TOMOYO: Simplify garbage collector.

#define TOMOYO_EXEC_TMPSIZE     4096

/* Garbage collector is trying to kfree() this element. */

#define TOMOYO_GC_IN_PROGRESS -1

/* Profile number is an integer between 0 and 255. */

#define TOMOYO_MAX_PROFILES 256

/* Common header for holding ACL entries. */

struct tomoyo_acl_head {

	struct list_head list;

	bool is_deleted;

	s8 is_deleted; /* true or false or TOMOYO_GC_IN_PROGRESS */

} __packed;

/* Common header for shared entries. */

struct tomoyo_acl_info {

	struct list_head list;

	struct tomoyo_condition *cond; /* Maybe NULL. */

	bool is_deleted;

	s8 is_deleted; /* true or false or TOMOYO_GC_IN_PROGRESS */

	u8 type; /* One of values in "enum tomoyo_acl_entry_type_index". */

} __packed;

		found = true;

		goto out;

	}

	list_for_each_entry_rcu(ptr, &tomoyo_condition_list, head.list) {

		if (!tomoyo_same_condition(ptr, entry))

	list_for_each_entry(ptr, &tomoyo_condition_list, head.list) {

		if (!tomoyo_same_condition(ptr, entry) ||

		    atomic_read(&ptr->head.users) == TOMOYO_GC_IN_PROGRESS)

			continue;

		/* Same entry found. Share this entry. */

		atomic_inc(&ptr->head.users);

	if (!found) {

		if (tomoyo_memory_ok(entry)) {

			atomic_set(&entry->head.users, 1);

			list_add_rcu(&entry->head.list,

				     &tomoyo_condition_list);

			list_add(&entry->head.list, &tomoyo_condition_list);

		} else {

			found = true;

			ptr = NULL;

	if (mutex_lock_interruptible(&tomoyo_policy_lock))

		return -ENOMEM;

	list_for_each_entry_rcu(entry, list, list) {

		if (entry->is_deleted == TOMOYO_GC_IN_PROGRESS)

			continue;

		if (!check_duplicate(entry, new_entry))

			continue;

		entry->is_deleted = param->is_delete;

	if (mutex_lock_interruptible(&tomoyo_policy_lock))

		goto out;

	list_for_each_entry_rcu(entry, list, list) {

		if (entry->is_deleted == TOMOYO_GC_IN_PROGRESS)

			continue;

		if (!tomoyo_same_acl_head(entry, new_entry) ||

		    !check_duplicate(entry, new_entry))

			continue;

/* Lock for protecting tomoyo_io_buffer_list. */

static DEFINE_SPINLOCK(tomoyo_io_buffer_list_lock);

/* Size of an element. */

static const u8 tomoyo_element_size[TOMOYO_MAX_POLICY] = {

	[TOMOYO_ID_GROUP] = sizeof(struct tomoyo_group),

	[TOMOYO_ID_ADDRESS_GROUP] = sizeof(struct tomoyo_address_group),

	[TOMOYO_ID_PATH_GROUP] = sizeof(struct tomoyo_path_group),

	[TOMOYO_ID_NUMBER_GROUP] = sizeof(struct tomoyo_number_group),

	[TOMOYO_ID_AGGREGATOR] = sizeof(struct tomoyo_aggregator),

	[TOMOYO_ID_TRANSITION_CONTROL] =

	sizeof(struct tomoyo_transition_control),

	[TOMOYO_ID_MANAGER] = sizeof(struct tomoyo_manager),

	/* [TOMOYO_ID_CONDITION] = "struct tomoyo_condition"->size, */

	/* [TOMOYO_ID_NAME] = "struct tomoyo_name"->size, */

	/* [TOMOYO_ID_ACL] =

	   tomoyo_acl_size["struct tomoyo_acl_info"->type], */

	[TOMOYO_ID_DOMAIN] = sizeof(struct tomoyo_domain_info),

};

