1 |
/* -*- c-basic-offset: 8 -*- |
2 |
rdesktop: A Remote Desktop Protocol client. |
3 |
Protocol services - RDP encryption and licensing |
4 |
Copyright (C) Matthew Chapman 1999-2002 |
5 |
|
6 |
This program is free software; you can redistribute it and/or modify |
7 |
it under the terms of the GNU General Public License as published by |
8 |
the Free Software Foundation; either version 2 of the License, or |
9 |
(at your option) any later version. |
10 |
|
11 |
This program is distributed in the hope that it will be useful, |
12 |
but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 |
GNU General Public License for more details. |
15 |
|
16 |
You should have received a copy of the GNU General Public License |
17 |
along with this program; if not, write to the Free Software |
18 |
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
19 |
*/ |
20 |
|
21 |
#include "rdesktop.h" |
22 |
|
23 |
#ifdef WITH_OPENSSL |
24 |
#include <openssl/rc4.h> |
25 |
#include <openssl/md5.h> |
26 |
#include <openssl/sha.h> |
27 |
#include <openssl/bn.h> |
28 |
#include <openssl/x509v3.h> |
29 |
#else |
30 |
#include "crypto/rc4.h" |
31 |
#include "crypto/md5.h" |
32 |
#include "crypto/sha.h" |
33 |
#include "crypto/bn.h" |
34 |
#endif |
35 |
|
36 |
extern char hostname[16]; |
37 |
extern int width; |
38 |
extern int height; |
39 |
extern int keylayout; |
40 |
extern BOOL encryption; |
41 |
extern BOOL g_licence_issued; |
42 |
extern BOOL use_rdp5; |
43 |
extern int server_bpp; |
44 |
extern uint16 mcs_userid; |
45 |
|
46 |
static int rc4_key_len; |
47 |
static RC4_KEY rc4_decrypt_key; |
48 |
static RC4_KEY rc4_encrypt_key; |
49 |
static RSA *server_public_key; |
50 |
|
51 |
static uint8 sec_sign_key[16]; |
52 |
static uint8 sec_decrypt_key[16]; |
53 |
static uint8 sec_encrypt_key[16]; |
54 |
static uint8 sec_decrypt_update_key[16]; |
55 |
static uint8 sec_encrypt_update_key[16]; |
56 |
static uint8 sec_crypted_random[SEC_MODULUS_SIZE]; |
57 |
|
58 |
uint16 server_rdp_version = 0; |
59 |
|
60 |
/* |
61 |
* General purpose 48-byte transformation, using two 32-byte salts (generally, |
62 |
* a client and server salt) and a global salt value used for padding. |
63 |
* Both SHA1 and MD5 algorithms are used. |
64 |
*/ |
65 |
void |
66 |
sec_hash_48(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2, uint8 salt) |
67 |
{ |
68 |
uint8 shasig[20]; |
69 |
uint8 pad[4]; |
70 |
SHA_CTX sha; |
71 |
MD5_CTX md5; |
72 |
int i; |
73 |
|
74 |
for (i = 0; i < 3; i++) |
75 |
{ |
76 |
memset(pad, salt + i, i + 1); |
77 |
|
78 |
SHA1_Init(&sha); |
79 |
SHA1_Update(&sha, pad, i + 1); |
80 |
SHA1_Update(&sha, in, 48); |
81 |
SHA1_Update(&sha, salt1, 32); |
82 |
SHA1_Update(&sha, salt2, 32); |
83 |
SHA1_Final(shasig, &sha); |
84 |
|
85 |
MD5_Init(&md5); |
86 |
MD5_Update(&md5, in, 48); |
87 |
MD5_Update(&md5, shasig, 20); |
88 |
MD5_Final(&out[i * 16], &md5); |
89 |
} |
90 |
} |
91 |
|
92 |
/* |
93 |
* Weaker 16-byte transformation, also using two 32-byte salts, but |
94 |
* only using a single round of MD5. |
95 |
*/ |
96 |
void |
97 |
sec_hash_16(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2) |
98 |
{ |
99 |
MD5_CTX md5; |
100 |
|
101 |
MD5_Init(&md5); |
102 |
MD5_Update(&md5, in, 16); |
