Make dedicated methods for data operations in PacketBuffer

One of the preparation to decouple underlying buffer implementation.
There are still some methods that tie to VectorisedView, and they will be
changed gradually in later CLs.

This CL also introduce a new ICMPv6ChecksumParams to replace long list of
parameters when calling ICMPv6Checksum, aiming to be more descriptive.

PiperOrigin-RevId: 360778149

8 files changed, 186 insertions, 73 deletions

diff --git a/pkg/tcpip/network/ipv6/icmp.go b/pkg/tcpip/network/ipv6/icmp.go
index 5f44ab317..e80e681da 100644
--- a/pkg/tcpip/network/ipv6/icmp.go
+++ b/pkg/tcpip/network/ipv6/icmp.go
@@ -18,7 +18,6 @@ import (
 	"fmt"
 
 	"gvisor.dev/gvisor/pkg/tcpip"
-	"gvisor.dev/gvisor/pkg/tcpip/buffer"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 )
@@ -165,7 +164,7 @@ func (e *endpoint) checkLocalAddress(addr tcpip.Address) bool {
 // used to find out which transport endpoint must be notified about the ICMP
 // packet.
 func (e *endpoint) handleControl(transErr stack.TransportError, pkt *stack.PacketBuffer) {
-	h, ok := pkt.Data.PullUp(header.IPv6MinimumSize)
+	h, ok := pkt.Data().PullUp(header.IPv6MinimumSize)
 	if !ok {
 		return
 	}
@@ -184,10 +183,10 @@ func (e *endpoint) handleControl(transErr stack.TransportError, pkt *stack.Packe
 
 	// Skip the IP header, then handle the fragmentation header if there
 	// is one.
-	pkt.Data.TrimFront(header.IPv6MinimumSize)
+	pkt.Data().TrimFront(header.IPv6MinimumSize)
 	p := hdr.TransportProtocol()
 	if p == header.IPv6FragmentHeader {
-		f, ok := pkt.Data.PullUp(header.IPv6FragmentHeaderSize)
+		f, ok := pkt.Data().PullUp(header.IPv6FragmentHeaderSize)
 		if !ok {
 			return
 		}
@@ -200,7 +199,7 @@ func (e *endpoint) handleControl(transErr stack.TransportError, pkt *stack.Packe
 
 		// Skip fragmentation header and find out the actual protocol
 		// number.
-		pkt.Data.TrimFront(header.IPv6FragmentHeaderSize)
+		pkt.Data().TrimFront(header.IPv6FragmentHeaderSize)
 		p = fragHdr.TransportProtocol()
 	}
 
@@ -268,7 +267,7 @@ func isMLDValid(pkt *stack.PacketBuffer, iph header.IPv6, routerAlert *header.IP
 	if routerAlert == nil || routerAlert.Value != header.IPv6RouterAlertMLD {
 		return false
 	}
-	if pkt.Data.Size() < header.ICMPv6HeaderSize+header.MLDMinimumSize {
+	if pkt.Data().Size() < header.ICMPv6HeaderSize+header.MLDMinimumSize {
 		return false
 	}
 	if iph.HopLimit() != header.MLDHopLimit {
@@ -285,7 +284,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 	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.
-	v, ok := pkt.Data.PullUp(header.ICMPv6HeaderSize)
+	v, ok := pkt.Data().PullUp(header.ICMPv6HeaderSize)
 	if !ok {
 		received.invalid.Increment()
 		return
@@ -296,11 +295,14 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 	dstAddr := iph.DestinationAddress()
 
