EtherGuard-VPN/device/conn_linux.go
Jason A. Donenfeld f8198c0428 device: getsockname on linux to determine port
It turns out Go isn't passing the pointer properly so we wound up with a
zero port every time.
2019-08-25 12:45:13 -06:00

758 lines
15 KiB
Go

// +build !android
/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
*
* This implements userspace semantics of "sticky sockets", modeled after
* WireGuard's kernelspace implementation. This is more or less a straight port
* of the sticky-sockets.c example code:
* https://git.zx2c4.com/WireGuard/tree/contrib/examples/sticky-sockets/sticky-sockets.c
*
* Currently there is no way to achieve this within the net package:
* See e.g. https://github.com/golang/go/issues/17930
* So this code is remains platform dependent.
*/
package device
import (
"errors"
"net"
"strconv"
"sync"
"syscall"
"unsafe"
"golang.org/x/sys/unix"
"golang.zx2c4.com/wireguard/rwcancel"
)
const (
FD_ERR = -1
)
type IPv4Source struct {
src [4]byte
ifindex int32
}
type IPv6Source struct {
src [16]byte
//ifindex belongs in dst.ZoneId
}
type NativeEndpoint struct {
dst [unsafe.Sizeof(unix.SockaddrInet6{})]byte
src [unsafe.Sizeof(IPv6Source{})]byte
isV6 bool
}
func (endpoint *NativeEndpoint) src4() *IPv4Source {
return (*IPv4Source)(unsafe.Pointer(&endpoint.src[0]))
}
func (endpoint *NativeEndpoint) src6() *IPv6Source {
return (*IPv6Source)(unsafe.Pointer(&endpoint.src[0]))
}
func (endpoint *NativeEndpoint) dst4() *unix.SockaddrInet4 {
return (*unix.SockaddrInet4)(unsafe.Pointer(&endpoint.dst[0]))
}
func (endpoint *NativeEndpoint) dst6() *unix.SockaddrInet6 {
return (*unix.SockaddrInet6)(unsafe.Pointer(&endpoint.dst[0]))
}
type nativeBind struct {
sock4 int
sock6 int
netlinkSock int
netlinkCancel *rwcancel.RWCancel
lastMark uint32
}
var _ Endpoint = (*NativeEndpoint)(nil)
var _ Bind = (*nativeBind)(nil)
func CreateEndpoint(s string) (Endpoint, error) {
var end NativeEndpoint
addr, err := parseEndpoint(s)
if err != nil {
return nil, err
}
ipv4 := addr.IP.To4()
if ipv4 != nil {
dst := end.dst4()
end.isV6 = false
dst.Port = addr.Port
copy(dst.Addr[:], ipv4)
end.ClearSrc()
return &end, nil
}
ipv6 := addr.IP.To16()
if ipv6 != nil {
zone, err := zoneToUint32(addr.Zone)
if err != nil {
return nil, err
}
dst := end.dst6()
end.isV6 = true
dst.Port = addr.Port
dst.ZoneId = zone
copy(dst.Addr[:], ipv6[:])
end.ClearSrc()
return &end, nil
}
return nil, errors.New("Invalid IP address")
}
func createNetlinkRouteSocket() (int, error) {
sock, err := unix.Socket(unix.AF_NETLINK, unix.SOCK_RAW, unix.NETLINK_ROUTE)
if err != nil {
return -1, err
}
saddr := &unix.SockaddrNetlink{
Family: unix.AF_NETLINK,
Groups: uint32(1 << (unix.RTNLGRP_IPV4_ROUTE - 1)),
}
err = unix.Bind(sock, saddr)
if err != nil {
unix.Close(sock)
return -1, err
