summaryrefslogtreecommitdiffstats
path: root/security/tomoyo/gc.c
blob: f2295c65f1e42eaa0b61c14143bbd8bc33cd1fae (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
/*
 * security/tomoyo/gc.c
 *
 * Copyright (C) 2005-2011  NTT DATA CORPORATION
 */

#include "common.h"
#include <linux/kthread.h>
#include <linux/slab.h>

/* The list for "struct tomoyo_io_buffer". */
static LIST_HEAD(tomoyo_io_buffer_list);
/* Lock for protecting tomoyo_io_buffer_list. */
static DEFINE_SPINLOCK(tomoyo_io_buffer_list_lock);

/**
 * tomoyo_struct_used_by_io_buffer - Check whether the list element is used by /sys/kernel/security/tomoyo/ users or not.
 *
 * @element: Pointer to "struct list_head".
 *
 * Returns true if @element is used by /sys/kernel/security/tomoyo/ users,
 * false otherwise.
 */
static bool tomoyo_struct_used_by_io_buffer(const struct list_head *element)
{
	struct tomoyo_io_buffer *head;
	bool in_use = false;

	spin_lock(&tomoyo_io_buffer_list_lock);
	list_for_each_entry(head, &tomoyo_io_buffer_list, list) {
		head->users++;
		spin_unlock(&tomoyo_io_buffer_list_lock);
		mutex_lock(&head->io_sem);
		if (head->r.domain == element || head->r.group == element ||
		    head->r.acl == element || &head->w.domain->list == element)
			in_use = true;
		mutex_unlock(&head->io_sem);
		spin_lock(&tomoyo_io_buffer_list_lock);
		head->users--;
		if (in_use)
			break;
	}
	spin_unlock(&tomoyo_io_buffer_list_lock);
	return in_use;
}

/**
 * tomoyo_name_used_by_io_buffer - Check whether the string is used by /sys/kernel/security/tomoyo/ users or not.
 *
 * @string: String to check.
 *
 * Returns true if @string is used by /sys/kernel/security/tomoyo/ users,
 * false otherwise.
 */
static bool tomoyo_name_used_by_io_buffer(const char *string)
{
	struct tomoyo_io_buffer *head;
	const size_t size = strlen(string) + 1;
	bool in_use = false;

	spin_lock(&tomoyo_io_buffer_list_lock);
	list_for_each_entry(head, &tomoyo_io_buffer_list, list) {
		int i;
		head->users++;
		spin_unlock(&tomoyo_io_buffer_list_lock);
		mutex_lock(&head->io_sem);
		for (i = 0; i < TOMOYO_MAX_IO_READ_QUEUE; i++) {
			const char *w = head->r.w[i];
			if (w < string || w > string + size)
				continue;
			in_use = true;
			break;
		}
		mutex_unlock(&head->io_sem);
		spin_lock(&tomoyo_io_buffer_list_lock);
		head->users--;
		if (in_use)
			break;
	}
	spin_unlock(&tomoyo_io_buffer_list_lock);
	return in_use;
}

/**
 * tomoyo_del_transition_control - Delete members in "struct tomoyo_transition_control".
 *
 * @element: Pointer to "struct list_head".
 *
 * Returns nothing.
 */
static inline void tomoyo_del_transition_control(struct list_head *element)
{
	struct tomoyo_transition_control *ptr =
		container_of(element, typeof(*ptr), head.list);
	tomoyo_put_name(ptr->domainname);
	tomoyo_put_name(ptr->program);
}

/**
 * tomoyo_del_aggregator - Delete members in "struct tomoyo_aggregator".
 *
 * @element: Pointer to "struct list_head".
 *
 * Returns nothing.
 */
static inline void tomoyo_del_aggregator(struct list_head *element)
{
	struct tomoyo_aggregator *ptr =
		container_of(element, typeof(*ptr), head.list);
	tomoyo_put_name(ptr->original_name);
	tomoyo_put_name(ptr->aggregated_name);
}

/**
 * tomoyo_del_manager - Delete members in "struct tomoyo_manager".
 *
 * @element: Pointer to "struct list_head".
 *
 * Returns nothing.
 */
static inline void tomoyo_del_manager(struct list_head *element)
{
	struct tomoyo_manager *ptr =
		container_of(element, typeof(*ptr), head.list);
	tomoyo_put_name(ptr->manager);
}

