/* 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;

  	/* 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 */