1/* 2 * Copyright 2014-2021 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/* Custom extension utility functions */ 11 12#include <openssl/ct.h> 13#include "../ssl_local.h" 14#include "internal/cryptlib.h" 15#include "statem_local.h" 16 17typedef struct { 18 void *add_arg; 19 custom_ext_add_cb add_cb; 20 custom_ext_free_cb free_cb; 21} custom_ext_add_cb_wrap; 22 23typedef struct { 24 void *parse_arg; 25 custom_ext_parse_cb parse_cb; 26} custom_ext_parse_cb_wrap; 27 28/* 29 * Provide thin wrapper callbacks which convert new style arguments to old style 30 */ 31static int custom_ext_add_old_cb_wrap(SSL *s, unsigned int ext_type, 32 unsigned int context, 33 const unsigned char **out, 34 size_t *outlen, X509 *x, size_t chainidx, 35 int *al, void *add_arg) 36{ 37 custom_ext_add_cb_wrap *add_cb_wrap = (custom_ext_add_cb_wrap *)add_arg; 38 39 if (add_cb_wrap->add_cb == NULL) 40 return 1; 41 42 return add_cb_wrap->add_cb(s, ext_type, out, outlen, al, 43 add_cb_wrap->add_arg); 44} 45 46static void custom_ext_free_old_cb_wrap(SSL *s, unsigned int ext_type, 47 unsigned int context, 48 const unsigned char *out, void *add_arg) 49{ 50 custom_ext_add_cb_wrap *add_cb_wrap = (custom_ext_add_cb_wrap *)add_arg; 51 52 if (add_cb_wrap->free_cb == NULL) 53 return; 54 55 add_cb_wrap->free_cb(s, ext_type, out, add_cb_wrap->add_arg); 56} 57 58static int custom_ext_parse_old_cb_wrap(SSL *s, unsigned int ext_type, 59 unsigned int context, 60 const unsigned char *in, 61 size_t inlen, X509 *x, size_t chainidx, 62 int *al, void *parse_arg) 63{ 64 custom_ext_parse_cb_wrap *parse_cb_wrap = 65 (custom_ext_parse_cb_wrap *)parse_arg; 66 67 if (parse_cb_wrap->parse_cb == NULL) 68 return 1; 69 70 return parse_cb_wrap->parse_cb(s, ext_type, in, inlen, al, 71 parse_cb_wrap->parse_arg); 72} 73 74/* 75 * Find a custom extension from the list. The |role| param is there to 76 * support the legacy API where custom extensions for client and server could 77 * be set independently on the same SSL_CTX. It is set to ENDPOINT_SERVER if we 78 * are trying to find a method relevant to the server, ENDPOINT_CLIENT for the 79 * client, or ENDPOINT_BOTH for either 80 */ 81custom_ext_method *custom_ext_find(const custom_ext_methods *exts, 82 ENDPOINT role, unsigned int ext_type, 83 size_t *idx) 84{ 85 size_t i; 86 custom_ext_method *meth = exts->meths; 87 88 for (i = 0; i < exts->meths_count; i++, meth++) { 89 if (ext_type == meth->ext_type 90 && (role == ENDPOINT_BOTH || role == meth->role 91 || meth->role == ENDPOINT_BOTH)) { 92 if (idx != NULL) 93 *idx = i; 94 return meth; 95 } 96 } 97 return NULL; 98} 99 100/* 101 * Initialise custom extensions flags to indicate neither sent nor received. 