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tailscale/ipn/prefs.go

637 lines
19 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"
"errors"
"fmt"
"io/ioutil"
"log"
"os"
"path/filepath"
"reflect"
"runtime"
"strings"
"inet.af/netaddr"
"tailscale.com/atomicfile"
"tailscale.com/ipn/ipnstate"
"tailscale.com/net/tsaddr"
"tailscale.com/tailcfg"
"tailscale.com/types/persist"
"tailscale.com/types/preftype"
"tailscale.com/util/dnsname"
)
//go:generate go run tailscale.com/cmd/cloner -type=Prefs -output=prefs_clone.go
// DefaultControlURL is the URL base of the control plane
// ("coordination server") for use when no explicit one is configured.
// The default control plane is the hosted version run by Tailscale.com.
const DefaultControlURL = "https://controlplane.tailscale.com"
var (
// ErrExitNodeIDAlreadySet is returned from (*Prefs).SetExitNodeIP when the
// Prefs.ExitNodeID field is already set.
ErrExitNodeIDAlreadySet = errors.New("cannot set ExitNodeIP when ExitNodeID is already set")
)
// IsLoginServerSynonym reports whether a URL is a drop-in replacement
// for the primary Tailscale login server.
func IsLoginServerSynonym(val any) bool {
return val == "https://login.tailscale.com" || val == "https://controlplane.tailscale.com"
}
// Prefs are the user modifiable settings of the Tailscale node agent.
type Prefs struct {
// ControlURL is the URL of the control server to use.
//
// If empty, the default for new installs, DefaultControlURL
// is used. It's set non-empty once the daemon has been started
// for the first time.
//
// TODO(apenwarr): Make it safe to update this with SetPrefs().
// Right now, you have to pass it in the initial prefs in Start(),
// which is the only code that actually uses the ControlURL value.
// It would be more consistent to restart controlclient
// automatically whenever this variable changes.
//
// Meanwhile, you have to provide this as part of Options.Prefs or
// Options.UpdatePrefs when calling Backend.Start().
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
// ExitNodeAllowLANAccess indicates whether locally accessible subnets should be
// routed directly or via the exit node.
ExitNodeAllowLANAccess bool
// CorpDNS specifies whether to install the Tailscale network's
// DNS configuration, if it exists.
CorpDNS bool
// RunSSH bool is whether this node should run an SSH
// server, permitting access to peers according to the
// policies as configured by the Tailnet's admin(s).
RunSSH bool
// WantRunning indicates whether networking should be active on
// this node.
WantRunning bool
// LoggedOut indicates whether the user intends to be logged out.
// There are other reasons we may be logged out, including no valid
// keys.
// We need to remember this state so that, on next startup, we can
// generate the "Login" vs "Connect" buttons correctly, without having
// to contact the server to confirm our nodekey status first.
LoggedOut 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
// 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
// OperatorUser is the local machine user name who is allowed to
// operate tailscaled without being root or using sudo.
OperatorUser string `json:",omitempty"`
// 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"`
ExitNodeAllowLANAccessSet bool `json:",omitempty"`
CorpDNSSet bool `json:",omitempty"`
RunSSHSet bool `json:",omitempty"`
WantRunningSet bool `json:",omitempty"`
LoggedOutSet bool `json:",omitempty"`
ShieldsUpSet bool `json:",omitempty"`
AdvertiseTagsSet bool `json:",omitempty"`
HostnameSet bool `json:",omitempty"`
NotepadURLsSet bool `json:",omitempty"`
ForceDaemonSet bool `json:",omitempty"`
AdvertiseRoutesSet bool `json:",omitempty"`
NoSNATSet bool `json:",omitempty"`
NetfilterModeSet bool `json:",omitempty"`
OperatorUserSet 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
format := func(v reflect.Value) string {
switch v.Type().Kind() {
case reflect.String:
return "%s=%q"
case reflect.Slice:
// []string
if v.Type().Elem().Kind() == reflect.String {
return "%s=%q"
}
}
return "%s=%v"
}
for i := 1; i < mt.NumField(); i++ {
name := mt.Field(i).Name
if mv.Field(i).Bool() {
if !first {
sb.WriteString(" ")
}
first = false
f := mpv.Field(i - 1)
fmt.Fprintf(&sb, format(f),
strings.TrimSuffix(name, "Set"),
f.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.RunSSH {
sb.WriteString("ssh=true ")
}
if p.LoggedOut {
sb.WriteString("loggedout=true ")
}
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 lan=%t ", p.ExitNodeIP, p.ExitNodeAllowLANAccess)
} else if !p.ExitNodeID.IsZero() {
fmt.Fprintf(&sb, "exit=%v lan=%t ", p.ExitNodeID, p.ExitNodeAllowLANAccess)
}
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 != DefaultControlURL {
fmt.Fprintf(&sb, "url=%q ", p.ControlURL)
}
if p.Hostname != "" {
fmt.Fprintf(&sb, "host=%q ", p.Hostname)
}
if p.OperatorUser != "" {
fmt.Fprintf(&sb, "op=%q ", p.OperatorUser)
}
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.ExitNodeAllowLANAccess == p2.ExitNodeAllowLANAccess &&
p.CorpDNS == p2.CorpDNS &&
p.RunSSH == p2.RunSSH &&
p.WantRunning == p2.WantRunning &&
p.LoggedOut == p2.LoggedOut &&
p.NotepadURLs == p2.NotepadURLs &&
p.ShieldsUp == p2.ShieldsUp &&
p.NoSNAT == p2.NoSNAT &&
p.NetfilterMode == p2.NetfilterMode &&
p.OperatorUser == p2.OperatorUser &&
p.Hostname == p2.Hostname &&
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
}
// NewPrefs returns the default preferences to use.
func NewPrefs() *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.
return &Prefs{
// ControlURL is explicitly not set to signal that
// it's not yet configured, which relaxes the CLI "up"
// safety net features. It will get set to DefaultControlURL
// on first up. Or, if not, DefaultControlURL will be used
// later anyway.
