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Python integration with c++ binary (not totally working yet)

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This commit is contained in:
DomySh
2022-07-18 18:52:14 +02:00
parent 02fe8f0064
commit 2a5be65feb
12 changed files with 594 additions and 866 deletions
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437
backend/nfqueue/nfqueue.cpp
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@@ -1,421 +1,22 @@
#include <arpa/inet.h>
#include <type_traits>
#include <tins/tins.h>
#include <libmnl/libmnl.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/types.h>
#include <linux/netfilter/nfnetlink_queue.h>
#include <libnetfilter_queue/libnetfilter_queue.h>
#include <linux/netfilter/nfnetlink_conntrack.h>
#include <stdexcept>
#include "classes/regex_filter.hpp"
#include "classes/netfilter.hpp"
#include "utils.hpp"
#include <iostream>
#include <cstring>
#include <cstdlib>
#include <cerrno>
#include <sstream>
#include <thread>
#include <mutex>
#include <jpcre2.hpp>
using namespace std;
using namespace Tins;
typedef jpcre2::select<char> jp;
mutex stdout_mutex;
bool unhexlify(string const &hex, string &newString) {
try{
int len = hex.length();
for(int i=0; i< len; i+=2)
{
std::string byte = hex.substr(i,2);
char chr = (char) (int)strtol(byte.c_str(), NULL, 16);
newString.push_back(chr);
}
return true;
}
catch (...){
return false;
}
}
typedef pair<string,jp::Regex> regex_rule_pair;
typedef vector<regex_rule_pair> regex_rule_vector;
struct regex_rules{
regex_rule_vector output_whitelist, input_whitelist, output_blacklist, input_blacklist;
regex_rule_vector* getByCode(char code){
switch(code){
case 'C': // Client to server Blacklist
return &input_blacklist; break;
case 'c': // Client to server Whitelist
return &input_whitelist; break;
case 'S': // Server to client Blacklist
return &output_blacklist; break;
case 's': // Server to client Whitelist
return &output_whitelist; break;
}
throw invalid_argument( "Expected 'C' 'c' 'S' or 's'" );
}
int add(const char* arg){
//Integrity checks
size_t arg_len = strlen(arg);
if (arg_len < 2 || arg_len%2 != 0){
cerr << "[warning] [regex_rules.add] invalid arg passed (" << arg << "), skipping..." << endl;
return -1;
}
if (arg[0] != '0' && arg[0] != '1'){
cerr << "[warning] [regex_rules.add] invalid is_case_sensitive (" << arg[0] << ") in '" << arg << "', must be '1' or '0', skipping..." << endl;
return -1;
}
if (arg[1] != 'C' && arg[1] != 'c' && arg[1] != 'S' && arg[1] != 's'){
cerr << "[warning] [regex_rules.add] invalid filter_type (" << arg[1] << ") in '" << arg << "', must be 'C', 'c', 'S' or 's', skipping..." << endl;
return -1;
}
string hex(arg+2), expr;
if (!unhexlify(hex, expr)){
cerr << "[warning] [regex_rules.add] invalid hex regex value (" << hex << "), skipping..." << endl;
return -1;
}
//Push regex
jp::Regex regex(expr,arg[0] == '1'?"gS":"giS");
if (regex){
cerr << "[info] [regex_rules.add] adding new regex filter: '" << expr << "'" << endl;
getByCode(arg[1])->push_back(make_pair(string(arg), regex));
} else {
cerr << "[warning] [regex_rules.add] compiling of '" << expr << "' regex failed, skipping..." << endl;
return -1;
}
return 0;
}
bool check(unsigned char* data, const size_t& bytes_transferred, const bool in_input){
