summaryrefslogtreecommitdiff
path: root/security/tomoyo/domain.c
blob: dc4ecc0b20386713e512a0f0d5db9de99701939f (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
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
// SPDX-License-Identifier: GPL-2.0
/*
 * security/tomoyo/domain.c
 *
 * Copyright (C) 2005-2011  NTT DATA CORPORATION
 */

#include "common.h"

#include <linux/binfmts.h>
#include <linux/slab.h>
#include <linux/rculist.h>

/* Variables definitions.*/

/* The initial domain. */
struct tomoyo_domain_info tomoyo_kernel_domain;

/**
 * tomoyo_update_policy - Update an entry for exception policy.
 *
 * @new_entry:       Pointer to "struct tomoyo_acl_info".
 * @size:            Size of @new_entry in bytes.
 * @param:           Pointer to "struct tomoyo_acl_param".
 * @check_duplicate: Callback function to find duplicated entry.
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
int tomoyo_update_policy(struct tomoyo_acl_head *new_entry, const int size,
			 struct tomoyo_acl_param *param,
			 bool (*check_duplicate)(const struct tomoyo_acl_head
						 *,
						 const struct tomoyo_acl_head
						 *))
{
	int error = param->is_delete ? -ENOENT : -ENOMEM;
	struct tomoyo_acl_head *entry;
	struct list_head *list = param->list;

	if (mutex_lock_interruptible(&tomoyo_policy_lock))
		return -ENOMEM;
	list_for_each_entry_rcu(entry, list, list,
				srcu_read_lock_held(&tomoyo_ss)) {
		if (entry->is_deleted == TOMOYO_GC_IN_PROGRESS)
			continue;
		if (!check_duplicate(entry, new_entry))
			continue;
		entry->is_deleted = param->is_delete;
		error = 0;
		break;
	}
	if (error && !param->is_delete) {
		entry = tomoyo_commit_ok(new_entry, size);
		if (entry) {
			list_add_tail_rcu(&entry->list, list);
			error = 0;
		}
	}
	mutex_unlock(&tomoyo_policy_lock);
	return error;
}

/**
 * tomoyo_same_acl_head - Check for duplicated "struct tomoyo_acl_info" entry.
 *
 * @a: Pointer to "struct tomoyo_acl_info".
 * @b: Pointer to "struct tomoyo_acl_info".
 *
 * Returns true if @a == @b, false otherwise.
 */
static inline bool tomoyo_same_acl_head(const struct tomoyo_acl_info *a,
					const struct tomoyo_acl_info *b)
{
	return a->type == b->type && a->cond == b->cond;
}

/**
 * tomoyo_update_domain - Update an entry for domain policy.
 *
 * @new_entry:       Pointer to "struct tomoyo_acl_info".
 * @size:            Size of @new_entry in bytes.
 * @param:           Pointer to "struct tomoyo_acl_param".
 * @check_duplicate: Callback function to find duplicated entry.
 * @merge_duplicate: Callback function to merge duplicated entry.
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
int tomoyo_update_domain(struct tomoyo_acl_info *new_entry, const int size,
			 struct tomoyo_acl_param *param,
			 bool (*check_duplicate)(const struct tomoyo_acl_info
						 *,
						 const struct tomoyo_acl_info
						 *),
			 bool (*merge_duplicate)(struct tomoyo_acl_info *,
						 struct tomoyo_acl_info *,
						 const bool))
{
	const bool is_delete = param->is_delete;
	int error = is_delete ? -ENOENT : -ENOMEM;
	struct tomoyo_acl_info *entry;
	struct list_head * const list = param->list;

