t1_ext.c revision 325335 
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. */
63static 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 */
78void 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. */
87int 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 */
125int 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 the flags from src to dst for any extensions that exist in both */
183int custom_exts_copy_flags(custom_ext_methods *dst,
184                           const custom_ext_methods *src)
185{
186    size_t i;
187    custom_ext_method *methsrc = src->meths;
188
189    for (i = 0; i < src->meths_count; i++, methsrc++) {
190        custom_ext_method *methdst = custom_ext_find(dst, methsrc->ext_type);
191
192        if (methdst == NULL)
193            continue;
194
195        methdst->ext_flags = methsrc->ext_flags;
196    }
197
198    return 1;
199}
200
201/* Copy table of custom extensions */
202int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src)
203{
204    if (src->meths_count) {
205        dst->meths =
206            BUF_memdup(src->meths,
207                       sizeof(custom_ext_method) * src->meths_count);
208        if (dst->meths == NULL)
209            return 0;
210        dst->meths_count = src->meths_count;
211    }
212    return 1;
213}
214
215void custom_exts_free(custom_ext_methods *exts)
216{
217    if (exts->meths)
218        OPENSSL_free(exts->meths);
219}
220
221/* Set callbacks for a custom extension. */
222static int custom_ext_meth_add(custom_ext_methods *exts,
223                               unsigned int ext_type,
224                               custom_ext_add_cb add_cb,
225                               custom_ext_free_cb free_cb,
226                               void *add_arg,
227                               custom_ext_parse_cb parse_cb, void *parse_arg)
228{
229    custom_ext_method *meth;
230    /*
231     * Check application error: if add_cb is not set free_cb will never be
232     * called.
233     */
234    if (!add_cb && free_cb)
235        return 0;
236    /* Don't add if extension supported internally. */
237    if (SSL_extension_supported(ext_type))
238        return 0;
239    /* Extension type must fit in 16 bits */
240    if (ext_type > 0xffff)
241        return 0;
242    /* Search for duplicate */
243    if (custom_ext_find(exts, ext_type))
244        return 0;
245    meth = OPENSSL_realloc(exts->meths,
246                           (exts->meths_count + 1)
247                           * sizeof(custom_ext_method));
248    if (meth == NULL)
249        return 0;
250
251    exts->meths = meth;
252    meth += exts->meths_count;
253    memset(meth, 0, sizeof(custom_ext_method));
254    meth->parse_cb = parse_cb;
255    meth->add_cb = add_cb;
256    meth->free_cb = free_cb;
257    meth->ext_type = ext_type;
258    meth->add_arg = add_arg;
259    meth->parse_arg = parse_arg;
260    exts->meths_count++;
261    return 1;
262}
263
264/* Application level functions to add custom extension callbacks */
265int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
266                                  custom_ext_add_cb add_cb,
267                                  custom_ext_free_cb free_cb,
268                                  void *add_arg,
269                                  custom_ext_parse_cb parse_cb,
270                                  void *parse_arg)
271{
272    return custom_ext_meth_add(&ctx->cert->cli_ext, ext_type,
273                               add_cb, free_cb, add_arg, parse_cb, parse_arg);
274}
275
276int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
277                                  custom_ext_add_cb add_cb,
278                                  custom_ext_free_cb free_cb,
279                                  void *add_arg,
280                                  custom_ext_parse_cb parse_cb,
281                                  void *parse_arg)
282{
283    return custom_ext_meth_add(&ctx->cert->srv_ext, ext_type,
284                               add_cb, free_cb, add_arg, parse_cb, parse_arg);
285}
286
287int SSL_extension_supported(unsigned int ext_type)
288{
289    switch (ext_type) {
290        /* Internally supported extensions. */
291    case TLSEXT_TYPE_application_layer_protocol_negotiation:
292    case TLSEXT_TYPE_ec_point_formats:
293    case TLSEXT_TYPE_elliptic_curves:
294    case TLSEXT_TYPE_heartbeat:
295# ifndef OPENSSL_NO_NEXTPROTONEG
296    case TLSEXT_TYPE_next_proto_neg:
297# endif
298    case TLSEXT_TYPE_padding:
299    case TLSEXT_TYPE_renegotiate:
300    case TLSEXT_TYPE_server_name:
301    case TLSEXT_TYPE_session_ticket:
302    case TLSEXT_TYPE_signature_algorithms:
303    case TLSEXT_TYPE_srp:
304    case TLSEXT_TYPE_status_request:
305    case TLSEXT_TYPE_use_srtp:
306# ifdef TLSEXT_TYPE_opaque_prf_input
307    case TLSEXT_TYPE_opaque_prf_input:
308# endif
309# ifdef TLSEXT_TYPE_encrypt_then_mac
310    case TLSEXT_TYPE_encrypt_then_mac:
311# endif
312        return 1;
313    default:
314        return 0;
315    }
316}
317#endif
318