1 /* 2 * Copyright 2014-2021 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the OpenSSL license (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_F_CUSTOM_EXT_PARSE, 143 SSL_R_BAD_EXTENSION); 144 return 0; 145 } 146 } 147 148 /* 149 * Extensions received in the ClientHello or CertificateRequest are marked 150 * with the SSL_EXT_FLAG_RECEIVED. This is so we know to add the equivalent 151 * extensions in the response messages 152 */ 153 if ((context & (SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_CERTIFICATE_REQUEST)) 154 != 0) 155 meth->ext_flags |= SSL_EXT_FLAG_RECEIVED; 156 157 /* If no parse function set return success */ 158 if (!meth->parse_cb) 159 return 1; 160 161 if (meth->parse_cb(s, ext_type, context, ext_data, ext_size, x, chainidx, 162 &al, meth->parse_arg) <= 0) { 163 SSLfatal(s, al, SSL_F_CUSTOM_EXT_PARSE, SSL_R_BAD_EXTENSION); 164 return 0; 165 } 166 167 return 1; 168 } 169 170 /* 171 * Request custom extension data from the application and add to the return 172 * buffer. 173 */ 174 int custom_ext_add(SSL *s, int context, WPACKET *pkt, X509 *x, size_t chainidx, 175 int maxversion) 176 { 177 custom_ext_methods *exts = &s->cert->custext; 178 custom_ext_method *meth; 179 size_t i; 180 int al; 181 182 for (i = 0; i < exts->meths_count; i++) { 183 const unsigned char *out = NULL; 184 size_t outlen = 0; 185 186 meth = exts->meths + i; 187 188 if (!should_add_extension(s, meth->context, context, maxversion)) 189 continue; 190 191 if ((context & (SSL_EXT_TLS1_2_SERVER_HELLO 192 | SSL_EXT_TLS1_3_SERVER_HELLO 193 | SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS 194 | SSL_EXT_TLS1_3_CERTIFICATE 195 | SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST)) != 0) { 196 /* Only send extensions present in ClientHello/CertificateRequest */ 197 if (!(meth->ext_flags & SSL_EXT_FLAG_RECEIVED)) 198 continue; 199 } 200 /* 201 * We skip it if the callback is absent - except for a ClientHello where 202 * we add an empty extension. 203 */ 204 if ((context & SSL_EXT_CLIENT_HELLO) == 0 && meth->add_cb == NULL) 205 continue; 206 207 if (meth->add_cb != NULL) { 208 int cb_retval = meth->add_cb(s, meth->ext_type, context, &out, 209 &outlen, x, chainidx, &al, 210 meth->add_arg); 211 212 if (cb_retval < 0) { 213 SSLfatal(s, al, SSL_F_CUSTOM_EXT_ADD, SSL_R_CALLBACK_FAILED); 214 return 0; /* error */ 215 } 216 if (cb_retval == 0) 217 continue; /* skip this extension */ 218 } 219 220 if (!WPACKET_put_bytes_u16(pkt, meth->ext_type) 221 || !WPACKET_start_sub_packet_u16(pkt) 222 || (outlen > 0 && !WPACKET_memcpy(pkt, out, outlen)) 223 || !WPACKET_close(pkt)) { 224 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_CUSTOM_EXT_ADD, 225 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 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_CUSTOM_EXT_ADD, 234 ERR_R_INTERNAL_ERROR); 235 return 0; 236 } 237 /* 238 * Indicate extension has been sent: this is both a sanity check to 239 * ensure we don't send duplicate extensions and indicates that it 240 * is not an error if the extension is present in ServerHello. 241 */ 242 meth->ext_flags |= SSL_EXT_FLAG_SENT; 243 } 244 if (meth->free_cb != NULL) 245 meth->free_cb(s, meth->ext_type, context, out, meth->add_arg); 246 } 247 return 1; 248 } 249 250 /* Copy the flags from src to dst for any extensions that exist in both */ 251 int custom_exts_copy_flags(custom_ext_methods *dst, 252 const custom_ext_methods *src) 253 { 254 size_t i; 255 custom_ext_method *methsrc = src->meths; 256 257 for (i = 0; i < src->meths_count; i++, methsrc++) { 258 custom_ext_method *methdst = custom_ext_find(dst, methsrc->role, 259 methsrc->ext_type, NULL); 260 261 if (methdst == NULL) 262 continue; 263 264 methdst->ext_flags = methsrc->ext_flags; 265 } 266 267 return 1; 268 } 269 270 /* Copy table of custom