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         union key_payload payload;      /* Proposed payload */
  44         const void      *data;          /* Raw data */
  45         size_t          datalen;        /* Raw datalen */
  46         size_t          quotalen;       /* Quota length for proposed payload */
  47         time_t          expiry;         /* Expiry time of key */
  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  * Preparsed matching criterion.
  56  */
  57 struct key_match_data {
  58         /* Comparison function, defaults to exact description match, but can be
  59          * overridden by type->match_preparse().  Should return true if a match
  60          * is found and false if not.
  61          */
  62         bool (*cmp)(const struct key *key,
  63                     const struct key_match_data *match_data);
  64
  65         const void      *raw_data;      /* Raw match data */
  66         void            *preparsed;     /* For ->match_preparse() to stash stuff */
  67         unsigned        lookup_type;    /* Type of lookup for this search. */
  68 #define KEYRING_SEARCH_LOOKUP_DIRECT    0x0000  /* Direct lookup by description. */
  69 #define KEYRING_SEARCH_LOOKUP_ITERATE   0x0001  /* Iterative search. */
  70 };
  71
  72 /*
  73  * kernel managed key type definition
  74  */
  75 struct key_type {
  76         /* name of the type */
  77         const char *name;
  78
  79         /* default payload length for quota precalculation (optional)
  80          * - this can be used instead of calling key_payload_reserve(), that
  81          *   function only needs to be called if the real datalen is different
  82          */
  83         size_t def_datalen;
  84
  85         /* vet a description */
  86         int (*vet_description)(const char *description);
  87
  88         /* Preparse the data blob from userspace that is to be the payload,
  89          * generating a proposed description and payload that will be handed to
  90          * the instantiate() and update() ops.
  91          */
  92         int (*preparse)(struct key_preparsed_payload *prep);
  93
  94         /* Free a preparse data structure.
  95          */
  96         void (*free_preparse)(struct key_preparsed_payload *prep);
  97
  98         /* instantiate a key of this type
  99          * - this method should call key_payload_reserve() to determine if the
 100          *   user's quota will hold the payload
 101          */
 102         int (*instantiate)(struct key *key, struct key_preparsed_payload *prep);
 103
 104         /* update a key of this type (optional)
 105          * - this method should call key_payload_reserve() to recalculate the
 106          *   quota consumption
 107          * - the key must be locked against read when modifying
 108          */
 109         int (*update)(struct key *key, struct key_preparsed_payload *prep);
 110
 111         /* Preparse the data supplied to ->match() (optional).  The
 112          * data to be preparsed can be found in match_data->raw_data.
 113          * The lookup type can also be set by this function.
 114          */
 115         int (*match_preparse)(struct key_match_data *match_data);
 116
 117         /* Free preparsed match data (optional).  This should be supplied it
 118          * ->match_preparse() is supplied. */
 119         void (*match_free)(struct key_match_data *match_data);
 120
 121         /* clear some of the data from a key on revokation (optional)
 122          * - the key's semaphore will be write-locked by the caller
 123          */
 124         void (*revoke)(struct key *key);
 125
 126         /* clear the data from a key (optional) */
 127         void (*destroy)(struct key *key);
 128
 129         /* describe a key */
 130         void (*describe)(const struct key *key, struct seq_file *p);
 131
 132         /* read a key's data (optional)
 133          * - permission checks will be done by the caller
 134          * - the key's semaphore will be readlocked by the caller
 135          * - should return the amount of data that could be read, no matter how
 136          *   much is copied into the buffer
 137          * - shouldn't do the copy if the buffer is NULL
 138          */
 139         long (*read)(const struct key *key, char __user *buffer, size_t buflen);
 140
 141         /* handle request_key() for this type instead of invoking
 142          * /sbin/request-key (optional)
 143          * - key is the key to instantiate
 144          * - authkey is the authority to assume when instantiating this key
 145          * - op is the operation to be done, usually "create"
 146          * - the call must not return until the instantiation process has run
 147          *   its course
 148          */
 149         request_key_actor_t request_key;
 150
 151         /* internal fields */
 152         struct list_head        link;           /* link in types list */
 153         struct lock_class_key   lock_class;     /* key->sem lock class */
 154 };
 155
 156 extern struct key_type key_type_keyring;
 157
 158 extern int register_key_type(struct key_type *ktype);
 159 extern void unregister_key_type(struct key_type *ktype);
 160
 161 extern int key_payload_reserve(struct key *key, size_t datalen);
 162 extern int key_instantiate_and_link(struct key *key,
 163                                     const void *data,
 164                                     size_t datalen,
 165                                     struct key *keyring,
 166                                     struct key *instkey);
 167 extern int key_reject_and_link(struct key *key,
 168                                unsigned timeout,
 169                                unsigned error,
 170                                struct key *keyring,
 171                                struct key *instkey);
 172 extern void complete_request_key(struct key_construction *cons, int error);
 173
 174 static inline int key_negate_and_link(struct key *key,
 175                                       unsigned timeout,
 176                                       struct key *keyring,
 177                                       struct key *instkey)
 178 {
 179         return key_reject_and_link(key, timeout, ENOKEY, keyring, instkey);
 180 }
 181
 182 extern int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep);
 183
 184 #endif /* CONFIG_KEYS */
 185 #endif /* _LINUX_KEY_TYPE_H */