1 /*
2 * Copyright 2018-2022 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 else
63 ctx->provctx = provctx;
64 return ctx;
65 }
66
kdf_sshkdf_free(void * vctx)67 static void kdf_sshkdf_free(void *vctx)
68 {
69 KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
70
71 if (ctx != NULL) {
72 kdf_sshkdf_reset(ctx);
73 OPENSSL_free(ctx);
74 }
75 }
76
kdf_sshkdf_reset(void * vctx)77 static void kdf_sshkdf_reset(void *vctx)
78 {
79 KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
80 void *provctx = ctx->provctx;
81
82 ossl_prov_digest_reset(&ctx->digest);
83 OPENSSL_clear_free(ctx->key, ctx->key_len);
84 OPENSSL_clear_free(ctx->xcghash, ctx->xcghash_len);
85 OPENSSL_clear_free(ctx->session_id, ctx->session_id_len);
86 memset(ctx, 0, sizeof(*ctx));
87 ctx->provctx = provctx;
88 }
89
sshkdf_set_membuf(unsigned char ** dst,size_t * dst_len,const OSSL_PARAM * p)90 static int sshkdf_set_membuf(unsigned char **dst, size_t *dst_len,
91 const OSSL_PARAM *p)
92 {
93 OPENSSL_clear_free(*dst, *dst_len);
94 *dst = NULL;
95 *dst_len = 0;
96 return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
97 }
98
kdf_sshkdf_derive(void * vctx,unsigned char * key,size_t keylen,const OSSL_PARAM params[])99 static int kdf_sshkdf_derive(void *vctx, unsigned char *key, size_t keylen,
100 const OSSL_PARAM params[])
101 {
102 KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
103 const EVP_MD *md;
104
105 if (!ossl_prov_is_running() || !kdf_sshkdf_set_ctx_params(ctx, params))
106 return 0;
107
108 md = ossl_prov_digest_md(&ctx->digest);
109 if (md == NULL) {
110 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
111 return 0;
112 }
113 if (ctx->key == NULL) {
114 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
115 return 0;
116 }
117 if (ctx->xcghash == NULL) {
118 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_XCGHASH);
119 return 0;
120 }
121 if (ctx->session_id == NULL) {
122 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SESSION_ID);
123 return 0;
124 }
125 if (ctx->type == 0) {
126 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_TYPE);
127 return 0;
128 }
129 return SSHKDF(md, ctx->key, ctx->key_len,
130 ctx->xcghash, ctx->xcghash_len,
131 ctx->session_id, ctx->session_id_len,
132 ctx->type, key, keylen);
133 }
134
kdf_sshkdf_set_ctx_params(void * vctx,const OSSL_PARAM params[])135 static int kdf_sshkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
136 {
137 const OSSL_PARAM *p;
138 KDF_SSHKDF *ctx = vctx;
139 OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx);
140
141 if (params == NULL)
142 return 1;
143
144 if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
145 return 0;
146
147 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
148 if (!sshkdf_set_membuf(&ctx->key, &ctx->key_len, p))
149 return 0;
150
151 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_XCGHASH))
152 != NULL)
153 if (!sshkdf_set_membuf(&ctx->xcghash, &ctx->xcghash_len, p))
154 return 0;
155
156 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_SESSION_ID))
157 != NULL)
158 if (!sshkdf_set_membuf(&ctx->session_id, &ctx->session_id_len, p))
159 return 0;
160
161 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_TYPE))
162 != NULL) {
163 const char *kdftype;
164
165 if (!OSSL_PARAM_get_utf8_string_ptr(p, &kdftype))
166 return 0;
167 /* Expect one character (byte in this case) */
168 if (kdftype == NULL || p->data_size != 1)
169 return 0;
170 if (kdftype[0] < 65 || kdftype[0] > 70) {
171 ERR_raise(ERR_LIB_PROV, PROV_R_VALUE_ERROR);
172 return 0;
173 }
174 ctx->type = kdftype[0];
175 }
176 return 1;
177 }
178
kdf_sshkdf_settable_ctx_params(ossl_unused void * ctx,ossl_unused void * p_ctx)179 static const OSSL_PARAM *kdf_sshkdf_settable_ctx_params(ossl_unused void *ctx,
180 ossl_unused void *p_ctx)
181 {
