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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 1999-2007 |
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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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#if defined(OPENSSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER >= 0x0090800f) |
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#define D2I_X509_CONST const |
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#else |
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#define D2I_X509_CONST |
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#endif |
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|
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extern char g_hostname[16]; |
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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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} |
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|
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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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}; |
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|
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/* Output a uint32 into a buffer (little-endian) */ |
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void |
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buf_out_uint32(uint8 * buffer, uint32 value) |
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{ |
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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; |
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} |
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|
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/* Generate a MAC hash (5.2.3.1), using a combination of SHA1 and MD5 */ |
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void |
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sec_sign(uint8 * signature, int siglen, uint8 * session_key, int keylen, uint8 * data, int datalen) |
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{ |
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uint8 shasig[20]; |
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uint8 md5sig[16]; |
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uint8 lenhdr[4]; |
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SHA_CTX sha; |
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MD5_CTX md5; |
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|
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buf_out_uint32(lenhdr, datalen); |
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|
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SHA1_Init(&sha); |
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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); |
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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, session_key, keylen); |
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MD5_Update(&md5, pad_92, 48); |
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MD5_Update(&md5, shasig, 20); |
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MD5_Final(md5sig, &md5); |
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|
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memcpy(signature, md5sig, siglen); |
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} |
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|
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/* Update an encryption key */ |
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static void |
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sec_update(uint8 * key, uint8 * update_key) |
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{ |
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uint8 shasig[20]; |
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SHA_CTX sha; |
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MD5_CTX md5; |
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RC4_KEY update; |
241 |
|
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SHA1_Init(&sha); |
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SHA1_Update(&sha, update_key, rc4_key_len); |
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SHA1_Update(&sha, pad_54, 40); |
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SHA1_Update(&sha, key, rc4_key_len); |
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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, update_key, rc4_key_len); |
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MD5_Update(&md5, pad_92, 48); |
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MD5_Update(&md5, shasig, 20); |
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MD5_Final(key, &md5); |
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|
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RC4_set_key(&update, rc4_key_len, key); |
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RC4(&update, rc4_key_len, key, key); |
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|
257 |
if (rc4_key_len == 8) |
258 |
sec_make_40bit(key); |
259 |
} |
260 |
|
261 |
/* Encrypt data using RC4 */ |
262 |
static void |
263 |
sec_encrypt(uint8 * data, int length) |
264 |
{ |
265 |
if (sec_encrypt_use_count == 4096) |
266 |
{ |
267 |
sec_update(sec_encrypt_key, sec_encrypt_update_key); |
268 |
RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key); |
269 |
sec_encrypt_use_count = 0; |
270 |
} |
271 |
|
272 |
RC4(&rc4_encrypt_key, length, data, data); |
273 |
sec_encrypt_use_count++; |
274 |
} |
275 |
|
276 |
/* Decrypt data using RC4 */ |
277 |
void |
278 |
sec_decrypt(uint8 * data, int length) |
279 |
{ |
280 |
if (sec_decrypt_use_count == 4096) |
281 |
{ |
282 |
sec_update(sec_decrypt_key, sec_decrypt_update_key); |
283 |
RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key); |
284 |
sec_decrypt_use_count = 0; |
285 |
} |
286 |
|
287 |
RC4(&rc4_decrypt_key, length, data, data); |
288 |
sec_decrypt_use_count++; |
289 |
} |
290 |
|
291 |
static void |
292 |
reverse(uint8 * p, int len) |
293 |
{ |
294 |
int i, j; |
295 |
uint8 temp; |
296 |
|
297 |
for (i = 0, j = len - 1; i < j; i++, j--) |
298 |
{ |
299 |
temp = p[i]; |
300 |
p[i] = p[j]; |
301 |
p[j] = temp; |
302 |
} |
303 |
} |
304 |
|
305 |
/* Perform an RSA public key encryption operation */ |
306 |
static void |
307 |
sec_rsa_encrypt(uint8 * out, uint8 * in, int len, uint32 modulus_size, uint8 * modulus, |
308 |
uint8 * exponent) |
309 |
{ |
310 |
BN_CTX *ctx; |
311 |
BIGNUM mod, exp, x, y; |
312 |
uint8 inr[SEC_MAX_MODULUS_SIZE]; |
313 |
int outlen; |
314 |
|
315 |
reverse(modulus, modulus_size); |
316 |
reverse(exponent, SEC_EXPONENT_SIZE); |
317 |
memcpy(inr, in, len); |
318 |
reverse(inr, len); |
319 |
|
320 |
