tailscale/net/tstun/wrap_test.go
Maisem Ali bb31fd7d1c net/tstun: add inital support for NAT v4
This adds support in tstun to utitilize the SelfNodeV4MasqAddrForThisPeer and
perform the necessary modifications to the packet as it passes through tstun.

Currently this only handles ICMP, UDP and TCP traffic.
Subnet routers and Exit Nodes are also unsupported.

Updates tailscale/corp#8020

Co-authored-by: Melanie Warrick <warrick@tailscale.com>
Signed-off-by: Maisem Ali <maisem@tailscale.com>
2023-03-23 16:54:12 -07:00

724 lines
17 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package tstun
import (
"bytes"
"context"
"encoding/binary"
"encoding/hex"
"fmt"
"net/netip"
"strconv"
"strings"
"testing"
"unicode"
"unsafe"
"github.com/google/go-cmp/cmp"
"github.com/google/go-cmp/cmp/cmpopts"
"github.com/tailscale/wireguard-go/tun/tuntest"
"go4.org/mem"
"go4.org/netipx"
"tailscale.com/disco"
"tailscale.com/net/connstats"
"tailscale.com/net/netaddr"
"tailscale.com/net/packet"
"tailscale.com/tailcfg"
"tailscale.com/tstest"
"tailscale.com/tstime/mono"
"tailscale.com/types/ipproto"
"tailscale.com/types/key"
"tailscale.com/types/logger"
"tailscale.com/types/netlogtype"
"tailscale.com/types/netmap"
"tailscale.com/util/must"
"tailscale.com/wgengine/filter"
)
func udp4(src, dst string, sport, dport uint16) []byte {
sip, err := netip.ParseAddr(src)
if err != nil {
panic(err)
}
dip, err := netip.ParseAddr(dst)
if err != nil {
panic(err)
}
header := &packet.UDP4Header{
IP4Header: packet.IP4Header{
Src: sip,
Dst: dip,
IPID: 0,
},
SrcPort: sport,
DstPort: dport,
}
return packet.Generate(header, []byte("udp_payload"))
}
func tcp4syn(src, dst string, sport, dport uint16) []byte {
sip, err := netip.ParseAddr(src)
if err != nil {
panic(err)
}
dip, err := netip.ParseAddr(dst)
if err != nil {
panic(err)
}
ipHeader := packet.IP4Header{
IPProto: ipproto.TCP,
Src: sip,
Dst: dip,
IPID: 0,
}
tcpHeader := make([]byte, 20)
binary.BigEndian.PutUint16(tcpHeader[0:], sport)
binary.BigEndian.PutUint16(tcpHeader[2:], dport)
tcpHeader[13] |= 2 // SYN
both := packet.Generate(ipHeader, tcpHeader)
// 20 byte IP4 + 20 byte TCP
binary.BigEndian.PutUint16(both[2:4], 40)
return both
}
func nets(nets ...string) (ret []netip.Prefix) {
for _, s := range nets {
if i := strings.IndexByte(s, '/'); i == -1 {
ip, err := netip.ParseAddr(s)
if err != nil {
panic(err)
}
bits := uint8(32)
if ip.Is6() {
bits = 128
}
ret = append(ret, netip.PrefixFrom(ip, int(bits)))
} else {
pfx, err := netip.ParsePrefix(s)
if err != nil {
panic(err)
}
ret = append(ret, pfx)
}
}
return ret
}
func ports(s string) filter.PortRange {
if s == "*" {
return filter.PortRange{First: 0, Last: 65535}
}
var fs, ls string
i := strings.IndexByte(s, '-')
if i == -1 {
fs = s
ls = fs
} else {
fs = s[:i]
ls = s[i+1:]
}
first, err := strconv.ParseInt(fs, 10, 16)
if err != nil {
panic(fmt.Sprintf("invalid NetPortRange %q", s))
}
last, err := strconv.ParseInt(ls, 10, 16)
if err != nil {
panic(fmt.Sprintf("invalid NetPortRange %q", s))
}
return filter.PortRange{First: uint16(first), Last: uint16(last)}
}
func netports(netPorts ...string) (ret []filter.NetPortRange) {
for _, s := range netPorts {
i := strings.LastIndexByte(s, ':')
if i == -1 {
panic(fmt.Sprintf("invalid NetPortRange %q", s))
}
npr := filter.NetPortRange{
Net: nets(s[:i])[0],
Ports: ports(s[i+1:]),
}