103 |
MD5_Update(&md5, salt1, 32); |
104 |
MD5_Update(&md5, salt2, 32); |
105 |
MD5_Final(out, &md5); |
106 |
} |
107 |
|
108 |
/* Reduce key entropy from 64 to 40 bits */ |
109 |
static void |
110 |
sec_make_40bit(uint8 * key) |
111 |
{ |
112 |
key[0] = 0xd1; |
113 |
key[1] = 0x26; |
114 |
key[2] = 0x9e; |
115 |
} |
116 |
|
117 |
/* Generate a session key and RC4 keys, given client and server randoms */ |
118 |
static void |
119 |
sec_generate_keys(uint8 * client_key, uint8 * server_key, int rc4_key_size) |
120 |
{ |
121 |
uint8 session_key[48]; |
122 |
uint8 temp_hash[48]; |
123 |
uint8 input[48]; |
124 |
|
125 |
/* Construct input data to hash */ |
126 |
memcpy(input, client_key, 24); |
127 |
memcpy(input + 24, server_key, 24); |
128 |
|
129 |
/* Generate session key - two rounds of sec_hash_48 */ |
130 |
sec_hash_48(temp_hash, input, client_key, server_key, 65); |
131 |
sec_hash_48(session_key, temp_hash, client_key, server_key, 88); |
132 |
|
133 |
/* Store first 16 bytes of session key, for generating signatures */ |
134 |
memcpy(sec_sign_key, session_key, 16); |
135 |
|
136 |
/* Generate RC4 keys */ |
137 |
sec_hash_16(sec_decrypt_key, &session_key[16], client_key, server_key); |
138 |
sec_hash_16(sec_encrypt_key, &session_key[32], client_key, server_key); |
139 |
|
140 |
if (rc4_key_size == 1) |
141 |
{ |
142 |
DEBUG(("40-bit encryption enabled\n")); |
143 |
sec_make_40bit(sec_sign_key); |
144 |
sec_make_40bit(sec_decrypt_key); |
145 |
sec_make_40bit(sec_encrypt_key); |
146 |
rc4_key_len = 8; |
147 |
} |
148 |
else |
149 |
{ |
150 |
DEBUG(("rc_4_key_size == %d, 128-bit encryption enabled\n", rc4_key_size)); |
151 |
rc4_key_len = 16; |
152 |
} |
153 |
|
154 |
/* Save initial RC4 keys as update keys */ |
155 |
memcpy(sec_decrypt_update_key, sec_decrypt_key, 16); |
156 |
memcpy(sec_encrypt_update_key, sec_encrypt_key, 16); |
157 |
|
158 |
/* Initialise RC4 state arrays */ |
159 |
RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key); |
160 |
RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key); |
161 |
} |
162 |
|
163 |
static uint8 pad_54[40] = { |
164 |
54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, |
165 |
54, 54, 54, |
166 |
54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, |
167 |
54, 54, 54 |
168 |
}; |
169 |
|
170 |
static uint8 pad_92[48] = { |
171 |
92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, |
172 |
92, 92, 92, 92, 92, 92, 92, |
173 |
92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, |
174 |
92, 92, 92, 92, 92, 92, 92 |
175 |
}; |
176 |
|
177 |
/* Output a uint32 into a buffer (little-endian) */ |
178 |
void |
179 |
buf_out_uint32(uint8 * buffer, uint32 value) |
180 |
{ |
181 |
buffer[0] = (value) & 0xff; |
182 |
buffer[1] = (value >> 8) & 0xff; |
183 |
buffer[2] = (value >> 16) & 0xff; |
184 |
buffer[3] = (value >> 24) & 0xff; |
185 |
} |
186 |
|
187 |
/* Generate a signature hash, using a combination of SHA1 and MD5 */ |
188 |
void |
189 |
sec_sign(uint8 * signature, int siglen, uint8 * session_key, int keylen, uint8 * data, int datalen) |
190 |
{ |
191 |
uint8 shasig[20]; |
192 |
uint8 md5sig[16]; |
193 |
uint8 lenhdr[4]; |
194 |
SHA_CTX sha; |
195 |
MD5_CTX md5; |
196 |
|
197 |