 	// Validate ICMPv6 checksum before processing the packet.
-	//
-	// This copy is used as extra payload during the checksum calculation.
-	payload := pkt.Data.Clone(nil)
-	payload.TrimFront(len(h))
-	if got, want := h.Checksum(), header.ICMPv6Checksum(h, srcAddr, dstAddr, payload); got != want {
+	payload := pkt.Data().AsRange().SubRange(len(h))
+	if got, want := h.Checksum(), header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+		Header:      h,
+		Src:         srcAddr,
+		Dst:         dstAddr,
+		PayloadCsum: payload.Checksum(),
+		PayloadLen:  payload.Size(),
+	}); got != want {
 		received.invalid.Increment()
 		return
 	}
@@ -320,12 +322,12 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 	switch icmpType := h.Type(); icmpType {
 	case header.ICMPv6PacketTooBig:
 		received.packetTooBig.Increment()
-		hdr, ok := pkt.Data.PullUp(header.ICMPv6PacketTooBigMinimumSize)
+		hdr, ok := pkt.Data().PullUp(header.ICMPv6PacketTooBigMinimumSize)
 		if !ok {
 			received.invalid.Increment()
 			return
 		}
-		pkt.Data.TrimFront(header.ICMPv6PacketTooBigMinimumSize)
+		pkt.Data().TrimFront(header.ICMPv6PacketTooBigMinimumSize)
 		networkMTU, err := calculateNetworkMTU(header.ICMPv6(hdr).MTU(), header.IPv6MinimumSize)
 		if err != nil {
 			networkMTU = 0
@@ -334,12 +336,12 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 
 	case header.ICMPv6DstUnreachable:
 		received.dstUnreachable.Increment()
-		hdr, ok := pkt.Data.PullUp(header.ICMPv6DstUnreachableMinimumSize)
+		hdr, ok := pkt.Data().PullUp(header.ICMPv6DstUnreachableMinimumSize)
 		if !ok {
 			received.invalid.Increment()
 			return
 		}
-		pkt.Data.TrimFront(header.ICMPv6DstUnreachableMinimumSize)
+		pkt.Data().TrimFront(header.ICMPv6DstUnreachableMinimumSize)
 		switch header.ICMPv6(hdr).Code() {
 		case header.ICMPv6NetworkUnreachable:
 			e.handleControl(&icmpv6DestinationNetworkUnreachableSockError{}, pkt)
@@ -348,16 +350,16 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 		}
 	case header.ICMPv6NeighborSolicit:
 		received.neighborSolicit.Increment()
-		if !isNDPValid() || pkt.Data.Size() < header.ICMPv6NeighborSolicitMinimumSize {
+		if !isNDPValid() || pkt.Data().Size() < header.ICMPv6NeighborSolicitMinimumSize {
 			received.invalid.Increment()
 			return
 		}
 
 		// The remainder of payload must be only the neighbor solicitation, so
-		// payload.ToView() always returns the solicitation. Per RFC 6980 section 5,
+		// payload.AsView() always returns the solicitation. Per RFC 6980 section 5,
 		// NDP messages cannot be fragmented. Also note that in the common case NDP
-		// datagrams are very small and ToView() will not incur allocations.
-		ns := header.NDPNeighborSolicit(payload.ToView())
+		// datagrams are very small and AsView() will not incur allocations.
+		ns := header.NDPNeighborSolicit(payload.AsView())
 		targetAddr := ns.TargetAddress()
 
 		// As per RFC 4861 section 4.3, the Target Address MUST NOT be a multicast
@@ -529,7 +531,11 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 		na.SetOverrideFlag(true)
 		na.SetTargetAddress(targetAddr)
 		na.Options().Serialize(optsSerializer)
-		packet.SetChecksum(header.ICMPv6Checksum(packet, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{}))
+		packet.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+			Header: packet,
+			Src:    r.LocalAddress,
+			Dst:    r.RemoteAddress,
+		}))
 
 		// RFC 4861 Neighbor Discovery for IP version 6 (IPv6)
 		//
@@ -545,16 +551,16 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 
 	case header.ICMPv6NeighborAdvert:
 		received.neighborAdvert.Increment()
-		if !isNDPValid() || pkt.Data.Size() < header.ICMPv6NeighborAdvertMinimumSize {
+		if !isNDPValid() || pkt.Data().Size() < header.ICMPv6NeighborAdvertMinimumSize {
 			received.invalid.Increment()
 			return
 		}
 
 		// The remainder of payload must be only the neighbor advertisement, so
-		// payload.ToView() always returns the advertisement. Per RFC 6980 section
+		// payload.AsView() always returns the advertisement. Per RFC 6980 section
 		// 5, NDP messages cannot be fragmented. Also note that in the common case
-		// NDP datagrams are very small and ToView() will not incur allocations.
-		na := header.NDPNeighborAdvert(payload.ToView())
+		// NDP datagrams are very small and AsView() will not incur allocations.
+		na := header.NDPNeighborAdvert(payload.AsView())
 		targetAddr := na.TargetAddress()
 
