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 17 typedef 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 23 typedef 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 */ 31 static 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 46 static 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 58 static 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 */ 81 custom_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 */ 103 void 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. */ 113 int 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 */ 173 int 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 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR); 224 return 0; 225 } 226 if ((context & SSL_EXT_CLIENT_HELLO) != 0) { 227 /* 228 * We can't send duplicates: code logic should prevent this. 229 */ 230 if (!ossl_assert((meth->ext_flags & SSL_EXT_FLAG_SENT) == 0)) { 231 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR); 232 return 0; 233 } 234 /* 235 * Indicate extension has been sent: this is both a sanity check to 236 * ensure we don't send duplicate extensions and indicates that it 237 * is not an error if the extension is present in ServerHello. 238 */ 239 meth->ext_flags |= SSL_EXT_FLAG_SENT; 240 } 241 if (meth->free_cb != NULL) 242 meth->free_cb(s, meth->ext_type, context, out, meth->add_arg); 243 } 244 return 1; 245 } 246 247 /* Copy the flags from src to dst for any extensions that exist in both */ 248 int custom_exts_copy_flags(custom_ext_methods *dst, 249 const custom_ext_methods *src) 250 { 251 size_t i; 252 custom_ext_method *methsrc = src->meths; 253 254 for (i = 0; i < src->meths_count; i++, methsrc++) { 255 custom_ext_method *methdst = custom_ext_find(dst, methsrc->role, 256 methsrc->ext_type, NULL); 257 258 if (methdst == NULL) 259 continue; 260 261 methdst->ext_flags = methsrc->ext_flags; 262 } 263 264 return 1; 265 } 266 267 /* Copy table of custom extensions */ 268 int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src) 269 { 270 size_t i; 271 int err = 0; 272 273 if (src->meths_count > 0) { 274 dst->meths = 275 OPENSSL_memdup(src->meths, 276 sizeof(*src->meths) * src->meths_count); 277 if (dst->meths == NULL) 278 return 0; 279 dst->meths_count = src->meths_count; 280 281 for (i = 0; i < src->meths_count; i++) { 282 custom_ext_method *methsrc = src->meths + i; 283 custom_ext_method *methdst = dst->meths + i; 284 285 if (methsrc->add_cb != custom_ext_add_old_cb_wrap) 286 continue; 287 288 /* 289 * We have found an old style API wrapper. We need to copy the 290 * arguments too. 291 */ 292 293 if (err) { 294 methdst->add_arg = NULL; 295 methdst->parse_arg = NULL; 296 continue; 297 } 298 299 methdst->add_arg = OPENSSL_memdup(methsrc->add_arg, 300 sizeof(custom_ext_add_cb_wrap)); 301 methdst->parse_arg = OPENSSL_memdup(methsrc->parse_arg, 302 sizeof(custom_ext_parse_cb_wrap)); 303 304 if (methdst->add_arg == NULL || methdst->parse_arg == NULL) 305 err = 1; 306 } 307 } 308 309 if (err) { 310 custom_exts_free(dst); 311 return 0; 312 } 313 314 return 1; 315 } 316 317 void custom_exts_free(custom_ext_methods *exts) 318 { 319 size_t i; 320 