LXR linux/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
  20extern 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 */
  26enum 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 */
  54struct asymmetric_key_id {
  55        unsigned short  len;
  56        unsigned char   data[];
  57};
  58
  59struct asymmetric_key_ids {
  60        void            *id[2];
  61};
  62
  63extern bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
  64                                   const struct asymmetric_key_id *kid2);
  65
  66extern bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
  67                                      const struct asymmetric_key_id *kid2);
  68
  69extern 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);
  73static inline
  74const struct asymmetric_key_ids *asymmetric_key_ids(const struct key *key)
  75{
  76        return key->payload.data[asym_key_ids];
  77}
  78
  79extern 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 */
  89