| 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 licence_issued; |
| 42 |
extern BOOL use_rdp5; |
| 43 |
extern int server_bpp; |
| 44 |
|
| 45 |
static int rc4_key_len; |
| 46 |
static RC4_KEY rc4_decrypt_key; |
| 47 |
static RC4_KEY rc4_encrypt_key; |
| 48 |
static RSA *server_public_key; |
| 49 |
|
| 50 |
static uint8 sec_sign_key[16]; |
| 51 |
static uint8 sec_decrypt_key[16]; |
| 52 |
static uint8 sec_encrypt_key[16]; |
| 53 |
static uint8 sec_decrypt_update_key[16]; |
| 54 |
static uint8 sec_encrypt_update_key[16]; |
| 55 |
static uint8 sec_crypted_random[SEC_MODULUS_SIZE]; |
| 56 |
|
| 57 |
uint16 server_rdp_version = 0; |
| 58 |
|
| 59 |
/* |
| 60 |
* General purpose 48-byte transformation, using two 32-byte salts (generally, |
| 61 |
* a client and server salt) and a global salt value used for padding. |
| 62 |
* Both SHA1 and MD5 algorithms are used. |
| 63 |
*/ |
| 64 |
void |
| 65 |
sec_hash_48(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2, uint8 salt) |
| 66 |
{ |
| 67 |
uint8 shasig[20]; |
| 68 |
uint8 pad[4]; |
| 69 |
SHA_CTX sha; |
| 70 |
MD5_CTX md5; |
| 71 |
int i; |
| 72 |
|
| 73 |
for (i = 0; i < 3; i++) |
| 74 |
{ |
| 75 |
memset(pad, salt + i, i + 1); |
| 76 |
|
| 77 |
SHA1_Init(&sha); |
| 78 |
SHA1_Update(&sha, pad, i + 1); |
| 79 |
SHA1_Update(&sha, in, 48); |
| 80 |
SHA1_Update(&sha, salt1, 32); |
| 81 |
SHA1_Update(&sha, salt2, 32); |
| 82 |
SHA1_Final(shasig, &sha); |
| 83 |
|
| 84 |
MD5_Init(&md5); |
| 85 |
MD5_Update(&md5, in, 48); |
| 86 |
MD5_Update(&md5, shasig, 20); |
| 87 |
MD5_Final(&out[i * 16], &md5); |
| 88 |
} |
| 89 |
} |
| 90 |
|
| 91 |
/* |
| 92 |
* Weaker 16-byte transformation, also using two 32-byte salts, but |
| 93 |
* only using a single round of MD5. |
| 94 |
*/ |
| 95 |
void |
| 96 |
sec_hash_16(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2) |
| 97 |
{ |
| 98 |
MD5_CTX md5; |
| 99 |
|
| 100 |
MD5_Init(&md5); |
| 101 |
MD5_Update(&md5, in, 16); |
| 102 |
MD5_Update(&md5, salt1, 32); |
| 103 |
MD5_Update(&md5, salt2, 32); |
| 104 |
MD5_Final(out, &md5); |
| 105 |
} |
| 106 |
|
| 107 |
/* Reduce key entropy from 64 to 40 bits */ |
| 108 |
static void |
| 109 |
sec_make_40bit(uint8 * key) |
| 110 |
{ |
| 111 |
key[0] = 0xd1; |
| 112 |
key[1] = 0x26; |
| 113 |
key[2] = 0x9e; |
| 114 |
} |
| 115 |
|
| 116 |
/* Generate a session key and RC4 keys, given client and server randoms */ |
| 117 |
static void |
| 118 |
sec_generate_keys(uint8 * client_key, uint8 * server_key, int rc4_key_size) |
| 119 |
{ |
| 120 |
uint8 session_key[48]; |
| 121 |
uint8 temp_hash[48]; |
| 122 |
uint8 input[48]; |
| 123 |
|
| 124 |
/* Construct input data to hash */ |
| 125 |
memcpy(input, client_key, 24); |
| 126 |
memcpy(input + 24, server_key, 24); |
| 127 |
|
| 128 |
/* Generate session key - two rounds of sec_hash_48 */ |
| 129 |
sec_hash_48(temp_hash, input, client_key, server_key, 65); |
| 130 |
sec_hash_48(session_key, temp_hash, client_key, server_key, 88); |
| 131 |
|
| 132 |
/* Store first 16 bytes of session key, for generating signatures */ |
| 133 |
memcpy(sec_sign_key, session_key, 16); |
| 134 |
|
| 135 |
