[net-next-2.6.git] / security / tomoyo / gc.c

/*
 * 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);
}
Commit	Line	Data
	1	/*
	2	* security/tomoyo/gc.c
	3	*
	4	* Implementation of the Domain-Based Mandatory Access Control.
	5	*
	6	* Copyright (C) 2005-2010 NTT DATA CORPORATION
	7	*
	8	*/
	9
	10	#include "common.h"
	11	#include <linux/kthread.h>
	12	#include <linux/slab.h>
	13
	14	enum tomoyo_policy_id {
	15	TOMOYO_ID_PATH_GROUP,
	16	TOMOYO_ID_PATH_GROUP_MEMBER,
	17	TOMOYO_ID_NUMBER_GROUP,
	18	TOMOYO_ID_NUMBER_GROUP_MEMBER,
	19	TOMOYO_ID_DOMAIN_INITIALIZER,
	20	TOMOYO_ID_DOMAIN_KEEPER,
	21	TOMOYO_ID_AGGREGATOR,
	22	TOMOYO_ID_ALIAS,
	23	TOMOYO_ID_GLOBALLY_READABLE,
	24	TOMOYO_ID_PATTERN,
	25	TOMOYO_ID_NO_REWRITE,
	26	TOMOYO_ID_MANAGER,
	27	TOMOYO_ID_NAME,
	28	TOMOYO_ID_ACL,
	29	TOMOYO_ID_DOMAIN,
	30	TOMOYO_MAX_POLICY
	31	};
	32
	33	struct tomoyo_gc_entry {
	34	struct list_head list;
	35	int type;
	36	void *element;
	37	};
	38	static LIST_HEAD(tomoyo_gc_queue);
	39	static DEFINE_MUTEX(tomoyo_gc_mutex);
	40
	41	/* Caller holds tomoyo_policy_lock mutex. */
	42	static bool tomoyo_add_to_gc(const int type, void *element)
	43	{
	44	struct tomoyo_gc_entry entry = kzalloc(sizeof(entry), GFP_ATOMIC);
	45	if (!entry)
	46	return false;
	47	entry->type = type;
	48	entry->element = element;
	49	list_add(&entry->list, &tomoyo_gc_queue);
	50	return true;
	51	}
	52
	53	static void tomoyo_del_allow_read
	54	(struct tomoyo_globally_readable_file_entry *ptr)
	55	{
	56	tomoyo_put_name(ptr->filename);
	57	}
	58
	59	static void tomoyo_del_file_pattern(struct tomoyo_pattern_entry *ptr)
	60	{
	61	tomoyo_put_name(ptr->pattern);
	62	}
	63
	64	static void tomoyo_del_no_rewrite(struct tomoyo_no_rewrite_entry *ptr)
	65	{
	66	tomoyo_put_name(ptr->pattern);
	67	}
	68
	69	static void tomoyo_del_domain_initializer
	70	(struct tomoyo_domain_initializer_entry *ptr)
	71	{
	72	tomoyo_put_name(ptr->domainname);
	73	tomoyo_put_name(ptr->program);
	74	}
	75
	76	static void tomoyo_del_domain_keeper(struct tomoyo_domain_keeper_entry *ptr)
	77	{
	78	tomoyo_put_name(ptr->domainname);
	79	tomoyo_put_name(ptr->program);
	80	}
	81
	82	static void tomoyo_del_aggregator(struct tomoyo_aggregator_entry *ptr)
	83	{
	84	tomoyo_put_name(ptr->original_name);
	85	tomoyo_put_name(ptr->aggregated_name);
	86	}
	87
	88	static void tomoyo_del_alias(struct tomoyo_alias_entry *ptr)
	89	{
	90	tomoyo_put_name(ptr->original_name);
	91	tomoyo_put_name(ptr->aliased_name);
	92	}
	93
	94	static void tomoyo_del_manager(struct tomoyo_policy_manager_entry *ptr)
	95	{
	96	tomoyo_put_name(ptr->manager);
	97	}
	98
	99	static void tomoyo_del_acl(struct tomoyo_acl_info *acl)
