diff options
Diffstat (limited to 'src/lib/protocols/ipsec.c')
| -rw-r--r-- | src/lib/protocols/ipsec.c | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/src/lib/protocols/ipsec.c b/src/lib/protocols/ipsec.c new file mode 100644 index 000000000..c2fb62c4a --- /dev/null +++ b/src/lib/protocols/ipsec.c @@ -0,0 +1,198 @@ +/* + * ipsec.c + * + * Copyright (C) 2022 - 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" + +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(ndpi_struct, 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; +} + +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_PROTOCOL_BITMASK *detection_bitmask) +{ + ndpi_set_bitmask_protocol_detection("IPSec", ndpi_struct, detection_bitmask, *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; +} + |