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suricata/src/detect-engine-event.c

400 lines
10 KiB
C

/* Copyright (C) 2007-2010 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 Breno Silva <breno.silva@gmail.com>
*
* Implements the decode-event keyword
*/
#include "suricata-common.h"
#include "suricata.h"
#include "decode.h"
#include "detect.h"
#include "detect-parse.h"
#include "flow-var.h"
#include "decode-events.h"
#include "util-debug.h"
#include "stream-tcp.h"
/* Need to get the DEvents[] array */
#define DETECT_EVENTS
#include "detect-engine-event.h"
#include "util-unittest.h"
#define PARSE_REGEX "\\S[0-9A-z_]+[.][A-z0-9_+]+$"
static pcre *parse_regex;
static pcre_extra *parse_regex_study;
int DetectEngineEventMatch (ThreadVars *, DetectEngineThreadCtx *, Packet *, Signature *, SigMatch *);
static int DetectEngineEventSetup (DetectEngineCtx *, Signature *, char *);
static int DetectDecodeEventSetup (DetectEngineCtx *, Signature *, char *);
static int DetectStreamEventSetup (DetectEngineCtx *, Signature *, char *);
void EngineEventRegisterTests(void);
/**
* \brief Registration function for decode-event: keyword
*/
void DetectEngineEventRegister (void) {
sigmatch_table[DETECT_ENGINE_EVENT].name = "engine-event";
sigmatch_table[DETECT_ENGINE_EVENT].Match = DetectEngineEventMatch;
sigmatch_table[DETECT_ENGINE_EVENT].Setup = DetectEngineEventSetup;
sigmatch_table[DETECT_ENGINE_EVENT].Free = NULL;
sigmatch_table[DETECT_ENGINE_EVENT].RegisterTests = EngineEventRegisterTests;
sigmatch_table[DETECT_DECODE_EVENT].name = "decode-event";
sigmatch_table[DETECT_DECODE_EVENT].Match = DetectEngineEventMatch;
sigmatch_table[DETECT_DECODE_EVENT].Setup = DetectDecodeEventSetup;
sigmatch_table[DETECT_DECODE_EVENT].Free = NULL;
sigmatch_table[DETECT_DECODE_EVENT].flags |= SIGMATCH_DEONLY_COMPAT;
sigmatch_table[DETECT_STREAM_EVENT].name = "stream-event";
sigmatch_table[DETECT_STREAM_EVENT].Match = DetectEngineEventMatch;
sigmatch_table[DETECT_STREAM_EVENT].Setup = DetectStreamEventSetup;
sigmatch_table[DETECT_STREAM_EVENT].Free = NULL;
const char *eb;
int eo;
int opts = 0;
parse_regex = pcre_compile(PARSE_REGEX, opts, &eb, &eo, NULL);
if(parse_regex == NULL)
{
SCLogError(SC_ERR_PCRE_COMPILE, "pcre compile of \"%s\" failed at offset %" PRId32 ": %s\n", PARSE_REGEX, eo, eb);
goto error;
}
parse_regex_study = pcre_study(parse_regex, 0, &eb);
if(eb != NULL)
{
SCLogError(SC_ERR_PCRE_STUDY, "pcre study failed: %s\n", eb);
goto error;
}
return;
error:
return;
}
/**
* \brief This function is used to match decoder event flags set on a packet with those passed via decode-event:
*
* \param t pointer to thread vars
* \param det_ctx pointer to the pattern matcher thread
* \param p pointer to the current packet
* \param s pointer to the Signature
* \param m pointer to the sigmatch
*
* \retval 0 no match
* \retval 1 match
*/
int DetectEngineEventMatch (ThreadVars *t, DetectEngineThreadCtx *det_ctx, Packet *p, Signature *s, SigMatch *m)
{
SCEnter();
DetectEngineEventData *de = (DetectEngineEventData *)m->ctx;
