3 files changed, 21 insertions, 8 deletions
diff --git a/pkg/tcpip/link/ethernet/ethernet.go b/pkg/tcpip/link/ethernet/ethernet.go
index b427c6170..b9db273d0 100644
--- a/pkg/tcpip/link/ethernet/ethernet.go
+++ b/pkg/tcpip/link/ethernet/ethernet.go
@@ -42,6 +42,14 @@ type Endpoint struct {
 	nested.Endpoint
 }
 
+// LinkAddress implements stack.LinkEndpoint.
+func (e *Endpoint) LinkAddress() tcpip.LinkAddress {
+	if l := e.Endpoint.LinkAddress(); len(l) != 0 {
+		return l
+	}
+	return header.UnspecifiedEthernetAddress
+}
+
 // DeliverNetworkPacket implements stack.NetworkDispatcher.
 func (e *Endpoint) DeliverNetworkPacket(_, _ tcpip.LinkAddress, _ tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) {
 	hdr, ok := pkt.LinkHeader().Consume(header.EthernetMinimumSize)
@@ -57,18 +65,22 @@ func (e *Endpoint) DeliverNetworkPacket(_, _ tcpip.LinkAddress, _ tcpip.NetworkP
 
 // Capabilities implements stack.LinkEndpoint.
 func (e *Endpoint) Capabilities() stack.LinkEndpointCapabilities {
-	return stack.CapabilityResolutionRequired | e.Endpoint.Capabilities()
+	c := e.Endpoint.Capabilities()
+	if c&stack.CapabilityLoopback == 0 {
+		c |= stack.CapabilityResolutionRequired
+	}
+	return c
 }
 
 // WritePacket implements stack.LinkEndpoint.
 func (e *Endpoint) WritePacket(r stack.RouteInfo, proto tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) tcpip.Error {
-	e.AddHeader(e.Endpoint.LinkAddress(), r.RemoteLinkAddress, proto, pkt)
+	e.AddHeader(e.LinkAddress(), r.RemoteLinkAddress, proto, pkt)
 	return e.Endpoint.WritePacket(r, proto, pkt)
 }
 
 // WritePackets implements stack.LinkEndpoint.
 func (e *Endpoint) WritePackets(r stack.RouteInfo, pkts stack.PacketBufferList, proto tcpip.NetworkProtocolNumber) (int, tcpip.Error) {
-	linkAddr := e.Endpoint.LinkAddress()
+	linkAddr := e.LinkAddress()
 
 	for pkt := pkts.Front(); pkt != nil; pkt = pkt.Next() {
 		e.AddHeader(linkAddr, r.RemoteLinkAddress, proto, pkt)
@@ -83,7 +95,10 @@ func (e *Endpoint) MaxHeaderLength() uint16 {
 }
 
 // ARPHardwareType implements stack.LinkEndpoint.
-func (*Endpoint) ARPHardwareType() header.ARPHardwareType {
+func (e *Endpoint) ARPHardwareType() header.ARPHardwareType {
+	if a := e.Endpoint.ARPHardwareType(); a != header.ARPHardwareNone {
+		return a
+	}
 	return header.ARPHardwareEther
 }
 
diff --git a/pkg/tcpip/link/tun/BUILD b/pkg/tcpip/link/tun/BUILD
index 4758a99ad..c3e4c3455 100644
--- a/pkg/tcpip/link/tun/BUILD
+++ b/pkg/tcpip/link/tun/BUILD
@@ -31,7 +31,6 @@ go_library(
         "//pkg/refs",
         "//pkg/refsvfs2",
         "//pkg/sync",
-        "//pkg/syserror",
         "//pkg/tcpip",
         "//pkg/tcpip/buffer",
         "//pkg/tcpip/header",
diff --git a/pkg/tcpip/link/tun/device.go b/pkg/tcpip/link/tun/device.go
index d23210503..fa2131c28 100644
--- a/pkg/tcpip/link/tun/device.go
+++ b/pkg/tcpip/link/tun/device.go
@@ -20,7 +20,6 @@ import (
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 	"gvisor.dev/gvisor/pkg/sync"
-	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
@@ -174,7 +173,7 @@ func (d *Device) Write(data []byte) (int64, error) {
 		return 0, linuxerr.EBADFD
 	}
 	if !endpoint.IsAttached() {
-		return 0, syserror.EIO
+		return 0, linuxerr.EIO
 	}
 
 	dataLen := int64(len(data))
@@ -249,7 +248,7 @@ func (d *Device) Read() ([]byte, error) {
 	for {
 		info, ok := endpoint.Read()
 		if !ok {
-			return nil, syserror.ErrWouldBlock
+			return nil, linuxerr.ErrWouldBlock
 		}
 
 		v, ok := d.encodePkt(&info)