ssl/statem/extensions_cust.c

   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  */
  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_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;
 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_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  */
 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_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 (!for_comp)
 229                 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
 230             return 0;
 231         }
 232         if ((context & SSL_EXT_CLIENT_HELLO) != 0) {
 233             /*
 234              * We can't send duplicates: code logic should prevent this.
 235              */
 236             if (!ossl_assert((meth->ext_flags & SSL_EXT_FLAG_SENT) == 0)) {
 237                 if (!for_comp)
 238                     SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
 239                 return 0;
 240             }
 241             /*
 242              * Indicate extension has been sent: this is both a sanity check to
 243              * ensure we don't send duplicate extensions and indicates that it
 244              * is not an error if the extension is present in ServerHello.
 245              */
 246             meth->ext_flags |= SSL_EXT_FLAG_SENT;
 247         }
 248         if (meth->free_cb != NULL)
 249             meth->free_cb(SSL_CONNECTION_GET_SSL(s), meth->ext_type, context,
 250                           out, meth->add_arg);
 251     }
 252     return 1;
 253 }
 254
 255 /* Copy the flags from src to dst for any extensions that exist in both */
 256 int custom_exts_copy_flags(custom_ext_methods *dst,
 257                            const custom_ext_methods *src)
 258 {
 259     size_t i;
 260     custom_ext_method *methsrc = src->meths;
 261
 262     for (i = 0; i < src->meths_count; i++, methsrc++) {
 263         custom_ext_method *methdst = custom_ext_find(dst, methsrc->role,
 264                                                      methsrc->ext_type, NULL);
 265
 266         if (methdst == NULL)
 267             continue;
 268
 269         methdst->ext_flags = methsrc->ext_flags;
 270     }
 271
 272     return 1;
 273 }
 274
 275 /* Copy table of custom extensions */
 276 int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src)
 277 {
 278     size_t i;
 279     int err = 0;
 280
 281     if (src->meths_count > 0) {
 282         dst->meths =
 283             OPENSSL_memdup(src->meths,
 284                            sizeof(*src->meths) * src->meths_count);
 285         if (dst->meths == NULL)
 286             return 0;
 287         dst->meths_count = src->meths_count;
 288
 289         for (i = 0; i < src->meths_count; i++) {
 290             custom_ext_method *methsrc = src->meths + i;
 291             custom_ext_method *methdst = dst->meths + i;
 292
 293             if (methsrc->add_cb != custom_ext_add_old_cb_wrap)
 294                 continue;
 295
 296             /*
 297              * We have found an old style API wrapper. We need to copy the
 298              * arguments too.
 299              */
 300
 301             if (err) {
 302                 methdst->add_arg = NULL;
 303                 methdst->parse_arg = NULL;
 304                 continue;
 305             }
 306
 307             methdst->add_arg = OPENSSL_memdup(methsrc->add_arg,
 308                                               sizeof(custom_ext_add_cb_wrap));
 309             methdst->parse_arg = OPENSSL_memdup(methsrc->parse_arg,
 310                                             sizeof(custom_ext_parse_cb_wrap));
 311
 312             if (methdst->add_arg == NULL || methdst->parse_arg == NULL)
 313                 err = 1;
 314         }
 315     }
 316
 317     if (err) {
 318         custom_exts_free(dst);
 319         return 0;
 320     }
 321
 322     return 1;
 323 }
 324
 325 void custom_exts_free(custom_ext_methods *exts)
 326 {
 327     size_t i;
 328     custom_ext_method *meth;
 329
 330     for (i = 0, meth = exts->meths; i < exts->meths_count; i++, meth++) {
 331         if (meth->add_cb != custom_ext_add_old_cb_wrap)
 332             continue;
 333
 334         /* Old style API wrapper. Need to free the arguments too */
 335         OPENSSL_free(meth->add_arg);
 336         OPENSSL_free(meth->parse_arg);
 337     }
 338     OPENSSL_free(exts->meths);
 339 }
 340
 341 /* Return true if a client custom extension exists, false otherwise */
 342 int SSL_CTX_has_client_custom_ext(const SSL_CTX *ctx, unsigned int ext_type)
 343 {
 344     return custom_ext_find(&ctx->cert->custext, ENDPOINT_CLIENT, ext_type,
 345                            NULL) != NULL;
 346 }
 347
 348 int ossl_tls_add_custom_ext_intern(SSL_CTX *ctx, custom_ext_methods *exts,
 349                                    ENDPOINT role, unsigned int ext_type,
 350                                    unsigned int context,
 351                                    SSL_custom_ext_add_cb_ex add_cb,
 352                                    SSL_custom_ext_free_cb_ex free_cb,
 353                                    void *add_arg,
 354                                    SSL_custom_ext_parse_cb_ex parse_cb,
 355                                    void *parse_arg)
 356 {
 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     if (exts == NULL)
 367         exts = &ctx->cert->custext;
 368
 369 #ifndef OPENSSL_NO_CT
 370     /*
 371      * We don't want applications registering callbacks for SCT extensions
 372      * whilst simultaneously using the built-in SCT validation features, as
 373      * these two things may not play well together.