 		e.dad.mu.Lock()
@@ -657,13 +663,20 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 
 		replyPkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
 			ReserveHeaderBytes: int(r.MaxHeaderLength()) + header.ICMPv6EchoMinimumSize,
-			Data:               pkt.Data,
+			Data:               pkt.Data().ExtractVV(),
 		})
-		packet := header.ICMPv6(replyPkt.TransportHeader().Push(header.ICMPv6EchoMinimumSize))
+		icmp := header.ICMPv6(replyPkt.TransportHeader().Push(header.ICMPv6EchoMinimumSize))
 		pkt.TransportProtocolNumber = header.ICMPv6ProtocolNumber
-		copy(packet, icmpHdr)
-		packet.SetType(header.ICMPv6EchoReply)
-		packet.SetChecksum(header.ICMPv6Checksum(packet, r.LocalAddress, r.RemoteAddress, pkt.Data))
+		copy(icmp, icmpHdr)
+		icmp.SetType(header.ICMPv6EchoReply)
+		dataRange := replyPkt.Data().AsRange()
+		icmp.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+			Header:      icmp,
+			Src:         r.LocalAddress,
+			Dst:         r.RemoteAddress,
+			PayloadCsum: dataRange.Checksum(),
+			PayloadLen:  dataRange.Size(),
+		}))
 		if err := r.WritePacket(nil /* gso */, stack.NetworkHeaderParams{
 			Protocol: header.ICMPv6ProtocolNumber,
 			TTL:      r.DefaultTTL(),
@@ -676,7 +689,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 
 	case header.ICMPv6EchoReply:
 		received.echoReply.Increment()
-		if pkt.Data.Size() < header.ICMPv6EchoMinimumSize {
+		if pkt.Data().Size() < header.ICMPv6EchoMinimumSize {
 			received.invalid.Increment()
 			return
 		}
@@ -696,7 +709,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 		//
 
 		// Is the NDP payload of sufficient size to hold a Router Solictation?
-		if !isNDPValid() || pkt.Data.Size()-header.ICMPv6HeaderSize < header.NDPRSMinimumSize {
+		if !isNDPValid() || pkt.Data().Size()-header.ICMPv6HeaderSize < header.NDPRSMinimumSize {
 			received.invalid.Increment()
 			return
 		}
@@ -710,9 +723,9 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 			return
 		}
 
-		// Note that in the common case NDP datagrams are very small and ToView()
+		// Note that in the common case NDP datagrams are very small and AsView()
 		// will not incur allocations.
-		rs := header.NDPRouterSolicit(payload.ToView())
+		rs := header.NDPRouterSolicit(payload.AsView())
 		it, err := rs.Options().Iter(false /* check */)
 		if err != nil {
 			// Options are not valid as per the wire format, silently drop the packet.
@@ -756,7 +769,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 		//
 
 		// Is the NDP payload of sufficient size to hold a Router Advertisement?
-		if !isNDPValid() || pkt.Data.Size()-header.ICMPv6HeaderSize < header.NDPRAMinimumSize {
+		if !isNDPValid() || pkt.Data().Size()-header.ICMPv6HeaderSize < header.NDPRAMinimumSize {
 			received.invalid.Increment()
 			return
 		}
@@ -770,9 +783,9 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 			return
 		}
 
-		// Note that in the common case NDP datagrams are very small and ToView()
+		// Note that in the common case NDP datagrams are very small and AsView()
 		// will not incur allocations.
-		ra := header.NDPRouterAdvert(payload.ToView())
+		ra := header.NDPRouterAdvert(payload.AsView())
 		it, err := ra.Options().Iter(false /* check */)
 		if err != nil {
 			// Options are not valid as per the wire format, silently drop the packet.
@@ -850,11 +863,11 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 		switch icmpType {
 		case header.ICMPv6MulticastListenerQuery:
 			e.mu.Lock()
-			e.mu.mld.handleMulticastListenerQuery(header.MLD(payload.ToView()))
+			e.mu.mld.handleMulticastListenerQuery(header.MLD(payload.AsView()))
 			e.mu.Unlock()
 		case header.ICMPv6MulticastListenerReport:
 			e.mu.Lock()
-			e.mu.mld.handleMulticastListenerReport(header.MLD(payload.ToView()))
+			e.mu.mld.handleMulticastListenerReport(header.MLD(payload.AsView()))
 			e.mu.Unlock()
 		case header.ICMPv6MulticastListenerDone:
 		default:
@@ -1077,13 +1090,13 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) tcpip
 	if available < header.IPv6MinimumSize {
 		return nil
 	}
-	payloadLen := network.Size() + transport.Size() + pkt.Data.Size()
+	payloadLen := network.Size() + transport.Size() + pkt.Data().Size()
 	if payloadLen > available {
 		payloadLen = available
 	}
 	payload := network.ToVectorisedView()
 	payload.AppendView(transport)
-	payload.Append(pkt.Data)
+	payload.Append(pkt.Data().ExtractVV())
 	payload.CapLength(payloadLen)
 
