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/* Copyright (C) 2007-2020 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 Eric Leblond <eric@regit.org>
*
* target keyword allow rules writer to specify information about target of the attack
*/
#include "suricata-common.h"
#include "util-unittest.h"
#include "detect-parse.h"
#include "detect-engine.h"
#include "detect-target.h"
/**
* \brief Regex for parsing our keyword options
*/
#define PARSE_REGEX "^\\s*(src_ip|dest_ip)\\s*$"
static DetectParseRegex parse_regex;
/* Prototypes of functions registered in DetectTargetRegister below */
static int DetectTargetSetup (DetectEngineCtx *, Signature *, const char *);
#ifdef UNITTESTS
static void DetectTargetRegisterTests (void);
#endif
/**
* \brief Registration function for target keyword
*
*/
void DetectTargetRegister(void) {
/* keyword name: this is how the keyword is used in a rule */
sigmatch_table[DETECT_TARGET].name = "target";
/* description: listed in "suricata --list-keywords=all" */
sigmatch_table[DETECT_TARGET].desc = "indicate to output module which side is the target of the attack";
/* link to further documentation of the keyword. Normally on the Suricata redmine/wiki */
sigmatch_table[DETECT_TARGET].url = "/rules/meta.html#target";
/* match function is called when the signature is inspected on a packet */
sigmatch_table[DETECT_TARGET].Match = NULL;
/* setup function is called during signature parsing, when the target
* keyword is encountered in the rule */
sigmatch_table[DETECT_TARGET].Setup = DetectTargetSetup;
/* free function is called when the detect engine is freed. Normally at
* shutdown, but also during rule reloads. */
sigmatch_table[DETECT_TARGET].Free = NULL;
/* registers unittests into the system */
#ifdef UNITTESTS
sigmatch_table[DETECT_TARGET].RegisterTests = DetectTargetRegisterTests;
#endif
/* set up the PCRE for keyword parsing */
DetectSetupParseRegexes(PARSE_REGEX, &parse_regex);
}
/**
* \brief This function is used to parse target options passed via target: keyword
*
* \param targetstr Pointer to the user provided target options
*
* \retval 0 on Success
* \retval -1 on Failure
*/
static int DetectTargetParse(Signature *s, const char *targetstr)
{
size_t pcre2len;
char value[10];
pcre2_match_data *match = NULL;
int ret = DetectParsePcreExec(&parse_regex, &match, targetstr, 0, 0);
if (ret < 1) {
SCLogError("pcre_exec parse error, ret %" PRId32 ", string %s", ret, targetstr);
goto error;
}
pcre2len = sizeof(value);
int res = pcre2_substring_copy_bynumber(match, 1, (PCRE2_UCHAR8 *)value, &pcre2len);
if (res < 0) {
SCLogError("pcre2_substring_copy_bynumber failed");
goto error;
}
/* now check key value */
if (!strcmp(value, "src_ip")) {
if (s->flags & SIG_FLAG_DEST_IS_TARGET) {
SCLogError("Conflicting values of target keyword");
goto error;
}
s->flags |= SIG_FLAG_SRC_IS_TARGET;
} else if (!strcmp(value, "dest_ip")) {
if (s->flags & SIG_FLAG_SRC_IS_TARGET) {
SCLogError("Conflicting values of target keyword");
goto error;
}
s->flags |= SIG_FLAG_DEST_IS_TARGET;
} else {
SCLogError("only 'src_ip' and 'dest_ip' are supported as target value");
goto error;
}
pcre2_match_data_free(match);
return 0;
error:
if (match) {
pcre2_match_data_free(match);
}
return -1;
}
/**
* \brief parse the options from the 'target' keyword in the rule into
* the Signature data structure.
*
* \param de_ctx pointer to the Detection Engine Context
* \param s pointer to the Current Signature
* \param targetstr pointer to the user provided target options
*
* \retval 0 on Success
* \retval -1 on Failure
*/
static int DetectTargetSetup(DetectEngineCtx *de_ctx, Signature *s, const char *targetstr)
{
int ret = DetectTargetParse(s, targetstr);
if (ret < 0)
return -1;
return 0;
}
#ifdef UNITTESTS
static int DetectTargetSignatureTest01(void)
{
DetectEngineCtx *de_ctx = DetectEngineCtxInit();
FAIL_IF_NULL(de_ctx);
Signature *sig = DetectEngineAppendSig(de_ctx, "alert ip any any -> any any (target: dest_ip; sid:1; rev:1;)");
FAIL_IF_NULL(sig);
DetectEngineCtxFree(de_ctx);
PASS;
}
/**
* \brief this function registers unit tests for DetectTarget
*/
static void DetectTargetRegisterTests(void)
{
UtRegisterTest("DetectTargetSignatureTest01",
DetectTargetSignatureTest01);
}
#endif /* UNITTESTS */
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