1 /* Copyright (c) 2014, Google Inc.
2 *
3 * Permission to use, copy, modify, and/or distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
14
15 #include <openssl/ssl.h>
16
17 #include <assert.h>
18 #include <string.h>
19
20 #include <openssl/bytestring.h>
21 #include <openssl/err.h>
22 #include <openssl/mem.h>
23 #include <openssl/stack.h>
24
25 #include "internal.h"
26
27
SSL_CUSTOM_EXTENSION_free(SSL_CUSTOM_EXTENSION * custom_extension)28 void SSL_CUSTOM_EXTENSION_free(SSL_CUSTOM_EXTENSION *custom_extension) {
29 OPENSSL_free(custom_extension);
30 }
31
custom_ext_find(STACK_OF (SSL_CUSTOM_EXTENSION)* stack,unsigned * out_index,uint16_t value)32 static const SSL_CUSTOM_EXTENSION *custom_ext_find(
33 STACK_OF(SSL_CUSTOM_EXTENSION) *stack,
34 unsigned *out_index, uint16_t value) {
35 size_t i;
36 for (i = 0; i < sk_SSL_CUSTOM_EXTENSION_num(stack); i++) {
37 const SSL_CUSTOM_EXTENSION *ext = sk_SSL_CUSTOM_EXTENSION_value(stack, i);
38 if (ext->value == value) {
39 if (out_index != NULL) {
40 *out_index = i;
41 }
42 return ext;
43 }
44 }
45
46 return NULL;
47 }
48
49 /* default_add_callback is used as the |add_callback| when the user doesn't
50 * provide one. For servers, it does nothing while, for clients, it causes an
51 * empty extension to be included. */
default_add_callback(SSL * ssl,unsigned extension_value,const uint8_t ** out,size_t * out_len,int * out_alert_value,void * add_arg)52 static int default_add_callback(SSL *ssl, unsigned extension_value,
53 const uint8_t **out, size_t *out_len,
54 int *out_alert_value, void *add_arg) {
55 if (ssl->server) {
56 return 0;
57 }
58 *out_len = 0;
59 return 1;
60 }
61
custom_ext_add_hello(SSL * ssl,CBB * extensions)62 static int custom_ext_add_hello(SSL *ssl, CBB *extensions) {
63 STACK_OF(SSL_CUSTOM_EXTENSION) *stack = ssl->ctx->client_custom_extensions;
64 if (ssl->server) {
65 stack = ssl->ctx->server_custom_extensions;
66 }
67
68 if (stack == NULL) {
69 return 1;
70 }
71
72 size_t i;
73 for (i = 0; i < sk_SSL_CUSTOM_EXTENSION_num(stack); i++) {
74 const SSL_CUSTOM_EXTENSION *ext = sk_SSL_CUSTOM_EXTENSION_value(stack, i);
75
76 if (ssl->server &&
77 !(ssl->s3->tmp.custom_extensions.received & (1u << i))) {
78 /* Servers cannot echo extensions that the client didn't send. */
79 continue;
80 }
81
82 const uint8_t *contents;
83 size_t contents_len;
84 int alert = SSL_AD_DECODE_ERROR;
85 CBB contents_cbb;
86
87 switch (ext->add_callback(ssl, ext->value, &contents, &contents_len, &alert,
88 ext->add_arg)) {
89 case 1:
90 if (!CBB_add_u16(extensions, ext->value) ||
91 !CBB_add_u16_length_prefixed(extensions, &contents_cbb) ||
92 !CBB_add_bytes(&contents_cbb, contents, contents_len) ||
93 !CBB_flush(extensions)) {
94 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
95 ERR_add_error_dataf("extension: %u", (unsigned) ext->value);
96 if (ext->free_callback && 0 < contents_len) {
97 ext->free_callback(ssl, ext->value, contents, ext->add_arg);
98 }
99 return 0;
100 }
