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414 lines
12 KiB
C
414 lines
12 KiB
C
/* Copyright (C) 2007-2013 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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* \ingroup decode
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*
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* @{
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*/
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/**
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* \file
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*
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* \author Breno Silva <breno.silva@gmail.com>
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*
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* Decodes GRE
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*/
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#include "suricata-common.h"
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#include "suricata.h"
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#include "decode.h"
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#include "decode-events.h"
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#include "decode-gre.h"
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#include "util-unittest.h"
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#include "util-debug.h"
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/**
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* \brief Function to decode GRE packets
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*/
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int DecodeGRE(ThreadVars *tv, DecodeThreadVars *dtv, Packet *p, uint8_t *pkt, uint16_t len, PacketQueue *pq)
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{
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uint16_t header_len = GRE_HDR_LEN;
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GRESreHdr *gsre = NULL;
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StatsIncr(tv, dtv->counter_gre);
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if(len < GRE_HDR_LEN) {
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ENGINE_SET_INVALID_EVENT(p, GRE_PKT_TOO_SMALL);
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return TM_ECODE_FAILED;
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}
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p->greh = (GREHdr *)pkt;
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if(p->greh == NULL)
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return TM_ECODE_FAILED;
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SCLogDebug("p %p pkt %p GRE protocol %04x Len: %d GRE version %x",
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p, pkt, GRE_GET_PROTO(p->greh), len,GRE_GET_VERSION(p->greh));
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switch (GRE_GET_VERSION(p->greh))
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{
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case GRE_VERSION_0:
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/* GRE version 0 doenst support the fields below RFC 1701 */
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/**
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* \todo We need to make sure this does not allow bypassing
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* inspection. A server may just ignore these and
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* continue processing the packet, but we will not look
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* further into it.
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*/
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if (GRE_FLAG_ISSET_RECUR(p->greh)) {
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ENGINE_SET_INVALID_EVENT(p, GRE_VERSION0_RECUR);
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return TM_ECODE_OK;
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}
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if (GREV1_FLAG_ISSET_FLAGS(p->greh)) {
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ENGINE_SET_INVALID_EVENT(p, GRE_VERSION0_FLAGS);
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return TM_ECODE_OK;
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}
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/* Adjust header length based on content */
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if (GRE_FLAG_ISSET_KY(p->greh))
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header_len += GRE_KEY_LEN;
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if (GRE_FLAG_ISSET_SQ(p->greh))
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header_len += GRE_SEQ_LEN;
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if (GRE_FLAG_ISSET_CHKSUM(p->greh) || GRE_FLAG_ISSET_ROUTE(p->greh))
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header_len += GRE_CHKSUM_LEN + GRE_OFFSET_LEN;
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if (header_len > len) {
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ENGINE_SET_INVALID_EVENT(p, GRE_VERSION0_HDR_TOO_BIG);
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return TM_ECODE_OK;
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}
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if (GRE_FLAG_ISSET_ROUTE(p->greh))
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{
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while (1)
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{
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if ((header_len + GRE_SRE_HDR_LEN) > len) {
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ENGINE_SET_INVALID_EVENT(p,
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GRE_VERSION0_MALFORMED_SRE_HDR);
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return TM_ECODE_OK;
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}
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gsre = (GRESreHdr *)(pkt + header_len);
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header_len += GRE_SRE_HDR_LEN;
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if ((ntohs(gsre->af) == 0) && (gsre->sre_length == 0))
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break;
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header_len += gsre->sre_length;
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if (header_len > len) {
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ENGINE_SET_INVALID_EVENT(p,
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GRE_VERSION0_MALFORMED_SRE_HDR);
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return TM_ECODE_OK;
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}
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}
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}
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break;
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case GRE_VERSION_1:
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/* GRE version 1 doenst support the fields below RFC 1701 */
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/**
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* \todo We need to make sure this does not allow bypassing
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* inspection. A server may just ignore these and
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* continue processing the packet, but we will not look
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* further into it.
