// Copyright (c) Tailscale Inc & AUTHORS // SPDX-License-Identifier: BSD-3-Clause package ipn import ( "bytes" "encoding/json" "errors" "fmt" "log" "net/netip" "os" "path/filepath" "reflect" "runtime" "strings" "tailscale.com/atomicfile" "tailscale.com/ipn/ipnstate" "tailscale.com/net/netaddr" "tailscale.com/net/tsaddr" "tailscale.com/tailcfg" "tailscale.com/types/persist" "tailscale.com/types/preftype" "tailscale.com/types/views" "tailscale.com/util/dnsname" ) // 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.LegacyMigrationPrefs 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 netip.Addr // 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"` // Egg is a optional debug flag. Egg bool `json:",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 []netip.Prefix // 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"` // ProfileName is the desired name of the profile. If empty, then the user's // LoginName is used. It is only used for display purposes in the client UI // and CLI. ProfileName string `json:",omitempty"` // AutoUpdate sets the auto-update preferences for the node agent. See // AutoUpdatePrefs docs for more details. AutoUpdate AutoUpdatePrefs // 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"` } // AutoUpdatePrefs are the auto update settings for the node agent. type AutoUpdatePrefs struct { // Check specifies whether background checks for updates are enabled. When // enabled, tailscaled will periodically check for available updates and // notify the user about them. Check bool // Apply specifies whether background auto-updates are enabled. When // enabled, tailscaled will apply available updates in the background. // Check must also be set when Apply is set. Apply bool } // 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"` EggSet bool `json:",omitempty"` AdvertiseRoutesSet bool `json:",omitempty"` NoSNATSet bool `json:",omitempty"` NetfilterModeSet bool `json:",omitempty"` OperatorUserSet bool `json:",omitempty"` ProfileNameSet bool `json:",omitempty"` AutoUpdateSet 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) } } } // IsEmpty reports whether there are no masks set or if m is nil. func (m *MaskedPrefs) IsEmpty() bool { if m == nil { return true } mv := reflect.ValueOf(m).Elem() fields := mv.NumField() for i := 1; i < fields; i++ { if mv.Field(i).Bool() { return false } } return true } func (m *MaskedPrefs) Pretty() string { if m == nil { return "MaskedPrefs{}" } 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" } case reflect.Struct: return "%s=%+v" case reflect.Pointer: if v.Type().Elem().Kind() == reflect.Struct { return "%s=%+v" } } 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 PrefsView) Pretty() string { return p.ж.Pretty() } 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.IsValid() { 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) } sb.WriteString(p.AutoUpdate.Pretty()) if p.Persist != nil { sb.WriteString(p.Persist.Pretty()) } else { sb.WriteString("Persist=nil") } sb.WriteString("}") return sb.String() } func (p PrefsView) ToBytes() []byte { return p.ж.ToBytes() } 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 PrefsView) Equals(p2 PrefsView) bool { return p.ж.Equals(p2.ж) } 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) && p.ProfileName == p2.ProfileName && p.AutoUpdate == p2.AutoUpdate } func (au AutoUpdatePrefs) Pretty() string { if au.Apply { return "update=on " } if au.Check { return "update=check " } return "update=off " } func compareIPNets(a, b []netip.Prefix) 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, AutoUpdate: AutoUpdatePrefs{ Check: true, Apply: false, }, } } // 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 PrefsView) ControlURLOrDefault() string { return p.ж.ControlURLOrDefault() } // 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 PrefsView) AdminPageURL() string { return p.ж.AdminPageURL() } // 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 PrefsView) AdvertisesExitNode() bool { return p.ж.AdvertisesExitNode() } // 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(views.SliceOf(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, netip.PrefixFrom(netaddr.IPv4(0, 0, 0, 0), 0), netip.PrefixFrom(netip.IPv6Unspecified(), 0)) } // peerWithTailscaleIP returns the peer in st with the provided // Tailscale IP. func peerWithTailscaleIP(st *ipnstate.Status, ip netip.Addr) (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 netip.Addr) 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 = netip.Addr{} } // 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 netip.Addr, err error) { if s == "" { return ip, os.ErrInvalid } ip, err = netip.ParseAddr(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 } // ShouldSSHBeRunning reports whether the SSH server should be running based on // the prefs. func (p PrefsView) ShouldSSHBeRunning() bool { return p.Valid() && p.ж.ShouldSSHBeRunning() } // ShouldSSHBeRunning reports whether the SSH server should be running based on // the prefs. func (p *Prefs) ShouldSSHBeRunning() bool { return p.WantRunning && p.RunSSH } // PrefsFromBytes deserializes Prefs from a JSON blob. func PrefsFromBytes(b []byte) (*Prefs, error) { p := NewPrefs() if len(b) == 0 { return p, nil } if err := json.Unmarshal(b, p); err != nil { return nil, err } return p, nil } var jsonEscapedZero = []byte(`\u0000`) // LoadPrefs loads a legacy relaynode config file into Prefs // with sensible migration defaults set. func LoadPrefs(filename string) (*Prefs, error) { data, err := os.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) } } // ProfileID is an auto-generated system-wide unique identifier for a login // profile. It is a 4 character hex string like "1ab3". type ProfileID string // WindowsUserID is a userid (suitable for passing to ipnauth.LookupUserFromID // or os/user.LookupId) but only set on Windows. It's empty on all other // platforms, unless envknob.GOOS is in used, making Linux act like Windows for // tests. type WindowsUserID string // LoginProfile represents a single login profile as managed // by the ProfileManager. type LoginProfile struct { // ID is a unique identifier for this profile. // It is assigned on creation and never changes. // It may seem redundant to have both ID and UserProfile.ID // but they are different things. UserProfile.ID may change // over time (e.g. if a device is tagged). ID ProfileID // Name is the user-visible name of this profile. // It is filled in from the UserProfile.LoginName field. Name string // Key is the StateKey under which the profile is stored. // It is assigned once at profile creation time and never changes. Key StateKey // UserProfile is the server provided UserProfile for this profile. // This is updated whenever the server provides a new UserProfile. UserProfile tailcfg.UserProfile // NodeID is the NodeID of the node that this profile is logged into. // This should be stable across tagging and untagging nodes. // It may seem redundant to check against both the UserProfile.UserID // and the NodeID. However the NodeID can change if the node is deleted // from the admin panel. NodeID tailcfg.StableNodeID // LocalUserID is the user ID of the user who created this profile. // It is only relevant on Windows where we have a multi-user system. // It is assigned once at profile creation time and never changes. LocalUserID WindowsUserID // ControlURL is the URL of the control server that this profile is logged // into. ControlURL string }