182 static const OSSL_PARAM known_settable_ctx_params[] = {
183 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
184 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
185 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
186 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_XCGHASH, NULL, 0),
187 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_SESSION_ID, NULL, 0),
188 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_SSHKDF_TYPE, NULL, 0),
189 OSSL_PARAM_END
190 };
191 return known_settable_ctx_params;
192 }
193
kdf_sshkdf_get_ctx_params(void * vctx,OSSL_PARAM params[])194 static int kdf_sshkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
195 {
196 OSSL_PARAM *p;
197
198 if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
199 return OSSL_PARAM_set_size_t(p, SIZE_MAX);
200 return -2;
201 }
202
kdf_sshkdf_gettable_ctx_params(ossl_unused void * ctx,ossl_unused void * p_ctx)203 static const OSSL_PARAM *kdf_sshkdf_gettable_ctx_params(ossl_unused void *ctx,
204 ossl_unused void *p_ctx)
205 {
206 static const OSSL_PARAM known_gettable_ctx_params[] = {
207 OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
208 OSSL_PARAM_END
209 };
210 return known_gettable_ctx_params;
211 }
212
213 const OSSL_DISPATCH ossl_kdf_sshkdf_functions[] = {
214 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_sshkdf_new },
215 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_sshkdf_free },
216 { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_sshkdf_reset },
217 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_sshkdf_derive },
218 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
219 (void(*)(void))kdf_sshkdf_settable_ctx_params },
220 { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_set_ctx_params },
221 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
222 (void(*)(void))kdf_sshkdf_gettable_ctx_params },
223 { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_get_ctx_params },
224 { 0, NULL }
225 };
226
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)227 static int SSHKDF(const EVP_MD *evp_md,
228 const unsigned char *key, size_t key_len,
229 const unsigned char *xcghash, size_t xcghash_len,
230 const unsigned char *session_id, size_t session_id_len,
231 char type, unsigned char *okey, size_t okey_len)
232 {
233 EVP_MD_CTX *md = NULL;
234 unsigned char digest[EVP_MAX_MD_SIZE];
235 unsigned int dsize = 0;
236 size_t cursize = 0;
237 int ret = 0;
238
239 md = EVP_MD_CTX_new();
240 if (md == NULL)
241 return 0;
242
243 if (!EVP_DigestInit_ex(md, evp_md, NULL))
244 goto out;
245
246 if (!EVP_DigestUpdate(md, key, key_len))
247 goto out;
248
249 if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
250 goto out;
251
252 if (!EVP_DigestUpdate(md, &type, 1))
253 goto out;
254
255 if (!EVP_DigestUpdate(md, session_id, session_id_len))
256 goto out;
257
258 if (!EVP_DigestFinal_ex(md, digest, &dsize))
259 goto out;
260
261 if (okey_len < dsize) {
262 memcpy(okey, digest, okey_len);
263 ret = 1;
264 goto out;
265 }
266
267 memcpy(okey, digest, dsize);
268
269 for (cursize = dsize; cursize < okey_len; cursize += dsize) {
270
271 if (!EVP_DigestInit_ex(md, evp_md, NULL))
272 goto out;
273
274 if (!EVP_DigestUpdate(md, key, key_len))
275 goto out;
276
277 if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
278 goto out;
279
280 if (!EVP_DigestUpdate(md, okey, cursize))
281 goto out;
282
283 if (!EVP_DigestFinal_ex(md, digest, &dsize))
284 goto out;
285
286 if (okey_len < cursize + dsize) {
287 memcpy(okey + cursize, digest, okey_len - cursize);
288 ret = 1;
289 goto out;
290 }
291
292 memcpy(okey + cursize, digest, dsize);
293 }
294
295 ret = 1;
296
297 out:
298 EVP_MD_CTX_free(md);
299 OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE);
300 return ret;
301 }
302
303