types/persist: add AttestationKey (#17281)

Extend Persist with AttestationKey to record a hardware-backed
attestation key for the node's identity.

Add a flag to tailscaled to allow users to control the use of
hardware-backed keys to bind node identity to individual machines.

Updates tailscale/corp#31269


Change-Id: Idcf40d730a448d85f07f1bebf387f086d4c58be3

Signed-off-by: Patrick O'Doherty <patrick@tailscale.com>

cmd/cloner/cloner.go

@@ -121,7 +121,12 @@ func gen(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named) {
 				continue
 			}
 			if !hasBasicUnderlying(ft) {
-				writef("dst.%s = *src.%s.Clone()", fname, fname)
+				// don't dereference if the underlying type is an interface
+				if _, isInterface := ft.Underlying().(*types.Interface); isInterface {
+					writef("if src.%s != nil { dst.%s = src.%s.Clone() }", fname, fname, fname)
+				} else {
+					writef("dst.%s = *src.%s.Clone()", fname, fname)
+				}
 				continue
 			}
 		}

cmd/cloner/cloner_test.go

@@ -59,3 +59,52 @@ func TestSliceContainer(t *testing.T) {
 		})
 	}
 }
+
+func TestInterfaceContainer(t *testing.T) {
+	examples := []struct {
+		name string
+		in   *clonerex.InterfaceContainer
+	}{
+		{
+			name: "nil",
+			in:   nil,
+		},
+		{
+			name: "zero",
+			in:   &clonerex.InterfaceContainer{},
+		},
+		{
+			name: "with_interface",
+			in: &clonerex.InterfaceContainer{
+				Interface: &clonerex.CloneableImpl{Value: 42},
+			},
+		},
+		{
+			name: "with_nil_interface",
+			in: &clonerex.InterfaceContainer{
+				Interface: nil,
+			},
+		},
+	}
+
+	for _, ex := range examples {
+		t.Run(ex.name, func(t *testing.T) {
+			out := ex.in.Clone()
+			if !reflect.DeepEqual(ex.in, out) {
+				t.Errorf("Clone() = %v, want %v", out, ex.in)
+			}
+
+			// Verify no aliasing: modifying the clone should not affect the original
+			if ex.in != nil && ex.in.Interface != nil {
+				if impl, ok := out.Interface.(*clonerex.CloneableImpl); ok {
+					impl.Value = 999
+					if origImpl, ok := ex.in.Interface.(*clonerex.CloneableImpl); ok {
+						if origImpl.Value == 999 {
+							t.Errorf("Clone() aliased memory with original")
+						}
+					}
+				}
+			}
+		})
+	}
+}

cmd/cloner/clonerex/clonerex.go

@@ -1,7 +1,7 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
 
-//go:generate go run tailscale.com/cmd/cloner  -clonefunc=true -type SliceContainer
+//go:generate go run tailscale.com/cmd/cloner  -clonefunc=true -type SliceContainer,InterfaceContainer
 
 // Package clonerex is an example package for the cloner tool.
 package clonerex
@@ -9,3 +9,26 @@ package clonerex
 type SliceContainer struct {
 	Slice []*int
 }
+
+// Cloneable is an interface with a Clone method.
+type Cloneable interface {
+	Clone() Cloneable
+}
+
+// CloneableImpl is a concrete type that implements Cloneable.
+type CloneableImpl struct {
+	Value int
+}
+
+func (c *CloneableImpl) Clone() Cloneable {
+	if c == nil {
+		return nil
+	}
+	return &CloneableImpl{Value: c.Value}
+}
+
+// InterfaceContainer has a pointer to an interface field, which tests
+// the special handling for interface types in the cloner.
+type InterfaceContainer struct {
+	Interface Cloneable
+}

cmd/cloner/clonerex/clonerex_clone.go

@@ -35,9 +35,28 @@ var _SliceContainerCloneNeedsRegeneration = SliceContainer(struct {
 	Slice []*int
 }{})
 
