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suricata/src/decode-tcp.c

549 lines
18 KiB
C

/* Copyright (C) 2007-2024 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 Victor Julien <victor@inliniac.net>
*
* Decode TCP
*/
#include "suricata-common.h"
#include "decode-tcp.h"
#include "decode.h"
#include "decode-events.h"
#include "util-unittest.h"
#include "util-debug.h"
#include "util-optimize.h"
#include "flow.h"
static void DecodeTCPOptions(Packet *p, const uint8_t *pkt, uint16_t pktlen)
{
uint8_t tcp_opt_cnt = 0;
TCPOpt tcp_opts[TCP_OPTMAX];
const TCPHdr *tcph = PacketGetTCP(p);
uint16_t plen = pktlen;
while (plen)
{
const uint8_t type = *pkt;
/* single byte options */
if (type == TCP_OPT_EOL) {
break;
} else if (type == TCP_OPT_NOP) {
pkt++;
plen--;
/* multibyte options */
} else {
if (plen < 2) {
break;
}
const uint8_t olen = *(pkt+1);
/* we already know that the total options len is valid,
* so here the len of the specific option must be bad.
* Also check for invalid lengths 0 and 1. */
if (unlikely(olen > plen || olen < 2)) {
ENGINE_SET_INVALID_EVENT(p, TCP_OPT_INVALID_LEN);
return;
}
tcp_opts[tcp_opt_cnt].type = type;
tcp_opts[tcp_opt_cnt].len = olen;
tcp_opts[tcp_opt_cnt].data = (olen > 2) ? (pkt+2) : NULL;
/* we are parsing the most commonly used opts to prevent
* us from having to walk the opts list for these all the
* time. */
switch (type) {
case TCP_OPT_WS:
if (olen != TCP_OPT_WS_LEN) {
ENGINE_SET_EVENT(p,TCP_OPT_INVALID_LEN);
} else {
if (p->l4.vars.tcp.wscale_set != 0) {
ENGINE_SET_EVENT(p,TCP_OPT_DUPLICATE);
} else {
p->l4.vars.tcp.wscale_set = 1;
const uint8_t wscale = *(tcp_opts[tcp_opt_cnt].data);
if (wscale <= TCP_WSCALE_MAX) {
p->l4.vars.tcp.wscale = wscale;
} else {
p->l4.vars.tcp.wscale = 0;
}
}
}
break;
case TCP_OPT_MSS:
if (olen != TCP_OPT_MSS_LEN) {
ENGINE_SET_EVENT(p,TCP_OPT_INVALID_LEN);
} else {
if (p->l4.vars.tcp.mss_set) {
ENGINE_SET_EVENT(p,TCP_OPT_DUPLICATE);
} else {
p->l4.vars.tcp.mss_set = true;
p->l4.vars.tcp.mss = SCNtohs(*(uint16_t *)(tcp_opts[tcp_opt_cnt].data));
}
}
break;
case TCP_OPT_SACKOK:
if (olen != TCP_OPT_SACKOK_LEN) {
ENGINE_SET_EVENT(p,TCP_OPT_INVALID_LEN);
} else {
if (TCP_GET_SACKOK(p)) {
ENGINE_SET_EVENT(p,TCP_OPT_DUPLICATE);
} else {