	100	{
	101	switch (acl->type) {
	102	case TOMOYO_TYPE_PATH_ACL:
	103	{
	104	struct tomoyo_path_acl *entry
	105	= container_of(acl, typeof(*entry), head);
	106	tomoyo_put_name_union(&entry->name);
	107	}
	108	break;
	109	case TOMOYO_TYPE_PATH2_ACL:
	110	{
	111	struct tomoyo_path2_acl *entry
	112	= container_of(acl, typeof(*entry), head);
	113	tomoyo_put_name_union(&entry->name1);
	114	tomoyo_put_name_union(&entry->name2);
	115	}
	116	break;
	117	case TOMOYO_TYPE_PATH_NUMBER_ACL:
	118	{
	119	struct tomoyo_path_number_acl *entry
	120	= container_of(acl, typeof(*entry), head);
	121	tomoyo_put_name_union(&entry->name);
	122	tomoyo_put_number_union(&entry->number);
	123	}
	124	break;
	125	case TOMOYO_TYPE_MKDEV_ACL:
	126	{
	127	struct tomoyo_mkdev_acl *entry
	128	= container_of(acl, typeof(*entry), head);
	129	tomoyo_put_name_union(&entry->name);
	130	tomoyo_put_number_union(&entry->mode);
	131	tomoyo_put_number_union(&entry->major);
	132	tomoyo_put_number_union(&entry->minor);
	133	}
	134	break;
	135	case TOMOYO_TYPE_MOUNT_ACL:
	136	{
	137	struct tomoyo_mount_acl *entry
	138	= container_of(acl, typeof(*entry), head);
	139	tomoyo_put_name_union(&entry->dev_name);
	140	tomoyo_put_name_union(&entry->dir_name);
	141	tomoyo_put_name_union(&entry->fs_type);
	142	tomoyo_put_number_union(&entry->flags);
	143	}
	144	break;
	145	default:
	146	printk(KERN_WARNING "Unknown type\n");
	147	break;
	148	}
	149	}
	150
	151	static bool tomoyo_del_domain(struct tomoyo_domain_info *domain)
	152	{
	153	struct tomoyo_acl_info *acl;
	154	struct tomoyo_acl_info *tmp;
	155	/*
	156	* Since we don't protect whole execve() operation using SRCU,
	157	* we need to recheck domain->users at this point.
	158	*
	159	* (1) Reader starts SRCU section upon execve().
	160	* (2) Reader traverses tomoyo_domain_list and finds this domain.
	161	* (3) Writer marks this domain as deleted.
	162	* (4) Garbage collector removes this domain from tomoyo_domain_list
	163	* because this domain is marked as deleted and used by nobody.
	164	* (5) Reader saves reference to this domain into
	165	* "struct linux_binprm"->cred->security .
	166	* (6) Reader finishes SRCU section, although execve() operation has
	167	* not finished yet.
	168	* (7) Garbage collector waits for SRCU synchronization.
	169	* (8) Garbage collector kfree() this domain because this domain is
	170	* used by nobody.
	171	* (9) Reader finishes execve() operation and restores this domain from
	172	* "struct linux_binprm"->cred->security.
	173	*
	174	* By updating domain->users at (5), we can solve this race problem
	175	* by rechecking domain->users at (8).
