Validate MLD packets

Fixes #5490

PiperOrigin-RevId: 359401532

pkg/tcpip/network/ipv6/icmp.go

@@ -260,12 +260,31 @@ func getTargetLinkAddr(it header.NDPOptionIterator) (tcpip.LinkAddress, bool) {
 	})
 }
 
-func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool) {
+func isMLDValid(pkt *stack.PacketBuffer, iph header.IPv6, routerAlert *header.IPv6RouterAlertOption) bool {
+	// As per RFC 2710 section 3:
+	//   All MLD messages described in this document are sent with a link-local
+	//   IPv6 Source Address, an IPv6 Hop Limit of 1, and an IPv6 Router Alert
+	//   option in a Hop-by-Hop Options header.
+	if routerAlert == nil || routerAlert.Value != header.IPv6RouterAlertMLD {
+		return false
+	}
+	if pkt.Data.Size() < header.ICMPv6HeaderSize+header.MLDMinimumSize {
+		return false
+	}
+	if iph.HopLimit() != header.MLDHopLimit {
+		return false
+	}
+	if !header.IsV6LinkLocalAddress(iph.SourceAddress()) {
+		return false
+	}
+	return true
+}
+
+func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, routerAlert *header.IPv6RouterAlertOption) {
 	sent := e.stats.icmp.packetsSent
 	received := e.stats.icmp.packetsReceived
-	// TODO(gvisor.dev/issue/170): ICMP packets don't have their
-	// TransportHeader fields set. See icmp/protocol.go:protocol.Parse for a
-	// full explanation.
+	// TODO(gvisor.dev/issue/170): ICMP packets don't have their TransportHeader
+	// fields set. See icmp/protocol.go:protocol.Parse for a full explanation.
 	v, ok := pkt.Data.PullUp(header.ICMPv6HeaderSize)
 	if !ok {
 		received.invalid.Increment()
@@ -823,7 +842,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool) {
 			panic(fmt.Sprintf("unrecognized MLD message = %d", icmpType))
 		}
 
-		if pkt.Data.Size()-header.ICMPv6HeaderSize < header.MLDMinimumSize {
+		if !isMLDValid(pkt, iph, routerAlert) {
 			received.invalid.Increment()
 			return
 		}

pkg/tcpip/network/ipv6/icmp_test.go

@@ -48,6 +48,8 @@ const (
 
 	// Extra time to use when waiting for an async event to occur.
 	defaultAsyncPositiveEventTimeout = 30 * time.Second
+
+	arbitraryHopLimit = 42
 )
 
 var (
@@ -157,20 +159,29 @@ func (*testInterface) CheckLocalAddress(tcpip.NetworkProtocolNumber, tcpip.Addre
 	return false
 }
 
-func handleICMPInIPv6(ep stack.NetworkEndpoint, src, dst tcpip.Address, icmp header.ICMPv6) {
-	ip := buffer.NewView(header.IPv6MinimumSize)
+func handleICMPInIPv6(ep stack.NetworkEndpoint, src, dst tcpip.Address, icmp header.ICMPv6, hopLimit uint8, includeRouterAlert bool) {
+	var extensionHeaders header.IPv6ExtHdrSerializer
+	if includeRouterAlert {
+		extensionHeaders = header.IPv6ExtHdrSerializer{
+			header.IPv6SerializableHopByHopExtHdr{
+				&header.IPv6RouterAlertOption{Value: header.IPv6RouterAlertMLD},
+			},
+		}
+	}
+	ip := buffer.NewView(header.IPv6MinimumSize + extensionHeaders.Length())
 	header.IPv6(ip).Encode(&header.IPv6Fields{
 		PayloadLength:     uint16(len(icmp)),
 		TransportProtocol: header.ICMPv6ProtocolNumber,
-		HopLimit:          header.NDPHopLimit,
+		HopLimit:          hopLimit,
 		SrcAddr:           src,
 		DstAddr:           dst,
+		ExtensionHeaders:  extensionHeaders,
 	})
+
 	vv := ip.ToVectorisedView()
 	vv.AppendView(buffer.View(icmp))
 	ep.HandlePacket(stack.NewPacketBuffer(stack.PacketBufferOptions{
-		ReserveHeaderBytes: header.IPv6MinimumSize,
-		Data:               vv,
+		Data: vv,
 	}))
 }
 
