aboutsummaryrefslogtreecommitdiff
path: root/security/tomoyo/gc.c
blob: 2dd9665af260596ac58259b98b06b5402723e8f7 (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
/*
 * security/tomoyo/gc.c
 *
 * Implementation of the Domain-Based Mandatory Access Control.
 *
 * Copyright (C) 2005-2010  NTT DATA CORPORATION
 *
 */

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

enum tomoyo_gc_id {
	TOMOYO_ID_PATH_GROUP,
	TOMOYO_ID_PATH_GROUP_MEMBER,
	TOMOYO_ID_NUMBER_GROUP,
	TOMOYO_ID_NUMBER_GROUP_MEMBER,
	TOMOYO_ID_DOMAIN_INITIALIZER,
	TOMOYO_ID_DOMAIN_KEEPER,
	TOMOYO_ID_AGGREGATOR,
	TOMOYO_ID_ALIAS,
	TOMOYO_ID_GLOBALLY_READABLE,
	TOMOYO_ID_PATTERN,
	TOMOYO_ID_NO_REWRITE,
	TOMOYO_ID_MANAGER,
	TOMOYO_ID_NAME,
	TOMOYO_ID_ACL,
	TOMOYO_ID_DOMAIN
};

struct tomoyo_gc_entry {
	struct list_head list;
	int type;
	void *element;
};
static LIST_HEAD(tomoyo_gc_queue);
static DEFINE_MUTEX(tomoyo_gc_mutex);

/* Caller holds tomoyo_policy_lock mutex. */
static bool tomoyo_add_to_gc(const int type, void *element)
{
	struct tomoyo_gc_entry *entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
	if (!entry)
		return false;
	entry->type = type;
	entry->element = element;
	list_add(&entry->list, &tomoyo_gc_queue);
	return true;
}

static void tomoyo_del_allow_read
(struct tomoyo_globally_readable_file_entry *ptr)
{
	tomoyo_put_name(ptr->filename);
}

static void tomoyo_del_file_pattern(struct tomoyo_pattern_entry *ptr)
{
	tomoyo_put_name(ptr->pattern);
}

static void tomoyo_del_no_rewrite(struct tomoyo_no_rewrite_entry *ptr)
{
	tomoyo_put_name(ptr->pattern);
}

static void tomoyo_del_domain_initializer
(struct tomoyo_domain_initializer_entry *ptr)
{
	tomoyo_put_name(ptr->domainname);
	tomoyo_put_name(ptr->program);
}

static void tomoyo_del_domain_keeper(struct tomoyo_domain_keeper_entry *ptr)
{
	tomoyo_put_name(ptr->domainname);
	tomoyo_put_name(ptr->program);
}

static void tomoyo_del_aggregator(struct tomoyo_aggregator_entry *ptr)
{
	tomoyo_put_name(ptr->original_name);
	tomoyo_put_name(ptr->aggregated_name);
}

static void tomoyo_del_alias(struct tomoyo_alias_entry *ptr)
{
	tomoyo_put_name(ptr->original_name);
	tomoyo_put_name(ptr->aliased_name);
}

static void tomoyo_del_manager(struct tomoyo_policy_manager_entry *ptr)
{
	tomoyo_put_name(ptr->manager);
}

static void tomoyo_del_acl(struct tomoyo_acl_info *acl)
{
	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_PATH_NUMBER3_ACL:
		{
			struct tomoyo_path_number3_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;
	default:
		printk(KERN_WARNING "Unknown type\n");
		break;
	}
}

static bool tomoyo_del_domain(struct tomoyo_domain_info *domain)
{
	struct tomoyo_acl_info *acl;
	struct tomoyo_acl_info *tmp;
	/*
	 * Since we don't protect whole execve() operation using SRCU,
	 * we need to recheck domain->users at this point.
	 *
	 * (1) Reader starts SRCU section upon execve().
	 * (2) Reader traverses tomoyo_domain_list and finds this domain.
	 * (3) Writer marks this domain as deleted.
	 * (4) Garbage collector removes this domain from tomoyo_domain_list
	 *     because this domain is marked as deleted and used by nobody.
	 * (5) Reader saves reference to this domain into
	 *     "struct linux_binprm"->cred->security .
	 * (6) Reader finishes SRCU section, although execve() operation has
	 *     not finished yet.
	 * (7) Garbage collector waits for SRCU synchronization.
	 * (8) Garbage collector kfree() this domain because this domain is
	 *     used by nobody.
	 * (9) Reader finishes execve() operation and restores this domain from
	 *     "struct linux_binprm"->cred->security.
	 *
	 * By updating domain->users at (5), we can solve this race problem
	 * by rechecking domain->users at (8).
	 */
	if (atomic_read(&domain->users))
		return false;
	list_for_each_entry_safe(acl, tmp, &domain->acl_info_list, list) {
		tomoyo_del_acl(acl);
		tomoyo_memory_free(acl);
	}
	tomoyo_put_name(domain->domainname);
	return true;
}