	if (param->data[0]) {
		new_entry->cond = tomoyo_get_condition(param);
		if (!new_entry->cond)
			return -EINVAL;
		/*
		 * Domain transition preference is allowed for only
		 * "file execute" entries.
		 */
		if (new_entry->cond->transit &&
		    !(new_entry->type == TOMOYO_TYPE_PATH_ACL &&
		      container_of(new_entry, struct tomoyo_path_acl, head)
		      ->perm == 1 << TOMOYO_TYPE_EXECUTE))
			goto out;
	}
	if (mutex_lock_interruptible(&tomoyo_policy_lock))
		goto out;
	list_for_each_entry_rcu(entry, list, list,
				srcu_read_lock_held(&tomoyo_ss)) {
		if (entry->is_deleted == TOMOYO_GC_IN_PROGRESS)
			continue;
		if (!tomoyo_same_acl_head(entry, new_entry) ||
		    !check_duplicate(entry, new_entry))
			continue;
		if (merge_duplicate)
			entry->is_deleted = merge_duplicate(entry, new_entry,
							    is_delete);
		else
			entry->is_deleted = is_delete;
		error = 0;
		break;
	}
	if (error && !is_delete) {
		entry = tomoyo_commit_ok(new_entry, size);
		if (entry) {
			list_add_tail_rcu(&entry->list, list);
			error = 0;
		}
	}
	mutex_unlock(&tomoyo_policy_lock);
out:
	tomoyo_put_condition(new_entry->cond);
	return error;
}

/**
 * tomoyo_check_acl - Do permission check.
 *
 * @r:           Pointer to "struct tomoyo_request_info".
 * @check_entry: Callback function to check type specific parameters.
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
void tomoyo_check_acl(struct tomoyo_request_info *r,
		      bool (*check_entry)(struct tomoyo_request_info *,
					  const struct tomoyo_acl_info *))
{
	const struct tomoyo_domain_info *domain = r->domain;
	struct tomoyo_acl_info *ptr;
	const struct list_head *list = &domain->acl_info_list;
	u16 i = 0;

retry:
	list_for_each_entry_rcu(ptr, list, list,
				srcu_read_lock_held(&tomoyo_ss)) {
		if (ptr->is_deleted || ptr->type != r->param_type)
			continue;
		if (!check_entry(r, ptr))
			continue;
		if (!tomoyo_condition(r, ptr->cond))
			continue;
		r->matched_acl = ptr;
		r->granted = true;
		return;
	}
	for (; i < TOMOYO_MAX_ACL_GROUPS; i++) {
		if (!test_bit(i, domain->group))
			continue;
		list = &domain->ns->acl_group[i++];
		goto retry;
	}
	r->granted = false;
}

/* The list for "struct tomoyo_domain_info". */
LIST_HEAD(tomoyo_domain_list);

/**
 * tomoyo_last_word - Get last component of a domainname.
 *
 * @name: Domainname to check.
 *
 * Returns the last word of @domainname.
 */
static const char *tomoyo_last_word(const char *name)
{
	const char *cp = strrchr(name, ' ');

	if (cp)
		return cp + 1;
	return name;
}

/**
 * tomoyo_same_transition_control - Check for duplicated "struct tomoyo_transition_control" entry.
 *
 * @a: Pointer to "struct tomoyo_acl_head".
 * @b: Pointer to "struct tomoyo_acl_head".
 *
 * Returns true if @a == @b, false otherwise.
 */
static bool tomoyo_same_transition_control(const struct tomoyo_acl_head *a,
					   const struct tomoyo_acl_head *b)
{
	const struct tomoyo_transition_control *p1 = container_of(a,
								  typeof(*p1),
								  head);
	const struct tomoyo_transition_control *p2 = container_of(b,
								  typeof(*p2),
								  head);

	return p1->type == p2->type && p1->is_last_name == p2->is_last_name
		&& p1->domainname == p2->domainname
		&& p1->program == p2->program;
}

