Pass PacketBuffer as pointer.

Historically we've been passing PacketBuffer by shallow copying through out
the stack. Right now, this is only correct as the caller would not use
PacketBuffer after passing into the next layer in netstack.

With new buffer management effort in gVisor/netstack, PacketBuffer will
own a Buffer (to be added). Internally, both PacketBuffer and Buffer may
have pointers and shallow copying shouldn't be used.

Updates #2404.

PiperOrigin-RevId: 314610879

11 files changed, 93 insertions, 73 deletions

diff --git a/pkg/tcpip/network/arp/arp.go b/pkg/tcpip/network/arp/arp.go
index 9d0797af7..ea1acba83 100644
--- a/pkg/tcpip/network/arp/arp.go
+++ b/pkg/tcpip/network/arp/arp.go
@@ -80,7 +80,7 @@ func (e *endpoint) MaxHeaderLength() uint16 {
 
 func (e *endpoint) Close() {}
 
-func (e *endpoint) WritePacket(*stack.Route, *stack.GSO, stack.NetworkHeaderParams, stack.PacketBuffer) *tcpip.Error {
+func (e *endpoint) WritePacket(*stack.Route, *stack.GSO, stack.NetworkHeaderParams, *stack.PacketBuffer) *tcpip.Error {
 	return tcpip.ErrNotSupported
 }
 
@@ -94,11 +94,11 @@ func (e *endpoint) WritePackets(*stack.Route, *stack.GSO, stack.PacketBufferList
 	return 0, tcpip.ErrNotSupported
 }
 
-func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt stack.PacketBuffer) *tcpip.Error {
+func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBuffer) *tcpip.Error {
 	return tcpip.ErrNotSupported
 }
 
-func (e *endpoint) HandlePacket(r *stack.Route, pkt stack.PacketBuffer) {
+func (e *endpoint) HandlePacket(r *stack.Route, pkt *stack.PacketBuffer) {
 	v, ok := pkt.Data.PullUp(header.ARPSize)
 	if !ok {
 		return
@@ -122,7 +122,7 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt stack.PacketBuffer) {
 		copy(packet.ProtocolAddressSender(), h.ProtocolAddressTarget())
 		copy(packet.HardwareAddressTarget(), h.HardwareAddressSender())
 		copy(packet.ProtocolAddressTarget(), h.ProtocolAddressSender())
-		e.linkEP.WritePacket(r, nil /* gso */, ProtocolNumber, stack.PacketBuffer{
+		e.linkEP.WritePacket(r, nil /* gso */, ProtocolNumber, &stack.PacketBuffer{
 			Header: hdr,
 		})
 		fallthrough // also fill the cache from requests
@@ -177,7 +177,7 @@ func (*protocol) LinkAddressRequest(addr, localAddr tcpip.Address, linkEP stack.
 	copy(h.ProtocolAddressSender(), localAddr)
 	copy(h.ProtocolAddressTarget(), addr)
 
-	return linkEP.WritePacket(r, nil /* gso */, ProtocolNumber, stack.PacketBuffer{
+	return linkEP.WritePacket(r, nil /* gso */, ProtocolNumber, &stack.PacketBuffer{
 		Header: hdr,
 	})
 }
diff --git a/pkg/tcpip/network/arp/arp_test.go b/pkg/tcpip/network/arp/arp_test.go
index 1646d9cde..66e67429c 100644
--- a/pkg/tcpip/network/arp/arp_test.go
+++ b/pkg/tcpip/network/arp/arp_test.go
@@ -103,7 +103,7 @@ func TestDirectRequest(t *testing.T) {
 