p->l4.vars.tcp.sack_ok = true;
}
}
break;
case TCP_OPT_TS:
if (olen != TCP_OPT_TS_LEN) {
ENGINE_SET_EVENT(p,TCP_OPT_INVALID_LEN);
} else {
if (p->l4.vars.tcp.ts_set) {
ENGINE_SET_EVENT(p,TCP_OPT_DUPLICATE);
} else {
uint32_t values[2];
memcpy(&values, tcp_opts[tcp_opt_cnt].data, sizeof(values));
p->l4.vars.tcp.ts_val = SCNtohl(values[0]);
p->l4.vars.tcp.ts_ecr = SCNtohl(values[1]);
p->l4.vars.tcp.ts_set = true;
}
}
break;
case TCP_OPT_SACK:
SCLogDebug("SACK option, len %u", olen);
if (olen == 2) {
/* useless, but common empty SACK record */
} else if (olen < TCP_OPT_SACK_MIN_LEN || olen > TCP_OPT_SACK_MAX_LEN ||
!((olen - 2) % 8 == 0)) {
ENGINE_SET_EVENT(p, TCP_OPT_INVALID_LEN);
} else {
if (p->l4.vars.tcp.sack_set) {
ENGINE_SET_EVENT(p,TCP_OPT_DUPLICATE);
} else {
ptrdiff_t diff = tcp_opts[tcp_opt_cnt].data - (uint8_t *)tcph;
DEBUG_VALIDATE_BUG_ON(diff > UINT16_MAX);
p->l4.vars.tcp.sack_set = true;
p->l4.vars.tcp.sack_cnt = (olen - 2) / 8;
p->l4.vars.tcp.sack_offset = (uint16_t)diff;
}
}
break;
case TCP_OPT_TFO:
SCLogDebug("TFO option, len %u", olen);
if ((olen != 2) && (olen < TCP_OPT_TFO_MIN_LEN || olen > TCP_OPT_TFO_MAX_LEN ||
!(((olen - 2) & 0x1) == 0))) {
ENGINE_SET_EVENT(p,TCP_OPT_INVALID_LEN);
} else {
if (p->l4.vars.tcp.tfo_set) {
ENGINE_SET_EVENT(p,TCP_OPT_DUPLICATE);
} else {
p->l4.vars.tcp.tfo_set = true;
}
}
break;
/* experimental options, could be TFO */
case TCP_OPT_EXP1:
case TCP_OPT_EXP2:
SCLogDebug("TCP EXP option, len %u", olen);
if (olen == 4 || olen == 12) {
uint16_t magic = SCNtohs(*(uint16_t *)tcp_opts[tcp_opt_cnt].data);
if (magic == 0xf989) {
if (p->l4.vars.tcp.tfo_set) {
ENGINE_SET_EVENT(p,TCP_OPT_DUPLICATE);
} else {
p->l4.vars.tcp.tfo_set = true;
}
}
} else {
ENGINE_SET_EVENT(p,TCP_OPT_INVALID_LEN);
}
break;
/* RFC 2385 MD5 option */
case TCP_OPT_MD5:
SCLogDebug("MD5 option, len %u", olen);
if (olen != 18) {
ENGINE_SET_INVALID_EVENT(p,TCP_OPT_INVALID_LEN);
} else {
/* we can't validate the option as the key is out of band */
p->l4.vars.tcp.md5_option_present = true;
}
break;
/* RFC 5925 AO option */
case TCP_OPT_AO:
SCLogDebug("AU option, len %u", olen);
if (olen < 4) {
ENGINE_SET_INVALID_EVENT(p,TCP_OPT_INVALID_LEN);
} else {
/* we can't validate the option as the key is out of band */
