Add singleton eBPF loader

client/internal/ebpf/bpf_bpfeb.go

@@ -0,0 +1,129 @@
+// Code generated by bpf2go; DO NOT EDIT.
+//go:build arm64be || armbe || mips || mips64 || mips64p32 || ppc64 || s390 || s390x || sparc || sparc64
+// +build arm64be armbe mips mips64 mips64p32 ppc64 s390 s390x sparc sparc64
+
+package ebpf
+
+import (
+	"bytes"
+	_ "embed"
+	"fmt"
+	"io"
+
+	"github.com/cilium/ebpf"
+)
+
+// loadBpf returns the embedded CollectionSpec for bpf.
+func loadBpf() (*ebpf.CollectionSpec, error) {
+	reader := bytes.NewReader(_BpfBytes)
+	spec, err := ebpf.LoadCollectionSpecFromReader(reader)
+	if err != nil {
+		return nil, fmt.Errorf("can't load bpf: %w", err)
+	}
+
+	return spec, err
+}
+
+// loadBpfObjects loads bpf and converts it into a struct.
+//
+// The following types are suitable as obj argument:
+//
+//	*bpfObjects
+//	*bpfPrograms
+//	*bpfMaps
+//
+// See ebpf.CollectionSpec.LoadAndAssign documentation for details.
+func loadBpfObjects(obj interface{}, opts *ebpf.CollectionOptions) error {
+	spec, err := loadBpf()
+	if err != nil {
+		return err
+	}
+
+	return spec.LoadAndAssign(obj, opts)
+}
+
+// bpfSpecs contains maps and programs before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type bpfSpecs struct {
+	bpfProgramSpecs
+	bpfMapSpecs
+}
+
+// bpfSpecs contains programs before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type bpfProgramSpecs struct {
+	NbXdpProg *ebpf.ProgramSpec `ebpf:"nb_xdp_prog"`
+}
+
+// bpfMapSpecs contains maps before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type bpfMapSpecs struct {
+	NbFeatures           *ebpf.MapSpec `ebpf:"nb_features"`
+	NbMapDnsIp           *ebpf.MapSpec `ebpf:"nb_map_dns_ip"`
+	NbMapDnsPort         *ebpf.MapSpec `ebpf:"nb_map_dns_port"`
+	NbWgProxySettingsMap *ebpf.MapSpec `ebpf:"nb_wg_proxy_settings_map"`
+}
+
+// bpfObjects contains all objects after they have been loaded into the kernel.
+//
+// It can be passed to loadBpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type bpfObjects struct {
+	bpfPrograms
+	bpfMaps
+}
+
+func (o *bpfObjects) Close() error {
+	return _BpfClose(
+		&o.bpfPrograms,
+		&o.bpfMaps,
+	)
+}
+
+// bpfMaps contains all maps after they have been loaded into the kernel.
+//
+// It can be passed to loadBpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type bpfMaps struct {
+	NbFeatures           *ebpf.Map `ebpf:"nb_features"`
+	NbMapDnsIp           *ebpf.Map `ebpf:"nb_map_dns_ip"`
+	NbMapDnsPort         *ebpf.Map `ebpf:"nb_map_dns_port"`
+	NbWgProxySettingsMap *ebpf.Map `ebpf:"nb_wg_proxy_settings_map"`
+}
+
+func (m *bpfMaps) Close() error {
+	return _BpfClose(
+		m.NbFeatures,
+		m.NbMapDnsIp,
+		m.NbMapDnsPort,
+		m.NbWgProxySettingsMap,
+	)
+}
+
+// bpfPrograms contains all programs after they have been loaded into the kernel.
+//
+// It can be passed to loadBpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type bpfPrograms struct {
+	NbXdpProg *ebpf.Program `ebpf:"nb_xdp_prog"`
+}
+
+func (p *bpfPrograms) Close() error {
+	return _BpfClose(
+		p.NbXdpProg,
+	)
+}
+
+func _BpfClose(closers ...io.Closer) error {
+	for _, closer := range closers {
+		if err := closer.Close(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Do not access this directly.
+//
+//go:embed bpf_bpfeb.o
+var _BpfBytes []byte

