providers/implementations/exchange/dh_exch.c

   1 /*
   2  * Copyright 2019-2021 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 /*
  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/params.h>
  23 #include "prov/providercommon.h"
  24 #include "prov/implementations.h"
  25 #include "prov/provider_ctx.h"
  26 #include "prov/securitycheck.h"
  27 #include "crypto/dh.h"
  28
  29 static OSSL_FUNC_keyexch_newctx_fn dh_newctx;
  30 static OSSL_FUNC_keyexch_init_fn dh_init;
  31 static OSSL_FUNC_keyexch_set_peer_fn dh_set_peer;
  32 static OSSL_FUNC_keyexch_derive_fn dh_derive;
  33 static OSSL_FUNC_keyexch_freectx_fn dh_freectx;
  34 static OSSL_FUNC_keyexch_dupctx_fn dh_dupctx;
  35 static OSSL_FUNC_keyexch_set_ctx_params_fn dh_set_ctx_params;
  36 static OSSL_FUNC_keyexch_settable_ctx_params_fn dh_settable_ctx_params;
  37 static OSSL_FUNC_keyexch_get_ctx_params_fn dh_get_ctx_params;
  38 static OSSL_FUNC_keyexch_gettable_ctx_params_fn dh_gettable_ctx_params;
  39
  40 /*
  41  * This type is only really used to handle some legacy related functionality.
  42  * If you need to use other KDF's (such as SSKDF) just use PROV_DH_KDF_NONE
  43  * here and then create and run a KDF after the key is derived.
  44  * Note that X942 has 2 variants of key derivation:
  45  *   (1) DH_KDF_X9_42_ASN1 - which contains an ANS1 encoded object that has
  46  *   the counter embedded in it.
  47  *   (2) DH_KDF_X941_CONCAT - which is the same as ECDH_X963_KDF (which can be
  48  *       done by creating a "X963KDF".
  49  */
  50 enum kdf_type {
  51     PROV_DH_KDF_NONE = 0,
  52     PROV_DH_KDF_X9_42_ASN1
  53 };
  54
  55 /*
  56  * What's passed as an actual key is defined by the KEYMGMT interface.
  57  * We happen to know that our KEYMGMT simply passes DH structures, so
  58  * we use that here too.
  59  */
  60
  61 typedef struct {
  62     OSSL_LIB_CTX *libctx;
  63     DH *dh;
  64     DH *dhpeer;
  65     unsigned int pad : 1;
  66
  67     /* DH KDF */
  68     /* KDF (if any) to use for DH */
  69     enum kdf_type kdf_type;
  70     /* Message digest to use for key derivation */
  71     EVP_MD *kdf_md;
  72     /* User key material */
  73     unsigned char *kdf_ukm;
  74     size_t kdf_ukmlen;
  75     /* KDF output length */
  76     size_t kdf_outlen;
  77     char *kdf_cekalg;
  78 } PROV_DH_CTX;
  79
  80 static void *dh_newctx(void *provctx)
  81 {
  82     PROV_DH_CTX *pdhctx;
  83
  84     if (!ossl_prov_is_running())
  85         return NULL;
  86
  87     pdhctx = OPENSSL_zalloc(sizeof(PROV_DH_CTX));
  88     if (pdhctx == NULL)
  89         return NULL;
  90     pdhctx->libctx = PROV_LIBCTX_OF(provctx);
  91     pdhctx->kdf_type = PROV_DH_KDF_NONE;
  92     return pdhctx;
  93 }
  94
  95 static int dh_init(void *vpdhctx, void *vdh)
  96 {
  97     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
  98
  99     if (!ossl_prov_is_running()
 100             || pdhctx == NULL
 101             || vdh == NULL
 102             || !DH_up_ref(vdh))
 103         return 0;
 104     DH_free(pdhctx->dh);
 105     pdhctx->dh = vdh;
 106     pdhctx->kdf_type = PROV_DH_KDF_NONE;
 107     return ossl_dh_check_key(vdh);
 108 }
 109
 110 static int dh_set_peer(void *vpdhctx, void *vdh)
 111 {
 112     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
 113
 114     if (!ossl_prov_is_running()
 115             || pdhctx == NULL
 116             || vdh == NULL
 117             || !DH_up_ref(vdh))
 118         return 0;
 119     DH_free(pdhctx->dhpeer);
 120     pdhctx->dhpeer = vdh;
 121     return 1;
 122 }
 123
 124 static int dh_plain_derive(void *vpdhctx,
 125                            unsigned char *secret, size_t *secretlen,
 126                            size_t outlen)
 127 {
 128     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
 129     int ret;
 130     size_t dhsize;
 131     const BIGNUM *pub_key = NULL;
 132
 133     /* TODO(3.0): Add errors to stack */
 134     if (pdhctx->dh == NULL || pdhctx->dhpeer == NULL)
