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/* Copyright (C) 2020-2021 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.
*/
/**
* \ingroup decode
*
* @{
*/
/**
* \file
*
* \author Carl Smith <carl.smith@alliedtelesis.co.nz>
*
* Decodes Network Service Header (NSH)
*/
#include "suricata-common.h"
#include "suricata.h"
#include "decode.h"
#include "decode-events.h"
#include "decode-nsh.h"
#include "util-validate.h"
#include "util-unittest.h"
#include "util-debug.h"
/**
* \brief Function to decode NSH packets
*/
int DecodeNSH(ThreadVars *tv, DecodeThreadVars *dtv, Packet *p, const uint8_t *pkt, uint32_t len)
{
DEBUG_VALIDATE_BUG_ON(pkt == NULL);
StatsIncr(tv, dtv->counter_nsh);
/* Check minimum header size */
if (len < sizeof(NshHdr)) {
ENGINE_SET_INVALID_EVENT(p, NSH_HEADER_TOO_SMALL);
return TM_ECODE_FAILED;
}
if (!PacketIncreaseCheckLayers(p)) {
return TM_ECODE_FAILED;
}
/* Sanity check the header version */
const NshHdr *hdr = (const NshHdr *)pkt;
uint16_t version = SCNtohs(hdr->ver_flags_len) >> 14;
if (version != 0) {
ENGINE_SET_EVENT(p, NSH_UNSUPPORTED_VERSION);
return TM_ECODE_OK;
}
/* Should always be some data after the header */
uint16_t length = (SCNtohs(hdr->ver_flags_len) & 0x003f) * 4;
if (length >= len) {
ENGINE_SET_INVALID_EVENT(p, NSH_BAD_HEADER_LENGTH);
return TM_ECODE_FAILED;
}
/* Check for valid MD types */
uint8_t md_type = hdr->md_type;
if (md_type == 0 || md_type == 0xF) {
/* We should silently ignore these packets */
ENGINE_SET_EVENT(p, NSH_RESERVED_TYPE);
return TM_ECODE_OK;
} else if (md_type == 1) {
/* Fixed header length format */
if (length != 24) {
ENGINE_SET_INVALID_EVENT(p, NSH_BAD_HEADER_LENGTH);
return TM_ECODE_FAILED;
}
} else if (md_type != 2) {
/* Not variable header length either */
ENGINE_SET_EVENT(p, NSH_UNSUPPORTED_TYPE);
return TM_ECODE_OK;
}
/* Now we can safely read the rest of the header */
uint8_t next_protocol = hdr->next_protocol;
#ifdef DEBUG
if (SCLogDebugEnabled()) {
uint32_t spi_si = SCNtohl(hdr->spi_si);
uint32_t spi = ((spi_si & 0xFFFFFF00) >> 8);
uint8_t si = (uint8_t)(spi_si & 0xFF);
SCLogDebug("NSH: version %u length %u spi %u si %u next_protocol %u", version, length, spi,
si, next_protocol);
}
#endif /* DEBUG */
/* Try to decode the payload */
switch (next_protocol) {
case NSH_NEXT_PROTO_IPV4:
if (len - length > USHRT_MAX) {
return TM_ECODE_FAILED;
}
return DecodeIPV4(tv, dtv, p, pkt + length, (uint16_t)(len - length));
case NSH_NEXT_PROTO_IPV6:
if (len - length > USHRT_MAX) {
return TM_ECODE_FAILED;
}
return DecodeIPV6(tv, dtv, p, pkt + length, (uint16_t)(len - length));
case NSH_NEXT_PROTO_ETHERNET:
return DecodeEthernet(tv, dtv, p, pkt + length, len - length);
case NSH_NEXT_PROTO_MPLS:
return DecodeMPLS(tv, dtv, p, pkt + length, len - length);
case NSH_NEXT_PROTO_NSH:
default:
SCLogDebug("NSH next protocol %u not supported", next_protocol);
ENGINE_SET_EVENT(p, NSH_UNKNOWN_PAYLOAD);
break;
}
return TM_ECODE_OK;
}
#ifdef UNITTESTS
static uint8_t valid_nsh_packet[] = { 0x00, 0x04, 0x02, 0x01, 0x00, 0x00, 0x02, 0x02, 0x45, 0x10,
0x00, 0x3c, 0x78, 0x8f, 0x40, 0x00, 0x3f, 0x06, 0x79, 0x05, 0x0b, 0x06, 0x06, 0x06, 0x33, 0x06,
0x06, 0x06, 0xbd, 0x2e, 0x00, 0x16, 0xc9, 0xee, 0x07, 0x62, 0x00, 0x00, 0x00, 0x00, 0xa0, 0x02,
0x16, 0xd0, 0x2f, 0x36, 0x00, 0x00, 0x02, 0x04, 0x05, 0xb4, 0x04, 0x02, 0x08, 0x0a, 0xa9, 0x5f,
0x7f, 0xed, 0x00, 0x00, 0x00, 0x00, 0x01, 0x03, 0x03, 0x07 };
static int DecodeNSHTestHeaderTooSmall(void)
{
ThreadVars tv;
DecodeThreadVars dtv;
Packet *p;
p = PacketGetFromAlloc();
FAIL_IF_NULL(p);