 	newPkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
@@ -1115,7 +1128,14 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) tcpip
 	default:
 		panic(fmt.Sprintf("unsupported ICMP type %T", reason))
 	}
-	icmpHdr.SetChecksum(header.ICMPv6Checksum(icmpHdr, route.LocalAddress, route.RemoteAddress, newPkt.Data))
+	dataRange := newPkt.Data().AsRange()
+	icmpHdr.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+		Header:      icmpHdr,
+		Src:         route.LocalAddress,
+		Dst:         route.RemoteAddress,
+		PayloadCsum: dataRange.Checksum(),
+		PayloadLen:  dataRange.Size(),
+	}))
 	if err := route.WritePacket(
 		nil, /* gso */
 		stack.NetworkHeaderParams{
diff --git a/pkg/tcpip/network/ipv6/icmp_test.go b/pkg/tcpip/network/ipv6/icmp_test.go
index c27164344..d4e63710c 100644
--- a/pkg/tcpip/network/ipv6/icmp_test.go
+++ b/pkg/tcpip/network/ipv6/icmp_test.go
@@ -324,7 +324,13 @@ func TestICMPCounts(t *testing.T) {
 		icmp := header.ICMPv6(buffer.NewView(typ.size + len(typ.extraData)))
 		copy(icmp[typ.size:], typ.extraData)
 		icmp.SetType(typ.typ)
-		icmp.SetChecksum(header.ICMPv6Checksum(icmp[:typ.size], lladdr0, lladdr1, buffer.View(typ.extraData).ToVectorisedView()))
+		icmp.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+			Header:      icmp[:typ.size],
+			Src:         lladdr0,
+			Dst:         lladdr1,
+			PayloadCsum: header.Checksum(typ.extraData, 0 /* initial */),
+			PayloadLen:  len(typ.extraData),
+		}))
 		handleICMPInIPv6(ep, lladdr1, lladdr0, icmp, typ.hopLimit, typ.includeRouterAlert)
 	}
 
@@ -498,7 +504,11 @@ func TestLinkResolution(t *testing.T) {
 	hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.IPv6MinimumSize + header.ICMPv6EchoMinimumSize)
 	pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6EchoMinimumSize))
 	pkt.SetType(header.ICMPv6EchoRequest)
-	pkt.SetChecksum(header.ICMPv6Checksum(pkt, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{}))
+	pkt.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+		Header: pkt,
+		Src:    r.LocalAddress,
+		Dst:    r.RemoteAddress,
+	}))
 
 	// We can't send our payload directly over the route because that
 	// doesn't provoke NDP discovery.
@@ -687,7 +697,11 @@ func TestICMPChecksumValidationSimple(t *testing.T) {
 					copy(icmp[typ.size:], typ.extraData)
 					icmp.SetType(typ.typ)
 					if checksum {
-						icmp.SetChecksum(header.ICMPv6Checksum(icmp, lladdr1, lladdr0, buffer.View{}.ToVectorisedView()))
+						icmp.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+							Header: icmp,
+							Src:    lladdr1,
+							Dst:    lladdr0,
+						}))
 					}
 					ip := header.IPv6(buffer.NewView(header.IPv6MinimumSize))
 					ip.Encode(&header.IPv6Fields{
@@ -879,7 +893,11 @@ func TestICMPChecksumValidationWithPayload(t *testing.T) {
 				payloadFn(icmpHdr.Payload())
 
 				if checksum {
-					icmpHdr.SetChecksum(header.ICMPv6Checksum(icmpHdr, lladdr1, lladdr0, buffer.VectorisedView{}))
+					icmpHdr.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+						Header: icmpHdr,
+						Src:    lladdr1,
+						Dst:    lladdr0,
+					}))
 				}
 
 				ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
@@ -1058,7 +1076,13 @@ func TestICMPChecksumValidationWithPayloadMultipleViews(t *testing.T) {
 				payloadFn(payload)
 
 				if checksum {
-					icmpHdr.SetChecksum(header.ICMPv6Checksum(icmpHdr, lladdr1, lladdr0, payload.ToVectorisedView()))
+					icmpHdr.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+						Header:      icmpHdr,
+						Src:         lladdr1,
+						Dst:         lladdr0,
+						PayloadCsum: header.Checksum(payload, 0 /* initial */),
+						PayloadLen:  len(payload),
+					}))
 				}
 