/**
 * tomoyo_write_transition_control - Write "struct tomoyo_transition_control" list.
 *
 * @param: Pointer to "struct tomoyo_acl_param".
 * @type:  Type of this entry.
 *
 * Returns 0 on success, negative value otherwise.
 */
int tomoyo_write_transition_control(struct tomoyo_acl_param *param,
				    const u8 type)
{
	struct tomoyo_transition_control e = { .type = type };
	int error = param->is_delete ? -ENOENT : -ENOMEM;
	char *program = param->data;
	char *domainname = strstr(program, " from ");

	if (domainname) {
		*domainname = '\0';
		domainname += 6;
	} else if (type == TOMOYO_TRANSITION_CONTROL_NO_KEEP ||
		   type == TOMOYO_TRANSITION_CONTROL_KEEP) {
		domainname = program;
		program = NULL;
	}
	if (program && strcmp(program, "any")) {
		if (!tomoyo_correct_path(program))
			return -EINVAL;
		e.program = tomoyo_get_name(program);
		if (!e.program)
			goto out;
	}
	if (domainname && strcmp(domainname, "any")) {
		if (!tomoyo_correct_domain(domainname)) {
			if (!tomoyo_correct_path(domainname))
				goto out;
			e.is_last_name = true;
		}
		e.domainname = tomoyo_get_name(domainname);
		if (!e.domainname)
			goto out;
	}
	param->list = &param->ns->policy_list[TOMOYO_ID_TRANSITION_CONTROL];
	error = tomoyo_update_policy(&e.head, sizeof(e), param,
				     tomoyo_same_transition_control);
out:
	tomoyo_put_name(e.domainname);
	tomoyo_put_name(e.program);
	return error;
}

/**
 * tomoyo_scan_transition - Try to find specific domain transition type.
 *
 * @list:       Pointer to "struct list_head".
 * @domainname: The name of current domain.
 * @program:    The name of requested program.
 * @last_name:  The last component of @domainname.
 * @type:       One of values in "enum tomoyo_transition_type".
 *
 * Returns true if found one, false otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static inline bool tomoyo_scan_transition
(const struct list_head *list, const struct tomoyo_path_info *domainname,
 const struct tomoyo_path_info *program, const char *last_name,
 const enum tomoyo_transition_type type)
{
	const struct tomoyo_transition_control *ptr;

	list_for_each_entry_rcu(ptr, list, head.list,
				srcu_read_lock_held(&tomoyo_ss)) {
		if (ptr->head.is_deleted || ptr->type != type)
			continue;
		if (ptr->domainname) {
			if (!ptr->is_last_name) {
				if (ptr->domainname != domainname)
					continue;
			} else {
				/*
				 * Use direct strcmp() since this is
				 * unlikely used.
				 */
				if (strcmp(ptr->domainname->name, last_name))
					continue;
			}
		}
		if (ptr->program && tomoyo_pathcmp(ptr->program, program))
			continue;
		return true;
	}
	return false;
}

/**
 * tomoyo_transition_type - Get domain transition type.
 *
 * @ns:         Pointer to "struct tomoyo_policy_namespace".
 * @domainname: The name of current domain.
 * @program:    The name of requested program.
 *
 * Returns TOMOYO_TRANSITION_CONTROL_TRANSIT if executing @program causes
 * domain transition across namespaces, TOMOYO_TRANSITION_CONTROL_INITIALIZE if
 * executing @program reinitializes domain transition within that namespace,
 * TOMOYO_TRANSITION_CONTROL_KEEP if executing @program stays at @domainname ,
 * others otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static enum tomoyo_transition_type tomoyo_transition_type
(const struct tomoyo_policy_namespace *ns,
 const struct tomoyo_path_info *domainname,
 const struct tomoyo_path_info *program)
{
	const char *last_name = tomoyo_last_word(domainname->name);
	enum tomoyo_transition_type type = TOMOYO_TRANSITION_CONTROL_NO_RESET;

	while (type < TOMOYO_MAX_TRANSITION_TYPE) {
		const struct list_head * const list =
			&ns->policy_list[TOMOYO_ID_TRANSITION_CONTROL];

		if (!tomoyo_scan_transition(list, domainname, program,
					    last_name, type)) {
			type++;
			continue;
		}
		if (type != TOMOYO_TRANSITION_CONTROL_NO_RESET &&
		    type != TOMOYO_TRANSITION_CONTROL_NO_INITIALIZE)
			break;
		/*
		 * Do not check for reset_domain if no_reset_domain matched.
		 * Do not check for initialize_domain if no_initialize_domain
		 * matched.
		 */
		type++;
		type++;
	}
	return type;
}

