include/keys/asymmetric-type.h

   1 /* Asymmetric Public-key cryptography key type interface
   2  *
   3  * See Documentation/security/asymmetric-keys.txt
   4  *
   5  * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
   6  * Written by David Howells (dhowells@redhat.com)
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public Licence
  10  * as published by the Free Software Foundation; either version
  11  * 2 of the Licence, or (at your option) any later version.
  12  */
  13
  14 #ifndef _KEYS_ASYMMETRIC_TYPE_H
  15 #define _KEYS_ASYMMETRIC_TYPE_H
  16
  17 #include <linux/key-type.h>
  18 #include <linux/verification.h>
  19
  20 extern struct key_type key_type_asymmetric;
  21
  22 /*
  23  * The key payload is four words.  The asymmetric-type key uses them as
  24  * follows:
  25  */
  26 enum asymmetric_payload_bits {
  27         asym_crypto,            /* The data representing the key */
  28         asym_subtype,           /* Pointer to an asymmetric_key_subtype struct */
  29         asym_key_ids,           /* Pointer to an asymmetric_key_ids struct */
  30         asym_auth               /* The key's authorisation (signature, parent key ID) */
  31 };
  32
  33 /*
  34  * Identifiers for an asymmetric key ID.  We have three ways of looking up a
  35  * key derived from an X.509 certificate:
  36  *
  37  * (1) Serial Number & Issuer.  Non-optional.  This is the only valid way to
  38  *     map a PKCS#7 signature to an X.509 certificate.
  39  *
  40  * (2) Issuer & Subject Unique IDs.  Optional.  These were the original way to
  41  *     match X.509 certificates, but have fallen into disuse in favour of (3).
  42  *
  43  * (3) Auth & Subject Key Identifiers.  Optional.  SKIDs are only provided on
  44  *     CA keys that are intended to sign other keys, so don't appear in end
  45  *     user certificates unless forced.
  46  *
  47  * We could also support an PGP key identifier, which is just a SHA1 sum of the
  48  * public key and certain parameters, but since we don't support PGP keys at
  49  * the moment, we shall ignore those.
  50  *
  51  * What we actually do is provide a place where binary identifiers can be
  52  * stashed and then compare against them when checking for an id match.
  53  */
  54 struct asymmetric_key_id {
  55         unsigned short  len;
  56         unsigned char   data[];
  57 };
  58
  59 struct asymmetric_key_ids {
  60         void            *id[2];
  61 };
  62
  63 extern bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
  64                                    const struct asymmetric_key_id *kid2);
  65
  66 extern bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
  67                                       const struct asymmetric_key_id *kid2);
  68
  69 extern struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
  70                                                             size_t len_1,
  71                                                             const void *val_2,
  72                                                             size_t len_2);
  73 static inline
  74 const struct asymmetric_key_ids *asymmetric_key_ids(const struct key *key)
  75 {
  76         return key->payload.data[asym_key_ids];
  77 }
  78
  79 extern struct key *find_asymmetric_key(struct key *keyring,
  80                                        const struct asymmetric_key_id *id_0,
  81                                        const struct asymmetric_key_id *id_1,
  82                                        bool partial);
  83
  84 /*
  85  * The payload is at the discretion of the subtype.
  86  */
  87
  88 #endif /* _KEYS_ASYMMETRIC_TYPE_H */