 				ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
@@ -1324,7 +1348,11 @@ func TestPacketQueing(t *testing.T) {
 				pkt.SetType(header.ICMPv6EchoRequest)
 				pkt.SetCode(0)
 				pkt.SetChecksum(0)
-				pkt.SetChecksum(header.ICMPv6Checksum(pkt, host2IPv6Addr.AddressWithPrefix.Address, host1IPv6Addr.AddressWithPrefix.Address, buffer.VectorisedView{}))
+				pkt.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+					Header: pkt,
+					Src:    host2IPv6Addr.AddressWithPrefix.Address,
+					Dst:    host1IPv6Addr.AddressWithPrefix.Address,
+				}))
 				ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
 				ip.Encode(&header.IPv6Fields{
 					PayloadLength:     header.ICMPv6MinimumSize,
@@ -1422,7 +1450,11 @@ func TestPacketQueing(t *testing.T) {
 				na.Options().Serialize(header.NDPOptionsSerializer{
 					header.NDPTargetLinkLayerAddressOption(host2NICLinkAddr),
 				})
-				pkt.SetChecksum(header.ICMPv6Checksum(pkt, host2IPv6Addr.AddressWithPrefix.Address, host1IPv6Addr.AddressWithPrefix.Address, buffer.VectorisedView{}))
+				pkt.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+					Header: pkt,
+					Src:    host2IPv6Addr.AddressWithPrefix.Address,
+					Dst:    host1IPv6Addr.AddressWithPrefix.Address,
+				}))
 				payloadLength := hdr.UsedLength()
 				ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
 				ip.Encode(&header.IPv6Fields{
@@ -1661,7 +1693,11 @@ func TestCallsToNeighborCache(t *testing.T) {
 			}
 
 			icmp := test.createPacket()
-			icmp.SetChecksum(header.ICMPv6Checksum(icmp, test.source, test.destination, buffer.VectorisedView{}))
+			icmp.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+				Header: icmp,
+				Src:    test.source,
+				Dst:    test.destination,
+			}))
 			handleICMPInIPv6(ep, test.source, test.destination, icmp, header.NDPHopLimit, false)
 
 			// Confirm the endpoint calls the correct NUDHandler method.
diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go
index 7638ade35..544717678 100644
--- a/pkg/tcpip/network/ipv6/ipv6.go
+++ b/pkg/tcpip/network/ipv6/ipv6.go
@@ -619,7 +619,7 @@ func addIPHeader(srcAddr, dstAddr tcpip.Address, pkt *stack.PacketBuffer, params
 }
 
 func packetMustBeFragmented(pkt *stack.PacketBuffer, networkMTU uint32, gso *stack.GSO) bool {
-	payload := pkt.TransportHeader().View().Size() + pkt.Data.Size()
+	payload := pkt.TransportHeader().View().Size() + pkt.Data().Size()
 	return (gso == nil || gso.Type == stack.GSONone) && uint32(payload) > networkMTU
 }
 
@@ -819,14 +819,14 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 // WriteHeaderIncludedPacket implements stack.NetworkEndpoint.
 func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBuffer) tcpip.Error {
 	// The packet already has an IP header, but there are a few required checks.
-	h, ok := pkt.Data.PullUp(header.IPv6MinimumSize)
+	h, ok := pkt.Data().PullUp(header.IPv6MinimumSize)
 	if !ok {
 		return &tcpip.ErrMalformedHeader{}
 	}
 	ip := header.IPv6(h)
 
 	// Always set the payload length.
-	pktSize := pkt.Data.Size()
+	pktSize := pkt.Data().Size()
 	ip.SetPayloadLength(uint16(pktSize - header.IPv6MinimumSize))
 
 	// Set the source address when zero.
@@ -964,7 +964,7 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 	stats := e.stats.ip
 
 	h := header.IPv6(pkt.NetworkHeader().View())
-	if !h.IsValid(pkt.Data.Size() + pkt.NetworkHeader().View().Size() + pkt.TransportHeader().View().Size()) {
+	if !h.IsValid(pkt.Data().Size() + pkt.NetworkHeader().View().Size() + pkt.TransportHeader().View().Size()) {
 		stats.MalformedPacketsReceived.Increment()
 		return
 	}
@@ -993,13 +993,14 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 		return
 	}
 
