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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 Victor Julien <victor@inliniac.net>
*
* Implements the pktvar keyword
*/
#include "suricata-common.h"
#include "decode.h"
#include "detect.h"
#include "detect-parse.h"
#include "threads.h"
#include "pkt-var.h"
#include "detect-pktvar.h"
#include "detect-content.h"
#include "util-spm.h"
#include "util-debug.h"
#include "util-var-name.h"
#define PARSE_REGEX "(.*),(.*)"
static DetectParseRegex parse_regex;
static int DetectPktvarMatch (DetectEngineThreadCtx *, Packet *,
const Signature *, const SigMatchCtx *);
static int DetectPktvarSetup (DetectEngineCtx *, Signature *, const char *);
static void DetectPktvarFree(DetectEngineCtx *, void *data);
void DetectPktvarRegister (void)
{
sigmatch_table[DETECT_PKTVAR].name = "pktvar";
sigmatch_table[DETECT_PKTVAR].Match = DetectPktvarMatch;
sigmatch_table[DETECT_PKTVAR].Setup = DetectPktvarSetup;
sigmatch_table[DETECT_PKTVAR].Free = DetectPktvarFree;
DetectSetupParseRegexes(PARSE_REGEX, &parse_regex);
}
/*
* returns 0: no match
* 1: match
* -1: error
*/
static int DetectPktvarMatch (DetectEngineThreadCtx *det_ctx, Packet *p,
const Signature *s, const SigMatchCtx *ctx)
{
int ret = 0;
const DetectPktvarData *pd = (const DetectPktvarData *)ctx;
PktVar *pv = PktVarGet(p, pd->id);
if (pv != NULL) {
uint8_t *ptr = SpmSearch(pv->value, pv->value_len, pd->content, pd->content_len);
if (ptr != NULL)
ret = 1;
}
return ret;
}
static void DetectPktvarFree(DetectEngineCtx *de_ctx, void *ptr)
{
DetectPktvarData *data = ptr;
if (data != NULL) {
VarNameStoreUnregister(data->id, VAR_TYPE_PKT_VAR);
SCFree(data->content);
SCFree(data);
}
}
static int DetectPktvarSetup (DetectEngineCtx *de_ctx, Signature *s, const char *rawstr)
{
char *varname = NULL, *varcontent = NULL;
int res = 0;
size_t pcre2_len;
uint8_t *content = NULL;
uint16_t len = 0;
pcre2_match_data *match = NULL;
int ret = DetectParsePcreExec(&parse_regex, &match, rawstr, 0, 0);
if (ret != 3) {
SCLogError("\"%s\" is not a valid setting for pktvar.", rawstr);
goto error;
}
const char *str_ptr;
res = pcre2_substring_get_bynumber(match, 1, (PCRE2_UCHAR8 **)&str_ptr, &pcre2_len);
if (res < 0) {
SCLogError("pcre2_substring_get_bynumber failed");
goto error;
}
varname = (char *)str_ptr;
res = pcre2_substring_get_bynumber(match, 2, (PCRE2_UCHAR8 **)&str_ptr, &pcre2_len);
if (res < 0) {
pcre2_substring_free((PCRE2_UCHAR8 *)varname);
SCLogError("pcre2_substring_get_bynumber failed");
goto error;
}
varcontent = (char *)str_ptr;
SCLogDebug("varname '%s', varcontent '%s'", varname, varcontent);
char *parse_content;
if (strlen(varcontent) >= 2 && varcontent[0] == '"' &&
varcontent[strlen(varcontent) - 1] == '"')
{
parse_content = varcontent + 1;
varcontent[strlen(varcontent) - 1] = '\0';
} else {
parse_content = varcontent;
}
ret = DetectContentDataParse("pktvar", parse_content, &content, &len);
if (ret == -1 || content == NULL) {
pcre2_substring_free((PCRE2_UCHAR8 *)varname);
pcre2_substring_free((PCRE2_UCHAR8 *)varcontent);
goto error;
}
pcre2_substring_free((PCRE2_UCHAR8 *)varcontent);
DetectPktvarData *cd = SCCalloc(1, sizeof(DetectPktvarData));
if (unlikely(cd == NULL)) {
pcre2_substring_free((PCRE2_UCHAR8 *)varname);
SCFree(content);
goto error;
}
cd->content = content;
cd->content_len = len;
cd->id = VarNameStoreRegister(varname, VAR_TYPE_PKT_VAR);
pcre2_substring_free((PCRE2_UCHAR8 *)varname);
/* Okay so far so good, lets get this into a SigMatch
* and put it in the Signature. */
SigMatch *sm = SigMatchAlloc();
if (unlikely(sm == NULL)) {
DetectPktvarFree(de_ctx, cd);
goto error;
}
sm->type = DETECT_PKTVAR;
sm->ctx = (SigMatchCtx *)cd;
SigMatchAppendSMToList(s, sm, DETECT_SM_LIST_MATCH);
pcre2_match_data_free(match);
return 0;
error:
if (match) {
pcre2_match_data_free(match);
}
return -1;
}
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