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-rw-r--r--pkg/tcpip/transport/udp/protocol.go101
-rw-r--r--pkg/tcpip/transport/udp/udp_test.go156
2 files changed, 255 insertions, 2 deletions
diff --git a/pkg/tcpip/transport/udp/protocol.go b/pkg/tcpip/transport/udp/protocol.go
index f76e7fbe1..068d9a272 100644
--- a/pkg/tcpip/transport/udp/protocol.go
+++ b/pkg/tcpip/transport/udp/protocol.go
@@ -69,7 +69,106 @@ func (*protocol) ParsePorts(v buffer.View) (src, dst uint16, err *tcpip.Error) {
// HandleUnknownDestinationPacket handles packets targeted at this protocol but
// that don't match any existing endpoint.
-func (p *protocol) HandleUnknownDestinationPacket(*stack.Route, stack.TransportEndpointID, buffer.VectorisedView) bool {
+func (p *protocol) HandleUnknownDestinationPacket(r *stack.Route, id stack.TransportEndpointID, netHeader buffer.View, vv buffer.VectorisedView) bool {
+ // Get the header then trim it from the view.
+ hdr := header.UDP(vv.First())
+ if int(hdr.Length()) > vv.Size() {
+ // Malformed packet.
+ r.Stack().Stats().UDP.MalformedPacketsReceived.Increment()
+ return true
+ }
+ // TODO(b/129426613): only send an ICMP message if UDP checksum is valid.
+
+ // Only send ICMP error if the address is not a multicast/broadcast
+ // v4/v6 address or the source is not the unspecified address.
+ //
+ // See: point e) in https://tools.ietf.org/html/rfc4443#section-2.4
+ if id.LocalAddress == header.IPv4Broadcast || header.IsV4MulticastAddress(id.LocalAddress) || header.IsV6MulticastAddress(id.LocalAddress) || id.RemoteAddress == header.IPv6Any || id.RemoteAddress == header.IPv4Any {
+ return true
+ }
+
+ // As per RFC: 1122 Section 3.2.2.1 A host SHOULD generate Destination
+ // Unreachable messages with code:
+ //
+ // 2 (Protocol Unreachable), when the designated transport protocol
+ // is not supported; or
+ //
+ // 3 (Port Unreachable), when the designated transport protocol
+ // (e.g., UDP) is unable to demultiplex the datagram but has no
+ // protocol mechanism to inform the sender.
+ switch len(id.LocalAddress) {
+ case header.IPv4AddressSize:
+ if !r.Stack().AllowICMPMessage() {
+ r.Stack().Stats().ICMP.V4PacketsSent.RateLimited.Increment()
+ return true
+ }
+ // As per RFC 1812 Section 4.3.2.3
+ //
+ // ICMP datagram SHOULD contain as much of the original
+ // datagram as possible without the length of the ICMP
+ // datagram exceeding 576 bytes
+ //
+ // NOTE: The above RFC referenced is different from the original
+ // recommendation in RFC 1122 where it mentioned that at least 8
+ // bytes of the payload must be included. Today linux and other
+ // systems implement the] RFC1812 definition and not the original
+ // RFC 1122 requirement.
+ mtu := int(r.MTU())
+ if mtu > header.IPv4MinimumProcessableDatagramSize {
+ mtu = header.IPv4MinimumProcessableDatagramSize
+ }
+ headerLen := int(r.MaxHeaderLength()) + header.ICMPv4MinimumSize
+ available := int(mtu) - headerLen
+ payloadLen := len(netHeader) + vv.Size()
+ if payloadLen > available {
+ payloadLen = available
+ }
+
+ payload := buffer.NewVectorisedView(len(netHeader), []buffer.View{netHeader})
+ payload.Append(vv)
+ payload.CapLength(payloadLen)
+
+ hdr := buffer.NewPrependable(headerLen)
+ pkt := header.ICMPv4(hdr.Prepend(header.ICMPv4MinimumSize))
+ pkt.SetType(header.ICMPv4DstUnreachable)
+ pkt.SetCode(header.ICMPv4PortUnreachable)
+ pkt.SetChecksum(header.ICMPv4Checksum(pkt, payload))
+ r.WritePacket(nil /* gso */, hdr, payload, header.ICMPv4ProtocolNumber, r.DefaultTTL())
+
+ case header.IPv6AddressSize:
+ if !r.Stack().AllowICMPMessage() {
+ r.Stack().Stats().ICMP.V6PacketsSent.RateLimited.Increment()
+ return true
+ }
+
+ // As per RFC 4443 section 2.4
+ //
+ // (c) Every ICMPv6 error message (type < 128) MUST include
+ // as much of the IPv6 offending (invoking) packet (the
+ // packet that caused the error) as possible without making
+ // the error message packet exceed the minimum IPv6 MTU
+ // [IPv6].