+	// Create a VV to parse the packet. We don't plan to modify anything here.
 	// vv consists of:
 	// - Any IPv6 header bytes after the first 40 (i.e. extensions).
 	// - The transport header, if present.
 	// - Any other payload data.
 	vv := pkt.NetworkHeader().View()[header.IPv6MinimumSize:].ToVectorisedView()
 	vv.AppendView(pkt.TransportHeader().View())
-	vv.Append(pkt.Data)
+	vv.AppendViews(pkt.Data().Views())
 	it := header.MakeIPv6PayloadIterator(header.IPv6ExtensionHeaderIdentifier(h.NextHeader()), vv)
 
 	// iptables filtering. All packets that reach here are intended for
@@ -1257,7 +1258,9 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 				// have more extension headers in the reassembled payload, as per RFC
 				// 8200 section 4.5. We also use the NextHeader value from the first
 				// fragment.
-				it = header.MakeIPv6PayloadIterator(header.IPv6ExtensionHeaderIdentifier(proto), pkt.Data)
+				data := pkt.Data()
+				dataVV := buffer.NewVectorisedView(data.Size(), data.Views())
+				it = header.MakeIPv6PayloadIterator(header.IPv6ExtensionHeaderIdentifier(proto), dataVV)
 			}
 
 		case header.IPv6DestinationOptionsExtHdr:
@@ -1314,7 +1317,7 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 			// For reassembled fragments, pkt.TransportHeader is unset, so this is a
 			// no-op and pkt.Data begins with the transport header.
 			extHdr.Buf.TrimFront(pkt.TransportHeader().View().Size())
-			pkt.Data = extHdr.Buf
+			pkt.Data().Replace(extHdr.Buf)
 
 			stats.PacketsDelivered.Increment()
 			if p := tcpip.TransportProtocolNumber(extHdr.Identifier); p == header.ICMPv6ProtocolNumber {
diff --git a/pkg/tcpip/network/ipv6/ipv6_test.go b/pkg/tcpip/network/ipv6/ipv6_test.go
index 05c9f4dbf..266a53e3b 100644
--- a/pkg/tcpip/network/ipv6/ipv6_test.go
+++ b/pkg/tcpip/network/ipv6/ipv6_test.go
@@ -68,7 +68,11 @@ func testReceiveICMP(t *testing.T, s *stack.Stack, e *channel.Endpoint, src, dst
 	hdr := buffer.NewPrependable(header.IPv6MinimumSize + header.ICMPv6NeighborAdvertMinimumSize)
 	pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6NeighborAdvertMinimumSize))
 	pkt.SetType(header.ICMPv6NeighborAdvert)
-	pkt.SetChecksum(header.ICMPv6Checksum(pkt, src, dst, buffer.VectorisedView{}))
+	pkt.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+		Header: pkt,
+		Src:    src,
+		Dst:    dst,
+	}))
 	payloadLength := hdr.UsedLength()
 	ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
 	ip.Encode(&header.IPv6Fields{
@@ -216,7 +220,7 @@ func compareFragments(packets []*stack.PacketBuffer, sourcePacket *stack.PacketB
 		// Store the reassembled payload as we parse each fragment. The payload
 		// includes the Transport header and everything after.
 		reassembledPayload.AppendView(fragment.TransportHeader().View())
-		reassembledPayload.Append(fragment.Data)
+		reassembledPayload.AppendView(fragment.Data().AsRange().ToOwnedView())
 	}
 
 	if diff := cmp.Diff(buffer.View(source[sourceIPHeadersLen:]), reassembledPayload.ToView()); diff != "" {
@@ -3065,7 +3069,11 @@ func TestForwarding(t *testing.T) {
 			icmp.SetType(header.ICMPv6EchoRequest)
 			icmp.SetCode(header.ICMPv6UnusedCode)
 			icmp.SetChecksum(0)
-			icmp.SetChecksum(header.ICMPv6Checksum(icmp, remoteIPv6Addr1, remoteIPv6Addr2, buffer.VectorisedView{}))
+			icmp.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+				Header: icmp,
+				Src:    remoteIPv6Addr1,
+				Dst:    remoteIPv6Addr2,
+			}))
 			ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
 			ip.Encode(&header.IPv6Fields{
 				PayloadLength:     header.ICMPv6MinimumSize,
diff --git a/pkg/tcpip/network/ipv6/mld.go b/pkg/tcpip/network/ipv6/mld.go
index 205e36cdd..dd153466d 100644
--- a/pkg/tcpip/network/ipv6/mld.go
+++ b/pkg/tcpip/network/ipv6/mld.go
@@ -236,7 +236,11 @@ func (mld *mldState) writePacket(destAddress, groupAddress tcpip.Address, mldTyp
 		localAddress = header.IPv6Any
 	}
 