static void tomoyo_del_name(const struct tomoyo_name_entry *ptr)
{
}

static void tomoyo_del_path_group_member(struct tomoyo_path_group_member
					 *member)
{
	tomoyo_put_name(member->member_name);
}

static void tomoyo_del_path_group(struct tomoyo_path_group *group)
{
	tomoyo_put_name(group->group_name);
}

static void tomoyo_del_number_group_member(struct tomoyo_number_group_member
					   *member)
{
}

static void tomoyo_del_number_group(struct tomoyo_number_group *group)
{
	tomoyo_put_name(group->group_name);
}

static void tomoyo_collect_entry(void)
{
	if (mutex_lock_interruptible(&tomoyo_policy_lock))
		return;
	{
		struct tomoyo_globally_readable_file_entry *ptr;
		list_for_each_entry_rcu(ptr, &tomoyo_globally_readable_list,
					head.list) {
			if (!ptr->head.is_deleted)
				continue;
			if (tomoyo_add_to_gc(TOMOYO_ID_GLOBALLY_READABLE, ptr))
				list_del_rcu(&ptr->head.list);
			else
				break;
		}
	}
	{
		struct tomoyo_pattern_entry *ptr;
		list_for_each_entry_rcu(ptr, &tomoyo_pattern_list, head.list) {
			if (!ptr->head.is_deleted)
				continue;
			if (tomoyo_add_to_gc(TOMOYO_ID_PATTERN, ptr))
				list_del_rcu(&ptr->head.list);
			else
				break;
		}
	}
	{
		struct tomoyo_no_rewrite_entry *ptr;
		list_for_each_entry_rcu(ptr, &tomoyo_no_rewrite_list,
					head.list) {
			if (!ptr->head.is_deleted)
				continue;
			if (tomoyo_add_to_gc(TOMOYO_ID_NO_REWRITE, ptr))
				list_del_rcu(&ptr->head.list);
			else
				break;
		}
	}
	{
		struct tomoyo_domain_initializer_entry *ptr;
		list_for_each_entry_rcu(ptr, &tomoyo_domain_initializer_list,
					head.list) {
			if (!ptr->head.is_deleted)
				continue;
			if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN_INITIALIZER, ptr))
				list_del_rcu(&ptr->head.list);
			else
				break;
		}
	}
	{
		struct tomoyo_domain_keeper_entry *ptr;
		list_for_each_entry_rcu(ptr, &tomoyo_domain_keeper_list,
					head.list) {
			if (!ptr->head.is_deleted)
				continue;
			if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN_KEEPER, ptr))
				list_del_rcu(&ptr->head.list);
			else
				break;
		}
	}
	{
		struct tomoyo_aggregator_entry *ptr;
		list_for_each_entry_rcu(ptr, &tomoyo_aggregator_list,
					head.list) {
			if (!ptr->head.is_deleted)
				continue;
			if (tomoyo_add_to_gc(TOMOYO_ID_AGGREGATOR, ptr))
				list_del_rcu(&ptr->head.list);
			else
				break;
		}
	}
	{
		struct tomoyo_alias_entry *ptr;
		list_for_each_entry_rcu(ptr, &tomoyo_alias_list, head.list) {
			if (!ptr->head.is_deleted)
				continue;
			if (tomoyo_add_to_gc(TOMOYO_ID_ALIAS, ptr))
				list_del_rcu(&ptr->head.list);
			else
				break;
		}
	}
	{
		struct tomoyo_policy_manager_entry *ptr;
		list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list,
					head.list) {
			if (!ptr->head.is_deleted)
				continue;
			if (tomoyo_add_to_gc(TOMOYO_ID_MANAGER, ptr))
				list_del_rcu(&ptr->head.list);
			else
				break;
		}
	}
	{
		struct tomoyo_domain_info *domain;
		list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
			struct tomoyo_acl_info *acl;
			list_for_each_entry_rcu(acl, &domain->acl_info_list,
						list) {
				if (!acl->is_deleted)
					continue;
				if (tomoyo_add_to_gc(TOMOYO_ID_ACL, acl))
					list_del_rcu(&acl->list);
				else
					break;
			}
			if (!domain->is_deleted || atomic_read(&domain->users))
				continue;
			/*
			 * Nobody is referring this domain. But somebody may
			 * refer this domain after successful execve().
			 * We recheck domain->users after SRCU synchronization.
			 */
			if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN, domain))
				list_del_rcu(&domain->list);
			else
				break;
		}
	}
	{
		int i;
		for (i = 0; i < TOMOYO_MAX_HASH; i++) {
			struct tomoyo_name_entry *ptr;
			list_for_each_entry_rcu(ptr, &tomoyo_name_list[i],
						list) {
				if (atomic_read(&ptr->users))
					continue;
				if (tomoyo_add_to_gc(TOMOYO_ID_NAME, ptr))
					list_del_rcu(&ptr->list);
				else {
					i = TOMOYO_MAX_HASH;
					break;
				}
			}
		}
	}
	{
		struct tomoyo_path_group *group;
		list_for_each_entry_rcu(group, &tomoyo_path_group_list, list) {
			struct tomoyo_path_group_member *member;
			list_for_each_entry_rcu(member, &group->member_list,
						head.list) {
				if (!member->head.is_deleted)
					continue;
				if (tomoyo_add_to_gc(TOMOYO_ID_PATH_GROUP_MEMBER,
						     member))
					list_del_rcu(&member->head.list);
				else
					break;
			}
			if (!list_empty(&group->member_list) ||
			    atomic_read(&group->users))
				continue;
			if (tomoyo_add_to_gc(TOMOYO_ID_PATH_GROUP, group))
				list_del_rcu(&group->list);
			else
				break;
		}
	}
	{
		struct tomoyo_number_group *group;
		list_for_each_entry_rcu(group, &tomoyo_number_group_list, list) {
			struct tomoyo_number_group_member *member;
			list_for_each_entry_rcu(member, &group->member_list,
						head.list) {
				if (!member->head.is_deleted)
					continue;
				if (tomoyo_add_to_gc(TOMOYO_ID_NUMBER_GROUP_MEMBER,
						     member))
					list_del_rcu(&member->head.list);
				else
					break;
			}
			if (!list_empty(&group->member_list) ||
			    atomic_read(&group->users))
				continue;
			if (tomoyo_add_to_gc(TOMOYO_ID_NUMBER_GROUP, group))
				list_del_rcu(&group->list);
			else
				break;
		}
	}
	mutex_unlock(&tomoyo_policy_lock);
}