+// Clone makes a deep copy of InterfaceContainer.
+// The result aliases no memory with the original.
+func (src *InterfaceContainer) Clone() *InterfaceContainer {
+	if src == nil {
+		return nil
+	}
+	dst := new(InterfaceContainer)
+	*dst = *src
+	if src.Interface != nil {
+		dst.Interface = src.Interface.Clone()
+	}
+	return dst
+}
+
+// A compilation failure here means this code must be regenerated, with the command at the top of this file.
+var _InterfaceContainerCloneNeedsRegeneration = InterfaceContainer(struct {
+	Interface Cloneable
+}{})
+
 // Clone duplicates src into dst and reports whether it succeeded.
 // To succeed, <src, dst> must be of types <*T, *T> or <*T, **T>,
-// where T is one of SliceContainer.
+// where T is one of SliceContainer,InterfaceContainer.
 func Clone(dst, src any) bool {
 	switch src := src.(type) {
 	case *SliceContainer:
@@ -49,6 +68,15 @@ func Clone(dst, src any) bool {
 			*dst = src.Clone()
 			return true
 		}
+	case *InterfaceContainer:
+		switch dst := dst.(type) {
+		case *InterfaceContainer:
+			*dst = *src.Clone()
+			return true
+		case **InterfaceContainer:
+			*dst = src.Clone()
+			return true
+		}
 	}
 	return false
 }

cmd/derper/depaware.txt

@@ -132,7 +132,7 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
         tailscale.com/types/logger                                   from tailscale.com/cmd/derper+
         tailscale.com/types/netmap                                   from tailscale.com/ipn
         tailscale.com/types/opt                                      from tailscale.com/envknob+
-        tailscale.com/types/persist                                  from tailscale.com/ipn
+        tailscale.com/types/persist                                  from tailscale.com/ipn+
         tailscale.com/types/preftype                                 from tailscale.com/ipn
         tailscale.com/types/ptr                                      from tailscale.com/hostinfo+
         tailscale.com/types/result                                   from tailscale.com/util/lineiter

cmd/stund/depaware.txt

@@ -59,16 +59,17 @@ tailscale.com/cmd/stund dependencies: (generated by github.com/tailscale/depawar
         tailscale.com/net/stunserver                                 from tailscale.com/cmd/stund
         tailscale.com/net/tsaddr                                     from tailscale.com/tsweb
         tailscale.com/syncs                                          from tailscale.com/metrics+
-        tailscale.com/tailcfg                                        from tailscale.com/version
+        tailscale.com/tailcfg                                        from tailscale.com/version+
         tailscale.com/tsweb                                          from tailscale.com/cmd/stund+
         tailscale.com/tsweb/promvarz                                 from tailscale.com/cmd/stund
         tailscale.com/tsweb/varz                                     from tailscale.com/tsweb+
         tailscale.com/types/dnstype                                  from tailscale.com/tailcfg
         tailscale.com/types/ipproto                                  from tailscale.com/tailcfg
-        tailscale.com/types/key                                      from tailscale.com/tailcfg
+        tailscale.com/types/key                                      from tailscale.com/tailcfg+
         tailscale.com/types/lazy                                     from tailscale.com/version+
         tailscale.com/types/logger                                   from tailscale.com/tsweb+
         tailscale.com/types/opt                                      from tailscale.com/envknob+
+        tailscale.com/types/persist                                  from tailscale.com/feature
         tailscale.com/types/ptr                                      from tailscale.com/tailcfg+
         tailscale.com/types/result                                   from tailscale.com/util/lineiter
         tailscale.com/types/structs                                  from tailscale.com/tailcfg+

cmd/tailscale/depaware.txt

@@ -162,7 +162,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/types/netmap                                   from tailscale.com/ipn+
         tailscale.com/types/nettype                                  from tailscale.com/net/netcheck+
         tailscale.com/types/opt                                      from tailscale.com/client/tailscale+
-        tailscale.com/types/persist                                  from tailscale.com/ipn
+        tailscale.com/types/persist                                  from tailscale.com/ipn+
         tailscale.com/types/preftype                                 from tailscale.com/cmd/tailscale/cli+
         tailscale.com/types/ptr                                      from tailscale.com/hostinfo+
         tailscale.com/types/result                                   from tailscale.com/util/lineiter

cmd/tailscaled/tailscaled.go

@@ -52,6 +52,7 @@ import (
 	"tailscale.com/syncs"
 	"tailscale.com/tsd"
 	"tailscale.com/types/flagtype"
+	"tailscale.com/types/key"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/logid"
 	"tailscale.com/util/osshare"
@@ -111,19 +112,20 @@ var args struct {
 	// or comma-separated list thereof.
 	tunname string
 
