/* -*- c-basic-offset: 8 -*- rdesktop: A Remote Desktop Protocol client. Protocol services - RDP encryption and licensing Copyright (C) Matthew Chapman 1999-2008 Copyright 2005-2011 Peter Astrand for Cendio AB Copyright 2017-2018 Henrik Andersson for Cendio AB This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . */ #include "rdesktop.h" #include "ssl.h" extern char g_hostname[16]; extern uint32 g_requested_session_width; extern uint32 g_requested_session_height; extern int g_dpi; extern unsigned int g_keylayout; extern int g_keyboard_type; extern int g_keyboard_subtype; extern int g_keyboard_functionkeys; extern RD_BOOL g_encryption; extern RD_BOOL g_licence_issued; extern RD_BOOL g_licence_error_result; extern RDP_VERSION g_rdp_version; extern RD_BOOL g_console_session; extern uint32 g_redirect_session_id; extern int g_server_depth; extern VCHANNEL g_channels[]; extern unsigned int g_num_channels; extern uint8 g_client_random[SEC_RANDOM_SIZE]; static int g_rc4_key_len; static RDSSL_RC4 g_rc4_decrypt_key; static RDSSL_RC4 g_rc4_encrypt_key; static uint32 g_server_public_key_len; static uint8 g_sec_sign_key[16]; static uint8 g_sec_decrypt_key[16]; static uint8 g_sec_encrypt_key[16]; static uint8 g_sec_decrypt_update_key[16]; static uint8 g_sec_encrypt_update_key[16]; static uint8 g_sec_crypted_random[SEC_MAX_MODULUS_SIZE]; uint16 g_server_rdp_version = 0; /* These values must be available to reset state - Session Directory */ static int g_sec_encrypt_use_count = 0; static int g_sec_decrypt_use_count = 0; /* * I believe this is based on SSLv3 with the following differences: * MAC algorithm (5.2.3.1) uses only 32-bit length in place of seq_num/type/length fields * MAC algorithm uses SHA1 and MD5 for the two hash functions instead of one or other * key_block algorithm (6.2.2) uses 'X', 'YY', 'ZZZ' instead of 'A', 'BB', 'CCC' * key_block partitioning is different (16 bytes each: MAC secret, decrypt key, encrypt key) * encryption/decryption keys updated every 4096 packets * See http://wp.netscape.com/eng/ssl3/draft302.txt */ /* * 48-byte transformation used to generate master secret (6.1) and key material (6.2.2). * Both SHA1 and MD5 algorithms are used. */ void sec_hash_48(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2, uint8 salt) { uint8 shasig[20]; uint8 pad[4]; RDSSL_SHA1 sha1; RDSSL_MD5 md5; int i; for (i = 0; i < 3; i++) { memset(pad, salt + i, i + 1); rdssl_sha1_init(&sha1); rdssl_sha1_update(&sha1, pad, i + 1); rdssl_sha1_update(&sha1, in, 48); rdssl_sha1_update(&sha1, salt1, 32); rdssl_sha1_update(&sha1, salt2, 32); rdssl_sha1_final(&sha1, shasig); rdssl_md5_init(&md5); rdssl_md5_update(&md5, in, 48); rdssl_md5_update(&md5, shasig, 20); rdssl_md5_final(&md5, &out[i * 16]); } } /* * 16-byte transformation used to generate export keys (6.2.2). */ void sec_hash_16(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2) { RDSSL_MD5 md5; rdssl_md5_init(&md5); rdssl_md5_update(&md5, in, 16); rdssl_md5_update(&md5, salt1, 32); rdssl_md5_update(&md5, salt2, 32); rdssl_md5_final(&md5, out); } /* * 16-byte sha1 hash */ void sec_hash_sha1_16(uint8 * out, uint8 * in, uint8 * salt1) { RDSSL_SHA1 sha1; rdssl_sha1_init(&sha1); rdssl_sha1_update(&sha1, in, 16); rdssl_sha1_update(&sha1, salt1, 