xref: /linux/security/tomoyo/gc.c (revision ca55b2fef3a9373fcfc30f82fd26bc7fccbda732) 
1 /*
2  * security/tomoyo/gc.c
3  *
4  * Copyright (C) 2005-2011  NTT DATA CORPORATION
5  */
6 
7 #include "common.h"
8 #include <linux/kthread.h>
9 #include <linux/slab.h>
10 
11 /**
12  * tomoyo_memory_free - Free memory for elements.
13  *
14  * @ptr:  Pointer to allocated memory.
15  *
16  * Returns nothing.
17  *
18  * Caller holds tomoyo_policy_lock mutex.
19  */
20 static inline void tomoyo_memory_free(void *ptr)
21 {
22 	tomoyo_memory_used[TOMOYO_MEMORY_POLICY] -= ksize(ptr);
23 	kfree(ptr);
24 }
25 
26 /* The list for "struct tomoyo_io_buffer". */
27 static LIST_HEAD(tomoyo_io_buffer_list);
28 /* Lock for protecting tomoyo_io_buffer_list. */
29 static DEFINE_SPINLOCK(tomoyo_io_buffer_list_lock);
30 
31 /**
32  * tomoyo_struct_used_by_io_buffer - Check whether the list element is used by /sys/kernel/security/tomoyo/ users or not.
33  *
34  * @element: Pointer to "struct list_head".
35  *
36  * Returns true if @element is used by /sys/kernel/security/tomoyo/ users,
37  * false otherwise.
38  */
39 static bool tomoyo_struct_used_by_io_buffer(const struct list_head *element)
40 {
41 	struct tomoyo_io_buffer *head;
42 	bool in_use = false;
43 
44 	spin_lock(&tomoyo_io_buffer_list_lock);
45 	list_for_each_entry(head, &tomoyo_io_buffer_list, list) {
46 		head->users++;
47 		spin_unlock(&tomoyo_io_buffer_list_lock);
48 		mutex_lock(&head->io_sem);
49 		if (head->r.domain == element || head->r.group == element ||
50 		    head->r.acl == element || &head->w.domain->list == element)
51 			in_use = true;
52 		mutex_unlock(&head->io_sem);
53 		spin_lock(&tomoyo_io_buffer_list_lock);
54 		head->users--;
55 		if (in_use)
56 			break;
57 	}
58 	spin_unlock(&tomoyo_io_buffer_list_lock);
59 	return in_use;
60 }
61 
62 /**
63  * tomoyo_name_used_by_io_buffer - Check whether the string is used by /sys/kernel/security/tomoyo/ users or not.
64  *
65  * @string: String to check.
66  *
67  * Returns true if @string is used by /sys/kernel/security/tomoyo/ users,
68  * false otherwise.
69  */
70 static bool tomoyo_name_used_by_io_buffer(const char *string)
71 {
72 	struct tomoyo_io_buffer *head;
73 	const size_t size = strlen(string) + 1;
74 	bool in_use = false;
75 
76 	spin_lock(&tomoyo_io_buffer_list_lock);
77 	list_for_each_entry(head, &tomoyo_io_buffer_list, list) {
78 		int i;
79 		head->users++;
80 		spin_unlock(&tomoyo_io_buffer_list_lock);
81 		mutex_lock(&head->io_sem);
82 		for (i = 0; i < TOMOYO_MAX_IO_READ_QUEUE; i++) {
83 			const char *w = head->r.w[i];
84 			if (w < string || w > string + size)
85 				continue;
86 			in_use = true;
87 			break;
88 		}
89 		mutex_unlock(&head->io_sem);
90 		spin_lock(&tomoyo_io_buffer_list_lock);
91 		head->users--;
92 		if (in_use)
93 			break;
94 	}
95 	spin_unlock(&tomoyo_io_buffer_list_lock);
96 	return in_use;
97 }
98 
99 /**
100  * tomoyo_del_transition_control - Delete members in "struct tomoyo_transition_control".
101  *
102  * @element: Pointer to "struct list_head".
103  *
104  * Returns nothing.