-	cleanUp        bool
+	cleanUp             bool
-	confFile       string // empty, file path, or "vm:user-data"
+	confFile            string // empty, file path, or "vm:user-data"
-	debug          string
+	debug               string
-	port           uint16
+	port                uint16
-	statepath      string
+	statepath           string
-	encryptState   boolFlag
+	encryptState        boolFlag
-	statedir       string
+	statedir            string
-	socketpath     string
+	socketpath          string
-	birdSocketPath string
+	birdSocketPath      string
-	verbose        int
+	verbose             int
-	socksAddr      string // listen address for SOCKS5 server
+	socksAddr           string // listen address for SOCKS5 server
-	httpProxyAddr  string // listen address for HTTP proxy server
+	httpProxyAddr       string // listen address for HTTP proxy server
-	disableLogs    bool
+	disableLogs         bool
+	hardwareAttestation boolFlag
 }
 
 var (
@@ -204,6 +206,9 @@ func main() {
 	flag.BoolVar(&printVersion, "version", false, "print version information and exit")
 	flag.BoolVar(&args.disableLogs, "no-logs-no-support", false, "disable log uploads; this also disables any technical support")
 	flag.StringVar(&args.confFile, "config", "", "path to config file, or 'vm:user-data' to use the VM's user-data (EC2)")
+	if buildfeatures.HasTPM {
+		flag.Var(&args.hardwareAttestation, "hardware-attestation", "use hardware-backed keys to bind node identity to this device when supported by the OS and hardware. Uses TPM 2.0 on Linux and Windows; SecureEnclave on macOS and iOS; and Keystore on Android")
+	}
 	if f, ok := hookRegisterOutboundProxyFlags.GetOk(); ok {
 		f()
 	}
@@ -667,6 +672,9 @@ func getLocalBackend(ctx context.Context, logf logger.Logf, logID logid.PublicID
 			log.Fatalf("failed to start netstack: %v", err)
 		}
 	}
+	if buildfeatures.HasTPM && args.hardwareAttestation.v {
+		lb.SetHardwareAttested()
+	}
 	return lb, nil
 }
 
@@ -879,9 +887,26 @@ func applyIntegrationTestEnvKnob() {
 	}
 }
 
-// handleTPMFlags validates the --encrypt-state flag if set, and defaults
+// handleTPMFlags validates the --encrypt-state and --hardware-attestation flags
-// state encryption on if it's supported and compatible with other settings.
+// if set, and defaults both to on if supported and compatible with other
+// settings.
 func handleTPMFlags() {
+	switch {
+	case args.hardwareAttestation.v:
+		if _, err := key.NewEmptyHardwareAttestationKey(); err == key.ErrUnsupported {
+			log.SetFlags(0)
+			log.Fatalf("--hardware-attestation is not supported on this platform or in this build of tailscaled")
+		}
+	case !args.hardwareAttestation.set:
+		policyHWAttestation, _ := policyclient.Get().GetBoolean(pkey.HardwareAttestation, feature.HardwareAttestationAvailable())
+		if !policyHWAttestation {
+			break
+		}
+		if feature.TPMAvailable() {
+			args.hardwareAttestation.v = true
+		}
+	}
+
 	switch {
 	case args.encryptState.v:
 		// Explicitly enabled, validate.

control/controlclient/direct.go

@@ -7,6 +7,8 @@ import (
 	"bytes"
 	"cmp"
 	"context"
+	"crypto"
+	"crypto/sha256"
 	"encoding/binary"
 	"encoding/json"
 	"errors"
@@ -604,6 +606,7 @@ func (c *Direct) doLogin(ctx context.Context, opt loginOpt) (mustRegen bool, new
 	if persist.NetworkLockKey.IsZero() {
 		persist.NetworkLockKey = key.NewNLPrivate()
 	}
+
 	nlPub := persist.NetworkLockKey.Public()
 
