1 /*
2 * Copyright 2014-2023 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 /* 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 */
custom_ext_add_old_cb_wrap(SSL * s,unsigned int ext_type,unsigned int context,const unsigned char ** out,size_t * outlen,X509 * x,size_t chainidx,int * al,void * add_arg)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
custom_ext_free_old_cb_wrap(SSL * s,unsigned int ext_type,unsigned int context,const unsigned char * out,void * add_arg)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
custom_ext_parse_old_cb_wrap(SSL * s,unsigned int ext_type,unsigned int context,const unsigned char * in,size_t inlen,X509 * x,size_t chainidx,int * al,void * parse_arg)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 */
custom_ext_find(const custom_ext_methods * exts,ENDPOINT role,unsigned int ext_type,size_t * idx)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 */
custom_ext_init(custom_ext_methods * exts)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. */
custom_ext_parse(SSL_CONNECTION * s,unsigned int context,unsigned int ext_type,const unsigned char * ext_data,size_t ext_size,X509 * x,size_t chainidx)113 int custom_ext_parse(SSL_CONNECTION *s, unsigned int context,
114 unsigned int ext_type,
115 const unsigned char *ext_data, size_t ext_size, X509 *x,
116 size_t chainidx)
117 {
118 int al = 0;
119 custom_ext_methods *exts = &s->cert->custext;
120 custom_ext_method *meth;
121 ENDPOINT role = ENDPOINT_BOTH;
122
123 if ((context & (SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO)) != 0)
124 role = s->server ? ENDPOINT_SERVER : ENDPOINT_CLIENT;
125
126 meth = custom_ext_find(exts, role, ext_type, NULL);
127 /* If not found return success */
128 if (!meth)
129 return 1;
130
131 /* Check if extension is defined for our protocol. If not, skip */
132 if (!extension_is_relevant(s, meth->context, context))
133 return 1;
134
135 if ((context & (SSL_EXT_TLS1_2_SERVER_HELLO
136 | SSL_EXT_TLS1_3_SERVER_HELLO
137 | SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS)) != 0) {
138 /*
139 * If it's ServerHello or EncryptedExtensions we can't have any
140 * extensions not sent in ClientHello.
141 */
142 if ((meth->ext_flags & SSL_EXT_FLAG_SENT) == 0) {
143 SSLfatal(s, TLS1_AD_UNSUPPORTED_EXTENSION, 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 == NULL)
159 return 1;
160
161 if (meth->parse_cb(SSL_CONNECTION_GET_USER_SSL(s), ext_type, context, ext_data,
162 ext_size, x, chainidx, &al, meth->parse_arg) <= 0) {
163 SSLfatal(s, al, 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 */
custom_ext_add(SSL_CONNECTION * s,int context,WPACKET * pkt,X509 * x,size_t chainidx,int maxversion)174 int custom_ext_add(SSL_CONNECTION *s, int context, WPACKET *pkt, X509 *x,
175 size_t chainidx, int maxversion)
176 {
177 custom_ext_methods *exts = &s->cert->custext;
178 custom_ext_method *meth;
179 size_t i;
180 int al;
181 int for_comp = (context & SSL_EXT_TLS1_3_CERTIFICATE_COMPRESSION) != 0;
182
183 for (i = 0; i < exts->meths_count; i++) {
184 const unsigned char *out = NULL;
185 size_t outlen = 0;
186
187 meth = exts->meths + i;
188
189 if (!should_add_extension(s, meth->context, context, maxversion))
190 continue;
191
192 if ((context & (SSL_EXT_TLS1_2_SERVER_HELLO
193 | SSL_EXT_TLS1_3_SERVER_HELLO
194 | SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS
195 | SSL_EXT_TLS1_3_CERTIFICATE
196 | SSL_EXT_TLS1_3_RAW_PUBLIC_KEY
197 | SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST)) != 0) {
198 /* Only send extensions present in ClientHello/CertificateRequest */
199 if (!(meth->ext_flags & SSL_EXT_FLAG_RECEIVED))
200 continue;
201 }
202 /*
203 * We skip it if the callback is absent - except for a ClientHello where
204 * we add an empty extension.
