linux/security/tomoyo/gc.c
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00

652 lines
17 KiB
C

// 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>
/**
* 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 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);
}
/**
* 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");
}