1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Copyright (c) 2016, Intel Corporation
4 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
6 #include <linux/kernel.h>
7 #include <linux/export.h>
9 #include <linux/string.h>
10 #include <crypto/dh.h>
11 #include <crypto/kpp.h>
12 #include "dhparameter.asn1.h"
14 #define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 4 * sizeof(int))
16 static inline u8 *dh_pack_data(u8 *dst, u8 *end, const void *src, size_t size)
18 if (!dst || size > end - dst)
20 memcpy(dst, src, size);
24 static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size)
26 memcpy(dst, src, size);
30 static inline unsigned int dh_data_size(const struct dh *p)
32 return p->key_size + p->p_size + p->q_size + p->g_size;
35 unsigned int crypto_dh_key_len(const struct dh *p)
37 return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p);
39 EXPORT_SYMBOL_GPL(crypto_dh_key_len);
41 int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params)
44 u8 * const end = ptr + len;
45 struct kpp_secret secret = {
46 .type = CRYPTO_KPP_SECRET_TYPE_DH,
53 /* Prevention of out-of-bounds access in decode code path */
54 if ((!params->key && params->key_size) ||
55 (!params->p && params->p_size) ||
56 (!params->g && params->g_size))
59 ptr = dh_pack_data(ptr, end, &secret, sizeof(secret));
60 ptr = dh_pack_data(ptr, end, ¶ms->key_size,
61 sizeof(params->key_size));
62 ptr = dh_pack_data(ptr, end, ¶ms->p_size, sizeof(params->p_size));
63 ptr = dh_pack_data(ptr, end, ¶ms->q_size, sizeof(params->q_size));
64 ptr = dh_pack_data(ptr, end, ¶ms->g_size, sizeof(params->g_size));
66 ptr = dh_pack_data(ptr, end, params->key, params->key_size);
68 ptr = dh_pack_data(ptr, end, params->p, params->p_size);
70 ptr = dh_pack_data(ptr, end, params->q, params->q_size);
72 ptr = dh_pack_data(ptr, end, params->g, params->g_size);
77 EXPORT_SYMBOL_GPL(crypto_dh_encode_key);
79 int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
82 struct kpp_secret secret;
84 if (unlikely(!buf || len < DH_KPP_SECRET_MIN_SIZE))
87 ptr = dh_unpack_data(&secret, ptr, sizeof(secret));
88 if (secret.type != CRYPTO_KPP_SECRET_TYPE_DH)
91 ptr = dh_unpack_data(¶ms->key_size, ptr, sizeof(params->key_size));
92 ptr = dh_unpack_data(¶ms->p_size, ptr, sizeof(params->p_size));
93 ptr = dh_unpack_data(¶ms->q_size, ptr, sizeof(params->q_size));
94 ptr = dh_unpack_data(¶ms->g_size, ptr, sizeof(params->g_size));
95 if (secret.len != crypto_dh_key_len(params))
99 * Don't permit the buffer for 'key' or 'g' to be larger than 'p', since
100 * some drivers assume otherwise.
102 if (params->key_size > params->p_size ||
103 params->g_size > params->p_size || params->q_size > params->p_size)
106 /* Don't allocate memory. Set pointers to data within
109 params->key = (void *)ptr;
110 params->p = (void *)(ptr + params->key_size);
111 params->q = (void *)(ptr + params->key_size + params->p_size);
112 params->g = (void *)(ptr + params->key_size + params->p_size +
116 * Don't permit 'p' to be 0. It's not a prime number, and it's subject
117 * to corner cases such as 'mod 0' being undefined or
118 * crypto_kpp_maxsize() returning 0.
120 if (memchr_inv(params->p, 0, params->p_size) == NULL)
123 /* It is permissible to not provide Q. */
124 if (params->q_size == 0)
129 EXPORT_SYMBOL_GPL(crypto_dh_decode_key);
131 int dh_get_p(void *context, size_t hdrlen, unsigned char tag, const void *value,
134 struct dh *dh = context;
136 /* invalid key provided */
146 int dh_get_g(void *context, size_t hdrlen, unsigned char tag,
147 const void *value, size_t vlen)
149 struct dh *dh = context;
151 /* invalid base provided */
152 if (!value || !dh->p_size || !vlen || vlen > dh->p_size)
161 int dh_parse_params_pkcs3(struct dh *dh, const void *param,
162 unsigned int param_len)
164 return asn1_ber_decoder(&dhparameter_decoder, dh, param, param_len);
166 EXPORT_SYMBOL_GPL(dh_parse_params_pkcs3);