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netstack: let ICMP echo handlers consume requests #13189

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19 changes: 13 additions & 6 deletions pkg/tcpip/network/ipv4/icmp.go
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Original file line number Diff line number Diff line change
Expand Up @@ -360,14 +360,21 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer) {
localAddressTemporary := pkt.NetworkPacketInfo.LocalAddressTemporary
localAddressBroadcast := pkt.NetworkPacketInfo.LocalAddressBroadcast

// It's possible that a raw socket or custom defaultHandler expects to
// receive this packet.
e.dispatcher.DeliverTransportPacket(header.ICMPv4ProtocolNumber, pkt)
// It's possible that a raw socket or per-stack default handler expects
// to receive this packet.
defaultHandlerHandled := false
if dispatcher, ok := e.dispatcher.(stack.TransportDispatcherWithDefaultHandlerResult); ok {
_, defaultHandlerHandled = dispatcher.DeliverTransportPacketWithDefaultHandlerResult(header.ICMPv4ProtocolNumber, pkt)
} else {
e.dispatcher.DeliverTransportPacket(header.ICMPv4ProtocolNumber, pkt)
}
pkt = nil

// Skip direct ICMP echo reply if the packet was received with a temporary
// address, allowing custom handlers to take over.
if localAddressTemporary {
// Skip the built-in ICMP echo reply if the request was consumed by a
// per-stack default handler. Also preserve the IPv4 behavior for
// temporary local addresses: the packet is delivered above, but the
// stack does not synthesize an echo reply for it.
if defaultHandlerHandled || localAddressTemporary {
return
}

Expand Down
313 changes: 313 additions & 0 deletions pkg/tcpip/network/ipv4/ipv4_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3886,6 +3886,319 @@ func TestCloseLocking(t *testing.T) {
}()
}

func TestICMPEchoDefaultHandlerControlsReply(t *testing.T) {
var (
localAddr = tcpip.ProtocolAddress{
Protocol: ipv4.ProtocolNumber,
AddressWithPrefix: tcpip.AddressWithPrefix{
Address: tcpip.AddrFromSlice(net.ParseIP("192.168.0.1").To4()),
PrefixLen: 24,
},
}
remoteAddr = tcpip.ProtocolAddress{
Protocol: ipv4.ProtocolNumber,
AddressWithPrefix: tcpip.AddressWithPrefix{
Address: tcpip.AddrFromSlice(net.ParseIP("192.168.0.2").To4()),
PrefixLen: 24,
},
}
)

tests := []struct {
name string
installHandler bool
handled bool
wantHandlerCalled bool
wantReply bool
}{
{
name: "no default handler",
wantReply: true,
},
{
name: "default handler handled",
installHandler: true,
handled: true,
wantHandlerCalled: true,
wantReply: false,
},
{
name: "default handler not handled",
installHandler: true,
handled: false,
wantHandlerCalled: true,
wantReply: true,
},
}

for _, test := range tests {
t.Run(test.name, func(t *testing.T) {
clock := faketime.NewManualClock()
s := stack.New(stack.Options{
NetworkProtocols: []stack.NetworkProtocolFactory{arp.NewProtocol, ipv4.NewProtocol},
TransportProtocols: []stack.TransportProtocolFactory{icmp.NewProtocol4},
Clock: clock,
})
defer func() {
s.Close()
s.Wait()
refs.DoRepeatedLeakCheck()
}()

const ident = 1234
handlerCalled := false
if test.installHandler {
s.SetTransportProtocolHandler(icmp.ProtocolNumber4, func(id stack.TransportEndpointID, pkt *stack.PacketBuffer) bool {
handlerCalled = true
if got := id.LocalPort; got != ident {
t.Errorf("got id.LocalPort = %d, want = %d", got, ident)
}
return test.handled
})
}

e := channel.New(1, defaultMTU, "")
defer e.Close()
if err := s.CreateNIC(nicID, e); err != nil {
t.Fatalf("s.CreateNIC(%d, _): %s", nicID, err)
}
if err := s.AddProtocolAddress(nicID, localAddr, stack.AddressProperties{}); err != nil {
t.Fatalf("s.AddProtocolAddress(%d, %+v, {}): %s", nicID, localAddr, err)
}
s.SetRouteTable([]tcpip.Route{{
Destination: localAddr.AddressWithPrefix.Subnet(),
NIC: nicID,
}})