 	inject := func(addr tcpip.Address) {
 		copy(h.ProtocolAddressTarget(), addr)
-		c.linkEP.InjectInbound(arp.ProtocolNumber, stack.PacketBuffer{
+		c.linkEP.InjectInbound(arp.ProtocolNumber, &stack.PacketBuffer{
 			Data: v.ToVectorisedView(),
 		})
 	}
diff --git a/pkg/tcpip/network/ip_test.go b/pkg/tcpip/network/ip_test.go
index 4c20301c6..d9b62f2db 100644
--- a/pkg/tcpip/network/ip_test.go
+++ b/pkg/tcpip/network/ip_test.go
@@ -96,7 +96,7 @@ func (t *testObject) checkValues(protocol tcpip.TransportProtocolNumber, vv buff
 // DeliverTransportPacket is called by network endpoints after parsing incoming
 // packets. This is used by the test object to verify that the results of the
 // parsing are expected.
-func (t *testObject) DeliverTransportPacket(r *stack.Route, protocol tcpip.TransportProtocolNumber, pkt stack.PacketBuffer) {
+func (t *testObject) DeliverTransportPacket(r *stack.Route, protocol tcpip.TransportProtocolNumber, pkt *stack.PacketBuffer) {
 	t.checkValues(protocol, pkt.Data, r.RemoteAddress, r.LocalAddress)
 	t.dataCalls++
 }
@@ -104,7 +104,7 @@ func (t *testObject) DeliverTransportPacket(r *stack.Route, protocol tcpip.Trans
 // DeliverTransportControlPacket is called by network endpoints after parsing
 // incoming control (ICMP) packets. This is used by the test object to verify
 // that the results of the parsing are expected.
-func (t *testObject) DeliverTransportControlPacket(local, remote tcpip.Address, net tcpip.NetworkProtocolNumber, trans tcpip.TransportProtocolNumber, typ stack.ControlType, extra uint32, pkt stack.PacketBuffer) {
+func (t *testObject) DeliverTransportControlPacket(local, remote tcpip.Address, net tcpip.NetworkProtocolNumber, trans tcpip.TransportProtocolNumber, typ stack.ControlType, extra uint32, pkt *stack.PacketBuffer) {
 	t.checkValues(trans, pkt.Data, remote, local)
 	if typ != t.typ {
 		t.t.Errorf("typ = %v, want %v", typ, t.typ)
@@ -150,7 +150,7 @@ func (*testObject) Wait() {}
 // WritePacket is called by network endpoints after producing a packet and
 // writing it to the link endpoint. This is used by the test object to verify
 // that the produced packet is as expected.
-func (t *testObject) WritePacket(_ *stack.Route, _ *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt stack.PacketBuffer) *tcpip.Error {
+func (t *testObject) WritePacket(_ *stack.Route, _ *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) *tcpip.Error {
 	var prot tcpip.TransportProtocolNumber
 	var srcAddr tcpip.Address
 	var dstAddr tcpip.Address
@@ -246,7 +246,11 @@ func TestIPv4Send(t *testing.T) {
 	if err != nil {
 		t.Fatalf("could not find route: %v", err)
 	}
-	if err := ep.WritePacket(&r, nil /* gso */, stack.NetworkHeaderParams{Protocol: 123, TTL: 123, TOS: stack.DefaultTOS}, stack.PacketBuffer{
+	if err := ep.WritePacket(&r, nil /* gso */, stack.NetworkHeaderParams{
+		Protocol: 123,
+		TTL:      123,
+		TOS:      stack.DefaultTOS,
+	}, &stack.PacketBuffer{
 		Header: hdr,
 		Data:   payload.ToVectorisedView(),
 	}); err != nil {
@@ -289,7 +293,7 @@ func TestIPv4Receive(t *testing.T) {
 	if err != nil {
 		t.Fatalf("could not find route: %v", err)
 	}
-	ep.HandlePacket(&r, stack.PacketBuffer{
+	ep.HandlePacket(&r, &stack.PacketBuffer{
 		Data: view.ToVectorisedView(),
 	})
 	if o.dataCalls != 1 {
@@ -379,7 +383,7 @@ func TestIPv4ReceiveControl(t *testing.T) {
 			o.extra = c.expectedExtra
 
 			vv := view[:len(view)-c.trunc].ToVectorisedView()
-			ep.HandlePacket(&r, stack.PacketBuffer{
+			ep.HandlePacket(&r, &stack.PacketBuffer{
 				Data: vv,
 			})
 			if want := c.expectedCount; o.controlCalls != want {
@@ -444,7 +448,7 @@ func TestIPv4FragmentationReceive(t *testing.T) {
 	}
 
 	// Send first segment.
-	ep.HandlePacket(&r, stack.PacketBuffer{
+	ep.HandlePacket(&r, &stack.PacketBuffer{
 		Data: frag1.ToVectorisedView(),
 	})
 	if o.dataCalls != 0 {
@@ -452,7 +456,7 @@ func TestIPv4FragmentationReceive(t *testing.T) {
 	}
 
 	// Send second segment.
-	ep.HandlePacket(&r, stack.PacketBuffer{
+	ep.HandlePacket(&r, &stack.PacketBuffer{
 		Data: frag2.ToVectorisedView(),
 	})
 	if o.dataCalls != 1 {
@@ -487,7 +491,11 @@ func TestIPv6Send(t *testing.T) {
 	if err != nil {
 		t.Fatalf("could not find route: %v", err)
 	}
-	if err := ep.WritePacket(&r, nil /* gso */, stack.NetworkHeaderParams{Protocol: 123, TTL: 123, TOS: stack.DefaultTOS}, stack.PacketBuffer{
+	if err := ep.WritePacket(&r, nil /* gso */, stack.NetworkHeaderParams{
+		Protocol: 123,
+		TTL:      123,
+		TOS:      stack.DefaultTOS,
+	}, &stack.PacketBuffer{
 		Header: hdr,
 		Data:   payload.ToVectorisedView(),
 	}); err != nil {
@@ -530,7 +538,7 @@ func TestIPv6Receive(t *testing.T) {
 		t.Fatalf("could not find route: %v", err)
 	}
 
