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
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
|
/*
* ECDH helper functions - KPP wrappings
*
* Copyright (C) 2017 Intel Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation;
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
* IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) AND AUTHOR(S) BE LIABLE FOR ANY
* CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* ALL LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF ANY PATENTS,
* COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS, RELATING TO USE OF THIS
* SOFTWARE IS DISCLAIMED.
*/
#include "ecdh_helper.h"
#include <linux/scatterlist.h>
#include <crypto/ecdh.h>
struct ecdh_completion {
struct completion completion;
int err;
};
static void ecdh_complete(struct crypto_async_request *req, int err)
{
struct ecdh_completion *res = req->data;
if (err == -EINPROGRESS)
return;
res->err = err;
complete(&res->completion);
}
static inline void swap_digits(u64 *in, u64 *out, unsigned int ndigits)
{
int i;
for (i = 0; i < ndigits; i++)
out[i] = __swab64(in[ndigits - 1 - i]);
}
/* compute_ecdh_secret() - function assumes that the private key was
* already set.
* @tfm: KPP tfm handle allocated with crypto_alloc_kpp().
* @public_key: pair's ecc public key.
* secret: memory where the ecdh computed shared secret will be saved.
*
* Return: zero on success; error code in case of error.
*/
int compute_ecdh_secret(struct crypto_kpp *tfm, const u8 public_key[64],
u8 secret[32])
{
struct kpp_request *req;
u8 *tmp;
struct ecdh_completion result;
struct scatterlist src, dst;
int err;
tmp = kmalloc(64, GFP_KERNEL);
if (!tmp)
return -ENOMEM;
req = kpp_request_alloc(tfm, GFP_KERNEL);
if (!req) {
err = -ENOMEM;
goto free_tmp;
}
init_completion(&result.completion);
swap_digits((u64 *)public_key, (u64 *)tmp, 4); /* x */
swap_digits((u64 *)&public_key[32], (u64 *)&tmp[32], 4); /* y */
sg_init_one(&src, tmp, 64);
sg_init_one(&dst, secret, 32);
kpp_request_set_input(req, &src, 64);
kpp_request_set_output(req, &dst, 32);
kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
ecdh_complete, &result);
err = crypto_kpp_compute_shared_secret(req);
if (err == -EINPROGRESS) {
wait_for_completion(&result.completion);
err = result.err;
}
if (err < 0) {
pr_err("alg: ecdh: compute shared secret failed. err %d\n",
err);
goto free_all;
}
swap_digits((u64 *)secret, (u64 *)tmp, 4);
memcpy(secret, tmp, 32);
free_all:
kpp_request_free(req);
free_tmp:
kzfree(tmp);
return err;
}
/* set_ecdh_privkey() - set or generate ecc private key.
*
* Function generates an ecc private key in the crypto subsystem when receiving
* a NULL private key or sets the received key when not NULL.
*
* @tfm: KPP tfm handle allocated with crypto_alloc_kpp().
* @private_key: user's ecc private key. When not NULL, the key is expected
* in little endian format.
*
* Return: zero on success; error code in case of error.
*/
int set_ecdh_privkey(struct crypto_kpp *tfm, const u8 private_key[32])
{
u8 *buf, *tmp = NULL;
unsigned int buf_len;
int err;
struct ecdh p = {0};
p.curve_id = ECC_CURVE_NIST_P256;
if (private_key) {
tmp = kmalloc(32, GFP_KERNEL);
if (!tmp)
return -ENOMEM;
swap_digits((u64 *)private_key, (u64 *)tmp, 4);
p.key = tmp;
p.key_size = 32;
}
buf_len = crypto_ecdh_key_len(&p);
buf = kmalloc(buf_len, GFP_KERNEL);
if (!buf) {
err = -ENOMEM;
goto free_tmp;
}
err = crypto_ecdh_encode_key(buf, buf_len, &p);
if (err)
goto free_all;
err = crypto_kpp_set_secret(tfm, buf, buf_len);
/* fall through */
free_all:
kzfree(buf);
free_tmp:
kzfree(tmp);
return err;
}
/* generate_ecdh_public_key() - function assumes that the private key was
* already set.
*
* @tfm: KPP tfm handle allocated with crypto_alloc_kpp().
* @public_key: memory where the computed ecc public key will be saved.
*
* Return: zero on success; error code in case of error.
*/
int generate_ecdh_public_key(struct crypto_kpp *tfm, u8 public_key[64])
{
struct kpp_request *req;
u8 *tmp;
struct ecdh_completion result;
struct scatterlist dst;
int err;
tmp = kmalloc(64, GFP_KERNEL);
if (!tmp)
return -ENOMEM;
req = kpp_request_alloc(tfm, GFP_KERNEL);
if (!req) {
err = -ENOMEM;
goto free_tmp;
}
init_completion(&result.completion);
sg_init_one(&dst, tmp, 64);
kpp_request_set_input(req, NULL, 0);
kpp_request_set_output(req, &dst, 64);
kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
ecdh_complete, &result);
err = crypto_kpp_generate_public_key(req);
if (err == -EINPROGRESS) {
wait_for_completion(&result.completion);
err = result.err;
}
if (err < 0)
goto free_all;
/* The public key is handed back in little endian as expected by
* the Security Manager Protocol.
*/
swap_digits((u64 *)tmp, (u64 *)public_key, 4); /* x */
swap_digits((u64 *)&tmp[32], (u64 *)&public_key[32], 4); /* y */
free_all:
kpp_request_free(req);
free_tmp:
kfree(tmp);
return err;
}
/* generate_ecdh_keys() - generate ecc key pair.
*
* @tfm: KPP tfm handle allocated with crypto_alloc_kpp().
* @public_key: memory where the computed ecc public key will be saved.
*
* Return: zero on success; error code in case of error.
*/
int generate_ecdh_keys(struct crypto_kpp *tfm, u8 public_key[64])
{
int err;
err = set_ecdh_privkey(tfm, NULL);
if (err)
return err;
return generate_ecdh_public_key(tfm, public_key);
}
|
