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 #ifndef OPENSSL_NO_CT
  58 # include <openssl/ct.h>
  59 #endif
  60 #include "ssl_locl.h"
  61
  62
  63 /* Find a custom extension from the list. */
  64 static custom_ext_method *custom_ext_find(const custom_ext_methods *exts,
  65                                           unsigned int ext_type)
  66 {
  67     size_t i;
  68     custom_ext_method *meth = exts->meths;
  69     for (i = 0; i < exts->meths_count; i++, meth++) {
  70         if (ext_type == meth->ext_type)
  71             return meth;
  72     }
  73     return NULL;
  74 }
  75
  76 /*
  77  * Initialise custom extensions flags to indicate neither sent nor received.
  78  */
  79 void custom_ext_init(custom_ext_methods *exts)
  80 {
  81     size_t i;
  82     custom_ext_method *meth = exts->meths;
  83     for (i = 0; i < exts->meths_count; i++, meth++)
  84         meth->ext_flags = 0;
  85 }
  86
  87 /* Pass received custom extension data to the application for parsing. */
  88 int custom_ext_parse(SSL *s, int server,
  89                      unsigned int ext_type,
  90                      const unsigned char *ext_data, size_t ext_size, int *al)
  91 {
  92     custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
  93     custom_ext_method *meth;
  94     meth = custom_ext_find(exts, ext_type);
  95     /* If not found return success */
  96     if (!meth)
  97         return 1;
  98     if (!server) {
  99         /*
 100          * If it's ServerHello we can't have any extensions not sent in
 101          * ClientHello.
 102          */
 103         if (!(meth->ext_flags & SSL_EXT_FLAG_SENT)) {
 104             *al = TLS1_AD_UNSUPPORTED_EXTENSION;
 105             return 0;
 106         }
 107     }
 108     /* If already present it's a duplicate */
 109     if (meth->ext_flags & SSL_EXT_FLAG_RECEIVED) {
 110         *al = TLS1_AD_DECODE_ERROR;
 111         return 0;
 112     }
 113     meth->ext_flags |= SSL_EXT_FLAG_RECEIVED;
 114     /* If no parse function set return success */
 115     if (!meth->parse_cb)
 116         return 1;
 117
 118     return meth->parse_cb(s, ext_type, ext_data, ext_size, al,
 119                           meth->parse_arg);
 120 }
 121
 122 /*
 123  * Request custom extension data from the application and add to the return
 124  * buffer.
 125  */
 126 int custom_ext_add(SSL *s, int server,
 127                    unsigned char **pret, unsigned char *limit, int *al)
 128 {
 129     custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
 130     custom_ext_method *meth;
 131     unsigned char *ret = *pret;
 132     size_t i;
 133
 134     for (i = 0; i < exts->meths_count; i++) {
 135         const unsigned char *out = NULL;
 136         size_t outlen = 0;
 137         meth = exts->meths + i;
 138
 139         if (server) {
 140             /*
 141              * For ServerHello only send extensions present in ClientHello.
 142              */
 143             if (!(meth->ext_flags & SSL_EXT_FLAG_RECEIVED))
 144                 continue;
 145             /* If callback absent for server skip it */
 146             if (!meth->add_cb)
 147                 continue;
 148         }
 149         if (meth->add_cb) {
 150             int cb_retval = 0;
 151             cb_retval = meth->add_cb(s, meth->ext_type,
 152                                      &out, &outlen, al, meth->add_arg);
 153             if (cb_retval < 0)
 154                 return 0;       /* error */
 155             if (cb_retval == 0)
 156                 continue;       /* skip this extension */
 157         }
 158         if (4 > limit - ret || outlen > (size_t)(limit - ret - 4))
 159             return 0;
 160         s2n(meth->ext_type, ret);
 161         s2n(outlen, ret);
 162         if (outlen) {
 163             memcpy(ret, out, outlen);
 164             ret += outlen;
 165         }
 166         /*
 167          * We can't send duplicates: code logic should prevent this.
 168          */
 169         OPENSSL_assert(!(meth->ext_flags & SSL_EXT_FLAG_SENT));
 170         /*
 171          * Indicate extension has been sent: this is both a sanity check to
 172          * ensure we don't send duplicate extensions and indicates that it is
 173          * not an error if the extension is present in ServerHello.