-	ep.HandlePacket(&r, stack.PacketBuffer{
+	ep.HandlePacket(&r, &stack.PacketBuffer{
 		Data: view.ToVectorisedView(),
 	})
 	if o.dataCalls != 1 {
@@ -644,7 +652,7 @@ func TestIPv6ReceiveControl(t *testing.T) {
 			// Set ICMPv6 checksum.
 			icmp.SetChecksum(header.ICMPv6Checksum(icmp, outerSrcAddr, localIpv6Addr, buffer.VectorisedView{}))
 
-			ep.HandlePacket(&r, stack.PacketBuffer{
+			ep.HandlePacket(&r, &stack.PacketBuffer{
 				Data: view[:len(view)-c.trunc].ToVectorisedView(),
 			})
 			if want := c.expectedCount; o.controlCalls != want {
diff --git a/pkg/tcpip/network/ipv4/icmp.go b/pkg/tcpip/network/ipv4/icmp.go
index 4cbefe5ab..d1c3ae835 100644
--- a/pkg/tcpip/network/ipv4/icmp.go
+++ b/pkg/tcpip/network/ipv4/icmp.go
@@ -24,7 +24,7 @@ import (
 // the original packet that caused the ICMP one to be sent. This information is
 // used to find out which transport endpoint must be notified about the ICMP
 // packet.
-func (e *endpoint) handleControl(typ stack.ControlType, extra uint32, pkt stack.PacketBuffer) {
+func (e *endpoint) handleControl(typ stack.ControlType, extra uint32, pkt *stack.PacketBuffer) {
 	h, ok := pkt.Data.PullUp(header.IPv4MinimumSize)
 	if !ok {
 		return
@@ -56,7 +56,7 @@ func (e *endpoint) handleControl(typ stack.ControlType, extra uint32, pkt stack.
 	e.dispatcher.DeliverTransportControlPacket(e.id.LocalAddress, hdr.DestinationAddress(), ProtocolNumber, p, typ, extra, pkt)
 }
 
-func (e *endpoint) handleICMP(r *stack.Route, pkt stack.PacketBuffer) {
+func (e *endpoint) handleICMP(r *stack.Route, pkt *stack.PacketBuffer) {
 	stats := r.Stats()
 	received := stats.ICMP.V4PacketsReceived
 	v, ok := pkt.Data.PullUp(header.ICMPv4MinimumSize)
@@ -88,7 +88,7 @@ func (e *endpoint) handleICMP(r *stack.Route, pkt stack.PacketBuffer) {
 
 		// It's possible that a raw socket expects to receive this.
 		h.SetChecksum(wantChecksum)
-		e.dispatcher.DeliverTransportPacket(r, header.ICMPv4ProtocolNumber, stack.PacketBuffer{
+		e.dispatcher.DeliverTransportPacket(r, header.ICMPv4ProtocolNumber, &stack.PacketBuffer{
 			Data:          pkt.Data.Clone(nil),
 			NetworkHeader: append(buffer.View(nil), pkt.NetworkHeader...),
 		})
@@ -102,7 +102,11 @@ func (e *endpoint) handleICMP(r *stack.Route, pkt stack.PacketBuffer) {
 		pkt.SetChecksum(0)
 		pkt.SetChecksum(^header.Checksum(pkt, header.ChecksumVV(vv, 0)))
 		sent := stats.ICMP.V4PacketsSent
-		if err := r.WritePacket(nil /* gso */, stack.NetworkHeaderParams{Protocol: header.ICMPv4ProtocolNumber, TTL: r.DefaultTTL(), TOS: stack.DefaultTOS}, stack.PacketBuffer{
+		if err := r.WritePacket(nil /* gso */, stack.NetworkHeaderParams{
+			Protocol: header.ICMPv4ProtocolNumber,
+			TTL:      r.DefaultTTL(),
+			TOS:      stack.DefaultTOS,
+		}, &stack.PacketBuffer{
 			Header:          hdr,
 			Data:            vv,
 			TransportHeader: buffer.View(pkt),
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index 64046cbbf..9cd7592f4 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -129,7 +129,7 @@ func (e *endpoint) NetworkProtocolNumber() tcpip.NetworkProtocolNumber {
 // packet's stated length matches the length of the header+payload. mtu
 // includes the IP header and options. This does not support the DontFragment
 // IP flag.
-func (e *endpoint) writePacketFragments(r *stack.Route, gso *stack.GSO, mtu int, pkt stack.PacketBuffer) *tcpip.Error {
+func (e *endpoint) writePacketFragments(r *stack.Route, gso *stack.GSO, mtu int, pkt *stack.PacketBuffer) *tcpip.Error {
 	// This packet is too big, it needs to be fragmented.
 	ip := header.IPv4(pkt.Header.View())
 	flags := ip.Flags()
@@ -169,7 +169,7 @@ func (e *endpoint) writePacketFragments(r *stack.Route, gso *stack.GSO, mtu int,
 		if i > 0 {
 			newPayload := pkt.Data.Clone(nil)
 			newPayload.CapLength(innerMTU)
-			if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, stack.PacketBuffer{
+			if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, &stack.PacketBuffer{
 				Header:        pkt.Header,
 				Data:          newPayload,
 				NetworkHeader: buffer.View(h),
@@ -188,7 +188,7 @@ func (e *endpoint) writePacketFragments(r *stack.Route, gso *stack.GSO, mtu int,
 			newPayload := pkt.Data.Clone(nil)
 			newPayloadLength := outerMTU - pkt.Header.UsedLength()
 			newPayload.CapLength(newPayloadLength)
-			if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, stack.PacketBuffer{
+			if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, &stack.PacketBuffer{
 				Header:        pkt.Header,
 				Data:          newPayload,
 				NetworkHeader: buffer.View(h),
@@ -202,7 +202,7 @@ func (e *endpoint) writePacketFragments(r *stack.Route, gso *stack.GSO, mtu int,
 			startOfHdr := pkt.Header
 			startOfHdr.TrimBack(pkt.Header.UsedLength() - outerMTU)
 			emptyVV := buffer.NewVectorisedView(0, []buffer.View{})
-			if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, stack.PacketBuffer{
+			if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, &stack.PacketBuffer{
 				Header:        startOfHdr,
 				Data:          emptyVV,
 				NetworkHeader: buffer.View(h),
@@ -245,7 +245,7 @@ func (e *endpoint) addIPHeader(r *stack.Route, hdr *buffer.Prependable, payloadS
 }
 
