1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
|
/* In-software asymmetric public-key crypto subtype
*
* See Documentation/crypto/asymmetric-keys.txt
*
* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#define pr_fmt(fmt) "PKEY: "fmt
#include <linux/module.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/scatterlist.h>
#include <keys/asymmetric-subtype.h>
#include <crypto/public_key.h>
#include <crypto/akcipher.h>
MODULE_DESCRIPTION("In-software asymmetric public-key subtype");
MODULE_AUTHOR("Red Hat, Inc.");
MODULE_LICENSE("GPL");
/*
* Provide a part of a description of the key for /proc/keys.
*/
static void public_key_describe(const struct key *asymmetric_key,
struct seq_file *m)
{
struct public_key *key = asymmetric_key->payload.data[asym_crypto];
if (key)
seq_printf(m, "%s.%s", key->id_type, key->pkey_algo);
}
/*
* Destroy a public key algorithm key.
*/
void public_key_free(struct public_key *key)
{
if (key) {
kfree(key->key);
kfree(key);
}
}
EXPORT_SYMBOL_GPL(public_key_free);
/*
* Destroy a public key algorithm key.
*/
static void public_key_destroy(void *payload0, void *payload3)
{
public_key_free(payload0);
public_key_signature_free(payload3);
}
/*
* Verify a signature using a public key.
*/
int public_key_verify_signature(const struct public_key *pkey,
const struct public_key_signature *sig)
{
struct crypto_wait cwait;
struct crypto_akcipher *tfm;
struct akcipher_request *req;
struct scatterlist sig_sg, digest_sg;
const char *alg_name;
char alg_name_buf[CRYPTO_MAX_ALG_NAME];
void *output;
unsigned int outlen;
int ret;
pr_devel("==>%s()\n", __func__);
BUG_ON(!pkey);
BUG_ON(!sig);
BUG_ON(!sig->digest);
BUG_ON(!sig->s);
alg_name = sig->pkey_algo;
if (strcmp(sig->pkey_algo, "rsa") == 0) {
/* The data wangled by the RSA algorithm is typically padded
* and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447
* sec 8.2].
*/
if (snprintf(alg_name_buf, CRYPTO_MAX_ALG_NAME,
"pkcs1pad(rsa,%s)", sig->hash_algo
) >= CRYPTO_MAX_ALG_NAME)
return -EINVAL;
alg_name = alg_name_buf;
}
tfm = crypto_alloc_akcipher(alg_name, 0, 0);
if (IS_ERR(tfm))
return PTR_ERR(tfm);
ret = -ENOMEM;
req = akcipher_request_alloc(tfm, GFP_KERNEL);
if (!req)
goto error_free_tfm;
ret = crypto_akcipher_set_pub_key(tfm, pkey->key, pkey->keylen);
if (ret)
goto error_free_req;
ret = -ENOMEM;
outlen = crypto_akcipher_maxsize(tfm);
output = kmalloc(outlen, GFP_KERNEL);
if (!output)
goto error_free_req;
sg_init_one(&sig_sg, sig->s, sig->s_size);
sg_init_one(&digest_sg, output, outlen);
akcipher_request_set_crypt(req, &sig_sg, &digest_sg, sig->s_size,
outlen);
crypto_init_wait(&cwait);
akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
CRYPTO_TFM_REQ_MAY_SLEEP,
crypto_req_done, &cwait);
/* Perform the verification calculation. This doesn't actually do the
* verification, but rather calculates the hash expected by the
* signature and returns that to us.
*/
ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
if (ret)
goto out_free_output;
/* Do the actual verification step. */
if (req->dst_len != sig->digest_size ||
memcmp(sig->digest, output, sig->digest_size) != 0)
ret = -EKEYREJECTED;
out_free_output:
kfree(output);
error_free_req:
akcipher_request_free(req);
error_free_tfm:
crypto_free_akcipher(tfm);
pr_devel("<==%s() = %d\n", __func__, ret);
if (WARN_ON_ONCE(ret > 0))
ret = -EINVAL;
return ret;
}
EXPORT_SYMBOL_GPL(public_key_verify_signature);
static int public_key_verify_signature_2(const struct key *key,
const struct public_key_signature *sig)
{
const struct public_key *pk = key->payload.data[asym_crypto];
return public_key_verify_signature(pk, sig);
}
/*
* Public key algorithm asymmetric key subtype
*/
struct asymmetric_key_subtype public_key_subtype = {
.owner = THIS_MODULE,
.name = "public_key",
.name_len = sizeof("public_key") - 1,
.describe = public_key_describe,
.destroy = public_key_destroy,
.verify_signature = public_key_verify_signature_2,
};
EXPORT_SYMBOL_GPL(public_key_subtype);
|
