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wgengine/netstack: Allow userspace networking mode to expose subnets (#1588)

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wgengine/netstack: Allow userspace networking mode to expose subnets

Updates #504

Updates #707

Signed-off-by: Naman Sood <mail@nsood.in>
crawshaw/cgi
Naman Sood 3 years ago committed by GitHub
parent a4c679e646
commit 662fbd4a09
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 114 additions and 38 deletions
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152
wgengine/netstack/netstack.go
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@ -31,6 +31,7 @@ import (
"inet.af/netstack/tcpip/transport/udp"
"inet.af/netstack/waiter"
"tailscale.com/net/packet"
"tailscale.com/net/tsaddr"
"tailscale.com/net/tstun"
"tailscale.com/types/logger"
"tailscale.com/types/netmap"
@ -55,6 +56,11 @@ type Impl struct {
mu sync.Mutex
dns DNSMap
// connsOpenBySubnetIP keeps track of number of connections open
// for each subnet IP temporarily registered on netstack for active
// TCP connections, so they can be unregistered when connections are
// closed.
connsOpenBySubnetIP map[netaddr.IP]int
}
const nicID = 1
@ -82,6 +88,12 @@ func Create(logf logger.Logf, tundev *tstun.Wrapper, e wgengine.Engine, mc *magi
if tcpipProblem := ipstack.CreateNIC(nicID, linkEP); tcpipProblem != nil {
return nil, fmt.Errorf("could not create netstack NIC: %v", tcpipProblem)
}
// By default the netstack NIC will only accept packets for the IPs
// registered to it. Since in some cases we dynamically register IPs
// based on the packets that arrive, the NIC needs to accept all
// incoming packets. The NIC won't receive anything it isn't meant to
// since Wireguard will only send us packets that are meant for us.
ipstack.SetPromiscuousMode(nicID, true)
// Add IPv4 and IPv6 default routes, so all incoming packets from the Tailscale side
// are handled by the one fake NIC we use.
ipv4Subnet, _ := tcpip.NewSubnet(tcpip.Address(strings.Repeat("\x00", 4)), tcpip.AddressMask(strings.Repeat("\x00", 4)))
@ -97,12 +109,13 @@ func Create(logf logger.Logf, tundev *tstun.Wrapper, e wgengine.Engine, mc *magi
},
})
ns := &Impl{
logf: logf,
ipstack: ipstack,
linkEP: linkEP,
tundev: tundev,
e: e,
mc: mc,
logf: logf,
ipstack: ipstack,
linkEP: linkEP,
tundev: tundev,
e: e,
mc: mc,
connsOpenBySubnetIP: make(map[netaddr.IP]int),
}
return ns, nil
}
@ -116,7 +129,24 @@ func (ns *Impl) Start() error {
const maxInFlightConnectionAttempts = 16
tcpFwd := tcp.NewForwarder(ns.ipstack, tcpReceiveBufferSize, maxInFlightConnectionAttempts, ns.acceptTCP)
udpFwd := udp.NewForwarder(ns.ipstack, ns.acceptUDP)
ns.ipstack.SetTransportProtocolHandler(tcp.ProtocolNumber, tcpFwd.HandlePacket)
ns.ipstack.SetTransportProtocolHandler(tcp.ProtocolNumber, func(tei stack.TransportEndpointID, pb *stack.PacketBuffer) bool {
addr := tei.LocalAddress
var pn tcpip.NetworkProtocolNumber
if addr.To4() != "" {
pn = ipv4.ProtocolNumber
} else {
pn = ipv6.ProtocolNumber
}
