118 lines
4.1 KiB
JavaScript
118 lines
4.1 KiB
JavaScript
/** \file
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* \brief This file contains wrappers for the original Virtual Reality API
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*
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* \see https://immersive-web.github.io/webvr/spec/1.1/
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*
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* \author Copyright (C) 2021 Libor Polcak
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*
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* \license SPDX-License-Identifier: GPL-3.0-or-later
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*/
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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//
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/** \file
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* \ingroup wrappers
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*
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* navigator.activeVRDisplays() allows any page script to learn the VR
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* displays attached to the computer.
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*
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* U. Iqbal, S. Englehardt and Z. Shafiq, "Fingerprinting the
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* Fingerprinters: Learning to Detect Browser Fingerprinting Behaviors,"
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* in 2021 2021 IEEE Symposium on Security and Privacy (SP), San Francisco,
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* CA, US, 2021 pp. 283-301 observed
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* (https://github.com/uiowa-irl/FP-Inspector/blob/master/Data/potential_fingerprinting_APIs.md)
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* that the interface is used in the wild to fingerprint users. As it is
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* likely that only a minority of users have a VR display connected and the API
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* provides additional information on the HW, it is likely that users with
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* a VR display connected are easily fingerprintable.
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*
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* As we expect that the majority of the users does not have a VR display
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* connected, we provide only a single mitigation - the wrapped APIs returns
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* an empty list.
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*
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* \bug The standard provides events *vrdisplayconnect*, *vrdisplaydisconnect*
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* *vrdisplayactivate* and *vrdisplaydeactivate* that fires at least on the
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* window object. We do not mitigate the event to fire and consequently, it is
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* possible that an adversary can learn that a VR display was (dis)connected but
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* there was no change in the result of the navigator.activeVRDisplays() API.
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*
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* The VRFrameData object carries a timestamp. As we allow wrapping of several
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* ways to obtain timestamps, we need to provide the same precision for the
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* VRFrameData object.
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*/
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(function() {
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var remember_past_ts_values = `var precision = args[0];
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var doNoise = args[1];
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var pastValues = {};
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${rounding_function}
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${noise_function}
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var mitigationF = rounding_function;
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if (doNoise === true){
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mitigationF = function(value, precision) {
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let params = [value, precision];
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if (params in pastValues) {
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return pastValues[params];
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}
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let result = noise_function(...params);
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pastValues[params] = result;
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return result;
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}
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}
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`;
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var wrappers = [
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{
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parent_object: "Navigator.prototype",
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parent_object_property: "activeVRDisplays",
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wrapped_objects: [],
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helping_code: "",
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wrapping_function_body: `
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return Promise.resolve(new window.Array());
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`,
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},
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{
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/**
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* \see https://developer.mozilla.org/en-US/docs/Web/API/VRFrameData/timestamp
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* \note that at the time of the writing of the prototype, we did not have
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* access to a VR display and this code was not tested.
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*/
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parent_object: "VRFrameData.prototype",
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parent_object_property: "timestamp",
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wrapped_objects: [],
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helping_code: remember_past_ts_values + `let origGet = Object.getOwnPropertyDescriptor(VRFrameData.prototype, "timestamp").get`,
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post_wrapping_code: [
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{
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code_type: "object_properties",
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parent_object: "VRFrameData.prototype",
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parent_object_property: "timestamp",
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wrapped_objects: [],
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/** \brief replaces VRFrameData.timestamp getter to create
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* a timestamp with the desired precision.
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*/
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wrapped_properties: [
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{
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property_name: "get",
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property_value: `
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function() {
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return mitigationF(origGet.call(this), precision);
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}`,
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},
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],
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}
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],
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},
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]
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add_wrappers(wrappers);
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})()
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