205 */
206 if ((context & SSL_EXT_CLIENT_HELLO) == 0 && meth->add_cb == NULL)
207 continue;
208
209 if (meth->add_cb != NULL) {
210 int cb_retval = meth->add_cb(SSL_CONNECTION_GET_USER_SSL(s),
211 meth->ext_type, context, &out,
212 &outlen, x, chainidx, &al,
213 meth->add_arg);
214
215 if (cb_retval < 0) {
216 if (!for_comp)
217 SSLfatal(s, al, SSL_R_CALLBACK_FAILED);
218 return 0; /* error */
219 }
220 if (cb_retval == 0)
221 continue; /* skip this extension */
222 }
223
224 if (!WPACKET_put_bytes_u16(pkt, meth->ext_type)
225 || !WPACKET_start_sub_packet_u16(pkt)
226 || (outlen > 0 && !WPACKET_memcpy(pkt, out, outlen))
227 || !WPACKET_close(pkt)) {
228 if (meth->free_cb != NULL)
229 meth->free_cb(SSL_CONNECTION_GET_USER_SSL(s), meth->ext_type,
230 context, out, meth->add_arg);
231 if (!for_comp)
232 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
233 return 0;
234 }
235 if ((context & SSL_EXT_CLIENT_HELLO) != 0) {
236 /*
237 * We can't send duplicates: code logic should prevent this.
238 */
239 if (!ossl_assert((meth->ext_flags & SSL_EXT_FLAG_SENT) == 0)) {
240 if (meth->free_cb != NULL)
241 meth->free_cb(SSL_CONNECTION_GET_USER_SSL(s), meth->ext_type,
242 context, out, meth->add_arg);
243 if (!for_comp)
244 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
245 return 0;
246 }
247 /*
248 * Indicate extension has been sent: this is both a sanity check to
249 * ensure we don't send duplicate extensions and indicates that it
250 * is not an error if the extension is present in ServerHello.
251 */
252 meth->ext_flags |= SSL_EXT_FLAG_SENT;
253 }
254 if (meth->free_cb != NULL)
255 meth->free_cb(SSL_CONNECTION_GET_USER_SSL(s), meth->ext_type,
256 context, out, meth->add_arg);
257 }
258 return 1;
259 }
260
261 /* Copy the flags from src to dst for any extensions that exist in both */
custom_exts_copy_flags(custom_ext_methods * dst,const custom_ext_methods * src)262 int custom_exts_copy_flags(custom_ext_methods *dst,
263 const custom_ext_methods *src)
264 {
265 size_t i;
266 custom_ext_method *methsrc = src->meths;
267
268 for (i = 0; i < src->meths_count; i++, methsrc++) {
269 custom_ext_method *methdst = custom_ext_find(dst, methsrc->role,
270 methsrc->ext_type, NULL);
271
272 if (methdst == NULL)
273 continue;
274
275 methdst->ext_flags = methsrc->ext_flags;
276 }
277
278 return 1;
279 }
280
281 /* Copy table of custom extensions */
custom_exts_copy(custom_ext_methods * dst,const custom_ext_methods * src)282 int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src)
283 {
284 size_t i;
285 int err = 0;
286
287 if (src->meths_count > 0) {
288 dst->meths =
289 OPENSSL_memdup(src->meths,
290 sizeof(*src->meths) * src->meths_count);
291 if (dst->meths == NULL)
292 return 0;
293 dst->meths_count = src->meths_count;
294
295 for (i = 0; i < src->meths_count; i++) {
296 custom_ext_method *methsrc = src->meths + i;
297 custom_ext_method *methdst = dst->meths + i;
298
299 if (methsrc->add_cb != custom_ext_add_old_cb_wrap)
300 continue;
301
302 /*
303 * We have found an old style API wrapper. We need to copy the
304 * arguments too.
