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// Copyright 2023 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.
package cmd
import (
"context"
_ "embed"
"fmt"
"path/filepath"
"github.com/google/subcommands"
"gvisor.dev/gvisor/runsc/flag"
)
// TunnelPinDir returns the directory to which eBPF objects will be pinned when
// xdp_loader is run against iface.
func TunnelPinDir(iface string) string {
return filepath.Join(bpffsDirPath, iface)
}
// TunnelHostMapPath returns the path where the eBPF map will be pinned when
// xdp_loader is run against iface.
func TunnelHostMapPath(iface string) string {
return filepath.Join(TunnelPinDir(iface), "tunnel_host_map")
}
// TunnelHostProgramPath returns the path where the eBPF program will be pinned
// when xdp_loader is run against iface.
func TunnelHostProgramPath(iface string) string {
return filepath.Join(TunnelPinDir(iface), "tunnel_host_program")
}
// TunnelHostLinkPath returns the path where the eBPF link will be pinned when
// xdp_loader is run against iface.
func TunnelHostLinkPath(iface string) string {
return filepath.Join(TunnelPinDir(iface), "tunnel_host_link")
}
// TunnelVethMapPath returns the path where the eBPF map should be pinned when
// xdp_loader is run against iface.
func TunnelVethMapPath(iface string) string {
return filepath.Join(TunnelPinDir(iface), "tunnel_veth_map")
}
// TunnelVethProgramPath returns the path where the eBPF program should be pinned
// when xdp_loader is run against iface.
func TunnelVethProgramPath(iface string) string {
return filepath.Join(TunnelPinDir(iface), "tunnel_veth_program")
}
// TunnelVethLinkPath returns the path where the eBPF link should be pinned when
// xdp_loader is run against iface.
func TunnelVethLinkPath(iface string) string {
return filepath.Join(TunnelPinDir(iface), "tunnel_veth_link")
}
//go:embed bpf/tunnel_host_ebpf.o
var tunnelHostProgram []byte
// TunnelCommand is a subcommand for tunneling traffic between two NICs. It is
// intended as a fast path between the host NIC and the veth of a container.
//
// SSH traffic is not tunneled. It is passed through to the Linux network stack.
type TunnelCommand struct {
device string
deviceIndex int
unpin bool
}
// Name implements subcommands.Command.Name.
func (*TunnelCommand) Name() string {
return "tunnel"
}
// Synopsis implements subcommands.Command.Synopsis.
func (*TunnelCommand) Synopsis() string {
return "Tunnel packets between two interfaces using AF_XDP. Pins eBPF objects in /sys/fs/bpf/<interface name>/."
}
// Usage implements subcommands.Command.Usage.
func (*TunnelCommand) Usage() string {
return "tunnel {-device <device> | -device-idx <device index>} [--unpin]"
}
// SetFlags implements subcommands.Command.SetFlags.
func (tn *TunnelCommand) SetFlags(fs *flag.FlagSet) {
fs.StringVar(&tn.device, "device", "", "which host device to attach to")
fs.IntVar(&tn.deviceIndex, "device-idx", 0, "which host device to attach to")
fs.BoolVar(&tn.unpin, "unpin", false, "unpin the map and program instead of pinning new ones; useful to reset state")
}
// Execute implements subcommands.Command.Execute.
func (tn *TunnelCommand) Execute(context.Context, *flag.FlagSet, ...any) subcommands.ExitStatus {
if err := tn.execute(); err != nil {
fmt.Printf("%v\n", err)
return subcommands.ExitFailure
}
return subcommands.ExitSuccess
}
func (tn *TunnelCommand) execute() error {
iface, err := getIface(tn.device, tn.deviceIndex)
if err != nil {
return fmt.Errorf("failed to get host iface: %v", err)
}
return installProgramAndMap(installProgramAndMapOpts{
program: tunnelHostProgram,
iface: iface,
unpin: tn.unpin,
pinDir: RedirectPinDir(iface.Name),
mapPath: TunnelHostMapPath(iface.Name),
programPath: TunnelHostProgramPath(iface.Name),
linkPath: TunnelHostLinkPath(iface.Name),
})
}
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