suricata/src/decode-vxlan.c

/* Copyright (C) 2014 Open Information Security Foundation
 *
 * You can copy, redistribute or modify this Program under the terms of
 * the GNU General Public License version 2 as published by the Free
 * Software Foundation.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

/**
 * \file
 *
 * \author Henrik Kramshoej <hlk@kramse.org>
 *
 * VXLAN decoder.
 */

#include "suricata-common.h"
#include "decode.h"
#include "decode-vxlan.h"
#include "decode-events.h"
#include "decode-udp.h"

#include "decode-ethernet.h"

#include "flow.h"

#include "util-unittest.h"
#include "util-debug.h"

#include "pkt-var.h"
#include "util-profiling.h"
#include "host.h"

#define VXLAN_HEADER_LEN         8

static bool g_vxlan_enabled = true;

void DecodeVXLANConfig(void)
{
    int enabled = 0;
    if (ConfGetBool("decoder.vxlan.enabled", &enabled) == 1) {
        if (enabled) {
            g_vxlan_enabled = true;
        } else {
            g_vxlan_enabled = false;
        }
    }
}

static int DecodeVXLANPacket(ThreadVars *t, Packet *p, uint8_t *pkt, uint16_t len)
{
    if (unlikely(len < UDP_HEADER_LEN)) {
        ENGINE_SET_INVALID_EVENT(p, UDP_HLEN_TOO_SMALL);
        return -1;
    }

    p->udph = (UDPHdr *)pkt;

    SET_UDP_SRC_PORT(p,&p->sp);
    SET_UDP_DST_PORT(p,&p->dp);

    p->payload = pkt + UDP_HEADER_LEN;
    p->payload_len = len - UDP_HEADER_LEN;
    p->proto = IPPROTO_UDP;

    return 0;
}

int DecodeVXLAN(ThreadVars *tv, DecodeThreadVars *dtv, Packet *p, uint8_t *pkt,
        uint32_t len, PacketQueue *pq)
{
    if (!g_vxlan_enabled)
        return TM_ECODE_FAILED;

    /* Is this packet to short to contain an IPv4/IPv6 packet ? */
    if (len < IPV4_HEADER_LEN)
        return TM_ECODE_FAILED;

    int event = 0;

    if (unlikely(DecodeVXLANPacket(tv, p,pkt,len) < 0)) {
        p->udph = NULL;
        return TM_ECODE_FAILED;
    }
    StatsIncr(tv, dtv->counter_vxlan);

    SCLogDebug("VXLAN UDP sp: %" PRIu32 " -> dp: %" PRIu32 " - HLEN: %" PRIu32 " LEN: %" PRIu32 "",
            UDP_GET_SRC_PORT(p), UDP_GET_DST_PORT(p), UDP_HEADER_LEN, p->payload_len);

    /* VXLAN encapsulate Layer 2 in UDP, most likely IPv4 and IPv6  */

    p->ethh = (EthernetHdr *)(pkt + UDP_HEADER_LEN + VXLAN_HEADER_LEN);
    SCLogDebug("VXLAN Ethertype 0x%04x", SCNtohs(p->ethh->eth_type));
    /* Best guess at inner packet. */
    switch (SCNtohs(p->ethh->eth_type)) {
        case ETHERNET_TYPE_ARP:
            SCLogDebug("VXLAN found ARP");
            break;
        case ETHERNET_TYPE_IP:
            SCLogDebug("VXLAN found IPv4");
            /* DecodeIPV4(tv, dtv, p, pkt, len, pq); */
            break;
        case ETHERNET_TYPE_IPV6:
            SCLogDebug("VXLAN found IPv6");
            /* DecodeIPV6(tv, dtv, p, pkt, len, pq); */
            break;
        default:
            SCLogDebug("VXLAN found no known Ethertype - only checks for IPv4, IPv6, ARP");
            /* ENGINE_SET_INVALID_EVENT(p, VXLAN_UNKNOWN_PAYLOAD_TYPE);*/
            /* return TM_ECODE_OK; */
    }

    SCLogDebug("VXLAN trying to decode with Ethernet");
    DecodeEthernet(tv, dtv, p, pkt + UDP_HEADER_LEN + VXLAN_HEADER_LEN,
      len - UDP_HEADER_LEN - VXLAN_HEADER_LEN, pq);

    if (event) {
        ENGINE_SET_EVENT(p, event);
    }
    return TM_ECODE_OK;
}

#ifdef UNITTESTS

/**
 * \test DecodeVXLANTest01 test a good vxlan header.
 * Contains a DNS request packet
 *
 *  \retval 1 on success
 *  \retval 0 on failure
 */
static int DecodeVXLANtest01 (void)
{
    uint8_t raw_vxlan[] = {
        0x12, 0xb5, 0x12, 0xb5, 0x00, 0x3a, 0x87, 0x51, /* UDP header */
        0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x25, 0x00, /* VXLAN header */
        0x10, 0x00, 0x00, 0x0c, 0x01, 0x00, /* inner destination MAC */
        0x00, 0x51, 0x52, 0xb3, 0x54, 0xe5, /* inner source MAC */
        0x08, 0x00, /* wot another IPv4 0x0800 */
        0x45, 0x00, 0x00, 0x1c, 0x00, 0x01, 0x00, 0x00, 0x40, 0x11,
        0x44, 0x45, 0x0a, 0x60, 0x00, 0x0a, 0xb9, 0x1b, 0x73, 0x06,  /* IPv4 hdr */
        0x00, 0x35, 0x30, 0x39, 0x00, 0x08, 0x98, 0xe4 /* UDP probe src port 53 */
    };
    Packet *p = PacketGetFromAlloc();
    FAIL_IF_NULL(p);
    ThreadVars tv;
    DecodeThreadVars dtv;

    memset(&tv, 0, sizeof(ThreadVars));
    memset(p, 0, SIZE_OF_PACKET);
    memset(&dtv, 0, sizeof(DecodeThreadVars));

    FlowInitConfig(FLOW_QUIET);
    DecodeVXLAN(&tv, &dtv, p, raw_vxlan, sizeof(raw_vxlan), NULL);

    FAIL_IF(p->udph == NULL);

    PACKET_RECYCLE(p);
    FlowShutdown();
    SCFree(p);
    PASS;
}
#endif /* UNITTESTS */

void DecodeVXLANRegisterTests(void)
{
#ifdef UNITTESTS
    UtRegisterTest("DecodeVXLANtest01",
                   DecodeVXLANtest01);
#endif /* UNITTESTS */
}