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/* -*- c-basic-offset: 8 -*- |
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rdesktop: A Remote Desktop Protocol client. |
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Protocol services - RDP encryption and licensing |
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Copyright (C) Matthew Chapman 1999-2005 |
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|
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This program is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 2 of the License, or |
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(at your option) any later version. |
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|
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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|
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You should have received a copy of the GNU General Public License |
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along with this program; if not, write to the Free Software |
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
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*/ |
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|
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#include "rdesktop.h" |
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|
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#include <openssl/rc4.h> |
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#include <openssl/md5.h> |
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#include <openssl/sha.h> |
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#include <openssl/bn.h> |
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#include <openssl/x509v3.h> |
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|
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extern char g_hostname[16]; |
30 |
extern int g_width; |
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extern int g_height; |
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extern unsigned int g_keylayout; |
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extern int g_keyboard_type; |
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extern int g_keyboard_subtype; |
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extern int g_keyboard_functionkeys; |
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extern BOOL g_encryption; |
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extern BOOL g_licence_issued; |
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extern BOOL g_use_rdp5; |
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extern BOOL g_console_session; |
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extern int g_server_depth; |
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extern uint16 mcs_userid; |
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extern VCHANNEL g_channels[]; |
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extern unsigned int g_num_channels; |
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|
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static int rc4_key_len; |
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static RC4_KEY rc4_decrypt_key; |
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static RC4_KEY rc4_encrypt_key; |
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static RSA *server_public_key; |
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static uint32 server_public_key_len; |
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|
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static uint8 sec_sign_key[16]; |
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static uint8 sec_decrypt_key[16]; |
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static uint8 sec_encrypt_key[16]; |
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static uint8 sec_decrypt_update_key[16]; |
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static uint8 sec_encrypt_update_key[16]; |
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static uint8 sec_crypted_random[SEC_MAX_MODULUS_SIZE]; |
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|
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uint16 g_server_rdp_version = 0; |
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|
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/* These values must be available to reset state - Session Directory */ |
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static int sec_encrypt_use_count = 0; |
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static int sec_decrypt_use_count = 0; |
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|
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/* |
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* I believe this is based on SSLv3 with the following differences: |
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* MAC algorithm (5.2.3.1) uses only 32-bit length in place of seq_num/type/length fields |
