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 };
  49
  50 typedef int (*request_key_actor_t)(struct key_construction *key,
  51                                    const char *op, void *aux);
  52
  53 /*
  54  * Preparsed matching criterion.
  55  */
  56 struct key_match_data {
  57         /* Comparison function, defaults to exact description match, but can be
  58          * overridden by type->match_preparse().  Should return true if a match
  59          * is found and false if not.
  60          */
  61         bool (*cmp)(const struct key *key,
  62                     const struct key_match_data *match_data);
  63
  64         const void      *raw_data;      /* Raw match data */
  65         void            *preparsed;     /* For ->match_preparse() to stash stuff */
  66         unsigned        lookup_type;    /* Type of lookup for this search. */
  67 #define KEYRING_SEARCH_LOOKUP_DIRECT    0x0000  /* Direct lookup by description. */
  68 #define KEYRING_SEARCH_LOOKUP_ITERATE   0x0001  /* Iterative search. */
  69 };
  70
  71 /*
  72  * kernel managed key type definition
  73  */
  74 struct key_type {
  75         /* name of the type */
  76         const char *name;
  77
  78         /* default payload length for quota precalculation (optional)
  79          * - this can be used instead of calling key_payload_reserve(), that
  80          *   function only needs to be called if the real datalen is different
  81          */
  82         size_t def_datalen;
  83
  84         /* vet a description */
  85         int (*vet_description)(const char *description);
  86
  87         /* Preparse the data blob from userspace that is to be the payload,
  88          * generating a proposed description and payload that will be handed to
  89          * the instantiate() and update() ops.
  90          */
  91         int (*preparse)(struct key_preparsed_payload *prep);
  92
  93         /* Free a preparse data structure.
  94          */
  95         void (*free_preparse)(struct key_preparsed_payload *prep);
  96
  97         /* instantiate a key of this type
  98          * - this method should call key_payload_reserve() to determine if the
  99          *   user's quota will hold the payload
 100          */
 101         int (*instantiate)(struct key *key, struct key_preparsed_payload *prep);
 102
 103         /* update a key of this type (optional)
 104          * - this method should call key_payload_reserve() to recalculate the
 105          *   quota consumption
 106          * - the key must be locked against read when modifying
 107          */
 108         int (*update)(struct key *key, struct key_preparsed_payload *prep);
 109
 110         /* Preparse the data supplied to ->match() (optional).  The
 111          * data to be preparsed can be found in match_data->raw_data.
 112          * The lookup type can also be set by this function.
 113          */
 114         int (*match_preparse)(struct key_match_data *match_data);
 115
 116         /* Free preparsed match data (optional).  This should be supplied it
 117          * ->match_preparse() is supplied. */
 118         void (*match_free)(struct key_match_data *match_data);
 119
 120         /* clear some of the data from a key on revokation (optional)
 121          * - the key's semaphore will be write-locked by the caller
 122          */
 123         void (*revoke)(struct key *key);
 124
 125         /* clear the data from a key (optional) */
 126         void (*destroy)(struct key *key);
 127
 128         /* describe a key */
 129         void (*describe)(const struct key *key, struct seq_file *p);
 130
 131         /* read a key's data (optional)
 132          * - permission checks will be done by the caller
 133          * - the key's semaphore will be readlocked by the caller
 134          * - should return the amount of data that could be read, no matter how
 135          *   much is copied into the buffer
 136          * - shouldn't do the copy if the buffer is NULL
 137          */
 138         long (*read)(const struct key *key, char __user *buffer, size_t buflen);
 139
 140         /* handle request_key() for this type instead of invoking
 141          * /sbin/request-key (optional)
 142          * - key is the key to instantiate
 143          * - authkey is the authority to assume when instantiating this key
 144          * - op is the operation to be done, usually "create"
 145          * - the call must not return until the instantiation process has run
 146          *   its course
 147          */
 148         request_key_actor_t request_key;
 149
 150         /* Look up a keyring access restriction (optional)
 151          *
 152          * - NULL is a valid return value (meaning the requested restriction
 153          *   is known but will never block addition of a key)
 154          * - should return -EINVAL if the restriction is unknown
 155          */
 156         struct key_restriction *(*lookup_restriction)(const char *params);
 157
 158         /* internal fields */
 159         struct list_head        link;           /* link in types list */
 160         struct lock_class_key   lock_class;     /* key->sem lock class */
 161 };
 162
 163 extern struct key_type key_type_keyring;
 164
 165 extern int register_key_type(struct key_type *ktype);
 166 extern void unregister_key_type(struct key_type *ktype);
 167
 168 extern int key_payload_reserve(struct key *key, size_t datalen);
 169 extern int key_instantiate_and_link(struct key *key,
 170                                     const void *data,
 171                                     size_t datalen,
 172                                     struct key *keyring,
 173                                     struct key *instkey);
 174 extern int key_reject_and_link(struct key *key,
 175                                unsigned timeout,
 176                                unsigned error,
 177                                struct key *keyring,
 178                                struct key *instkey);
 179 extern void complete_request_key(struct key_construction *cons, int error);
 180
 181 static inline int key_negate_and_link(struct key *key,
 182                                       unsigned timeout,
 183                                       struct key *keyring,
 184                                       struct key *instkey)
 185 {
 186         return key_reject_and_link(key, timeout, ENOKEY, keyring, instkey);
 187 }
 188
 189 extern int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep);
 190
 191 #endif /* CONFIG_KEYS */
 192 #endif /* _LINUX_KEY_TYPE_H */