extensions */ 271 int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src) 272 { 273 size_t i; 274 int err = 0; 275 276 if (src->meths_count > 0) { 277 dst->meths = 278 OPENSSL_memdup(src->meths, 279 sizeof(*src->meths) * src->meths_count); 280 if (dst->meths == NULL) 281 return 0; 282 dst->meths_count = src->meths_count; 283 284 for (i = 0; i < src->meths_count; i++) { 285 custom_ext_method *methsrc = src->meths + i; 286 custom_ext_method *methdst = dst->meths + i; 287 288 if (methsrc->add_cb != custom_ext_add_old_cb_wrap) 289 continue; 290 291 /* 292 * We have found an old style API wrapper. We need to copy the 293 * arguments too. 294 */ 295 296 if (err) { 297 methdst->add_arg = NULL; 298 methdst->parse_arg = NULL; 299 continue; 300 } 301 302 methdst->add_arg = OPENSSL_memdup(methsrc->add_arg, 303 sizeof(custom_ext_add_cb_wrap)); 304 methdst->parse_arg = OPENSSL_memdup(methsrc->parse_arg, 305 sizeof(custom_ext_parse_cb_wrap)); 306 307 if (methdst->add_arg == NULL || methdst->parse_arg == NULL) 308 err = 1; 309 } 310 } 311 312 if (err) { 313 custom_exts_free(dst); 314 return 0; 315 } 316 317 return 1; 318 } 319 320 void custom_exts_free(custom_ext_methods *exts) 321 { 322 size_t i; 323 custom_ext_method *meth; 324 325 for (i = 0, meth = exts->meths; i < exts->meths_count; i++, meth++) { 326 if (meth->add_cb != custom_ext_add_old_cb_wrap) 327 continue; 328 329 /* Old style API wrapper. Need to free the arguments too */ 330 OPENSSL_free(meth->add_arg); 331 OPENSSL_free(meth->parse_arg); 332 } 333 OPENSSL_free(exts->meths); 334 } 335 336 /* Return true if a client custom extension exists, false otherwise */ 337 int SSL_CTX_has_client_custom_ext(const SSL_CTX *ctx, unsigned int ext_type) 338 { 339 return custom_ext_find(&ctx->cert->custext, ENDPOINT_CLIENT, ext_type, 340 NULL) != NULL; 341 } 342 343 static int add_custom_ext_intern(SSL_CTX *ctx, ENDPOINT role, 344 unsigned int ext_type, 345 unsigned int context, 346 SSL_custom_ext_add_cb_ex add_cb, 347 SSL_custom_ext_free_cb_ex free_cb, 348 void *add_arg, 349 SSL_custom_ext_parse_cb_ex parse_cb, 350 void *parse_arg) 351 { 352 custom_ext_methods *exts = &ctx->cert->custext; 353 custom_ext_method *meth, *tmp; 354 355 /* 356 * Check application error: if add_cb is not set free_cb will never be 357 * called. 358 */ 359 if (add_cb == NULL && free_cb != NULL) 360 return 0; 361 362 #ifndef OPENSSL_NO_CT 363 /* 364 * We don't want applications registering callbacks for SCT extensions 365 * whilst simultaneously using the built-in SCT validation features, as 366 * these two things may not play well together. 367 */ 368 if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp 369 && (context & SSL_EXT_CLIENT_HELLO) != 0 370 && SSL_CTX_ct_is_enabled(ctx)) 371 return 0; 372 #endif 373 374 /* 375 * Don't add if extension supported internally, but make exception 376 * for extension types that previously were not supported, but now are. 377 */ 378 if (SSL_extension_supported(ext_type) 379 && ext_type != TLSEXT_TYPE_signed_certificate_timestamp) 380 return 0; 381 382 /* Extension type must fit in 16 bits */ 383 if (ext_type > 0xffff) 384 return 0; 385 /* Search for duplicate */ 386 if (custom_ext_find(exts, role, ext_type, NULL)) 387 return 0; 388 tmp = OPENSSL_realloc(exts->meths, 389 (exts->meths_count + 1) * sizeof(custom_ext_method)); 390 if (tmp == NULL) 391 return 0; 392 393 exts->meths = tmp; 394 meth = exts->meths + exts->meths_count; 395 memset(meth, 0, sizeof(*meth)); 396 meth->role = role; 397 meth->context = context; 398 meth->parse_cb = parse_cb; 399 meth->add_cb = add_cb; 400 meth->free_cb = free_cb; 401 meth->ext_type = ext_type; 402 meth->add_arg = add_arg; 403 meth->parse_arg = parse_arg; 404 exts->meths_count++; 405 return 1; 406 } 407 408 static int add_old_custom_ext(SSL_CTX *ctx, ENDPOINT