}
return sock, nil
}
func CreateBind(port uint16, device *Device) (*nativeBind, uint16, error) {
var err error
var bind nativeBind
var newPort uint16
bind.netlinkSock, err = createNetlinkRouteSocket()
if err != nil {
return nil, 0, err
}
bind.netlinkCancel, err = rwcancel.NewRWCancel(bind.netlinkSock)
if err != nil {
unix.Close(bind.netlinkSock)
return nil, 0, err
}
go bind.routineRouteListener(device)
// attempt ipv6 bind, update port if succesful
bind.sock6, newPort, err = create6(port)
if err != nil {
if err != syscall.EAFNOSUPPORT {
bind.netlinkCancel.Cancel()
return nil, 0, err
}
} else {
port = newPort
}
// attempt ipv4 bind, update port if succesful
bind.sock4, newPort, err = create4(port)
if err != nil {
if err != syscall.EAFNOSUPPORT {
bind.netlinkCancel.Cancel()
unix.Close(bind.sock6)
return nil, 0, err
}
} else {
port = newPort
}
if bind.sock4 == FD_ERR && bind.sock6 == FD_ERR {
return nil, 0, errors.New("ipv4 and ipv6 not supported")
}
return &bind, port, nil
}
func (bind *nativeBind) SetMark(value uint32) error {
if bind.sock6 != -1 {
err := unix.SetsockoptInt(
bind.sock6,
unix.SOL_SOCKET,
unix.SO_MARK,
int(value),
)
if err != nil {
return err
}
}
if bind.sock4 != -1 {
err := unix.SetsockoptInt(
bind.sock4,
unix.SOL_SOCKET,
unix.SO_MARK,
int(value),
)
if err != nil {
return err
}
}
bind.lastMark = value
return nil
}
func closeUnblock(fd int) error {
// shutdown to unblock readers and writers
unix.Shutdown(fd, unix.SHUT_RDWR)
return unix.Close(fd)
}
func (bind *nativeBind) Close() error {
var err1, err2, err3 error
if bind.sock6 != -1 {
err1 = closeUnblock(bind.sock6)
}
if bind.sock4 != -1 {
err2 = closeUnblock(bind.sock4)
}
err3 = bind.netlinkCancel.Cancel()
if err1 != nil {
return err1
}
if err2 != nil {
return err2
}
return err3
}
func (bind *nativeBind) ReceiveIPv6(buff []byte) (int, Endpoint, error) {
var end NativeEndpoint
if bind.sock6 == -1 {
return 0, nil, syscall.EAFNOSUPPORT
}
n, err := receive6(
bind.sock6,
buff,
&end,
)
return n, &end, err
}
func (bind *nativeBind) ReceiveIPv4(buff []byte) (int, Endpoint, error) {
var end NativeEndpoint
if bind.sock4 == -1 {
return 0, nil, syscall.EAFNOSUPPORT
}
n, err := receive4(
bind.sock4,
buff,
&end,
)
return n, &end, err
}
func (bind *nativeBind) Send(buff []byte, end Endpoint) error {
nend := end.(*NativeEndpoint)
if !nend.isV6 {
if bind.sock4 == -1 {
return syscall.EAFNOSUPPORT
}
return send4(bind.sock4, nend, buff)
} else {
if bind.sock6 == -1 {
return syscall.EAFNOSUPPORT
}
return send6(bind.sock6, nend, buff)
}
}
func (end *NativeEndpoint) SrcIP() net.IP {
if !end.isV6 {
return net.IPv4(
end.src4().src[0],
end.src4().src[1],
end.src4().src[2],
end.src4().src[3],
)
} else {
return end.src6().src[:]
}
}
func (end *NativeEndpoint) DstIP() net.IP {
