summaryrefslogtreecommitdiff
path: root/source4/dsdb/samdb/ldb_modules/descriptor.c
blob: 9a4f3d3e04775ef5d183184546c70b9061874cda (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
/*
   ldb database library

   Copyright (C) Simo Sorce  2006-2008
   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2005-2007
   Copyright (C) Nadezhda Ivanova  2009

   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/>.
*/

/*
 *  Name: ldb
 *
 *  Component: DS Security descriptor module
 *
 *  Description:
 *  - Calculate the security descriptor of a newly created object
 *  - Perform sd recalculation on a move operation
 *  - Handle sd modification invariants
 *
 *  Author: Nadezhda Ivanova
 */

#include "includes.h"
#include <ldb_module.h>
#include "util/dlinklist.h"
#include "dsdb/samdb/samdb.h"
#include "librpc/ndr/libndr.h"
#include "librpc/gen_ndr/ndr_security.h"
#include "libcli/security/security.h"
#include "auth/auth.h"
#include "param/param.h"
#include "dsdb/samdb/ldb_modules/util.h"

struct descriptor_data {
	int _dummy;
};

struct descriptor_context {
	struct ldb_module *module;
	struct ldb_request *req;
	struct ldb_message *msg;
	struct ldb_reply *search_res;
	struct ldb_reply *search_oc_res;
	struct ldb_val *parentsd_val;
	struct ldb_message_element *sd_element;
	struct ldb_val *sd_val;
	uint32_t sd_flags;
	int (*step_fn)(struct descriptor_context *);
};

static struct dom_sid *get_default_ag(TALLOC_CTX *mem_ctx,
			       struct ldb_dn *dn,
			       struct security_token *token,
			       struct ldb_context *ldb)
{
	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
	const struct dom_sid *domain_sid = samdb_domain_sid(ldb);
	struct dom_sid *da_sid = dom_sid_add_rid(tmp_ctx, domain_sid, DOMAIN_RID_ADMINS);
	struct dom_sid *ea_sid = dom_sid_add_rid(tmp_ctx, domain_sid, DOMAIN_RID_ENTERPRISE_ADMINS);
	struct dom_sid *sa_sid = dom_sid_add_rid(tmp_ctx, domain_sid, DOMAIN_RID_SCHEMA_ADMINS);
	struct dom_sid *dag_sid;
	struct ldb_dn *nc_root;
	int ret;

	ret = dsdb_find_nc_root(ldb, tmp_ctx, dn, &nc_root);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return NULL;
	}

	if (ldb_dn_compare(nc_root, ldb_get_schema_basedn(ldb)) == 0) {
		if (security_token_has_sid(token, sa_sid)) {
			dag_sid = dom_sid_dup(mem_ctx, sa_sid);
		} else if (security_token_has_sid(token, ea_sid)) {
			dag_sid = dom_sid_dup(mem_ctx, ea_sid);
		} else if (security_token_has_sid(token, da_sid)) {
			dag_sid = dom_sid_dup(mem_ctx, da_sid);
		} else if (security_token_is_system(token)) {
			dag_sid = dom_sid_dup(mem_ctx, sa_sid);
		} else {
			dag_sid = NULL;
		}
	} else if (ldb_dn_compare(nc_root, ldb_get_config_basedn(ldb)) == 0) {
		if (security_token_has_sid(token, ea_sid)) {
			dag_sid = dom_sid_dup(mem_ctx, ea_sid);
		} else if (security_token_has_sid(token, da_sid)) {
			dag_sid = dom_sid_dup(mem_ctx, da_sid);
		} else if (security_token_is_system(token)) {
			dag_sid = dom_sid_dup(mem_ctx, ea_sid);
		} else {
			dag_sid = NULL;
		}
	} else if (ldb_dn_compare(nc_root, ldb_get_default_basedn(ldb)) == 0) {
		if (security_token_has_sid(token, da_sid)) {
			dag_sid = dom_sid_dup(mem_ctx, da_sid);
		} else if (security_token_has_sid(token, ea_sid)) {
				dag_sid = dom_sid_dup(mem_ctx, ea_sid);
		} else if (security_token_is_system(token)) {
			dag_sid = dom_sid_dup(mem_ctx, da_sid);
		} else {
			dag_sid = NULL;
		}
	} else {
		dag_sid = NULL;
	}

