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Diffstat (limited to 'src/lib/protocols/wireguard.c')
| -rw-r--r-- | src/lib/protocols/wireguard.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/src/lib/protocols/wireguard.c b/src/lib/protocols/wireguard.c new file mode 100644 index 000000000..902113bf4 --- /dev/null +++ b/src/lib/protocols/wireguard.c @@ -0,0 +1,172 @@ +/* + * wireguard.c + * + * Copyright (C) 2019 - ntop.org + * Copyright (C) 2019 - Yağmur Oymak + * + * This file is part of nDPI, an open source deep packet inspection + * library based on the OpenDPI and PACE technology by ipoque GmbH + * + * 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_WIREGUARD + +#include "ndpi_api.h" + +/* + * See https://www.wireguard.com/protocol/ for protocol reference. + */ + +enum wg_message_type { + WG_TYPE_HANDSHAKE_INITIATION = 1, + WG_TYPE_HANDSHAKE_RESPONSE = 2, + WG_TYPE_COOKIE_REPLY = 3, + WG_TYPE_TRANSPORT_DATA = 4 +}; + +void ndpi_search_wireguard(struct ndpi_detection_module_struct + *ndpi_struct, struct ndpi_flow_struct *flow) +{ + struct ndpi_packet_struct *packet = &flow->packet; + const u_int8_t *payload = packet->payload; + u_int8_t message_type = payload[0]; + + NDPI_LOG_DBG(ndpi_struct, "search WireGuard\n"); + + /* + * First, try some easy ways to rule out the protocol. + * The packet size and the reserved bytes in the header are good candidates. + */ + + /* + * A transport packet contains at minimum the following fields: + * u8 message_type + * u8 reserved_zero[3] + * u32 receiver_index + * u64 counter + * u8 encrypted_encapsulated_packet[] + * In the case of a keepalive message, the encapsulated packet will have + * zero length, but will still have a 16 byte poly1305 authentication tag. + * Thus, packet->payload will be at least 32 bytes in size. + * Note that handshake packets have a slightly different structure, but they are larger. + */ + if (packet->payload_packet_len < 32) { + NDPI_EXCLUDE_PROTO(ndpi_struct, flow); + return; + } + /* + * The next three bytes after the message type are reserved and set to zero. + */ + if (payload[1] != 0 || payload[2] != 0 || payload[3] != 0) { + NDPI_EXCLUDE_PROTO(ndpi_struct, flow); + return; + } + + /* + * Below we make a deeper analysis; possibly inspecting multiple packets to + * look for consistent sender/receiver index fields. We also exploit the fact + * that handshake messages always have a fixed size. + * + * Stages 1-2 means we are processing a handshake sequence. + * Stages 3-4 means we are processing a transport packet sequence. + * + * Message type can be one of the following: + * 1) Handshake Initiation (148 bytes) + * 2) Handshake Response (92 bytes) + * 3) Cookie Reply (64 bytes) + * 4) Transport Data (variable length, min 32 bytes) + */ + if (message_type == WG_TYPE_HANDSHAKE_INITIATION && packet->payload_packet_len == 148) { + u_int32_t sender_index = get_u_int32_t(payload, 4); + /* + * We always start a new detection stage on a handshake initiation. + */ + flow->l4.udp.wireguard_stage = 1 + packet->packet_direction; + flow->l4.udp.wireguard_peer_index[packet->packet_direction] = sender_index; + /* need more packets before deciding */ + } else if (message_type == WG_TYPE_HANDSHAKE_RESPONSE && packet->payload_packet_len == 92) { + if (flow->l4.udp.wireguard_stage == 2 - packet->packet_direction) { + /* + * This means we are probably processing a handshake response to a handshake + * initiation that we've just processed, so we check if the receiver index + * matches the index in the handshake initiation. + */ + u_int32_t receiver_index = get_u_int32_t(payload, 8); + if (receiver_index == flow->l4.udp.wireguard_peer_index[1 - packet->packet_direction]) { + ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_WIREGUARD, NDPI_PROTOCOL_UNKNOWN); + } else { + NDPI_EXCLUDE_PROTO(ndpi_struct, flow); + } + } + /* need more packets before deciding */ + } else if (message_type == WG_TYPE_COOKIE_REPLY && packet->payload_packet_len == 64) { + /* + * A cookie reply is sent as response to a handshake initiation when under load, + * for DoS mitigation. If we have just seen a handshake initiation before + * this cookie reply packet, we check if the receiver index in this packet + * matches the sender index in that handshake initiation packet. + */ + if (flow->l4.udp.wireguard_stage == 2 - packet->packet_direction) { + u_int32_t receiver_index = get_u_int32_t(payload, 4); + if (receiver_index == flow->l4.udp.wireguard_peer_index[1 - packet->packet_direction]) { + ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_WIREGUARD, NDPI_PROTOCOL_UNKNOWN); + } else { + NDPI_EXCLUDE_PROTO(ndpi_struct, flow); + } + } + /* need more packets before deciding */ + } else if (message_type == WG_TYPE_TRANSPORT_DATA) { + /* + * For detecting transport data packets, we save the peer + * indices in both directions first. This requires at least one packet in each + * direction (stages 3-4). The third packet that we process will be checked + * against the appropriate index for a match (stage 5). + */ + u_int32_t receiver_index = get_u_int32_t(payload, 4); + if (flow->l4.udp.wireguard_stage == 0) { + flow->l4.udp.wireguard_stage = 3 + packet->packet_direction; + flow->l4.udp.wireguard_peer_index[packet->packet_direction] = receiver_index; + /* need more packets before deciding */ + } else if (flow->l4.udp.wireguard_stage == 4 - packet->packet_direction) { + flow->l4.udp.wireguard_peer_index[packet->packet_direction] = receiver_index; + flow->l4.udp.wireguard_stage = 5; + /* need more packets before deciding */ + } else if (flow->l4.udp.wireguard_stage == 5) { + if (receiver_index == flow->l4.udp.wireguard_peer_index[packet->packet_direction]) { + ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_WIREGUARD, NDPI_PROTOCOL_UNKNOWN); + } else { + NDPI_EXCLUDE_PROTO(ndpi_struct, flow); + } + } + /* need more packets before deciding */ + } else { + NDPI_EXCLUDE_PROTO(ndpi_struct, flow); + } +} + +void init_wireguard_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask) +{ + ndpi_set_bitmask_protocol_detection("WireGuard", ndpi_struct, detection_bitmask, *id, + NDPI_PROTOCOL_WIREGUARD, + ndpi_search_wireguard, + NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD, + SAVE_DETECTION_BITMASK_AS_UNKNOWN, + ADD_TO_DETECTION_BITMASK); + + *id += 1; +} |