 // 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, gso *stack.GSO, params stack.NetworkHeaderParams, pkt *stack.PacketBuffer) *tcpip.Error {
 	ip := e.addIPHeader(r, &pkt.Header, pkt.Data.Size(), params)
 	pkt.NetworkHeader = buffer.View(ip)
 
@@ -253,7 +253,7 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
 	// iptables filtering. All packets that reach here are locally
 	// generated.
 	ipt := e.stack.IPTables()
-	if ok := ipt.Check(stack.Output, &pkt, gso, r, "", nicName); !ok {
+	if ok := ipt.Check(stack.Output, pkt, gso, r, "", nicName); !ok {
 		// iptables is telling us to drop the packet.
 		return nil
 	}
@@ -271,9 +271,9 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
 			views := make([]buffer.View, 1, 1+len(pkt.Data.Views()))
 			views[0] = pkt.Header.View()
 			views = append(views, pkt.Data.Views()...)
-			packet := stack.PacketBuffer{
-				Data: buffer.NewVectorisedView(len(views[0])+pkt.Data.Size(), views)}
-			ep.HandlePacket(&route, packet)
+			ep.HandlePacket(&route, &stack.PacketBuffer{
+				Data: buffer.NewVectorisedView(len(views[0])+pkt.Data.Size(), views),
+			})
 			return nil
 		}
 	}
@@ -286,7 +286,7 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
 		views = append(views, pkt.Data.Views()...)
 		loopedR := r.MakeLoopedRoute()
 
-		e.HandlePacket(&loopedR, stack.PacketBuffer{
+		e.HandlePacket(&loopedR, &stack.PacketBuffer{
 			Data: buffer.NewVectorisedView(len(views[0])+pkt.Data.Size(), views),
 		})
 
@@ -351,14 +351,14 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 				views := make([]buffer.View, 1, 1+len(pkt.Data.Views()))
 				views[0] = pkt.Header.View()
 				views = append(views, pkt.Data.Views()...)
-				packet := stack.PacketBuffer{
-					Data: buffer.NewVectorisedView(len(views[0])+pkt.Data.Size(), views)}
-				ep.HandlePacket(&route, packet)
+				ep.HandlePacket(&route, &stack.PacketBuffer{
+					Data: buffer.NewVectorisedView(len(views[0])+pkt.Data.Size(), views),
+				})
 				n++
 				continue
 			}
 		}
-		if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, *pkt); err != nil {
+		if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, pkt); err != nil {
 			r.Stats().IP.PacketsSent.IncrementBy(uint64(n))
 			return n, err
 		}
@@ -370,7 +370,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 
 // WriteHeaderIncludedPacket writes a packet already containing a network
 // header through the given route.
-func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt stack.PacketBuffer) *tcpip.Error {
+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.IPv4MinimumSize)
@@ -426,7 +426,7 @@ func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt stack.PacketBuf
 