@@ -223,66 +234,85 @@ func TestICMPCounts(t *testing.T) {
 	})
 
 	types := []struct {
-		typ       header.ICMPv6Type
-		size      int
-		extraData []byte
+		typ                header.ICMPv6Type
+		hopLimit           uint8
+		includeRouterAlert bool
+		size               int
+		extraData          []byte
 	}{
 		{
-			typ:  header.ICMPv6DstUnreachable,
-			size: header.ICMPv6DstUnreachableMinimumSize,
+			typ:      header.ICMPv6DstUnreachable,
+			hopLimit: arbitraryHopLimit,
+			size:     header.ICMPv6DstUnreachableMinimumSize,
 		},
 		{
-			typ:  header.ICMPv6PacketTooBig,
-			size: header.ICMPv6PacketTooBigMinimumSize,
+			typ:      header.ICMPv6PacketTooBig,
+			hopLimit: arbitraryHopLimit,
+			size:     header.ICMPv6PacketTooBigMinimumSize,
 		},
 		{
-			typ:  header.ICMPv6TimeExceeded,
-			size: header.ICMPv6MinimumSize,
+			typ:      header.ICMPv6TimeExceeded,
+			hopLimit: arbitraryHopLimit,
+			size:     header.ICMPv6MinimumSize,
 		},
 		{
-			typ:  header.ICMPv6ParamProblem,
-			size: header.ICMPv6MinimumSize,
+			typ:      header.ICMPv6ParamProblem,
+			hopLimit: arbitraryHopLimit,
+			size:     header.ICMPv6MinimumSize,
 		},
 		{
-			typ:  header.ICMPv6EchoRequest,
-			size: header.ICMPv6EchoMinimumSize,
+			typ:      header.ICMPv6EchoRequest,
+			hopLimit: arbitraryHopLimit,
+			size:     header.ICMPv6EchoMinimumSize,
 		},
 		{
-			typ:  header.ICMPv6EchoReply,
-			size: header.ICMPv6EchoMinimumSize,
+			typ:      header.ICMPv6EchoReply,
+			hopLimit: arbitraryHopLimit,
+			size:     header.ICMPv6EchoMinimumSize,
 		},
 		{
-			typ:  header.ICMPv6RouterSolicit,
-			size: header.ICMPv6MinimumSize,
+			typ:      header.ICMPv6RouterSolicit,
+			hopLimit: header.NDPHopLimit,
+			size:     header.ICMPv6MinimumSize,
 		},
 		{
-			typ:  header.ICMPv6RouterAdvert,
-			size: header.ICMPv6HeaderSize + header.NDPRAMinimumSize,
+			typ:      header.ICMPv6RouterAdvert,
+			hopLimit: header.NDPHopLimit,
+			size:     header.ICMPv6HeaderSize + header.NDPRAMinimumSize,
 		},
 		{
-			typ:  header.ICMPv6NeighborSolicit,
-			size: header.ICMPv6NeighborSolicitMinimumSize,
+			typ:      header.ICMPv6NeighborSolicit,
+			hopLimit: header.NDPHopLimit,
+			size:     header.ICMPv6NeighborSolicitMinimumSize,
 		},
 		{
 			typ:       header.ICMPv6NeighborAdvert,
+			hopLimit:  header.NDPHopLimit,
 			size:      header.ICMPv6NeighborAdvertMinimumSize,
 			extraData: tllData[:],
 		},
 		{
-			typ:  header.ICMPv6RedirectMsg,
-			size: header.ICMPv6MinimumSize,
+			typ:      header.ICMPv6RedirectMsg,
+			hopLimit: header.NDPHopLimit,
+			size:     header.ICMPv6MinimumSize,
 		},
 		{
-			typ:  header.ICMPv6MulticastListenerQuery,
-			size: header.MLDMinimumSize + header.ICMPv6HeaderSize,
+			typ:                header.ICMPv6MulticastListenerQuery,
+			hopLimit:           header.MLDHopLimit,
+			includeRouterAlert: true,
+			size:               header.MLDMinimumSize + header.ICMPv6HeaderSize,
 		},
 		{
-			typ:  header.ICMPv6MulticastListenerReport,
-			size: header.MLDMinimumSize + header.ICMPv6HeaderSize,
+			typ:                header.ICMPv6MulticastListenerReport,
+			hopLimit:           header.MLDHopLimit,
+			includeRouterAlert: true,
+			size:               header.MLDMinimumSize + header.ICMPv6HeaderSize,
 		},
 		{
-			typ:  header.ICMPv6MulticastListenerDone,
-			size: header.MLDMinimumSize + header.ICMPv6HeaderSize,
+			typ:                header.ICMPv6MulticastListenerDone,
+			hopLimit:           header.MLDHopLimit,
+			includeRouterAlert: true,
+			size:               header.MLDMinimumSize + header.ICMPv6HeaderSize,
 		},
 		{
 			typ:  255, /* Unrecognized */
@@ -295,12 +325,12 @@ func TestICMPCounts(t *testing.T) {
 		copy(icmp[typ.size:], typ.extraData)
 		icmp.SetType(typ.typ)
 		icmp.SetChecksum(header.ICMPv6Checksum(icmp[:typ.size], lladdr0, lladdr1, buffer.View(typ.extraData).ToVectorisedView()))
-		handleICMPInIPv6(ep, lladdr1, lladdr0, icmp)
+		handleICMPInIPv6(ep, lladdr1, lladdr0, icmp, typ.hopLimit, typ.includeRouterAlert)
 	}
 
