1 /*
2 * Copyright 2018-2021 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 <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 <openssl/proverr.h>
17 #include "internal/cryptlib.h"
18 #include "internal/numbers.h"
19 #include "crypto/evp.h"
20 #include "prov/provider_ctx.h"
21 #include "prov/providercommon.h"
22 #include "prov/implementations.h"
23 #include "prov/provider_util.h"
24
25 /* See RFC 4253, Section 7.2 */
26 static OSSL_FUNC_kdf_newctx_fn kdf_sshkdf_new;
27 static OSSL_FUNC_kdf_freectx_fn kdf_sshkdf_free;
28 static OSSL_FUNC_kdf_reset_fn kdf_sshkdf_reset;
29 static OSSL_FUNC_kdf_derive_fn kdf_sshkdf_derive;
30 static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_sshkdf_settable_ctx_params;
31 static OSSL_FUNC_kdf_set_ctx_params_fn kdf_sshkdf_set_ctx_params;
32 static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_sshkdf_gettable_ctx_params;
33 static OSSL_FUNC_kdf_get_ctx_params_fn kdf_sshkdf_get_ctx_params;
34
35 static int SSHKDF(const EVP_MD *evp_md,
36 const unsigned char *key, size_t key_len,
37 const unsigned char *xcghash, size_t xcghash_len,
38 const unsigned char *session_id, size_t session_id_len,
39 char type, unsigned char *okey, size_t okey_len);
40
41 typedef struct {
42 void *provctx;
43 PROV_DIGEST digest;
44 unsigned char *key; /* K */
45 size_t key_len;
46 unsigned char *xcghash; /* H */
47 size_t xcghash_len;
48 char type; /* X */
49 unsigned char *session_id;
50 size_t session_id_len;
51 } KDF_SSHKDF;
52
kdf_sshkdf_new(void * provctx)53 static void *kdf_sshkdf_new(void *provctx)
54 {
55 KDF_SSHKDF *ctx;
56
57 if (!ossl_prov_is_running())
58 return NULL;
59
60 if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
61 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
62 ctx->provctx = provctx;
63 return ctx;
64 }
65
kdf_sshkdf_free(void * vctx)66 static void kdf_sshkdf_free(void *vctx)
67 {
68 KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
69
70 if (ctx != NULL) {
71 kdf_sshkdf_reset(ctx);
72 OPENSSL_free(ctx);
73 }
74 }
75
kdf_sshkdf_reset(void * vctx)76 static void kdf_sshkdf_reset(void *vctx)
77 {
78 KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
79 void *provctx = ctx->provctx;
80
81 ossl_prov_digest_reset(&ctx->digest);
82 OPENSSL_clear_free(ctx->key, ctx->key_len);
83 OPENSSL_clear_free(ctx->xcghash, ctx->xcghash_len);
84 OPENSSL_clear_free(ctx->session_id, ctx->session_id_len);
85 memset(ctx, 0, sizeof(*ctx));
86 ctx->provctx = provctx;
87 }
88
sshkdf_set_membuf(unsigned char ** dst,size_t * dst_len,const OSSL_PARAM * p)89 static int sshkdf_set_membuf(unsigned char **dst, size_t *dst_len,
90 const OSSL_PARAM *p)
91 {
92 OPENSSL_clear_free(*dst, *dst_len);
93 *dst = NULL;
94 return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
95 }
96
kdf_sshkdf_derive(void * vctx,unsigned char * key,size_t keylen,const OSSL_PARAM params[])97 static int kdf_sshkdf_derive(void *vctx, unsigned char *key, size_t keylen,
98 const OSSL_PARAM params[])
99 {
100 KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
101 const EVP_MD *md;
102
103 if (!ossl_prov_is_running() || !kdf_sshkdf_set_ctx_params(ctx, params))
104 return 0;
105
106 md = ossl_prov_digest_md(&ctx->digest);
107 if (md == NULL) {
108 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
109 return 0;
110 }
111 if (ctx->key == NULL) {
112 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
113 return 0;
114 }
115 if (ctx->xcghash == NULL) {
116 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_XCGHASH);
117 return 0;
118 }
119 if (ctx->session_id == NULL) {
120 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SESSION_ID);
121 return 0;
122 }
123 if (ctx->type == 0) {
124 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_TYPE);
125 return 0;
126 }
127 return SSHKDF(md, ctx->key, ctx->key_len,
128 ctx->xcghash, ctx->xcghash_len,
129 ctx->session_id, ctx->session_id_len,
130 ctx->type, key, keylen);
131 }
132
kdf_sshkdf_set_ctx_params(void * vctx,const OSSL_PARAM params[])133 static int kdf_sshkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
134 {
135 const OSSL_PARAM *p;
136 KDF_SSHKDF *ctx = vctx;
137 OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx);
138
139 if (params == NULL)
140 return 1;
141
142 if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
143 return 0;
144
145 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
146 if (!sshkdf_set_membuf(&ctx->key, &ctx->key_len, p))
147 return 0;
148
149 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_XCGHASH))
150 != NULL)
151 if (!sshkdf_set_membuf(&ctx->xcghash, &ctx->xcghash_len, p))
152 return 0;
153
154 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_SESSION_ID))
155 != NULL)
