}
	}

	ret = krb5_cc_resolve(ccc->smb_krb5_context->krb5_context, ccache_name, 
			      &ccc->ccache);
	if (ret) {
		(*error_string) = talloc_asprintf(cred, "failed to resolve a krb5 ccache (%s): %s\n",
						  ccache_name,
						  smb_get_krb5_error_message(ccc->smb_krb5_context->krb5_context,
									     ret, ccc));
		talloc_free(ccache_name);
		talloc_free(ccc);
		return ret;
	}

	if (strncasecmp(ccache_name, "MEMORY:", 7) == 0) {
		talloc_set_destructor(ccc, free_mccache);
	} else {
		talloc_set_destructor(ccc, free_dccache);
	}

	if (must_free_cc_name) {
		talloc_free(ccache_name);
	}

	*_ccc = ccc;

	return 0;
}

_PUBLIC_ int cli_credentials_get_named_ccache(struct cli_credentials *cred, 
					      struct tevent_context *event_ctx,
					      struct loadparm_context *lp_ctx,
					      char *ccache_name,
					      struct ccache_container **ccc,
					      const char **error_string)
{
	krb5_error_code ret;
	enum credentials_obtained obtained;
	
	if (cred->machine_account_pending) {
		cli_credentials_set_machine_account(cred, lp_ctx);
	}

	if (cred->ccache_obtained >= cred->ccache_threshold && 
	    cred->ccache_obtained > CRED_UNINITIALISED) {
		*ccc = cred->ccache;
		return 0;
	}
	if (cli_credentials_is_anonymous(cred)) {
		(*error_string) = "Cannot get anonymous kerberos credentials";
		return EINVAL;
	}

	ret = cli_credentials_new_ccache(cred, lp_ctx, ccache_name, ccc, error_string);
	if (ret) {
		return ret;
	}

	ret = kinit_to_ccache(cred, cred, (*ccc)->smb_krb5_context, event_ctx, (*ccc)->ccache, &obtained, error_string);
	if (ret) {
		return ret;
	}

	ret = cli_credentials_set_from_ccache(cred, *ccc, 
					      obtained, error_string);
	
	cred->ccache = *ccc;
	cred->ccache_obtained = cred->principal_obtained;
	if (ret) {
		return ret;
	}
	cli_credentials_invalidate_client_gss_creds(cred, cred->ccache_obtained);
	return 0;
}

_PUBLIC_ int cli_credentials_get_ccache(struct cli_credentials *cred, 
					struct tevent_context *event_ctx,
					struct loadparm_context *lp_ctx,
					struct ccache_container **ccc,
					const char **error_string)
{
	return cli_credentials_get_named_ccache(cred, event_ctx, lp_ctx, NULL, ccc, error_string);
}

/* We have good reason to think the ccache in these credentials is invalid - blow it away */
static void cli_credentials_unconditionally_invalidate_client_gss_creds(struct cli_credentials *cred)
{
	if (cred->client_gss_creds_obtained > CRED_UNINITIALISED) {
		talloc_unlink(cred, cred->client_gss_creds);
		cred->client_gss_creds = NULL;
	}
	cred->client_gss_creds_obtained = CRED_UNINITIALISED;
}

void cli_credentials_invalidate_client_gss_creds(struct cli_credentials *cred, 
						 enum credentials_obtained obtained)
{
	/* If the caller just changed the username/password etc, then
	 * any cached credentials are now invalid */
	if (obtained >= cred->client_gss_creds_obtained) {
		if (cred->client_gss_creds_obtained > CRED_UNINITIALISED) {
			talloc_unlink(cred, cred->client_gss_creds);
			cred->client_gss_creds = NULL;
		}
		cred->client_gss_creds_obtained = CRED_UNINITIALISED;
	}
	/* Now that we know that the data is 'this specified', then
	 * don't allow something less 'known' to be returned as a
	 * ccache.  Ie, if the username is on the commmand line, we
	 * don't want to later guess to use a file-based ccache */
	if (obtained > cred->client_gss_creds_threshold) {
		cred->client_gss_creds_threshold = obtained;
	}
}