 	// Construct an empty ICMP packet so that
 	// Stats().ICMP.ICMPv6ReceivedPacketStats.Invalid is incremented.
-	handleICMPInIPv6(ep, lladdr1, lladdr0, header.ICMPv6(buffer.NewView(header.IPv6MinimumSize)))
+	handleICMPInIPv6(ep, lladdr1, lladdr0, header.ICMPv6(buffer.NewView(header.IPv6MinimumSize)), arbitraryHopLimit, false)
 
 	icmpv6Stats := s.Stats().ICMP.V6.PacketsReceived
 	visitStats(reflect.ValueOf(&icmpv6Stats).Elem(), func(name string, s *tcpip.StatCounter) {
@@ -1632,7 +1662,7 @@ func TestCallsToNeighborCache(t *testing.T) {
 
 			icmp := test.createPacket()
 			icmp.SetChecksum(header.ICMPv6Checksum(icmp, test.source, test.destination, buffer.VectorisedView{}))
-			handleICMPInIPv6(ep, test.source, test.destination, icmp)
+			handleICMPInIPv6(ep, test.source, test.destination, icmp, header.NDPHopLimit, false)
 
 			// Confirm the endpoint calls the correct NUDHandler method.
 			if testInterface.probeCount != test.wantProbeCount {

pkg/tcpip/network/ipv6/ipv6.go

@@ -1001,7 +1001,6 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 	vv.AppendView(pkt.TransportHeader().View())
 	vv.Append(pkt.Data)
 	it := header.MakeIPv6PayloadIterator(header.IPv6ExtensionHeaderIdentifier(h.NextHeader()), vv)
-	hasFragmentHeader := false
 
 	// iptables filtering. All packets that reach here are intended for
 	// this machine and need not be forwarded.
@@ -1012,6 +1011,11 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 		return
 	}
 
+	var (
+		hasFragmentHeader bool
+		routerAlert       *header.IPv6RouterAlertOption
+	)
+
 	for {
 		// Keep track of the start of the previous header so we can report the
 		// special case of a Hop by Hop at a location other than at the start.
@@ -1049,34 +1053,46 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 					break
 				}
 
