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xrdp/rdp/rdp_sec.c
Jay Sorg c6fa03102f copyright year update
2013-06-08 10:51:53 -07:00

714 lines
20 KiB
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/**
* xrdp: A Remote Desktop Protocol server.
*
* Copyright (C) Jay Sorg 2004-2013
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* librdp secure layer
*/
#include "rdp.h"
static char g_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 char g_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
};
/*****************************************************************************/
struct rdp_sec *APP_CC
rdp_sec_create(struct rdp_rdp *owner)
{
struct rdp_sec *self;
self = (struct rdp_sec *)g_malloc(sizeof(struct rdp_sec), 1);
self->rdp_layer = owner;
make_stream(self->client_mcs_data);
init_stream(self->client_mcs_data, 8192);
make_stream(self->server_mcs_data);
init_stream(self->server_mcs_data, 8192);
self->mcs_layer = rdp_mcs_create(self, self->client_mcs_data,
self->server_mcs_data);
if (self->decrypt_rc4_info != NULL)
{
g_writeln("rdp_sec_create - decrypt_rc4_info already created !!!");
}
self->decrypt_rc4_info = ssl_rc4_info_create();
if (self->encrypt_rc4_info != NULL)
{
g_writeln("rdp_sec_create - encrypt_rc4_info already created !!!");
}
self->encrypt_rc4_info = ssl_rc4_info_create();
self->lic_layer = rdp_lic_create(self);
return self;
}
/*****************************************************************************/
void APP_CC
rdp_sec_delete(struct rdp_sec *self)
{
if (self == 0)
{
return;
}
rdp_lic_delete(self->lic_layer);
rdp_mcs_delete(self->mcs_layer);
free_stream(self->client_mcs_data);
free_stream(self->server_mcs_data);
ssl_rc4_info_delete(self->decrypt_rc4_info);
ssl_rc4_info_delete(self->encrypt_rc4_info);
g_free(self);
}
/*****************************************************************************/
/* Reduce key entropy from 64 to 40 bits */
static void APP_CC
rdp_sec_make_40bit(char *key)
{
key[0] = 0xd1;
key[1] = 0x26;
key[2] = 0x9e;
}
/*****************************************************************************/
/* returns error */
/* update an encryption key */
static int APP_CC
rdp_sec_update(char *key, char *update_key, int key_len)
{
char shasig[20];
void *sha1_info;
void *md5_info;
void *rc4_info;
sha1_info = ssl_sha1_info_create();
md5_info = ssl_md5_info_create();
rc4_info = ssl_rc4_info_create();
ssl_sha1_clear(sha1_info);
ssl_sha1_transform(sha1_info, update_key, key_len);
ssl_sha1_transform(sha1_info, g_pad_54, 40);
ssl_sha1_transform(sha1_info, key, key_len);
ssl_sha1_complete(sha1_info, shasig);
ssl_md5_clear(md5_info);
ssl_md5_transform(md5_info, update_key, key_len);
ssl_md5_transform(md5_info, g_pad_92, 48);
ssl_md5_transform(md5_info, shasig, 20);
ssl_md5_complete(md5_info, key);
ssl_rc4_set_key(rc4_info, key, key_len);
ssl_rc4_crypt(rc4_info, key, key_len);
if (key_len == 8)
{
rdp_sec_make_40bit(key);
}
ssl_sha1_info_delete(sha1_info);
ssl_md5_info_delete(md5_info);
ssl_rc4_info_delete(rc4_info);
return 0;
}
/*****************************************************************************/
static void APP_CC
rdp_sec_decrypt(struct rdp_sec *self, char *data, int len)
{
