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/* Definitions for key type implementations
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
#include <linux/key.h>
* key under-construction record
* - passed to the request_key actor if supplied
struct key_construction {
struct key *key; /* key being constructed */
struct key *authkey;/* authorisation for key being constructed */
typedef int (*request_key_actor_t)(struct key_construction *key,
const char *op, void *aux);
* kernel managed key type definition
struct key_type {
/* name of the type */
const char *name;
/* default payload length for quota precalculation (optional)
* - this can be used instead of calling key_payload_reserve(), that
* function only needs to be called if the real datalen is different
size_t def_datalen;
/* vet a description */
int (*vet_description)(const char *description);
/* instantiate a key of this type
* - this method should call key_payload_reserve() to determine if the
* user's quota will hold the payload
int (*instantiate)(struct key *key, const void *data, size_t datalen);
/* update a key of this type (optional)
* - this method should call key_payload_reserve() to recalculate the
* quota consumption
* - the key must be locked against read when modifying
int (*update)(struct key *key, const void *data, size_t datalen);
/* match a key against a description */
int (*match)(const struct key *key, const void *desc);
/* clear some of the data from a key on revokation (optional)
* - the key's semaphore will be write-locked by the caller
void (*revoke)(struct key *key);
/* clear the data from a key (optional) */
void (*destroy)(struct key *key);
/* describe a key */
void (*describe)(const struct key *key, struct seq_file *p);
/* read a key's data (optional)
* - permission checks will be done by the caller
* - the key's semaphore will be readlocked by the caller
* - should return the amount of data that could be read, no matter how
* much is copied into the buffer
* - shouldn't do the copy if the buffer is NULL
long (*read)(const struct key *key, char __user *buffer, size_t buflen);
/* handle request_key() for this type instead of invoking
* /sbin/request-key (optional)
* - key is the key to instantiate
* - authkey is the authority to assume when instantiating this key
* - op is the operation to be done, usually "create"
* - the call must not return until the instantiation process has run
* its course
request_key_actor_t request_key;
/* internal fields */
struct list_head link; /* link in types list */
struct lock_class_key lock_class; /* key->sem lock class */
extern struct key_type key_type_keyring;
extern int register_key_type(struct key_type *ktype);
extern void unregister_key_type(struct key_type *ktype);
extern int key_payload_reserve(struct key *key, size_t datalen);
extern int key_instantiate_and_link(struct key *key,
const void *data,
size_t datalen,
struct key *keyring,
struct key *instkey);
extern int key_reject_and_link(struct key *key,
unsigned timeout,
unsigned error,
struct key *keyring,
struct key *instkey);
extern void complete_request_key(struct key_construction *cons, int error);
static inline int key_negate_and_link(struct key *key,
unsigned timeout,
struct key *keyring,
struct key *instkey)
return key_reject_and_link(key, timeout, ENOKEY, keyring, instkey);
#endif /* CONFIG_KEYS */
#endif /* _LINUX_KEY_TYPE_H */