	talloc_free(tmp_ctx);
	return dag_sid;
}

static struct security_descriptor *get_sd_unpacked(struct ldb_module *module, TALLOC_CTX *mem_ctx,
					    const struct dsdb_class *objectclass)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct security_descriptor *sd;
	const struct dom_sid *domain_sid = samdb_domain_sid(ldb);

	if (!objectclass->defaultSecurityDescriptor || !domain_sid) {
		return NULL;
	}

	sd = sddl_decode(mem_ctx,
			 objectclass->defaultSecurityDescriptor,
			 domain_sid);
	return sd;
}

static struct dom_sid *get_default_group(TALLOC_CTX *mem_ctx,
					 struct ldb_context *ldb,
					 struct dom_sid *dag)
{
	if (dsdb_functional_level(ldb) >= DS_DOMAIN_FUNCTION_2008) {
		return dag;
	}

	return NULL;
}

static struct security_descriptor *descr_handle_sd_flags(TALLOC_CTX *mem_ctx,
							 struct security_descriptor *new_sd,
							 struct security_descriptor *old_sd,
							 uint32_t sd_flags)
{
	struct security_descriptor *final_sd; 
	/* if there is no control or control == 0 modify everything */
	if (!sd_flags) {
		return new_sd;
	}

	final_sd = talloc_zero(mem_ctx, struct security_descriptor);
	final_sd->revision = SECURITY_DESCRIPTOR_REVISION_1;
	final_sd->type = SEC_DESC_SELF_RELATIVE;

	if (sd_flags & (SECINFO_OWNER)) {
		final_sd->owner_sid = talloc_memdup(mem_ctx, new_sd->owner_sid, sizeof(struct dom_sid));
		final_sd->type |= new_sd->type & SEC_DESC_OWNER_DEFAULTED;
	}
	else if (old_sd) {
		final_sd->owner_sid = talloc_memdup(mem_ctx, old_sd->owner_sid, sizeof(struct dom_sid));
		final_sd->type |= old_sd->type & SEC_DESC_OWNER_DEFAULTED;
	}

	if (sd_flags & (SECINFO_GROUP)) {
		final_sd->group_sid = talloc_memdup(mem_ctx, new_sd->group_sid, sizeof(struct dom_sid));
		final_sd->type |= new_sd->type & SEC_DESC_GROUP_DEFAULTED;
	} 
	else if (old_sd) {
		final_sd->group_sid = talloc_memdup(mem_ctx, old_sd->group_sid, sizeof(struct dom_sid));
		final_sd->type |= old_sd->type & SEC_DESC_GROUP_DEFAULTED;
	}

	if (sd_flags & (SECINFO_SACL)) {
		final_sd->sacl = security_acl_dup(mem_ctx,new_sd->sacl);
		final_sd->type |= new_sd->type & (SEC_DESC_SACL_PRESENT |
			SEC_DESC_SACL_DEFAULTED|SEC_DESC_SACL_AUTO_INHERIT_REQ |
			SEC_DESC_SACL_AUTO_INHERITED|SEC_DESC_SACL_PROTECTED |
			SEC_DESC_SERVER_SECURITY);
	} 
	else if (old_sd && old_sd->sacl) {
		final_sd->sacl = security_acl_dup(mem_ctx,old_sd->sacl);
		final_sd->type |= old_sd->type & (SEC_DESC_SACL_PRESENT |
			SEC_DESC_SACL_DEFAULTED|SEC_DESC_SACL_AUTO_INHERIT_REQ |
			SEC_DESC_SACL_AUTO_INHERITED|SEC_DESC_SACL_PROTECTED |
			SEC_DESC_SERVER_SECURITY);
	}

