[management] Refuse to pin an agent network gateway onto another account's host (#7519)

An agent network bootstrap stores its cluster as proxy_address, which selects the proxy that serves the endpoint. An account-scoped proxy only receives its own account's mappings, so a pin onto a host another account's proxy declares can never be served, and the endpoint is immutable — a dead gateway until the account deletes its settings. Nothing refused that pin; the domain unique index only arbitrates between endpoints.

Both bootstrap paths now refuse, before the insert, a host that another account's proxy declares, a host another account has labeled pins beneath (self-addressed path), or a hostname that is another account's endpoint (labeled path).

Shared clusters are unaffected: shared proxies are never foreign, and labeled pins under one cluster are never asked about, so any number of accounts still pin beneath eu.proxy.netbird.io. Registration is deliberately unchanged — refusing a proxy for another account's pin would let a pin lock a tenant out after the reaper drops its rows.

management/server/store/sql_store.go

@@ -6471,6 +6471,25 @@ func (s *SqlStore) IsClusterAddressConflicting(ctx context.Context, clusterAddre
 	return count > 0, nil
 }
 
+// HasForeignAccountProxyAtHost reports whether a proxy owned by a different
+// account declares this host. Shared proxies (account_id IS NULL) are not
+// foreign: a shared cluster is what most accounts pin their agent network
+// gateway to. The match folds case because proxies declare their address as
+// the operator spelled it while the caller's host is normalised; that costs a
+// scan of the proxies table, taken once per account when its gateway is
+// bootstrapped, not on the per-connect path IsClusterAddressConflicting serves.
+func (s *SqlStore) HasForeignAccountProxyAtHost(ctx context.Context, host, accountID string) (bool, error) {
+	var count int64
+	result := s.db.
+		Model(&proxy.Proxy{}).
+		Where("LOWER(cluster_address) = LOWER(?) AND account_id IS NOT NULL AND account_id != ?", host, accountID).
+		Count(&count)
+	if result.Error != nil {
+		return false, status.Errorf(status.Internal, "check proxy host ownership: %v", result.Error)
+	}
+	return count > 0, nil
+}
+
 func (s *SqlStore) DeleteAccountCluster(ctx context.Context, clusterAddress, accountID string) error {
 	result := s.db.
 		Where("cluster_address = ? AND account_id = ?", clusterAddress, accountID).

management/server/store/sql_store_agentnetwork.go

@@ -315,6 +315,36 @@ func (s *SqlStore) GetAllAgentNetworkSettings(ctx context.Context, lockStrength
 	return settings, nil
 }
 
+// HasGatewayClusterPinnedByOtherAccount reports whether another account has a
+// labeled agent network gateway pinned beneath host, making host its cluster.
+// A self-addressed endpoint on the very same hostname is not counted: that
+// collision is the domain unique index's to refuse, as a conflict. Case-folded,
+// since a settings row written before hostnames were normalised may carry
+// capitals; one row per account, so the scan is cheap.
+func (s *SqlStore) HasGatewayClusterPinnedByOtherAccount(ctx context.Context, host, accountID string) (bool, error) {
+	return s.countGatewayRowsByOtherAccount(ctx, "LOWER(proxy_address) = LOWER(?) AND LOWER(domain) <> LOWER(proxy_address)", host, accountID)
+}
+
+// HasGatewayEndpointByOtherAccount reports whether host is another account's
+// agent network endpoint hostname (domain). Case-folded for the same reason as
+// HasGatewayClusterPinnedByOtherAccount.
+func (s *SqlStore) HasGatewayEndpointByOtherAccount(ctx context.Context, host, accountID string) (bool, error) {
+	return s.countGatewayRowsByOtherAccount(ctx, "LOWER(domain) = LOWER(?)", host, accountID)
+}
+
+func (s *SqlStore) countGatewayRowsByOtherAccount(ctx context.Context, predicate, host, accountID string) (bool, error) {
+	var count int64
+	result := s.db.
+		Model(&agentNetworkTypes.Settings{}).
+		Where(predicate+" AND account_id != ?", host, accountID).
+		Count(&count)
+	if result.Error != nil {
+		log.WithContext(ctx).Errorf("failed to check agent network gateway claims at host: %v", result.Error)
+		return false, status.Errorf(status.Internal, "check agent network gateway claims at host")
+	}
+	return count > 0, nil
+}
+
 // GetAgentNetworkSettingsByProxyAddress returns every Settings row whose
 // gateway is served by the proxy declaring the given cluster address. Used by
 // cluster-scoped synthesis to find the accounts a shared proxy serves.