305 */
306
307 if (err) {
308 methdst->add_arg = NULL;
309 methdst->parse_arg = NULL;
310 continue;
311 }
312
313 methdst->add_arg = OPENSSL_memdup(methsrc->add_arg,
314 sizeof(custom_ext_add_cb_wrap));
315 methdst->parse_arg = OPENSSL_memdup(methsrc->parse_arg,
316 sizeof(custom_ext_parse_cb_wrap));
317
318 if (methdst->add_arg == NULL || methdst->parse_arg == NULL)
319 err = 1;
320 }
321 }
322
323 if (err) {
324 custom_exts_free(dst);
325 return 0;
326 }
327
328 return 1;
329 }
330
custom_exts_free(custom_ext_methods * exts)331 void custom_exts_free(custom_ext_methods *exts)
332 {
333 size_t i;
334 custom_ext_method *meth;
335
336 for (i = 0, meth = exts->meths; i < exts->meths_count; i++, meth++) {
337 if (meth->add_cb != custom_ext_add_old_cb_wrap)
338 continue;
339
340 /* Old style API wrapper. Need to free the arguments too */
341 OPENSSL_free(meth->add_arg);
342 OPENSSL_free(meth->parse_arg);
343 }
344 OPENSSL_free(exts->meths);
345 exts->meths = NULL;
346 exts->meths_count = 0;
347 }
348
349 /* Return true if a client custom extension exists, false otherwise */
SSL_CTX_has_client_custom_ext(const SSL_CTX * ctx,unsigned int ext_type)350 int SSL_CTX_has_client_custom_ext(const SSL_CTX *ctx, unsigned int ext_type)
351 {
352 return custom_ext_find(&ctx->cert->custext, ENDPOINT_CLIENT, ext_type,
353 NULL) != NULL;
354 }
355
ossl_tls_add_custom_ext_intern(SSL_CTX * ctx,custom_ext_methods * exts,ENDPOINT role,unsigned int ext_type,unsigned int context,SSL_custom_ext_add_cb_ex add_cb,SSL_custom_ext_free_cb_ex free_cb,void * add_arg,SSL_custom_ext_parse_cb_ex parse_cb,void * parse_arg)356 int ossl_tls_add_custom_ext_intern(SSL_CTX *ctx, custom_ext_methods *exts,
357 ENDPOINT role, unsigned int ext_type,
358 unsigned int context,
359 SSL_custom_ext_add_cb_ex add_cb,
360 SSL_custom_ext_free_cb_ex free_cb,
361 void *add_arg,
362 SSL_custom_ext_parse_cb_ex parse_cb,
363 void *parse_arg)
364 {
365 custom_ext_method *meth, *tmp;
366
367 /*
368 * Check application error: if add_cb is not set free_cb will never be
369 * called.
370 */
371 if (add_cb == NULL && free_cb != NULL)
372 return 0;
373
374 if (exts == NULL)
375 exts = &ctx->cert->custext;
376
377 #ifndef OPENSSL_NO_CT
378 /*
379 * We don't want applications registering callbacks for SCT extensions
380 * whilst simultaneously using the built-in SCT validation features, as
381 * these two things may not play well together.
382 */
383 if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp
384 && (context & SSL_EXT_CLIENT_HELLO) != 0
385 && ctx != NULL
386 && SSL_CTX_ct_is_enabled(ctx))
387 return 0;
388 #endif
389
390 /*
391 * Don't add if extension supported internally, but make exception
392 * for extension types that previously were not supported, but now are.
