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suricata/src/detect-icode.c

480 lines
13 KiB
C

/**
* Copyright (c) 2009 Open Information Security Foundation
*
* \file detect-icode.c
* \author Gerardo Iglesias <iglesiasg@gmail.com>
*
* "icode" keyword support
*/
#include "suricata-common.h"
#include "debug.h"
#include "decode.h"
#include "detect.h"
#include "detect-icode.h"
#include "util-byte.h"
#include "util-unittest.h"
#include "util-debug.h"
/**
*\brief Regex for parsing our icode options
*/
#define PARSE_REGEX "^\\s*(<|>)?\\s*([0-9]+)\\s*(?:<>\\s*([0-9]+))?\\s*$"
static pcre *parse_regex;
static pcre_extra *parse_regex_study;
int DetectICodeMatch(ThreadVars *, DetectEngineThreadCtx *, Packet *, Signature *, SigMatch *);
int DetectICodeSetup(DetectEngineCtx *, Signature *, SigMatch *, char *);
void DetectICodeRegisterTests(void);
void DetectICodeFree(void *);
/**
* \brief Registration function for icode: keyword
*/
void DetectICodeRegister (void) {
sigmatch_table[DETECT_ICODE].name = "icode";
sigmatch_table[DETECT_ICODE].Match = DetectICodeMatch;
sigmatch_table[DETECT_ICODE].Setup = DetectICodeSetup;
sigmatch_table[DETECT_ICODE].Free = DetectICodeFree;
sigmatch_table[DETECT_ICODE].RegisterTests = DetectICodeRegisterTests;
const char *eb;
int eo;
int opts = 0;
parse_regex = pcre_compile(PARSE_REGEX, opts, &eb, &eo, NULL);
if(parse_regex == NULL)
{
SCLogError(SC_PCRE_COMPILE_FAILED, "pcre compile of \"%s\" failed at offset %" PRId32 ": %s", PARSE_REGEX, eo, eb);
goto error;
}
parse_regex_study = pcre_study(parse_regex, 0, &eb);
if(eb != NULL)
{
SCLogError(SC_PCRE_COMPILE_FAILED, "pcre study failed: %s", eb);
goto error;
}
return;
error:
return;
}
/**
* \brief This function is used to match icode rule option set on a packet with those passed via icode:
*
* \param t pointer to thread vars
* \param det_ctx pointer to the pattern matcher thread
* \param p pointer to the current packet
* \param m pointer to the sigmatch that we will cast into DetectICodeData
*
* \retval 0 no match
* \retval 1 match
*/
int DetectICodeMatch (ThreadVars *t, DetectEngineThreadCtx *det_ctx, Packet *p, Signature *s, SigMatch *m) {
int ret = 0;
uint8_t picode;
DetectICodeData *icd = (DetectICodeData *)m->ctx;
if (PKT_IS_ICMPV4(p)) {
picode = ICMPV4_GET_CODE(p);
} else if (PKT_IS_ICMPV6(p)) {
picode = ICMPV6_GET_CODE(p);
} else {
/* Packet not ICMPv4 nor ICMPv6 */
return ret;
}
switch(icd->mode) {
case DETECT_ICODE_EQ:
ret = (picode == icd->code1) ? 1 : 0;
break;
case DETECT_ICODE_LT:
ret = (picode < icd->code1) ? 1 : 0;
break;
case DETECT_ICODE_GT:
ret = (picode > icd->code1) ? 1 : 0;
break;
case DETECT_ICODE_RN:
ret = (picode >= icd->code1 && picode <= icd->code2) ? 1 : 0;
break;
}
return ret;
}
/**
* \brief This function is used to parse icode options passed via icode: keyword
*
* \param icodestr Pointer to the user provided icode options
*
* \retval icd pointer to DetectICodeData on success
* \retval NULL on failure
*/
