2 * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
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
11 #include "../ssl_locl.h"
12 #include "statem_locl.h"
15 /* The ID for the extension */
18 * Initialise extension before parsing. Always called even if extension not
21 int (*init_ext)(SSL *s, unsigned int context);
22 /* Parse extension received by server from client */
23 int (*parse_client_ext)(SSL *s, PACKET *pkt, int *al);
24 /* Parse extension received by client from server */
25 int (*parse_server_ext)(SSL *s, PACKET *pkt, int *al);
26 /* Construct extension sent by server */
27 int (*construct_server_ext)(SSL *s, WPACKET *pkt, int *al);
28 /* Construct extension sent by client */
29 int (*construct_client_ext)(SSL *s, WPACKET *pkt, int *al);
31 * Finalise extension after parsing. Always called even if extension not
34 int (*finalise_ext)(SSL *s, unsigned int context);
36 } EXTENSION_DEFINITION;
39 * TODO(TLS1.3): Temporarily modified the definitions below to put all TLS1.3
40 * extensions in the ServerHello for now. That needs to be put back to correct
41 * setting once encrypted extensions is working properly.
43 static const EXTENSION_DEFINITION ext_defs[] = {
45 TLSEXT_TYPE_renegotiate,
47 tls_parse_client_renegotiate,
48 tls_parse_server_renegotiate,
49 tls_construct_server_renegotiate,
50 tls_construct_client_renegotiate,
52 EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_SSL3_ALLOWED
53 | EXT_TLS1_2_AND_BELOW_ONLY
56 TLSEXT_TYPE_server_name,
58 tls_parse_client_server_name,
59 tls_parse_server_server_name,
60 tls_construct_server_server_name,
61 tls_construct_client_server_name,
63 EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO
64 | EXT_TLS1_3_ENCRYPTED_EXTENSIONS
66 #ifndef OPENSSL_NO_SRP
73 tls_construct_client_srp,
75 EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY
80 TLSEXT_TYPE_ec_point_formats,
82 tls_parse_client_ec_pt_formats,
83 tls_parse_server_ec_pt_formats,
84 tls_construct_server_ec_pt_formats,
85 tls_construct_client_ec_pt_formats,
87 EXT_CLIENT_HELLO | EXT_TLS1_2_AND_BELOW_ONLY
90 TLSEXT_TYPE_supported_groups,
92 tls_parse_client_supported_groups,
94 NULL /* TODO(TLS1.3): Need to add this */,
95 tls_construct_client_supported_groups,
97 EXT_CLIENT_HELLO | EXT_TLS1_3_ENCRYPTED_EXTENSIONS
101 TLSEXT_TYPE_session_ticket,
103 tls_parse_client_session_ticket,
104 tls_parse_server_session_ticket,
105 tls_construct_server_session_ticket,
106 tls_construct_client_session_ticket,
108 EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY
111 TLSEXT_TYPE_signature_algorithms,
113 tls_parse_client_sig_algs,
116 tls_construct_client_sig_algs,
120 #ifndef OPENSSL_NO_OCSP
122 TLSEXT_TYPE_status_request,
124 tls_parse_client_status_request,
125 tls_parse_server_status_request,
126 tls_construct_server_status_request,
127 tls_construct_client_status_request,
129 EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO
130 | EXT_TLS1_3_CERTIFICATE
133 #ifndef OPENSSL_NO_NEXTPROTONEG
135 TLSEXT_TYPE_next_proto_neg,
137 tls_parse_client_npn,
138 tls_parse_server_npn,
139 tls_construct_server_next_proto_neg,
140 tls_construct_client_npn,
142 EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY
146 TLSEXT_TYPE_application_layer_protocol_negotiation,
148 tls_parse_client_alpn,
149 tls_parse_server_alpn,
150 tls_construct_server_alpn,
151 tls_construct_client_alpn,
153 EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO
154 | EXT_TLS1_3_ENCRYPTED_EXTENSIONS
156 #ifndef OPENSSL_NO_SRTP
158 TLSEXT_TYPE_use_srtp,
160 tls_parse_client_use_srtp,
161 tls_parse_server_use_srtp,
162 tls_construct_server_use_srtp,
163 tls_construct_client_use_srtp,
165 EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO
166 | EXT_TLS1_3_ENCRYPTED_EXTENSIONS | EXT_DTLS_ONLY
170 TLSEXT_TYPE_encrypt_then_mac,
172 tls_parse_client_etm,
173 tls_parse_server_etm,
174 tls_construct_server_etm,
175 tls_construct_client_etm,
177 EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY
179 #ifndef OPENSSL_NO_CT
181 TLSEXT_TYPE_signed_certificate_timestamp,
184 * No server side support for this, but can be provided by a custom
185 * extension. This is an exception to the rule that custom extensions
186 * cannot override built in ones.
