// 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_obj(*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);	}}