/* Size of a domain ACL element. */

static const u8 tomoyo_acl_size[] = {

	[TOMOYO_TYPE_PATH_ACL] = sizeof(struct tomoyo_path_acl),

	[TOMOYO_TYPE_PATH2_ACL] = sizeof(struct tomoyo_path2_acl),

	[TOMOYO_TYPE_PATH_NUMBER_ACL] = sizeof(struct tomoyo_path_number_acl),

	[TOMOYO_TYPE_MKDEV_ACL] = sizeof(struct tomoyo_mkdev_acl),

	[TOMOYO_TYPE_MOUNT_ACL] = sizeof(struct tomoyo_mount_acl),

	[TOMOYO_TYPE_INET_ACL] = sizeof(struct tomoyo_inet_acl),

	[TOMOYO_TYPE_UNIX_ACL] = sizeof(struct tomoyo_unix_acl),

	[TOMOYO_TYPE_ENV_ACL] = sizeof(struct tomoyo_env_acl),

};

/**

 * tomoyo_struct_used_by_io_buffer - Check whether the list element is used by /sys/kernel/security/tomoyo/ users or not.

 *

	list_for_each_entry(head, &tomoyo_io_buffer_list, list) {

		head->users++;

		spin_unlock(&tomoyo_io_buffer_list_lock);

		if (mutex_lock_interruptible(&head->io_sem)) {

			in_use = true;

			goto out;

		}

		mutex_lock(&head->io_sem);

		if (head->r.domain == element || head->r.group == element ||

		    head->r.acl == element || &head->w.domain->list == element)

			in_use = true;

		mutex_unlock(&head->io_sem);

out:

		spin_lock(&tomoyo_io_buffer_list_lock);

		head->users--;

		if (in_use)

 * tomoyo_name_used_by_io_buffer - Check whether the string is used by /sys/kernel/security/tomoyo/ users or not.

 *

 * @string: String to check.

 * @size:   Memory allocated for @string .

 *

 * Returns true if @string is used by /sys/kernel/security/tomoyo/ users,

 * false otherwise.

 */

static bool tomoyo_name_used_by_io_buffer(const char *string,

					  const size_t size)

static bool tomoyo_name_used_by_io_buffer(const char *string)

{

	struct tomoyo_io_buffer *head;

	const size_t size = strlen(string) + 1;

	bool in_use = false;

	spin_lock(&tomoyo_io_buffer_list_lock);

		int i;

		head->users++;

		spin_unlock(&tomoyo_io_buffer_list_lock);

		if (mutex_lock_interruptible(&head->io_sem)) {

			in_use = true;

			goto out;

		}

		mutex_lock(&head->io_sem);

		for (i = 0; i < TOMOYO_MAX_IO_READ_QUEUE; i++) {

			const char *w = head->r.w[i];

			if (w < string || w > string + size)

			break;

		}

		mutex_unlock(&head->io_sem);

out:

		spin_lock(&tomoyo_io_buffer_list_lock);

		head->users--;

		if (in_use)

	return in_use;

}

/* Structure for garbage collection. */

struct tomoyo_gc {

	struct list_head list;

	enum tomoyo_policy_id type;

	size_t size;

	struct list_head *element;

};

/* List of entries to be deleted. */

static LIST_HEAD(tomoyo_gc_list);

/* Length of tomoyo_gc_list. */

static int tomoyo_gc_list_len;

/**

 * 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;

	if (type == TOMOYO_ID_ACL)

		entry->size = tomoyo_acl_size[

			      container_of(element,

					   typeof(struct tomoyo_acl_info),

					   list)->type];

	else if (type == TOMOYO_ID_NAME)

		entry->size = strlen(container_of(element,

						  typeof(struct tomoyo_name),

						  head.list)->entry.name) + 1;

	else if (type == TOMOYO_ID_CONDITION)

		entry->size =

			container_of(element, typeof(struct tomoyo_condition),

				     head.list)->size;

	else

		entry->size = tomoyo_element_size[type];

	entry->element = element;

	list_add(&entry->list, &tomoyo_gc_list);

	list_del_rcu(element);

	return tomoyo_gc_list_len++ < 128;

}

/**

 * tomoyo_element_linked_by_gc - Validate next element of an entry.

 *

 * @element: Pointer to an element.

 * @size:    Size of @element in byte.

 *

 * Returns true if @element is linked by other elements in the garbage

 * collector's queue, false otherwise.

