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Remove unusable networks from remote tunnels at handshake time (#1318)

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Nate Brown 2025-01-27 16:40:11 -06:00 committed by GitHub
parent 84dd988f01
commit 1ad0f57c1e
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GPG Key ID: B5690EEEBB952194
5 changed files with 66 additions and 27 deletions
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6
firewall.go
View File

@ -8,7 +8,6 @@ import (
"hash/fnv"
"net/netip"
"reflect"
"slices"
"strconv"
"strings"
"sync"
@ -438,9 +437,8 @@ func (f *Firewall) Drop(fp firewall.Packet, incoming bool, h *HostInfo, caPool *
return ErrInvalidRemoteIP
}
} else {
// Simple case: Certificate has one IP and no subnets
//TODO: we can make this more performant
if !slices.Contains(h.vpnAddrs, fp.RemoteAddr) {
// Simple case: Certificate has one address and no unsafe networks
if h.vpnAddrs[0] != fp.RemoteAddr {
f.metrics(incoming).droppedRemoteAddr.Inc(1)
return ErrInvalidRemoteIP
}

15
firewall_test.go
View File

@ -152,7 +152,7 @@ func TestFirewall_Drop(t *testing.T) {
},
vpnAddrs: []netip.Addr{netip.MustParseAddr("1.2.3.4")},
}
h.buildNetworks(&c)
h.buildNetworks(c.networks, c.unsafeNetworks)
fw := NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
assert.Nil(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"any"}, "", netip.Prefix{}, netip.Prefix{}, "", ""))
@ -332,7 +332,7 @@ func TestFirewall_Drop2(t *testing.T) {
},
vpnAddrs: []netip.Addr{network.Addr()},
}
h.buildNetworks(c.Certificate)
h.buildNetworks(c.Certificate.Networks(), c.Certificate.UnsafeNetworks())
c1 := cert.CachedCertificate{
Certificate: &dummyCert{
@ -342,11 +342,12 @@ func TestFirewall_Drop2(t *testing.T) {
InvertedGroups: map[string]struct{}{"default-group": {}, "test-group-not": {}},
}
h1 := HostInfo{
vpnAddrs: []netip.Addr{network.Addr()},
ConnectionState: &ConnectionState{
peerCert: &c1,
},
}
h1.buildNetworks(c1.Certificate)
h1.buildNetworks(c1.Certificate.Networks(), c1.Certificate.UnsafeNetworks())
fw := NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
assert.Nil(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group", "test-group"}, "", netip.Prefix{}, netip.Prefix{}, "", ""))
@ -394,7 +395,7 @@ func TestFirewall_Drop3(t *testing.T) {
},
vpnAddrs: []netip.Addr{network.Addr()},
}
h1.buildNetworks(c1.Certificate)
h1.buildNetworks(c1.Certificate.Networks(), c1.Certificate.UnsafeNetworks())
c2 := cert.CachedCertificate{
Certificate: &dummyCert{
@ -409,7 +410,7 @@ func TestFirewall_Drop3(t *testing.T) {
},
vpnAddrs: []netip.Addr{network.Addr()},
}
h2.buildNetworks(c2.Certificate)
h2.buildNetworks(c2.Certificate.Networks(), c2.Certificate.UnsafeNetworks())
c3 := cert.CachedCertificate{
Certificate: &dummyCert{
@ -424,7 +425,7 @@ func TestFirewall_Drop3(t *testing.T) {
},
vpnAddrs: []netip.Addr{network.Addr()},
}
h3.buildNetworks(c3.Certificate)
h3.buildNetworks(c3.Certificate.Networks(), c3.Certificate.UnsafeNetworks())
fw := NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
assert.Nil(t, fw.AddRule(true, firewall.ProtoAny, 1, 1, []string{}, "host1", netip.Prefix{}, netip.Prefix{}, "", ""))
@ -471,7 +472,7 @@ func TestFirewall_DropConntrackReload(t *testing.T) {
},
vpnAddrs: []netip.Addr{network.Addr()},
}
h.buildNetworks(c.Certificate)
h.buildNetworks(c.Certificate.Networks(), c.Certificate.UnsafeNetworks())
fw := NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
assert.Nil(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"any"}, "", netip.Prefix{}, netip.Prefix{}, "", ""))

