security/tomoyo/gc.c - linux - Git at Google

 /*
  * 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>

 struct tomoyo_gc {
 	struct list_head list;
 	enum tomoyo_policy_id type;
 	struct list_head *element;
 };
 static LIST_HEAD(tomoyo_gc_queue);
 static DEFINE_MUTEX(tomoyo_gc_mutex);

 /**
  * tomoyo_add_to_gc - Add an entry to to be deleted list.
  *
  * @type:    One of values in "enum tomoyo_policy_id".
  * @element: Pointer to "struct list_head".
  *
  * Returns true on success, false otherwise.
  *
  * Caller holds tomoyo_policy_lock mutex.
  *
  * Adding an entry needs kmalloc(). Thus, if we try to add thousands of
  * entries at once, it will take too long time. Thus, do not add more than 128
  * entries per a scan. But to be able to handle worst case where all entries
  * are in-use, we accept one more entry per a scan.
  *
  * If we use singly linked list using "struct list_head"->prev (which is
  * LIST_POISON2), we can avoid kmalloc().
  */
 static bool tomoyo_add_to_gc(const int type, struct list_head *element)
 {
 	struct tomoyo_gc *entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
 	if (!entry)
 		return false;
 	entry->type = type;
 	entry->element = element;
 	list_add(&entry->list, &tomoyo_gc_queue);
 	list_del_rcu(element);
 	return true;
 }

 /**
  * tomoyo_del_transition_control - Delete members in "struct tomoyo_transition_control".
  *
  * @element: Pointer to "struct list_head".
  *
  * Returns nothing.
  */
 static 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 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 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);
 	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;
 	}
 }

 static bool 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 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->list);
 		tomoyo_memory_free(acl);
 	}
 	tomoyo_put_name(domain->domainname);
 	return true;
 }


 /**
  * tomoyo_del_name - Delete members in "struct tomoyo_name".
  *
  * @element: Pointer to "struct list_head".
  *
  * Returns nothing.
  */
 static void tomoyo_del_name(struct list_head *element)
 {
 	const struct tomoyo_name *ptr =
 		container_of(element, typeof(*ptr), head.list);
 }

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

 /**
  * 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 true if some elements are deleted, false otherwise.
  */
 static bool tomoyo_collect_member(const enum tomoyo_policy_id id,
 				  struct list_head *member_list)
 {
 	struct tomoyo_acl_head *member;
 	list_for_each_entry(member, member_list, list) {
 		if (!member->is_deleted)
 			continue;
 		if (!tomoyo_add_to_gc(id, &member->list))
 			return false;
 	}
         return true;
 }

 static bool tomoyo_collect_acl(struct tomoyo_domain_info *domain)
 {
 	struct tomoyo_acl_info *acl;
 	list_for_each_entry(acl, &domain->acl_info_list, list) {
 		if (!acl->is_deleted)
 			continue;
 		if (!tomoyo_add_to_gc(TOMOYO_ID_ACL, &acl->list))
 			return false;
 	}
 	return true;
 }

 /**
  * tomoyo_collect_entry - Scan lists for deleted elements.
  *
  * Returns nothing.
  */
 static void tomoyo_collect_entry(void)
 {
 	int i;
 	if (mutex_lock_interruptible(&tomoyo_policy_lock))
 		return;
 	for (i = 0; i < TOMOYO_MAX_POLICY; i++) {
 		if (!tomoyo_collect_member(i, &tomoyo_policy_list[i]))
 			goto unlock;
 	}
 	{
 		struct tomoyo_domain_info *domain;
 		list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
 			if (!tomoyo_collect_acl(domain))
 				goto unlock;
 			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))
 				goto unlock;
 		}
 	}
 	for (i = 0; i < TOMOYO_MAX_HASH; i++) {
 		struct tomoyo_name *ptr;
 		list_for_each_entry_rcu(ptr, &tomoyo_name_list[i], head.list) {
 			if (atomic_read(&ptr->head.users))
 				continue;
 			if (!tomoyo_add_to_gc(TOMOYO_ID_NAME, &ptr->head.list))
 				goto unlock;
 		}
 	}
 	for (i = 0; i < TOMOYO_MAX_GROUP; i++) {
 		struct list_head *list = &tomoyo_group_list[i];
 		int id;
 		struct tomoyo_group *group;
 		switch (i) {
 		case 0:
 			id = TOMOYO_ID_PATH_GROUP;
 			break;
 		default:
 			id = TOMOYO_ID_NUMBER_GROUP;
 			break;
 		}
 		list_for_each_entry(group, list, head.list) {
 			if (!tomoyo_collect_member(id, &group->member_list))
 				goto unlock;
 			if (!list_empty(&group->member_list) ||
 			    atomic_read(&group->head.users))
 				continue;
 			if (!tomoyo_add_to_gc(TOMOYO_ID_GROUP,
 					      &group->head.list))
 				goto unlock;
 		}
 	}
  unlock:
 	mutex_unlock(&tomoyo_policy_lock);
 }