client/internal/ebpf/bpf_bpfel.go

@@ -0,0 +1,129 @@
+// Code generated by bpf2go; DO NOT EDIT.
+//go:build 386 || amd64 || amd64p32 || arm || arm64 || mips64le || mips64p32le || mipsle || ppc64le || riscv64
+// +build 386 amd64 amd64p32 arm arm64 mips64le mips64p32le mipsle ppc64le riscv64
+
+package ebpf
+
+import (
+	"bytes"
+	_ "embed"
+	"fmt"
+	"io"
+
+	"github.com/cilium/ebpf"
+)
+
+// loadBpf returns the embedded CollectionSpec for bpf.
+func loadBpf() (*ebpf.CollectionSpec, error) {
+	reader := bytes.NewReader(_BpfBytes)
+	spec, err := ebpf.LoadCollectionSpecFromReader(reader)
+	if err != nil {
+		return nil, fmt.Errorf("can't load bpf: %w", err)
+	}
+
+	return spec, err
+}
+
+// loadBpfObjects loads bpf and converts it into a struct.
+//
+// The following types are suitable as obj argument:
+//
+//	*bpfObjects
+//	*bpfPrograms
+//	*bpfMaps
+//
+// See ebpf.CollectionSpec.LoadAndAssign documentation for details.
+func loadBpfObjects(obj interface{}, opts *ebpf.CollectionOptions) error {
+	spec, err := loadBpf()
+	if err != nil {
+		return err
+	}
+
+	return spec.LoadAndAssign(obj, opts)
+}
+
+// bpfSpecs contains maps and programs before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type bpfSpecs struct {
+	bpfProgramSpecs
+	bpfMapSpecs
+}
+
+// bpfSpecs contains programs before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type bpfProgramSpecs struct {
+	NbXdpProg *ebpf.ProgramSpec `ebpf:"nb_xdp_prog"`
+}
+
+// bpfMapSpecs contains maps before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type bpfMapSpecs struct {
+	NbFeatures           *ebpf.MapSpec `ebpf:"nb_features"`
+	NbMapDnsIp           *ebpf.MapSpec `ebpf:"nb_map_dns_ip"`
+	NbMapDnsPort         *ebpf.MapSpec `ebpf:"nb_map_dns_port"`
+	NbWgProxySettingsMap *ebpf.MapSpec `ebpf:"nb_wg_proxy_settings_map"`
+}
+
+// bpfObjects contains all objects after they have been loaded into the kernel.
+//
+// It can be passed to loadBpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type bpfObjects struct {
+	bpfPrograms
+	bpfMaps
+}
+
+func (o *bpfObjects) Close() error {
+	return _BpfClose(
+		&o.bpfPrograms,
+		&o.bpfMaps,
+	)
+}
+
+// bpfMaps contains all maps after they have been loaded into the kernel.
+//
+// It can be passed to loadBpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type bpfMaps struct {
+	NbFeatures           *ebpf.Map `ebpf:"nb_features"`
+	NbMapDnsIp           *ebpf.Map `ebpf:"nb_map_dns_ip"`
+	NbMapDnsPort         *ebpf.Map `ebpf:"nb_map_dns_port"`
+	NbWgProxySettingsMap *ebpf.Map `ebpf:"nb_wg_proxy_settings_map"`
+}
+
+func (m *bpfMaps) Close() error {
+	return _BpfClose(
+		m.NbFeatures,
+		m.NbMapDnsIp,
+		m.NbMapDnsPort,
+		m.NbWgProxySettingsMap,
+	)
+}
+
+// bpfPrograms contains all programs after they have been loaded into the kernel.
+//
+// It can be passed to loadBpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type bpfPrograms struct {
+	NbXdpProg *ebpf.Program `ebpf:"nb_xdp_prog"`
+}
+
+func (p *bpfPrograms) Close() error {
+	return _BpfClose(
+		p.NbXdpProg,
+	)
+}
+
+func _BpfClose(closers ...io.Closer) error {
+	for _, closer := range closers {
+		if err := closer.Close(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Do not access this directly.
+//
+//go:embed bpf_bpfel.o
+var _BpfBytes []byte