 // HandlePacket is called by the link layer when new ipv4 packets arrive for
 // this endpoint.
-func (e *endpoint) HandlePacket(r *stack.Route, pkt stack.PacketBuffer) {
+func (e *endpoint) HandlePacket(r *stack.Route, pkt *stack.PacketBuffer) {
 	headerView, ok := pkt.Data.PullUp(header.IPv4MinimumSize)
 	if !ok {
 		r.Stats().IP.MalformedPacketsReceived.Increment()
@@ -447,7 +447,7 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt stack.PacketBuffer) {
 	// iptables filtering. All packets that reach here are intended for
 	// this machine and will not be forwarded.
 	ipt := e.stack.IPTables()
-	if ok := ipt.Check(stack.Input, &pkt, nil, nil, "", ""); !ok {
+	if ok := ipt.Check(stack.Input, pkt, nil, nil, "", ""); !ok {
 		// iptables is telling us to drop the packet.
 		return
 	}
diff --git a/pkg/tcpip/network/ipv4/ipv4_test.go b/pkg/tcpip/network/ipv4/ipv4_test.go
index 36035c820..c208ebd99 100644
--- a/pkg/tcpip/network/ipv4/ipv4_test.go
+++ b/pkg/tcpip/network/ipv4/ipv4_test.go
@@ -114,7 +114,7 @@ func makeHdrAndPayload(hdrLength int, extraLength int, viewSizes []int) (buffer.
 
 // comparePayloads compared the contents of all the packets against the contents
 // of the source packet.
-func compareFragments(t *testing.T, packets []stack.PacketBuffer, sourcePacketInfo stack.PacketBuffer, mtu uint32) {
+func compareFragments(t *testing.T, packets []*stack.PacketBuffer, sourcePacketInfo *stack.PacketBuffer, mtu uint32) {
 	t.Helper()
 	// Make a complete array of the sourcePacketInfo packet.
 	source := header.IPv4(packets[0].Header.View()[:header.IPv4MinimumSize])
@@ -174,7 +174,7 @@ func compareFragments(t *testing.T, packets []stack.PacketBuffer, sourcePacketIn
 
 type errorChannel struct {
 	*channel.Endpoint
-	Ch                    chan stack.PacketBuffer
+	Ch                    chan *stack.PacketBuffer
 	packetCollectorErrors []*tcpip.Error
 }
 
@@ -184,7 +184,7 @@ type errorChannel struct {
 func newErrorChannel(size int, mtu uint32, linkAddr tcpip.LinkAddress, packetCollectorErrors []*tcpip.Error) *errorChannel {
 	return &errorChannel{
 		Endpoint:              channel.New(size, mtu, linkAddr),
-		Ch:                    make(chan stack.PacketBuffer, size),
+		Ch:                    make(chan *stack.PacketBuffer, size),
 		packetCollectorErrors: packetCollectorErrors,
 	}
 }
@@ -203,7 +203,7 @@ func (e *errorChannel) Drain() int {
 }
 
 // WritePacket stores outbound packets into the channel.
-func (e *errorChannel) WritePacket(r *stack.Route, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt stack.PacketBuffer) *tcpip.Error {
+func (e *errorChannel) WritePacket(r *stack.Route, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) *tcpip.Error {
 	select {
 	case e.Ch <- pkt:
 	default:
@@ -282,13 +282,17 @@ func TestFragmentation(t *testing.T) {
 	for _, ft := range fragTests {
 		t.Run(ft.description, func(t *testing.T) {
 			hdr, payload := makeHdrAndPayload(ft.hdrLength, ft.extraLength, ft.payloadViewsSizes)
-			source := stack.PacketBuffer{
+			source := &stack.PacketBuffer{
 				Header: hdr,
 				// Save the source payload because WritePacket will modify it.
 				Data: payload.Clone(nil),
 			}
 			c := buildContext(t, nil, ft.mtu)
-			err := c.Route.WritePacket(ft.gso, stack.NetworkHeaderParams{Protocol: tcp.ProtocolNumber, TTL: 42, TOS: stack.DefaultTOS}, stack.PacketBuffer{
+			err := c.Route.WritePacket(ft.gso, stack.NetworkHeaderParams{
+				Protocol: tcp.ProtocolNumber,
+				TTL:      42,
+				TOS:      stack.DefaultTOS,
+			}, &stack.PacketBuffer{
 				Header: hdr,
 				Data:   payload,
 			})
@@ -296,7 +300,7 @@ func TestFragmentation(t *testing.T) {
 				t.Errorf("err got %v, want %v", err, nil)
 			}
 
-			var results []stack.PacketBuffer
+			var results []*stack.PacketBuffer
 		L:
 			for {
 				select {
@@ -338,7 +342,11 @@ func TestFragmentationErrors(t *testing.T) {
 		t.Run(ft.description, func(t *testing.T) {
 			hdr, payload := makeHdrAndPayload(ft.hdrLength, header.IPv4MinimumSize, ft.payloadViewsSizes)
 			c := buildContext(t, ft.packetCollectorErrors, ft.mtu)
-			err := c.Route.WritePacket(&stack.GSO{}, stack.NetworkHeaderParams{Protocol: tcp.ProtocolNumber, TTL: 42, TOS: stack.DefaultTOS}, stack.PacketBuffer{
+			err := c.Route.WritePacket(&stack.GSO{}, stack.NetworkHeaderParams{
+				Protocol: tcp.ProtocolNumber,
+				TTL:      42,
+				TOS:      stack.DefaultTOS,
+			}, &stack.PacketBuffer{
 				Header: hdr,
 				Data:   payload,
 			})
@@ -460,7 +468,7 @@ func TestInvalidFragments(t *testing.T) {
 			s.CreateNIC(nicID, sniffer.New(ep))
 
