// SPDX-License-Identifier: GPL-2.0
/*
* security/tomoyo/gc.c
*
* Copyright (C) 2005-2011 NTT DATA CORPORATION
*/
#include "common.h"
#include <linux/kthread.h>
#include <linux/slab.h>
/* Lock for GC. */
DEFINE_SRCU(tomoyo_ss);
/**
* tomoyo_memory_free - Free memory for elements.
*
* @ptr: Pointer to allocated memory.
*
* Returns nothing.
*
* Caller holds tomoyo_policy_lock mutex.
*/
static inline void tomoyo_memory_free(void *ptr)
{
tomoyo_memory_used[TOMOYO_MEMORY_POLICY] -= ksize(ptr);
kfree(ptr);
}
/* The list for "struct tomoyo_io_buffer". */
static LIST_HEAD(tomoyo_io_buffer_list);
/* Lock for protecting tomoyo_io_buffer_list. */
static DEFINE_SPINLOCK(tomoyo_io_buffer_list_lock);
/**
* tomoyo_struct_used_by_io_buffer - Check whether the list element is used by /sys/kernel/security/tomoyo/ users or not.
*
* @element: Pointer to "struct list_head".
*
* Returns true if @element is used by /sys/kernel/security/tomoyo/ users,
* false otherwise.
*/
static bool tomoyo_struct_used_by_io_buffer(const struct list_head *element)
{
struct tomoyo_io_buffer *head;
bool in_use = false;
spin_lock(&tomoyo_io_buffer_list_lock);
list_for_each_entry(head, &tomoyo_io_buffer_list, list) {
head->users++;
spin_unlock(&tomoyo_io_buffer_list_lock);
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);
spin_lock(&tomoyo_io_buffer_list_lock);
head->users--;
if (in_use)
break;
}
spin_unlock(&tomoyo_io_buffer_list_lock);
return 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.
*
* 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)
{
struct tomoyo_io_buffer *head;
const size_t size = strlen(string) + 1;
bool in_use = false;
spin_lock(&tomoyo_io_buffer_list_lock);
list_for_each_entry(head, &tomoyo_io_buffer_list, list) {
int i;
head->users++;
spin_unlock(&tomoyo_io_buffer_list_lock);
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)
continue;
in_use = true;
break;
}
mutex_unlock(&head->io_sem);
spin_lock(&tomoyo_io_buffer_list_lock);
head->users--;
if (in_use)
break;
}
spin_unlock(&tomoyo_io_buffer_list_lock);
return in_use;
}
/**
* tomoyo_del_transition_control - Delete members in "struct tomoyo_transition_control".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
static inline 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 inline 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 inline 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);
tomoyo_put_condition(acl->cond);
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;
case TOMOYO_TYPE_ENV_ACL:
{
struct tomoyo_env_acl *entry =
container_of(acl, typeof(*entry), head);
tomoyo_put_name(entry->env);
}
break;
case TOMOYO_TYPE_INET_ACL:
{
struct tomoyo_inet_acl *entry =
container_of(acl, typeof(*entry), head);
tomoyo_put_group(entry->address.group);
tomoyo_put_number_union(&entry->port);
}
break;
case TOMOYO_TYPE_UNIX_ACL:
{
struct tomoyo_unix_acl *entry =
container_of(acl, typeof(*entry), head);
tomoyo_put_name_union(&entry->name);
}
break;
case TOMOYO_TYPE_MANUAL_TASK_ACL:
{
struct tomoyo_task_acl *entry =
container_of(acl, typeof(*entry), head);
tomoyo_put_name(entry->domainname);
}
break;
}
}
/**
* tomoyo_del_domain - Delete members in "struct tomoyo_domain_info".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*
* Caller holds tomoyo_policy_lock mutex.
*/
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 this domain is referenced from neither
* "struct tomoyo_io_buffer" nor "struct cred"->security, we can delete
* elements without checking for is_deleted flag.
*/
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);
}
/**
* tomoyo_del_condition - Delete members in "struct tomoyo_condition".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
void tomoyo_del_condition(struct list_head *element)
{
struct tomoyo_condition *cond = container_of(element, typeof(*cond),
head.list);
const u16 condc = cond->condc;
const u16 numbers_count = cond->numbers_count;
const u16 names_count = cond->names_count;
const u16 argc = cond->argc;
const u16 envc = cond->envc;
unsigned int i;
const struct tomoyo_condition_element *condp
= (const struct tomoyo_condition_element *) (cond + 1);
struct tomoyo_number_union *numbers_p
= (struct tomoyo_number_union *) (condp + condc);
struct tomoyo_name_union *names_p
= (struct tomoyo_name_union *) (numbers_p + numbers_count);
const struct tomoyo_argv *argv
= (const struct tomoyo_argv *) (names_p + names_count);
const struct tomoyo_envp *envp
= (const struct tomoyo_envp *) (argv + argc);
for (i = 0; i < numbers_count; i++)
tomoyo_put_number_union(numbers_p++);
for (i = 0; i < names_count; i++)
tomoyo_put_name_union(names_p++);
for (i = 0; i < argc; argv++, i++)
tomoyo_put_name(argv->value);
for (i = 0; i < envc; envp++, i++) {
tomoyo_put_name(envp->name);
tomoyo_put_name(envp->value);
}
}
/**
* tomoyo_del_name - Delete members in "struct tomoyo_name".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
static inline void tomoyo_del_name(struct list_head *element)
{
/* Nothing to do. */
}
/**
* tomoyo_del_path_group - Delete members in "struct tomoyo_path_group".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
static inline 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 inline 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_address_group - Delete members in "struct tomoyo_address_group".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
static inline void tomoyo_del_address_group(struct list_head *element)
{
/* Nothing to do. */
}
/**
* tomoyo_del_number_group - Delete members in "struct tomoyo_number_group".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
static inline void tomoyo_del_number_group(struct list_head *element)
{
/* 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;
break;
case TOMOYO_MAX_POLICY:
break;
}
mutex_lock(&tomoyo_policy_lock);
if (type == TOMOYO_ID_DOMAIN)
tomoyo_del_domain(element);
tomoyo_memory_free(element);
return;
reinject:
/*
* We can safely reinject this element here because
* (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);
}
/**
* 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 nothing.
