t1_ext.c revision 306343 
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 table of custom extensions */
183int 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
196void 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. */
203static 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 */
248int 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
259int 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
270int 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# ifndef OPENSSL_NO_NEXTPROTONEG
279    case TLSEXT_TYPE_next_proto_neg:
280# endif
281    case TLSEXT_TYPE_padding:
282    case TLSEXT_TYPE_renegotiate:
283    case TLSEXT_TYPE_server_name:
284    case TLSEXT_TYPE_session_ticket:
285    case TLSEXT_TYPE_signature_algorithms:
286    case TLSEXT_TYPE_srp:
287    case TLSEXT_TYPE_status_request:
288    case TLSEXT_TYPE_use_srtp:
289# ifdef TLSEXT_TYPE_opaque_prf_input
290    case TLSEXT_TYPE_opaque_prf_input:
291# endif
292# ifdef TLSEXT_TYPE_encrypt_then_mac
293    case TLSEXT_TYPE_encrypt_then_mac:
294# endif
295        return 1;
296    default:
297        return 0;
298    }
299}
300#endif
301