ret = append(ret, npr)
}
return ret
}
func setfilter(logf logger.Logf, tun *Wrapper) {
protos := []ipproto.Proto{
ipproto.TCP,
ipproto.UDP,
}
matches := []filter.Match{
{IPProto: protos, Srcs: nets("5.6.7.8"), Dsts: netports("1.2.3.4:89-90")},
{IPProto: protos, Srcs: nets("1.2.3.4"), Dsts: netports("5.6.7.8:98")},
}
var sb netipx.IPSetBuilder
sb.AddPrefix(netip.MustParsePrefix("1.2.0.0/16"))
ipSet, _ := sb.IPSet()
tun.SetFilter(filter.New(matches, ipSet, ipSet, nil, logf))
}
func newChannelTUN(logf logger.Logf, secure bool) (*tuntest.ChannelTUN, *Wrapper) {
chtun := tuntest.NewChannelTUN()
tun := Wrap(logf, chtun.TUN())
if secure {
setfilter(logf, tun)
} else {
tun.disableFilter = true
}
return chtun, tun
}
func newFakeTUN(logf logger.Logf, secure bool) (*fakeTUN, *Wrapper) {
ftun := NewFake()
tun := Wrap(logf, ftun)
if secure {
setfilter(logf, tun)
} else {
tun.disableFilter = true
}
return ftun.(*fakeTUN), tun
}
func TestReadAndInject(t *testing.T) {
chtun, tun := newChannelTUN(t.Logf, false)
defer tun.Close()
const size = 2 // all payloads have this size
written := []string{"w0", "w1"}
injected := []string{"i0", "i1"}
go func() {
for _, packet := range written {
payload := []byte(packet)
chtun.Outbound <- payload
}
}()
for _, packet := range injected {
go func(packet string) {
payload := []byte(packet)
err := tun.InjectOutbound(payload)
if err != nil {
t.Errorf("%s: error: %v", packet, err)
}
}(packet)
}
var buf [MaxPacketSize]byte
var seen = make(map[string]bool)
sizes := make([]int, 1)
// We expect the same packets back, in no particular order.
for i := 0; i < len(written)+len(injected); i++ {
packet := buf[:]
buffs := [][]byte{packet}
numPackets, err := tun.Read(buffs, sizes, 0)
if err != nil {
t.Errorf("read %d: error: %v", i, err)
}
if numPackets != 1 {
t.Fatalf("read %d packets, expected %d", numPackets, 1)
}
packet = packet[:sizes[0]]
packetLen := len(packet)
if packetLen != size {
t.Errorf("read %d: got size %d; want %d", i, packetLen, size)
}
got := string(packet)
t.Logf("read %d: got %s", i, got)
seen[got] = true
}
for _, packet := range written {
if !seen[packet] {
t.Errorf("%s not received", packet)
}
}
for _, packet := range injected {
if !seen[packet] {
t.Errorf("%s not received", packet)
}
}
}
func TestWriteAndInject(t *testing.T) {
chtun, tun := newChannelTUN(t.Logf, false)
defer tun.Close()
const size = 2 // all payloads have this size
written := []string{"w0", "w1"}
injected := []string{"i0", "i1"}
go func() {
for _, packet := range written {
payload := []byte(packet)
_, err := tun.Write([][]byte{payload}, 0)
if err != nil {
t.Errorf("%s: error: %v", packet, err)
}
}
}()
for _, packet := range injected {
go func(packet string) {
payload := []byte(packet)
err := tun.InjectInboundCopy(payload)
if err != nil {
t.Errorf("%s: error: %v", packet, err)
}
}(packet)
}
seen := make(map[string]bool)
// We expect the same packets back, in no particular order.
for i := 0; i < len(written)+len(injected); i++ {
packet := <-chtun.Inbound
got := string(packet)
t.Logf("read %d: got %s", i, got)
seen[got] = true
}
for _, packet := range written {
if !seen[packet] {
t.Errorf("%s not received", packet)
}
}
for _, packet := range injected {
if !seen[packet] {
t.Errorf("%s not received", packet)
}
}
}
// mustHexDecode is like hex.DecodeString, but panics on error
// and ignores whitespace in s.