/* We have good reason to think this CCACHE is invalid.  Blow it away */
static void cli_credentials_unconditionally_invalidate_ccache(struct cli_credentials *cred)
{
	if (cred->ccache_obtained > CRED_UNINITIALISED) {
		talloc_unlink(cred, cred->ccache);
		cred->ccache = NULL;
	}
	cred->ccache_obtained = CRED_UNINITIALISED;

	cli_credentials_unconditionally_invalidate_client_gss_creds(cred);
}

_PUBLIC_ void cli_credentials_invalidate_ccache(struct cli_credentials *cred, 
				       enum credentials_obtained obtained)
{
	/* If the caller just changed the username/password etc, then
	 * any cached credentials are now invalid */
	if (obtained >= cred->ccache_obtained) {
		if (cred->ccache_obtained > CRED_UNINITIALISED) {
			talloc_unlink(cred, cred->ccache);
			cred->ccache = NULL;
		}
		cred->ccache_obtained = CRED_UNINITIALISED;
	}
	/* Now that we know that the data is 'this specified', then
	 * don't allow something less 'known' to be returned as a
	 * ccache.  Ie, if the username is on the commmand line, we
	 * don't want to later guess to use a file-based ccache */
	if (obtained > cred->ccache_threshold) {
		cred->ccache_threshold  = obtained;
	}

	cli_credentials_invalidate_client_gss_creds(cred, 
						    obtained);
}

static int free_gssapi_creds(struct gssapi_creds_container *gcc)
{
	OM_uint32 min_stat, maj_stat;
	maj_stat = gss_release_cred(&min_stat, &gcc->creds);
	return 0;
}

_PUBLIC_ int cli_credentials_get_client_gss_creds(struct cli_credentials *cred, 
						  struct tevent_context *event_ctx,
						  struct loadparm_context *lp_ctx,
						  struct gssapi_creds_container **_gcc,
						  const char **error_string)
{
	int ret = 0;
	OM_uint32 maj_stat, min_stat;
	struct gssapi_creds_container *gcc;
	struct ccache_container *ccache;
	gss_buffer_desc empty_buffer = GSS_C_EMPTY_BUFFER;
	krb5_enctype *etypes = NULL;

	if (cred->client_gss_creds_obtained >= cred->client_gss_creds_threshold && 
	    cred->client_gss_creds_obtained > CRED_UNINITIALISED) {
		*_gcc = cred->client_gss_creds;
		return 0;
	}

	ret = cli_credentials_get_ccache(cred, event_ctx, lp_ctx,
					 &ccache, error_string);
	if (ret) {
		DEBUG(1, ("Failed to get CCACHE for GSSAPI client: %s\n", error_message(ret)));
		return ret;
	}

	gcc = talloc(cred, struct gssapi_creds_container);
	if (!gcc) {
		(*error_string) = error_message(ENOMEM);
		return ENOMEM;
	}

	maj_stat = gss_krb5_import_cred(&min_stat, ccache->ccache, NULL, NULL, 
					&gcc->creds);
	if ((maj_stat == GSS_S_FAILURE) && (min_stat == (OM_uint32)KRB5_CC_END || min_stat == (OM_uint32) KRB5_CC_NOTFOUND)) {
		/* This CCACHE is no good.  Ensure we don't use it again */
		cli_credentials_unconditionally_invalidate_ccache(cred);

		/* Now try again to get a ccache */
		ret = cli_credentials_get_ccache(cred, event_ctx, lp_ctx,
						 &ccache, error_string);
		if (ret) {
			DEBUG(1, ("Failed to re-get CCACHE for GSSAPI client: %s\n", error_message(ret)));
			return ret;
		}

		maj_stat = gss_krb5_import_cred(&min_stat, ccache->ccache, NULL, NULL,
						&gcc->creds);

