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 "ssl_locl.h"
  58
  59
  60 /* Find a custom extension from the list. */
  61 static custom_ext_method *custom_ext_find(custom_ext_methods *exts,
  62                                           unsigned int ext_type)
  63 {
  64     size_t i;
  65     custom_ext_method *meth = exts->meths;
  66     for (i = 0; i < exts->meths_count; i++, meth++) {
  67         if (ext_type == meth->ext_type)
  68             return meth;
  69     }
  70     return NULL;
  71 }
  72
  73 /*
  74  * Initialise custom extensions flags to indicate neither sent nor received.
  75  */
  76 void custom_ext_init(custom_ext_methods *exts)
  77 {
  78     size_t i;
  79     custom_ext_method *meth = exts->meths;
  80     for (i = 0; i < exts->meths_count; i++, meth++)
  81         meth->ext_flags = 0;
  82 }
  83
  84 /* Pass received custom extension data to the application for parsing. */
  85 int custom_ext_parse(SSL *s, int server,
  86                      unsigned int ext_type,
  87                      const unsigned char *ext_data, size_t ext_size, int *al)
  88 {
  89     custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
  90     custom_ext_method *meth;
  91     meth = custom_ext_find(exts, ext_type);
  92     /* If not found return success */
  93     if (!meth)
  94         return 1;
  95     if (!server) {
  96         /*
  97          * If it's ServerHello we can't have any extensions not sent in
  98          * ClientHello.
  99          */
 100         if (!(meth->ext_flags & SSL_EXT_FLAG_SENT)) {
 101             *al = TLS1_AD_UNSUPPORTED_EXTENSION;
 102             return 0;
 103         }
 104     }
 105     /* If already present it's a duplicate */
 106     if (meth->ext_flags & SSL_EXT_FLAG_RECEIVED) {
 107         *al = TLS1_AD_DECODE_ERROR;
 108         return 0;
 109     }
 110     meth->ext_flags |= SSL_EXT_FLAG_RECEIVED;
 111     /* If no parse function set return success */
 112     if (!meth->parse_cb)
 113         return 1;
 114
 115     return meth->parse_cb(s, ext_type, ext_data, ext_size, al,
 116                           meth->parse_arg);
 117 }
 118
 119 /*
 120  * Request custom extension data from the application and add to the return
 121  * buffer.
 122  */
 123 int custom_ext_add(SSL *s, int server,
 124                    unsigned char **pret, unsigned char *limit, int *al)
 125 {
 126     custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
 127     custom_ext_method *meth;
 128     unsigned char *ret = *pret;
 129     size_t i;
 130
 131     for (i = 0; i < exts->meths_count; i++) {
 132         const unsigned char *out = NULL;
 133         size_t outlen = 0;
 134         meth = exts->meths + i;
 135
 136         if (server) {
 137             /*
 138              * For ServerHello only send extensions present in ClientHello.
 139              */
 140             if (!(meth->ext_flags & SSL_EXT_FLAG_RECEIVED))
 141                 continue;
 142             /* If callback absent for server skip it */
 143             if (!meth->add_cb)
 144                 continue;
 145         }
 146         if (meth->add_cb) {
 147             int cb_retval = 0;
 148             cb_retval = meth->add_cb(s, meth->ext_type,
 149                                      &out, &outlen, al, meth->add_arg);
 150             if (cb_retval < 0)
 151                 return 0;       /* error */
 152             if (cb_retval == 0)
 153                 continue;       /* skip this extension */
 154         }
 155         if (4 > limit - ret || outlen > (size_t)(limit - ret - 4))
 156             return 0;
 157         s2n(meth->ext_type, ret);
 158         s2n(outlen, ret);
 159         if (outlen) {
 160             memcpy(ret, out, outlen);
 161             ret += outlen;
 162         }
 163         /*
 164          * We can't send duplicates: code logic should prevent this.
 165          */
 166         OPENSSL_assert(!(meth->ext_flags & SSL_EXT_FLAG_SENT));
 167         /*
 168          * Indicate extension has been sent: this is both a sanity check to
 169          * ensure we don't send duplicate extensions and indicates that it is
 170          * not an error if the extension is present in ServerHello.