 135         return 0;
 136
 137     dhsize = (size_t)DH_size(pdhctx->dh);
 138     if (secret == NULL) {
 139         *secretlen = dhsize;
 140         return 1;
 141     }
 142     if (outlen < dhsize)
 143         return 0;
 144
 145     DH_get0_key(pdhctx->dhpeer, &pub_key, NULL);
 146     if (pdhctx->pad)
 147         ret = DH_compute_key_padded(secret, pub_key, pdhctx->dh);
 148     else
 149         ret = DH_compute_key(secret, pub_key, pdhctx->dh);
 150     if (ret <= 0)
 151         return 0;
 152
 153     *secretlen = ret;
 154     return 1;
 155 }
 156
 157 static int dh_X9_42_kdf_derive(void *vpdhctx, unsigned char *secret,
 158                                size_t *secretlen, size_t outlen)
 159 {
 160     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
 161     unsigned char *stmp = NULL;
 162     size_t stmplen;
 163     int ret = 0;
 164
 165     if (secret == NULL) {
 166         *secretlen = pdhctx->kdf_outlen;
 167         return 1;
 168     }
 169
 170     if (pdhctx->kdf_outlen > outlen)
 171         return 0;
 172     if (!dh_plain_derive(pdhctx, NULL, &stmplen, 0))
 173         return 0;
 174     if ((stmp = OPENSSL_secure_malloc(stmplen)) == NULL) {
 175         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 176         return 0;
 177     }
 178     if (!dh_plain_derive(pdhctx, stmp, &stmplen, stmplen))
 179         goto err;
 180
 181     /* Do KDF stuff */
 182     if (pdhctx->kdf_type == PROV_DH_KDF_X9_42_ASN1) {
 183         if (!dh_KDF_X9_42_asn1(secret, pdhctx->kdf_outlen,
 184                                stmp, stmplen,
 185                                pdhctx->kdf_cekalg,
 186                                pdhctx->kdf_ukm,
 187                                pdhctx->kdf_ukmlen,
 188                                pdhctx->kdf_md,
 189                                pdhctx->libctx, NULL))
 190             goto err;
 191     }
 192     *secretlen = pdhctx->kdf_outlen;
 193     ret = 1;
 194 err:
 195     OPENSSL_secure_clear_free(stmp, stmplen);
 196     return ret;
 197 }
 198
 199 static int dh_derive(void *vpdhctx, unsigned char *secret,
 200                      size_t *psecretlen, size_t outlen)
 201 {
 202     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
 203
 204     if (!ossl_prov_is_running())
 205         return 0;
 206
 207     switch (pdhctx->kdf_type) {
 208         case PROV_DH_KDF_NONE:
 209             return dh_plain_derive(pdhctx, secret, psecretlen, outlen);
 210         case PROV_DH_KDF_X9_42_ASN1:
 211             return dh_X9_42_kdf_derive(pdhctx, secret, psecretlen, outlen);
 212         default:
 213             break;
 214     }
 215     return 0;
 216 }
 217
 218
 219 static void dh_freectx(void *vpdhctx)
 220 {
 221     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
 222
 223     OPENSSL_free(pdhctx->kdf_cekalg);
 224     DH_free(pdhctx->dh);
 225     DH_free(pdhctx->dhpeer);
 226     EVP_MD_free(pdhctx->kdf_md);
 227     OPENSSL_clear_free(pdhctx->kdf_ukm, pdhctx->kdf_ukmlen);
 228
 229     OPENSSL_free(pdhctx);
 230 }
 231
 232 static void *dh_dupctx(void *vpdhctx)
 233 {
 234     PROV_DH_CTX *srcctx = (PROV_DH_CTX *)vpdhctx;
 235     PROV_DH_CTX *dstctx;
 236
 237     if (!ossl_prov_is_running())
 238         return NULL;
 239
 240     dstctx = OPENSSL_zalloc(sizeof(*srcctx));
 241     if (dstctx == NULL)
 242         return NULL;
 243
 244     *dstctx = *srcctx;
 245     dstctx->dh = NULL;
 246     dstctx->dhpeer = NULL;
 247     dstctx->kdf_md = NULL;
 248     dstctx->kdf_ukm = NULL;
 249     dstctx->kdf_cekalg = NULL;
 250
 251     if (dstctx->dh != NULL && !DH_up_ref(srcctx->dh))
 252         goto err;
 253     else
 254         dstctx->dh = srcctx->dh;
 255
 256     if (dstctx->dhpeer != NULL && !DH_up_ref(srcctx->dhpeer))
 257         goto err;
 258     else
 259         dstctx->dhpeer = srcctx->dhpeer;
 260
 261     if (srcctx->kdf_md != NULL && !EVP_MD_up_ref(srcctx->kdf_md))
 262         goto err;
 263     else
 264         dstctx->kdf_md = srcctx->kdf_md;
