--- sourceforge.net/trunk/rdesktop/secure.c 2002/09/26 14:26:46 207 +++ sourceforge.net/trunk/rdesktop/secure.c 2003/05/19 21:36:33 376 @@ -1,4 +1,4 @@ -/* +/* -*- c-basic-offset: 8 -*- rdesktop: A Remote Desktop Protocol client. Protocol services - RDP encryption and licensing Copyright (C) Matthew Chapman 1999-2002 @@ -25,6 +25,7 @@ #include #include #include +#include #else #include "crypto/rc4.h" #include "crypto/md5.h" @@ -38,10 +39,13 @@ extern int keylayout; extern BOOL encryption; extern BOOL licence_issued; +extern BOOL use_rdp5; +extern int server_bpp; static int rc4_key_len; static RC4_KEY rc4_decrypt_key; static RC4_KEY rc4_encrypt_key; +static RSA *server_public_key; static uint8 sec_sign_key[16]; static uint8 sec_decrypt_key[16]; @@ -50,6 +54,8 @@ static uint8 sec_encrypt_update_key[16]; static uint8 sec_crypted_random[SEC_MODULUS_SIZE]; +uint16 server_rdp_version = 0; + /* * General purpose 48-byte transformation, using two 32-byte salts (generally, * a client and server salt) and a global salt value used for padding. @@ -140,7 +146,7 @@ } else { - DEBUG(("128-bit encryption enabled\n")); + DEBUG(("rc_4_key_size == %d, 128-bit encryption enabled\n", rc4_key_size)); rc4_key_len = 16; } @@ -251,7 +257,7 @@ } /* Decrypt data using RC4 */ -static void +void sec_decrypt(uint8 * data, int length) { static int use_count; @@ -285,7 +291,7 @@ static void sec_rsa_encrypt(uint8 * out, uint8 * in, int len, uint8 * modulus, uint8 * exponent) { - BN_CTX ctx; + BN_CTX *ctx; BIGNUM mod, exp, x, y; uint8 inr[SEC_MODULUS_SIZE]; int outlen; @@ -295,7 +301,7 @@ memcpy(inr, in, len); reverse(inr, len); - BN_CTX_init(&ctx); + ctx = BN_CTX_new(); BN_init(&mod); BN_init(&exp); BN_init(&x); @@ -304,7 +310,7 @@ BN_bin2bn(modulus, SEC_MODULUS_SIZE, &mod); BN_bin2bn(exponent, SEC_EXPONENT_SIZE, &exp); BN_bin2bn(inr, len, &x); - BN_mod_exp(&y, &x, &exp, &mod, &ctx); + BN_mod_exp(&y, &x, &exp, &mod, ctx); outlen = BN_bn2bin(&y, out); reverse(out, outlen); if (outlen < SEC_MODULUS_SIZE) @@ -314,7 +320,7 @@ BN_clear_free(&x); BN_free(&exp); BN_free(&mod); - BN_CTX_free(&ctx); + BN_CTX_free(ctx); } /* Initialise secure transport packet */ @@ -384,6 +390,7 @@ sec_out_mcs_data(STREAM s) { int hostlen = 2 * strlen(hostname); + int length = 158 + 76 + 12 + 4 + 20; if (hostlen > 30) hostlen = 30; @@ -393,7 +400,7 @@ out_uint8(s, 0x7c); out_uint16_be(s, 1); - out_uint16_be(s, (158 | 0x8000)); /* remaining length */ + out_uint16_be(s, (length | 0x8000)); /* remaining length */ out_uint16_be(s, 8); /* length? */ out_uint16_be(s, 16); @@ -402,19 +409,19 @@ out_uint8(s, 0); out_uint32_le(s, 0x61637544); /* "Duca" ?! */ - out_uint16_be(s, (144 | 0x8000)); /* remaining length */ + out_uint16_be(s, ((length - 14) | 0x8000)); /* remaining length */ /* Client information */ out_uint16_le(s, SEC_TAG_CLI_INFO); - out_uint16_le(s, 136); /* length */ - out_uint16_le(s, 1); + out_uint16_le(s, 212); /* length */ + out_uint16_le(s, use_rdp5 ? 4 : 1); /* RDP version. 1 == RDP4, 4 == RDP5. */ out_uint16_le(s, 8); out_uint16_le(s, width); out_uint16_le(s, height); out_uint16_le(s, 0xca01); out_uint16_le(s, 0xaa03); out_uint32_le(s, keylayout); - out_uint32_le(s, 419); /* client build? we are 419 compatible :-) */ + out_uint32_le(s, 2600); /* Client build. We are now 2600 compatible :-) */ /* Unicode name of client, padded to 32 bytes */ rdp_out_unistr(s, hostname, hostlen); @@ -425,13 +432,48 @@ out_uint32_le(s, 12); out_uint8s(s, 64); /* reserved? 4 + 12 doublewords */ - out_uint16_le(s, 0xca01); - out_uint16(s, 0); + switch (server_bpp) + { + case 8: + out_uint16_le(s, 0xca01); + break; + case 15: + out_uint16_le(s, 0xca02); + break; + case 16: + out_uint16_le(s, 0xca03); + break; + case 24: + out_uint16_le(s, 0xca04); + break; + } + out_uint16_le(s, 1); + + out_uint32(s, 0); + out_uint8(s, server_bpp); + out_uint16_le(s, 0x0700); + out_uint8(s, 0); + out_uint32_le(s, 1); + out_uint8s(s, 64); /* End of client info */ + + out_uint16_le(s, SEC_TAG_CLI_4); + out_uint16_le(s, 12); + out_uint32_le(s, 9); + out_uint32(s, 0); /* Client encryption settings */ out_uint16_le(s, SEC_TAG_CLI_CRYPT); - out_uint16_le(s, 8); /* length */ + out_uint16_le(s, 12); /* length */ out_uint32_le(s, encryption ? 