	if (sd_flags & (SECINFO_DACL)) {
		final_sd->dacl = security_acl_dup(mem_ctx,new_sd->dacl);
		final_sd->type |= new_sd->type & (SEC_DESC_DACL_PRESENT |
			SEC_DESC_DACL_DEFAULTED|SEC_DESC_DACL_AUTO_INHERIT_REQ |
			SEC_DESC_DACL_AUTO_INHERITED|SEC_DESC_DACL_PROTECTED |
			SEC_DESC_DACL_TRUSTED);
	} 
	else if (old_sd && old_sd->dacl) {
		final_sd->dacl = security_acl_dup(mem_ctx,old_sd->dacl);
		final_sd->type |= old_sd->type & (SEC_DESC_DACL_PRESENT |
			SEC_DESC_DACL_DEFAULTED|SEC_DESC_DACL_AUTO_INHERIT_REQ |
			SEC_DESC_DACL_AUTO_INHERITED|SEC_DESC_DACL_PROTECTED |
			SEC_DESC_DACL_TRUSTED);
	}
	/* not so sure about this */
	final_sd->type |= new_sd->type & SEC_DESC_RM_CONTROL_VALID;
	return final_sd;
}

static DATA_BLOB *get_new_descriptor(struct ldb_module *module,
				     struct ldb_dn *dn,
				     TALLOC_CTX *mem_ctx,
				     const struct dsdb_class *objectclass,
				     const struct ldb_val *parent,
				     const struct ldb_val *object,
				     const struct ldb_val *old_sd,
				     uint32_t sd_flags)
{
	struct security_descriptor *user_descriptor = NULL, *parent_descriptor = NULL;
	struct security_descriptor *old_descriptor = NULL;
	struct security_descriptor *new_sd, *final_sd;
	DATA_BLOB *linear_sd;
	enum ndr_err_code ndr_err;
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct auth_session_info *session_info
		= ldb_get_opaque(ldb, "sessionInfo");
	const struct dom_sid *domain_sid = samdb_domain_sid(ldb);
	char *sddl_sd;
	struct dom_sid *default_owner;
	struct dom_sid *default_group;
	struct security_descriptor *default_descriptor = NULL;

	if (objectclass != NULL) {
		default_descriptor = get_sd_unpacked(module, mem_ctx, objectclass);
	}

	if (object) {
		user_descriptor = talloc(mem_ctx, struct security_descriptor);
		if (!user_descriptor) {
			return NULL;
		}
		ndr_err = ndr_pull_struct_blob(object, user_descriptor, 
					       user_descriptor,
					       (ndr_pull_flags_fn_t)ndr_pull_security_descriptor);

		if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
			talloc_free(user_descriptor);
			return NULL;
		}
	} else {
		user_descriptor = default_descriptor;
	}

	if (old_sd) {
		old_descriptor = talloc(mem_ctx, struct security_descriptor);
		if (!old_descriptor) {
			return NULL;
		}
		ndr_err = ndr_pull_struct_blob(old_sd, old_descriptor, 
					       old_descriptor,
					       (ndr_pull_flags_fn_t)ndr_pull_security_descriptor);

		if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
			talloc_free(old_descriptor);
			return NULL;
		}
	}

	if (parent) {
		parent_descriptor = talloc(mem_ctx, struct security_descriptor);
		if (!parent_descriptor) {
			return NULL;
		}
		ndr_err = ndr_pull_struct_blob(parent, parent_descriptor, 
					       parent_descriptor,
					       (ndr_pull_flags_fn_t)ndr_pull_security_descriptor);

		if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
			talloc_free(parent_descriptor);
			return NULL;
		}
	}

	if (user_descriptor && default_descriptor &&
	    (user_descriptor->dacl == NULL))
	{
		user_descriptor->dacl = default_descriptor->dacl;
		user_descriptor->type |= default_descriptor->type & (
			SEC_DESC_DACL_PRESENT |
			SEC_DESC_DACL_DEFAULTED|SEC_DESC_DACL_AUTO_INHERIT_REQ |
			SEC_DESC_DACL_AUTO_INHERITED|SEC_DESC_DACL_PROTECTED |
			SEC_DESC_DACL_TRUSTED);
	}

	if (user_descriptor && default_descriptor &&
	    (user_descriptor->sacl == NULL))
	{
		user_descriptor->sacl = default_descriptor->sacl;
		user_descriptor->type |= default_descriptor->type & (
			SEC_DESC_SACL_PRESENT |
			SEC_DESC_SACL_DEFAULTED|SEC_DESC_SACL_AUTO_INHERIT_REQ |
			SEC_DESC_SACL_AUTO_INHERITED|SEC_DESC_SACL_PROTECTED |
			SEC_DESC_SERVER_SECURITY);
	}