func mustHexDecode(s string) []byte {
return must.Get(hex.DecodeString(strings.Map(func(r rune) rune {
if unicode.IsSpace(r) {
return -1
}
return r
}, s)))
}
func TestFilter(t *testing.T) {
chtun, tun := newChannelTUN(t.Logf, true)
defer tun.Close()
type direction int
const (
in direction = iota
out
)
tests := []struct {
name string
dir direction
drop bool
data []byte
}{
{"short_in", in, true, []byte("\x45xxx")},
{"short_out", out, true, []byte("\x45xxx")},
{"ip97_out", out, false, mustHexDecode("4500 0019 d186 4000 4061 751d 644a 4603 6449 e549 6865 6c6c 6f")},
{"bad_port_in", in, true, udp4("5.6.7.8", "1.2.3.4", 22, 22)},
{"bad_port_out", out, false, udp4("1.2.3.4", "5.6.7.8", 22, 22)},
{"bad_ip_in", in, true, udp4("8.1.1.1", "1.2.3.4", 89, 89)},
{"bad_ip_out", out, false, udp4("1.2.3.4", "8.1.1.1", 98, 98)},
{"good_packet_in", in, false, udp4("5.6.7.8", "1.2.3.4", 89, 89)},
{"good_packet_out", out, false, udp4("1.2.3.4", "5.6.7.8", 98, 98)},
}
// A reader on the other end of the tun.
go func() {
var recvbuf []byte
for {
select {
case <-tun.closed:
return
case recvbuf = <-chtun.Inbound:
// continue
}
for _, tt := range tests {
if tt.drop && bytes.Equal(recvbuf, tt.data) {
t.Errorf("did not drop %s", tt.name)
}
}
}
}()
var buf [MaxPacketSize]byte
stats := connstats.NewStatistics(0, 0, nil)
defer stats.Shutdown(context.Background())
tun.SetStatistics(stats)
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
var n int
var err error
var filtered bool
sizes := make([]int, 1)
tunStats, _ := stats.TestExtract()
if len(tunStats) > 0 {
t.Errorf("connstats.Statistics.Extract = %v, want {}", stats)
}
if tt.dir == in {
// Use the side effect of updating the last
// activity atomic to determine whether the
// data was actually filtered.
// If it stays zero, nothing made it through
// to the wrapped TUN.
tun.lastActivityAtomic.StoreAtomic(0)
_, err = tun.Write([][]byte{tt.data}, 0)
filtered = tun.lastActivityAtomic.LoadAtomic() == 0
} else {
chtun.Outbound <- tt.data
n, err = tun.Read([][]byte{buf[:]}, sizes, 0)
// In the read direction, errors are fatal, so we return n = 0 instead.
filtered = (n == 0)
}
if err != nil {
t.Errorf("got err %v; want nil", err)
}
if filtered {
if !tt.drop {
t.Errorf("got drop; want accept")
}
} else {
if tt.drop {
t.Errorf("got accept; want drop")
}
}
got, _ := stats.TestExtract()
want := map[netlogtype.Connection]netlogtype.Counts{}
var wasUDP bool
if !tt.drop {
var p packet.Parsed
p.Decode(tt.data)
wasUDP = p.IPProto == ipproto.UDP
switch tt.dir {
case in:
conn := netlogtype.Connection{Proto: ipproto.UDP, Src: p.Dst, Dst: p.Src}
want[conn] = netlogtype.Counts{RxPackets: 1, RxBytes: uint64(len(tt.data))}
case out:
conn := netlogtype.Connection{Proto: ipproto.UDP, Src: p.Src, Dst: p.Dst}
want[conn] = netlogtype.Counts{TxPackets: 1, TxBytes: uint64(len(tt.data))}
}
}
if wasUDP {
if diff := cmp.Diff(got, want, cmpopts.EquateEmpty()); diff != "" {
t.Errorf("stats.TestExtract (-got +want):\n%s", diff)
}
}
})
}
}
func TestAllocs(t *testing.T) {
ftun, tun := newFakeTUN(t.Logf, false)
defer tun.Close()
buf := [][]byte{{0x00}}
err := tstest.MinAllocsPerRun(t, 0, func() {
_, err := ftun.Write(buf, 0)
if err != nil {
t.Errorf("write: error: %v", err)
return
}
})
if err != nil {
t.Error(err)
}
}
func TestClose(t *testing.T) {
ftun, tun := newFakeTUN(t.Logf, false)
data := [][]byte{udp4("1.2.3.4", "5.6.7.8", 98, 98)}
_, err := ftun.Write(data, 0)
if err != nil {
t.Error(err)
}
tun.Close()
_, err = ftun.Write(data, 0)
if err == nil {
t.Error("Expected error from ftun.Write() after Close()")
}
}
func BenchmarkWrite(b *testing.B) {
b.ReportAllocs()
ftun, tun := newFakeTUN(b.Logf, true)
defer tun.Close()
packet := [][]byte{udp4("5.6.7.8", "1.2.3.4", 89, 89)}
for i := 0; i < b.N; i++ {
