gc.c revision a427fd14d3edf6396c4b9638dbc8e2972afaa05b 
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 */
20static 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". */
27static LIST_HEAD(tomoyo_io_buffer_list);
28/* Lock for protecting tomoyo_io_buffer_list. */
29static 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 */
39static 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 */
70static 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 */
106static 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 */
121static 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 */
136static 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 */
150static 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	}
225}
226
227/**
228 * tomoyo_del_domain - Delete members in "struct tomoyo_domain_info".
229 *
230 * @element: Pointer to "struct list_head".
231 *
232 * Returns nothing.
233 *
234 * Caller holds tomoyo_policy_lock mutex.
235 */
236static inline void tomoyo_del_domain(struct list_head *element)
237{
238	struct tomoyo_domain_info *domain =
239		container_of(element, typeof(*domain), list);
240	struct tomoyo_acl_info *acl;
241	struct tomoyo_acl_info *tmp;
242	/*
243	 * Since this domain is referenced from neither
244	 * "struct tomoyo_io_buffer" nor "struct cred"->security, we can delete
245	 * elements without checking for is_deleted flag.
246	 */
247	list_for_each_entry_safe(acl, tmp, &domain->acl_info_list, list) {
248		tomoyo_del_acl(&acl->list);
249		tomoyo_memory_free(acl);
250	}
251	tomoyo_put_name(domain->domainname);
252}
253
254/**
255 * tomoyo_del_condition - Delete members in "struct tomoyo_condition".
256 *
257 * @element: Pointer to "struct list_head".
258 *
259 * Returns nothing.
260 */
261void tomoyo_del_condition(struct list_head *element)
262{
263	struct tomoyo_condition *cond = container_of(element, typeof(*cond),
264						     head.list);
265	const u16 condc = cond->condc;
266	const u16 numbers_count = cond->numbers_count;
267	const u16 names_count = cond->names_count;
268	const u16 argc = cond->argc;
269	const u16 envc = cond->envc;
270	unsigned int i;
271	const struct tomoyo_condition_element *condp
272		= (const struct tomoyo_condition_element *) (cond + 1);
273	struct tomoyo_number_union *numbers_p
274		= (struct tomoyo_number_union *) (condp + condc);
275	struct tomoyo_name_union *names_p
276		= (struct tomoyo_name_union *) (numbers_p + numbers_count);
277	const struct tomoyo_argv *argv
278		= (const struct tomoyo_argv *) (names_p + names_count);
279	const struct tomoyo_envp *envp
280		= (const struct tomoyo_envp *) (argv + argc);
281	for (i = 0; i < numbers_count; i++)
282		tomoyo_put_number_union(numbers_p++);
283	for (i = 0; i < names_count; i++)
284		tomoyo_put_name_union(names_p++);
285	for (i = 0; i < argc; argv++, i++)
286		tomoyo_put_name(argv->value);
287	for (i = 0; i < envc; envp++, i++) {
288		tomoyo_put_name(envp->name);
289		tomoyo_put_name(envp->value);
290	}
291}
292
293/**
294 * tomoyo_del_name - Delete members in "struct tomoyo_name".
295 *
296 * @element: Pointer to "struct list_head".
297 *
298 * Returns nothing.
299 */
300static inline void tomoyo_del_name(struct list_head *element)
301{
302	/* Nothing to do. */
303}
304
305/**
306 * tomoyo_del_path_group - Delete members in "struct tomoyo_path_group".
307 *
308 * @element: Pointer to "struct list_head".
309 *
310 * Returns nothing.
311 */
312static inline void tomoyo_del_path_group(struct list_head *element)
313{
314	struct tomoyo_path_group *member =
315		container_of(element, typeof(*member), head.list);
316	tomoyo_put_name(member->member_name);
317}
318
319/**
320 * tomoyo_del_group - Delete "struct tomoyo_group".
321 *
322 * @element: Pointer to "struct list_head".
323 *
324 * Returns nothing.
