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suricata/src/detect-filename.c

336 lines
9.0 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 Pablo Rincon <pablo.rincon.crespo@gmail.com>
*
*/
#include "suricata-common.h"
#include "threads.h"
#include "debug.h"
#include "decode.h"
#include "detect.h"
#include "detect-parse.h"
#include "detect-engine.h"
#include "detect-engine-mpm.h"
#include "detect-engine-state.h"
#include "flow.h"
#include "flow-var.h"
#include "flow-util.h"
#include "util-debug.h"
#include "util-spm-bm.h"
#include "util-unittest.h"
#include "util-unittest-helper.h"
#include "app-layer.h"
#include "stream-tcp.h"
#include "detect-filename.h"
/**
* \brief Regex for parsing the protoversion string
*/
#define PARSE_REGEX "^\\s*\"?\\s*(.+)\\s*\"?\\s*$"
static pcre *parse_regex;
static pcre_extra *parse_regex_study;
int DetectFilenameMatch (ThreadVars *, DetectEngineThreadCtx *, Flow *, uint8_t, void *, Signature *, SigMatch *);
static int DetectFilenameSetup (DetectEngineCtx *, Signature *, char *);
void DetectFilenameRegisterTests(void);
void DetectFilenameFree(void *);
/**
* \brief Registration function for keyword: filename
*/
void DetectFilenameRegister(void) {
sigmatch_table[DETECT_FILENAME].name = "filename";
sigmatch_table[DETECT_FILENAME].Match = NULL;
sigmatch_table[DETECT_FILENAME].AppLayerMatch = DetectFilenameMatch;
sigmatch_table[DETECT_FILENAME].alproto = ALPROTO_HTTP;
sigmatch_table[DETECT_FILENAME].Setup = DetectFilenameSetup;
sigmatch_table[DETECT_FILENAME].Free = DetectFilenameFree;
sigmatch_table[DETECT_FILENAME].RegisterTests = DetectFilenameRegisterTests;
const char *eb;
int eo;
int opts = 0;
SCLogDebug("registering filename rule option");
parse_regex = pcre_compile(PARSE_REGEX, opts, &eb, &eo, NULL);
if (parse_regex == NULL) {
SCLogError(SC_ERR_PCRE_COMPILE, "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_ERR_PCRE_STUDY, "pcre study failed: %s", eb);
goto error;
}
return;
error:
return;
}
/**
* \brief match the specified filename
*
* \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 DetectFilenameData
*
* \retval 0 no match
* \retval 1 match
*/
int DetectFilenameMatch (ThreadVars *t, DetectEngineThreadCtx *det_ctx, Flow *f, uint8_t flags, void *state, Signature *s, SigMatch *m)
{
SCEnter();
int ret = 0;
DetectFilenameData *filename = m->ctx;
SCMutexLock(&f->files_m);
if (f->files != NULL && f->files->cnt > 0) {
FlowFile *file = f->files->start;
for (; file != NULL; file = file->next) {
if (file != NULL && file->name != NULL &&
BoyerMooreNocase(filename->name, filename->len, file->name,
file->name_len, filename->bm_ctx->bmGs, filename->bm_ctx->bmBc) != NULL)
{
ret = 1;
SCLogDebug("File %s found", file->name);
/* Stop searching */
break;
}
}
}
SCMutexUnlock(&f->files_m);
SCReturnInt(ret);
}
/**
* \brief This function is used to parse IPV4 ip_id passed via keyword: "id"
*
* \param idstr Pointer to the user provided id option
*
* \retval filename pointer to DetectFilenameData on success
* \retval NULL on failure
*/
DetectFilenameData *DetectFilenameParse (char *str)
{
DetectFilenameData *filename = NULL;
#define MAX_SUBSTRINGS 30
int ret = 0, res = 0;
int ov[MAX_SUBSTRINGS];
ret = pcre_exec(parse_regex, parse_regex_study, str, strlen(str), 0, 0,
ov, MAX_SUBSTRINGS);
if (ret < 1 || ret > 3) {
SCLogError(SC_ERR_PCRE_MATCH, "invalid filename option");
goto error;
}
if (ret > 1) {
const char *str_ptr;
res = pcre_get_substring((char *)str, ov, MAX_SUBSTRINGS, 1, &str_ptr);
if (res < 0) {
SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre_get_substring failed");
goto error;
}
/* We have a correct filename option */