 171          */
 172         meth->ext_flags |= SSL_EXT_FLAG_SENT;
 173         if (meth->free_cb)
 174             meth->free_cb(s, meth->ext_type, out, meth->add_arg);
 175     }
 176     *pret = ret;
 177     return 1;
 178 }
 179
 180 /* Copy table of custom extensions */
 181 int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src)
 182 {
 183     if (src->meths_count) {
 184         dst->meths =
 185             OPENSSL_memdup(src->meths,
 186                        sizeof(custom_ext_method) * src->meths_count);
 187         if (dst->meths == NULL)
 188             return 0;
 189         dst->meths_count = src->meths_count;
 190     }
 191     return 1;
 192 }
 193
 194 void custom_exts_free(custom_ext_methods *exts)
 195 {
 196     OPENSSL_free(exts->meths);
 197 }
 198
 199 /* Set callbacks for a custom extension. */
 200 static int custom_ext_meth_add(custom_ext_methods *exts,
 201                                unsigned int ext_type,
 202                                custom_ext_add_cb add_cb,
 203                                custom_ext_free_cb free_cb,
 204                                void *add_arg,
 205                                custom_ext_parse_cb parse_cb, void *parse_arg)
 206 {
 207     custom_ext_method *meth;
 208     /*
 209      * Check application error: if add_cb is not set free_cb will never be
 210      * called.
 211      */
 212     if (!add_cb && free_cb)
 213         return 0;
 214     /* Don't add if extension supported internally. */
 215     if (SSL_extension_supported(ext_type))
 216         return 0;
 217     /* Extension type must fit in 16 bits */
 218     if (ext_type > 0xffff)
 219         return 0;
 220     /* Search for duplicate */
 221     if (custom_ext_find(exts, ext_type))
 222         return 0;
 223     exts->meths = OPENSSL_realloc(exts->meths,
 224                                   (exts->meths_count +
 225                                    1) * sizeof(custom_ext_method));
 226
 227     if (!exts->meths) {
 228         exts->meths_count = 0;
 229         return 0;
 230     }
 231
 232     meth = exts->meths + exts->meths_count;
 233     memset(meth, 0, sizeof(*meth));
 234     meth->parse_cb = parse_cb;
 235     meth->add_cb = add_cb;
 236     meth->free_cb = free_cb;
 237     meth->ext_type = ext_type;
 238     meth->add_arg = add_arg;
 239     meth->parse_arg = parse_arg;
 240     exts->meths_count++;
 241     return 1;
 242 }
 243
 244 /* Application level functions to add custom extension callbacks */
 245 int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
 246                                   custom_ext_add_cb add_cb,
 247                                   custom_ext_free_cb free_cb,
 248                                   void *add_arg,
 249                                   custom_ext_parse_cb parse_cb,
 250                                   void *parse_arg)
 251 {
 252     return custom_ext_meth_add(&ctx->cert->cli_ext, ext_type,
 253                                add_cb, free_cb, add_arg, parse_cb, parse_arg);
 254 }
 255
 256 int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
 257                                   custom_ext_add_cb add_cb,
 258                                   custom_ext_free_cb free_cb,
 259                                   void *add_arg,
 260                                   custom_ext_parse_cb parse_cb,
 261                                   void *parse_arg)
 262 {
 263     return custom_ext_meth_add(&ctx->cert->srv_ext, ext_type,
 264                                add_cb, free_cb, add_arg, parse_cb, parse_arg);
 265 }
 266
 267 int SSL_extension_supported(unsigned int ext_type)
 268 {
 269     switch (ext_type) {
 270         /* Internally supported extensions. */
 271     case TLSEXT_TYPE_application_layer_protocol_negotiation:
 272     case TLSEXT_TYPE_ec_point_formats:
 273     case TLSEXT_TYPE_elliptic_curves:
 274     case TLSEXT_TYPE_heartbeat:
 275     case TLSEXT_TYPE_next_proto_neg:
 276     case TLSEXT_TYPE_padding:
 277     case TLSEXT_TYPE_renegotiate:
 278     case TLSEXT_TYPE_server_name:
 279     case TLSEXT_TYPE_session_ticket:
 280     case TLSEXT_TYPE_signature_algorithms:
 281     case TLSEXT_TYPE_srp:
 282     case TLSEXT_TYPE_status_request:
 283     case TLSEXT_TYPE_use_srtp:
 284 #ifdef TLSEXT_TYPE_encrypt_then_mac
 285     case TLSEXT_TYPE_encrypt_then_mac:
 286 #endif
 287         return 1;
 288     default:
 289         return 0;
 290     }
 291 }