Only carry GSO options in the packet buffer

With this change, GSO options no longer needs to be passed around as
a function argument in the write path.

This change is done in preparation for a later change that defers
segmentation, and may change GSO options for a packet as it flows
down the stack.

Updates #170.

PiperOrigin-RevId: 369774872

6 files changed, 38 insertions, 56 deletions

diff --git a/pkg/tcpip/network/ipv6/icmp.go b/pkg/tcpip/network/ipv6/icmp.go
index b2a80e1e9..1319db32b 100644
--- a/pkg/tcpip/network/ipv6/icmp.go
+++ b/pkg/tcpip/network/ipv6/icmp.go
@@ -564,7 +564,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 		//
 		// The IP Hop Limit field has a value of 255, i.e., the packet
 		// could not possibly have been forwarded by a router.
-		if err := r.WritePacket(nil /* gso */, stack.NetworkHeaderParams{Protocol: header.ICMPv6ProtocolNumber, TTL: header.NDPHopLimit, TOS: stack.DefaultTOS}, pkt); err != nil {
+		if err := r.WritePacket(stack.NetworkHeaderParams{Protocol: header.ICMPv6ProtocolNumber, TTL: header.NDPHopLimit, TOS: stack.DefaultTOS}, pkt); err != nil {
 			sent.dropped.Increment()
 			return
 		}
@@ -704,7 +704,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 			PayloadCsum: dataRange.Checksum(),
 			PayloadLen:  dataRange.Size(),
 		}))
-		if err := r.WritePacket(nil /* gso */, stack.NetworkHeaderParams{
+		if err := r.WritePacket(stack.NetworkHeaderParams{
 			Protocol: header.ICMPv6ProtocolNumber,
 			TTL:      r.DefaultTTL(),
 			TOS:      stack.DefaultTOS,
@@ -1167,7 +1167,6 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) tcpip
 		PayloadLen:  dataRange.Size(),
 	}))
 	if err := route.WritePacket(
-		nil, /* gso */
 		stack.NetworkHeaderParams{
 			Protocol: header.ICMPv6ProtocolNumber,
 			TTL:      route.DefaultTTL(),
diff --git a/pkg/tcpip/network/ipv6/icmp_test.go b/pkg/tcpip/network/ipv6/icmp_test.go
index 6a7705ed1..e457be3cf 100644
--- a/pkg/tcpip/network/ipv6/icmp_test.go
+++ b/pkg/tcpip/network/ipv6/icmp_test.go
@@ -81,7 +81,7 @@ func (*stubLinkEndpoint) LinkAddress() tcpip.LinkAddress {
 	return ""
 }
 
-func (*stubLinkEndpoint) WritePacket(stack.RouteInfo, *stack.GSO, tcpip.NetworkProtocolNumber, *stack.PacketBuffer) tcpip.Error {
+func (*stubLinkEndpoint) WritePacket(stack.RouteInfo, tcpip.NetworkProtocolNumber, *stack.PacketBuffer) tcpip.Error {
 	return nil
 }
 
@@ -130,19 +130,19 @@ func (*testInterface) Spoofing() bool {
 	return false
 }
 
-func (t *testInterface) WritePacket(r *stack.Route, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) tcpip.Error {
-	return t.LinkEndpoint.WritePacket(r.Fields(), gso, protocol, pkt)
+func (t *testInterface) WritePacket(r *stack.Route, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) tcpip.Error {
+	return t.LinkEndpoint.WritePacket(r.Fields(), protocol, pkt)
 }
 
-func (t *testInterface) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.PacketBufferList, protocol tcpip.NetworkProtocolNumber) (int, tcpip.Error) {
-	return t.LinkEndpoint.WritePackets(r.Fields(), gso, pkts, protocol)
+func (t *testInterface) WritePackets(r *stack.Route, pkts stack.PacketBufferList, protocol tcpip.NetworkProtocolNumber) (int, tcpip.Error) {
+	return t.LinkEndpoint.WritePackets(r.Fields(), pkts, protocol)
 }
 