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* MAC algorithm uses SHA1 and MD5 for the two hash functions instead of one or other |
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* key_block algorithm (6.2.2) uses 'X', 'YY', 'ZZZ' instead of 'A', 'BB', 'CCC' |
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* key_block partitioning is different (16 bytes each: MAC secret, decrypt key, encrypt key) |
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* encryption/decryption keys updated every 4096 packets |
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* See http://wp.netscape.com/eng/ssl3/draft302.txt |
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*/ |
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|
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/* |
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* 48-byte transformation used to generate master secret (6.1) and key material (6.2.2). |
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* Both SHA1 and MD5 algorithms are used. |
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*/ |
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void |
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sec_hash_48(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2, uint8 salt) |
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{ |
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uint8 shasig[20]; |
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uint8 pad[4]; |
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SHA_CTX sha; |
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MD5_CTX md5; |
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int i; |
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|
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for (i = 0; i < 3; i++) |
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{ |
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memset(pad, salt + i, i + 1); |
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|
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SHA1_Init(&sha); |
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SHA1_Update(&sha, pad, i + 1); |
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SHA1_Update(&sha, in, 48); |
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SHA1_Update(&sha, salt1, 32); |
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SHA1_Update(&sha, salt2, 32); |
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SHA1_Final(shasig, &sha); |
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|
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MD5_Init(&md5); |
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MD5_Update(&md5, in, 48); |
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MD5_Update(&md5, shasig, 20); |
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MD5_Final(&out[i * 16], &md5); |
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} |
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} |
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|
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/* |
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* 16-byte transformation used to generate export keys (6.2.2). |
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*/ |
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void |
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sec_hash_16(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2) |
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{ |
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MD5_CTX md5; |
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|
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MD5_Init(&md5); |
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MD5_Update(&md5, in, 16); |
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MD5_Update(&md5, salt1, 32); |
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MD5_Update(&md5, salt2, 32); |
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MD5_Final(out, &md5); |
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} |
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|
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/* Reduce key entropy from 64 to 40 bits */ |
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static void |
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sec_make_40bit(uint8 * key) |
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{ |
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key[0] = 0xd1; |
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key[1] = 0x26; |
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key[2] = 0x9e; |
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} |
128 |
|
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/* Generate encryption keys given client and server randoms */ |
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static void |