 374      */
 375     if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp
 376             && (context & SSL_EXT_CLIENT_HELLO) != 0
 377             && ctx != NULL
 378             && SSL_CTX_ct_is_enabled(ctx))
 379         return 0;
 380 #endif
 381
 382     /*
 383      * Don't add if extension supported internally, but make exception
 384      * for extension types that previously were not supported, but now are.
 385      */
 386     if (SSL_extension_supported(ext_type)
 387             && ext_type != TLSEXT_TYPE_signed_certificate_timestamp)
 388         return 0;
 389
 390     /* Extension type must fit in 16 bits */
 391     if (ext_type > 0xffff)
 392         return 0;
 393     /* Search for duplicate */
 394     if (custom_ext_find(exts, role, ext_type, NULL))
 395         return 0;
 396     tmp = OPENSSL_realloc(exts->meths,
 397                           (exts->meths_count + 1) * sizeof(custom_ext_method));
 398     if (tmp == NULL)
 399         return 0;
 400
 401     exts->meths = tmp;
 402     meth = exts->meths + exts->meths_count;
 403     memset(meth, 0, sizeof(*meth));
 404     meth->role = role;
 405     meth->context = context;
 406     meth->parse_cb = parse_cb;
 407     meth->add_cb = add_cb;
 408     meth->free_cb = free_cb;
 409     meth->ext_type = ext_type;
 410     meth->add_arg = add_arg;
 411     meth->parse_arg = parse_arg;
 412     exts->meths_count++;
 413     return 1;
 414 }
 415
 416 static int add_old_custom_ext(SSL_CTX *ctx, ENDPOINT role,
 417                               unsigned int ext_type,
 418                               unsigned int context,
 419                               custom_ext_add_cb add_cb,
 420                               custom_ext_free_cb free_cb,
 421                               void *add_arg,
 422                               custom_ext_parse_cb parse_cb, void *parse_arg)
 423 {
 424     custom_ext_add_cb_wrap *add_cb_wrap
 425         = OPENSSL_malloc(sizeof(*add_cb_wrap));
 426     custom_ext_parse_cb_wrap *parse_cb_wrap
 427         = OPENSSL_malloc(sizeof(*parse_cb_wrap));
 428     int ret;
 429
 430     if (add_cb_wrap == NULL || parse_cb_wrap == NULL) {
 431         OPENSSL_free(add_cb_wrap);
 432         OPENSSL_free(parse_cb_wrap);
 433         return 0;
 434     }
 435
 436     add_cb_wrap->add_arg = add_arg;
 437     add_cb_wrap->add_cb = add_cb;
 438     add_cb_wrap->free_cb = free_cb;
 439     parse_cb_wrap->parse_arg = parse_arg;
 440     parse_cb_wrap->parse_cb = parse_cb;
 441
 442     ret = ossl_tls_add_custom_ext_intern(ctx, NULL, role, ext_type,
 443                                          context,
 444                                          custom_ext_add_old_cb_wrap,
 445                                          custom_ext_free_old_cb_wrap,
 446                                          add_cb_wrap,
 447                                          custom_ext_parse_old_cb_wrap,
 448                                          parse_cb_wrap);
 449
 450     if (!ret) {
 451         OPENSSL_free(add_cb_wrap);
 452         OPENSSL_free(parse_cb_wrap);
 453     }
 454
 455     return ret;
 456 }
 457
 458 /* Application level functions to add the old custom extension callbacks */
 459 int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
 460                                   custom_ext_add_cb add_cb,
 461                                   custom_ext_free_cb free_cb,
 462                                   void *add_arg,