189 tls_parse_server_sct,
191 tls_construct_client_sct,
193 EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO
194 | EXT_TLS1_3_CERTIFICATE
198 TLSEXT_TYPE_extended_master_secret,
200 tls_parse_client_ems,
201 tls_parse_server_ems,
202 tls_construct_server_ems,
203 tls_construct_client_ems,
205 EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY
208 TLSEXT_TYPE_supported_versions,
210 /* Processed inline as part of version selection */
214 tls_construct_client_supported_versions,
216 EXT_CLIENT_HELLO | EXT_TLS_IMPLEMENTATION_ONLY | EXT_TLS1_3_ONLY
219 TLSEXT_TYPE_key_share,
221 tls_parse_client_key_share,
222 tls_parse_server_key_share,
223 tls_construct_server_key_share,
224 tls_construct_client_key_share,
226 EXT_CLIENT_HELLO | EXT_TLS1_3_SERVER_HELLO
227 | EXT_TLS1_3_HELLO_RETRY_REQUEST | EXT_TLS_IMPLEMENTATION_ONLY
232 * Special unsolicited ServerHello extension only used when
233 * SSL_OP_CRYPTOPRO_TLSEXT_BUG is set
235 TLSEXT_TYPE_cryptopro_bug,
239 tls_construct_server_cryptopro_bug,
242 EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY
245 /* Last in the list because it must be added as the last extension */
248 /* We send this, but don't read it */
252 tls_construct_client_padding,
259 * Comparison function used in a call to qsort (see tls_collect_extensions()
261 * The two arguments |p1| and |p2| are expected to be pointers to RAW_EXTENSIONs
264 * 1 if the type for p1 is greater than p2
265 * 0 if the type for p1 and p2 are the same
266 * -1 if the type for p1 is less than p2
268 static int compare_extensions(const void *p1, const void *p2)
270 const RAW_EXTENSION *e1 = (const RAW_EXTENSION *)p1;
271 const RAW_EXTENSION *e2 = (const RAW_EXTENSION *)p2;
273 if (e1->type < e2->type)
275 else if (e1->type > e2->type)
282 * Verify whether we are allowed to use the extension |type| in the current
283 * |context|. Returns 1 to indicate the extension is allowed or unknown or 0 to
284 * indicate the extension is not allowed.
286 static int verify_extension(SSL *s, unsigned int context, unsigned int type)
290 for (i = 0; i < OSSL_NELEM(ext_defs); i++) {
291 if (type == ext_defs[i].type) {
292 /* Check we're allowed to use this extension in this context */
293 if ((context & ext_defs[i].context) == 0)
296 if (SSL_IS_DTLS(s)) {
297 if ((ext_defs[i].context & EXT_TLS_ONLY) != 0)
299 } else if ((ext_defs[i].context & EXT_DTLS_ONLY) != 0) {
307 /* Unknown extension. We allow it */
312 * Finds an extension definition for the give extension |type|.
313 * Returns 1 if found and stores the definition in |*def|, or returns 0
316 static int find_extension_definition(SSL *s, unsigned int type,
317 const EXTENSION_DEFINITION **def)
321 for (i = 0; i < OSSL_NELEM(ext_defs); i++) {
322 if (type == ext_defs[i].type) {
328 /* Unknown extension */
333 * Gather a list of all the extensions from the data in |packet]. |context|
334 * tells us which message this extension is for. Ttls_parse_server_ec_pt_formatshe raw extension data is
335 * stored in |*res| with the number of found extensions in |*numfound|. In the
336 * event of an error the alert type to use is stored in |*ad|. We don't actually
337 * process the content of the extensions yet, except to check their types.
339 * Per http://tools.ietf.org/html/rfc5246#section-7.4.1.4, there may not be
340 * more than one extension of the same type in a ClientHello or ServerHello.
341 * This function returns 1 if all extensions are unique and we have parsed their
342 * types, and 0 if the extensions contain duplicates, could not be successfully
343 * parsed, or an internal error occurred.