/* Generate RC4 keys */ |
| 136 |
sec_hash_16(sec_decrypt_key, &session_key[16], client_key, server_key); |
| 137 |
sec_hash_16(sec_encrypt_key, &session_key[32], client_key, server_key); |
| 138 |
|
| 139 |
if (rc4_key_size == 1) |
| 140 |
{ |
| 141 |
DEBUG(("40-bit encryption enabled\n")); |
| 142 |
sec_make_40bit(sec_sign_key); |
| 143 |
sec_make_40bit(sec_decrypt_key); |
| 144 |
sec_make_40bit(sec_encrypt_key); |
| 145 |
rc4_key_len = 8; |
| 146 |
} |
| 147 |
else |
| 148 |
{ |
| 149 |
DEBUG(("rc_4_key_size == %d, 128-bit encryption enabled\n", rc4_key_size)); |
| 150 |
rc4_key_len = 16; |
| 151 |
} |
| 152 |
|
| 153 |
/* Save initial RC4 keys as update keys */ |
| 154 |
memcpy(sec_decrypt_update_key, sec_decrypt_key, 16); |
| 155 |
memcpy(sec_encrypt_update_key, sec_encrypt_key, 16); |
| 156 |
|
| 157 |
/* Initialise RC4 state arrays */ |
| 158 |
RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key); |
| 159 |
RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key); |
| 160 |
} |
| 161 |
|
| 162 |
static uint8 pad_54[40] = { |
| 163 |
54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, |
| 164 |
54, 54, 54, |
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54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, |
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54, 54, 54 |
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}; |
| 168 |
|
| 169 |
static uint8 pad_92[48] = { |
| 170 |
92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, |
| 171 |
92, 92, 92, 92, 92, 92, 92, |
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92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, |
| 173 |
92, 92, 92, 92, 92, 92, 92 |
| 174 |
}; |
| 175 |
|
| 176 |
/* Output a uint32 into a buffer (little-endian) */ |
| 177 |
void |
| 178 |
buf_out_uint32(uint8 * buffer, uint32 value) |
| 179 |
{ |
| 180 |
buffer[0] = (value) & 0xff; |
| 181 |
buffer[1] = (value >> 8) & 0xff; |
| 182 |
buffer[2] = (value >> 16) & 0xff; |
| 183 |
buffer[3] = (value >> 24) & 0xff; |
| 184 |
} |
| 185 |
|
| 186 |
/* Generate a signature hash, using a combination of SHA1 and MD5 */ |
| 187 |
void |
| 188 |
sec_sign(uint8 * signature, int siglen, uint8 * session_key, int keylen, uint8 * data, int datalen) |
| 189 |
{ |
| 190 |
uint8 shasig[20]; |
| 191 |
uint8 md5sig[16]; |
| 192 |
uint8 lenhdr[4]; |
| 193 |
SHA_CTX sha; |
| 194 |
MD5_CTX md5; |
| 195 |
|
| 196 |
buf_out_uint32(lenhdr, datalen); |
| 197 |
|
| 198 |
SHA1_Init(&sha); |
| 199 |
SHA1_Update(&sha, session_key, keylen); |
| 200 |
SHA1_Update(&sha, pad_54, 40); |
| 201 |
SHA1_Update(&sha, lenhdr, 4); |
| 202 |
SHA1_Update(&sha, data, datalen); |
| 203 |
SHA1_Final(shasig, &sha); |
| 204 |
|
| 205 |
MD5_Init(&md5); |
| 206 |
MD5_Update(&md5, session_key, keylen); |
| 207 |
MD5_Update(&md5, pad_92, 48); |
| 208 |
MD5_Update(&md5, shasig, 20); |
| 209 |
MD5_Final(md5sig, &md5); |
| 210 |
|
| 211 |
memcpy(signature, md5sig, siglen); |
| 212 |
} |
| 213 |
|
| 214 |
/* Update an encryption key - similar to the signing process */ |
| 215 |
static void |
| 216 |
sec_update(uint8 * key, uint8 * update_key) |
| 217 |
{ |
| 218 |