 	if tryingNewKey.IsZero() {
@@ -944,6 +947,27 @@ func (c *Direct) sendMapRequest(ctx context.Context, isStreaming bool, nu Netmap
 		TKAHead:                 tkaHead,
 		ConnectionHandleForTest: connectionHandleForTest,
 	}
+
+	// If we have a hardware attestation key, sign the node key with it and send
+	// the key & signature in the map request.
+	if buildfeatures.HasTPM {
+		if k := persist.AsStruct().AttestationKey; k != nil && !k.IsZero() {
+			hwPub := key.HardwareAttestationPublicFromPlatformKey(k)
+			request.HardwareAttestationKey = hwPub
+
+			t := c.clock.Now()
+			msg := fmt.Sprintf("%d|%s", t.Unix(), nodeKey.String())
+			digest := sha256.Sum256([]byte(msg))
+			sig, err := k.Sign(nil, digest[:], crypto.SHA256)
+			if err != nil {
+				c.logf("failed to sign node key with hardware attestation key: %v", err)
+			} else {
+				request.HardwareAttestationKeySignature = sig
+				request.HardwareAttestationKeySignatureTimestamp = t
+			}
+		}
+	}
+
 	var extraDebugFlags []string
 	if buildfeatures.HasAdvertiseRoutes && hi != nil && c.netMon != nil && !c.skipIPForwardingCheck &&
 		ipForwardingBroken(hi.RoutableIPs, c.netMon.InterfaceState()) {

feature/hooks.go

@@ -6,6 +6,9 @@ package feature
 import (
 	"net/http"
 	"net/url"
+
+	"tailscale.com/types/logger"
+	"tailscale.com/types/persist"
 )
 
 // HookCanAutoUpdate is a hook for the clientupdate package
@@ -45,6 +48,8 @@ var HookProxySetTransportGetProxyConnectHeader Hook[func(*http.Transport)]
 // and available.
 var HookTPMAvailable Hook[func() bool]
 
+var HookGenerateAttestationKeyIfEmpty Hook[func(p *persist.Persist, logf logger.Logf) (bool, error)]
+
 // TPMAvailable reports whether a TPM device is supported and available.
 func TPMAvailable() bool {
 	if f, ok := HookTPMAvailable.GetOk(); ok {
@@ -52,3 +57,17 @@ func TPMAvailable() bool {
 	}
 	return false
 }
+
+// HookHardwareAttestationAvailable is a hook that reports whether hardware
+// attestation is supported and available.
+var HookHardwareAttestationAvailable Hook[func() bool]
+
+// HardwareAttestationAvailable reports whether hardware attestation is
+// supported and available (TPM on Windows/Linux, Secure Enclave on macOS|iOS,
+// KeyStore on Android)
+func HardwareAttestationAvailable() bool {
+	if f, ok := HookHardwareAttestationAvailable.GetOk(); ok {
+		return f()
+	}
+	return false
+}

feature/tpm/attestation.go

@@ -142,13 +142,18 @@ type attestationKeySerialized struct {
 	TPMPublic  []byte `json:"tpmPublic"`
 }
 
+// MarshalJSON implements json.Marshaler.
 func (ak *attestationKey) MarshalJSON() ([]byte, error) {
+	if ak == nil || ak.IsZero() {
+		return []byte("null"), nil
+	}
 	return json.Marshal(attestationKeySerialized{
 		TPMPublic:  ak.tpmPublic.Bytes(),
 		TPMPrivate: ak.tpmPrivate.Buffer,
 	})
 }
 
+// UnmarshalJSON implements json.Unmarshaler.
 func (ak *attestationKey) UnmarshalJSON(data []byte) (retErr error) {
 	var aks attestationKeySerialized
 	if err := json.Unmarshal(data, &aks); err != nil {
@@ -254,6 +259,9 @@ func (ak *attestationKey) Close() error {
 }
 
 func (ak *attestationKey) Clone() key.HardwareAttestationKey {
+	if ak == nil {
+		return nil
+	}
 	return &attestationKey{
 		tpm:        ak.tpm,
 		tpmPrivate: ak.tpmPrivate,
@@ -263,4 +271,9 @@ func (ak *attestationKey) Clone() key.HardwareAttestationKey {
 	}
 }
 