ctx = BN_CTX_new(); |
321 |
BN_init(&mod); |
322 |
BN_init(&exp); |
323 |
BN_init(&x); |
324 |
BN_init(&y); |
325 |
|
326 |
BN_bin2bn(modulus, modulus_size, &mod); |
327 |
BN_bin2bn(exponent, SEC_EXPONENT_SIZE, &exp); |
328 |
BN_bin2bn(inr, len, &x); |
329 |
BN_mod_exp(&y, &x, &exp, &mod, ctx); |
330 |
outlen = BN_bn2bin(&y, out); |
331 |
reverse(out, outlen); |
332 |
if (outlen < modulus_size) |
333 |
memset(out + outlen, 0, modulus_size - outlen); |
334 |
|
335 |
BN_free(&y); |
336 |
BN_clear_free(&x); |
337 |
BN_free(&exp); |
338 |
BN_free(&mod); |
339 |
BN_CTX_free(ctx); |
340 |
} |
341 |
|
342 |
/* Initialise secure transport packet */ |
343 |
STREAM |
344 |
sec_init(uint32 flags, int maxlen) |
345 |
{ |
346 |
int hdrlen; |
347 |
STREAM s; |
348 |
|
349 |
if (!g_licence_issued) |
350 |
hdrlen = (flags & SEC_ENCRYPT) ? 12 : 4; |
351 |
else |
352 |
hdrlen = (flags & SEC_ENCRYPT) ? 12 : 0; |
353 |
s = mcs_init(maxlen + hdrlen); |
354 |
s_push_layer(s, sec_hdr, hdrlen); |
355 |
|
356 |
return s; |
357 |
} |
358 |
|
359 |
/* Transmit secure transport packet over specified channel */ |
360 |
void |
361 |
sec_send_to_channel(STREAM s, uint32 flags, uint16 channel) |
362 |
{ |
363 |
int datalen; |
364 |
|
365 |
#ifdef WITH_SCARD |
366 |
scard_lock(SCARD_LOCK_SEC); |
367 |
#endif |
368 |
|
369 |
s_pop_layer(s, sec_hdr); |
370 |
if (!g_licence_issued || (flags & SEC_ENCRYPT)) |
371 |
out_uint32_le(s, flags); |
372 |
|
373 |
if (flags & SEC_ENCRYPT) |
374 |
{ |
375 |
flags &= ~SEC_ENCRYPT; |
376 |
datalen = s->end - s->p - 8; |
377 |
|
378 |
#if WITH_DEBUG |
379 |
DEBUG(("Sending encrypted packet:\n")); |
380 |
hexdump(s->p + 8, datalen); |
381 |
#endif |
382 |
|
383 |
sec_sign(s->p, 8, sec_sign_key, rc4_key_len, s->p + 8, datalen); |
384 |
sec_encrypt(s->p + 8, datalen); |
385 |
} |
386 |
|
387 |
mcs_send_to_channel(s, channel); |
388 |
|
389 |
#ifdef WITH_SCARD |
390 |
scard_unlock(SCARD_LOCK_SEC); |
391 |
#endif |
392 |
} |
393 |
|
394 |
/* Transmit secure transport packet */ |
395 |
|
396 |
void |
397 |
sec_send(STREAM s, uint32 flags) |
398 |
{ |
399 |
sec_send_to_channel(s, flags, MCS_GLOBAL_CHANNEL); |
400 |
} |
401 |
|
402 |
|
403 |
/* Transfer the client random to the server */ |
404 |
static void |
405 |
sec_establish_key(void) |
406 |
{ |
407 |
uint32 length = server_public_key_len + SEC_PADDING_SIZE; |
408 |
uint32 flags = SEC_CLIENT_RANDOM; |
409 |
STREAM s; |
410 |
|
411 |
s = sec_init(flags, length + 4); |
412 |
|
413 |
out_uint32_le(s, length); |
414 |
out_uint8p(s, sec_crypted_random, server_public_key_len); |
415 |
out_uint8s(s, SEC_PADDING_SIZE); |
416 |
|
417 |
s_mark_end(s); |
418 |
sec_send(s, flags); |
419 |
} |
420 |
|
421 |
/* Output connect initial data blob */ |
422 |
static void |
423 |
sec_out_mcs_data(STREAM s) |
424 |
{ |
425 |
int hostlen = 2 * strlen(g_hostname); |
426 |
int length = 158 + 76 + 12 + 4; |
427 |
unsigned int i; |
428 |
|
429 |
if (g_num_channels > 0) |
430 |
length += g_num_channels * 12 + 8; |
431 |
|
432 |
if (hostlen > 30) |
433 |
hostlen = 30; |
434 |
|
435 |
/* Generic Conference Control (T.124) ConferenceCreateRequest */ |
436 |
out_uint16_be(s, 5); |
437 |
out_uint16_be(s, 0x14); |
438 |
out_uint8(s, 0x7c); |
439 |
out_uint16_be(s, 1); |
440 |
|
441 |
out_uint16_be(s, (length | 0x8000)); /* remaining length */ |
442 |
|
443 |
out_uint16_be(s, 8); /* length? */ |
444 |
out_uint16_be(s, 16); |
445 |
out_uint8(s, 0); |
446 |
out_uint16_le(s, 0xc001); |
