Files
firegex-traffic-viewer/backend/binsrc/classes/nfqueue.cpp
2025-04-12 20:34:45 +02:00

589 lines
16 KiB
C++

#ifndef NFQUEUE_CLASS_CPP
#define NFQUEUE_CLASS_CPP
#include <libnetfilter_queue/libnetfilter_queue.h>
#include <linux/netfilter/nfnetlink_queue.h>
#include <tins/tcp_ip/stream_identifier.h>
#include <libmnl/libmnl.h>
#include <tins/tins.h>
#include <map>
using namespace std;
namespace Firegex{
namespace NfQueue{
enum class FilterAction{ DROP, ACCEPT, MANGLE, NOACTION };
enum class L4Proto { TCP, UDP, RAW };
typedef Tins::TCPIP::StreamIdentifier stream_id;
struct tcp_ack_seq_ctx{
int64_t in = 0;
int64_t out = 0;
tcp_ack_seq_ctx(){}
void reset(){
in = 0;
out = 0;
}
};
typedef map<stream_id, tcp_ack_seq_ctx*> tcp_ack_map;
template<typename T>
class PktRequest {
private:
FilterAction action = FilterAction::NOACTION;
mnl_socket* nl = nullptr;
uint16_t res_id;
uint32_t packet_id;
size_t _original_size;
size_t _data_original_size;
size_t _header_size;
bool need_tcp_fixing = false;
public:
bool is_ipv6;
Tins::IP* ipv4 = nullptr;
Tins::IPv6* ipv6 = nullptr;
Tins::TCP* tcp = nullptr;
Tins::UDP* udp = nullptr;
L4Proto l4_proto;
bool is_input;
string packet;
stream_id sid;
tcp_ack_seq_ctx* ack_seq_offset = nullptr;
T* ctx = nullptr;
private:
static inline size_t inner_data_size(Tins::PDU* pdu){
if (pdu == nullptr){
return 0;
}
auto inner = pdu->inner_pdu();
if (inner == nullptr){
return 0;
}
return inner->size();
}
inline void __internal_fetch_data_size(Tins::PDU* pdu){
_data_original_size = inner_data_size(pdu);
_header_size = _original_size - _data_original_size;
}
L4Proto fill_l4_info(){
if (is_ipv6){
tcp = ipv6->find_pdu<Tins::TCP>();
if (tcp == nullptr){
udp = ipv6->find_pdu<Tins::UDP>();
if (udp == nullptr){
__internal_fetch_data_size(ipv6);
return L4Proto::RAW;
}else{
__internal_fetch_data_size(udp);
return L4Proto::UDP;
}
}else{
__internal_fetch_data_size(tcp);
return L4Proto::TCP;
}
}else{
tcp = ipv4->find_pdu<Tins::TCP>();
if (tcp == nullptr){
udp = ipv4->find_pdu<Tins::UDP>();
if (udp == nullptr){
__internal_fetch_data_size(ipv4);
return L4Proto::RAW;
}else{
__internal_fetch_data_size(udp);
return L4Proto::UDP;
}
}else{
__internal_fetch_data_size(tcp);
return L4Proto::TCP;
}
}
}
bool need_tcp_fix(){
return tcp && ack_seq_offset != nullptr && (ack_seq_offset->in != 0 || ack_seq_offset->out != 0);
}
public:
PktRequest(const char* payload, size_t plen, T* ctx, mnl_socket* nl, nfgenmsg *nfg, nfqnl_msg_packet_hdr *ph, bool is_input):
ctx(ctx), nl(nl), res_id(nfg->res_id),
packet_id(ph->packet_id), is_input(is_input),
packet(string(payload, plen)),
action(FilterAction::NOACTION),
is_ipv6((payload[0] & 0xf0) == 0x60)
{
if (is_ipv6){
ipv6 = new Tins::IPv6((uint8_t*)packet.c_str(), plen);
sid = stream_id::make_identifier(*ipv6);
_original_size = ipv6->size();
}else{
ipv4 = new Tins::IP((uint8_t*)packet.c_str(), plen);
sid = stream_id::make_identifier(*ipv4);
