1 /* In-software asymmetric public-key crypto subtype
2  *
3  * See Documentation/crypto/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 #define pr_fmt(fmt) "PKEY: "fmt
15 #include <linux/module.h>
16 #include <linux/export.h>
17 #include <linux/kernel.h>
18 #include <linux/slab.h>
19 #include <linux/seq_file.h>
20 #include <keys/asymmetric-subtype.h>
21 #include "public_key.h"
22 
23 MODULE_LICENSE("GPL");
24 
25 const char *const pkey_algo_name[PKEY_ALGO__LAST] = {
26 	[PKEY_ALGO_DSA]		= "DSA",
27 	[PKEY_ALGO_RSA]		= "RSA",
28 };
29 EXPORT_SYMBOL_GPL(pkey_algo_name);
30 
31 const struct public_key_algorithm *pkey_algo[PKEY_ALGO__LAST] = {
32 #if defined(CONFIG_PUBLIC_KEY_ALGO_RSA) || \
33 	defined(CONFIG_PUBLIC_KEY_ALGO_RSA_MODULE)
34 	[PKEY_ALGO_RSA]		= &RSA_public_key_algorithm,
35 #endif
36 };
37 EXPORT_SYMBOL_GPL(pkey_algo);
38 
39 const char *const pkey_id_type_name[PKEY_ID_TYPE__LAST] = {
40 	[PKEY_ID_PGP]		= "PGP",
41 	[PKEY_ID_X509]		= "X509",
42 	[PKEY_ID_PKCS7]		= "PKCS#7",
43 };
44 EXPORT_SYMBOL_GPL(pkey_id_type_name);
45 
46 /*
47  * Provide a part of a description of the key for /proc/keys.
48  */
49 static void public_key_describe(const struct key *asymmetric_key,
50 				struct seq_file *m)
51 {
52 	struct public_key *key = asymmetric_key->payload.data[asym_crypto];
53 
54 	if (key)
55 		seq_printf(m, "%s.%s",
56 			   pkey_id_type_name[key->id_type], key->algo->name);
57 }
58 
59 /*
60  * Destroy a public key algorithm key.
61  */
62 void public_key_destroy(void *payload)
63 {
64 	struct public_key *key = payload;
65 	int i;
66 
67 	if (key) {
68 		for (i = 0; i < ARRAY_SIZE(key->mpi); i++)
69 			mpi_free(key->mpi[i]);
70 		kfree(key);
71 	}
72 }
73 EXPORT_SYMBOL_GPL(public_key_destroy);
74 
75 /*
76  * Verify a signature using a public key.
77  */
78 int public_key_verify_signature(const struct public_key *pk,
79 				const struct public_key_signature *sig)
80 {
81 	const struct public_key_algorithm *algo;
82 
83 	BUG_ON(!pk);
84 	BUG_ON(!pk->mpi[0]);
85 	BUG_ON(!pk->mpi[1]);
86 	BUG_ON(!sig);
87 	BUG_ON(!sig->digest);
88 	BUG_ON(!sig->mpi[0]);
89 
90 	algo = pk->algo;
91 	if (!algo) {
92 		if (pk->pkey_algo >= PKEY_ALGO__LAST)
93 			return -ENOPKG;
94 		algo = pkey_algo[pk->pkey_algo];
95 		if (!algo)
96 			return -ENOPKG;
97 	}
98 
99 	if (!algo->verify_signature)
100 		return -ENOTSUPP;
101 
102 	if (sig->nr_mpi != algo->n_sig_mpi) {
103 		pr_debug("Signature has %u MPI not %u\n",
104 			 sig->nr_mpi, algo->n_sig_mpi);
105 		return -EINVAL;
106 	}
107 
108 	return algo->verify_signature(pk, sig);
109 }
110 EXPORT_SYMBOL_GPL(public_key_verify_signature);
111 
112 static int public_key_verify_signature_2(const struct key *key,
113 					 const struct public_key_signature *sig)
114 {
115 	const struct public_key *pk = key->payload.data[asym_crypto];
116 	return public_key_verify_signature(pk, sig);
117 }
118 
119 /*
120  * Public key algorithm asymmetric key subtype
121  */
122 struct asymmetric_key_subtype public_key_subtype = {
123 	.owner			= THIS_MODULE,
124 	.name			= "public_key",
125 	.name_len		= sizeof("public_key") - 1,
126 	.describe		= public_key_describe,
127 	.destroy		= public_key_destroy,
128 	.verify_signature	= public_key_verify_signature_2,
129 };
130 EXPORT_SYMBOL_GPL(public_key_subtype);
131