 174          */
 175         meth->ext_flags |= SSL_EXT_FLAG_SENT;
 176         if (meth->free_cb)
 177             meth->free_cb(s, meth->ext_type, out, meth->add_arg);
 178     }
 179     *pret = ret;
 180     return 1;
 181 }
 182
 183 /* Copy table of custom extensions */
 184 int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src)
 185 {
 186     if (src->meths_count) {
 187         dst->meths =
 188             OPENSSL_memdup(src->meths,
 189                        sizeof(custom_ext_method) * src->meths_count);
 190         if (dst->meths == NULL)
 191             return 0;
 192         dst->meths_count = src->meths_count;
 193     }
 194     return 1;
 195 }
 196
 197 void custom_exts_free(custom_ext_methods *exts)
 198 {
 199     OPENSSL_free(exts->meths);
 200 }
 201
 202 /* Set callbacks for a custom extension. */
 203 static int custom_ext_meth_add(custom_ext_methods *exts,
 204                                unsigned int ext_type,
 205                                custom_ext_add_cb add_cb,
 206                                custom_ext_free_cb free_cb,
 207                                void *add_arg,
 208                                custom_ext_parse_cb parse_cb, void *parse_arg)
 209 {
 210     custom_ext_method *meth;
 211     /*
 212      * Check application error: if add_cb is not set free_cb will never be
 213      * called.
 214      */
 215     if (!add_cb && free_cb)
 216         return 0;
 217     /*
 218      * Don't add if extension supported internally, but make exception
 219      * for extension types that previously were not supported, but now are.
 220      */
 221     if (SSL_extension_supported(ext_type) &&
 222         ext_type != TLSEXT_TYPE_signed_certificate_timestamp)
 223         return 0;
 224     /* Extension type must fit in 16 bits */
 225     if (ext_type > 0xffff)
 226         return 0;
 227     /* Search for duplicate */
 228     if (custom_ext_find(exts, ext_type))
 229         return 0;
 230     exts->meths = OPENSSL_realloc(exts->meths,
 231                                   (exts->meths_count +
 232                                    1) * sizeof(custom_ext_method));
 233
 234     if (!exts->meths) {
 235         exts->meths_count = 0;
 236         return 0;
 237     }
 238
 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     int ret = custom_ext_meth_add(&ctx->cert->cli_ext, ext_type, add_cb,
 266                                   free_cb, add_arg, parse_cb, parse_arg);
 267
 268     if (ret != 1)
 269         goto end;
 270
 271 #ifndef OPENSSL_NO_CT
 272     /*
 273      * We don't want applications registering callbacks for SCT extensions
 274      * whilst simultaneously using the built-in SCT validation features, as
 275      * these two things may not play well together.
 276      */
 277     if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp &&
 278         SSL_CTX_get_ct_validation_callback(ctx) != NULL) {
 279         ret = 0;
 280     }
 281 #endif
 282 end:
 283     return ret;
 284 }
 285
 286 int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
 287                                   custom_ext_add_cb add_cb,
 288                                   custom_ext_free_cb free_cb,
 289                                   void *add_arg,
 290                                   custom_ext_parse_cb parse_cb,
 291                                   void *parse_arg)
 292 {
 293     return custom_ext_meth_add(&ctx->cert->srv_ext, ext_type,
 294                                add_cb, free_cb, add_arg, parse_cb, parse_arg);
 295 }
 296
 297 int SSL_extension_supported(unsigned int ext_type)
 298 {
 299     switch (ext_type) {
 300         /* Internally supported extensions. */
 301     case TLSEXT_TYPE_application_layer_protocol_negotiation:
 302     case TLSEXT_TYPE_ec_point_formats:
 303     case TLSEXT_TYPE_elliptic_curves:
 304     case TLSEXT_TYPE_heartbeat:
 305     case TLSEXT_TYPE_next_proto_neg:
 306     case TLSEXT_TYPE_padding:
 307     case TLSEXT_TYPE_renegotiate:
 308     case TLSEXT_TYPE_server_name:
 309     case TLSEXT_TYPE_session_ticket:
 310     case TLSEXT_TYPE_signature_algorithms:
 311     case TLSEXT_TYPE_srp:
 312     case TLSEXT_TYPE_status_request:
 313     case TLSEXT_TYPE_signed_certificate_timestamp:
 314     case TLSEXT_TYPE_use_srtp:
 315 #ifdef TLSEXT_TYPE_encrypt_then_mac
 316     case TLSEXT_TYPE_encrypt_then_mac:
 317 #endif
 318         return 1;
 319     default:
 320         return 0;
 321     }
 322 }