-				// We currently do not support any IPv6 Hop By Hop extension header
-				// options.
-				switch opt.UnknownAction() {
-				case header.IPv6OptionUnknownActionSkip:
-				case header.IPv6OptionUnknownActionDiscard:
-					return
-				case header.IPv6OptionUnknownActionDiscardSendICMPNoMulticastDest:
-					if header.IsV6MulticastAddress(dstAddr) {
+				switch opt := opt.(type) {
+				case *header.IPv6RouterAlertOption:
+					if routerAlert != nil {
+						// As per RFC 2711 section 3, there should be at most one Router
+						// Alert option per packet.
+						//
+						//    There MUST only be one option of this type, regardless of
+						//    value, per Hop-by-Hop header.
+						stats.MalformedPacketsReceived.Increment()
 						return
 					}
-					fallthrough
-				case header.IPv6OptionUnknownActionDiscardSendICMP:
-					// This case satisfies a requirement of RFC 8200 section 4.2
-					// which states that an unknown option starting with bits [10] should:
-					//
-					//    discard the packet and, regardless of whether or not the
-					//    packet's Destination Address was a multicast address, send an
-					//    ICMP Parameter Problem, Code 2, message to the packet's
-					//    Source Address, pointing to the unrecognized Option Type.
-					//
-					_ = e.protocol.returnError(&icmpReasonParameterProblem{
-						code:               header.ICMPv6UnknownOption,
-						pointer:            it.ParseOffset() + optsIt.OptionOffset(),
-						respondToMulticast: true,
-					}, pkt)
-					return
+					routerAlert = opt
+					stats.OptionRouterAlertReceived.Increment()
 				default:
-					panic(fmt.Sprintf("unrecognized action for an unrecognized Hop By Hop extension header option = %d", opt))
+					switch opt.UnknownAction() {
+					case header.IPv6OptionUnknownActionSkip:
+					case header.IPv6OptionUnknownActionDiscard:
+						return
+					case header.IPv6OptionUnknownActionDiscardSendICMPNoMulticastDest:
+						if header.IsV6MulticastAddress(dstAddr) {
+							return
+						}
+						fallthrough
+					case header.IPv6OptionUnknownActionDiscardSendICMP:
+						// This case satisfies a requirement of RFC 8200 section 4.2 which
+						// states that an unknown option starting with bits [10] should:
+						//
+						//    discard the packet and, regardless of whether or not the
+						//    packet's Destination Address was a multicast address, send an
+						//    ICMP Parameter Problem, Code 2, message to the packet's
+						//    Source Address, pointing to the unrecognized Option Type.
+						_ = e.protocol.returnError(&icmpReasonParameterProblem{
+							code:               header.ICMPv6UnknownOption,
+							pointer:            it.ParseOffset() + optsIt.OptionOffset(),
+							respondToMulticast: true,
+						}, pkt)
+						return
+					default:
+						panic(fmt.Sprintf("unrecognized action for an unrecognized Hop By Hop extension header option = %d", opt))
+					}
 				}
 			}
 
@@ -1303,7 +1319,7 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 			stats.PacketsDelivered.Increment()
 			if p := tcpip.TransportProtocolNumber(extHdr.Identifier); p == header.ICMPv6ProtocolNumber {
 				pkt.TransportProtocolNumber = p
-				e.handleICMP(pkt, hasFragmentHeader)
+				e.handleICMP(pkt, hasFragmentHeader, routerAlert)
 			} else {
 				stats.PacketsDelivered.Increment()
 				switch res := e.dispatcher.DeliverTransportPacket(p, pkt); res {

pkg/tcpip/network/ipv6/ipv6_test.go

@@ -382,9 +382,10 @@ func TestAddIpv6Address(t *testing.T) {
 
 func TestReceiveIPv6ExtHdrs(t *testing.T) {
 	tests := []struct {
-		name         string
-		extHdr       func(nextHdr uint8) ([]byte, uint8)
-		shouldAccept bool
+		name                    string
+		extHdr                  func(nextHdr uint8) ([]byte, uint8)
+		shouldAccept            bool
+		countersToBeIncremented func(*tcpip.Stats) []*tcpip.StatCounter
 		// Should we expect an ICMP response and if so, with what contents?
 		expectICMP bool
 		ICMPType   header.ICMPv6Type
@@ -398,6 +399,42 @@ func TestReceiveIPv6ExtHdrs(t *testing.T) {
 			shouldAccept: true,
 			expectICMP:   false,
 		},
+		{
+			name: "hopbyhop with router alert option",
+			extHdr: func(nextHdr uint8) ([]byte, uint8) {
+				return []byte{
+					nextHdr, 0,
+
+					// Router Alert option.
+					5, 2, 0, 0, 0, 0,
+				}, hopByHopExtHdrID
+			},
+			shouldAccept: true,
+			countersToBeIncremented: func(stats *tcpip.Stats) []*tcpip.StatCounter {
+				return []*tcpip.StatCounter{stats.IP.OptionRouterAlertReceived}
+			},
+		},
+		{
+			name: "hopbyhop with two router alert options",
+			extHdr: func(nextHdr uint8) ([]byte, uint8) {
+				return []byte{
+					nextHdr, 1,
+
+					// Router Alert option.
+					5, 2, 0, 0, 0, 0,
+
+					// Router Alert option.
+					5, 2, 0, 0, 0, 0, 0, 0,
+				}, hopByHopExtHdrID
+			},
+			shouldAccept: false,
+			countersToBeIncremented: func(stats *tcpip.Stats) []*tcpip.StatCounter {
+				return []*tcpip.StatCounter{
+					stats.IP.OptionRouterAlertReceived,
+					stats.IP.MalformedPacketsReceived,
+				}
+			},
+		},
 		{
 			name: "hopbyhop with unknown option skippable action",
 			extHdr: func(nextHdr uint8) ([]byte, uint8) {
@@ -924,14 +961,32 @@ func TestReceiveIPv6ExtHdrs(t *testing.T) {
 				DstAddr:           dstAddr,
 			})
 
