mirror of https://github.com/OISF/suricata
detect: add tcp.wscale keyword
Allows matching on wscale option value in TCP header options. Ticket: #7713.pull/13410/head
Victor Julien
5 months ago
committed by
Victor Julien
parent
0246668de7
commit
ecbcccf355
@ -0,0 +1,172 @@
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/* Copyright (C) 2007-2025 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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* \file
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*
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* \author Victor Julien <vjulien@oisf.net>
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*
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*/
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#include "suricata-common.h"
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#include "detect.h"
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#include "detect-parse.h"
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#include "detect-engine-prefilter-common.h"
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#include "detect-engine-uint.h"
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#include "util-byte.h"
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#include "detect-tcp-wscale.h"
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/* prototypes */
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static int DetectTcpWscaleMatch(
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DetectEngineThreadCtx *, Packet *, const Signature *, const SigMatchCtx *);
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static int DetectTcpWscaleSetup(DetectEngineCtx *, Signature *, const char *);
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void DetectTcpWscaleFree(DetectEngineCtx *, void *);
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static int PrefilterSetupTcpWscale(DetectEngineCtx *de_ctx, SigGroupHead *sgh);
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static bool PrefilterTcpWscaleIsPrefilterable(const Signature *s);
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/**
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* \brief Registration function for tcp.wscale keyword
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*/
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void DetectTcpWscaleRegister(void)
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{
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sigmatch_table[DETECT_TCP_WSCALE].name = "tcp.wscale";
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sigmatch_table[DETECT_TCP_WSCALE].desc = "match on TCP WSCALE option field";
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sigmatch_table[DETECT_TCP_WSCALE].url = "/rules/header-keywords.html#tcpwscale";
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sigmatch_table[DETECT_TCP_WSCALE].Match = DetectTcpWscaleMatch;
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sigmatch_table[DETECT_TCP_WSCALE].Setup = DetectTcpWscaleSetup;
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sigmatch_table[DETECT_TCP_WSCALE].Free = DetectTcpWscaleFree;
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sigmatch_table[DETECT_TCP_WSCALE].SupportsPrefilter = PrefilterTcpWscaleIsPrefilterable;
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sigmatch_table[DETECT_TCP_WSCALE].SetupPrefilter = PrefilterSetupTcpWscale;
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sigmatch_table[DETECT_TCP_WSCALE].flags = SIGMATCH_SUPPORT_FIREWALL;
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}
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/**
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* \brief This function is used to match WSCALE rule option on a packet with those passed via
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* tcp.wscale:
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*
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* \param det_ctx pointer to the pattern matcher thread
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* \param p pointer to the current packet
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* \param ctx pointer to the sigmatch that we will cast into DetectU8Data
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*
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* \retval 0 no match
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* \retval 1 match
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*/
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static int DetectTcpWscaleMatch(
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DetectEngineThreadCtx *det_ctx, Packet *p, const Signature *s, const SigMatchCtx *ctx)
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{
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DEBUG_VALIDATE_BUG_ON(PKT_IS_PSEUDOPKT(p));
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if (!(PacketIsTCP(p)))
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return 0;
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if (!(TCP_HAS_WSCALE(p)))
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return 0;
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uint8_t v = TCP_GET_WSCALE(p);
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const DetectU8Data *ws = (const DetectU8Data *)ctx;
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return DetectU8Match(v, ws);
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}
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/**
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* \brief this function is used to attach the parsed tcp.wscale data into the current signature
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*
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* \param de_ctx pointer to the Detection Engine Context
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* \param s pointer to the Current Signature
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* \param str pointer to the user provided options
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*
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* \retval 0 on Success
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* \retval -1 on Failure
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*/
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static int DetectTcpWscaleSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
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{
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DetectU8Data *ws = DetectU8Parse(str);
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if (ws == NULL)
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return -1;
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if (SCSigMatchAppendSMToList(
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de_ctx, s, DETECT_TCP_WSCALE, (SigMatchCtx *)ws, DETECT_SM_LIST_MATCH) == NULL) {
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DetectTcpWscaleFree(de_ctx, ws);
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return -1;
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}
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s->flags |= SIG_FLAG_REQUIRE_PACKET;
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return 0;
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}
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/**
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* \brief this function will free memory associated with DetectU8Data
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*
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* \param ptr pointer to DetectU8Data
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*/
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void DetectTcpWscaleFree(DetectEngineCtx *de_ctx, void *ptr)
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{
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SCDetectU8Free(ptr);
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}
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/* prefilter code */
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static void PrefilterPacketTcpWscaleMatch(
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DetectEngineThreadCtx *det_ctx, Packet *p, const void *pectx)
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{
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DEBUG_VALIDATE_BUG_ON(PKT_IS_PSEUDOPKT(p));
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if (!(PacketIsTCP(p)))
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return;
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if (!(TCP_HAS_WSCALE(p)))
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return;
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const uint8_t v = TCP_GET_WSCALE(p);
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/* during setup Suricata will automatically see if there is another
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* check that can be added: alproto, sport or dport */
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const PrefilterPacketHeaderCtx *ctx = pectx;
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if (!PrefilterPacketHeaderExtraMatch(ctx, p))
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return;
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DetectU8Data du8;
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du8.mode = ctx->v1.u8[0];
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du8.arg1 = ctx->v1.u8[1];
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du8.arg2 = ctx->v1.u8[2];
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/* if we match, add all the sigs that use this prefilter. This means
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* that these will be inspected further */
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if (DetectU8Match(v, &du8)) {
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SCLogDebug("packet matches wscale %u", v);
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PrefilterAddSids(&det_ctx->pmq, ctx->sigs_array, ctx->sigs_cnt);
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}
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}
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static int PrefilterSetupTcpWscale(DetectEngineCtx *de_ctx, SigGroupHead *sgh)
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{
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return PrefilterSetupPacketHeader(de_ctx, sgh, DETECT_TCP_WSCALE, SIG_MASK_REQUIRE_REAL_PKT,
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PrefilterPacketU8Set, PrefilterPacketU8Compare, PrefilterPacketTcpWscaleMatch);
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}
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static bool PrefilterTcpWscaleIsPrefilterable(const Signature *s)
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{
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const SigMatch *sm;
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for (sm = s->init_data->smlists[DETECT_SM_LIST_MATCH]; sm != NULL; sm = sm->next) {
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switch (sm->type) {
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case DETECT_TCP_WSCALE:
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return true;
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}
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}
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return false;
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}
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@ -0,0 +1,29 @@
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/* Copyright (C) 2007-2019 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
|
||||
* 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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* \file
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*
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* \author Victor Julien <victor@inliniac.net>
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*/
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#ifndef SURICARA_DETECT_TCP_WSCALE_H
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#define SURICARA_DETECT_TCP_WSCALE_H
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void DetectTcpWscaleRegister(void);
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#endif /* SURICARA_DETECT_TCP_WSCALE_H */
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