/**
 * tomoyo_same_aggregator - Check for duplicated "struct tomoyo_aggregator" entry.
 *
 * @a: Pointer to "struct tomoyo_acl_head".
 * @b: Pointer to "struct tomoyo_acl_head".
 *
 * Returns true if @a == @b, false otherwise.
 */
static bool tomoyo_same_aggregator(const struct tomoyo_acl_head *a,
				   const struct tomoyo_acl_head *b)
{
	const struct tomoyo_aggregator *p1 = container_of(a, typeof(*p1),
							  head);
	const struct tomoyo_aggregator *p2 = container_of(b, typeof(*p2),
							  head);

	return p1->original_name == p2->original_name &&
		p1->aggregated_name == p2->aggregated_name;
}

/**
 * tomoyo_write_aggregator - Write "struct tomoyo_aggregator" list.
 *
 * @param: Pointer to "struct tomoyo_acl_param".
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
int tomoyo_write_aggregator(struct tomoyo_acl_param *param)
{
	struct tomoyo_aggregator e = { };
	int error = param->is_delete ? -ENOENT : -ENOMEM;
	const char *original_name = tomoyo_read_token(param);
	const char *aggregated_name = tomoyo_read_token(param);

	if (!tomoyo_correct_word(original_name) ||
	    !tomoyo_correct_path(aggregated_name))
		return -EINVAL;
	e.original_name = tomoyo_get_name(original_name);
	e.aggregated_name = tomoyo_get_name(aggregated_name);
	if (!e.original_name || !e.aggregated_name ||
	    e.aggregated_name->is_patterned) /* No patterns allowed. */
		goto out;
	param->list = &param->ns->policy_list[TOMOYO_ID_AGGREGATOR];
	error = tomoyo_update_policy(&e.head, sizeof(e), param,
				     tomoyo_same_aggregator);
out:
	tomoyo_put_name(e.original_name);
	tomoyo_put_name(e.aggregated_name);
	return error;
}

/**
 * tomoyo_find_namespace - Find specified namespace.
 *
 * @name: Name of namespace to find.
 * @len:  Length of @name.
 *
 * Returns pointer to "struct tomoyo_policy_namespace" if found,
 * NULL otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static struct tomoyo_policy_namespace *tomoyo_find_namespace
(const char *name, const unsigned int len)
{
	struct tomoyo_policy_namespace *ns;

	list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {
		if (strncmp(name, ns->name, len) ||
		    (name[len] && name[len] != ' '))
			continue;
		return ns;
	}
	return NULL;
}

/**
 * tomoyo_assign_namespace - Create a new namespace.
 *
 * @domainname: Name of namespace to create.
 *
 * Returns pointer to "struct tomoyo_policy_namespace" on success,
 * NULL otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
struct tomoyo_policy_namespace *tomoyo_assign_namespace(const char *domainname)
{
	struct tomoyo_policy_namespace *ptr;
	struct tomoyo_policy_namespace *entry;
	const char *cp = domainname;
	unsigned int len = 0;

	while (*cp && *cp++ != ' ')
		len++;
	ptr = tomoyo_find_namespace(domainname, len);
	if (ptr)
		return ptr;
	if (len >= TOMOYO_EXEC_TMPSIZE - 10 || !tomoyo_domain_def(domainname))
		return NULL;
	entry = kzalloc(sizeof(*entry) + len + 1, GFP_NOFS);
	if (!entry)
		return NULL;
	if (mutex_lock_interruptible(&tomoyo_policy_lock))
		goto out;
	ptr = tomoyo_find_namespace(domainname, len);
	if (!ptr && tomoyo_memory_ok(entry)) {
		char *name = (char *) (entry + 1);

		ptr = entry;
		memmove(name, domainname, len);
		name[len] = '\0';
		entry->name = name;
		tomoyo_init_policy_namespace(entry);
		entry = NULL;
	}
	mutex_unlock(&tomoyo_policy_lock);
out:
	kfree(entry);
	return ptr;
}

