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  * Pre-parsed payload, used by key add, update and instantiate.
  22  *
  23  * This struct will be cleared and data and datalen will be set with the data
  24  * and length parameters from the caller and quotalen will be set from
  25  * def_datalen from the key type.  Then if the preparse() op is provided by the
  26  * key type, that will be called.  Then the struct will be passed to the
  27  * instantiate() or the update() op.
  28  *
  29  * If the preparse() op is given, the free_preparse() op will be called to
  30  * clear the contents.
  31  */
  32 struct key_preparsed_payload {
  33         char            *description;   /* Proposed key description (or NULL) */
  34         union key_payload payload;      /* Proposed payload */
  35         const void      *data;          /* Raw data */
  36         size_t          datalen;        /* Raw datalen */
  37         size_t          quotalen;       /* Quota length for proposed payload */
  38         time64_t        expiry;         /* Expiry time of key */
  39 } __randomize_layout;
  40
  41 typedef int (*request_key_actor_t)(struct key *auth_key, void *aux);
  42
  43 /*
  44  * Preparsed matching criterion.
  45  */
  46 struct key_match_data {
  47         /* Comparison function, defaults to exact description match, but can be
  48          * overridden by type->match_preparse().  Should return true if a match
  49          * is found and false if not.
  50          */
  51         bool (*cmp)(const struct key *key,
  52                     const struct key_match_data *match_data);
  53
  54         const void      *raw_data;      /* Raw match data */
  55         void            *preparsed;     /* For ->match_preparse() to stash stuff */
  56         unsigned        lookup_type;    /* Type of lookup for this search. */
  57 #define KEYRING_SEARCH_LOOKUP_DIRECT    0x0000  /* Direct lookup by description. */
  58 #define KEYRING_SEARCH_LOOKUP_ITERATE   0x0001  /* Iterative search. */
  59 };
  60
  61 /*
  62  * kernel managed key type definition
  63  */
  64 struct key_type {
  65         /* name of the type */
  66         const char *name;
  67
  68         /* default payload length for quota precalculation (optional)
  69          * - this can be used instead of calling key_payload_reserve(), that
  70          *   function only needs to be called if the real datalen is different
  71          */
  72         size_t def_datalen;
  73
  74         /* vet a description */
  75         int (*vet_description)(const char *description);
  76
  77         /* Preparse the data blob from userspace that is to be the payload,
  78          * generating a proposed description and payload that will be handed to
  79          * the instantiate() and update() ops.
  80          */
  81         int (*preparse)(struct key_preparsed_payload *prep);
  82
  83         /* Free a preparse data structure.
  84          */
  85         void (*free_preparse)(struct key_preparsed_payload *prep);
  86
  87         /* instantiate a key of this type
  88          * - this method should call key_payload_reserve() to determine if the
  89          *   user's quota will hold the payload
  90          */
  91         int (*instantiate)(struct key *key, struct key_preparsed_payload *prep);
  92
  93         /* update a key of this type (optional)
  94          * - this method should call key_payload_reserve() to recalculate the
  95          *   quota consumption
  96          * - the key must be locked against read when modifying
  97          */
  98         int (*update)(struct key *key, struct key_preparsed_payload *prep);
  99
 100         /* Preparse the data supplied to ->match() (optional).  The
 101          * data to be preparsed can be found in match_data->raw_data.
 102          * The lookup type can also be set by this function.
 103          */
 104         int (*match_preparse)(struct key_match_data *match_data);
 105
 106         /* Free preparsed match data (optional).  This should be supplied it
 107          * ->match_preparse() is supplied. */
 108         void (*match_free)(struct key_match_data *match_data);
 109
 110         /* clear some of the data from a key on revokation (optional)
 111          * - the key's semaphore will be write-locked by the caller
 112          */
 113         void (*revoke)(struct key *key);
 114
 115         /* clear the data from a key (optional) */
 116         void (*destroy)(struct key *key);
 117
 118         /* describe a key */
 119         void (*describe)(const struct key *key, struct seq_file *p);
 120
 121         /* read a key's data (optional)
 122          * - permission checks will be done by the caller
 123          * - the key's semaphore will be readlocked by the caller
 124          * - should return the amount of data that could be read, no matter how
 125          *   much is copied into the buffer
 126          * - shouldn't do the copy if the buffer is NULL
 127          */
 128         long (*read)(const struct key *key, char __user *buffer, size_t buflen);
 129
 130         /* handle request_key() for this type instead of invoking
 131          * /sbin/request-key (optional)
 132          * - key is the key to instantiate
 133          * - authkey is the authority to assume when instantiating this key
 134          * - op is the operation to be done, usually "create"
 135          * - the call must not return until the instantiation process has run
 136          *   its course
 137          */
 138         request_key_actor_t request_key;
 139
 140         /* Look up a keyring access restriction (optional)
 141          *
 142          * - NULL is a valid return value (meaning the requested restriction
 143          *   is known but will never block addition of a key)
 144          * - should return -EINVAL if the restriction is unknown
 145          */
 146         struct key_restriction *(*lookup_restriction)(const char *params);
 147
 148         /* internal fields */
 149         struct list_head        link;           /* link in types list */
 150         struct lock_class_key   lock_class;     /* key->sem lock class */
 151 } __randomize_layout;
 152
 153 extern struct key_type key_type_keyring;
 154
 155 extern int register_key_type(struct key_type *ktype);
 156 extern void unregister_key_type(struct key_type *ktype);
 157
 158 extern int key_payload_reserve(struct key *key, size_t datalen);
 159 extern int key_instantiate_and_link(struct key *key,
 160                                     const void *data,
 161                                     size_t datalen,
 162                                     struct key *keyring,
 163                                     struct key *authkey);
 164 extern int key_reject_and_link(struct key *key,
 165                                unsigned timeout,
 166                                unsigned error,
 167                                struct key *keyring,
 168                                struct key *authkey);
 169 extern void complete_request_key(struct key *authkey, int error);
 170
 171 static inline int key_negate_and_link(struct key *key,
 172                                       unsigned timeout,
 173                                       struct key *keyring,
 174                                       struct key *authkey)
 175 {
 176         return key_reject_and_link(key, timeout, ENOKEY, keyring, authkey);
 177 }
 178
 179 extern int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep);
 180
 181 #endif /* CONFIG_KEYS */
 182 #endif /* _LINUX_KEY_TYPE_H */