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

 	list_for_each_entry_safe(p, tmp, &tomoyo_gc_queue, list) {
 		struct list_head *element = p->element;
 		switch (p->type) {
 		case TOMOYO_ID_TRANSITION_CONTROL:
 			tomoyo_del_transition_control(element);
 			break;
 		case TOMOYO_ID_AGGREGATOR:
 			tomoyo_del_aggregator(element);
 			break;
 		case TOMOYO_ID_MANAGER:
 			tomoyo_del_manager(element);
 			break;
 		case TOMOYO_ID_NAME:
 			tomoyo_del_name(element);
 			break;
 		case TOMOYO_ID_ACL:
 			tomoyo_del_acl(element);
 			break;
 		case TOMOYO_ID_DOMAIN:
 			if (!tomoyo_del_domain(element))
 				continue;
 			break;
 		case TOMOYO_ID_PATH_GROUP:
 			tomoyo_del_path_group(element);
 			break;
 		case TOMOYO_ID_GROUP:
 			tomoyo_del_group(element);
 			break;
 		case TOMOYO_ID_NUMBER_GROUP:
 			tomoyo_del_number_group(element);
 			break;
 		case TOMOYO_MAX_POLICY:
 			break;
 		}
 		tomoyo_memory_free(element);
 		list_del(&p->list);
 		kfree(p);
 	}
 }

 /**
  * tomoyo_gc_thread - Garbage collector thread function.
  *
  * @unused: Unused.
  *
  * In case OOM-killer choose this thread for termination, we create this thread
  * as a short live thread whenever /sys/kernel/security/tomoyo/ interface was
  * close()d.
  *
  * Returns 0.
  */
 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);
 }
	/*
	* 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>

	struct tomoyo_gc {
	struct list_head list;
	enum tomoyo_policy_id type;
	struct list_head *element;
	};
	static LIST_HEAD(tomoyo_gc_queue);
	static DEFINE_MUTEX(tomoyo_gc_mutex);

	/**
	* tomoyo_add_to_gc - Add an entry to to be deleted list.
	*
	* @type: One of values in "enum tomoyo_policy_id".
	* @element: Pointer to "struct list_head".
	*
	* Returns true on success, false otherwise.
	*
	* Caller holds tomoyo_policy_lock mutex.
	*
	* Adding an entry needs kmalloc(). Thus, if we try to add thousands of
	* entries at once, it will take too long time. Thus, do not add more than 128
	* entries per a scan. But to be able to handle worst case where all entries
	* are in-use, we accept one more entry per a scan.
	*
	* If we use singly linked list using "struct list_head"->prev (which is
	* LIST_POISON2), we can avoid kmalloc().
	*/
	static bool tomoyo_add_to_gc(const int type, struct list_head *element)
	{
	struct tomoyo_gc entry = kzalloc(sizeof(entry), GFP_ATOMIC);
	if (!entry)
	return false;
	entry->type = type;
	entry->element = element;
	list_add(&entry->list, &tomoyo_gc_queue);
	list_del_rcu(element);
	return true;
	}

	/**
	* tomoyo_del_transition_control - Delete members in "struct tomoyo_transition_control".
	*
	* @element: Pointer to "struct list_head".
	*
	* Returns nothing.
	*/
	static 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 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 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);
	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;
	}
	}

	static bool 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 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->list);
	tomoyo_memory_free(acl);
	}
	tomoyo_put_name(domain->domainname);
	return true;
	}


	/**
	* tomoyo_del_name - Delete members in "struct tomoyo_name".
	*
	* @element: Pointer to "struct list_head".
	*
	* Returns nothing.
	*/
	static void tomoyo_del_name(struct list_head *element)
	{
	const struct tomoyo_name *ptr =
	container_of(element, typeof(*ptr), head.list);
	}