ControlURL: "",
RouteAll: true,
AllowSingleHosts: true,
CorpDNS: true,
WantRunning: false,
NetfilterMode: preftype.NetfilterOn,
}
}
// ControlURLOrDefault returns the coordination server's URL base.
//
// If not configured, or if the configured value is a legacy name equivalent to
// the default, then DefaultControlURL is returned instead.
func (p *Prefs) ControlURLOrDefault() string {
if p.ControlURL != "" {
if p.ControlURL != DefaultControlURL && IsLoginServerSynonym(p.ControlURL) {
return DefaultControlURL
}
return p.ControlURL
}
return DefaultControlURL
}
// AdminPageURL returns the admin web site URL for the current ControlURL.
func (p *Prefs) AdminPageURL() string {
url := p.ControlURLOrDefault()
if IsLoginServerSynonym(url) {
// TODO(crawshaw): In future release, make this https://console.tailscale.com
url = "https://login.tailscale.com"
}
return url + "/admin/machines"
}
// AdvertisesExitNode reports whether p is advertising both the v4 and
// v6 /0 exit node routes.
func (p *Prefs) AdvertisesExitNode() bool {
if p == nil {
return false
}
return tsaddr.ContainsExitRoutes(p.AdvertiseRoutes)
}
// SetAdvertiseExitNode mutates p (if non-nil) to add or remove the two
// /0 exit node routes.
func (p *Prefs) SetAdvertiseExitNode(runExit bool) {
if p == nil {
return
}
all := p.AdvertiseRoutes
p.AdvertiseRoutes = p.AdvertiseRoutes[:0]
for _, r := range all {
if r.Bits() != 0 {
p.AdvertiseRoutes = append(p.AdvertiseRoutes, r)
}
}
if !runExit {
return
}
p.AdvertiseRoutes = append(p.AdvertiseRoutes,
netaddr.IPPrefixFrom(netaddr.IPv4(0, 0, 0, 0), 0),
netaddr.IPPrefixFrom(netaddr.IPv6Unspecified(), 0))
}
// peerWithTailscaleIP returns the peer in st with the provided
// Tailscale IP.
func peerWithTailscaleIP(st *ipnstate.Status, ip netaddr.IP) (ps *ipnstate.PeerStatus, ok bool) {
for _, ps := range st.Peer {
for _, ip2 := range ps.TailscaleIPs {
if ip == ip2 {
return ps, true
}
}
}
return nil, false
}
func isRemoteIP(st *ipnstate.Status, ip netaddr.IP) bool {
for _, selfIP := range st.TailscaleIPs {
if ip == selfIP {
return false
}
}
return true
}
// ClearExitNode sets the ExitNodeID and ExitNodeIP to their zero values.
func (p *Prefs) ClearExitNode() {
p.ExitNodeID = ""
p.ExitNodeIP = netaddr.IP{}
}
// ExitNodeLocalIPError is returned when the requested IP address for an exit
// node belongs to the local machine.
type ExitNodeLocalIPError struct {
hostOrIP string
}
func (e ExitNodeLocalIPError) Error() string {
return fmt.Sprintf("cannot use %s as an exit node as it is a local IP address to this machine", e.hostOrIP)
}
func exitNodeIPOfArg(s string, st *ipnstate.Status) (ip netaddr.IP, err error) {
if s == "" {
return ip, os.ErrInvalid
}
ip, err = netaddr.ParseIP(s)
if err == nil {
// If we're online already and have a netmap, double check that the IP
// address specified is valid.
if st.BackendState == "Running" {
ps, ok := peerWithTailscaleIP(st, ip)
if !ok {
return ip, fmt.Errorf("no node found in netmap with IP %v", ip)
}
if !ps.ExitNodeOption {
return ip, fmt.Errorf("node %v is not advertising an exit node", ip)
}
}
if !isRemoteIP(st, ip) {
return ip, ExitNodeLocalIPError{s}
}
return ip, nil
}
match := 0
for _, ps := range st.Peer {
baseName := dnsname.TrimSuffix(ps.DNSName, st.MagicDNSSuffix)
if !strings.EqualFold(s, baseName) {
continue
}
match++
if len(ps.TailscaleIPs) == 0 {
return ip, fmt.Errorf("node %q has no Tailscale IP?", s)
}
if !ps.ExitNodeOption {
return ip, fmt.Errorf("node %q is not advertising an exit node", s)
}
ip = ps.TailscaleIPs[0]
}
switch match {
case 0:
return ip, fmt.Errorf("invalid value %q for --exit-node; must be IP or unique node name", s)
case 1:
if !isRemoteIP(st, ip) {
return ip, ExitNodeLocalIPError{s}
}
return ip, nil
default:
return ip, fmt.Errorf("ambiguous exit node name %q", s)
}
}
// SetExitNodeIP validates and sets the ExitNodeIP from a user-provided string
// specifying either an IP address or a MagicDNS base name ("foo", as opposed to
// "foo.bar.beta.tailscale.net"). This method does not mutate ExitNodeID and
// will fail if ExitNodeID is already set.
func (p *Prefs) SetExitNodeIP(s string, st *ipnstate.Status) error {
if !p.ExitNodeID.IsZero() {
return ErrExitNodeIDAlreadySet
}
ip, err := exitNodeIPOfArg(s, st)
if err == nil {
p.ExitNodeIP = ip
}
return err
}
// PrefsFromBytes deserializes Prefs from a JSON blob.
func PrefsFromBytes(b []byte) (*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)
}
}
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)
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)
}
}