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suricata/src/detect-tls-certs.c

261 lines
7.9 KiB
C

/* Copyright (C) 2019 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 Mats Klepsland <mats.klepsland@gmail.com>
*
* Implements support for tls.certs keyword.
*/
#include "suricata-common.h"
#include "threads.h"
#include "debug.h"
#include "decode.h"
#include "detect.h"
#include "detect-parse.h"
#include "detect-engine.h"
#include "detect-engine-mpm.h"
#include "detect-engine-prefilter.h"
#include "detect-engine-content-inspection.h"
#include "detect-content.h"
#include "detect-pcre.h"
#include "detect-tls-certs.h"
#include "flow.h"
#include "flow-util.h"
#include "flow-var.h"
#include "util-debug.h"
#include "util-unittest.h"
#include "util-spm.h"
#include "util-print.h"
#include "stream-tcp.h"
#include "app-layer.h"
#include "app-layer-ssl.h"
#include "util-unittest.h"
#include "util-unittest-helper.h"
static int DetectTlsCertsSetup(DetectEngineCtx *, Signature *, const char *);
#ifdef UNITTESTS
static void DetectTlsCertsRegisterTests(void);
#endif
static int DetectEngineInspectTlsCerts(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);
static int PrefilterMpmTlsCertsRegister(DetectEngineCtx *de_ctx,
SigGroupHead *sgh, MpmCtx *mpm_ctx,
const DetectBufferMpmRegistery *mpm_reg, int list_id);
static int g_tls_certs_buffer_id = 0;
struct TlsCertsGetDataArgs {
int local_id; /**< used as index into thread inspect array */
SSLCertsChain *cert;
};
typedef struct PrefilterMpmTlsCerts {
int list_id;
const MpmCtx *mpm_ctx;
const DetectEngineTransforms *transforms;
} PrefilterMpmTlsCerts;
/**
* \brief Registration function for keyword: tls.certs
*/
void DetectTlsCertsRegister(void)
{
sigmatch_table[DETECT_AL_TLS_CERTS].name = "tls.certs";
sigmatch_table[DETECT_AL_TLS_CERTS].desc = "content modifier to match the TLS certificate sticky buffer";
sigmatch_table[DETECT_AL_TLS_CERTS].url = DOC_URL DOC_VERSION "/rules/tls-keywords.html#tls-certs";
sigmatch_table[DETECT_AL_TLS_CERTS].Setup = DetectTlsCertsSetup;
#ifdef UNITTESTS
sigmatch_table[DETECT_AL_TLS_CERTS].RegisterTests = DetectTlsCertsRegisterTests;
#endif
sigmatch_table[DETECT_AL_TLS_CERTS].flags |= SIGMATCH_NOOPT;
sigmatch_table[DETECT_AL_TLS_CERTS].flags |= SIGMATCH_INFO_STICKY_BUFFER;
DetectAppLayerInspectEngineRegister2("tls.certs", ALPROTO_TLS,
SIG_FLAG_TOCLIENT, TLS_STATE_CERT_READY,
DetectEngineInspectTlsCerts, NULL);
DetectAppLayerMpmRegister2("tls.certs", SIG_FLAG_TOCLIENT, 2,
PrefilterMpmTlsCertsRegister, NULL, ALPROTO_TLS,
TLS_STATE_CERT_READY);
DetectBufferTypeSetDescriptionByName("tls.certs", "TLS certificate");
g_tls_certs_buffer_id = DetectBufferTypeGetByName("tls.certs");
}
/**
* \brief This function setup the tls.certs modifier keyword
*
* \param de_ctx Pointer to the Detect Engine Context
* \param s Pointer to the Signature to which the keyword belongs
* \param str Should hold an empty string always
*
* \retval 0 On success
* \retval -1 On failure
*/
static int DetectTlsCertsSetup(DetectEngineCtx *de_ctx, Signature *s,
const char *str)
{
if (DetectBufferSetActiveList(s, g_tls_certs_buffer_id) < 0)
return -1;
if (DetectSignatureSetAppProto(s, ALPROTO_TLS) < 0)
return -1;
return 0;
}
static InspectionBuffer *TlsCertsGetData(DetectEngineThreadCtx *det_ctx,
const DetectEngineTransforms *transforms, Flow *f,
struct TlsCertsGetDataArgs *cbdata, int list_id)
{
SCEnter();
InspectionBufferMultipleForList *fb = InspectionBufferGetMulti(det_ctx, list_id);
InspectionBuffer *buffer = InspectionBufferMultipleForListGet(fb, cbdata->local_id);
if (buffer == NULL)
return NULL;
const SSLState *ssl_state = (SSLState *)f->alstate;
if (TAILQ_EMPTY(&ssl_state->server_connp.certs)) {
return NULL;
}
if (cbdata->cert == NULL) {
cbdata->cert = TAILQ_FIRST(&ssl_state->server_connp.certs);
} else {
cbdata->cert = TAILQ_NEXT(cbdata->cert, next);
}
if (cbdata->cert == NULL) {
return NULL;
}
InspectionBufferSetup(buffer, cbdata->cert->cert_data,
cbdata->cert->cert_len);
InspectionBufferApplyTransforms(buffer, transforms);
SCReturnPtr(buffer, "InspectionBuffer");
}
static int DetectEngineInspectTlsCerts(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)
{
const DetectEngineTransforms *transforms = NULL;
if (!engine->mpm) {
transforms = engine->v2.transforms;
}
struct TlsCertsGetDataArgs cbdata = { 0, NULL };
while (1)
{
InspectionBuffer *buffer = TlsCertsGetData(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;
}
cbdata.local_id++;
}
return DETECT_ENGINE_INSPECT_SIG_NO_MATCH;
}
static void PrefilterTxTlsCerts(DetectEngineThreadCtx *det_ctx,
const void *pectx, Packet *p, Flow *f, void *txv,
const uint64_t idx, const uint8_t flags)
{
SCEnter();
const PrefilterMpmTlsCerts *ctx = (const PrefilterMpmTlsCerts *)pectx;
const MpmCtx *mpm_ctx = ctx->mpm_ctx;
const int list_id = ctx->list_id;
struct TlsCertsGetDataArgs cbdata = { 0, NULL };
while (1)
{
InspectionBuffer *buffer = TlsCertsGetData(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);
}
cbdata.local_id++;
}
}
static void PrefilterMpmTlsCertsFree(void *ptr)
{
SCFree(ptr);
}
static int PrefilterMpmTlsCertsRegister(DetectEngineCtx *de_ctx,
SigGroupHead *sgh, MpmCtx *mpm_ctx,
const DetectBufferMpmRegistery *mpm_reg, int list_id)
{
PrefilterMpmTlsCerts *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, PrefilterTxTlsCerts,
mpm_reg->app_v2.alproto, mpm_reg->app_v2.tx_min_progress,
pectx, PrefilterMpmTlsCertsFree, mpm_reg->name);
}
#ifdef UNITTESTS
#include "tests/detect-tls-certs.c"
#endif