-func (ak *attestationKey) IsZero() bool { return !ak.loaded() }
+func (ak *attestationKey) IsZero() bool {
+	if ak == nil {
+		return true
+	}
+	return !ak.loaded()
+}

feature/tpm/tpm.go

@@ -40,6 +40,8 @@ var infoOnce = sync.OnceValue(info)
 func init() {
 	feature.Register("tpm")
 	feature.HookTPMAvailable.Set(tpmSupported)
+	feature.HookHardwareAttestationAvailable.Set(tpmSupported)
+
 	hostinfo.RegisterHostinfoNewHook(func(hi *tailcfg.Hostinfo) {
 		hi.TPM = infoOnce()
 	})

ipn/ipnlocal/hwattest.go

@@ -0,0 +1,48 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build !ts_omit_tpm
+
+package ipnlocal
+
+import (
+	"errors"
+
+	"tailscale.com/feature"
+	"tailscale.com/types/key"
+	"tailscale.com/types/logger"
+	"tailscale.com/types/persist"
+)
+
+func init() {
+	feature.HookGenerateAttestationKeyIfEmpty.Set(generateAttestationKeyIfEmpty)
+}
+
+// generateAttestationKeyIfEmpty generates a new hardware attestation key if
+// none exists. It returns true if a new key was generated and stored in
+// p.AttestationKey.
+func generateAttestationKeyIfEmpty(p *persist.Persist, logf logger.Logf) (bool, error) {
+	// attempt to generate a new hardware attestation key if none exists
+	var ak key.HardwareAttestationKey
+	if p != nil {
+		ak = p.AttestationKey
+	}
+
+	if ak == nil || ak.IsZero() {
+		var err error
+		ak, err = key.NewHardwareAttestationKey()
+		if err != nil {
+			if !errors.Is(err, key.ErrUnsupported) {
+				logf("failed to create hardware attestation key: %v", err)
+			}
+		} else if ak != nil {
+			logf("using new hardware attestation key: %v", ak.Public())
+			if p == nil {
+				p = &persist.Persist{}
+			}
+			p.AttestationKey = ak
+			return true, nil
+		}
+	}
+	return false, nil
+}

ipn/ipnlocal/local.go

@@ -392,6 +392,23 @@ type LocalBackend struct {
 	//
 	// See tailscale/corp#29969.
 	overrideExitNodePolicy bool
+
+	// hardwareAttested is whether backend should use a hardware-backed key to
+	// bind the node identity to this device.
+	hardwareAttested atomic.Bool
+}
+
+// SetHardwareAttested enables hardware attestation key signatures in map
+// requests, if supported on this platform. SetHardwareAttested should be called
+// before Start.
+func (b *LocalBackend) SetHardwareAttested() {
+	b.hardwareAttested.Store(true)
+}
+
+// HardwareAttested reports whether hardware-backed attestation keys should be
+// used to bind the node's identity to this device.
+func (b *LocalBackend) HardwareAttested() bool {
+	return b.hardwareAttested.Load()
 }
 
 // HealthTracker returns the health tracker for the backend.
@@ -2455,10 +2472,23 @@ func (b *LocalBackend) Start(opts ipn.Options) error {
 	if b.reconcilePrefsLocked(newPrefs) {
 		prefsChanged = true
 	}
+
+	// neither UpdatePrefs or reconciliation should change Persist
+	newPrefs.Persist = b.pm.CurrentPrefs().Persist().AsStruct()
+
+	if buildfeatures.HasTPM {
+		if genKey, ok := feature.HookGenerateAttestationKeyIfEmpty.GetOk(); ok {
+			newKey, err := genKey(newPrefs.Persist, b.logf)
+			if err != nil {
+				b.logf("failed to populate attestation key from TPM: %v", err)
+			}
+			if newKey {
+				prefsChanged = true
+			}
+		}
+	}
+
 	if prefsChanged {
-		// Neither opts.UpdatePrefs nor prefs reconciliation
-		// is allowed to modify Persist; retain the old value.
-		newPrefs.Persist = b.pm.CurrentPrefs().Persist().AsStruct()
 		if err := b.pm.SetPrefs(newPrefs.View(), cn.NetworkProfile()); err != nil {
 			b.logf("failed to save updated and reconciled prefs: %v", err)
 		}
@@ -2491,8 +2521,6 @@ func (b *LocalBackend) Start(opts ipn.Options) error {
 
 	discoPublic := b.MagicConn().DiscoPublicKey()
 
