1/*
2 * Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10#include <openssl/crypto.h>
11#include <openssl/core_numbers.h>
12#include <openssl/core_names.h>
13#include <openssl/dh.h>
14#include <openssl/params.h>
15#include "prov/implementations.h"
16
17static OSSL_OP_keyexch_newctx_fn dh_newctx;
18static OSSL_OP_keyexch_init_fn dh_init;
19static OSSL_OP_keyexch_set_peer_fn dh_set_peer;
20static OSSL_OP_keyexch_derive_fn dh_derive;
21static OSSL_OP_keyexch_freectx_fn dh_freectx;
22static OSSL_OP_keyexch_dupctx_fn dh_dupctx;
23static OSSL_OP_keyexch_set_ctx_params_fn dh_set_ctx_params;
24static OSSL_OP_keyexch_settable_ctx_params_fn dh_settable_ctx_params;
25
26/*
27 * What's passed as an actual key is defined by the KEYMGMT interface.
28 * We happen to know that our KEYMGMT simply passes DH structures, so
29 * we use that here too.
30 */
31
32typedef struct {
33 DH *dh;
34 DH *dhpeer;
35 unsigned int pad : 1;
36} PROV_DH_CTX;
37
38static void *dh_newctx(void *provctx)
39{
40 return OPENSSL_zalloc(sizeof(PROV_DH_CTX));
41}
42
43static int dh_init(void *vpdhctx, void *vdh)
44{
45 PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
46
47 if (pdhctx == NULL || vdh == NULL || !DH_up_ref(vdh))
48 return 0;
49 DH_free(pdhctx->dh);
50 pdhctx->dh = vdh;
51 return 1;
52}
53
54static int dh_set_peer(void *vpdhctx, void *vdh)
55{
56 PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
57
58 if (pdhctx == NULL || vdh == NULL || !DH_up_ref(vdh))
59 return 0;
60 DH_free(pdhctx->dhpeer);
61 pdhctx->dhpeer = vdh;
62 return 1;
63}
64
65static int dh_derive(void *vpdhctx, unsigned char *secret, size_t *secretlen,
66 size_t outlen)
67{
68 PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
69 int ret;
70 size_t dhsize;
71 const BIGNUM *pub_key = NULL;
72
73 /* TODO(3.0): Add errors to stack */
74 if (pdhctx->dh == NULL || pdhctx->dhpeer == NULL)
75 return 0;
76
77 dhsize = (size_t)DH_size(pdhctx->dh);
78 if (secret == NULL) {
79 *secretlen = dhsize;
80 return 1;
81 }
82 if (outlen < dhsize)
83 return 0;
84
85 DH_get0_key(pdhctx->dhpeer, &pub_key, NULL);
86 ret = (pdhctx->pad) ? DH_compute_key_padded(secret, pub_key, pdhctx->dh)
87 : DH_compute_key(secret, pub_key, pdhctx->dh);
88 if (ret <= 0)
89 return 0;
90
91 *secretlen = ret;
92 return 1;
93}
94
95static void dh_freectx(void *vpdhctx)
96{
97 PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
98
99 DH_free(pdhctx->dh);
100 DH_free(pdhctx->dhpeer);
101
102 OPENSSL_free(pdhctx);
103}
104
105static void *dh_dupctx(void *vpdhctx)
106{
107 PROV_DH_CTX *srcctx = (PROV_DH_CTX *)vpdhctx;
108 PROV_DH_CTX *dstctx;
109
110 dstctx = OPENSSL_zalloc(sizeof(*srcctx));
111 if (dstctx == NULL)
112 return NULL;
113
114 *dstctx = *srcctx;
115 if (dstctx->dh != NULL && !DH_up_ref(dstctx->dh)) {
116 OPENSSL_free(dstctx);
117 return NULL;
118 }
119
120 if (dstctx->dhpeer != NULL && !DH_up_ref(dstctx->dhpeer)) {
121 DH_free(dstctx->dh);
122 OPENSSL_free(dstctx);
123 return NULL;
124 }
125
126 return dstctx;
127}
128
129static int dh_set_ctx_params(void *vpdhctx, const OSSL_PARAM params[])
130{
131 PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
132 const OSSL_PARAM *p;
133 unsigned int pad;
134
135 if (pdhctx == NULL || params == NULL)
136 return 0;
137
138 p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_PAD);
139 if (p == NULL || !OSSL_PARAM_get_uint(p, &pad))
140 return 0;
141 pdhctx->pad = pad ? 1 : 0;
142 return 1;
143}
144
145static const OSSL_PARAM known_settable_ctx_params[] = {
146 OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_PAD, NULL),
147 OSSL_PARAM_END
148};
149
150static const OSSL_PARAM *dh_settable_ctx_params(void)
151{
152 return known_settable_ctx_params;
153}
154
155const OSSL_DISPATCH dh_keyexch_functions[] = {
156 { OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))dh_newctx },
157 { OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))dh_init },
158 { OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))dh_derive },
159 { OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))dh_set_peer },
160 { OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))dh_freectx },
161 { OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))dh_dupctx },
162 { OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))dh_set_ctx_params },
163 { OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
164 (void (*)(void))dh_settable_ctx_params },
165 { 0, NULL }
166};
167