393 */
394 if (SSL_extension_supported(ext_type)
395 && ext_type != TLSEXT_TYPE_signed_certificate_timestamp)
396 return 0;
397
398 /* Extension type must fit in 16 bits */
399 if (ext_type > 0xffff)
400 return 0;
401 /* Search for duplicate */
402 if (custom_ext_find(exts, role, ext_type, NULL))
403 return 0;
404 tmp = OPENSSL_realloc(exts->meths,
405 (exts->meths_count + 1) * sizeof(custom_ext_method));
406 if (tmp == NULL)
407 return 0;
408
409 exts->meths = tmp;
410 meth = exts->meths + exts->meths_count;
411 memset(meth, 0, sizeof(*meth));
412 meth->role = role;
413 meth->context = context;
414 meth->parse_cb = parse_cb;
415 meth->add_cb = add_cb;
416 meth->free_cb = free_cb;
417 meth->ext_type = ext_type;
418 meth->add_arg = add_arg;
419 meth->parse_arg = parse_arg;
420 exts->meths_count++;
421 return 1;
422 }
423
add_old_custom_ext(SSL_CTX * ctx,ENDPOINT role,unsigned int ext_type,unsigned int context,custom_ext_add_cb add_cb,custom_ext_free_cb free_cb,void * add_arg,custom_ext_parse_cb parse_cb,void * parse_arg)424 static int add_old_custom_ext(SSL_CTX *ctx, ENDPOINT role,
425 unsigned int ext_type,
426 unsigned int context,
427 custom_ext_add_cb add_cb,
428 custom_ext_free_cb free_cb,
429 void *add_arg,
430 custom_ext_parse_cb parse_cb, void *parse_arg)
431 {
432 custom_ext_add_cb_wrap *add_cb_wrap
433 = OPENSSL_malloc(sizeof(*add_cb_wrap));
434 custom_ext_parse_cb_wrap *parse_cb_wrap
435 = OPENSSL_malloc(sizeof(*parse_cb_wrap));
436 int ret;
437
438 if (add_cb_wrap == NULL || parse_cb_wrap == NULL) {
439 OPENSSL_free(add_cb_wrap);
440 OPENSSL_free(parse_cb_wrap);
441 return 0;
442 }
443
444 add_cb_wrap->add_arg = add_arg;
445 add_cb_wrap->add_cb = add_cb;
446 add_cb_wrap->free_cb = free_cb;
447 parse_cb_wrap->parse_arg = parse_arg;
448 parse_cb_wrap->parse_cb = parse_cb;
449
450 ret = ossl_tls_add_custom_ext_intern(ctx, NULL, role, ext_type,
451 context,
452 custom_ext_add_old_cb_wrap,
453 custom_ext_free_old_cb_wrap,
454 add_cb_wrap,
455 custom_ext_parse_old_cb_wrap,
456 parse_cb_wrap);
457
458 if (!ret) {
459 OPENSSL_free(add_cb_wrap);
460 OPENSSL_free(parse_cb_wrap);
461 }
462
463 return ret;
464 }
465
466 /* Application level functions to add the old custom extension callbacks */
SSL_CTX_add_client_custom_ext(SSL_CTX * ctx,unsigned int ext_type,custom_ext_add_cb add_cb,custom_ext_free_cb free_cb,void * add_arg,custom_ext_parse_cb parse_cb,void * parse_arg)467 int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
468 custom_ext_add_cb add_cb,
469 custom_ext_free_cb free_cb,
470 void *add_arg,
471 custom_ext_parse_cb parse_cb, void *parse_arg)
472 {
473 return add_old_custom_ext(ctx, ENDPOINT_CLIENT, ext_type,
474 SSL_EXT_TLS1_2_AND_BELOW_ONLY
475 | SSL_EXT_CLIENT_HELLO
476 | SSL_EXT_TLS1_2_SERVER_HELLO
477 | SSL_EXT_IGNORE_ON_RESUMPTION,