uint8 shasig[20]; |
| 219 |
SHA_CTX sha; |
| 220 |
MD5_CTX md5; |
| 221 |
RC4_KEY update; |
| 222 |
|
| 223 |
SHA1_Init(&sha); |
| 224 |
SHA1_Update(&sha, update_key, rc4_key_len); |
| 225 |
SHA1_Update(&sha, pad_54, 40); |
| 226 |
SHA1_Update(&sha, key, rc4_key_len); |
| 227 |
SHA1_Final(shasig, &sha); |
| 228 |
|
| 229 |
MD5_Init(&md5); |
| 230 |
MD5_Update(&md5, update_key, rc4_key_len); |
| 231 |
MD5_Update(&md5, pad_92, 48); |
| 232 |
MD5_Update(&md5, shasig, 20); |
| 233 |
MD5_Final(key, &md5); |
| 234 |
|
| 235 |
RC4_set_key(&update, rc4_key_len, key); |
| 236 |
RC4(&update, rc4_key_len, key, key); |
| 237 |
|
| 238 |
if (rc4_key_len == 8) |
| 239 |
sec_make_40bit(key); |
| 240 |
} |
| 241 |
|
| 242 |
/* Encrypt data using RC4 */ |
| 243 |
static void |
| 244 |
sec_encrypt(uint8 * data, int length) |
| 245 |
{ |
| 246 |
static int use_count; |
| 247 |
|
| 248 |
if (use_count == 4096) |
| 249 |
{ |
| 250 |
sec_update(sec_encrypt_key, sec_encrypt_update_key); |
| 251 |
RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key); |
| 252 |
use_count = 0; |
| 253 |
} |
| 254 |
|
| 255 |
RC4(&rc4_encrypt_key, length, data, data); |
| 256 |
use_count++; |
| 257 |
} |
| 258 |
|
| 259 |
/* Decrypt data using RC4 */ |
| 260 |
void |
| 261 |
sec_decrypt(uint8 * data, int length) |
| 262 |
{ |
| 263 |
static int use_count; |
| 264 |
|
| 265 |
if (use_count == 4096) |
| 266 |
{ |
| 267 |
sec_update(sec_decrypt_key, sec_decrypt_update_key); |
| 268 |
RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key); |
| 269 |
use_count = 0; |
| 270 |
} |
| 271 |
|
| 272 |
RC4(&rc4_decrypt_key, length, data, data); |
| 273 |
use_count++; |
| 274 |
} |
| 275 |
|
| 276 |
static void |
| 277 |
reverse(uint8 * p, int len) |
| 278 |
{ |
| 279 |
int i, j; |
| 280 |
uint8 temp; |
| 281 |
|
| 282 |
for (i = 0, j = len - 1; i < j; i++, j--) |
| 283 |
{ |
| 284 |
temp = p[i]; |
| 285 |
p[i] = p[j]; |
| 286 |
p[j] = temp; |
| 287 |
} |
| 288 |
} |
| 289 |
|
| 290 |
/* Perform an RSA public key encryption operation */ |
| 291 |
static void |
| 292 |
sec_rsa_encrypt(uint8 * out, uint8 * in, int len, uint8 * modulus, uint8 * exponent) |
| 293 |
{ |
| 294 |
BN_CTX *ctx; |
| 295 |
BIGNUM mod, exp, x, y; |
| 296 |
uint8 inr[SEC_MODULUS_SIZE]; |
| 297 |
int outlen; |
| 298 |
|
| 299 |
reverse(modulus, SEC_MODULUS_SIZE); |
| 300 |
reverse(exponent, SEC_EXPONENT_SIZE); |
| 301 |
memcpy(inr, in, len); |
| 302 |
reverse(inr, len); |
| 303 |
|
| 304 |
ctx = BN_CTX_new(); |
| 305 |
BN_init(&mod); |
| 306 |
BN_init(&exp); |
| 307 |
BN_init(&x); |
| 308 |
BN_init(&y); |
| 309 |
|
| 310 |
BN_bin2bn(modulus, SEC_MODULUS_SIZE, &mod); |
| 311 |
BN_bin2bn(exponent, SEC_EXPONENT_SIZE, &exp); |
| 312 |
BN_bin2bn(inr, len, &x); |
| 313 |
BN_mod_exp(&y, &x, &exp, &mod, ctx); |
| 314 |
outlen = BN_bn2bin(&y, out); |
| 315 |
reverse(out, outlen); |
| 316 |
if (outlen < SEC_MODULUS_SIZE) |
| 317 |
memset(out + outlen, 0, SEC_MODULUS_SIZE - outlen); |
| 318 |
|
| 319 |
BN_free(&y); |
| 320 |
BN_clear_free(&x); |
| 321 |
BN_free(&exp); |
| 322 |
BN_free(&mod); |
| 323 |
BN_CTX_free(ctx); |
| 324 |
} |
| 325 |
|
| 326 |
