xdp: split xdp_loader subcommands into cmd directory

This allows other code to use them as deps, which is impossible as a go_binary.

PiperOrigin-RevId: 591054831

tools/xdp/BUILD

@@ -8,30 +8,13 @@ package(
 go_binary(
     name = "xdp_loader",
     srcs = [
-        "drop.go",
         "main.go",
-        "pass.go",
-        "redirect_host.go",
-        "tcpdump.go",
-    ],
-    embedsrcs = [
-        "//tools/xdp/bpf:drop_ebpf.o",  # keep
-        "//tools/xdp/bpf:pass_ebpf.o",  # keep
-        "//tools/xdp/bpf:redirect_host_ebpf.o",  # keep
-        "//tools/xdp/bpf:tcpdump_ebpf.o",  # keep
     ],
     pure = True,
     visibility = ["//:sandbox"],
     deps = [
-        "//pkg/buffer",
-        "//pkg/tcpip/header",
-        "//pkg/tcpip/link/sniffer",
-        "//pkg/tcpip/stack",
-        "//pkg/xdp",
         "//runsc/flag",
-        "@com_github_cilium_ebpf//:go_default_library",
-        "@com_github_cilium_ebpf//link:go_default_library",
+        "//tools/xdp/cmd",
         "@com_github_google_subcommands//:go_default_library",
-        "@org_golang_x_sys//unix:go_default_library",
     ],
 )

tools/xdp/cmd/BUILD

@@ -0,0 +1,36 @@
+load("//tools:defs.bzl", "go_library")
+
+package(
+    default_applicable_licenses = ["//:license"],
+    licenses = ["notice"],
+)
+
+go_library(
+    name = "cmd",
+    srcs = [
+        "cmd.go",
+        "drop.go",
+        "pass.go",
+        "redirect_host.go",
+        "tcpdump.go",
+    ],
+    embedsrcs = [
+        "//tools/xdp/cmd/bpf:drop_ebpf.o",  # keep
+        "//tools/xdp/cmd/bpf:pass_ebpf.o",  # keep
+        "//tools/xdp/cmd/bpf:redirect_host_ebpf.o",  # keep
+        "//tools/xdp/cmd/bpf:tcpdump_ebpf.o",  # keep
+    ],
+    visibility = ["//:sandbox"],
+    deps = [
+        "//pkg/buffer",
+        "//pkg/tcpip/header",
+        "//pkg/tcpip/link/sniffer",
+        "//pkg/tcpip/stack",
+        "//pkg/xdp",
+        "//runsc/flag",
+        "@com_github_cilium_ebpf//:go_default_library",
+        "@com_github_cilium_ebpf//link:go_default_library",
+        "@com_github_google_subcommands//:go_default_library",
+        "@org_golang_x_sys//unix:go_default_library",
+    ],
+)

tools/xdp/cmd/cmd.go

@@ -0,0 +1,124 @@
+// Copyright 2022 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 amd64 || arm64
+// +build amd64 arm64
+
+// Package cmd implements the subcommands of xdp_loader.
+package cmd
+
+import (
+	"bytes"
+	_ "embed"
+	"fmt"
+	"log"
+	"net"
+
+	"github.com/cilium/ebpf"
+	"github.com/cilium/ebpf/link"
+	"golang.org/x/sys/unix"
+)
+
+func runBasicProgram(progData []byte, device string, deviceIndex int) error {
+	iface, err := getIface(device, deviceIndex)
+	if err != nil {
+		return fmt.Errorf("%v", err)
+	}
+
+	// Load into the kernel.
+	spec, err := ebpf.LoadCollectionSpecFromReader(bytes.NewReader(progData))
+	if err != nil {
+		return fmt.Errorf("failed to load spec: %v", err)
+	}
+
+	var objects struct {
+		Program *ebpf.Program `ebpf:"xdp_prog"`
+	}
+	if err := spec.LoadAndAssign(&objects, nil); err != nil {
+		return fmt.Errorf("failed to load program: %v", err)
+	}
+	defer func() {
+		if err := objects.Program.Close(); err != nil {
+			fmt.Printf("failed to close program: %v", err)
+		}
+	}()
+
+	_, cleanup, err := attach(objects.Program, iface)
+	if err != nil {
+		return fmt.Errorf("failed to attach: %v", err)
+	}
+	defer cleanup()
+
+	waitForever()
+	return nil
+}
+
+func getIface(device string, deviceIndex int) (*net.Interface, error) {
+	switch {
+	case device != "" && deviceIndex != 0:
+		return nil, fmt.Errorf("device specified twice")
+	case device != "":
+		iface, err := net.InterfaceByName(device)
+		if err != nil {
+			return nil, fmt.Errorf("unknown device %q: %v", device, err)
+		}
+		return iface, nil
+	case deviceIndex != 0:
+		iface, err := net.InterfaceByIndex(deviceIndex)
+		if err != nil {
+			return nil, fmt.Errorf("unknown device with index %d: %v", deviceIndex, err)
+		}
+		return iface, nil
+	default:
+		return nil, fmt.Errorf("no device specified")
+	}
+}
+
+func attach(program *ebpf.Program, iface *net.Interface) (link.Link, func(), error) {
+	// Attach the program to the XDP hook on the device. Fallback from best
+	// to worst mode.
+	modes := []struct {
+		name string
+		flag link.XDPAttachFlags
+	}{
+		{name: "offload", flag: link.XDPOffloadMode},
+		{name: "driver", flag: link.XDPDriverMode},
+		{name: "generic", flag: link.XDPGenericMode},
+	}
+	var attached link.Link
+	var err error
+	for _, mode := range modes {
+		attached, err = link.AttachXDP(link.XDPOptions{
+			Program:   program,
+			Interface: iface.Index,
+			Flags:     mode.flag,
+		})
+		if err == nil {
+			log.Printf("attached with mode %q", mode.name)
+			break
+		}
+		log.Printf("failed to attach with mode %q: %v", mode.name, err)
+	}
+	if attached == nil {
+		return nil, nil, fmt.Errorf("failed to attach program")
+	}
+	return attached, func() { attached.Close() }, nil
+}
+
+func waitForever() {
+	log.Printf("Successfully attached! Press CTRL-C to quit and remove the program from the device.")
+	for {
+		unix.Pause()
+	}
+}

