AF_PACKET support for netstack (aka epsocket).

Like (AF_INET, SOCK_RAW) sockets, AF_PACKET sockets require CAP_NET_RAW. With
runsc, you'll need to pass `--net-raw=true` to enable them.

Binding isn't supported yet.

PiperOrigin-RevId: 275909366

2 files changed, 22 insertions, 6 deletions

diff --git a/pkg/tcpip/link/waitable/waitable.go b/pkg/tcpip/link/waitable/waitable.go
index 5a1791cb5..e9b50b802 100644
--- a/pkg/tcpip/link/waitable/waitable.go
+++ b/pkg/tcpip/link/waitable/waitable.go
@@ -50,12 +50,12 @@ func New(lower stack.LinkEndpoint) *Endpoint {
 // It is called by the link-layer endpoint being wrapped when a packet arrives,
 // and only forwards to the actual dispatcher if Wait or WaitDispatch haven't
 // been called.
-func (e *Endpoint) DeliverNetworkPacket(linkEP stack.LinkEndpoint, remote, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, vv buffer.VectorisedView) {
+func (e *Endpoint) DeliverNetworkPacket(linkEP stack.LinkEndpoint, remote, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, vv buffer.VectorisedView, linkHeader buffer.View) {
 	if !e.dispatchGate.Enter() {
 		return
 	}
 
-	e.dispatcher.DeliverNetworkPacket(e, remote, local, protocol, vv)
+	e.dispatcher.DeliverNetworkPacket(e, remote, local, protocol, vv, linkHeader)
 	e.dispatchGate.Leave()
 }
 
@@ -109,6 +109,17 @@ func (e *Endpoint) WritePacket(r *stack.Route, gso *stack.GSO, hdr buffer.Prepen
 	return err
 }
 
+// WriteRawPacket implements stack.LinkEndpoint.WriteRawPacket.
+func (e *Endpoint) WriteRawPacket(packet buffer.VectorisedView) *tcpip.Error {
+	if !e.writeGate.Enter() {
+		return nil
+	}
+
+	err := e.lower.WriteRawPacket(packet)
+	e.writeGate.Leave()
+	return err
+}
+
 // WaitWrite prevents new calls to WritePacket from reaching the lower endpoint,
 // and waits for inflight ones to finish before returning.
 func (e *Endpoint) WaitWrite() {
diff --git a/pkg/tcpip/link/waitable/waitable_test.go b/pkg/tcpip/link/waitable/waitable_test.go
index ae23c96b7..f03bbceec 100644
--- a/pkg/tcpip/link/waitable/waitable_test.go
+++ b/pkg/tcpip/link/waitable/waitable_test.go
@@ -35,7 +35,7 @@ type countedEndpoint struct {
 	dispatcher stack.NetworkDispatcher
 }
 
-func (e *countedEndpoint) DeliverNetworkPacket(linkEP stack.LinkEndpoint, remote, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, vv buffer.VectorisedView) {
+func (e *countedEndpoint) DeliverNetworkPacket(linkEP stack.LinkEndpoint, remote, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, vv buffer.VectorisedView, linkHeader buffer.View) {
 	e.dispatchCount++
 }
 
@@ -70,6 +70,11 @@ func (e *countedEndpoint) WritePacket(r *stack.Route, _ *stack.GSO, hdr buffer.P
 	return nil
 }
 
+func (e *countedEndpoint) WriteRawPacket(packet buffer.VectorisedView) *tcpip.Error {
+	e.writeCount++
+	return nil
+}
+
 // Wait implements stack.LinkEndpoint.Wait.
 func (*countedEndpoint) Wait() {}
 
@@ -109,21 +114,21 @@ func TestWaitDispatch(t *testing.T) {
 	}
 
 	// Dispatch and check that it goes through.
-	ep.dispatcher.DeliverNetworkPacket(ep, "", "", 0, buffer.VectorisedView{})
+	ep.dispatcher.DeliverNetworkPacket(ep, "", "", 0, buffer.VectorisedView{}, buffer.View{})
 	if want := 1; ep.dispatchCount != want {
 		t.Fatalf("Unexpected dispatchCount: got=%v, want=%v", ep.dispatchCount, want)
 	}
 
 	// Wait on writes, then try to dispatch. It must go through.
 	wep.WaitWrite()
-	ep.dispatcher.DeliverNetworkPacket(ep, "", "", 0, buffer.VectorisedView{})
+	ep.dispatcher.DeliverNetworkPacket(ep, "", "", 0, buffer.VectorisedView{}, buffer.View{})
 	if want := 2; ep.dispatchCount != want {
 		t.Fatalf("Unexpected dispatchCount: got=%v, want=%v", ep.dispatchCount, want)
 	}
 
 	// Wait on dispatches, then try to dispatch. It must not go through.
 	wep.WaitDispatch()
-	ep.dispatcher.DeliverNetworkPacket(ep, "", "", 0, buffer.VectorisedView{})
+	ep.dispatcher.DeliverNetworkPacket(ep, "", "", 0, buffer.VectorisedView{}, buffer.View{})
 	if want := 2; ep.dispatchCount != want {
 		t.Fatalf("Unexpected dispatchCount: got=%v, want=%v", ep.dispatchCount, want)
 	}