if !end.isV6 {
return net.IPv4(
end.dst4().Addr[0],
end.dst4().Addr[1],
end.dst4().Addr[2],
end.dst4().Addr[3],
)
} else {
return end.dst6().Addr[:]
}
}
func (end *NativeEndpoint) DstToBytes() []byte {
if !end.isV6 {
return (*[unsafe.Offsetof(end.dst4().Addr) + unsafe.Sizeof(end.dst4().Addr)]byte)(unsafe.Pointer(end.dst4()))[:]
} else {
return (*[unsafe.Offsetof(end.dst6().Addr) + unsafe.Sizeof(end.dst6().Addr)]byte)(unsafe.Pointer(end.dst6()))[:]
}
}
func (end *NativeEndpoint) SrcToString() string {
return end.SrcIP().String()
}
func (end *NativeEndpoint) DstToString() string {
var udpAddr net.UDPAddr
udpAddr.IP = end.DstIP()
if !end.isV6 {
udpAddr.Port = end.dst4().Port
} else {
udpAddr.Port = end.dst6().Port
}
return udpAddr.String()
}
func (end *NativeEndpoint) ClearDst() {
for i := range end.dst {
end.dst[i] = 0
}
}
func (end *NativeEndpoint) ClearSrc() {
for i := range end.src {
end.src[i] = 0
}
}
func zoneToUint32(zone string) (uint32, error) {
if zone == "" {
return 0, nil
}
if intr, err := net.InterfaceByName(zone); err == nil {
return uint32(intr.Index), nil
}
n, err := strconv.ParseUint(zone, 10, 32)
return uint32(n), err
}
func create4(port uint16) (int, uint16, error) {
// create socket
fd, err := unix.Socket(
unix.AF_INET,
unix.SOCK_DGRAM,
0,
)
if err != nil {
return FD_ERR, 0, err
}
addr := unix.SockaddrInet4{
Port: int(port),
}
// set sockopts and bind
if err := func() error {
if err := unix.SetsockoptInt(
fd,
unix.SOL_SOCKET,
unix.SO_REUSEADDR,
1,
); err != nil {
return err
}
if err := unix.SetsockoptInt(
fd,
unix.IPPROTO_IP,
unix.IP_PKTINFO,
1,
); err != nil {
return err
}
return unix.Bind(fd, &addr)
}(); err != nil {
unix.Close(fd)
return FD_ERR, 0, err
}
sa, err := unix.Getsockname(fd)
if err == nil {
addr.Port = sa.(*unix.SockaddrInet4).Port
}
return fd, uint16(addr.Port), err
}
func create6(port uint16) (int, uint16, error) {
// create socket
fd, err := unix.Socket(
unix.AF_INET6,
unix.SOCK_DGRAM,
0,
)
if err != nil {
return FD_ERR, 0, err
}
// set sockopts and bind
addr := unix.SockaddrInet6{
Port: int(port),
}
if err := func() error {
if err := unix.SetsockoptInt(
fd,
unix.SOL_SOCKET,
unix.SO_REUSEADDR,
1,
); err != nil {
return err
}
if err := unix.SetsockoptInt(
fd,
unix.IPPROTO_IPV6,
unix.IPV6_RECVPKTINFO,
1,
); err != nil {
return err
}
if err := unix.SetsockoptInt(
fd,
unix.IPPROTO_IPV6,
unix.IPV6_V6ONLY,
1,
); err != nil {
return err
}
return unix.Bind(fd, &addr)
}(); err != nil {
unix.Close(fd)
return FD_ERR, 0, err
}
sa, err := unix.Getsockname(fd)
if err == nil {
addr.Port = sa.(*unix.SockaddrInet6).Port
}
return fd, uint16(addr.Port), err
}
func send4(sock int, end *NativeEndpoint, buff []byte) error {
// construct message header
cmsg := struct {
cmsghdr unix.Cmsghdr
pktinfo unix.Inet4Pktinfo
