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/dh.h>
11#include <crypto/kpp.h>
12
13#define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 3 * sizeof(int))
14
15static inline u8 *dh_pack_data(u8 *dst, u8 *end, const void *src, size_t size)
16{
17 if (!dst || size > end - dst)
18 return NULL;
19 memcpy(dst, src, size);
20 return dst + size;
21}
22
23static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size)
24{
25 memcpy(dst, src, size);
26 return src + size;
27}
28
29static inline unsigned int dh_data_size(const struct dh *p)
30{
31 return p->key_size + p->p_size + p->g_size;
32}
33
34unsigned int crypto_dh_key_len(const struct dh *p)
35{
36 return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p);
37}
38EXPORT_SYMBOL_GPL(crypto_dh_key_len);
39
40int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params)
41{
42 u8 *ptr = buf;
43 u8 * const end = ptr + len;
44 struct kpp_secret secret = {
45 .type = CRYPTO_KPP_SECRET_TYPE_DH,
46 .len = len
47 };
48
49 if (unlikely(!len))
50 return -EINVAL;
51
52 ptr = dh_pack_data(dst: ptr, end, src: &secret, size: sizeof(secret));
53 ptr = dh_pack_data(dst: ptr, end, src: &params->key_size,
54 size: sizeof(params->key_size));
55 ptr = dh_pack_data(dst: ptr, end, src: &params->p_size, size: sizeof(params->p_size));
56 ptr = dh_pack_data(dst: ptr, end, src: &params->g_size, size: sizeof(params->g_size));
57 ptr = dh_pack_data(dst: ptr, end, src: params->key, size: params->key_size);
58 ptr = dh_pack_data(dst: ptr, end, src: params->p, size: params->p_size);
59 ptr = dh_pack_data(dst: ptr, end, src: params->g, size: params->g_size);
60 if (ptr != end)
61 return -EINVAL;
62 return 0;
63}
64EXPORT_SYMBOL_GPL(crypto_dh_encode_key);
65
66int __crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
67{
68 const u8 *ptr = buf;
69 struct kpp_secret secret;
70
71 if (unlikely(!buf || len < DH_KPP_SECRET_MIN_SIZE))
72 return -EINVAL;
73
74 ptr = dh_unpack_data(dst: &secret, src: ptr, size: sizeof(secret));
75 if (secret.type != CRYPTO_KPP_SECRET_TYPE_DH)
76 return -EINVAL;
77
78 ptr = dh_unpack_data(dst: &params->key_size, src: ptr, size: sizeof(params->key_size));
79 ptr = dh_unpack_data(dst: &params->p_size, src: ptr, size: sizeof(params->p_size));
80 ptr = dh_unpack_data(dst: &params->g_size, src: ptr, size: sizeof(params->g_size));
81 if (secret.len != crypto_dh_key_len(params))
82 return -EINVAL;
83
84 /* Don't allocate memory. Set pointers to data within
85 * the given buffer
86 */
87 params->key = (void *)ptr;
88 params->p = (void *)(ptr + params->key_size);
89 params->g = (void *)(ptr + params->key_size + params->p_size);
90
91 return 0;
92}
93
94int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
95{
96 int err;
97
98 err = __crypto_dh_decode_key(buf, len, params);
99 if (err)
100 return err;
101
102 /*
103 * Don't permit the buffer for 'key' or 'g' to be larger than 'p', since
104 * some drivers assume otherwise.
105 */
106 if (params->key_size > params->p_size ||
107 params->g_size > params->p_size)
108 return -EINVAL;
109
110 /*
111 * Don't permit 'p' to be 0. It's not a prime number, and it's subject
112 * to corner cases such as 'mod 0' being undefined or
113 * crypto_kpp_maxsize() returning 0.
114 */
115 if (memchr_inv(p: params->p, c: 0, size: params->p_size) == NULL)
116 return -EINVAL;
117
118 return 0;
119}
120EXPORT_SYMBOL_GPL(crypto_dh_decode_key);
121

source code of linux/crypto/dh_helper.c