	default_owner = get_default_ag(mem_ctx, dn,
				       session_info->security_token, ldb);
	default_group = get_default_group(mem_ctx, ldb, default_owner);
	new_sd = create_security_descriptor(mem_ctx, parent_descriptor, user_descriptor, true,
					    NULL, SEC_DACL_AUTO_INHERIT|SEC_SACL_AUTO_INHERIT,
					    session_info->security_token,
					    default_owner, default_group,
					    map_generic_rights_ds);
	if (!new_sd) {
		return NULL;
	}
	final_sd = descr_handle_sd_flags(mem_ctx, new_sd, old_descriptor, sd_flags);

	if (!final_sd) {
		return NULL;
	}

	if (final_sd->dacl) {
		final_sd->dacl->revision = SECURITY_ACL_REVISION_ADS;
	}
	if (final_sd->sacl) {
		final_sd->sacl->revision = SECURITY_ACL_REVISION_ADS;
	}

	sddl_sd = sddl_encode(mem_ctx, final_sd, domain_sid);
	DEBUG(10, ("Object %s created with desriptor %s\n\n", ldb_dn_get_linearized(dn), sddl_sd));

	linear_sd = talloc(mem_ctx, DATA_BLOB);
	if (!linear_sd) {
		return NULL;
	}

	ndr_err = ndr_push_struct_blob(linear_sd, mem_ctx,
				       final_sd,
				       (ndr_push_flags_fn_t)ndr_push_security_descriptor);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		return NULL;
	}

	return linear_sd;
}

static DATA_BLOB *descr_get_descriptor_to_show(struct ldb_module *module,
					       TALLOC_CTX *mem_ctx,
					       struct ldb_val *sd,
					       uint32_t sd_flags)
{
	struct security_descriptor *old_sd, *final_sd;
	DATA_BLOB *linear_sd;
	enum ndr_err_code ndr_err;

	old_sd = talloc(mem_ctx, struct security_descriptor);
	if (!old_sd) {
		return NULL;
	}
	ndr_err = ndr_pull_struct_blob(sd, old_sd, 
				       old_sd,
				       (ndr_pull_flags_fn_t)ndr_pull_security_descriptor);

	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		talloc_free(old_sd);
		return NULL;
	}

	final_sd = descr_handle_sd_flags(mem_ctx, old_sd, NULL, sd_flags);

	if (!final_sd) {
		return NULL;
	}

	linear_sd = talloc(mem_ctx, DATA_BLOB);
	if (!linear_sd) {
		return NULL;
	}

	ndr_err = ndr_push_struct_blob(linear_sd, mem_ctx,
				       final_sd,
				       (ndr_push_flags_fn_t)ndr_push_security_descriptor);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		return NULL;
	}

	return linear_sd;
}

static struct descriptor_context *descriptor_init_context(struct ldb_module *module,
							  struct ldb_request *req)
{
	struct ldb_context *ldb;
	struct descriptor_context *ac;

	ldb = ldb_module_get_ctx(module);

	ac = talloc_zero(req, struct descriptor_context);
	if (ac == NULL) {
		ldb_set_errstring(ldb, "Out of Memory");
		return NULL;
	}

	ac->module = module;
	ac->req = req;
	return ac;
}

static int descriptor_search_callback(struct ldb_request *req, struct ldb_reply *ares)
{
	struct descriptor_context *ac;
	struct ldb_val *sd_val = NULL;
	struct ldb_message_element *sd_el;
	DATA_BLOB *show_sd;
	int ret;

	ac = talloc_get_type(req->context, struct descriptor_context);

	if (!ares) {
		ret = LDB_ERR_OPERATIONS_ERROR;
		goto fail;
	}
	if (ares->error != LDB_SUCCESS) {
		return ldb_module_done(ac->req, ares->controls,
					ares->response, ares->error);
	}

	switch (ares->type) {
	case LDB_REPLY_ENTRY:
		sd_el = ldb_msg_find_element(ares->message, "nTSecurityDescriptor");
		if (sd_el) {
			sd_val = sd_el->values;
		}

