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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Landlock LSM - Object management
- *
- * Copyright © 2016-2020 Mickaël Salaün <[email protected]>
- * 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);
- }
- }
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