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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
- */
- #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 */
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