p->l4.vars.tcp.ao_option_present = true;
}
break;
}
pkt += olen;
plen -= olen;
tcp_opt_cnt++;
}
}
}
static int DecodeTCPPacket(
ThreadVars *tv, DecodeThreadVars *dtv, Packet *p, const uint8_t *pkt, uint16_t len)
{
if (unlikely(len < TCP_HEADER_LEN)) {
ENGINE_SET_INVALID_EVENT(p, TCP_PKT_TOO_SMALL);
return -1;
}
TCPHdr *tcph = PacketSetTCP(p, pkt);
uint8_t hlen = TCP_GET_RAW_HLEN(tcph);
if (unlikely(len < hlen)) {
ENGINE_SET_INVALID_EVENT(p, TCP_HLEN_TOO_SMALL);
return -1;
}
uint8_t tcp_opt_len = hlen - TCP_HEADER_LEN;
if (unlikely(tcp_opt_len > TCP_OPTLENMAX)) {
ENGINE_SET_INVALID_EVENT(p, TCP_INVALID_OPTLEN);
return -1;
}
if (likely(tcp_opt_len > 0)) {
DecodeTCPOptions(p, pkt + TCP_HEADER_LEN, tcp_opt_len);
}
p->sp = TCP_GET_RAW_SRC_PORT(tcph);
p->dp = TCP_GET_RAW_DST_PORT(tcph);
p->proto = IPPROTO_TCP;
p->payload = (uint8_t *)pkt + hlen;
p->payload_len = len - hlen;
/* update counters */
if ((tcph->th_flags & (TH_SYN | TH_ACK)) == (TH_SYN | TH_ACK)) {
StatsIncr(tv, dtv->counter_tcp_synack);
} else if (tcph->th_flags & (TH_SYN)) {
StatsIncr(tv, dtv->counter_tcp_syn);
}
if (tcph->th_flags & (TH_RST)) {
StatsIncr(tv, dtv->counter_tcp_rst);
}
#ifdef DEBUG
SCLogDebug("TCP sp: %u -> dp: %u - HLEN: %" PRIu32 " LEN: %" PRIu32 " %s%s%s%s%s%s", p->sp,
p->dp, TCP_GET_RAW_HLEN(tcph), len, TCP_GET_SACKOK(p) ? "SACKOK " : "",
TCP_HAS_SACK(p) ? "SACK " : "", TCP_HAS_WSCALE(p) ? "WS " : "",
TCP_HAS_TS(p) ? "TS " : "", TCP_HAS_MSS(p) ? "MSS " : "", TCP_HAS_TFO(p) ? "TFO " : "");
#endif
return 0;
}
int DecodeTCP(ThreadVars *tv, DecodeThreadVars *dtv, Packet *p, const uint8_t *pkt, uint16_t len)
{
StatsIncr(tv, dtv->counter_tcp);
if (unlikely(DecodeTCPPacket(tv, dtv, p, pkt, len) < 0)) {
SCLogDebug("invalid TCP packet");
PacketClearL4(p);
return TM_ECODE_FAILED;
}
FlowSetupPacket(p);
return TM_ECODE_OK;
}
#ifdef UNITTESTS
#include "util-unittest-helper.h"
#include "packet.h"
static int TCPCalculateValidChecksumtest01(void)
{
uint16_t csum = 0;
uint8_t raw_ipshdr[] = {
0x40, 0x8e, 0x7e, 0xb2, 0xc0, 0xa8, 0x01, 0x03};
uint8_t raw_tcp[] = {
0x00, 0x50, 0x8e, 0x16, 0x0d, 0x59, 0xcd, 0x3c,
0xcf, 0x0d, 0x21, 0x80, 0xa0, 0x12, 0x16, 0xa0,
0xfa, 0x03, 0x00, 0x00, 0x02, 0x04, 0x05, 0xb4,
