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tailscale/ipn/prefs.go

402 lines
12 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 ipn
import (
"bytes"
"encoding/json"
"fmt"
"io/ioutil"
"log"
"os"
"path/filepath"
"reflect"
"runtime"
"strings"
"inet.af/netaddr"
"tailscale.com/atomicfile"
"tailscale.com/tailcfg"
"tailscale.com/types/persist"
"tailscale.com/types/preftype"
)
//go:generate go run tailscale.com/cmd/cloner -type=Prefs -output=prefs_clone.go
// Prefs are the user modifiable settings of the Tailscale node agent.
type Prefs struct {
// ControlURL is the URL of the control server to use.
ControlURL string
// RouteAll specifies whether to accept subnets advertised by
// other nodes on the Tailscale network. Note that this does not
// include default routes (0.0.0.0/0 and ::/0), those are
// controlled by ExitNodeID/IP below.
RouteAll bool
// AllowSingleHosts specifies whether to install routes for each
// node IP on the tailscale network, in addition to a route for
// the whole network.
// This corresponds to the "tailscale up --host-routes" value,
// which defaults to true.
//
// TODO(danderson): why do we have this? It dumps a lot of stuff
// into the routing table, and a single network route _should_ be
// all that we need. But when I turn this off in my tailscaled,
// packets stop flowing. What's up with that?
AllowSingleHosts bool
// ExitNodeID and ExitNodeIP specify the node that should be used
// as an exit node for internet traffic. At most one of these
// should be non-zero.
//
// The preferred way to express the chosen node is ExitNodeID, but
// in some cases it's not possible to use that ID (e.g. in the
// linux CLI, before tailscaled has a netmap). For those
// situations, we allow specifying the exit node by IP, and
// ipnlocal.LocalBackend will translate the IP into an ID when the
// node is found in the netmap.
//
// If the selected exit node doesn't exist (e.g. it's not part of
// the current tailnet), or it doesn't offer exit node services, a
// blackhole route will be installed on the local system to
// prevent any traffic escaping to the local network.
ExitNodeID tailcfg.StableNodeID
ExitNodeIP netaddr.IP
// CorpDNS specifies whether to install the Tailscale network's
// DNS configuration, if it exists.
CorpDNS bool
// WantRunning indicates whether networking should be active on
// this node.
WantRunning bool
// ShieldsUp indicates whether to block all incoming connections,
// regardless of the control-provided packet filter. If false, we
// use the packet filter as provided. If true, we block incoming
// connections. This overrides tailcfg.Hostinfo's ShieldsUp.
ShieldsUp bool
// AdvertiseTags specifies groups that this node wants to join, for
// purposes of ACL enforcement. These can be referenced from the ACL
// security policy. Note that advertising a tag doesn't guarantee that
// the control server will allow you to take on the rights for that
// tag.
AdvertiseTags []string
// Hostname is the hostname to use for identifying the node. If
// not set, os.Hostname is used.
Hostname string
// OSVersion overrides tailcfg.Hostinfo's OSVersion.
OSVersion string
// DeviceModel overrides tailcfg.Hostinfo's DeviceModel.
DeviceModel string
// NotepadURLs is a debugging setting that opens OAuth URLs in
// notepad.exe on Windows, rather than loading them in a browser.
//
// apenwarr 2020-04-29: Unfortunately this is still needed sometimes.
// Windows' default browser setting is sometimes screwy and this helps
// users narrow it down a bit.
NotepadURLs bool
// ForceDaemon specifies whether a platform that normally
// operates in "client mode" (that is, requires an active user
// logged in with the GUI app running) should keep running after the
// GUI ends and/or the user logs out.
//
// The only current applicable platform is Windows. This
// forced Windows to go into "server mode" where Tailscale is
// running even with no users logged in. This might also be
// used for macOS in the future. This setting has no effect
// for Linux/etc, which always operate in daemon mode.
ForceDaemon bool `json:"ForceDaemon,omitempty"`
// The following block of options only have an effect on Linux.
// AdvertiseRoutes specifies CIDR prefixes to advertise into the
// Tailscale network as reachable through the current
// node.
AdvertiseRoutes []netaddr.IPPrefix
// NoSNAT specifies whether to source NAT traffic going to
// destinations in AdvertiseRoutes. The default is to apply source
// NAT, which makes the traffic appear to come from the router
// machine rather than the peer's Tailscale IP.
//
// Disabling SNAT requires additional manual configuration in your
// network to route Tailscale traffic back to the subnet relay
// machine.
//
// Linux-only.
NoSNAT bool
// NetfilterMode specifies how much to manage netfilter rules for
// Tailscale, if at all.