	}

	if (maj_stat) {
		talloc_free(gcc);
		if (min_stat) {
			ret = min_stat;
		} else {
			ret = EINVAL;
		}
		(*error_string) = talloc_asprintf(cred, "gss_krb5_import_cred failed: %s", error_message(ret));
		return ret;
	}

	/*
	 * transfer the enctypes from the smb_krb5_context to the gssapi layer
	 *
	 * We use 'our' smb_krb5_context to do the AS-REQ and it is possible
	 * to configure the enctypes via the krb5.conf.
	 *
	 * And the gss_init_sec_context() creates it's own krb5_context and
	 * the TGS-REQ had all enctypes in it and only the ones configured
	 * and used for the AS-REQ, so it wasn't possible to disable the usage
	 * of AES keys.
	 */
	min_stat = krb5_get_default_in_tkt_etypes(ccache->smb_krb5_context->krb5_context,
						  &etypes);
	if (min_stat == 0) {
		OM_uint32 num_ktypes;

		for (num_ktypes = 0; etypes[num_ktypes]; num_ktypes++);

		maj_stat = gss_krb5_set_allowable_enctypes(&min_stat, gcc->creds,
							   num_ktypes,
							   (int32_t *) etypes);
		krb5_xfree (etypes);
		if (maj_stat) {
			talloc_free(gcc);
			if (min_stat) {
				ret = min_stat;
			} else {
				ret = EINVAL;
			}
			(*error_string) = talloc_asprintf(cred, "gss_krb5_set_allowable_enctypes failed: %s", error_message(ret));
			return ret;
		}
	}

	/* don't force GSS_C_CONF_FLAG and GSS_C_INTEG_FLAG */
	maj_stat = gss_set_cred_option(&min_stat, &gcc->creds,
				       GSS_KRB5_CRED_NO_CI_FLAGS_X,
				       &empty_buffer);
	if (maj_stat) {
		talloc_free(gcc);
		if (min_stat) {
			ret = min_stat;
		} else {
			ret = EINVAL;
		}
		(*error_string) = talloc_asprintf(cred, "gss_set_cred_option failed: %s", error_message(ret));
		return ret;
	}

	cred->client_gss_creds_obtained = cred->ccache_obtained;
	talloc_set_destructor(gcc, free_gssapi_creds);
	cred->client_gss_creds = gcc;
	*_gcc = gcc;
	return 0;
}

/**
   Set a gssapi cred_id_t into the credentials system. (Client case)

   This grabs the credentials both 'intact' and getting the krb5
   ccache out of it.  This routine can be generalised in future for
   the case where we deal with GSSAPI mechs other than krb5.  

   On sucess, the caller must not free gssapi_cred, as it now belongs
   to the credentials system.
*/

 int cli_credentials_set_client_gss_creds(struct cli_credentials *cred, 
					  struct loadparm_context *lp_ctx,
					  gss_cred_id_t gssapi_cred,
					  enum credentials_obtained obtained,
					  const char **error_string)
{
	int ret;
	OM_uint32 maj_stat, min_stat;
	struct ccache_container *ccc;
	struct gssapi_creds_container *gcc;
	if (cred->client_gss_creds_obtained > obtained) {
		return 0;
	}

	gcc = talloc(cred, struct gssapi_creds_container);
	if (!gcc) {
		(*error_string) = error_message(ENOMEM);
		return ENOMEM;
	}

	ret = cli_credentials_new_ccache(cred, lp_ctx, NULL, &ccc, error_string);
	if (ret != 0) {
		return ret;
	}

	maj_stat = gss_krb5_copy_ccache(&min_stat, 
					gssapi_cred, ccc->ccache);
	if (maj_stat) {
		if (min_stat) {
			ret = min_stat;
		} else {
			ret = EINVAL;
		}
		if (ret) {
			(*error_string) = error_message(ENOMEM);
		}
	}

	if (ret == 0) {
		ret = cli_credentials_set_from_ccache(cred, ccc, obtained, error_string);
	}
	cred->ccache = ccc;
	cred->ccache_obtained = obtained;
	if (ret == 0) {
		gcc->creds = gssapi_cred;
		talloc_set_destructor(gcc, free_gssapi_creds);
		
