1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
|
/*
* Copyright (c) 2007, Cameron Rich
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* * Neither the name of the axTLS project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "os_port.h"
#include "ssl.h"
static const uint8_t g_hello_done[] = { HS_SERVER_HELLO_DONE, 0, 0, 0 };
static int process_client_hello(SSL *ssl);
static int send_server_hello_sequence(SSL *ssl);
static int send_server_hello(SSL *ssl);
static int send_server_hello_done(SSL *ssl);
static int process_client_key_xchg(SSL *ssl);
#ifdef CONFIG_SSL_CERT_VERIFICATION
static int send_certificate_request(SSL *ssl);
static int process_cert_verify(SSL *ssl);
#endif
/*
* Establish a new SSL connection to an SSL client.
*/
EXP_FUNC SSL * STDCALL ssl_server_new(SSL_CTX *ssl_ctx, int client_fd)
{
SSL *ssl;
ssl = ssl_new(ssl_ctx, client_fd);
ssl->next_state = HS_CLIENT_HELLO;
#ifdef CONFIG_SSL_FULL_MODE
if (ssl_ctx->chain_length == 0)
printf("Warning - no server certificate defined\n"); TTY_FLUSH();
#endif
return ssl;
}
/*
* Process the handshake record.
*/
int do_svr_handshake(SSL *ssl, int handshake_type, uint8_t *buf, int hs_len)
{
int ret = SSL_OK;
ssl->hs_status = SSL_NOT_OK; /* not connected */
/* To get here the state must be valid */
switch (handshake_type)
{
case HS_CLIENT_HELLO:
if ((ret = process_client_hello(ssl)) == SSL_OK)
ret = send_server_hello_sequence(ssl);
break;
#ifdef CONFIG_SSL_CERT_VERIFICATION
case HS_CERTIFICATE:/* the client sends its cert */
ret = process_certificate(ssl, &ssl->x509_ctx);
if (ret == SSL_OK) /* verify the cert */
{
int cert_res;
cert_res = x509_verify(
ssl->ssl_ctx->ca_cert_ctx, ssl->x509_ctx);
ret = (cert_res == 0) ? SSL_OK : SSL_X509_ERROR(cert_res);
}
break;
case HS_CERT_VERIFY:
ret = process_cert_verify(ssl);
add_packet(ssl, buf, hs_len); /* needs to be done after */
break;
#endif
case HS_CLIENT_KEY_XCHG:
ret = process_client_key_xchg(ssl);
break;
case HS_FINISHED:
ret = process_finished(ssl, buf, hs_len);
disposable_free(ssl); /* free up some memory */
break;
}
return ret;
}
/*
* Process a client hello message.
*/
static int process_client_hello(SSL *ssl)
{
uint8_t *buf = ssl->bm_data;
uint8_t *record_buf = ssl->hmac_header;
int pkt_size = ssl->bm_index;
int i, j, cs_len, id_len, offset = 6 + SSL_RANDOM_SIZE;
int ret = SSL_OK;
uint8_t version = (buf[4] << 4) + buf[5];
ssl->version = ssl->client_version = version;
if (version > SSL_PROTOCOL_VERSION_MAX)
{
/* use client's version instead */
ssl->version = SSL_PROTOCOL_VERSION_MAX;
}
else if (version < SSL_PROTOCOL_MIN_VERSION) /* old version supported? */
{
ret = SSL_ERROR_INVALID_VERSION;
ssl_display_error(ret);
goto error;
}
memcpy(ssl->dc->client_random, &buf[6], SSL_RANDOM_SIZE);
/* process the session id */
id_len = buf[offset++];
if (id_len > SSL_SESSION_ID_SIZE)
{
return SSL_ERROR_INVALID_SESSION;
}
#ifndef CONFIG_SSL_SKELETON_MODE
ssl->session = ssl_session_update(ssl->ssl_ctx->num_sessions,
ssl->ssl_ctx->ssl_sessions, ssl, id_len ? &buf[offset] : NULL);
#endif
offset += id_len;
cs_len = (buf[offset]<<8) + buf[offset+1];
offset += 3; /* add 1 due to all cipher suites being 8 bit */
PARANOIA_CHECK(pkt_size, offset);
/* work out what cipher suite we are going to use - client defines
the preference */
for (i = 0; i < cs_len; i += 2)
{
for (j = 0; j < NUM_PROTOCOLS; j++)
{
if (ssl_prot_prefs[j] == buf[offset+i]) /* got a match? */
{
ssl->cipher = ssl_prot_prefs[j];
goto do_state;
}
}
}
/* ouch! protocol is not supported */
ret = SSL_ERROR_NO_CIPHER;
do_state:
error:
return ret;
}
#ifdef CONFIG_SSL_ENABLE_V23_HANDSHAKE
/*
* Some browsers use a hybrid SSLv2 "client hello"
*/
int process_sslv23_client_hello(SSL *ssl)
{
uint8_t *buf = ssl->bm_data;