102 */ 103void custom_ext_init(custom_ext_methods *exts) 104{ 105 size_t i; 106 custom_ext_method *meth = exts->meths; 107 108 for (i = 0; i < exts->meths_count; i++, meth++) 109 meth->ext_flags = 0; 110} 111 112/* Pass received custom extension data to the application for parsing. */ 113int custom_ext_parse(SSL *s, unsigned int context, unsigned int ext_type, 114 const unsigned char *ext_data, size_t ext_size, X509 *x, 115 size_t chainidx) 116{ 117 int al; 118 custom_ext_methods *exts = &s->cert->custext; 119 custom_ext_method *meth; 120 ENDPOINT role = ENDPOINT_BOTH; 121 122 if ((context & (SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO)) != 0) 123 role = s->server ? ENDPOINT_SERVER : ENDPOINT_CLIENT; 124 125 meth = custom_ext_find(exts, role, ext_type, NULL); 126 /* If not found return success */ 127 if (!meth) 128 return 1; 129 130 /* Check if extension is defined for our protocol. If not, skip */ 131 if (!extension_is_relevant(s, meth->context, context)) 132 return 1; 133 134 if ((context & (SSL_EXT_TLS1_2_SERVER_HELLO 135 | SSL_EXT_TLS1_3_SERVER_HELLO 136 | SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS)) != 0) { 137 /* 138 * If it's ServerHello or EncryptedExtensions we can't have any 139 * extensions not sent in ClientHello. 140 */ 141 if ((meth->ext_flags & SSL_EXT_FLAG_SENT) == 0) { 142 SSLfatal(s, TLS1_AD_UNSUPPORTED_EXTENSION, SSL_R_BAD_EXTENSION); 143 return 0; 144 } 145 } 146 147 /* 148 * Extensions received in the ClientHello or CertificateRequest are marked 149 * with the SSL_EXT_FLAG_RECEIVED. This is so we know to add the equivalent 150 * extensions in the response messages 151 */ 152 if ((context & (SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_CERTIFICATE_REQUEST)) 153 != 0) 154 meth->ext_flags |= SSL_EXT_FLAG_RECEIVED; 155 156 /* If no parse function set return success */ 157 if (!meth->parse_cb) 158 return 1; 159 160 if (meth->parse_cb(s, ext_type, context, ext_data, ext_size, x, chainidx, 161 &al, meth->parse_arg) <= 0) { 162 SSLfatal(s, al, SSL_R_BAD_EXTENSION); 163 return 0; 164 } 165 166 return 1; 167} 168 169/* 170 * Request custom extension data from the application and add to the return 171 * buffer. 172 */ 173int custom_ext_add(SSL *s, int context, WPACKET *pkt, X509 *x, size_t chainidx, 174 int maxversion) 175{ 176 custom_ext_methods *exts = &s->cert->custext; 177 custom_ext_method *meth; 178 size_t i; 179 int al; 180 181 for (i = 0; i < exts->meths_count; i++) { 182 const unsigned char *out = NULL; 183 size_t outlen = 0; 184 185 meth = exts->meths + i; 186 187 if (!should_add_extension(s, meth->context, context, maxversion)) 188 continue; 189 190 if ((context & (SSL_EXT_TLS1_2_SERVER_HELLO 191 | SSL_EXT_TLS1_3_SERVER_HELLO 192 | SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS 193 | SSL_EXT_TLS1_3_CERTIFICATE 194 | SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST)) != 0) { 195 /* Only send extensions present in ClientHello/CertificateRequest */ 196 if (!(meth->ext_flags & SSL_EXT_FLAG_RECEIVED)) 197 continue; 198 } 199 /* 200 * We skip it if the callback is absent - except for a ClientHello where 201 * we add an empty extension. 