ssl/t1_ext.c

   1 /* ====================================================================
   2  * Copyright (c) 2014 The OpenSSL Project.  All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  *
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  *
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in
  13  *    the documentation and/or other materials provided with the
  14  *    distribution.
  15  *
  16  * 3. All advertising materials mentioning features or use of this
  17  *    software must display the following acknowledgment:
  18  *    "This product includes software developed by the OpenSSL Project
  19  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  20  *
  21  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  22  *    endorse or promote products derived from this software without
  23  *    prior written permission. For written permission, please contact
  24  *    openssl-core@openssl.org.
  25  *
  26  * 5. Products derived from this software may not be called "OpenSSL"
  27  *    nor may "OpenSSL" appear in their names without prior written
  28  *    permission of the OpenSSL Project.
  29  *
  30  * 6. Redistributions of any form whatsoever must retain the following
  31  *    acknowledgment:
  32  *    "This product includes software developed by the OpenSSL Project
  33  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  34  *
  35  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  36  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  37  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  38  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  39  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  40  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  41  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  42  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  43  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  44  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  45  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  46  * OF THE POSSIBILITY OF SUCH DAMAGE.
  47  * ====================================================================
  48  *
  49  * This product includes cryptographic software written by Eric Young
  50  * (eay@cryptsoft.com).  This product includes software written by Tim
  51  * Hudson (tjh@cryptsoft.com).
  52  *
  53  */
  54
  55 /* Custom extension utility functions */
  56
  57 #include <openssl/ct.h>
  58 #include "ssl_locl.h"
  59
  60
  61 /* Find a custom extension from the list. */
  62 static custom_ext_method *custom_ext_find(const custom_ext_methods *exts,
  63                                           unsigned int ext_type)
  64 {
  65     size_t i;
  66     custom_ext_method *meth = exts->meths;
  67     for (i = 0; i < exts->meths_count; i++, meth++) {
  68         if (ext_type == meth->ext_type)
  69             return meth;
  70     }
  71     return NULL;
  72 }
  73
  74 /*
  75  * Initialise custom extensions flags to indicate neither sent nor received.
  76  */
  77 void custom_ext_init(custom_ext_methods *exts)
  78 {
  79     size_t i;
  80     custom_ext_method *meth = exts->meths;
  81     for (i = 0; i < exts->meths_count; i++, meth++)
  82         meth->ext_flags = 0;
  83 }
  84
  85 /* Pass received custom extension data to the application for parsing. */
  86 int custom_ext_parse(SSL *s, int server,
  87                      unsigned int ext_type,
  88                      const unsigned char *ext_data, size_t ext_size, int *al)
  89 {
  90     custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
  91     custom_ext_method *meth;
  92     meth = custom_ext_find(exts, ext_type);
  93     /* If not found return success */
  94     if (!meth)
  95         return 1;
  96     if (!server) {
  97         /*
  98          * If it's ServerHello we can't have any extensions not sent in
  99          * ClientHello.
 100          */
 101         if (!(meth->ext_flags & SSL_EXT_FLAG_SENT)) {
 102             *al = TLS1_AD_UNSUPPORTED_EXTENSION;
 103             return 0;
 104         }
 105     }
 106     /* If already present it's a duplicate */
 107     if (meth->ext_flags & SSL_EXT_FLAG_RECEIVED) {
 108         *al = TLS1_AD_DECODE_ERROR;
 109         return 0;
 110     }
 111     meth->ext_flags |= SSL_EXT_FLAG_RECEIVED;
 112     /* If no parse function set return success */
 113     if (!meth->parse_cb)
 114         return 1;
 115
 116     return meth->parse_cb(s, ext_type, ext_data, ext_size, al,
 117                           meth->parse_arg);
 118 }
 119
 120 /*
 121  * Request custom extension data from the application and add to the return
 122  * buffer.
 123  */
 124 int custom_ext_add(SSL *s, int server,
 125                    unsigned char **pret, unsigned char *limit, int *al)
 126 {
 127     custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
 128     custom_ext_method *meth;
 129     unsigned char *ret = *pret;
 130     size_t i;
 131
 132     for (i = 0; i < exts->meths_count; i++) {
 133         const unsigned char *out = NULL;
 134         size_t outlen = 0;
 135         meth = exts->meths + i;
 136
 137         if (server) {
 138             /*
 139              * For ServerHello only send extensions present in ClientHello.
 140              */
 141             if (!(meth->ext_flags & SSL_EXT_FLAG_RECEIVED))
 142                 continue;
 143             /* If callback absent for server skip it */
 144             if (!meth->add_cb)
 145                 continue;
 146         }
 147         if (meth->add_cb) {
 148             int cb_retval = 0;
 149             cb_retval = meth->add_cb(s, meth->ext_type,
 150                                      &out, &outlen, al, meth->add_arg);
 151             if (cb_retval < 0)
 152                 return 0;       /* error */
 153             if (cb_retval == 0)
 154                 continue;       /* skip this extension */
 155         }
 156         if (4 > limit - ret || outlen > (size_t)(limit - ret - 4))
 157             return 0;
 158         s2n(meth->ext_type, ret);
 159         s2n(outlen, ret);
 160         if (outlen) {
 161             memcpy(ret, out, outlen);
 162             ret += outlen;
 163         }
 164         /*
 165          * We can't send duplicates: code logic should prevent this.
 166          */
 167         OPENSSL_assert(!(meth->ext_flags & SSL_EXT_FLAG_SENT));
 168         /*
 169          * Indicate extension has been sent: this is both a sanity check to
 170          * ensure we don't send duplicate extensions and indicates that it is
 171          * not an error if the extension is present in ServerHello.
