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 
19 extern struct key_type key_type_asymmetric;
20 
21 /*
22  * The key payload is four words.  The asymmetric-type key uses them as
23  * follows:
24  */
25 enum asymmetric_payload_bits {
26 	asym_crypto,
27 	asym_subtype,
28 	asym_key_ids,
29 };
30 
31 /*
32  * Identifiers for an asymmetric key ID.  We have three ways of looking up a
33  * key derived from an X.509 certificate:
34  *
35  * (1) Serial Number & Issuer.  Non-optional.  This is the only valid way to
36  *     map a PKCS#7 signature to an X.509 certificate.
37  *
38  * (2) Issuer & Subject Unique IDs.  Optional.  These were the original way to
39  *     match X.509 certificates, but have fallen into disuse in favour of (3).
40  *
41  * (3) Auth & Subject Key Identifiers.  Optional.  SKIDs are only provided on
42  *     CA keys that are intended to sign other keys, so don't appear in end
43  *     user certificates unless forced.
44  *
45  * We could also support an PGP key identifier, which is just a SHA1 sum of the
46  * public key and certain parameters, but since we don't support PGP keys at
47  * the moment, we shall ignore those.
48  *
49  * What we actually do is provide a place where binary identifiers can be
50  * stashed and then compare against them when checking for an id match.
51  */
52 struct asymmetric_key_id {
53 	unsigned short	len;
54 	unsigned char	data[];
55 };
56 
57 struct asymmetric_key_ids {
58 	void		*id[2];
59 };
60 
61 extern bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
62 				   const struct asymmetric_key_id *kid2);
63 
64 extern bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
65 				      const struct asymmetric_key_id *kid2);
66 
67 extern struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
68 							    size_t len_1,
69 							    const void *val_2,
70 							    size_t len_2);
71 static inline
72 const struct asymmetric_key_ids *asymmetric_key_ids(const struct key *key)
73 {
74 	return key->payload.data[asym_key_ids];
75 }
76 
77 /*
78  * The payload is at the discretion of the subtype.
79  */
80 
81 #endif /* _KEYS_ASYMMETRIC_TYPE_H */
82