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