		if (sd_val) {
			show_sd = descr_get_descriptor_to_show(ac->module, ac->req,
							       sd_val, ac->sd_flags);
			if (!show_sd) {
				ret = LDB_ERR_OPERATIONS_ERROR;
				goto fail;
			}
			ldb_msg_remove_attr(ares->message, "nTSecurityDescriptor");
			ret = ldb_msg_add_steal_value(ares->message, "nTSecurityDescriptor", show_sd);
			if (ret != LDB_SUCCESS) {
				goto fail;
			}
		}
		return ldb_module_send_entry(ac->req, ares->message, ares->controls);

	case LDB_REPLY_REFERRAL:
		return ldb_module_send_referral(ac->req, ares->referral);

	case LDB_REPLY_DONE:
		return ldb_module_done(ac->req, ares->controls,
					ares->response, ares->error);
	}

fail:
	talloc_free(ares);
	return ldb_module_done(ac->req, NULL, NULL, ret);
}

static int descriptor_add(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct ldb_request *add_req;
	struct ldb_message *msg;
	struct ldb_result *parent_res;
	const struct ldb_val *parent_sd = NULL;
	const struct ldb_val *user_sd;
	struct ldb_dn *dn = req->op.add.message->dn;
	struct ldb_dn *parent_dn, *nc_root;
	struct ldb_message_element *objectclass_element, *sd_element;
	int ret;
	const struct dsdb_schema *schema;
	DATA_BLOB *sd;
	const struct dsdb_class *objectclass;
	static const char * const parent_attrs[] = { "nTSecurityDescriptor", NULL };
	uint32_t instanceType;
	bool isNC = false;
	uint32_t sd_flags = dsdb_request_sd_flags(req, NULL);

	/* do not manipulate our control entries */
	if (ldb_dn_is_special(dn)) {
		return ldb_next_request(module, req);
	}

	user_sd = ldb_msg_find_ldb_val(req->op.add.message, "nTSecurityDescriptor");
	sd_element = ldb_msg_find_element(req->op.add.message, "nTSecurityDescriptor");
	/* nTSecurityDescriptor without a value is an error, letting through so it is handled */
	if (user_sd == NULL && sd_element) {
		return ldb_next_request(module, req);
	}

	ldb_debug(ldb, LDB_DEBUG_TRACE,"descriptor_add: %s\n", ldb_dn_get_linearized(dn));

	instanceType = ldb_msg_find_attr_as_uint(req->op.add.message, "instanceType", 0);

	if (instanceType & INSTANCE_TYPE_IS_NC_HEAD) {
		isNC = true;
	}

	if (!isNC) {
		ret = dsdb_find_nc_root(ldb, req, dn, &nc_root);
		if (ret != LDB_SUCCESS) {
			ldb_debug(ldb, LDB_DEBUG_TRACE,"descriptor_add: Could not find NC root for %s\n",
				ldb_dn_get_linearized(dn));
			return ret;
		}

		if (ldb_dn_compare(dn, nc_root) == 0) {
			DEBUG(0, ("Found DN %s being a NC by the old method\n", ldb_dn_get_linearized(dn)));
			isNC = true;
		}
	}

	if (isNC) {
		DEBUG(2, ("DN: %s is a NC\n", ldb_dn_get_linearized(dn)));
	}
	if (!isNC) {
		/* if the object has a parent, retrieve its SD to
		 * use for calculation. Unfortunately we do not yet have
		 * instanceType, so we use dsdb_find_nc_root. */

		parent_dn = ldb_dn_get_parent(req, dn);
		if (parent_dn == NULL) {
			return ldb_oom(ldb);
		}

		/* we aren't any NC */
		ret = dsdb_module_search_dn(module, req, &parent_res, parent_dn,
					    parent_attrs,
					    DSDB_FLAG_NEXT_MODULE |
					    DSDB_FLAG_AS_SYSTEM |
					    DSDB_SEARCH_SHOW_RECYCLED,
					    req);
		if (ret != LDB_SUCCESS) {
			ldb_debug(ldb, LDB_DEBUG_TRACE,"descriptor_add: Could not find SD for %s\n",
				  ldb_dn_get_linearized(parent_dn));
			return ret;
		}
		if (parent_res->count != 1) {
			return ldb_operr(ldb);
		}
		parent_sd = ldb_msg_find_ldb_val(parent_res->msgs[0], "nTSecurityDescriptor");
	}

	schema = dsdb_get_schema(ldb, req);

	objectclass_element = ldb_msg_find_element(req->op.add.message, "objectClass");
	if (objectclass_element == NULL) {
		return ldb_operr(ldb);
	}

	objectclass = dsdb_get_last_structural_class(schema,
						     objectclass_element);
	if (objectclass == NULL) {
		return ldb_operr(ldb);
	}