-func (t *testInterface) WritePacketToRemote(remoteLinkAddr tcpip.LinkAddress, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) tcpip.Error {
+func (t *testInterface) WritePacketToRemote(remoteLinkAddr tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) tcpip.Error {
 	var r stack.RouteInfo
 	r.NetProto = protocol
 	r.RemoteLinkAddress = remoteLinkAddr
-	return t.LinkEndpoint.WritePacket(r, gso, protocol, pkt)
+	return t.LinkEndpoint.WritePacket(r, protocol, pkt)
 }
 
 func (t *testInterface) HandleNeighborProbe(tcpip.NetworkProtocolNumber, tcpip.Address, tcpip.LinkAddress) tcpip.Error {
diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go
index 2e515379c..f7510c243 100644
--- a/pkg/tcpip/network/ipv6/ipv6.go
+++ b/pkg/tcpip/network/ipv6/ipv6.go
@@ -675,9 +675,9 @@ func addIPHeader(srcAddr, dstAddr tcpip.Address, pkt *stack.PacketBuffer, params
 	return nil
 }
 
-func packetMustBeFragmented(pkt *stack.PacketBuffer, networkMTU uint32, gso *stack.GSO) bool {
+func packetMustBeFragmented(pkt *stack.PacketBuffer, networkMTU uint32) bool {
 	payload := pkt.TransportHeader().View().Size() + pkt.Data().Size()
-	return (gso == nil || gso.Type == stack.GSONone) && uint32(payload) > networkMTU
+	return pkt.GSOOptions.Type == stack.GSONone && uint32(payload) > networkMTU
 }
 
 // handleFragments fragments pkt and calls the handler function on each
@@ -685,7 +685,7 @@ func packetMustBeFragmented(pkt *stack.PacketBuffer, networkMTU uint32, gso *sta
 // fragments left to be processed. The IP header must already be present in the
 // original packet. The transport header protocol number is required to avoid
 // parsing the IPv6 extension headers.
-func (e *endpoint) handleFragments(r *stack.Route, gso *stack.GSO, networkMTU uint32, pkt *stack.PacketBuffer, transProto tcpip.TransportProtocolNumber, handler func(*stack.PacketBuffer) tcpip.Error) (int, int, tcpip.Error) {
+func (e *endpoint) handleFragments(r *stack.Route, networkMTU uint32, pkt *stack.PacketBuffer, transProto tcpip.TransportProtocolNumber, handler func(*stack.PacketBuffer) tcpip.Error) (int, int, tcpip.Error) {
 	networkHeader := header.IPv6(pkt.NetworkHeader().View())
 
 	// TODO(gvisor.dev/issue/3912): Once the Authentication or ESP Headers are
@@ -724,7 +724,7 @@ func (e *endpoint) handleFragments(r *stack.Route, gso *stack.GSO, networkMTU ui
 }
 
 // WritePacket writes a packet to the given destination address and protocol.
-func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.NetworkHeaderParams, pkt *stack.PacketBuffer) tcpip.Error {
+func (e *endpoint) WritePacket(r *stack.Route, params stack.NetworkHeaderParams, pkt *stack.PacketBuffer) tcpip.Error {
 	if err := addIPHeader(r.LocalAddress(), r.RemoteAddress(), pkt, params, nil /* extensionHeaders */); err != nil {
 		return err
 	}
@@ -732,7 +732,7 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
 	// iptables filtering. All packets that reach here are locally
 	// generated.
 	outNicName := e.protocol.stack.FindNICNameFromID(e.nic.ID())
-	if ok := e.protocol.stack.IPTables().Check(stack.Output, pkt, gso, r, "" /* preroutingAddr */, "" /* inNicName */, outNicName); !ok {
+	if ok := e.protocol.stack.IPTables().Check(stack.Output, pkt, r, "" /* preroutingAddr */, "" /* inNicName */, outNicName); !ok {
 		// iptables is telling us to drop the packet.
 		e.stats.ip.IPTablesOutputDropped.Increment()
 		return nil
@@ -755,10 +755,10 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
 		}
 	}
 
-	return e.writePacket(r, gso, pkt, params.Protocol, false /* headerIncluded */)
+	return e.writePacket(r, pkt, params.Protocol, false /* headerIncluded */)
 }
 
