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/* Copyright (C) 2020 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.
*/
/**
* \file
*
* \author Philippe Antoine <p.antoine@catenacyber.fr>
*
*/
#include "suricata-common.h"
#include "detect.h"
#include "detect-parse.h"
#include "detect-icmpv6-mtu.h"
#include "detect-engine-uint.h"
/* prototypes */
static int DetectICMPv6mtuMatch (DetectEngineThreadCtx *, Packet *,
const Signature *, const SigMatchCtx *);
static int DetectICMPv6mtuSetup (DetectEngineCtx *, Signature *, const char *);
void DetectICMPv6mtuFree (DetectEngineCtx *de_ctx, void *);
#ifdef UNITTESTS
void DetectICMPv6mtuRegisterTests (void);
#endif
static int PrefilterSetupIcmpv6mtu(DetectEngineCtx *de_ctx, SigGroupHead *sgh);
static bool PrefilterIcmpv6mtuIsPrefilterable(const Signature *s);
/**
* \brief Registration function for icmpv6.mtu: keyword
*/
void DetectICMPv6mtuRegister(void)
{
sigmatch_table[DETECT_ICMPV6MTU].name = "icmpv6.mtu";
sigmatch_table[DETECT_ICMPV6MTU].desc = "match on ICMPv6 MTU field";
sigmatch_table[DETECT_ICMPV6MTU].url = "/rules/header-keywords.html#icmpv6mtu";
sigmatch_table[DETECT_ICMPV6MTU].Match = DetectICMPv6mtuMatch;
sigmatch_table[DETECT_ICMPV6MTU].Setup = DetectICMPv6mtuSetup;
sigmatch_table[DETECT_ICMPV6MTU].Free = DetectICMPv6mtuFree;
#ifdef UNITTESTS
sigmatch_table[DETECT_ICMPV6MTU].RegisterTests = DetectICMPv6mtuRegisterTests;
#endif
sigmatch_table[DETECT_ICMPV6MTU].SupportsPrefilter = PrefilterIcmpv6mtuIsPrefilterable;
sigmatch_table[DETECT_ICMPV6MTU].SetupPrefilter = PrefilterSetupIcmpv6mtu;
return;
}
// returns 0 on no mtu, and 1 if mtu
static inline int DetectICMPv6mtuGetValue(Packet *p, uint32_t *picmpv6mtu)
{
if (!(PKT_IS_ICMPV6(p)) || PKT_IS_PSEUDOPKT(p))
return 0;
if (ICMPV6_GET_CODE(p) != 0)
return 0;
if (!(ICMPV6_HAS_MTU(p)))
return 0;
*picmpv6mtu = ICMPV6_GET_MTU(p);
return 1;
}
/**
* \brief This function is used to match ICMPV6 MTU rule option on a packet with those passed via icmpv6.mtu:
*
* \param det_ctx pointer to the pattern matcher thread
* \param p pointer to the current packet
* \param s pointer to the signature unused
* \param ctx pointer to the signature match context
*
* \retval 0 no match
* \retval 1 match
*/
static int DetectICMPv6mtuMatch (DetectEngineThreadCtx *det_ctx, Packet *p,
const Signature *s, const SigMatchCtx *ctx)
{
uint32_t picmpv6mtu;
if (DetectICMPv6mtuGetValue(p, &picmpv6mtu) == 0) {
return 0;
}
const DetectU32Data *du32 = (const DetectU32Data *)ctx;
return DetectU32Match(picmpv6mtu, du32);
}
/**
* \brief this function is used to attach the parsed icmpv6.mtu data into the current signature
*
* \param de_ctx pointer to the Detection Engine Context
* \param s pointer to the Current Signature
* \param icmpv6mtustr pointer to the user provided icmpv6.mtu options
*
* \retval 0 on Success
* \retval -1 on Failure
*/
static int DetectICMPv6mtuSetup (DetectEngineCtx *de_ctx, Signature *s, const char *icmpv6mtustr)
{
DetectU32Data *icmpv6mtud = DetectU32Parse(icmpv6mtustr);
if (icmpv6mtud == NULL)
return -1;
SigMatch *sm = SigMatchAlloc();
if (sm == NULL) {
DetectICMPv6mtuFree(de_ctx, icmpv6mtud);
return -1;
}
sm->type = DETECT_ICMPV6MTU;
sm->ctx = (SigMatchCtx *)icmpv6mtud;
SigMatchAppendSMToList(s, sm, DETECT_SM_LIST_MATCH);
s->flags |= SIG_FLAG_REQUIRE_PACKET;
s->proto.flags |= DETECT_PROTO_IPV6;
return 0;
}
/**
* \brief this function will free memory associated with DetectU32Data
*
* \param ptr pointer to DetectU32Data
*/
void DetectICMPv6mtuFree(DetectEngineCtx *de_ctx, void *ptr)
{
rs_detect_u32_free(ptr);
}
/* prefilter code */
static void
PrefilterPacketIcmpv6mtuMatch(DetectEngineThreadCtx *det_ctx, Packet *p, const void *pectx)
{
uint32_t picmpv6mtu;
if (DetectICMPv6mtuGetValue(p, &picmpv6mtu) == 0) {
return;
}
/* during setup Suricata will automatically see if there is another
* check that can be added: alproto, sport or dport */
const PrefilterPacketHeaderCtx *ctx = pectx;
if (!PrefilterPacketHeaderExtraMatch(ctx, p))
return;
/* if we match, add all the sigs that use this prefilter. This means
* that these will be inspected further */
DetectU32Data du32;
du32.mode = ctx->v1.u8[0];
du32.arg1 = ctx->v1.u32[1];
du32.arg2 = ctx->v1.u32[2];
if (DetectU32Match(picmpv6mtu, &du32))
{
SCLogDebug("packet matches icmpv6.mtu/hl %u", picmpv6mtu);
PrefilterAddSids(&det_ctx->pmq, ctx->sigs_array, ctx->sigs_cnt);
}
}
static int PrefilterSetupIcmpv6mtu(DetectEngineCtx *de_ctx, SigGroupHead *sgh)
{
return PrefilterSetupPacketHeader(de_ctx, sgh, DETECT_ICMPV6MTU,
PrefilterPacketU32Set,
PrefilterPacketU32Compare,
PrefilterPacketIcmpv6mtuMatch);
}
static bool PrefilterIcmpv6mtuIsPrefilterable(const Signature *s)
{
return PrefilterIsPrefilterableById(s, DETECT_ICMPV6MTU);
}
#ifdef UNITTESTS
#include "tests/detect-icmpv6-mtu.c"
#endif
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