1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
|
/** \file
* \brief Wrappers for navigator.deviceMemory property
*
* \see https://xhr.spec.whatwg.org/
*
* \author Copyright (C) 2019 Libor Polcak
* \author Copyright (C) 2021 Matus Svancar
*
* \license SPDX-License-Identifier: GPL-3.0-or-later
* \license SPDX-License-Identifier: MPL-2.0
*/
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
//
// Alternatively, the contents of this file may be used under the terms
// of the Mozilla Public License, v. 2.0, as described below:
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.
//
// \copyright Copyright (c) 2020 The Brave Authors.
/** \file
* This file contains a wrapper for [navigator.deviceMemory](https://developer.mozilla.org/en-US/docs/Web/API/Navigator/deviceMemory).
* \ingroup wrappers
*
* The goal is to prevent fingerprinting by modifying the return value of the `navigator.deviceMemory` parameter.
*
* This wrapper operates with three levels of protection:
*
* * (0) - return random valid value from range [0.25 - real value]
* * (1) - return random valid value from range [0.25 - 8]
* * (2) - return 4
*
* These approaches are inspired by the algorithms created by [Brave Software](https://brave.com)
* available [here](https://github.com/brave/brave-core/blob/master/chromium_src/third_party/blink/renderer/core/frame/navigator_device_memory.cc).
*
*/
/*
* Create private namespace
*/
(function() {
var wrappers = [
{
parent_object: "Navigator.prototype",
parent_object_property: "deviceMemory",
wrapped_objects: [],
helping_code: `
let dm_prng = alea(domainHash, "navigator.deviceMemory");
var validValues = [0.25, 0.5, 1.0, 2.0, 4.0, 8.0];
var ret = 4;
var realValue = navigator.deviceMemory;
if(args[0]!=2 && realValue==0.25){
ret = realValue;
}
else if(args[0]==0){
var maxIndex = validValues.indexOf(realValue);
if(maxIndex == -1){
maxIndex = validValues.length-1;
}
ret = validValues[Math.floor((dm_prng()*(maxIndex+1)))];
}
else if(args[0]==1){
ret = validValues[Math.floor(dm_prng()*(validValues.length))];
}
`,
post_wrapping_code: [
{
code_type: "object_properties",
parent_object: "Navigator.prototype",
parent_object_property: "deviceMemory",
wrapped_objects: [],
/** \brief replaces navigator.deviceMemory getter
*
* Depending on level chosen this property returns:
* * (0) - random valid value from range [0.25 - real value]
* * (1) - random valid value from range [0.25 - 8]
* * (2) - 4
*/
wrapped_properties: [
{
property_name: "get",
property_value: `
function() {
return ret;
}`,
},
],
}
],
},
]
add_wrappers(wrappers);
})();
|