if (self->decrypt_use_count == 4096)
{
rdp_sec_update(self->decrypt_key, self->decrypt_update_key,
self->rc4_key_len);
ssl_rc4_set_key(self->decrypt_rc4_info, self->decrypt_key,
self->rc4_key_len);
self->decrypt_use_count = 0;
}
ssl_rc4_crypt(self->decrypt_rc4_info, data, len);
self->decrypt_use_count++;
}
/*****************************************************************************/
/* returns error */
int APP_CC
rdp_sec_recv(struct rdp_sec *self, struct stream *s, int *chan)
{
int flags;
DEBUG((" in rdp_sec_recv"));
if (rdp_mcs_recv(self->mcs_layer, s, chan) != 0)
{
DEBUG((" error in rdp_sec_recv, rdp_mcs_recv failed"));
return 1;
}
in_uint32_le(s, flags);
DEBUG((" rdp_sec_recv flags %8.8x", flags));
if (flags & SEC_ENCRYPT) /* 0x08 */
{
in_uint8s(s, 8); /* signature */
rdp_sec_decrypt(self, s->p, s->end - s->p);
}
if (flags & SEC_LICENCE_NEG) /* 0x80 */
{
DEBUG((" in rdp_sec_recv, got SEC_LICENCE_NEG"));
rdp_lic_process(self->lic_layer, s);
*chan = 0;
}
DEBUG((" out rdp_sec_recv"));
return 0;
}
/*****************************************************************************/
/* prepare client mcs data to send in mcs layer */
static void APP_CC
rdp_sec_out_mcs_data(struct rdp_sec *self)
{
struct stream *s;
int hostlen;
int length;
s = self->client_mcs_data;
init_stream(s, 512);
self->rdp_layer->mod->hostname[15] = 0; /* limit length to 15 */
hostlen = 2 * g_strlen(self->rdp_layer->mod->hostname);
length = 158 + 76 + 12 + 4;
/* 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 */
out_uint16_le(s, SEC_TAG_CLI_INFO);
out_uint16_le(s, 212); /* length */
out_uint16_le(s, 1); /* RDP version. 1 == RDP4, 4 == RDP5. */
out_uint16_le(s, 8);
out_uint16_le(s, self->rdp_layer->mod->width);
out_uint16_le(s, self->rdp_layer->mod->height);
out_uint16_le(s, 0xca01);
out_uint16_le(s, 0xaa03);
out_uint32_le(s, self->rdp_layer->mod->keylayout);
out_uint32_le(s, 2600); /* Client build */
/* Unicode name of client, padded to 32 bytes */
rdp_rdp_out_unistr(s, self->rdp_layer->mod->hostname);
out_uint8s(s, 30 - hostlen);
out_uint32_le(s, 4);
out_uint32_le(s, 0);
out_uint32_le(s, 12);
out_uint8s(s, 64); /* reserved? 4 + 12 doublewords */
out_uint16_le(s, 0xca01); /* color depth? */
out_uint16_le(s, 1);
out_uint32_le(s, 0);
out_uint8(s, self->rdp_layer->mod->rdp_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_le(s, 0);
/* Client encryption settings */
out_uint16_le(s, SEC_TAG_CLI_CRYPT);
out_uint16_le(s, 12); /* length */
/* encryption supported, 128-bit supported */
out_uint32_le(s, 0x3);
out_uint32_le(s, 0); /* Unknown */
s_mark_end(s);
}
/*****************************************************************************/
/* Parse a public key structure */
/* returns boolean */
static int APP_CC
rdp_sec_parse_public_key(struct rdp_sec *self, struct stream *s,
char *modulus, char *exponent)
{
int magic;
int modulus_len;
in_uint32_le(s, magic);
if (magic != SEC_RSA_MAGIC)
{
return 0;
}
in_uint32_le(s, modulus_len);
if (modulus_len != SEC_MODULUS_SIZE + SEC_PADDING_SIZE)
{
return 0;
}
in_uint8s(s, 8);
in_uint8a(s, exponent, SEC_EXPONENT_SIZE);
in_uint8a(s, modulus, SEC_MODULUS_SIZE);
in_uint8s(s, SEC_PADDING_SIZE);
return s_check(s);
}
/*****************************************************************************/