346 int tls_collect_extensions(SSL *s, PACKET *packet, unsigned int context,
347 RAW_EXTENSION **res, size_t *numfound, int *ad)
349 PACKET extensions = *packet;
350 size_t num_extensions = 0, i = 0;
351 RAW_EXTENSION *raw_extensions = NULL;
353 /* First pass: count the extensions. */
354 while (PACKET_remaining(&extensions) > 0) {
358 if (!PACKET_get_net_2(&extensions, &type) ||
359 !PACKET_get_length_prefixed_2(&extensions, &extension)) {
360 SSLerr(SSL_F_TLS_COLLECT_EXTENSIONS, SSL_R_BAD_EXTENSION);
361 *ad = SSL_AD_DECODE_ERROR;
364 /* Verify this extension is allowed */
365 if (!verify_extension(s, context, type)) {
366 SSLerr(SSL_F_TLS_COLLECT_EXTENSIONS, SSL_R_BAD_EXTENSION);
367 *ad = SSL_AD_ILLEGAL_PARAMETER;
373 if (num_extensions > 0) {
374 raw_extensions = OPENSSL_zalloc(sizeof(*raw_extensions)
376 if (raw_extensions == NULL) {
377 *ad = SSL_AD_INTERNAL_ERROR;
378 SSLerr(SSL_F_TLS_COLLECT_EXTENSIONS, ERR_R_MALLOC_FAILURE);
382 /* Second pass: collect the extensions. */
383 for (i = 0; i < num_extensions; i++) {
384 if (!PACKET_get_net_2(packet, &raw_extensions[i].type) ||
385 !PACKET_get_length_prefixed_2(packet,
386 &raw_extensions[i].data)) {
387 /* This should not happen. */
388 *ad = SSL_AD_INTERNAL_ERROR;
389 SSLerr(SSL_F_TLS_COLLECT_EXTENSIONS, ERR_R_INTERNAL_ERROR);
394 if (PACKET_remaining(packet) != 0) {
395 *ad = SSL_AD_DECODE_ERROR;
396 SSLerr(SSL_F_TLS_COLLECT_EXTENSIONS, SSL_R_LENGTH_MISMATCH);
399 /* Sort the extensions and make sure there are no duplicates. */
400 qsort(raw_extensions, num_extensions, sizeof(*raw_extensions),
402 for (i = 1; i < num_extensions; i++) {
403 if (raw_extensions[i - 1].type == raw_extensions[i].type) {
404 *ad = SSL_AD_DECODE_ERROR;
411 * Initialise all known extensions relevant to this context, whether we have
414 for (i = 0; i < OSSL_NELEM(ext_defs); i++) {
415 if(ext_defs[i].init_ext != NULL && (ext_defs[i].context & context) != 0
416 && !ext_defs[i].init_ext(s, context)) {
417 *ad = SSL_AD_INTERNAL_ERROR;
422 *res = raw_extensions;
423 *numfound = num_extensions;
427 OPENSSL_free(raw_extensions);
432 * Parse all remaining extensions that have not yet been parsed. Also calls the
433 * finalisation for all extensions at the end. Returns 1 for success or 0 for
434 * failure. On failure, |*al| is populated with a suitable alert code.
436 int tls_parse_all_extensions(SSL *s, int context, RAW_EXTENSION *exts,
437 size_t numexts, int *al)
441 for (loop = 0; loop < numexts; loop++) {
442 RAW_EXTENSION *currext = &exts[loop];
443 const EXTENSION_DEFINITION *extdef = NULL;
444 int (*parser)(SSL *s, PACKET *pkt, int *al) = NULL;
446 if (s->tlsext_debug_cb)
447 s->tlsext_debug_cb(s, !s->server, currext->type,
448 PACKET_data(&currext->data),
449 PACKET_remaining(&currext->data),
450 s->tlsext_debug_arg);
452 /* Skip if we've already parsed this extension */
459 if (find_extension_definition(s, currext->type, &extdef)) {
460 parser = s->server ? extdef->parse_client_ext
461 : extdef->parse_server_ext;
463 /* Check if extension is defined for our protocol. If not, skip */
465 && (extdef->context & EXT_TLS_IMPLEMENTATION_ONLY) != 0)
466 || (s->version == SSL3_VERSION
467 && (extdef->context & EXT_SSL3_ALLOWED) == 0)
469 && (extdef->context & EXT_TLS1_2_AND_BELOW_ONLY) != 0)
471 && (extdef->context & EXT_TLS1_3_ONLY) != 0))
475 if (parser == NULL) {
477 * Could be a custom extension. We only allow this if it is a non
478 * resumed session on the server side.