 			for _, pkt := range tc.packets {
-				ep.InjectLinkAddr(header.IPv4ProtocolNumber, remoteLinkAddr, stack.PacketBuffer{
+				ep.InjectLinkAddr(header.IPv4ProtocolNumber, remoteLinkAddr, &stack.PacketBuffer{
 					Data: buffer.NewVectorisedView(len(pkt), []buffer.View{pkt}),
 				})
 			}
@@ -698,7 +706,7 @@ func TestReceiveFragments(t *testing.T) {
 				vv := hdr.View().ToVectorisedView()
 				vv.AppendView(frag.payload)
 
-				e.InjectInbound(header.IPv4ProtocolNumber, stack.PacketBuffer{
+				e.InjectInbound(header.IPv4ProtocolNumber, &stack.PacketBuffer{
 					Data: vv,
 				})
 			}
diff --git a/pkg/tcpip/network/ipv6/icmp.go b/pkg/tcpip/network/ipv6/icmp.go
index bdf3a0d25..b62fb1de6 100644
--- a/pkg/tcpip/network/ipv6/icmp.go
+++ b/pkg/tcpip/network/ipv6/icmp.go
@@ -27,7 +27,7 @@ import (
 // the original packet that caused the ICMP one to be sent. This information is
 // used to find out which transport endpoint must be notified about the ICMP
 // packet.
-func (e *endpoint) handleControl(typ stack.ControlType, extra uint32, pkt stack.PacketBuffer) {
+func (e *endpoint) handleControl(typ stack.ControlType, extra uint32, pkt *stack.PacketBuffer) {
 	h, ok := pkt.Data.PullUp(header.IPv6MinimumSize)
 	if !ok {
 		return
@@ -70,7 +70,7 @@ func (e *endpoint) handleControl(typ stack.ControlType, extra uint32, pkt stack.
 	e.dispatcher.DeliverTransportControlPacket(e.id.LocalAddress, hdr.DestinationAddress(), ProtocolNumber, p, typ, extra, pkt)
 }
 
-func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, pkt stack.PacketBuffer, hasFragmentHeader bool) {
+func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, pkt *stack.PacketBuffer, hasFragmentHeader bool) {
 	stats := r.Stats().ICMP
 	sent := stats.V6PacketsSent
 	received := stats.V6PacketsReceived
@@ -288,7 +288,7 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, pkt stack.P
 		//
 		// 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}, stack.PacketBuffer{
+		if err := r.WritePacket(nil /* gso */, stack.NetworkHeaderParams{Protocol: header.ICMPv6ProtocolNumber, TTL: header.NDPHopLimit, TOS: stack.DefaultTOS}, &stack.PacketBuffer{
 			Header: hdr,
 		}); err != nil {
 			sent.Dropped.Increment()
@@ -390,7 +390,7 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, pkt stack.P
 		copy(packet, icmpHdr)
 		packet.SetType(header.ICMPv6EchoReply)
 		packet.SetChecksum(header.ICMPv6Checksum(packet, r.LocalAddress, r.RemoteAddress, pkt.Data))
-		if err := r.WritePacket(nil /* gso */, stack.NetworkHeaderParams{Protocol: header.ICMPv6ProtocolNumber, TTL: r.DefaultTTL(), TOS: stack.DefaultTOS}, stack.PacketBuffer{
+		if err := r.WritePacket(nil /* gso */, stack.NetworkHeaderParams{Protocol: header.ICMPv6ProtocolNumber, TTL: r.DefaultTTL(), TOS: stack.DefaultTOS}, &stack.PacketBuffer{
 			Header: hdr,
 			Data:   pkt.Data,
 		}); err != nil {
@@ -532,7 +532,7 @@ func (*protocol) LinkAddressRequest(addr, localAddr tcpip.Address, linkEP stack.
 	})
 
 	// TODO(stijlist): count this in ICMP stats.
-	return linkEP.WritePacket(r, nil /* gso */, ProtocolNumber, stack.PacketBuffer{
+	return linkEP.WritePacket(r, nil /* gso */, ProtocolNumber, &stack.PacketBuffer{
 		Header: hdr,
 	})
 }
diff --git a/pkg/tcpip/network/ipv6/icmp_test.go b/pkg/tcpip/network/ipv6/icmp_test.go
index d412ff688..a720f626f 100644
--- a/pkg/tcpip/network/ipv6/icmp_test.go
+++ b/pkg/tcpip/network/ipv6/icmp_test.go
@@ -57,7 +57,7 @@ func (*stubLinkEndpoint) LinkAddress() tcpip.LinkAddress {
 	return ""
 }
 
