mirror of
https://github.com/tailscale/tailscale.git
synced 2024-11-30 05:25:35 +00:00
104 lines
2.8 KiB
Go
104 lines
2.8 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package netns
|
|
|
|
import (
|
|
"flag"
|
|
"fmt"
|
|
"os"
|
|
"os/exec"
|
|
"sync"
|
|
"syscall"
|
|
|
|
"golang.org/x/sys/unix"
|
|
"tailscale.com/net/interfaces"
|
|
)
|
|
|
|
// tailscaleBypassMark is the mark indicating that packets originating
|
|
// from a socket should bypass Tailscale-managed routes during routing
|
|
// table lookups.
|
|
//
|
|
// Keep this in sync with tailscaleBypassMark in
|
|
// wgengine/router/router_linux.go.
|
|
const tailscaleBypassMark = 0x80000
|
|
|
|
// ipRuleOnce is the sync.Once & cached value for ipRuleAvailable.
|
|
var ipRuleOnce struct {
|
|
sync.Once
|
|
v bool
|
|
}
|
|
|
|
// ipRuleAvailable reports whether the 'ip rule' command works.
|
|
// If it doesn't, we have to use SO_BINDTODEVICE on our sockets instead.
|
|
func ipRuleAvailable() bool {
|
|
ipRuleOnce.Do(func() {
|
|
ipRuleOnce.v = exec.Command("ip", "rule").Run() == nil
|
|
})
|
|
return ipRuleOnce.v
|
|
}
|
|
|
|
// ignoreErrors returns true if we should ignore setsocketopt errors in
|
|
// this instance.
|
|
func ignoreErrors() bool {
|
|
// If we're in a test, ignore errors. Assume the test knows
|
|
// what it's doing and will do its own skips or permission
|
|
// checks if it's setting up a world that needs netns to work.
|
|
// But by default, assume that tests don't need netns and it's
|
|
// harmless to ignore the sockopts failing.
|
|
if flag.CommandLine.Lookup("test.v") != nil {
|
|
return true
|
|
}
|
|
if os.Getuid() != 0 {
|
|
// only root can manipulate these socket flags
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
// control marks c as necessary to dial in a separate network namespace.
|
|
//
|
|
// It's intentionally the same signature as net.Dialer.Control
|
|
// and net.ListenConfig.Control.
|
|
func control(network, address string, c syscall.RawConn) error {
|
|
var sockErr error
|
|
err := c.Control(func(fd uintptr) {
|
|
if ipRuleAvailable() {
|
|
sockErr = setBypassMark(fd)
|
|
} else {
|
|
sockErr = bindToDevice(fd)
|
|
}
|
|
})
|
|
if err != nil {
|
|
return fmt.Errorf("RawConn.Control on %T: %w", c, err)
|
|
}
|
|
if sockErr != nil && ignoreErrors() {
|
|
// TODO(bradfitz): maybe log once? probably too spammy for e.g. CLI tools like tailscale netcheck.
|
|
return nil
|
|
}
|
|
return sockErr
|
|
}
|
|
|
|
func setBypassMark(fd uintptr) error {
|
|
if err := unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_MARK, tailscaleBypassMark); err != nil {
|
|
return fmt.Errorf("setting SO_MARK bypass: %w", err)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func bindToDevice(fd uintptr) error {
|
|
ifc, err := interfaces.DefaultRouteInterface()
|
|
if err != nil {
|
|
// Make sure we bind to *some* interface,
|
|
// or we could get a routing loop.
|
|
// "lo" is always wrong, but if we don't have
|
|
// a default route anyway, it doesn't matter.
|
|
ifc = "lo"
|
|
}
|
|
if err := unix.SetsockoptString(int(fd), unix.SOL_SOCKET, unix.SO_BINDTODEVICE, ifc); err != nil {
|
|
return fmt.Errorf("setting SO_BINDTODEVICE: %w", err)
|
|
}
|
|
return nil
|
|
}
|