/**
 * tomoyo_del_acl - Delete members in "struct tomoyo_acl_info".
 *
 * @element: Pointer to "struct list_head".
 *
 * Returns nothing.
 */
static void tomoyo_del_acl(struct list_head *element)
{
	struct tomoyo_acl_info *acl =
		container_of(element, typeof(*acl), list);
	tomoyo_put_condition(acl->cond);
	switch (acl->type) {
	case TOMOYO_TYPE_PATH_ACL:
		{
			struct tomoyo_path_acl *entry
				= container_of(acl, typeof(*entry), head);
			tomoyo_put_name_union(&entry->name);
		}
		break;
	case TOMOYO_TYPE_PATH2_ACL:
		{
			struct tomoyo_path2_acl *entry
				= container_of(acl, typeof(*entry), head);
			tomoyo_put_name_union(&entry->name1);
			tomoyo_put_name_union(&entry->name2);
		}
		break;
	case TOMOYO_TYPE_PATH_NUMBER_ACL:
		{
			struct tomoyo_path_number_acl *entry
				= container_of(acl, typeof(*entry), head);
			tomoyo_put_name_union(&entry->name);
			tomoyo_put_number_union(&entry->number);
		}
		break;
	case TOMOYO_TYPE_MKDEV_ACL:
		{
			struct tomoyo_mkdev_acl *entry
				= container_of(acl, typeof(*entry), head);
			tomoyo_put_name_union(&entry->name);
			tomoyo_put_number_union(&entry->mode);
			tomoyo_put_number_union(&entry->major);
			tomoyo_put_number_union(&entry->minor);
		}
		break;
	case TOMOYO_TYPE_MOUNT_ACL:
		{
			struct tomoyo_mount_acl *entry
				= container_of(acl, typeof(*entry), head);
			tomoyo_put_name_union(&entry->dev_name);
			tomoyo_put_name_union(&entry->dir_name);
			tomoyo_put_name_union(&entry->fs_type);
			tomoyo_put_number_union(&entry->flags);
		}
		break;
	case TOMOYO_TYPE_ENV_ACL:
		{
			struct tomoyo_env_acl *entry =
				container_of(acl, typeof(*entry), head);

			tomoyo_put_name(entry->env);
		}
		break;
	case TOMOYO_TYPE_INET_ACL:
		{
			struct tomoyo_inet_acl *entry =
				container_of(acl, typeof(*entry), head);

			tomoyo_put_group(entry->address.group);
			tomoyo_put_number_union(&entry->port);
		}
		break;
	case TOMOYO_TYPE_UNIX_ACL:
		{
			struct tomoyo_unix_acl *entry =
				container_of(acl, typeof(*entry), head);

			tomoyo_put_name_union(&entry->name);
		}
		break;
	}
}

/**
 * tomoyo_del_domain - Delete members in "struct tomoyo_domain_info".
 *
 * @element: Pointer to "struct list_head".
 *
 * Returns nothing.
 */
static inline void tomoyo_del_domain(struct list_head *element)
{
	struct tomoyo_domain_info *domain =
		container_of(element, typeof(*domain), list);
	struct tomoyo_acl_info *acl;
	struct tomoyo_acl_info *tmp;
	/*
	 * Since this domain is referenced from neither
	 * "struct tomoyo_io_buffer" nor "struct cred"->security, we can delete
	 * elements without checking for is_deleted flag.
	 */
	list_for_each_entry_safe(acl, tmp, &domain->acl_info_list, list) {
		tomoyo_del_acl(&acl->list);
		tomoyo_memory_free(acl);
	}
	tomoyo_put_name(domain->domainname);
}