string str_data((char *) data, bytes_transferred);
for (regex_rule_pair ele:(in_input?input_blacklist:output_blacklist)){
try{
if(ele.second.match(str_data)){
unique_lock<mutex> lck(stdout_mutex);
cout << "BLOCKED " << ele.first << endl;
return false;
}
} catch(...){
cerr << "[info] [regex_rules.check] Error while matching blacklist regex: " << ele.first << endl;
}
}
for (regex_rule_pair ele:(in_input?input_whitelist:output_whitelist)){
try{
cerr << "[debug] [regex_rules.check] regex whitelist match " << ele.second.getPattern() << endl;
if(!ele.second.match(str_data)){
unique_lock<mutex> lck(stdout_mutex);
cout << "BLOCKED " << ele.first << endl;
return false;
}
} catch(...){
cerr << "[info] [regex_rules.check] Error while matching whitelist regex: " << ele.first << endl;
}
}
return true;
}
};
shared_ptr<regex_rules> regex_config;
typedef bool NetFilterQueueCallback(const uint8_t*,uint32_t);
PDU * find_transport_layer(PDU* pkt){
while(pkt != NULL){
if (pkt->pdu_type() == PDU::TCP || pkt->pdu_type() == PDU::UDP) {
return pkt;
}
pkt = pkt->inner_pdu();
}
return pkt;
}
template <NetFilterQueueCallback callback_func>
class NetfilterQueue {
public:
size_t BUF_SIZE = 0xffff + (MNL_SOCKET_BUFFER_SIZE/2);
char *buf = NULL;
unsigned int portid;
u_int16_t queue_num;
struct mnl_socket* nl = NULL;
NetfilterQueue(u_int16_t queue_num): queue_num(queue_num) {
nl = mnl_socket_open(NETLINK_NETFILTER);
if (nl == NULL) { throw runtime_error( "mnl_socket_open" );}
if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
mnl_socket_close(nl);
throw runtime_error( "mnl_socket_bind" );
}
portid = mnl_socket_get_portid(nl);
buf = (char*) malloc(BUF_SIZE);
if (!buf) {
mnl_socket_close(nl);
throw runtime_error( "allocate receive buffer" );
}
if (send_config_cmd(NFQNL_CFG_CMD_BIND) < 0) {
_clear();
throw runtime_error( "mnl_socket_send" );
}
//TEST if BIND was successful
if (send_config_cmd(NFQNL_CFG_CMD_NONE) < 0) { // SEND A NONE cmmand to generate an error meessage
_clear();
throw runtime_error( "mnl_socket_send" );
}
if (recv_packet() == -1) { //RECV the error message
_clear();
throw std::runtime_error( "mnl_socket_recvfrom" );
}
struct nlmsghdr *nlh = (struct nlmsghdr *) buf;
if (nlh->nlmsg_type != NLMSG_ERROR) {
_clear();
throw runtime_error( "unexpected packet from kernel (expected NLMSG_ERROR packet)" );
}
//nfqnl_msg_config_cmd
nlmsgerr* error_msg = (nlmsgerr *)mnl_nlmsg_get_payload(nlh);
// error code taken from the linux kernel:
// https://elixir.bootlin.com/linux/v5.18.12/source/include/linux/errno.h#L27
#define ENOTSUPP 524 /* Operation is not supported */
if (error_msg->error != -ENOTSUPP) {
_clear();
throw std::invalid_argument( "queueid is already busy" );
}
//END TESTING BIND
nlh = nfq_nlmsg_put(buf, NFQNL_MSG_CONFIG, queue_num);
nfq_nlmsg_cfg_put_params(nlh, NFQNL_COPY_PACKET, 0xffff);
mnl_attr_put_u32(nlh, NFQA_CFG_FLAGS, htonl(NFQA_CFG_F_GSO));
mnl_attr_put_u32(nlh, NFQA_CFG_MASK, htonl(NFQA_CFG_F_GSO));
if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
_clear();
throw runtime_error( "mnl_socket_send" );
}
}
void run(){
/*
* ENOBUFS is signalled to userspace when packets were lost
* on kernel side. In most cases, userspace isn't interested
* in this information, so turn it off.
