linux-brain/include/keys/user-type.h

/* SPDX-License-Identifier: GPL-2.0-or-later */
/* user-type.h: User-defined key type
 *
 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#ifndef _KEYS_USER_TYPE_H
#define _KEYS_USER_TYPE_H

#include <linux/key.h>
#include <linux/rcupdate.h>

#ifdef CONFIG_KEYS

/*****************************************************************************/
/*
 * the payload for a key of type "user" or "logon"
 * - once filled in and attached to a key:
 *   - the payload struct is invariant may not be changed, only replaced
 *   - the payload must be read with RCU procedures or with the key semaphore
 *     held
 *   - the payload may only be replaced with the key semaphore write-locked
 * - the key's data length is the size of the actual data, not including the
 *   payload wrapper
 */
struct user_key_payload {
	struct rcu_head	rcu;		/* RCU destructor */
	unsigned short	datalen;	/* length of this data */
	char		data[0] __aligned(__alignof__(u64)); /* actual data */
};

extern struct key_type key_type_user;
extern struct key_type key_type_logon;

struct key_preparsed_payload;

extern int user_preparse(struct key_preparsed_payload *prep);
extern void user_free_preparse(struct key_preparsed_payload *prep);
extern int user_update(struct key *key, struct key_preparsed_payload *prep);
extern void user_revoke(struct key *key);
extern void user_destroy(struct key *key);
extern void user_describe(const struct key *user, struct seq_file *m);
extern long user_read(const struct key *key, char *buffer, size_t buflen);

static inline const struct user_key_payload *user_key_payload_rcu(const struct key *key)
{
	return (struct user_key_payload *)dereference_key_rcu(key);
}

static inline struct user_key_payload *user_key_payload_locked(const struct key *key)
{
	return (struct user_key_payload *)dereference_key_locked((struct key *)key);
}

#endif /* CONFIG_KEYS */

#endif /* _KEYS_USER_TYPE_H */