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/* Copyright (C) 2018-2022 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 Pierre Chifflier <chifflier@wzdftpd.net>
*/
#include "suricata-common.h"
#include "util-unittest.h"
#include "detect-parse.h"
#include "detect-engine.h"
#include "detect-engine-mpm.h"
#include "detect-engine-state.h"
#include "detect-engine-prefilter.h"
#include "detect-engine-content-inspection.h"
#include "detect-krb5-sname.h"
#include "rust.h"
#include "app-layer-krb5.h"
#include "util-profiling.h"
static int g_krb5_sname_buffer_id = 0;
struct Krb5PrincipalNameDataArgs {
uint32_t local_id; /**< used as index into thread inspect array */
void *txv;
};
static int DetectKrb5SNameSetup(DetectEngineCtx *de_ctx, Signature *s, const char *arg)
{
if (DetectBufferSetActiveList(de_ctx, s, g_krb5_sname_buffer_id) < 0)
return -1;
if (DetectSignatureSetAppProto(s, ALPROTO_KRB5) != 0)
return -1;
return 0;
}
static InspectionBuffer *GetKrb5SNameData(DetectEngineThreadCtx *det_ctx,
const DetectEngineTransforms *transforms, Flow *_f,
const struct Krb5PrincipalNameDataArgs *cbdata, int list_id)
{
SCEnter();
InspectionBuffer *buffer =
InspectionBufferMultipleForListGet(det_ctx, list_id, cbdata->local_id);
if (buffer == NULL)
return NULL;
if (buffer->initialized)
return buffer;
uint32_t b_len = 0;
const uint8_t *b = NULL;
if (rs_krb5_tx_get_sname(cbdata->txv, cbdata->local_id, &b, &b_len) != 1) {
InspectionBufferSetupMultiEmpty(buffer);
return NULL;
}
if (b == NULL || b_len == 0) {
InspectionBufferSetupMultiEmpty(buffer);
return NULL;
}
InspectionBufferSetupMulti(buffer, transforms, b, b_len);
SCReturnPtr(buffer, "InspectionBuffer");
}
static uint8_t DetectEngineInspectKrb5SName(DetectEngineCtx *de_ctx, DetectEngineThreadCtx *det_ctx,
const DetectEngineAppInspectionEngine *engine, const Signature *s, Flow *f, uint8_t flags,
void *alstate, void *txv, uint64_t tx_id)
{
uint32_t local_id = 0;
const DetectEngineTransforms *transforms = NULL;
if (!engine->mpm) {
transforms = engine->v2.transforms;
}
while (1) {
struct Krb5PrincipalNameDataArgs cbdata = { local_id, txv, };
InspectionBuffer *buffer =
GetKrb5SNameData(det_ctx, transforms, f, &cbdata, engine->sm_list);
if (buffer == NULL || buffer->inspect == NULL)
break;
det_ctx->buffer_offset = 0;
det_ctx->discontinue_matching = 0;
det_ctx->inspection_recursion_counter = 0;
const int match = DetectEngineContentInspection(de_ctx, det_ctx, s, engine->smd,
NULL, f,
(uint8_t *)buffer->inspect,
buffer->inspect_len,
buffer->inspect_offset, DETECT_CI_FLAGS_SINGLE,
DETECT_ENGINE_CONTENT_INSPECTION_MODE_STATE);
if (match == 1) {
return DETECT_ENGINE_INSPECT_SIG_MATCH;
}
local_id++;
}
return DETECT_ENGINE_INSPECT_SIG_NO_MATCH;
}
typedef struct PrefilterMpmKrb5Name {
int list_id;
const MpmCtx *mpm_ctx;
const DetectEngineTransforms *transforms;
} PrefilterMpmKrb5Name;
/** \brief Krb5SName Krb5SName Mpm prefilter callback
*
* \param det_ctx detection engine thread ctx
* \param p packet to inspect
* \param f flow to inspect
* \param txv tx to inspect
* \param pectx inspection context
*/
static void PrefilterTxKrb5SName(DetectEngineThreadCtx *det_ctx, const void *pectx, Packet *p,
Flow *f, void *txv, const uint64_t idx, const AppLayerTxData *_txd, const uint8_t flags)
{
SCEnter();
const PrefilterMpmKrb5Name *ctx = (const PrefilterMpmKrb5Name *)pectx;
const MpmCtx *mpm_ctx = ctx->mpm_ctx;
const int list_id = ctx->list_id;
uint32_t local_id = 0;
while(1) {
// loop until we get a NULL
struct Krb5PrincipalNameDataArgs cbdata = { local_id, txv };
InspectionBuffer *buffer = GetKrb5SNameData(det_ctx, ctx->transforms, f, &cbdata, list_id);
if (buffer == NULL)
break;
if (buffer->inspect_len >= mpm_ctx->minlen) {
(void)mpm_table[mpm_ctx->mpm_type].Search(mpm_ctx,
&det_ctx->mtcu, &det_ctx->pmq,
buffer->inspect, buffer->inspect_len);
PREFILTER_PROFILING_ADD_BYTES(det_ctx, buffer->inspect_len);
}
local_id++;
}
}
static void PrefilterMpmKrb5NameFree(void *ptr)
{
SCFree(ptr);
}
static int PrefilterMpmKrb5SNameRegister(DetectEngineCtx *de_ctx, SigGroupHead *sgh,
MpmCtx *mpm_ctx, const DetectBufferMpmRegistry *mpm_reg, int list_id)
{
PrefilterMpmKrb5Name *pectx = SCCalloc(1, sizeof(*pectx));
if (pectx == NULL)
return -1;
pectx->list_id = list_id;
pectx->mpm_ctx = mpm_ctx;
pectx->transforms = &mpm_reg->transforms;
return PrefilterAppendTxEngine(de_ctx, sgh, PrefilterTxKrb5SName,
mpm_reg->app_v2.alproto, mpm_reg->app_v2.tx_min_progress,
pectx, PrefilterMpmKrb5NameFree, mpm_reg->name);
}
void DetectKrb5SNameRegister(void)
{
sigmatch_table[DETECT_AL_KRB5_SNAME].name = "krb5.sname";
sigmatch_table[DETECT_AL_KRB5_SNAME].alias = "krb5_sname";
sigmatch_table[DETECT_AL_KRB5_SNAME].url = "/rules/kerberos-keywords.html#krb5-sname";
sigmatch_table[DETECT_AL_KRB5_SNAME].Setup = DetectKrb5SNameSetup;
sigmatch_table[DETECT_AL_KRB5_SNAME].flags |= SIGMATCH_NOOPT|SIGMATCH_INFO_STICKY_BUFFER;
sigmatch_table[DETECT_AL_KRB5_SNAME].desc = "sticky buffer to match on Kerberos 5 server name";
DetectAppLayerMpmRegister2("krb5_sname", SIG_FLAG_TOCLIENT, 2,
PrefilterMpmKrb5SNameRegister, NULL,
ALPROTO_KRB5, 1);
DetectAppLayerInspectEngineRegister2("krb5_sname",
ALPROTO_KRB5, SIG_FLAG_TOCLIENT, 0,
DetectEngineInspectKrb5SName, NULL);
DetectBufferTypeSetDescriptionByName("krb5_sname",
"Kerberos 5 ticket server name");
g_krb5_sname_buffer_id = DetectBufferTypeGetByName("krb5_sname");
DetectBufferTypeSupportsMultiInstance("krb5_sname");
}
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