brave · arthuredelstein · Oct 20, 2022 · Sep 20, 2022 · Sep 30, 2022 · Oct 1, 2022
diff --git a/browser/about_flags.cc b/browser/about_flags.cc
@@ -205,6 +205,11 @@ constexpr char kBraveTorWindowsHttpsOnlyDescription[] =
     "Prevents Private Windows with Tor from making any insecure HTTP "
     "connections without warning the user first.";
 
+constexpr char kBraveRoundTimeStampsName[] = "Round time stamps";
+constexpr char kBraveRoundTimeStampsDescription[] =
+    "Prevents JavaScript from getting access to high-resolution clocks by "
+    "rounding all DOMHighResTimeStamps to the nearest millisecond.";
+
 constexpr char kBraveSpeedreaderName[] = "Enable SpeedReader";
 constexpr char kBraveSpeedreaderDescription[] =
     "Enables faster loading of simplified article-style web pages.";
@@ -717,6 +722,11 @@ constexpr char kBraveBackgroundVideoPlaybackDescription[] =
       flag_descriptions::kBraveTorWindowsHttpsOnlyDescription,              \
       kOsAll, FEATURE_VALUE_TYPE(                                           \
           blink::features::kBraveTorWindowsHttpsOnly)},                     \
+    {"brave-round-time-stamps",                                             \
+      flag_descriptions::kBraveRoundTimeStampsName,                         \
+      flag_descriptions::kBraveRoundTimeStampsDescription,                  \
+      kOsAll, FEATURE_VALUE_TYPE(                                           \
+          blink::features::kBraveRoundTimeStamps)},                         \
     BRAVE_IPFS_FEATURE_ENTRIES                                              \
     BRAVE_NATIVE_WALLET_FEATURE_ENTRIES                                     \
     BRAVE_NEWS_FEATURE_ENTRIES                                              \

diff --git a/browser/brave_shields/brave_timestamp_rounding_browsertest.cc b/browser/brave_shields/brave_timestamp_rounding_browsertest.cc
@@ -0,0 +1,72 @@
+/* Copyright (c) 2022 The Brave Authors. All rights reserved.
+ * 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/. */
+
+#include "base/test/scoped_feature_list.h"
+#include "base/test/task_environment.h"
+#include "base/time/time.h"
+#include "content/public/renderer/render_frame.h"
+#include "content/public/test/render_view_test.h"
+#include "third_party/blink/public/common/features.h"
+
+using blink::features::kBraveRoundTimeStamps;
+
+class BraveTimeStampRoundingRenderViewTest
+    : public content::RenderViewTest,
+      public ::testing::WithParamInterface<bool> {
+ public:
+  BraveTimeStampRoundingRenderViewTest() {}
+
+  ~BraveTimeStampRoundingRenderViewTest() override = default;
+
+  bool IsBraveRoundTimeStampsEnabled() { return GetParam(); }
+
+  void SetUp() override {
+    if (IsBraveRoundTimeStampsEnabled()) {
+      scoped_feature_list_.InitAndEnableFeature(kBraveRoundTimeStamps);
+    } else {
+      scoped_feature_list_.InitAndDisableFeature(kBraveRoundTimeStamps);
+    }
+    RenderViewTest::SetUp();
+  }
+
+  double ExecuteJSAndReturnDouble(const std::u16string& script) {
+    double result;
+    EXPECT_TRUE(ExecuteJavaScriptAndReturnNumberValue(script, &result));
+    return result;
+  }
+
+  void CheckRounded(const std::u16string& script, bool expect_rounded) {
+    double result = ExecuteJSAndReturnDouble(script);
+    if (expect_rounded) {
+      EXPECT_DOUBLE_EQ(round(result) - result, 0);
+    } else {
+      EXPECT_NE(round(result) - result, 0);
+    }
+  }
+
+  void Advance100Microseconds() {
+    task_environment_.AdvanceClock(base::Microseconds(100));
+  }
+
+ protected:
+  base::test::ScopedFeatureList scoped_feature_list_;
+};
+
+TEST_P(BraveTimeStampRoundingRenderViewTest, SynchronousApisRounded) {
+  bool expect_rounded = IsBraveRoundTimeStampsEnabled();
+  LoadHTML("<html><body>hi</body></html>");
+  Advance100Microseconds();
+  CheckRounded(u"performance.now()", expect_rounded);
+  Advance100Microseconds();
+  CheckRounded(u"performance.mark('test').startTime", expect_rounded);
+  Advance100Microseconds();
+  if (expect_rounded) {
+    CheckRounded(u"performance.timeOrigin", true);
+  }
+}
+
+INSTANTIATE_TEST_SUITE_P(BraveTimeStampRoundingRenderViewTest,
+                         BraveTimeStampRoundingRenderViewTest,
+                         ::testing::Bool());
@@ -54,13 +54,17 @@ const base::Feature kPartitionBlinkMemoryCache{
 const base::Feature kRestrictWebSocketsPool{"RestrictWebSocketsPool",
                                             base::FEATURE_ENABLED_BY_DEFAULT};
 