325 */
326static inline void tomoyo_del_group(struct list_head *element)
327{
328	struct tomoyo_group *group =
329		container_of(element, typeof(*group), head.list);
330	tomoyo_put_name(group->group_name);
331}
332
333/**
334 * tomoyo_del_address_group - Delete members in "struct tomoyo_address_group".
335 *
336 * @element: Pointer to "struct list_head".
337 *
338 * Returns nothing.
339 */
340static inline void tomoyo_del_address_group(struct list_head *element)
341{
342	/* Nothing to do. */
343}
344
345/**
346 * tomoyo_del_number_group - Delete members in "struct tomoyo_number_group".
347 *
348 * @element: Pointer to "struct list_head".
349 *
350 * Returns nothing.
351 */
352static inline void tomoyo_del_number_group(struct list_head *element)
353{
354	/* Nothing to do. */
355}
356
357/**
358 * tomoyo_try_to_gc - Try to kfree() an entry.
359 *
360 * @type:    One of values in "enum tomoyo_policy_id".
361 * @element: Pointer to "struct list_head".
362 *
363 * Returns nothing.
364 *
365 * Caller holds tomoyo_policy_lock mutex.
366 */
367static void tomoyo_try_to_gc(const enum tomoyo_policy_id type,
368			     struct list_head *element)
369{
370	/*
371	 * __list_del_entry() guarantees that the list element became no longer
372	 * reachable from the list which the element was originally on (e.g.
373	 * tomoyo_domain_list). Also, synchronize_srcu() guarantees that the
374	 * list element became no longer referenced by syscall users.
375	 */
376	__list_del_entry(element);
377	mutex_unlock(&tomoyo_policy_lock);
378	synchronize_srcu(&tomoyo_ss);
379	/*
380	 * However, there are two users which may still be using the list
381	 * element. We need to defer until both users forget this element.
382	 *
383	 * Don't kfree() until "struct tomoyo_io_buffer"->r.{domain,group,acl}
384	 * and "struct tomoyo_io_buffer"->w.domain forget this element.
385	 */
386	if (tomoyo_struct_used_by_io_buffer(element))
387		goto reinject;
388	switch (type) {
389	case TOMOYO_ID_TRANSITION_CONTROL:
390		tomoyo_del_transition_control(element);
391		break;
392	case TOMOYO_ID_MANAGER:
393		tomoyo_del_manager(element);
394		break;
395	case TOMOYO_ID_AGGREGATOR:
396		tomoyo_del_aggregator(element);
397		break;
398	case TOMOYO_ID_GROUP:
399		tomoyo_del_group(element);
400		break;
401	case TOMOYO_ID_PATH_GROUP:
402		tomoyo_del_path_group(element);
403		break;
404	case TOMOYO_ID_ADDRESS_GROUP:
405		tomoyo_del_address_group(element);
406		break;
407	case TOMOYO_ID_NUMBER_GROUP:
408		tomoyo_del_number_group(element);
409		break;
410	case TOMOYO_ID_CONDITION:
411		tomoyo_del_condition(element);
412		break;
413	case TOMOYO_ID_NAME:
414		/*
415		 * Don't kfree() until all "struct tomoyo_io_buffer"->r.w[]
416		 * forget this element.
417		 */
418		if (tomoyo_name_used_by_io_buffer
419		    (container_of(element, typeof(struct tomoyo_name),
420				  head.list)->entry.name))
421			goto reinject;
422		tomoyo_del_name(element);
423		break;
424	case TOMOYO_ID_ACL:
425		tomoyo_del_acl(element);
426		break;
427	case TOMOYO_ID_DOMAIN:
428		/*
429		 * Don't kfree() until all "struct cred"->security forget this
430		 * element.