buf_out_uint32(lenhdr, datalen); |
198 |
|
199 |
SHA1_Init(&sha); |
200 |
SHA1_Update(&sha, session_key, keylen); |
201 |
SHA1_Update(&sha, pad_54, 40); |
202 |
SHA1_Update(&sha, lenhdr, 4); |
203 |
SHA1_Update(&sha, data, datalen); |
204 |
SHA1_Final(shasig, &sha); |
205 |
|
206 |
MD5_Init(&md5); |
207 |
MD5_Update(&md5, session_key, keylen); |
208 |
MD5_Update(&md5, pad_92, 48); |
209 |
MD5_Update(&md5, shasig, 20); |
210 |
MD5_Final(md5sig, &md5); |
211 |
|
212 |
memcpy(signature, md5sig, siglen); |
213 |
} |
214 |
|
215 |
/* Update an encryption key - similar to the signing process */ |
216 |
static void |
217 |
sec_update(uint8 * key, uint8 * update_key) |
218 |
{ |
219 |
uint8 shasig[20]; |
220 |
SHA_CTX sha; |
221 |
MD5_CTX md5; |
222 |
RC4_KEY update; |
223 |
|
224 |
SHA1_Init(&sha); |
225 |
SHA1_Update(&sha, update_key, rc4_key_len); |
226 |
SHA1_Update(&sha, pad_54, 40); |
227 |
SHA1_Update(&sha, key, rc4_key_len); |
228 |
SHA1_Final(shasig, &sha); |
229 |
|
230 |
MD5_Init(&md5); |
231 |
MD5_Update(&md5, update_key, rc4_key_len); |
232 |
MD5_Update(&md5, pad_92, 48); |
233 |
MD5_Update(&md5, shasig, 20); |
234 |
MD5_Final(key, &md5); |
235 |
|
236 |
RC4_set_key(&update, rc4_key_len, key); |
237 |
RC4(&update, rc4_key_len, key, key); |
238 |
|
239 |
if (rc4_key_len == 8) |
240 |
sec_make_40bit(key); |
241 |
} |
242 |
|
243 |
/* Encrypt data using RC4 */ |
244 |
static void |
245 |
sec_encrypt(uint8 * data, int length) |
246 |
{ |
247 |
static int use_count; |
248 |
|
249 |
if (use_count == 4096) |
250 |
{ |
251 |
sec_update(sec_encrypt_key, sec_encrypt_update_key); |
252 |
RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key); |
253 |
use_count = 0; |
254 |
} |
255 |
|
256 |
RC4(&rc4_encrypt_key, length, data, data); |
257 |
use_count++; |
258 |
} |
259 |
|
260 |
/* Decrypt data using RC4 */ |
261 |
void |
262 |
sec_decrypt(uint8 * data, int length) |
263 |
{ |
264 |
static int use_count; |
265 |
|
266 |
if (use_count == 4096) |
267 |
{ |
268 |
sec_update(sec_decrypt_key, sec_decrypt_update_key); |
269 |
RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key); |
270 |
use_count = 0; |
271 |
} |
272 |
|
273 |
RC4(&rc4_decrypt_key, length, data, data); |
274 |
use_count++; |
275 |
} |
276 |
|
277 |
static void |
278 |
reverse(uint8 * p, int len) |
279 |
{ |
280 |
int i, j; |
281 |
uint8 temp; |
282 |
|
283 |
for (i = 0, j = len - 1; i < j; i++, j--) |
284 |
{ |
285 |
temp = p[i]; |
286 |
p[i] = p[j]; |
287 |
p[j] = temp; |
288 |
} |
289 |
} |
290 |
|
291 |
/* Perform an RSA public key encryption operation */ |
292 |
static void |
293 |
sec_rsa_encrypt(uint8 * out, uint8 * in, int len, uint8 * modulus, uint8 * exponent) |
294 |
{ |
295 |
BN_CTX *ctx; |
296 |
BIGNUM mod, exp, x, y; |
297 |
uint8 inr[SEC_MODULUS_SIZE]; |
298 |
int outlen; |
299 |
|
300 |
reverse(modulus, SEC_MODULUS_SIZE); |
301 |
reverse(exponent, SEC_EXPONENT_SIZE); |
302 |
memcpy(inr, in, len); |
303 |
reverse(inr, len); |
304 |
|
305 |
ctx = BN_CTX_new(); |
306 |
BN_init(&mod); |
307 |
BN_init(&exp); |
308 |
BN_init(&x); |
309 |
BN_init(&y); |
310 |
|
311 |
BN_bin2bn(modulus, SEC_MODULUS_SIZE, &mod); |
312 |
BN_bin2bn(exponent, SEC_EXPONENT_SIZE, &exp); |
313 |
BN_bin2bn(inr, len, &x); |
