providers/implementations/exchange/dh_exch.c

   1 /*
   2  * Copyright 2019-2023 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
  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
  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 */
 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
 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
 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
 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         return 0;
 199     if (!dh_plain_derive(pdhctx, stmp, &stmplen, stmplen, 1))
 200         goto err;
 201
 202     /* Do KDF stuff */
 203     if (pdhctx->kdf_type == PROV_DH_KDF_X9_42_ASN1) {
 204         if (!ossl_dh_kdf_X9_42_asn1(secret, pdhctx->kdf_outlen,
 205                                     stmp, stmplen,
 206                                     pdhctx->kdf_cekalg,
 207                                     pdhctx->kdf_ukm,
 208                                     pdhctx->kdf_ukmlen,
 209                                     pdhctx->kdf_md,
 210                                     pdhctx->libctx, NULL))
 211             goto err;
 212     }
 213     *secretlen = pdhctx->kdf_outlen;
 214     ret = 1;
 215 err:
 216     OPENSSL_secure_clear_free(stmp, stmplen);
 217     return ret;
 218 }
 219
 220 static int dh_derive(void *vpdhctx, unsigned char *secret,
 221                      size_t *psecretlen, size_t outlen)
 222 {
 223     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
 224
 225     if (!ossl_prov_is_running())
 226         return 0;
 227
 228     switch (pdhctx->kdf_type) {
 229         case PROV_DH_KDF_NONE:
 230             return dh_plain_derive(pdhctx, secret, psecretlen, outlen,
 231                                    pdhctx->pad);
 232         case PROV_DH_KDF_X9_42_ASN1:
 233             return dh_X9_42_kdf_derive(pdhctx, secret, psecretlen, outlen);
 234         default:
 235             break;
 236     }
 237     return 0;
 238 }
 239
 240 static void dh_freectx(void *vpdhctx)
 241 {
 242     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
 243
 244     OPENSSL_free(pdhctx->kdf_cekalg);
 245     DH_free(pdhctx->dh);
 246     DH_free(pdhctx->dhpeer);
 247     EVP_MD_free(pdhctx->kdf_md);
 248     OPENSSL_clear_free(pdhctx->kdf_ukm, pdhctx->kdf_ukmlen);
 249
 250     OPENSSL_free(pdhctx);
 251 }
 252
 253 static void *dh_dupctx(void *vpdhctx)
 254 {
 255     PROV_DH_CTX *srcctx = (PROV_DH_CTX *)vpdhctx;
 256     PROV_DH_CTX *dstctx;
 257
 258     if (!ossl_prov_is_running())
 259         return NULL;
 260
 261     dstctx = OPENSSL_zalloc(sizeof(*srcctx));
 262     if (dstctx == NULL)
 263         return NULL;
 264
 265     *dstctx = *srcctx;
 266     dstctx->dh = NULL;
 267     dstctx->dhpeer = NULL;
 268     dstctx->kdf_md = NULL;
 269     dstctx->kdf_ukm = NULL;
 270     dstctx->kdf_cekalg = NULL;
 271
 272     if (srcctx->dh != NULL && !DH_up_ref(srcctx->dh))
 273         goto err;
 274     else
 275         dstctx->dh = srcctx->dh;
 276
 277     if (srcctx->dhpeer != NULL && !DH_up_ref(srcctx->dhpeer))
 278         goto err;
 279     else
 280         dstctx->dhpeer = srcctx->dhpeer;
 281
 282     if (srcctx->kdf_md != NULL && !EVP_MD_up_ref(srcctx->kdf_md))
 283         goto err;
 284     else
 285         dstctx->kdf_md = srcctx->kdf_md;
 286
 287     /* Duplicate UKM data if present */
 288     if (srcctx->kdf_ukm != NULL && srcctx->kdf_ukmlen > 0) {
 289         dstctx->kdf_ukm = OPENSSL_memdup(srcctx->kdf_ukm,
 290                                          srcctx->kdf_ukmlen);
 291         if (dstctx->kdf_ukm == NULL)
 292             goto err;
 293     }
 294
 295     if (srcctx->kdf_cekalg != NULL) {
 296         dstctx->kdf_cekalg = OPENSSL_strdup(srcctx->kdf_cekalg);
 297         if (dstctx->kdf_cekalg == NULL)
 298             goto err;
 299     }
 300
 301     return dstctx;
 302 err:
 303     dh_freectx(dstctx);
 304     return NULL;
 305 }
 306
