mirror of https://github.com/OISF/suricata
detect-ftpdata: match on ftp-data operation
This keyword mathes on ftp operation STOR and RETR. It will allow rules writer to select if the alert has to be on a put or a fetch operation. It is now possible to write a signature like: alert ftp-data any any -> any any (msg:"FTP data get firwmare"; ftdata_command:retr; sid:2; rev:1;) to alert when a file is retrieved from a FTP server.pull/3108/head
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/* Copyright (C) 2017 Open Information Security Foundation
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*
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* You can copy, redistribute or modify this Program under the terms of
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* the GNU General Public License version 2 as published by the Free
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* Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* version 2 along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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/**
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* \file
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*
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* \author Eric Leblond <eric@regit.org>
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*
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* Match on ftp command used to trigger a ftp data transfer
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*/
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#include "suricata-common.h"
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#include "util-unittest.h"
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#include "detect-parse.h"
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#include "detect-engine.h"
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#include "detect-engine-state.h"
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#include "app-layer-ftp.h"
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#include "detect-ftpdata.h"
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/**
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* \brief Regex for parsing our keyword options
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*/
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#define PARSE_REGEX "^\\s*(stor|retr)\\s*$"
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static pcre *parse_regex;
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static pcre_extra *parse_regex_study;
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/* Prototypes of functions registered in DetectFtpdataRegister below */
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static int DetectFtpdataMatch(ThreadVars *, DetectEngineThreadCtx *,
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Flow *, uint8_t, void *, void *,
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const Signature *, const SigMatchCtx *);
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static int DetectFtpdataSetup (DetectEngineCtx *, Signature *, const char *);
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static void DetectFtpdataFree (void *);
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static void DetectFtpdataRegisterTests (void);
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static int DetectEngineInspectFtpdataGeneric(ThreadVars *tv,
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DetectEngineCtx *de_ctx, DetectEngineThreadCtx *det_ctx,
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const Signature *s, const SigMatchData *smd,
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Flow *f, uint8_t flags, void *alstate,
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void *txv, uint64_t tx_id);
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static int g_ftpdata_buffer_id = 0;
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/**
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* \brief Registration function for ftpcommand: keyword
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*
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* This function is called once in the 'lifetime' of the engine.
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*/
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void DetectFtpdataRegister(void) {
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/* keyword name: this is how the keyword is used in a rule */
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sigmatch_table[DETECT_FTPDATA].name = "ftpdata_command";
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/* description: listed in "suricata --list-keywords=all" */
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sigmatch_table[DETECT_FTPDATA].desc = "match FTP command triggering a FTP data channel";
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sigmatch_table[DETECT_FTPDATA].url = DOC_URL DOC_VERSION "/rules/ftp-keywords#ftpdata_command";
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sigmatch_table[DETECT_FTPDATA].AppLayerTxMatch = DetectFtpdataMatch;
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/* setup function is called during signature parsing, when the ftpcommand
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* keyword is encountered in the rule */
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sigmatch_table[DETECT_FTPDATA].Setup = DetectFtpdataSetup;
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/* free function is called when the detect engine is freed. Normally at
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* shutdown, but also during rule reloads. */
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sigmatch_table[DETECT_FTPDATA].Free = DetectFtpdataFree;
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/* registers unittests into the system */
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sigmatch_table[DETECT_FTPDATA].RegisterTests = DetectFtpdataRegisterTests;
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DetectAppLayerInspectEngineRegister("ftpdata_command",
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ALPROTO_FTPDATA, SIG_FLAG_TOSERVER, 0,
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DetectEngineInspectFtpdataGeneric);
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DetectAppLayerInspectEngineRegister("ftpdata_command",
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ALPROTO_FTPDATA, SIG_FLAG_TOCLIENT, 0,
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DetectEngineInspectFtpdataGeneric);
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g_ftpdata_buffer_id = DetectBufferTypeGetByName("ftpdata_command");
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/* set up the PCRE for keyword parsing */
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DetectSetupParseRegexes(PARSE_REGEX, &parse_regex, &parse_regex_study);
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}
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static int DetectEngineInspectFtpdataGeneric(ThreadVars *tv,
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DetectEngineCtx *de_ctx, DetectEngineThreadCtx *det_ctx,
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const Signature *s, const SigMatchData *smd,
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Flow *f, uint8_t flags, void *alstate,
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void *txv, uint64_t tx_id)
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{
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return DetectEngineInspectGenericList(tv, de_ctx, det_ctx, s, smd,
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f, flags, alstate, txv, tx_id);
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}
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/**
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* \brief This function is used to check matches from the FTP App Layer Parser
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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
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* \retval 0 no match
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* \retval 1 match
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*/
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static int DetectFtpdataMatch(ThreadVars *t, DetectEngineThreadCtx *det_ctx,
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Flow *f, uint8_t flags,
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void *state, void *txv,
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const Signature *s, const SigMatchCtx *m)
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{
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const DetectFtpdataData *ftpcommandd = (const DetectFtpdataData *) m;
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const FtpDataState *ftp_state = (const FtpDataState *)state;
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if (ftp_state == NULL)
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return 0;
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if (ftpcommandd->command == ftp_state->command) {
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/* Only match if the flow is in the good direction */
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if ((flags & STREAM_TOSERVER) && (ftpcommandd->command == FTP_COMMAND_RETR)) {
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return 0;
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} else if ((flags & STREAM_TOCLIENT) && (ftpcommandd->command == FTP_COMMAND_STOR)) {
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return 0;
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}
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return 1;
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}
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return 0;
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}
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/**
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* \brief This function is used to parse ftpcommand options passed via ftpcommand: keyword
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*
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* \param ftpcommandstr Pointer to the user provided ftpcommand options
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*
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* \retval ftpcommandd pointer to DetectFtpdataData on success