if (ENGINE_ISSET_EVENT(p, de->event)) {
SCLogDebug("de->event matched %u", de->event);
SCReturnInt(1);
}
SCReturnInt(0);
}
/**
* \brief This function is used to parse decoder events options passed via decode-event: keyword
*
* \param rawstr Pointer to the user provided decode-event options
*
* \retval de pointer to DetectFlowData on success
* \retval NULL on failure
*/
DetectEngineEventData *DetectEngineEventParse (char *rawstr)
{
int i;
DetectEngineEventData *de = NULL;
#define MAX_SUBSTRINGS 30
int ret = 0, res = 0, found = 0;
int ov[MAX_SUBSTRINGS];
ret = pcre_exec(parse_regex, parse_regex_study, rawstr, strlen(rawstr), 0, 0, ov, MAX_SUBSTRINGS);
if (ret < 1) {
SCLogError(SC_ERR_PCRE_MATCH, "pcre_exec parse error, ret %" PRId32
", string %s", ret, rawstr);
goto error;
}
const char *str_ptr;
res = pcre_get_substring((char *)rawstr, ov, MAX_SUBSTRINGS, 0, &str_ptr);
if (res < 0) {
SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre_get_substring failed");
goto error;
}
for (i = 0; DEvents[i].event_name != NULL; i++) {
if (strcasecmp(DEvents[i].event_name,str_ptr) == 0) {
found = 1;
break;
}
}
if (found == 0) {
SCLogError(SC_ERR_UNKNOWN_DECODE_EVENT, "unknown decode event \"%s\"",
str_ptr);
goto error;
}
de = SCMalloc(sizeof(DetectEngineEventData));
if (unlikely(de == NULL))
goto error;
de->event = DEvents[i].code;
if (de->event == STREAM_REASSEMBLY_OVERLAP_DIFFERENT_DATA) {
StreamTcpReassembleConfigEnableOverlapCheck();
}
return de;
error:
if (de) SCFree(de);
return NULL;
}
/**
* \brief this function is used to add the parsed decode-event into the current signature
*
* \param de_ctx pointer to the Detection Engine Context
* \param s pointer to the Current Signature
* \param rawstr pointer to the user provided decode-event options
*
* \retval 0 on Success
* \retval -1 on Failure
*/
static int _DetectEngineEventSetup (DetectEngineCtx *de_ctx, Signature *s, char *rawstr, int smtype)
{
DetectEngineEventData *de = NULL;
SigMatch *sm = NULL;
de = DetectEngineEventParse(rawstr);
if (de == NULL)
goto error;
SCLogDebug("rawstr %s %u", rawstr, de->event);
sm = SigMatchAlloc();
if (sm == NULL)
goto error;
sm->type = smtype;
sm->ctx = (void *)de;
SigMatchAppendSMToList(s, sm, DETECT_SM_LIST_MATCH);
return 0;
error:
if (de) SCFree(de);
if (sm) SCFree(sm);
return -1;
}
static int DetectEngineEventSetup (DetectEngineCtx *de_ctx, Signature *s, char *rawstr)
{
return _DetectEngineEventSetup (de_ctx, s, rawstr, DETECT_ENGINE_EVENT);
}
/**
* \brief this function will free memory associated with DetectEngineEventData
*
* \param de pointer to DetectEngineEventData
*/
void DetectEngineEventFree(DetectEngineEventData *de) {
if(de) SCFree(de);
}
/**
* \brief this function Setup the 'decode-event' keyword by setting the correct
* signature type
*/
static int DetectDecodeEventSetup (DetectEngineCtx *de_ctx, Signature *s, char *rawstr)
{
return _DetectEngineEventSetup(de_ctx, s, rawstr, DETECT_DECODE_EVENT);
}
/**
* \brief this function Setup the 'stream-event' keyword by resolving the alias
*/
static int DetectStreamEventSetup (DetectEngineCtx *de_ctx, Signature *s, char *rawstr)