 */

static bool tomoyo_element_linked_by_gc(const u8 *element, const size_t size)

{

	struct tomoyo_gc *p;

	list_for_each_entry(p, &tomoyo_gc_list, list) {

		const u8 *ptr = (const u8 *) p->element->next;

		if (ptr < element || element + size < ptr)

			continue;

		return true;

	}

	return false;

}

/**

 * tomoyo_del_transition_control - Delete members in "struct tomoyo_transition_control".

 *

 *

 * Returns nothing.

 */

static void tomoyo_del_transition_control(struct list_head *element)

static inline void tomoyo_del_transition_control(struct list_head *element)

{

	struct tomoyo_transition_control *ptr =

		container_of(element, typeof(*ptr), head.list);

 *

 * Returns nothing.

 */

static void tomoyo_del_aggregator(struct list_head *element)

static inline void tomoyo_del_aggregator(struct list_head *element)

{

	struct tomoyo_aggregator *ptr =

		container_of(element, typeof(*ptr), head.list);

 *

 * Returns nothing.

 */

static void tomoyo_del_manager(struct list_head *element)

static inline void tomoyo_del_manager(struct list_head *element)

{

	struct tomoyo_manager *ptr =

		container_of(element, typeof(*ptr), head.list);

 *

 * @element: Pointer to "struct list_head".

 *

 * Returns true if deleted, false otherwise.

 * Returns nothing.

 */

static bool tomoyo_del_domain(struct list_head *element)

static inline void 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).

	 * Since this domain is referenced from neither

	 * "struct tomoyo_io_buffer" nor "struct cred"->security, we can delete

	 * elements without checking for is_deleted flag.

	 */

	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;

}

/**

 *

 * Returns nothing.

 */

static void tomoyo_del_name(struct list_head *element)

static inline void tomoyo_del_name(struct list_head *element)

{

	const struct tomoyo_name *ptr =

		container_of(element, typeof(*ptr), head.list);

	/* Nothing to do. */

}

/**

 *

 * Returns nothing.

 */

static void tomoyo_del_path_group(struct list_head *element)

static inline void tomoyo_del_path_group(struct list_head *element)

{

	struct tomoyo_path_group *member =

		container_of(element, typeof(*member), head.list);

 *

 * Returns nothing.

 */

static void tomoyo_del_group(struct list_head *element)

static inline void tomoyo_del_group(struct list_head *element)

{

	struct tomoyo_group *group =

		container_of(element, typeof(*group), head.list);

 *

 * Returns nothing.

 */

static void tomoyo_del_number_group(struct list_head *element)

static inline void tomoyo_del_number_group(struct list_head *element)

{

	struct tomoyo_number_group *member =

		container_of(element, typeof(*member), head.list);

	/* Nothing to do. */

}

/**

 * tomoyo_try_to_gc - Try to kfree() an entry.

 *

 * @type:    One of values in "enum tomoyo_policy_id".

 * @element: Pointer to "struct list_head".

 *

 * Returns nothing.

 *

 * Caller holds tomoyo_policy_lock mutex.

 */

static void tomoyo_try_to_gc(const enum tomoyo_policy_id type,

			     struct list_head *element)

{

	/*

	 * __list_del_entry() guarantees that the list element became no longer

	 * reachable from the list which the element was originally on (e.g.

	 * tomoyo_domain_list). Also, synchronize_srcu() guarantees that the

	 * list element became no longer referenced by syscall users.

	 */

	__list_del_entry(element);

	mutex_unlock(&tomoyo_policy_lock);

	synchronize_srcu(&tomoyo_ss);

	/*

	 * However, there are two users which may still be using the list

	 * element. We need to defer until both users forget this element.

	 *

	 * Don't kfree() until "struct tomoyo_io_buffer"->r.{domain,group,acl}

	 * and "struct tomoyo_io_buffer"->w.domain forget this element.

	 */

	if (tomoyo_struct_used_by_io_buffer(element))

		goto reinject;

	switch (type) {

	case TOMOYO_ID_TRANSITION_CONTROL:

		tomoyo_del_transition_control(element);

		break;

	case TOMOYO_ID_MANAGER:

		tomoyo_del_manager(element);

		break;

	case TOMOYO_ID_AGGREGATOR:

		tomoyo_del_aggregator(element);

		break;

	case TOMOYO_ID_GROUP:

		tomoyo_del_group(element);

		break;

	case TOMOYO_ID_PATH_GROUP:

		tomoyo_del_path_group(element);

		break;

	case TOMOYO_ID_ADDRESS_GROUP:

		tomoyo_del_address_group(element);

		break;

	case TOMOYO_ID_NUMBER_GROUP:

		tomoyo_del_number_group(element);

		break;

	case TOMOYO_ID_CONDITION:

		tomoyo_del_condition(element);

		break;

	case TOMOYO_ID_NAME:

		/*

		 * Don't kfree() until all "struct tomoyo_io_buffer"->r.w[]

		 * forget this element.