+ mtu := int(r.MTU())
+ if mtu > header.IPv6MinimumMTU {
+ mtu = header.IPv6MinimumMTU
+ }
+ headerLen := int(r.MaxHeaderLength()) + header.ICMPv6DstUnreachableMinimumSize
+ available := int(mtu) - headerLen
+ payloadLen := len(netHeader) + vv.Size()
+ if payloadLen > available {
+ payloadLen = available
+ }
+ payload := buffer.NewVectorisedView(len(netHeader), []buffer.View{netHeader})
+ payload.Append(vv)
+ payload.CapLength(payloadLen)
+
+ hdr := buffer.NewPrependable(headerLen)
+ pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6DstUnreachableMinimumSize))
+ pkt.SetType(header.ICMPv6DstUnreachable)
+ pkt.SetCode(header.ICMPv6PortUnreachable)
+ pkt.SetChecksum(header.ICMPv6Checksum(pkt, r.LocalAddress, r.RemoteAddress, payload))
+ r.WritePacket(nil /* gso */, hdr, payload, header.ICMPv6ProtocolNumber, r.DefaultTTL())
+ }
return true
}
diff --git a/pkg/tcpip/transport/udp/udp_test.go b/pkg/tcpip/transport/udp/udp_test.go
index 9da6edce2..995d6e8a1 100644
--- a/pkg/tcpip/transport/udp/udp_test.go
+++ b/pkg/tcpip/transport/udp/udp_test.go
@@ -461,7 +461,11 @@ func (c *testContext) injectV4Packet(payload []byte, h *header4Tuple) {
}
func newPayload() []byte {
- b := make([]byte, 30+rand.Intn(100))
+ return newMinPayload(30)
+}
+
+func newMinPayload(minSize int) []byte {
+ b := make([]byte, minSize+rand.Intn(100))
for i := range b {
b[i] = byte(rand.Intn(256))
}
@@ -1238,3 +1242,153 @@ func TestMulticastInterfaceOption(t *testing.T) {
})
}
}
+
+// TestV4UnknownDestination verifies that we generate an ICMPv4 Destination
+// Unreachable message when a udp datagram is received on ports for which there
+// is no bound udp socket.
+func TestV4UnknownDestination(t *testing.T) {
+ c := newDualTestContext(t, defaultMTU)
+ defer c.cleanup()
+
+ testCases := []struct {
+ flow testFlow
+ icmpRequired bool
+ // largePayload if true, will result in a payload large enough
+ // so that the final generated IPv4 packet is larger than
+ // header.IPv4MinimumProcessableDatagramSize.
+ largePayload bool
+ }{
+ {unicastV4, true, false},
+ {unicastV4, true, true},
+ {multicastV4, false, false},
+ {multicastV4, false, true},
+ {broadcast, false, false},
+ {broadcast, false, true},
+ }
+ for _, tc := range testCases {
+ t.Run(fmt.Sprintf("flow:%s icmpRequired:%t largePayload:%t", tc.flow, tc.icmpRequired, tc.largePayload), func(t *testing.T) {
+ payload := newPayload()
+ if tc.largePayload {
+ payload = newMinPayload(576)
+ }
+ c.injectPacket(tc.flow, payload)
+ if !tc.icmpRequired {
+ select {
+ case p := <-c.linkEP.C:
+ t.Fatalf("unexpected packet received: %+v", p)
+ case <-time.After(1 * time.Second):
+ return
+ }
+ }
+
+ select {
+ case p := <-c.linkEP.C:
+ var pkt []byte
+ pkt = append(pkt, p.Header...)
+ pkt = append(pkt, p.Payload...)