0x04, 0x02, 0x08, 0x0a, 0x6e, 0x18, 0x78, 0x73,
0x01, 0x71, 0x74, 0xde, 0x01, 0x03, 0x03, 02};
csum = *( ((uint16_t *)raw_tcp) + 8);
FAIL_IF(TCPChecksum((uint16_t *)raw_ipshdr,
(uint16_t *)raw_tcp, sizeof(raw_tcp), csum) != 0);
PASS;
}
static int TCPCalculateInvalidChecksumtest02(void)
{
uint16_t csum = 0;
uint8_t raw_ipshdr[] = {
0x40, 0x8e, 0x7e, 0xb2, 0xc0, 0xa8, 0x01, 0x03};
uint8_t raw_tcp[] = {
0x00, 0x50, 0x8e, 0x16, 0x0d, 0x59, 0xcd, 0x3c,
0xcf, 0x0d, 0x21, 0x80, 0xa0, 0x12, 0x16, 0xa0,
0xfa, 0x03, 0x00, 0x00, 0x02, 0x04, 0x05, 0xb4,
0x04, 0x02, 0x08, 0x0a, 0x6e, 0x18, 0x78, 0x73,
0x01, 0x71, 0x74, 0xde, 0x01, 0x03, 0x03, 03};
csum = *( ((uint16_t *)raw_tcp) + 8);
FAIL_IF(TCPChecksum((uint16_t *) raw_ipshdr,
(uint16_t *)raw_tcp, sizeof(raw_tcp), csum) == 0);
PASS;
}
static int TCPV6CalculateValidChecksumtest03(void)
{
uint16_t csum = 0;
static uint8_t raw_ipv6[] = {
0x00, 0x60, 0x97, 0x07, 0x69, 0xea, 0x00, 0x00,
0x86, 0x05, 0x80, 0xda, 0x86, 0xdd, 0x60, 0x00,
0x00, 0x00, 0x00, 0x20, 0x06, 0x40, 0x3f, 0xfe,
0x05, 0x07, 0x00, 0x00, 0x00, 0x01, 0x02, 0x00,
0x86, 0xff, 0xfe, 0x05, 0x80, 0xda, 0x3f, 0xfe,
0x05, 0x01, 0x04, 0x10, 0x00, 0x00, 0x02, 0xc0,
0xdf, 0xff, 0xfe, 0x47, 0x03, 0x3e, 0x03, 0xfe,
0x00, 0x16, 0xd6, 0x76, 0xf5, 0x2d, 0x0c, 0x7a,
0x08, 0x77, 0x80, 0x10, 0x21, 0x5c, 0xc2, 0xf1,
0x00, 0x00, 0x01, 0x01, 0x08, 0x0a, 0x00, 0x08,
0xca, 0x5a, 0x00, 0x01, 0x69, 0x27};
csum = *( ((uint16_t *)(raw_ipv6 + 70)));
FAIL_IF(TCPV6Checksum((uint16_t *)(raw_ipv6 + 14 + 8),
(uint16_t *)(raw_ipv6 + 54), 32, csum) != 0);
PASS;
}
static int TCPV6CalculateInvalidChecksumtest04(void)
{
uint16_t csum = 0;
static uint8_t raw_ipv6[] = {
0x00, 0x60, 0x97, 0x07, 0x69, 0xea, 0x00, 0x00,
0x86, 0x05, 0x80, 0xda, 0x86, 0xdd, 0x60, 0x00,
0x00, 0x00, 0x00, 0x20, 0x06, 0x40, 0x3f, 0xfe,
0x05, 0x07, 0x00, 0x00, 0x00, 0x01, 0x02, 0x00,
0x86, 0xff, 0xfe, 0x05, 0x80, 0xda, 0x3f, 0xfe,
0x05, 0x01, 0x04, 0x10, 0x00, 0x00, 0x02, 0xc0,
0xdf, 0xff, 0xfe, 0x47, 0x03, 0x3e, 0x03, 0xfe,
0x00, 0x16, 0xd6, 0x76, 0xf5, 0x2d, 0x0c, 0x7a,
0x08, 0x77, 0x80, 0x10, 0x21, 0x5c, 0xc2, 0xf1,
0x00, 0x00, 0x01, 0x01, 0x08, 0x0a, 0x00, 0x08,
0xca, 0x5a, 0x00, 0x01, 0x69, 0x28};
csum = *( ((uint16_t *)(raw_ipv6 + 70)));
FAIL_IF(TCPV6Checksum((uint16_t *)(raw_ipv6 + 14 + 8),
