Bluetooth: Introduce HCI_CONN_FLAG_DEVICE_PRIVACY device flag

This introduces HCI_CONN_FLAG_DEVICE_PRIVACY which can be used by
userspace to indicate to the controller to use Device Privacy Mode to a
specific device.
Signed-off-by: NLuiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/hci_core.h

@@ -154,6 +154,7 @@ struct bdaddr_list_with_irk {
 
 enum hci_conn_flags {
 	HCI_CONN_FLAG_REMOTE_WAKEUP,
+	HCI_CONN_FLAG_DEVICE_PRIVACY,
 
 	__HCI_CONN_NUM_FLAGS,
 };
@@ -1466,6 +1467,9 @@ void hci_conn_del_sysfs(struct hci_conn *conn);
 #define use_ll_privacy(dev) (ll_privacy_capable(dev) && \
 			     hci_dev_test_flag(dev, HCI_ENABLE_LL_PRIVACY))
 
+#define privacy_mode_capable(dev) (use_ll_privacy(dev) && \
+				   (hdev->commands[39] & 0x04))
+
 /* Use enhanced synchronous connection if command is supported */
 #define enhanced_sco_capable(dev) ((dev)->commands[29] & 0x08)
 

net/bluetooth/mgmt.c

@@ -3978,6 +3978,11 @@ static int exp_ll_privacy_feature_changed(bool enabled, struct hci_dev *hdev,
 	memcpy(ev.uuid, rpa_resolution_uuid, 16);
 	ev.flags = cpu_to_le32((enabled ? BIT(0) : 0) | BIT(1));
 
+	if (enabled && privacy_mode_capable(hdev))
+		set_bit(HCI_CONN_FLAG_DEVICE_PRIVACY, hdev->conn_flags);
+	else
+		clear_bit(HCI_CONN_FLAG_DEVICE_PRIVACY, hdev->conn_flags);
+
 	return mgmt_limited_event(MGMT_EV_EXP_FEATURE_CHANGED, hdev,
 				  &ev, sizeof(ev),
 				  HCI_MGMT_EXP_FEATURE_EVENTS, skip);
@@ -4461,6 +4466,13 @@ static int set_device_flags(struct sock *sk, struct hci_dev *hdev, void *data,
 		if (params) {
 			bitmap_from_u64(params->flags, current_flags);
 			status = MGMT_STATUS_SUCCESS;
+
+			/* Update passive scan if HCI_CONN_FLAG_DEVICE_PRIVACY
+			 * has been set.
+			 */
+			if (test_bit(HCI_CONN_FLAG_DEVICE_PRIVACY,
+				     params->flags))
+				hci_update_passive_scan(hdev);
 		} else {
 			bt_dev_warn(hdev, "No such LE device %pMR (0x%x)",
 				    &cp->addr.bdaddr,