DetectICodeData *DetectICodeParse(char *icodestr) {
DetectICodeData *icd = NULL;
char *args[3] = {NULL, NULL, NULL};
#define MAX_SUBSTRINGS 30
int ret = 0, res = 0;
int ov[MAX_SUBSTRINGS];
ret = pcre_exec(parse_regex, parse_regex_study, icodestr, strlen(icodestr), 0, 0, ov, MAX_SUBSTRINGS);
if (ret < 1 || ret > 4) {
SCLogError(SC_PCRE_MATCH_FAILED, "DetectICodeParse: parse error");
goto error;
}
int i;
const char *str_ptr;
for (i = 1; i < ret; i++) {
res = pcre_get_substring((char *)icodestr, ov, MAX_SUBSTRINGS, i, &str_ptr);
if (res < 0) {
SCLogError(SC_PCRE_GET_SUBSTRING_FAILED, "DetectICodeParse: pcre_get_substring failed");
goto error;
}
args[i-1] = (char *)str_ptr;
}
icd = malloc(sizeof(DetectICodeData));
if (icd == NULL) {
SCLogError(SC_ERR_MEM_ALLOC, "Error allocating memory");
goto error;
}
icd->code1 = 0;
icd->code2 = 0;
icd->mode = 0;
/* we have either "<" or ">" */
if (strlen(args[0]) != 0) {
/* we have a third part ("<> y"), therefore it's invalid */
if (args[2] != NULL) {
SCLogInfo("icode: invalid value");
goto error;
}
/* we have only a comparison ("<", ">") */
ByteExtractStringUint8(&icd->code1, 10, 0, args[1]);
if ((strcmp(args[0], ">")) == 0) icd->mode = DETECT_ICODE_GT;
else icd->mode = DETECT_ICODE_LT;
} else { /* no "<", ">" */
/* we have a range ("<>") */
if (args[2] != NULL) {
icd->mode = (uint8_t) DETECT_ICODE_RN;
ByteExtractStringUint8(&icd->code1, 10, 0, args[1]);
ByteExtractStringUint8(&icd->code2, 10, 0, args[2]);
/* we check that the first given value in the range is less than
the second, otherwise we swap them */
if (icd->code1 > icd->code2) {
uint8_t temp = icd->code1;
icd->code1 = icd->code2;
icd->code2 = temp;
}
} else { /* we have an equality */
icd->mode = DETECT_ICODE_EQ;
ByteExtractStringUint8(&icd->code1, 10, 0, args[1]);
}
}
for (i = 0; i < (ret-1); i++) {
if (args[i] != NULL) free(args[i]);
}
return icd;
error:
for (i = 0; i < (ret-1); i++) {
if (args[i] != NULL) free(args[i]);
}
if (icd != NULL) DetectICodeFree(icd);
return NULL;
}
/**
* \brief this function is used to add the parsed icode data into the current signature
*
* \param de_ctx pointer to the Detection Engine Context
* \param s pointer to the Current Signature
* \param m pointer to the Current SigMatch
* \param icodestr pointer to the user provided icode options
*
* \retval 0 on Success
* \retval -1 on Failure
*/
int DetectICodeSetup(DetectEngineCtx *de_ctx, Signature *s, SigMatch *m, char *icodestr) {
DetectICodeData *icd = NULL;
SigMatch *sm = NULL;
icd = DetectICodeParse(icodestr);
if (icd == NULL) goto error;
sm = SigMatchAlloc();
if (sm == NULL) goto error;
sm->type = DETECT_ICODE;
sm->ctx = (void *)icd;
SigMatchAppend(s, m, sm);
return 0;
error:
if (icd != NULL) DetectICodeFree(icd);
if (sm != NULL) free(sm);
return -1;
}
/**
* \brief this function will free memory associated with DetectICodeData
*
* \param ptr pointer to DetectICodeData
*/
void DetectICodeFree(void *ptr) {
DetectICodeData *icd = (DetectICodeData *)ptr;
