[management] Require a private proxy cluster for cluster and direct upstream targets (#7984)

* [management] Require a private proxy cluster for cluster and direct upstream targets

Cluster targets and direct upstream targets make the proxy dial the
upstream from its own host network instead of through the embedded
NetBird client. Only clusters running in private mode are meant to do
that, but the service API accepted these targets on any cluster.

Service create and update now reject such targets unless the service's
proxy cluster reports the private capability. An unreported capability
is treated as unsupported.

* [management] Require every proxy in the cluster to be private

The private capability is aggregated as any-true, so a cluster where
only one proxy runs in private mode passed the check. The mapping is
delivered to every proxy in the cluster, so the non-private ones would
serve cluster and direct upstream targets from their host network too.

Validate these targets against a unanimous aggregation instead. The
existing any-true lookup stays as is for the dashboard flags and the
agent network gateway.

management/server/store/sql_store_proxy.go

@@ -358,6 +358,14 @@ func (s *SqlStore) GetClusterSupportsPrivate(ctx context.Context, clusterAddr st
 	return s.getClusterCapability(ctx, clusterAddr, "private")
 }
 
+// GetClusterAllProxiesPrivate reports whether every active proxy in the cluster
+// has the private capability. Returns nil when no proxy reported the capability.
+// Use it where any proxy in the cluster may serve the result, since a single
+// non-private proxy would serve it without the private guarantees.
+func (s *SqlStore) GetClusterAllProxiesPrivate(ctx context.Context, clusterAddr string) *bool {
+	return s.getClusterUnanimousCapability(ctx, clusterAddr, "private")
+}
+
 // GetClusterSupportsCrowdSec returns whether all active proxies in the cluster
 // have CrowdSec configured. Returns nil when no proxy reported the capability.
 // Unlike other capabilities that use ANY-true (for rolling upgrades), CrowdSec

management/server/store/store.go

@@ -336,6 +336,7 @@ type Store interface {
 	GetClusterRequireSubdomain(ctx context.Context, clusterAddr string) *bool
 	GetClusterSupportsCrowdSec(ctx context.Context, clusterAddr string) *bool
 	GetClusterSupportsPrivate(ctx context.Context, clusterAddr string) *bool
+	GetClusterAllProxiesPrivate(ctx context.Context, clusterAddr string) *bool
 	GetActiveProxyVersions(ctx context.Context, clusterAddr string) ([]string, error)
 	CleanupStaleProxies(ctx context.Context, inactivityDuration time.Duration) error
 	GetAllProxies(ctx context.Context) ([]*proxy.Proxy, error)

management/server/store/store_mock.go

@@ -1870,6 +1870,20 @@ func (mr *MockStoreMockRecorder) GetAnyAccountID(ctx any) *gomock.Call {
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetAnyAccountID", reflect.TypeOf((*MockStore)(nil).GetAnyAccountID), ctx)
 }
 
+// GetClusterAllProxiesPrivate mocks base method.
+func (m *MockStore) GetClusterAllProxiesPrivate(ctx context.Context, clusterAddr string) *bool {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetClusterAllProxiesPrivate", ctx, clusterAddr)
+	ret0, _ := ret[0].(*bool)
+	return ret0
+}
+
+// GetClusterAllProxiesPrivate indicates an expected call of GetClusterAllProxiesPrivate.
+func (mr *MockStoreMockRecorder) GetClusterAllProxiesPrivate(ctx, clusterAddr any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetClusterAllProxiesPrivate", reflect.TypeOf((*MockStore)(nil).GetClusterAllProxiesPrivate), ctx, clusterAddr)
+}
+
 // GetClusterRequireSubdomain mocks base method.
 func (m *MockStore) GetClusterRequireSubdomain(ctx context.Context, clusterAddr string) *bool {
 	m.ctrl.T.Helper()