blob: 24fdb2ecaa85dd9ad20d223898e94503f4307c3c [file] [log] [blame]
Salvatore Benedetto802c7f12016-06-22 17:49:14 +01001/*
2 * Copyright (c) 2016, Intel Corporation
3 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
4 *
5 * This program is free software; you can redistribute it and/or
Tudor-Dan Ambarusc0ca1212017-05-25 10:18:03 +03006 * modify it under the terms of the GNU General Public License
Salvatore Benedetto802c7f12016-06-22 17:49:14 +01007 * as published by the Free Software Foundation; either version
Tudor-Dan Ambarusc0ca1212017-05-25 10:18:03 +03008 * 2 of the License, or (at your option) any later version.
Salvatore Benedetto802c7f12016-06-22 17:49:14 +01009 */
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>
16
17#define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 3 * sizeof(int))
18
19static inline u8 *dh_pack_data(void *dst, const void *src, size_t size)
20{
21 memcpy(dst, src, size);
22 return dst + size;
23}
24
25static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size)
26{
27 memcpy(dst, src, size);
28 return src + size;
29}
30
Tudor-Dan Ambaruscb195b32017-09-29 12:21:04 +030031static inline unsigned int dh_data_size(const struct dh *p)
Salvatore Benedetto802c7f12016-06-22 17:49:14 +010032{
33 return p->key_size + p->p_size + p->g_size;
34}
35
Tudor-Dan Ambarus5b3f3a82017-09-29 12:21:05 +030036unsigned int crypto_dh_key_len(const struct dh *p)
Salvatore Benedetto802c7f12016-06-22 17:49:14 +010037{
38 return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p);
39}
40EXPORT_SYMBOL_GPL(crypto_dh_key_len);
41
42int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params)
43{
44 u8 *ptr = buf;
45 struct kpp_secret secret = {
46 .type = CRYPTO_KPP_SECRET_TYPE_DH,
47 .len = len
48 };
49
50 if (unlikely(!buf))
51 return -EINVAL;
52
53 if (len != crypto_dh_key_len(params))
54 return -EINVAL;
55
56 ptr = dh_pack_data(ptr, &secret, sizeof(secret));
57 ptr = dh_pack_data(ptr, &params->key_size, sizeof(params->key_size));
58 ptr = dh_pack_data(ptr, &params->p_size, sizeof(params->p_size));
59 ptr = dh_pack_data(ptr, &params->g_size, sizeof(params->g_size));
60 ptr = dh_pack_data(ptr, params->key, params->key_size);
61 ptr = dh_pack_data(ptr, params->p, params->p_size);
62 dh_pack_data(ptr, params->g, params->g_size);
63
64 return 0;
65}
66EXPORT_SYMBOL_GPL(crypto_dh_encode_key);
67
68int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
69{
70 const u8 *ptr = buf;
71 struct kpp_secret secret;
72
73 if (unlikely(!buf || len < DH_KPP_SECRET_MIN_SIZE))
74 return -EINVAL;
75
76 ptr = dh_unpack_data(&secret, ptr, sizeof(secret));
77 if (secret.type != CRYPTO_KPP_SECRET_TYPE_DH)
78 return -EINVAL;
79
80 ptr = dh_unpack_data(&params->key_size, ptr, sizeof(params->key_size));
81 ptr = dh_unpack_data(&params->p_size, ptr, sizeof(params->p_size));
82 ptr = dh_unpack_data(&params->g_size, ptr, sizeof(params->g_size));
83 if (secret.len != crypto_dh_key_len(params))
84 return -EINVAL;
85
Eric Biggersccd98882017-11-05 18:30:46 -080086 /*
87 * Don't permit the buffer for 'key' or 'g' to be larger than 'p', since
88 * some drivers assume otherwise.
89 */
90 if (params->key_size > params->p_size ||
91 params->g_size > params->p_size)
92 return -EINVAL;
93
Salvatore Benedetto802c7f12016-06-22 17:49:14 +010094 /* Don't allocate memory. Set pointers to data within
95 * the given buffer
96 */
97 params->key = (void *)ptr;
98 params->p = (void *)(ptr + params->key_size);
99 params->g = (void *)(ptr + params->key_size + params->p_size);
100
Eric Biggers199512b2017-11-05 18:30:45 -0800101 /*
102 * Don't permit 'p' to be 0. It's not a prime number, and it's subject
103 * to corner cases such as 'mod 0' being undefined or
104 * crypto_kpp_maxsize() returning 0.
105 */
106 if (memchr_inv(params->p, 0, params->p_size) == NULL)
107 return -EINVAL;
108
Salvatore Benedetto802c7f12016-06-22 17:49:14 +0100109 return 0;
110}
111EXPORT_SYMBOL_GPL(crypto_dh_decode_key);