105  */
106 static inline void tomoyo_del_transition_control(struct list_head *element)
107 {
108 	struct tomoyo_transition_control *ptr =
109 		container_of(element, typeof(*ptr), head.list);
110 	tomoyo_put_name(ptr->domainname);
111 	tomoyo_put_name(ptr->program);
112 }
113 
114 /**
115  * tomoyo_del_aggregator - Delete members in "struct tomoyo_aggregator".
116  *
117  * @element: Pointer to "struct list_head".
118  *
119  * Returns nothing.
120  */
121 static inline void tomoyo_del_aggregator(struct list_head *element)
122 {
123 	struct tomoyo_aggregator *ptr =
124 		container_of(element, typeof(*ptr), head.list);
125 	tomoyo_put_name(ptr->original_name);
126 	tomoyo_put_name(ptr->aggregated_name);
127 }
128 
129 /**
130  * tomoyo_del_manager - Delete members in "struct tomoyo_manager".
131  *
132  * @element: Pointer to "struct list_head".
133  *
134  * Returns nothing.
135  */
136 static inline void tomoyo_del_manager(struct list_head *element)
137 {
138 	struct tomoyo_manager *ptr =
139 		container_of(element, typeof(*ptr), head.list);
140 	tomoyo_put_name(ptr->manager);
141 }
142 
143 /**
144  * tomoyo_del_acl - Delete members in "struct tomoyo_acl_info".
145  *
146  * @element: Pointer to "struct list_head".
147  *
148  * Returns nothing.
149  */
150 static void tomoyo_del_acl(struct list_head *element)
151 {
152 	struct tomoyo_acl_info *acl =
153 		container_of(element, typeof(*acl), list);
154 	tomoyo_put_condition(acl->cond);
155 	switch (acl->type) {
156 	case TOMOYO_TYPE_PATH_ACL:
157 		{
158 			struct tomoyo_path_acl *entry
159 				= container_of(acl, typeof(*entry), head);
160 			tomoyo_put_name_union(&entry->name);
161 		}
162 		break;
163 	case TOMOYO_TYPE_PATH2_ACL:
164 		{
165 			struct tomoyo_path2_acl *entry
166 				= container_of(acl, typeof(*entry), head);
167 			tomoyo_put_name_union(&entry->name1);
168 			tomoyo_put_name_union(&entry->name2);
169 		}
170 		break;
171 	case TOMOYO_TYPE_PATH_NUMBER_ACL:
172 		{
173 			struct tomoyo_path_number_acl *entry
174 				= container_of(acl, typeof(*entry), head);
175 			tomoyo_put_name_union(&entry->name);
176 			tomoyo_put_number_union(&entry->number);
177 		}
178 		break;
179 	case TOMOYO_TYPE_MKDEV_ACL:
180 		{
181 			struct tomoyo_mkdev_acl *entry
182 				= container_of(acl, typeof(*entry), head);
183 			tomoyo_put_name_union(&entry->name);
184 			tomoyo_put_number_union(&entry->mode);
185 			tomoyo_put_number_union(&entry->major);
186 			tomoyo_put_number_union(&entry->minor);
187 		}
188 		break;
189 	case TOMOYO_TYPE_MOUNT_ACL:
190 		{
191 			struct tomoyo_mount_acl *entry
192 				= container_of(acl, typeof(*entry), head);
193 			tomoyo_put_name_union(&entry->dev_name);
194 			tomoyo_put_name_union(&entry->dir_name);
195 			tomoyo_put_name_union(&entry->fs_type);
196 			tomoyo_put_number_union(&entry->flags);
197 		}
198 		break;
199 	case TOMOYO_TYPE_ENV_ACL:
200 		{
201 			struct tomoyo_env_acl *entry =
202 				container_of(acl, typeof(*entry), head);
203 
204 			tomoyo_put_name(entry->env);
205 		}
206 		break;
207 	case TOMOYO_TYPE_INET_ACL:
208 		{
209 			struct tomoyo_inet_acl *entry =
210 				container_of(acl, typeof(*entry), head);
211 
212 			tomoyo_put_group(entry->address.group);
213 			tomoyo_put_number_union(&entry->port);
214 		}
215 		break;
216 	case TOMOYO_TYPE_UNIX_ACL:
217 		{
218 			struct tomoyo_unix_acl *entry =
219 				container_of(acl, typeof(*entry), head);
220 
221 			tomoyo_put_name_union(&entry->name);
222 		}
223 		break;
224 	case TOMOYO_TYPE_MANUAL_TASK_ACL:
225 		{
226 			struct tomoyo_task_acl *entry =
227 				container_of(acl, typeof(*entry), head);
228 			tomoyo_put_name(entry->domainname);
229 		}
230 		break;
231 	}
232 }
233 
234 /**
235  * tomoyo_del_domain - Delete members in "struct tomoyo_domain_info".