		/* set the clinet_gss_creds_obtained here, as it just 
		   got set to UNINITIALISED by the calls above */
		cred->client_gss_creds_obtained = obtained;
		cred->client_gss_creds = gcc;
	}
	return ret;
}

/* Get the keytab (actually, a container containing the krb5_keytab)
 * attached to this context.  If this hasn't been done or set before,
 * it will be generated from the password.
 */
_PUBLIC_ int cli_credentials_get_keytab(struct cli_credentials *cred, 
					struct loadparm_context *lp_ctx,
					struct keytab_container **_ktc)
{
	krb5_error_code ret;
	struct keytab_container *ktc;
	struct smb_krb5_context *smb_krb5_context;
	TALLOC_CTX *mem_ctx;

	if (cred->keytab_obtained >= (MAX(cred->principal_obtained, 
					  cred->username_obtained))) {
		*_ktc = cred->keytab;
		return 0;
	}

	if (cli_credentials_is_anonymous(cred)) {
		return EINVAL;
	}

	ret = cli_credentials_get_krb5_context(cred, lp_ctx,
					       &smb_krb5_context);
	if (ret) {
		return ret;
	}

	mem_ctx = talloc_new(cred);
	if (!mem_ctx) {
		return ENOMEM;
	}

	ret = smb_krb5_create_memory_keytab(mem_ctx, cred, 
					    smb_krb5_context, &ktc);
	if (ret) {
		talloc_free(mem_ctx);
		return ret;
	}

	cred->keytab_obtained = (MAX(cred->principal_obtained, 
				     cred->username_obtained));

	talloc_steal(cred, ktc);
	cred->keytab = ktc;
	*_ktc = cred->keytab;
	talloc_free(mem_ctx);
	return ret;
}

/* Given the name of a keytab (presumably in the format
 * FILE:/etc/krb5.keytab), open it and attach it */

_PUBLIC_ int cli_credentials_set_keytab_name(struct cli_credentials *cred, 
					     struct loadparm_context *lp_ctx,
					     const char *keytab_name,
					     enum credentials_obtained obtained)
{
	krb5_error_code ret;
	struct keytab_container *ktc;
	struct smb_krb5_context *smb_krb5_context;
	TALLOC_CTX *mem_ctx;

	if (cred->keytab_obtained >= obtained) {
		return 0;
	}

	ret = cli_credentials_get_krb5_context(cred, lp_ctx, &smb_krb5_context);
	if (ret) {
		return ret;
	}

	mem_ctx = talloc_new(cred);
	if (!mem_ctx) {
		return ENOMEM;
	}

	ret = smb_krb5_open_keytab(mem_ctx, smb_krb5_context, 
				   keytab_name, &ktc);
	if (ret) {
		return ret;
	}

	cred->keytab_obtained = obtained;

	talloc_steal(cred, ktc);
	cred->keytab = ktc;
	talloc_free(mem_ctx);

	return ret;
}

/* Get server gss credentials (in gsskrb5, this means the keytab) */

_PUBLIC_ int cli_credentials_get_server_gss_creds(struct cli_credentials *cred, 
						  struct loadparm_context *lp_ctx,
						  struct gssapi_creds_container **_gcc)
{
	int ret = 0;
	OM_uint32 maj_stat, min_stat;
	struct gssapi_creds_container *gcc;
	struct keytab_container *ktc;
	struct smb_krb5_context *smb_krb5_context;
	TALLOC_CTX *mem_ctx;
	krb5_principal princ;
	const char *error_string;
	enum credentials_obtained obtained;