filename = SCMalloc(sizeof(DetectFilenameData));
if (filename == NULL)
goto error;
memset(filename, 0x00, sizeof(DetectFilenameData));
/* Remove quotes if any and copy the filename */
if (str_ptr[0] == '\"') {
filename->name = (uint8_t *)SCStrdup((char*)str_ptr + 1);
} else {
filename->name = (uint8_t *)SCStrdup((char*)str_ptr);
}
if (filename->name[strlen((char *)filename->name) - 1] == '\"') {
filename->name[strlen((char *)filename->name) - 1] = '\0';
}
if (filename->name == NULL) {
goto error;
}
filename->len = strlen((char *) filename->name);
filename->bm_ctx = BoyerMooreCtxInit(filename->name, filename->len);
if (filename->bm_ctx == NULL) {
goto error;
}
BoyerMooreCtxToNocase(filename->bm_ctx, filename->name, filename->len);
SCLogDebug("will look for filename %s", filename->name);
}
return filename;
error:
if (filename != NULL)
DetectFilenameFree(filename);
return NULL;
}
/**
* \brief this function is used to parse filename options
* \brief into the current signature
*
* \param de_ctx pointer to the Detection Engine Context
* \param s pointer to the Current Signature
* \param str pointer to the user provided "filename" option
*
* \retval 0 on Success
* \retval -1 on Failure
*/
static int DetectFilenameSetup (DetectEngineCtx *de_ctx, Signature *s, char *str)
{
DetectFilenameData *filename = NULL;
SigMatch *sm = NULL;
filename = DetectFilenameParse(str);
if (filename == NULL)
goto error;
/* Okay so far so good, lets get this into a SigMatch
* and put it in the Signature. */
sm = SigMatchAlloc();
if (sm == NULL)
goto error;
sm->type = DETECT_FILENAME;
sm->ctx = (void *)filename;
SigMatchAppendAppLayer(s, sm);
if (s->alproto != ALPROTO_UNKNOWN && s->alproto != ALPROTO_HTTP) {
SCLogError(SC_ERR_CONFLICTING_RULE_KEYWORDS, "rule contains conflicting keywords.");
goto error;
}
AppLayerHtpNeedFileInspection();
s->alproto = ALPROTO_HTTP;
return 0;
error:
if (filename != NULL)
DetectFilenameFree(filename);
if (sm != NULL)
SCFree(sm);
return -1;
}
/**
* \brief this function will free memory associated with DetectFilenameData
*
* \param filename pointer to DetectFilenameData
*/
void DetectFilenameFree(void *ptr) {
if (ptr != NULL) {
DetectFilenameData *filename = (DetectFilenameData *)ptr;
if (filename->bm_ctx != NULL) {
BoyerMooreCtxDeInit(filename->bm_ctx);
}
SCFree(filename);
}
}
#ifdef UNITTESTS /* UNITTESTS */
/**
* \test DetectFilenameTestParse01
*/
int DetectFilenameTestParse01 (void) {
DetectFilenameData *dnd = DetectFilenameParse("secret.pdf");
if (dnd != NULL) {
DetectFilenameFree(dnd);
return 1;
}
return 0;
}
/**
* \test DetectFilenameTestParse02
*/
int DetectFilenameTestParse02 (void) {
int result = 0;
DetectFilenameData *dnd = DetectFilenameParse("\"backup.tar.gz\"");
if (dnd != NULL) {
if (dnd->len == 13 && memcmp(dnd->name, "backup.tar.gz", 13) == 0) {
result = 1;
}
DetectFilenameFree(dnd);
return result;
}
return 0;
}
/**
* \test DetectFilenameTestParse03
*/
int DetectFilenameTestParse03 (void) {
int result = 0;
DetectFilenameData *dnd = DetectFilenameParse("cmd.exe");
if (dnd != NULL) {
if (dnd->len == 7 && memcmp(dnd->name, "cmd.exe", 7) == 0) {
result = 1;
}
DetectFilenameFree(dnd);
return result;
}
return 0;
}
#endif /* UNITTESTS */
/**
* \brief this function registers unit tests for DetectFilename
*/
void DetectFilenameRegisterTests(void) {
#ifdef UNITTESTS /* UNITTESTS */
UtRegisterTest("DetectFilenameTestParse01", DetectFilenameTestParse01, 1);
UtRegisterTest("DetectFilenameTestParse02", DetectFilenameTestParse02, 1);
UtRegisterTest("DetectFilenameTestParse03", DetectFilenameTestParse03, 1);
#endif /* UNITTESTS */
}