-	var err error
-
 	isNetstack := b.sys.IsNetstackRouter()
 	debugFlags := controlDebugFlags
 	if isNetstack {

ipn/ipnlocal/local_test.go

@@ -7030,6 +7030,27 @@ func TestDisplayMessageIPNBus(t *testing.T) {
 	}
 }
 
+func TestHardwareAttested(t *testing.T) {
+	b := new(LocalBackend)
+
+	// default false
+	if got := b.HardwareAttested(); got != false {
+		t.Errorf("HardwareAttested() = %v, want false", got)
+	}
+
+	// set true
+	b.SetHardwareAttested()
+	if got := b.HardwareAttested(); got != true {
+		t.Errorf("HardwareAttested() = %v, want true after SetHardwareAttested()", got)
+	}
+
+	// repeat calls are safe; still true
+	b.SetHardwareAttested()
+	if got := b.HardwareAttested(); got != true {
+		t.Errorf("HardwareAttested() = %v, want true after second SetHardwareAttested()", got)
+	}
+}
+
 func TestDeps(t *testing.T) {
 	deptest.DepChecker{
 		OnImport: func(pkg string) {

ipn/ipnlocal/profiles.go

@@ -19,7 +19,9 @@ import (
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/ipnext"
 	"tailscale.com/tailcfg"
+	"tailscale.com/types/key"
 	"tailscale.com/types/logger"
+	"tailscale.com/types/persist"
 	"tailscale.com/util/clientmetric"
 	"tailscale.com/util/eventbus"
 )
@@ -645,8 +647,8 @@ func (pm *profileManager) setProfileAsUserDefault(profile ipn.LoginProfileView)
 	return pm.WriteState(k, []byte(profile.Key()))
 }
 
-func (pm *profileManager) loadSavedPrefs(key ipn.StateKey) (ipn.PrefsView, error) {
+func (pm *profileManager) loadSavedPrefs(k ipn.StateKey) (ipn.PrefsView, error) {
-	bs, err := pm.store.ReadState(key)
+	bs, err := pm.store.ReadState(k)
 	if err == ipn.ErrStateNotExist || len(bs) == 0 {
 		return defaultPrefs, nil
 	}
@@ -654,10 +656,18 @@ func (pm *profileManager) loadSavedPrefs(key ipn.StateKey) (ipn.PrefsView, error
 		return ipn.PrefsView{}, err
 	}
 	savedPrefs := ipn.NewPrefs()
+
+	// if supported by the platform, create an empty hardware attestation key to use when deserializing
+	// to avoid type exceptions from json.Unmarshaling into an interface{}.
+	hw, _ := key.NewEmptyHardwareAttestationKey()
+	savedPrefs.Persist = &persist.Persist{
+		AttestationKey: hw,
+	}
+
 	if err := ipn.PrefsFromBytes(bs, savedPrefs); err != nil {
 		return ipn.PrefsView{}, fmt.Errorf("parsing saved prefs: %v", err)
 	}
-	pm.logf("using backend prefs for %q: %v", key, savedPrefs.Pretty())
+	pm.logf("using backend prefs for %q: %v", k, savedPrefs.Pretty())
 
 	// Ignore any old stored preferences for https://login.tailscale.com
 	// as the control server that would override the new default of

ipn/ipnlocal/profiles_test.go

@@ -151,6 +151,7 @@ func TestProfileDupe(t *testing.T) {
 				ID:        tailcfg.UserID(user),
 				LoginName: fmt.Sprintf("user%d@example.com", user),
 			},
+			AttestationKey: nil,
 		}
 	}
 	user1Node1 := newPersist(1, 1)

ipn/prefs.go

@@ -709,6 +709,7 @@ 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.
+
 	p := &Prefs{
 		// ControlURL is explicitly not set to signal that
 		// it's not yet configured, which relaxes the CLI "up"

ipn/prefs_test.go

@@ -501,7 +501,7 @@ func TestPrefsPretty(t *testing.T) {
 				},
 			},
 			"linux",
-			`Prefs{ra=false dns=false want=false routes=[] nf=off update=off Persist{o=, n=[B1VKl] u=""}}`,
+			`Prefs{ra=false dns=false want=false routes=[] nf=off update=off Persist{o=, n=[B1VKl] u="" ak=-}}`,
 		},
 		{
 			Prefs{

tailcfg/tailcfg.go

@@ -176,7 +176,8 @@ type CapabilityVersion int
 //   - 127: 2025-09-19: can handle C2N /debug/netmap.
 //   - 128: 2025-10-02: can handle C2N /debug/health.
 //   - 129: 2025-10-04: Fixed sleep/wake deadlock in magicsock when using peer relay (PR #17449)
-const CurrentCapabilityVersion CapabilityVersion = 129
+//   - 130: 2025-10-06: client can send key.HardwareAttestationPublic and key.HardwareAttestationKeySignature in MapRequest
+const CurrentCapabilityVersion CapabilityVersion = 130
 
