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125 lines
4.2 KiB
C
125 lines
4.2 KiB
C
/* Copyright (C) 2026 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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* Implements sctp.chunk_cnt keyword
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*
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* Author: Giuseppe Longo <glongo@oisf.net>
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*/
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#include "suricata-common.h"
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#include "decode.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-build.h"
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#include "detect-sctp-chunk-cnt.h"
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#include "detect-engine-uint.h"
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#include "util-byte.h"
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#include "util-debug.h"
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static int DetectSCTPChunkCntMatch(
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DetectEngineThreadCtx *, Packet *, const Signature *, const SigMatchCtx *);
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static int DetectSCTPChunkCntSetup(DetectEngineCtx *, Signature *, const char *);
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void DetectSCTPChunkCntFree(DetectEngineCtx *, void *);
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static int PrefilterSetupSCTPChunkCnt(DetectEngineCtx *de_ctx, SigGroupHead *sgh);
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static bool PrefilterSCTPChunkCntIsPrefilterable(const Signature *s);
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void DetectSCTPChunkCntRegister(void)
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{
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sigmatch_table[DETECT_SCTP_CHUNK_CNT].name = "sctp.chunk_cnt";
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sigmatch_table[DETECT_SCTP_CHUNK_CNT].desc = "match on the SCTP chunk count";
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sigmatch_table[DETECT_SCTP_CHUNK_CNT].url = "/rules/sctp-keywords.html#sctp-chunk-cnt";
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sigmatch_table[DETECT_SCTP_CHUNK_CNT].Match = DetectSCTPChunkCntMatch;
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sigmatch_table[DETECT_SCTP_CHUNK_CNT].Setup = DetectSCTPChunkCntSetup;
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sigmatch_table[DETECT_SCTP_CHUNK_CNT].Free = DetectSCTPChunkCntFree;
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sigmatch_table[DETECT_SCTP_CHUNK_CNT].flags = SIGMATCH_INFO_UINT16;
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sigmatch_table[DETECT_SCTP_CHUNK_CNT].SupportsPrefilter = PrefilterSCTPChunkCntIsPrefilterable;
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sigmatch_table[DETECT_SCTP_CHUNK_CNT].SetupPrefilter = PrefilterSetupSCTPChunkCnt;
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}
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static int DetectSCTPChunkCntMatch(
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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 (!PacketIsSCTP(p)) {
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return 0;
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}
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uint16_t val = p->l4.vars.sctp.chunk_cnt;
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const DetectU16Data *data = (const DetectU16Data *)ctx;
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return DetectU16Match(val, data);
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}
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static int DetectSCTPChunkCntSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
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{
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DetectU16Data *data = DetectU16Parse(str);
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if (data == NULL)
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return -1;
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if (SCSigMatchAppendSMToList(de_ctx, s, DETECT_SCTP_CHUNK_CNT, (SigMatchCtx *)data,
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DETECT_SM_LIST_MATCH) == NULL) {
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DetectSCTPChunkCntFree(de_ctx, data);
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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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void DetectSCTPChunkCntFree(DetectEngineCtx *de_ctx, void *ptr)
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{
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DetectU16Data *data = (DetectU16Data *)ptr;
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SCDetectU16Free(data);
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}
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static void PrefilterPacketSCTPChunkCntMatch(
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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 (PacketIsSCTP(p)) {
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uint16_t val = p->l4.vars.sctp.chunk_cnt;
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const PrefilterPacketHeaderCtx *ctx = pectx;
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DetectU16Data du16;
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du16.mode = ctx->v1.u8[0];
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du16.arg1 = ctx->v1.u16[1];
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du16.arg2 = ctx->v1.u16[2];
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if (DetectU16Match(val, &du16)) {
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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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}
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static int PrefilterSetupSCTPChunkCnt(DetectEngineCtx *de_ctx, SigGroupHead *sgh)
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{
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return PrefilterSetupPacketHeader(de_ctx, sgh, DETECT_SCTP_CHUNK_CNT, SIG_MASK_REQUIRE_REAL_PKT,
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PrefilterPacketU16Set, PrefilterPacketU16Compare, PrefilterPacketSCTPChunkCntMatch);
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}
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static bool PrefilterSCTPChunkCntIsPrefilterable(const Signature *s)
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{
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return PrefilterIsPrefilterableById(s, DETECT_SCTP_CHUNK_CNT);
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}
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