Deep copy dispatcher views.

When VectorisedViews were passed up the stack from packet_dispatchers, we were
passing a sub-slice of the dispatcher's views fields. The dispatchers then
immediately set those views to nil.

This wasn't caught before because every implementer copied the data in these
views before returning.

PiperOrigin-RevId: 277615351

pkg/tcpip/link/fdbased/endpoint_test.go

@@ -45,7 +45,7 @@ const (
 type packetInfo struct {
 	raddr      tcpip.LinkAddress
 	proto      tcpip.NetworkProtocolNumber
-	contents   buffer.View
+	contents   buffer.VectorisedView
 	linkHeader buffer.View
 }
 
@@ -94,7 +94,7 @@ func (c *context) cleanup() {
 }
 
 func (c *context) DeliverNetworkPacket(linkEP stack.LinkEndpoint, remote tcpip.LinkAddress, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, vv buffer.VectorisedView, linkHeader buffer.View) {
-	c.ch <- packetInfo{remote, protocol, vv.ToView(), linkHeader}
+	c.ch <- packetInfo{remote, protocol, vv, linkHeader}
 }
 
 func TestNoEthernetProperties(t *testing.T) {
@@ -319,13 +319,17 @@ func TestDeliverPacket(t *testing.T) {
 					want := packetInfo{
 						raddr:      raddr,
 						proto:      proto,
-						contents:   b,
+						contents:   buffer.View(b).ToVectorisedView(),
 						linkHeader: buffer.View(hdr),
 					}
 					if !eth {
 						want.proto = header.IPv4ProtocolNumber
 						want.raddr = ""
 					}
+					// want.contents will be a single view,
+					// so make pi do the same for the
+					// DeepEqual check.
+					pi.contents = pi.contents.ToView().ToVectorisedView()
 					if !reflect.DeepEqual(want, pi) {
 						t.Fatalf("Unexpected received packet: %+v, want %+v", pi, want)
 					}

pkg/tcpip/link/fdbased/packet_dispatchers.go

@@ -139,7 +139,7 @@ func (d *readVDispatcher) dispatch() (bool, *tcpip.Error) {
 	}
 
 	used := d.capViews(n, BufConfig)
-	vv := buffer.NewVectorisedView(n, d.views[:used])
+	vv := buffer.NewVectorisedView(n, append([]buffer.View(nil), d.views[:used]...))
 	vv.TrimFront(d.e.hdrSize)
 
 	d.e.dispatcher.DeliverNetworkPacket(d.e, remote, local, p, vv, buffer.View(eth))
@@ -293,7 +293,7 @@ func (d *recvMMsgDispatcher) dispatch() (bool, *tcpip.Error) {
 		}
 
 		used := d.capViews(k, int(n), BufConfig)
-		vv := buffer.NewVectorisedView(int(n), d.views[k][:used])
+		vv := buffer.NewVectorisedView(int(n), append([]buffer.View(nil), d.views[k][:used]...))
 		vv.TrimFront(d.e.hdrSize)
 		d.e.dispatcher.DeliverNetworkPacket(d.e, remote, local, p, vv, buffer.View(eth))
 

pkg/tcpip/stack/nic.go

@@ -762,7 +762,7 @@ func (n *NIC) DeliverNetworkPacket(linkEP LinkEndpoint, remote, local tcpip.Link
 	}
 	n.mu.RUnlock()
 	for _, ep := range packetEPs {
-		ep.HandlePacket(n.id, local, protocol, vv, linkHeader)
+		ep.HandlePacket(n.id, local, protocol, vv.Clone(nil), linkHeader)
 	}
 
 	if netProto.Number() == header.IPv4ProtocolNumber || netProto.Number() == header.IPv6ProtocolNumber {

pkg/tcpip/stack/registration.go

@@ -65,10 +65,14 @@ type TransportEndpoint interface {
 
 	// HandlePacket is called by the stack when new packets arrive to
 	// this transport endpoint.
+	//
+	// HandlePacket takes ownership of vv.
 	HandlePacket(r *Route, id TransportEndpointID, vv buffer.VectorisedView)
 
 	// HandleControlPacket is called by the stack when new control (e.g.,
 	// ICMP) packets arrive to this transport endpoint.
+	//
+	// HandleControlPacket takes ownership of vv.
 	HandleControlPacket(id TransportEndpointID, typ ControlType, extra uint32, vv buffer.VectorisedView)
 
 	// Close puts the endpoint in a closed state and frees all resources
@@ -94,6 +98,8 @@ type RawTransportEndpoint interface {
 	// HandlePacket is called by the stack when new packets arrive to
 	// this transport endpoint. The packet contains all data from the link
 	// layer up.
+	//
+	// HandlePacket takes ownership of packet and netHeader.
 	HandlePacket(r *Route, netHeader buffer.View, packet buffer.VectorisedView)
 }
 
@@ -110,6 +116,8 @@ type PacketEndpoint interface {
 	//
 	// linkHeader may have a length of 0, in which case the PacketEndpoint
 	// should construct its own ethernet header for applications.
+	//
+	// HandlePacket takes ownership of packet and linkHeader.
 	HandlePacket(nicid tcpip.NICID, addr tcpip.LinkAddress, netProto tcpip.NetworkProtocolNumber, packet buffer.VectorisedView, linkHeader buffer.View)
 }
 
@@ -160,10 +168,14 @@ type TransportDispatcher interface {
 	// DeliverTransportPacket delivers packets to the appropriate
 	// transport protocol endpoint. It also returns the network layer
 	// header for the enpoint to inspect or pass up the stack.
+	//
+	// DeliverTransportPacket takes ownership of vv and netHeader.
 	DeliverTransportPacket(r *Route, protocol tcpip.TransportProtocolNumber, netHeader buffer.View, vv buffer.VectorisedView)
 
