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 */
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_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 */
custom_ext_add(SSL * s,int context,WPACKET * pkt,X509 * x,size_t chainidx,int maxversion)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 if (meth->free_cb != NULL)
224 meth->free_cb(s, meth->ext_type, context, out, meth->add_arg);
225 SSLfatal(s, SSL_AD_INTERNAL_ERROR, 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 if (meth->free_cb != NULL)
234 meth->free_cb(s, meth->ext_type, context, out,
235 meth->add_arg);
236 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
237 return 0;
238 }
239 /*
240 * Indicate extension has been sent: this is both a sanity check to
241 * ensure we don't send duplicate extensions and indicates that it
242 * is not an error if the extension is present in ServerHello.
243 */
244 meth->ext_flags |= SSL_EXT_FLAG_SENT;
245 }
246 if (meth->free_cb != NULL)
247 meth->free_cb(s, meth->ext_type, context, out, meth->add_arg);
248 }
249 return 1;
250 }
251
252 /* 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)253 int custom_exts_copy_flags(custom_ext_methods *dst,
254 const custom_ext_methods *src)
255 {
256 size_t i;
257 custom_ext_method *methsrc = src->meths;
258
259 for (i = 0; i < src->meths_count; i++, methsrc++) {
260 custom_ext_method *methdst = custom_ext_find(dst, methsrc->role,
261 methsrc->ext_type, NULL);
262
263 if (methdst == NULL)
264 continue;
265
266 methdst->ext_flags = methsrc->ext_flags;
267 }
268
269 return 1;
270 }
271
272 /* Copy table of custom extensions */
custom_exts_copy(custom_ext_methods * dst,const custom_ext_methods * src)273 int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src)
274 {
275 size_t i;
276 int err = 0;
277
278 if (src->meths_count > 0) {
279 dst->meths =
280 OPENSSL_memdup(src->meths,
281 sizeof(*src->meths) * src->meths_count);
282 if (dst->meths == NULL)
283 return 0;
284 dst->meths_count = src->meths_count;
285
286 for (i = 0; i < src->meths_count; i++) {
287 custom_ext_method *methsrc = src->meths + i;
288 custom_ext_method *methdst = dst->meths + i;
289
290 if (methsrc->add_cb != custom_ext_add_old_cb_wrap)
291 continue;
292
293 /*
294 * We have found an old style API wrapper. We need to copy the
295 * arguments too.
296 */
297
298 if (err) {
299 methdst->add_arg = NULL;
300 methdst->parse_arg = NULL;
301 continue;
302 }
303
304 methdst->add_arg = OPENSSL_memdup(methsrc->add_arg,
305 sizeof(custom_ext_add_cb_wrap));
306 methdst->parse_arg = OPENSSL_memdup(methsrc->parse_arg,
307 sizeof(custom_ext_parse_cb_wrap));
308
309 if (methdst->add_arg == NULL || methdst->parse_arg == NULL)
310 err = 1;
311 }
312 }
313
314 if (err) {
315 custom_exts_free(dst);
316 return 0;
317 }
318
319 return 1;
320 }
321
custom_exts_free(custom_ext_methods * exts)322 void custom_exts_free(custom_ext_methods *exts)
323 {
324 size_t i;
325 custom_ext_method *meth;
326
327 for (i = 0, meth = exts->meths; i < exts->meths_count; i++, meth++) {
328 if (meth->add_cb != custom_ext_add_old_cb_wrap)
329 continue;
330
331 /* Old style API wrapper. Need to free the arguments too */
332 OPENSSL_free(meth->add_arg);
333 OPENSSL_free(meth->parse_arg);
334 }
335 OPENSSL_free(exts->meths);
336 exts->meths = NULL;
337 exts->meths_count = 0;
338 }
339
340 /* Return true if a client custom extension exists, false otherwise */
SSL_CTX_has_client_custom_ext(const SSL_CTX * ctx,unsigned int ext_type)341 int SSL_CTX_has_client_custom_ext(const SSL_CTX *ctx, unsigned int ext_type)
342 {
343 return custom_ext_find(&ctx->cert->custext, ENDPOINT_CLIENT, ext_type,
344 NULL) != NULL;
345 }
346
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)347 static int add_custom_ext_intern(SSL_CTX *ctx, ENDPOINT role,
348 unsigned int ext_type,
349 unsigned int context,
350 SSL_custom_ext_add_cb_ex add_cb,
351 SSL_custom_ext_free_cb_ex free_cb,
352 void *add_arg,
353 SSL_custom_ext_parse_cb_ex parse_cb,
354 void *parse_arg)
355 {
356 custom_ext_methods *exts = &ctx->cert->custext;
357 custom_ext_method *meth, *tmp;
358
359 /*
360 * Check application error: if add_cb is not set free_cb will never be
361 * called.