		 */

		if (tomoyo_name_used_by_io_buffer

		    (container_of(element, typeof(struct tomoyo_name),

				  head.list)->entry.name))

			goto reinject;

		tomoyo_del_name(element);

		break;

	case TOMOYO_ID_ACL:

		tomoyo_del_acl(element);

		break;

	case TOMOYO_ID_DOMAIN:

		/*

		 * Don't kfree() until all "struct cred"->security forget this

		 * element.

		 */

		if (atomic_read(&container_of

				(element, typeof(struct tomoyo_domain_info),

				 list)->users))

			goto reinject;

		tomoyo_del_domain(element);

		break;

	case TOMOYO_MAX_POLICY:

		break;

	}

	mutex_lock(&tomoyo_policy_lock);

	tomoyo_memory_free(element);

	return;

reinject:

	/*

	 * We can safely reinject this element here bacause

	 * (1) Appending list elements and removing list elements are protected

	 *     by tomoyo_policy_lock mutex.

	 * (2) Only this function removes list elements and this function is

	 *     exclusively executed by tomoyo_gc_mutex mutex.

	 * are true.

	 */

	mutex_lock(&tomoyo_policy_lock);

	list_add_rcu(element, element->prev);

}

/**

 * @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.

 * Returns nothing.

 */

static bool tomoyo_collect_member(const enum tomoyo_policy_id id,

static void 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) {

	struct tomoyo_acl_head *tmp;

	list_for_each_entry_safe(member, tmp, member_list, list) {

		if (!member->is_deleted)

			continue;

		if (!tomoyo_add_to_gc(id, &member->list))

			return false;

		member->is_deleted = TOMOYO_GC_IN_PROGRESS;

		tomoyo_try_to_gc(id, &member->list);

	}

	return true;

}

/**

 *

 * @list: Pointer to "struct list_head".

 *

 * Returns true if some elements are deleted, false otherwise.

 * Returns nothing.

 */

static bool tomoyo_collect_acl(struct list_head *list)

static void tomoyo_collect_acl(struct list_head *list)

{

	struct tomoyo_acl_info *acl;

	list_for_each_entry(acl, list, list) {

	struct tomoyo_acl_info *tmp;

	list_for_each_entry_safe(acl, tmp, list, list) {

		if (!acl->is_deleted)

			continue;

		if (!tomoyo_add_to_gc(TOMOYO_ID_ACL, &acl->list))

			return false;

		acl->is_deleted = TOMOYO_GC_IN_PROGRESS;

		tomoyo_try_to_gc(TOMOYO_ID_ACL, &acl->list);

	}

	return true;

}

/**

 * tomoyo_collect_entry - Scan lists for deleted elements.

 * tomoyo_collect_entry - Try to kfree() deleted elements.

 *

 * Returns nothing.

 */

	int i;

	enum tomoyo_policy_id id;

	struct tomoyo_policy_namespace *ns;

	int idx;

	if (mutex_lock_interruptible(&tomoyo_policy_lock))

		return;

	idx = tomoyo_read_lock();

	mutex_lock(&tomoyo_policy_lock);

	{

		struct tomoyo_domain_info *domain;

		list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {

			if (!tomoyo_collect_acl(&domain->acl_info_list))

				goto unlock;

		struct tomoyo_domain_info *tmp;

		list_for_each_entry_safe(domain, tmp, &tomoyo_domain_list,

					 list) {

			tomoyo_collect_acl(&domain->acl_info_list);

			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;

			tomoyo_try_to_gc(TOMOYO_ID_DOMAIN, &domain->list);

