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
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
|
// SPDX-License-Identifier: GPL-2.0-or-later
/* ECDH key-agreement protocol
*
* Copyright (c) 2016, Intel Corporation
* Authors: Salvator Benedetto <salvatore.benedetto@intel.com>
*/
#include <linux/module.h>
#include <crypto/internal/kpp.h>
#include <crypto/kpp.h>
#include <crypto/ecdh.h>
#include <linux/scatterlist.h>
#include "ecc.h"
struct ecdh_ctx {
unsigned int curve_id;
unsigned int ndigits;
u64 private_key[ECC_MAX_DIGITS];
};
static inline struct ecdh_ctx *ecdh_get_ctx(struct crypto_kpp *tfm)
{
return kpp_tfm_ctx(tfm);
}
static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
unsigned int len)
{
struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
struct ecdh params;
if (crypto_ecdh_decode_key(buf, len, ¶ms) < 0 ||
params.key_size > sizeof(u64) * ctx->ndigits)
return -EINVAL;
if (!params.key || !params.key_size)
return ecc_gen_privkey(ctx->curve_id, ctx->ndigits,
ctx->private_key);
memcpy(ctx->private_key, params.key, params.key_size);
if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits,
ctx->private_key, params.key_size) < 0) {
memzero_explicit(ctx->private_key, params.key_size);
return -EINVAL;
}
return 0;
}
static int ecdh_compute_value(struct kpp_request *req)
{
struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
u64 *public_key;
u64 *shared_secret = NULL;
void *buf;
size_t copied, nbytes, public_key_sz;
int ret = -ENOMEM;
nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
/* Public part is a point thus it has both coordinates */
public_key_sz = 2 * nbytes;
public_key = kmalloc(public_key_sz, GFP_KERNEL);
if (!public_key)
return -ENOMEM;
if (req->src) {
shared_secret = kmalloc(nbytes, GFP_KERNEL);
if (!shared_secret)
goto free_pubkey;
/* from here on it's invalid parameters */
ret = -EINVAL;
/* must have exactly two points to be on the curve */
if (public_key_sz != req->src_len)
goto free_all;
copied = sg_copy_to_buffer(req->src,
sg_nents_for_len(req->src,
public_key_sz),
public_key, public_key_sz);
if (copied != public_key_sz)
goto free_all;
ret = crypto_ecdh_shared_secret(ctx->curve_id, ctx->ndigits,
ctx->private_key, public_key,
shared_secret);
buf = shared_secret;
} else {
ret = ecc_make_pub_key(ctx->curve_id, ctx->ndigits,
ctx->private_key, public_key);
buf = public_key;
nbytes = public_key_sz;
}
if (ret < 0)
goto free_all;
/* might want less than we've got */
nbytes = min_t(size_t, nbytes, req->dst_len);
copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,
nbytes),
buf, nbytes);
if (copied != nbytes)
ret = -EINVAL;
/* fall through */
free_all:
kfree_sensitive(shared_secret);
free_pubkey:
kfree(public_key);
return ret;
}
static unsigned int ecdh_max_size(struct crypto_kpp *tfm)
{
struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
/* Public key is made of two coordinates, add one to the left shift */
return ctx->ndigits << (ECC_DIGITS_TO_BYTES_SHIFT + 1);
}
static int ecdh_nist_p192_init_tfm(struct crypto_kpp *tfm)
{
struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
ctx->curve_id = ECC_CURVE_NIST_P192;
ctx->ndigits = ECC_CURVE_NIST_P192_DIGITS;
return 0;
}
static struct kpp_alg ecdh_nist_p192 = {
.set_secret = ecdh_set_secret,
.generate_public_key = ecdh_compute_value,
.compute_shared_secret = ecdh_compute_value,
.max_size = ecdh_max_size,
.init = ecdh_nist_p192_init_tfm,
.base = {
.cra_name = "ecdh-nist-p192",
.cra_driver_name = "ecdh-nist-p192-generic",
.cra_priority = 100,
.cra_module = THIS_MODULE,
.cra_ctxsize = sizeof(struct ecdh_ctx),
},
};
static int ecdh_nist_p256_init_tfm(struct crypto_kpp *tfm)
{
struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
ctx->curve_id = ECC_CURVE_NIST_P256;
ctx->ndigits = ECC_CURVE_NIST_P256_DIGITS;
return 0;
}
static struct kpp_alg ecdh_nist_p256 = {
.set_secret = ecdh_set_secret,
.generate_public_key = ecdh_compute_value,
.compute_shared_secret = ecdh_compute_value,
.max_size = ecdh_max_size,
.init = ecdh_nist_p256_init_tfm,
.base = {
.cra_name = "ecdh-nist-p256",
.cra_driver_name = "ecdh-nist-p256-generic",
.cra_priority = 100,
.cra_module = THIS_MODULE,
.cra_ctxsize = sizeof(struct ecdh_ctx),
},
};
static bool ecdh_nist_p192_registered;
static int ecdh_init(void)
{
int ret;
/* NIST p192 will fail to register in FIPS mode */
ret = crypto_register_kpp(&ecdh_nist_p192);
ecdh_nist_p192_registered = ret == 0;
return crypto_register_kpp(&ecdh_nist_p256);
}
static void ecdh_exit(void)
{
if (ecdh_nist_p192_registered)
crypto_unregister_kpp(&ecdh_nist_p192);
crypto_unregister_kpp(&ecdh_nist_p256);
}
subsys_initcall(ecdh_init);
module_exit(ecdh_exit);
MODULE_ALIAS_CRYPTO("ecdh");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ECDH generic algorithm");
|
