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/*
* ipsec.c
*
* Copyright (C) 2022-23 - ntop.org
*
* nDPI is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* nDPI 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with nDPI. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include "ndpi_protocol_ids.h"
#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_IPSEC
#include "ndpi_api.h"
#include "ndpi_private.h"
enum isakmp_type {
ISAKMP_INVALID = 0,
ISAKMP_MALFORMED,
ISAKMP_V1,
ISAKMP_V2,
};
static void ndpi_int_ipsec_add_connection(struct ndpi_detection_module_struct * const ndpi_struct,
struct ndpi_flow_struct * const flow,
enum isakmp_type isakmp_type)
{
switch (isakmp_type)
{
case ISAKMP_INVALID:
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
case ISAKMP_MALFORMED:
NDPI_LOG_INFO(ndpi_struct, "found malformed ISAKMP (UDP)\n");
ndpi_set_risk(flow, NDPI_MALFORMED_PACKET, "Invalid IPSec/ISAKMP Header");
break;
case ISAKMP_V1:
NDPI_LOG_INFO(ndpi_struct, "found ISAKMPv1 (UDP)\n");
break;
case ISAKMP_V2:
NDPI_LOG_INFO(ndpi_struct, "found ISAKMPv2 (UDP)\n");
break;
}
ndpi_set_detected_protocol(ndpi_struct, flow,
NDPI_PROTOCOL_IPSEC,
NDPI_PROTOCOL_UNKNOWN,
NDPI_CONFIDENCE_DPI);
}
static enum isakmp_type ndpi_int_check_ports(struct ndpi_packet_struct const * const packet)
{
u_int16_t sport = ntohs(packet->udp->source);
u_int16_t dport = ntohs(packet->udp->dest);
/*
* If packet matches default IPSec/ISAKMP ports, it is most likely malformed,
* not IPSec/ISAKMP otherwise.
*/
if (sport == 500 || dport == 500 ||
sport == 4500 || dport == 4500)
{
return ISAKMP_MALFORMED;
}
return ISAKMP_INVALID;
}
static enum isakmp_type ndpi_int_check_isakmp_v1(struct ndpi_packet_struct const * const packet,
u_int16_t isakmp_offset, enum isakmp_type isakmp_type)
{
/* Next payload type */
if (packet->payload[isakmp_offset + 16] >= 14 && packet->payload[isakmp_offset + 16] <= 127)
{
return ndpi_int_check_ports(packet);
}
/* Exchange Type */
if (packet->payload[isakmp_offset + 18] >= 6 && packet->payload[isakmp_offset + 18] < 31)
{
return ndpi_int_check_ports(packet);
}
/* Flags */
if (packet->payload[isakmp_offset + 19] >= 8)
{
return ndpi_int_check_ports(packet);
}
return isakmp_type;
}
static enum isakmp_type ndpi_int_check_isakmp_v2(struct ndpi_packet_struct const * const packet,
u_int16_t isakmp_offset, enum isakmp_type isakmp_type)
{
/* Next payload type */
if ((packet->payload[isakmp_offset + 16] > 0 && packet->payload[isakmp_offset + 16] <= 32) ||
(packet->payload[isakmp_offset + 16] >= 49 && packet->payload[isakmp_offset + 16] <= 127))
{
return ndpi_int_check_ports(packet);
}
/* Exchange Type */
if ((packet->payload[isakmp_offset + 18] <= 33) ||
(packet->payload[isakmp_offset + 18] >= 38 && packet->payload[isakmp_offset + 18] <= 239))
{
return ndpi_int_check_ports(packet);
}
/* Flags */
if ((packet->payload[isakmp_offset + 19] & 0xC7) != 0)
{
return ndpi_int_check_ports(packet);
}
return isakmp_type;
}
static void ndpi_search_ipsec(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct * const packet = &ndpi_struct->packet;
u_int16_t isakmp_offset = 0;
enum isakmp_type isakmp_type = ISAKMP_INVALID;
NDPI_LOG_DBG(ndpi_struct, "search IPSEC (UDP)\n");
if (packet->payload_packet_len < 28)
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
/* check for non-ESP marker required for ISAKMP over UDP */
if (get_u_int32_t(packet->payload, 0) == 0x00000000)
{
isakmp_offset = 4;
if (packet->payload_packet_len < 32)
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
}
if (packet->payload[isakmp_offset + 17] != 0x20 /* Major Version 2 */)
{
if (packet->payload[isakmp_offset + 17] != 0x10 /* Major Version 1 */)
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
} else {
/* Version 1 is obsolete, but still used by some embedded devices. */
isakmp_type = ISAKMP_V1;
}
} else {
isakmp_type = ISAKMP_V2;
}
if (ntohl(get_u_int32_t(packet->payload, isakmp_offset + 24)) != (u_int32_t)packet->payload_packet_len - isakmp_offset)
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
if (isakmp_type == ISAKMP_V1)
{
isakmp_type = ndpi_int_check_isakmp_v1(packet, isakmp_offset, isakmp_type);
} else {
isakmp_type = ndpi_int_check_isakmp_v2(packet, isakmp_offset, isakmp_type);
}
ndpi_int_ipsec_add_connection(ndpi_struct, flow, isakmp_type);
}
void init_ipsec_dissector(struct ndpi_detection_module_struct *ndpi_struct,
u_int32_t *id)
{
ndpi_set_bitmask_protocol_detection("IPSec", ndpi_struct, *id,
NDPI_PROTOCOL_IPSEC,
ndpi_search_ipsec,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD,
SAVE_DETECTION_BITMASK_AS_UNKNOWN,
ADD_TO_DETECTION_BITMASK
);
*id += 1;
}
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