ip, ok := netaddr.FromStdIP(net.IP(addr))
if !ok {
ns.logf("netstack: could not parse local address %s for incoming TCP connection", ip)
return false
}
if !tsaddr.IsTailscaleIP(ip) {
ns.addSubnetAddress(pn, ip)
}
return tcpFwd.HandlePacket(tei, pb)
})
ns.ipstack.SetTransportProtocolHandler(udp.ProtocolNumber, udpFwd.HandlePacket)
go ns.injectOutbound()
ns.tundev.PostFilterIn = ns.injectInbound
@ -156,50 +186,86 @@ func (ns *Impl) updateDNS(nm *netmap.NetworkMap) {
ns.dns = DNSMapFromNetworkMap(nm)
}
func (ns *Impl) addSubnetAddress(pn tcpip.NetworkProtocolNumber, ip netaddr.IP) {
ns.mu.Lock()
ns.connsOpenBySubnetIP[ip]++
needAdd := ns.connsOpenBySubnetIP[ip] == 1
ns.mu.Unlock()
// Only register address into netstack for first concurrent connection.
if needAdd {
ns.ipstack.AddAddress(nicID, pn, tcpip.Address(ip.IPAddr().IP))
}
}
func (ns *Impl) removeSubnetAddress(ip netaddr.IP) {
ns.mu.Lock()
defer ns.mu.Unlock()
ns.connsOpenBySubnetIP[ip]--
// Only unregister address from netstack after last concurrent connection.
if ns.connsOpenBySubnetIP[ip] == 0 {
ns.ipstack.RemoveAddress(nicID, tcpip.Address(ip.IPAddr().IP))
delete(ns.connsOpenBySubnetIP, ip)
}
}
func ipPrefixToAddressWithPrefix(ipp netaddr.IPPrefix) tcpip.AddressWithPrefix {
return tcpip.AddressWithPrefix{
Address: tcpip.Address(ipp.IP.IPAddr().IP),
PrefixLen: int(ipp.Bits),
}
}
func (ns *Impl) updateIPs(nm *netmap.NetworkMap) {
ns.updateDNS(nm)
oldIPs := make(map[tcpip.Address]bool)
for _, ip := range ns.ipstack.AllAddresses()[nicID] {
oldIPs[ip.AddressWithPrefix.Address] = true
oldIPs := make(map[tcpip.AddressWithPrefix]bool)
for _, protocolAddr := range ns.ipstack.AllAddresses()[nicID] {
oldIPs[protocolAddr.AddressWithPrefix] = true
}
newIPs := make(map[tcpip.Address]bool)
for _, ip := range nm.Addresses {
newIPs[tcpip.Address(ip.IP.IPAddr().IP)] = true
newIPs := make(map[tcpip.AddressWithPrefix]bool)
for _, ipp := range nm.SelfNode.AllowedIPs {
newIPs[ipPrefixToAddressWithPrefix(ipp)] = true
}
ipsToBeAdded := make(map[tcpip.Address]bool)
for ip := range newIPs {
if !oldIPs[ip] {
ipsToBeAdded[ip] = true
ipsToBeAdded := make(map[tcpip.AddressWithPrefix]bool)
for ipp := range newIPs {
if !oldIPs[ipp] {
ipsToBeAdded[ipp] = true
}
}
ipsToBeRemoved := make(map[tcpip.Address]bool)
ipsToBeRemoved := make(map[tcpip.AddressWithPrefix]bool)
for ip := range oldIPs {
if !newIPs[ip] {
ipsToBeRemoved[ip] = true
}
}
ns.mu.Lock()
for ip := range ns.connsOpenBySubnetIP {
ipp := tcpip.Address(ip.IPAddr().IP).WithPrefix()
ipsToBeAdded[ipp] = true
delete(ipsToBeRemoved, ipp)
}
ns.mu.Unlock()
for ip := range ipsToBeRemoved {
err := ns.ipstack.RemoveAddress(nicID, ip)
for ipp := range ipsToBeRemoved {
err := ns.ipstack.RemoveAddress(nicID, ipp.Address)
if err != nil {
ns.logf("netstack: could not deregister IP %s: %v", ip, err)
ns.logf("netstack: could not deregister IP %s: %v", ipp, err)
} else {
ns.logf("[v2] netstack: deregistered IP %s", ip)
ns.logf("[v2] netstack: deregistered IP %s", ipp)
}
}
for ip := range ipsToBeAdded {
for ipp := range ipsToBeAdded {