free(icd);
}
#ifdef UNITTESTS
#include "detect-parse.h"
#include "detect-engine.h"
#include "detect-engine-mpm.h"
/**
* \test DetectICodeParseTest01 is a test for setting a valid icode value
*/
int DetectICodeParseTest01(void) {
DetectICodeData *icd = NULL;
int result = 0;
icd = DetectICodeParse("8");
if (icd != NULL) {
if (icd->code1 == 8 && icd->mode == DETECT_ICODE_EQ)
result = 1;
DetectICodeFree(icd);
}
return result;
}
/**
* \test DetectICodeParseTest02 is a test for setting a valid icode value
* with ">" operator
*/
int DetectICodeParseTest02(void) {
DetectICodeData *icd = NULL;
int result = 0;
icd = DetectICodeParse(">8");
if (icd != NULL) {
if (icd->code1 == 8 && icd->mode == DETECT_ICODE_GT)
result = 1;
DetectICodeFree(icd);
}
return result;
}
/**
* \test DetectICodeParseTest03 is a test for setting a valid icode value
* with "<" operator
*/
int DetectICodeParseTest03(void) {
DetectICodeData *icd = NULL;
int result = 0;
icd = DetectICodeParse("<8");
if (icd != NULL) {
if (icd->code1 == 8 && icd->mode == DETECT_ICODE_LT)
result = 1;
DetectICodeFree(icd);
}
return result;
}
/**
* \test DetectICodeParseTest04 is a test for setting a valid icode value
* with "<>" operator
*/
int DetectICodeParseTest04(void) {
DetectICodeData *icd = NULL;
int result = 0;
icd = DetectICodeParse("8<>20");
if (icd != NULL) {
if (icd->code1 == 8 && icd->code2 == 20 && icd->mode == DETECT_ICODE_RN)
result = 1;
DetectICodeFree(icd);
}
return result;
}
/**
* \test DetectICodeParseTest05 is a test for setting a valid icode value
* with spaces all around
*/
int DetectICodeParseTest05(void) {
DetectICodeData *icd = NULL;
int result = 0;
icd = DetectICodeParse(" 8 ");
if (icd != NULL) {
if (icd->code1 == 8 && icd->mode == DETECT_ICODE_EQ)
result = 1;
DetectICodeFree(icd);
}
return result;
}
/**
* \test DetectICodeParseTest06 is a test for setting a valid icode value
* with ">" operator and spaces all around
*/
int DetectICodeParseTest06(void) {
DetectICodeData *icd = NULL;
int result = 0;
icd = DetectICodeParse(" > 8 ");
if (icd != NULL) {
if (icd->code1 == 8 && icd->mode == DETECT_ICODE_GT)
result = 1;
DetectICodeFree(icd);
}
return result;
}
/**
* \test DetectICodeParseTest07 is a test for setting a valid icode value
* with "<>" operator and spaces all around
*/
int DetectICodeParseTest07(void) {
DetectICodeData *icd = NULL;
int result = 0;
icd = DetectICodeParse(" 8 <> 20 ");
if (icd != NULL) {
if (icd->code1 == 8 && icd->code2 == 20 && icd->mode == DETECT_ICODE_RN)
result = 1;
DetectICodeFree(icd);
}
return result;
}
/**
* \test DetectICodeParseTest08 is a test for setting an invalid icode value
*/
int DetectICodeParseTest08(void) {
DetectICodeData *icd = NULL;
icd = DetectICodeParse("> 8 <> 20");
if (icd == NULL)
return 1;
DetectICodeFree(icd);
return 0;
}
/**
* \test DetectICodeMatchTest01 is a test for checking the working of icode
* keyword by creating 5 rules and matching a crafted packet against
* them. 4 out of 5 rules shall trigger.