/**
 * tomoyo_namespace_jump - Check for namespace jump.
 *
 * @domainname: Name of domain.
 *
 * Returns true if namespace differs, false otherwise.
 */
static bool tomoyo_namespace_jump(const char *domainname)
{
	const char *namespace = tomoyo_current_namespace()->name;
	const int len = strlen(namespace);

	return strncmp(domainname, namespace, len) ||
		(domainname[len] && domainname[len] != ' ');
}

/**
 * tomoyo_assign_domain - Create a domain or a namespace.
 *
 * @domainname: The name of domain.
 * @transit:    True if transit to domain found or created.
 *
 * Returns pointer to "struct tomoyo_domain_info" on success, NULL otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
struct tomoyo_domain_info *tomoyo_assign_domain(const char *domainname,
						const bool transit)
{
	struct tomoyo_domain_info e = { };
	struct tomoyo_domain_info *entry = tomoyo_find_domain(domainname);
	bool created = false;

	if (entry) {
		if (transit) {
			/*
			 * Since namespace is created at runtime, profiles may
			 * not be created by the moment the process transits to
			 * that domain. Do not perform domain transition if
			 * profile for that domain is not yet created.
			 */
			if (tomoyo_policy_loaded &&
			    !entry->ns->profile_ptr[entry->profile])
				return NULL;
		}
		return entry;
	}
	/* Requested domain does not exist. */
	/* Don't create requested domain if domainname is invalid. */
	if (strlen(domainname) >= TOMOYO_EXEC_TMPSIZE - 10 ||
	    !tomoyo_correct_domain(domainname))
		return NULL;
	/*
	 * Since definition of profiles and acl_groups may differ across
	 * namespaces, do not inherit "use_profile" and "use_group" settings
	 * by automatically creating requested domain upon domain transition.
	 */
	if (transit && tomoyo_namespace_jump(domainname))
		return NULL;
	e.ns = tomoyo_assign_namespace(domainname);
	if (!e.ns)
		return NULL;
	/*
	 * "use_profile" and "use_group" settings for automatically created
	 * domains are inherited from current domain. These are 0 for manually
	 * created domains.
	 */
	if (transit) {
		const struct tomoyo_domain_info *domain = tomoyo_domain();

		e.profile = domain->profile;
		memcpy(e.group, domain->group, sizeof(e.group));
	}
	e.domainname = tomoyo_get_name(domainname);
	if (!e.domainname)
		return NULL;
	if (mutex_lock_interruptible(&tomoyo_policy_lock))
		goto out;
	entry = tomoyo_find_domain(domainname);
	if (!entry) {
		entry = tomoyo_commit_ok(&e, sizeof(e));
		if (entry) {
			INIT_LIST_HEAD(&entry->acl_info_list);
			list_add_tail_rcu(&entry->list, &tomoyo_domain_list);
			created = true;
		}
	}
	mutex_unlock(&tomoyo_policy_lock);
out:
	tomoyo_put_name(e.domainname);
	if (entry && transit) {
		if (created) {
			struct tomoyo_request_info r;
			int i;

			tomoyo_init_request_info(&r, entry,
						 TOMOYO_MAC_FILE_EXECUTE);
			r.granted = false;
			tomoyo_write_log(&r, "use_profile %u\n",
					 entry->profile);
			for (i = 0; i < TOMOYO_MAX_ACL_GROUPS; i++)
				if (test_bit(i, entry->group))
					tomoyo_write_log(&r, "use_group %u\n",
							 i);
			tomoyo_update_stat(TOMOYO_STAT_POLICY_UPDATES);
		}
	}
	return entry;
}