314 |
BN_mod_exp(&y, &x, &exp, &mod, ctx); |
315 |
outlen = BN_bn2bin(&y, out); |
316 |
reverse(out, outlen); |
317 |
if (outlen < SEC_MODULUS_SIZE) |
318 |
memset(out + outlen, 0, SEC_MODULUS_SIZE - outlen); |
319 |
|
320 |
BN_free(&y); |
321 |
BN_clear_free(&x); |
322 |
BN_free(&exp); |
323 |
BN_free(&mod); |
324 |
BN_CTX_free(ctx); |
325 |
} |
326 |
|
327 |
/* Initialise secure transport packet */ |
328 |
STREAM |
329 |
sec_init(uint32 flags, int maxlen) |
330 |
{ |
331 |
int hdrlen; |
332 |
STREAM s; |
333 |
|
334 |
if (!g_licence_issued) |
335 |
hdrlen = (flags & SEC_ENCRYPT) ? 12 : 4; |
336 |
else |
337 |
hdrlen = (flags & SEC_ENCRYPT) ? 12 : 0; |
338 |
s = mcs_init(maxlen + hdrlen); |
339 |
s_push_layer(s, sec_hdr, hdrlen); |
340 |
|
341 |
return s; |
342 |
} |
343 |
|
344 |
/* Transmit secure transport packet over specified channel */ |
345 |
void |
346 |
sec_send_to_channel(STREAM s, uint32 flags, uint16 channel) |
347 |
{ |
348 |
int datalen; |
349 |
|
350 |
s_pop_layer(s, sec_hdr); |
351 |
if (!g_licence_issued || (flags & SEC_ENCRYPT)) |
352 |
out_uint32_le(s, flags); |
353 |
|
354 |
if (flags & SEC_ENCRYPT) |
355 |
{ |
356 |
flags &= ~SEC_ENCRYPT; |
357 |
datalen = s->end - s->p - 8; |
358 |
|
359 |
#if WITH_DEBUG |
360 |
DEBUG(("Sending encrypted packet:\n")); |
361 |
hexdump(s->p + 8, datalen); |
362 |
#endif |
363 |
|
364 |
sec_sign(s->p, 8, sec_sign_key, rc4_key_len, s->p + 8, datalen); |
365 |
sec_encrypt(s->p + 8, datalen); |
366 |
} |
367 |
|
368 |
mcs_send_to_channel(s, channel); |
369 |
} |
370 |
|
371 |
/* Transmit secure transport packet */ |
372 |
|
373 |
void |
374 |
sec_send(STREAM s, uint32 flags) |
375 |
{ |
376 |
sec_send_to_channel(s, flags, MCS_GLOBAL_CHANNEL); |
377 |
} |
378 |
|
379 |
|
380 |
/* Transfer the client random to the server */ |
381 |
static void |
382 |
sec_establish_key(void) |
383 |
{ |
384 |
uint32 length = SEC_MODULUS_SIZE + SEC_PADDING_SIZE; |
385 |
uint32 flags = SEC_CLIENT_RANDOM; |
386 |
STREAM s; |
387 |
|
388 |
s = sec_init(flags, 76); |
389 |
|
390 |
out_uint32_le(s, length); |
391 |
out_uint8p(s, sec_crypted_random, SEC_MODULUS_SIZE); |
392 |
out_uint8s(s, SEC_PADDING_SIZE); |
393 |
|
394 |
s_mark_end(s); |
395 |
sec_send(s, flags); |
396 |
} |
397 |
|
398 |
/* Output connect initial data blob */ |
399 |
static void |
400 |
sec_out_mcs_data(STREAM s) |
401 |
{ |
402 |
uint16 num_channels = get_num_channels(); |
403 |
int hostlen = 2 * strlen(hostname); |
404 |
int length = 158 + 76 + 12 + 4 + (CHANNEL_TAGDATA_SIZE * num_channels); |
405 |
uint16 i; |
406 |
rdp5_channel *channel; |
407 |
|
408 |
if (0 < num_channels) |
409 |
{ |
410 |
length += +4 + 4; |
411 |
} |
412 |
|
413 |
if (hostlen > 30) |
414 |
hostlen = 30; |
415 |
|
416 |
out_uint16_be(s, 5); /* unknown */ |
417 |
out_uint16_be(s, 0x14); |
418 |
out_uint8(s, 0x7c); |
419 |
out_uint16_be(s, 1); |
420 |
|
421 |
out_uint16_be(s, (length | 0x8000)); /* remaining length */ |
422 |
|
423 |
out_uint16_be(s, 8); /* length? */ |
424 |
out_uint16_be(s, 16); |
425 |
out_uint8(s, 0); |
426 |
out_uint16_le(s, 0xc001); |
427 |
out_uint8(s, 0); |
428 |
|
429 |
out_uint32_le(s, 0x61637544); /* "Duca" ?! */ |
430 |