+ if got, want := len(pkt), header.IPv4MinimumProcessableDatagramSize; got > want {
+ t.Fatalf("got an ICMP packet of size: %d, want: sz <= %d", got, want)
+ }
+
+ hdr := header.IPv4(pkt)
+ checker.IPv4(t, hdr, checker.ICMPv4(
+ checker.ICMPv4Type(header.ICMPv4DstUnreachable),
+ checker.ICMPv4Code(header.ICMPv4PortUnreachable)))
+
+ icmpPkt := header.ICMPv4(hdr.Payload())
+ payloadIPHeader := header.IPv4(icmpPkt.Payload())
+ wantLen := len(payload)
+ if tc.largePayload {
+ wantLen = header.IPv4MinimumProcessableDatagramSize - header.IPv4MinimumSize*2 - header.ICMPv4MinimumSize - header.UDPMinimumSize
+ }
+
+ // In case of large payloads the IP packet may be truncated. Update
+ // the length field before retrieving the udp datagram payload.
+ payloadIPHeader.SetTotalLength(uint16(wantLen + header.UDPMinimumSize + header.IPv4MinimumSize))
+
+ origDgram := header.UDP(payloadIPHeader.Payload())
+ if got, want := len(origDgram.Payload()), wantLen; got != want {
+ t.Fatalf("unexpected payload length got: %d, want: %d", got, want)
+ }
+ if got, want := origDgram.Payload(), payload[:wantLen]; !bytes.Equal(got, want) {
+ t.Fatalf("unexpected payload got: %d, want: %d", got, want)
+ }
+ case <-time.After(1 * time.Second):
+ t.Fatalf("packet wasn't written out")
+ }
+ })
+ }
+}
+
+// TestV6UnknownDestination verifies that we generate an ICMPv6 Destination
+// Unreachable message when a udp datagram is received on ports for which there
+// is no bound udp socket.
+func TestV6UnknownDestination(t *testing.T) {
+ c := newDualTestContext(t, defaultMTU)
+ defer c.cleanup()
+
+ testCases := []struct {
+ flow testFlow
+ icmpRequired bool
+ // largePayload if true will result in a payload large enough to
+ // create an IPv6 packet > header.IPv6MinimumMTU bytes.
+ largePayload bool
+ }{
+ {unicastV6, true, false},
+ {unicastV6, true, true},
+ {multicastV6, false, false},
+ {multicastV6, false, true},
+ }
+ for _, tc := range testCases {
+ t.Run(fmt.Sprintf("flow:%s icmpRequired:%t largePayload:%t", tc.flow, tc.icmpRequired, tc.largePayload), func(t *testing.T) {
+ payload := newPayload()
+ if tc.largePayload {
+ payload = newMinPayload(1280)
+ }
+ c.injectPacket(tc.flow, payload)
+ if !tc.icmpRequired {
+ select {
+ case p := <-c.linkEP.C:
+ t.Fatalf("unexpected packet received: %+v", p)
+ case <-time.After(1 * time.Second):
+ return
+ }
+ }
+
+ select {
+ case p := <-c.linkEP.C:
+ var pkt []byte
+ pkt = append(pkt, p.Header...)
+ pkt = append(pkt, p.Payload...)
+ if got, want := len(pkt), header.IPv6MinimumMTU; got > want {
+ t.Fatalf("got an ICMP packet of size: %d, want: sz <= %d", got, want)
+ }
+
+ hdr := header.IPv6(pkt)
+ checker.IPv6(t, hdr, checker.ICMPv6(
+ checker.ICMPv6Type(header.ICMPv6DstUnreachable),
+ checker.ICMPv6Code(header.ICMPv6PortUnreachable)))
+
+ icmpPkt := header.ICMPv6(hdr.Payload())
+ payloadIPHeader := header.IPv6(icmpPkt.Payload())
+ wantLen := len(payload)
+ if tc.largePayload {
+ wantLen = header.IPv6MinimumMTU - header.IPv6MinimumSize*2 - header.ICMPv6MinimumSize - header.UDPMinimumSize
+ }
+ // In case of large payloads the IP packet may be truncated. Update
+ // the length field before retrieving the udp datagram payload.
+ payloadIPHeader.SetPayloadLength(uint16(wantLen + header.UDPMinimumSize))
+
+ origDgram := header.UDP(payloadIPHeader.Payload())
+ if got, want := len(origDgram.Payload()), wantLen; got != want {
+ t.Fatalf("unexpected payload length got: %d, want: %d", got, want)
+ }
+ if got, want := origDgram.Payload(), payload[:wantLen]; !bytes.Equal(got, want) {
+ t.Fatalf("unexpected payload got: %v, want: %v", got, want)
+ }
+ case <-time.After(1 * time.Second):
+ t.Fatalf("packet wasn't written out")
+ }
+ })
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-11 10:26:13 +0000