/**
 * tomoyo_environ - Check permission for environment variable names.
 *
 * @ee: Pointer to "struct tomoyo_execve".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_environ(struct tomoyo_execve *ee)
{
	struct tomoyo_request_info *r = &ee->r;
	struct linux_binprm *bprm = ee->bprm;
	/* env_page.data is allocated by tomoyo_dump_page(). */
	struct tomoyo_page_dump env_page = { };
	char *arg_ptr; /* Size is TOMOYO_EXEC_TMPSIZE bytes */
	int arg_len = 0;
	unsigned long pos = bprm->p;
	int offset = pos % PAGE_SIZE;
	int argv_count = bprm->argc;
	int envp_count = bprm->envc;
	int error = -ENOMEM;

	ee->r.type = TOMOYO_MAC_ENVIRON;
	ee->r.profile = r->domain->profile;
	ee->r.mode = tomoyo_get_mode(r->domain->ns, ee->r.profile,
				     TOMOYO_MAC_ENVIRON);
	if (!r->mode || !envp_count)
		return 0;
	arg_ptr = kzalloc(TOMOYO_EXEC_TMPSIZE, GFP_NOFS);
	if (!arg_ptr)
		goto out;
	while (error == -ENOMEM) {
		if (!tomoyo_dump_page(bprm, pos, &env_page))
			goto out;
		pos += PAGE_SIZE - offset;
		/* Read. */
		while (argv_count && offset < PAGE_SIZE) {
			if (!env_page.data[offset++])
				argv_count--;
		}
		if (argv_count) {
			offset = 0;
			continue;
		}
		while (offset < PAGE_SIZE) {
			const unsigned char c = env_page.data[offset++];

			if (c && arg_len < TOMOYO_EXEC_TMPSIZE - 10) {
				if (c == '=') {
					arg_ptr[arg_len++] = '\0';
				} else if (c == '\\') {
					arg_ptr[arg_len++] = '\\';
					arg_ptr[arg_len++] = '\\';
				} else if (c > ' ' && c < 127) {
					arg_ptr[arg_len++] = c;
				} else {
					arg_ptr[arg_len++] = '\\';
					arg_ptr[arg_len++] = (c >> 6) + '0';
					arg_ptr[arg_len++]
						= ((c >> 3) & 7) + '0';
					arg_ptr[arg_len++] = (c & 7) + '0';
				}
			} else {
				arg_ptr[arg_len] = '\0';
			}
			if (c)
				continue;
			if (tomoyo_env_perm(r, arg_ptr)) {
				error = -EPERM;
				break;
			}
			if (!--envp_count) {
				error = 0;
				break;
			}
			arg_len = 0;
		}
		offset = 0;
	}
out:
	if (r->mode != TOMOYO_CONFIG_ENFORCING)
		error = 0;
	kfree(env_page.data);
	kfree(arg_ptr);
	return error;
}

/**
 * tomoyo_find_next_domain - Find a domain.
 *
 * @bprm: Pointer to "struct linux_binprm".
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
int tomoyo_find_next_domain(struct linux_binprm *bprm)
{
	struct tomoyo_domain_info *old_domain = tomoyo_domain();
	struct tomoyo_domain_info *domain = NULL;
	const char *original_name = bprm->filename;
	int retval = -ENOMEM;
	bool reject_on_transition_failure = false;
	const struct tomoyo_path_info *candidate;
	struct tomoyo_path_info exename;
	struct tomoyo_execve *ee = kzalloc(sizeof(*ee), GFP_NOFS);