static void tomoyo_kfree_entry(void)
{
	struct tomoyo_gc_entry *p;
	struct tomoyo_gc_entry *tmp;

	list_for_each_entry_safe(p, tmp, &tomoyo_gc_queue, list) {
		switch (p->type) {
		case TOMOYO_ID_DOMAIN_INITIALIZER:
			tomoyo_del_domain_initializer(p->element);
			break;
		case TOMOYO_ID_DOMAIN_KEEPER:
			tomoyo_del_domain_keeper(p->element);
			break;
		case TOMOYO_ID_AGGREGATOR:
			tomoyo_del_aggregator(p->element);
			break;
		case TOMOYO_ID_ALIAS:
			tomoyo_del_alias(p->element);
			break;
		case TOMOYO_ID_GLOBALLY_READABLE:
			tomoyo_del_allow_read(p->element);
			break;
		case TOMOYO_ID_PATTERN:
			tomoyo_del_file_pattern(p->element);
			break;
		case TOMOYO_ID_NO_REWRITE:
			tomoyo_del_no_rewrite(p->element);
			break;
		case TOMOYO_ID_MANAGER:
			tomoyo_del_manager(p->element);
			break;
		case TOMOYO_ID_NAME:
			tomoyo_del_name(p->element);
			break;
		case TOMOYO_ID_ACL:
			tomoyo_del_acl(p->element);
			break;
		case TOMOYO_ID_DOMAIN:
			if (!tomoyo_del_domain(p->element))
				continue;
			break;
		case TOMOYO_ID_PATH_GROUP_MEMBER:
			tomoyo_del_path_group_member(p->element);
			break;
		case TOMOYO_ID_PATH_GROUP:
			tomoyo_del_path_group(p->element);
			break;
		case TOMOYO_ID_NUMBER_GROUP_MEMBER:
			tomoyo_del_number_group_member(p->element);
			break;
		case TOMOYO_ID_NUMBER_GROUP:
			tomoyo_del_number_group(p->element);
			break;
		default:
			printk(KERN_WARNING "Unknown type\n");
			break;
		}
		tomoyo_memory_free(p->element);
		list_del(&p->list);
		kfree(p);
	}
}

static int tomoyo_gc_thread(void *unused)
{
	daemonize("GC for TOMOYO");
	if (mutex_trylock(&tomoyo_gc_mutex)) {
		int i;
		for (i = 0; i < 10; i++) {
			tomoyo_collect_entry();
			if (list_empty(&tomoyo_gc_queue))
				break;
			synchronize_srcu(&tomoyo_ss);
			tomoyo_kfree_entry();
		}
		mutex_unlock(&tomoyo_gc_mutex);
	}
	do_exit(0);
}

void tomoyo_run_gc(void)
{
	struct task_struct *task = kthread_create(tomoyo_gc_thread, NULL,
						  "GC for TOMOYO");
	if (!IS_ERR(task))
		wake_up_process(task);
}