 265
 266     /* Duplicate UKM data if present */
 267     if (srcctx->kdf_ukm != NULL && srcctx->kdf_ukmlen > 0) {
 268         dstctx->kdf_ukm = OPENSSL_memdup(srcctx->kdf_ukm,
 269                                          srcctx->kdf_ukmlen);
 270         if (dstctx->kdf_ukm == NULL)
 271             goto err;
 272     }
 273     dstctx->kdf_cekalg = OPENSSL_strdup(srcctx->kdf_cekalg);
 274
 275     return dstctx;
 276 err:
 277     dh_freectx(dstctx);
 278     return NULL;
 279 }
 280
 281 static int dh_set_ctx_params(void *vpdhctx, const OSSL_PARAM params[])
 282 {
 283     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
 284     const OSSL_PARAM *p;
 285     unsigned int pad;
 286     char name[80] = { '\0' }; /* should be big enough */
 287     char *str = NULL;
 288
 289     if (pdhctx == NULL || params == NULL)
 290         return 0;
 291
 292     p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
 293     if (p != NULL) {
 294         str = name;
 295         if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
 296             return 0;
 297
 298         if (name[0] == '\0')
 299             pdhctx->kdf_type = PROV_DH_KDF_NONE;
 300         else if (strcmp(name, OSSL_KDF_NAME_X942KDF_ASN1) == 0)
 301             pdhctx->kdf_type = PROV_DH_KDF_X9_42_ASN1;
 302         else
 303             return 0;
 304     }
 305     p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
 306     if (p != NULL) {
 307         char mdprops[80] = { '\0' }; /* should be big enough */
 308
 309         str = name;
 310         if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
 311             return 0;
 312
 313         str = mdprops;
 314         p = OSSL_PARAM_locate_const(params,
 315                                     OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS);
 316
 317         if (p != NULL) {
 318             if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(mdprops)))
 319                 return 0;
 320         }
 321
 322         EVP_MD_free(pdhctx->kdf_md);
 323         pdhctx->kdf_md = EVP_MD_fetch(pdhctx->libctx, name, mdprops);
 324         if (!ossl_digest_is_allowed(pdhctx->kdf_md)) {
 325             EVP_MD_free(pdhctx->kdf_md);
 326             pdhctx->kdf_md = NULL;
 327         }
 328         if (pdhctx->kdf_md == NULL)
 329             return 0;
 330     }
 331
 332     p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
 333     if (p != NULL) {
 334         size_t outlen;
 335
 336         if (!OSSL_PARAM_get_size_t(p, &outlen))
 337             return 0;
 338         pdhctx->kdf_outlen = outlen;
 339     }
 340
 341     p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
 342     if (p != NULL) {
 343         void *tmp_ukm = NULL;
 344         size_t tmp_ukmlen;
 345
 346         OPENSSL_free(pdhctx->kdf_ukm);
 347         pdhctx->kdf_ukm = NULL;
 348         pdhctx->kdf_ukmlen = 0;
 349         /* ukm is an optional field so it can be NULL */
 350         if (p->data != NULL && p->data_size != 0) {
 351             if (!OSSL_PARAM_get_octet_string(p, &tmp_ukm, 0, &tmp_ukmlen))
 352                 return 0;
 353             pdhctx->kdf_ukm = tmp_ukm;
 354             pdhctx->kdf_ukmlen = tmp_ukmlen;
 355         }
 356     }
 357
 358     p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_PAD);
 359     if (p != NULL) {
 360         if (!OSSL_PARAM_get_uint(p, &pad))
 361             return 0;
 362         pdhctx->pad = pad ? 1 : 0;
 363     }
 364
 365     p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_CEK_ALG);
 366     if (p != NULL) {
 367         str = name;
 368         if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
 369             return 0;
 370         pdhctx->kdf_cekalg = OPENSSL_strdup(name);
 371     }
 372     return 1;
 373 }
 374
 375 static const OSSL_PARAM known_settable_ctx_params[] = {
 376     OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_PAD, NULL),
 377     OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