/* Parse a crypto information structure */
/* returns boolean */
static int APP_CC
rdp_sec_parse_crypt_info(struct rdp_sec *self, struct stream *s,
char *modulus, char *exponent)
{
int random_len;
int rsa_info_len;
int flags;
int tag;
int length;
char *next_tag;
char *end;
in_uint32_le(s, self->rc4_key_size); /* 1 = 40-bit, 2 = 128-bit */
in_uint32_le(s, self->crypt_level); /* 1 = low, 2 = medium, 3 = high */
if (self->crypt_level == 0) /* no encryption */
{
return 0;
}
in_uint32_le(s, random_len);
in_uint32_le(s, rsa_info_len);
if (random_len != SEC_RANDOM_SIZE)
{
return 0;
}
in_uint8a(s, self->server_random, random_len);
/* RSA info */
end = s->p + rsa_info_len;
if (end > s->end)
{
return 0;
}
in_uint32_le(s, flags); /* 1 = RDP4-style, 0x80000002 = X.509 */
if (flags & 1)
{
in_uint8s(s, 8); /* unknown */
while (s->p < end)
{
in_uint16_le(s, tag);
in_uint16_le(s, length);
next_tag = s->p + length;
DEBUG((" rdp_sec_parse_crypt_info tag %d length %d", tag, length));
switch (tag)
{
case SEC_TAG_PUBKEY:
if (!rdp_sec_parse_public_key(self, s, modulus, exponent))
{
return 0;
}
break;
case SEC_TAG_KEYSIG:
break;
default:
break;
}
s->p = next_tag;
}
}
else
{
/* todo */
return 0;
}
return s_check_end(s);
}
/*****************************************************************************/
static void APP_CC
rdp_sec_rsa_op(char *out, char *in, char *mod, char *exp)
{
ssl_mod_exp(out, SEC_MODULUS_SIZE, /* 64 */
in, SEC_RANDOM_SIZE, /* 32 */
mod, SEC_MODULUS_SIZE, /* 64 */
exp, SEC_EXPONENT_SIZE); /* 4 */
}
/*****************************************************************************/
void APP_CC
rdp_sec_hash_48(char *out, char *in, char *salt1, char *salt2, int salt)
{
int i;
void *sha1_info;
void *md5_info;
char pad[4];
char sha1_sig[20];
char md5_sig[16];
sha1_info = ssl_sha1_info_create();
md5_info = ssl_md5_info_create();
for (i = 0; i < 3; i++)
{
g_memset(pad, salt + i, 4);
ssl_sha1_clear(sha1_info);
ssl_sha1_transform(sha1_info, pad, i + 1);
ssl_sha1_transform(sha1_info, in, 48);
ssl_sha1_transform(sha1_info, salt1, 32);
ssl_sha1_transform(sha1_info, salt2, 32);
ssl_sha1_complete(sha1_info, sha1_sig);
ssl_md5_clear(md5_info);
ssl_md5_transform(md5_info, in, 48);
ssl_md5_transform(md5_info, sha1_sig, 20);
ssl_md5_complete(md5_info, md5_sig);
g_memcpy(out + i * 16, md5_sig, 16);
}
ssl_sha1_info_delete(sha1_info);
ssl_md5_info_delete(md5_info);
}
/*****************************************************************************/
void APP_CC
rdp_sec_hash_16(char *out, char *in, char *salt1, char *salt2)
{
void *md5_info;
md5_info = ssl_md5_info_create();
ssl_md5_clear(md5_info);
ssl_md5_transform(md5_info, in, 16);
ssl_md5_transform(md5_info, salt1, 32);
ssl_md5_transform(md5_info, salt2, 32);
ssl_md5_complete(md5_info, out);
ssl_md5_info_delete(md5_info);
}
/*****************************************************************************/
static int APP_CC
rdp_sec_generate_keys(struct rdp_sec *self)
{
char session_key[48];
char temp_hash[48];
char input[48];
g_memcpy(input, self->client_random, 24);
g_memcpy(input + 24, self->server_random, 24);
rdp_sec_hash_48(temp_hash, input, self->client_random,
self->server_random, 65);