236  *
237  * @element: Pointer to "struct list_head".
238  *
239  * Returns nothing.
240  *
241  * Caller holds tomoyo_policy_lock mutex.
242  */
243 static inline void tomoyo_del_domain(struct list_head *element)
244 {
245 	struct tomoyo_domain_info *domain =
246 		container_of(element, typeof(*domain), list);
247 	struct tomoyo_acl_info *acl;
248 	struct tomoyo_acl_info *tmp;
249 	/*
250 	 * Since this domain is referenced from neither
251 	 * "struct tomoyo_io_buffer" nor "struct cred"->security, we can delete
252 	 * elements without checking for is_deleted flag.
253 	 */
254 	list_for_each_entry_safe(acl, tmp, &domain->acl_info_list, list) {
255 		tomoyo_del_acl(&acl->list);
256 		tomoyo_memory_free(acl);
257 	}
258 	tomoyo_put_name(domain->domainname);
259 }
260 
261 /**
262  * tomoyo_del_condition - Delete members in "struct tomoyo_condition".
263  *
264  * @element: Pointer to "struct list_head".
265  *
266  * Returns nothing.
267  */
268 void tomoyo_del_condition(struct list_head *element)
269 {
270 	struct tomoyo_condition *cond = container_of(element, typeof(*cond),
271 						     head.list);
272 	const u16 condc = cond->condc;
273 	const u16 numbers_count = cond->numbers_count;
274 	const u16 names_count = cond->names_count;
275 	const u16 argc = cond->argc;
276 	const u16 envc = cond->envc;
277 	unsigned int i;
278 	const struct tomoyo_condition_element *condp
279 		= (const struct tomoyo_condition_element *) (cond + 1);
280 	struct tomoyo_number_union *numbers_p
281 		= (struct tomoyo_number_union *) (condp + condc);
282 	struct tomoyo_name_union *names_p
283 		= (struct tomoyo_name_union *) (numbers_p + numbers_count);
284 	const struct tomoyo_argv *argv
285 		= (const struct tomoyo_argv *) (names_p + names_count);
286 	const struct tomoyo_envp *envp
287 		= (const struct tomoyo_envp *) (argv + argc);
288 	for (i = 0; i < numbers_count; i++)
289 		tomoyo_put_number_union(numbers_p++);
290 	for (i = 0; i < names_count; i++)
291 		tomoyo_put_name_union(names_p++);
292 	for (i = 0; i < argc; argv++, i++)
293 		tomoyo_put_name(argv->value);
294 	for (i = 0; i < envc; envp++, i++) {
295 		tomoyo_put_name(envp->name);
296 		tomoyo_put_name(envp->value);
297 	}
298 }
299 
300 /**
301  * tomoyo_del_name - Delete members in "struct tomoyo_name".
302  *
303  * @element: Pointer to "struct list_head".
304  *
305  * Returns nothing.
306  */
307 static inline void tomoyo_del_name(struct list_head *element)
308 {
309 	/* Nothing to do. */
310 }
311 
312 /**
313  * tomoyo_del_path_group - Delete members in "struct tomoyo_path_group".
314  *
315  * @element: Pointer to "struct list_head".
316  *
317  * Returns nothing.
318  */
319 static inline void tomoyo_del_path_group(struct list_head *element)
320 {
321 	struct tomoyo_path_group *member =
322 		container_of(element, typeof(*member), head.list);
323 	tomoyo_put_name(member->member_name);
324 }
325 
326 /**
327  * tomoyo_del_group - Delete "struct tomoyo_group".
328  *
329  * @element: Pointer to "struct list_head".
