ssl/t1_ext.c

   1 /* ssl/t1_ext.c */
   2 /* ====================================================================
   3  * Copyright (c) 2014 The OpenSSL Project.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  *
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in
  14  *    the documentation and/or other materials provided with the
  15  *    distribution.
  16  *
  17  * 3. All advertising materials mentioning features or use of this
  18  *    software must display the following acknowledgment:
  19  *    "This product includes software developed by the OpenSSL Project
  20  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  21  *
  22  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  23  *    endorse or promote products derived from this software without
  24  *    prior written permission. For written permission, please contact
  25  *    openssl-core@openssl.org.
  26  *
  27  * 5. Products derived from this software may not be called "OpenSSL"
  28  *    nor may "OpenSSL" appear in their names without prior written
  29  *    permission of the OpenSSL Project.
  30  *
  31  * 6. Redistributions of any form whatsoever must retain the following
  32  *    acknowledgment:
  33  *    "This product includes software developed by the OpenSSL Project
  34  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  35  *
  36  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  37  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  38  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  39  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  40  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  41  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  42  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  43  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  44  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  45  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  46  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  47  * OF THE POSSIBILITY OF SUCH DAMAGE.
  48  * ====================================================================
  49  *
  50  * This product includes cryptographic software written by Eric Young
  51  * (eay@cryptsoft.com).  This product includes software written by Tim
  52  * Hudson (tjh@cryptsoft.com).
  53  *
  54  */
  55
  56 /* Custom extension utility functions */
  57
  58 #include "ssl_locl.h"
  59
  60 #ifndef OPENSSL_NO_TLSEXT
  61
  62 /* Find a custom extension from the list. */
  63 static custom_ext_method *custom_ext_find(custom_ext_methods *exts,
  64                                           unsigned int ext_type)
  65 {
  66     size_t i;
  67     custom_ext_method *meth = exts->meths;
  68     for (i = 0; i < exts->meths_count; i++, meth++) {
  69         if (ext_type == meth->ext_type)
  70             return meth;
  71     }
  72     return NULL;
  73 }
  74
  75 /*
  76  * Initialise custom extensions flags to indicate neither sent nor received.
  77  */
  78 void custom_ext_init(custom_ext_methods *exts)
  79 {
  80     size_t i;
  81     custom_ext_method *meth = exts->meths;
  82     for (i = 0; i < exts->meths_count; i++, meth++)
  83         meth->ext_flags = 0;
  84 }
  85
  86 /* Pass received custom extension data to the application for parsing. */
  87 int custom_ext_parse(SSL *s, int server,
  88                      unsigned int ext_type,
  89                      const unsigned char *ext_data, size_t ext_size, int *al)
  90 {
  91     custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
  92     custom_ext_method *meth;
  93     meth = custom_ext_find(exts, ext_type);
  94     /* If not found return success */
  95     if (!meth)
  96         return 1;
  97     if (!server) {
  98         /*
  99          * If it's ServerHello we can't have any extensions not sent in
 100          * ClientHello.
 101          */
 102         if (!(meth->ext_flags & SSL_EXT_FLAG_SENT)) {
 103             *al = TLS1_AD_UNSUPPORTED_EXTENSION;
 104             return 0;
 105         }
 106     }
 107     /* If already present it's a duplicate */
 108     if (meth->ext_flags & SSL_EXT_FLAG_RECEIVED) {
 109         *al = TLS1_AD_DECODE_ERROR;
 110         return 0;
 111     }
 112     meth->ext_flags |= SSL_EXT_FLAG_RECEIVED;
 113     /* If no parse function set return success */
 114     if (!meth->parse_cb)
 115         return 1;
 116
 117     return meth->parse_cb(s, ext_type, ext_data, ext_size, al,
 118                           meth->parse_arg);
 119 }
 120
 121 /*
 122  * Request custom extension data from the application and add to the return
 123  * buffer.
 124  */
 125 int custom_ext_add(SSL *s, int server,
 126                    unsigned char **pret, unsigned char *limit, int *al)
 127 {
 128     custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
 129     custom_ext_method *meth;
 130     unsigned char *ret = *pret;
 131     size_t i;
 132
 133     for (i = 0; i < exts->meths_count; i++) {
 134         const unsigned char *out = NULL;
 135         size_t outlen = 0;
 136         meth = exts->meths + i;
 137
 138         if (server) {
 139             /*
 140              * For ServerHello only send extensions present in ClientHello.
