tailscale/net/tstun/tun_linux.go

104 lines
3.1 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package tstun
import (
"bytes"
"errors"
"os"
"os/exec"
"strings"
"syscall"
"tailscale.com/types/logger"
"tailscale.com/version/distro"
)
func init() {
tunDiagnoseFailure = diagnoseLinuxTUNFailure
}
func diagnoseLinuxTUNFailure(tunName string, logf logger.Logf, createErr error) {
if errors.Is(createErr, syscall.EBUSY) {
logf("TUN device %s is busy; another process probably still has it open (from old version of Tailscale that had a bug)", tunName)
logf("To fix, kill the process that has it open. Find with:\n\n$ sudo lsof -n /dev/net/tun\n\n")
logf("... and then kill those PID(s)")
return
}
var un syscall.Utsname
err := syscall.Uname(&un)
if err != nil {
logf("no TUN, and failed to look up kernel version: %v", err)
return
}
kernel := utsReleaseField(&un)
logf("Linux kernel version: %s", kernel)
modprobeOut, err := exec.Command("/sbin/modprobe", "tun").CombinedOutput()
if err == nil {
logf("'modprobe tun' successful")
// Either tun is currently loaded, or it's statically
// compiled into the kernel (which modprobe checks
// with /lib/modules/$(uname -r)/modules.builtin)
//
// So if there's a problem at this point, it's
// probably because /dev/net/tun doesn't exist.
const dev = "/dev/net/tun"
if fi, err := os.Stat(dev); err != nil {
logf("tun module loaded in kernel, but %s does not exist", dev)
} else {
logf("%s: %v", dev, fi.Mode())
}
// We failed to find why it failed. Just let our
// caller report the error it got from wireguard-go.
return
}
logf("is CONFIG_TUN enabled in your kernel? `modprobe tun` failed with: %s", modprobeOut)
switch distro.Get() {
case distro.Debian:
dpkgOut, err := exec.Command("dpkg", "-S", "kernel/drivers/net/tun.ko").CombinedOutput()
if len(bytes.TrimSpace(dpkgOut)) == 0 || err != nil {
logf("tun module not loaded nor found on disk")
return
}
if !bytes.Contains(dpkgOut, []byte(kernel)) {
logf("kernel/drivers/net/tun.ko found on disk, but not for current kernel; are you in middle of a system update and haven't rebooted? found: %s", dpkgOut)
}
case distro.Arch:
findOut, err := exec.Command("find", "/lib/modules/", "-path", "*/net/tun.ko*").CombinedOutput()
if len(bytes.TrimSpace(findOut)) == 0 || err != nil {
logf("tun module not loaded nor found on disk")
return
}
if !bytes.Contains(findOut, []byte(kernel)) {
logf("kernel/drivers/net/tun.ko found on disk, but not for current kernel; are you in middle of a system update and haven't rebooted? found: %s", findOut)
}
case distro.OpenWrt:
out, err := exec.Command("opkg", "list-installed").CombinedOutput()
if err != nil {
logf("error querying OpenWrt installed packages: %s", out)
return
}
for _, pkg := range []string{"kmod-tun", "ca-bundle"} {
if !bytes.Contains(out, []byte(pkg+" - ")) {
logf("Missing required package %s; run: opkg install %s", pkg, pkg)
}
}
}
}
func utsReleaseField(u *syscall.Utsname) string {
var sb strings.Builder
for _, v := range u.Release {
if v == 0 {
break
}
sb.WriteByte(byte(v))
}
return strings.TrimSpace(sb.String())
}