out_uint16_be(s, ((length - 14) | 0x8000)); /* remaining length */ |
431 |
|
432 |
/* Client information */ |
433 |
out_uint16_le(s, SEC_TAG_CLI_INFO); |
434 |
out_uint16_le(s, 212); /* length */ |
435 |
out_uint16_le(s, use_rdp5 ? 4 : 1); /* RDP version. 1 == RDP4, 4 == RDP5. */ |
436 |
out_uint16_le(s, 8); |
437 |
out_uint16_le(s, width); |
438 |
out_uint16_le(s, height); |
439 |
out_uint16_le(s, 0xca01); |
440 |
out_uint16_le(s, 0xaa03); |
441 |
out_uint32_le(s, keylayout); |
442 |
out_uint32_le(s, 2600); /* Client build. We are now 2600 compatible :-) */ |
443 |
|
444 |
/* Unicode name of client, padded to 32 bytes */ |
445 |
rdp_out_unistr(s, hostname, hostlen); |
446 |
out_uint8s(s, 30 - hostlen); |
447 |
|
448 |
out_uint32_le(s, 4); |
449 |
out_uint32(s, 0); |
450 |
out_uint32_le(s, 12); |
451 |
out_uint8s(s, 64); /* reserved? 4 + 12 doublewords */ |
452 |
|
453 |
switch (server_bpp) |
454 |
{ |
455 |
case 8: |
456 |
out_uint16_le(s, 0xca01); |
457 |
break; |
458 |
case 15: |
459 |
out_uint16_le(s, 0xca02); |
460 |
break; |
461 |
case 16: |
462 |
out_uint16_le(s, 0xca03); |
463 |
break; |
464 |
case 24: |
465 |
out_uint16_le(s, 0xca04); |
466 |
break; |
467 |
} |
468 |
out_uint16_le(s, 1); |
469 |
|
470 |
out_uint32(s, 0); |
471 |
out_uint8(s, server_bpp); |
472 |
out_uint16_le(s, 0x0700); |
473 |
out_uint8(s, 0); |
474 |
out_uint32_le(s, 1); |
475 |
out_uint8s(s, 64); /* End of client info */ |
476 |
|
477 |
out_uint16_le(s, SEC_TAG_CLI_4); |
478 |
out_uint16_le(s, 12); |
479 |
out_uint32_le(s, 9); |
480 |
out_uint32(s, 0); |
481 |
|
482 |
/* Client encryption settings */ |
483 |
out_uint16_le(s, SEC_TAG_CLI_CRYPT); |
484 |
out_uint16_le(s, 12); /* length */ |
485 |
out_uint32_le(s, encryption ? 0x3 : 0); /* encryption supported, 128-bit supported */ |
486 |
out_uint32(s, 0); /* Unknown */ |
487 |
|
488 |
DEBUG_RDP5(("num_channels is %d\n", num_channels)); |
489 |
if (0 < num_channels) |
490 |
{ |
491 |
out_uint16_le(s, SEC_TAG_CLI_CHANNELS); |
492 |
out_uint16_le(s, num_channels * CHANNEL_TAGDATA_SIZE + 4 + 4); /* length */ |
493 |
out_uint32_le(s, num_channels); /* number of virtual channels */ |
494 |
for (i = 0; i < num_channels; i++) |
495 |
{ |
496 |
channel = find_channel_by_num(i); |
497 |
DEBUG_RDP5(("Requesting channel %s\n", channel->name)); |
498 |
out_uint8p(s, channel->name, 8); |
499 |
out_uint32_be(s, channel->channelflags); |
500 |
} |
501 |
} |
502 |
|
503 |
s_mark_end(s); |
504 |
} |
505 |
|
506 |
/* Parse a public key structure */ |
507 |
static BOOL |
508 |
sec_parse_public_key(STREAM s, uint8 ** modulus, uint8 ** exponent) |
509 |
{ |
510 |
uint32 magic, modulus_len; |
511 |
|
512 |
in_uint32_le(s, magic); |
513 |
if (magic != SEC_RSA_MAGIC) |
514 |
{ |
515 |
error("RSA magic 0x%x\n", magic); |
516 |
return False; |
517 |
} |
518 |
|
519 |
in_uint32_le(s, modulus_len); |
520 |
if (modulus_len != SEC_MODULUS_SIZE + SEC_PADDING_SIZE) |
521 |
{ |
522 |
error("modulus len 0x%x\n", modulus_len); |
523 |
return False; |
524 |
} |
525 |
|
526 |
in_uint8s(s, 8); /* modulus_bits, unknown */ |
527 |
in_uint8p(s, *exponent, SEC_EXPONENT_SIZE); |
528 |
in_uint8p(s, *modulus, SEC_MODULUS_SIZE); |
529 |
in_uint8s(s, SEC_PADDING_SIZE); |
530 |
|
531 |
return s_check(s); |