101
102 if (ext->free_callback && 0 < contents_len) {
103 ext->free_callback(ssl, ext->value, contents, ext->add_arg);
104 }
105
106 if (!ssl->server) {
107 assert((ssl->s3->tmp.custom_extensions.sent & (1u << i)) == 0);
108 ssl->s3->tmp.custom_extensions.sent |= (1u << i);
109 }
110 break;
111
112 case 0:
113 break;
114
115 default:
116 ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
117 OPENSSL_PUT_ERROR(SSL, SSL_R_CUSTOM_EXTENSION_ERROR);
118 ERR_add_error_dataf("extension: %u", (unsigned) ext->value);
119 return 0;
120 }
121 }
122
123 return 1;
124 }
125
custom_ext_add_clienthello(SSL * ssl,CBB * extensions)126 int custom_ext_add_clienthello(SSL *ssl, CBB *extensions) {
127 return custom_ext_add_hello(ssl, extensions);
128 }
129
custom_ext_parse_serverhello(SSL * ssl,int * out_alert,uint16_t value,const CBS * extension)130 int custom_ext_parse_serverhello(SSL *ssl, int *out_alert, uint16_t value,
131 const CBS *extension) {
132 unsigned index;
133 const SSL_CUSTOM_EXTENSION *ext =
134 custom_ext_find(ssl->ctx->client_custom_extensions, &index, value);
135
136 if (/* Unknown extensions are not allowed in a ServerHello. */
137 ext == NULL ||
138 /* Also, if we didn't send the extension, that's also unacceptable. */
139 !(ssl->s3->tmp.custom_extensions.sent & (1u << index))) {
140 OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
141 ERR_add_error_dataf("extension: %u", (unsigned)value);
142 *out_alert = SSL_AD_DECODE_ERROR;
143 return 0;
144 }
145
146 if (ext->parse_callback != NULL &&
147 !ext->parse_callback(ssl, value, CBS_data(extension), CBS_len(extension),
148 out_alert, ext->parse_arg)) {
149 OPENSSL_PUT_ERROR(SSL, SSL_R_CUSTOM_EXTENSION_ERROR);
150 ERR_add_error_dataf("extension: %u", (unsigned)ext->value);
151 return 0;
152 }
153
154 return 1;
155 }
156
custom_ext_parse_clienthello(SSL * ssl,int * out_alert,uint16_t value,const CBS * extension)157 int custom_ext_parse_clienthello(SSL *ssl, int *out_alert, uint16_t value,
158 const CBS *extension) {
159 unsigned index;
160 const SSL_CUSTOM_EXTENSION *ext =
161 custom_ext_find(ssl->ctx->server_custom_extensions, &index, value);
162
163 if (ext == NULL) {
164 return 1;
165 }
166
167 assert((ssl->s3->tmp.custom_extensions.received & (1u << index)) == 0);
168 ssl->s3->tmp.custom_extensions.received |= (1u << index);
169
170 if (ext->parse_callback &&
171 !ext->parse_callback(ssl, value, CBS_data(extension), CBS_len(extension),
172 out_alert, ext->parse_arg)) {
173 OPENSSL_PUT_ERROR(SSL, SSL_R_CUSTOM_EXTENSION_ERROR);
174 ERR_add_error_dataf("extension: %u", (unsigned)ext->value);
175 return 0;
176 }
177
178 return 1;
179 }
180
custom_ext_add_serverhello(SSL * ssl,CBB * extensions)181 int custom_ext_add_serverhello(SSL *ssl, CBB *extensions) {
182 return custom_ext_add_hello(ssl, extensions);
183 }
184
185 /* MAX_NUM_CUSTOM_EXTENSIONS is the maximum number of custom extensions that
186 * can be set on an |SSL_CTX|. It's determined by the size of the bitset used