362 */
363 if (add_cb == NULL && free_cb != NULL)
364 return 0;
365
366 #ifndef OPENSSL_NO_CT
367 /*
368 * We don't want applications registering callbacks for SCT extensions
369 * whilst simultaneously using the built-in SCT validation features, as
370 * these two things may not play well together.
371 */
372 if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp
373 && (context & SSL_EXT_CLIENT_HELLO) != 0
374 && SSL_CTX_ct_is_enabled(ctx))
375 return 0;
376 #endif
377
378 /*
379 * Don't add if extension supported internally, but make exception
380 * for extension types that previously were not supported, but now are.
381 */
382 if (SSL_extension_supported(ext_type)
383 && ext_type != TLSEXT_TYPE_signed_certificate_timestamp)
384 return 0;
385
386 /* Extension type must fit in 16 bits */
387 if (ext_type > 0xffff)
388 return 0;
389 /* Search for duplicate */
390 if (custom_ext_find(exts, role, ext_type, NULL))
391 return 0;
392 tmp = OPENSSL_realloc(exts->meths,
393 (exts->meths_count + 1) * sizeof(custom_ext_method));
394 if (tmp == NULL)
395 return 0;
396
397 exts->meths = tmp;
398 meth = exts->meths + exts->meths_count;
399 memset(meth, 0, sizeof(*meth));
400 meth->role = role;
401 meth->context = context;
402 meth->parse_cb = parse_cb;
403 meth->add_cb = add_cb;
404 meth->free_cb = free_cb;
405 meth->ext_type = ext_type;
406 meth->add_arg = add_arg;
407 meth->parse_arg = parse_arg;
408 exts->meths_count++;
409 return 1;
410 }
411
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)412 static int add_old_custom_ext(SSL_CTX *ctx, ENDPOINT role,
413 unsigned int ext_type,
414 unsigned int context,
415 custom_ext_add_cb add_cb,
416 custom_ext_free_cb free_cb,
417 void *add_arg,
418 custom_ext_parse_cb parse_cb, void *parse_arg)
419 {
420 custom_ext_add_cb_wrap *add_cb_wrap
421 = OPENSSL_malloc(sizeof(*add_cb_wrap));
422 custom_ext_parse_cb_wrap *parse_cb_wrap
423 = OPENSSL_malloc(sizeof(*parse_cb_wrap));
424 int ret;
425
426 if (add_cb_wrap == NULL || parse_cb_wrap == NULL) {
427 OPENSSL_free(add_cb_wrap);
428 OPENSSL_free(parse_cb_wrap);
429 return 0;
430 }
431
432 add_cb_wrap->add_arg = add_arg;
433 add_cb_wrap->add_cb = add_cb;
434 add_cb_wrap->free_cb = free_cb;
435 parse_cb_wrap->parse_arg = parse_arg;
436 parse_cb_wrap->parse_cb = parse_cb;
437
438 ret = add_custom_ext_intern(ctx, role, ext_type,
439 context,
440 custom_ext_add_old_cb_wrap,
441 custom_ext_free_old_cb_wrap,
442 add_cb_wrap,
443 custom_ext_parse_old_cb_wrap,
444 parse_cb_wrap);
445
446 if (!ret) {
447 OPENSSL_free(add_cb_wrap);
448 OPENSSL_free(parse_cb_wrap);
449 }
450
451 return ret;
452 }
453
454 /* 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)455 int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