/* Initialise secure transport packet */ |
| 327 |
STREAM |
| 328 |
sec_init(uint32 flags, int maxlen) |
| 329 |
{ |
| 330 |
int hdrlen; |
| 331 |
STREAM s; |
| 332 |
|
| 333 |
if (!licence_issued) |
| 334 |
hdrlen = (flags & SEC_ENCRYPT) ? 12 : 4; |
| 335 |
else |
| 336 |
hdrlen = (flags & SEC_ENCRYPT) ? 12 : 0; |
| 337 |
s = mcs_init(maxlen + hdrlen); |
| 338 |
s_push_layer(s, sec_hdr, hdrlen); |
| 339 |
|
| 340 |
return s; |
| 341 |
} |
| 342 |
|
| 343 |
/* Transmit secure transport packet */ |
| 344 |
void |
| 345 |
sec_send(STREAM s, uint32 flags) |
| 346 |
{ |
| 347 |
int datalen; |
| 348 |
|
| 349 |
s_pop_layer(s, sec_hdr); |
| 350 |
if (!licence_issued || (flags & SEC_ENCRYPT)) |
| 351 |
out_uint32_le(s, flags); |
| 352 |
|
| 353 |
if (flags & SEC_ENCRYPT) |
| 354 |
{ |
| 355 |
flags &= ~SEC_ENCRYPT; |
| 356 |
datalen = s->end - s->p - 8; |
| 357 |
|
| 358 |
#if WITH_DEBUG |
| 359 |
DEBUG(("Sending encrypted packet:\n")); |
| 360 |
hexdump(s->p + 8, datalen); |
| 361 |
#endif |
| 362 |
|
| 363 |
sec_sign(s->p, 8, sec_sign_key, rc4_key_len, s->p + 8, datalen); |
| 364 |
sec_encrypt(s->p + 8, datalen); |
| 365 |
} |
| 366 |
|
| 367 |
mcs_send(s); |
| 368 |
} |
| 369 |
|
| 370 |
/* Transfer the client random to the server */ |
| 371 |
static void |
| 372 |
sec_establish_key(void) |
| 373 |
{ |
| 374 |
uint32 length = SEC_MODULUS_SIZE + SEC_PADDING_SIZE; |
| 375 |
uint32 flags = SEC_CLIENT_RANDOM; |
| 376 |
STREAM s; |
| 377 |
|
| 378 |
s = sec_init(flags, 76); |
| 379 |
|
| 380 |
out_uint32_le(s, length); |
| 381 |
out_uint8p(s, sec_crypted_random, SEC_MODULUS_SIZE); |
| 382 |
out_uint8s(s, SEC_PADDING_SIZE); |
| 383 |
|
| 384 |
s_mark_end(s); |
| 385 |
sec_send(s, flags); |
| 386 |
} |
| 387 |
|
| 388 |
/* Output connect initial data blob */ |
| 389 |
static void |
| 390 |
sec_out_mcs_data(STREAM s) |
| 391 |
{ |
| 392 |
int hostlen = 2 * strlen(hostname); |
| 393 |
int length = 158 + 76 + 12 + 4 + 20; |
| 394 |
|
| 395 |
if (hostlen > 30) |
| 396 |
hostlen = 30; |
| 397 |
|
| 398 |
out_uint16_be(s, 5); /* unknown */ |
| 399 |
out_uint16_be(s, 0x14); |
| 400 |
out_uint8(s, 0x7c); |
| 401 |
out_uint16_be(s, 1); |
| 402 |
|
| 403 |
out_uint16_be(s, (length | 0x8000)); /* remaining length */ |
| 404 |
|
| 405 |
out_uint16_be(s, 8); /* length? */ |
| 406 |
out_uint16_be(s, 16); |
| 407 |
out_uint8(s, 0); |
| 408 |
out_uint16_le(s, 0xc001); |
| 409 |
out_uint8(s, 0); |
| 410 |
|
| 411 |
out_uint32_le(s, 0x61637544); /* "Duca" ?! */ |
| 412 |
out_uint16_be(s, ((length - 14) | 0x8000)); /* remaining length */ |
| 413 |
|
| 414 |
/* Client information */ |
| 415 |
out_uint16_le(s, SEC_TAG_CLI_INFO); |
| 416 |
out_uint16_le(s, 212); /* length */ |
| 417 |
out_uint16_le(s, use_rdp5 ? 4 : 1); /* RDP version. 1 == RDP4, 4 == RDP5. */ |
| 418 |
out_uint16_le(s, 8); |
| 419 |
out_uint16_le(s, width); |
| 420 |
out_uint16_le(s, height); |
| 421 |
out_uint16_le(s, 0xca01); |
| 422 |
out_uint16_le(s, 0xaa03); |
| 423 |
out_uint32_le(s, keylayout); |
| 424 |
out_uint32_le(s, 2600); /* Client build. We are now 2600 compatible :-) */ |
| 425 |
|
| 426 |
/* Unicode name of client, padded to 32 bytes */ |