0x3 : 0); /* encryption supported, 128-bit supported */ + out_uint32(s, 0); /* Unknown */ + + out_uint16_le(s, SEC_TAG_CLI_CHANNELS); + out_uint16_le(s, 20); /* length */ + out_uint32_le(s, 1); /* number of virtual channels */ + out_uint8p(s, "cliprdr", 8); /* name padded to 8(?) */ + out_uint16(s, 0); + out_uint16_le(s, 0xc0a0); /* Flags. Rumours tell this is documented in MSDN. */ + s_mark_end(s); } @@ -463,25 +505,54 @@ return s_check(s); } +static BOOL +sec_parse_x509_key(X509 * cert) +{ + EVP_PKEY *epk = NULL; + /* By some reason, Microsoft sets the OID of the Public RSA key to + the oid for "MD5 with RSA Encryption" instead of "RSA Encryption" + + Kudos to Richard Levitte for the following (. intiutive .) + lines of code that resets the OID and let's us extract the key. */ + if (OBJ_obj2nid(cert->cert_info->key->algor->algorithm) == NID_md5WithRSAEncryption) + { + DEBUG_RDP5(("Re-setting algorithm type to RSA in server certificate\n")); + cert->cert_info->key->algor->algorithm = OBJ_nid2obj(NID_rsaEncryption); + } + epk = X509_get_pubkey(cert); + if (NULL == epk) + { + error("Failed to extract public key from certificate\n"); + return False; + } + + server_public_key = (RSA *) epk->pkey.ptr; + + return True; +} + + /* Parse a crypto information structure */ static 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; + X509 *cacert, *server_cert; uint16 tag, length; uint8 *next_tag, *end; 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 encryptation */ + if (crypt_level == 0) /* no encryption */ return False; in_uint32_le(s, random_len); in_uint32_le(s, rsa_info_len); if (random_len != SEC_RANDOM_SIZE) { - error("random len %d\n", random_len); + error("random len %d, expected %d\n", random_len, SEC_RANDOM_SIZE); return False; } @@ -492,35 +563,97 @@ if (end > s->end) return False; - in_uint8s(s, 12); /* unknown */ + in_uint32_le(s, flags); /* 1 = RDP4-style, 0x80000002 = X.509 */ + if (flags & 1) + { + DEBUG_RDP5(("We're going for the RDP4-style encryption\n")); + in_uint8s(s, 8); /* unknown */ + + while (s->p < end) + { + in_uint16_le(s, tag); + in_uint16_le(s, length); + + next_tag = s->p + length; + + switch (tag) + { + case SEC_TAG_PUBKEY: + if (!sec_parse_public_key(s, modulus, exponent)) + return False; + DEBUG_RDP5(("Got Public key, RDP4-style\n")); + + break; + + case SEC_TAG_KEYSIG: + /* Is this a Microsoft key that we just got? */ + /* Care factor: zero! */ + /* Actually, it would probably be a good idea to check if the public key is signed with this key, and then store this + key as a known key of the hostname. This would prevent some MITM-attacks. */ + break; + + default: + unimpl("crypt tag 0x%x\n", tag); + } - while (s->p < end) + s->p = next_tag; + } + } + else { - in_uint16_le(s, tag); - in_uint16_le(s, length); + DEBUG_RDP5(("We're going for the RDP5-style encryption\n")); + in_uint8s(s, 4); /* Number of certificates */ - next_tag = s->p + length; + /* Do da funky X.509 stuffy - switch (tag) + "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); + cacert = d2i_X509(NULL, &(s->p), cacert_len); + /* Note: We don't need to move s->p here - d2i_X509 is + "kind" enough to do it for us */ + if (NULL == cacert) { - case SEC_TAG_PUBKEY: - if (!sec_parse_public_key(s, modulus, exponent)) - return False; + error("Couldn't load CA Certificate from server\n"); + return False; + } - break; + /* Currently, we don't use the CA Certificate. + FIXME: + *) Verify the server certificate (server_cert) with the + CA certificate. + *) Store the CA Certificate with the hostname of the + server we are