+			stats := s.Stats()
+			var counters []*tcpip.StatCounter
+			// Make sure that the counters we expect to be incremented are initially
+			// set to zero.
+			if fn := test.countersToBeIncremented; fn != nil {
+				counters = fn(&stats)
+			}
+			for i := range counters {
+				if got := counters[i].Value(); got != 0 {
+					t.Errorf("before writing packet: got test.countersToBeIncremented(&stats)[%d].Value() = %d, want = 0", i, got)
+				}
+			}
+
 			e.InjectInbound(ProtocolNumber, stack.NewPacketBuffer(stack.PacketBufferOptions{
 				Data: hdr.View().ToVectorisedView(),
 			}))
 
-			stats := s.Stats().UDP.PacketsReceived
+			for i := range counters {
+				if got := counters[i].Value(); got != 1 {
+					t.Errorf("after writing packet: got test.countersToBeIncremented(&stats)[%d].Value() = %d, want = 1", i, got)
+				}
+			}
 
+			udpReceiveStat := stats.UDP.PacketsReceived
 			if !test.shouldAccept {
-				if got := stats.Value(); got != 0 {
+				if got := udpReceiveStat.Value(); got != 0 {
 					t.Errorf("got UDP Rx Packets = %d, want = 0", got)
 				}
 
@@ -977,7 +1032,7 @@ func TestReceiveIPv6ExtHdrs(t *testing.T) {
 			}
 
 			// Expect a UDP packet.
-			if got := stats.Value(); got != 1 {
+			if got := udpReceiveStat.Value(); got != 1 {
 				t.Errorf("got UDP Rx Packets = %d, want = 1", got)
 			}
 			var buf bytes.Buffer

pkg/tcpip/network/ipv6/mld_test.go

@@ -48,8 +48,7 @@ func validateMLDPacket(t *testing.T, p buffer.View, localAddress, remoteAddress
 		),
 		checker.SrcAddr(localAddress),
 		checker.DstAddr(remoteAddress),
-		// Hop Limit for an MLD message must be 1 as per RFC 2710 section 3.
-		checker.TTL(1),
+		checker.TTL(header.MLDHopLimit),
 		checker.MLD(mldType, header.MLDMinimumSize,
 			checker.MLDMaxRespDelay(0),
 			checker.MLDMulticastAddress(groupAddress),
@@ -195,7 +194,7 @@ func TestSendQueuedMLDReports(t *testing.T) {
 