*/
int ret = 1;
mnl_socket_setsockopt(nl, NETLINK_NO_ENOBUFS, &ret, sizeof(int));
for (;;) {
ret = recv_packet();
if (ret == -1) {
throw std::runtime_error( "mnl_socket_recvfrom" );
}
ret = mnl_cb_run(buf, ret, 0, portid, queue_cb, nl);
if (ret < 0){
throw std::runtime_error( "mnl_cb_run" );
}
}
}
~NetfilterQueue() {
send_config_cmd(NFQNL_CFG_CMD_UNBIND);
_clear();
}
private:
ssize_t send_config_cmd(nfqnl_msg_config_cmds cmd){
struct nlmsghdr *nlh = nfq_nlmsg_put(buf, NFQNL_MSG_CONFIG, queue_num);
nfq_nlmsg_cfg_put_cmd(nlh, AF_INET, cmd);
return mnl_socket_sendto(nl, nlh, nlh->nlmsg_len);
}
ssize_t recv_packet(){
return mnl_socket_recvfrom(nl, buf, BUF_SIZE);
}
void _clear(){
if (buf != NULL) {
free(buf);
buf = NULL;
}
mnl_socket_close(nl);
}
static int queue_cb(const struct nlmsghdr *nlh, void *data)
{
struct mnl_socket* nl = (struct mnl_socket*)data;
//Extract attributes from the nlmsghdr
struct nlattr *attr[NFQA_MAX+1] = {};
if (nfq_nlmsg_parse(nlh, attr) < 0) {
perror("problems parsing");
return MNL_CB_ERROR;
}
if (attr[NFQA_PACKET_HDR] == NULL) {
fputs("metaheader not set\n", stderr);
return MNL_CB_ERROR;
}
//Get Payload
uint16_t plen = mnl_attr_get_payload_len(attr[NFQA_PAYLOAD]);
void *payload = mnl_attr_get_payload(attr[NFQA_PAYLOAD]);
//Return result to the kernel
struct nfqnl_msg_packet_hdr *ph = (nfqnl_msg_packet_hdr*) mnl_attr_get_payload(attr[NFQA_PACKET_HDR]);
struct nfgenmsg *nfg = (nfgenmsg *)mnl_nlmsg_get_payload(nlh);
char buf[MNL_SOCKET_BUFFER_SIZE];
struct nlmsghdr *nlh_verdict;
struct nlattr *nest;
nlh_verdict = nfq_nlmsg_put(buf, NFQNL_MSG_VERDICT, ntohs(nfg->res_id));
/*
This define allow to avoid to allocate new heap memory for each packet.
The code under this comment is replicated for ipv6 and ip
Better solutions are welcome. :)
*/
#define PKT_HANDLE \
PDU *transport_layer = find_transport_layer(&packet); \
if(transport_layer->inner_pdu() == nullptr || transport_layer == nullptr){ \
nfq_nlmsg_verdict_put(nlh_verdict, ntohl(ph->packet_id), NF_ACCEPT ); \
}else{ \
int size = transport_layer->inner_pdu()->size(); \
if(callback_func((const uint8_t*)payload+plen - size, size)){ \
nfq_nlmsg_verdict_put(nlh_verdict, ntohl(ph->packet_id), NF_ACCEPT ); \
} else{ \
if (transport_layer->pdu_type() == PDU::TCP){ \
((TCP *)transport_layer)->release_inner_pdu(); \
((TCP *)transport_layer)->set_flag(TCP::FIN,1); \
((TCP *)transport_layer)->set_flag(TCP::ACK,1); \
((TCP *)transport_layer)->set_flag(TCP::SYN,0); \
nfq_nlmsg_verdict_put_pkt(nlh_verdict, packet.serialize().data(), packet.size()); \
nfq_nlmsg_verdict_put(nlh_verdict, ntohl(ph->packet_id), NF_ACCEPT ); \
}else{ \
nfq_nlmsg_verdict_put(nlh_verdict, ntohl(ph->packet_id), NF_DROP ); \
} \
} \
}
// Check IP protocol version
if ( (((uint8_t*)payload)[0] & 0xf0) == 0x40 ){
IP packet = IP((uint8_t*)payload,plen);