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sec_generate_keys(uint8 * client_random, uint8 * server_random, int rc4_key_size) |
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{ |
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uint8 pre_master_secret[48]; |
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uint8 master_secret[48]; |
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uint8 key_block[48]; |
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|
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/* Construct pre-master secret */ |
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memcpy(pre_master_secret, client_random, 24); |
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memcpy(pre_master_secret + 24, server_random, 24); |
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|
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/* Generate master secret and then key material */ |
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sec_hash_48(master_secret, pre_master_secret, client_random, server_random, 'A'); |
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sec_hash_48(key_block, master_secret, client_random, server_random, 'X'); |
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|
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/* First 16 bytes of key material is MAC secret */ |
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memcpy(sec_sign_key, key_block, 16); |
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|
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/* Generate export keys from next two blocks of 16 bytes */ |
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sec_hash_16(sec_decrypt_key, &key_block[16], client_random, server_random); |
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sec_hash_16(sec_encrypt_key, &key_block[32], client_random, server_random); |
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|
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if (rc4_key_size == 1) |
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{ |
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DEBUG(("40-bit encryption enabled\n")); |
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sec_make_40bit(sec_sign_key); |
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sec_make_40bit(sec_decrypt_key); |
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sec_make_40bit(sec_encrypt_key); |
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rc4_key_len = 8; |
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} |
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else |
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{ |
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DEBUG(("rc_4_key_size == %d, 128-bit encryption enabled\n", rc4_key_size)); |
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rc4_key_len = 16; |
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} |
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|
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/* Save initial RC4 keys as update keys */ |
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memcpy(sec_decrypt_update_key, sec_decrypt_key, 16); |
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memcpy(sec_encrypt_update_key, sec_encrypt_key, 16); |
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|
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/* Initialise RC4 state arrays */ |
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RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key); |
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RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key); |
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} |
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|
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static uint8 pad_54[40] = { |
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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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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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}; |
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|
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static uint8 pad_92[48] = { |
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92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, |
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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, |
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92, 92, 92, 92, 92, 92, 92 |
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}; |
188 |
|
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/* Output a uint32 into a buffer (little-endian) */ |
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void |
191 |
buf_out_uint32(uint8 * buffer, uint32 value) |
192 |
{ |
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buffer[0] = (value) & 0xff; |
