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/* Copyright (C) 2019-2021 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 tunneling scheme decoder.
*
* This implementation is based on the following specification doc:
* https://tools.ietf.org/html/draft-mahalingam-dutt-dcops-vxlan-00
*/
#include "suricata-common.h"
#include "decode.h"
#include "decode-vxlan.h"
#include "decode-events.h"
#include "detect.h"
#include "detect-engine-port.h"
#include "flow.h"
#include "util-validate.h"
#include "util-unittest.h"
#include "util-debug.h"
#define VXLAN_HEADER_LEN sizeof(VXLANHeader)
#define VXLAN_MAX_PORTS 4
#define VXLAN_UNSET_PORT -1
#define VXLAN_DEFAULT_PORT 4789
#define VXLAN_DEFAULT_PORT_S "4789"
static bool g_vxlan_enabled = true;
static int g_vxlan_ports_idx = 0;
static int g_vxlan_ports[VXLAN_MAX_PORTS] = { VXLAN_DEFAULT_PORT, VXLAN_UNSET_PORT,
VXLAN_UNSET_PORT, VXLAN_UNSET_PORT };
typedef struct VXLANHeader_ {
uint8_t flags[2];
uint16_t gdp;
uint8_t vni[3];
uint8_t res;
} VXLANHeader;
bool DecodeVXLANEnabledForPort(const uint16_t sp, const uint16_t dp)
{
SCLogDebug("ports %u->%u ports %d %d %d %d", sp, dp, g_vxlan_ports[0], g_vxlan_ports[1],
g_vxlan_ports[2], g_vxlan_ports[3]);
if (g_vxlan_enabled) {
for (int i = 0; i < g_vxlan_ports_idx; i++) {
if (g_vxlan_ports[i] == VXLAN_UNSET_PORT)
return false;
const int port = g_vxlan_ports[i];
if (port == (const int)sp || port == (const int)dp)
return true;
}
}
return false;
}
static void DecodeVXLANConfigPorts(const char *pstr)
{
SCLogDebug("parsing \'%s\'", pstr);
DetectPort *head = NULL;
DetectPortParse(NULL, &head, pstr);
g_vxlan_ports_idx = 0;
for (DetectPort *p = head; p != NULL; p = p->next) {
if (g_vxlan_ports_idx >= VXLAN_MAX_PORTS) {
SCLogWarning("more than %d VXLAN ports defined", VXLAN_MAX_PORTS);
break;
}
g_vxlan_ports[g_vxlan_ports_idx++] = (int)p->port;
}
DetectPortCleanupList(NULL, head);
}
void DecodeVXLANConfig(void)
{
int enabled = 0;
if (ConfGetBool("decoder.vxlan.enabled", &enabled) == 1) {
if (enabled) {
g_vxlan_enabled = true;
} else {
g_vxlan_enabled = false;
}
}
if (g_vxlan_enabled) {
ConfNode *node = ConfGetNode("decoder.vxlan.ports");
if (node && node->val) {
DecodeVXLANConfigPorts(node->val);
} else {
DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S);
}
}
}
/** \param pkt payload data directly above UDP header
* \param len length in bytes of pkt
*/
int DecodeVXLAN(ThreadVars *tv, DecodeThreadVars *dtv, Packet *p,
const uint8_t *pkt, uint32_t len)
{
DEBUG_VALIDATE_BUG_ON(pkt == NULL);
/* Initial packet validation */
if (unlikely(!g_vxlan_enabled))
return TM_ECODE_FAILED;
if (len < (VXLAN_HEADER_LEN + sizeof(EthernetHdr)))
return TM_ECODE_FAILED;
if (!PacketIncreaseCheckLayers(p)) {
return TM_ECODE_FAILED;
}
const VXLANHeader *vxlanh = (const VXLANHeader *)pkt;
if ((vxlanh->flags[0] & 0x08) == 0 || vxlanh->res != 0)
return TM_ECODE_FAILED;
#if DEBUG
