include/keys/asymmetric-type.h

   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 */