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tailscale/net/netns/netns_windows.go

223 lines
6.1 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package netns
import (
"fmt"
"math/bits"
"net/netip"
"strings"
"syscall"
"golang.org/x/sys/cpu"
"golang.org/x/sys/windows"
"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
"tailscale.com/envknob"
"tailscale.com/net/netmon"
"tailscale.com/tsconst"
"tailscale.com/types/logger"
)
func interfaceIndex(iface *winipcfg.IPAdapterAddresses) uint32 {
if iface == nil {
// The zero ifidx means "unspecified". If we end up passing zero
// to bindSocket*(), it unsets the binding and lets the socket
// behave as normal again, which is what we want if there's no
// default route we can use.
return 0
}
return iface.IfIndex
}
func defaultInterfaceIndex(family winipcfg.AddressFamily) (uint32, error) {
iface, err := netmon.GetWindowsDefault(family)
if err != nil {
return 0, err
}
return interfaceIndex(iface), nil
}
func control(logf logger.Logf, _ *netmon.Monitor) func(network, address string, c syscall.RawConn) error {
return func(network, address string, c syscall.RawConn) error {
return controlC(logf, network, address, c)
}
}
var bindToInterfaceByRouteEnv = envknob.RegisterBool("TS_BIND_TO_INTERFACE_BY_ROUTE")
// controlC binds c to the Windows interface that holds a default
// route, and is not the Tailscale WinTun interface.
func controlC(logf logger.Logf, network, address string, c syscall.RawConn) (err error) {
if isLocalhost(address) {
// Don't bind to an interface for localhost connections,
// otherwise we get:
// connectex: The requested address is not valid in its context
// (The derphttp tests were failing)
return nil
}
canV4, canV6 := false, false
switch network {
case "tcp", "udp":
canV4, canV6 = true, true
case "tcp4", "udp4":
canV4 = true
case "tcp6", "udp6":
canV6 = true
}
var defIfaceIdxV4, defIfaceIdxV6 uint32
if canV4 {
defIfaceIdxV4, err = defaultInterfaceIndex(windows.AF_INET)
if err != nil {
return fmt.Errorf("defaultInterfaceIndex(AF_INET): %w", err)
}
}
if canV6 {
defIfaceIdxV6, err = defaultInterfaceIndex(windows.AF_INET6)
if err != nil {
return fmt.Errorf("defaultInterfaceIndex(AF_INET6): %w", err)
}
}
var ifaceIdxV4, ifaceIdxV6 uint32
if useRoute := bindToInterfaceByRoute.Load() || bindToInterfaceByRouteEnv(); useRoute {
addr, err := parseAddress(address)
if err == nil {
if canV4 && (addr.Is4() || addr.Is4In6()) {
addrV4 := addr.Unmap()
ifaceIdxV4, err = getInterfaceIndex(logf, addrV4, defIfaceIdxV4)
if err != nil {
return fmt.Errorf("getInterfaceIndex(%v): %w", addrV4, err)
}
}
if canV6 && addr.Is6() {
ifaceIdxV6, err = getInterfaceIndex(logf, addr, defIfaceIdxV6)
if err != nil {
return fmt.Errorf("getInterfaceIndex(%v): %w", addr, err)
}
}
} else {
logf("[unexpected] netns: error parsing address %q: %v", address, err)
ifaceIdxV4, ifaceIdxV6 = defIfaceIdxV4, defIfaceIdxV6
}
} else {
ifaceIdxV4, ifaceIdxV6 = defIfaceIdxV4, defIfaceIdxV6
}
if canV4 {
if err := bindSocket4(c, ifaceIdxV4); err != nil {
return fmt.Errorf("bindSocket4(%d): %w", ifaceIdxV4, err)
}
}
if canV6 {
if err := bindSocket6(c, ifaceIdxV6); err != nil {
return fmt.Errorf("bindSocket6(%d): %w", ifaceIdxV6, err)
}
}
return nil
}
func getInterfaceIndex(logf logger.Logf, addr netip.Addr, defaultIdx uint32) (idx uint32, err error) {
idx, err = interfaceIndexFor(addr)
if err != nil {
return defaultIdx, fmt.Errorf("interfaceIndexFor: %w", err)
}
isTS, err := isTailscaleInterface(idx)
if err != nil {
return defaultIdx, fmt.Errorf("isTailscaleInterface: %w", err)
}
if isTS {
return defaultIdx, nil
}
return idx, nil
}
func isTailscaleInterface(ifaceIdx uint32) (bool, error) {
ifaceLUID, err := winipcfg.LUIDFromIndex(ifaceIdx)
if err != nil {
return false, err
}
iface, err := ifaceLUID.Interface()
if err != nil {
return false, err
}
result := iface.Type == winipcfg.IfTypePropVirtual &&
strings.Contains(iface.Description(), tsconst.WintunInterfaceDesc)
return result, nil
}
func interfaceIndexFor(addr netip.Addr) (uint32, error) {
var sockaddr winipcfg.RawSockaddrInet
if err := sockaddr.SetAddr(addr); err != nil {
return 0, err
}
var idx uint32
if err := getBestInterfaceEx(&sockaddr, &idx); err != nil {
return 0, err
}
return idx, nil
}
// sockoptBoundInterface is the value of IP_UNICAST_IF and IPV6_UNICAST_IF.
//
// See https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options
// and https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ipv6-socket-options
const sockoptBoundInterface = 31
// bindSocket4 binds the given RawConn to the network interface with
// index ifidx, for IPv4 traffic only.
func bindSocket4(c syscall.RawConn, ifidx uint32) error {
// For IPv4 (but NOT IPv6) the interface index must be passed
// as a big-endian integer (regardless of platform endianness)
// because the underlying sockopt takes either an IPv4 address
// or an index shoved into IPv4 address representation (an IP
// in 0.0.0.0/8 means it's actually an index).
//
// See https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options
// and IP_UNICAST_IF.
indexAsAddr := nativeToBigEndian(ifidx)
var controlErr error
err := c.Control(func(fd uintptr) {
controlErr = windows.SetsockoptInt(windows.Handle(fd), windows.IPPROTO_IP, sockoptBoundInterface, int(indexAsAddr))
})
if err != nil {
return err
}
return controlErr
}
// bindSocket6 binds the given RawConn to the network interface with
// index ifidx, for IPv6 traffic only.
func bindSocket6(c syscall.RawConn, ifidx uint32) error {
var controlErr error
err := c.Control(func(fd uintptr) {
controlErr = windows.SetsockoptInt(windows.Handle(fd), windows.IPPROTO_IPV6, sockoptBoundInterface, int(ifidx))
})
if err != nil {
return err
}
return controlErr
}
// nativeToBigEndian returns i converted into big-endian
// representation, suitable for passing to Windows APIs that require a
// mangled uint32.
func nativeToBigEndian(i uint32) uint32 {
if cpu.IsBigEndian {
return i
}
return bits.ReverseBytes32(i)
}