-func (*stubLinkEndpoint) WritePacket(*stack.Route, *stack.GSO, tcpip.NetworkProtocolNumber, stack.PacketBuffer) *tcpip.Error {
+func (*stubLinkEndpoint) WritePacket(*stack.Route, *stack.GSO, tcpip.NetworkProtocolNumber, *stack.PacketBuffer) *tcpip.Error {
 	return nil
 }
 
@@ -67,7 +67,7 @@ type stubDispatcher struct {
 	stack.TransportDispatcher
 }
 
-func (*stubDispatcher) DeliverTransportPacket(*stack.Route, tcpip.TransportProtocolNumber, stack.PacketBuffer) {
+func (*stubDispatcher) DeliverTransportPacket(*stack.Route, tcpip.TransportProtocolNumber, *stack.PacketBuffer) {
 }
 
 type stubLinkAddressCache struct {
@@ -189,7 +189,7 @@ func TestICMPCounts(t *testing.T) {
 			SrcAddr:       r.LocalAddress,
 			DstAddr:       r.RemoteAddress,
 		})
-		ep.HandlePacket(&r, stack.PacketBuffer{
+		ep.HandlePacket(&r, &stack.PacketBuffer{
 			Data: hdr.View().ToVectorisedView(),
 		})
 	}
@@ -328,7 +328,7 @@ func routeICMPv6Packet(t *testing.T, args routeArgs, fn func(*testing.T, header.
 		views := []buffer.View{pi.Pkt.Header.View(), pi.Pkt.Data.ToView()}
 		size := pi.Pkt.Header.UsedLength() + pi.Pkt.Data.Size()
 		vv := buffer.NewVectorisedView(size, views)
-		args.dst.InjectLinkAddr(pi.Proto, args.dst.LinkAddress(), stack.PacketBuffer{
+		args.dst.InjectLinkAddr(pi.Proto, args.dst.LinkAddress(), &stack.PacketBuffer{
 			Data: vv,
 		})
 	}
@@ -563,7 +563,7 @@ func TestICMPChecksumValidationSimple(t *testing.T) {
 					SrcAddr:       lladdr1,
 					DstAddr:       lladdr0,
 				})
-				e.InjectInbound(ProtocolNumber, stack.PacketBuffer{
+				e.InjectInbound(ProtocolNumber, &stack.PacketBuffer{
 					Data: hdr.View().ToVectorisedView(),
 				})
 			}
@@ -740,7 +740,7 @@ func TestICMPChecksumValidationWithPayload(t *testing.T) {
 					SrcAddr:       lladdr1,
 					DstAddr:       lladdr0,
 				})
-				e.InjectInbound(ProtocolNumber, stack.PacketBuffer{
+				e.InjectInbound(ProtocolNumber, &stack.PacketBuffer{
 					Data: hdr.View().ToVectorisedView(),
 				})
 			}
@@ -918,7 +918,7 @@ func TestICMPChecksumValidationWithPayloadMultipleViews(t *testing.T) {
 					SrcAddr:       lladdr1,
 					DstAddr:       lladdr0,
 				})
-				e.InjectInbound(ProtocolNumber, stack.PacketBuffer{
+				e.InjectInbound(ProtocolNumber, &stack.PacketBuffer{
 					Data: buffer.NewVectorisedView(header.IPv6MinimumSize+size+payloadSize, []buffer.View{hdr.View(), payload}),
 				})
 			}
diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go
index daf1fcbc6..0d94ad122 100644
--- a/pkg/tcpip/network/ipv6/ipv6.go
+++ b/pkg/tcpip/network/ipv6/ipv6.go
@@ -116,7 +116,7 @@ func (e *endpoint) addIPHeader(r *stack.Route, hdr *buffer.Prependable, payloadS
 }
 
 // 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, gso *stack.GSO, params stack.NetworkHeaderParams, pkt *stack.PacketBuffer) *tcpip.Error {
 	ip := e.addIPHeader(r, &pkt.Header, pkt.Data.Size(), params)
 	pkt.NetworkHeader = buffer.View(ip)
 
@@ -128,7 +128,7 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
 		views = append(views, pkt.Data.Views()...)
 		loopedR := r.MakeLoopedRoute()
 
-		e.HandlePacket(&loopedR, stack.PacketBuffer{
+		e.HandlePacket(&loopedR, &stack.PacketBuffer{
 			Data: buffer.NewVectorisedView(len(views[0])+pkt.Data.Size(), views),
 		})
 
@@ -163,14 +163,14 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 
 // WriteHeaderIncludedPacker implements stack.NetworkEndpoint. It is not yet
 // supported by IPv6.
-func (*endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt stack.PacketBuffer) *tcpip.Error {
+func (*endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBuffer) *tcpip.Error {
 	// TODO(b/146666412): Support IPv6 header-included packets.
 	return tcpip.ErrNotSupported
 }
 
