health,ipn/ipnlocal: report the node being locked out as a health issue

Signed-off-by: Tom DNetto <tom@tailscale.com>

health/health.go

@@ -70,6 +70,9 @@ const (
 
 	// SysDNSManager is the name of the net/dns manager subsystem.
 	SysDNSManager = Subsystem("dns-manager")
+
+	// SysTKA is the name of the tailnet key authority subsystem.
+	SysTKA = Subsystem("tailnet-lock")
 )
 
 // NewWarnable returns a new warnable item that the caller can mark
@@ -194,6 +197,12 @@ func SetDNSManagerHealth(err error) { setErr(SysDNSManager, err) }
 // DNSOSHealth returns the net/dns.OSConfigurator error state.
 func DNSOSHealth() error { return get(SysDNSOS) }
 
+// SetTKAHealth sets the health of the tailnet key authority.
+func SetTKAHealth(err error) { setErr(SysTKA, err) }
+
+// TKAHealth returns the tailnet key authority error state.
+func TKAHealth() error { return get(SysTKA) }
+
 // SetLocalLogConfigHealth sets the error state of this client's local log configuration.
 func SetLocalLogConfigHealth(err error) {
 	mu.Lock()

ipn/ipnlocal/network-lock.go

@@ -20,6 +20,7 @@ import (
 	"time"
 
 	"tailscale.com/envknob"
+	"tailscale.com/health"
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/net/tsaddr"
@@ -60,9 +61,11 @@ func (b *LocalBackend) permitTKAInitLocked() bool {
 func (b *LocalBackend) tkaFilterNetmapLocked(nm *netmap.NetworkMap) {
 	// TODO(tom): Remove this guard for 1.35 and later.
 	if b.tka == nil && !b.permitTKAInitLocked() {
+		health.SetTKAHealth(nil)
 		return
 	}
 	if b.tka == nil {
+		health.SetTKAHealth(nil)
 		return // TKA not enabled.
 	}
 
@@ -111,6 +114,13 @@ func (b *LocalBackend) tkaFilterNetmapLocked(nm *netmap.NetworkMap) {
 	} else {
 		b.tka.filtered = nil
 	}
+
+	// Check that we ourselves are not locked out, report a health issue if so.
+	if nm.SelfNode != nil && b.tka.authority.NodeKeyAuthorized(nm.SelfNode.Key, nm.SelfNode.KeySignature) != nil {
+		health.SetTKAHealth(errors.New("this node is locked out; it will not have connectivity until it is signed. For more info, see https://tailscale.com/s/locked-out"))
+	} else {
+		health.SetTKAHealth(nil)
+	}
 }
 
 // tkaSyncIfNeeded examines TKA info reported from the control plane,
@@ -177,6 +187,7 @@ func (b *LocalBackend) tkaSyncIfNeeded(nm *netmap.NetworkMap, prefs ipn.PrefsVie
 				b.logf("Disablement failed, leaving TKA enabled. Error: %v", err)
 			} else {
 				isEnabled = false
+				health.SetTKAHealth(nil)
 			}
 		} else {
 			return fmt.Errorf("[bug] unreachable invariant of wantEnabled /w isEnabled")