rdp_sec_hash_48(session_key, temp_hash, self->client_random,
self->server_random, 88);
g_memcpy(self->sign_key, session_key, 16);
rdp_sec_hash_16(self->decrypt_key, session_key + 16, self->client_random,
self->server_random);
rdp_sec_hash_16(self->encrypt_key, session_key + 32, self->client_random,
self->server_random);
DEBUG((" rdp_sec_generate_keys, rc4_key_size is %d", self->rc4_key_size));
DEBUG((" rdp_sec_generate_keys, crypt_level is %d", self->crypt_level));
if (self->rc4_key_size == 1)
{
rdp_sec_make_40bit(self->sign_key);
rdp_sec_make_40bit(self->encrypt_key);
rdp_sec_make_40bit(self->decrypt_key);
self->rc4_key_len = 8;
}
else
{
self->rc4_key_len = 16;
}
g_memcpy(self->decrypt_update_key, self->decrypt_key, 16);
g_memcpy(self->encrypt_update_key, self->encrypt_key, 16);
ssl_rc4_set_key(self->decrypt_rc4_info, self->decrypt_key, self->rc4_key_len);
ssl_rc4_set_key(self->encrypt_rc4_info, self->encrypt_key, self->rc4_key_len);
return 0;
}
/*****************************************************************************/
/* Process crypto information blob */
static void APP_CC
rdp_sec_process_crypt_info(struct rdp_sec *self, struct stream *s)
{
char modulus[64];
char exponent[64];
g_memset(modulus, 0, sizeof(modulus));
g_memset(exponent, 0, sizeof(exponent));
if (!rdp_sec_parse_crypt_info(self, s, modulus, exponent))
{
DEBUG((" error in rdp_sec_process_crypt_info"));
return;
}
/* Generate a client random, and determine encryption keys */
g_random(self->client_random, 32);
rdp_sec_rsa_op(self->client_crypt_random, self->client_random,
modulus, exponent);
rdp_sec_generate_keys(self);
}
/*****************************************************************************/
/* Process connect response data blob */
static void APP_CC
rdp_sec_process_mcs_data(struct rdp_sec *self)
{
int tag;
int length;
int len;
char *next_tag;
struct stream *s;
s = self->server_mcs_data;
s->p = s->data;
in_uint8s(s, 21); /* header (T.124 ConferenceCreateResponse) */
in_uint8(s, len);
if (len & 0x80)
{
in_uint8(s, len);
}
while (s->p < s->end)
{
in_uint16_le(s, tag);
in_uint16_le(s, length);
DEBUG((" rdp_sec_process_mcs_data tag %d length %d", tag, length));
if (length <= 4)
{
return;
}
next_tag = (s->p + length) - 4;
switch (tag)
{
case SEC_TAG_SRV_INFO:
//rdp_sec_process_srv_info(self, s);
break;
case SEC_TAG_SRV_CRYPT:
rdp_sec_process_crypt_info(self, s);
break;
case SEC_TAG_SRV_CHANNELS:
break;
default:
break;
}
s->p = next_tag;
}
}
/*****************************************************************************/
/* Transfer the client random to the server */
/* returns error */
static int APP_CC
rdp_sec_establish_key(struct rdp_sec *self)
{
int length;
int flags;
struct stream *s;
DEBUG((" sending client random"));
make_stream(s);
init_stream(s, 8192);
length = SEC_MODULUS_SIZE + SEC_PADDING_SIZE;
flags = SEC_CLIENT_RANDOM;
if (rdp_sec_init(self, s, flags) != 0)
{
free_stream(s);
return 1;
}
out_uint32_le(s, length);
out_uint8p(s, self->client_crypt_random, SEC_MODULUS_SIZE);
out_uint8s(s, SEC_PADDING_SIZE);
s_mark_end(s);
if (rdp_sec_send(self, s, flags) != 0)
{
free_stream(s);
return 1;
}
free_stream(s);
return 0;
}