 378     OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
 379     OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS, NULL, 0),
 380     OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
 381     OSSL_PARAM_octet_string(OSSL_EXCHANGE_PARAM_KDF_UKM, NULL, 0),
 382     OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
 383     OSSL_PARAM_END
 384 };
 385
 386 static const OSSL_PARAM *dh_settable_ctx_params(ossl_unused void *provctx)
 387 {
 388     return known_settable_ctx_params;
 389 }
 390
 391 static const OSSL_PARAM known_gettable_ctx_params[] = {
 392     OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE, NULL),
 393     OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
 394     OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
 395     OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
 396     OSSL_PARAM_DEFN(OSSL_EXCHANGE_PARAM_KDF_UKM, OSSL_PARAM_OCTET_PTR,
 397                     NULL, 0),
 398     OSSL_PARAM_END
 399 };
 400
 401 static const OSSL_PARAM *dh_gettable_ctx_params(ossl_unused void *provctx)
 402 {
 403     return known_gettable_ctx_params;
 404 }
 405
 406 static int dh_get_ctx_params(void *vpdhctx, OSSL_PARAM params[])
 407 {
 408     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
 409     OSSL_PARAM *p;
 410
 411     if (pdhctx == NULL || params == NULL)
 412         return 0;
 413
 414     p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
 415     if (p != NULL) {
 416         const char *kdf_type = NULL;
 417
 418         switch (pdhctx->kdf_type) {
 419             case PROV_DH_KDF_NONE:
 420                 kdf_type = "";
 421                 break;
 422             case PROV_DH_KDF_X9_42_ASN1:
 423                 kdf_type = OSSL_KDF_NAME_X942KDF_ASN1;
 424                 break;
 425             default:
 426                 return 0;
 427         }
 428
 429         if (!OSSL_PARAM_set_utf8_string(p, kdf_type))
 430             return 0;
 431     }
 432
 433     p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
 434     if (p != NULL
 435             && !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_md == NULL
 436                                            ? ""
 437                                            : EVP_MD_name(pdhctx->kdf_md))){
 438         return 0;
 439     }
 440
 441     p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
 442     if (p != NULL && !OSSL_PARAM_set_size_t(p, pdhctx->kdf_outlen))
 443         return 0;
 444
 445     p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
 446     if (p != NULL
 447         && !OSSL_PARAM_set_octet_ptr(p, pdhctx->kdf_ukm, pdhctx->kdf_ukmlen))
 448         return 0;
 449
 450     p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_CEK_ALG);
 451     if (p != NULL
 452             && !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_cekalg == NULL
 453                                            ? "" :  pdhctx->kdf_cekalg))
 454         return 0;
 455
 456     return 1;
 457 }
 458
 459 const OSSL_DISPATCH ossl_dh_keyexch_functions[] = {
 460     { OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))dh_newctx },
 461     { OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))dh_init },
 462     { OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))dh_derive },
 463     { OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))dh_set_peer },
 464     { OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))dh_freectx },
 465     { OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))dh_dupctx },
 466     { OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))dh_set_ctx_params },
 467     { OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
 468       (void (*)(void))dh_settable_ctx_params },
 469     { OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS, (void (*)(void))dh_get_ctx_params },
 470     { OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS,
 471       (void (*)(void))dh_gettable_ctx_params },
 472     { 0, NULL }
 473 };