NetfilterMode preftype.NetfilterMode
// The Persist field is named 'Config' in the file for backward
// compatibility with earlier versions.
// TODO(apenwarr): We should move this out of here, it's not a pref.
// We can maybe do that once we're sure which module should persist
// it (backend or frontend?)
Persist *persist.Persist `json:"Config"`
}
// MaskedPrefs is a Prefs with an associated bitmask of which fields are set.
type MaskedPrefs struct {
Prefs
ControlURLSet bool `json:",omitempty"`
RouteAllSet bool `json:",omitempty"`
AllowSingleHostsSet bool `json:",omitempty"`
ExitNodeIDSet bool `json:",omitempty"`
ExitNodeIPSet bool `json:",omitempty"`
CorpDNSSet bool `json:",omitempty"`
WantRunningSet bool `json:",omitempty"`
ShieldsUpSet bool `json:",omitempty"`
AdvertiseTagsSet bool `json:",omitempty"`
HostnameSet bool `json:",omitempty"`
OSVersionSet bool `json:",omitempty"`
DeviceModelSet bool `json:",omitempty"`
NotepadURLsSet bool `json:",omitempty"`
ForceDaemonSet bool `json:",omitempty"`
AdvertiseRoutesSet bool `json:",omitempty"`
NoSNATSet bool `json:",omitempty"`
NetfilterModeSet bool `json:",omitempty"`
}
// ApplyEdits mutates p, assigning fields from m.Prefs for each MaskedPrefs
// Set field that's true.
func (p *Prefs) ApplyEdits(m *MaskedPrefs) {
if p == nil {
panic("can't edit nil Prefs")
}
pv := reflect.ValueOf(p).Elem()
mv := reflect.ValueOf(m).Elem()
mpv := reflect.ValueOf(&m.Prefs).Elem()
fields := mv.NumField()
for i := 1; i < fields; i++ {
if mv.Field(i).Bool() {
newFieldValue := mpv.Field(i - 1)
pv.Field(i - 1).Set(newFieldValue)
}
}
}
func (m *MaskedPrefs) Pretty() string {
if m == nil {
return "MaskedPrefs{<nil>}"
}
var sb strings.Builder
sb.WriteString("MaskedPrefs{")
mv := reflect.ValueOf(m).Elem()
mt := mv.Type()
mpv := reflect.ValueOf(&m.Prefs).Elem()
first := true
for i := 1; i < mt.NumField(); i++ {
name := mt.Field(i).Name
if mv.Field(i).Bool() {
if !first {
sb.WriteString(" ")
}
first = false
fmt.Fprintf(&sb, "%s=%#v",
strings.TrimSuffix(name, "Set"),
mpv.Field(i-1).Interface())
}
}
sb.WriteString("}")
return sb.String()
}
// IsEmpty reports whether p is nil or pointing to a Prefs zero value.
func (p *Prefs) IsEmpty() bool { return p == nil || p.Equals(&Prefs{}) }
func (p *Prefs) Pretty() string { return p.pretty(runtime.GOOS) }
func (p *Prefs) pretty(goos string) string {
var sb strings.Builder
sb.WriteString("Prefs{")
fmt.Fprintf(&sb, "ra=%v ", p.RouteAll)
if !p.AllowSingleHosts {
sb.WriteString("mesh=false ")
}
fmt.Fprintf(&sb, "dns=%v want=%v ", p.CorpDNS, p.WantRunning)
if p.ForceDaemon {
sb.WriteString("server=true ")
}
if p.NotepadURLs {
sb.WriteString("notepad=true ")
}
if p.ShieldsUp {
sb.WriteString("shields=true ")
}
if !p.ExitNodeIP.IsZero() {
fmt.Fprintf(&sb, "exit=%v ", p.ExitNodeIP)
} else if !p.ExitNodeID.IsZero() {
fmt.Fprintf(&sb, "exit=%v ", p.ExitNodeID)
}
if len(p.AdvertiseRoutes) > 0 || goos == "linux" {
fmt.Fprintf(&sb, "routes=%v ", p.AdvertiseRoutes)
}
if len(p.AdvertiseRoutes) > 0 || p.NoSNAT {
fmt.Fprintf(&sb, "snat=%v ", !p.NoSNAT)
}
if len(p.AdvertiseTags) > 0 {
fmt.Fprintf(&sb, "tags=%s ", strings.Join(p.AdvertiseTags, ","))
}
if goos == "linux" {
fmt.Fprintf(&sb, "nf=%v ", p.NetfilterMode)
}
if p.ControlURL != "" && p.ControlURL != "https://login.tailscale.com" {
fmt.Fprintf(&sb, "url=%q ", p.ControlURL)
}
if p.Hostname != "" {
fmt.Fprintf(&sb, "host=%q ", p.Hostname)
}
if p.Persist != nil {