totalLength := header.IPv4MinimumSize + header.ICMPv4MinimumSize
hdr := prependable.New(totalLength)
icmpH := header.ICMPv4(hdr.Prepend(header.ICMPv4MinimumSize))
icmpH.SetIdent(ident)
icmpH.SetType(header.ICMPv4Echo)
icmpH.SetCode(header.ICMPv4UnusedCode)
icmpH.SetChecksum(0)
icmpH.SetChecksum(^checksum.Checksum(icmpH, 0))
ip := header.IPv4(hdr.Prepend(header.IPv4MinimumSize))
ip.Encode(&header.IPv4Fields{
TotalLength: uint16(totalLength),
Protocol: uint8(icmp.ProtocolNumber4),
TTL: ipv4.DefaultTTL,
SrcAddr: remoteAddr.AddressWithPrefix.Address,
DstAddr: localAddr.AddressWithPrefix.Address,
})
ip.SetChecksum(^ip.CalculateChecksum())
echoPkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
Payload: buffer.MakeWithData(hdr.View()),
})
e.InjectInbound(header.IPv4ProtocolNumber, echoPkt)
echoPkt.DecRef()
clock.RunImmediatelyScheduledJobs()

if got, want := handlerCalled, test.wantHandlerCalled; got != want {
t.Fatalf("got handlerCalled = %t, want = %t", got, want)
}

p := e.Read()
if !test.wantReply {
if p != nil {
p.DecRef()
t.Fatalf("got unexpected ICMP echo reply")
}
return
}
if p == nil {
t.Fatalf("expected ICMP echo reply")
}
defer p.DecRef()
payload := stack.PayloadSince(p.NetworkHeader())
defer payload.Release()
checker.IPv4(t, payload,
checker.SrcAddr(localAddr.AddressWithPrefix.Address),
checker.DstAddr(remoteAddr.AddressWithPrefix.Address),
checker.ICMPv4(
checker.ICMPv4Type(header.ICMPv4EchoReply),
checker.ICMPv4Code(header.ICMPv4UnusedCode)))
})
}
}

func TestICMPEchoRegisteredEndpointDoesNotSuppressReply(t *testing.T) {
localAddr := tcpip.ProtocolAddress{
Protocol: ipv4.ProtocolNumber,
AddressWithPrefix: tcpip.AddressWithPrefix{
Address: tcpip.AddrFromSlice(net.ParseIP("192.168.0.1").To4()),
PrefixLen: 24,
},
}
remoteAddr := tcpip.ProtocolAddress{
Protocol: ipv4.ProtocolNumber,
AddressWithPrefix: tcpip.AddressWithPrefix{
Address: tcpip.AddrFromSlice(net.ParseIP("192.168.0.2").To4()),
PrefixLen: 24,
},
}

clock := faketime.NewManualClock()
s := stack.New(stack.Options{
NetworkProtocols: []stack.NetworkProtocolFactory{arp.NewProtocol, ipv4.NewProtocol},
TransportProtocols: []stack.TransportProtocolFactory{icmp.NewProtocol4},
Clock: clock,
})
defer func() {
s.Close()
s.Wait()
refs.DoRepeatedLeakCheck()
}()

e := channel.New(1, defaultMTU, "")
defer e.Close()
if err := s.CreateNIC(nicID, e); err != nil {
t.Fatalf("s.CreateNIC(%d, _): %s", nicID, err)
}
if err := s.AddProtocolAddress(nicID, localAddr, stack.AddressProperties{}); err != nil {
t.Fatalf("s.AddProtocolAddress(%d, %+v, {}): %s", nicID, localAddr, err)
}
s.SetRouteTable([]tcpip.Route{{
Destination: localAddr.AddressWithPrefix.Subnet(),
NIC: nicID,
}})

const ident = 1234
var wq waiter.Queue
ep, err := s.NewEndpoint(icmp.ProtocolNumber4, ipv4.ProtocolNumber, &wq)
if err != nil {
t.Fatalf("s.NewEndpoint(%d, %d, _) = %s", icmp.ProtocolNumber4, ipv4.ProtocolNumber, err)
}
defer ep.Close()
if err := ep.Bind(tcpip.FullAddress{Addr: localAddr.AddressWithPrefix.Address, Port: ident}); err != nil {
t.Fatalf("ep.Bind(...) = %s", err)
}

handlerCalled := false
s.SetTransportProtocolHandler(icmp.ProtocolNumber4, func(stack.TransportEndpointID, *stack.PacketBuffer) bool {
handlerCalled = true
return true
})