| 427 |
rdp_out_unistr(s, hostname, hostlen); |
| 428 |
out_uint8s(s, 30 - hostlen); |
| 429 |
|
| 430 |
out_uint32_le(s, 4); |
| 431 |
out_uint32(s, 0); |
| 432 |
out_uint32_le(s, 12); |
| 433 |
out_uint8s(s, 64); /* reserved? 4 + 12 doublewords */ |
| 434 |
|
| 435 |
switch (server_bpp) |
| 436 |
{ |
| 437 |
case 8: |
| 438 |
out_uint16_le(s, 0xca01); |
| 439 |
break; |
| 440 |
case 15: |
| 441 |
out_uint16_le(s, 0xca02); |
| 442 |
break; |
| 443 |
case 16: |
| 444 |
out_uint16_le(s, 0xca03); |
| 445 |
break; |
| 446 |
case 24: |
| 447 |
out_uint16_le(s, 0xca04); |
| 448 |
break; |
| 449 |
} |
| 450 |
out_uint16(s, 1); |
| 451 |
|
| 452 |
out_uint32(s, 0); |
| 453 |
out_uint32_le(s, 0x070008); |
| 454 |
out_uint32_le(s, 1); |
| 455 |
out_uint8s(s, 64); /* End of client info */ |
| 456 |
|
| 457 |
out_uint16_le(s, SEC_TAG_CLI_4); |
| 458 |
out_uint16_le(s, 12); |
| 459 |
out_uint32_le(s, 9); |
| 460 |
out_uint32_le(s, 0); |
| 461 |
|
| 462 |
/* Client encryption settings */ |
| 463 |
out_uint16_le(s, SEC_TAG_CLI_CRYPT); |
| 464 |
out_uint16_le(s, 12); /* length */ |
| 465 |
out_uint32_le(s, encryption ? 0x3 : 0); /* encryption supported, 128-bit supported */ |
| 466 |
out_uint32_le(s, 0); /* Unknown */ |
| 467 |
|
| 468 |
out_uint16_le(s, SEC_TAG_CLI_CHANNELS); |
| 469 |
out_uint16_le(s, 20); /* length */ |
| 470 |
out_uint32_le(s, 1); /* number of virtual channels */ |
| 471 |
out_uint8p(s, "cliprdr", 8); /* name padded to 8(?) */ |
| 472 |
out_uint16(s, 0); |
| 473 |
out_uint16_le(s, 0xc0a0); /* Flags. Rumours tell this is documented in MSDN. */ |
| 474 |
|
| 475 |
s_mark_end(s); |
| 476 |
} |
| 477 |
|
| 478 |
/* Parse a public key structure */ |
| 479 |
static BOOL |
| 480 |
sec_parse_public_key(STREAM s, uint8 ** modulus, uint8 ** exponent) |
| 481 |
{ |
| 482 |
uint32 magic, modulus_len; |
| 483 |
|
| 484 |
in_uint32_le(s, magic); |
| 485 |
if (magic != SEC_RSA_MAGIC) |
| 486 |
{ |
| 487 |
error("RSA magic 0x%x\n", magic); |
| 488 |
return False; |
| 489 |
} |
| 490 |
|
| 491 |
in_uint32_le(s, modulus_len); |
| 492 |
if (modulus_len != SEC_MODULUS_SIZE + SEC_PADDING_SIZE) |
| 493 |
{ |
| 494 |
error("modulus len 0x%x\n", modulus_len); |
| 495 |
return False; |
| 496 |
} |
| 497 |
|
| 498 |
in_uint8s(s, 8); /* modulus_bits, unknown */ |
| 499 |
in_uint8p(s, *exponent, SEC_EXPONENT_SIZE); |
| 500 |
in_uint8p(s, *modulus, SEC_MODULUS_SIZE); |
| 501 |
in_uint8s(s, SEC_PADDING_SIZE); |
| 502 |
|
| 503 |
return s_check(s); |
| 504 |
} |
| 505 |
|
| 506 |
static BOOL |
| 507 |
sec_parse_x509_key(X509 * cert) |
| 508 |
{ |
| 509 |
EVP_PKEY *epk = NULL; |
| 510 |
/* By some reason, Microsoft sets the OID of the Public RSA key to |
| 511 |
the oid for "MD5 with RSA Encryption" instead of "RSA Encryption" |
| 512 |
|
| 513 |
Kudos to Richard Levitte for the following (. intiutive .) |
| 514 |
lines of code that resets the OID and let's us extract the key. */ |
| 515 |
if (OBJ_obj2nid(cert->cert_info->key->algor->algorithm) == NID_md5WithRSAEncryption) |
| 516 |
{ |
| 517 |
DEBUG_RDP5(("Re-setting algorithm type to RSA in server certificate\n")); |
| 518 |