_, err := ftun.Write(packet, 0)
if err != nil {
b.Errorf("err = %v; want nil", err)
}
}
}
func TestAtomic64Alignment(t *testing.T) {
off := unsafe.Offsetof(Wrapper{}.lastActivityAtomic)
if off%8 != 0 {
t.Errorf("offset %v not 8-byte aligned", off)
}
c := new(Wrapper)
c.lastActivityAtomic.StoreAtomic(mono.Now())
}
func TestPeerAPIBypass(t *testing.T) {
wrapperWithPeerAPI := &Wrapper{
PeerAPIPort: func(ip netip.Addr) (port uint16, ok bool) {
if ip == netip.MustParseAddr("100.64.1.2") {
return 60000, true
}
return
},
}
tests := []struct {
name string
w *Wrapper
filter *filter.Filter
pkt []byte
want filter.Response
}{
{
name: "reject_nil_filter",
w: &Wrapper{
PeerAPIPort: func(netip.Addr) (port uint16, ok bool) {
return 60000, true
},
},
pkt: tcp4syn("1.2.3.4", "100.64.1.2", 1234, 60000),
want: filter.Drop,
},
{
name: "reject_with_filter",
w: &Wrapper{},
filter: filter.NewAllowNone(logger.Discard, new(netipx.IPSet)),
pkt: tcp4syn("1.2.3.4", "100.64.1.2", 1234, 60000),
want: filter.Drop,
},
{
name: "peerapi_bypass_filter",
w: wrapperWithPeerAPI,
filter: filter.NewAllowNone(logger.Discard, new(netipx.IPSet)),
pkt: tcp4syn("1.2.3.4", "100.64.1.2", 1234, 60000),
want: filter.Accept,
},
{
name: "peerapi_dont_bypass_filter_wrong_port",
w: wrapperWithPeerAPI,
filter: filter.NewAllowNone(logger.Discard, new(netipx.IPSet)),
pkt: tcp4syn("1.2.3.4", "100.64.1.2", 1234, 60001),
want: filter.Drop,
},
{
name: "peerapi_dont_bypass_filter_wrong_dst_ip",
w: wrapperWithPeerAPI,
filter: filter.NewAllowNone(logger.Discard, new(netipx.IPSet)),
pkt: tcp4syn("1.2.3.4", "100.64.1.3", 1234, 60000),
want: filter.Drop,
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
p := new(packet.Parsed)
p.Decode(tt.pkt)
tt.w.SetFilter(tt.filter)
tt.w.disableTSMPRejected = true
tt.w.logf = t.Logf
if got := tt.w.filterPacketInboundFromWireGuard(p); got != tt.want {
t.Errorf("got = %v; want %v", got, tt.want)
}
})
}
}
// Issue 1526: drop disco frames from ourselves.
func TestFilterDiscoLoop(t *testing.T) {
var memLog tstest.MemLogger
discoPub := key.DiscoPublicFromRaw32(mem.B([]byte{1: 1, 2: 2, 31: 0}))
tw := &Wrapper{logf: memLog.Logf, limitedLogf: memLog.Logf}
tw.SetDiscoKey(discoPub)
uh := packet.UDP4Header{
IP4Header: packet.IP4Header{
IPProto: ipproto.UDP,
Src: netaddr.IPv4(1, 2, 3, 4),
Dst: netaddr.IPv4(5, 6, 7, 8),
},
SrcPort: 9,
DstPort: 10,
}
discobs := discoPub.Raw32()
discoPayload := fmt.Sprintf("%s%s%s", disco.Magic, discobs[:], [disco.NonceLen]byte{})
pkt := make([]byte, uh.Len()+len(discoPayload))
uh.Marshal(pkt)
copy(pkt[uh.Len():], discoPayload)
p := new(packet.Parsed)
p.Decode(pkt)
got := tw.filterPacketInboundFromWireGuard(p)
if got != filter.DropSilently {
t.Errorf("got %v; want DropSilently", got)
}
if got, want := memLog.String(), "[unexpected] received self disco in packet over tstun; dropping\n"; got != want {
t.Errorf("log output mismatch\n got: %q\nwant: %q\n", got, want)
}
memLog.Reset()
pp := new(packet.Parsed)
pp.Decode(pkt)
got = tw.filterPacketOutboundToWireGuard(pp)
if got != filter.DropSilently {
t.Errorf("got %v; want DropSilently", got)
}
if got, want := memLog.String(), "[unexpected] received self disco out packet over tstun; dropping\n"; got != want {
t.Errorf("log output mismatch\n got: %q\nwant: %q\n", got, want)
}
}
func TestNATCfg(t *testing.T) {
node := func(ip, eip netip.Addr) *tailcfg.Node {
return &tailcfg.Node{
Addresses: []netip.Prefix{
netip.PrefixFrom(ip, ip.BitLen()),
},
SelfNodeV4MasqAddrForThisPeer: eip,
}
}
var (
noIP netip.Addr
selfNativeIP = netip.MustParseAddr("100.64.0.1")
selfEIP1 = netip.MustParseAddr("100.64.1.1")
selfEIP2 = netip.MustParseAddr("100.64.1.2")
peer1IP = netip.MustParseAddr("100.64.0.2")
peer2IP = netip.MustParseAddr("100.64.0.3")
// subnets should not be impacted.