management/server/store/store.go

@@ -342,6 +342,9 @@ type Store interface {
 	CountProxiesByAccountID(ctx context.Context, accountID string) (int64, error)
 	IsClusterAddressConflicting(ctx context.Context, clusterAddress, accountID string) (bool, error)
 	HasActiveProxyAtClusterAddress(ctx context.Context, clusterAddress string) (bool, error)
+	HasForeignAccountProxyAtHost(ctx context.Context, host, accountID string) (bool, error)
+	HasGatewayClusterPinnedByOtherAccount(ctx context.Context, host, accountID string) (bool, error)
+	HasGatewayEndpointByOtherAccount(ctx context.Context, host, accountID string) (bool, error)
 	DeleteAccountCluster(ctx context.Context, clusterAddress, accountID string) error
 
 	GetCustomDomainsCounts(ctx context.Context) (total int64, validated int64, err error)

management/server/store/store_mock.go

@@ -3065,6 +3065,51 @@ func (mr *MockStoreMockRecorder) HasActiveProxyAtClusterAddress(ctx, clusterAddr
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "HasActiveProxyAtClusterAddress", reflect.TypeOf((*MockStore)(nil).HasActiveProxyAtClusterAddress), ctx, clusterAddress)
 }
 
+// HasForeignAccountProxyAtHost mocks base method.
+func (m *MockStore) HasForeignAccountProxyAtHost(ctx context.Context, host, accountID string) (bool, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "HasForeignAccountProxyAtHost", ctx, host, accountID)
+	ret0, _ := ret[0].(bool)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// HasForeignAccountProxyAtHost indicates an expected call of HasForeignAccountProxyAtHost.
+func (mr *MockStoreMockRecorder) HasForeignAccountProxyAtHost(ctx, host, accountID any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "HasForeignAccountProxyAtHost", reflect.TypeOf((*MockStore)(nil).HasForeignAccountProxyAtHost), ctx, host, accountID)
+}
+
+// HasGatewayClusterPinnedByOtherAccount mocks base method.
+func (m *MockStore) HasGatewayClusterPinnedByOtherAccount(ctx context.Context, host, accountID string) (bool, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "HasGatewayClusterPinnedByOtherAccount", ctx, host, accountID)
+	ret0, _ := ret[0].(bool)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// HasGatewayClusterPinnedByOtherAccount indicates an expected call of HasGatewayClusterPinnedByOtherAccount.
+func (mr *MockStoreMockRecorder) HasGatewayClusterPinnedByOtherAccount(ctx, host, accountID any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "HasGatewayClusterPinnedByOtherAccount", reflect.TypeOf((*MockStore)(nil).HasGatewayClusterPinnedByOtherAccount), ctx, host, accountID)
+}
+
+// HasGatewayEndpointByOtherAccount mocks base method.
+func (m *MockStore) HasGatewayEndpointByOtherAccount(ctx context.Context, host, accountID string) (bool, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "HasGatewayEndpointByOtherAccount", ctx, host, accountID)
+	ret0, _ := ret[0].(bool)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// HasGatewayEndpointByOtherAccount indicates an expected call of HasGatewayEndpointByOtherAccount.
+func (mr *MockStoreMockRecorder) HasGatewayEndpointByOtherAccount(ctx, host, accountID any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "HasGatewayEndpointByOtherAccount", reflect.TypeOf((*MockStore)(nil).HasGatewayEndpointByOtherAccount), ctx, host, accountID)
+}
+
 // IncrementAgentNetworkConsumption mocks base method.
 func (m *MockStore) IncrementAgentNetworkConsumption(ctx context.Context, accountID string, kind types.ConsumptionDimension, dimID string, windowSeconds int64, windowStart time.Time, tokensIn, tokensOut int64, costUSD float64) error {
 	m.ctrl.T.Helper()