_original_size = ipv4->size();
}
l4_proto = fill_l4_info();
#ifdef PKTDEBUG
if (tcp){
cerr << "[DEBUG] NEW_PACKET " << (is_input?"-> IN ":"<- OUT") << " [SIZE: " << data_size() << "] FLAGS: " << (tcp->get_flag(Tins::TCP::FIN)?"FIN ":"") << (tcp->get_flag(Tins::TCP::SYN)?"SYN ":"") << (tcp->get_flag(Tins::TCP::RST)?"RST ":"") << (tcp->get_flag(Tins::TCP::ACK)?"ACK ":"") << (tcp->get_flag(Tins::TCP::PSH)?"PSH ":"") << endl;
cerr << "[SEQ: " << tcp->seq() << "] [ACK: " << tcp->ack_seq() << "]" << " [WIN: " << tcp->window() << "] [FLAGS: " << tcp->flags() << "]\n" << endl;
}
#endif
}
inline size_t header_size(){
return _header_size;
}
char* data(){
return packet.data()+_header_size;
}
size_t data_size(){
return packet.size()-_header_size;
}
size_t data_original_size(){
return _data_original_size;
}
void reserialize(){
auto data = serialize();
packet.resize(data.size());
memcpy(packet.data(), data.data(), data.size());
}
void set_data(const char* data, const size_t& data_size){
auto bef_raw = before_raw_pdu_ptr();
if (bef_raw){
delete before_raw_pdu_ptr()->release_inner_pdu();
before_raw_pdu_ptr() /= move(Tins::RawPDU((uint8_t*)data, data_size));
}
}
Tins::PDU* before_raw_pdu_ptr(){
if (tcp){
return tcp;
}else if (udp){
return udp;
}else if (ipv4){
return ipv4;
}else if (ipv6){
return ipv6;
}
return nullptr;
}
void set_packet(const char* data, size_t data_size){
// Parsing only the header with libtins
Tins::PDU *data_pdu = nullptr;
size_t total_size;
if (is_ipv6){
delete ipv6;
ipv6 = nullptr;
if (data_size >= 40){ // 40 == fixed size of ipv6 header
// Resetting payload length before parsing to libtins
uint16_t payload_len = htons(data_size-40);
memcpy(((uint8_t *)data)+4, &payload_len, 2);
}
ipv6 = new Tins::IPv6((uint8_t*)data, data_size);
if (tcp){
tcp = ipv6->find_pdu<Tins::TCP>();
data_pdu = tcp;
}else if (udp){
udp = ipv6->find_pdu<Tins::UDP>();
data_pdu = udp;
}else{
data_pdu = ipv6;
}
total_size = ipv6->size();
}else{
delete ipv4;
ipv4 = nullptr;
ipv4 = new Tins::IP((uint8_t*)data, data_size);
if (tcp){
tcp = ipv4->find_pdu<Tins::TCP>();
data_pdu = tcp;
}else if(udp){
udp = ipv4->find_pdu<Tins::UDP>();
data_pdu = udp;
}else{
data_pdu = ipv4;
}
total_size = ipv4->size();
}
_header_size = total_size - inner_data_size(data_pdu);
// Libtins can skip data if the lenght is changed to a bigger len (due to ip header total lenght), so we need to specify the data section manually
set_data(data+_header_size, data_size-_header_size);
}
void fix_tcp_ack(){
need_tcp_fixing = need_tcp_fix();
if(!need_tcp_fixing){
return;
}
#ifdef DEBUG
cerr << "[DEBUG] Fixing ack_seq with offsets " << ((int32_t)ack_seq_offset->in) << " " << ((int32_t)ack_seq_offset->out) << endl;
#endif
if (is_input){
tcp->seq(tcp->seq() + ack_seq_offset->in);
tcp->ack_seq(tcp->ack_seq() - ack_seq_offset->out);
}else{
tcp->ack_seq(tcp->ack_seq() - ack_seq_offset->in);
tcp->seq(tcp->seq() + ack_seq_offset->out);