custom_ext_method *meth; 321 322 for (i = 0, meth = exts->meths; i < exts->meths_count; i++, meth++) { 323 if (meth->add_cb != custom_ext_add_old_cb_wrap) 324 continue; 325 326 /* Old style API wrapper. Need to free the arguments too */ 327 OPENSSL_free(meth->add_arg); 328 OPENSSL_free(meth->parse_arg); 329 } 330 OPENSSL_free(exts->meths); 331 } 332 333 /* Return true if a client custom extension exists, false otherwise */ 334 int SSL_CTX_has_client_custom_ext(const SSL_CTX *ctx, unsigned int ext_type) 335 { 336 return custom_ext_find(&ctx->cert->custext, ENDPOINT_CLIENT, ext_type, 337 NULL) != NULL; 338 } 339 340 static int add_custom_ext_intern(SSL_CTX *ctx, ENDPOINT role, 341 unsigned int ext_type, 342 unsigned int context, 343 SSL_custom_ext_add_cb_ex add_cb, 344 SSL_custom_ext_free_cb_ex free_cb, 345 void *add_arg, 346 SSL_custom_ext_parse_cb_ex parse_cb, 347 void *parse_arg) 348 { 349 custom_ext_methods *exts = &ctx->cert->custext; 350 custom_ext_method *meth, *tmp; 351 352 /* 353 * Check application error: if add_cb is not set free_cb will never be 354 * called. 355 */ 356 if (add_cb == NULL && free_cb != NULL) 357 return 0; 358 359 #ifndef OPENSSL_NO_CT 360 /* 361 * We don't want applications registering callbacks for SCT extensions 362 * whilst simultaneously using the built-in SCT validation features, as 363 * these two things may not play well together. 364 */ 365 if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp 366 && (context & SSL_EXT_CLIENT_HELLO) != 0 367 && SSL_CTX_ct_is_enabled(ctx)) 368 return 0; 369 #endif 370 371 /* 372 * Don't add if extension supported internally, but make exception 373 * for extension types that previously were not supported, but now are. 374 */ 375 if (SSL_extension_supported(ext_type) 376 && ext_type != TLSEXT_TYPE_signed_certificate_timestamp) 377 return 0; 378 379 /* Extension type must fit in 16 bits */ 380 if (ext_type > 0xffff) 381 return 0; 382 /* Search for duplicate */ 383 if (custom_ext_find(exts, role, ext_type, NULL)) 384 return 0; 385 tmp = OPENSSL_realloc(exts->meths, 386 (exts->meths_count + 1) * sizeof(custom_ext_method)); 387 if (tmp == NULL) 388 return 0; 389 390 exts->meths = tmp; 391 meth = exts->meths + exts->meths_count; 392 memset(meth, 0, sizeof(*meth)); 393 meth->role = role; 394 meth->context = context; 395 meth->parse_cb = parse_cb; 396 meth->add_cb = add_cb; 397 meth->free_cb = free_cb; 398 meth->ext_type = ext_type; 399 meth->add_arg = add_arg; 400 meth->parse_arg = parse_arg; 401 exts->meths_count++; 402 return 1; 403 } 404 405 static int add_old_custom_ext(SSL_CTX *ctx, ENDPOINT role, 406 unsigned int ext_type, 407 unsigned int context, 408 custom_ext_add_cb add_cb, 409 custom_ext_free_cb free_cb, 410 void *add_arg, 411 custom_ext_parse_cb parse_cb, void *parse_arg) 412 { 413 custom_ext_add_cb_wrap *add_cb_wrap 414 = OPENSSL_malloc(sizeof(*add_cb_wrap)); 415 custom_ext_parse_cb_wrap *parse_cb_wrap 416 = OPENSSL_malloc(sizeof(*parse_cb_wrap)); 417 int ret; 418 419 if (add_cb_wrap == NULL || parse_cb_wrap == NULL) { 420 OPENSSL_free(add_cb_wrap); 421 OPENSSL_free(parse_cb_wrap); 422 return 0; 423 } 424 425 add_cb_wrap->add_arg = add_arg; 