 	// DeliverTransportControlPacket delivers control packets to the
 	// appropriate transport protocol endpoint.
+	//
+	// DeliverTransportControlPacket takes ownership of vv.
 	DeliverTransportControlPacket(local, remote tcpip.Address, net tcpip.NetworkProtocolNumber, trans tcpip.TransportProtocolNumber, typ ControlType, extra uint32, vv buffer.VectorisedView)
 }
 
@@ -237,6 +249,8 @@ type NetworkEndpoint interface {
 
 	// HandlePacket is called by the link layer when new packets arrive to
 	// this network endpoint.
+	//
+	// HandlePacket takes ownership of vv.
 	HandlePacket(r *Route, vv buffer.VectorisedView)
 
 	// Close is called when the endpoint is reomved from a stack.
@@ -282,6 +296,8 @@ type NetworkDispatcher interface {
 	// DeliverNetworkPacket finds the appropriate network protocol endpoint
 	// and hands the packet over for further processing. linkHeader may have
 	// length 0 when the caller does not have ethernet data.
+	//
+	// DeliverNetworkPacket takes ownership of vv and linkHeader.
 	DeliverNetworkPacket(linkEP LinkEndpoint, remote, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, vv buffer.VectorisedView, linkHeader buffer.View)
 }
 

pkg/tcpip/transport/icmp/endpoint.go

@@ -31,9 +31,6 @@ type icmpPacket struct {
 	senderAddress tcpip.FullAddress
 	data          buffer.VectorisedView `state:".(buffer.VectorisedView)"`
 	timestamp     int64
-	// views is used as buffer for data when its length is large
-	// enough to store a VectorisedView.
-	views [8]buffer.View `state:"nosave"`
 }
 
 type endpointState int
@@ -767,7 +764,7 @@ func (e *endpoint) HandlePacket(r *stack.Route, id stack.TransportEndpointID, vv
 		},
 	}
 
-	pkt.data = vv.Clone(pkt.views[:])
+	pkt.data = vv
 
 	e.rcvList.PushBack(pkt)
 	e.rcvBufSize += pkt.data.Size()

pkg/tcpip/transport/packet/endpoint.go

@@ -41,10 +41,6 @@ type packet struct {
 	// data holds the actual packet data, including any headers and
 	// payload.
 	data buffer.VectorisedView `state:".(buffer.VectorisedView)"`
-	// views is pre-allocated space to back data. As long as the packet is
-	// made up of fewer than 8 buffer.Views, no extra allocation is
-	// necessary to store packet data.
-	views [8]buffer.View `state:"nosave"`
 	// timestampNS is the unix time at which the packet was received.
 	timestampNS int64
 	// senderAddr is the network address of the sender.
@@ -310,7 +306,7 @@ func (ep *endpoint) HandlePacket(nicid tcpip.NICID, localAddr tcpip.LinkAddress,
 
 	if ep.cooked {
 		// Cooked packets can simply be queued.
-		packet.data = vv.Clone(packet.views[:])
+		packet.data = vv
 	} else {
 		// Raw packets need their ethernet headers prepended before
 		// queueing.
@@ -328,7 +324,7 @@ func (ep *endpoint) HandlePacket(nicid tcpip.NICID, localAddr tcpip.LinkAddress,
 		}
 		combinedVV := buffer.View(ethHeader).ToVectorisedView()
 		combinedVV.Append(vv)
-		packet.data = combinedVV.Clone(packet.views[:])
+		packet.data = combinedVV
 	}
 	packet.timestampNS = ep.stack.NowNanoseconds()
 

pkg/tcpip/transport/raw/endpoint.go

@@ -42,10 +42,6 @@ type rawPacket struct {
 	// data holds the actual packet data, including any headers and
 	// payload.
 	data buffer.VectorisedView `state:".(buffer.VectorisedView)"`
-	// views is pre-allocated space to back data. As long as the packet is
-	// made up of fewer than 8 buffer.Views, no extra allocation is
-	// necessary to store packet data.
-	views [8]buffer.View `state:"nosave"`
 	// timestampNS is the unix time at which the packet was received.
 	timestampNS int64
 	// senderAddr is the network address of the sender.
@@ -609,7 +605,7 @@ func (e *endpoint) HandlePacket(route *stack.Route, netHeader buffer.View, vv bu
 
 	combinedVV := netHeader.ToVectorisedView()
 	combinedVV.Append(vv)
-	pkt.data = combinedVV.Clone(pkt.views[:])
+	pkt.data = combinedVV
 	pkt.timestampNS = e.stack.NowNanoseconds()
 
 	e.rcvList.PushBack(pkt)

pkg/tcpip/transport/udp/endpoint.go

@@ -31,9 +31,6 @@ type udpPacket struct {
 	senderAddress tcpip.FullAddress
 	data          buffer.VectorisedView `state:".(buffer.VectorisedView)"`
 	timestamp     int64
-	// views is used as buffer for data when its length is large
-	// enough to store a VectorisedView.
-	views [8]buffer.View `state:"nosave"`
 }
 
 // EndpointState represents the state of a UDP endpoint.
@@ -1202,7 +1199,7 @@ func (e *endpoint) HandlePacket(r *stack.Route, id stack.TransportEndpointID, vv
 			Port: hdr.SourcePort(),
 		},
 	}
-	pkt.data = vv.Clone(pkt.views[:])
+	pkt.data = vv
 	e.rcvList.PushBack(pkt)
 	e.rcvBufSize += vv.Size()