connecting to as key, and compare it + when we connect the next time, in order to prevent + MITM-attacks. + */ + + in_uint32_le(s, cert_len); + server_cert = d2i_X509(NULL, &(s->p), cert_len); + if (NULL == server_cert) + { + error("Couldn't load Certificate from server\n"); + return False; + } - case SEC_TAG_KEYSIG: - /* Is this a Microsoft key that we just got? */ - /* Care factor: zero! */ - break; + in_uint8s(s, 16); /* Padding */ - default: - unimpl("crypt tag 0x%x\n", tag); - } + /* Note: Verifying the server certificate must be done here, + before sec_parse_public_key since we'll have to apply + serious violence to the key after this */ - s->p = next_tag; + if (!sec_parse_x509_key(server_cert)) + { + DEBUG_RDP5(("Didn't parse X509 correctly\n")); + return False; + } + return True; /* There's some garbage here we don't care about */ } - return s_check_end(s); } @@ -531,25 +664,61 @@ uint8 *server_random, *modulus, *exponent; uint8 client_random[SEC_RANDOM_SIZE]; uint32 rc4_key_size; + uint8 inr[SEC_MODULUS_SIZE]; if (!sec_parse_crypt_info(s, &rc4_key_size, &server_random, &modulus, &exponent)) + { + DEBUG(("Failed to parse crypt info\n")); return; + } + DEBUG(("Generating client random\n")); /* Generate a client random, and hence determine encryption keys */ + generate_random(inr); + // This is what the MS client do: + // memset(inr, 0, SEC_RANDOM_SIZE); + // *ARIGL!* generate_random(client_random); - sec_rsa_encrypt(sec_crypted_random, client_random, SEC_RANDOM_SIZE, modulus, exponent); + if (NULL != server_public_key) + { /* Which means we should use + RDP5-style encryption */ + + memcpy(inr + SEC_RANDOM_SIZE, client_random, SEC_RANDOM_SIZE); + reverse(inr + SEC_RANDOM_SIZE, SEC_RANDOM_SIZE); + + RSA_public_encrypt(SEC_MODULUS_SIZE, + inr, sec_crypted_random, server_public_key, RSA_NO_PADDING); + + reverse(sec_crypted_random, SEC_MODULUS_SIZE); + + } + else + { /* RDP4-style encryption */ + sec_rsa_encrypt(sec_crypted_random, + client_random, SEC_RANDOM_SIZE, modulus, exponent); + } sec_generate_keys(client_random, server_random, rc4_key_size); } -/* Process connect response data blob */ + +/* Process SRV_INFO, find RDP version supported by server */ static void +sec_process_srv_info(STREAM s) +{ + in_uint16_le(s, server_rdp_version); + DEBUG_RDP5(("Server RDP version is %d\n", server_rdp_version)); +} + + +/* Process connect response data blob */ +void sec_process_mcs_data(STREAM s) { uint16 tag, length; uint8 *next_tag; uint8 len; - in_uint8s(s, 21); /* header */ + in_uint8s(s, 21); /* header (T.124 stuff, probably) */ in_uint8(s, len); if (len & 0x80) in_uint8(s, len); @@ -567,6 +736,9 @@ switch (tag) { case SEC_TAG_SRV_INFO: + sec_process_srv_info(s); + break; + case SEC_TAG_SRV_3: break; @@ -587,9 +759,10 @@ sec_recv(void) { uint32 sec_flags; + uint16 channel; STREAM s; - while ((s = mcs_recv()) != NULL) + while ((s = mcs_recv(&channel)) != NULL) { if (encryption || !licence_issued) { @@ -597,6 +770,9 @@ if (sec_flags & SEC_LICENCE_NEG) { + if (sec_flags & SEC_ENCRYPT) { + DEBUG_RDP5(("Encrypted license detected\n")); + } licence_process(s); continue; } @@ -608,7 +784,13 @@ } } - return s; + if (MCS_GLOBAL_CHANNEL == channel) + { + return s; + } + else + rdp5_process_channel(s, channel); + } return NULL; @@ -616,21 +798,22 @@ /* Establish a secure connection */ BOOL -sec_connect(char *server) +sec_connect(char *server, char *username) { struct stream mcs_data; /* We exchange some RDP data during the MCS-Connect */ mcs_data.size = 512; - mcs_data.p = mcs_data.data = xmalloc(mcs_data.size); + mcs_data.p = mcs_data.data = (uint8*)xmalloc(mcs_data.size); sec_out_mcs_data(&mcs_data); - if (!mcs_connect(server, &mcs_data)) + if (!mcs_connect(server, &mcs_data, username)) return False; - sec_process_mcs_data(&mcs_data); + // sec_process_mcs_data(&mcs_data); if (encryption) sec_establish_key(); + xfree(mcs_data.data); return True; }