426 add_cb_wrap->add_cb = add_cb; 427 add_cb_wrap->free_cb = free_cb; 428 parse_cb_wrap->parse_arg = parse_arg; 429 parse_cb_wrap->parse_cb = parse_cb; 430 431 ret = add_custom_ext_intern(ctx, role, ext_type, 432 context, 433 custom_ext_add_old_cb_wrap, 434 custom_ext_free_old_cb_wrap, 435 add_cb_wrap, 436 custom_ext_parse_old_cb_wrap, 437 parse_cb_wrap); 438 439 if (!ret) { 440 OPENSSL_free(add_cb_wrap); 441 OPENSSL_free(parse_cb_wrap); 442 } 443 444 return ret; 445 } 446 447 /* Application level functions to add the old custom extension callbacks */ 448 int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type, 449 custom_ext_add_cb add_cb, 450 custom_ext_free_cb free_cb, 451 void *add_arg, 452 custom_ext_parse_cb parse_cb, void *parse_arg) 453 { 454 return add_old_custom_ext(ctx, ENDPOINT_CLIENT, ext_type, 455 SSL_EXT_TLS1_2_AND_BELOW_ONLY 456 | SSL_EXT_CLIENT_HELLO 457 | SSL_EXT_TLS1_2_SERVER_HELLO 458 | SSL_EXT_IGNORE_ON_RESUMPTION, 459 add_cb, free_cb, add_arg, parse_cb, parse_arg); 460 } 461 462 int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type, 463 custom_ext_add_cb add_cb, 464 custom_ext_free_cb free_cb, 465 void *add_arg, 466 custom_ext_parse_cb parse_cb, void *parse_arg) 467 { 468 return add_old_custom_ext(ctx, ENDPOINT_SERVER, ext_type, 469 SSL_EXT_TLS1_2_AND_BELOW_ONLY 470 | SSL_EXT_CLIENT_HELLO 471 | SSL_EXT_TLS1_2_SERVER_HELLO 472 | SSL_EXT_IGNORE_ON_RESUMPTION, 473 add_cb, free_cb, add_arg, parse_cb, parse_arg); 474 } 475 476 int SSL_CTX_add_custom_ext(SSL_CTX *ctx, unsigned int ext_type, 477 unsigned int context, 478 SSL_custom_ext_add_cb_ex add_cb, 479 SSL_custom_ext_free_cb_ex free_cb, 480 void *add_arg, 481 SSL_custom_ext_parse_cb_ex parse_cb, void *parse_arg) 482 { 483 return add_custom_ext_intern(ctx, ENDPOINT_BOTH, ext_type, context, add_cb, 484 free_cb, add_arg, parse_cb, parse_arg); 485 } 486 487 int SSL_extension_supported(unsigned int ext_type) 488 { 489 switch (ext_type) { 490 /* Internally supported extensions. */ 491 case TLSEXT_TYPE_application_layer_protocol_negotiation: 492 case TLSEXT_TYPE_ec_point_formats: 493 case TLSEXT_TYPE_supported_groups: 494 case TLSEXT_TYPE_key_share: 495 #ifndef OPENSSL_NO_NEXTPROTONEG 496 case TLSEXT_TYPE_next_proto_neg: 497 #endif 498 case TLSEXT_TYPE_padding: 499 case TLSEXT_TYPE_renegotiate: 500 case TLSEXT_TYPE_max_fragment_length: 501 case TLSEXT_TYPE_server_name: 502 case TLSEXT_TYPE_session_ticket: 503 case TLSEXT_TYPE_signature_algorithms: 504 #ifndef OPENSSL_NO_SRP 505 case TLSEXT_TYPE_srp: 506 #endif 507 #ifndef OPENSSL_NO_OCSP 508 case TLSEXT_TYPE_status_request: 509 #endif 510 #ifndef OPENSSL_NO_CT 511 case TLSEXT_TYPE_signed_certificate_timestamp: 512 #endif 513 #ifndef OPENSSL_NO_SRTP 514 case TLSEXT_TYPE_use_srtp: 515 #endif 516 case TLSEXT_TYPE_encrypt_then_mac: 517 case TLSEXT_TYPE_supported_versions: 518 case TLSEXT_TYPE_extended_master_secret: 519 case TLSEXT_TYPE_psk_kex_modes: 520 case TLSEXT_TYPE_cookie: 521 case TLSEXT_TYPE_early_data: 522 case TLSEXT_TYPE_certificate_authorities: 523 case TLSEXT_TYPE_psk: 524 case TLSEXT_TYPE_post_handshake_auth: 525 return 1; 526 default: 527 return 0; 528 } 529 } 530