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buffer[1] = (value >> 8) & 0xff; |
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buffer[2] = (value >> 16) & 0xff; |
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buffer[3] = (value >> 24) & 0xff; |
197 |
} |
198 |
|
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/* Generate a MAC hash (5.2.3.1), using a combination of SHA1 and MD5 */ |
200 |
void |
201 |
sec_sign(uint8 * signature, int siglen, uint8 * session_key, int keylen, uint8 * data, int datalen) |
202 |
{ |
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uint8 shasig[20]; |
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uint8 md5sig[16]; |
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uint8 lenhdr[4]; |
206 |
SHA_CTX sha; |
207 |
MD5_CTX md5; |
208 |
|
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buf_out_uint32(lenhdr, datalen); |
210 |
|
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SHA1_Init(&sha); |
212 |
SHA1_Update(&sha, session_key, keylen); |
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SHA1_Update(&sha, pad_54, 40); |
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SHA1_Update(&sha, lenhdr, 4); |
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SHA1_Update(&sha, data, datalen); |
216 |
SHA1_Final(shasig, &sha); |
217 |
|
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MD5_Init(&md5); |
219 |
MD5_Update(&md5, session_key, keylen); |
220 |
MD5_Update(&md5, pad_92, 48); |
221 |
MD5_Update(&md5, shasig, 20); |
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MD5_Final(md5sig, &md5); |
223 |
|
224 |
memcpy(signature, md5sig, siglen); |
225 |
} |
226 |
|
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/* Update an encryption key */ |
228 |
static void |
229 |
sec_update(uint8 * key, uint8 * update_key) |
230 |
{ |
231 |
uint8 shasig[20]; |
232 |
SHA_CTX sha; |
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MD5_CTX md5; |
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RC4_KEY update; |
235 |
|
236 |
SHA1_Init(&sha); |
237 |
SHA1_Update(&sha, update_key, rc4_key_len); |
238 |
SHA1_Update(&sha, pad_54, 40); |
239 |
SHA1_Update(&sha, key, rc4_key_len); |
240 |
SHA1_Final(shasig, &sha); |
241 |
|
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MD5_Init(&md5); |
243 |
MD5_Update(&md5, update_key, rc4_key_len); |
244 |
MD5_Update(&md5, pad_92, 48); |
245 |
MD5_Update(&md5, shasig, 20); |
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MD5_Final(key, &md5); |
247 |
|
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RC4_set_key(&update, rc4_key_len, key); |
249 |
RC4(&update, rc4_key_len, key, key); |
250 |
|
251 |
if (rc4_key_len == 8) |
252 |
sec_make_40bit(key); |
253 |
} |
254 |
|
255 |
/* Encrypt data using RC4 */ |
256 |
static void |
257 |
sec_encrypt(uint8 * data, int length) |
258 |
{ |
259 |
if (sec_encrypt_use_count == 4096) |
260 |
{ |
261 |
sec_update(sec_encrypt_key, sec_encrypt_update_key); |
262 |
RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key); |
263 |
sec_encrypt_use_count = 0; |
264 |
} |
265 |
|
266 |
RC4(&rc4_encrypt_key, length, data, data); |
267 |
sec_encrypt_use_count++; |
268 |
} |
269 |
|
270 |
/* Decrypt data using RC4 */ |
271 |
void |
272 |
sec_decrypt(uint8 * data, int length) |
273 |
{ |
274 |
if (sec_decrypt_use_count == 4096) |
275 |
{ |
276 |
sec_update(sec_decrypt_key, sec_decrypt_update_key); |
277 |
RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key); |
278 |
sec_decrypt_use_count = 0; |
279 |
} |
280 |
|
281 |
RC4(&rc4_decrypt_key, length, data, data); |
282 |
sec_decrypt_use_count++; |
283 |
} |
284 |
|
285 |
static void |
286 |
reverse(uint8 * p, int len) |
287 |
{ |
288 |
int i, j; |
289 |
uint8 temp; |
290 |
|
291 |
for (i = 0, j = len - 1; i < j; i++, j--) |
292 |
{ |
293 |
temp = p[i]; |
294 |
p[i] = p[j]; |
295 |
p[j] = temp; |
296 |
} |
297 |
} |
298 |
|
299 |
/* Perform an RSA public key encryption operation */ |
300 |
static void |
301 |
sec_rsa_encrypt(uint8 * out, uint8 * in, int len, uint32 modulus_size, uint8 * modulus, |
302 |
uint8 * exponent) |
303 |
{ |
304 |
BN_CTX *ctx; |
305 |
BIGNUM mod, exp, x, y; |
306 |
uint8 inr[SEC_MAX_MODULUS_SIZE]; |
307 |
int outlen; |
308 |
|
309 |
reverse(modulus, modulus_size); |
310 |
reverse(exponent, SEC_EXPONENT_SIZE); |
311 |
memcpy(inr, in, len); |
312 |
reverse(inr, len); |
313 |
|
314 |
ctx = BN_CTX_new(); |
315 |
BN_init(&mod); |
316 |
BN_init(&exp); |
317 |
BN_init(&x); |
318 |
BN_init(&y); |
319 |
|
320 |
BN_bin2bn(modulus, modulus_size, &mod); |
321 |
BN_bin2bn(exponent, SEC_EXPONENT_SIZE, &exp); |
322 |
BN_bin2bn(inr, len, &x); |
323 |
BN_mod_exp(&y, &x, &exp, &mod, ctx); |
324 |
outlen = BN_bn2bin(&y, out); |
325 |
reverse(out, outlen); |
326 |
if (outlen < modulus_size) |
327 |
memset(out + outlen, 0, modulus_size - outlen); |
328 |
|
329 |
BN_free(&y); |
330 |
BN_clear_free(&x); |
331 |
BN_free(&exp); |
332 |