16); rdssl_sha1_final(&sha1, out); } /* create string from hash */ void sec_hash_to_string(char *out, int out_size, uint8 * in, int in_size) { int k; memset(out, 0, out_size); for (k = 0; k < in_size; k++, out += 2) { sprintf(out, "%.2x", in[k]); } } /* Reduce key entropy from 64 to 40 bits */ static void sec_make_40bit(uint8 * key) { key[0] = 0xd1; key[1] = 0x26; key[2] = 0x9e; } /* Generate encryption keys given client and server randoms */ static void sec_generate_keys(uint8 * client_random, uint8 * server_random, int rc4_key_size) { uint8 pre_master_secret[48]; uint8 master_secret[48]; uint8 key_block[48]; /* Construct pre-master secret */ memcpy(pre_master_secret, client_random, 24); memcpy(pre_master_secret + 24, server_random, 24); /* Generate master secret and then key material */ sec_hash_48(master_secret, pre_master_secret, client_random, server_random, 'A'); sec_hash_48(key_block, master_secret, client_random, server_random, 'X'); /* First 16 bytes of key material is MAC secret */ memcpy(g_sec_sign_key, key_block, 16); /* Generate export keys from next two blocks of 16 bytes */ sec_hash_16(g_sec_decrypt_key, &key_block[16], client_random, server_random); sec_hash_16(g_sec_encrypt_key, &key_block[32], client_random, server_random); if (rc4_key_size == 1) { logger(Protocol, Debug, "sec_generate_keys(), 40-bit encryption enabled"); sec_make_40bit(g_sec_sign_key); sec_make_40bit(g_sec_decrypt_key); sec_make_40bit(g_sec_encrypt_key); g_rc4_key_len = 8; } else { logger(Protocol, Debug, "sec_generate_key(), rc_4_key_size == %d, 128-bit encryption enabled", rc4_key_size); g_rc4_key_len = 16; } /* Save initial RC4 keys as update keys */ memcpy(g_sec_decrypt_update_key, g_sec_decrypt_key, 16); memcpy(g_sec_encrypt_update_key, g_sec_encrypt_key, 16); /* Initialise RC4 state arrays */ rdssl_rc4_set_key(&g_rc4_decrypt_key, g_sec_decrypt_key, g_rc4_key_len); rdssl_rc4_set_key(&g_rc4_encrypt_key, g_sec_encrypt_key, g_rc4_key_len); } static uint8 pad_54[40] = { 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54 }; static uint8 pad_92[48] = { 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92 }; /* Output a uint32 into a buffer (little-endian) */ void buf_out_uint32(uint8 * buffer, uint32 value) { buffer[0] = (value) & 0xff; buffer[1] = (value >> 8) & 0xff; buffer[2] = (value >> 16) & 0xff; buffer[3] = (value >> 24) & 0xff; } /* Generate a MAC hash (5.2.3.1), using a combination of SHA1 and MD5 */ void sec_sign(uint8 * signature, int siglen, uint8 * session_key, int keylen, uint8 * data, int datalen) { uint8 shasig[20]; uint8 md5sig[16]; uint8 lenhdr[4]; RDSSL_SHA1 sha1; RDSSL_MD5 md5; buf_out_uint32(lenhdr, datalen); rdssl_sha1_init(&sha1); rdssl_sha1_update(&sha1, session_key, keylen); rdssl_sha1_update(&sha1, pad_54, 40); rdssl_sha1_update(&sha1, lenhdr, 4); rdssl_sha1_update(&sha1, data, datalen); rdssl_sha1_final(&sha1, shasig); rdssl_md5_init(&md5); rdssl_md5_update(&md5, session_key, keylen); rdssl_md5_update(&md5, pad_92, 48); rdssl_md5_update(&md5, shasig, 20); rdssl_md5_final(&md5, md5sig); memcpy(signature, md5sig, siglen); } /* Update an encryption key */ static void sec_update(uint8 * key, uint8 * update_key) { uint8 shasig[20]; RDSSL_SHA1 sha1; RDSSL_MD5 