cert->cert_info->key->algor->algorithm = OBJ_nid2obj(NID_rsaEncryption); |
| 519 |
} |
| 520 |
epk = X509_get_pubkey(cert); |
| 521 |
if (NULL == epk) |
| 522 |
{ |
| 523 |
error("Failed to extract public key from certificate\n"); |
| 524 |
return False; |
| 525 |
} |
| 526 |
|
| 527 |
server_public_key = (RSA *) epk->pkey.ptr; |
| 528 |
|
| 529 |
return True; |
| 530 |
} |
| 531 |
|
| 532 |
|
| 533 |
/* Parse a crypto information structure */ |
| 534 |
static BOOL |
| 535 |
sec_parse_crypt_info(STREAM s, uint32 * rc4_key_size, |
| 536 |
uint8 ** server_random, uint8 ** modulus, uint8 ** exponent) |
| 537 |
{ |
| 538 |
uint32 crypt_level, random_len, rsa_info_len; |
| 539 |
uint32 cacert_len, cert_len; |
| 540 |
X509 *cacert, *server_cert; |
| 541 |
uint16 tag, length; |
| 542 |
uint8 *next_tag, *end; |
| 543 |
|
| 544 |
in_uint32_le(s, *rc4_key_size); /* 1 = 40-bit, 2 = 128-bit */ |
| 545 |
in_uint32_le(s, crypt_level); /* 1 = low, 2 = medium, 3 = high */ |
| 546 |
if (crypt_level == 0) /* no encryption */ |
| 547 |
return False; |
| 548 |
in_uint32_le(s, random_len); |
| 549 |
in_uint32_le(s, rsa_info_len); |
| 550 |
|
| 551 |
if (random_len != SEC_RANDOM_SIZE) |
| 552 |
{ |
| 553 |
error("random len %d, expected %d\n", random_len, SEC_RANDOM_SIZE); |
| 554 |
return False; |
| 555 |
} |
| 556 |
|
| 557 |
in_uint8p(s, *server_random, random_len); |
| 558 |
|
| 559 |
/* RSA info */ |
| 560 |
end = s->p + rsa_info_len; |
| 561 |
if (end > s->end) |
| 562 |
return False; |
| 563 |
|
| 564 |
if (!use_rdp5 || 1 == server_rdp_version) |
| 565 |
{ |
| 566 |
DEBUG_RDP5(("We're going for the RDP4-style encryption\n")); |
| 567 |
in_uint8s(s, 12); /* unknown */ |
| 568 |
|
| 569 |
while (s->p < end) |
| 570 |
{ |
| 571 |
in_uint16_le(s, tag); |
| 572 |
in_uint16_le(s, length); |
| 573 |
|
| 574 |
next_tag = s->p + length; |
| 575 |
|
| 576 |
switch (tag) |
| 577 |
{ |
| 578 |
case SEC_TAG_PUBKEY: |
| 579 |
if (!sec_parse_public_key(s, modulus, exponent)) |
| 580 |
return False; |
| 581 |
DEBUG_RDP5(("Got Public key, RDP4-style\n")); |
| 582 |
|
| 583 |
break; |
| 584 |
|
| 585 |
case SEC_TAG_KEYSIG: |
| 586 |
/* Is this a Microsoft key that we just got? */ |
| 587 |
/* Care factor: zero! */ |
| 588 |
/* Actually, it would probably be a good idea to check if the public key is signed with this key, and then store this |
| 589 |
key as a known key of the hostname. This would prevent some MITM-attacks. */ |
| 590 |
break; |
| 591 |
|
| 592 |
default: |
| 593 |
unimpl("crypt tag 0x%x\n", tag); |
| 594 |
} |
| 595 |
|
| 596 |
s->p = next_tag; |
| 597 |
} |
| 598 |
} |
| 599 |
else if (4 == server_rdp_version) |
| 600 |
{ |
| 601 |
DEBUG_RDP5(("We're going for the RDP5-style encryption\n")); |
| 602 |
in_uint8s(s, 8); /* Unknown */ |
| 603 |
|
| 604 |
/* Do da funky X.509 stuffy |
| 605 |
|
| 606 |
"How did I find out about this? I looked up and saw a |
| 607 |
bright light and when I came to I had a scar on my forehead |
| 608 |
and knew about X.500" |
| 609 |
- Peter Gutman in a early version of |
| 610 |
http://www.cs.auckland.ac.nz/~pgut001/pubs/x509guide.txt |
| 611 |
*/ |
| 612 |
|
| 613 |
in_uint32_le(s, cacert_len); |
