1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (c) 2016, Intel Corporation
4 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
5 */
6 #include <linux/kernel.h>
7 #include <linux/export.h>
8 #include <linux/err.h>
9 #include <linux/string.h>
10 #include <crypto/ecdh.h>
11 #include <crypto/kpp.h>
12
13 #define ECDH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + sizeof(short))
14
15 static inline u8 *ecdh_pack_data(void *dst, const void *src, size_t sz)
16 {
17 memcpy(dst, src, sz);
18 return dst + sz;
19 }
20
21 static inline const u8 *ecdh_unpack_data(void *dst, const void *src, size_t sz)
22 {
23 memcpy(dst, src, sz);
24 return src + sz;
25 }
26
27 unsigned int crypto_ecdh_key_len(const struct ecdh *params)
28 {
29 return ECDH_KPP_SECRET_MIN_SIZE + params->key_size;
30 }
31 EXPORT_SYMBOL_GPL(crypto_ecdh_key_len);
32
33 int crypto_ecdh_encode_key(char *buf, unsigned int len,
34 const struct ecdh *params)
35 {
36 u8 *ptr = buf;
37 struct kpp_secret secret = {
38 .type = CRYPTO_KPP_SECRET_TYPE_ECDH,
39 .len = len
40 };
41
42 if (unlikely(!buf))
43 return -EINVAL;
44
45 if (len != crypto_ecdh_key_len(params))
46 return -EINVAL;
47
48 ptr = ecdh_pack_data(ptr, &secret, sizeof(secret));
49 ptr = ecdh_pack_data(ptr, ¶ms->key_size, sizeof(params->key_size));
50 ecdh_pack_data(ptr, params->key, params->key_size);
51
52 return 0;
53 }
54 EXPORT_SYMBOL_GPL(crypto_ecdh_encode_key);
55
56 int crypto_ecdh_decode_key(const char *buf, unsigned int len,
57 struct ecdh *params)
58 {
59 const u8 *ptr = buf;
60 struct kpp_secret secret;
61
62 if (unlikely(!buf || len < ECDH_KPP_SECRET_MIN_SIZE))
63 return -EINVAL;
64
65 ptr = ecdh_unpack_data(&secret, ptr, sizeof(secret));
66 if (secret.type != CRYPTO_KPP_SECRET_TYPE_ECDH)
67 return -EINVAL;
68
69 if (unlikely(len < secret.len))
70 return -EINVAL;
71
72 ptr = ecdh_unpack_data(¶ms->key_size, ptr, sizeof(params->key_size));
73 if (secret.len != crypto_ecdh_key_len(params))
74 return -EINVAL;
75
76 /* Don't allocate memory. Set pointer to data
77 * within the given buffer
78 */
79 params->key = (void *)ptr;
80
81 return 0;
82 }
83 EXPORT_SYMBOL_GPL(crypto_ecdh_decode_key);
84
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