202 */ 203 if ((context & SSL_EXT_CLIENT_HELLO) == 0 && meth->add_cb == NULL) 204 continue; 205 206 if (meth->add_cb != NULL) { 207 int cb_retval = meth->add_cb(s, meth->ext_type, context, &out, 208 &outlen, x, chainidx, &al, 209 meth->add_arg); 210 211 if (cb_retval < 0) { 212 SSLfatal(s, al, SSL_R_CALLBACK_FAILED); 213 return 0; /* error */ 214 } 215 if (cb_retval == 0) 216 continue; /* skip this extension */ 217 } 218 219 if (!WPACKET_put_bytes_u16(pkt, meth->ext_type) 220 || !WPACKET_start_sub_packet_u16(pkt) 221 || (outlen > 0 && !WPACKET_memcpy(pkt, out, outlen)) 222 || !WPACKET_close(pkt)) { 223 if (meth->free_cb != NULL) 224 meth->free_cb(s, meth->ext_type, context, out, meth->add_arg); 225 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR); 226 return 0; 227 } 228 if ((context & SSL_EXT_CLIENT_HELLO) != 0) { 229 /* 230 * We can't send duplicates: code logic should prevent this. 231 */ 232 if (!ossl_assert((meth->ext_flags & SSL_EXT_FLAG_SENT) == 0)) { 233 if (meth->free_cb != NULL) 234 meth->free_cb(s, meth->ext_type, context, out, 235 meth->add_arg); 236 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR); 237 return 0; 238 } 239 /* 240 * Indicate extension has been sent: this is both a sanity check to 241 * ensure we don't send duplicate extensions and indicates that it 242 * is not an error if the extension is present in ServerHello. 243 */ 244 meth->ext_flags |= SSL_EXT_FLAG_SENT; 245 } 246 if (meth->free_cb != NULL) 247 meth->free_cb(s, meth->ext_type, context, out, meth->add_arg); 248 } 249 return 1; 250} 251 252/* Copy the flags from src to dst for any extensions that exist in both */ 253int custom_exts_copy_flags(custom_ext_methods *dst, 254 const custom_ext_methods *src) 255{ 256 size_t i; 257 custom_ext_method *methsrc = src->meths; 258 259 for (i = 0; i < src->meths_count; i++, methsrc++) { 260 custom_ext_method *methdst = custom_ext_find(dst, methsrc->role, 261 methsrc->ext_type, NULL); 262 263 if (methdst == NULL) 264 continue; 265 266 methdst->ext_flags = methsrc->ext_flags; 267 } 268 269 return 1; 270} 271 272/* Copy table of custom extensions */ 273int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src) 274{ 275 size_t i; 276 int err = 0; 277 278 if (src->meths_count > 0) { 279 dst->meths = 280 OPENSSL_memdup(src->meths, 281 sizeof(*src->meths) * src->meths_count); 282 if (dst->meths == NULL) 283 return 0; 284 dst->meths_count = src->meths_count; 285 286 for (i = 0; i < src->meths_count; i++) { 287 custom_ext_method *methsrc = src->meths + i; 288 custom_ext_method *methdst = dst->meths + i; 289 290 if (methsrc->add_cb != custom_ext_add_old_cb_wrap) 291 continue; 292 293 /* 294 * We have found an old style API wrapper. We need to copy the 295 * arguments too. 296 */ 297 298 if (err) { 299 methdst->add_arg = NULL; 300 methdst->parse_arg = NULL; 301 continue; 302 } 303 304 methdst->add_arg = OPENSSL_memdup(methsrc->add_arg, 305 sizeof(custom_ext_add_cb_wrap)); 306 methdst->parse_arg = OPENSSL_memdup(methsrc->parse_arg, 307 sizeof(custom_ext_parse_cb_wrap)); 308 309 if (methdst->add_arg == NULL || methdst->parse_arg == NULL) 310 err = 1; 311 } 312 } 313 314 if (err) { 315 custom_exts_free(dst); 316 return 0; 317 } 318 319 return 1; 320} 321 322void custom_exts_free(custom_ext_methods *exts) 323{ 324 size_t i; 325 custom_ext_method *meth; 326 327 for (i = 0, meth = exts->meths; i < exts->meths_count; i++, meth++) { 328 if (meth->add_cb != custom_ext_add_old_cb_wrap) 