 			// Adding a global address should not send reports for the already joined
 			// group since we should only send queued reports when a link-local
-			// addres sis assigned.
+			// address is assigned.
 			//
 			// Note, we will still expect to send a report for the global address's
 			// solicited node address from the unspecified address as per  RFC 3590
@@ -295,3 +294,153 @@ func TestSendQueuedMLDReports(t *testing.T) {
 		})
 	}
 }
+
+// createAndInjectMLDPacket creates and injects an MLD packet with the
+// specified fields.
+func createAndInjectMLDPacket(e *channel.Endpoint, mldType header.ICMPv6Type, hopLimit uint8, srcAddress tcpip.Address, withRouterAlertOption bool, routerAlertValue header.IPv6RouterAlertValue) {
+	var extensionHeaders header.IPv6ExtHdrSerializer
+	if withRouterAlertOption {
+		extensionHeaders = header.IPv6ExtHdrSerializer{
+			header.IPv6SerializableHopByHopExtHdr{
+				&header.IPv6RouterAlertOption{Value: routerAlertValue},
+			},
+		}
+	}
+
+	extensionHeadersLength := extensionHeaders.Length()
+	payloadLength := extensionHeadersLength + header.ICMPv6HeaderSize + header.MLDMinimumSize
+	buf := buffer.NewView(header.IPv6MinimumSize + payloadLength)
+
+	ip := header.IPv6(buf)
+	ip.Encode(&header.IPv6Fields{
+		PayloadLength:     uint16(payloadLength),
+		HopLimit:          hopLimit,
+		TransportProtocol: header.ICMPv6ProtocolNumber,
+		SrcAddr:           srcAddress,
+		DstAddr:           header.IPv6AllNodesMulticastAddress,
+		ExtensionHeaders:  extensionHeaders,
+	})
+
+	icmp := header.ICMPv6(ip.Payload()[extensionHeadersLength:])
+	icmp.SetType(mldType)
+	mld := header.MLD(icmp.MessageBody())
+	mld.SetMaximumResponseDelay(0)
+	mld.SetMulticastAddress(header.IPv6Any)
+	icmp.SetChecksum(header.ICMPv6Checksum(icmp, srcAddress, header.IPv6AllNodesMulticastAddress, buffer.VectorisedView{}))
+
+	e.InjectInbound(ipv6.ProtocolNumber, &stack.PacketBuffer{
+		Data: buf.ToVectorisedView(),
+	})
+}
+
+func TestMLDPacketValidation(t *testing.T) {
+	const (
+		nicID          = 1
+		linkLocalAddr2 = tcpip.Address("\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
+	)
+
+	tests := []struct {
+		name                     string
+		messageType              header.ICMPv6Type
+		srcAddr                  tcpip.Address
+		includeRouterAlertOption bool
+		routerAlertValue         header.IPv6RouterAlertValue
+		hopLimit                 uint8
+		expectValidMLD           bool
+		getMessageTypeStatValue  func(tcpip.Stats) uint64
+	}{
+		{
+			name:                     "valid",
+			messageType:              header.ICMPv6MulticastListenerQuery,
+			includeRouterAlertOption: true,
+			routerAlertValue:         header.IPv6RouterAlertMLD,
+			srcAddr:                  linkLocalAddr2,
+			hopLimit:                 header.MLDHopLimit,
+			expectValidMLD:           true,
+			getMessageTypeStatValue:  func(stats tcpip.Stats) uint64 { return stats.ICMP.V6.PacketsReceived.MulticastListenerQuery.Value() },
+		},
+		{
+			name:                     "bad hop limit",
+			messageType:              header.ICMPv6MulticastListenerReport,
+			includeRouterAlertOption: true,
+			routerAlertValue:         header.IPv6RouterAlertMLD,
+			srcAddr:                  linkLocalAddr2,
+			hopLimit:                 header.MLDHopLimit + 1,
+			expectValidMLD:           false,
+			getMessageTypeStatValue:  func(stats tcpip.Stats) uint64 { return stats.ICMP.V6.PacketsReceived.MulticastListenerReport.Value() },
