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 */