/**
 * tomoyo_del_condition - Delete members in "struct tomoyo_condition".
 *
 * @element: Pointer to "struct list_head".
 *
 * Returns nothing.
 */
void tomoyo_del_condition(struct list_head *element)
{
	struct tomoyo_condition *cond = container_of(element, typeof(*cond),
						     head.list);
	const u16 condc = cond->condc;
	const u16 numbers_count = cond->numbers_count;
	const u16 names_count = cond->names_count;
	const u16 argc = cond->argc;
	const u16 envc = cond->envc;
	unsigned int i;
	const struct tomoyo_condition_element *condp
		= (const struct tomoyo_condition_element *) (cond + 1);
	struct tomoyo_number_union *numbers_p
		= (struct tomoyo_number_union *) (condp + condc);
	struct tomoyo_name_union *names_p
		= (struct tomoyo_name_union *) (numbers_p + numbers_count);
	const struct tomoyo_argv *argv
		= (const struct tomoyo_argv *) (names_p + names_count);
	const struct tomoyo_envp *envp
		= (const struct tomoyo_envp *) (argv + argc);
	for (i = 0; i < numbers_count; i++)
		tomoyo_put_number_union(numbers_p++);
	for (i = 0; i < names_count; i++)
		tomoyo_put_name_union(names_p++);
	for (i = 0; i < argc; argv++, i++)
		tomoyo_put_name(argv->value);
	for (i = 0; i < envc; envp++, i++) {
		tomoyo_put_name(envp->name);
		tomoyo_put_name(envp->value);
	}
}

/**
 * tomoyo_del_name - Delete members in "struct tomoyo_name".
 *
 * @element: Pointer to "struct list_head".
 *
 * Returns nothing.
 */
static inline void tomoyo_del_name(struct list_head *element)
{
	/* Nothing to do. */
}

/**
 * tomoyo_del_path_group - Delete members in "struct tomoyo_path_group".
 *
 * @element: Pointer to "struct list_head".
 *
 * Returns nothing.
 */
static inline void tomoyo_del_path_group(struct list_head *element)
{
	struct tomoyo_path_group *member =
		container_of(element, typeof(*member), head.list);
	tomoyo_put_name(member->member_name);
}

/**
 * tomoyo_del_group - Delete "struct tomoyo_group".
 *
 * @element: Pointer to "struct list_head".
 *
 * Returns nothing.
 */
static inline void tomoyo_del_group(struct list_head *element)
{
	struct tomoyo_group *group =
		container_of(element, typeof(*group), head.list);
	tomoyo_put_name(group->group_name);
}

/**
 * tomoyo_del_address_group - Delete members in "struct tomoyo_address_group".
 *
 * @element: Pointer to "struct list_head".
 *
 * Returns nothing.
 */
static inline void tomoyo_del_address_group(struct list_head *element)
{
	/* Nothing to do. */
}

/**
 * tomoyo_del_number_group - Delete members in "struct tomoyo_number_group".
 *
 * @element: Pointer to "struct list_head".
 *
 * Returns nothing.
 */
static inline void tomoyo_del_number_group(struct list_head *element)
{
	/* Nothing to do. */
}