447 |
out_uint8(s, 0); |
448 |
|
449 |
out_uint32_le(s, 0x61637544); /* OEM ID: "Duca", as in Ducati. */ |
450 |
out_uint16_be(s, ((length - 14) | 0x8000)); /* remaining length */ |
451 |
|
452 |
/* Client information */ |
453 |
out_uint16_le(s, SEC_TAG_CLI_INFO); |
454 |
out_uint16_le(s, 212); /* length */ |
455 |
out_uint16_le(s, g_use_rdp5 ? 4 : 1); /* RDP version. 1 == RDP4, 4 == RDP5. */ |
456 |
out_uint16_le(s, 8); |
457 |
out_uint16_le(s, g_width); |
458 |
out_uint16_le(s, g_height); |
459 |
out_uint16_le(s, 0xca01); |
460 |
out_uint16_le(s, 0xaa03); |
461 |
out_uint32_le(s, g_keylayout); |
462 |
out_uint32_le(s, 2600); /* Client build. We are now 2600 compatible :-) */ |
463 |
|
464 |
/* Unicode name of client, padded to 32 bytes */ |
465 |
rdp_out_unistr(s, g_hostname, hostlen); |
466 |
out_uint8s(s, 30 - hostlen); |
467 |
|
468 |
/* See |
469 |
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wceddk40/html/cxtsksupportingremotedesktopprotocol.asp */ |
470 |
out_uint32_le(s, g_keyboard_type); |
471 |
out_uint32_le(s, g_keyboard_subtype); |
472 |
out_uint32_le(s, g_keyboard_functionkeys); |
473 |
out_uint8s(s, 64); /* reserved? 4 + 12 doublewords */ |
474 |
out_uint16_le(s, 0xca01); /* colour depth? */ |
475 |
out_uint16_le(s, 1); |
476 |
|
477 |
out_uint32(s, 0); |
478 |
out_uint8(s, g_server_depth); |
479 |
out_uint16_le(s, 0x0700); |
480 |
out_uint8(s, 0); |
481 |
out_uint32_le(s, 1); |
482 |
out_uint8s(s, 64); /* End of client info */ |
483 |
|
484 |
out_uint16_le(s, SEC_TAG_CLI_4); |
485 |
out_uint16_le(s, 12); |
486 |
out_uint32_le(s, g_console_session ? 0xb : 9); |
487 |
out_uint32(s, 0); |
488 |
|
489 |
/* Client encryption settings */ |
490 |
out_uint16_le(s, SEC_TAG_CLI_CRYPT); |
491 |
out_uint16_le(s, 12); /* length */ |
492 |
out_uint32_le(s, g_encryption ? 0x3 : 0); /* encryption supported, 128-bit supported */ |
493 |
out_uint32(s, 0); /* Unknown */ |
494 |
|
495 |
DEBUG_RDP5(("g_num_channels is %d\n", g_num_channels)); |
496 |
if (g_num_channels > 0) |
497 |
{ |
498 |
out_uint16_le(s, SEC_TAG_CLI_CHANNELS); |
499 |
out_uint16_le(s, g_num_channels * 12 + 8); /* length */ |
500 |
out_uint32_le(s, g_num_channels); /* number of virtual channels */ |
501 |
for (i = 0; i < g_num_channels; i++) |
502 |
{ |
503 |
DEBUG_RDP5(("Requesting channel %s\n", g_channels[i].name)); |
504 |
out_uint8a(s, g_channels[i].name, 8); |
505 |
out_uint32_be(s, g_channels[i].flags); |
506 |
} |
507 |
} |
508 |
|
509 |
s_mark_end(s); |
510 |
} |
511 |
|
512 |
/* Parse a public key structure */ |
513 |
static BOOL |
514 |
sec_parse_public_key(STREAM s, uint8 ** modulus, uint8 ** exponent) |
515 |
{ |
516 |
uint32 magic, modulus_len; |
517 |
|
518 |
in_uint32_le(s, magic); |
519 |
if (magic != SEC_RSA_MAGIC) |
520 |
{ |
521 |
error("RSA magic 0x%x\n", magic); |
522 |
return False; |
523 |
} |
524 |
|
525 |
in_uint32_le(s, modulus_len); |
526 |
modulus_len -= SEC_PADDING_SIZE; |
527 |
if ((modulus_len < 64) || (modulus_len > SEC_MAX_MODULUS_SIZE)) |
528 |
{ |
529 |
error("Bad server public key size (%u bits)\n", modulus_len * 8); |
530 |
return False; |
531 |
} |
532 |
|
533 |
in_uint8s(s, 8); /* modulus_bits, unknown */ |
534 |
in_uint8p(s, *exponent, SEC_EXPONENT_SIZE); |
535 |
in_uint8p(s, *modulus, modulus_len); |
536 |
in_uint8s(s, SEC_PADDING_SIZE); |
537 |
server_public_key_len = modulus_len; |
538 |
|
539 |
return s_check(s); |
540 |
} |
541 |
|
542 |
static BOOL |
543 |