PKT_HANDLE
}else{
IPv6 packet = IPv6((uint8_t*)payload,plen);
PKT_HANDLE
}
/* example to set the connmark. First, start NFQA_CT section: */
nest = mnl_attr_nest_start(nlh_verdict, NFQA_CT);
/* then, add the connmark attribute: */
mnl_attr_put_u32(nlh_verdict, CTA_MARK, htonl(42));
/* more conntrack attributes, e.g. CTA_LABELS could be set here */
/* end conntrack section */
mnl_attr_nest_end(nlh_verdict, nest);
if (mnl_socket_sendto(nl, nlh_verdict, nlh_verdict->nlmsg_len) < 0) {
throw std::runtime_error( "mnl_socket_send" );
}
return MNL_CB_OK;
}
};
template <NetFilterQueueCallback func>
class NFQueueSequence{
private:
vector<NetfilterQueue<func> *> nfq;
uint16_t _init;
uint16_t _end;
vector<thread> threads;
public:
static const int QUEUE_BASE_NUM = 1000;
NFQueueSequence(uint16_t seq_len){
if (seq_len <= 0) throw invalid_argument("seq_len <= 0");
nfq = vector<NetfilterQueue<func>*>(seq_len);
_init = QUEUE_BASE_NUM;
while(nfq[0] == NULL){
if (_init+seq_len-1 >= 65536){
throw runtime_error("NFQueueSequence: too many queues!");
}
for (int i=0;i<seq_len;i++){
try{
nfq[i] = new NetfilterQueue<func>(_init+i);
}catch(const invalid_argument e){
for(int j = 0; j < i; j++) {
delete nfq[j];
nfq[j] = nullptr;
}
_init += seq_len - i;
break;
}
}
}
_end = _init + seq_len - 1;
}
void start(){
if (threads.size() != 0) throw runtime_error("NFQueueSequence: already started!");
for (int i=0;i<nfq.size();i++){
threads.push_back(thread(&NetfilterQueue<func>::run, nfq[i]));
}
}
void join(){
for (int i=0;i<nfq.size();i++){
threads[i].join();
}
threads.clear();
}
uint16_t init(){
return _init;
}
uint16_t end(){
return _end;
}
~NFQueueSequence(){
for (int i=0;i<nfq.size();i++){
delete nfq[i];
}
}
};
bool is_sudo(){
return getuid() == 0;
}
void config_updater (){
string line, data;
while (true){
getline(cin, line);
if (cin.eof()){
cerr << "[fatal] [upfdater] cin.eof()" << endl;
exit(EXIT_FAILURE);
}
if (cin.bad()){
cerr << "[fatal] [upfdater] cin.bad() != 0" << endl;
cerr << "[fatal] [upfdater] cin.bad()" << endl;
exit(EXIT_FAILURE);
}
cerr << "[info] [updater] Updating configuration with line " << line << endl;
@@ -423,7 +24,9 @@ void config_updater (){
regex_rules *regex_new_config = new regex_rules();
while(!config_stream.eof()){
config_stream >> data;
regex_new_config->add(data.c_str());
if (data != "" && data != "\n"){
regex_new_config->add(data.c_str());
}
}
regex_config.reset(regex_new_config);
cerr << "[info] [updater] Config update done" << endl;
@@ -456,21 +59,3 @@ int main(int argc, char *argv[])
config_updater();
}
/*
libpcre2-dev
libnetfilter-queue-dev
libtins-dev
libmnl-dev
c++ nfqueue.cpp -o nfqueue -pthread -lpcre2-8 -ltins -lnetfilter_queue -lmnl
WORKDIR /tmp/
RUN git clone --branch release https://github.com/jpcre2/jpcre2
WORKDIR /tmp/jpcre2
RUN ./configure; make; make install
WORKDIR /
*/