/**
 * tomoyo_try_to_gc - Try to kfree() an entry.
 *
 * @type:    One of values in "enum tomoyo_policy_id".
 * @element: Pointer to "struct list_head".
 *
 * Returns nothing.
 *
 * Caller holds tomoyo_policy_lock mutex.
 */
static void tomoyo_try_to_gc(const enum tomoyo_policy_id type,
			     struct list_head *element)
{
	/*
	 * __list_del_entry() guarantees that the list element became no longer
	 * reachable from the list which the element was originally on (e.g.
	 * tomoyo_domain_list). Also, synchronize_srcu() guarantees that the
	 * list element became no longer referenced by syscall users.
	 */
	__list_del_entry(element);
	mutex_unlock(&tomoyo_policy_lock);
	synchronize_srcu(&tomoyo_ss);
	/*
	 * However, there are two users which may still be using the list
	 * element. We need to defer until both users forget this element.
	 *
	 * Don't kfree() until "struct tomoyo_io_buffer"->r.{domain,group,acl}
	 * and "struct tomoyo_io_buffer"->w.domain forget this element.
	 */
	if (tomoyo_struct_used_by_io_buffer(element))
		goto reinject;
	switch (type) {
	case TOMOYO_ID_TRANSITION_CONTROL:
		tomoyo_del_transition_control(element);
		break;
	case TOMOYO_ID_MANAGER:
		tomoyo_del_manager(element);
		break;
	case TOMOYO_ID_AGGREGATOR:
		tomoyo_del_aggregator(element);
		break;
	case TOMOYO_ID_GROUP:
		tomoyo_del_group(element);
		break;
	case TOMOYO_ID_PATH_GROUP:
		tomoyo_del_path_group(element);
		break;
	case TOMOYO_ID_ADDRESS_GROUP:
		tomoyo_del_address_group(element);
		break;
	case TOMOYO_ID_NUMBER_GROUP:
		tomoyo_del_number_group(element);
		break;
	case TOMOYO_ID_CONDITION:
		tomoyo_del_condition(element);
		break;
	case TOMOYO_ID_NAME:
		/*
		 * Don't kfree() until all "struct tomoyo_io_buffer"->r.w[]
		 * forget this element.
		 */
		if (tomoyo_name_used_by_io_buffer
		    (container_of(element, typeof(struct tomoyo_name),
				  head.list)->entry.name))
			goto reinject;
		tomoyo_del_name(element);
		break;
	case TOMOYO_ID_ACL:
		tomoyo_del_acl(element);
		break;
	case TOMOYO_ID_DOMAIN:
		/*
		 * Don't kfree() until all "struct cred"->security forget this
		 * element.
		 */
		if (atomic_read(&container_of
				(element, typeof(struct tomoyo_domain_info),
				 list)->users))
			goto reinject;
		tomoyo_del_domain(element);
		break;
	case TOMOYO_MAX_POLICY:
		break;
	}
	mutex_lock(&tomoyo_policy_lock);
	tomoyo_memory_free(element);
	return;
reinject:
	/*
	 * We can safely reinject this element here bacause
	 * (1) Appending list elements and removing list elements are protected
	 *     by tomoyo_policy_lock mutex.
	 * (2) Only this function removes list elements and this function is
	 *     exclusively executed by tomoyo_gc_mutex mutex.
	 * are true.
	 */
	mutex_lock(&tomoyo_policy_lock);
	list_add_rcu(element, element->prev);
}

/**
 * tomoyo_collect_member - Delete elements with "struct tomoyo_acl_head".
 *
 * @id:          One of values in "enum tomoyo_policy_id".
 * @member_list: Pointer to "struct list_head".
 *
 * Returns nothing.
 */
static void tomoyo_collect_member(const enum tomoyo_policy_id id,
				  struct list_head *member_list)
{
	struct tomoyo_acl_head *member;
	struct tomoyo_acl_head *tmp;
	list_for_each_entry_safe(member, tmp, member_list, list) {
		if (!member->is_deleted)
			continue;
		member->is_deleted = TOMOYO_GC_IN_PROGRESS;
		tomoyo_try_to_gc(id, &member->list);
	}
}

/**
 * tomoyo_collect_acl - Delete elements in "struct tomoyo_domain_info".
 *
 * @list: Pointer to "struct list_head".
 *
 * Returns nothing.
 */
static void tomoyo_collect_acl(struct list_head *list)
{
	struct tomoyo_acl_info *acl;
	struct tomoyo_acl_info *tmp;
	list_for_each_entry_safe(acl, tmp, list, list) {
		if (!acl->is_deleted)
			continue;
		acl->is_deleted = TOMOYO_GC_IN_PROGRESS;
		tomoyo_try_to_gc(TOMOYO_ID_ACL, &acl->list);
	}
}