BN_free(&mod); |
333 |
BN_CTX_free(ctx); |
334 |
} |
335 |
|
336 |
/* Initialise secure transport packet */ |
337 |
STREAM |
338 |
sec_init(uint32 flags, int maxlen) |
339 |
{ |
340 |
int hdrlen; |
341 |
STREAM s; |
342 |
|
343 |
if (!g_licence_issued) |
344 |
hdrlen = (flags & SEC_ENCRYPT) ? 12 : 4; |
345 |
else |
346 |
hdrlen = (flags & SEC_ENCRYPT) ? 12 : 0; |
347 |
s = mcs_init(maxlen + hdrlen); |
348 |
s_push_layer(s, sec_hdr, hdrlen); |
349 |
|
350 |
return s; |
351 |
} |
352 |
|
353 |
/* Transmit secure transport packet over specified channel */ |
354 |
void |
355 |
sec_send_to_channel(STREAM s, uint32 flags, uint16 channel) |
356 |
{ |
357 |
int datalen; |
358 |
|
359 |
s_pop_layer(s, sec_hdr); |
360 |
if (!g_licence_issued || (flags & SEC_ENCRYPT)) |
361 |
out_uint32_le(s, flags); |
362 |
|
363 |
if (flags & SEC_ENCRYPT) |
364 |
{ |
365 |
flags &= ~SEC_ENCRYPT; |
366 |
datalen = s->end - s->p - 8; |
367 |
|
368 |
#if WITH_DEBUG |
369 |
DEBUG(("Sending encrypted packet:\n")); |
370 |
hexdump(s->p + 8, datalen); |
371 |
#endif |
372 |
|
373 |
sec_sign(s->p, 8, sec_sign_key, rc4_key_len, s->p + 8, datalen); |
374 |
sec_encrypt(s->p + 8, datalen); |
375 |
} |
376 |
|
377 |
mcs_send_to_channel(s, channel); |
378 |
} |
379 |
|
380 |
/* Transmit secure transport packet */ |
381 |
|
382 |
void |
383 |
sec_send(STREAM s, uint32 flags) |
384 |
{ |
385 |
sec_send_to_channel(s, flags, MCS_GLOBAL_CHANNEL); |
386 |
} |
387 |
|
388 |
|
389 |
/* Transfer the client random to the server */ |
390 |
static void |
391 |
sec_establish_key(void) |
392 |
{ |
393 |
uint32 length = server_public_key_len + SEC_PADDING_SIZE; |
394 |
uint32 flags = SEC_CLIENT_RANDOM; |
395 |
STREAM s; |
396 |
|
397 |
s = sec_init(flags, length + 4); |
398 |
|
399 |
out_uint32_le(s, length); |
400 |
out_uint8p(s, sec_crypted_random, server_public_key_len); |
401 |
out_uint8s(s, SEC_PADDING_SIZE); |
402 |
|
403 |
s_mark_end(s); |
404 |
sec_send(s, flags); |
405 |
} |
406 |
|
407 |
/* Output connect initial data blob */ |
408 |
static void |
409 |
sec_out_mcs_data(STREAM s) |
410 |
{ |
411 |
int hostlen = 2 * strlen(g_hostname); |
412 |
int length = 158 + 76 + 12 + 4; |
413 |
unsigned int i; |
414 |
|
415 |
if (g_num_channels > 0) |
416 |
length += g_num_channels * 12 + 8; |
417 |
|
418 |
if (hostlen > 30) |
419 |
hostlen = 30; |
420 |
|
421 |
/* Generic Conference Control (T.124) ConferenceCreateRequest */ |
422 |
out_uint16_be(s, 5); |
423 |
out_uint16_be(s, 0x14); |
424 |
out_uint8(s, 0x7c); |
425 |
out_uint16_be(s, 1); |
426 |
|
427 |
out_uint16_be(s, (length | 0x8000)); /* remaining length */ |
428 |
|
429 |
out_uint16_be(s, 8); /* length? */ |
430 |
out_uint16_be(s, 16); |
431 |
out_uint8(s, 0); |
432 |
out_uint16_le(s, 0xc001); |
433 |
out_uint8(s, 0); |
434 |
|
435 |
out_uint32_le(s, 0x61637544); /* OEM ID: "Duca", as in Ducati. */ |
436 |
out_uint16_be(s, ((length - 14) | 0x8000)); /* remaining length */ |
437 |
|
438 |
/* Client information */ |
439 |
out_uint16_le(s, SEC_TAG_CLI_INFO); |
440 |
out_uint16_le(s, 212); /* length */ |
441 |
out_uint16_le(s, g_use_rdp5 ? 4 : 1); /* RDP version. 1 == RDP4, 4 == RDP5. */ |
442 |
out_uint16_le(s, 8); |
443 |
out_uint16_le(s, g_width); |
444 |
out_uint16_le(s, g_height); |
445 |
out_uint16_le(s, 0xca01); |
446 |
out_uint16_le(s, 0xaa03); |
447 |
out_uint32_le(s, g_keylayout); |
448 |
out_uint32_le(s, 2600); /* Client build. We are now 2600 compatible :-) */ |
449 |
|
450 |
/* Unicode name of client, padded to 32 bytes */ |
451 |
rdp_out_unistr(s, g_hostname, hostlen); |
452 |
out_uint8s(s, 30 - hostlen); |
453 |
|
454 |
/* See |
455 |
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wceddk40/html/cxtsksupportingremotedesktopprotocol.asp */ |
456 |
out_uint32_le(s, g_keyboard_type); |
457 |
out_uint32_le(s, g_keyboard_subtype); |
458 |
out_uint32_le(s, g_keyboard_functionkeys); |
459 |
out_uint8s(s, 64); /* reserved? 4 + 12 doublewords */ |
460 |
out_uint16_le(s, 0xca01); /* colour depth? */ |
461 |
out_uint16_le(s, 1); |
462 |
|
463 |
out_uint32(s, 0); |
464 |
out_uint8(s, g_server_depth); |
465 |
out_uint16_le(s, 0x0700); |
466 |
out_uint8(s, 0); |
467 |
out_uint32_le(s, 1); |
468 |
out_uint8s(s, 64); /* End of client info */ |
469 |
|
470 |
out_uint16_le(s, SEC_TAG_CLI_4); |
471 |
out_uint16_le(s, 12); |
472 |
out_uint32_le(s, g_console_session ? 0xb : 9); |
473 |
out_uint32(s, 0); |
474 |
|
475 |
/* Client encryption settings */ |
476 |
out_uint16_le(s, SEC_TAG_CLI_CRYPT); |
477 |
out_uint16_le(s, 12); /* length */ |
478 |
out_uint32_le(s, g_encryption ? 0x3 : 0); /* encryption supported, 128-bit supported */ |
479 |
out_uint32(s, 0); /* Unknown */ |
480 |
|
481 |
DEBUG_RDP5(("g_num_channels is %d\n", g_num_channels)); |
482 |
if (g_num_channels > 0) |
483 |
{ |
484 |
out_uint16_le(s, SEC_TAG_CLI_CHANNELS); |
485 |
out_uint16_le(s, g_num_channels * 12 + 8); /* length */ |
486 |
out_uint32_le(s, g_num_channels); /* number of virtual channels */ |
487 |