-func (e *endpoint) writePacket(r *stack.Route, gso *stack.GSO, pkt *stack.PacketBuffer, protocol tcpip.TransportProtocolNumber, headerIncluded bool) tcpip.Error {
+func (e *endpoint) writePacket(r *stack.Route, pkt *stack.PacketBuffer, protocol tcpip.TransportProtocolNumber, headerIncluded bool) tcpip.Error {
 	if r.Loop()&stack.PacketLoop != 0 {
 		// If the packet was generated by the stack (not a raw/packet endpoint
 		// where a packet may be written with the header included), then we can
@@ -772,7 +772,7 @@ func (e *endpoint) writePacket(r *stack.Route, gso *stack.GSO, pkt *stack.Packet
 	// Postrouting NAT can only change the source address, and does not alter the
 	// route or outgoing interface of the packet.
 	outNicName := e.protocol.stack.FindNICNameFromID(e.nic.ID())
-	if ok := e.protocol.stack.IPTables().Check(stack.Postrouting, pkt, gso, r, "" /* preroutingAddr */, "" /* inNicName */, outNicName); !ok {
+	if ok := e.protocol.stack.IPTables().Check(stack.Postrouting, pkt, r, "" /* preroutingAddr */, "" /* inNicName */, outNicName); !ok {
 		// iptables is telling us to drop the packet.
 		e.stats.ip.IPTablesPostroutingDropped.Increment()
 		return nil
@@ -785,20 +785,20 @@ func (e *endpoint) writePacket(r *stack.Route, gso *stack.GSO, pkt *stack.Packet
 		return err
 	}
 
-	if packetMustBeFragmented(pkt, networkMTU, gso) {
-		sent, remain, err := e.handleFragments(r, gso, networkMTU, pkt, protocol, func(fragPkt *stack.PacketBuffer) tcpip.Error {
+	if packetMustBeFragmented(pkt, networkMTU) {
+		sent, remain, err := e.handleFragments(r, networkMTU, pkt, protocol, func(fragPkt *stack.PacketBuffer) tcpip.Error {
 			// TODO(gvisor.dev/issue/3884): Evaluate whether we want to send each
 			// fragment one by one using WritePacket() (current strategy) or if we
 			// want to create a PacketBufferList from the fragments and feed it to
 			// WritePackets(). It'll be faster but cost more memory.
-			return e.nic.WritePacket(r, gso, ProtocolNumber, fragPkt)
+			return e.nic.WritePacket(r, ProtocolNumber, fragPkt)
 		})
 		stats.PacketsSent.IncrementBy(uint64(sent))
 		stats.OutgoingPacketErrors.IncrementBy(uint64(remain))
 		return err
 	}
 
-	if err := e.nic.WritePacket(r, gso, ProtocolNumber, pkt); err != nil {
+	if err := e.nic.WritePacket(r, ProtocolNumber, pkt); err != nil {
 		stats.OutgoingPacketErrors.Increment()
 		return err
 	}
@@ -808,7 +808,7 @@ func (e *endpoint) writePacket(r *stack.Route, gso *stack.GSO, pkt *stack.Packet
 }
 