-	icmp.SetChecksum(header.ICMPv6Checksum(icmp, localAddress, destAddress, buffer.VectorisedView{}))
+	icmp.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+		Header: icmp,
+		Src:    localAddress,
+		Dst:    destAddress,
+	}))
 
 	extensionHeaders := header.IPv6ExtHdrSerializer{
 		header.IPv6SerializableHopByHopExtHdr{
diff --git a/pkg/tcpip/network/ipv6/mld_test.go b/pkg/tcpip/network/ipv6/mld_test.go
index f1b8d58f2..9a425e50a 100644
--- a/pkg/tcpip/network/ipv6/mld_test.go
+++ b/pkg/tcpip/network/ipv6/mld_test.go
@@ -326,11 +326,15 @@ func createAndInjectMLDPacket(e *channel.Endpoint, mldType header.ICMPv6Type, ho
 	mld := header.MLD(icmp.MessageBody())
 	mld.SetMaximumResponseDelay(0)
 	mld.SetMulticastAddress(header.IPv6Any)
-	icmp.SetChecksum(header.ICMPv6Checksum(icmp, srcAddress, header.IPv6AllNodesMulticastAddress, buffer.VectorisedView{}))
+	icmp.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+		Header: icmp,
+		Src:    srcAddress,
+		Dst:    header.IPv6AllNodesMulticastAddress,
+	}))
 
-	e.InjectInbound(ipv6.ProtocolNumber, &stack.PacketBuffer{
+	e.InjectInbound(ipv6.ProtocolNumber, stack.NewPacketBuffer(stack.PacketBufferOptions{
 		Data: buf.ToVectorisedView(),
-	})
+	}))
 }
 
 func TestMLDPacketValidation(t *testing.T) {
diff --git a/pkg/tcpip/network/ipv6/ndp.go b/pkg/tcpip/network/ipv6/ndp.go
index 721269c58..c22f60709 100644
--- a/pkg/tcpip/network/ipv6/ndp.go
+++ b/pkg/tcpip/network/ipv6/ndp.go
@@ -1721,7 +1721,11 @@ func (ndp *ndpState) startSolicitingRouters() {
 			icmpData.SetType(header.ICMPv6RouterSolicit)
 			rs := header.NDPRouterSolicit(icmpData.MessageBody())
 			rs.Options().Serialize(optsSerializer)
-			icmpData.SetChecksum(header.ICMPv6Checksum(icmpData, localAddr, header.IPv6AllRoutersMulticastAddress, buffer.VectorisedView{}))
+			icmpData.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+				Header: icmpData,
+				Src:    localAddr,
+				Dst:    header.IPv6AllRoutersMulticastAddress,
+			}))
 
 			pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
 				ReserveHeaderBytes: int(ndp.ep.MaxHeaderLength()),
@@ -1812,7 +1816,11 @@ func (e *endpoint) sendNDPNS(srcAddr, dstAddr, targetAddr tcpip.Address, remoteL
 	ns := header.NDPNeighborSolicit(icmp.MessageBody())
 	ns.SetTargetAddress(targetAddr)
 	ns.Options().Serialize(opts)
-	icmp.SetChecksum(header.ICMPv6Checksum(icmp, srcAddr, dstAddr, buffer.VectorisedView{}))
+	icmp.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+		Header: icmp,
+		Src:    srcAddr,
+		Dst:    dstAddr,
+	}))
 