sec_parse_x509_key(X509 * cert) |
544 |
{ |
545 |
EVP_PKEY *epk = NULL; |
546 |
/* By some reason, Microsoft sets the OID of the Public RSA key to |
547 |
the oid for "MD5 with RSA Encryption" instead of "RSA Encryption" |
548 |
|
549 |
Kudos to Richard Levitte for the following (. intiutive .) |
550 |
lines of code that resets the OID and let's us extract the key. */ |
551 |
if (OBJ_obj2nid(cert->cert_info->key->algor->algorithm) == NID_md5WithRSAEncryption) |
552 |
{ |
553 |
DEBUG_RDP5(("Re-setting algorithm type to RSA in server certificate\n")); |
554 |
ASN1_OBJECT_free(cert->cert_info->key->algor->algorithm); |
555 |
cert->cert_info->key->algor->algorithm = OBJ_nid2obj(NID_rsaEncryption); |
556 |
} |
557 |
epk = X509_get_pubkey(cert); |
558 |
if (NULL == epk) |
559 |
{ |
560 |
error("Failed to extract public key from certificate\n"); |
561 |
return False; |
562 |
} |
563 |
|
564 |
server_public_key = RSAPublicKey_dup((RSA *) epk->pkey.ptr); |
565 |
EVP_PKEY_free(epk); |
566 |
|
567 |
server_public_key_len = RSA_size(server_public_key); |
568 |
if ((server_public_key_len < 64) || (server_public_key_len > SEC_MAX_MODULUS_SIZE)) |
569 |
{ |
570 |
error("Bad server public key size (%u bits)\n", server_public_key_len * 8); |
571 |
return False; |
572 |
} |
573 |
|
574 |
return True; |
575 |
} |
576 |
|
577 |
|
578 |
/* Parse a crypto information structure */ |
579 |
static BOOL |
580 |
sec_parse_crypt_info(STREAM s, uint32 * rc4_key_size, |
581 |
uint8 ** server_random, uint8 ** modulus, uint8 ** exponent) |
582 |
{ |
583 |
uint32 crypt_level, random_len, rsa_info_len; |
584 |
uint32 cacert_len, cert_len, flags; |
585 |
X509 *cacert, *server_cert; |
586 |
uint16 tag, length; |
587 |
uint8 *next_tag, *end; |
588 |
|
589 |
in_uint32_le(s, *rc4_key_size); /* 1 = 40-bit, 2 = 128-bit */ |
590 |
in_uint32_le(s, crypt_level); /* 1 = low, 2 = medium, 3 = high */ |
591 |
if (crypt_level == 0) /* no encryption */ |
592 |
return False; |
593 |
in_uint32_le(s, random_len); |
594 |
in_uint32_le(s, rsa_info_len); |
595 |
|
596 |
if (random_len != SEC_RANDOM_SIZE) |
597 |
{ |
598 |
error("random len %d, expected %d\n", random_len, SEC_RANDOM_SIZE); |
599 |
return False; |
600 |
} |
601 |
|
602 |
in_uint8p(s, *server_random, random_len); |
603 |
|
604 |
/* RSA info */ |
605 |
end = s->p + rsa_info_len; |
606 |
if (end > s->end) |
607 |
return False; |
608 |
|
609 |
in_uint32_le(s, flags); /* 1 = RDP4-style, 0x80000002 = X.509 */ |
610 |
if (flags & 1) |
611 |
{ |
612 |
DEBUG_RDP5(("We're going for the RDP4-style encryption\n")); |
613 |
in_uint8s(s, 8); /* unknown */ |
614 |
|
615 |
while (s->p < end) |
616 |
{ |
617 |
in_uint16_le(s, tag); |
618 |
in_uint16_le(s, length); |
619 |
|
620 |
next_tag = s->p + length; |
621 |
|
622 |
switch (tag) |
623 |
{ |
624 |
case SEC_TAG_PUBKEY: |
625 |
if (!sec_parse_public_key(s, modulus, exponent)) |
626 |
return False; |
627 |
DEBUG_RDP5(("Got Public key, RDP4-style\n")); |
628 |
|
629 |
break; |
630 |
|
631 |
case SEC_TAG_KEYSIG: |
632 |
/* Is this a Microsoft key that we just got? */ |
633 |
/* Care factor: zero! */ |
634 |
/* Actually, it would probably be a good idea to check if the public key is signed with this key, and then store this |
635 |
key as a known key of the hostname. This would prevent some MITM-attacks. */ |
636 |
break; |
637 |
|
638 |
default: |
639 |
unimpl("crypt tag 0x%x\n", tag); |
640 |
} |
641 |
|
642 |
s->p = next_tag; |
643 |
} |
644 |
} |
645 |