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*/
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if (GRE_FLAG_ISSET_CHKSUM(p->greh)) {
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ENGINE_SET_INVALID_EVENT(p,GRE_VERSION1_CHKSUM);
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return TM_ECODE_OK;
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}
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if (GRE_FLAG_ISSET_ROUTE(p->greh)) {
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ENGINE_SET_INVALID_EVENT(p,GRE_VERSION1_ROUTE);
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return TM_ECODE_OK;
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}
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if (GRE_FLAG_ISSET_SSR(p->greh)) {
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ENGINE_SET_INVALID_EVENT(p,GRE_VERSION1_SSR);
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return TM_ECODE_OK;
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}
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if (GRE_FLAG_ISSET_RECUR(p->greh)) {
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ENGINE_SET_INVALID_EVENT(p,GRE_VERSION1_RECUR);
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return TM_ECODE_OK;
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}
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if (GREV1_FLAG_ISSET_FLAGS(p->greh)) {
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ENGINE_SET_INVALID_EVENT(p,GRE_VERSION1_FLAGS);
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return TM_ECODE_OK;
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}
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if (GRE_GET_PROTO(p->greh) != GRE_PROTO_PPP) {
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ENGINE_SET_INVALID_EVENT(p,GRE_VERSION1_WRONG_PROTOCOL);
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return TM_ECODE_OK;
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}
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if (!(GRE_FLAG_ISSET_KY(p->greh))) {
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ENGINE_SET_INVALID_EVENT(p,GRE_VERSION1_NO_KEY);
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return TM_ECODE_OK;
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}
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header_len += GRE_KEY_LEN;
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/* Adjust header length based on content */
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if (GRE_FLAG_ISSET_SQ(p->greh))
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header_len += GRE_SEQ_LEN;
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if (GREV1_FLAG_ISSET_ACK(p->greh))
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header_len += GREV1_ACK_LEN;
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if (header_len > len) {
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ENGINE_SET_INVALID_EVENT(p, GRE_VERSION1_HDR_TOO_BIG);
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return TM_ECODE_OK;
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}
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break;
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default:
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ENGINE_SET_INVALID_EVENT(p, GRE_WRONG_VERSION);
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return TM_ECODE_OK;
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}
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switch (GRE_GET_PROTO(p->greh))
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{
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case ETHERNET_TYPE_IP:
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{
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if (pq != NULL) {
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Packet *tp = PacketTunnelPktSetup(tv, dtv, p, pkt + header_len,
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len - header_len, DECODE_TUNNEL_IPV4, pq);
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if (tp != NULL) {
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PKT_SET_SRC(tp, PKT_SRC_DECODER_GRE);
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PacketEnqueue(pq,tp);
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}
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}
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break;
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}
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case GRE_PROTO_PPP:
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{
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if (pq != NULL) {
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Packet *tp = PacketTunnelPktSetup(tv, dtv, p, pkt + header_len,
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len - header_len, DECODE_TUNNEL_PPP, pq);
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if (tp != NULL) {
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PKT_SET_SRC(tp, PKT_SRC_DECODER_GRE);
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PacketEnqueue(pq,tp);
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}
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}
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break;
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}
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case ETHERNET_TYPE_IPV6:
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{
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if (pq != NULL) {
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Packet *tp = PacketTunnelPktSetup(tv, dtv, p, pkt + header_len,
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len - header_len, DECODE_TUNNEL_IPV6, pq);
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if (tp != NULL) {
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PKT_SET_SRC(tp, PKT_SRC_DECODER_GRE);
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PacketEnqueue(pq,tp);
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}
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}
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break;
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}
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case ETHERNET_TYPE_VLAN:
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{
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if (pq != NULL) {
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Packet *tp = PacketTunnelPktSetup(tv, dtv, p, pkt + header_len,
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len - header_len, DECODE_TUNNEL_VLAN, pq);
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if (tp != NULL) {
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PKT_SET_SRC(tp, PKT_SRC_DECODER_GRE);
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PacketEnqueue(pq,tp);
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}
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}
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break;
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}
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case ETHERNET_TYPE_ERSPAN:
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{
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if (pq != NULL) {
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Packet *tp = PacketTunnelPktSetup(tv, dtv, p, pkt + header_len,
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len - header_len, DECODE_TUNNEL_ERSPAN, pq);
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if (tp != NULL) {
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PKT_SET_SRC(tp, PKT_SRC_DECODER_GRE);
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PacketEnqueue(pq,tp);
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}
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}
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break;
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}
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case ETHERNET_TYPE_BRIDGE:
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{
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if (pq != NULL) {
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Packet *tp = PacketTunnelPktSetup(tv, dtv, p, pkt + header_len,
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len - header_len, DECODE_TUNNEL_ETHERNET, pq);