456 custom_ext_add_cb add_cb,
457 custom_ext_free_cb free_cb,
458 void *add_arg,
459 custom_ext_parse_cb parse_cb, void *parse_arg)
460 {
461 return add_old_custom_ext(ctx, ENDPOINT_CLIENT, ext_type,
462 SSL_EXT_TLS1_2_AND_BELOW_ONLY
463 | SSL_EXT_CLIENT_HELLO
464 | SSL_EXT_TLS1_2_SERVER_HELLO
465 | SSL_EXT_IGNORE_ON_RESUMPTION,
466 add_cb, free_cb, add_arg, parse_cb, parse_arg);
467 }
468
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)469 int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
470 custom_ext_add_cb add_cb,
471 custom_ext_free_cb free_cb,
472 void *add_arg,
473 custom_ext_parse_cb parse_cb, void *parse_arg)
474 {
475 return add_old_custom_ext(ctx, ENDPOINT_SERVER, ext_type,
476 SSL_EXT_TLS1_2_AND_BELOW_ONLY
477 | SSL_EXT_CLIENT_HELLO
478 | SSL_EXT_TLS1_2_SERVER_HELLO
479 | SSL_EXT_IGNORE_ON_RESUMPTION,
480 add_cb, free_cb, add_arg, parse_cb, parse_arg);
481 }
482
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)483 int SSL_CTX_add_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
484 unsigned int context,
485 SSL_custom_ext_add_cb_ex add_cb,
486 SSL_custom_ext_free_cb_ex free_cb,
487 void *add_arg,
488 SSL_custom_ext_parse_cb_ex parse_cb, void *parse_arg)
489 {
490 return add_custom_ext_intern(ctx, ENDPOINT_BOTH, ext_type, context, add_cb,
491 free_cb, add_arg, parse_cb, parse_arg);
492 }
493
SSL_extension_supported(unsigned int ext_type)494 int SSL_extension_supported(unsigned int ext_type)
495 {
496 switch (ext_type) {
497 /* Internally supported extensions. */
498 case TLSEXT_TYPE_application_layer_protocol_negotiation:
499 case TLSEXT_TYPE_ec_point_formats:
500 case TLSEXT_TYPE_supported_groups:
501 case TLSEXT_TYPE_key_share:
502 #ifndef OPENSSL_NO_NEXTPROTONEG
503 case TLSEXT_TYPE_next_proto_neg:
504 #endif
505 case TLSEXT_TYPE_padding:
506 case TLSEXT_TYPE_renegotiate:
507 case TLSEXT_TYPE_max_fragment_length:
508 case TLSEXT_TYPE_server_name:
509 case TLSEXT_TYPE_session_ticket:
510 case TLSEXT_TYPE_signature_algorithms:
511 #ifndef OPENSSL_NO_SRP
512 case TLSEXT_TYPE_srp:
513 #endif
514 #ifndef OPENSSL_NO_OCSP
515 case TLSEXT_TYPE_status_request:
516 #endif
517 #ifndef OPENSSL_NO_CT
518 case TLSEXT_TYPE_signed_certificate_timestamp:
519 #endif
520 #ifndef OPENSSL_NO_SRTP
521 case TLSEXT_TYPE_use_srtp:
522 #endif
523 case TLSEXT_TYPE_encrypt_then_mac:
524 case TLSEXT_TYPE_supported_versions:
525 case TLSEXT_TYPE_extended_master_secret:
526 case TLSEXT_TYPE_psk_kex_modes:
527 case TLSEXT_TYPE_cookie:
528 case TLSEXT_TYPE_early_data:
529 case TLSEXT_TYPE_certificate_authorities:
530 case TLSEXT_TYPE_psk:
531 case TLSEXT_TYPE_post_handshake_auth:
532 return 1;
533 default:
534 return 0;
535 }
536 }
537