}
#ifdef PKTDEBUG
size_t new_size = inner_data_size(tcp);
cerr << "[DEBUG] FIXED PKT " << (is_input?"-> IN ":"<- OUT") << " [SIZE: " << data_size() << "] FLAGS: " << (tcp->get_flag(Tins::TCP::FIN)?"FIN ":"") << (tcp->get_flag(Tins::TCP::SYN)?"SYN ":"") << (tcp->get_flag(Tins::TCP::RST)?"RST ":"") << (tcp->get_flag(Tins::TCP::ACK)?"ACK ":"") << (tcp->get_flag(Tins::TCP::PSH)?"PSH ":"") << endl;
cerr << "[SEQ: " << tcp->seq() << "] [ACK: " << tcp->ack_seq() << "]" << " [WIN: " << tcp->window() << "] [FLAGS: " << tcp->flags() << "]\n" << endl;
#endif
}
void fix_data_payload(){
//Stream follower move the payload data, so we need to reinizialize RawPDU
auto bef_raw = before_raw_pdu_ptr();
if (bef_raw){
delete bef_raw->release_inner_pdu();
auto new_data_size = packet.size()-_header_size;
if (new_data_size > 0){
bef_raw /= move(Tins::RawPDU((uint8_t*)packet.data()+_header_size, new_data_size));
}
}
}
void drop(){
if (action == FilterAction::NOACTION){
action = FilterAction::DROP;
perfrom_action();
}else{
throw invalid_argument("Cannot drop a packet that has already been dropped or accepted");
}
}
size_t original_size(){
return _original_size;
}
void accept(){
if (action == FilterAction::NOACTION){
action = FilterAction::ACCEPT;
perfrom_action();
}else{
throw invalid_argument("Cannot accept a packet that has already been dropped or accepted");
}
}
void mangle(){
if (action == FilterAction::NOACTION){
action = FilterAction::MANGLE;
perfrom_action();
}else{
throw invalid_argument("Cannot mangle a packet that has already been accepted or dropped");
}
}
void reject(){
if (tcp){
//If the packet has data, we have to remove it
set_data(nullptr, 0);
//For the first matched data or only for data packets, we set RST bit
//This only for client packets, because this will trigger server to close the connection
//Packets will be filtered anyway also if client don't send packets
if (_data_original_size != 0){
tcp->set_flag(Tins::TCP::RST,1);
}
//Send the edited packet to the kernel
mangle();
}else{
drop();
}
}
void mangle_custom_pkt(const char* raw_pkt, size_t raw_pkt_size){
if (action == FilterAction::NOACTION){
try{
set_packet(raw_pkt, raw_pkt_size);
reserialize();
action = FilterAction::MANGLE;
}catch(const std::exception& e){
#ifdef DEBUG
cerr << "[DEBUG] [PktRequest.mangle_custom_pkt] " << e.what() << endl;
#endif
action = FilterAction::DROP;
}
perfrom_action(false);
}else{
throw invalid_argument("Cannot mangle a packet that has already been accepted or dropped");
}
}
FilterAction get_action(){
return action;
}
~PktRequest(){
delete ipv4;
delete ipv6;
}
Tins::PDU::serialization_type serialize(){
if (is_ipv6){
return ipv6->serialize();
}else{
return ipv4->serialize();
}
}
private:
void perfrom_action(bool do_serialize = true){
char buf[MNL_SOCKET_BUFFER_SIZE];
struct nlmsghdr *nlh_verdict = nfq_nlmsg_put(buf, NFQNL_MSG_VERDICT, ntohs(res_id));
switch (action)
{