md5; RDSSL_RC4 update; rdssl_sha1_init(&sha1); rdssl_sha1_update(&sha1, update_key, g_rc4_key_len); rdssl_sha1_update(&sha1, pad_54, 40); rdssl_sha1_update(&sha1, key, g_rc4_key_len); rdssl_sha1_final(&sha1, shasig); rdssl_md5_init(&md5); rdssl_md5_update(&md5, update_key, g_rc4_key_len); rdssl_md5_update(&md5, pad_92, 48); rdssl_md5_update(&md5, shasig, 20); rdssl_md5_final(&md5, key); rdssl_rc4_set_key(&update, key, g_rc4_key_len); rdssl_rc4_crypt(&update, key, key, g_rc4_key_len); if (g_rc4_key_len == 8) sec_make_40bit(key); } /* Encrypt data using RC4 */ static void sec_encrypt(uint8 * data, int length) { if (g_sec_encrypt_use_count == 4096) { sec_update(g_sec_encrypt_key, g_sec_encrypt_update_key); rdssl_rc4_set_key(&g_rc4_encrypt_key, g_sec_encrypt_key, g_rc4_key_len); g_sec_encrypt_use_count = 0; } rdssl_rc4_crypt(&g_rc4_encrypt_key, data, data, length); g_sec_encrypt_use_count++; } /* Decrypt data using RC4 */ void sec_decrypt(uint8 * data, int length) { if (length <= 0) return; if (g_sec_decrypt_use_count == 4096) { sec_update(g_sec_decrypt_key, g_sec_decrypt_update_key); rdssl_rc4_set_key(&g_rc4_decrypt_key, g_sec_decrypt_key, g_rc4_key_len); g_sec_decrypt_use_count = 0; } rdssl_rc4_crypt(&g_rc4_decrypt_key, data, data, length); g_sec_decrypt_use_count++; } /* Perform an RSA public key encryption operation */ static void sec_rsa_encrypt(uint8 * out, uint8 * in, int len, uint32 modulus_size, uint8 * modulus, uint8 * exponent) { rdssl_rsa_encrypt(out, in, len, modulus_size, modulus, exponent); } /* Initialise secure transport packet */ STREAM sec_init(uint32 flags, int maxlen) { int hdrlen; STREAM s; if (!g_licence_issued && !g_licence_error_result) hdrlen = (flags & SEC_ENCRYPT) ? 12 : 4; else hdrlen = (flags & SEC_ENCRYPT) ? 12 : 0; s = mcs_init(maxlen + hdrlen); s_push_layer(s, sec_hdr, hdrlen); return s; } /* Transmit secure transport packet over specified channel */ void sec_send_to_channel(STREAM s, uint32 flags, uint16 channel) { int datalen; #ifdef WITH_SCARD scard_lock(SCARD_LOCK_SEC); #endif s_pop_layer(s, sec_hdr); if ((!g_licence_issued && !g_licence_error_result) || (flags & SEC_ENCRYPT)) out_uint32_le(s, flags); if (flags & SEC_ENCRYPT) { unsigned char *data; flags &= ~SEC_ENCRYPT; datalen = s_remaining(s) - 8; inout_uint8p(s, data, datalen + 8); sec_sign(data, 8, g_sec_sign_key, g_rc4_key_len, data + 8, datalen); sec_encrypt(data + 8, datalen); } mcs_send_to_channel(s, channel); #ifdef WITH_SCARD scard_unlock(SCARD_LOCK_SEC); #endif } /* Transmit secure transport packet */ void sec_send(STREAM s, uint32 flags) { sec_send_to_channel(s, flags, MCS_GLOBAL_CHANNEL); } /* Transfer the client random to the server */ static void sec_establish_key(void) { uint32 length = g_server_public_key_len + SEC_PADDING_SIZE; uint32 flags = SEC_EXCHANGE_PKT; STREAM s; s = sec_init(flags, length + 4); out_uint32_le(s, length); out_uint8a(s, g_sec_crypted_random, g_server_public_key_len); out_uint8s(s, SEC_PADDING_SIZE); s_mark_end(s); sec_send(s, flags); s_free(s); } /* Output connect initial data blob */ static void sec_out_mcs_connect_initial_pdu(STREAM s, uint32 selected_protocol) { int length = 162 + 76 + 12 + 4 + (g_dpi > 0 ? 