478 add_cb, free_cb, add_arg, parse_cb, parse_arg);
479 }
480
SSL_CTX_add_server_custom_ext(SSL_CTX * ctx,unsigned int ext_type,custom_ext_add_cb add_cb,custom_ext_free_cb free_cb,void * add_arg,custom_ext_parse_cb parse_cb,void * parse_arg)481 int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
482 custom_ext_add_cb add_cb,
483 custom_ext_free_cb free_cb,
484 void *add_arg,
485 custom_ext_parse_cb parse_cb, void *parse_arg)
486 {
487 return add_old_custom_ext(ctx, ENDPOINT_SERVER, ext_type,
488 SSL_EXT_TLS1_2_AND_BELOW_ONLY
489 | SSL_EXT_CLIENT_HELLO
490 | SSL_EXT_TLS1_2_SERVER_HELLO
491 | SSL_EXT_IGNORE_ON_RESUMPTION,
492 add_cb, free_cb, add_arg, parse_cb, parse_arg);
493 }
494
SSL_CTX_add_custom_ext(SSL_CTX * ctx,unsigned int ext_type,unsigned int context,SSL_custom_ext_add_cb_ex add_cb,SSL_custom_ext_free_cb_ex free_cb,void * add_arg,SSL_custom_ext_parse_cb_ex parse_cb,void * parse_arg)495 int SSL_CTX_add_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
496 unsigned int context,
497 SSL_custom_ext_add_cb_ex add_cb,
498 SSL_custom_ext_free_cb_ex free_cb,
499 void *add_arg,
500 SSL_custom_ext_parse_cb_ex parse_cb, void *parse_arg)
501 {
502 return ossl_tls_add_custom_ext_intern(ctx, NULL, ENDPOINT_BOTH, ext_type,
503 context, add_cb, free_cb, add_arg,
504 parse_cb, parse_arg);
505 }
506
SSL_extension_supported(unsigned int ext_type)507 int SSL_extension_supported(unsigned int ext_type)
508 {
509 switch (ext_type) {
510 /* Internally supported extensions. */
511 case TLSEXT_TYPE_application_layer_protocol_negotiation:
512 case TLSEXT_TYPE_ec_point_formats:
513 case TLSEXT_TYPE_supported_groups:
514 case TLSEXT_TYPE_key_share:
515 #ifndef OPENSSL_NO_NEXTPROTONEG
516 case TLSEXT_TYPE_next_proto_neg:
517 #endif
518 case TLSEXT_TYPE_padding:
519 case TLSEXT_TYPE_renegotiate:
520 case TLSEXT_TYPE_max_fragment_length:
521 case TLSEXT_TYPE_server_name:
522 case TLSEXT_TYPE_session_ticket:
523 case TLSEXT_TYPE_signature_algorithms:
524 #ifndef OPENSSL_NO_SRP
525 case TLSEXT_TYPE_srp:
526 #endif
527 #ifndef OPENSSL_NO_OCSP
528 case TLSEXT_TYPE_status_request:
529 #endif
530 #ifndef OPENSSL_NO_CT
531 case TLSEXT_TYPE_signed_certificate_timestamp:
532 #endif
533 #ifndef OPENSSL_NO_SRTP
534 case TLSEXT_TYPE_use_srtp:
535 #endif
536 case TLSEXT_TYPE_encrypt_then_mac:
537 case TLSEXT_TYPE_supported_versions:
538 case TLSEXT_TYPE_extended_master_secret:
539 case TLSEXT_TYPE_psk_kex_modes:
540 case TLSEXT_TYPE_cookie:
541 case TLSEXT_TYPE_early_data:
542 case TLSEXT_TYPE_certificate_authorities:
543 case TLSEXT_TYPE_psk:
544 case TLSEXT_TYPE_post_handshake_auth:
545 case TLSEXT_TYPE_compress_certificate:
546 case TLSEXT_TYPE_client_cert_type:
547 case TLSEXT_TYPE_server_cert_type:
548 return 1;
549 default:
550 return 0;
551 }
552 }
553
