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xrdp/libxrdp/xrdp_iso.c

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/**
* xrdp: A Remote Desktop Protocol server.
*
* Copyright (C) Jay Sorg 2004-2014
* Copyright (C) Idan Freiberg 2013-2014
*
* 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.
*
* iso layer
*/
#if defined(HAVE_CONFIG_H)
#include <config_ac.h>
#endif
#include "libxrdp.h"
#include "ms-rdpbcgr.h"
#include "log.h"
#define LOG_LEVEL 1
#define LLOG(_level, _args) \
do { if (_level < LOG_LEVEL) { g_write _args ; } } while (0)
#define LLOGLN(_level, _args) \
do { if (_level < LOG_LEVEL) { g_writeln _args ; } } while (0)
#define LHEXDUMP(_level, _args) \
do { if (_level < LOG_LEVEL) { g_hexdump _args ; } } while (0)
/*****************************************************************************/
struct xrdp_iso *
xrdp_iso_create(struct xrdp_mcs *owner, struct trans *trans)
{
struct xrdp_iso *self;
LLOGLN(10, (" in xrdp_iso_create"));
self = (struct xrdp_iso *) g_malloc(sizeof(struct xrdp_iso), 1);
self->mcs_layer = owner;
self->trans = trans;
LLOGLN(10, (" out xrdp_iso_create"));
return self;
}
/*****************************************************************************/
void
xrdp_iso_delete(struct xrdp_iso *self)
{
if (self == 0)
{
return;
}
g_free(self);
}
/*****************************************************************************/
/* returns error */
static int
xrdp_iso_negotiate_security(struct xrdp_iso *self)
{
int rv = 0;
struct xrdp_client_info *client_info = &(self->mcs_layer->sec_layer->rdp_layer->client_info);
self->selectedProtocol = client_info->security_layer;
switch (client_info->security_layer)
{
case PROTOCOL_RDP:
break;
case PROTOCOL_SSL:
if (self->requestedProtocol & PROTOCOL_SSL)
{
if (!g_file_readable(client_info->certificate) ||
!g_file_readable(client_info->key_file))
{
/* certificate or privkey is not readable */
log_message(LOG_LEVEL_DEBUG, "No readable certificates or "
"private keys, cannot accept TLS connections");
self->failureCode = SSL_CERT_NOT_ON_SERVER;
rv = 1; /* error */
}
else
{
self->selectedProtocol = PROTOCOL_SSL;
}
}
else
{
self->failureCode = SSL_REQUIRED_BY_SERVER;
rv = 1; /* error */
}
break;
case PROTOCOL_HYBRID:
case PROTOCOL_HYBRID_EX:
default:
if ((self->requestedProtocol & PROTOCOL_SSL) &&
g_file_readable(client_info->certificate) &&
g_file_readable(client_info->key_file))
{
/* that's a patch since we don't support CredSSP for now */
self->selectedProtocol = PROTOCOL_SSL;
}
else
{
self->selectedProtocol = PROTOCOL_RDP;
}
break;
}
log_message(LOG_LEVEL_DEBUG, "Security layer: requested %d, selected %d",
self->requestedProtocol, self->selectedProtocol);
return rv;
}
/*****************************************************************************/
/* returns error */
static int
xrdp_iso_process_rdp_neg_req(struct xrdp_iso *self, struct stream *s)
{
int flags;
int len;
if (!s_check_rem(s, 7))
{
LLOGLN(10, ("xrdp_iso_process_rdpNegReq: unexpected end-of-record"));
return 1;
}
in_uint8(s, flags);
if (flags != 0x0 && flags != 0x8 && flags != 0x1)
{
LLOGLN(10, ("xrdp_iso_process_rdpNegReq: error, flags: %x",flags));
return 1;
}
in_uint16_le(s, len);
if (len != 8)
{
LLOGLN(10, ("xrdp_iso_process_rdpNegReq: error, length: %x",len));
return 1;
}
in_uint32_le(s, self->requestedProtocol);
if (self->requestedProtocol > 0xb)
{
LLOGLN(10, ("xrdp_iso_process_rdpNegReq: error, requestedProtocol: %x",
self->requestedProtocol));
return 1;
}
return 0;
}
/*****************************************************************************
* Reads an X.224 PDU (X.224 section 13) preceded by a T.123 TPKT
* header (T.123 section 8)
*
* On entry, the TPKT header length field will have been inspected and used to
* set up the input stream.