	176	*/
	177	if (atomic_read(&domain->users))
	178	return false;
	179	list_for_each_entry_safe(acl, tmp, &domain->acl_info_list, list) {
	180	tomoyo_del_acl(acl);
	181	tomoyo_memory_free(acl);
	182	}
	183	tomoyo_put_name(domain->domainname);
	184	return true;
	185	}
	186
	187
	188	static void tomoyo_del_name(const struct tomoyo_name_entry *ptr)
	189	{
	190	}
	191
	192	static void tomoyo_del_path_group_member(struct tomoyo_path_group_member
	193	*member)
	194	{
	195	tomoyo_put_name(member->member_name);
	196	}
	197
	198	static void tomoyo_del_path_group(struct tomoyo_path_group *group)
	199	{
	200	tomoyo_put_name(group->group_name);
	201	}
	202
	203	static void tomoyo_del_number_group_member(struct tomoyo_number_group_member
	204	*member)
	205	{
	206	}
	207
	208	static void tomoyo_del_number_group(struct tomoyo_number_group *group)
	209	{
	210	tomoyo_put_name(group->group_name);
	211	}
	212
	213	static struct list_head *tomoyo_policy_list[TOMOYO_MAX_POLICY] = {
	214	[TOMOYO_ID_GLOBALLY_READABLE] = &tomoyo_globally_readable_list,
	215	[TOMOYO_ID_PATTERN] = &tomoyo_pattern_list,
	216	[TOMOYO_ID_NO_REWRITE] = &tomoyo_no_rewrite_list,
	217	[TOMOYO_ID_DOMAIN_INITIALIZER] = &tomoyo_domain_initializer_list,
	218	[TOMOYO_ID_DOMAIN_KEEPER] = &tomoyo_domain_keeper_list,
	219	[TOMOYO_ID_AGGREGATOR] = &tomoyo_aggregator_list,
	220	[TOMOYO_ID_ALIAS] = &tomoyo_alias_list,
	221	[TOMOYO_ID_MANAGER] = &tomoyo_policy_manager_list,
	222	};
	223
	224	static bool tomoyo_collect_member(struct list_head *member_list, int id)
	225	{
	226	struct tomoyo_acl_head *member;
	227	list_for_each_entry(member, member_list, list) {
	228	if (!member->is_deleted)
	229	continue;
	230	if (!tomoyo_add_to_gc(id, &member->list))
	231	return false;
	232	list_del_rcu(&member->list);
	233	}
	234	return true;
	235	}
	236
	237	static bool tomoyo_collect_acl(struct tomoyo_domain_info *domain)
	238	{
	239	struct tomoyo_acl_info *acl;
	240	list_for_each_entry(acl, &domain->acl_info_list, list) {
	241	if (!acl->is_deleted)
	242	continue;
	243	if (!tomoyo_add_to_gc(TOMOYO_ID_ACL, &acl->list))
	244	return false;
	245	list_del_rcu(&acl->list);
	246	}
	247	return true;
	248	}
	249
	250	static void tomoyo_collect_entry(void)
	251	{
	252	int i;
	253	if (mutex_lock_interruptible(&tomoyo_policy_lock))
	254	return;
	255	for (i = 0; i < TOMOYO_MAX_POLICY; i++) {
	256	if (tomoyo_policy_list[i])
	257	if (!tomoyo_collect_member(tomoyo_policy_list[i], i))
	258	goto unlock;
	259	}
	260	{
	261	struct tomoyo_domain_info *domain;
	262	list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
	263	if (!tomoyo_collect_acl(domain))
	264	goto unlock;
	265	if (!domain->is_deleted \|\| atomic_read(&domain->users))
	266	continue;
	267	/*
	268	* Nobody is referring this domain. But somebody may
	269	* refer this domain after successful execve().
	270	* We recheck domain->users after SRCU synchronization.