 // WritePackets implements stack.NetworkEndpoint.WritePackets.
-func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.PacketBufferList, params stack.NetworkHeaderParams) (int, tcpip.Error) {
+func (e *endpoint) WritePackets(r *stack.Route, pkts stack.PacketBufferList, params stack.NetworkHeaderParams) (int, tcpip.Error) {
 	if r.Loop()&stack.PacketLoop != 0 {
 		panic("not implemented")
 	}
@@ -828,11 +828,11 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 			stats.OutgoingPacketErrors.IncrementBy(uint64(pkts.Len()))
 			return 0, err
 		}
-		if packetMustBeFragmented(pb, networkMTU, gso) {
+		if packetMustBeFragmented(pb, networkMTU) {
 			// Keep track of the packet that is about to be fragmented so it can be
 			// removed once the fragmentation is done.
 			originalPkt := pb
-			if _, _, err := e.handleFragments(r, gso, networkMTU, pb, params.Protocol, func(fragPkt *stack.PacketBuffer) tcpip.Error {
+			if _, _, err := e.handleFragments(r, networkMTU, pb, params.Protocol, func(fragPkt *stack.PacketBuffer) tcpip.Error {
 				// Modify the packet list in place with the new fragments.
 				pkts.InsertAfter(pb, fragPkt)
 				pb = fragPkt
@@ -849,7 +849,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 	// iptables filtering. All packets that reach here are locally
 	// generated.
 	outNicName := e.protocol.stack.FindNICNameFromID(e.nic.ID())
-	outputDropped, natPkts := e.protocol.stack.IPTables().CheckPackets(stack.Output, pkts, gso, r, "" /* inNicName */, outNicName)
+	outputDropped, natPkts := e.protocol.stack.IPTables().CheckPackets(stack.Output, pkts, r, "" /* inNicName */, outNicName)
 	stats.IPTablesOutputDropped.IncrementBy(uint64(len(outputDropped)))
 	for pkt := range outputDropped {
 		pkts.Remove(pkt)
@@ -875,7 +875,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 	// We ignore the list of NAT-ed packets here because Postrouting NAT can only
 	// change the source address, and does not alter the route or outgoing
 	// interface of the packet.
-	postroutingDropped, _ := e.protocol.stack.IPTables().CheckPackets(stack.Postrouting, pkts, gso, r, "" /* inNicName */, outNicName)
+	postroutingDropped, _ := e.protocol.stack.IPTables().CheckPackets(stack.Postrouting, pkts, r, "" /* inNicName */, outNicName)
 	stats.IPTablesPostroutingDropped.IncrementBy(uint64(len(postroutingDropped)))
 	for pkt := range postroutingDropped {
 		pkts.Remove(pkt)
@@ -883,7 +883,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 
 	// The rest of the packets can be delivered to the NIC as a batch.
 	pktsLen := pkts.Len()
-	written, err := e.nic.WritePackets(r, gso, pkts, ProtocolNumber)
+	written, err := e.nic.WritePackets(r, pkts, ProtocolNumber)
 	stats.PacketsSent.IncrementBy(uint64(written))
 	stats.OutgoingPacketErrors.IncrementBy(uint64(pktsLen - written))
 
@@ -924,7 +924,7 @@ func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBu
 		return &tcpip.ErrMalformedHeader{}
 	}
 
-	return e.writePacket(r, nil /* gso */, pkt, proto, true /* headerIncluded */)
+	return e.writePacket(r, pkt, proto, true /* headerIncluded */)
 }
 
 // forwardPacket attempts to forward a packet to its final destination.
@@ -1027,7 +1027,7 @@ func (e *endpoint) HandlePacket(pkt *stack.PacketBuffer) {
 