uint32_t vni = (vxlanh->vni[0] << 16) + (vxlanh->vni[1] << 8) + (vxlanh->vni[2]);
SCLogDebug("VXLAN vni %u", vni);
#endif
/* Increment stats counter for VXLAN packets */
StatsIncr(tv, dtv->counter_vxlan);
EthernetHdr *ethh = (EthernetHdr *)(pkt + VXLAN_HEADER_LEN);
int decode_tunnel_proto = DECODE_TUNNEL_UNSET;
/* Look at encapsulated Ethernet frame to get next protocol */
uint16_t eth_type = SCNtohs(ethh->eth_type);
SCLogDebug("VXLAN ethertype 0x%04x", eth_type);
switch (eth_type) {
case ETHERNET_TYPE_ARP:
SCLogDebug("VXLAN found ARP");
break;
case ETHERNET_TYPE_IP:
SCLogDebug("VXLAN found IPv4");
decode_tunnel_proto = DECODE_TUNNEL_IPV4;
break;
case ETHERNET_TYPE_IPV6:
SCLogDebug("VXLAN found IPv6");
decode_tunnel_proto = DECODE_TUNNEL_IPV6;
break;
case ETHERNET_TYPE_VLAN:
case ETHERNET_TYPE_8021AD:
case ETHERNET_TYPE_8021QINQ:
SCLogDebug("VXLAN found VLAN");
decode_tunnel_proto = DECODE_TUNNEL_VLAN;
break;
default:
SCLogDebug("VXLAN found unsupported Ethertype - expected IPv4, IPv6, VLAN, or ARP");
ENGINE_SET_INVALID_EVENT(p, VXLAN_UNKNOWN_PAYLOAD_TYPE);
}
/* Set-up and process inner packet if it is a supported ethertype */
if (decode_tunnel_proto != DECODE_TUNNEL_UNSET) {
Packet *tp = PacketTunnelPktSetup(tv, dtv, p, pkt + VXLAN_HEADER_LEN + ETHERNET_HEADER_LEN,
len - (VXLAN_HEADER_LEN + ETHERNET_HEADER_LEN), decode_tunnel_proto);
if (tp != NULL) {
PKT_SET_SRC(tp, PKT_SRC_DECODER_VXLAN);
PacketEnqueueNoLock(&tv->decode_pq, tp);
}
}
return TM_ECODE_OK;
}
#ifdef UNITTESTS
/**
* \test DecodeVXLANTest01 test a good vxlan header.
* Contains a DNS request packet.
*/
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, /* 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(&dtv, 0, sizeof(DecodeThreadVars));
DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S);
FlowInitConfig(FLOW_QUIET);
DecodeUDP(&tv, &dtv, p, raw_vxlan, sizeof(raw_vxlan));
FAIL_IF(p->udph == NULL);
FAIL_IF(tv.decode_pq.top == NULL);
Packet *tp = PacketDequeueNoLock(&tv.decode_pq);
FAIL_IF(tp->udph == NULL);
FAIL_IF_NOT(tp->sp == 53);
FlowShutdown();
PacketFree(p);
PacketFreeOrRelease(tp);
PASS;
}
/**
* \test DecodeVXLANtest02 tests default port disabled by the config.
*/
static int DecodeVXLANtest02 (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, /* 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(&dtv, 0, sizeof(DecodeThreadVars));
DecodeVXLANConfigPorts("1");
FlowInitConfig(FLOW_QUIET);
DecodeUDP(&tv, &dtv, p, raw_vxlan, sizeof(raw_vxlan));
FAIL_IF(p->udph == NULL);
FAIL_IF(tv.decode_pq.top != NULL);
DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S); /* reset */
FlowShutdown();
PacketFree(p);
PASS;
}
#endif /* UNITTESTS */
void DecodeVXLANRegisterTests(void)
{
#ifdef UNITTESTS
UtRegisterTest("DecodeVXLANtest01",
DecodeVXLANtest01);
UtRegisterTest("DecodeVXLANtest02",
DecodeVXLANtest02);
#endif /* UNITTESTS */
}
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