/**
 * tomoyo_collect_entry - Try to kfree() deleted elements.
 *
 * Returns nothing.
 */
static void tomoyo_collect_entry(void)
{
	int i;
	enum tomoyo_policy_id id;
	struct tomoyo_policy_namespace *ns;
	mutex_lock(&tomoyo_policy_lock);
	{
		struct tomoyo_domain_info *domain;
		struct tomoyo_domain_info *tmp;
		list_for_each_entry_safe(domain, tmp, &tomoyo_domain_list,
					 list) {
			tomoyo_collect_acl(&domain->acl_info_list);
			if (!domain->is_deleted || atomic_read(&domain->users))
				continue;
			tomoyo_try_to_gc(TOMOYO_ID_DOMAIN, &domain->list);
		}
	}
	list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {
		for (id = 0; id < TOMOYO_MAX_POLICY; id++)
			tomoyo_collect_member(id, &ns->policy_list[id]);
		for (i = 0; i < TOMOYO_MAX_ACL_GROUPS; i++)
			tomoyo_collect_acl(&ns->acl_group[i]);
	}
	{
		struct tomoyo_shared_acl_head *ptr;
		struct tomoyo_shared_acl_head *tmp;
		list_for_each_entry_safe(ptr, tmp, &tomoyo_condition_list,
					 list) {
			if (atomic_read(&ptr->users) > 0)
				continue;
			atomic_set(&ptr->users, TOMOYO_GC_IN_PROGRESS);
			tomoyo_try_to_gc(TOMOYO_ID_CONDITION, &ptr->list);
		}
	}
	list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {
		for (i = 0; i < TOMOYO_MAX_GROUP; i++) {
			struct list_head *list = &ns->group_list[i];
			struct tomoyo_group *group;
			struct tomoyo_group *tmp;
			switch (i) {
			case 0:
				id = TOMOYO_ID_PATH_GROUP;
				break;
			case 1:
				id = TOMOYO_ID_NUMBER_GROUP;
				break;
			default:
				id = TOMOYO_ID_ADDRESS_GROUP;
				break;
			}
			list_for_each_entry_safe(group, tmp, list, head.list) {
				tomoyo_collect_member(id, &group->member_list);
				if (!list_empty(&group->member_list) ||
				    atomic_read(&group->head.users) > 0)
					continue;
				atomic_set(&group->head.users,
					   TOMOYO_GC_IN_PROGRESS);
				tomoyo_try_to_gc(TOMOYO_ID_GROUP,
						 &group->head.list);
			}
		}
	}
	for (i = 0; i < TOMOYO_MAX_HASH; i++) {
		struct list_head *list = &tomoyo_name_list[i];
		struct tomoyo_shared_acl_head *ptr;
		struct tomoyo_shared_acl_head *tmp;
		list_for_each_entry_safe(ptr, tmp, list, list) {
			if (atomic_read(&ptr->users) > 0)
				continue;
			atomic_set(&ptr->users, TOMOYO_GC_IN_PROGRESS);
			tomoyo_try_to_gc(TOMOYO_ID_NAME, &ptr->list);
		}
	}
	mutex_unlock(&tomoyo_policy_lock);
}

/**
 * tomoyo_gc_thread - Garbage collector thread function.
 *
 * @unused: Unused.
 *
 * Returns 0.
 */
static int tomoyo_gc_thread(void *unused)
{
	/* Garbage collector thread is exclusive. */
	static DEFINE_MUTEX(tomoyo_gc_mutex);
	if (!mutex_trylock(&tomoyo_gc_mutex))
		goto out;
	tomoyo_collect_entry();
	{
		struct tomoyo_io_buffer *head;
		struct tomoyo_io_buffer *tmp;

		spin_lock(&tomoyo_io_buffer_list_lock);
		list_for_each_entry_safe(head, tmp, &tomoyo_io_buffer_list,
					 list) {
			if (head->users)
				continue;
			list_del(&head->list);
			kfree(head->read_buf);
			kfree(head->write_buf);
			kfree(head);
		}
		spin_unlock(&tomoyo_io_buffer_list_lock);
	}
	mutex_unlock(&tomoyo_gc_mutex);
out:
	/* This acts as do_exit(0). */
	return 0;
}

/**
 * tomoyo_notify_gc - Register/unregister /sys/kernel/security/tomoyo/ users.
 *
 * @head:        Pointer to "struct tomoyo_io_buffer".
 * @is_register: True if register, false if unregister.
 *
 * Returns nothing.
 */
void tomoyo_notify_gc(struct tomoyo_io_buffer *head, const bool is_register)
{
	bool is_write = false;

	spin_lock(&tomoyo_io_buffer_list_lock);
	if (is_register) {
		head->users = 1;
		list_add(&head->list, &tomoyo_io_buffer_list);
	} else {
		is_write = head->write_buf != NULL;
		if (!--head->users) {
			list_del(&head->list);
			kfree(head->read_buf);
			kfree(head->write_buf);
			kfree(head);
		}
	}
	spin_unlock(&tomoyo_io_buffer_list_lock);
	if (is_write) {
		struct task_struct *task = kthread_create(tomoyo_gc_thread,
							  NULL,
							  "GC for TOMOYO");
		if (!IS_ERR(task))
			wake_up_process(task);
	}
}