runsc: remove cilium as a dependency unless built with --define=gotags=xdp

XDP isn't currently being used or developed, so it's best to reduce external
dependencies.

PiperOrigin-RevId: 678786045

runsc/sandbox/BUILD

@@ -11,6 +11,7 @@ go_library(
         "memory.go",
         "network.go",
         "network_unsafe.go",
+        "no_xdp.go",
         "sandbox.go",
         "sandbox_impl.go",
         "xdp.go",

runsc/sandbox/no_xdp.go

@@ -0,0 +1,45 @@
+// Copyright 2024 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !xdp
+// +build !xdp
+
+package sandbox
+
+import (
+	"errors"
+	"net"
+	"os"
+
+	"gvisor.dev/gvisor/pkg/urpc"
+	"gvisor.dev/gvisor/runsc/config"
+)
+
+// This file holds placeholders for XDP support, which is not compiled in by default.
+//
+// To enable XDP support, build gVisor with `--define=gotags=xdp`.
+
+const noXDPMsg = "XDP support was not built into this release -- rebuild with --define=gotags=xdp"
+
+func createRedirectInterfacesAndRoutes(conn *urpc.Client, conf *config.Config) error {
+	return errors.New(noXDPMsg)
+}
+
+func createSocketXDP(iface net.Interface) ([]*os.File, error) {
+	return nil, errors.New(noXDPMsg)
+}
+
+func createXDPTunnel(conn *urpc.Client, nsPath string, conf *config.Config) error {
+	return errors.New(noXDPMsg)
+}

runsc/sandbox/xdp.go

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build xdp
+// +build xdp
+
 package sandbox
 
 import (
@@ -34,6 +37,10 @@ import (
 	xdpcmd "gvisor.dev/gvisor/tools/xdp/cmd"
 )
 
+// This file supports XDP in gVisor. It is not compiled in by default.
+//
+// To enable XDP support, build gVisor with `--define=gotags=xdp`.
+
 // createRedirectInterfacesAndRoutes initializes the network using an AF_XDP
 // socket on a *host* device, not a device in the container netns. It:
 //