 307 static int dh_set_ctx_params(void *vpdhctx, const OSSL_PARAM params[])
 308 {
 309     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
 310     const OSSL_PARAM *p;
 311     unsigned int pad;
 312     char name[80] = { '\0' }; /* should be big enough */
 313     char *str = NULL;
 314
 315     if (pdhctx == NULL)
 316         return 0;
 317     if (params == NULL)
 318         return 1;
 319
 320     p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
 321     if (p != NULL) {
 322         str = name;
 323         if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
 324             return 0;
 325
 326         if (name[0] == '\0')
 327             pdhctx->kdf_type = PROV_DH_KDF_NONE;
 328         else if (strcmp(name, OSSL_KDF_NAME_X942KDF_ASN1) == 0)
 329             pdhctx->kdf_type = PROV_DH_KDF_X9_42_ASN1;
 330         else
 331             return 0;
 332     }
 333     p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
 334     if (p != NULL) {
 335         char mdprops[80] = { '\0' }; /* should be big enough */
 336
 337         str = name;
 338         if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
 339             return 0;
 340
 341         str = mdprops;
 342         p = OSSL_PARAM_locate_const(params,
 343                                     OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS);
 344
 345         if (p != NULL) {
 346             if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(mdprops)))
 347                 return 0;
 348         }
 349
 350         EVP_MD_free(pdhctx->kdf_md);
 351         pdhctx->kdf_md = EVP_MD_fetch(pdhctx->libctx, name, mdprops);
 352         if (pdhctx->kdf_md == NULL)
 353             return 0;
 354         if (!ossl_digest_is_allowed(pdhctx->libctx, pdhctx->kdf_md)) {
 355             EVP_MD_free(pdhctx->kdf_md);
 356             pdhctx->kdf_md = NULL;
 357             return 0;
 358         }
 359     }
 360
 361     p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
 362     if (p != NULL) {
 363         size_t outlen;
 364
 365         if (!OSSL_PARAM_get_size_t(p, &outlen))
 366             return 0;
 367         pdhctx->kdf_outlen = outlen;
 368     }
 369
 370     p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
 371     if (p != NULL) {
 372         void *tmp_ukm = NULL;
 373         size_t tmp_ukmlen;
 374
 375         OPENSSL_free(pdhctx->kdf_ukm);
 376         pdhctx->kdf_ukm = NULL;
 377         pdhctx->kdf_ukmlen = 0;
 378         /* ukm is an optional field so it can be NULL */
 379         if (p->data != NULL && p->data_size != 0) {
 380             if (!OSSL_PARAM_get_octet_string(p, &tmp_ukm, 0, &tmp_ukmlen))
 381                 return 0;
 382             pdhctx->kdf_ukm = tmp_ukm;
 383             pdhctx->kdf_ukmlen = tmp_ukmlen;
 384         }
 385     }
 386
 387     p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_PAD);
 388     if (p != NULL) {
 389         if (!OSSL_PARAM_get_uint(p, &pad))
 390             return 0;
 391         pdhctx->pad = pad ? 1 : 0;
 392     }
 393
 394     p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_CEK_ALG);
 395     if (p != NULL) {
 396         str = name;
 397
 398         OPENSSL_free(pdhctx->kdf_cekalg);
 399         pdhctx->kdf_cekalg = NULL;
 400         if (p->data != NULL && p->data_size != 0) {
 401             if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
 402                 return 0;
 403             pdhctx->kdf_cekalg = OPENSSL_strdup(name);
 404             if (pdhctx->kdf_cekalg == NULL)
 405                 return 0;
 406         }
 407     }
 408     return 1;
 409 }
 410
 411 static const OSSL_PARAM known_settable_ctx_params[] = {
 412     OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_PAD, NULL),
 413     OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
 414     OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
 415     OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS, NULL, 0),
 416     OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