	271	*/
	272	if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN, domain))
	273	list_del_rcu(&domain->list);
	274	else
	275	goto unlock;
	276	}
	277	}
	278	for (i = 0; i < TOMOYO_MAX_HASH; i++) {
	279	struct tomoyo_name_entry *ptr;
	280	list_for_each_entry_rcu(ptr, &tomoyo_name_list[i], list) {
	281	if (atomic_read(&ptr->users))
	282	continue;
	283	if (tomoyo_add_to_gc(TOMOYO_ID_NAME, ptr))
	284	list_del_rcu(&ptr->list);
	285	else
	286	goto unlock;
	287	}
	288	}
	289	{
	290	struct tomoyo_path_group *group;
	291	list_for_each_entry_rcu(group, &tomoyo_path_group_list, list) {
	292	tomoyo_collect_member(&group->member_list,
	293	TOMOYO_ID_PATH_GROUP_MEMBER);
	294	if (!list_empty(&group->member_list) \|\|
	295	atomic_read(&group->users))
	296	continue;
	297	if (tomoyo_add_to_gc(TOMOYO_ID_PATH_GROUP, group))
	298	list_del_rcu(&group->list);
	299	else
	300	goto unlock;
	301	}
	302	}
	303	{
	304	struct tomoyo_number_group *group;
	305	list_for_each_entry_rcu(group, &tomoyo_number_group_list,
	306	list) {
	307	tomoyo_collect_member(&group->member_list,
	308	TOMOYO_ID_NUMBER_GROUP_MEMBER);
	309	if (!list_empty(&group->member_list) \|\|
	310	atomic_read(&group->users))
	311	continue;
	312	if (tomoyo_add_to_gc(TOMOYO_ID_NUMBER_GROUP, group))
	313	list_del_rcu(&group->list);
	314	else
	315	goto unlock;
	316	}
	317	}
	318	unlock:
	319	mutex_unlock(&tomoyo_policy_lock);
	320	}
	321
	322	static void tomoyo_kfree_entry(void)
	323	{
	324	struct tomoyo_gc_entry *p;
	325	struct tomoyo_gc_entry *tmp;
	326
	327	list_for_each_entry_safe(p, tmp, &tomoyo_gc_queue, list) {
	328	switch (p->type) {
	329	case TOMOYO_ID_DOMAIN_INITIALIZER:
	330	tomoyo_del_domain_initializer(p->element);
	331	break;
	332	case TOMOYO_ID_DOMAIN_KEEPER:
	333	tomoyo_del_domain_keeper(p->element);
	334	break;
	335	case TOMOYO_ID_AGGREGATOR:
	336	tomoyo_del_aggregator(p->element);
	337	break;
	338	case TOMOYO_ID_ALIAS:
	339	tomoyo_del_alias(p->element);
	340	break;
	341	case TOMOYO_ID_GLOBALLY_READABLE:
	342	tomoyo_del_allow_read(p->element);
	343	break;
	344	case TOMOYO_ID_PATTERN:
	345	tomoyo_del_file_pattern(p->element);
	346	break;
	347	case TOMOYO_ID_NO_REWRITE:
	348	tomoyo_del_no_rewrite(p->element);
	349	break;
	350	case TOMOYO_ID_MANAGER:
	351	tomoyo_del_manager(p->element);
	352	break;
	353	case TOMOYO_ID_NAME:
	354	tomoyo_del_name(p->element);
	355	break;
	356	case TOMOYO_ID_ACL:
	357	tomoyo_del_acl(p->element);
	358	break;
	359	case TOMOYO_ID_DOMAIN:
	360	if (!tomoyo_del_domain(p->element))
	361	continue;
	362	break;
	363	case TOMOYO_ID_PATH_GROUP_MEMBER:
	364	tomoyo_del_path_group_member(p->element);
	365	break;
	366	case TOMOYO_ID_PATH_GROUP:
	367	tomoyo_del_path_group(p->element);
	368	break;
	369	case TOMOYO_ID_NUMBER_GROUP_MEMBER:
	370	tomoyo_del_number_group_member(p->element);
	371	break;
	372	case TOMOYO_ID_NUMBER_GROUP:
	373	tomoyo_del_number_group(p->element);
	374	break;
	375	default:
	376	printk(KERN_WARNING "Unknown type\n");
	377	break;
	378	}
	379	tomoyo_memory_free(p->element);
	380	list_del(&p->list);
	381	kfree(p);
	382	}
	383	}
	384
	385	static int tomoyo_gc_thread(void *unused)
	386	{
	387	daemonize("GC for TOMOYO");
	388	if (mutex_trylock(&tomoyo_gc_mutex)) {
	389	int i;
	390	for (i = 0; i < 10; i++) {
	391	tomoyo_collect_entry();
	392	if (list_empty(&tomoyo_gc_queue))
	393	break;
	394	synchronize_srcu(&tomoyo_ss);
	395	tomoyo_kfree_entry();
	396	}
	397	mutex_unlock(&tomoyo_gc_mutex);
	398	}
	399	do_exit(0);
	400	}
	401
	402	void tomoyo_run_gc(void)
	403	{
	404	struct task_struct *task = kthread_create(tomoyo_gc_thread, NULL,
	405	"GC for TOMOYO");
	406	if (!IS_ERR(task))
	407	wake_up_process(task);
	408	}