1 /*
2 * Copyright 2019-2022 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 /*
11 * DH low level APIs are deprecated for public use, but still ok for
12 * internal use.
13 */
14 #include "internal/deprecated.h"
15
16 #include <string.h>
17 #include <openssl/crypto.h>
18 #include <openssl/core_dispatch.h>
19 #include <openssl/core_names.h>
20 #include <openssl/dh.h>
21 #include <openssl/err.h>
22 #include <openssl/proverr.h>
23 #include <openssl/params.h>
24 #include "prov/providercommon.h"
25 #include "prov/implementations.h"
26 #include "prov/provider_ctx.h"
27 #include "prov/securitycheck.h"
28 #include "crypto/dh.h"
29
30 static OSSL_FUNC_keyexch_newctx_fn dh_newctx;
31 static OSSL_FUNC_keyexch_init_fn dh_init;
32 static OSSL_FUNC_keyexch_set_peer_fn dh_set_peer;
33 static OSSL_FUNC_keyexch_derive_fn dh_derive;
34 static OSSL_FUNC_keyexch_freectx_fn dh_freectx;
35 static OSSL_FUNC_keyexch_dupctx_fn dh_dupctx;
36 static OSSL_FUNC_keyexch_set_ctx_params_fn dh_set_ctx_params;
37 static OSSL_FUNC_keyexch_settable_ctx_params_fn dh_settable_ctx_params;
38 static OSSL_FUNC_keyexch_get_ctx_params_fn dh_get_ctx_params;
39 static OSSL_FUNC_keyexch_gettable_ctx_params_fn dh_gettable_ctx_params;
40
41 /*
42 * This type is only really used to handle some legacy related functionality.
43 * If you need to use other KDF's (such as SSKDF) just use PROV_DH_KDF_NONE
44 * here and then create and run a KDF after the key is derived.
45 * Note that X942 has 2 variants of key derivation:
46 * (1) DH_KDF_X9_42_ASN1 - which contains an ANS1 encoded object that has
47 * the counter embedded in it.
48 * (2) DH_KDF_X941_CONCAT - which is the same as ECDH_X963_KDF (which can be
49 * done by creating a "X963KDF".
50 */
51 enum kdf_type {
52 PROV_DH_KDF_NONE = 0,
53 PROV_DH_KDF_X9_42_ASN1
54 };
55
56 /*
57 * What's passed as an actual key is defined by the KEYMGMT interface.
58 * We happen to know that our KEYMGMT simply passes DH structures, so
59 * we use that here too.
60 */
61
62 typedef struct {
63 OSSL_LIB_CTX *libctx;
64 DH *dh;
65 DH *dhpeer;
66 unsigned int pad : 1;
67
68 /* DH KDF */
69 /* KDF (if any) to use for DH */
70 enum kdf_type kdf_type;
71 /* Message digest to use for key derivation */
72 EVP_MD *kdf_md;
73 /* User key material */
74 unsigned char *kdf_ukm;
75 size_t kdf_ukmlen;
76 /* KDF output length */
77 size_t kdf_outlen;
78 char *kdf_cekalg;
79 } PROV_DH_CTX;
80
dh_newctx(void * provctx)81 static void *dh_newctx(void *provctx)
82 {
83 PROV_DH_CTX *pdhctx;
84
85 if (!ossl_prov_is_running())
86 return NULL;
87
88 pdhctx = OPENSSL_zalloc(sizeof(PROV_DH_CTX));
89 if (pdhctx == NULL)
90 return NULL;
91 pdhctx->libctx = PROV_LIBCTX_OF(provctx);
92 pdhctx->kdf_type = PROV_DH_KDF_NONE;
93 return pdhctx;
94 }
95
dh_init(void * vpdhctx,void * vdh,const OSSL_PARAM params[])96 static int dh_init(void *vpdhctx, void *vdh, const OSSL_PARAM params[])
97 {
98 PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
99
100 if (!ossl_prov_is_running()
101 || pdhctx == NULL
102 || vdh == NULL
103 || !DH_up_ref(vdh))
104 return 0;
105 DH_free(pdhctx->dh);
106 pdhctx->dh = vdh;
107 pdhctx->kdf_type = PROV_DH_KDF_NONE;
108 return dh_set_ctx_params(pdhctx, params)
109 && ossl_dh_check_key(pdhctx->libctx, vdh);
110 }
111
112 /* The 2 parties must share the same domain parameters */
dh_match_params(DH * priv,DH * peer)113 static int dh_match_params(DH *priv, DH *peer)
114 {
115 int ret;
116 FFC_PARAMS *dhparams_priv = ossl_dh_get0_params(priv);
117 FFC_PARAMS *dhparams_peer = ossl_dh_get0_params(peer);
118
119 ret = dhparams_priv != NULL
120 && dhparams_peer != NULL
121 && ossl_ffc_params_cmp(dhparams_priv, dhparams_peer, 1);
122 if (!ret)
123 ERR_raise(ERR_LIB_PROV, PROV_R_MISMATCHING_DOMAIN_PARAMETERS);
124 return ret;
125 }
126
dh_set_peer(void * vpdhctx,void * vdh)127 static int dh_set_peer(void *vpdhctx, void *vdh)