client/internal/ebpf/dns_fwd.go

@@ -0,0 +1,51 @@
+package ebpf
+
+import (
+	"encoding/binary"
+	"net"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	mapKeyDNSIP   uint32 = 0
+	mapKeyDNSPort uint32 = 1
+)
+
+func (tf *Manager) LoadDNSFwd(ip string, dnsPort int) error {
+	log.Debugf("load ebpf DNS forwarder: address: %s:%d", ip, dnsPort)
+	tf.lock.Lock()
+	defer tf.lock.Unlock()
+
+	err := tf.loadXdp()
+	if err != nil {
+		return err
+	}
+
+	err = tf.bpfObjs.NbMapDnsIp.Put(mapKeyDNSIP, ip2int(ip))
+	if err != nil {
+		return err
+	}
+
+	err = tf.bpfObjs.NbMapDnsPort.Put(mapKeyDNSPort, uint16(dnsPort))
+	if err != nil {
+		return err
+	}
+
+	tf.setFeatureFlag(featureFlagDnsForwarder)
+	err = tf.bpfObjs.NbFeatures.Put(mapKeyFeatures, tf.featureFlags)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (tf *Manager) FreeDNSFwd() error {
+	log.Debugf("free ebpf DNS forwarder")
+	return tf.unsetFeatureFlag(featureFlagDnsForwarder)
+}
+
+func ip2int(ipString string) uint32 {
+	ip := net.ParseIP(ipString)
+	return binary.BigEndian.Uint32(ip.To4())
+}

client/internal/ebpf/loader.go

@@ -0,0 +1,104 @@
+package ebpf
+
+import (
+	_ "embed"
+	"net"
+	"sync"
+
+	"github.com/cilium/ebpf/link"
+	"github.com/cilium/ebpf/rlimit"
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	mapKeyFeatures uint32 = 0
+
+	featureFlagWGProxy      = 0b00000001
+	featureFlagDnsForwarder = 0b00000010
+)
+
+var (
+	singleton     *Manager
+	singletonLock = &sync.Mutex{}
+)
+
+// libbpf-dev, libc6-dev-i386-amd64-cross
+
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -cc clang-14 bpf src/prog.c -- -I /usr/x86_64-linux-gnu/include
+type Manager struct {
+	lock         sync.Mutex
+	link         link.Link
+	featureFlags uint16
+	bpfObjs      bpfObjects
+}
+
+// GetEbpfManagerInstance return a static eBpf Manager instance
+func GetEbpfManagerInstance() *Manager {
+	singletonLock.Lock()
+	defer singletonLock.Unlock()
+	if singleton != nil {
+		return singleton
+	}
+	singleton = &Manager{}
+	return singleton
+}
+
+func (tf *Manager) setFeatureFlag(feature uint16) {
+	tf.featureFlags = tf.featureFlags | feature
+}
+
+func (tf *Manager) loadXdp() error {
+	if tf.link != nil {
+		return nil
+	}
+	// it required for Docker
+	err := rlimit.RemoveMemlock()
+	if err != nil {
+		return err
+	}
+
+	iFace, err := net.InterfaceByName("lo")
+	if err != nil {
+		return err
+	}
+
+	// load pre-compiled programs into the kernel.
+	err = loadBpfObjects(&tf.bpfObjs, nil)
+	if err != nil {
+		return err
+	}
+
+	tf.link, err = link.AttachXDP(link.XDPOptions{
+		Program:   tf.bpfObjs.NbXdpProg,
+		Interface: iFace.Index,
+	})
+	return err
+}
+
+func (tf *Manager) unsetFeatureFlag(feature uint16) error {
+	tf.lock.Lock()
+	defer tf.lock.Unlock()
+	tf.featureFlags &^= feature
+
+	if tf.link == nil {
+		return nil
+	}
+
+	if tf.featureFlags == 0 {
+		return tf.close()
+	}
+
+	return tf.bpfObjs.NbFeatures.Put(mapKeyFeatures, tf.featureFlags)
+}
+
+func (tf *Manager) close() error {
+	log.Debugf("detach ebpf program ")
+	err := tf.bpfObjs.Close()
+	if err != nil {
+		log.Warnf("failed to close eBpf objects: %s", err)
+	}
+
+	err = tf.link.Close()
+	tf.link = nil
+	return err
+}