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* \retval NULL on failure
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*/
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static DetectFtpdataData *DetectFtpdataParse(const char *ftpcommandstr)
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{
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DetectFtpdataData *ftpcommandd = NULL;
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char arg1[5] = "";
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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,
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ftpcommandstr, strlen(ftpcommandstr),
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0, 0, ov, MAX_SUBSTRINGS);
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if (ret != 2) {
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SCLogError(SC_ERR_PCRE_MATCH, "parse error, ret %" PRId32 "", ret);
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goto error;
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}
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res = pcre_copy_substring((char *) ftpcommandstr, ov, MAX_SUBSTRINGS, 1, arg1, sizeof(arg1));
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if (res < 0) {
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SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre_copy_substring failed");
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goto error;
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}
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SCLogDebug("Arg1 \"%s\"", arg1);
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ftpcommandd = SCMalloc(sizeof (DetectFtpdataData));
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if (unlikely(ftpcommandd == NULL))
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goto error;
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if (!strcmp(arg1, "stor")) {
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ftpcommandd->command = FTP_COMMAND_STOR;
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} else if (!strcmp(arg1, "retr")) {
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ftpcommandd->command = FTP_COMMAND_RETR;
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} else {
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SCLogError(SC_ERR_NOT_SUPPORTED, "Invalid command value");
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goto error;
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}
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return ftpcommandd;
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error:
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if (ftpcommandd)
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SCFree(ftpcommandd);
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return NULL;
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}
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/**
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* \brief parse the options from the 'ftpcommand' keyword in the rule into
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* the Signature data structure.
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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 ftpcommandstr pointer to the user provided ftpcommand 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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static int DetectFtpdataSetup(DetectEngineCtx *de_ctx, Signature *s, const char *ftpcommandstr)
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{
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DetectFtpdataData *ftpcommandd = NULL;
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SigMatch *sm = NULL;
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if (DetectSignatureSetAppProto(s, ALPROTO_FTPDATA) != 0)
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return -1;
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ftpcommandd = DetectFtpdataParse(ftpcommandstr);
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if (ftpcommandd == NULL)
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goto error;
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sm = SigMatchAlloc();
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if (sm == NULL)
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goto error;
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sm->type = DETECT_FTPDATA;
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sm->ctx = (void *)ftpcommandd;
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s->flags |= SIG_FLAG_STATE_MATCH;
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SigMatchAppendSMToList(s, sm, g_ftpdata_buffer_id);
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return 0;
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error:
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if (ftpcommandd != NULL)
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DetectFtpdataFree(ftpcommandd);
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if (sm != NULL)
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SCFree(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 DetectFtpdataData
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*
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* \param ptr pointer to DetectFtpdataData
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*/
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static void DetectFtpdataFree(void *ptr) {
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DetectFtpdataData *ftpcommandd = (DetectFtpdataData *)ptr;
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/* do more specific cleanup here, if needed */
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SCFree(ftpcommandd);
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}
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#if UNITTESTS
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static int DetectFtpdataParseTest01(void)
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{
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DetectFtpdataData *ftpcommandd = DetectFtpdataParse("stor");
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FAIL_IF_NULL(ftpcommandd);
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FAIL_IF(!(ftpcommandd->command == FTP_COMMAND_STOR));
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DetectFtpdataFree(ftpcommandd);
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PASS;
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}
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static int DetectFtpdataSignatureTest01(void)
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{
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DetectEngineCtx *de_ctx = DetectEngineCtxInit();
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FAIL_IF_NULL(de_ctx);
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Signature *sig = DetectEngineAppendSig(de_ctx, "alert ip any any -> any any (ftpdata_command:stor; sid:1; rev:1;)");
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FAIL_IF_NULL(sig);
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DetectEngineCtxFree(de_ctx);
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PASS;
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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 DetectFtpdata
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*/
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void DetectFtpdataRegisterTests(void) {
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#ifdef UNITTESTS
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UtRegisterTest("DetectFtpdataParseTest01", DetectFtpdataParseTest01);
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UtRegisterTest("DetectFtpdataSignatureTest01",
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DetectFtpdataSignatureTest01);
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#endif /* UNITTESTS */
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}
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@ -0,0 +1,43 @@
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/* Copyright (C) 2017 Open Information Security Foundation
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*
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* You can copy, redistribute or modify this Program under the terms of
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* the GNU General Public License version 2 as published by the Free
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* Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* version 2 along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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/**
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* \file
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*
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* \author Eric Leblond <eric@regit.org>
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*/
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#ifndef __DETECT_FTPDATA_H__
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#define __DETECT_FTPDATA_H__
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#include "detect-engine.h"
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#include "app-layer-ftp.h"
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/** Per keyword data. This is set up by the DetectFtpcommandSetup() function.
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* Each signature will have an instance of DetectFtpcommandData per occurence
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* of the keyword.
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* The structure should be considered static/readonly after initialization.
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*/
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typedef struct DetectFtpdataData_ {
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FtpRequestCommand command;
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} DetectFtpdataData;
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/** \brief registers the keyword into the engine. Called from
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* detect.c::SigTableSetup() */
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void DetectFtpdataRegister(void);
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#endif /* __DETECT_FTPDATA_H__ */
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