 		// Loopback traffic skips the prerouting chain.
 		inNicName := e.protocol.stack.FindNICNameFromID(e.nic.ID())
-		if ok := e.protocol.stack.IPTables().Check(stack.Prerouting, pkt, nil, nil, e.MainAddress().Address, inNicName, "" /* outNicName */); !ok {
+		if ok := e.protocol.stack.IPTables().Check(stack.Prerouting, pkt, nil, e.MainAddress().Address, inNicName, "" /* outNicName */); !ok {
 			// iptables is telling us to drop the packet.
 			stats.IPTablesPreroutingDropped.Increment()
 			return
@@ -1097,7 +1097,7 @@ func (e *endpoint) handleValidatedPacket(h header.IPv6, pkt *stack.PacketBuffer)
 	// iptables filtering. All packets that reach here are intended for
 	// this machine and need not be forwarded.
 	inNicName := e.protocol.stack.FindNICNameFromID(e.nic.ID())
-	if ok := e.protocol.stack.IPTables().Check(stack.Input, pkt, nil, nil, "" /* preroutingAddr */, inNicName, "" /* outNicName */); !ok {
+	if ok := e.protocol.stack.IPTables().Check(stack.Input, pkt, nil, "" /* preroutingAddr */, inNicName, "" /* outNicName */); !ok {
 		// iptables is telling us to drop the packet.
 		stats.IPTablesInputDropped.Increment()
 		return
diff --git a/pkg/tcpip/network/ipv6/ipv6_test.go b/pkg/tcpip/network/ipv6/ipv6_test.go
index a620e9ad9..40a793d6b 100644
--- a/pkg/tcpip/network/ipv6/ipv6_test.go
+++ b/pkg/tcpip/network/ipv6/ipv6_test.go
@@ -2584,7 +2584,7 @@ func TestWriteStats(t *testing.T) {
 			writePackets: func(rt *stack.Route, pkts stack.PacketBufferList) (int, tcpip.Error) {
 				nWritten := 0
 				for pkt := pkts.Front(); pkt != nil; pkt = pkt.Next() {
-					if err := rt.WritePacket(nil, stack.NetworkHeaderParams{}, pkt); err != nil {
+					if err := rt.WritePacket(stack.NetworkHeaderParams{}, pkt); err != nil {
 						return nWritten, err
 					}
 					nWritten++
@@ -2594,7 +2594,7 @@ func TestWriteStats(t *testing.T) {
 		}, {
 			name: "WritePackets",
 			writePackets: func(rt *stack.Route, pkts stack.PacketBufferList) (int, tcpip.Error) {
-				return rt.WritePackets(nil, pkts, stack.NetworkHeaderParams{})
+				return rt.WritePackets(pkts, stack.NetworkHeaderParams{})
 			},
 		},
 	}
@@ -2739,7 +2739,6 @@ type fragmentInfo struct {
 var fragmentationTests = []struct {
 	description   string
 	mtu           uint32
-	gso           *stack.GSO
 	transHdrLen   int
 	payloadSize   int
 	wantFragments []fragmentInfo
@@ -2747,7 +2746,6 @@ var fragmentationTests = []struct {
 	{
 		description: "No fragmentation",
 		mtu:         header.IPv6MinimumMTU,
-		gso:         nil,
 		transHdrLen: 0,
 		payloadSize: 1000,
 		wantFragments: []fragmentInfo{
@@ -2757,7 +2755,6 @@ var fragmentationTests = []struct {
 	{
 		description: "Fragmented",
 		mtu:         header.IPv6MinimumMTU,
-		gso:         nil,
 		transHdrLen: 0,
 		payloadSize: 2000,
 		wantFragments: []fragmentInfo{
@@ -2768,7 +2765,6 @@ var fragmentationTests = []struct {
 	{
 		description: "Fragmented with mtu not a multiple of 8",
 		mtu:         header.IPv6MinimumMTU + 1,
-		gso:         nil,
 		transHdrLen: 0,
 		payloadSize: 2000,
 		wantFragments: []fragmentInfo{
@@ -2779,7 +2775,6 @@ var fragmentationTests = []struct {
 	{
 		description: "No fragmentation with big header",
 		mtu:         2000,
-		gso:         nil,
 		transHdrLen: 100,
 		payloadSize: 1000,
 		wantFragments: []fragmentInfo{
@@ -2787,20 +2782,8 @@ var fragmentationTests = []struct {
 		},
 	},
 	{
-		description: "Fragmented with gso none",
-		mtu:         header.IPv6MinimumMTU,
-		gso:         &stack.GSO{Type: stack.GSONone},
-		transHdrLen: 0,
-		payloadSize: 1400,
-		wantFragments: []fragmentInfo{
-			{offset: 0, payloadSize: 1240, more: true},
-			{offset: 154, payloadSize: 176, more: false},
-		},
-	},
-	{
 		description: "Fragmented with big header",
 		mtu:         header.IPv6MinimumMTU,
-		gso:         nil,
 		transHdrLen: 100,
 		payloadSize: 1200,
 		wantFragments: []fragmentInfo{
@@ -2823,7 +2806,7 @@ func TestFragmentationWritePacket(t *testing.T) {
 			source := pkt.Clone()
 			ep := testutil.NewMockLinkEndpoint(ft.mtu, nil, math.MaxInt32)
 			r := buildRoute(t, ep)
-			err := r.WritePacket(ft.gso, stack.NetworkHeaderParams{
+			err := r.WritePacket(stack.NetworkHeaderParams{
 				Protocol: tcp.ProtocolNumber,
 				TTL:      ttl,
 				TOS:      stack.DefaultTOS,
@@ -2896,7 +2879,7 @@ func TestFragmentationWritePackets(t *testing.T) {
 					r := buildRoute(t, ep)
 