480 * TODO(TLS1.3): We only allow old style <=TLS1.2 custom extensions.
481 * We're going to need a new mechanism for TLS1.3 to specify which
482 * messages to add the custom extensions to.
484 if ((!s->hit || !s->server)
486 & (EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO)) != 0
487 && custom_ext_parse(s, s->server, currext->type,
488 PACKET_data(&currext->data),
489 PACKET_remaining(&currext->data),
496 if (!parser(s, &currext->data, al))
501 * Finalise all known extensions relevant to this context, whether we have
504 for (loop = 0; loop < OSSL_NELEM(ext_defs); loop++) {
505 if(ext_defs[loop].finalise_ext != NULL
506 && (ext_defs[loop].context & context) != 0
507 && !ext_defs[loop].finalise_ext(s, context)) {
508 *al = SSL_AD_INTERNAL_ERROR;
517 * Find a specific extension by |type| in the list |exts| containing |numexts|
518 * extensions, and the parse it immediately. Returns 1 on success, or 0 on
519 * failure. If a failure has occurred then |*al| will also be set to the alert
522 int tls_parse_extension(SSL *s, int type, int context, RAW_EXTENSION *exts,
523 size_t numexts, int *al)
525 RAW_EXTENSION *ext = tls_get_extension_by_type(exts, numexts, type);
530 return tls_parse_all_extensions(s, context, ext, 1, al);
533 int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,
538 int min_version, max_version = 0, reason;
541 * Normally if something goes wrong during construction its an internal
542 * error. We can always override this later.
544 *al = SSL_AD_INTERNAL_ERROR;
546 if (!WPACKET_start_sub_packet_u16(pkt)
548 * If extensions are of zero length then we don't even add the
549 * extensions length bytes to a ClientHello/ServerHello in SSLv3
551 || ((context & (EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO)) != 0
552 && s->version == SSL3_VERSION
553 && !WPACKET_set_flags(pkt,
554 WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH))) {
555 SSLerr(SSL_F_TLS_CONSTRUCT_EXTENSIONS, ERR_R_INTERNAL_ERROR);
559 if ((context & EXT_CLIENT_HELLO) != 0) {
560 reason = ssl_get_client_min_max_version(s, &min_version, &max_version);
562 SSLerr(SSL_F_TLS_CONSTRUCT_EXTENSIONS, reason);
567 /* Add custom extensions first */
568 if ((context & EXT_CLIENT_HELLO) != 0) {
569 custom_ext_init(&s->cert->cli_ext);
571 } else if ((context & EXT_TLS1_2_SERVER_HELLO) != 0) {
573 * We already initialised the custom extensions during ClientHello
576 * TODO(TLS1.3): We're going to need a new custom extension mechanism
577 * for TLS1.3, so that custom extensions can specify which of the
578 * multiple message they wish to add themselves to.
583 if (addcustom && !custom_ext_add(s, s->server, pkt, al)) {
584 SSLerr(SSL_F_TLS_CONSTRUCT_EXTENSIONS, ERR_R_INTERNAL_ERROR);
588 for (loop = 0; loop < OSSL_NELEM(ext_defs); loop++) {
589 int (*construct)(SSL *s, WPACKET *pkt, int *al);
591 /* Skip if not relevant for our context */
592 if ((ext_defs[loop].context & context) == 0)
595 construct = s->server ? ext_defs[loop].construct_server_ext
596 : ext_defs[loop].construct_client_ext;
598 /* Check if this extension is defined for our protocol. If not, skip */
600 && (ext_defs[loop].context & EXT_TLS_IMPLEMENTATION_ONLY)
602 || (s->version == SSL3_VERSION
603 && (ext_defs[loop].context & EXT_SSL3_ALLOWED) == 0)
605 && (ext_defs[loop].context & EXT_TLS1_2_AND_BELOW_ONLY)
608 && (ext_defs[loop].context & EXT_TLS1_3_ONLY) != 0
609 && (context & EXT_CLIENT_HELLO) == 0)
610 || ((ext_defs[loop].context & EXT_TLS1_3_ONLY) != 0
611 && (context & EXT_CLIENT_HELLO) != 0
612 && (SSL_IS_DTLS(s) || max_version < TLS1_3_VERSION))
613 || construct == NULL)
616 if (!construct(s, pkt, al))
620 if (!WPACKET_close(pkt)) {
621 SSLerr(SSL_F_TLS_CONSTRUCT_EXTENSIONS, ERR_R_INTERNAL_ERROR);