1/*
2 * Copyright 2018-2019 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (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 <stdlib.h>
11#include <stdarg.h>
12#include <string.h>
13#include <openssl/evp.h>
14#include <openssl/kdf.h>
15#include <openssl/core_names.h>
16#include "internal/cryptlib.h"
17#include "internal/numbers.h"
18#include "crypto/evp.h"
19#include "prov/provider_ctx.h"
20#include "prov/providercommonerr.h"
21#include "prov/implementations.h"
22# include "prov/provider_util.h"
23
24/* See RFC 4253, Section 7.2 */
25static OSSL_OP_kdf_newctx_fn kdf_sshkdf_new;
26static OSSL_OP_kdf_freectx_fn kdf_sshkdf_free;
27static OSSL_OP_kdf_reset_fn kdf_sshkdf_reset;
28static OSSL_OP_kdf_derive_fn kdf_sshkdf_derive;
29static OSSL_OP_kdf_settable_ctx_params_fn kdf_sshkdf_settable_ctx_params;
30static OSSL_OP_kdf_set_ctx_params_fn kdf_sshkdf_set_ctx_params;
31static OSSL_OP_kdf_gettable_ctx_params_fn kdf_sshkdf_gettable_ctx_params;
32static OSSL_OP_kdf_get_ctx_params_fn kdf_sshkdf_get_ctx_params;
33
34static int SSHKDF(const EVP_MD *evp_md,
35 const unsigned char *key, size_t key_len,
36 const unsigned char *xcghash, size_t xcghash_len,
37 const unsigned char *session_id, size_t session_id_len,
38 char type, unsigned char *okey, size_t okey_len);
39
40typedef struct {
41 void *provctx;
42 PROV_DIGEST digest;
43 unsigned char *key; /* K */
44 size_t key_len;
45 unsigned char *xcghash; /* H */
46 size_t xcghash_len;
47 char type; /* X */
48 unsigned char *session_id;
49 size_t session_id_len;
50} KDF_SSHKDF;
51
52static void *kdf_sshkdf_new(void *provctx)
53{
54 KDF_SSHKDF *ctx;
55
56 if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
57 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
58 ctx->provctx = provctx;
59 return ctx;
60}
61
62static void kdf_sshkdf_free(void *vctx)
63{
64 KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
65
66 if (ctx != NULL) {
67 kdf_sshkdf_reset(ctx);
68 OPENSSL_free(ctx);
69 }
70}
71
72static void kdf_sshkdf_reset(void *vctx)
73{
74 KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
75
76 ossl_prov_digest_reset(&ctx->digest);
77 OPENSSL_clear_free(ctx->key, ctx->key_len);
78 OPENSSL_clear_free(ctx->xcghash, ctx->xcghash_len);
79 OPENSSL_clear_free(ctx->session_id, ctx->session_id_len);
80 memset(ctx, 0, sizeof(*ctx));
81}
82
83static int sshkdf_set_membuf(unsigned char **dst, size_t *dst_len,
84 const OSSL_PARAM *p)
85{
86 OPENSSL_clear_free(*dst, *dst_len);
87 *dst = NULL;
88 return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
89}
90
91static int kdf_sshkdf_derive(void *vctx, unsigned char *key,
92 size_t keylen)
93{
94 KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
95 const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
96
97 if (md == NULL) {
98 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
99 return 0;
100 }
101 if (ctx->key == NULL) {
102 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
103 return 0;
104 }
105 if (ctx->xcghash == NULL) {
106 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_XCGHASH);
107 return 0;
108 }
109 if (ctx->session_id == NULL) {
110 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SESSION_ID);
111 return 0;
112 }
113 if (ctx->type == 0) {
114 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_TYPE);
115 return 0;
116 }
117 return SSHKDF(md, ctx->key, ctx->key_len,
118 ctx->xcghash, ctx->xcghash_len,
119 ctx->session_id, ctx->session_id_len,
120 ctx->type, key, keylen);
121}
122
123static int kdf_sshkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
124{
125 const OSSL_PARAM *p;
126 KDF_SSHKDF *ctx = vctx;
127 OPENSSL_CTX *provctx = PROV_LIBRARY_CONTEXT_OF(ctx->provctx);
128 int t;
129
130 if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
131 return 0;
132
133 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
134 if (!sshkdf_set_membuf(&ctx->key, &ctx->key_len, p))
135 return 0;
136
137 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_XCGHASH))
138 != NULL)
139 if (!sshkdf_set_membuf(&ctx->xcghash, &ctx->xcghash_len, p))
140 return 0;
141