128 {
129 PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
130
131 if (!ossl_prov_is_running()
132 || pdhctx == NULL
133 || vdh == NULL
134 || !dh_match_params(vdh, pdhctx->dh)
135 || !DH_up_ref(vdh))
136 return 0;
137 DH_free(pdhctx->dhpeer);
138 pdhctx->dhpeer = vdh;
139 return 1;
140 }
141
dh_plain_derive(void * vpdhctx,unsigned char * secret,size_t * secretlen,size_t outlen,unsigned int pad)142 static int dh_plain_derive(void *vpdhctx,
143 unsigned char *secret, size_t *secretlen,
144 size_t outlen, unsigned int pad)
145 {
146 PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
147 int ret;
148 size_t dhsize;
149 const BIGNUM *pub_key = NULL;
150
151 if (pdhctx->dh == NULL || pdhctx->dhpeer == NULL) {
152 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
153 return 0;
154 }
155
156 dhsize = (size_t)DH_size(pdhctx->dh);
157 if (secret == NULL) {
158 *secretlen = dhsize;
159 return 1;
160 }
161 if (outlen < dhsize) {
162 ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
163 return 0;
164 }
165
166 DH_get0_key(pdhctx->dhpeer, &pub_key, NULL);
167 if (pad)
168 ret = DH_compute_key_padded(secret, pub_key, pdhctx->dh);
169 else
170 ret = DH_compute_key(secret, pub_key, pdhctx->dh);
171 if (ret <= 0)
172 return 0;
173
174 *secretlen = ret;
175 return 1;
176 }
177
dh_X9_42_kdf_derive(void * vpdhctx,unsigned char * secret,size_t * secretlen,size_t outlen)178 static int dh_X9_42_kdf_derive(void *vpdhctx, unsigned char *secret,
179 size_t *secretlen, size_t outlen)
180 {
181 PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
182 unsigned char *stmp = NULL;
183 size_t stmplen;
184 int ret = 0;
185
186 if (secret == NULL) {
187 *secretlen = pdhctx->kdf_outlen;
188 return 1;
189 }
190
191 if (pdhctx->kdf_outlen > outlen) {
192 ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
193 return 0;
194 }
195 if (!dh_plain_derive(pdhctx, NULL, &stmplen, 0, 1))
196 return 0;
197 if ((stmp = OPENSSL_secure_malloc(stmplen)) == NULL) {
198 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
199 return 0;
200 }
201 if (!dh_plain_derive(pdhctx, stmp, &stmplen, stmplen, 1))
202 goto err;
203
204 /* Do KDF stuff */
205 if (pdhctx->kdf_type == PROV_DH_KDF_X9_42_ASN1) {
206 if (!ossl_dh_kdf_X9_42_asn1(secret, pdhctx->kdf_outlen,
207 stmp, stmplen,
208 pdhctx->kdf_cekalg,
209 pdhctx->kdf_ukm,
210 pdhctx->kdf_ukmlen,
211 pdhctx->kdf_md,
212 pdhctx->libctx, NULL))
213 goto err;
214 }
215 *secretlen = pdhctx->kdf_outlen;
216 ret = 1;
217 err:
218 OPENSSL_secure_clear_free(stmp, stmplen);
219 return ret;
220 }
221
dh_derive(void * vpdhctx,unsigned char * secret,size_t * psecretlen,size_t outlen)222 static int dh_derive(void *vpdhctx, unsigned char *secret,
223 size_t *psecretlen, size_t outlen)
224 {
225 PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
226
227 if (!ossl_prov_is_running())
228 return 0;
229
230 switch (pdhctx->kdf_type) {
231 case PROV_DH_KDF_NONE:
232 return dh_plain_derive(pdhctx, secret, psecretlen, outlen,
233 pdhctx->pad);
234 case PROV_DH_KDF_X9_42_ASN1:
235 return dh_X9_42_kdf_derive(pdhctx, secret, psecretlen, outlen);
236 default:
237 break;
238 }
239 return 0;
240 }
241
dh_freectx(void * vpdhctx)242 static void dh_freectx(void *vpdhctx)
243 {
244 PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
245
246 OPENSSL_free(pdhctx->kdf_cekalg);
247 DH_free(pdhctx->dh);
248 DH_free(pdhctx->dhpeer);
249 EVP_MD_free(pdhctx->kdf_md);
250 OPENSSL_clear_free(pdhctx->kdf_ukm, pdhctx->kdf_ukmlen);
251
252 OPENSSL_free(pdhctx);
253 }
254
dh_dupctx(void * vpdhctx)255 static void *dh_dupctx(void *vpdhctx)
256 {
257 PROV_DH_CTX *srcctx = (PROV_DH_CTX *)vpdhctx;
258 PROV_DH_CTX *dstctx;
259
260 if (!ossl_prov_is_running())
261 return NULL;
262
263 dstctx = OPENSSL_zalloc(sizeof(*srcctx));
264 if (dstctx == NULL)
