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         bool            trusted;        /* True if key is trusted */
  49 };
  50
  51 typedef int (*request_key_actor_t)(struct key_construction *key,
  52                                    const char *op, void *aux);
  53
  54 /*
  55  * kernel managed key type definition
  56  */
  57 struct key_type {
  58         /* name of the type */
  59         const char *name;
  60
  61         /* default payload length for quota precalculation (optional)
  62          * - this can be used instead of calling key_payload_reserve(), that
  63          *   function only needs to be called if the real datalen is different
  64          */
  65         size_t def_datalen;
  66
  67         /* Default key search algorithm. */
  68         unsigned def_lookup_type;
  69 #define KEYRING_SEARCH_LOOKUP_DIRECT    0x0000  /* Direct lookup by description. */
  70 #define KEYRING_SEARCH_LOOKUP_ITERATE   0x0001  /* Iterative search. */
  71
  72         /* vet a description */
  73         int (*vet_description)(const char *description);
  74
  75         /* Preparse the data blob from userspace that is to be the payload,
  76          * generating a proposed description and payload that will be handed to
  77          * the instantiate() and update() ops.
  78          */
  79         int (*preparse)(struct key_preparsed_payload *prep);
  80
  81         /* Free a preparse data structure.
  82          */
  83         void (*free_preparse)(struct key_preparsed_payload *prep);
  84
  85         /* instantiate a key of this type
  86          * - this method should call key_payload_reserve() to determine if the
  87          *   user's quota will hold the payload
  88          */
  89         int (*instantiate)(struct key *key, struct key_preparsed_payload *prep);
  90
  91         /* update a key of this type (optional)
  92          * - this method should call key_payload_reserve() to recalculate the
  93          *   quota consumption
  94          * - the key must be locked against read when modifying
  95          */
  96         int (*update)(struct key *key, struct key_preparsed_payload *prep);
  97
  98         /* match a key against a description */
  99         int (*match)(const struct key *key, const void *desc);
 100
 101         /* clear some of the data from a key on revokation (optional)
 102          * - the key's semaphore will be write-locked by the caller
 103          */
 104         void (*revoke)(struct key *key);
 105
 106         /* clear the data from a key (optional) */
 107         void (*destroy)(struct key *key);
 108
 109         /* describe a key */
 110         void (*describe)(const struct key *key, struct seq_file *p);
 111
 112         /* read a key's data (optional)
 113          * - permission checks will be done by the caller
 114          * - the key's semaphore will be readlocked by the caller
 115          * - should return the amount of data that could be read, no matter how
 116          *   much is copied into the buffer
 117          * - shouldn't do the copy if the buffer is NULL
 118          */
 119         long (*read)(const struct key *key, char __user *buffer, size_t buflen);
 120
 121         /* handle request_key() for this type instead of invoking
 122          * /sbin/request-key (optional)
 123          * - key is the key to instantiate
 124          * - authkey is the authority to assume when instantiating this key
 125          * - op is the operation to be done, usually "create"
 126          * - the call must not return until the instantiation process has run
 127          *   its course
 128          */
 129         request_key_actor_t request_key;
 130
 131         /* internal fields */
 132         struct list_head        link;           /* link in types list */
 133         struct lock_class_key   lock_class;     /* key->sem lock class */
 134 };
 135
 136 extern struct key_type key_type_keyring;
 137
 138 extern int register_key_type(struct key_type *ktype);
 139 extern void unregister_key_type(struct key_type *ktype);
 140
 141 extern int key_payload_reserve(struct key *key, size_t datalen);
 142 extern int key_instantiate_and_link(struct key *key,
 143                                     const void *data,
 144                                     size_t datalen,
 145                                     struct key *keyring,
 146                                     struct key *instkey);
 147 extern int key_reject_and_link(struct key *key,
 148                                unsigned timeout,
 149                                unsigned error,
 150                                struct key *keyring,
 151                                struct key *instkey);
 152 extern void complete_request_key(struct key_construction *cons, int error);
 153
 154 static inline int key_negate_and_link(struct key *key,
 155                                       unsigned timeout,
 156                                       struct key *keyring,
 157                                       struct key *instkey)
 158 {
 159         return key_reject_and_link(key, timeout, ENOKEY, keyring, instkey);
 160 }
 161
 162 #endif /* CONFIG_KEYS */
 163 #endif /* _LINUX_KEY_TYPE_H */