54
handshake_ix.go
View File

@ -172,6 +172,7 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
}
var vpnAddrs []netip.Addr
var filteredNetworks []netip.Prefix
certName := remoteCert.Certificate.Name()
fingerprint := remoteCert.Fingerprint
issuer := remoteCert.Certificate.Issuer()
@ -189,15 +190,32 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
}
if addr.IsValid() {
// addr can be invalid when the tunnel is being relayed.
// We only want to apply the remote allow list for direct tunnels here
if !f.lightHouse.GetRemoteAllowList().Allow(vpnAddr, addr.Addr()) {
f.l.WithField("vpnAddr", vpnAddr).WithField("udpAddr", addr).Debug("lighthouse.remote_allow_list denied incoming handshake")
return
}
}
// vpnAddrs outside our vpn networks are of no use to us, filter them out
if _, ok := f.myVpnNetworksTable.Lookup(vpnAddr); !ok {
continue
}
filteredNetworks = append(filteredNetworks, network)
vpnAddrs = append(vpnAddrs, vpnAddr)
}
if len(vpnAddrs) == 0 {
f.l.WithError(err).WithField("udpAddr", addr).
WithField("certName", certName).
WithField("fingerprint", fingerprint).
WithField("issuer", issuer).
WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).Error("No usable vpn addresses from host, refusing handshake")
return
}
myIndex, err := generateIndex(f.l)
if err != nil {
f.l.WithError(err).WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
@ -294,7 +312,7 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
hostinfo.remotes = f.lightHouse.QueryCache(vpnAddrs)
hostinfo.SetRemote(addr)
hostinfo.buildNetworks(remoteCert.Certificate)
hostinfo.buildNetworks(filteredNetworks, remoteCert.Certificate.UnsafeNetworks())
existing, err := f.handshakeManager.CheckAndComplete(hostinfo, 0, f)
if err != nil {
@ -431,7 +449,7 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
hostinfo := hh.hostinfo
if addr.IsValid() {
//TODO: this is kind of nonsense now
// The vpnAddr we know about is the one we tried to handshake with, use it to apply the remote allow list.
if !f.lightHouse.GetRemoteAllowList().Allow(hostinfo.vpnAddrs[0], addr.Addr()) {
f.l.WithField("vpnIp", hostinfo.vpnAddrs).WithField("udpAddr", addr).Debug("lighthouse.remote_allow_list denied incoming handshake")
return false
@ -492,7 +510,7 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
e = e.WithField("cert", remoteCert)
}
e.Info("Invalid vpn ip from host")
e.Info("Empty networks from host")
return true
}
@ -516,9 +534,26 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
hostinfo.relayState.InsertRelayTo(via.relayHI.vpnAddrs[0])
}
vpnAddrs := make([]netip.Addr, len(vpnNetworks))
for i, n := range vpnNetworks {
vpnAddrs[i] = n.Addr()
var vpnAddrs []netip.Addr
var filteredNetworks []netip.Prefix
for _, network := range vpnNetworks {
// vpnAddrs outside our vpn networks are of no use to us, filter them out
vpnAddr := network.Addr()
if _, ok := f.myVpnNetworksTable.Lookup(vpnAddr); !ok {
continue
}
filteredNetworks = append(filteredNetworks, network)
vpnAddrs = append(vpnAddrs, vpnAddr)
}
if len(vpnAddrs) == 0 {
f.l.WithError(err).WithField("udpAddr", addr).
WithField("certName", certName).
WithField("fingerprint", fingerprint).
WithField("issuer", issuer).
WithField("handshake", m{"stage": 2, "style": "ix_psk0"}).Error("No usable vpn addresses from host, refusing handshake")
return true
}
// Ensure the right host responded
@ -558,7 +593,7 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
ci.window.Update(f.l, 2)
duration := time.Since(hh.startTime).Nanoseconds()
f.l.WithField("vpnNetworks", vpnNetworks).WithField("udpAddr", addr).
f.l.WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
WithField("certName", certName).
WithField("fingerprint", fingerprint).
WithField("issuer", issuer).
@ -569,9 +604,10 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
Info("Handshake message received")
// Build up the radix for the firewall if we have subnets in the cert
hostinfo.buildNetworks(remoteCert.Certificate)
hostinfo.vpnAddrs = vpnAddrs
hostinfo.buildNetworks(filteredNetworks, remoteCert.Certificate.UnsafeNetworks())
// Complete our handshake and update metrics, this will replace any existing tunnels for this vpnIp
// Complete our handshake and update metrics, this will replace any existing tunnels for the vpnAddrs here
f.handshakeManager.Complete(hostinfo, f)
f.connectionManager.AddTrafficWatch(hostinfo.localIndexId)

16
hostmap.go
View File

@ -215,8 +215,12 @@ type HostInfo struct {
ConnectionState *ConnectionState
remoteIndexId uint32
localIndexId uint32
vpnAddrs []netip.Addr
recvError atomic.Uint32
// vpnAddrs is a list of vpn addresses assigned to this host that are within our own vpn networks
// The host may have other vpn addresses that are outside our
// vpn networks but were removed because they are not usable
vpnAddrs []netip.Addr
recvError atomic.Uint32
// networks are both all vpn and unsafe networks assigned to this host
networks *bart.Table[struct{}]
@ -712,18 +716,18 @@ func (i *HostInfo) RecvErrorExceeded() bool {
return true
}
func (i *HostInfo) buildNetworks(c cert.Certificate) {
if len(c.Networks()) == 1 && len(c.UnsafeNetworks()) == 0 {
func (i *HostInfo) buildNetworks(networks, unsafeNetworks []netip.Prefix) {
if len(networks) == 1 && len(unsafeNetworks) == 0 {
// Simple case, no CIDRTree needed
return
}
i.networks = new(bart.Table[struct{}])
for _, network := range c.Networks() {
for _, network := range networks {
i.networks.Insert(network, struct{}{})
}
for _, network := range c.UnsafeNetworks() {
for _, network := range unsafeNetworks {
i.networks.Insert(network, struct{}{})
}
}

2
interface.go
View File

@ -64,7 +64,7 @@ type Interface struct {
myBroadcastAddrsTable *bart.Table[struct{}]
myVpnAddrs []netip.Addr // A list of addresses assigned to us via our certificate
myVpnAddrsTable *bart.Table[struct{}] // A table of addresses assigned to us via our certificate
myVpnNetworks []netip.Prefix // A table of networks assigned to us via our certificate
myVpnNetworks []netip.Prefix // A list of networks assigned to us via our certificate
myVpnNetworksTable *bart.Table[struct{}] // A table of networks assigned to us via our certificate
dropLocalBroadcast bool
dropMulticast bool