 172          */
 173         meth->ext_flags |= SSL_EXT_FLAG_SENT;
 174         if (meth->free_cb)
 175             meth->free_cb(s, meth->ext_type, out, meth->add_arg);
 176     }
 177     *pret = ret;
 178     return 1;
 179 }
 180
 181 /* Copy table of custom extensions */
 182 int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src)
 183 {
 184     if (src->meths_count) {
 185         dst->meths =
 186             OPENSSL_memdup(src->meths,
 187                        sizeof(custom_ext_method) * src->meths_count);
 188         if (dst->meths == NULL)
 189             return 0;
 190         dst->meths_count = src->meths_count;
 191     }
 192     return 1;
 193 }
 194
 195 void custom_exts_free(custom_ext_methods *exts)
 196 {
 197     OPENSSL_free(exts->meths);
 198 }
 199
 200 /* Set callbacks for a custom extension. */
 201 static int custom_ext_meth_add(custom_ext_methods *exts,
 202                                unsigned int ext_type,
 203                                custom_ext_add_cb add_cb,
 204                                custom_ext_free_cb free_cb,
 205                                void *add_arg,
 206                                custom_ext_parse_cb parse_cb, void *parse_arg)
 207 {
 208     custom_ext_method *meth, *tmp;
 209     /*
 210      * Check application error: if add_cb is not set free_cb will never be
 211      * called.
 212      */
 213     if (!add_cb && free_cb)
 214         return 0;
 215     /*
 216      * Don't add if extension supported internally, but make exception
 217      * for extension types that previously were not supported, but now are.
 218      */
 219     if (SSL_extension_supported(ext_type) &&
 220         ext_type != TLSEXT_TYPE_signed_certificate_timestamp)
 221         return 0;
 222     /* Extension type must fit in 16 bits */
 223     if (ext_type > 0xffff)
 224         return 0;
 225     /* Search for duplicate */
 226     if (custom_ext_find(exts, ext_type))
 227         return 0;
 228     tmp = OPENSSL_realloc(exts->meths,
 229                           (exts->meths_count + 1) * sizeof(custom_ext_method));
 230
 231     if (tmp == NULL) {
 232         OPENSSL_free(exts->meths);
 233         exts->meths = NULL;
 234         exts->meths_count = 0;
 235         return 0;
 236     }
 237
 238     exts->meths = tmp;
 239     meth = exts->meths + exts->meths_count;
 240     memset(meth, 0, sizeof(*meth));
 241     meth->parse_cb = parse_cb;
 242     meth->add_cb = add_cb;
 243     meth->free_cb = free_cb;
 244     meth->ext_type = ext_type;
 245     meth->add_arg = add_arg;
 246     meth->parse_arg = parse_arg;
 247     exts->meths_count++;
 248     return 1;
 249 }
 250
 251 /* Return true if a client custom extension exists, false otherwise */
 252 int SSL_CTX_has_client_custom_ext(const SSL_CTX *ctx, unsigned int ext_type)
 253 {
 254     return custom_ext_find(&ctx->cert->cli_ext, ext_type) != NULL;
 255 }
 256
 257 /* Application level functions to add custom extension callbacks */
 258 int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
 259                                   custom_ext_add_cb add_cb,
 260                                   custom_ext_free_cb free_cb,
 261                                   void *add_arg,
 262                                   custom_ext_parse_cb parse_cb,
 263                                   void *parse_arg)
 264 {
 265 #ifndef OPENSSL_NO_CT
 266     /*
 267      * We don't want applications registering callbacks for SCT extensions
 268      * whilst simultaneously using the built-in SCT validation features, as
 269      * these two things may not play well together.
 270      */
 271     if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp &&
 272         SSL_CTX_ct_is_enabled(ctx))
 273         return 0;
 274 #endif
 275     return custom_ext_meth_add(&ctx->cert->cli_ext, ext_type, add_cb,
 276                                free_cb, add_arg, parse_cb, parse_arg);
 277 }
 278
 279 int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
 280                                   custom_ext_add_cb add_cb,
 281                                   custom_ext_free_cb free_cb,
 282                                   void *add_arg,
 283                                   custom_ext_parse_cb parse_cb,
 284                                   void *parse_arg)
 285 {
 286     return custom_ext_meth_add(&ctx->cert->srv_ext, ext_type,
 287                                add_cb, free_cb, add_arg, parse_cb, parse_arg);
 288 }
 289
 290 int SSL_extension_supported(unsigned int ext_type)
 291 {
 292     switch (ext_type) {
 293         /* Internally supported extensions. */
 294     case TLSEXT_TYPE_application_layer_protocol_negotiation:
 295     case TLSEXT_TYPE_ec_point_formats:
 296     case TLSEXT_TYPE_elliptic_curves:
 297     case TLSEXT_TYPE_heartbeat:
 298 #ifndef OPENSSL_NO_NEXTPROTONEG
 299     case TLSEXT_TYPE_next_proto_neg:
 300 #endif
 301     case TLSEXT_TYPE_padding:
 302     case TLSEXT_TYPE_renegotiate:
 303     case TLSEXT_TYPE_server_name:
 304     case TLSEXT_TYPE_session_ticket:
 305     case TLSEXT_TYPE_signature_algorithms:
 306     case TLSEXT_TYPE_srp:
 307     case TLSEXT_TYPE_status_request:
 308     case TLSEXT_TYPE_signed_certificate_timestamp:
 309     case TLSEXT_TYPE_use_srtp:
 310 #ifdef TLSEXT_TYPE_encrypt_then_mac
 311     case TLSEXT_TYPE_encrypt_then_mac:
 312 #endif
 313         return 1;
 314     default:
 315         return 0;
 316     }
 317 }