else |
646 |
{ |
647 |
uint32 certcount; |
648 |
|
649 |
DEBUG_RDP5(("We're going for the RDP5-style encryption\n")); |
650 |
in_uint32_le(s, certcount); /* Number of certificates */ |
651 |
|
652 |
if (certcount < 2) |
653 |
{ |
654 |
error("Server didn't send enough X509 certificates\n"); |
655 |
return False; |
656 |
} |
657 |
|
658 |
for (; certcount > 2; certcount--) |
659 |
{ /* ignore all the certificates between the root and the signing CA */ |
660 |
uint32 ignorelen; |
661 |
X509 *ignorecert; |
662 |
|
663 |
DEBUG_RDP5(("Ignored certs left: %d\n", certcount)); |
664 |
|
665 |
in_uint32_le(s, ignorelen); |
666 |
DEBUG_RDP5(("Ignored Certificate length is %d\n", ignorelen)); |
667 |
ignorecert = |
668 |
d2i_X509(NULL, (D2I_X509_CONST unsigned char **) &(s->p), |
669 |
ignorelen); |
670 |
|
671 |
if (ignorecert == NULL) |
672 |
{ /* XXX: error out? */ |
673 |
DEBUG_RDP5(("got a bad cert: this will probably screw up the rest of the communication\n")); |
674 |
} |
675 |
|
676 |
#ifdef WITH_DEBUG_RDP5 |
677 |
DEBUG_RDP5(("cert #%d (ignored):\n", certcount)); |
678 |
X509_print_fp(stdout, ignorecert); |
679 |
#endif |
680 |
} |
681 |
|
682 |
/* Do da funky X.509 stuffy |
683 |
|
684 |
"How did I find out about this? I looked up and saw a |
685 |
bright light and when I came to I had a scar on my forehead |
686 |
and knew about X.500" |
687 |
- Peter Gutman in a early version of |
688 |
http://www.cs.auckland.ac.nz/~pgut001/pubs/x509guide.txt |
689 |
*/ |
690 |
|
691 |
in_uint32_le(s, cacert_len); |
692 |
DEBUG_RDP5(("CA Certificate length is %d\n", cacert_len)); |
693 |
cacert = d2i_X509(NULL, (D2I_X509_CONST unsigned char **) &(s->p), cacert_len); |
694 |
/* Note: We don't need to move s->p here - d2i_X509 is |
695 |
"kind" enough to do it for us */ |
696 |
if (NULL == cacert) |
697 |
{ |
698 |
error("Couldn't load CA Certificate from server\n"); |
699 |
return False; |
700 |
} |
701 |
|
702 |
/* Currently, we don't use the CA Certificate. |
703 |
FIXME: |
704 |
*) Verify the server certificate (server_cert) with the |
705 |
CA certificate. |
706 |
*) Store the CA Certificate with the hostname of the |
707 |
server we are connecting to as key, and compare it |
708 |
when we connect the next time, in order to prevent |
709 |
MITM-attacks. |
710 |
*/ |
711 |
|
712 |
X509_free(cacert); |
713 |
|
714 |
in_uint32_le(s, cert_len); |
715 |
DEBUG_RDP5(("Certificate length is %d\n", cert_len)); |
716 |
server_cert = d2i_X509(NULL, (D2I_X509_CONST unsigned char **) &(s->p), cert_len); |
717 |
if (NULL == server_cert) |
718 |
{ |
719 |
error("Couldn't load Certificate from server\n"); |
720 |
return False; |
721 |
} |
722 |
|
723 |
in_uint8s(s, 16); /* Padding */ |
724 |
|
725 |
/* Note: Verifying the server certificate must be done here, |
726 |
before sec_parse_public_key since we'll have to apply |
727 |
serious violence to the key after this */ |
728 |
|
729 |
if (!sec_parse_x509_key(server_cert)) |
730 |
{ |
731 |
DEBUG_RDP5(("Didn't parse X509 correctly\n")); |
732 |
X509_free(server_cert); |
733 |
return False; |
734 |
} |
735 |
X509_free(server_cert); |
736 |
return True; /* There's some garbage here we don't care about */ |
737 |
} |
738 |
return s_check_end(s); |
739 |
} |
740 |
|
741 |
/* Process crypto information blob */ |
742 |
static void |
743 |
sec_process_crypt_info(STREAM s) |
744 |
{ |
745 |
uint8 *server_random = NULL, *modulus = NULL, *exponent = NULL; |
746 |
