/* SPDX-License-Identifier: GPL-2.0-only *//* * Landlock LSM - Object management * * Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net> * Copyright © 2018-2020 ANSSI */ #ifndef _SECURITY_LANDLOCK_OBJECT_H#define _SECURITY_LANDLOCK_OBJECT_H #include <linux/compiler_types.h>#include <linux/refcount.h>#include <linux/spinlock.h> struct landlock_object; /** * struct landlock_object_underops - Operations on an underlying object */struct landlock_object_underops {	/**	 * @release: Releases the underlying object (e.g. iput() for an inode).	 */	void (*release)(struct landlock_object *const object)		__releases(object->lock);}; /** * struct landlock_object - Security blob tied to a kernel object * * The goal of this structure is to enable to tie a set of ephemeral access * rights (pertaining to different domains) to a kernel object (e.g an inode) * in a safe way.  This implies to handle concurrent use and modification. * * The lifetime of a &struct landlock_object depends on the rules referring to * it. */struct landlock_object {	/**	 * @usage: This counter is used to tie an object to the rules matching	 * it or to keep it alive while adding a new rule.  If this counter	 * reaches zero, this struct must not be modified, but this counter can	 * still be read from within an RCU read-side critical section.  When	 * adding a new rule to an object with a usage counter of zero, we must	 * wait until the pointer to this object is set to NULL (or recycled).	 */	refcount_t usage;	/**	 * @lock: Protects against concurrent modifications.  This lock must be	 * held from the time @usage drops to zero until any weak references	 * from @underobj to this object have been cleaned up.	 *	 * Lock ordering: inode->i_lock nests inside this.	 */	spinlock_t lock;	/**	 * @underobj: Used when cleaning up an object and to mark an object as	 * tied to its underlying kernel structure.  This pointer is protected	 * by @lock.  Cf. landlock_release_inodes() and release_inode().	 */	void *underobj;	union {		/**		 * @rcu_free: Enables lockless use of @usage, @lock and		 * @underobj from within an RCU read-side critical section.		 * @rcu_free and @underops are only used by		 * landlock_put_object().		 */		struct rcu_head rcu_free;		/**		 * @underops: Enables landlock_put_object() to release the		 * underlying object (e.g. inode).		 */		const struct landlock_object_underops *underops;	};}; struct landlock_object *landlock_create_object(const struct landlock_object_underops *const underops,		       void *const underobj); void landlock_put_object(struct landlock_object *const object); static inline void landlock_get_object(struct landlock_object *const object){	if (object)		refcount_inc(&object->usage);} #endif /* _SECURITY_LANDLOCK_OBJECT_H */