+		},
+		{
+			name:                     "src ip not link local",
+			messageType:              header.ICMPv6MulticastListenerReport,
+			includeRouterAlertOption: true,
+			routerAlertValue:         header.IPv6RouterAlertMLD,
+			srcAddr:                  globalAddr,
+			hopLimit:                 header.MLDHopLimit,
+			expectValidMLD:           false,
+			getMessageTypeStatValue:  func(stats tcpip.Stats) uint64 { return stats.ICMP.V6.PacketsReceived.MulticastListenerReport.Value() },
+		},
+		{
+			name:                     "missing router alert ip option",
+			messageType:              header.ICMPv6MulticastListenerDone,
+			includeRouterAlertOption: false,
+			srcAddr:                  linkLocalAddr2,
+			hopLimit:                 header.MLDHopLimit,
+			expectValidMLD:           false,
+			getMessageTypeStatValue:  func(stats tcpip.Stats) uint64 { return stats.ICMP.V6.PacketsReceived.MulticastListenerDone.Value() },
+		},
+		{
+			name:                     "incorrect router alert value",
+			messageType:              header.ICMPv6MulticastListenerDone,
+			includeRouterAlertOption: true,
+			routerAlertValue:         header.IPv6RouterAlertRSVP,
+			srcAddr:                  linkLocalAddr2,
+			hopLimit:                 header.MLDHopLimit,
+			expectValidMLD:           false,
+			getMessageTypeStatValue:  func(stats tcpip.Stats) uint64 { return stats.ICMP.V6.PacketsReceived.MulticastListenerDone.Value() },
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			s := stack.New(stack.Options{
+				NetworkProtocols: []stack.NetworkProtocolFactory{ipv6.NewProtocolWithOptions(ipv6.Options{
+					MLD: ipv6.MLDOptions{
+						Enabled: true,
+					},
+				})},
+			})
+			e := channel.New(nicID, header.IPv6MinimumMTU, "")
+			if err := s.CreateNIC(nicID, e); err != nil {
+				t.Fatalf("CreateNIC(%d, _): %s", nicID, err)
+			}
+			stats := s.Stats()
+			// Verify that every relevant stats is zero'd before we send a packet.
+			if got := test.getMessageTypeStatValue(s.Stats()); got != 0 {
+				t.Errorf("got test.getMessageTypeStatValue(s.Stats()) = %d, want = 0", got)
+			}
+			if got := stats.ICMP.V6.PacketsReceived.Invalid.Value(); got != 0 {
+				t.Errorf("got stats.ICMP.V6.PacketsReceived.Invalid.Value() = %d, want = 0", got)
+			}
+			if got := stats.IP.PacketsDelivered.Value(); got != 0 {
+				t.Fatalf("got stats.IP.PacketsDelivered.Value() = %d, want = 0", got)
+			}
+			createAndInjectMLDPacket(e, test.messageType, test.hopLimit, test.srcAddr, test.includeRouterAlertOption, test.routerAlertValue)
+			// We always expect the packet to pass IP validation.
+			if got := stats.IP.PacketsDelivered.Value(); got != 1 {
+				t.Fatalf("got stats.IP.PacketsDelivered.Value() = %d, want = 1", got)
+			}
+			// Even when the MLD-specific validation checks fail, we expect the
+			// corresponding MLD counter to be incremented.
+			if got := test.getMessageTypeStatValue(s.Stats()); got != 1 {
+				t.Errorf("got test.getMessageTypeStatValue(s.Stats()) = %d, want = 1", got)
+			}
+			var expectedInvalidCount uint64
+			if !test.expectValidMLD {
+				expectedInvalidCount = 1
+			}
+			if got := stats.ICMP.V6.PacketsReceived.Invalid.Value(); got != expectedInvalidCount {
+				t.Errorf("got stats.ICMP.V6.PacketsReceived.Invalid.Value() = %d, want = %d", got, expectedInvalidCount)
+			}
+		})
+	}
+}