*
* On exit, the TPKT header and the fixed part of the PDU header will have been
* removed from the stream.
*
* Returns error
*****************************************************************************/
static int
xrdp_iso_recv_msg(struct xrdp_iso *self, struct stream *s, int *code, int *len)
{
int ver;
*code = 0;
*len = 0;
if (s != self->trans->in_s)
{
LLOGLN(10, ("xrdp_iso_recv_msg error logic"));
}
/* TPKT header is 4 bytes, then first 2 bytes of the X.224 CR-TPDU */
if (!s_check_rem(s, 6))
{
return 1;
}
in_uint8(s, ver);
in_uint8s(s, 3); /* Skip reserved field, plus length */
in_uint8(s, *len);
in_uint8(s, *code);
if (ver != 3)
{
LLOGLN(10, ("xrdp_iso_recv_msg: bad ver"));
LHEXDUMP(10, (s->data, 4));
return 1;
}
if (*len == 255)
{
/* X.224 13.2.1 - reserved value */
LLOGLN(10, ("xrdp_iso_recv_msg: reserved length encountered"));
LHEXDUMP(10, (s->data, 4));
return 1;
}
if (*code == ISO_PDU_DT)
{
/* Data PDU : X.224 13.7 */
if (!s_check_rem(s, 1))
{
return 1;
}
in_uint8s(s, 1);
}
else
{
/* Other supported PDUs : X.224 13.x */
if (!s_check_rem(s, 5))
{
return 1;
}
in_uint8s(s, 5);
}
return 0;
}
/*****************************************************************************/
/* returns error */
int
xrdp_iso_recv(struct xrdp_iso *self, struct stream *s)
{
int code;
int len;
LLOGLN(10, (" in xrdp_iso_recv"));
if (xrdp_iso_recv_msg(self, s, &code, &len) != 0)
{
LLOGLN(10, (" out xrdp_iso_recv xrdp_iso_recv_msg return non zero"));
return 1;
}
if (code != ISO_PDU_DT || len != 2)
{
LLOGLN(10, (" out xrdp_iso_recv code != ISO_PDU_DT or length != 2"));
return 1;
}
LLOGLN(10, (" out xrdp_iso_recv"));
return 0;
}
/*****************************************************************************/
static int
xrdp_iso_send_cc(struct xrdp_iso *self)
{
struct stream *s;
char *holdp;
char *len_ptr;
char *len_indicator_ptr;
int len;
int len_indicator;
make_stream(s);
init_stream(s, 8192);
holdp = s->p;
/* tpkt */
out_uint8(s, 3); /* version */
out_uint8(s, 0); /* pad */
len_ptr = s->p;
out_uint16_be(s, 0); /* length, set later */
/* iso */
len_indicator_ptr = s->p;
out_uint8(s, 0); /* length indicator, set later */
out_uint8(s, ISO_PDU_CC); /* Connection Confirm PDU */
out_uint16_be(s, 0);
out_uint16_be(s, 0x1234);
out_uint8(s, 0);
/* rdpNegData */
if (self->rdpNegData)
{
if (self->failureCode)
{
out_uint8(s, RDP_NEG_FAILURE);
out_uint8(s, 0); /* no flags */
out_uint16_le(s, 8); /* must be 8 */
out_uint32_le(s, self->failureCode); /* failure code */
}
else
{
out_uint8(s, RDP_NEG_RSP);
//TODO: hardcoded flags
out_uint8(s, EXTENDED_CLIENT_DATA_SUPPORTED); /* flags */
out_uint16_le(s, 8); /* must be 8 */
out_uint32_le(s, self->selectedProtocol); /* selected protocol */
}
}
s_mark_end(s);
len = (int) (s->end - holdp);
len_indicator = (int) (s->end - len_indicator_ptr) - 1;
len_ptr[0] = len >> 8;
len_ptr[1] = len;
len_indicator_ptr[0] = len_indicator;
if (trans_write_copy_s(self->trans, s) != 0)
{
free_stream(s);
return 1;
}
free_stream(s);
return 0;
}
/*****************************************************************************
* Process an X.224 connection request PDU
*
* See MS-RDPCGR v20190923 sections 2.2.1.1 and 3.3.5.3.1.