sb.WriteString(p.Persist.Pretty())
} else {
sb.WriteString("Persist=nil")
}
sb.WriteString("}")
return sb.String()
}
func (p *Prefs) ToBytes() []byte {
data, err := json.MarshalIndent(p, "", "\t")
if err != nil {
log.Fatalf("Prefs marshal: %v\n", err)
}
return data
}
func (p *Prefs) Equals(p2 *Prefs) bool {
if p == nil && p2 == nil {
return true
}
if p == nil || p2 == nil {
return false
}
return p != nil && p2 != nil &&
p.ControlURL == p2.ControlURL &&
p.RouteAll == p2.RouteAll &&
p.AllowSingleHosts == p2.AllowSingleHosts &&
p.ExitNodeID == p2.ExitNodeID &&
p.ExitNodeIP == p2.ExitNodeIP &&
p.CorpDNS == p2.CorpDNS &&
p.WantRunning == p2.WantRunning &&
p.NotepadURLs == p2.NotepadURLs &&
p.ShieldsUp == p2.ShieldsUp &&
p.NoSNAT == p2.NoSNAT &&
p.NetfilterMode == p2.NetfilterMode &&
p.Hostname == p2.Hostname &&
p.OSVersion == p2.OSVersion &&
p.DeviceModel == p2.DeviceModel &&
p.ForceDaemon == p2.ForceDaemon &&
compareIPNets(p.AdvertiseRoutes, p2.AdvertiseRoutes) &&
compareStrings(p.AdvertiseTags, p2.AdvertiseTags) &&
p.Persist.Equals(p2.Persist)
}
func compareIPNets(a, b []netaddr.IPPrefix) bool {
if len(a) != len(b) {
return false
}
for i := range a {
if a[i] != b[i] {
return false
}
}
return true
}
func compareStrings(a, b []string) bool {
if len(a) != len(b) {
return false
}
for i := range a {
if a[i] != b[i] {
return false
}
}
return true
}
func NewPrefs() *Prefs {
return &Prefs{
// Provide default values for options which might be missing
// from the json data for any reason. The json can still
// override them to false.
ControlURL: "https://login.tailscale.com",
RouteAll: true,
AllowSingleHosts: true,
CorpDNS: true,
WantRunning: false,
NetfilterMode: preftype.NetfilterOn,
}
}
// PrefsFromBytes deserializes Prefs from a JSON blob. If
// enforceDefaults is true, Prefs.RouteAll and Prefs.AllowSingleHosts
// are forced on.
func PrefsFromBytes(b []byte, enforceDefaults bool) (*Prefs, error) {
p := NewPrefs()
if len(b) == 0 {
return p, nil
}
persist := &persist.Persist{}
err := json.Unmarshal(b, persist)
if err == nil && (persist.Provider != "" || persist.LoginName != "") {
// old-style relaynode config; import it
p.Persist = persist
} else {
err = json.Unmarshal(b, &p)
if err != nil {
log.Printf("Prefs parse: %v: %v\n", err, b)
}
}
if enforceDefaults {
p.RouteAll = true
p.AllowSingleHosts = true
}
return p, err
}
// LoadPrefs loads a legacy relaynode config file into Prefs
// with sensible migration defaults set.
func LoadPrefs(filename string) (*Prefs, error) {
data, err := ioutil.ReadFile(filename)
if err != nil {
return nil, fmt.Errorf("LoadPrefs open: %w", err) // err includes path
}
if bytes.Contains(data, jsonEscapedZero) {
// Tailscale 1.2.0 - 1.2.8 on Windows had a memory corruption bug
// in the backend process that ended up sending NULL bytes over JSON
// to the frontend which wrote them out to JSON files on disk.
// So if we see one, treat is as corrupt and the user will need
// to log in again. (better than crashing)
return nil, os.ErrNotExist
}
p, err := PrefsFromBytes(data, false)
if err != nil {
return nil, fmt.Errorf("LoadPrefs(%q) decode: %w", filename, err)
}
return p, nil
}
func SavePrefs(filename string, p *Prefs) {
log.Printf("Saving prefs %v %v\n", filename, p.Pretty())
data := p.ToBytes()
os.MkdirAll(filepath.Dir(filename), 0700)
if err := atomicfile.WriteFile(filename, data, 0600); err != nil {
log.Printf("SavePrefs: %v\n", err)
}
}