| 614 |
cacert = d2i_X509(NULL, &(s->p), cacert_len); |
| 615 |
/* Note: We don't need to move s->p here - d2i_X509 is |
| 616 |
"kind" enough to do it for us */ |
| 617 |
if (NULL == cacert) |
| 618 |
{ |
| 619 |
error("Couldn't load CA Certificate from server\n"); |
| 620 |
return False; |
| 621 |
} |
| 622 |
|
| 623 |
/* Currently, we don't use the CA Certificate. |
| 624 |
FIXME: |
| 625 |
*) Verify the server certificate (server_cert) with the |
| 626 |
CA certificate. |
| 627 |
*) Store the CA Certificate with the hostname of the |
| 628 |
server we are connecting to as key, and compare it |
| 629 |
when we connect the next time, in order to prevent |
| 630 |
MITM-attacks. |
| 631 |
*/ |
| 632 |
|
| 633 |
in_uint32_le(s, cert_len); |
| 634 |
server_cert = d2i_X509(NULL, &(s->p), cert_len); |
| 635 |
if (NULL == server_cert) |
| 636 |
{ |
| 637 |
error("Couldn't load Certificate from server\n"); |
| 638 |
return False; |
| 639 |
} |
| 640 |
|
| 641 |
in_uint8s(s, 16); /* Padding */ |
| 642 |
|
| 643 |
/* Note: Verifying the server certificate must be done here, |
| 644 |
before sec_parse_public_key since we'll have to apply |
| 645 |
serious violence to the key after this */ |
| 646 |
|
| 647 |
if (!sec_parse_x509_key(server_cert)) |
| 648 |
{ |
| 649 |
DEBUG_RDP5(("Didn't parse X509 correctly\n")); |
| 650 |
return False; |
| 651 |
} |
| 652 |
return True; /* There's some garbage here we don't care about */ |
| 653 |
} |
| 654 |
else |
| 655 |
{ |
| 656 |
error("Unknown Server RDP version %d", server_rdp_version); |
| 657 |
return False; |
| 658 |
} |
| 659 |
return s_check_end(s); |
| 660 |
} |
| 661 |
|
| 662 |
/* Process crypto information blob */ |
| 663 |
static void |
| 664 |
sec_process_crypt_info(STREAM s) |
| 665 |
{ |
| 666 |
uint8 *server_random, *modulus, *exponent; |
| 667 |
uint8 client_random[SEC_RANDOM_SIZE]; |
| 668 |
uint32 rc4_key_size; |
| 669 |
uint8 inr[SEC_MODULUS_SIZE]; |
| 670 |
|
| 671 |
if (!sec_parse_crypt_info(s, &rc4_key_size, &server_random, &modulus, &exponent)) |
| 672 |
{ |
| 673 |
DEBUG(("Failed to parse crypt info\n")); |
| 674 |
return; |
| 675 |
} |
| 676 |
|
| 677 |
DEBUG(("Generating client random\n")); |
| 678 |
/* Generate a client random, and hence determine encryption keys */ |
| 679 |
generate_random(inr); |
| 680 |
// This is what the MS client do: |
| 681 |
// memset(inr, 0, SEC_RANDOM_SIZE); |
| 682 |
// *ARIGL!* |
| 683 |
generate_random(client_random); |
| 684 |
if (NULL != server_public_key) |
| 685 |
{ /* Which means we should use |
| 686 |
RDP5-style encryption */ |
| 687 |
|
| 688 |
memcpy(inr + SEC_RANDOM_SIZE, client_random, SEC_RANDOM_SIZE); |
| 689 |
reverse(inr + SEC_RANDOM_SIZE, SEC_RANDOM_SIZE); |
| 690 |
|
| 691 |
RSA_public_encrypt(SEC_MODULUS_SIZE, |
| 692 |
inr, sec_crypted_random, server_public_key, RSA_NO_PADDING); |
| 693 |
|
| 694 |
reverse(sec_crypted_random, SEC_MODULUS_SIZE); |
| 695 |
|
| 696 |
} |
| 697 |
else |
| 698 |
{ /* RDP4-style encryption */ |
| 699 |
sec_rsa_encrypt(sec_crypted_random, |
| 700 |
client_random, SEC_RANDOM_SIZE, modulus, exponent); |
| 701 |
} |
| 702 |