532 |
} |
533 |
|
534 |
static BOOL |
535 |
sec_parse_x509_key(X509 * cert) |
536 |
{ |
537 |
EVP_PKEY *epk = NULL; |
538 |
/* By some reason, Microsoft sets the OID of the Public RSA key to |
539 |
the oid for "MD5 with RSA Encryption" instead of "RSA Encryption" |
540 |
|
541 |
Kudos to Richard Levitte for the following (. intiutive .) |
542 |
lines of code that resets the OID and let's us extract the key. */ |
543 |
if (OBJ_obj2nid(cert->cert_info->key->algor->algorithm) == NID_md5WithRSAEncryption) |
544 |
{ |
545 |
DEBUG_RDP5(("Re-setting algorithm type to RSA in server certificate\n")); |
546 |
cert->cert_info->key->algor->algorithm = OBJ_nid2obj(NID_rsaEncryption); |
547 |
} |
548 |
epk = X509_get_pubkey(cert); |
549 |
if (NULL == epk) |
550 |
{ |
551 |
error("Failed to extract public key from certificate\n"); |
552 |
return False; |
553 |
} |
554 |
|
555 |
server_public_key = (RSA *) epk->pkey.ptr; |
556 |
|
557 |
return True; |
558 |
} |
559 |
|
560 |
|
561 |
/* Parse a crypto information structure */ |
562 |
static BOOL |
563 |
sec_parse_crypt_info(STREAM s, uint32 * rc4_key_size, |
564 |
uint8 ** server_random, uint8 ** modulus, uint8 ** exponent) |
565 |
{ |
566 |
uint32 crypt_level, random_len, rsa_info_len; |
567 |
uint32 cacert_len, cert_len, flags; |
568 |
X509 *cacert, *server_cert; |
569 |
uint16 tag, length; |
570 |
uint8 *next_tag, *end; |
571 |
|
572 |
in_uint32_le(s, *rc4_key_size); /* 1 = 40-bit, 2 = 128-bit */ |
573 |
in_uint32_le(s, crypt_level); /* 1 = low, 2 = medium, 3 = high */ |
574 |
if (crypt_level == 0) /* no encryption */ |
575 |
return False; |
576 |
in_uint32_le(s, random_len); |
577 |
in_uint32_le(s, rsa_info_len); |
578 |
|
579 |
if (random_len != SEC_RANDOM_SIZE) |
580 |
{ |
581 |
error("random len %d, expected %d\n", random_len, SEC_RANDOM_SIZE); |
582 |
return False; |
583 |
} |
584 |
|
585 |
in_uint8p(s, *server_random, random_len); |
586 |
|
587 |
/* RSA info */ |
588 |
end = s->p + rsa_info_len; |
589 |
if (end > s->end) |
590 |
return False; |
591 |
|
592 |
in_uint32_le(s, flags); /* 1 = RDP4-style, 0x80000002 = X.509 */ |
593 |
if (flags & 1) |
594 |
{ |
595 |
DEBUG_RDP5(("We're going for the RDP4-style encryption\n")); |
596 |
in_uint8s(s, 8); /* unknown */ |
597 |
|
598 |
while (s->p < end) |
599 |
{ |
600 |
in_uint16_le(s, tag); |
601 |
in_uint16_le(s, length); |
602 |
|
603 |
next_tag = s->p + length; |
604 |
|
605 |
switch (tag) |
606 |
{ |
607 |
case SEC_TAG_PUBKEY: |
608 |
if (!sec_parse_public_key(s, modulus, exponent)) |
609 |
return False; |
610 |
DEBUG_RDP5(("Got Public key, RDP4-style\n")); |
611 |
|
612 |
break; |
613 |
|
614 |
case SEC_TAG_KEYSIG: |
615 |
/* Is this a Microsoft key that we just got? */ |
616 |
/* Care factor: zero! */ |
617 |
/* Actually, it would probably be a good idea to check if the public key is signed with this key, and then store this |
618 |
key as a known key of the hostname. This would prevent some MITM-attacks. */ |
619 |
break; |
620 |
|
621 |
default: |
622 |
unimpl("crypt tag 0x%x\n", tag); |
623 |
} |
624 |
|
625 |
s->p = next_tag; |
626 |
} |
627 |
} |
628 |
else |
629 |
{ |
630 |
DEBUG_RDP5(("We're going for the RDP5-style encryption\n")); |
631 |