(uint16_t *)(raw_ipv6 + 54), 32, csum) == 0);
PASS;
}
/** \test Get the wscale of 2 */
static int TCPGetWscaleTest01(void)
{
static uint8_t raw_tcp[] = {0xda, 0xc1, 0x00, 0x50, 0xb6, 0x21, 0x7f, 0x58,
0x00, 0x00, 0x00, 0x00, 0xa0, 0x02, 0x16, 0xd0,
0x8a, 0xaf, 0x00, 0x00, 0x02, 0x04, 0x05, 0xb4,
0x04, 0x02, 0x08, 0x0a, 0x00, 0x62, 0x88, 0x28,
0x00, 0x00, 0x00, 0x00, 0x01, 0x03, 0x03, 0x02};
Packet *p = PacketGetFromAlloc();
FAIL_IF_NULL(p);
IPV4Hdr ip4h;
ThreadVars tv;
DecodeThreadVars dtv;
memset(&tv, 0, sizeof(ThreadVars));
memset(&dtv, 0, sizeof(DecodeThreadVars));
memset(&ip4h, 0, sizeof(IPV4Hdr));
p->src.family = AF_INET;
p->dst.family = AF_INET;
UTHSetIPV4Hdr(p, &ip4h);
FlowInitConfig(FLOW_QUIET);
DecodeTCP(&tv, &dtv, p, raw_tcp, sizeof(raw_tcp));
FAIL_IF_NOT(PacketIsTCP(p));
uint8_t wscale = TCP_GET_WSCALE(p);
FAIL_IF(wscale != 2);
PacketRecycle(p);
FlowShutdown();
SCFree(p);
PASS;
}
/** \test Get the wscale of 15, so see if return 0 properly */
static int TCPGetWscaleTest02(void)
{
static uint8_t raw_tcp[] = {0xda, 0xc1, 0x00, 0x50, 0xb6, 0x21, 0x7f, 0x58,
0x00, 0x00, 0x00, 0x00, 0xa0, 0x02, 0x16, 0xd0,
0x8a, 0xaf, 0x00, 0x00, 0x02, 0x04, 0x05, 0xb4,
0x04, 0x02, 0x08, 0x0a, 0x00, 0x62, 0x88, 0x28,
0x00, 0x00, 0x00, 0x00, 0x01, 0x03, 0x03, 0x0f};
Packet *p = PacketGetFromAlloc();
FAIL_IF_NULL(p);
IPV4Hdr ip4h;
ThreadVars tv;
DecodeThreadVars dtv;
memset(&tv, 0, sizeof(ThreadVars));
memset(&dtv, 0, sizeof(DecodeThreadVars));
memset(&ip4h, 0, sizeof(IPV4Hdr));
p->src.family = AF_INET;
p->dst.family = AF_INET;
UTHSetIPV4Hdr(p, &ip4h);
FlowInitConfig(FLOW_QUIET);
DecodeTCP(&tv, &dtv, p, raw_tcp, sizeof(raw_tcp));
FAIL_IF_NOT(PacketIsTCP(p));
uint8_t wscale = TCP_GET_WSCALE(p);
FAIL_IF(wscale != 0);
PacketRecycle(p);
FlowShutdown();
SCFree(p);
PASS;
}
/** \test Get the wscale, but it's missing, so see if return 0 properly */
static int TCPGetWscaleTest03(void)
{
static uint8_t raw_tcp[] = {0xda, 0xc1, 0x00, 0x50, 0xb6, 0x21, 0x7f, 0x59,
0xdd, 0xa3, 0x6f, 0xf8, 0x80, 0x10, 0x05, 0xb4,
0x7c, 0x70, 0x00, 0x00, 0x01, 0x01, 0x08, 0x0a,
0x00, 0x62, 0x88, 0x9e, 0x00, 0x00, 0x00, 0x00};
Packet *p = PacketGetFromAlloc();
FAIL_IF_NULL(p);
IPV4Hdr ip4h;
ThreadVars tv;
DecodeThreadVars dtv;