sec_generate_keys(client_random, server_random, rc4_key_size); |
| 703 |
} |
| 704 |
|
| 705 |
|
| 706 |
/* Process SRV_INFO, find RDP version supported by server */ |
| 707 |
static void |
| 708 |
sec_process_srv_info(STREAM s) |
| 709 |
{ |
| 710 |
in_uint16_le(s, server_rdp_version); |
| 711 |
DEBUG_RDP5(("Server RDP version is %d\n", server_rdp_version)); |
| 712 |
} |
| 713 |
|
| 714 |
|
| 715 |
/* Process connect response data blob */ |
| 716 |
void |
| 717 |
sec_process_mcs_data(STREAM s) |
| 718 |
{ |
| 719 |
uint16 tag, length; |
| 720 |
uint8 *next_tag; |
| 721 |
uint8 len; |
| 722 |
|
| 723 |
in_uint8s(s, 21); /* header (T.124 stuff, probably) */ |
| 724 |
in_uint8(s, len); |
| 725 |
if (len & 0x80) |
| 726 |
in_uint8(s, len); |
| 727 |
|
| 728 |
while (s->p < s->end) |
| 729 |
{ |
| 730 |
in_uint16_le(s, tag); |
| 731 |
in_uint16_le(s, length); |
| 732 |
|
| 733 |
if (length <= 4) |
| 734 |
return; |
| 735 |
|
| 736 |
next_tag = s->p + length - 4; |
| 737 |
|
| 738 |
switch (tag) |
| 739 |
{ |
| 740 |
case SEC_TAG_SRV_INFO: |
| 741 |
sec_process_srv_info(s); |
| 742 |
break; |
| 743 |
|
| 744 |
case SEC_TAG_SRV_3: |
| 745 |
break; |
| 746 |
|
| 747 |
case SEC_TAG_SRV_CRYPT: |
| 748 |
sec_process_crypt_info(s); |
| 749 |
break; |
| 750 |
|
| 751 |
default: |
| 752 |
unimpl("response tag 0x%x\n", tag); |
| 753 |
} |
| 754 |
|
| 755 |
s->p = next_tag; |
| 756 |
} |
| 757 |
} |
| 758 |
|
| 759 |
/* Receive secure transport packet */ |
| 760 |
STREAM |
| 761 |
sec_recv(void) |
| 762 |
{ |
| 763 |
uint32 sec_flags; |
| 764 |
uint16 channel; |
| 765 |
STREAM s; |
| 766 |
|
| 767 |
while ((s = mcs_recv(&channel)) != NULL) |
| 768 |
{ |
| 769 |
if (encryption || !licence_issued) |
| 770 |
{ |
| 771 |
in_uint32_le(s, sec_flags); |
| 772 |
|
| 773 |
if (sec_flags & SEC_LICENCE_NEG) |
| 774 |
{ |
| 775 |
licence_process(s); |
| 776 |
continue; |
| 777 |
} |
| 778 |
|
| 779 |
if (sec_flags & SEC_ENCRYPT) |
| 780 |
{ |
| 781 |
in_uint8s(s, 8); /* signature */ |
| 782 |
sec_decrypt(s->p, s->end - s->p); |
| 783 |
} |
| 784 |
} |
| 785 |
|
| 786 |
if (MCS_GLOBAL_CHANNEL == channel) |
| 787 |
{ |
| 788 |
return s; |
| 789 |
} |
| 790 |
else |
| 791 |
rdp5_process_channel(s, channel); |
| 792 |
|
| 793 |
} |
| 794 |
|
| 795 |
return NULL; |
| 796 |
} |
| 797 |
|
| 798 |
/* Establish a secure connection */ |
| 799 |
BOOL |
| 800 |
sec_connect(char *server, char *username) |
| 801 |
{ |
| 802 |
struct stream mcs_data; |
| 803 |
|
| 804 |
/* We exchange some RDP data during the MCS-Connect */ |
| 805 |
mcs_data.size = 512; |
| 806 |
mcs_data.p = mcs_data.data = xmalloc(mcs_data.size); |
| 807 |
sec_out_mcs_data(&mcs_data); |
| 808 |
|
| 809 |
if (!mcs_connect(server, &mcs_data, username)) |
| 810 |
return False; |
| 811 |
|
| 812 |
// sec_process_mcs_data(&mcs_data); |
| 813 |
if (encryption) |
| 814 |
sec_establish_key(); |
| 815 |
xfree(mcs_data.data); |
| 816 |
return True; |
| 817 |
} |
| 818 |
|
| 819 |
/* Disconnect a connection */ |
| 820 |
void |
| 821 |
sec_disconnect(void) |
| 822 |
{ |
| 823 |
mcs_disconnect(); |
| 824 |
} |
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