 // ID is an integer ID for a user, node, or login allocated by the
 // control plane.
@@ -1372,9 +1373,13 @@ type MapRequest struct {
 	// HardwareAttestationKey is the public key of the node's hardware-backed
 	// identity attestation key, if any.
 	HardwareAttestationKey key.HardwareAttestationPublic `json:",omitzero"`
-	// HardwareAttestationKeySignature is the signature of the NodeKey
+	// HardwareAttestationKeySignature is the signature of
-	// serialized using MarshalText using its hardware attestation key, if any.
+	// "$UNIX_TIMESTAMP|$NODE_KEY" using its hardware attestation key, if any.
 	HardwareAttestationKeySignature []byte `json:",omitempty"`
+	// HardwareAttestationKeySignatureTimestamp is the time at which the
+	// HardwareAttestationKeySignature was created, if any. This UNIX timestamp
+	// value is prepended to the node key when signing.
+	HardwareAttestationKeySignatureTimestamp time.Time `json:",omitzero"`
 
 	// Stream is whether the client wants to receive multiple MapResponses over
 	// the same HTTP connection.

types/persist/persist.go

@@ -26,6 +26,7 @@ type Persist struct {
 	UserProfile       tailcfg.UserProfile
 	NetworkLockKey    key.NLPrivate
 	NodeID            tailcfg.StableNodeID
+	AttestationKey    key.HardwareAttestationKey `json:",omitempty"`
 
 	// DisallowedTKAStateIDs stores the tka.State.StateID values which
 	// this node will not operate network lock on. This is used to
@@ -84,11 +85,20 @@ func (p *Persist) Equals(p2 *Persist) bool {
 		return false
 	}
 
+	var pub, p2Pub key.HardwareAttestationPublic
+	if p.AttestationKey != nil && !p.AttestationKey.IsZero() {
+		pub = key.HardwareAttestationPublicFromPlatformKey(p.AttestationKey)
+	}
+	if p2.AttestationKey != nil && !p2.AttestationKey.IsZero() {
+		p2Pub = key.HardwareAttestationPublicFromPlatformKey(p2.AttestationKey)
+	}
+
 	return p.PrivateNodeKey.Equal(p2.PrivateNodeKey) &&
 		p.OldPrivateNodeKey.Equal(p2.OldPrivateNodeKey) &&
 		p.UserProfile.Equal(&p2.UserProfile) &&
 		p.NetworkLockKey.Equal(p2.NetworkLockKey) &&
 		p.NodeID == p2.NodeID &&
+		pub.Equal(p2Pub) &&
 		reflect.DeepEqual(nilIfEmpty(p.DisallowedTKAStateIDs), nilIfEmpty(p2.DisallowedTKAStateIDs))
 }
 
@@ -96,12 +106,16 @@ func (p *Persist) Pretty() string {
 	var (
 		ok, nk key.NodePublic
 	)
+	akString := "-"
 	if !p.OldPrivateNodeKey.IsZero() {
 		ok = p.OldPrivateNodeKey.Public()
 	}
 	if !p.PrivateNodeKey.IsZero() {
 		nk = p.PublicNodeKey()
 	}
-	return fmt.Sprintf("Persist{o=%v, n=%v u=%#v}",
+	if p.AttestationKey != nil && !p.AttestationKey.IsZero() {
-		ok.ShortString(), nk.ShortString(), p.UserProfile.LoginName)
+		akString = fmt.Sprintf("%v", p.AttestationKey.Public())
+	}
+	return fmt.Sprintf("Persist{o=%v, n=%v u=%#v ak=%s}",
+		ok.ShortString(), nk.ShortString(), p.UserProfile.LoginName, akString)
 }