var err tcpip.Error
if ip.To4() == "" {
err = ns.ipstack.AddAddress(nicID, ipv6.ProtocolNumber, ip)
if ipp.Address.To4() == "" {
err = ns.ipstack.AddAddressWithPrefix(nicID, ipv6.ProtocolNumber, ipp)
} else {
err = ns.ipstack.AddAddress(nicID, ipv4.ProtocolNumber, ip)
err = ns.ipstack.AddAddressWithPrefix(nicID, ipv4.ProtocolNumber, ipp)
}
if err != nil {
ns.logf("netstack: could not register IP %s: %v", ip, err)
ns.logf("netstack: could not register IP %s: %v", ipp, err)
} else {
ns.logf("[v2] netstack: registered IP %s", ip)
ns.logf("[v2] netstack: registered IP %s", ipp)
}
}
}
@ -322,25 +388,35 @@ func (ns *Impl) acceptTCP(r *tcp.ForwarderRequest) {
// ForwarderRequest: &{{{{0 0}}} 0xc0001c30b0 0xc0004c3d40 {1240 6 true 826109390 0 true}
ns.logf("[v2] ForwarderRequest: %v", r)
}
reqDetails := r.ID()
dialAddr := reqDetails.LocalAddress
dialNetAddr, _ := netaddr.FromStdIP(net.IP(dialAddr))
isTailscaleIP := tsaddr.IsTailscaleIP(dialNetAddr)
defer func() {
if !isTailscaleIP {
// if this is a subnet IP, we added this in before the TCP handshake
// so netstack is happy TCP-handshaking as a subnet IP
ns.removeSubnetAddress(dialNetAddr)
}
}()
var wq waiter.Queue
ep, err := r.CreateEndpoint(&wq)
if err != nil {
r.Complete(true)
return
}
localAddr, err := ep.GetLocalAddress()
if err != nil {
r.Complete(true)
return
if isTailscaleIP {
dialAddr = tcpip.Address(net.ParseIP("127.0.0.1")).To4()
}
r.Complete(false)
c := gonet.NewTCPConn(&wq, ep)
go ns.forwardTCP(c, &wq, localAddr.Port)
ns.forwardTCP(c, &wq, dialAddr, reqDetails.LocalPort)
}
func (ns *Impl) forwardTCP(client *gonet.TCPConn, wq *waiter.Queue, port uint16) {
func (ns *Impl) forwardTCP(client *gonet.TCPConn, wq *waiter.Queue, dialAddr tcpip.Address, dialPort uint16) {
defer client.Close()
ns.logf("[v2] netstack: forwarding incoming connection on port %v", port)
dialAddrStr := net.JoinHostPort(dialAddr.String(), strconv.Itoa(int(dialPort)))
ns.logf("[v2] netstack: forwarding incoming connection to %s", dialAddrStr)
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
waitEntry, notifyCh := waiter.NewChannelEntry(nil)
@ -358,9 +434,9 @@ func (ns *Impl) forwardTCP(client *gonet.TCPConn, wq *waiter.Queue, port uint16)
cancel()
}()
var stdDialer net.Dialer
server, err := stdDialer.DialContext(ctx, "tcp", net.JoinHostPort("localhost", strconv.Itoa(int(port))))
server, err := stdDialer.DialContext(ctx, "tcp", dialAddrStr)
if err != nil {
ns.logf("netstack: could not connect to local server on port %v: %v", port, err)
ns.logf("netstack: could not connect to local server at %s: %v", dialAddrStr, err)
return
}
defer server.Close()
@ -382,7 +458,7 @@ func (ns *Impl) forwardTCP(client *gonet.TCPConn, wq *waiter.Queue, port uint16)
if err != nil {
ns.logf("proxy connection closed with error: %v", err)
}
ns.logf("[v2] netstack: forwarder connection on port %v closed", port)
ns.logf("[v2] netstack: forwarder connection to %s closed", dialAddrStr)
}
func (ns *Impl) acceptUDP(r *udp.ForwarderRequest) {

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