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 };
43 EXPORT_SYMBOL_GPL(pkey_id_type_name);
44 
45 /*
46  * Provide a part of a description of the key for /proc/keys.
47  */
48 static void public_key_describe(const struct key *asymmetric_key,
49 				struct seq_file *m)
50 {
51 	struct public_key *key = asymmetric_key->payload.data;
52 
53 	if (key)
54 		seq_printf(m, "%s.%s",
55 			   pkey_id_type_name[key->id_type], key->algo->name);
56 }
57 
58 /*
59  * Destroy a public key algorithm key.
60  */
61 void public_key_destroy(void *payload)
62 {
63 	struct public_key *key = payload;
64 	int i;
65 
66 	if (key) {
67 		for (i = 0; i < ARRAY_SIZE(key->mpi); i++)
68 			mpi_free(key->mpi[i]);
69 		kfree(key);
70 	}
71 }
72 EXPORT_SYMBOL_GPL(public_key_destroy);
73 
74 /*
75  * Verify a signature using a public key.
76  */
77 int public_key_verify_signature(const struct public_key *pk,
78 				const struct public_key_signature *sig)
79 {
80 	const struct public_key_algorithm *algo;
81 
82 	BUG_ON(!pk);
83 	BUG_ON(!pk->mpi[0]);
84 	BUG_ON(!pk->mpi[1]);
85 	BUG_ON(!sig);
86 	BUG_ON(!sig->digest);
87 	BUG_ON(!sig->mpi[0]);
88 
89 	algo = pk->algo;
90 	if (!algo) {
91 		if (pk->pkey_algo >= PKEY_ALGO__LAST)
92 			return -ENOPKG;
93 		algo = pkey_algo[pk->pkey_algo];
94 		if (!algo)
95 			return -ENOPKG;
96 	}
97 
98 	if (!algo->verify_signature)
99 		return -ENOTSUPP;
100 
101 	if (sig->nr_mpi != algo->n_sig_mpi) {
102 		pr_debug("Signature has %u MPI not %u\n",
103 			 sig->nr_mpi, algo->n_sig_mpi);
104 		return -EINVAL;
105 	}
106 
107 	return algo->verify_signature(pk, sig);
108 }
109 EXPORT_SYMBOL_GPL(public_key_verify_signature);
110 
111 static int public_key_verify_signature_2(const struct key *key,
112 					 const struct public_key_signature *sig)
113 {
114 	const struct public_key *pk = key->payload.data;
115 	return public_key_verify_signature(pk, sig);
116 }
117 
118 /*
119  * Public key algorithm asymmetric key subtype
120  */
121 struct asymmetric_key_subtype public_key_subtype = {
122 	.owner			= THIS_MODULE,
123 	.name			= "public_key",
124 	.name_len		= sizeof("public_key") - 1,
125 	.describe		= public_key_describe,
126 	.destroy		= public_key_destroy,
127 	.verify_signature	= public_key_verify_signature_2,
128 };
129 EXPORT_SYMBOL_GPL(public_key_subtype);
130