for (i = 0; i < g_num_channels; i++) |
488 |
{ |
489 |
DEBUG_RDP5(("Requesting channel %s\n", g_channels[i].name)); |
490 |
out_uint8a(s, g_channels[i].name, 8); |
491 |
out_uint32_be(s, g_channels[i].flags); |
492 |
} |
493 |
} |
494 |
|
495 |
s_mark_end(s); |
496 |
} |
497 |
|
498 |
/* Parse a public key structure */ |
499 |
static BOOL |
500 |
sec_parse_public_key(STREAM s, uint8 ** modulus, uint8 ** exponent) |
501 |
{ |
502 |
uint32 magic, modulus_len; |
503 |
|
504 |
in_uint32_le(s, magic); |
505 |
if (magic != SEC_RSA_MAGIC) |
506 |
{ |
507 |
error("RSA magic 0x%x\n", magic); |
508 |
return False; |
509 |
} |
510 |
|
511 |
in_uint32_le(s, modulus_len); |
512 |
modulus_len -= SEC_PADDING_SIZE; |
513 |
if ((modulus_len < 64) || (modulus_len > SEC_MAX_MODULUS_SIZE)) |
514 |
{ |
515 |
error("Bad server public key size (%u bits)\n", modulus_len * 8); |
516 |
return False; |
517 |
} |
518 |
|
519 |
in_uint8s(s, 8); /* modulus_bits, unknown */ |
520 |
in_uint8p(s, *exponent, SEC_EXPONENT_SIZE); |
521 |
in_uint8p(s, *modulus, modulus_len); |
522 |
in_uint8s(s, SEC_PADDING_SIZE); |
523 |
server_public_key_len = modulus_len; |
524 |
|
525 |
return s_check(s); |
526 |
} |
527 |
|
528 |
static BOOL |
529 |
sec_parse_x509_key(X509 * cert) |
530 |
{ |
531 |
EVP_PKEY *epk = NULL; |
532 |
/* By some reason, Microsoft sets the OID of the Public RSA key to |
533 |
the oid for "MD5 with RSA Encryption" instead of "RSA Encryption" |
534 |
|
535 |
Kudos to Richard Levitte for the following (. intiutive .) |
536 |
lines of code that resets the OID and let's us extract the key. */ |
537 |
if (OBJ_obj2nid(cert->cert_info->key->algor->algorithm) == NID_md5WithRSAEncryption) |
538 |
{ |
539 |
DEBUG_RDP5(("Re-setting algorithm type to RSA in server certificate\n")); |
540 |
ASN1_OBJECT_free(cert->cert_info->key->algor->algorithm); |
541 |
cert->cert_info->key->algor->algorithm = OBJ_nid2obj(NID_rsaEncryption); |
542 |
} |
543 |
epk = X509_get_pubkey(cert); |
544 |
if (NULL == epk) |
545 |
{ |
546 |
error("Failed to extract public key from certificate\n"); |
547 |
return False; |
548 |
} |
549 |
|
550 |
server_public_key = RSAPublicKey_dup((RSA *) epk->pkey.ptr); |
551 |
EVP_PKEY_free(epk); |
552 |
|
553 |
server_public_key_len = RSA_size(server_public_key); |
554 |
if ((server_public_key_len < 64) || (server_public_key_len > SEC_MAX_MODULUS_SIZE)) |
555 |
{ |
556 |
error("Bad server public key size (%u bits)\n", server_public_key_len * 8); |
557 |
return False; |
558 |
} |
559 |
|
560 |
return True; |
561 |
} |
562 |
|
563 |
|
564 |
/* Parse a crypto information structure */ |
565 |
static BOOL |
566 |
sec_parse_crypt_info(STREAM s, uint32 * rc4_key_size, |
567 |
uint8 ** server_random, uint8 ** modulus, uint8 ** exponent) |
568 |
{ |
569 |
uint32 crypt_level, random_len, rsa_info_len; |
570 |
uint32 cacert_len, cert_len, flags; |
571 |
X509 *cacert, *server_cert; |
572 |
uint16 tag, length; |
573 |
uint8 *next_tag, *end; |
574 |
|
575 |
in_uint32_le(s, *rc4_key_size); /* 1 = 40-bit, 2 = 128-bit */ |
576 |
in_uint32_le(s, crypt_level); /* 1 = low, 2 = medium, 3 = high */ |
577 |
if (crypt_level == 0) /* no encryption */ |
578 |
return False; |
579 |
in_uint32_le(s, random_len); |
580 |
in_uint32_le(s, rsa_info_len); |
581 |
|
582 |
if (random_len != SEC_RANDOM_SIZE) |
583 |
{ |
584 |
error("random len %d, expected %d\n", random_len, SEC_RANDOM_SIZE); |
585 |
return False; |
586 |
} |
587 |
|
588 |
in_uint8p(s, *server_random, random_len); |
589 |
|
590 |
/* RSA info */ |
591 |
end = s->p + rsa_info_len; |
592 |
if (end > s->end) |
593 |
return False; |
594 |
|
595 |
in_uint32_le(s, flags); /* 1 = RDP4-style, 0x80000002 = X.509 */ |
596 |
if (flags & 1) |
597 |
{ |
598 |
DEBUG_RDP5(("We're going for the RDP4-style encryption\n")); |
599 |
in_uint8s(s, 8); /* unknown */ |
600 |
|
601 |
while (s->p < end) |
602 |
{ |
603 |
in_uint16_le(s, tag); |
604 |
in_uint16_le(s, length); |
605 |
|
606 |
next_tag = s->p + length; |
607 |
|
608 |
switch (tag) |
609 |
{ |
610 |
case SEC_TAG_PUBKEY: |
611 |
if (!sec_parse_public_key(s, modulus, exponent)) |
612 |
return False; |
613 |
DEBUG_RDP5(("Got Public key, RDP4-style\n")); |
614 |
|
615 |
break; |
616 |
|
617 |
case SEC_TAG_KEYSIG: |
618 |
/* Is this a Microsoft key that we just got? */ |
619 |
/* Care factor: zero! */ |
620 |
/* Actually, it would probably be a good idea to check if the public key is signed with this key, and then store this |
621 |
key as a known key of the hostname. This would prevent some MITM-attacks. */ |
622 |
break; |
623 |
|
624 |
default: |
625 |
unimpl("crypt tag 0x%x\n", tag); |
626 |
} |
627 |
|
628 |
s->p = next_tag; |
629 |
} |
630 |
} |
631 |
else |
632 |
{ |
633 |
uint32 certcount; |
634 |
|
635 |
DEBUG_RDP5(("We're going for the RDP5-style encryption\n")); |
636 |
in_uint32_le(s, certcount); /* Number of certificates */ |
637 |
|
638 |
if (certcount < 2) |
639 |
{ |
640 |
error("Server didn't send enough X509 certificates\n"); |
641 |
