include/linux/key-type.h

   1 /* Definitions for key type implementations
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11
  12 #ifndef _LINUX_KEY_TYPE_H
  13 #define _LINUX_KEY_TYPE_H
  14
  15 #include <linux/key.h>
  16 #include <linux/errno.h>
  17
  18 #ifdef CONFIG_KEYS
  19
  20 /*
  21  * key under-construction record
  22  * - passed to the request_key actor if supplied
  23  */
  24 struct key_construction {
  25         struct key      *key;   /* key being constructed */
  26         struct key      *authkey;/* authorisation for key being constructed */
  27 };
  28
  29 typedef int (*request_key_actor_t)(struct key_construction *key,
  30                                    const char *op, void *aux);
  31
  32 /*
  33  * kernel managed key type definition
  34  */
  35 struct key_type {
  36         /* name of the type */
  37         const char *name;
  38
  39         /* default payload length for quota precalculation (optional)
  40          * - this can be used instead of calling key_payload_reserve(), that
  41          *   function only needs to be called if the real datalen is different
  42          */
  43         size_t def_datalen;
  44
  45         /* vet a description */
  46         int (*vet_description)(const char *description);
  47
  48         /* instantiate a key of this type
  49          * - this method should call key_payload_reserve() to determine if the
  50          *   user's quota will hold the payload
  51          */
  52         int (*instantiate)(struct key *key, const void *data, size_t datalen);
  53
  54         /* update a key of this type (optional)
  55          * - this method should call key_payload_reserve() to recalculate the
  56          *   quota consumption
  57          * - the key must be locked against read when modifying
  58          */
  59         int (*update)(struct key *key, const void *data, size_t datalen);
  60
  61         /* match a key against a description */
  62         int (*match)(const struct key *key, const void *desc);
  63
  64         /* clear some of the data from a key on revokation (optional)
  65          * - the key's semaphore will be write-locked by the caller
  66          */
  67         void (*revoke)(struct key *key);
  68
  69         /* clear the data from a key (optional) */
  70         void (*destroy)(struct key *key);
  71
  72         /* describe a key */
  73         void (*describe)(const struct key *key, struct seq_file *p);
  74
  75         /* read a key's data (optional)
  76          * - permission checks will be done by the caller
  77          * - the key's semaphore will be readlocked by the caller
  78          * - should return the amount of data that could be read, no matter how
  79          *   much is copied into the buffer
  80          * - shouldn't do the copy if the buffer is NULL
  81          */
  82         long (*read)(const struct key *key, char __user *buffer, size_t buflen);
  83
  84         /* handle request_key() for this type instead of invoking
  85          * /sbin/request-key (optional)
  86          * - key is the key to instantiate
  87          * - authkey is the authority to assume when instantiating this key
  88          * - op is the operation to be done, usually "create"
  89          * - the call must not return until the instantiation process has run
  90          *   its course
  91          */
  92         request_key_actor_t request_key;
  93
  94         /* internal fields */
  95         struct list_head        link;           /* link in types list */
  96         struct lock_class_key   lock_class;     /* key->sem lock class */
  97 };
  98
  99 extern struct key_type key_type_keyring;
 100
 101 extern int register_key_type(struct key_type *ktype);
 102 extern void unregister_key_type(struct key_type *ktype);
 103
 104 extern int key_payload_reserve(struct key *key, size_t datalen);
 105 extern int key_instantiate_and_link(struct key *key,
 106                                     const void *data,
 107                                     size_t datalen,
 108                                     struct key *keyring,
 109                                     struct key *instkey);
 110 extern int key_reject_and_link(struct key *key,
 111                                unsigned timeout,
 112                                unsigned error,
 113                                struct key *keyring,
 114                                struct key *instkey);
 115 extern void complete_request_key(struct key_construction *cons, int error);
 116
 117 static inline int key_negate_and_link(struct key *key,
 118                                       unsigned timeout,
 119                                       struct key *keyring,
 120                                       struct key *instkey)
 121 {
 122         return key_reject_and_link(key, timeout, ENOKEY, keyring, instkey);
 123 }
 124
 125 #endif /* CONFIG_KEYS */
 126 #endif /* _LINUX_KEY_TYPE_H */