18 : 0); unsigned int i; uint32 rdpversion = RDP_40; uint16 capflags = RNS_UD_CS_SUPPORT_ERRINFO_PDU; uint16 colorsupport = RNS_UD_24BPP_SUPPORT | RNS_UD_16BPP_SUPPORT | RNS_UD_32BPP_SUPPORT; uint32 physwidth, physheight, desktopscale, devicescale; logger(Protocol, Debug, "%s()", __func__); if (g_rdp_version >= RDP_V5) rdpversion = RDP_50; if (g_num_channels > 0) length += g_num_channels * 12 + 8; /* Generic Conference Control (T.124) ConferenceCreateRequest */ out_uint16_be(s, 5); out_uint16_be(s, 0x14); out_uint8(s, 0x7c); out_uint16_be(s, 1); out_uint16_be(s, (length | 0x8000)); /* remaining length */ out_uint16_be(s, 8); /* length? */ out_uint16_be(s, 16); out_uint8(s, 0); out_uint16_le(s, 0xc001); out_uint8(s, 0); out_uint32_le(s, 0x61637544); /* OEM ID: "Duca", as in Ducati. */ out_uint16_be(s, ((length - 14) | 0x8000)); /* remaining length */ /* Client information (TS_UD_CS_CORE) */ out_uint16_le(s, CS_CORE); /* type */ out_uint16_le(s, 216 + (g_dpi > 0 ? 18 : 0)); /* length */ out_uint32_le(s, rdpversion); /* version */ out_uint16_le(s, g_requested_session_width); /* desktopWidth */ out_uint16_le(s, g_requested_session_height); /* desktopHeight */ out_uint16_le(s, RNS_UD_COLOR_8BPP); /* colorDepth */ out_uint16_le(s, RNS_UD_SAS_DEL); /* SASSequence */ out_uint32_le(s, g_keylayout); /* keyboardLayout */ /* * According to s.1.7 of MS-RDPESC if the build number is at least 4,304, * SCREDIR_VERSION_LONGHORN is assumed; otherwise SCREDIR_VERSIONXP is to be used */ out_uint32_le(s, 2600); /* Client build. We are now 2600 compatible :-) */ /* Unicode name of client, padded to 32 bytes */ out_utf16s_padded(s, g_hostname, 32, 0x00); out_uint32_le(s, g_keyboard_type); /* keyboardType */ out_uint32_le(s, g_keyboard_subtype); /* keyboardSubtype */ out_uint32_le(s, g_keyboard_functionkeys); /* keyboardFunctionKey */ out_uint8s(s, 64); /* imeFileName */ out_uint16_le(s, RNS_UD_COLOR_8BPP); /* postBeta2ColorDepth (overrides colorDepth) */ out_uint16_le(s, 1); /* clientProductId (should be 1) */ out_uint32_le(s, 0); /* serialNumber (should be 0) */ /* highColorDepth (overrides postBeta2ColorDepth). Capped at 24BPP. To get 32BPP sessions, we need to set a capability flag. */ out_uint16_le(s, MIN(g_server_depth, 24)); if (g_server_depth == 32) capflags |= RNS_UD_CS_WANT_32BPP_SESSION; out_uint16_le(s, colorsupport); /* supportedColorDepths */ out_uint16_le(s, capflags); /* earlyCapabilityFlags */ out_uint8s(s, 64); /* clientDigProductId */ out_uint8(s, 0); /* connectionType */ out_uint8(s, 0); /* pad */ out_uint32_le(s, selected_protocol); /* serverSelectedProtocol */ if (g_dpi > 0) { /* Extended client info describing monitor geometry */ utils_calculate_dpi_scale_factors(g_requested_session_width, g_requested_session_height, g_dpi, &physwidth, &physheight, &desktopscale, &devicescale); out_uint32_le(s, physwidth); /* physicalwidth */ out_uint32_le(s, physheight); /* physicalheight */ out_uint16_le(s, ORIENTATION_LANDSCAPE); /* Orientation */ out_uint32_le(s, desktopscale); /* DesktopScaleFactor */ out_uint32_le(s, devicescale); /* DeviceScaleFactor */ } /* Write a Client Cluster Data (TS_UD_CS_CLUSTER) */ uint32 cluster_flags = 0; out_uint16_le(s, CS_CLUSTER); /* header.type */ out_uint16_le(s, 12); /* length */ cluster_flags |= SEC_CC_REDIRECTION_SUPPORTED; cluster_flags |= (SEC_CC_REDIRECT_VERSION_4 << 2); if (g_console_session || g_redirect_session_id != 0) cluster_flags |= SEC_CC_REDIRECT_SESSIONID_FIELD_VALID; out_uint32_le(s, cluster_flags); out_uint32(s, g_redirect_session_id); /* Client encryption settings (TS_UD_CS_SEC) */ out_uint16_le(s, CS_SECURITY); /* type */ out_uint16_le(s, 12); /* length */ out_uint32_le(s, g_encryption ? 