*/
static void tomoyo_collect_member(const enum tomoyo_policy_id id,
struct list_head *member_list)
{
struct tomoyo_acl_head *member;
struct tomoyo_acl_head *tmp;
list_for_each_entry_safe(member, tmp, member_list, list) {
if (!member->is_deleted)
continue;
member->is_deleted = TOMOYO_GC_IN_PROGRESS;
tomoyo_try_to_gc(id, &member->list);
}
}
/**
* tomoyo_collect_acl - Delete elements in "struct tomoyo_domain_info".
*
* @list: Pointer to "struct list_head".
*
* Returns nothing.
*/
static void tomoyo_collect_acl(struct list_head *list)
{
struct tomoyo_acl_info *acl;
struct tomoyo_acl_info *tmp;
list_for_each_entry_safe(acl, tmp, list, list) {
if (!acl->is_deleted)
continue;
acl->is_deleted = TOMOYO_GC_IN_PROGRESS;
tomoyo_try_to_gc(TOMOYO_ID_ACL, &acl->list);
}
}
/**
* tomoyo_collect_entry - Try to kfree() deleted elements.
*
* Returns nothing.
*/
static void tomoyo_collect_entry(void)
{
int i;
enum tomoyo_policy_id id;
struct tomoyo_policy_namespace *ns;
mutex_lock(&tomoyo_policy_lock);
{
struct tomoyo_domain_info *domain;
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;
tomoyo_try_to_gc(TOMOYO_ID_DOMAIN, &domain->list);
}
}
list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {
for (id = 0; id < TOMOYO_MAX_POLICY; id++)
tomoyo_collect_member(id, &ns->policy_list[id]);
for (i = 0; i < TOMOYO_MAX_ACL_GROUPS; i++)
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;
break;
case 1:
id = TOMOYO_ID_NUMBER_GROUP;
break;
default:
id = TOMOYO_ID_ADDRESS_GROUP;
break;
}
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) > 0)
continue;
atomic_set(&group->head.users,
TOMOYO_GC_IN_PROGRESS);
tomoyo_try_to_gc(TOMOYO_ID_GROUP,
&group->head.list);
}
}
}
for (i = 0; i < TOMOYO_MAX_HASH; i++) {
struct list_head *list = &tomoyo_name_list[i];
struct tomoyo_shared_acl_head *ptr;
struct tomoyo_shared_acl_head *tmp;
list_for_each_entry_safe(ptr, tmp, list, list) {
if (atomic_read(&ptr->users) > 0)
continue;
atomic_set(&ptr->users, TOMOYO_GC_IN_PROGRESS);
tomoyo_try_to_gc(TOMOYO_ID_NAME, &ptr->list);
}
}
mutex_unlock(&tomoyo_policy_lock);
}
/**
* tomoyo_gc_thread - Garbage collector thread function.
*
* @unused: Unused.
*
* Returns 0.
*/
static int tomoyo_gc_thread(void *unused)
{
/* Garbage collector thread is exclusive. */
static DEFINE_MUTEX(tomoyo_gc_mutex);
if (!mutex_trylock(&tomoyo_gc_mutex))
goto out;
tomoyo_collect_entry();
{
struct tomoyo_io_buffer *head;
struct tomoyo_io_buffer *tmp;
spin_lock(&tomoyo_io_buffer_list_lock);
list_for_each_entry_safe(head, tmp, &tomoyo_io_buffer_list,
list) {
if (head->users)
continue;
list_del(&head->list);
kfree(head->read_buf);
kfree(head->write_buf);
kfree(head);
}
spin_unlock(&tomoyo_io_buffer_list_lock);
}
mutex_unlock(&tomoyo_gc_mutex);
out:
/* This acts as do_exit(0). */
return 0;
}
/**
* tomoyo_notify_gc - Register/unregister /sys/kernel/security/tomoyo/ users.
*
* @head: Pointer to "struct tomoyo_io_buffer".
* @is_register: True if register, false if unregister.
*
* Returns nothing.
*/
void tomoyo_notify_gc(struct tomoyo_io_buffer *head, const bool is_register)
{
bool is_write = false;
spin_lock(&tomoyo_io_buffer_list_lock);
if (is_register) {
head->users = 1;
list_add(&head->list, &tomoyo_io_buffer_list);
} else {
is_write = head->write_buf != NULL;
if (!--head->users) {
list_del(&head->list);
kfree(head->read_buf);
kfree(head->write_buf);
kfree(head);
}
}
spin_unlock(&tomoyo_io_buffer_list_lock);
if (is_write)
kthread_run(tomoyo_gc_thread, NULL, "GC for TOMOYO");
}
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