	if (!ee)
		return -ENOMEM;
	ee->tmp = kzalloc(TOMOYO_EXEC_TMPSIZE, GFP_NOFS);
	if (!ee->tmp) {
		kfree(ee);
		return -ENOMEM;
	}
	/* ee->dump->data is allocated by tomoyo_dump_page(). */
	tomoyo_init_request_info(&ee->r, NULL, TOMOYO_MAC_FILE_EXECUTE);
	ee->r.ee = ee;
	ee->bprm = bprm;
	ee->r.obj = &ee->obj;
	ee->obj.path1 = bprm->file->f_path;
	/* Get symlink's pathname of program. */
	retval = -ENOENT;
	exename.name = tomoyo_realpath_nofollow(original_name);
	if (!exename.name)
		goto out;
	tomoyo_fill_path_info(&exename);
retry:
	/* Check 'aggregator' directive. */
	{
		struct tomoyo_aggregator *ptr;
		struct list_head *list =
			&old_domain->ns->policy_list[TOMOYO_ID_AGGREGATOR];

		/* Check 'aggregator' directive. */
		candidate = &exename;
		list_for_each_entry_rcu(ptr, list, head.list,
					srcu_read_lock_held(&tomoyo_ss)) {
			if (ptr->head.is_deleted ||
			    !tomoyo_path_matches_pattern(&exename,
							 ptr->original_name))
				continue;
			candidate = ptr->aggregated_name;
			break;
		}
	}

	/* Check execute permission. */
	retval = tomoyo_execute_permission(&ee->r, candidate);
	if (retval == TOMOYO_RETRY_REQUEST)
		goto retry;
	if (retval < 0)
		goto out;
	/*
	 * To be able to specify domainnames with wildcards, use the
	 * pathname specified in the policy (which may contain
	 * wildcard) rather than the pathname passed to execve()
	 * (which never contains wildcard).
	 */
	if (ee->r.param.path.matched_path)
		candidate = ee->r.param.path.matched_path;

	/*
	 * Check for domain transition preference if "file execute" matched.
	 * If preference is given, make execve() fail if domain transition
	 * has failed, for domain transition preference should be used with
	 * destination domain defined.
	 */
	if (ee->transition) {
		const char *domainname = ee->transition->name;

		reject_on_transition_failure = true;
		if (!strcmp(domainname, "keep"))
			goto force_keep_domain;
		if (!strcmp(domainname, "child"))
			goto force_child_domain;
		if (!strcmp(domainname, "reset"))
			goto force_reset_domain;
		if (!strcmp(domainname, "initialize"))
			goto force_initialize_domain;
		if (!strcmp(domainname, "parent")) {
			char *cp;