	/*
	 * The SD_FLAG control is ignored on add
	 * and we default to all bits set.
	 */
	sd_flags = 0xF;

	sd = get_new_descriptor(module, dn, req,
				objectclass, parent_sd,
				user_sd, NULL, sd_flags);
	if (sd == NULL) {
		return ldb_operr(ldb);
	}
	msg = ldb_msg_copy_shallow(req, req->op.add.message);
	if (msg == NULL) {
		return ldb_oom(ldb);
	}
	if (sd_element != NULL) {
		sd_element->values[0] = *sd;
	} else {
		ret = ldb_msg_add_steal_value(msg,
					      "nTSecurityDescriptor",
					      sd);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	ret = ldb_build_add_req(&add_req, ldb, req,
				msg,
				req->controls,
				req, dsdb_next_callback,
				req);
	LDB_REQ_SET_LOCATION(add_req);
	if (ret != LDB_SUCCESS) {
		return ldb_error(ldb, ret,
				 "descriptor_add: Error creating new add request.");
	}

	return ldb_next_request(module, add_req);
}

static int descriptor_modify(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct ldb_request *mod_req;
	struct ldb_message *msg;
	struct ldb_result *current_res, *parent_res;
	const struct ldb_val *old_sd = NULL;
	const struct ldb_val *parent_sd = NULL;
	const struct ldb_val *user_sd;
	struct ldb_dn *dn = req->op.mod.message->dn;
	struct ldb_dn *parent_dn;
	struct ldb_message_element *objectclass_element;
	int ret;
	uint32_t instanceType;
	uint32_t sd_flags = dsdb_request_sd_flags(req, NULL);
	const struct dsdb_schema *schema;
	DATA_BLOB *sd;
	const struct dsdb_class *objectclass;
	static const char * const parent_attrs[] = { "nTSecurityDescriptor", NULL };
	static const char * const current_attrs[] = { "nTSecurityDescriptor",
						      "instanceType",
						      "objectClass", NULL };

	/* do not manipulate our control entries */
	if (ldb_dn_is_special(dn)) {
		return ldb_next_request(module, req);
	}

	user_sd = ldb_msg_find_ldb_val(req->op.mod.message, "nTSecurityDescriptor");
	if (!user_sd) {
		return ldb_next_request(module, req);
	}

	ldb_debug(ldb, LDB_DEBUG_TRACE,"descriptor_modify: %s\n", ldb_dn_get_linearized(dn));

	ret = dsdb_module_search_dn(module, req, &current_res, dn,
				    current_attrs,
				    DSDB_FLAG_NEXT_MODULE |
				    DSDB_FLAG_AS_SYSTEM |
				    DSDB_SEARCH_SHOW_RECYCLED,
				    req);
	if (ret != LDB_SUCCESS) {
		ldb_debug(ldb, LDB_DEBUG_ERROR,"descriptor_modify: Could not find %s\n",
			  ldb_dn_get_linearized(dn));
		return ret;
	}

	instanceType = ldb_msg_find_attr_as_uint(current_res->msgs[0],
						 "instanceType", 0);
	/* if the object has a parent, retrieve its SD to
	 * use for calculation */
	if (!ldb_dn_is_null(current_res->msgs[0]->dn) &&
	    !(instanceType & INSTANCE_TYPE_IS_NC_HEAD)) {
		parent_dn = ldb_dn_get_parent(req, dn);
		if (parent_dn == NULL) {
			return ldb_oom(ldb);
		}
		ret = dsdb_module_search_dn(module, req, &parent_res, parent_dn,
					    parent_attrs,
					    DSDB_FLAG_NEXT_MODULE |
					    DSDB_FLAG_AS_SYSTEM |
					    DSDB_SEARCH_SHOW_RECYCLED,
					    req);
		if (ret != LDB_SUCCESS) {
			ldb_debug(ldb, LDB_DEBUG_ERROR, "descriptor_modify: Could not find SD for %s\n",
				  ldb_dn_get_linearized(parent_dn));
			return ret;
		}
		if (parent_res->count != 1) {
			return ldb_operr(ldb);
		}
		parent_sd = ldb_msg_find_ldb_val(parent_res->msgs[0], "nTSecurityDescriptor");
	}

