2 files changed, 46 insertions, 8 deletions
diff --git a/pkg/tcpip/transport/packet/endpoint.go b/pkg/tcpip/transport/packet/endpoint.go
index 8e7bb6c6e..89b4720aa 100644
--- a/pkg/tcpip/transport/packet/endpoint.go
+++ b/pkg/tcpip/transport/packet/endpoint.go
@@ -207,8 +207,52 @@ func (ep *endpoint) Read(dst io.Writer, opts tcpip.ReadOptions) (tcpip.ReadResul
 	return res, nil
 }
 
-func (*endpoint) Write(tcpip.Payloader, tcpip.WriteOptions) (int64, tcpip.Error) {
-	return 0, &tcpip.ErrInvalidOptionValue{}
+func (ep *endpoint) Write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, tcpip.Error) {
+	if !ep.stack.PacketEndpointWriteSupported() {
+		return 0, &tcpip.ErrNotSupported{}
+	}
+
+	ep.mu.Lock()
+	closed := ep.closed
+	nicID := ep.boundNIC
+	ep.mu.Unlock()
+	if closed {
+		return 0, &tcpip.ErrClosedForSend{}
+	}
+
+	var remote tcpip.LinkAddress
+	proto := ep.netProto
+	if to := opts.To; to != nil {
+		remote = tcpip.LinkAddress(to.Addr)
+
+		if n := to.NIC; n != 0 {
+			nicID = n
+		}
+
+		if p := to.Port; p != 0 {
+			proto = tcpip.NetworkProtocolNumber(p)
+		}
+	}
+
+	if nicID == 0 {
+		return 0, &tcpip.ErrInvalidOptionValue{}
+	}
+
+	// TODO(https://gvisor.dev/issue/6538): Avoid this allocation.
+	payloadBytes := make(buffer.View, p.Len())
+	if _, err := io.ReadFull(p, payloadBytes); err != nil {
+		return 0, &tcpip.ErrBadBuffer{}
+	}
+
+	if err := func() tcpip.Error {
+		if ep.cooked {
+			return ep.stack.WritePacketToRemote(nicID, remote, proto, payloadBytes.ToVectorisedView())
+		}
+		return ep.stack.WriteRawPacket(nicID, proto, payloadBytes.ToVectorisedView())
+	}(); err != nil {
+		return 0, err
+	}
+	return int64(len(payloadBytes)), nil
 }
 
 // Disconnect implements tcpip.Endpoint.Disconnect. Packet sockets cannot be
diff --git a/pkg/tcpip/transport/packet/endpoint_state.go b/pkg/tcpip/transport/packet/endpoint_state.go
index e729921db..5c688d286 100644
--- a/pkg/tcpip/transport/packet/endpoint_state.go
+++ b/pkg/tcpip/transport/packet/endpoint_state.go
@@ -34,17 +34,11 @@ func (p *packet) loadReceivedAt(nsec int64) {
 
 // saveData saves packet.data field.
 func (p *packet) saveData() buffer.VectorisedView {
-	// We cannot save p.data directly as p.data.views may alias to p.views,
-	// which is not allowed by state framework (in-struct pointer).
 	return p.data.Clone(nil)
 }
 
 // loadData loads packet.data field.
 func (p *packet) loadData(data buffer.VectorisedView) {
-	// NOTE: We cannot do the p.data = data.Clone(p.views[:]) optimization
-	// here because data.views is not guaranteed to be loaded by now. Plus,
-	// data.views will be allocated anyway so there really is little point
-	// of utilizing p.views for data.views.
 	p.data = data
 }