return False; |
642 |
} |
643 |
|
644 |
for (; certcount > 2; certcount--) |
645 |
{ /* ignore all the certificates between the root and the signing CA */ |
646 |
uint32 ignorelen; |
647 |
X509 *ignorecert; |
648 |
|
649 |
DEBUG_RDP5(("Ignored certs left: %d\n", certcount)); |
650 |
|
651 |
in_uint32_le(s, ignorelen); |
652 |
DEBUG_RDP5(("Ignored Certificate length is %d\n", ignorelen)); |
653 |
ignorecert = d2i_X509(NULL, &(s->p), ignorelen); |
654 |
|
655 |
if (ignorecert == NULL) |
656 |
{ /* XXX: error out? */ |
657 |
DEBUG_RDP5(("got a bad cert: this will probably screw up the rest of the communication\n")); |
658 |
} |
659 |
|
660 |
#ifdef WITH_DEBUG_RDP5 |
661 |
DEBUG_RDP5(("cert #%d (ignored):\n", certcount)); |
662 |
X509_print_fp(stdout, ignorecert); |
663 |
#endif |
664 |
} |
665 |
|
666 |
/* Do da funky X.509 stuffy |
667 |
|
668 |
"How did I find out about this? I looked up and saw a |
669 |
bright light and when I came to I had a scar on my forehead |
670 |
and knew about X.500" |
671 |
- Peter Gutman in a early version of |
672 |
http://www.cs.auckland.ac.nz/~pgut001/pubs/x509guide.txt |
673 |
*/ |
674 |
|
675 |
in_uint32_le(s, cacert_len); |
676 |
DEBUG_RDP5(("CA Certificate length is %d\n", cacert_len)); |
677 |
cacert = d2i_X509(NULL, &(s->p), cacert_len); |
678 |
/* Note: We don't need to move s->p here - d2i_X509 is |
679 |
"kind" enough to do it for us */ |
680 |
if (NULL == cacert) |
681 |
{ |
682 |
error("Couldn't load CA Certificate from server\n"); |
683 |
return False; |
684 |
} |
685 |
|
686 |
/* Currently, we don't use the CA Certificate. |
687 |
FIXME: |
688 |
*) Verify the server certificate (server_cert) with the |
689 |
CA certificate. |
690 |
*) Store the CA Certificate with the hostname of the |
691 |
server we are connecting to as key, and compare it |
692 |
when we connect the next time, in order to prevent |
693 |
MITM-attacks. |
694 |
*/ |
695 |
|
696 |
X509_free(cacert); |
697 |
|
698 |
in_uint32_le(s, cert_len); |
699 |
DEBUG_RDP5(("Certificate length is %d\n", cert_len)); |
700 |
server_cert = d2i_X509(NULL, &(s->p), cert_len); |
701 |
if (NULL == server_cert) |
702 |
{ |
703 |
error("Couldn't load Certificate from server\n"); |
704 |
return False; |
705 |
} |
706 |
|
707 |
in_uint8s(s, 16); /* Padding */ |
708 |
|
709 |
/* Note: Verifying the server certificate must be done here, |
710 |
before sec_parse_public_key since we'll have to apply |
711 |
serious violence to the key after this */ |
712 |
|
713 |
if (!sec_parse_x509_key(server_cert)) |
714 |
{ |
715 |
DEBUG_RDP5(("Didn't parse X509 correctly\n")); |
716 |
X509_free(server_cert); |
717 |
return False; |
718 |
} |
719 |
X509_free(server_cert); |
720 |
return True; /* There's some garbage here we don't care about */ |
721 |
} |
722 |
return s_check_end(s); |
723 |
} |
724 |
|
725 |
/* Process crypto information blob */ |
726 |
static void |
727 |
sec_process_crypt_info(STREAM s) |
728 |
{ |
729 |
uint8 *server_random = NULL, *modulus = NULL, *exponent = NULL; |
730 |
uint8 client_random[SEC_RANDOM_SIZE]; |
731 |
uint32 rc4_key_size; |
732 |
|
733 |
if (!sec_parse_crypt_info(s, &rc4_key_size, &server_random, &modulus, &exponent)) |
734 |
{ |
735 |
DEBUG(("Failed to parse crypt info\n")); |
736 |
return; |
737 |
} |
738 |
|
739 |
DEBUG(("Generating client random\n")); |
740 |
generate_random(client_random); |
741 |
|
742 |
if (NULL != server_public_key) |
743 |
{ /* Which means we should use |
744 |
RDP5-style encryption */ |
745 |
uint8 inr[SEC_MAX_MODULUS_SIZE]; |
746 |
uint32 padding_len = server_public_key_len - SEC_RANDOM_SIZE; |
747 |
|
748 |
/* This is what the MS client do: */ |
749 |
memset(inr, 0, padding_len); |
750 |
/* *ARIGL!* Plaintext attack, anyone? |
751 |
I tried doing: |
752 |
generate_random(inr); |
753 |
..but that generates connection errors now and then (yes, |
754 |
"now and then". Something like 0 to 3 attempts needed before a |
755 |
successful connection. Nice. Not! |
756 |
*/ |
757 |
memcpy(inr + padding_len, client_random, SEC_RANDOM_SIZE); |
758 |
reverse(inr + padding_len, SEC_RANDOM_SIZE); |
759 |
|
760 |
RSA_public_encrypt(server_public_key_len, |
761 |
inr, sec_crypted_random, server_public_key, RSA_NO_PADDING); |
762 |
|
763 |
reverse(sec_crypted_random, server_public_key_len); |
764 |
|
765 |
RSA_free(server_public_key); |
766 |
server_public_key = NULL; |
767 |
} |
768 |
else |
769 |
{ /* RDP4-style encryption */ |
770 |
sec_rsa_encrypt(sec_crypted_random, |
771 |
client_random, SEC_RANDOM_SIZE, server_public_key_len, modulus, |
772 |
exponent); |
773 |
} |
774 |
sec_generate_keys(client_random, server_random, rc4_key_size); |
775 |
} |
776 |
|
777 |
|
778 |
/* Process SRV_INFO, find RDP version supported by server */ |
779 |
static void |
780 |
sec_process_srv_info(STREAM s) |
781 |
{ |
782 |
in_uint16_le(s, g_server_rdp_version); |
783 |
DEBUG_RDP5(("Server RDP version is %d\n", g_server_rdp_version)); |
784 |
if (1 == g_server_rdp_version) |