	mem_ctx = talloc_new(cred);
	if (!mem_ctx) {
		return ENOMEM;
	}

	ret = cli_credentials_get_krb5_context(cred, lp_ctx, &smb_krb5_context);
	if (ret) {
		return ret;
	}

	ret = principal_from_credentials(mem_ctx, cred, smb_krb5_context, &princ, &obtained, &error_string);
	if (ret) {
		DEBUG(1,("cli_credentials_get_server_gss_creds: making krb5 principal failed (%s)\n",
			 error_string));
		talloc_free(mem_ctx);
		return ret;
	}

	if (cred->server_gss_creds_obtained >= (MAX(cred->keytab_obtained, obtained))) {
		talloc_free(mem_ctx);
		*_gcc = cred->server_gss_creds;
		return 0;
	}

	ret = cli_credentials_get_keytab(cred, lp_ctx, &ktc);
	if (ret) {
		DEBUG(1, ("Failed to get keytab for GSSAPI server: %s\n", error_message(ret)));
		return ret;
	}

	gcc = talloc(cred, struct gssapi_creds_container);
	if (!gcc) {
		talloc_free(mem_ctx);
		return ENOMEM;
	}

	/* This creates a GSSAPI cred_id_t with the principal and keytab set */
	maj_stat = gss_krb5_import_cred(&min_stat, NULL, princ, ktc->keytab, 
					&gcc->creds);
	if (maj_stat) {
		if (min_stat) {
			ret = min_stat;
		} else {
			ret = EINVAL;
		}
	}
	if (ret == 0) {
		cred->server_gss_creds_obtained = cred->keytab_obtained;
		talloc_set_destructor(gcc, free_gssapi_creds);
		cred->server_gss_creds = gcc;
		*_gcc = gcc;
	}
	talloc_free(mem_ctx);
	return ret;
}

/** 
 * Set Kerberos KVNO
 */

_PUBLIC_ void cli_credentials_set_kvno(struct cli_credentials *cred,
			      int kvno)
{
	cred->kvno = kvno;
}

/**
 * Return Kerberos KVNO
 */

_PUBLIC_ int cli_credentials_get_kvno(struct cli_credentials *cred)
{
	return cred->kvno;
}


const char *cli_credentials_get_salt_principal(struct cli_credentials *cred) 
{
	return cred->salt_principal;
}

_PUBLIC_ void cli_credentials_set_salt_principal(struct cli_credentials *cred, const char *principal) 
{
	talloc_free(cred->salt_principal);
	cred->salt_principal = talloc_strdup(cred, principal);
}

/* The 'impersonate_principal' is used to allow on Kerberos principal
 * (and it's associated keytab etc) to impersonate another.  The
 * ability to do this is controlled by the KDC, but it is generally
 * permitted to impersonate anyone to yourself.  This allows any
 * member of the domain to get the groups of a user.  This is also
 * known as S4U2Self */

const char *cli_credentials_get_impersonate_principal(struct cli_credentials *cred)
{
	return cred->impersonate_principal;
}

_PUBLIC_ void cli_credentials_set_impersonate_principal(struct cli_credentials *cred, const char *principal)
{
	talloc_free(cred->impersonate_principal);
	cred->impersonate_principal = talloc_strdup(cred, principal);
}

/* when impersonating for S4U2Self we need to set the target principal
 * to ourself, as otherwise we would need additional rights.
 * Similarly, we may only be authorized to do general impersonation to
 * some particular services.
 *
 * Likewise, password changes typically require a ticket to kpasswd/realm directly, not via a TGT
 *
 * NULL means that tickets will be obtained for the krbtgt service.
*/

const char *cli_credentials_get_target_service(struct cli_credentials *cred)
{
	return cred->target_service;
}

_PUBLIC_ void cli_credentials_set_target_service(struct cli_credentials *cred, const char *target_service)
{
	talloc_free(cred->target_service);
	cred->target_service = talloc_strdup(cred, target_service);
}