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
23MODULE_LICENSE("GPL");
24
25const char *const pkey_algo_name[PKEY_ALGO__LAST] = {
26	[PKEY_ALGO_DSA]		= "DSA",
27	[PKEY_ALGO_RSA]		= "RSA",
28};
29EXPORT_SYMBOL_GPL(pkey_algo_name);
30
31const 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};
37EXPORT_SYMBOL_GPL(pkey_algo);
38
39const char *const pkey_id_type_name[PKEY_ID_TYPE__LAST] = {
40	[PKEY_ID_PGP]		= "PGP",
41	[PKEY_ID_X509]		= "X509",
42};
43EXPORT_SYMBOL_GPL(pkey_id_type_name);
44
45/*
46 * Provide a part of a description of the key for /proc/keys.
47 */
48static 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 */
61void 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}
72EXPORT_SYMBOL_GPL(public_key_destroy);
73
74/*
75 * Verify a signature using a public key.
76 */
77int 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}
109EXPORT_SYMBOL_GPL(public_key_verify_signature);
110
111static 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 */
121struct 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};
129EXPORT_SYMBOL_GPL(public_key_subtype);
130