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 /*
  30  * Pre-parsed payload, used by key add, update and instantiate.
  31  *
  32  * This struct will be cleared and data and datalen will be set with the data
  33  * and length parameters from the caller and quotalen will be set from
  34  * def_datalen from the key type.  Then if the preparse() op is provided by the
  35  * key type, that will be called.  Then the struct will be passed to the
  36  * instantiate() or the update() op.
  37  *
  38  * If the preparse() op is given, the free_preparse() op will be called to
  39  * clear the contents.
  40  */
  41 struct key_preparsed_payload {
  42         char            *description;   /* Proposed key description (or NULL) */
  43         void            *type_data[2];  /* Private key-type data */
  44         void            *payload;       /* Proposed payload */
  45         const void      *data;          /* Raw data */
  46         size_t          datalen;        /* Raw datalen */
  47         size_t          quotalen;       /* Quota length for proposed payload */
  48 };
  49
  50 typedef int (*request_key_actor_t)(struct key_construction *key,
  51                                    const char *op, void *aux);
  52
  53 /*
  54  * kernel managed key type definition
  55  */
  56 struct key_type {
  57         /* name of the type */
  58         const char *name;
  59
  60         /* default payload length for quota precalculation (optional)
  61          * - this can be used instead of calling key_payload_reserve(), that
  62          *   function only needs to be called if the real datalen is different
  63          */
  64         size_t def_datalen;
  65
  66         /* vet a description */
  67         int (*vet_description)(const char *description);
  68
  69         /* Preparse the data blob from userspace that is to be the payload,
  70          * generating a proposed description and payload that will be handed to
  71          * the instantiate() and update() ops.
  72          */
  73         int (*preparse)(struct key_preparsed_payload *prep);
  74
  75         /* Free a preparse data structure.
  76          */
  77         void (*free_preparse)(struct key_preparsed_payload *prep);
  78
  79         /* instantiate a key of this type
  80          * - this method should call key_payload_reserve() to determine if the
  81          *   user's quota will hold the payload
  82          */
  83         int (*instantiate)(struct key *key, struct key_preparsed_payload *prep);
  84
  85         /* update a key of this type (optional)
  86          * - this method should call key_payload_reserve() to recalculate the
  87          *   quota consumption
  88          * - the key must be locked against read when modifying
  89          */
  90         int (*update)(struct key *key, struct key_preparsed_payload *prep);
  91
  92         /* match a key against a description */
  93         int (*match)(const struct key *key, const void *desc);
  94
  95         /* clear some of the data from a key on revokation (optional)
  96          * - the key's semaphore will be write-locked by the caller
  97          */
  98         void (*revoke)(struct key *key);
  99
 100         /* clear the data from a key (optional) */
 101         void (*destroy)(struct key *key);
 102
 103         /* describe a key */
 104         void (*describe)(const struct key *key, struct seq_file *p);
 105
 106         /* read a key's data (optional)
 107          * - permission checks will be done by the caller
 108          * - the key's semaphore will be readlocked by the caller
 109          * - should return the amount of data that could be read, no matter how
 110          *   much is copied into the buffer
 111          * - shouldn't do the copy if the buffer is NULL
 112          */
 113         long (*read)(const struct key *key, char __user *buffer, size_t buflen);
 114
 115         /* handle request_key() for this type instead of invoking
 116          * /sbin/request-key (optional)
 117          * - key is the key to instantiate
 118          * - authkey is the authority to assume when instantiating this key
 119          * - op is the operation to be done, usually "create"
 120          * - the call must not return until the instantiation process has run
 121          *   its course
 122          */
 123         request_key_actor_t request_key;
 124
 125         /* internal fields */
 126         struct list_head        link;           /* link in types list */
 127         struct lock_class_key   lock_class;     /* key->sem lock class */
 128 };
 129
 130 extern struct key_type key_type_keyring;
 131
 132 extern int register_key_type(struct key_type *ktype);
 133 extern void unregister_key_type(struct key_type *ktype);
 134
 135 extern int key_payload_reserve(struct key *key, size_t datalen);
 136 extern int key_instantiate_and_link(struct key *key,
 137                                     const void *data,
 138                                     size_t datalen,
 139                                     struct key *keyring,
 140                                     struct key *instkey);
 141 extern int key_reject_and_link(struct key *key,
 142                                unsigned timeout,
 143                                unsigned error,
 144                                struct key *keyring,
 145                                struct key *instkey);
 146 extern void complete_request_key(struct key_construction *cons, int error);
 147
 148 static inline int key_negate_and_link(struct key *key,
 149                                       unsigned timeout,
 150                                       struct key *keyring,
 151                                       struct key *instkey)
 152 {
 153         return key_reject_and_link(key, timeout, ENOKEY, keyring, instkey);
 154 }
 155
 156 #endif /* CONFIG_KEYS */
 157 #endif /* _LINUX_KEY_TYPE_H */