memset(&tv, 0, sizeof(ThreadVars));
memset(&dtv, 0, sizeof(DecodeThreadVars));
memset(&ip4h, 0, sizeof(IPV4Hdr));
p->src.family = AF_INET;
p->dst.family = AF_INET;
UTHSetIPV4Hdr(p, &ip4h);
FlowInitConfig(FLOW_QUIET);
DecodeTCP(&tv, &dtv, p, raw_tcp, sizeof(raw_tcp));
FAIL_IF_NOT(PacketIsTCP(p));
uint8_t wscale = TCP_GET_WSCALE(p);
FAIL_IF(wscale != 0);
PacketRecycle(p);
FlowShutdown();
SCFree(p);
PASS;
}
static int TCPGetSackTest01(void)
{
static uint8_t raw_tcp[] = {
0x00, 0x50, 0x06, 0xa6, 0xfa, 0x87, 0x0b, 0xf5,
0xf1, 0x59, 0x02, 0xe0, 0xa0, 0x10, 0x3e, 0xbc,
0x1d, 0xe7, 0x00, 0x00, 0x01, 0x01, 0x05, 0x12,
0xf1, 0x59, 0x13, 0xfc, 0xf1, 0x59, 0x1f, 0x64,
0xf1, 0x59, 0x08, 0x94, 0xf1, 0x59, 0x0e, 0x48 };
static uint8_t raw_tcp_sack[] = {
0xf1, 0x59, 0x13, 0xfc, 0xf1, 0x59, 0x1f, 0x64,
0xf1, 0x59, 0x08, 0x94, 0xf1, 0x59, 0x0e, 0x48 };
Packet *p = PacketGetFromAlloc();
FAIL_IF_NULL(p);
IPV4Hdr ip4h;
ThreadVars tv;
DecodeThreadVars dtv;
memset(&tv, 0, sizeof(ThreadVars));
memset(&dtv, 0, sizeof(DecodeThreadVars));
memset(&ip4h, 0, sizeof(IPV4Hdr));
p->src.family = AF_INET;
p->dst.family = AF_INET;
UTHSetIPV4Hdr(p, &ip4h);
FlowInitConfig(FLOW_QUIET);
DecodeTCP(&tv, &dtv, p, raw_tcp, sizeof(raw_tcp));
FAIL_IF_NOT(PacketIsTCP(p));
FAIL_IF(!TCP_HAS_SACK(p));
int sack = TCP_GET_SACK_CNT(p);
FAIL_IF(sack != 2);
const TCPHdr *tcph = PacketGetTCP(p);
const uint8_t *sackptr = TCP_GET_SACK_PTR(p, tcph);
FAIL_IF_NULL(sackptr);
FAIL_IF(memcmp(sackptr, raw_tcp_sack, 16) != 0);
PacketRecycle(p);
FlowShutdown();
SCFree(p);
PASS;
}
#endif /* UNITTESTS */
void DecodeTCPRegisterTests(void)
{
#ifdef UNITTESTS
UtRegisterTest("TCPCalculateValidChecksumtest01",
TCPCalculateValidChecksumtest01);
UtRegisterTest("TCPCalculateInvalidChecksumtest02",
TCPCalculateInvalidChecksumtest02);
UtRegisterTest("TCPV6CalculateValidChecksumtest03",
TCPV6CalculateValidChecksumtest03);
UtRegisterTest("TCPV6CalculateInvalidChecksumtest04",
TCPV6CalculateInvalidChecksumtest04);
UtRegisterTest("TCPGetWscaleTest01", TCPGetWscaleTest01);
UtRegisterTest("TCPGetWscaleTest02", TCPGetWscaleTest02);
UtRegisterTest("TCPGetWscaleTest03", TCPGetWscaleTest03);
UtRegisterTest("TCPGetSackTest01", TCPGetSackTest01);
#endif /* UNITTESTS */
}
/**
* @}
*/