tailscale/net/netns/netns_linux.go
Brad Fitzpatrick 1407540b52 net/netns: don't return an error if we're not root and running the tailscale binary
tailscale netcheck was broken otherwise.

We can fix this a better way later; I'm just fixing a regression in
some way because I'm trying to work on netcheck at the moment.
2020-05-29 21:58:31 -07:00

56 lines
1.5 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.
// +build linux
package netns
import (
"fmt"
"os"
"path/filepath"
"syscall"
"golang.org/x/sys/unix"
)
// 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 = 0x20000
// 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 {
if skipPrivileged.Get() {
// We can't set socket marks without CAP_NET_ADMIN on linux,
// skip as requested.
return nil
}
var controlErr error
err := c.Control(func(fd uintptr) {
controlErr = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_MARK, tailscaleBypassMark)
})
// Before returning some fatal error, see if we're just a regular user
// running cmd/tailscale (presumably netcheck) and ignore the error if so.
if (err != nil || controlErr != nil) && os.Getuid() != 0 {
if v, _ := os.Executable(); filepath.Base(v) == "tailscale" {
return nil
}
}
if err != nil {
return fmt.Errorf("setting socket mark: %w", err)
}
if controlErr != nil {
return fmt.Errorf("setting socket mark: %w", controlErr)
}
return nil
}