-// Disable protection against fingerprinting on screen dimensions by default.
+// Enables protection against fingerprinting on screen dimensions.
 const base::Feature kBraveBlockScreenFingerprinting{
     "BraveBlockScreenFingerprinting", base::FEATURE_DISABLED_BY_DEFAULT};
 
-// Enable HTTPS-Only Mode in Private Windows with Tor by default.
+// Enables HTTPS-Only Mode in Private Windows with Tor by default.
 const base::Feature kBraveTorWindowsHttpsOnly{"BraveTorWindowsHttpsOnly",
                                               base::FEATURE_ENABLED_BY_DEFAULT};
 
+// Enables protection against fingerprinting via high-resolution time stamps.
+const base::Feature kBraveRoundTimeStamps{"BraveRoundTimeStamps",
+                                          base::FEATURE_ENABLED_BY_DEFAULT};
+
 }  // namespace features
 }  // namespace blink
@@ -18,6 +18,7 @@ BLINK_COMMON_EXPORT extern const base::Feature kPartitionBlinkMemoryCache;
 BLINK_COMMON_EXPORT extern const base::Feature kRestrictWebSocketsPool;
 BLINK_COMMON_EXPORT extern const base::Feature kBraveBlockScreenFingerprinting;
 BLINK_COMMON_EXPORT extern const base::Feature kBraveTorWindowsHttpsOnly;
+BLINK_COMMON_EXPORT extern const base::Feature kBraveRoundTimeStamps;
 