	schema = dsdb_get_schema(ldb, req);

	objectclass_element = ldb_msg_find_element(current_res->msgs[0], "objectClass");
	if (objectclass_element == NULL) {
		return ldb_operr(ldb);
	}

	objectclass = dsdb_get_last_structural_class(schema,
						     objectclass_element);
	if (objectclass == NULL) {
		return ldb_operr(ldb);
	}

	old_sd = ldb_msg_find_ldb_val(current_res->msgs[0], "nTSecurityDescriptor");

	sd = get_new_descriptor(module, dn, req,
				objectclass, parent_sd,
				user_sd, old_sd, sd_flags);
	if (sd == NULL) {
		return ldb_operr(ldb);
	}
	msg = ldb_msg_copy_shallow(req, req->op.mod.message);
	if (msg == NULL) {
		return ldb_oom(ldb);
	}
	if (sd != NULL) {
		struct ldb_message_element *sd_element;
		if (user_sd != NULL) {
			sd_element = ldb_msg_find_element(msg,
							  "nTSecurityDescriptor");
			sd_element->values[0] = *sd;
		}
	}

	ret = ldb_build_mod_req(&mod_req, ldb, req,
				msg,
				req->controls,
				req,
				dsdb_next_callback,
				req);
	LDB_REQ_SET_LOCATION(mod_req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return ldb_next_request(module, mod_req);
}

static int descriptor_search(struct ldb_module *module, struct ldb_request *req)
{
	int ret;
	struct ldb_context *ldb;
	struct ldb_request *down_req;
	struct descriptor_context *ac;
	bool explicit_sd_flags = false;
	uint32_t sd_flags = dsdb_request_sd_flags(req, &explicit_sd_flags);
	bool show_sd = explicit_sd_flags;

	if (!show_sd &&
	    ldb_attr_in_list(req->op.search.attrs, "nTSecurityDescriptor"))
	{
		show_sd = true;
	}

	if (!show_sd) {
		return ldb_next_request(module, req);
	}

	ldb = ldb_module_get_ctx(module);
	ac = descriptor_init_context(module, req);
	if (ac == NULL) {
		return ldb_operr(ldb);
	}
	ac->sd_flags = sd_flags;

	ret = ldb_build_search_req_ex(&down_req, ldb, ac,
				      req->op.search.base,
				      req->op.search.scope,
				      req->op.search.tree,
				      req->op.search.attrs,
				      req->controls,
				      ac, descriptor_search_callback,
				      ac->req);
	LDB_REQ_SET_LOCATION(down_req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return ldb_next_request(ac->module, down_req);
}
/* TODO */
static int descriptor_rename(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct ldb_dn *olddn = req->op.rename.olddn;

	/* do not manipulate our control entries */
	if (ldb_dn_is_special(req->op.rename.olddn)) {
		return ldb_next_request(module, req);
	}

	ldb_debug(ldb, LDB_DEBUG_TRACE,"descriptor_rename: %s\n",
		  ldb_dn_get_linearized(olddn));

	return ldb_next_request(module, req);
}

static int descriptor_init(struct ldb_module *module)
{
	int ret = ldb_mod_register_control(module, LDB_CONTROL_SD_FLAGS_OID);
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	if (ret != LDB_SUCCESS) {
		ldb_debug(ldb, LDB_DEBUG_ERROR,
			"descriptor: Unable to register control with rootdse!\n");
		return ldb_operr(ldb);
	}
	return ldb_next_init(module);
}


static const struct ldb_module_ops ldb_descriptor_module_ops = {
	.name	       = "descriptor",
	.search        = descriptor_search,
	.add           = descriptor_add,
	.modify        = descriptor_modify,
	.rename        = descriptor_rename,
	.init_context  = descriptor_init
};

int ldb_descriptor_module_init(const char *version)
{
	LDB_MODULE_CHECK_VERSION(version);
	return ldb_register_module(&ldb_descriptor_module_ops);
}