*/
int DetectICodeMatchTest01(void) {
Packet p;
Signature *s = NULL;
ThreadVars th_v;
DetectEngineThreadCtx *det_ctx;
int result = 0;
IPV4Hdr ip4h;
ICMPV4Hdr icmpv4h;
memset(&th_v, 0, sizeof(th_v));
memset(&p, 0, sizeof(p));
memset(&ip4h, 0, sizeof(ip4h));
memset(&icmpv4h, 0, sizeof(icmpv4h));
p.src.family = AF_INET;
p.dst.family = AF_INET;
p.proto = IPPROTO_ICMP;
p.ip4h = &ip4h;
icmpv4h.code = 10;
p.icmpv4h = &icmpv4h;
DetectEngineCtx *de_ctx = DetectEngineCtxInit();
if (de_ctx == NULL) {
goto end;
}
de_ctx->flags |= DE_QUIET;
s = de_ctx->sig_list = SigInit(de_ctx,"alert icmp any any -> any any (icode:10; sid:1;)");
if (s == NULL) {
goto end;
}
s = s->next = SigInit(de_ctx,"alert icmp any any -> any any (icode:<15; sid:2;)");
if (s == NULL) {
goto end;
}
s = s->next = SigInit(de_ctx,"alert icmp any any -> any any (icode:>20; sid:3;)");
if (s == NULL) {
goto end;
}
s = s->next = SigInit(de_ctx,"alert icmp any any -> any any (icode:8<>20; sid:4;)");
if (s == NULL) {
goto end;
}
s = s->next = SigInit(de_ctx,"alert icmp any any -> any any (icode:20<>8; sid:5;)");
if (s == NULL) {
goto end;
}
SigGroupBuild(de_ctx);
DetectEngineThreadCtxInit(&th_v, (void *)de_ctx, (void *)&det_ctx);
SigMatchSignatures(&th_v, de_ctx, det_ctx, &p);
if (PacketAlertCheck(&p, 1) == 0) {
SCLogDebug("sid 1 did not alert, but should have");
goto cleanup;
} else if (PacketAlertCheck(&p, 2) == 0) {
SCLogDebug("sid 2 did not alert, but should have");
goto cleanup;
} else if (PacketAlertCheck(&p, 3)) {
SCLogDebug("sid 3 alerted, but should not have");
goto cleanup;
} else if (PacketAlertCheck(&p, 4) == 0) {
SCLogDebug("sid 4 did not alert, but should have");
goto cleanup;
} else if (PacketAlertCheck(&p, 5) == 0) {
SCLogDebug("sid 5 did not alert, but should have");
goto cleanup;
}
result = 1;
cleanup:
SigGroupCleanup(de_ctx);
SigCleanSignatures(de_ctx);
DetectEngineThreadCtxDeinit(&th_v, (void *)det_ctx);
DetectEngineCtxFree(de_ctx);
end:
return result;
}
#endif /* UNITTESTS */
/**
* \brief this function registers unit tests for DetectICode
*/
void DetectICodeRegisterTests(void) {
#ifdef UNITTESTS
UtRegisterTest("DetectICodeParseTest01", DetectICodeParseTest01, 1);
UtRegisterTest("DetectICodeParseTest02", DetectICodeParseTest02, 1);
UtRegisterTest("DetectICodeParseTest03", DetectICodeParseTest03, 1);
UtRegisterTest("DetectICodeParseTest04", DetectICodeParseTest04, 1);
UtRegisterTest("DetectICodeParseTest05", DetectICodeParseTest05, 1);
UtRegisterTest("DetectICodeParseTest06", DetectICodeParseTest06, 1);
UtRegisterTest("DetectICodeParseTest07", DetectICodeParseTest07, 1);
UtRegisterTest("DetectICodeParseTest08", DetectICodeParseTest08, 1);
UtRegisterTest("DetectICodeMatchTest01", DetectICodeMatchTest01, 1);
#endif /* UNITTESTS */
}