int bytes_needed = ((buf[0] & 0x7f) << 8) + buf[1];
int ret = SSL_OK;
/* we have already read 3 extra bytes so far */
int read_len = SOCKET_READ(ssl->client_fd, buf, bytes_needed-3);
int cs_len = buf[1];
int id_len = buf[3];
int ch_len = buf[5];
int i, j, offset = 8; /* start at first cipher */
int random_offset = 0;
DISPLAY_BYTES(ssl, "received %d bytes", buf, read_len, read_len);
add_packet(ssl, buf, read_len);
/* connection has gone, so die */
if (bytes_needed < 0)
{
return SSL_ERROR_CONN_LOST;
}
/* now work out what cipher suite we are going to use */
for (j = 0; j < NUM_PROTOCOLS; j++)
{
for (i = 0; i < cs_len; i += 3)
{
if (ssl_prot_prefs[j] == buf[offset+i])
{
ssl->cipher = ssl_prot_prefs[j];
goto server_hello;
}
}
}
/* ouch! protocol is not supported */
ret = SSL_ERROR_NO_CIPHER;
goto error;
server_hello:
/* get the session id */
offset += cs_len - 2; /* we've gone 2 bytes past the end */
#ifndef CONFIG_SSL_SKELETON_MODE
ssl->session = ssl_session_update(ssl->ssl_ctx->num_sessions,
ssl->ssl_ctx->ssl_sessions, ssl, id_len ? &buf[offset] : NULL);
#endif
/* get the client random data */
offset += id_len;
/* random can be anywhere between 16 and 32 bytes long - so it is padded
* with 0's to the left */
if (ch_len == 0x10)
{
random_offset += 0x10;
}
memcpy(&ssl->dc->client_random[random_offset], &buf[offset], ch_len);
ret = send_server_hello_sequence(ssl);
error:
return ret;
}
#endif
/*
* Send the entire server hello sequence
*/
static int send_server_hello_sequence(SSL *ssl)
{
int ret;
if ((ret = send_server_hello(ssl)) == SSL_OK)
{
#ifndef CONFIG_SSL_SKELETON_MODE
/* resume handshake? */
if (IS_SET_SSL_FLAG(SSL_SESSION_RESUME))
{
if ((ret = send_change_cipher_spec(ssl)) == SSL_OK)
{
ret = send_finished(ssl);
ssl->next_state = HS_FINISHED;
}
}
else
#endif
if ((ret = send_certificate(ssl)) == SSL_OK)
{
#ifdef CONFIG_SSL_CERT_VERIFICATION
/* ask the client for its certificate */
if (IS_SET_SSL_FLAG(SSL_CLIENT_AUTHENTICATION))
{
if ((ret = send_certificate_request(ssl)) == SSL_OK)
{
ret = send_server_hello_done(ssl);
ssl->next_state = HS_CERTIFICATE;
}
}
else
#endif
{
ret = send_server_hello_done(ssl);
ssl->next_state = HS_CLIENT_KEY_XCHG;
}
}
}
return ret;
}
/*
* Send a server hello message.
*/
static int send_server_hello(SSL *ssl)
{
uint8_t *buf = ssl->bm_data;
int offset = 0;
buf[0] = HS_SERVER_HELLO;
buf[1] = 0;
buf[2] = 0;
/* byte 3 is calculated later */
buf[4] = 0x03;
buf[5] = ssl->version & 0x0f;
/* server random value */
get_random(SSL_RANDOM_SIZE, &buf[6]);
memcpy(ssl->dc->server_random, &buf[6], SSL_RANDOM_SIZE);
offset = 6 + SSL_RANDOM_SIZE;
#ifndef CONFIG_SSL_SKELETON_MODE
if (IS_SET_SSL_FLAG(SSL_SESSION_RESUME))
{
/* retrieve id from session cache */
buf[offset++] = SSL_SESSION_ID_SIZE;
memcpy(&buf[offset], ssl->session->session_id, SSL_SESSION_ID_SIZE);
memcpy(ssl->session_id, ssl->session->session_id, SSL_SESSION_ID_SIZE);
ssl->sess_id_size = SSL_SESSION_ID_SIZE;
offset += SSL_SESSION_ID_SIZE;
}
else /* generate our own session id */
#endif
{
#ifndef CONFIG_SSL_SKELETON_MODE
buf[offset++] = SSL_SESSION_ID_SIZE;
get_random(SSL_SESSION_ID_SIZE, &buf[offset]);
memcpy(ssl->session_id, &buf[offset], SSL_SESSION_ID_SIZE);
ssl->sess_id_size = SSL_SESSION_ID_SIZE;
/* store id in session cache */
if (ssl->ssl_ctx->num_sessions)
{
memcpy(ssl->session->session_id,
ssl->session_id, SSL_SESSION_ID_SIZE);
}
offset += SSL_SESSION_ID_SIZE;
#else
buf[offset++] = 0; /* don't bother with session id in skelton mode */
#endif
}
buf[offset++] = 0; /* cipher we are using */
buf[offset++] = ssl->cipher;
buf[offset++] = 0; /* no compression */
buf[3] = offset - 4; /* handshake size */
return send_packet(ssl, PT_HANDSHAKE_PROTOCOL, NULL, offset);
}
/*
* Send the server hello done message.