431		 */
432		if (atomic_read(&container_of
433				(element, typeof(struct tomoyo_domain_info),
434				 list)->users))
435			goto reinject;
436		break;
437	case TOMOYO_MAX_POLICY:
438		break;
439	}
440	mutex_lock(&tomoyo_policy_lock);
441	if (type == TOMOYO_ID_DOMAIN)
442		tomoyo_del_domain(element);
443	tomoyo_memory_free(element);
444	return;
445reinject:
446	/*
447	 * We can safely reinject this element here bacause
448	 * (1) Appending list elements and removing list elements are protected
449	 *     by tomoyo_policy_lock mutex.
450	 * (2) Only this function removes list elements and this function is
451	 *     exclusively executed by tomoyo_gc_mutex mutex.
452	 * are true.
453	 */
454	mutex_lock(&tomoyo_policy_lock);
455	list_add_rcu(element, element->prev);
456}
457
458/**
459 * tomoyo_collect_member - Delete elements with "struct tomoyo_acl_head".
460 *
461 * @id:          One of values in "enum tomoyo_policy_id".
462 * @member_list: Pointer to "struct list_head".
463 *
464 * Returns nothing.
465 */
466static void tomoyo_collect_member(const enum tomoyo_policy_id id,
467				  struct list_head *member_list)
468{
469	struct tomoyo_acl_head *member;
470	struct tomoyo_acl_head *tmp;
471	list_for_each_entry_safe(member, tmp, member_list, list) {
472		if (!member->is_deleted)
473			continue;
474		member->is_deleted = TOMOYO_GC_IN_PROGRESS;
475		tomoyo_try_to_gc(id, &member->list);
476	}
477}
478
479/**
480 * tomoyo_collect_acl - Delete elements in "struct tomoyo_domain_info".
481 *
482 * @list: Pointer to "struct list_head".
483 *
484 * Returns nothing.
485 */
486static void tomoyo_collect_acl(struct list_head *list)
487{
488	struct tomoyo_acl_info *acl;
489	struct tomoyo_acl_info *tmp;
490	list_for_each_entry_safe(acl, tmp, list, list) {
491		if (!acl->is_deleted)
492			continue;
493		acl->is_deleted = TOMOYO_GC_IN_PROGRESS;
494		tomoyo_try_to_gc(TOMOYO_ID_ACL, &acl->list);
495	}
496}
497
498/**
499 * tomoyo_collect_entry - Try to kfree() deleted elements.
500 *
501 * Returns nothing.
502 */
503static void tomoyo_collect_entry(void)
504{
505	int i;
506	enum tomoyo_policy_id id;
507	struct tomoyo_policy_namespace *ns;
508	mutex_lock(&tomoyo_policy_lock);
509	{
510		struct tomoyo_domain_info *domain;
511		struct tomoyo_domain_info *tmp;
512		list_for_each_entry_safe(domain, tmp, &tomoyo_domain_list,
513					 list) {
514			tomoyo_collect_acl(&domain->acl_info_list);
515			if (!domain->is_deleted || atomic_read(&domain->users))
516				continue;
517			tomoyo_try_to_gc(TOMOYO_ID_DOMAIN, &domain->list);
518		}
519	}
520	list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {
521		for (id = 0; id < TOMOYO_MAX_POLICY; id++)
522			tomoyo_collect_member(id, &ns->policy_list[id]);
523		for (i = 0; i < TOMOYO_MAX_ACL_GROUPS; i++)
524			tomoyo_collect_acl(&ns->acl_group[i]);
525	}
526	{
527		struct tomoyo_shared_acl_head *ptr;
528		struct tomoyo_shared_acl_head *tmp;
529		list_for_each_entry_safe(ptr, tmp, &tomoyo_condition_list,
530					 list) {
531			if (atomic_read(&ptr->users) > 0)
532				continue;
533			atomic_set(&ptr->users, TOMOYO_GC_IN_PROGRESS);
534			tomoyo_try_to_gc(TOMOYO_ID_CONDITION, &ptr->list);