330  *
331  * Returns nothing.
332  */
333 static inline void tomoyo_del_group(struct list_head *element)
334 {
335 	struct tomoyo_group *group =
336 		container_of(element, typeof(*group), head.list);
337 	tomoyo_put_name(group->group_name);
338 }
339 
340 /**
341  * tomoyo_del_address_group - Delete members in "struct tomoyo_address_group".
342  *
343  * @element: Pointer to "struct list_head".
344  *
345  * Returns nothing.
346  */
347 static inline void tomoyo_del_address_group(struct list_head *element)
348 {
349 	/* Nothing to do. */
350 }
351 
352 /**
353  * tomoyo_del_number_group - Delete members in "struct tomoyo_number_group".
354  *
355  * @element: Pointer to "struct list_head".
356  *
357  * Returns nothing.
358  */
359 static inline void tomoyo_del_number_group(struct list_head *element)
360 {
361 	/* Nothing to do. */
362 }
363 
364 /**
365  * tomoyo_try_to_gc - Try to kfree() an entry.
366  *
367  * @type:    One of values in "enum tomoyo_policy_id".
368  * @element: Pointer to "struct list_head".
369  *
370  * Returns nothing.
371  *
372  * Caller holds tomoyo_policy_lock mutex.
373  */
374 static void tomoyo_try_to_gc(const enum tomoyo_policy_id type,
375 			     struct list_head *element)
376 {
377 	/*
378 	 * __list_del_entry() guarantees that the list element became no longer
379 	 * reachable from the list which the element was originally on (e.g.
380 	 * tomoyo_domain_list). Also, synchronize_srcu() guarantees that the
381 	 * list element became no longer referenced by syscall users.
382 	 */
383 	__list_del_entry(element);
384 	mutex_unlock(&tomoyo_policy_lock);
385 	synchronize_srcu(&tomoyo_ss);
386 	/*
387 	 * However, there are two users which may still be using the list
388 	 * element. We need to defer until both users forget this element.
389 	 *
390 	 * Don't kfree() until "struct tomoyo_io_buffer"->r.{domain,group,acl}
391 	 * and "struct tomoyo_io_buffer"->w.domain forget this element.
392 	 */
393 	if (tomoyo_struct_used_by_io_buffer(element))
394 		goto reinject;
395 	switch (type) {
396 	case TOMOYO_ID_TRANSITION_CONTROL:
397 		tomoyo_del_transition_control(element);
398 		break;
399 	case TOMOYO_ID_MANAGER:
400 		tomoyo_del_manager(element);
401 		break;
402 	case TOMOYO_ID_AGGREGATOR:
403 		tomoyo_del_aggregator(element);
404 		break;
405 	case TOMOYO_ID_GROUP:
406 		tomoyo_del_group(element);
407 		break;
408 	case TOMOYO_ID_PATH_GROUP:
409 		tomoyo_del_path_group(element);
410 		break;
411 	case TOMOYO_ID_ADDRESS_GROUP:
412 		tomoyo_del_address_group(element);
413 		break;
414 	case TOMOYO_ID_NUMBER_GROUP:
415 		tomoyo_del_number_group(element);
416 		break;
417 	case TOMOYO_ID_CONDITION:
418 		tomoyo_del_condition(element);
419 		break;
420 	case TOMOYO_ID_NAME:
421 		/*
422 		 * Don't kfree() until all "struct tomoyo_io_buffer"->r.w[]
423 		 * forget this element.
424 		 */
425 		if (tomoyo_name_used_by_io_buffer
426 		    (container_of(element, typeof(struct tomoyo_name),
427 				  head.list)->entry.name))
428 			goto reinject;
429 		tomoyo_del_name(element);
430 		break;
431 	case TOMOYO_ID_ACL:
432 		tomoyo_del_acl(element);
433 		break;
434 	case TOMOYO_ID_DOMAIN:
435 		/*
436 		 * Don't kfree() until all "struct cred"->security forget this
437 		 * element.
