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 struct kernel_pkey_query;
  21 struct kernel_pkey_params;
  22
  23 /*
  24  * key under-construction record
  25  * - passed to the request_key actor if supplied
  26  */
  27 struct key_construction {
  28         struct key      *key;   /* key being constructed */
  29         struct key      *authkey;/* authorisation for key being constructed */
  30 };
  31
  32 /*
  33  * Pre-parsed payload, used by key add, update and instantiate.
  34  *
  35  * This struct will be cleared and data and datalen will be set with the data
  36  * and length parameters from the caller and quotalen will be set from
  37  * def_datalen from the key type.  Then if the preparse() op is provided by the
  38  * key type, that will be called.  Then the struct will be passed to the
  39  * instantiate() or the update() op.
  40  *
  41  * If the preparse() op is given, the free_preparse() op will be called to
  42  * clear the contents.
  43  */
  44 struct key_preparsed_payload {
  45         char            *description;   /* Proposed key description (or NULL) */
  46         union key_payload payload;      /* Proposed payload */
  47         const void      *data;          /* Raw data */
  48         size_t          datalen;        /* Raw datalen */
  49         size_t          quotalen;       /* Quota length for proposed payload */
  50         time_t          expiry;         /* Expiry time of key */
  51 };
  52
  53 typedef int (*request_key_actor_t)(struct key_construction *key,
  54                                    const char *op, void *aux);
  55
  56 /*
  57  * Preparsed matching criterion.
  58  */
  59 struct key_match_data {
  60         /* Comparison function, defaults to exact description match, but can be
  61          * overridden by type->match_preparse().  Should return true if a match
  62          * is found and false if not.
  63          */
  64         bool (*cmp)(const struct key *key,
  65                     const struct key_match_data *match_data);
  66
  67         const void      *raw_data;      /* Raw match data */
  68         void            *preparsed;     /* For ->match_preparse() to stash stuff */
  69         unsigned        lookup_type;    /* Type of lookup for this search. */
  70 #define KEYRING_SEARCH_LOOKUP_DIRECT    0x0000  /* Direct lookup by description. */
  71 #define KEYRING_SEARCH_LOOKUP_ITERATE   0x0001  /* Iterative search. */
  72 };
  73
  74 /*
  75  * kernel managed key type definition
  76  */
  77 struct key_type {
  78         /* name of the type */
  79         const char *name;
  80
  81         /* default payload length for quota precalculation (optional)
  82          * - this can be used instead of calling key_payload_reserve(), that
  83          *   function only needs to be called if the real datalen is different
  84          */
  85         size_t def_datalen;
  86
  87         /* vet a description */
  88         int (*vet_description)(const char *description);
  89
  90         /* Preparse the data blob from userspace that is to be the payload,
  91          * generating a proposed description and payload that will be handed to
  92          * the instantiate() and update() ops.
  93          */
  94         int (*preparse)(struct key_preparsed_payload *prep);
  95
  96         /* Free a preparse data structure.
  97          */
  98         void (*free_preparse)(struct key_preparsed_payload *prep);
  99
 100         /* instantiate a key of this type
 101          * - this method should call key_payload_reserve() to determine if the
 102          *   user's quota will hold the payload
 103          */
 104         int (*instantiate)(struct key *key, struct key_preparsed_payload *prep);
 105
 106         /* update a key of this type (optional)
 107          * - this method should call key_payload_reserve() to recalculate the
 108          *   quota consumption
 109          * - the key must be locked against read when modifying
 110          */
 111         int (*update)(struct key *key, struct key_preparsed_payload *prep);
 112
 113         /* Preparse the data supplied to ->match() (optional).  The
 114          * data to be preparsed can be found in match_data->raw_data.
 115          * The lookup type can also be set by this function.
 116          */
 117         int (*match_preparse)(struct key_match_data *match_data);
 118
 119         /* Free preparsed match data (optional).  This should be supplied it
 120          * ->match_preparse() is supplied. */
 121         void (*match_free)(struct key_match_data *match_data);
 122
 123         /* clear some of the data from a key on revokation (optional)
 124          * - the key's semaphore will be write-locked by the caller
 125          */
 126         void (*revoke)(struct key *key);
 127
 128         /* clear the data from a key (optional) */
 129         void (*destroy)(struct key *key);
 130
 131         /* describe a key */
 132         void (*describe)(const struct key *key, struct seq_file *p);
 133
 134         /* read a key's data (optional)
 135          * - permission checks will be done by the caller
 136          * - the key's semaphore will be readlocked by the caller
 137          * - should return the amount of data that could be read, no matter how
 138          *   much is copied into the buffer
 139          * - shouldn't do the copy if the buffer is NULL
 140          */
 141         long (*read)(const struct key *key, char __user *buffer, size_t buflen);
 142
 143         /* handle request_key() for this type instead of invoking
 144          * /sbin/request-key (optional)
 145          * - key is the key to instantiate
 146          * - authkey is the authority to assume when instantiating this key
 147          * - op is the operation to be done, usually "create"
 148          * - the call must not return until the instantiation process has run
 149          *   its course
 150          */
 151         request_key_actor_t request_key;
 152
 153         /* Asymmetric key accessor functions. */
 154         int (*asym_query)(const struct kernel_pkey_params *params,
 155                           struct kernel_pkey_query *info);
 156         int (*asym_eds_op)(struct kernel_pkey_params *params,
 157                            const void *in, void *out);
 158         int (*asym_verify_signature)(struct kernel_pkey_params *params,
 159                                      const void *in, const void *in2);
 160
 161         /* internal fields */
 162         struct list_head        link;           /* link in types list */
 163         struct lock_class_key   lock_class;     /* key->sem lock class */
 164 };
 165
 166 extern struct key_type key_type_keyring;
 167
 168 extern int register_key_type(struct key_type *ktype);
 169 extern void unregister_key_type(struct key_type *ktype);
 170
 171 extern int key_payload_reserve(struct key *key, size_t datalen);
 172 extern int key_instantiate_and_link(struct key *key,
 173                                     const void *data,
 174                                     size_t datalen,
 175                                     struct key *keyring,
 176                                     struct key *instkey);
 177 extern int key_reject_and_link(struct key *key,
 178                                unsigned timeout,
 179                                unsigned error,
 180                                struct key *keyring,
 181                                struct key *instkey);
 182 extern void complete_request_key(struct key_construction *cons, int error);
 183
 184 static inline int key_negate_and_link(struct key *key,
 185                                       unsigned timeout,
 186                                       struct key *keyring,
 187                                       struct key *instkey)
 188 {
 189         return key_reject_and_link(key, timeout, ENOKEY, keyring, instkey);
 190 }
 191
 192 extern int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep);
 193
 194 #endif /* CONFIG_KEYS */
 195 #endif /* _LINUX_KEY_TYPE_H */