}{
unix.Cmsghdr{
Level: unix.IPPROTO_IP,
Type: unix.IP_PKTINFO,
Len: unix.SizeofInet4Pktinfo + unix.SizeofCmsghdr,
},
unix.Inet4Pktinfo{
Spec_dst: end.src4().src,
Ifindex: end.src4().ifindex,
},
}
_, err := unix.SendmsgN(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], end.dst4(), 0)
if err == nil {
return nil
}
// clear src and retry
if err == unix.EINVAL {
end.ClearSrc()
cmsg.pktinfo = unix.Inet4Pktinfo{}
_, err = unix.SendmsgN(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], end.dst4(), 0)
}
return err
}
func send6(sock int, end *NativeEndpoint, buff []byte) error {
// construct message header
cmsg := struct {
cmsghdr unix.Cmsghdr
pktinfo unix.Inet6Pktinfo
}{
unix.Cmsghdr{
Level: unix.IPPROTO_IPV6,
Type: unix.IPV6_PKTINFO,
Len: unix.SizeofInet6Pktinfo + unix.SizeofCmsghdr,
},
unix.Inet6Pktinfo{
Addr: end.src6().src,
Ifindex: end.dst6().ZoneId,
},
}
if cmsg.pktinfo.Addr == [16]byte{} {
cmsg.pktinfo.Ifindex = 0
}
_, err := unix.SendmsgN(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], end.dst6(), 0)
if err == nil {
return nil
}
// clear src and retry
if err == unix.EINVAL {
end.ClearSrc()
cmsg.pktinfo = unix.Inet6Pktinfo{}
_, err = unix.SendmsgN(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], end.dst6(), 0)
}
return err
}
func receive4(sock int, buff []byte, end *NativeEndpoint) (int, error) {
// contruct message header
var cmsg struct {
cmsghdr unix.Cmsghdr
pktinfo unix.Inet4Pktinfo
}
size, _, _, newDst, err := unix.Recvmsg(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], 0)
if err != nil {
return 0, err
}
end.isV6 = false
if newDst4, ok := newDst.(*unix.SockaddrInet4); ok {
*end.dst4() = *newDst4
}
// update source cache
if cmsg.cmsghdr.Level == unix.IPPROTO_IP &&
cmsg.cmsghdr.Type == unix.IP_PKTINFO &&
cmsg.cmsghdr.Len >= unix.SizeofInet4Pktinfo {
end.src4().src = cmsg.pktinfo.Spec_dst
end.src4().ifindex = cmsg.pktinfo.Ifindex
}
return size, nil
}
func receive6(sock int, buff []byte, end *NativeEndpoint) (int, error) {
// contruct message header
var cmsg struct {
cmsghdr unix.Cmsghdr
pktinfo unix.Inet6Pktinfo
}
size, _, _, newDst, err := unix.Recvmsg(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], 0)
if err != nil {
return 0, err
}
end.isV6 = true
if newDst6, ok := newDst.(*unix.SockaddrInet6); ok {
*end.dst6() = *newDst6
}
// update source cache
if cmsg.cmsghdr.Level == unix.IPPROTO_IPV6 &&
cmsg.cmsghdr.Type == unix.IPV6_PKTINFO &&
cmsg.cmsghdr.Len >= unix.SizeofInet6Pktinfo {
end.src6().src = cmsg.pktinfo.Addr
end.dst6().ZoneId = cmsg.pktinfo.Ifindex
}
return size, nil
}
func (bind *nativeBind) routineRouteListener(device *Device) {
type peerEndpointPtr struct {
peer *Peer
endpoint *Endpoint
}
var reqPeer map[uint32]peerEndpointPtr
var reqPeerLock sync.Mutex