types/persist/persist_clone.go

@@ -19,6 +19,9 @@ func (src *Persist) Clone() *Persist {
 	}
 	dst := new(Persist)
 	*dst = *src
+	if src.AttestationKey != nil {
+		dst.AttestationKey = src.AttestationKey.Clone()
+	}
 	dst.DisallowedTKAStateIDs = append(src.DisallowedTKAStateIDs[:0:0], src.DisallowedTKAStateIDs...)
 	return dst
 }
@@ -31,5 +34,6 @@ var _PersistCloneNeedsRegeneration = Persist(struct {
 	UserProfile           tailcfg.UserProfile
 	NetworkLockKey        key.NLPrivate
 	NodeID                tailcfg.StableNodeID
+	AttestationKey        key.HardwareAttestationKey
 	DisallowedTKAStateIDs []string
 }{})

types/persist/persist_test.go

@@ -21,7 +21,7 @@ func fieldsOf(t reflect.Type) (fields []string) {
 }
 
 func TestPersistEqual(t *testing.T) {
-	persistHandles := []string{"PrivateNodeKey", "OldPrivateNodeKey", "UserProfile", "NetworkLockKey", "NodeID", "DisallowedTKAStateIDs"}
+	persistHandles := []string{"PrivateNodeKey", "OldPrivateNodeKey", "UserProfile", "NetworkLockKey", "NodeID", "AttestationKey", "DisallowedTKAStateIDs"}
 	if have := fieldsOf(reflect.TypeFor[Persist]()); !reflect.DeepEqual(have, persistHandles) {
 		t.Errorf("Persist.Equal check might be out of sync\nfields: %q\nhandled: %q\n",
 			have, persistHandles)

types/persist/persist_view.go

@@ -89,10 +89,11 @@ func (v *PersistView) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 func (v PersistView) PrivateNodeKey() key.NodePrivate { return v.ж.PrivateNodeKey }
 
 // needed to request key rotation
-func (v PersistView) OldPrivateNodeKey() key.NodePrivate { return v.ж.OldPrivateNodeKey }
+func (v PersistView) OldPrivateNodeKey() key.NodePrivate   { return v.ж.OldPrivateNodeKey }
-func (v PersistView) UserProfile() tailcfg.UserProfile   { return v.ж.UserProfile }
+func (v PersistView) UserProfile() tailcfg.UserProfile     { return v.ж.UserProfile }
-func (v PersistView) NetworkLockKey() key.NLPrivate      { return v.ж.NetworkLockKey }
+func (v PersistView) NetworkLockKey() key.NLPrivate        { return v.ж.NetworkLockKey }
-func (v PersistView) NodeID() tailcfg.StableNodeID       { return v.ж.NodeID }
+func (v PersistView) NodeID() tailcfg.StableNodeID         { return v.ж.NodeID }
+func (v PersistView) AttestationKey() tailcfg.StableNodeID { panic("unsupported") }
 
 // DisallowedTKAStateIDs stores the tka.State.StateID values which
 // this node will not operate network lock on. This is used to
@@ -110,5 +111,6 @@ var _PersistViewNeedsRegeneration = Persist(struct {
 	UserProfile           tailcfg.UserProfile
 	NetworkLockKey        key.NLPrivate
 	NodeID                tailcfg.StableNodeID
+	AttestationKey        key.HardwareAttestationKey
 	DisallowedTKAStateIDs []string
 }{})

util/syspolicy/pkey/pkey.go

@@ -141,6 +141,10 @@ const (
 	// It's a noop on other platforms.
 	EncryptState Key = "EncryptState"
 
+	// HardwareAttestation is a boolean key that controls whether to use a
+	// hardware-backed key to bind the node identity to this device.
+	HardwareAttestation Key = "HardwareAttestation"
+
 	// PostureChecking indicates if posture checking is enabled and the client shall gather
 	// posture data.
 	// Key is a string value that specifies an option: "always", "never", "user-decides".

util/syspolicy/policy_keys.go

@@ -43,6 +43,7 @@ var implicitDefinitions = []*setting.Definition{
 	setting.NewDefinition(pkey.PostureChecking, setting.DeviceSetting, setting.PreferenceOptionValue),
 	setting.NewDefinition(pkey.ReconnectAfter, setting.DeviceSetting, setting.DurationValue),
 	setting.NewDefinition(pkey.Tailnet, setting.DeviceSetting, setting.StringValue),
+	setting.NewDefinition(pkey.HardwareAttestation, setting.DeviceSetting, setting.BooleanValue),
 
 	// User policy settings (can be configured on a user- or device-basis):
 	setting.NewDefinition(pkey.AdminConsoleVisibility, setting.UserSetting, setting.VisibilityValue),