 417     OSSL_PARAM_octet_string(OSSL_EXCHANGE_PARAM_KDF_UKM, NULL, 0),
 418     OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
 419     OSSL_PARAM_END
 420 };
 421
 422 static const OSSL_PARAM *dh_settable_ctx_params(ossl_unused void *vpdhctx,
 423                                                 ossl_unused void *provctx)
 424 {
 425     return known_settable_ctx_params;
 426 }
 427
 428 static const OSSL_PARAM known_gettable_ctx_params[] = {
 429     OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
 430     OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
 431     OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
 432     OSSL_PARAM_DEFN(OSSL_EXCHANGE_PARAM_KDF_UKM, OSSL_PARAM_OCTET_PTR,
 433                     NULL, 0),
 434     OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
 435     OSSL_PARAM_END
 436 };
 437
 438 static const OSSL_PARAM *dh_gettable_ctx_params(ossl_unused void *vpdhctx,
 439                                                 ossl_unused void *provctx)
 440 {
 441     return known_gettable_ctx_params;
 442 }
 443
 444 static int dh_get_ctx_params(void *vpdhctx, OSSL_PARAM params[])
 445 {
 446     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
 447     OSSL_PARAM *p;
 448
 449     if (pdhctx == NULL)
 450         return 0;
 451
 452     p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
 453     if (p != NULL) {
 454         const char *kdf_type = NULL;
 455
 456         switch (pdhctx->kdf_type) {
 457             case PROV_DH_KDF_NONE:
 458                 kdf_type = "";
 459                 break;
 460             case PROV_DH_KDF_X9_42_ASN1:
 461                 kdf_type = OSSL_KDF_NAME_X942KDF_ASN1;
 462                 break;
 463             default:
 464                 return 0;
 465         }
 466
 467         if (!OSSL_PARAM_set_utf8_string(p, kdf_type))
 468             return 0;
 469     }
 470
 471     p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
 472     if (p != NULL
 473             && !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_md == NULL
 474                                            ? ""
 475                                            : EVP_MD_get0_name(pdhctx->kdf_md))) {
 476         return 0;
 477     }
 478
 479     p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
 480     if (p != NULL && !OSSL_PARAM_set_size_t(p, pdhctx->kdf_outlen))
 481         return 0;
 482
 483     p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
 484     if (p != NULL
 485         && !OSSL_PARAM_set_octet_ptr(p, pdhctx->kdf_ukm, pdhctx->kdf_ukmlen))
 486         return 0;
 487
 488     p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_CEK_ALG);
 489     if (p != NULL
 490             && !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_cekalg == NULL
 491                                            ? "" :  pdhctx->kdf_cekalg))
 492         return 0;
 493
 494     return 1;
 495 }
 496
 497 const OSSL_DISPATCH ossl_dh_keyexch_functions[] = {
 498     { OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))dh_newctx },
 499     { OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))dh_init },
 500     { OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))dh_derive },
 501     { OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))dh_set_peer },
 502     { OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))dh_freectx },
 503     { OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))dh_dupctx },
 504     { OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))dh_set_ctx_params },
 505     { OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
 506       (void (*)(void))dh_settable_ctx_params },
 507     { OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS, (void (*)(void))dh_get_ctx_params },
 508     { OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS,
 509       (void (*)(void))dh_gettable_ctx_params },
 510     OSSL_DISPATCH_END
 511 };