pkg/tcpip/network/multicast_group_test.go

@@ -37,7 +37,8 @@ const (
 
 	stackIPv4Addr           = tcpip.Address("\x0a\x00\x00\x01")
 	defaultIPv4PrefixLength = 24
-	ipv6Addr                = tcpip.Address("\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
+	linkLocalIPv6Addr1      = tcpip.Address("\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
+	linkLocalIPv6Addr2      = tcpip.Address("\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
 
 	ipv4MulticastAddr1 = tcpip.Address("\xe0\x00\x00\x03")
 	ipv4MulticastAddr2 = tcpip.Address("\xe0\x00\x00\x04")
@@ -69,7 +70,7 @@ var (
 		return uint8(ipv4.UnsolicitedReportIntervalMax / decisecond)
 	}()
 
-	ipv6AddrSNMC = header.SolicitedNodeAddr(ipv6Addr)
+	ipv6AddrSNMC = header.SolicitedNodeAddr(linkLocalIPv6Addr1)
 )
 
 // validateMLDPacket checks that a passed PacketInfo is an IPv6 MLD packet
@@ -82,7 +83,7 @@ func validateMLDPacket(t *testing.T, p channel.PacketInfo, remoteAddress tcpip.A
 		checker.IPv6ExtHdr(
 			checker.IPv6HopByHopExtensionHeader(checker.IPv6RouterAlert(header.IPv6RouterAlertMLD)),
 		),
-		checker.SrcAddr(ipv6Addr),
+		checker.SrcAddr(linkLocalIPv6Addr1),
 		checker.DstAddr(remoteAddress),
 		// Hop Limit for an MLD message must be 1 as per RFC 2710 section 3.
 		checker.TTL(1),
@@ -153,8 +154,8 @@ func createStackWithLinkEndpoint(t *testing.T, v4, mgpEnabled bool, e stack.Link
 	if err := s.AddAddressWithPrefix(nicID, ipv4.ProtocolNumber, addr); err != nil {
 		t.Fatalf("AddAddressWithPrefix(%d, %d, %s): %s", nicID, ipv4.ProtocolNumber, addr, err)
 	}
-	if err := s.AddAddress(nicID, ipv6.ProtocolNumber, ipv6Addr); err != nil {
-		t.Fatalf("AddAddress(%d, %d, %s): %s", nicID, ipv6.ProtocolNumber, ipv6Addr, err)
+	if err := s.AddAddress(nicID, ipv6.ProtocolNumber, linkLocalIPv6Addr1); err != nil {
+		t.Fatalf("AddAddress(%d, %d, %s): %s", nicID, ipv6.ProtocolNumber, linkLocalIPv6Addr1, err)
 	}
 
 	return s, clock
@@ -236,29 +237,33 @@ func createAndInjectIGMPPacket(e *channel.Endpoint, igmpType byte, maxRespTime b
 
 // createAndInjectMLDPacket creates and injects an MLD packet with the
 // specified fields.
-//
-// Note, the router alert option is not included in this packet.
-//
-// TODO(b/162198658): set the router alert option.
 func createAndInjectMLDPacket(e *channel.Endpoint, mldType uint8, maxRespDelay byte, groupAddress tcpip.Address) {
-	icmpSize := header.ICMPv6HeaderSize + header.MLDMinimumSize
-	buf := buffer.NewView(header.IPv6MinimumSize + icmpSize)
+	extensionHeaders := header.IPv6ExtHdrSerializer{
+		header.IPv6SerializableHopByHopExtHdr{
+			&header.IPv6RouterAlertOption{Value: header.IPv6RouterAlertMLD},
+		},
+	}
+
+	extensionHeadersLength := extensionHeaders.Length()
+	payloadLength := extensionHeadersLength + header.ICMPv6HeaderSize + header.MLDMinimumSize
+	buf := buffer.NewView(header.IPv6MinimumSize + payloadLength)
 
 	ip := header.IPv6(buf)
 	ip.Encode(&header.IPv6Fields{
-		PayloadLength:     uint16(icmpSize),
+		PayloadLength:     uint16(payloadLength),
 		HopLimit:          header.MLDHopLimit,
 		TransportProtocol: header.ICMPv6ProtocolNumber,
-		SrcAddr:           header.IPv4Any,
+		SrcAddr:           linkLocalIPv6Addr2,
 		DstAddr:           header.IPv6AllNodesMulticastAddress,
+		ExtensionHeaders:  extensionHeaders,
 	})
 
-	icmp := header.ICMPv6(buf[header.IPv6MinimumSize:])
+	icmp := header.ICMPv6(ip.Payload()[extensionHeadersLength:])
 	icmp.SetType(header.ICMPv6Type(mldType))
 	mld := header.MLD(icmp.MessageBody())
 	mld.SetMaximumResponseDelay(uint16(maxRespDelay))
 	mld.SetMulticastAddress(groupAddress)
-	icmp.SetChecksum(header.ICMPv6Checksum(icmp, header.IPv6Any, header.IPv6AllNodesMulticastAddress, buffer.VectorisedView{}))
+	icmp.SetChecksum(header.ICMPv6Checksum(icmp, linkLocalIPv6Addr2, header.IPv6AllNodesMulticastAddress, buffer.VectorisedView{}))
 
 	e.InjectInbound(ipv6.ProtocolNumber, &stack.PacketBuffer{
 		Data: buf.ToVectorisedView(),