187 * to track when an extension has been sent. */
188 #define MAX_NUM_CUSTOM_EXTENSIONS \
189 (sizeof(((struct ssl3_state_st *)NULL)->tmp.custom_extensions.sent) * 8)
190
custom_ext_append(STACK_OF (SSL_CUSTOM_EXTENSION)** stack,unsigned extension_value,SSL_custom_ext_add_cb add_cb,SSL_custom_ext_free_cb free_cb,void * add_arg,SSL_custom_ext_parse_cb parse_cb,void * parse_arg)191 static int custom_ext_append(STACK_OF(SSL_CUSTOM_EXTENSION) **stack,
192 unsigned extension_value,
193 SSL_custom_ext_add_cb add_cb,
194 SSL_custom_ext_free_cb free_cb, void *add_arg,
195 SSL_custom_ext_parse_cb parse_cb,
196 void *parse_arg) {
197 if (add_cb == NULL ||
198 0xffff < extension_value ||
199 SSL_extension_supported(extension_value) ||
200 /* Specifying a free callback without an add callback is nonsensical
201 * and an error. */
202 (*stack != NULL &&
203 (MAX_NUM_CUSTOM_EXTENSIONS <= sk_SSL_CUSTOM_EXTENSION_num(*stack) ||
204 custom_ext_find(*stack, NULL, extension_value) != NULL))) {
205 return 0;
206 }
207
208 SSL_CUSTOM_EXTENSION *ext = OPENSSL_malloc(sizeof(SSL_CUSTOM_EXTENSION));
209 if (ext == NULL) {
210 return 0;
211 }
212 ext->add_callback = add_cb;
213 ext->add_arg = add_arg;
214 ext->free_callback = free_cb;
215 ext->parse_callback = parse_cb;
216 ext->parse_arg = parse_arg;
217 ext->value = extension_value;
218
219 if (*stack == NULL) {
220 *stack = sk_SSL_CUSTOM_EXTENSION_new_null();
221 if (*stack == NULL) {
222 SSL_CUSTOM_EXTENSION_free(ext);
223 return 0;
224 }
225 }
226
227 if (!sk_SSL_CUSTOM_EXTENSION_push(*stack, ext)) {
228 SSL_CUSTOM_EXTENSION_free(ext);
229 if (sk_SSL_CUSTOM_EXTENSION_num(*stack) == 0) {
230 sk_SSL_CUSTOM_EXTENSION_free(*stack);
231 *stack = NULL;
232 }
233 return 0;
234 }
235
236 return 1;
237 }
238
SSL_CTX_add_client_custom_ext(SSL_CTX * ctx,unsigned extension_value,SSL_custom_ext_add_cb add_cb,SSL_custom_ext_free_cb free_cb,void * add_arg,SSL_custom_ext_parse_cb parse_cb,void * parse_arg)239 int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned extension_value,
240 SSL_custom_ext_add_cb add_cb,
241 SSL_custom_ext_free_cb free_cb, void *add_arg,
242 SSL_custom_ext_parse_cb parse_cb,
243 void *parse_arg) {
244 return custom_ext_append(&ctx->client_custom_extensions, extension_value,
245 add_cb ? add_cb : default_add_callback, free_cb,
246 add_arg, parse_cb, parse_arg);
247 }
248
SSL_CTX_add_server_custom_ext(SSL_CTX * ctx,unsigned extension_value,SSL_custom_ext_add_cb add_cb,SSL_custom_ext_free_cb free_cb,void * add_arg,SSL_custom_ext_parse_cb parse_cb,void * parse_arg)249 int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned extension_value,
250 SSL_custom_ext_add_cb add_cb,
251 SSL_custom_ext_free_cb free_cb, void *add_arg,
252 SSL_custom_ext_parse_cb parse_cb,
253 void *parse_arg) {
254 return custom_ext_append(&ctx->server_custom_extensions, extension_value,
255 add_cb ? add_cb : default_add_callback, free_cb,
256 add_arg, parse_cb, parse_arg);
257 }
258