156 if (!sshkdf_set_membuf(&ctx->session_id, &ctx->session_id_len, p))
157 return 0;
158
159 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_TYPE))
160 != NULL) {
161 const char *kdftype;
162
163 if (!OSSL_PARAM_get_utf8_string_ptr(p, &kdftype))
164 return 0;
165 /* Expect one character (byte in this case) */
166 if (kdftype == NULL || p->data_size != 1)
167 return 0;
168 if (kdftype[0] < 65 || kdftype[0] > 70) {
169 ERR_raise(ERR_LIB_PROV, PROV_R_VALUE_ERROR);
170 return 0;
171 }
172 ctx->type = kdftype[0];
173 }
174 return 1;
175 }
176
kdf_sshkdf_settable_ctx_params(ossl_unused void * ctx,ossl_unused void * p_ctx)177 static const OSSL_PARAM *kdf_sshkdf_settable_ctx_params(ossl_unused void *ctx,
178 ossl_unused void *p_ctx)
179 {
180 static const OSSL_PARAM known_settable_ctx_params[] = {
181 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
182 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
183 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
184 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_XCGHASH, NULL, 0),
185 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_SESSION_ID, NULL, 0),
186 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_SSHKDF_TYPE, NULL, 0),
187 OSSL_PARAM_END
188 };
189 return known_settable_ctx_params;
190 }
191
kdf_sshkdf_get_ctx_params(void * vctx,OSSL_PARAM params[])192 static int kdf_sshkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
193 {
194 OSSL_PARAM *p;
195
196 if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
197 return OSSL_PARAM_set_size_t(p, SIZE_MAX);
198 return -2;
199 }
200
kdf_sshkdf_gettable_ctx_params(ossl_unused void * ctx,ossl_unused void * p_ctx)201 static const OSSL_PARAM *kdf_sshkdf_gettable_ctx_params(ossl_unused void *ctx,
202 ossl_unused void *p_ctx)
203 {
204 static const OSSL_PARAM known_gettable_ctx_params[] = {
205 OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
206 OSSL_PARAM_END
207 };
208 return known_gettable_ctx_params;
209 }
210
211 const OSSL_DISPATCH ossl_kdf_sshkdf_functions[] = {
212 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_sshkdf_new },
213 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_sshkdf_free },
214 { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_sshkdf_reset },
215 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_sshkdf_derive },
216 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
217 (void(*)(void))kdf_sshkdf_settable_ctx_params },
218 { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_set_ctx_params },
219 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
220 (void(*)(void))kdf_sshkdf_gettable_ctx_params },
221 { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_get_ctx_params },
222 { 0, NULL }
223 };
224
SSHKDF(const EVP_MD * evp_md,const unsigned char * key,size_t key_len,const unsigned char * xcghash,size_t xcghash_len,const unsigned char * session_id,size_t session_id_len,char type,unsigned char * okey,size_t okey_len)225 static int SSHKDF(const EVP_MD *evp_md,
226 const unsigned char *key, size_t key_len,
227 const unsigned char *xcghash, size_t xcghash_len,
228 const unsigned char *session_id, size_t session_id_len,
229 char type, unsigned char *okey, size_t okey_len)
230 {
231 EVP_MD_CTX *md = NULL;
232 unsigned char digest[EVP_MAX_MD_SIZE];
233 unsigned int dsize = 0;
234 size_t cursize = 0;
235 int ret = 0;
236
237 md = EVP_MD_CTX_new();
238 if (md == NULL)
239 return 0;
240
241 if (!EVP_DigestInit_ex(md, evp_md, NULL))
242 goto out;
243
244 if (!EVP_DigestUpdate(md, key, key_len))
245 goto out;
246
247 if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
248 goto out;
249
250 if (!EVP_DigestUpdate(md, &type, 1))
251 goto out;
252
253 if (!EVP_DigestUpdate(md, session_id, session_id_len))
254 goto out;
255
256 if (!EVP_DigestFinal_ex(md, digest, &dsize))
257 goto out;
258
259 if (okey_len < dsize) {
260 memcpy(okey, digest, okey_len);
261 ret = 1;
262 goto out;
263 }
264
265 memcpy(okey, digest, dsize);
266
267 for (cursize = dsize; cursize < okey_len; cursize += dsize) {
268
269 if (!EVP_DigestInit_ex(md, evp_md, NULL))
270 goto out;
271
272 if (!EVP_DigestUpdate(md, key, key_len))
273 goto out;
274
275 if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
276 goto out;
277
278 if (!EVP_DigestUpdate(md, okey, cursize))
279 goto out;
280
281 if (!EVP_DigestFinal_ex(md, digest, &dsize))
282 goto out;
283
284 if (okey_len < cursize + dsize) {
285 memcpy(okey + cursize, digest, okey_len - cursize);
286 ret = 1;
287 goto out;
288 }
289
290 memcpy(okey + cursize, digest, dsize);
291 }
292
293 ret = 1;
294
295 out:
296 EVP_MD_CTX_free(md);
297 OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE);
298 return ret;
299 }
300
301