// 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); } }