 					wantTotalPackets := len(ft.wantFragments) + test.insertBefore + test.insertAfter
-					n, err := r.WritePackets(ft.gso, pkts, stack.NetworkHeaderParams{
+					n, err := r.WritePackets(pkts, stack.NetworkHeaderParams{
 						Protocol: tcp.ProtocolNumber,
 						TTL:      ttl,
 						TOS:      stack.DefaultTOS,
@@ -3000,7 +2983,7 @@ func TestFragmentationErrors(t *testing.T) {
 			pkt := testutil.MakeRandPkt(ft.transHdrLen, extraHeaderReserve+header.IPv6MinimumSize, []int{ft.payloadSize}, header.IPv6ProtocolNumber)
 			ep := testutil.NewMockLinkEndpoint(ft.mtu, ft.mockError, ft.allowPackets)
 			r := buildRoute(t, ep)
-			err := r.WritePacket(&stack.GSO{}, stack.NetworkHeaderParams{
+			err := r.WritePacket(stack.NetworkHeaderParams{
 				Protocol: tcp.ProtocolNumber,
 				TTL:      ttl,
 				TOS:      stack.DefaultTOS,
diff --git a/pkg/tcpip/network/ipv6/mld.go b/pkg/tcpip/network/ipv6/mld.go
index 165b7d2d2..bc1af193c 100644
--- a/pkg/tcpip/network/ipv6/mld.go
+++ b/pkg/tcpip/network/ipv6/mld.go
@@ -277,7 +277,7 @@ func (mld *mldState) writePacket(destAddress, groupAddress tcpip.Address, mldTyp
 	}, extensionHeaders); err != nil {
 		panic(fmt.Sprintf("failed to add IP header: %s", err))
 	}
-	if err := mld.ep.nic.WritePacketToRemote(header.EthernetAddressFromMulticastIPv6Address(destAddress), nil /* gso */, ProtocolNumber, pkt); err != nil {
+	if err := mld.ep.nic.WritePacketToRemote(header.EthernetAddressFromMulticastIPv6Address(destAddress), ProtocolNumber, pkt); err != nil {
 		sentStats.dropped.Increment()
 		return false, err
 	}
diff --git a/pkg/tcpip/network/ipv6/ndp.go b/pkg/tcpip/network/ipv6/ndp.go
index a110faa54..d6e0a81a6 100644
--- a/pkg/tcpip/network/ipv6/ndp.go
+++ b/pkg/tcpip/network/ipv6/ndp.go
@@ -1746,7 +1746,7 @@ func (ndp *ndpState) startSolicitingRouters() {
 				panic(fmt.Sprintf("failed to add IP header: %s", err))
 			}
 
-			if err := ndp.ep.nic.WritePacketToRemote(header.EthernetAddressFromMulticastIPv6Address(header.IPv6AllRoutersLinkLocalMulticastAddress), nil /* gso */, ProtocolNumber, pkt); err != nil {
+			if err := ndp.ep.nic.WritePacketToRemote(header.EthernetAddressFromMulticastIPv6Address(header.IPv6AllRoutersLinkLocalMulticastAddress), ProtocolNumber, pkt); err != nil {
 				sent.dropped.Increment()
 				// Don't send any more messages if we had an error.
 				remaining = 0
@@ -1839,7 +1839,7 @@ func (e *endpoint) sendNDPNS(srcAddr, dstAddr, targetAddr tcpip.Address, remoteL
 	}
 
 	sent := e.stats.icmp.packetsSent
-	err := e.nic.WritePacketToRemote(remoteLinkAddr, nil /* gso */, ProtocolNumber, pkt)
+	err := e.nic.WritePacketToRemote(remoteLinkAddr, ProtocolNumber, pkt)
 	if err != nil {
 		sent.dropped.Increment()
 	} else {