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suricata/src/detect-mqtt-subscribe-topic.c

143 lines
4.5 KiB
C

/* Copyright (C) 2020-2022 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 Sascha Steinbiss <sascha@steinbiss.name>
*/
#include "suricata-common.h"
#include "app-layer.h"
#include "app-layer-parser.h"
#include "conf.h"
#include "decode.h"
#include "detect.h"
#include "detect-content.h"
#include "detect-parse.h"
#include "detect-pcre.h"
#include "detect-engine.h"
#include "detect-engine-content-inspection.h"
#include "detect-engine-mpm.h"
#include "detect-engine-prefilter.h"
#include "detect-mqtt-subscribe-topic.h"
#include "util-unittest.h"
#include "util-unittest-helper.h"
#include "rust-bindings.h"
#include "threads.h"
#include "flow.h"
#include "flow-util.h"
#include "flow-var.h"
#include "util-debug.h"
#include "util-spm.h"
#include "util-print.h"
#include "util-profiling.h"
static int DetectMQTTSubscribeTopicSetup(DetectEngineCtx *, Signature *, const char *);
static int g_mqtt_subscribe_topic_buffer_id = 0;
static uint32_t subscribe_topic_match_limit = 100;
static InspectionBuffer *MQTTSubscribeTopicGetData(DetectEngineThreadCtx *det_ctx,
const DetectEngineTransforms *transforms, Flow *f, const uint8_t flags, void *txv,
int list_id, uint32_t local_id)
{
SCEnter();
if (subscribe_topic_match_limit > 0 && local_id >= subscribe_topic_match_limit)
return NULL;
InspectionBuffer *buffer = InspectionBufferMultipleForListGet(det_ctx, list_id, local_id);
if (buffer == NULL)
return NULL;
if (buffer->initialized)
return buffer;
const uint8_t *data;
uint32_t data_len;
if (rs_mqtt_tx_get_subscribe_topic(txv, local_id, &data, &data_len) == 0) {
InspectionBufferSetupMultiEmpty(buffer);
return NULL;
}
InspectionBufferSetupMulti(buffer, transforms, data, data_len);
buffer->flags = DETECT_CI_FLAGS_SINGLE;
SCReturnPtr(buffer, "InspectionBuffer");
}
/**
* \brief Registration function for keyword: mqtt.subscribe.topic
*/
void DetectMQTTSubscribeTopicRegister (void)
{
sigmatch_table[DETECT_AL_MQTT_SUBSCRIBE_TOPIC].name = "mqtt.subscribe.topic";
sigmatch_table[DETECT_AL_MQTT_SUBSCRIBE_TOPIC].desc = "sticky buffer to match MQTT SUBSCRIBE topic";
sigmatch_table[DETECT_AL_MQTT_SUBSCRIBE_TOPIC].url = "/rules/mqtt-keywords.html#mqtt-subscribe-topic";
sigmatch_table[DETECT_AL_MQTT_SUBSCRIBE_TOPIC].Setup = DetectMQTTSubscribeTopicSetup;
sigmatch_table[DETECT_AL_MQTT_SUBSCRIBE_TOPIC].flags |= SIGMATCH_NOOPT;
sigmatch_table[DETECT_AL_MQTT_SUBSCRIBE_TOPIC].flags |= SIGMATCH_INFO_STICKY_BUFFER;
intmax_t val = 0;
if (ConfGetInt("app-layer.protocols.mqtt.subscribe-topic-match-limit", &val)) {
subscribe_topic_match_limit = val;
}
if (subscribe_topic_match_limit <= 0) {
SCLogDebug("Using unrestricted MQTT SUBSCRIBE topic matching");
} else {
SCLogDebug("Using MQTT SUBSCRIBE topic match-limit setting of: %u",
subscribe_topic_match_limit);
}
DetectAppLayerMultiRegister("mqtt.subscribe.topic", ALPROTO_MQTT, SIG_FLAG_TOSERVER, 1,
MQTTSubscribeTopicGetData, 1, 1);
DetectBufferTypeSetDescriptionByName("mqtt.subscribe.topic",
"subscribe topic query");
g_mqtt_subscribe_topic_buffer_id = DetectBufferTypeGetByName("mqtt.subscribe.topic");
DetectBufferTypeSupportsMultiInstance("mqtt.subscribe.topic");
}
/**
* \brief setup the sticky buffer keyword used in the rule
*
* \param de_ctx Pointer to the Detection Engine Context
* \param s Pointer to the Signature to which the current keyword belongs
* \param str Should hold an empty string always
*
* \retval 0 On success
* \retval -1 On failure
*/
static int DetectMQTTSubscribeTopicSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
{
if (DetectBufferSetActiveList(de_ctx, s, g_mqtt_subscribe_topic_buffer_id) < 0)
return -1;
if (DetectSignatureSetAppProto(s, ALPROTO_MQTT) < 0)
return -1;
return 0;
}