uint8 client_random[SEC_RANDOM_SIZE]; |
747 |
uint32 rc4_key_size; |
748 |
|
749 |
if (!sec_parse_crypt_info(s, &rc4_key_size, &server_random, &modulus, &exponent)) |
750 |
{ |
751 |
DEBUG(("Failed to parse crypt info\n")); |
752 |
return; |
753 |
} |
754 |
|
755 |
DEBUG(("Generating client random\n")); |
756 |
generate_random(client_random); |
757 |
|
758 |
if (NULL != server_public_key) |
759 |
{ /* Which means we should use |
760 |
RDP5-style encryption */ |
761 |
uint8 inr[SEC_MAX_MODULUS_SIZE]; |
762 |
uint32 padding_len = server_public_key_len - SEC_RANDOM_SIZE; |
763 |
|
764 |
/* This is what the MS client do: */ |
765 |
memset(inr, 0, padding_len); |
766 |
/* *ARIGL!* Plaintext attack, anyone? |
767 |
I tried doing: |
768 |
generate_random(inr); |
769 |
..but that generates connection errors now and then (yes, |
770 |
"now and then". Something like 0 to 3 attempts needed before a |
771 |
successful connection. Nice. Not! |
772 |
*/ |
773 |
memcpy(inr + padding_len, client_random, SEC_RANDOM_SIZE); |
774 |
reverse(inr + padding_len, SEC_RANDOM_SIZE); |
775 |
|
776 |
RSA_public_encrypt(server_public_key_len, |
777 |
inr, sec_crypted_random, server_public_key, RSA_NO_PADDING); |
778 |
|
779 |
reverse(sec_crypted_random, server_public_key_len); |
780 |
|
781 |
RSA_free(server_public_key); |
782 |
server_public_key = NULL; |
783 |
} |
784 |
else |
785 |
{ /* RDP4-style encryption */ |
786 |
sec_rsa_encrypt(sec_crypted_random, |
787 |
client_random, SEC_RANDOM_SIZE, server_public_key_len, modulus, |
788 |
exponent); |
789 |
} |
790 |
sec_generate_keys(client_random, server_random, rc4_key_size); |
791 |
} |
792 |
|
793 |
|
794 |
/* Process SRV_INFO, find RDP version supported by server */ |
795 |
static void |
796 |
sec_process_srv_info(STREAM s) |
797 |
{ |
798 |
in_uint16_le(s, g_server_rdp_version); |
799 |
DEBUG_RDP5(("Server RDP version is %d\n", g_server_rdp_version)); |
800 |
if (1 == g_server_rdp_version) |
801 |
{ |
802 |
g_use_rdp5 = 0; |
803 |
g_server_depth = 8; |
804 |
} |
805 |
} |
806 |
|
807 |
|
808 |
/* Process connect response data blob */ |
809 |
void |
810 |
sec_process_mcs_data(STREAM s) |
811 |
{ |
812 |
uint16 tag, length; |
813 |
uint8 *next_tag; |
814 |
uint8 len; |
815 |
|
816 |
in_uint8s(s, 21); /* header (T.124 ConferenceCreateResponse) */ |
817 |
in_uint8(s, len); |
818 |
if (len & 0x80) |
819 |
in_uint8(s, len); |
820 |
|
821 |
while (s->p < s->end) |
822 |
{ |
823 |
in_uint16_le(s, tag); |
824 |
in_uint16_le(s, length); |
825 |
|
826 |
if (length <= 4) |
827 |
return; |
828 |
|
829 |
next_tag = s->p + length - 4; |
830 |
|
831 |
switch (tag) |
832 |
{ |
833 |
case SEC_TAG_SRV_INFO: |
834 |
sec_process_srv_info(s); |
835 |
break; |
836 |
|
837 |
case SEC_TAG_SRV_CRYPT: |
838 |
sec_process_crypt_info(s); |
839 |
break; |
840 |
|
841 |
case SEC_TAG_SRV_CHANNELS: |
842 |
/* FIXME: We should parse this information and |
843 |
use it to map RDP5 channels to MCS |
844 |
channels */ |
845 |
break; |
846 |
|
847 |
default: |
848 |
unimpl("response tag 0x%x\n", tag); |
849 |
} |
850 |
|
851 |
s->p = next_tag; |
852 |
} |
853 |
} |
854 |
|
855 |
/* Receive secure transport packet */ |
856 |
STREAM |
857 |
sec_recv(uint8 * rdpver) |
858 |
{ |
859 |
uint32 sec_flags; |
860 |
uint16 channel; |
861 |
STREAM s; |
862 |
|
863 |
while ((s = mcs_recv(&channel, rdpver)) != NULL) |
864 |
{ |
865 |
if (rdpver != NULL) |
866 |
{ |
867 |
if (*rdpver != 3) |
868 |
{ |
869 |
if (*rdpver & 0x80) |