 	pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
 		ReserveHeaderBytes: int(e.MaxHeaderLength()),
diff --git a/pkg/tcpip/network/ipv6/ndp_test.go b/pkg/tcpip/network/ipv6/ndp_test.go
index ce20af0e3..0d53c260d 100644
--- a/pkg/tcpip/network/ipv6/ndp_test.go
+++ b/pkg/tcpip/network/ipv6/ndp_test.go
@@ -215,7 +215,11 @@ func TestNeighborSolicitationWithSourceLinkLayerOption(t *testing.T) {
 			ns.SetTargetAddress(lladdr0)
 			opts := ns.Options()
 			copy(opts, test.optsBuf)
-			pkt.SetChecksum(header.ICMPv6Checksum(pkt, lladdr1, lladdr0, buffer.VectorisedView{}))
+			pkt.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+				Header: pkt,
+				Src:    lladdr1,
+				Dst:    lladdr0,
+			}))
 			payloadLength := hdr.UsedLength()
 			ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
 			ip.Encode(&header.IPv6Fields{
@@ -478,7 +482,11 @@ func TestNeighborSolicitationResponse(t *testing.T) {
 			ns.SetTargetAddress(nicAddr)
 			opts := ns.Options()
 			opts.Serialize(test.nsOpts)
-			pkt.SetChecksum(header.ICMPv6Checksum(pkt, test.nsSrc, test.nsDst, buffer.VectorisedView{}))
+			pkt.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+				Header: pkt,
+				Src:    test.nsSrc,
+				Dst:    test.nsDst,
+			}))
 			payloadLength := hdr.UsedLength()
 			ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
 			ip.Encode(&header.IPv6Fields{
@@ -554,7 +562,11 @@ func TestNeighborSolicitationResponse(t *testing.T) {
 				na.SetOverrideFlag(true)
 				na.SetTargetAddress(test.nsSrc)
 				na.Options().Serialize(ser)
-				pkt.SetChecksum(header.ICMPv6Checksum(pkt, test.nsSrc, nicAddr, buffer.VectorisedView{}))
+				pkt.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+					Header: pkt,
+					Src:    test.nsSrc,
+					Dst:    nicAddr,
+				}))
 				payloadLength := hdr.UsedLength()
 				ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
 				ip.Encode(&header.IPv6Fields{
@@ -657,7 +669,11 @@ func TestNeighborAdvertisementWithTargetLinkLayerOption(t *testing.T) {
 			ns.SetTargetAddress(lladdr1)
 			opts := ns.Options()
 			copy(opts, test.optsBuf)
-			pkt.SetChecksum(header.ICMPv6Checksum(pkt, lladdr1, lladdr0, buffer.VectorisedView{}))
+			pkt.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+				Header: pkt,
+				Src:    lladdr1,
+				Dst:    lladdr0,
+			}))
 			payloadLength := hdr.UsedLength()
 			ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
 			ip.Encode(&header.IPv6Fields{
@@ -874,7 +890,13 @@ func TestNDPValidation(t *testing.T) {
 						copy(icmp[typ.size:], typ.extraData)
 						icmp.SetType(typ.typ)
 						icmp.SetCode(test.code)
-						icmp.SetChecksum(header.ICMPv6Checksum(icmp[:typ.size], lladdr0, lladdr1, buffer.View(typ.extraData).ToVectorisedView()))
+						icmp.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+							Header:      icmp[:typ.size],
+							Src:         lladdr0,
+							Dst:         lladdr1,
+							PayloadCsum: header.Checksum(typ.extraData /* initial */, 0),
+							PayloadLen:  len(typ.extraData),
+						}))
 
 						// Rx count of the NDP message should initially be 0.
 						if got := typStat.Value(); got != 0 {
@@ -987,7 +1009,11 @@ func TestNeighborAdvertisementValidation(t *testing.T) {
 			na := header.NDPNeighborAdvert(pkt.MessageBody())
 			na.SetTargetAddress(lladdr1)
 			na.SetSolicitedFlag(test.solicitedFlag)
-			pkt.SetChecksum(header.ICMPv6Checksum(pkt, lladdr1, test.ipDstAddr, buffer.VectorisedView{}))
+			pkt.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+				Header: pkt,
+				Src:    lladdr1,
+				Dst:    test.ipDstAddr,
+			}))
 			payloadLength := hdr.UsedLength()
 			ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
 			ip.Encode(&header.IPv6Fields{
@@ -1182,7 +1208,11 @@ func TestRouterAdvertValidation(t *testing.T) {
 			pkt.SetCode(test.code)
 			copy(pkt.MessageBody(), test.ndpPayload)
 			payloadLength := hdr.UsedLength()
-			pkt.SetChecksum(header.ICMPv6Checksum(pkt, test.src, header.IPv6AllNodesMulticastAddress, buffer.VectorisedView{}))
+			pkt.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+				Header: pkt,
+				Src:    test.src,
+				Dst:    header.IPv6AllNodesMulticastAddress,
+			}))
 			ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
 			ip.Encode(&header.IPv6Fields{
 				PayloadLength:     uint16(payloadLength),