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/* Packet-rdp_ear.c
* Routines for the redirected authentication RDP channel
* Copyright 2023, David Fort <contact@hardening-consulting.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/*
* See: "[MS-RDPEAR] "
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/prefs.h>
#include <epan/conversation.h>
#include <epan/expert.h>
#include <epan/value_string.h>
#include <epan/asn1.h>
#include "packet-gssapi.h"
#include "packet-ber.h"
#define PNAME "RDP authentication redirection virtual channel Protocol"
#define PSNAME "rdpear"
#define PFNAME "rdp_ear"
void proto_register_rdp_ear(void);
void proto_reg_handoff_rdp_ear(void);
static int proto_rdp_ear;
static int hf_rdpear_protocolMagic;
static int hf_rdpear_length;
static int hf_rdpear_version;
static int hf_rdpear_reserved;
static int hf_rdpear_tspkgcontext;
static int hf_rdpear_payload;
static int hf_rdpear_packet_version;
static int hf_rdpear_packet_packageName;
static int hf_rdpear_packet_buffer;
static int ett_rdp_ear;
static int ett_rdp_ear_innerPacket;
static dissector_handle_t gssapi_wrap_handle;
static int
dissect_rdpear_ber_VERSION(bool implicit_tag, tvbuff_t *tvb, int offset, asn1_ctx_t *actx, proto_tree *tree, int hf_index) {
offset = dissect_ber_integer(implicit_tag, actx, tree, tvb, offset, hf_index, NULL);
return offset;
}
static int
dissect_rdpear_ber_packageName(bool implicit_tag, tvbuff_t *tvb, int offset, asn1_ctx_t *actx, proto_tree *tree, int hf_index) {
offset = dissect_ber_octet_string_with_encoding(implicit_tag, actx, tree, tvb, offset, hf_index, NULL, ENC_UTF_16|ENC_LITTLE_ENDIAN);
return offset;
}
static int
dissect_rdpear_ber_packetBuffer(bool implicit_tag, tvbuff_t *tvb, int offset, asn1_ctx_t *actx, proto_tree *tree, int hf_index) {
offset = dissect_ber_octet_string(implicit_tag, actx, tree, tvb, offset, hf_index, NULL);
return offset;
}
static const ber_sequence_t TSRemoteGuardInnerPacket_sequence[] = {
{ &hf_rdpear_packet_version, BER_CLASS_CON, 0, BER_FLAGS_OPTIONAL, dissect_rdpear_ber_VERSION },
{ &hf_rdpear_packet_packageName, BER_CLASS_CON, 1, 0, dissect_rdpear_ber_packageName },
{ &hf_rdpear_packet_buffer, BER_CLASS_CON, 2, 0, dissect_rdpear_ber_packetBuffer },
{ NULL, 0, 0, 0, NULL }
};
static int dissect_rcg_payload(packet_info *pinfo, proto_tree *tree, tvbuff_t *tvb, int offset)
{
asn1_ctx_t asn1_ctx;
asn1_ctx_init(&asn1_ctx, ASN1_ENC_BER, true, pinfo);
offset = dissect_ber_sequence(false, &asn1_ctx, tree, tvb, offset,
TSRemoteGuardInnerPacket_sequence, hf_rdpear_payload, ett_rdp_ear_innerPacket);
return offset;
}
static int
dissect_rdp_ear(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void *data _U_)
{
tvbuff_t *payload_tvb = NULL;
tvbuff_t *decr_tvb = NULL;
gssapi_encrypt_info_t gssapi_encrypt;
proto_item *item;
int nextOffset, offset = 0;
uint32_t pduLength;
proto_tree *tree;