defer unix.Close(bind.netlinkSock)
for msg := make([]byte, 1<<16); ; {
var err error
var msgn int
for {
msgn, _, _, _, err = unix.Recvmsg(bind.netlinkSock, msg[:], nil, 0)
if err == nil || !rwcancel.RetryAfterError(err) {
break
}
if !bind.netlinkCancel.ReadyRead() {
return
}
}
if err != nil {
return
}
for remain := msg[:msgn]; len(remain) >= unix.SizeofNlMsghdr; {
hdr := *(*unix.NlMsghdr)(unsafe.Pointer(&remain[0]))
if uint(hdr.Len) > uint(len(remain)) {
break
}
switch hdr.Type {
case unix.RTM_NEWROUTE, unix.RTM_DELROUTE:
if hdr.Seq <= MaxPeers && hdr.Seq > 0 {
if uint(len(remain)) < uint(hdr.Len) {
break
}
if hdr.Len > unix.SizeofNlMsghdr+unix.SizeofRtMsg {
attr := remain[unix.SizeofNlMsghdr+unix.SizeofRtMsg:]
for {
if uint(len(attr)) < uint(unix.SizeofRtAttr) {
break
}
attrhdr := *(*unix.RtAttr)(unsafe.Pointer(&attr[0]))
if attrhdr.Len < unix.SizeofRtAttr || uint(len(attr)) < uint(attrhdr.Len) {
break
}
if attrhdr.Type == unix.RTA_OIF && attrhdr.Len == unix.SizeofRtAttr+4 {
ifidx := *(*uint32)(unsafe.Pointer(&attr[unix.SizeofRtAttr]))
reqPeerLock.Lock()
if reqPeer == nil {
reqPeerLock.Unlock()
break
}
pePtr, ok := reqPeer[hdr.Seq]
reqPeerLock.Unlock()
if !ok {
break
}
pePtr.peer.Lock()
if &pePtr.peer.endpoint != pePtr.endpoint {
pePtr.peer.Unlock()
break
}
if uint32(pePtr.peer.endpoint.(*NativeEndpoint).src4().ifindex) == ifidx {
pePtr.peer.Unlock()
break
}
pePtr.peer.endpoint.(*NativeEndpoint).ClearSrc()
pePtr.peer.Unlock()
}
attr = attr[attrhdr.Len:]
}
}
break
}
reqPeerLock.Lock()
reqPeer = make(map[uint32]peerEndpointPtr)
reqPeerLock.Unlock()
go func() {
device.peers.RLock()
i := uint32(1)
for _, peer := range device.peers.keyMap {
peer.RLock()
if peer.endpoint == nil || peer.endpoint.(*NativeEndpoint) == nil {
peer.RUnlock()
continue
}
if peer.endpoint.(*NativeEndpoint).isV6 || peer.endpoint.(*NativeEndpoint).src4().ifindex == 0 {
peer.RUnlock()
break
}
nlmsg := struct {
hdr unix.NlMsghdr
msg unix.RtMsg
dsthdr unix.RtAttr
dst [4]byte
srchdr unix.RtAttr
src [4]byte
markhdr unix.RtAttr
mark uint32
}{
unix.NlMsghdr{
Type: uint16(unix.RTM_GETROUTE),
Flags: unix.NLM_F_REQUEST,
Seq: i,
},
unix.RtMsg{
Family: unix.AF_INET,
Dst_len: 32,
Src_len: 32,
},
unix.RtAttr{
Len: 8,
Type: unix.RTA_DST,
},
peer.endpoint.(*NativeEndpoint).dst4().Addr,
unix.RtAttr{
Len: 8,
Type: unix.RTA_SRC,
},
peer.endpoint.(*NativeEndpoint).src4().src,
unix.RtAttr{
Len: 8,
Type: unix.RTA_MARK,
},
uint32(bind.lastMark),
}
nlmsg.hdr.Len = uint32(unsafe.Sizeof(nlmsg))
reqPeerLock.Lock()
reqPeer[i] = peerEndpointPtr{
peer: peer,
endpoint: &peer.endpoint,
}
reqPeerLock.Unlock()
peer.RUnlock()
i++
_, err := bind.netlinkCancel.Write((*[unsafe.Sizeof(nlmsg)]byte)(unsafe.Pointer(&nlmsg))[:])
if err != nil {
break
}
}
device.peers.RUnlock()
}()
}
remain = remain[hdr.Len:]
}
}
}