329 continue; 330 331 /* Old style API wrapper. Need to free the arguments too */ 332 OPENSSL_free(meth->add_arg); 333 OPENSSL_free(meth->parse_arg); 334 } 335 OPENSSL_free(exts->meths); 336 exts->meths = NULL; 337 exts->meths_count = 0; 338} 339 340/* Return true if a client custom extension exists, false otherwise */ 341int SSL_CTX_has_client_custom_ext(const SSL_CTX *ctx, unsigned int ext_type) 342{ 343 return custom_ext_find(&ctx->cert->custext, ENDPOINT_CLIENT, ext_type, 344 NULL) != NULL; 345} 346 347static int add_custom_ext_intern(SSL_CTX *ctx, ENDPOINT role, 348 unsigned int ext_type, 349 unsigned int context, 350 SSL_custom_ext_add_cb_ex add_cb, 351 SSL_custom_ext_free_cb_ex free_cb, 352 void *add_arg, 353 SSL_custom_ext_parse_cb_ex parse_cb, 354 void *parse_arg) 355{ 356 custom_ext_methods *exts = &ctx->cert->custext; 357 custom_ext_method *meth, *tmp; 358 359 /* 360 * Check application error: if add_cb is not set free_cb will never be 361 * called. 362 */ 363 if (add_cb == NULL && free_cb != NULL) 364 return 0; 365 366#ifndef OPENSSL_NO_CT 367 /* 368 * We don't want applications registering callbacks for SCT extensions 369 * whilst simultaneously using the built-in SCT validation features, as 370 * these two things may not play well together. 371 */ 372 if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp 373 && (context & SSL_EXT_CLIENT_HELLO) != 0 374 && SSL_CTX_ct_is_enabled(ctx)) 375 return 0; 376#endif 377 378 /* 379 * Don't add if extension supported internally, but make exception 380 * for extension types that previously were not supported, but now are. 381 */ 382 if (SSL_extension_supported(ext_type) 383 && ext_type != TLSEXT_TYPE_signed_certificate_timestamp) 384 return 0; 385 386 /* Extension type must fit in 16 bits */ 387 if (ext_type > 0xffff) 388 return 0; 389 /* Search for duplicate */ 390 if (custom_ext_find(exts, role, ext_type, NULL)) 391 return 0; 392 tmp = OPENSSL_realloc(exts->meths, 393 (exts->meths_count + 1) * sizeof(custom_ext_method)); 394 if (tmp == NULL) 395 return 0; 396 397 exts->meths = tmp; 398 meth = exts->meths + exts->meths_count; 399 memset(meth, 0, sizeof(*meth)); 400 meth->role = role; 401 meth->context = context; 402 meth->parse_cb = parse_cb; 403 meth->add_cb = add_cb; 404 meth->free_cb = free_cb; 405 meth->ext_type = ext_type; 406 meth->add_arg = add_arg; 407 meth->parse_arg = parse_arg; 408 exts->meths_count++; 409 return 1; 410} 411 412static int add_old_custom_ext(SSL_CTX *ctx, ENDPOINT role, 413 unsigned int ext_type, 414 unsigned int context, 415 custom_ext_add_cb add_cb, 416 custom_ext_free_cb free_cb, 417 void *add_arg, 418 custom_ext_parse_cb parse_cb, void *parse_arg) 419{ 420 custom_ext_add_cb_wrap *add_cb_wrap 421 = OPENSSL_malloc(sizeof(*add_cb_wrap)); 422 custom_ext_parse_cb_wrap *parse_cb_wrap 423 = OPENSSL_malloc(sizeof(*parse_cb_wrap)); 424 int ret; 425 426 if (add_cb_wrap == NULL || parse_cb_wrap == NULL) { 427 OPENSSL_free(add_cb_wrap); 428 OPENSSL_free(parse_cb_wrap); 429 return 0; 430 } 431 432 add_cb_wrap->add_arg = add_arg; 433 add_cb_wrap->add_cb = add_cb; 