client/internal/ebpf/loader_test.go

@@ -0,0 +1,40 @@
+package ebpf
+
+import (
+	"testing"
+)
+
+func TestManager_setFeatureFlag(t *testing.T) {
+	mgr := Manager{}
+	mgr.setFeatureFlag(featureFlagWGProxy)
+	if mgr.featureFlags != 1 {
+		t.Errorf("invalid faeture state")
+	}
+
+	mgr.setFeatureFlag(featureFlagDnsForwarder)
+	if mgr.featureFlags != 3 {
+		t.Errorf("invalid faeture state")
+	}
+}
+
+func TestManager_unsetFeatureFlag(t *testing.T) {
+	mgr := Manager{}
+	mgr.setFeatureFlag(featureFlagWGProxy)
+	mgr.setFeatureFlag(featureFlagDnsForwarder)
+
+	err := mgr.unsetFeatureFlag(featureFlagWGProxy)
+	if err != nil {
+		t.Errorf("unexpected error: %s", err)
+	}
+	if mgr.featureFlags != 2 {
+		t.Errorf("invalid faeture state, expected: %d, got: %d", 2, mgr.featureFlags)
+	}
+
+	err = mgr.unsetFeatureFlag(featureFlagDnsForwarder)
+	if err != nil {
+		t.Errorf("unexpected error: %s", err)
+	}
+	if mgr.featureFlags != 0 {
+		t.Errorf("invalid faeture state, expected: %d, got: %d", 0, mgr.featureFlags)
+	}
+}

client/internal/ebpf/src/dns_fwd.c

@@ -0,0 +1,64 @@
+const __u32 map_key_dns_ip = 0;
+const __u32 map_key_dns_port = 1;
+
+struct bpf_map_def SEC("maps") nb_map_dns_ip = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u32),
+	.max_entries = 10,
+};
+
+struct bpf_map_def SEC("maps") nb_map_dns_port = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u16),
+	.max_entries = 10,
+};
+
+__be32 dns_ip = 0;
+__be16 dns_port = 0;
+
+// 13568 is 53 in big endian
+__be16 GENERAL_DNS_PORT = 13568;
+
+bool read_settings() {
+    __u16 *port_value;
+    __u32 *ip_value;
+
+    // read dns ip
+    ip_value = bpf_map_lookup_elem(&nb_map_dns_ip, &map_key_dns_ip);
+    if(!ip_value) {
+        return false;
+    }
+    dns_ip = htonl(*ip_value);
+
+    // read dns port
+    port_value = bpf_map_lookup_elem(&nb_map_dns_port, &map_key_dns_port);
+    if (!port_value) {
+        return false;
+    }
+    dns_port = htons(*port_value);
+    return true;
+}
+
+int xdp_dns_fwd(struct iphdr  *ip, struct udphdr *udp) {
+    if (dns_port == 0) {
+        if(!read_settings()){
+            return XDP_PASS;
+        }
+        bpf_printk("dns port: %d", ntohs(dns_port));
+        bpf_printk("dns ip: %d", ntohl(dns_ip));
+    }
+
+    if (udp->dest == GENERAL_DNS_PORT && ip->daddr == dns_ip) {
+        udp->dest = dns_port;
+        return XDP_PASS;
+    }
+
+    if (udp->source == dns_port && ip->saddr == dns_ip) {
+        udp->source = GENERAL_DNS_PORT;
+        return XDP_PASS;
+    }
+
+    return XDP_PASS;
+}

