security/tomoyo/gc.c - kernel/msm-4.9 - Gitiles

 /*
  * 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_policy_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,
 	TOMOYO_MAX_POLICY
 };

 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_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;
 	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 struct list_head *tomoyo_policy_list[TOMOYO_MAX_POLICY] = {
 	[TOMOYO_ID_GLOBALLY_READABLE] = &tomoyo_globally_readable_list,
 	[TOMOYO_ID_PATTERN] = &tomoyo_pattern_list,
 	[TOMOYO_ID_NO_REWRITE] = &tomoyo_no_rewrite_list,
 	[TOMOYO_ID_DOMAIN_INITIALIZER] = &tomoyo_domain_initializer_list,
 	[TOMOYO_ID_DOMAIN_KEEPER] = &tomoyo_domain_keeper_list,
 	[TOMOYO_ID_AGGREGATOR] = &tomoyo_aggregator_list,
 	[TOMOYO_ID_ALIAS] = &tomoyo_alias_list,
 	[TOMOYO_ID_MANAGER] = &tomoyo_policy_manager_list,
 };

 static bool tomoyo_collect_member(struct list_head *member_list, int id)
 {
 	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;
 		list_del_rcu(&member->list);
 	}
         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;
 		list_del_rcu(&acl->list);
 	}
 	return true;
 }

 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_policy_list[i])
 			if (!tomoyo_collect_member(tomoyo_policy_list[i], 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_del_rcu(&domain->list);
 			else
 				goto unlock;
 		}
 	}
 	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
 				goto unlock;
 		}
 	}
 	{
 		struct tomoyo_path_group *group;
 		list_for_each_entry_rcu(group, &tomoyo_path_group_list, list) {
 			tomoyo_collect_member(&group->member_list,
 					      TOMOYO_ID_PATH_GROUP_MEMBER);
 			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
 				goto unlock;
 		}
 	}
 	{
 		struct tomoyo_number_group *group;
 		list_for_each_entry_rcu(group, &tomoyo_number_group_list,
 					list) {
 			tomoyo_collect_member(&group->member_list,
 					      TOMOYO_ID_NUMBER_GROUP_MEMBER);
 			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
 				goto unlock;
 		}
 	}
  unlock:
 	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);
 }
	/*
	* 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_policy_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,
	TOMOYO_MAX_POLICY
	};

	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_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;
	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 struct list_head *tomoyo_policy_list[TOMOYO_MAX_POLICY] = {
	[TOMOYO_ID_GLOBALLY_READABLE] = &tomoyo_globally_readable_list,
	[TOMOYO_ID_PATTERN] = &tomoyo_pattern_list,
	[TOMOYO_ID_NO_REWRITE] = &tomoyo_no_rewrite_list,
	[TOMOYO_ID_DOMAIN_INITIALIZER] = &tomoyo_domain_initializer_list,
	[TOMOYO_ID_DOMAIN_KEEPER] = &tomoyo_domain_keeper_list,
	[TOMOYO_ID_AGGREGATOR] = &tomoyo_aggregator_list,
	[TOMOYO_ID_ALIAS] = &tomoyo_alias_list,
	[TOMOYO_ID_MANAGER] = &tomoyo_policy_manager_list,
	};

	static bool tomoyo_collect_member(struct list_head *member_list, int id)
	{
	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;
	list_del_rcu(&member->list);
	}
	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;
	list_del_rcu(&acl->list);
	}
	return true;
	}

	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_policy_list[i])
	if (!tomoyo_collect_member(tomoyo_policy_list[i], 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_del_rcu(&domain->list);
	else
	goto unlock;
	}
	}
	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
	goto unlock;
	}
	}
	{
	struct tomoyo_path_group *group;
	list_for_each_entry_rcu(group, &tomoyo_path_group_list, list) {
	tomoyo_collect_member(&group->member_list,
	TOMOYO_ID_PATH_GROUP_MEMBER);
	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
	goto unlock;
	}
	}
	{
	struct tomoyo_number_group *group;
	list_for_each_entry_rcu(group, &tomoyo_number_group_list,
	list) {
	tomoyo_collect_member(&group->member_list,
	TOMOYO_ID_NUMBER_GROUP_MEMBER);
	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
	goto unlock;
	}
	}
	unlock:
	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);
	}