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 */
89