 // HandlePacket is called by the link layer when new ipv6 packets arrive for
 // this endpoint.
-func (e *endpoint) HandlePacket(r *stack.Route, pkt stack.PacketBuffer) {
+func (e *endpoint) HandlePacket(r *stack.Route, pkt *stack.PacketBuffer) {
 	headerView, ok := pkt.Data.PullUp(header.IPv6MinimumSize)
 	if !ok {
 		r.Stats().IP.MalformedPacketsReceived.Increment()
diff --git a/pkg/tcpip/network/ipv6/ipv6_test.go b/pkg/tcpip/network/ipv6/ipv6_test.go
index 841a0cb7a..213ff64f2 100644
--- a/pkg/tcpip/network/ipv6/ipv6_test.go
+++ b/pkg/tcpip/network/ipv6/ipv6_test.go
@@ -65,7 +65,7 @@ func testReceiveICMP(t *testing.T, s *stack.Stack, e *channel.Endpoint, src, dst
 		DstAddr:       dst,
 	})
 
-	e.InjectInbound(ProtocolNumber, stack.PacketBuffer{
+	e.InjectInbound(ProtocolNumber, &stack.PacketBuffer{
 		Data: hdr.View().ToVectorisedView(),
 	})
 
@@ -123,7 +123,7 @@ func testReceiveUDP(t *testing.T, s *stack.Stack, e *channel.Endpoint, src, dst
 		DstAddr:       dst,
 	})
 
-	e.InjectInbound(ProtocolNumber, stack.PacketBuffer{
+	e.InjectInbound(ProtocolNumber, &stack.PacketBuffer{
 		Data: hdr.View().ToVectorisedView(),
 	})
 
@@ -637,7 +637,7 @@ func TestReceiveIPv6ExtHdrs(t *testing.T) {
 				DstAddr:       addr2,
 			})
 
-			e.InjectInbound(ProtocolNumber, stack.PacketBuffer{
+			e.InjectInbound(ProtocolNumber, &stack.PacketBuffer{
 				Data: hdr.View().ToVectorisedView(),
 			})
 
@@ -1238,7 +1238,7 @@ func TestReceiveIPv6Fragments(t *testing.T) {
 				vv := hdr.View().ToVectorisedView()
 				vv.Append(f.data)
 
-				e.InjectInbound(ProtocolNumber, stack.PacketBuffer{
+				e.InjectInbound(ProtocolNumber, &stack.PacketBuffer{
 					Data: vv,
 				})
 			}
diff --git a/pkg/tcpip/network/ipv6/ndp_test.go b/pkg/tcpip/network/ipv6/ndp_test.go
index 12b70f7e9..3c141b91b 100644
--- a/pkg/tcpip/network/ipv6/ndp_test.go
+++ b/pkg/tcpip/network/ipv6/ndp_test.go
@@ -136,7 +136,7 @@ func TestNeighorSolicitationWithSourceLinkLayerOption(t *testing.T) {
 				t.Fatalf("got invalid = %d, want = 0", got)
 			}
 
-			e.InjectInbound(ProtocolNumber, stack.PacketBuffer{
+			e.InjectInbound(ProtocolNumber, &stack.PacketBuffer{
 				Data: hdr.View().ToVectorisedView(),
 			})
 
@@ -380,7 +380,7 @@ func TestNeighorSolicitationResponse(t *testing.T) {
 				t.Fatalf("got invalid = %d, want = 0", got)
 			}
 
-			e.InjectLinkAddr(ProtocolNumber, test.nsSrcLinkAddr, stack.PacketBuffer{
+			e.InjectLinkAddr(ProtocolNumber, test.nsSrcLinkAddr, &stack.PacketBuffer{
 				Data: hdr.View().ToVectorisedView(),
 			})
 
@@ -497,7 +497,7 @@ func TestNeighorAdvertisementWithTargetLinkLayerOption(t *testing.T) {
 				t.Fatalf("got invalid = %d, want = 0", got)
 			}
 
-			e.InjectInbound(ProtocolNumber, stack.PacketBuffer{
+			e.InjectInbound(ProtocolNumber, &stack.PacketBuffer{
 				Data: hdr.View().ToVectorisedView(),
 			})
 
@@ -568,7 +568,7 @@ func TestNDPValidation(t *testing.T) {
 			SrcAddr:       r.LocalAddress,
 			DstAddr:       r.RemoteAddress,
 		})
-		ep.HandlePacket(r, stack.PacketBuffer{
+		ep.HandlePacket(r, &stack.PacketBuffer{
 			Data: hdr.View().ToVectorisedView(),
 		})
 	}
@@ -884,7 +884,7 @@ func TestRouterAdvertValidation(t *testing.T) {
 				t.Fatalf("got rxRA = %d, want = 0", got)
 			}
 
-			e.InjectInbound(header.IPv6ProtocolNumber, stack.PacketBuffer{
+			e.InjectInbound(header.IPv6ProtocolNumber, &stack.PacketBuffer{
 				Data: hdr.View().ToVectorisedView(),
 			})