68 lines
1.7 KiB
C
68 lines
1.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* Landlock LSM - Object management
|
|
*
|
|
* Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net>
|
|
* Copyright © 2018-2020 ANSSI
|
|
*/
|
|
|
|
#include <linux/bug.h>
|
|
#include <linux/compiler_types.h>
|
|
#include <linux/err.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/rcupdate.h>
|
|
#include <linux/refcount.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/spinlock.h>
|
|
|
|
#include "object.h"
|
|
|
|
struct landlock_object *
|
|
landlock_create_object(const struct landlock_object_underops *const underops,
|
|
void *const underobj)
|
|
{
|
|
struct landlock_object *new_object;
|
|
|
|
if (WARN_ON_ONCE(!underops || !underobj))
|
|
return ERR_PTR(-ENOENT);
|
|
new_object = kzalloc(sizeof(*new_object), GFP_KERNEL_ACCOUNT);
|
|
if (!new_object)
|
|
return ERR_PTR(-ENOMEM);
|
|
refcount_set(&new_object->usage, 1);
|
|
spin_lock_init(&new_object->lock);
|
|
new_object->underops = underops;
|
|
new_object->underobj = underobj;
|
|
return new_object;
|
|
}
|
|
|
|
/*
|
|
* The caller must own the object (i.e. thanks to object->usage) to safely put
|
|
* it.
|
|
*/
|
|
void landlock_put_object(struct landlock_object *const object)
|
|
{
|
|
/*
|
|
* The call to @object->underops->release(object) might sleep, e.g.
|
|
* because of iput().
|
|
*/
|
|
might_sleep();
|
|
if (!object)
|
|
return;
|
|
|
|
/*
|
|
* If the @object's refcount cannot drop to zero, we can just decrement
|
|
* the refcount without holding a lock. Otherwise, the decrement must
|
|
* happen under @object->lock for synchronization with things like
|
|
* get_inode_object().
|
|
*/
|
|
if (refcount_dec_and_lock(&object->usage, &object->lock)) {
|
|
__acquire(&object->lock);
|
|
/*
|
|
* With @object->lock initially held, remove the reference from
|
|
* @object->underobj to @object (if it still exists).
|
|
*/
|
|
object->underops->release(object);
|
|
kfree_rcu(object, rcu_free);
|
|
}
|
|
}
|