438 		 */
439 		if (atomic_read(&container_of
440 				(element, typeof(struct tomoyo_domain_info),
441 				 list)->users))
442 			goto reinject;
443 		break;
444 	case TOMOYO_MAX_POLICY:
445 		break;
446 	}
447 	mutex_lock(&tomoyo_policy_lock);
448 	if (type == TOMOYO_ID_DOMAIN)
449 		tomoyo_del_domain(element);
450 	tomoyo_memory_free(element);
451 	return;
452 reinject:
453 	/*
454 	 * We can safely reinject this element here bacause
455 	 * (1) Appending list elements and removing list elements are protected
456 	 *     by tomoyo_policy_lock mutex.
457 	 * (2) Only this function removes list elements and this function is
458 	 *     exclusively executed by tomoyo_gc_mutex mutex.
459 	 * are true.
460 	 */
461 	mutex_lock(&tomoyo_policy_lock);
462 	list_add_rcu(element, element->prev);
463 }
464 
465 /**
466  * tomoyo_collect_member - Delete elements with "struct tomoyo_acl_head".
467  *
468  * @id:          One of values in "enum tomoyo_policy_id".
469  * @member_list: Pointer to "struct list_head".
470  *
471  * Returns nothing.
472  */
473 static void tomoyo_collect_member(const enum tomoyo_policy_id id,
474 				  struct list_head *member_list)
475 {
476 	struct tomoyo_acl_head *member;
477 	struct tomoyo_acl_head *tmp;
478 	list_for_each_entry_safe(member, tmp, member_list, list) {
479 		if (!member->is_deleted)
480 			continue;
481 		member->is_deleted = TOMOYO_GC_IN_PROGRESS;
482 		tomoyo_try_to_gc(id, &member->list);
483 	}
484 }
485 
486 /**
487  * tomoyo_collect_acl - Delete elements in "struct tomoyo_domain_info".
488  *
489  * @list: Pointer to "struct list_head".
490  *
491  * Returns nothing.
492  */
493 static void tomoyo_collect_acl(struct list_head *list)
494 {
495 	struct tomoyo_acl_info *acl;
496 	struct tomoyo_acl_info *tmp;
497 	list_for_each_entry_safe(acl, tmp, list, list) {
498 		if (!acl->is_deleted)
499 			continue;
500 		acl->is_deleted = TOMOYO_GC_IN_PROGRESS;
501 		tomoyo_try_to_gc(TOMOYO_ID_ACL, &acl->list);
502 	}
503 }
504 
505 /**
506  * tomoyo_collect_entry - Try to kfree() deleted elements.
507  *
508  * Returns nothing.
509  */
510 static void tomoyo_collect_entry(void)
511 {
512 	int i;
513 	enum tomoyo_policy_id id;
514 	struct tomoyo_policy_namespace *ns;
515 	mutex_lock(&tomoyo_policy_lock);
516 	{
517 		struct tomoyo_domain_info *domain;
518 		struct tomoyo_domain_info *tmp;
519 		list_for_each_entry_safe(domain, tmp, &tomoyo_domain_list,
520 					 list) {
521 			tomoyo_collect_acl(&domain->acl_info_list);
522 			if (!domain->is_deleted || atomic_read(&domain->users))
523 				continue;
524 			tomoyo_try_to_gc(TOMOYO_ID_DOMAIN, &domain->list);
525 		}
526 	}
527 	list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {
528 		for (id = 0; id < TOMOYO_MAX_POLICY; id++)
529 			tomoyo_collect_member(id, &ns->policy_list[id]);
530 		for (i = 0; i < TOMOYO_MAX_ACL_GROUPS; i++)
531 			tomoyo_collect_acl(&ns->acl_group[i]);
532 	}
533 	{
534 		struct tomoyo_shared_acl_head *ptr;
535 		struct tomoyo_shared_acl_head *tmp;
536 		list_for_each_entry_safe(ptr, tmp, &tomoyo_condition_list,
537 					 list) {
538 			if (atomic_read(&ptr->users) > 0)
539 				continue;
540 			atomic_set(&ptr->users, TOMOYO_GC_IN_PROGRESS);
541 			tomoyo_try_to_gc(TOMOYO_ID_CONDITION, &ptr->list);
