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279 lines
8.4 KiB
C
279 lines
8.4 KiB
C
/* Copyright (C) 2019-2021 Open Information Security Foundation
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*
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* You can copy, redistribute or modify this Program under the terms of
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* the GNU General Public License version 2 as published by the Free
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* Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* version 2 along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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/**
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* \file
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*
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* \author Henrik Kramshoej <hlk@kramse.org>
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*
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* VXLAN tunneling scheme decoder.
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*
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* This implementation is based on the following specification doc:
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* https://tools.ietf.org/html/draft-mahalingam-dutt-dcops-vxlan-00
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*/
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#include "suricata-common.h"
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#include "decode.h"
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#include "decode-vxlan.h"
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#include "decode-events.h"
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#include "detect.h"
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#include "detect-engine-port.h"
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#include "flow.h"
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#include "util-validate.h"
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#include "util-unittest.h"
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#include "util-debug.h"
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#define VXLAN_HEADER_LEN sizeof(VXLANHeader)
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#define VXLAN_MAX_PORTS 4
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#define VXLAN_UNSET_PORT -1
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#define VXLAN_DEFAULT_PORT 4789
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#define VXLAN_DEFAULT_PORT_S "4789"
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static bool g_vxlan_enabled = true;
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static int g_vxlan_ports_idx = 0;
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static int g_vxlan_ports[VXLAN_MAX_PORTS] = { VXLAN_DEFAULT_PORT, VXLAN_UNSET_PORT,
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VXLAN_UNSET_PORT, VXLAN_UNSET_PORT };
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typedef struct VXLANHeader_ {
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uint8_t flags[2];
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uint16_t gdp;
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uint8_t vni[3];
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uint8_t res;
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} VXLANHeader;
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bool DecodeVXLANEnabledForPort(const uint16_t sp, const uint16_t dp)
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{
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SCLogDebug("ports %u->%u ports %d %d %d %d", sp, dp, g_vxlan_ports[0], g_vxlan_ports[1],
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g_vxlan_ports[2], g_vxlan_ports[3]);
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if (g_vxlan_enabled) {
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for (int i = 0; i < g_vxlan_ports_idx; i++) {
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if (g_vxlan_ports[i] == VXLAN_UNSET_PORT)
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return false;
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const int port = g_vxlan_ports[i];
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if (port == (const int)sp || port == (const int)dp)
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return true;
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}
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}
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return false;
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}
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static void DecodeVXLANConfigPorts(const char *pstr)
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{
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SCLogDebug("parsing \'%s\'", pstr);
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DetectPort *head = NULL;
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DetectPortParse(NULL, &head, pstr);
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g_vxlan_ports_idx = 0;
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for (DetectPort *p = head; p != NULL; p = p->next) {
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if (g_vxlan_ports_idx >= VXLAN_MAX_PORTS) {
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SCLogWarning("more than %d VXLAN ports defined", VXLAN_MAX_PORTS);
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break;
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}
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g_vxlan_ports[g_vxlan_ports_idx++] = (int)p->port;
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}
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DetectPortCleanupList(NULL, head);
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}
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void DecodeVXLANConfig(void)
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{
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int enabled = 0;
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if (ConfGetBool("decoder.vxlan.enabled", &enabled) == 1) {
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if (enabled) {
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g_vxlan_enabled = true;
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} else {
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g_vxlan_enabled = false;
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}
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}
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if (g_vxlan_enabled) {
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ConfNode *node = ConfGetNode("decoder.vxlan.ports");
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if (node && node->val) {
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DecodeVXLANConfigPorts(node->val);
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} else {
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DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S);
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}
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}
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}
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/** \param pkt payload data directly above UDP header
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* \param len length in bytes of pkt
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*/
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int DecodeVXLAN(ThreadVars *tv, DecodeThreadVars *dtv, Packet *p,
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const uint8_t *pkt, uint32_t len)
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{
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DEBUG_VALIDATE_BUG_ON(pkt == NULL);
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/* Initial packet validation */
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if (unlikely(!g_vxlan_enabled))
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return TM_ECODE_FAILED;
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if (len < (VXLAN_HEADER_LEN + sizeof(EthernetHdr)))
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return TM_ECODE_FAILED;
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if (!PacketIncreaseCheckLayers(p)) {
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return TM_ECODE_FAILED;
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}
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const VXLANHeader *vxlanh = (const VXLANHeader *)pkt;
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if ((vxlanh->flags[0] & 0x08) == 0 || vxlanh->res != 0)
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return TM_ECODE_FAILED;
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#if DEBUG
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uint32_t vni = (vxlanh->vni[0] << 16) + (vxlanh->vni[1] << 8) + (vxlanh->vni[2]);
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SCLogDebug("VXLAN vni %u", vni);
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#endif
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/* Increment stats counter for VXLAN packets */
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StatsIncr(tv, dtv->counter_vxlan);
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EthernetHdr *ethh = (EthernetHdr *)(pkt + VXLAN_HEADER_LEN);
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int decode_tunnel_proto = DECODE_TUNNEL_UNSET;
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/* Look at encapsulated Ethernet frame to get next protocol */
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uint16_t eth_type = SCNtohs(ethh->eth_type);
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SCLogDebug("VXLAN ethertype 0x%04x", eth_type);
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switch (eth_type) {
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case ETHERNET_TYPE_ARP:
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SCLogDebug("VXLAN found ARP");
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break;
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case ETHERNET_TYPE_IP:
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SCLogDebug("VXLAN found IPv4");
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decode_tunnel_proto = DECODE_TUNNEL_IPV4;
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break;
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case ETHERNET_TYPE_IPV6:
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SCLogDebug("VXLAN found IPv6");
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decode_tunnel_proto = DECODE_TUNNEL_IPV6;
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break;
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case ETHERNET_TYPE_VLAN:
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case ETHERNET_TYPE_8021AD:
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case ETHERNET_TYPE_8021QINQ:
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SCLogDebug("VXLAN found VLAN");
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decode_tunnel_proto = DECODE_TUNNEL_VLAN;
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break;
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default:
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SCLogDebug("VXLAN found unsupported Ethertype - expected IPv4, IPv6, VLAN, or ARP");
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ENGINE_SET_INVALID_EVENT(p, VXLAN_UNKNOWN_PAYLOAD_TYPE);
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}
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/* Set-up and process inner packet if it is a supported ethertype */
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if (decode_tunnel_proto != DECODE_TUNNEL_UNSET) {
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Packet *tp = PacketTunnelPktSetup(tv, dtv, p, pkt + VXLAN_HEADER_LEN + ETHERNET_HEADER_LEN,
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len - (VXLAN_HEADER_LEN + ETHERNET_HEADER_LEN), decode_tunnel_proto);
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if (tp != NULL) {
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PKT_SET_SRC(tp, PKT_SRC_DECODER_VXLAN);
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PacketEnqueueNoLock(&tv->decode_pq, tp);
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}
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}
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return TM_ECODE_OK;
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}
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#ifdef UNITTESTS
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/**
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* \test DecodeVXLANTest01 test a good vxlan header.