parent_tree = proto_tree_get_root(parent_tree);
col_set_str(pinfo->cinfo, COL_PROTOCOL, "RDPEAR");
col_clear(pinfo->cinfo, COL_INFO);
pduLength = tvb_get_uint32(tvb, offset + 4, ENC_LITTLE_ENDIAN) + 24;
nextOffset = offset + pduLength;
item = proto_tree_add_item(parent_tree, proto_rdp_ear, tvb, offset, pduLength, ENC_NA);
tree = proto_item_add_subtree(item, ett_rdp_ear);
proto_tree_add_item(tree, hf_rdpear_protocolMagic, tvb, offset, 4, ENC_LITTLE_ENDIAN);
offset += 4;
proto_tree_add_item(tree, hf_rdpear_length, tvb, offset, 4, ENC_LITTLE_ENDIAN);
offset += 4;
proto_tree_add_item(tree, hf_rdpear_version, tvb, offset, 4, ENC_LITTLE_ENDIAN);
offset += 4;
proto_tree_add_item(tree, hf_rdpear_reserved, tvb, offset, 4, ENC_LITTLE_ENDIAN);
offset += 4;
proto_tree_add_item(tree, hf_rdpear_tspkgcontext, tvb, offset, 8, ENC_LITTLE_ENDIAN);
offset += 8;
/* ================== */
payload_tvb = tvb_new_subset_length(tvb, offset, pduLength - 24);
memset(&gssapi_encrypt, 0, sizeof(gssapi_encrypt));
gssapi_encrypt.decrypt_gssapi_tvb = DECRYPT_GSSAPI_NORMAL;
call_dissector_with_data(gssapi_wrap_handle, payload_tvb, pinfo, tree, &gssapi_encrypt);
decr_tvb = gssapi_encrypt.gssapi_decrypted_tvb;
if (decr_tvb != NULL) {
dissect_rcg_payload(pinfo, tree, decr_tvb, 0);
}
offset = nextOffset;
return offset;
}
void proto_register_rdp_ear(void) {
static hf_register_info hf[] = {
{ &hf_rdpear_protocolMagic,
{ "Protocol magic", "rdp_ear.magic",
FT_UINT32, BASE_HEX, NULL, 0x0,
NULL, HFILL }},
{ &hf_rdpear_length,
{ "Length", "rdp_ear.length",
FT_UINT32, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_rdpear_version,
{ "Version", "rdp_ear.version",
FT_UINT32, BASE_HEX, NULL, 0x0,
NULL, HFILL }},
{ &hf_rdpear_reserved,
{ "Reserved", "rdp_ear.reserved",
FT_UINT32, BASE_HEX, NULL, 0x0,
NULL, HFILL }},
{ &hf_rdpear_tspkgcontext,
{ "TsPkgContext", "rdp_ear.tspkgcontext",
FT_UINT64, BASE_HEX, NULL, 0x0,
NULL, HFILL }},
{ &hf_rdpear_payload,
{ "Payload", "rdp_ear.payload",
FT_NONE, BASE_NONE, NULL, 0,
NULL, HFILL }},
{ &hf_rdpear_packet_version,
{ "Version", "rdp_ear.payload.version",
FT_INT32, BASE_DEC, NULL, 0,
NULL, HFILL }},
{ &hf_rdpear_packet_packageName,
{ "Package", "rdp_ear.payload.package",
FT_STRING, BASE_NONE, NULL, 0,
NULL, HFILL }},
{ &hf_rdpear_packet_buffer,
{ "Buffer", "rdp_ear.payload.buffer",
FT_BYTES, BASE_NONE, NULL, 0,
NULL, HFILL }},
};
static int *ett[] = {
&ett_rdp_ear,
&ett_rdp_ear_innerPacket,
};
proto_rdp_ear = proto_register_protocol(PNAME, PSNAME, PFNAME);
/* Register fields and subtrees */
proto_register_field_array(proto_rdp_ear, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
register_dissector("rdp_ear", dissect_rdp_ear, proto_rdp_ear);
}
void proto_reg_handoff_rdp_ear(void) {
gssapi_wrap_handle = find_dissector_add_dependency("gssapi_verf", proto_rdp_ear);
}
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