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

	/**
	* 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 true if some elements are deleted, false otherwise.
	*/
	static bool tomoyo_collect_member(const enum tomoyo_policy_id id,
	struct list_head *member_list)
	{
	struct tomoyo_acl_head *member;
	list_for_each_entry(member, member_list, list) {
	if (!member->is_deleted)
	continue;
	if (!tomoyo_add_to_gc(id, &member->list))
	return false;
	}
	return true;
	}

	static bool tomoyo_collect_acl(struct tomoyo_domain_info *domain)
	{
	struct tomoyo_acl_info *acl;
	list_for_each_entry(acl, &domain->acl_info_list, list) {
	if (!acl->is_deleted)
	continue;
	if (!tomoyo_add_to_gc(TOMOYO_ID_ACL, &acl->list))
	return false;
	}
	return true;
	}

	/**
	* tomoyo_collect_entry - Scan lists for deleted elements.
	*
	* Returns nothing.
	*/
	static void tomoyo_collect_entry(void)
	{
	int i;
	if (mutex_lock_interruptible(&tomoyo_policy_lock))
	return;
	for (i = 0; i < TOMOYO_MAX_POLICY; i++) {
	if (!tomoyo_collect_member(i, &tomoyo_policy_list[i]))
	goto unlock;
	}
	{
	struct tomoyo_domain_info *domain;
	list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
	if (!tomoyo_collect_acl(domain))
	goto unlock;
	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))
	goto unlock;
	}
	}
	for (i = 0; i < TOMOYO_MAX_HASH; i++) {
	struct tomoyo_name *ptr;
	list_for_each_entry_rcu(ptr, &tomoyo_name_list[i], head.list) {
	if (atomic_read(&ptr->head.users))
	continue;
	if (!tomoyo_add_to_gc(TOMOYO_ID_NAME, &ptr->head.list))
	goto unlock;
	}
	}
	for (i = 0; i < TOMOYO_MAX_GROUP; i++) {
	struct list_head *list = &tomoyo_group_list[i];
	int id;
	struct tomoyo_group *group;
	switch (i) {
	case 0:
	id = TOMOYO_ID_PATH_GROUP;
	break;
	default:
	id = TOMOYO_ID_NUMBER_GROUP;
	break;
	}
	list_for_each_entry(group, list, head.list) {
	if (!tomoyo_collect_member(id, &group->member_list))
	goto unlock;
	if (!list_empty(&group->member_list) \|\|
	atomic_read(&group->head.users))
	continue;
	if (!tomoyo_add_to_gc(TOMOYO_ID_GROUP,
	&group->head.list))
	goto unlock;
	}
	}
	unlock:
	mutex_unlock(&tomoyo_policy_lock);
	}

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

	list_for_each_entry_safe(p, tmp, &tomoyo_gc_queue, list) {
	struct list_head *element = p->element;
	switch (p->type) {
	case TOMOYO_ID_TRANSITION_CONTROL:
	tomoyo_del_transition_control(element);
	break;
	case TOMOYO_ID_AGGREGATOR:
	tomoyo_del_aggregator(element);
	break;
	case TOMOYO_ID_MANAGER:
	tomoyo_del_manager(element);
	break;
	case TOMOYO_ID_NAME:
	tomoyo_del_name(element);
	break;
	case TOMOYO_ID_ACL:
	tomoyo_del_acl(element);
	break;
	case TOMOYO_ID_DOMAIN:
	if (!tomoyo_del_domain(element))
	continue;
	break;
	case TOMOYO_ID_PATH_GROUP:
	tomoyo_del_path_group(element);
	break;
	case TOMOYO_ID_GROUP:
	tomoyo_del_group(element);
	break;
	case TOMOYO_ID_NUMBER_GROUP:
	tomoyo_del_number_group(element);
	break;
	case TOMOYO_MAX_POLICY:
	break;
	}
	tomoyo_memory_free(element);
	list_del(&p->list);
	kfree(p);
	}
	}

	/**
	* tomoyo_gc_thread - Garbage collector thread function.
	*
	* @unused: Unused.
	*
	* In case OOM-killer choose this thread for termination, we create this thread
	* as a short live thread whenever /sys/kernel/security/tomoyo/ interface was
	* close()d.
	*
	* Returns 0.
	*/
	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);
	}