// TODO(maisem/nyghtowl): add support for subnets and exit nodes and test them.
subnet = netip.MustParseAddr("192.168.0.1")
)
tests := []struct {
name string
nm *netmap.NetworkMap
snatMap map[netip.Addr]netip.Addr // dst -> src
dnatMap map[netip.Addr]netip.Addr
}{
{
name: "no-netmap",
nm: nil,
snatMap: map[netip.Addr]netip.Addr{
peer1IP: selfNativeIP,
peer2IP: selfNativeIP,
subnet: selfNativeIP,
},
dnatMap: map[netip.Addr]netip.Addr{
selfNativeIP: selfNativeIP,
selfEIP1: selfEIP1,
selfEIP2: selfEIP2,
},
},
{
name: "single-peer-requires-nat",
nm: &netmap.NetworkMap{
SelfNode: node(selfNativeIP, noIP),
Peers: []*tailcfg.Node{
node(peer1IP, noIP),
node(peer2IP, selfEIP1),
},
},
snatMap: map[netip.Addr]netip.Addr{
peer1IP: selfNativeIP,
peer2IP: selfEIP1,
subnet: selfNativeIP,
},
dnatMap: map[netip.Addr]netip.Addr{
selfNativeIP: selfNativeIP,
selfEIP1: selfNativeIP,
selfEIP2: selfEIP2,
subnet: subnet,
},
},
{
name: "multiple-peers-require-nat",
nm: &netmap.NetworkMap{
SelfNode: node(selfNativeIP, noIP),
Peers: []*tailcfg.Node{
node(peer1IP, selfEIP1),
node(peer2IP, selfEIP2),
},
},
snatMap: map[netip.Addr]netip.Addr{
peer1IP: selfEIP1,
peer2IP: selfEIP2,
subnet: selfNativeIP,
},
dnatMap: map[netip.Addr]netip.Addr{
selfNativeIP: selfNativeIP,
selfEIP1: selfNativeIP,
selfEIP2: selfNativeIP,
subnet: subnet,
},
},
{
name: "no-nat",
nm: &netmap.NetworkMap{
SelfNode: node(selfNativeIP, noIP),
Peers: []*tailcfg.Node{
node(peer1IP, noIP),
node(peer2IP, noIP),
},
},
snatMap: map[netip.Addr]netip.Addr{
peer1IP: selfNativeIP,
peer2IP: selfNativeIP,
subnet: selfNativeIP,
},
dnatMap: map[netip.Addr]netip.Addr{
selfNativeIP: selfNativeIP,
selfEIP1: selfEIP1,
selfEIP2: selfEIP2,
subnet: subnet,
},
},
}
for _, tc := range tests {
t.Run(tc.name, func(t *testing.T) {
ncfg := natConfigFromNetMap(tc.nm)
for peer, want := range tc.snatMap {
if got := ncfg.selectSrcIP(selfNativeIP, peer); got != want {
t.Errorf("selectSrcIP: got %v; want %v", got, want)
}
}
for dstIP, want := range tc.dnatMap {
if got := ncfg.mapDstIP(dstIP); got != want {
t.Errorf("mapDstIP: got %v; want %v", got, want)
}
}
})
}
}