1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* Asymmetric Public-key cryptography key type interface
3  *
4  * See Documentation/crypto/asymmetric-keys.rst
5  *
6  * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
7  * Written by David Howells (dhowells@redhat.com)
8  */
9 
10 #ifndef _KEYS_ASYMMETRIC_TYPE_H
11 #define _KEYS_ASYMMETRIC_TYPE_H
12 
13 #include <linux/key-type.h>
14 #include <linux/verification.h>
15 
16 extern struct key_type key_type_asymmetric;
17 
18 /*
19  * The key payload is four words.  The asymmetric-type key uses them as
20  * follows:
21  */
22 enum asymmetric_payload_bits {
23 	asym_crypto,		/* The data representing the key */
24 	asym_subtype,		/* Pointer to an asymmetric_key_subtype struct */
25 	asym_key_ids,		/* Pointer to an asymmetric_key_ids struct */
26 	asym_auth		/* The key's authorisation (signature, parent key ID) */
27 };
28 
29 /*
30  * Identifiers for an asymmetric key ID.  We have three ways of looking up a
31  * key derived from an X.509 certificate:
32  *
33  * (1) Serial Number & Issuer.  Non-optional.  This is the only valid way to
34  *     map a PKCS#7 signature to an X.509 certificate.
35  *
36  * (2) Issuer & Subject Unique IDs.  Optional.  These were the original way to
37  *     match X.509 certificates, but have fallen into disuse in favour of (3).
38  *
39  * (3) Auth & Subject Key Identifiers.  Optional.  SKIDs are only provided on
40  *     CA keys that are intended to sign other keys, so don't appear in end
41  *     user certificates unless forced.
42  *
43  * We could also support an PGP key identifier, which is just a SHA1 sum of the
44  * public key and certain parameters, but since we don't support PGP keys at
45  * the moment, we shall ignore those.
46  *
47  * What we actually do is provide a place where binary identifiers can be
48  * stashed and then compare against them when checking for an id match.
49  */
50 struct asymmetric_key_id {
51 	unsigned short	len;
52 	unsigned char	data[];
53 };
54 
55 struct asymmetric_key_ids {
56 	void		*id[2];
57 };
58 
59 extern bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
60 				   const struct asymmetric_key_id *kid2);
61 
62 extern bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
63 				      const struct asymmetric_key_id *kid2);
64 
65 extern struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
66 							    size_t len_1,
67 							    const void *val_2,
68 							    size_t len_2);
69 static inline
70 const struct asymmetric_key_ids *asymmetric_key_ids(const struct key *key)
71 {
72 	return key->payload.data[asym_key_ids];
73 }
74 
75 extern struct key *find_asymmetric_key(struct key *keyring,
76 				       const struct asymmetric_key_id *id_0,
77 				       const struct asymmetric_key_id *id_1,
78 				       bool partial);
79 
80 /*
81  * The payload is at the discretion of the subtype.
82  */
83 
84 #endif /* _KEYS_ASYMMETRIC_TYPE_H */
85