		}

	}

	list_for_each_entry_rcu(ns, &tomoyo_namespace_list, namespace_list) {

	list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {

		for (id = 0; id < TOMOYO_MAX_POLICY; id++)

			if (!tomoyo_collect_member(id, &ns->policy_list[id]))

				goto unlock;

			tomoyo_collect_member(id, &ns->policy_list[id]);

		for (i = 0; i < TOMOYO_MAX_ACL_GROUPS; i++)

			if (!tomoyo_collect_acl(&ns->acl_group[i]))

				goto unlock;

			tomoyo_collect_acl(&ns->acl_group[i]);

	}

	{

		struct tomoyo_shared_acl_head *ptr;

		struct tomoyo_shared_acl_head *tmp;

		list_for_each_entry_safe(ptr, tmp, &tomoyo_condition_list,

					 list) {

			if (atomic_read(&ptr->users) > 0)

				continue;

			atomic_set(&ptr->users, TOMOYO_GC_IN_PROGRESS);

			tomoyo_try_to_gc(TOMOYO_ID_CONDITION, &ptr->list);

		}

	}

	list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {

		for (i = 0; i < TOMOYO_MAX_GROUP; i++) {

			struct list_head *list = &ns->group_list[i];

			struct tomoyo_group *group;

			struct tomoyo_group *tmp;

			switch (i) {

			case 0:

				id = TOMOYO_ID_PATH_GROUP;

				id = TOMOYO_ID_ADDRESS_GROUP;

				break;

			}

			list_for_each_entry(group, list, head.list) {

				if (!tomoyo_collect_member

				    (id, &group->member_list))

					goto unlock;

			list_for_each_entry_safe(group, tmp, list, head.list) {

				tomoyo_collect_member(id, &group->member_list);

				if (!list_empty(&group->member_list) ||

				    atomic_read(&group->head.users))

				    atomic_read(&group->head.users) > 0)

					continue;

				if (!tomoyo_add_to_gc(TOMOYO_ID_GROUP,

						      &group->head.list))

					goto unlock;

				atomic_set(&group->head.users,

					   TOMOYO_GC_IN_PROGRESS);

				tomoyo_try_to_gc(TOMOYO_ID_GROUP,

						 &group->head.list);

			}

		}

	}

	id = TOMOYO_ID_CONDITION;

	for (i = 0; i < TOMOYO_MAX_HASH + 1; i++) {

		struct list_head *list = !i ?

			&tomoyo_condition_list : &tomoyo_name_list[i - 1];

	for (i = 0; i < TOMOYO_MAX_HASH; i++) {

		struct list_head *list = &tomoyo_name_list[i];

		struct tomoyo_shared_acl_head *ptr;

		list_for_each_entry(ptr, list, list) {

			if (atomic_read(&ptr->users))

		struct tomoyo_shared_acl_head *tmp;

		list_for_each_entry_safe(ptr, tmp, list, list) {

			if (atomic_read(&ptr->users) > 0)

				continue;

			if (!tomoyo_add_to_gc(id, &ptr->list))

				goto unlock;

			atomic_set(&ptr->users, TOMOYO_GC_IN_PROGRESS);

			tomoyo_try_to_gc(TOMOYO_ID_NAME, &ptr->list);

		}

		id = TOMOYO_ID_NAME;

	}

unlock:

	tomoyo_read_unlock(idx);

	mutex_unlock(&tomoyo_policy_lock);

}

/**

 * tomoyo_kfree_entry - Delete entries in tomoyo_gc_list.

 *

 * Returns true if some entries were kfree()d, false otherwise.

 */

static bool tomoyo_kfree_entry(void)

{

	struct tomoyo_gc *p;

	struct tomoyo_gc *tmp;

	bool result = false;

	list_for_each_entry_safe(p, tmp, &tomoyo_gc_list, list) {

		struct list_head *element = p->element;

		/*

		 * list_del_rcu() in tomoyo_add_to_gc() guarantees that the

		 * list element became no longer reachable from the list which

		 * the element was originally on (e.g. tomoyo_domain_list).

		 * Also, synchronize_srcu() in tomoyo_gc_thread() guarantees

		 * that the list element became no longer referenced by syscall

		 * users.

		 *

		 * However, there are three users which may still be using the

		 * list element. We need to defer until all of these users

		 * forget the list element.

		 *

		 * Firstly, defer until "struct tomoyo_io_buffer"->r.{domain,