			strncpy(ee->tmp, old_domain->domainname->name,
				TOMOYO_EXEC_TMPSIZE - 1);
			cp = strrchr(ee->tmp, ' ');
			if (cp)
				*cp = '\0';
		} else if (*domainname == '<')
			strncpy(ee->tmp, domainname, TOMOYO_EXEC_TMPSIZE - 1);
		else
			snprintf(ee->tmp, TOMOYO_EXEC_TMPSIZE - 1, "%s %s",
				 old_domain->domainname->name, domainname);
		goto force_jump_domain;
	}
	/*
	 * No domain transition preference specified.
	 * Calculate domain to transit to.
	 */
	switch (tomoyo_transition_type(old_domain->ns, old_domain->domainname,
				       candidate)) {
	case TOMOYO_TRANSITION_CONTROL_RESET:
force_reset_domain:
		/* Transit to the root of specified namespace. */
		snprintf(ee->tmp, TOMOYO_EXEC_TMPSIZE - 1, "<%s>",
			 candidate->name);
		/*
		 * Make execve() fail if domain transition across namespaces
		 * has failed.
		 */
		reject_on_transition_failure = true;
		break;
	case TOMOYO_TRANSITION_CONTROL_INITIALIZE:
force_initialize_domain:
		/* Transit to the child of current namespace's root. */
		snprintf(ee->tmp, TOMOYO_EXEC_TMPSIZE - 1, "%s %s",
			 old_domain->ns->name, candidate->name);
		break;
	case TOMOYO_TRANSITION_CONTROL_KEEP:
force_keep_domain:
		/* Keep current domain. */
		domain = old_domain;
		break;
	default:
		if (old_domain == &tomoyo_kernel_domain &&
		    !tomoyo_policy_loaded) {
			/*
			 * Needn't to transit from kernel domain before
			 * starting /sbin/init. But transit from kernel domain
			 * if executing initializers because they might start
			 * before /sbin/init.
			 */
			domain = old_domain;
			break;
		}
force_child_domain:
		/* Normal domain transition. */
		snprintf(ee->tmp, TOMOYO_EXEC_TMPSIZE - 1, "%s %s",
			 old_domain->domainname->name, candidate->name);
		break;
	}
force_jump_domain:
	if (!domain)
		domain = tomoyo_assign_domain(ee->tmp, true);
	if (domain)
		retval = 0;
	else if (reject_on_transition_failure) {
		pr_warn("ERROR: Domain '%s' not ready.\n", ee->tmp);
		retval = -ENOMEM;
	} else if (ee->r.mode == TOMOYO_CONFIG_ENFORCING)
		retval = -ENOMEM;
	else {
		retval = 0;
		if (!old_domain->flags[TOMOYO_DIF_TRANSITION_FAILED]) {
			old_domain->flags[TOMOYO_DIF_TRANSITION_FAILED] = true;
			ee->r.granted = false;
			tomoyo_write_log(&ee->r, "%s", tomoyo_dif
					 [TOMOYO_DIF_TRANSITION_FAILED]);
			pr_warn("ERROR: Domain '%s' not defined.\n", ee->tmp);
		}
	}
 out:
	if (!domain)
		domain = old_domain;
	/* Update reference count on "struct tomoyo_domain_info". */
	{
		struct tomoyo_task *s = tomoyo_task(current);

		s->old_domain_info = s->domain_info;
		s->domain_info = domain;
		atomic_inc(&domain->users);
	}
	kfree(exename.name);
	if (!retval) {
		ee->r.domain = domain;
		retval = tomoyo_environ(ee);
	}
	kfree(ee->tmp);
	kfree(ee->dump.data);
	kfree(ee);
	return retval;
}

/**
 * tomoyo_dump_page - Dump a page to buffer.
 *
 * @bprm: Pointer to "struct linux_binprm".
 * @pos:  Location to dump.
 * @dump: Poiner to "struct tomoyo_page_dump".
 *
 * Returns true on success, false otherwise.
 */
bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos,
		      struct tomoyo_page_dump *dump)
{
	struct page *page;

	/* dump->data is released by tomoyo_find_next_domain(). */
	if (!dump->data) {
		dump->data = kzalloc(PAGE_SIZE, GFP_NOFS);
		if (!dump->data)
			return false;
	}
	/* Same with get_arg_page(bprm, pos, 0) in fs/exec.c */
#ifdef CONFIG_MMU
	/*
	 * This is called at execve() time in order to dig around
	 * in the argv/environment of the new proceess
	 * (represented by bprm).  'current' is the process doing
	 * the execve().
	 */
	if (get_user_pages_remote(bprm->mm, pos, 1,
				FOLL_FORCE, &page, NULL, NULL) <= 0)
		return false;
#else
	page = bprm->page[pos / PAGE_SIZE];
#endif
	if (page != dump->page) {
		const unsigned int offset = pos % PAGE_SIZE;
		/*
		 * Maybe kmap()/kunmap() should be used here.
		 * But remove_arg_zero() uses kmap_atomic()/kunmap_atomic().
		 * So do I.
		 */
		char *kaddr = kmap_atomic(page);

		dump->page = page;
		memcpy(dump->data + offset, kaddr + offset,
		       PAGE_SIZE - offset);
		kunmap_atomic(kaddr);
	}
	/* Same with put_arg_page(page) in fs/exec.c */
#ifdef CONFIG_MMU
	put_page(page);
#endif
	return true;
}