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 */
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 * 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 *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 */
custom_ext_add(SSL * s,int context,WPACKET * pkt,X509 * x,size_t chainidx,int maxversion)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 */
custom_exts_copy_flags(custom_ext_methods * dst,const custom_ext_methods * src)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 */
custom_exts_copy(custom_ext_methods * dst,const custom_ext_methods * src)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
custom_exts_free(custom_ext_methods * exts)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 */
SSL_CTX_has_client_custom_ext(const SSL_CTX * ctx,unsigned int ext_type)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
add_custom_ext_intern(SSL_CTX * ctx,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)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
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)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 */
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)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
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)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
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)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
SSL_extension_supported(unsigned int ext_type)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