case FilterAction::ACCEPT:
if (need_tcp_fixing){
if (do_serialize){
fix_data_payload();
reserialize();
}
nfq_nlmsg_verdict_put_pkt(nlh_verdict, packet.data(), packet.size());
}
nfq_nlmsg_verdict_put(nlh_verdict, ntohl(packet_id), NF_ACCEPT );
break;
case FilterAction::DROP:
nfq_nlmsg_verdict_put(nlh_verdict, ntohl(packet_id), NF_DROP );
break;
case FilterAction::MANGLE:{
//If not custom data, use the data in the packets
if(do_serialize){
reserialize();
}
nfq_nlmsg_verdict_put_pkt(nlh_verdict, packet.data(), packet.size());
#ifdef PKTDEBUG
if (tcp){
cerr << "[DEBUG] MANGLEDPKT " << (is_input?"-> IN ":"<- OUT") << " [SIZE: " << data_size() << "] FLAGS: " << (tcp->get_flag(Tins::TCP::FIN)?"FIN ":"") << (tcp->get_flag(Tins::TCP::SYN)?"SYN ":"") << (tcp->get_flag(Tins::TCP::RST)?"RST ":"") << (tcp->get_flag(Tins::TCP::ACK)?"ACK ":"") << (tcp->get_flag(Tins::TCP::PSH)?"PSH ":"") << endl;
cerr << "[SEQ: " << tcp->seq() << "] [ACK: " << tcp->ack_seq() << "]" << " [WIN: " << tcp->window() << "] [FLAGS: " << tcp->flags() << "]\n" << endl;
}
#endif
size_t payload_offset = data_size() - _data_original_size;
if (tcp && ack_seq_offset && payload_offset != 0){
if (is_input){
ack_seq_offset->in += payload_offset;
}else{
ack_seq_offset->out += payload_offset;
}
}
nfq_nlmsg_verdict_put(nlh_verdict, ntohl(packet_id), NF_ACCEPT );
break;
}
default:
throw invalid_argument("Invalid action");
}
if (mnl_socket_sendto(nl, nlh_verdict, nlh_verdict->nlmsg_len) < 0) {
throw runtime_error( "mnl_socket_send" );
}
}
};
struct internal_nfqueue_execution_data_tmp{
mnl_socket* nl = nullptr;
void *data = nullptr;
};
const size_t NFQUEUE_BUFFER_SIZE = 0xffff + (MNL_SOCKET_BUFFER_SIZE/2);
/* NfQueue wrapper class to handle nfqueue packets
this class is made to be possible enqueue multiple packets to multiple threads
--> handle function is responsable to delete the PktRequest object */
template <typename D, void handle_func(PktRequest<D>*)>
class NfQueue {
private:
mnl_socket* nl = nullptr;
unsigned int portid;
public:
char* queue_msg_buffer = nullptr;
const uint16_t queue_num;
NfQueue(u_int16_t queue_num): queue_num(queue_num) {
queue_msg_buffer = new char[NFQUEUE_BUFFER_SIZE];
nl = mnl_socket_open(NETLINK_NETFILTER);
if (nl == nullptr) { 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);
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 command to generate an error meessage
_clear();
throw runtime_error( "mnl_socket_send" );
}
if (_recv_packet() == -1) { //RECV the error message
_clear();
throw runtime_error( "mnl_socket_recvfrom" );
}
struct nlmsghdr *nlh = (struct nlmsghdr *) queue_msg_buffer;
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 invalid_argument( "queueid is already busy" );
}
//END TESTING BIND
nlh = nfq_nlmsg_put(queue_msg_buffer, NFQNL_MSG_CONFIG, queue_num);
nfq_nlmsg_cfg_put_params(nlh, NFQNL_COPY_PACKET, 0xffff);
char * enable_fail_open = getenv("FIREGEX_NFQUEUE_FAIL_OPEN");