tools/xdp/cmd/drop.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package main
+package cmd
 
 import (
 	"context"

tools/xdp/cmd/pass.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package main
+package cmd
 
 import (
 	"context"

tools/xdp/cmd/redirect_host.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package main
+package cmd
 
 import (
 	"bytes"

tools/xdp/cmd/tcpdump.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package main
+package cmd
 
 import (
 	"bytes"

tools/xdp/main.go

@@ -20,121 +20,22 @@
 package main
 
 import (
-	"bytes"
 	"context"
 	_ "embed"
-	"fmt"
-	"log"
-	"net"
 	"os"
 
-	"github.com/cilium/ebpf"
-	"github.com/cilium/ebpf/link"
 	"github.com/google/subcommands"
-	"golang.org/x/sys/unix"
 	"gvisor.dev/gvisor/runsc/flag"
+	"gvisor.dev/gvisor/tools/xdp/cmd"
 )
 
 func main() {
-	subcommands.Register(new(DropCommand), "")
-	subcommands.Register(new(PassCommand), "")
-	subcommands.Register(new(RedirectHostCommand), "")
-	subcommands.Register(new(TcpdumpCommand), "")
+	subcommands.Register(new(cmd.DropCommand), "")
+	subcommands.Register(new(cmd.PassCommand), "")
+	subcommands.Register(new(cmd.RedirectHostCommand), "")
+	subcommands.Register(new(cmd.TcpdumpCommand), "")
 
 	flag.Parse()
 	ctx := context.Background()
 	os.Exit(int(subcommands.Execute(ctx)))
 }
-
-func runBasicProgram(progData []byte, device string, deviceIndex int) error {
-	iface, err := getIface(device, deviceIndex)
-	if err != nil {
-		return fmt.Errorf("%v", err)
-	}
-
-	// Load into the kernel.
-	spec, err := ebpf.LoadCollectionSpecFromReader(bytes.NewReader(progData))
-	if err != nil {
-		return fmt.Errorf("failed to load spec: %v", err)
-	}
-
-	var objects struct {
-		Program *ebpf.Program `ebpf:"xdp_prog"`
-	}
-	if err := spec.LoadAndAssign(&objects, nil); err != nil {
-		return fmt.Errorf("failed to load program: %v", err)
-	}
-	defer func() {
-		if err := objects.Program.Close(); err != nil {
-			fmt.Printf("failed to close program: %v", err)
-		}
-	}()
-
-	_, cleanup, err := attach(objects.Program, iface)
-	if err != nil {
-		return fmt.Errorf("failed to attach: %v", err)
-	}
-	defer cleanup()
-
-	waitForever()
-	return nil
-}
-
-func getIface(device string, deviceIndex int) (*net.Interface, error) {
-	switch {
-	case device != "" && deviceIndex != 0:
-		return nil, fmt.Errorf("device specified twice")
-	case device != "":
-		iface, err := net.InterfaceByName(device)
-		if err != nil {
-			return nil, fmt.Errorf("unknown device %q: %v", device, err)
-		}
-		return iface, nil
-	case deviceIndex != 0:
-		iface, err := net.InterfaceByIndex(deviceIndex)
-		if err != nil {
-			return nil, fmt.Errorf("unknown device with index %d: %v", deviceIndex, err)
-		}
-		return iface, nil
-	default:
-		return nil, fmt.Errorf("no device specified")
-	}
-}
-
-func attach(program *ebpf.Program, iface *net.Interface) (link.Link, func(), error) {
-	// Attach the program to the XDP hook on the device. Fallback from best
-	// to worst mode.
-	modes := []struct {
-		name string
-		flag link.XDPAttachFlags
-	}{
-		{name: "offload", flag: link.XDPOffloadMode},
-		{name: "driver", flag: link.XDPDriverMode},
-		{name: "generic", flag: link.XDPGenericMode},
-	}
-	var attached link.Link
-	var err error
-	for _, mode := range modes {
-		attached, err = link.AttachXDP(link.XDPOptions{
-			Program:   program,
-			Interface: iface.Index,
-			Flags:     mode.flag,
-		})
-		if err == nil {
-			log.Printf("attached with mode %q", mode.name)
-			break
-		}
-		log.Printf("failed to attach with mode %q: %v", mode.name, err)
-	}
-	if attached == nil {
-		return nil, nil, fmt.Errorf("failed to attach program")
-	}
-	return attached, func() { attached.Close() }, nil
-}
-
-func waitForever() {
-	log.Printf("Successfully attached! Press CTRL-C to quit and remove the program from the device.")
-	for {
-		unix.Pause()
-	}
-}