265 return NULL;
266
267 *dstctx = *srcctx;
268 dstctx->dh = NULL;
269 dstctx->dhpeer = NULL;
270 dstctx->kdf_md = NULL;
271 dstctx->kdf_ukm = NULL;
272 dstctx->kdf_cekalg = NULL;
273
274 if (srcctx->dh != NULL && !DH_up_ref(srcctx->dh))
275 goto err;
276 else
277 dstctx->dh = srcctx->dh;
278
279 if (srcctx->dhpeer != NULL && !DH_up_ref(srcctx->dhpeer))
280 goto err;
281 else
282 dstctx->dhpeer = srcctx->dhpeer;
283
284 if (srcctx->kdf_md != NULL && !EVP_MD_up_ref(srcctx->kdf_md))
285 goto err;
286 else
287 dstctx->kdf_md = srcctx->kdf_md;
288
289 /* Duplicate UKM data if present */
290 if (srcctx->kdf_ukm != NULL && srcctx->kdf_ukmlen > 0) {
291 dstctx->kdf_ukm = OPENSSL_memdup(srcctx->kdf_ukm,
292 srcctx->kdf_ukmlen);
293 if (dstctx->kdf_ukm == NULL)
294 goto err;
295 }
296
297 if (srcctx->kdf_cekalg != NULL) {
298 dstctx->kdf_cekalg = OPENSSL_strdup(srcctx->kdf_cekalg);
299 if (dstctx->kdf_cekalg == NULL)
300 goto err;
301 }
302
303 return dstctx;
304 err:
305 dh_freectx(dstctx);
306 return NULL;
307 }
308
dh_set_ctx_params(void * vpdhctx,const OSSL_PARAM params[])309 static int dh_set_ctx_params(void *vpdhctx, const OSSL_PARAM params[])
310 {
311 PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
312 const OSSL_PARAM *p;
313 unsigned int pad;
314 char name[80] = { '\0' }; /* should be big enough */
315 char *str = NULL;
316
317 if (pdhctx == NULL)
318 return 0;
319 if (params == NULL)
320 return 1;
321
322 p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
323 if (p != NULL) {
324 str = name;
325 if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
326 return 0;
327
328 if (name[0] == '\0')
329 pdhctx->kdf_type = PROV_DH_KDF_NONE;
330 else if (strcmp(name, OSSL_KDF_NAME_X942KDF_ASN1) == 0)
331 pdhctx->kdf_type = PROV_DH_KDF_X9_42_ASN1;
332 else
333 return 0;
334 }
335 p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
336 if (p != NULL) {
337 char mdprops[80] = { '\0' }; /* should be big enough */
338
339 str = name;
340 if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
341 return 0;
342
343 str = mdprops;
344 p = OSSL_PARAM_locate_const(params,
345 OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS);
346
347 if (p != NULL) {
348 if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(mdprops)))
349 return 0;
350 }
351
352 EVP_MD_free(pdhctx->kdf_md);
353 pdhctx->kdf_md = EVP_MD_fetch(pdhctx->libctx, name, mdprops);
354 if (!ossl_digest_is_allowed(pdhctx->libctx, pdhctx->kdf_md)) {
355 EVP_MD_free(pdhctx->kdf_md);
356 pdhctx->kdf_md = NULL;
357 }
358 if (pdhctx->kdf_md == NULL)
359 return 0;
360 }
361
362 p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
363 if (p != NULL) {
364 size_t outlen;
365
366 if (!OSSL_PARAM_get_size_t(p, &outlen))
367 return 0;
368 pdhctx->kdf_outlen = outlen;
369 }
370
371 p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
372 if (p != NULL) {
373 void *tmp_ukm = NULL;
374 size_t tmp_ukmlen;
375
376 OPENSSL_free(pdhctx->kdf_ukm);
377 pdhctx->kdf_ukm = NULL;
378 pdhctx->kdf_ukmlen = 0;
379 /* ukm is an optional field so it can be NULL */
380 if (p->data != NULL && p->data_size != 0) {
381 if (!OSSL_PARAM_get_octet_string(p, &tmp_ukm, 0, &tmp_ukmlen))
382 return 0;
383 pdhctx->kdf_ukm = tmp_ukm;
384 pdhctx->kdf_ukmlen = tmp_ukmlen;
385 }
386 }
387
388 p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_PAD);
389 if (p != NULL) {
390 if (!OSSL_PARAM_get_uint(p, &pad))
391 return 0;
392 pdhctx->pad = pad ? 1 : 0;
393 }
394
395 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_CEK_ALG);
396 if (p != NULL) {
397 str = name;
398
399 OPENSSL_free(pdhctx->kdf_cekalg);
400 pdhctx->kdf_cekalg = NULL;
401 if (p->data != NULL && p->data_size != 0) {
402 if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
403 return 0;
404 pdhctx->kdf_cekalg = OPENSSL_strdup(name);
405 if (pdhctx->kdf_cekalg == NULL)
406 return 0;