*/
static int send_server_hello_done(SSL *ssl)
{
return send_packet(ssl, PT_HANDSHAKE_PROTOCOL,
g_hello_done, sizeof(g_hello_done));
}
/*
* Pull apart a client key exchange message. Decrypt the pre-master key (using
* our RSA private key) and then work out the master key. Initialise the
* ciphers.
*/
static int process_client_key_xchg(SSL *ssl)
{
uint8_t *buf = &ssl->bm_data[ssl->dc->bm_proc_index];
int pkt_size = ssl->bm_index;
int premaster_size, secret_length = (buf[2] << 8) + buf[3];
uint8_t premaster_secret[MAX_KEY_BYTE_SIZE];
RSA_CTX *rsa_ctx = ssl->ssl_ctx->rsa_ctx;
int offset = 4;
int ret = SSL_OK;
if (rsa_ctx == NULL)
{
ret = SSL_ERROR_NO_CERT_DEFINED;
goto error;
}
/* is there an extra size field? */
if ((secret_length - 2) == rsa_ctx->num_octets)
offset += 2;
PARANOIA_CHECK(pkt_size, rsa_ctx->num_octets+offset);
/* rsa_ctx->bi_ctx is not thread-safe */
SSL_CTX_LOCK(ssl->ssl_ctx->mutex);
premaster_size = RSA_decrypt(rsa_ctx, &buf[offset], premaster_secret, 1);
SSL_CTX_UNLOCK(ssl->ssl_ctx->mutex);
if (premaster_size != SSL_SECRET_SIZE ||
premaster_secret[0] != 0x03 || /* must be the same as client
offered version */
premaster_secret[1] != (ssl->client_version & 0x0f))
{
/* guard against a Bleichenbacher attack */
get_random(SSL_SECRET_SIZE, premaster_secret);
/* and continue - will die eventually when checking the mac */
}
#if 0
print_blob("pre-master", premaster_secret, SSL_SECRET_SIZE);
#endif
generate_master_secret(ssl, premaster_secret);
#ifdef CONFIG_SSL_CERT_VERIFICATION
ssl->next_state = IS_SET_SSL_FLAG(SSL_CLIENT_AUTHENTICATION) ?
HS_CERT_VERIFY : HS_FINISHED;
#else
ssl->next_state = HS_FINISHED;
#endif
ssl->dc->bm_proc_index += rsa_ctx->num_octets+offset;
error:
return ret;
}
#ifdef CONFIG_SSL_CERT_VERIFICATION
static const uint8_t g_cert_request[] = { HS_CERT_REQ, 0, 0, 4, 1, 0, 0, 0 };
/*
* Send the certificate request message.
*/
static int send_certificate_request(SSL *ssl)
{
return send_packet(ssl, PT_HANDSHAKE_PROTOCOL,
g_cert_request, sizeof(g_cert_request));
}
/*
* Ensure the client has the private key by first decrypting the packet and
* then checking the packet digests.
*/
static int process_cert_verify(SSL *ssl)
{
uint8_t *buf = &ssl->bm_data[ssl->dc->bm_proc_index];
int pkt_size = ssl->bm_index;
uint8_t dgst_buf[MAX_KEY_BYTE_SIZE];
uint8_t dgst[MD5_SIZE+SHA1_SIZE];
X509_CTX *x509_ctx = ssl->x509_ctx;
int ret = SSL_OK;
int n;
PARANOIA_CHECK(pkt_size, x509_ctx->rsa_ctx->num_octets+6);
DISPLAY_RSA(ssl, x509_ctx->rsa_ctx);
/* rsa_ctx->bi_ctx is not thread-safe */
SSL_CTX_LOCK(ssl->ssl_ctx->mutex);
n = RSA_decrypt(x509_ctx->rsa_ctx, &buf[6], dgst_buf, 0);
SSL_CTX_UNLOCK(ssl->ssl_ctx->mutex);
if (n != SHA1_SIZE + MD5_SIZE)
{
ret = SSL_ERROR_INVALID_KEY;
goto end_cert_vfy;
}
finished_digest(ssl, NULL, dgst); /* calculate the digest */
if (memcmp(dgst_buf, dgst, MD5_SIZE + SHA1_SIZE))
{
ret = SSL_ERROR_INVALID_KEY;
}
end_cert_vfy:
ssl->next_state = HS_FINISHED;
error:
return ret;
}
#endif
|