{
char srawstr[MAX_SUBSTRINGS * 2] = "stream.";
/* stream:$EVENT alias command develop as decode-event:stream.$EVENT */
strlcat(srawstr, rawstr, 2 * MAX_SUBSTRINGS - strlen("stream.") - 1);
return DetectEngineEventSetup(de_ctx, s, srawstr);
}
/*
* ONLY TESTS BELOW THIS COMMENT
*/
#ifdef UNITTESTS
/**
* \test EngineEventTestParse01 is a test for a valid decode-event value
*/
int EngineEventTestParse01 (void) {
DetectEngineEventData *de = NULL;
de = DetectEngineEventParse("ipv4.pkt_too_small");
if (de) {
DetectEngineEventFree(de);
return 1;
}
return 0;
}
/**
* \test EngineEventTestParse02 is a test for a valid upper + lower case decode-event value
*/
int EngineEventTestParse02 (void) {
DetectEngineEventData *de = NULL;
de = DetectEngineEventParse("PPP.pkt_too_small");
if (de) {
DetectEngineEventFree(de);
return 1;
}
return 0;
}
/**
* \test EngineEventTestParse03 is a test for a valid upper case decode-event value
*/
int EngineEventTestParse03 (void) {
DetectEngineEventData *de = NULL;
de = DetectEngineEventParse("IPV6.PKT_TOO_SMALL");
if (de) {
DetectEngineEventFree(de);
return 1;
}
return 0;
}
/**
* \test EngineEventTestParse04 is a test for an invalid upper case decode-event value
*/
int EngineEventTestParse04 (void) {
DetectEngineEventData *de = NULL;
de = DetectEngineEventParse("IPV6.INVALID_EVENT");
if (de) {
DetectEngineEventFree(de);
return 1;
}
return 0;
}
/**
* \test EngineEventTestParse05 is a test for an invalid char into the decode-event value
*/
int EngineEventTestParse05 (void) {
DetectEngineEventData *de = NULL;
de = DetectEngineEventParse("IPV-6,INVALID_CHAR");
if (de) {
DetectEngineEventFree(de);
return 1;
}
return 0;
}
/**
* \test EngineEventTestParse06 is a test for match function with valid decode-event value
*/
int EngineEventTestParse06 (void) {
Packet *p = SCMalloc(SIZE_OF_PACKET);
if (unlikely(p == NULL))
return 0;
ThreadVars tv;
int ret = 0;
DetectEngineEventData *de = NULL;
SigMatch *sm = NULL;
memset(&tv, 0, sizeof(ThreadVars));
memset(p, 0, SIZE_OF_PACKET);
p->pkt = (uint8_t *)(p + 1);
ENGINE_SET_EVENT(p,PPP_PKT_TOO_SMALL);
de = DetectEngineEventParse("ppp.pkt_too_small");
if (de == NULL)
goto error;
de->event = PPP_PKT_TOO_SMALL;
sm = SigMatchAlloc();
if (sm == NULL)
goto error;
sm->type = DETECT_DECODE_EVENT;
sm->ctx = (void *)de;
ret = DetectEngineEventMatch(&tv,NULL,p,NULL,sm);
if(ret) {
SCFree(p);
return 1;
}
error:
if (de) SCFree(de);
if (sm) SCFree(sm);
SCFree(p);
return 0;
}
#endif /* UNITTESTS */
/**
* \brief this function registers unit tests for EngineEvent
*/
void EngineEventRegisterTests(void) {
#ifdef UNITTESTS
UtRegisterTest("EngineEventTestParse01", EngineEventTestParse01, 1);
UtRegisterTest("EngineEventTestParse02", EngineEventTestParse02, 1);
UtRegisterTest("EngineEventTestParse03", EngineEventTestParse03, 1);
UtRegisterTest("EngineEventTestParse04", EngineEventTestParse04, 0);
UtRegisterTest("EngineEventTestParse05", EngineEventTestParse05, 0);
UtRegisterTest("EngineEventTestParse06", EngineEventTestParse06, 1);
#endif /* UNITTESTS */
}