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) + 2 * sizeof(short))
14
ecdh_pack_data(void * dst,const void * src,size_t sz)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
ecdh_unpack_data(void * dst,const void * src,size_t sz)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
crypto_ecdh_key_len(const struct ecdh * params)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
crypto_ecdh_encode_key(char * buf,unsigned int len,const struct ecdh * params)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->curve_id, sizeof(params->curve_id));
50 ptr = ecdh_pack_data(ptr, ¶ms->key_size, sizeof(params->key_size));
51 ecdh_pack_data(ptr, params->key, params->key_size);
52
53 return 0;
54 }
55 EXPORT_SYMBOL_GPL(crypto_ecdh_encode_key);
56
crypto_ecdh_decode_key(const char * buf,unsigned int len,struct ecdh * params)57 int crypto_ecdh_decode_key(const char *buf, unsigned int len,
58 struct ecdh *params)
59 {
60 const u8 *ptr = buf;
61 struct kpp_secret secret;
62
63 if (unlikely(!buf || len < ECDH_KPP_SECRET_MIN_SIZE))
64 return -EINVAL;
65
66 ptr = ecdh_unpack_data(&secret, ptr, sizeof(secret));
67 if (secret.type != CRYPTO_KPP_SECRET_TYPE_ECDH)
68 return -EINVAL;
69
70 ptr = ecdh_unpack_data(¶ms->curve_id, ptr, sizeof(params->curve_id));
71 ptr = ecdh_unpack_data(¶ms->key_size, ptr, sizeof(params->key_size));
72 if (secret.len != crypto_ecdh_key_len(params))
73 return -EINVAL;
74
75 /* Don't allocate memory. Set pointer to data
76 * within the given buffer
77 */
78 params->key = (void *)ptr;
79
80 return 0;
81 }
82 EXPORT_SYMBOL_GPL(crypto_ecdh_decode_key);
83