From ce91af8ad27e5ddef1e1f8316129bfcaa3de9ef6 Mon Sep 17 00:00:00 2001 From: Alexander Chernavin Date: Wed, 20 Jul 2022 12:43:42 +0000 Subject: wireguard: add dos mitigation support Type: feature With this change: - if the number of received handshake messages exceeds the limit calculated based on the peers number, under load state will activate; - if being under load a handshake message with a valid mac1 is received, but mac2 is invalid, a cookie reply will be sent. Also, cover these with tests. Signed-off-by: Alexander Chernavin Change-Id: I3003570a9cf807cfb0b5145b89a085455c30e717 --- src/plugins/wireguard/wireguard_send.c | 98 ++++++++++++++++++++++++++++++---- 1 file changed, 87 insertions(+), 11 deletions(-) (limited to 'src/plugins/wireguard/wireguard_send.c') diff --git a/src/plugins/wireguard/wireguard_send.c b/src/plugins/wireguard/wireguard_send.c index 53692f074da..509fe70c777 100644 --- a/src/plugins/wireguard/wireguard_send.c +++ b/src/plugins/wireguard/wireguard_send.c @@ -41,7 +41,7 @@ ip46_enqueue_packet (vlib_main_t *vm, u32 bi0, int is_ip4) } static void -wg_buffer_prepend_rewrite (vlib_buffer_t *b0, const wg_peer_t *peer, u8 is_ip4) +wg_buffer_prepend_rewrite (vlib_buffer_t *b0, const u8 *rewrite, u8 is_ip4) { if (is_ip4) { @@ -52,7 +52,7 @@ wg_buffer_prepend_rewrite (vlib_buffer_t *b0, const wg_peer_t *peer, u8 is_ip4) hdr4 = vlib_buffer_get_current (b0); /* copy only ip4 and udp header; wireguard header not needed */ - clib_memcpy (hdr4, peer->rewrite, sizeof (ip4_udp_header_t)); + clib_memcpy (hdr4, rewrite, sizeof (ip4_udp_header_t)); hdr4->udp.length = clib_host_to_net_u16 (b0->current_length - sizeof (ip4_header_t)); @@ -68,7 +68,7 @@ wg_buffer_prepend_rewrite (vlib_buffer_t *b0, const wg_peer_t *peer, u8 is_ip4) hdr6 = vlib_buffer_get_current (b0); /* copy only ip6 and udp header; wireguard header not needed */ - clib_memcpy (hdr6, peer->rewrite, sizeof (ip6_udp_header_t)); + clib_memcpy (hdr6, rewrite, sizeof (ip6_udp_header_t)); hdr6->udp.length = clib_host_to_net_u16 (b0->current_length - sizeof (ip6_header_t)); @@ -78,7 +78,7 @@ wg_buffer_prepend_rewrite (vlib_buffer_t *b0, const wg_peer_t *peer, u8 is_ip4) } static bool -wg_create_buffer (vlib_main_t *vm, const wg_peer_t *peer, const u8 *packet, +wg_create_buffer (vlib_main_t *vm, const u8 *rewrite, const u8 *packet, u32 packet_len, u32 *bi, u8 is_ip4) { u32 n_buf0 = 0; @@ -95,11 +95,57 @@ wg_create_buffer (vlib_main_t *vm, const wg_peer_t *peer, const u8 *packet, b0->current_length = packet_len; - wg_buffer_prepend_rewrite (b0, peer, is_ip4); + wg_buffer_prepend_rewrite (b0, rewrite, is_ip4); return true; } +u8 * +wg_build_rewrite (ip46_address_t *src_addr, u16 src_port, + ip46_address_t *dst_addr, u16 dst_port, u8 is_ip4) +{ + u8 *rewrite = NULL; + if (is_ip4) + { + ip4_udp_header_t *hdr; + + /* reserve space for ip4, udp and wireguard headers */ + vec_validate (rewrite, sizeof (ip4_udp_wg_header_t) - 1); + hdr = (ip4_udp_header_t *) rewrite; + + hdr->ip4.ip_version_and_header_length = 0x45; + hdr->ip4.ttl = 64; + hdr->ip4.src_address = src_addr->ip4; + hdr->ip4.dst_address = dst_addr->ip4; + hdr->ip4.protocol = IP_PROTOCOL_UDP; + hdr->ip4.checksum = ip4_header_checksum (&hdr->ip4); + + hdr->udp.src_port = clib_host_to_net_u16 (src_port); + hdr->udp.dst_port = clib_host_to_net_u16 (dst_port); + hdr->udp.checksum = 0; + } + else + { + ip6_udp_header_t *hdr; + + /* reserve space for ip6, udp and wireguard headers */ + vec_validate (rewrite, sizeof (ip6_udp_wg_header_t) - 1); + hdr = (ip6_udp_header_t *) rewrite; + + hdr->ip6.ip_version_traffic_class_and_flow_label = 0x60; + ip6_address_copy (&hdr->ip6.src_address, &src_addr->ip6); + ip6_address_copy (&hdr->ip6.dst_address, &dst_addr->ip6); + hdr->ip6.protocol = IP_PROTOCOL_UDP; + hdr->ip6.hop_limit = 64; + + hdr->udp.src_port = clib_host_to_net_u16 (src_port); + hdr->udp.dst_port = clib_host_to_net_u16 (dst_port); + hdr->udp.checksum = 0; + } + + return (rewrite); +} + bool wg_send_handshake (vlib_main_t * vm, wg_peer_t * peer, bool is_retry) { @@ -135,8 +181,8 @@ wg_send_handshake (vlib_main_t * vm, wg_peer_t * peer, bool is_retry) u8 is_ip4 = ip46_address_is_ip4 (&peer->dst.addr); u32 bi0 = 0; - if (!wg_create_buffer (vm, peer, (u8 *) &packet, sizeof (packet), &bi0, - is_ip4)) + if (!wg_create_buffer (vm, peer->rewrite, (u8 *) &packet, sizeof (packet), + &bi0, is_ip4)) return false; ip46_enqueue_packet (vm, bi0, is_ip4); @@ -211,8 +257,8 @@ wg_send_keepalive (vlib_main_t * vm, wg_peer_t * peer) u8 is_ip4 = ip46_address_is_ip4 (&peer->dst.addr); packet->header.type = MESSAGE_DATA; - if (!wg_create_buffer (vm, peer, (u8 *) packet, size_of_packet, &bi0, - is_ip4)) + if (!wg_create_buffer (vm, peer->rewrite, (u8 *) packet, size_of_packet, + &bi0, is_ip4)) { ret = false; goto out; @@ -252,8 +298,8 @@ wg_send_handshake_response (vlib_main_t * vm, wg_peer_t * peer) u32 bi0 = 0; u8 is_ip4 = ip46_address_is_ip4 (&peer->dst.addr); - if (!wg_create_buffer (vm, peer, (u8 *) &packet, sizeof (packet), - &bi0, is_ip4)) + if (!wg_create_buffer (vm, peer->rewrite, (u8 *) &packet, + sizeof (packet), &bi0, is_ip4)) return false; ip46_enqueue_packet (vm, bi0, is_ip4); @@ -264,6 +310,36 @@ wg_send_handshake_response (vlib_main_t * vm, wg_peer_t * peer) return false; } +bool +wg_send_handshake_cookie (vlib_main_t *vm, u32 sender_index, + cookie_checker_t *cookie_checker, + message_macs_t *macs, ip46_address_t *wg_if_addr, + u16 wg_if_port, ip46_address_t *remote_addr, + u16 remote_port) +{ + message_handshake_cookie_t packet; + u8 *rewrite; + + packet.header.type = MESSAGE_HANDSHAKE_COOKIE; + packet.receiver_index = sender_index; + + cookie_checker_create_payload (vm, cookie_checker, macs, packet.nonce, + packet.encrypted_cookie, remote_addr, + remote_port); + + u32 bi0 = 0; + u8 is_ip4 = ip46_address_is_ip4 (remote_addr); + rewrite = wg_build_rewrite (wg_if_addr, wg_if_port, remote_addr, remote_port, + is_ip4); + if (!wg_create_buffer (vm, rewrite, (u8 *) &packet, sizeof (packet), &bi0, + is_ip4)) + return false; + + ip46_enqueue_packet (vm, bi0, is_ip4); + + return true; +} + /* * fd.io coding-style-patch-verification: ON * -- cgit 1.2.3-korg