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xdp: split xdp_loader subcommands into cmd directory
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This allows other code to use them as deps, which is impossible as a go_binary.

PiperOrigin-RevId: 591054831
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kevinGC authored and gvisor-bot committed Dec 14, 2023
1 parent 48fcf0a commit 3b77e29
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Showing 13 changed files with 170 additions and 126 deletions.
19 changes: 1 addition & 18 deletions tools/xdp/BUILD
Original file line number Diff line number Diff line change
Expand Up @@ -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",
],
)
36 changes: 36 additions & 0 deletions tools/xdp/cmd/BUILD
Original file line number Diff line number Diff line change
@@ -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",
],
)
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124 changes: 124 additions & 0 deletions tools/xdp/cmd/cmd.go
Original file line number Diff line number Diff line change
@@ -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()
}
}
2 changes: 1 addition & 1 deletion tools/xdp/drop.go → tools/xdp/cmd/drop.go
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@
// See the License for the specific language governing permissions and
// limitations under the License.

package main
package cmd

import (
"context"
Expand Down
2 changes: 1 addition & 1 deletion tools/xdp/pass.go → tools/xdp/cmd/pass.go
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@
// See the License for the specific language governing permissions and
// limitations under the License.

package main
package cmd

import (
"context"
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@
// See the License for the specific language governing permissions and
// limitations under the License.

package main
package cmd

import (
"bytes"
Expand Down
2 changes: 1 addition & 1 deletion tools/xdp/tcpdump.go → tools/xdp/cmd/tcpdump.go
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@
// See the License for the specific language governing permissions and
// limitations under the License.

package main
package cmd

import (
"bytes"
Expand Down
109 changes: 5 additions & 104 deletions tools/xdp/main.go
Original file line number Diff line number Diff line change
Expand Up @@ -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()
}
}

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