0x3 : 0); /* encryptionMethods */ out_uint32(s, 0); /* extEncryptionMethods */ /* Channel definitions (TS_UD_CS_NET) */ logger(Protocol, Debug, "sec_out_mcs_data(), g_num_channels is %d", g_num_channels); if (g_num_channels > 0) { out_uint16_le(s, CS_NET); /* type */ out_uint16_le(s, g_num_channels * 12 + 8); /* length */ out_uint32_le(s, g_num_channels); /* number of virtual channels */ for (i = 0; i < g_num_channels; i++) { logger(Protocol, Debug, "sec_out_mcs_data(), requesting channel %s", g_channels[i].name); out_uint8a(s, g_channels[i].name, 8); out_uint32_be(s, g_channels[i].flags); } } s_mark_end(s); } /* Parse a public key structure */ static RD_BOOL sec_parse_public_key(STREAM s, uint8 * modulus, uint8 * exponent) { uint32 magic, modulus_len; if (!s_check_rem(s, 8)) { return False; } in_uint32_le(s, magic); if (magic != SEC_RSA_MAGIC) { logger(Protocol, Error, "sec_parse_public_key(), magic (0x%x) != SEC_RSA_MAGIC", magic); return False; } in_uint32_le(s, modulus_len); modulus_len -= SEC_PADDING_SIZE; if ((modulus_len < SEC_MODULUS_SIZE) || (modulus_len > SEC_MAX_MODULUS_SIZE)) { logger(Protocol, Error, "sec_parse_public_key(), invalid public key size (%u bits) from server", modulus_len * 8); return False; } if (!s_check_rem(s, 1 + SEC_EXPONENT_SIZE + modulus_len + SEC_PADDING_SIZE)) { return False; } in_uint8s(s, 8); /* modulus_bits, unknown */ in_uint8a(s, exponent, SEC_EXPONENT_SIZE); in_uint8a(s, modulus, modulus_len); in_uint8s(s, SEC_PADDING_SIZE); g_server_public_key_len = modulus_len; return True; } /* Parse a public signature structure */ static RD_BOOL sec_parse_public_sig(STREAM s, uint32 len, uint8 * modulus, uint8 * exponent) { uint8 signature[SEC_MAX_MODULUS_SIZE]; uint32 sig_len; if (len != 72) { return True; } memset(signature, 0, sizeof(signature)); sig_len = len - 8; in_uint8a(s, signature, sig_len); return rdssl_sig_ok(exponent, SEC_EXPONENT_SIZE, modulus, g_server_public_key_len, signature, sig_len); } /* Parse a crypto information structure */ static RD_BOOL sec_parse_crypt_info(STREAM s, uint32 * rc4_key_size, uint8 ** server_random, uint8 * modulus, uint8 * exponent) { uint32 crypt_level, random_len, rsa_info_len; uint32 cacert_len, cert_len, flags; RDSSL_CERT *cacert, *server_cert; RDSSL_RKEY *server_public_key; uint16 tag, length; size_t next_tag; logger(Protocol, Debug, "%s()", __func__); in_uint32_le(s, *rc4_key_size); /* 1 = 40-bit, 2 = 128-bit */ in_uint32_le(s, crypt_level); /* 1 = low, 2 = medium, 3 = high */ if (crypt_level == 0) { /* no encryption */ logger(Protocol, Debug, "sec_parse_crypt_info(), got ENCRYPTION_LEVEL_NONE"); return False; } in_uint32_le(s, random_len); in_uint32_le(s, rsa_info_len); if (random_len != SEC_RANDOM_SIZE) { logger(Protocol, Error, "sec_parse_crypt_info(), got random len %d, expected %d", random_len, SEC_RANDOM_SIZE); return