*
* From the latter, in particular:-
* - The length embedded in the TPKT header MUST be examined for
* consistency with the received data. If there is a discrepancy, the
* connection SHOULD be dropped
* - If the optional routingToken field exists it MUST be ignored.
* - If the optional cookie field is present it MUST be ignored.
* - If both the routingToken and cookie fields are present, the server
* SHOULD continue with the connection.
*****************************************************************************/
/* returns error */
int
xrdp_iso_incoming(struct xrdp_iso *self)
{
int rv = 0;
int code;
int len;
int cc_type;
struct stream *s;
int expected_pdu_len;
LLOGLN(10, (" in xrdp_iso_incoming"));
s = libxrdp_force_read(self->trans);
if (s == NULL)
{
return 1;
}
if (xrdp_iso_recv_msg(self, s, &code, &len) != 0)
{
LLOGLN(0, ("xrdp_iso_incoming: xrdp_iso_recv_msg returned non zero"));
return 1;
}
if (code != ISO_PDU_CR)
{
return 1;
}
/*
* Make sure the length indicator field extracted from the X.224
* connection request TPDU corresponds to the length in the TPKT header.
*
* We do this by seeing how the indicator field minus the counted
* octets in the TPDU header (6) compares with the space left in
* the stream.
*/
expected_pdu_len = (s->end - s->p) + 6;
if (len != expected_pdu_len)
{
LLOGLN(0, ("xrdp_iso_incoming: X.224 CR-TPDU length exp %d got %d",
expected_pdu_len, len));
return 1;
}
/* process connection request */
while (s_check_rem(s, 1))
{
in_uint8(s, cc_type);
switch (cc_type)
{
default:
break;
case RDP_NEG_REQ: /* rdpNegReq 1 */
self->rdpNegData = 1;
if (xrdp_iso_process_rdp_neg_req(self, s) != 0)
{
LLOGLN(0, ("xrdp_iso_incoming: xrdp_iso_process_rdpNegReq returned non zero"));
return 1;
}
break;
case RDP_CORRELATION_INFO: /* rdpCorrelationInfo 6 */
// TODO
if (!s_check_rem(s, 1 + 2 + 16 + 16))
{
LLOGLN(0, ("xrdp_iso_incoming: short correlation info"));
return 1;
}
in_uint8s(s, 1 + 2 + 16 + 16);
break;
case 'C': /* Cookie */
/* The routingToken and cookie fields are both ASCII
* strings starting with the word 'Cookie: ' and
* ending with CR+LF. We ignore both, so we do
* not need to distinguish them */
while (s_check_rem(s, 1))
{
in_uint8(s, cc_type);
if (cc_type == 0x0D && s_check_rem(s, 1))
{
in_uint8(s, cc_type);
if (cc_type == 0x0A)
{
break;
}
}
}
break;
}
}
/* negotiate client-server security layer */
rv = xrdp_iso_negotiate_security(self);
/* send connection confirm back to client */
if (xrdp_iso_send_cc(self) != 0)
{
LLOGLN(0, ("xrdp_iso_incoming: xrdp_iso_send_cc returned non zero"));
return 1;
}
LLOGLN(10, (" out xrdp_iso_incoming"));
return rv;
}
/*****************************************************************************/
/* returns error */
int
xrdp_iso_init(struct xrdp_iso *self, struct stream *s)
{
init_stream(s, 8192 * 4); /* 32 KB */
s_push_layer(s, iso_hdr, 7);
return 0;
}
/*****************************************************************************/
/* returns error */
int
xrdp_iso_send(struct xrdp_iso *self, struct stream *s)
{
int len;
LLOGLN(10, (" in xrdp_iso_send"));
s_pop_layer(s, iso_hdr);
len = (int) (s->end - s->p);
out_uint8(s, 3);
out_uint8(s, 0);
out_uint16_be(s, len);
out_uint8(s, 2);
out_uint8(s, ISO_PDU_DT);
out_uint8(s, 0x80);
if (trans_write_copy_s(self->trans, s) != 0)
{
return 1;
}
LLOGLN(10, (" out xrdp_iso_send"));
return 0;
}
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