 463                                   custom_ext_parse_cb parse_cb, void *parse_arg)
 464 {
 465     return add_old_custom_ext(ctx, ENDPOINT_CLIENT, ext_type,
 466                               SSL_EXT_TLS1_2_AND_BELOW_ONLY
 467                               | SSL_EXT_CLIENT_HELLO
 468                               | SSL_EXT_TLS1_2_SERVER_HELLO
 469                               | SSL_EXT_IGNORE_ON_RESUMPTION,
 470                               add_cb, free_cb, add_arg, parse_cb, parse_arg);
 471 }
 472
 473 int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
 474                                   custom_ext_add_cb add_cb,
 475                                   custom_ext_free_cb free_cb,
 476                                   void *add_arg,
 477                                   custom_ext_parse_cb parse_cb, void *parse_arg)
 478 {
 479     return add_old_custom_ext(ctx, ENDPOINT_SERVER, ext_type,
 480                               SSL_EXT_TLS1_2_AND_BELOW_ONLY
 481                               | SSL_EXT_CLIENT_HELLO
 482                               | SSL_EXT_TLS1_2_SERVER_HELLO
 483                               | SSL_EXT_IGNORE_ON_RESUMPTION,
 484                               add_cb, free_cb, add_arg, parse_cb, parse_arg);
 485 }
 486
 487 int SSL_CTX_add_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
 488                            unsigned int context,
 489                            SSL_custom_ext_add_cb_ex add_cb,
 490                            SSL_custom_ext_free_cb_ex free_cb,
 491                            void *add_arg,
 492                            SSL_custom_ext_parse_cb_ex parse_cb, void *parse_arg)
 493 {
 494     return ossl_tls_add_custom_ext_intern(ctx, NULL, ENDPOINT_BOTH, ext_type,
 495                                           context, add_cb, free_cb, add_arg,
 496                                           parse_cb, parse_arg);
 497 }
 498
 499 int SSL_extension_supported(unsigned int ext_type)
 500 {
 501     switch (ext_type) {
 502         /* Internally supported extensions. */
 503     case TLSEXT_TYPE_application_layer_protocol_negotiation:
 504     case TLSEXT_TYPE_ec_point_formats:
 505     case TLSEXT_TYPE_supported_groups:
 506     case TLSEXT_TYPE_key_share:
 507 #ifndef OPENSSL_NO_NEXTPROTONEG
 508     case TLSEXT_TYPE_next_proto_neg:
 509 #endif
 510     case TLSEXT_TYPE_padding:
 511     case TLSEXT_TYPE_renegotiate:
 512     case TLSEXT_TYPE_max_fragment_length:
 513     case TLSEXT_TYPE_server_name:
 514     case TLSEXT_TYPE_session_ticket:
 515     case TLSEXT_TYPE_signature_algorithms:
 516 #ifndef OPENSSL_NO_SRP
 517     case TLSEXT_TYPE_srp:
 518 #endif
 519 #ifndef OPENSSL_NO_OCSP
 520     case TLSEXT_TYPE_status_request:
 521 #endif
 522 #ifndef OPENSSL_NO_CT
 523     case TLSEXT_TYPE_signed_certificate_timestamp:
 524 #endif
 525 #ifndef OPENSSL_NO_SRTP
 526     case TLSEXT_TYPE_use_srtp:
 527 #endif
 528     case TLSEXT_TYPE_encrypt_then_mac:
 529     case TLSEXT_TYPE_supported_versions:
 530     case TLSEXT_TYPE_extended_master_secret:
 531     case TLSEXT_TYPE_psk_kex_modes:
 532     case TLSEXT_TYPE_cookie:
 533     case TLSEXT_TYPE_early_data:
 534     case TLSEXT_TYPE_certificate_authorities:
 535     case TLSEXT_TYPE_psk:
 536     case TLSEXT_TYPE_post_handshake_auth:
 537     case TLSEXT_TYPE_compress_certificate:
 538     case TLSEXT_TYPE_client_cert_type:
 539     case TLSEXT_TYPE_server_cert_type:
 540         return 1;
 541     default:
 542         return 0;
 543     }
 544 }