False; } in_uint8p(s, *server_random, random_len); /* RSA info */ if (!s_check_rem(s, rsa_info_len)) { logger(Protocol, Error, "sec_parse_crypt_info(), !s_check_rem(s, rsa_info_len)"); return False; } in_uint32_le(s, flags); /* 1 = RDP4-style, 0x80000002 = X.509 */ if (flags & 1) { logger(Protocol, Debug, "sec_parse_crypt_info(), We're going for the RDP4-style encryption"); in_uint8s(s, 8); /* unknown */ while (!s_check_end(s)) { in_uint16_le(s, tag); in_uint16_le(s, length); next_tag = s_tell(s) + length; switch (tag) { case SEC_TAG_PUBKEY: if (!sec_parse_public_key(s, modulus, exponent)) { logger(Protocol, Error, "sec_parse_crypt_info(), invalid public key"); return False; } logger(Protocol, Debug, "sec_parse_crypt_info(), got public key"); break; case SEC_TAG_KEYSIG: if (!sec_parse_public_sig(s, length, modulus, exponent)) { logger(Protocol, Error, "sec_parse_crypt_info(), invalid public sig"); return False; } break; default: logger(Protocol, Warning, "sec_parse_crypt_info(), unhandled crypt tag 0x%x", tag); } s_seek(s, next_tag); } } else { uint32 certcount; unsigned char *certdata; logger(Protocol, Debug, "sec_parse_crypt_info(), We're going for the RDP5-style encryption"); in_uint32_le(s, certcount); /* Number of certificates */ if (certcount < 2) { logger(Protocol, Error, "sec_parse_crypt_info(), server didn't send enough x509 certificates"); return False; } for (; certcount > 2; certcount--) { /* ignore all the certificates between the root and the signing CA */ uint32 ignorelen; RDSSL_CERT *ignorecert; unsigned char *ignoredata; in_uint32_le(s, ignorelen); in_uint8p(s, ignoredata, ignorelen); ignorecert = rdssl_cert_read(ignoredata, ignorelen); if (ignorecert == NULL) { /* XXX: error out? */ logger(Protocol, Error, "sec_parse_crypt_info(), got a bad cert: this will probably screw up the rest of the communication"); } else { rdssl_cert_free(ignorecert); } } /* Do da funky X.509 stuffy "How did I find out about this? I looked up and saw a bright light and when I came to I had a scar on my forehead and knew about X.500" - Peter Gutman in a early version of http://www.cs.auckland.ac.nz/~pgut001/pubs/x509guide.txt */ in_uint32_le(s, cacert_len); in_uint8p(s, certdata, cacert_len); logger(Protocol, Debug, "sec_parse_crypt_info(), server CA Certificate length is %d", cacert_len); cacert = rdssl_cert_read(certdata, cacert_len); if (NULL == cacert) { logger(Protocol, Error, "sec_parse_crypt_info(), couldn't load CA Certificate from server"); return False; } in_uint32_le(s, cert_len); in_uint8p(s, certdata, cert_len); logger(Protocol, Debug, "sec_parse_crypt_info(), certificate length is %d", cert_len); server_cert = rdssl_cert_read(certdata, cert_len); if (NULL == server_cert) { rdssl_cert_free(cacert); logger(Protocol, Error, "sec_parse_crypt_info(), couldn't load Certificate from server"); return False; } if (!rdssl_certs_ok(server_cert, cacert)) { rdssl_cert_free(server_cert); rdssl_cert_free(cacert); logger(Protocol, Error, "sec_parse_crypt_info(), security error, CA Certificate invalid"); return False; } rdssl_cert_free(cacert); in_uint8s(s, 16); /* Padding */ server_public_key = rdssl_cert_to_rkey(server_cert, &g_server_public_key_len); if (NULL == server_public_key) { logger(Protocol, Debug, "sec_parse_crypt_info(). failed to parse X509 correctly"); rdssl_cert_free(server_cert); return False; } rdssl_cert_free(server_cert); if ((g_server_public_key_len < SEC_MODULUS_SIZE) || (g_server_public_key_len > SEC_MAX_MODULUS_SIZE)) { logger(Protocol, Error, "sec_parse_crypt_info(), bad server public key size (%u bits)", g_server_public_key_len * 8); rdssl_rkey_free(server_public_key); return False; } if (rdssl_rkey_get_exp_mod(server_public_key, exponent, SEC_EXPONENT_SIZE, modulus, SEC_MAX_MODULUS_SIZE) != 0) { logger(Protocol, Error, "sec_parse_crypt_info(), problem extracting RSA exponent, modulus"); rdssl_rkey_free(server_public_key); return False; } rdssl_rkey_free(server_public_key); return True; /* There's some garbage here we don't care about */ } return s_check_end(s); } /* Process crypto information blob */ static void sec_process_crypt_info(STREAM s) { uint8 *server_random = NULL; uint8 modulus[SEC_MAX_MODULUS_SIZE]; uint8 exponent[SEC_EXPONENT_SIZE]; uint32 rc4_key_size; logger(Protocol, Debug, "%s()", __func__); memset(modulus, 0, sizeof(modulus)); memset(exponent, 0, sizeof(exponent)); if (!sec_parse_crypt_info(s, &rc4_key_size, &server_random, modulus, exponent)) return; logger(Protocol, Debug, "sec_parse_crypt_info(), generating client random"); generate_random(g_client_random); sec_rsa_encrypt(g_sec_crypted_random, g_client_random, SEC_RANDOM_SIZE, g_server_public_key_len, modulus, exponent); sec_generate_keys(g_client_random, server_random, rc4_key_size); } /* Process SRV_INFO, find RDP version supported by server */ static void sec_process_srv_info(STREAM s) { in_uint16_le(s, g_server_rdp_version); logger(Protocol, Debug, "sec_process_srv_info(), server RDP version is %d", g_server_rdp_version); if (1 == g_server_rdp_version) { g_rdp_version = RDP_V4; g_server_depth = 8; } } /* Process connect response data blob */ void sec_process_mcs_data(STREAM s) { uint16 tag, length; size_t next_tag; uint8 len; in_uint8s(s, 21); /* header (T.124 ConferenceCreateResponse) */ in_uint8(s, len); if (len & 0x80) in_uint8(s, len); logger(Protocol, Debug, "%s()", __func__); while (!s_check_end(s)) { in_uint16_le(s, tag); in_uint16_le(s, length); if (length <= 4) return; next_tag = s_tell(s) + length - 4; switch (tag) { case SEC_TAG_SRV_INFO: logger(Protocol, Debug, "%s(), SEC_TAG_SRV_INFO", __func__); sec_process_srv_info(s); break; case SEC_TAG_SRV_CRYPT: logger(Protocol, Debug, "%s(), SEC_TAG_SRV_CRYPT", __func__); sec_process_crypt_info(s); break; case SEC_TAG_SRV_CHANNELS: logger(Protocol, Debug, "%s(), SEC_TAG_SRV_CHANNELS", __func__); /* FIXME: We should parse this information and use it to map RDP5 channels to MCS channels */ break; default: logger(Protocol, Warning, "Unhandled response tag 0x%x", tag); } s_seek(s, next_tag); } } /* Receive secure transport packet */ STREAM sec_recv(RD_BOOL * is_fastpath) { uint8 fastpath_hdr, fastpath_flags; uint16 sec_flags; uint16 channel; STREAM s; struct stream packet; size_t data_offset; size_t remaining; unsigned char *data; while ((s = mcs_recv(&channel, is_fastpath, &fastpath_hdr)) != NULL) { packet = *s; if (*is_fastpath == True) { /* If fastpath packet is encrypted, read data signature and decrypt */ /* FIXME: extracting flags from hdr could be made less obscure */ fastpath_flags = (fastpath_hdr & 0xC0) >> 6; if (fastpath_flags & FASTPATH_OUTPUT_ENCRYPTED) { if (!s_check_rem(s, 8)) { rdp_protocol_error("consume fastpath signature from stream would overrun", &packet); } in_uint8s(s, 8); /* signature */ data_offset = s_tell(s); remaining = s_remaining(s); inout_uint8p(s, data, remaining); sec_decrypt(data, remaining); s_seek(s, data_offset); } return s; } if (g_encryption || (!g_licence_issued && !g_licence_error_result)) { data_offset = s_tell(s); /* TS_SECURITY_HEADER */ in_uint16_le(s, sec_flags); in_uint8s(s, 2); /* skip sec_flags_hi */ if (g_encryption) { data_offset = s_tell(s); if (sec_flags & SEC_ENCRYPT) { if (!s_check_rem(s, 8)) { rdp_protocol_error("consume encrypt signature from stream would overrun", &packet); } in_uint8s(s, 8); /* signature */ data_offset = s_tell(s); remaining = s_remaining(s); inout_uint8p(s, data, remaining); sec_decrypt(data, remaining); } if (sec_flags & SEC_LICENSE_PKT) { s_seek(s, data_offset); licence_process(s); continue; } if (sec_flags & SEC_REDIRECTION_PKT) { uint8 swapbyte; if (!s_check_rem(s, 8)) { rdp_protocol_error("consume redirect signature from stream would overrun", &packet); } in_uint8s(s, 8); /* signature */ data_offset = s_tell(s); remaining = s_remaining(s); inout_uint8p(s, data, remaining); sec_decrypt(data, remaining); /* Check for a redirect packet, starts with 00 04 */ if (data[0] == 0 && data[1] == 4) { /* for some reason the PDU and the length seem to be swapped. This isn't good, but we're going to do a byte for byte swap. So the first four value appear as: 00 04 XX YY, where XX YY is the little endian length. We're going to use 04 00 as the PDU type, so after our swap this will look like: XX YY 04 00 */ swapbyte = data[0]; data[0] = data[2]; data[2] = swapbyte; swapbyte = data[1]; data[1] = data[3]; data[3] = swapbyte; swapbyte = data[2]; data[2] = data[3]; data[3] = swapbyte; } } } else { if (sec_flags & SEC_LICENSE_PKT) { licence_process(s); continue; } } s_seek(s, data_offset); } if (channel != MCS_GLOBAL_CHANNEL) { channel_process(s, channel); continue; } return s; } return NULL; } /* Establish a secure connection */ RD_BOOL sec_connect(char *server, char *username, char *domain, char *password, RD_BOOL reconnect) { uint32 selected_proto; STREAM mcs_data; /* Start a MCS connect sequence */ if (!mcs_connect_start(server, username, domain, password, reconnect, &selected_proto)) return False; /* We exchange some RDP data during the MCS-Connect */ mcs_data = s_alloc(512); sec_out_mcs_connect_initial_pdu(mcs_data, selected_proto); /* finalize the MCS connect sequence */ if (!mcs_connect_finalize(mcs_data)) return False; /* sec_process_mcs_data(&mcs_data); */ if (g_encryption) sec_establish_key(); s_free(mcs_data); return True; } /* Disconnect a connection */ void sec_disconnect(void) { /* Perform a User-initiated disconnect sequence, see [MS-RDPBCGR] 1.3.1.4 Disconnect Sequences */ mcs_disconnect(RN_USER_REQUESTED); } /* reset the state of the sec layer */ void sec_reset_state(void) { g_server_rdp_version = 0; g_sec_encrypt_use_count = 0; g_sec_decrypt_use_count = 0; g_licence_issued = 0; g_licence_error_result = 0; mcs_reset_state(); }