totalLength := header.IPv4MinimumSize + header.ICMPv4MinimumSize
hdr := prependable.New(totalLength)
icmpH := header.ICMPv4(hdr.Prepend(header.ICMPv4MinimumSize))
icmpH.SetIdent(ident)
icmpH.SetType(header.ICMPv4Echo)
icmpH.SetCode(header.ICMPv4UnusedCode)
icmpH.SetChecksum(0)
icmpH.SetChecksum(^checksum.Checksum(icmpH, 0))
ip := header.IPv4(hdr.Prepend(header.IPv4MinimumSize))
ip.Encode(&header.IPv4Fields{
TotalLength: uint16(totalLength),
Protocol: uint8(icmp.ProtocolNumber4),
TTL: ipv4.DefaultTTL,
SrcAddr: remoteAddr.AddressWithPrefix.Address,
DstAddr: localAddr.AddressWithPrefix.Address,
})
ip.SetChecksum(^ip.CalculateChecksum())
echoPkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
Payload: buffer.MakeWithData(hdr.View()),
})
e.InjectInbound(header.IPv4ProtocolNumber, echoPkt)
echoPkt.DecRef()
clock.RunImmediatelyScheduledJobs()

if handlerCalled {
t.Fatalf("default handler was unexpectedly called")
}

p := e.Read()
if p == nil {
t.Fatalf("expected ICMP echo reply")
}
defer p.DecRef()
payload := stack.PayloadSince(p.NetworkHeader())
defer payload.Release()
checker.IPv4(t, payload,
checker.SrcAddr(localAddr.AddressWithPrefix.Address),
checker.DstAddr(remoteAddr.AddressWithPrefix.Address),
checker.ICMPv4(
checker.ICMPv4Type(header.ICMPv4EchoReply),
checker.ICMPv4Code(header.ICMPv4UnusedCode)))
}

func TestICMPEchoTemporaryAddressSuppressesReply(t *testing.T) {
assignedAddr := tcpip.ProtocolAddress{
Protocol: ipv4.ProtocolNumber,
AddressWithPrefix: tcpip.AddressWithPrefix{
Address: tcpip.AddrFromSlice(net.ParseIP("192.168.0.1").To4()),
PrefixLen: 24,
},
}
temporaryAddr := tcpip.AddrFromSlice(net.ParseIP("192.168.0.99").To4())
remoteAddr := tcpip.ProtocolAddress{
Protocol: ipv4.ProtocolNumber,
AddressWithPrefix: tcpip.AddressWithPrefix{
Address: tcpip.AddrFromSlice(net.ParseIP("192.168.0.2").To4()),
PrefixLen: 24,
},
}

clock := faketime.NewManualClock()
s := stack.New(stack.Options{
NetworkProtocols: []stack.NetworkProtocolFactory{arp.NewProtocol, ipv4.NewProtocol},
TransportProtocols: []stack.TransportProtocolFactory{icmp.NewProtocol4},
Clock: clock,
})
defer func() {
s.Close()
s.Wait()
refs.DoRepeatedLeakCheck()
}()

e := channel.New(1, defaultMTU, "")
defer e.Close()
if err := s.CreateNIC(nicID, e); err != nil {
t.Fatalf("s.CreateNIC(%d, _): %s", nicID, err)
}
if err := s.AddProtocolAddress(nicID, assignedAddr, stack.AddressProperties{}); err != nil {
t.Fatalf("s.AddProtocolAddress(%d, %+v, {}): %s", nicID, assignedAddr, err)
}
if err := s.SetPromiscuousMode(nicID, true); err != nil {
t.Fatalf("s.SetPromiscuousMode(%d, true): %s", nicID, err)
}
s.SetRouteTable([]tcpip.Route{{
Destination: assignedAddr.AddressWithPrefix.Subnet(),
NIC: nicID,
}})

const ident = 1234
totalLength := header.IPv4MinimumSize + header.ICMPv4MinimumSize
hdr := prependable.New(totalLength)
icmpH := header.ICMPv4(hdr.Prepend(header.ICMPv4MinimumSize))
icmpH.SetIdent(ident)
icmpH.SetType(header.ICMPv4Echo)
icmpH.SetCode(header.ICMPv4UnusedCode)
icmpH.SetChecksum(0)
icmpH.SetChecksum(^checksum.Checksum(icmpH, 0))
ip := header.IPv4(hdr.Prepend(header.IPv4MinimumSize))
ip.Encode(&header.IPv4Fields{
TotalLength: uint16(totalLength),
Protocol: uint8(icmp.ProtocolNumber4),
TTL: ipv4.DefaultTTL,
SrcAddr: remoteAddr.AddressWithPrefix.Address,
DstAddr: temporaryAddr,
})
ip.SetChecksum(^ip.CalculateChecksum())
echoPkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
Payload: buffer.MakeWithData(hdr.View()),
})
e.InjectInbound(header.IPv4ProtocolNumber, echoPkt)
echoPkt.DecRef()
clock.RunImmediatelyScheduledJobs()

if p := e.Read(); p != nil {
p.DecRef()
t.Fatalf("got unexpected ICMP echo reply")
}
}

func TestIcmpRateLimit(t *testing.T) {
var (
host1IPv4Addr = tcpip.ProtocolAddress{
Expand Down
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