 141              */
 142             if (!(meth->ext_flags & SSL_EXT_FLAG_RECEIVED))
 143                 continue;
 144             /* If callback absent for server skip it */
 145             if (!meth->add_cb)
 146                 continue;
 147         }
 148         if (meth->add_cb) {
 149             int cb_retval = 0;
 150             cb_retval = meth->add_cb(s, meth->ext_type,
 151                                      &out, &outlen, al, meth->add_arg);
 152             if (cb_retval < 0)
 153                 return 0;       /* error */
 154             if (cb_retval == 0)
 155                 continue;       /* skip this extension */
 156         }
 157         if (4 > limit - ret || outlen > (size_t)(limit - ret - 4))
 158             return 0;
 159         s2n(meth->ext_type, ret);
 160         s2n(outlen, ret);
 161         if (outlen) {
 162             memcpy(ret, out, outlen);
 163             ret += outlen;
 164         }
 165         /*
 166          * We can't send duplicates: code logic should prevent this.
 167          */
 168         OPENSSL_assert(!(meth->ext_flags & SSL_EXT_FLAG_SENT));
 169         /*
 170          * Indicate extension has been sent: this is both a sanity check to
 171          * ensure we don't send duplicate extensions and indicates that it is
 172          * not an error if the extension is present in ServerHello.
 173          */
 174         meth->ext_flags |= SSL_EXT_FLAG_SENT;
 175         if (meth->free_cb)
 176             meth->free_cb(s, meth->ext_type, out, meth->add_arg);
 177     }
 178     *pret = ret;
 179     return 1;
 180 }
 181
 182 /* Copy table of custom extensions */
 183 int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src)
 184 {
 185     if (src->meths_count) {
 186         dst->meths =
 187             BUF_memdup(src->meths,
 188                        sizeof(custom_ext_method) * src->meths_count);
 189         if (dst->meths == NULL)
 190             return 0;
 191         dst->meths_count = src->meths_count;
 192     }
 193     return 1;
 194 }
 195
 196 void custom_exts_free(custom_ext_methods *exts)
 197 {
 198     if (exts->meths)
 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     /* Don't add if extension supported internally. */
 218     if (SSL_extension_supported(ext_type))
 219         return 0;
 220     /* Extension type must fit in 16 bits */
 221     if (ext_type > 0xffff)
 222         return 0;
 223     /* Search for duplicate */
 224     if (custom_ext_find(exts, ext_type))
 225         return 0;
 226     exts->meths = OPENSSL_realloc(exts->meths,
 227                                   (exts->meths_count +
 228                                    1) * sizeof(custom_ext_method));
 229
 230     if (!exts->meths) {
 231         exts->meths_count = 0;
 232         return 0;
 233     }
 234
 235     meth = exts->meths + exts->meths_count;
 236     memset(meth, 0, sizeof(custom_ext_method));
 237     meth->parse_cb = parse_cb;
 238     meth->add_cb = add_cb;
 239     meth->free_cb = free_cb;
 240     meth->ext_type = ext_type;
 241     meth->add_arg = add_arg;
 242     meth->parse_arg = parse_arg;
 243     exts->meths_count++;
 244     return 1;
 245 }
 246
 247 /* Application level functions to add custom extension callbacks */
 248 int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
 249                                   custom_ext_add_cb add_cb,
 250                                   custom_ext_free_cb free_cb,
 251                                   void *add_arg,
 252                                   custom_ext_parse_cb parse_cb,
 253                                   void *parse_arg)
 254 {
 255     return custom_ext_meth_add(&ctx->cert->cli_ext, ext_type,
 256                                add_cb, free_cb, add_arg, parse_cb, parse_arg);
 257 }
 258
 259 int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
 260                                   custom_ext_add_cb add_cb,
 261                                   custom_ext_free_cb free_cb,
 262                                   void *add_arg,
 263                                   custom_ext_parse_cb parse_cb,
 264                                   void *parse_arg)
 265 {
 266     return custom_ext_meth_add(&ctx->cert->srv_ext, ext_type,
 267                                add_cb, free_cb, add_arg, parse_cb, parse_arg);
 268 }
 269
 270 int SSL_extension_supported(unsigned int ext_type)
 271 {
 272     switch (ext_type) {
 273         /* Internally supported extensions. */
 274     case TLSEXT_TYPE_application_layer_protocol_negotiation:
 275     case TLSEXT_TYPE_ec_point_formats:
 276     case TLSEXT_TYPE_elliptic_curves:
 277     case TLSEXT_TYPE_heartbeat:
 278     case TLSEXT_TYPE_next_proto_neg:
 279     case TLSEXT_TYPE_padding:
 280     case TLSEXT_TYPE_renegotiate:
 281     case TLSEXT_TYPE_server_name:
 282     case TLSEXT_TYPE_session_ticket:
 283     case TLSEXT_TYPE_signature_algorithms:
 284     case TLSEXT_TYPE_srp:
 285     case TLSEXT_TYPE_status_request:
 286     case TLSEXT_TYPE_use_srtp:
 287 # ifdef TLSEXT_TYPE_encrypt_then_mac
 288     case TLSEXT_TYPE_encrypt_then_mac:
 289 # endif
 290         return 1;
 291     default:
 292         return 0;
 293     }
 294 }
 295 #endif