root/include/linux/key-type.h

INCLUDED FROM

/* Definitions for key type implementations
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * 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.
 */

#ifndef _LINUX_KEY_TYPE_H
#define _LINUX_KEY_TYPE_H

#include <linux/key.h>

#ifdef CONFIG_KEYS

/*
 * 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;

        /* 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 */
};

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_negate_and_link(struct key *key,
                               unsigned timeout,
                               struct key *keyring,
                               struct key *instkey);
extern void complete_request_key(struct key_construction *cons, int error);

#endif /* CONFIG_KEYS */
#endif /* _LINUX_KEY_TYPE_H */