linux/include/linux/key-type.h
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   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 */
  24struct 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 */
  41struct 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
  50typedef int (*request_key_actor_t)(struct key_construction *key,
  51                                   const char *op, void *aux);
  52
  53/*
  54 * kernel managed key type definition
  55 */
  56struct 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
 130extern struct key_type key_type_keyring;
 131
 132extern int register_key_type(struct key_type *ktype);
 133extern void unregister_key_type(struct key_type *ktype);
 134
 135extern int key_payload_reserve(struct key *key, size_t datalen);
 136extern int key_instantiate_and_link(struct key *key,
 137                                    const void *data,
 138                                    size_t datalen,
 139                                    struct key *keyring,
 140                                    struct key *instkey);
 141extern int key_reject_and_link(struct key *key,
 142                               unsigned timeout,
 143                               unsigned error,
 144                               struct key *keyring,
 145                               struct key *instkey);
 146extern void complete_request_key(struct key_construction *cons, int error);
 147
 148static 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 */
 158
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