role, 409 unsigned int ext_type, 410 unsigned int context, 411 custom_ext_add_cb add_cb, 412 custom_ext_free_cb free_cb, 413 void *add_arg, 414 custom_ext_parse_cb parse_cb, void *parse_arg) 415 { 416 custom_ext_add_cb_wrap *add_cb_wrap 417 = OPENSSL_malloc(sizeof(*add_cb_wrap)); 418 custom_ext_parse_cb_wrap *parse_cb_wrap 419 = OPENSSL_malloc(sizeof(*parse_cb_wrap)); 420 int ret; 421 422 if (add_cb_wrap == NULL || parse_cb_wrap == NULL) { 423 OPENSSL_free(add_cb_wrap); 424 OPENSSL_free(parse_cb_wrap); 425 return 0; 426 } 427 428 add_cb_wrap->add_arg = add_arg; 429 add_cb_wrap->add_cb = add_cb; 430 add_cb_wrap->free_cb = free_cb; 431 parse_cb_wrap->parse_arg = parse_arg; 432 parse_cb_wrap->parse_cb = parse_cb; 433 434 ret = add_custom_ext_intern(ctx, role, ext_type, 435 context, 436 custom_ext_add_old_cb_wrap, 437 custom_ext_free_old_cb_wrap, 438 add_cb_wrap, 439 custom_ext_parse_old_cb_wrap, 440 parse_cb_wrap); 441 442 if (!ret) { 443 OPENSSL_free(add_cb_wrap); 444 OPENSSL_free(parse_cb_wrap); 445 } 446 447 return ret; 448 } 449 450 /* Application level functions to add the old custom extension callbacks */ 451 int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type, 452 custom_ext_add_cb add_cb, 453 custom_ext_free_cb free_cb, 454 void *add_arg, 455 custom_ext_parse_cb parse_cb, void *parse_arg) 456 { 457 return add_old_custom_ext(ctx, ENDPOINT_CLIENT, ext_type, 458 SSL_EXT_TLS1_2_AND_BELOW_ONLY 459 | SSL_EXT_CLIENT_HELLO 460 | SSL_EXT_TLS1_2_SERVER_HELLO 461 | SSL_EXT_IGNORE_ON_RESUMPTION, 462 add_cb, free_cb, add_arg, parse_cb, parse_arg); 463 } 464 465 int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type, 466 custom_ext_add_cb add_cb, 467 custom_ext_free_cb free_cb, 468 void *add_arg, 469 custom_ext_parse_cb parse_cb, void *parse_arg) 470 { 471 return add_old_custom_ext(ctx, ENDPOINT_SERVER, ext_type, 472 SSL_EXT_TLS1_2_AND_BELOW_ONLY 473 | SSL_EXT_CLIENT_HELLO 474 | SSL_EXT_TLS1_2_SERVER_HELLO 475 | SSL_EXT_IGNORE_ON_RESUMPTION, 476 add_cb, free_cb, add_arg, parse_cb, parse_arg); 477 } 478 479 int SSL_CTX_add_custom_ext(SSL_CTX *ctx, unsigned int ext_type, 480 unsigned int context, 481 SSL_custom_ext_add_cb_ex add_cb, 482 SSL_custom_ext_free_cb_ex free_cb, 483 void *add_arg, 484 SSL_custom_ext_parse_cb_ex parse_cb, void *parse_arg) 485 { 486 return add_custom_ext_intern(ctx, ENDPOINT_BOTH, ext_type, context, add_cb, 487 free_cb, add_arg, parse_cb, parse_arg); 488 } 489 490 int SSL_extension_supported(unsigned int ext_type) 491 { 492 switch (ext_type) { 493 /* Internally supported extensions. */ 494 case TLSEXT_TYPE_application_layer_protocol_negotiation: 495 #ifndef OPENSSL_NO_EC 496 case TLSEXT_TYPE_ec_point_formats: 497 case TLSEXT_TYPE_supported_groups: 498 case TLSEXT_TYPE_key_share: 499 #endif 500 #ifndef OPENSSL_NO_NEXTPROTONEG 501 case TLSEXT_TYPE_next_proto_neg: 502 #endif 503 case TLSEXT_TYPE_padding: 504 case TLSEXT_TYPE_renegotiate: 505 case TLSEXT_TYPE_max_fragment_length: 506 case TLSEXT_TYPE_server_name: 507 case TLSEXT_TYPE_session_ticket: 508 case TLSEXT_TYPE_signature_algorithms: 509 #ifndef OPENSSL_NO_SRP 510 case TLSEXT_TYPE_srp: 511 #endif 512 #ifndef OPENSSL_NO_OCSP 513 case TLSEXT_TYPE_status_request: 514 #endif 515 #ifndef OPENSSL_NO_CT 516 case TLSEXT_TYPE_signed_certificate_timestamp: 517 #endif 518 #ifndef OPENSSL_NO_SRTP 519 case TLSEXT_TYPE_use_srtp: 520 #endif 521 case TLSEXT_TYPE_encrypt_then_mac: 522 case TLSEXT_TYPE_supported_versions: 523 case TLSEXT_TYPE_extended_master_secret: 524 case TLSEXT_TYPE_psk_kex_modes: 525 case TLSEXT_TYPE_cookie: 526 case TLSEXT_TYPE_early_data: 527 case TLSEXT_TYPE_certificate_authorities: 528 case TLSEXT_TYPE_psk: 529 case TLSEXT_TYPE_post_handshake_auth: 530 return 1; 531 default: 532 return 0; 533 } 534 } 535
Indexes created Sat Feb 28 05:31:39 UTC 2026