542 		}
543 	}
544 	list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {
545 		for (i = 0; i < TOMOYO_MAX_GROUP; i++) {
546 			struct list_head *list = &ns->group_list[i];
547 			struct tomoyo_group *group;
548 			struct tomoyo_group *tmp;
549 			switch (i) {
550 			case 0:
551 				id = TOMOYO_ID_PATH_GROUP;
552 				break;
553 			case 1:
554 				id = TOMOYO_ID_NUMBER_GROUP;
555 				break;
556 			default:
557 				id = TOMOYO_ID_ADDRESS_GROUP;
558 				break;
559 			}
560 			list_for_each_entry_safe(group, tmp, list, head.list) {
561 				tomoyo_collect_member(id, &group->member_list);
562 				if (!list_empty(&group->member_list) ||
563 				    atomic_read(&group->head.users) > 0)
564 					continue;
565 				atomic_set(&group->head.users,
566 					   TOMOYO_GC_IN_PROGRESS);
567 				tomoyo_try_to_gc(TOMOYO_ID_GROUP,
568 						 &group->head.list);
569 			}
570 		}
571 	}
572 	for (i = 0; i < TOMOYO_MAX_HASH; i++) {
573 		struct list_head *list = &tomoyo_name_list[i];
574 		struct tomoyo_shared_acl_head *ptr;
575 		struct tomoyo_shared_acl_head *tmp;
576 		list_for_each_entry_safe(ptr, tmp, list, list) {
577 			if (atomic_read(&ptr->users) > 0)
578 				continue;
579 			atomic_set(&ptr->users, TOMOYO_GC_IN_PROGRESS);
580 			tomoyo_try_to_gc(TOMOYO_ID_NAME, &ptr->list);
581 		}
582 	}
583 	mutex_unlock(&tomoyo_policy_lock);
584 }
585 
586 /**
587  * tomoyo_gc_thread - Garbage collector thread function.
588  *
589  * @unused: Unused.
590  *
591  * Returns 0.
592  */
593 static int tomoyo_gc_thread(void *unused)
594 {
595 	/* Garbage collector thread is exclusive. */
596 	static DEFINE_MUTEX(tomoyo_gc_mutex);
597 	if (!mutex_trylock(&tomoyo_gc_mutex))
598 		goto out;
599 	tomoyo_collect_entry();
600 	{
601 		struct tomoyo_io_buffer *head;
602 		struct tomoyo_io_buffer *tmp;
603 
604 		spin_lock(&tomoyo_io_buffer_list_lock);
605 		list_for_each_entry_safe(head, tmp, &tomoyo_io_buffer_list,
606 					 list) {
607 			if (head->users)
608 				continue;
609 			list_del(&head->list);
610 			kfree(head->read_buf);
611 			kfree(head->write_buf);
612 			kfree(head);
613 		}
614 		spin_unlock(&tomoyo_io_buffer_list_lock);
615 	}
616 	mutex_unlock(&tomoyo_gc_mutex);
617 out:
618 	/* This acts as do_exit(0). */
619 	return 0;
620 }
621 
622 /**
623  * tomoyo_notify_gc - Register/unregister /sys/kernel/security/tomoyo/ users.
624  *
625  * @head:        Pointer to "struct tomoyo_io_buffer".
626  * @is_register: True if register, false if unregister.
627  *
628  * Returns nothing.
629  */
630 void tomoyo_notify_gc(struct tomoyo_io_buffer *head, const bool is_register)
631 {
632 	bool is_write = false;
633 
634 	spin_lock(&tomoyo_io_buffer_list_lock);
635 	if (is_register) {
636 		head->users = 1;
637 		list_add(&head->list, &tomoyo_io_buffer_list);
638 	} else {
639 		is_write = head->write_buf != NULL;
640 		if (!--head->users) {
641 			list_del(&head->list);
642 			kfree(head->read_buf);
643 			kfree(head->write_buf);
644 			kfree(head);
645 		}
646 	}
647 	spin_unlock(&tomoyo_io_buffer_list_lock);
648 	if (is_write) {
649 		struct task_struct *task = kthread_create(tomoyo_gc_thread,
650 							  NULL,
651 							  "GC for TOMOYO");
652 		if (!IS_ERR(task))
653 			wake_up_process(task);
654 	}
655 }
656