in_uint8s(s, 4); /* Number of certificates */ |
632 |
|
633 |
/* Do da funky X.509 stuffy |
634 |
|
635 |
"How did I find out about this? I looked up and saw a |
636 |
bright light and when I came to I had a scar on my forehead |
637 |
and knew about X.500" |
638 |
- Peter Gutman in a early version of |
639 |
http://www.cs.auckland.ac.nz/~pgut001/pubs/x509guide.txt |
640 |
*/ |
641 |
|
642 |
in_uint32_le(s, cacert_len); |
643 |
cacert = d2i_X509(NULL, &(s->p), cacert_len); |
644 |
/* Note: We don't need to move s->p here - d2i_X509 is |
645 |
"kind" enough to do it for us */ |
646 |
if (NULL == cacert) |
647 |
{ |
648 |
error("Couldn't load CA Certificate from server\n"); |
649 |
return False; |
650 |
} |
651 |
|
652 |
/* Currently, we don't use the CA Certificate. |
653 |
FIXME: |
654 |
*) Verify the server certificate (server_cert) with the |
655 |
CA certificate. |
656 |
*) Store the CA Certificate with the hostname of the |
657 |
server we are connecting to as key, and compare it |
658 |
when we connect the next time, in order to prevent |
659 |
MITM-attacks. |
660 |
*/ |
661 |
|
662 |
in_uint32_le(s, cert_len); |
663 |
server_cert = d2i_X509(NULL, &(s->p), cert_len); |
664 |
if (NULL == server_cert) |
665 |
{ |
666 |
error("Couldn't load Certificate from server\n"); |
667 |
return False; |
668 |
} |
669 |
|
670 |
in_uint8s(s, 16); /* Padding */ |
671 |
|
672 |
/* Note: Verifying the server certificate must be done here, |
673 |
before sec_parse_public_key since we'll have to apply |
674 |
serious violence to the key after this */ |
675 |
|
676 |
if (!sec_parse_x509_key(server_cert)) |
677 |
{ |
678 |
DEBUG_RDP5(("Didn't parse X509 correctly\n")); |
679 |
return False; |
680 |
} |
681 |
return True; /* There's some garbage here we don't care about */ |
682 |
} |
683 |
return s_check_end(s); |
684 |
} |
685 |
|
686 |
/* Process crypto information blob */ |
687 |
static void |
688 |
sec_process_crypt_info(STREAM s) |
689 |
{ |
690 |
uint8 *server_random, *modulus, *exponent; |
691 |
uint8 client_random[SEC_RANDOM_SIZE]; |
692 |
uint32 rc4_key_size; |
693 |
uint8 inr[SEC_MODULUS_SIZE]; |
694 |
|
695 |
if (!sec_parse_crypt_info(s, &rc4_key_size, &server_random, &modulus, &exponent)) |
696 |
{ |
697 |
DEBUG(("Failed to parse crypt info\n")); |
698 |
return; |
699 |
} |
700 |
|
701 |
DEBUG(("Generating client random\n")); |
702 |
/* Generate a client random, and hence determine encryption keys */ |
703 |
// This is what the MS client do: |
704 |
memset(inr, 0, SEC_RANDOM_SIZE); |
705 |
/* *ARIGL!* Plaintext attack, anyone? |
706 |
I tried doing: |
707 |
generate_random(inr); |
708 |
..but that generates connection errors now and then (yes, |
709 |
"now and then". Something like 0 to 3 attempts needed before a |
710 |
successful connection. Nice. Not! |
711 |
*/ |
712 |
|
713 |
generate_random(client_random); |
714 |
if (NULL != server_public_key) |
715 |
{ /* Which means we should use |
716 |
RDP5-style encryption */ |
717 |
|
718 |
memcpy(inr + SEC_RANDOM_SIZE, client_random, SEC_RANDOM_SIZE); |
719 |
reverse(inr + SEC_RANDOM_SIZE, SEC_RANDOM_SIZE); |
720 |
|
721 |
RSA_public_encrypt(SEC_MODULUS_SIZE, |
722 |
inr, sec_crypted_random, server_public_key, RSA_NO_PADDING); |