870 |
{ |
871 |
in_uint8s(s, 8); /* signature */ |
872 |
sec_decrypt(s->p, s->end - s->p); |
873 |
} |
874 |
return s; |
875 |
} |
876 |
} |
877 |
if (g_encryption || !g_licence_issued) |
878 |
{ |
879 |
in_uint32_le(s, sec_flags); |
880 |
|
881 |
if (sec_flags & SEC_ENCRYPT) |
882 |
{ |
883 |
in_uint8s(s, 8); /* signature */ |
884 |
sec_decrypt(s->p, s->end - s->p); |
885 |
} |
886 |
|
887 |
if (sec_flags & SEC_LICENCE_NEG) |
888 |
{ |
889 |
licence_process(s); |
890 |
continue; |
891 |
} |
892 |
|
893 |
if (sec_flags & 0x0400) /* SEC_REDIRECT_ENCRYPT */ |
894 |
{ |
895 |
uint8 swapbyte; |
896 |
|
897 |
in_uint8s(s, 8); /* signature */ |
898 |
sec_decrypt(s->p, s->end - s->p); |
899 |
|
900 |
/* Check for a redirect packet, starts with 00 04 */ |
901 |
if (s->p[0] == 0 && s->p[1] == 4) |
902 |
{ |
903 |
/* for some reason the PDU and the length seem to be swapped. |
904 |
This isn't good, but we're going to do a byte for byte |
905 |
swap. So the first foure value appear as: 00 04 XX YY, |
906 |
where XX YY is the little endian length. We're going to |
907 |
use 04 00 as the PDU type, so after our swap this will look |
908 |
like: XX YY 04 00 */ |
909 |
swapbyte = s->p[0]; |
910 |
s->p[0] = s->p[2]; |
911 |
s->p[2] = swapbyte; |
912 |
|
913 |
swapbyte = s->p[1]; |
914 |
s->p[1] = s->p[3]; |
915 |
s->p[3] = swapbyte; |
916 |
|
917 |
swapbyte = s->p[2]; |
918 |
s->p[2] = s->p[3]; |
919 |
s->p[3] = swapbyte; |
920 |
} |
921 |
#ifdef WITH_DEBUG |
922 |
/* warning! this debug statement will show passwords in the clear! */ |
923 |
hexdump(s->p, s->end - s->p); |
924 |
#endif |
925 |
} |
926 |
|
927 |
} |
928 |
|
929 |
if (channel != MCS_GLOBAL_CHANNEL) |
930 |
{ |
931 |
channel_process(s, channel); |
932 |
*rdpver = 0xff; |
933 |
return s; |
934 |
} |
935 |
|
936 |
return s; |
937 |
} |
938 |
|
939 |
return NULL; |
940 |
} |
941 |
|
942 |
/* Establish a secure connection */ |
943 |
BOOL |
944 |
sec_connect(char *server, char *username) |
945 |
{ |
946 |
struct stream mcs_data; |
947 |
|
948 |
/* We exchange some RDP data during the MCS-Connect */ |
949 |
mcs_data.size = 512; |
950 |
mcs_data.p = mcs_data.data = (uint8 *) xmalloc(mcs_data.size); |
951 |
sec_out_mcs_data(&mcs_data); |
952 |
|
953 |
if (!mcs_connect(server, &mcs_data, username)) |
954 |
return False; |
955 |
|
956 |
/* sec_process_mcs_data(&mcs_data); */ |
957 |
if (g_encryption) |
958 |
sec_establish_key(); |
959 |
xfree(mcs_data.data); |
960 |
return True; |
961 |
} |
962 |
|
963 |
/* Establish a secure connection */ |
964 |
BOOL |
965 |
sec_reconnect(char *server) |
966 |
{ |
967 |
struct stream mcs_data; |
968 |
|
969 |
/* We exchange some RDP data during the MCS-Connect */ |
970 |
mcs_data.size = 512; |
971 |
mcs_data.p = mcs_data.data = (uint8 *) xmalloc(mcs_data.size); |
972 |
sec_out_mcs_data(&mcs_data); |
973 |
|
974 |
if (!mcs_reconnect(server, &mcs_data)) |
975 |
return False; |
976 |
|
977 |
/* sec_process_mcs_data(&mcs_data); */ |
978 |
if (g_encryption) |
979 |
sec_establish_key(); |
980 |
xfree(mcs_data.data); |
981 |
return True; |
982 |
} |
983 |
|
984 |
/* Disconnect a connection */ |
985 |
void |
986 |
sec_disconnect(void) |
987 |
{ |
988 |
mcs_disconnect(); |
989 |
} |
990 |
|
991 |
/* reset the state of the sec layer */ |
992 |
void |
993 |
sec_reset_state(void) |
994 |
{ |
995 |
g_server_rdp_version = 0; |
996 |
sec_encrypt_use_count = 0; |
997 |
sec_decrypt_use_count = 0; |
998 |
mcs_reset_state(); |
999 |
} |