407 }
408 }
409 return 1;
410 }
411
412 static const OSSL_PARAM known_settable_ctx_params[] = {
413 OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_PAD, NULL),
414 OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
415 OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
416 OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS, NULL, 0),
417 OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
418 OSSL_PARAM_octet_string(OSSL_EXCHANGE_PARAM_KDF_UKM, NULL, 0),
419 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
420 OSSL_PARAM_END
421 };
422
dh_settable_ctx_params(ossl_unused void * vpdhctx,ossl_unused void * provctx)423 static const OSSL_PARAM *dh_settable_ctx_params(ossl_unused void *vpdhctx,
424 ossl_unused void *provctx)
425 {
426 return known_settable_ctx_params;
427 }
428
429 static const OSSL_PARAM known_gettable_ctx_params[] = {
430 OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
431 OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
432 OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
433 OSSL_PARAM_DEFN(OSSL_EXCHANGE_PARAM_KDF_UKM, OSSL_PARAM_OCTET_PTR,
434 NULL, 0),
435 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
436 OSSL_PARAM_END
437 };
438
dh_gettable_ctx_params(ossl_unused void * vpdhctx,ossl_unused void * provctx)439 static const OSSL_PARAM *dh_gettable_ctx_params(ossl_unused void *vpdhctx,
440 ossl_unused void *provctx)
441 {
442 return known_gettable_ctx_params;
443 }
444
dh_get_ctx_params(void * vpdhctx,OSSL_PARAM params[])445 static int dh_get_ctx_params(void *vpdhctx, OSSL_PARAM params[])
446 {
447 PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
448 OSSL_PARAM *p;
449
450 if (pdhctx == NULL)
451 return 0;
452
453 p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
454 if (p != NULL) {
455 const char *kdf_type = NULL;
456
457 switch (pdhctx->kdf_type) {
458 case PROV_DH_KDF_NONE:
459 kdf_type = "";
460 break;
461 case PROV_DH_KDF_X9_42_ASN1:
462 kdf_type = OSSL_KDF_NAME_X942KDF_ASN1;
463 break;
464 default:
465 return 0;
466 }
467
468 if (!OSSL_PARAM_set_utf8_string(p, kdf_type))
469 return 0;
470 }
471
472 p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
473 if (p != NULL
474 && !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_md == NULL
475 ? ""
476 : EVP_MD_get0_name(pdhctx->kdf_md))){
477 return 0;
478 }
479
480 p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
481 if (p != NULL && !OSSL_PARAM_set_size_t(p, pdhctx->kdf_outlen))
482 return 0;
483
484 p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
485 if (p != NULL
486 && !OSSL_PARAM_set_octet_ptr(p, pdhctx->kdf_ukm, pdhctx->kdf_ukmlen))
487 return 0;
488
489 p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_CEK_ALG);
490 if (p != NULL
491 && !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_cekalg == NULL
492 ? "" : pdhctx->kdf_cekalg))
493 return 0;
494
495 return 1;
496 }
497
498 const OSSL_DISPATCH ossl_dh_keyexch_functions[] = {
499 { OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))dh_newctx },
500 { OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))dh_init },
501 { OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))dh_derive },
502 { OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))dh_set_peer },
503 { OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))dh_freectx },
504 { OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))dh_dupctx },
505 { OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))dh_set_ctx_params },
506 { OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
507 (void (*)(void))dh_settable_ctx_params },
508 { OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS, (void (*)(void))dh_get_ctx_params },
509 { OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS,
510 (void (*)(void))dh_gettable_ctx_params },
511 { 0, NULL }
512 };
513