/*****************************************************************************/
/* Establish a secure connection */
int APP_CC
rdp_sec_connect(struct rdp_sec *self, char *ip, char *port)
{
DEBUG((" in rdp_sec_connect"));
rdp_sec_out_mcs_data(self);
if (rdp_mcs_connect(self->mcs_layer, ip, port) != 0)
{
DEBUG((" out rdp_sec_connect error rdp_mcs_connect failed"));
return 1;
}
rdp_sec_process_mcs_data(self);
if (rdp_sec_establish_key(self) != 0)
{
DEBUG((" out rdp_sec_connect error rdp_sec_establish_key failed"));
return 1;
}
DEBUG((" out rdp_sec_connect"));
return 0;
}
/*****************************************************************************/
/* returns error */
int APP_CC
rdp_sec_init(struct rdp_sec *self, struct stream *s, int flags)
{
if (rdp_mcs_init(self->mcs_layer, s) != 0)
{
return 1;
}
if (flags & SEC_ENCRYPT)
{
s_push_layer(s, sec_hdr, 12);
}
else
{
s_push_layer(s, sec_hdr, 4);
}
return 0;
}
/*****************************************************************************/
/* Output a uint32 into a buffer (little-endian) */
void APP_CC
rdp_sec_buf_out_uint32(char *buffer, int 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 APP_CC
rdp_sec_sign(char *signature, int siglen, char *session_key, int keylen,
char *data, int datalen)
{
char shasig[20];
char md5sig[16];
char lenhdr[4];
void *sha1_context;
void *md5_context;
rdp_sec_buf_out_uint32(lenhdr, datalen);
sha1_context = ssl_sha1_info_create();
ssl_sha1_clear(sha1_context);
ssl_sha1_transform(sha1_context, session_key, keylen);
ssl_sha1_transform(sha1_context, g_pad_54, 40);
ssl_sha1_transform(sha1_context, lenhdr, 4);
ssl_sha1_transform(sha1_context, data, datalen);
ssl_sha1_complete(sha1_context, shasig);
ssl_sha1_info_delete(sha1_context);
md5_context = ssl_md5_info_create();
ssl_md5_clear(md5_context);
ssl_md5_transform(md5_context, session_key, keylen);
ssl_md5_transform(md5_context, g_pad_92, 48);
ssl_md5_transform(md5_context, shasig, 20);
ssl_md5_complete(md5_context, md5sig);
ssl_md5_info_delete(md5_context);
g_memcpy(signature, md5sig, siglen);
}
/*****************************************************************************/
/* Encrypt data using RC4 */
static void APP_CC
rdp_sec_encrypt(struct rdp_sec *self, char *data, int length)
{
if (self->encrypt_use_count == 4096)
{
rdp_sec_update(self->encrypt_key, self->encrypt_update_key,
self->rc4_key_len);
ssl_rc4_set_key(self->encrypt_rc4_info, self->encrypt_key,
self->rc4_key_len);
self->encrypt_use_count = 0;
}
ssl_rc4_crypt(self->encrypt_rc4_info, data, length);
self->encrypt_use_count++;
}
/*****************************************************************************/
/* returns error */
int APP_CC
rdp_sec_send(struct rdp_sec *self, struct stream *s, int flags)
{
int datalen;
DEBUG((" in rdp_sec_send flags %8.8x", flags));
s_pop_layer(s, sec_hdr);
out_uint32_le(s, flags);
if (flags & SEC_ENCRYPT)
{
datalen = (s->end - s->p) - 8;
rdp_sec_sign(s->p, 8, self->sign_key, self->rc4_key_len, s->p + 8,
datalen);
rdp_sec_encrypt(self, s->p + 8, datalen);
}
if (rdp_mcs_send(self->mcs_layer, s) != 0)
{
DEBUG((" out rdp_sec_send, rdp_mcs_send failed"));
return 1;
}
DEBUG((" out rdp_sec_send"));
return 0;
}
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