if (strcmp(enable_fail_open, "1") == 0){
mnl_attr_put_u32(nlh, NFQA_CFG_FLAGS, htonl(NFQA_CFG_F_GSO|NFQA_CFG_F_FAIL_OPEN));
mnl_attr_put_u32(nlh, NFQA_CFG_MASK, htonl(NFQA_CFG_F_GSO|NFQA_CFG_F_FAIL_OPEN));
}else{
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" );
}
/*
* 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 tmp = 1;
mnl_socket_setsockopt(nl, NETLINK_NO_ENOBUFS, &tmp, sizeof(int));
}
void handle_next_packet(D* data){
int ret = _recv_packet();
if (ret == -1) {
throw runtime_error( "mnl_socket_recvfrom" );
}
internal_nfqueue_execution_data_tmp raw_ptr = {
nl: nl,
data: data
};
ret = mnl_cb_run(queue_msg_buffer, ret, 0, portid, _real_queue_cb, &raw_ptr);
if (ret <= 0){
cerr << "[error] [NfQueue.handle_next_packet] mnl_cb_run error with: " << ret << endl;
throw runtime_error( "mnl_cb_run error!" );
}
}
~NfQueue() {
_send_config_cmd(NFQNL_CFG_CMD_UNBIND);
_clear();
}
private:
static int _real_queue_cb(const nlmsghdr *nlh, void *data_ptr) {
internal_nfqueue_execution_data_tmp* info = (internal_nfqueue_execution_data_tmp*) data_ptr;
//Extract attributes from the nlmsghdr
nlattr *attr[NFQA_MAX+1] = {};
if (nfq_nlmsg_parse(nlh, attr) < 0) {
cerr << "[error] [NfQueue._real_queue_cb] problems parsing" << endl;
return MNL_CB_ERROR;
}
if (attr[NFQA_PACKET_HDR] == nullptr) {
cerr << "[error] [NfQueue._real_queue_cb] packet header not set" << endl;
return MNL_CB_ERROR;
}
if (attr[NFQA_MARK] == nullptr) {
cerr << "[error] [NfQueue._real_queue_cb] mark not set" << endl;
return MNL_CB_ERROR;
}
//Get Payload
uint16_t plen = mnl_attr_get_payload_len(attr[NFQA_PAYLOAD]);
char *payload = (char *)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);
bool is_input = ntohl(mnl_attr_get_u32(attr[NFQA_MARK])) & 0x1; // == 0x1337 that is odd
handle_func(new PktRequest<D>(
payload, plen, (D*)info->data, info->nl, nfg, ph, is_input
));
return MNL_CB_OK;
}
inline void _clear(){
if (nl != nullptr) {
mnl_socket_close(nl);
nl = nullptr;
}
delete[] queue_msg_buffer;
}
inline ssize_t _send_config_cmd(nfqnl_msg_config_cmds cmd){
struct nlmsghdr *nlh = nfq_nlmsg_put(queue_msg_buffer, NFQNL_MSG_CONFIG, queue_num);
nfq_nlmsg_cfg_put_cmd(nlh, AF_INET, cmd);
return mnl_socket_sendto(nl, nlh, nlh->nlmsg_len);
}
inline ssize_t _recv_packet(){
return mnl_socket_recvfrom(nl, queue_msg_buffer, NFQUEUE_BUFFER_SIZE);
}
};
uint32_t hash_stream_id(const stream_id &sid) {
uint32_t addr_hash = 0;
const uint32_t* min_addr = reinterpret_cast<const uint32_t*>(sid.min_address.data());
const uint32_t* max_addr = reinterpret_cast<const uint32_t*>(sid.max_address.data());
addr_hash ^= min_addr[0] ^ min_addr[1] ^ min_addr[2] ^ min_addr[3];
addr_hash ^= max_addr[0] ^ max_addr[1] ^ max_addr[2] ^ max_addr[3];
uint32_t ports = (static_cast<uint32_t>(sid.min_address_port) << 16) | sid.max_address_port;
uint32_t hash = addr_hash ^ ports;
hash *= 0x9e3779b9;
return hash;
}
}}
#endif // NFQUEUE_CLASS_CPP