client/internal/ebpf/src/prog.c

@@ -0,0 +1,66 @@
+#include <stdbool.h>
+#include <linux/if_ether.h> // ETH_P_IP
+#include <linux/udp.h>
+#include <linux/ip.h>
+#include <netinet/in.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "dns_fwd.c"
+#include "wg_proxy.c"
+
+#define bpf_printk(fmt, ...)                                                   \
+  ({                                                                           \
+    char ____fmt[] = fmt;                                                      \
+    bpf_trace_printk(____fmt, sizeof(____fmt), ##__VA_ARGS__);                 \
+  })
+
+const __u16 flag_feature_wg_proxy = 0b01;
+const __u16 flag_feature_dns_fwd = 0b10;
+
+const __u32 map_key_features = 0;
+struct bpf_map_def SEC("maps") nb_features = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u16),
+	.max_entries = 10,
+};
+
+SEC("xdp")
+int nb_xdp_prog(struct xdp_md *ctx) {
+    __u16 *features;
+    features = bpf_map_lookup_elem(&nb_features, &map_key_features);
+    if (!features) {
+        return XDP_PASS;
+    }
+
+    void *data     = (void *)(long)ctx->data;
+    void *data_end = (void *)(long)ctx->data_end;
+    struct ethhdr *eth = data;
+    struct iphdr  *ip  = (data + sizeof(struct ethhdr));
+    struct udphdr *udp = (data + sizeof(struct ethhdr) + sizeof(struct iphdr));
+
+    // return early if not enough data
+    if (data + sizeof(struct ethhdr) + sizeof(struct iphdr) + sizeof(struct udphdr) > data_end){
+        return XDP_PASS;
+    }
+
+    // skip non IPv4 packages
+    if (eth->h_proto != htons(ETH_P_IP)) {
+       return XDP_PASS;
+    }
+
+    // skip non UPD packages
+    if (ip->protocol != IPPROTO_UDP) {
+       return XDP_PASS;
+    }
+
+    if (*features & flag_feature_dns_fwd) {
+        xdp_dns_fwd(ip, udp);
+    }
+
+    if (*features & flag_feature_wg_proxy) {
+        xdp_wg_proxy(ip, udp);
+    }
+    return XDP_PASS;
+}
+char _license[] SEC("license") = "GPL";

client/internal/ebpf/src/wg_proxy.c

@@ -0,0 +1,54 @@
+const __u32 map_key_proxy_port = 0;
+const __u32 map_key_wg_port = 1;
+
+struct bpf_map_def SEC("maps") nb_wg_proxy_settings_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u16),
+	.max_entries = 10,
+};
+
+__u16 proxy_port = 0;
+__u16 wg_port = 0;
+
+bool read_port_settings() {
+    __u16 *value;
+    value = bpf_map_lookup_elem(&nb_wg_proxy_settings_map, &map_key_proxy_port);
+    if (!value) {
+        return false;
+    }
+
+    proxy_port = *value;
+
+    value = bpf_map_lookup_elem(&nb_wg_proxy_settings_map, &map_key_wg_port);
+    if (!value) {
+        return false;
+    }
+    wg_port = htons(*value);
+
+    return true;
+}
+
+int xdp_wg_proxy(struct iphdr  *ip, struct udphdr *udp) {
+    if (proxy_port == 0 || wg_port == 0) {
+        if (!read_port_settings()){
+            return XDP_PASS;
+        }
+        bpf_printk("proxy port: %d, wg port: %d", proxy_port, wg_port);
+    }
+
+    // 2130706433 = 127.0.0.1
+    if (ip->daddr != htonl(2130706433)) {
+        return XDP_PASS;
+    }
+
+    if (udp->source != wg_port){
+        return XDP_PASS;
+    }
+
+    __be16 new_src_port = udp->dest;
+    __be16 new_dst_port = htons(proxy_port);
+    udp->dest = new_dst_port;
+    udp->source = new_src_port;
+	return XDP_PASS;
+}

client/internal/ebpf/wg_proxy.go

@@ -0,0 +1,41 @@
+package ebpf
+
+import log "github.com/sirupsen/logrus"
+
+const (
+	mapKeyProxyPort uint32 = 0
+	mapKeyWgPort    uint32 = 1
+)
+
+func (tf *Manager) LoadWgProxy(proxyPort, wgPort int) error {
+	log.Debugf("load ebpf WG proxy")
+	tf.lock.Lock()
+	defer tf.lock.Unlock()
+
+	err := tf.loadXdp()
+	if err != nil {
+		return err
+	}
+
+	err = tf.bpfObjs.NbWgProxySettingsMap.Put(mapKeyProxyPort, uint16(proxyPort))
+	if err != nil {
+		return err
+	}
+
+	err = tf.bpfObjs.NbWgProxySettingsMap.Put(mapKeyWgPort, uint16(wgPort))
+	if err != nil {
+		return err
+	}
+
+	tf.setFeatureFlag(featureFlagWGProxy)
+	err = tf.bpfObjs.NbFeatures.Put(mapKeyFeatures, tf.featureFlags)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (tf *Manager) FreeWGProxy() error {
+	log.Debugf("free ebpf WG proxy")
+	return tf.unsetFeatureFlag(featureFlagWGProxy)
+}