434 add_cb_wrap->free_cb = free_cb; 435 parse_cb_wrap->parse_arg = parse_arg; 436 parse_cb_wrap->parse_cb = parse_cb; 437 438 ret = add_custom_ext_intern(ctx, role, ext_type, 439 context, 440 custom_ext_add_old_cb_wrap, 441 custom_ext_free_old_cb_wrap, 442 add_cb_wrap, 443 custom_ext_parse_old_cb_wrap, 444 parse_cb_wrap); 445 446 if (!ret) { 447 OPENSSL_free(add_cb_wrap); 448 OPENSSL_free(parse_cb_wrap); 449 } 450 451 return ret; 452} 453 454/* Application level functions to add the old custom extension callbacks */ 455int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type, 456 custom_ext_add_cb add_cb, 457 custom_ext_free_cb free_cb, 458 void *add_arg, 459 custom_ext_parse_cb parse_cb, void *parse_arg) 460{ 461 return add_old_custom_ext(ctx, ENDPOINT_CLIENT, ext_type, 462 SSL_EXT_TLS1_2_AND_BELOW_ONLY 463 | SSL_EXT_CLIENT_HELLO 464 | SSL_EXT_TLS1_2_SERVER_HELLO 465 | SSL_EXT_IGNORE_ON_RESUMPTION, 466 add_cb, free_cb, add_arg, parse_cb, parse_arg); 467} 468 469int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type, 470 custom_ext_add_cb add_cb, 471 custom_ext_free_cb free_cb, 472 void *add_arg, 473 custom_ext_parse_cb parse_cb, void *parse_arg) 474{ 475 return add_old_custom_ext(ctx, ENDPOINT_SERVER, ext_type, 476 SSL_EXT_TLS1_2_AND_BELOW_ONLY 477 | SSL_EXT_CLIENT_HELLO 478 | SSL_EXT_TLS1_2_SERVER_HELLO 479 | SSL_EXT_IGNORE_ON_RESUMPTION, 480 add_cb, free_cb, add_arg, parse_cb, parse_arg); 481} 482 483int SSL_CTX_add_custom_ext(SSL_CTX *ctx, unsigned int ext_type, 484 unsigned int context, 485 SSL_custom_ext_add_cb_ex add_cb, 486 SSL_custom_ext_free_cb_ex free_cb, 487 void *add_arg, 488 SSL_custom_ext_parse_cb_ex parse_cb, void *parse_arg) 489{ 490 return add_custom_ext_intern(ctx, ENDPOINT_BOTH, ext_type, context, add_cb, 491 free_cb, add_arg, parse_cb, parse_arg); 492} 493 494int SSL_extension_supported(unsigned int ext_type) 495{ 496 switch (ext_type) { 497 /* Internally supported extensions. */ 498 case TLSEXT_TYPE_application_layer_protocol_negotiation: 499 case TLSEXT_TYPE_ec_point_formats: 500 case TLSEXT_TYPE_supported_groups: 501 case TLSEXT_TYPE_key_share: 502#ifndef OPENSSL_NO_NEXTPROTONEG 503 case TLSEXT_TYPE_next_proto_neg: 504#endif 505 case TLSEXT_TYPE_padding: 506 case TLSEXT_TYPE_renegotiate: 507 case TLSEXT_TYPE_max_fragment_length: 508 case TLSEXT_TYPE_server_name: 509 case TLSEXT_TYPE_session_ticket: 510 case TLSEXT_TYPE_signature_algorithms: 511#ifndef OPENSSL_NO_SRP 512 case TLSEXT_TYPE_srp: 513#endif 514#ifndef OPENSSL_NO_OCSP 515 case TLSEXT_TYPE_status_request: 516#endif 517#ifndef OPENSSL_NO_CT 518 case TLSEXT_TYPE_signed_certificate_timestamp: 519#endif 520#ifndef OPENSSL_NO_SRTP 521 case TLSEXT_TYPE_use_srtp: 522#endif 523 case TLSEXT_TYPE_encrypt_then_mac: 524 case TLSEXT_TYPE_supported_versions: 525 case TLSEXT_TYPE_extended_master_secret: 526 case TLSEXT_TYPE_psk_kex_modes: 527 case TLSEXT_TYPE_cookie: 528 case TLSEXT_TYPE_early_data: 529 case TLSEXT_TYPE_certificate_authorities: 530 case TLSEXT_TYPE_psk: 531 case TLSEXT_TYPE_post_handshake_auth: 532 return 1; 533 default: 534 return 0; 535 } 536} 537