785 |
{ |
786 |
g_use_rdp5 = 0; |
787 |
g_server_depth = 8; |
788 |
} |
789 |
} |
790 |
|
791 |
|
792 |
/* Process connect response data blob */ |
793 |
void |
794 |
sec_process_mcs_data(STREAM s) |
795 |
{ |
796 |
uint16 tag, length; |
797 |
uint8 *next_tag; |
798 |
uint8 len; |
799 |
|
800 |
in_uint8s(s, 21); /* header (T.124 ConferenceCreateResponse) */ |
801 |
in_uint8(s, len); |
802 |
if (len & 0x80) |
803 |
in_uint8(s, len); |
804 |
|
805 |
while (s->p < s->end) |
806 |
{ |
807 |
in_uint16_le(s, tag); |
808 |
in_uint16_le(s, length); |
809 |
|
810 |
if (length <= 4) |
811 |
return; |
812 |
|
813 |
next_tag = s->p + length - 4; |
814 |
|
815 |
switch (tag) |
816 |
{ |
817 |
case SEC_TAG_SRV_INFO: |
818 |
sec_process_srv_info(s); |
819 |
break; |
820 |
|
821 |
case SEC_TAG_SRV_CRYPT: |
822 |
sec_process_crypt_info(s); |
823 |
break; |
824 |
|
825 |
case SEC_TAG_SRV_CHANNELS: |
826 |
/* FIXME: We should parse this information and |
827 |
use it to map RDP5 channels to MCS |
828 |
channels */ |
829 |
break; |
830 |
|
831 |
default: |
832 |
unimpl("response tag 0x%x\n", tag); |
833 |
} |
834 |
|
835 |
s->p = next_tag; |
836 |
} |
837 |
} |
838 |
|
839 |
/* Receive secure transport packet */ |
840 |
STREAM |
841 |
sec_recv(uint8 * rdpver) |
842 |
{ |
843 |
uint32 sec_flags; |
844 |
uint16 channel; |
845 |
STREAM s; |
846 |
|
847 |
while ((s = mcs_recv(&channel, rdpver)) != NULL) |
848 |
{ |
849 |
if (rdpver != NULL) |
850 |
{ |
851 |
if (*rdpver != 3) |
852 |
{ |
853 |
if (*rdpver & 0x80) |
854 |
{ |
855 |
in_uint8s(s, 8); /* signature */ |
856 |
sec_decrypt(s->p, s->end - s->p); |
857 |
} |
858 |
return s; |
859 |
} |
860 |
} |
861 |
if (g_encryption || !g_licence_issued) |
862 |
{ |
863 |
in_uint32_le(s, sec_flags); |
864 |
|
865 |
if (sec_flags & SEC_ENCRYPT) |
866 |
{ |
867 |
in_uint8s(s, 8); /* signature */ |
868 |
sec_decrypt(s->p, s->end - s->p); |
869 |
} |
870 |
|
871 |
if (sec_flags & SEC_LICENCE_NEG) |
872 |
{ |
873 |
licence_process(s); |
874 |
continue; |
875 |
} |
876 |
|
877 |
if (sec_flags & 0x0400) /* SEC_REDIRECT_ENCRYPT */ |
878 |
{ |
879 |
uint8 swapbyte; |
880 |
|
881 |
in_uint8s(s, 8); /* signature */ |
882 |
sec_decrypt(s->p, s->end - s->p); |
883 |
|
884 |
/* Check for a redirect packet, starts with 00 04 */ |
885 |
if (s->p[0] == 0 && s->p[1] == 4) |
886 |
{ |
887 |
/* for some reason the PDU and the length seem to be swapped. |
888 |
This isn't good, but we're going to do a byte for byte |
889 |
swap. So the first foure value appear as: 00 04 XX YY, |
890 |
where XX YY is the little endian length. We're going to |
891 |
use 04 00 as the PDU type, so after our swap this will look |
892 |
like: XX YY 04 00 */ |
893 |
swapbyte = s->p[0]; |
894 |
s->p[0] = s->p[2]; |
895 |
s->p[2] = swapbyte; |
896 |
|
897 |
swapbyte = s->p[1]; |
898 |
s->p[1] = s->p[3]; |
899 |
s->p[3] = swapbyte; |
900 |
|
901 |
swapbyte = s->p[2]; |
902 |
s->p[2] = s->p[3]; |
903 |
s->p[3] = swapbyte; |
904 |
} |
905 |
#ifdef WITH_DEBUG |
906 |
/* warning! this debug statement will show passwords in the clear! */ |
907 |
hexdump(s->p, s->end - s->p); |
908 |
#endif |
909 |
} |
910 |
|
911 |
} |
912 |
|
913 |
if (channel != MCS_GLOBAL_CHANNEL) |
914 |
{ |
915 |
channel_process(s, channel); |
916 |
*rdpver = 0xff; |
917 |
return s; |
918 |
} |
919 |
|
920 |
return s; |
921 |
} |
922 |
|
923 |
return NULL; |
924 |
} |
925 |
|
926 |
/* Establish a secure connection */ |
927 |
BOOL |
928 |
sec_connect(char *server, char *username) |
929 |
{ |
930 |
struct stream mcs_data; |
931 |
|
932 |
/* We exchange some RDP data during the MCS-Connect */ |
933 |
mcs_data.size = 512; |
934 |
mcs_data.p = mcs_data.data = (uint8 *) xmalloc(mcs_data.size); |
935 |
sec_out_mcs_data(&mcs_data); |
936 |
|
937 |
if (!mcs_connect(server, &mcs_data, username)) |
938 |
return False; |
939 |
|
940 |
/* sec_process_mcs_data(&mcs_data); */ |
941 |
if (g_encryption) |
942 |
sec_establish_key(); |
943 |
xfree(mcs_data.data); |
944 |
return True; |
945 |
} |
946 |
|
947 |
/* Establish a secure connection */ |
948 |
BOOL |
949 |
sec_reconnect(char *server) |
950 |
{ |
951 |
struct stream mcs_data; |
952 |
|
953 |
/* We exchange some RDP data during the MCS-Connect */ |
954 |
mcs_data.size = 512; |
955 |
mcs_data.p = mcs_data.data = (uint8 *) xmalloc(mcs_data.size); |
956 |
sec_out_mcs_data(&mcs_data); |
957 |
|
958 |
if (!mcs_reconnect(server, &mcs_data)) |
959 |
return False; |
960 |
|
961 |
/* sec_process_mcs_data(&mcs_data); */ |
962 |
if (g_encryption) |
963 |
sec_establish_key(); |
964 |
xfree(mcs_data.data); |
965 |
return True; |
966 |
} |
967 |
|
968 |
/* Disconnect a connection */ |
969 |
void |
970 |
sec_disconnect(void) |
971 |
{ |
972 |
mcs_disconnect(); |
973 |
} |
974 |
|
975 |
/* reset the state of the sec layer */ |
976 |
void |
977 |
sec_reset_state(void) |
978 |
{ |
979 |
g_server_rdp_version = 0; |
980 |
sec_encrypt_use_count = 0; |
981 |
sec_decrypt_use_count = 0; |
982 |
mcs_reset_state(); |
983 |
} |