memset(&dtv, 0, sizeof(DecodeThreadVars));
memset(&tv, 0, sizeof(ThreadVars));
/* A packet that is too small to have a complete NSH header */
DecodeNSH(&tv, &dtv, p, valid_nsh_packet, 7);
FAIL_IF_NOT(ENGINE_ISSET_EVENT(p, NSH_HEADER_TOO_SMALL));
SCFree(p);
PASS;
}
static int DecodeNSHTestUnsupportedVersion(void)
{
ThreadVars tv;
DecodeThreadVars dtv;
Packet *p;
p = PacketGetFromAlloc();
FAIL_IF_NULL(p);
memset(&dtv, 0, sizeof(DecodeThreadVars));
memset(&tv, 0, sizeof(ThreadVars));
/* Non-zero version field */
valid_nsh_packet[0] = 0xFF;
DecodeNSH(&tv, &dtv, p, valid_nsh_packet, sizeof(valid_nsh_packet));
valid_nsh_packet[0] = 0x00;
FAIL_IF_NOT(ENGINE_ISSET_EVENT(p, NSH_UNSUPPORTED_VERSION));
SCFree(p);
PASS;
}
static int DecodeNSHTestPacketTooSmall(void)
{
ThreadVars tv;
DecodeThreadVars dtv;
Packet *p;
p = PacketGetFromAlloc();
FAIL_IF_NULL(p);
memset(&dtv, 0, sizeof(DecodeThreadVars));
memset(&tv, 0, sizeof(ThreadVars));
/* A packet that has no payload */
DecodeNSH(&tv, &dtv, p, valid_nsh_packet, 8);
FAIL_IF_NOT(ENGINE_ISSET_EVENT(p, NSH_BAD_HEADER_LENGTH));
SCFree(p);
PASS;
}
static int DecodeNSHTestReservedType(void)
{
ThreadVars tv;
DecodeThreadVars dtv;
Packet *p;
p = PacketGetFromAlloc();
FAIL_IF_NULL(p);
memset(&dtv, 0, sizeof(DecodeThreadVars));
memset(&tv, 0, sizeof(ThreadVars));
/* Reserved type */
valid_nsh_packet[2] = 0x00;
DecodeNSH(&tv, &dtv, p, valid_nsh_packet, sizeof(valid_nsh_packet));
valid_nsh_packet[2] = 0x02;
FAIL_IF_NOT(ENGINE_ISSET_EVENT(p, NSH_RESERVED_TYPE));
SCFree(p);
PASS;
}
static int DecodeNSHTestInvalidType(void)
{
ThreadVars tv;
DecodeThreadVars dtv;
Packet *p;
p = PacketGetFromAlloc();
FAIL_IF_NULL(p);
memset(&dtv, 0, sizeof(DecodeThreadVars));
memset(&tv, 0, sizeof(ThreadVars));
/* Type length mismatch */
valid_nsh_packet[2] = 0x01;
DecodeNSH(&tv, &dtv, p, valid_nsh_packet, sizeof(valid_nsh_packet));
valid_nsh_packet[2] = 0x02;
FAIL_IF_NOT(ENGINE_ISSET_EVENT(p, NSH_BAD_HEADER_LENGTH));
SCFree(p);
PASS;
}
static int DecodeNSHTestUnsupportedType(void)
{
ThreadVars tv;
DecodeThreadVars dtv;
Packet *p;
p = PacketGetFromAlloc();
FAIL_IF_NULL(p);
memset(&dtv, 0, sizeof(DecodeThreadVars));
memset(&tv, 0, sizeof(ThreadVars));
/* Unsupported type */
valid_nsh_packet[2] = 0x03;
DecodeNSH(&tv, &dtv, p, valid_nsh_packet, sizeof(valid_nsh_packet));
valid_nsh_packet[2] = 0x02;
FAIL_IF_NOT(ENGINE_ISSET_EVENT(p, NSH_UNSUPPORTED_TYPE));
SCFree(p);
PASS;
}
static int DecodeNSHTestUnknownPayload(void)
{
ThreadVars tv;
DecodeThreadVars dtv;
Packet *p;
p = PacketGetFromAlloc();
FAIL_IF_NULL(p);
memset(&dtv, 0, sizeof(DecodeThreadVars));
memset(&tv, 0, sizeof(ThreadVars));
/* Unknown type */
valid_nsh_packet[3] = 0x99;
DecodeNSH(&tv, &dtv, p, valid_nsh_packet, sizeof(valid_nsh_packet));
valid_nsh_packet[3] = 0x01;
FAIL_IF_NOT(ENGINE_ISSET_EVENT(p, NSH_UNKNOWN_PAYLOAD));
SCFree(p);
PASS;
}
#endif /* UNITTESTS */
void DecodeNSHRegisterTests(void)
{
#ifdef UNITTESTS
UtRegisterTest("DecodeNSHTestHeaderTooSmall", DecodeNSHTestHeaderTooSmall);
UtRegisterTest("DecodeNSHTestUnsupportedVersion", DecodeNSHTestUnsupportedVersion);
UtRegisterTest("DecodeNSHTestPacketTooSmall", DecodeNSHTestPacketTooSmall);
UtRegisterTest("DecodeNSHTestReservedType", DecodeNSHTestReservedType);
UtRegisterTest("DecodeNSHTestInvalidType", DecodeNSHTestInvalidType);
UtRegisterTest("DecodeNSHTestUnsupportedType", DecodeNSHTestUnsupportedType);
UtRegisterTest("DecodeNSHTestUnknownPayload", DecodeNSHTestUnknownPayload);
#endif /* UNITTESTS */
}
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