142 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_SESSION_ID))
143 != NULL)
144 if (!sshkdf_set_membuf(&ctx->session_id, &ctx->session_id_len, p))
145 return 0;
146
147 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_TYPE))
148 != NULL) {
149 if (p->data == NULL || p->data_size == 0)
150 return 0;
151 t = *(unsigned char *)p->data;
152 if (t < 65 || t > 70) {
153 ERR_raise(ERR_LIB_PROV, PROV_R_VALUE_ERROR);
154 return 0;
155 }
156 ctx->type = (char)t;
157 }
158 return 1;
159}
160
161static const OSSL_PARAM *kdf_sshkdf_settable_ctx_params(void)
162{
163 static const OSSL_PARAM known_settable_ctx_params[] = {
164 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
165 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
166 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
167 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_XCGHASH, NULL, 0),
168 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_SESSION_ID, NULL, 0),
169 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_SSHKDF_TYPE, NULL, 0),
170 OSSL_PARAM_END
171 };
172 return known_settable_ctx_params;
173}
174
175static int kdf_sshkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
176{
177 OSSL_PARAM *p;
178
179 if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
180 return OSSL_PARAM_set_size_t(p, SIZE_MAX);
181 return -2;
182}
183
184static const OSSL_PARAM *kdf_sshkdf_gettable_ctx_params(void)
185{
186 static const OSSL_PARAM known_gettable_ctx_params[] = {
187 OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
188 OSSL_PARAM_END
189 };
190 return known_gettable_ctx_params;
191}
192
193const OSSL_DISPATCH kdf_sshkdf_functions[] = {
194 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_sshkdf_new },
195 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_sshkdf_free },
196 { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_sshkdf_reset },
197 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_sshkdf_derive },
198 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
199 (void(*)(void))kdf_sshkdf_settable_ctx_params },
200 { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_set_ctx_params },
201 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
202 (void(*)(void))kdf_sshkdf_gettable_ctx_params },
203 { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_get_ctx_params },
204 { 0, NULL }
205};
206
207static int SSHKDF(const EVP_MD *evp_md,
208 const unsigned char *key, size_t key_len,
209 const unsigned char *xcghash, size_t xcghash_len,
210 const unsigned char *session_id, size_t session_id_len,
211 char type, unsigned char *okey, size_t okey_len)
212{
213 EVP_MD_CTX *md = NULL;
214 unsigned char digest[EVP_MAX_MD_SIZE];
215 unsigned int dsize = 0;
216 size_t cursize = 0;
217 int ret = 0;
218
219 md = EVP_MD_CTX_new();
220 if (md == NULL)
221 return 0;
222
223 if (!EVP_DigestInit_ex(md, evp_md, NULL))
224 goto out;
225
226 if (!EVP_DigestUpdate(md, key, key_len))
227 goto out;
228
229 if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
230 goto out;
231
232 if (!EVP_DigestUpdate(md, &type, 1))
233 goto out;
234
235 if (!EVP_DigestUpdate(md, session_id, session_id_len))
236 goto out;
237
238 if (!EVP_DigestFinal_ex(md, digest, &dsize))
239 goto out;
240
241 if (okey_len < dsize) {
242 memcpy(okey, digest, okey_len);
243 ret = 1;
244 goto out;
245 }
246
247 memcpy(okey, digest, dsize);
248
249 for (cursize = dsize; cursize < okey_len; cursize += dsize) {
250
251 if (!EVP_DigestInit_ex(md, evp_md, NULL))
252 goto out;
253
254 if (!EVP_DigestUpdate(md, key, key_len))
255 goto out;
256
257 if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
258 goto out;
259
260 if (!EVP_DigestUpdate(md, okey, cursize))
261 goto out;
262
263 if (!EVP_DigestFinal_ex(md, digest, &dsize))
264 goto out;
265
266 if (okey_len < cursize + dsize) {
267 memcpy(okey + cursize, digest, okey_len - cursize);
268 ret = 1;
269 goto out;
270 }
271
272 memcpy(okey + cursize, digest, dsize);
273 }
274
275 ret = 1;
276
277out:
278 EVP_MD_CTX_free(md);
279 OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE);
280 return ret;
281}
282
283