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if (tp != NULL) {
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PKT_SET_SRC(tp, PKT_SRC_DECODER_GRE);
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PacketEnqueue(pq,tp);
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}
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}
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break;
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}
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default:
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return TM_ECODE_OK;
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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 DecodeGRETest01 is a test for small gre packet
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*/
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static int DecodeGREtest01 (void)
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{
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uint8_t raw_gre[] = { 0x00 ,0x6e ,0x62 };
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Packet *p = PacketGetFromAlloc();
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if (unlikely(p == NULL))
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return 0;
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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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DecodeGRE(&tv, &dtv, p, raw_gre, sizeof(raw_gre), NULL);
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if(ENGINE_ISSET_EVENT(p,GRE_PKT_TOO_SMALL)) {
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SCFree(p);
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return 1;
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}
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SCFree(p);
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return 0;
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}
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/**
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* \test DecodeGRETest02 is a test for wrong gre version
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*/
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static int DecodeGREtest02 (void)
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{
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uint8_t raw_gre[] = {
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0x00, 0x6e, 0x62, 0xac, 0x40, 0x00, 0x40, 0x2f,
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0xc2, 0xc7, 0x0a, 0x00, 0x00, 0x64, 0x0a, 0x00,
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0x00, 0x8a, 0x30, 0x01, 0x0b, 0x00, 0x4e, 0x00,
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0x00, 0x00, 0x18, 0x4a, 0x50, 0xff, 0x03, 0x00,
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0x21, 0x45, 0x00, 0x00, 0x4a, 0x00, 0x00, 0x40,
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0x00, 0x40, 0x11, 0x94, 0x22, 0x50, 0x7e, 0x2b,
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0x2d, 0xc2, 0x6d, 0x68, 0x68, 0x80, 0x0e, 0x00,
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0x35, 0x00, 0x36, 0x9f, 0x18, 0xdb, 0xc4, 0x01,
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0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x01, 0x03, 0x73, 0x31, 0x36, 0x09, 0x73, 0x69,
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0x74, 0x65, 0x6d, 0x65, 0x74, 0x65, 0x72, 0x03,
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0x63, 0x6f, 0x6d, 0x00, 0x00, 0x01, 0x00, 0x01,
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0x00, 0x00, 0x29, 0x10, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00 };
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Packet *p = PacketGetFromAlloc();
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if (unlikely(p == NULL))
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return 0;
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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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DecodeGRE(&tv, &dtv, p, raw_gre, sizeof(raw_gre), NULL);
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if(ENGINE_ISSET_EVENT(p,GRE_WRONG_VERSION)) {
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SCFree(p);
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return 1;
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}
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SCFree(p);
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return 0;
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}
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/**
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* \test DecodeGRETest03 is a test for valid gre packet
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*/
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static int DecodeGREtest03 (void)
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{
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uint8_t raw_gre[] = {
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0x00, 0x6e, 0x62, 0xac, 0x40, 0x00, 0x40, 0x2f,
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0xc2, 0xc7, 0x0a, 0x00, 0x00, 0x64, 0x0a, 0x00,
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0x00, 0x8a, 0x30, 0x01, 0x88, 0x0b, 0x00, 0x4e,
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0x00, 0x00, 0x00, 0x18, 0x4a, 0x50, 0xff, 0x03,
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0x00, 0x21, 0x45, 0x00, 0x00, 0x4a, 0x00, 0x00,
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0x40, 0x00, 0x40, 0x11, 0x94, 0x22, 0x50, 0x7e,
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0x2b, 0x2d, 0xc2, 0x6d, 0x68, 0x68, 0x80, 0x0e,
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0x00, 0x35, 0x00, 0x36, 0x9f, 0x18, 0xdb, 0xc4,
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0x01, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x01, 0x03, 0x73, 0x31, 0x36, 0x09, 0x73,
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0x69, 0x74, 0x65, 0x6d, 0x65, 0x74, 0x65, 0x72,
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0x03, 0x63, 0x6f, 0x6d, 0x00, 0x00, 0x01, 0x00,
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0x01, 0x00, 0x00, 0x29, 0x10, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00 };
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Packet *p = PacketGetFromAlloc();
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if (unlikely(p == NULL))
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return 0;
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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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DecodeGRE(&tv, &dtv, p, raw_gre, sizeof(raw_gre), NULL);
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if(p->greh == NULL) {
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SCFree(p);
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return 0;
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}
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SCFree(p);
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return 1;
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}
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#endif /* UNITTESTS */
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/**
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* \brief this function registers unit tests for GRE decoder
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*/
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void DecodeGRERegisterTests(void)
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{
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#ifdef UNITTESTS
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UtRegisterTest("DecodeGREtest01", DecodeGREtest01);
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UtRegisterTest("DecodeGREtest02", DecodeGREtest02);
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UtRegisterTest("DecodeGREtest03", DecodeGREtest03);
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#endif /* UNITTESTS */
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}
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/**
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* @}
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*/
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