2 * Copyright (c) 2016, Intel Corporation
3 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
10 #include <linux/kernel.h>
11 #include <linux/export.h>
12 #include <linux/err.h>
13 #include <linux/string.h>
14 #include <crypto/dh.h>
15 #include <crypto/kpp.h>
17 #define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 3 * sizeof(int))
19 static inline u8 *dh_pack_data(void *dst, const void *src, size_t size)
21 memcpy(dst, src, size);
25 static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size)
27 memcpy(dst, src, size);
31 static inline unsigned int dh_data_size(const struct dh *p)
33 return p->key_size + p->p_size + p->q_size + p->g_size;
36 unsigned int crypto_dh_key_len(const struct dh *p)
38 return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p);
40 EXPORT_SYMBOL_GPL(crypto_dh_key_len);
42 int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params)
45 struct kpp_secret secret = {
46 .type = CRYPTO_KPP_SECRET_TYPE_DH,
53 if (len != crypto_dh_key_len(params))
56 ptr = dh_pack_data(ptr, &secret, sizeof(secret));
57 ptr = dh_pack_data(ptr, ¶ms->key_size, sizeof(params->key_size));
58 ptr = dh_pack_data(ptr, ¶ms->p_size, sizeof(params->p_size));
59 ptr = dh_pack_data(ptr, ¶ms->q_size, sizeof(params->q_size));
60 ptr = dh_pack_data(ptr, ¶ms->g_size, sizeof(params->g_size));
61 ptr = dh_pack_data(ptr, params->key, params->key_size);
62 ptr = dh_pack_data(ptr, params->p, params->p_size);
63 ptr = dh_pack_data(ptr, params->q, params->q_size);
64 dh_pack_data(ptr, params->g, params->g_size);
68 EXPORT_SYMBOL_GPL(crypto_dh_encode_key);
70 int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
73 struct kpp_secret secret;
75 if (unlikely(!buf || len < DH_KPP_SECRET_MIN_SIZE))
78 ptr = dh_unpack_data(&secret, ptr, sizeof(secret));
79 if (secret.type != CRYPTO_KPP_SECRET_TYPE_DH)
82 ptr = dh_unpack_data(¶ms->key_size, ptr, sizeof(params->key_size));
83 ptr = dh_unpack_data(¶ms->p_size, ptr, sizeof(params->p_size));
84 ptr = dh_unpack_data(¶ms->q_size, ptr, sizeof(params->q_size));
85 ptr = dh_unpack_data(¶ms->g_size, ptr, sizeof(params->g_size));
86 if (secret.len != crypto_dh_key_len(params))
90 * Don't permit the buffer for 'key' or 'g' to be larger than 'p', since
91 * some drivers assume otherwise.
93 if (params->key_size > params->p_size ||
94 params->g_size > params->p_size || params->q_size > params->p_size)
97 /* Don't allocate memory. Set pointers to data within
100 params->key = (void *)ptr;
101 params->p = (void *)(ptr + params->key_size);
102 params->q = (void *)(ptr + params->key_size + params->p_size);
103 params->g = (void *)(ptr + params->key_size + params->p_size +
107 * Don't permit 'p' to be 0. It's not a prime number, and it's subject
108 * to corner cases such as 'mod 0' being undefined or
109 * crypto_kpp_maxsize() returning 0.
111 if (memchr_inv(params->p, 0, params->p_size) == NULL)
114 /* It is permissible to not provide Q. */
115 if (params->q_size == 0)
120 EXPORT_SYMBOL_GPL(crypto_dh_decode_key);