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* Contains a DNS request packet.
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*/
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static int DecodeVXLANtest01 (void)
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{
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uint8_t raw_vxlan[] = {
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0x12, 0xb5, 0x12, 0xb5, 0x00, 0x3a, 0x87, 0x51, /* UDP header */
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0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x25, 0x00, /* VXLAN header */
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0x10, 0x00, 0x00, 0x0c, 0x01, 0x00, /* inner destination MAC */
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0x00, 0x51, 0x52, 0xb3, 0x54, 0xe5, /* inner source MAC */
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0x08, 0x00, /* another IPv4 0x0800 */
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0x45, 0x00, 0x00, 0x1c, 0x00, 0x01, 0x00, 0x00, 0x40, 0x11,
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0x44, 0x45, 0x0a, 0x60, 0x00, 0x0a, 0xb9, 0x1b, 0x73, 0x06, /* IPv4 hdr */
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0x00, 0x35, 0x30, 0x39, 0x00, 0x08, 0x98, 0xe4 /* UDP probe src port 53 */
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};
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Packet *p = PacketGetFromAlloc();
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FAIL_IF_NULL(p);
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ThreadVars tv;
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DecodeThreadVars dtv;
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memset(&tv, 0, sizeof(ThreadVars));
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memset(&dtv, 0, sizeof(DecodeThreadVars));
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DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S);
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FlowInitConfig(FLOW_QUIET);
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DecodeUDP(&tv, &dtv, p, raw_vxlan, sizeof(raw_vxlan));
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FAIL_IF(p->udph == NULL);
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FAIL_IF(tv.decode_pq.top == NULL);
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Packet *tp = PacketDequeueNoLock(&tv.decode_pq);
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FAIL_IF(tp->udph == NULL);
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FAIL_IF_NOT(tp->sp == 53);
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FlowShutdown();
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PacketFree(p);
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PacketFreeOrRelease(tp);
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PASS;
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}
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/**
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* \test DecodeVXLANtest02 tests default port disabled by the config.
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*/
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static int DecodeVXLANtest02 (void)
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{
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uint8_t raw_vxlan[] = {
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0x12, 0xb5, 0x12, 0xb5, 0x00, 0x3a, 0x87, 0x51, /* UDP header */
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0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x25, 0x00, /* VXLAN header */
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0x10, 0x00, 0x00, 0x0c, 0x01, 0x00, /* inner destination MAC */
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0x00, 0x51, 0x52, 0xb3, 0x54, 0xe5, /* inner source MAC */
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0x08, 0x00, /* another IPv4 0x0800 */
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0x45, 0x00, 0x00, 0x1c, 0x00, 0x01, 0x00, 0x00, 0x40, 0x11,
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0x44, 0x45, 0x0a, 0x60, 0x00, 0x0a, 0xb9, 0x1b, 0x73, 0x06, /* IPv4 hdr */
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0x00, 0x35, 0x30, 0x39, 0x00, 0x08, 0x98, 0xe4 /* UDP probe src port 53 */
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};
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Packet *p = PacketGetFromAlloc();
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FAIL_IF_NULL(p);
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ThreadVars tv;
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DecodeThreadVars dtv;
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memset(&tv, 0, sizeof(ThreadVars));
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memset(&dtv, 0, sizeof(DecodeThreadVars));
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DecodeVXLANConfigPorts("1");
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FlowInitConfig(FLOW_QUIET);
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DecodeUDP(&tv, &dtv, p, raw_vxlan, sizeof(raw_vxlan));
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FAIL_IF(p->udph == NULL);
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FAIL_IF(tv.decode_pq.top != NULL);
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DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S); /* reset */
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FlowShutdown();
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PacketFree(p);
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PASS;
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}
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#endif /* UNITTESTS */
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void DecodeVXLANRegisterTests(void)
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{
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#ifdef UNITTESTS
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UtRegisterTest("DecodeVXLANtest01",
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DecodeVXLANtest01);
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UtRegisterTest("DecodeVXLANtest02",
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DecodeVXLANtest02);
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#endif /* UNITTESTS */
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}
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