535		}
536	}
537	list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {
538		for (i = 0; i < TOMOYO_MAX_GROUP; i++) {
539			struct list_head *list = &ns->group_list[i];
540			struct tomoyo_group *group;
541			struct tomoyo_group *tmp;
542			switch (i) {
543			case 0:
544				id = TOMOYO_ID_PATH_GROUP;
545				break;
546			case 1:
547				id = TOMOYO_ID_NUMBER_GROUP;
548				break;
549			default:
550				id = TOMOYO_ID_ADDRESS_GROUP;
551				break;
552			}
553			list_for_each_entry_safe(group, tmp, list, head.list) {
554				tomoyo_collect_member(id, &group->member_list);
555				if (!list_empty(&group->member_list) ||
556				    atomic_read(&group->head.users) > 0)
557					continue;
558				atomic_set(&group->head.users,
559					   TOMOYO_GC_IN_PROGRESS);
560				tomoyo_try_to_gc(TOMOYO_ID_GROUP,
561						 &group->head.list);
562			}
563		}
564	}
565	for (i = 0; i < TOMOYO_MAX_HASH; i++) {
566		struct list_head *list = &tomoyo_name_list[i];
567		struct tomoyo_shared_acl_head *ptr;
568		struct tomoyo_shared_acl_head *tmp;
569		list_for_each_entry_safe(ptr, tmp, list, list) {
570			if (atomic_read(&ptr->users) > 0)
571				continue;
572			atomic_set(&ptr->users, TOMOYO_GC_IN_PROGRESS);
573			tomoyo_try_to_gc(TOMOYO_ID_NAME, &ptr->list);
574		}
575	}
576	mutex_unlock(&tomoyo_policy_lock);
577}
578
579/**
580 * tomoyo_gc_thread - Garbage collector thread function.
581 *
582 * @unused: Unused.
583 *
584 * Returns 0.
585 */
586static int tomoyo_gc_thread(void *unused)
587{
588	/* Garbage collector thread is exclusive. */
589	static DEFINE_MUTEX(tomoyo_gc_mutex);
590	if (!mutex_trylock(&tomoyo_gc_mutex))
591		goto out;
592	tomoyo_collect_entry();
593	{
594		struct tomoyo_io_buffer *head;
595		struct tomoyo_io_buffer *tmp;
596
597		spin_lock(&tomoyo_io_buffer_list_lock);
598		list_for_each_entry_safe(head, tmp, &tomoyo_io_buffer_list,
599					 list) {
600			if (head->users)
601				continue;
602			list_del(&head->list);
603			kfree(head->read_buf);
604			kfree(head->write_buf);
605			kfree(head);
606		}
607		spin_unlock(&tomoyo_io_buffer_list_lock);
608	}
609	mutex_unlock(&tomoyo_gc_mutex);
610out:
611	/* This acts as do_exit(0). */
612	return 0;
613}
614
615/**
616 * tomoyo_notify_gc - Register/unregister /sys/kernel/security/tomoyo/ users.
617 *
618 * @head:        Pointer to "struct tomoyo_io_buffer".
619 * @is_register: True if register, false if unregister.
620 *
621 * Returns nothing.
622 */
623void tomoyo_notify_gc(struct tomoyo_io_buffer *head, const bool is_register)
624{
625	bool is_write = false;
626
627	spin_lock(&tomoyo_io_buffer_list_lock);
628	if (is_register) {
629		head->users = 1;
630		list_add(&head->list, &tomoyo_io_buffer_list);
631	} else {
632		is_write = head->write_buf != NULL;
633		if (!--head->users) {
634			list_del(&head->list);
635			kfree(head->read_buf);
636			kfree(head->write_buf);
637			kfree(head);
638		}
639	}
640	spin_unlock(&tomoyo_io_buffer_list_lock);
641	if (is_write) {
642		struct task_struct *task = kthread_create(tomoyo_gc_thread,
643							  NULL,
644							  "GC for TOMOYO");
645		if (!IS_ERR(task))
646			wake_up_process(task);
647	}
648}
649