Move ebpf code to its own package to avoid crash issues in Android (#1033)

* Move ebpf code to its own package to avoid crash issues in Android

Older versions of android crashes because of the bytecode files
Even when they aren't loaded as it was our case

* move c file to own folder

* fix lint

client/internal/wgproxy/ebpf/bpf_bpfeb.go

@@ -0,0 +1,120 @@
+// 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 {
+	XdpProgFunc *ebpf.ProgramSpec `ebpf:"xdp_prog_func"`
+}
+
+// bpfMapSpecs contains maps before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type bpfMapSpecs struct {
+	XdpPortMap *ebpf.MapSpec `ebpf:"xdp_port_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 {
+	XdpPortMap *ebpf.Map `ebpf:"xdp_port_map"`
+}
+
+func (m *bpfMaps) Close() error {
+	return _BpfClose(
+		m.XdpPortMap,
+	)
+}
+
+// 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 {
+	XdpProgFunc *ebpf.Program `ebpf:"xdp_prog_func"`
+}
+
+func (p *bpfPrograms) Close() error {
+	return _BpfClose(
+		p.XdpProgFunc,
+	)
+}
+
+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/wgproxy/ebpf/bpf_bpfel.go

@@ -0,0 +1,120 @@
+// 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 {
+	XdpProgFunc *ebpf.ProgramSpec `ebpf:"xdp_prog_func"`
+}
+
+// bpfMapSpecs contains maps before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type bpfMapSpecs struct {
+	XdpPortMap *ebpf.MapSpec `ebpf:"xdp_port_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 {
+	XdpPortMap *ebpf.Map `ebpf:"xdp_port_map"`
+}
+
+func (m *bpfMaps) Close() error {
+	return _BpfClose(
+		m.XdpPortMap,
+	)
+}
+
+// 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 {
+	XdpProgFunc *ebpf.Program `ebpf:"xdp_prog_func"`
+}
+
+func (p *bpfPrograms) Close() error {
+	return _BpfClose(
+		p.XdpProgFunc,
+	)
+}
+
+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/wgproxy/ebpf/loader.go

@@ -0,0 +1,84 @@
+//go:build linux && !android
+
+package ebpf
+
+import (
+	_ "embed"
+	"net"
+
+	"github.com/cilium/ebpf/link"
+	"github.com/cilium/ebpf/rlimit"
+)
+
+const (
+	mapKeyProxyPort uint32 = 0
+	mapKeyWgPort    uint32 = 1
+)
+
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -cc clang-14 bpf src/portreplace.c --
+
+// EBPF is a wrapper for eBPF program
+type EBPF struct {
+	link link.Link
+}
+
+// NewEBPF create new EBPF instance
+func NewEBPF() *EBPF {
+	return &EBPF{}
+}
+
+// Load load ebpf program
+func (l *EBPF) Load(proxyPort, wgPort int) error {
+	// it required for Docker
+	err := rlimit.RemoveMemlock()
+	if err != nil {
+		return err
+	}
+
+	ifce, err := net.InterfaceByName("lo")
+	if err != nil {
+		return err
+	}
+
+	// Load pre-compiled programs into the kernel.
+	objs := bpfObjects{}
+	err = loadBpfObjects(&objs, nil)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		_ = objs.Close()
+	}()
+
+	err = objs.XdpPortMap.Put(mapKeyProxyPort, uint16(proxyPort))
+	if err != nil {
+		return err
+	}
+
+	err = objs.XdpPortMap.Put(mapKeyWgPort, uint16(wgPort))
+	if err != nil {
+		return err
+	}
+
+	defer func() {
+		_ = objs.XdpPortMap.Close()
+	}()
+
+	l.link, err = link.AttachXDP(link.XDPOptions{
+		Program:   objs.XdpProgFunc,
+		Interface: ifce.Index,
+	})
+	if err != nil {
+		return err
+	}
+
+	return err
+}
+
+// Free free ebpf program
+func (l *EBPF) Free() error {
+	if l.link != nil {
+		return l.link.Close()
+	}
+	return nil
+}

client/internal/wgproxy/ebpf/loader_test.go

@@ -0,0 +1,18 @@
+//go:build linux
+
+package ebpf
+
+import (
+	"testing"
+)
+
+func Test_newEBPF(t *testing.T) {
+	ebpf := NewEBPF()
+	err := ebpf.Load(1234, 51892)
+	defer func() {
+		_ = ebpf.Free()
+	}()
+	if err != nil {
+		t.Errorf("%s", err)
+	}
+}

client/internal/wgproxy/ebpf/src/portreplace.c

@@ -0,0 +1,90 @@
+#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>
+
+#define bpf_printk(fmt, ...)                                                   \
+  ({                                                                           \
+    char ____fmt[] = fmt;                                                      \
+    bpf_trace_printk(____fmt, sizeof(____fmt), ##__VA_ARGS__);                 \
+  })
+
+const __u32 map_key_proxy_port = 0;
+const __u32 map_key_wg_port = 1;
+
+struct bpf_map_def SEC("maps") xdp_port_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(&xdp_port_map, &map_key_proxy_port);
+    if(!value) {
+        return false;
+    }
+
+    proxy_port = *value;
+
+    value = bpf_map_lookup_elem(&xdp_port_map, &map_key_wg_port);
+    if(!value) {
+        return false;
+    }
+    wg_port = *value;
+
+    return true;
+}
+
+SEC("xdp")
+int xdp_prog_func(struct xdp_md *ctx) {
+    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);
+    }
+
+	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;
+    }
+
+    if (ip->protocol != IPPROTO_UDP) {
+       return XDP_PASS;
+    }
+
+    // 2130706433 = 127.0.0.1
+    if (ip->daddr != htonl(2130706433)) {
+        return XDP_PASS;
+    }
+
+    if (udp->source != htons(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;
+}
+char _license[] SEC("license") = "GPL";