723 |
|
724 |
reverse(sec_crypted_random, SEC_MODULUS_SIZE); |
725 |
|
726 |
} |
727 |
else |
728 |
{ /* RDP4-style encryption */ |
729 |
sec_rsa_encrypt(sec_crypted_random, |
730 |
client_random, SEC_RANDOM_SIZE, modulus, exponent); |
731 |
} |
732 |
sec_generate_keys(client_random, server_random, rc4_key_size); |
733 |
} |
734 |
|
735 |
|
736 |
/* Process SRV_INFO, find RDP version supported by server */ |
737 |
static void |
738 |
sec_process_srv_info(STREAM s) |
739 |
{ |
740 |
in_uint16_le(s, server_rdp_version); |
741 |
DEBUG_RDP5(("Server RDP version is %d\n", server_rdp_version)); |
742 |
} |
743 |
|
744 |
|
745 |
/* Process connect response data blob */ |
746 |
void |
747 |
sec_process_mcs_data(STREAM s) |
748 |
{ |
749 |
uint16 tag, length; |
750 |
uint8 *next_tag; |
751 |
uint8 len; |
752 |
|
753 |
in_uint8s(s, 21); /* header (T.124 stuff, probably) */ |
754 |
in_uint8(s, len); |
755 |
if (len & 0x80) |
756 |
in_uint8(s, len); |
757 |
|
758 |
while (s->p < s->end) |
759 |
{ |
760 |
in_uint16_le(s, tag); |
761 |
in_uint16_le(s, length); |
762 |
|
763 |
if (length <= 4) |
764 |
return; |
765 |
|
766 |
next_tag = s->p + length - 4; |
767 |
|
768 |
switch (tag) |
769 |
{ |
770 |
case SEC_TAG_SRV_INFO: |
771 |
sec_process_srv_info(s); |
772 |
break; |
773 |
|
774 |
case SEC_TAG_SRV_3: |
775 |
break; |
776 |
|
777 |
case SEC_TAG_SRV_CRYPT: |
778 |
sec_process_crypt_info(s); |
779 |
break; |
780 |
|
781 |
default: |
782 |
unimpl("response tag 0x%x\n", tag); |
783 |
} |
784 |
|
785 |
s->p = next_tag; |
786 |
} |
787 |
} |
788 |
|
789 |
/* Receive secure transport packet */ |
790 |
STREAM |
791 |
sec_recv(void) |
792 |
{ |
793 |
uint32 sec_flags; |
794 |
uint16 channel; |
795 |
STREAM s; |
796 |
|
797 |
while ((s = mcs_recv(&channel)) != NULL) |
798 |
{ |
799 |
if (encryption || !g_licence_issued) |
800 |
{ |
801 |
in_uint32_le(s, sec_flags); |
802 |
|
803 |
if (sec_flags & SEC_LICENCE_NEG) |
804 |
{ |
805 |
if (sec_flags & SEC_ENCRYPT) |
806 |
{ |
807 |
DEBUG_RDP5(("Encrypted license detected\n")); |
808 |
} |
809 |
licence_process(s); |
810 |
continue; |
811 |
} |
812 |
|
813 |
if (sec_flags & SEC_ENCRYPT) |
814 |
{ |
815 |
in_uint8s(s, 8); /* signature */ |
816 |
sec_decrypt(s->p, s->end - s->p); |
817 |
} |
818 |
} |
819 |
|
820 |
if (MCS_GLOBAL_CHANNEL == channel) |
821 |
{ |
822 |
return s; |
823 |
} |
824 |
else |
825 |
rdp5_process_channel(s, channel); |
826 |
|
827 |
} |
828 |
|
829 |
return NULL; |
830 |
} |
831 |
|
832 |
/* Establish a secure connection */ |
833 |
BOOL |
834 |
sec_connect(char *server, char *username) |
835 |
{ |
836 |
struct stream mcs_data; |
837 |
|
838 |
/* We exchange some RDP data during the MCS-Connect */ |
839 |
mcs_data.size = 512; |
840 |
mcs_data.p = mcs_data.data = (uint8 *) xmalloc(mcs_data.size); |
841 |
sec_out_mcs_data(&mcs_data); |
842 |
|
843 |
if (!mcs_connect(server, &mcs_data, username)) |
844 |
return False; |
845 |
|
846 |
// sec_process_mcs_data(&mcs_data); |
847 |
if (encryption) |
848 |
sec_establish_key(); |
849 |
xfree(mcs_data.data); |
850 |
return True; |
851 |
} |
852 |
|
853 |
/* Disconnect a connection */ |
854 |
void |
855 |
sec_disconnect(void) |
856 |
{ |
857 |
mcs_disconnect(); |
858 |
} |