 }  // namespace features
 }  // namespace blink

@@ -0,0 +1,25 @@
+/* Copyright (c) 2022 The Brave Authors. All rights reserved.
+ * 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/. */
+
+#include "third_party/blink/renderer/core/loader/document_load_timing.h"
+
+#define MonotonicTimeToZeroBasedDocumentTime \
+  MonotonicTimeToZeroBasedDocumentTime_ChromiumImpl
+
+#include "src/third_party/blink/renderer/core/loader/document_load_timing.cc"
+
+#undef MonotonicTimeToZeroBasedDocumentTime
+
+#include "third_party/blink/renderer/core/timing/time_clamper.h"
+
+namespace blink {
+
+base::TimeDelta DocumentLoadTiming::MonotonicTimeToZeroBasedDocumentTime(
+    base::TimeTicks monotonic_time) const {
+  return TimeClamper::MaybeRoundTimeDelta(
+      MonotonicTimeToZeroBasedDocumentTime_ChromiumImpl(monotonic_time));
+}
+
+}  // namespace blink
@@ -0,0 +1,17 @@
+/* Copyright (c) 2022 The Brave Authors. All rights reserved.
+ * 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/. */
+
+#ifndef BRAVE_CHROMIUM_SRC_THIRD_PARTY_BLINK_RENDERER_CORE_LOADER_DOCUMENT_LOAD_TIMING_H_
+#define BRAVE_CHROMIUM_SRC_THIRD_PARTY_BLINK_RENDERER_CORE_LOADER_DOCUMENT_LOAD_TIMING_H_
+
+#define MonotonicTimeToZeroBasedDocumentTime                   \
+  MonotonicTimeToZeroBasedDocumentTime(base::TimeTicks) const; \
+  base::TimeDelta MonotonicTimeToZeroBasedDocumentTime_ChromiumImpl
+
+#include "src/third_party/blink/renderer/core/loader/document_load_timing.h"
+
+#undef MonotonicTimeToZeroBasedDocumentTime
+
+#endif  // BRAVE_CHROMIUM_SRC_THIRD_PARTY_BLINK_RENDERER_CORE_LOADER_DOCUMENT_LOAD_TIMING_H_
@@ -0,0 +1,56 @@
+/* Copyright (c) 2022 The Brave Authors. All rights reserved.
+ * 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/. */
+
+#include "third_party/blink/renderer/core/timing/time_clamper.h"
+
+#define kFineResolutionMicroseconds FineResolutionMicroseconds()
+#define kCoarseResolutionMicroseconds CoarseResolutionMicroseconds()
+
+#include "src/third_party/blink/renderer/core/timing/time_clamper.cc"
+
+#undef FineResolutionMicroseconds
+#undef CoarseResolutionMicroseconds
+
+#include "base/feature_list.h"
+#include "base/time/time.h"
+#include "third_party/blink/public/common/features.h"
+
+namespace blink {
+
+namespace {
+
+constexpr int kBraveTimerResolutionMicroseconds = 1000;
+
+bool ShouldRound() {
+  return base::FeatureList::IsEnabled(features::kBraveRoundTimeStamps);
+}
+
+}  // namespace
+
+// static
+double TimeClamper::MaybeRoundMilliseconds(double value) {
+  return ShouldRound() ? round(value) : value;
+}
+
+// static
+base::TimeDelta TimeClamper::MaybeRoundTimeDelta(base::TimeDelta value) {
+  return ShouldRound() ? value.RoundToMultiple(base::Microseconds(
+                             kBraveTimerResolutionMicroseconds))
+                       : value;
+}
+
+// static
+int TimeClamper::FineResolutionMicroseconds() {
+  return ShouldRound() ? kBraveTimerResolutionMicroseconds
+                       : kFineResolutionMicroseconds_ChromiumImpl;
+}
+
+// static
+int TimeClamper::CoarseResolutionMicroseconds() {
+  return ShouldRound() ? kBraveTimerResolutionMicroseconds
+                       : kCoarseResolutionMicroseconds_ChromiumImpl;
+}
+
+}  // namespace blink
@@ -0,0 +1,28 @@
+/* Copyright (c) 2022 The Brave Authors. All rights reserved.
+ * 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/. */
+
+#ifndef BRAVE_CHROMIUM_SRC_THIRD_PARTY_BLINK_RENDERER_CORE_TIMING_TIME_CLAMPER_H_
+#define BRAVE_CHROMIUM_SRC_THIRD_PARTY_BLINK_RENDERER_CORE_TIMING_TIME_CLAMPER_H_
+
+#include "base/time/time.h"
+
+// Any future usages of kCoarseResolutionMicroseconds or
+// kFineResolutionMicroseconds won't compile and will need to be fixed.
+#define kCoarseResolutionMicroseconds kCoarseResolutionMicroseconds_ChromiumImpl
+
+#define kFineResolutionMicroseconds                                  \
+  kFineResolutionMicroseconds_ChromiumImpl = 5;                      \
+  static int CoarseResolutionMicroseconds();                         \
+  static int FineResolutionMicroseconds();                           \
+  static double MaybeRoundMilliseconds(double value);                \
+  static base::TimeDelta MaybeRoundTimeDelta(base::TimeDelta value); \
+  int dummy
+
+#include "src/third_party/blink/renderer/core/timing/time_clamper.h"
+
+#undef kCoarseResolutionMicroseconds
+#undef kFineResolutionMicroseconds
+
+#endif  // BRAVE_CHROMIUM_SRC_THIRD_PARTY_BLINK_RENDERER_CORE_TIMING_TIME_CLAMPER_H_
@@ -0,0 +1,20 @@
+/* Copyright (c) 2022 The Brave Authors. All rights reserved.
+ * 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/. */
+
+#include "third_party/blink/renderer/modules/video_rvfc/video_frame_callback_requester_impl.h"
+
+#define kCoarseResolution kCoarseResolution [[maybe_unused]]
+
+#define FloorToMultiple(X) \
+  FloorToMultiple(         \
+      base::Microseconds(TimeClamper::CoarseResolutionMicroseconds()))
+
+#define static_assert(...) static_assert(true)
+
+#include "src/third_party/blink/renderer/modules/video_rvfc/video_frame_callback_requester_impl.cc"
+
+#undef kCoarseResolution
+#undef FloorToMultiple
+#undef static_assert
diff --git a/test/BUILD.gn b/test/BUILD.gn
@@ -724,6 +724,7 @@ test("brave_browser_tests") {
     "//brave/browser/brave_shields/ad_block_service_browsertest.cc",
     "//brave/browser/brave_shields/ad_block_service_browsertest.h",
     "//brave/browser/brave_shields/brave_shields_web_contents_observer_browsertest.cc",
+    "//brave/browser/brave_shields/brave_timestamp_rounding_browsertest.cc",
     "//brave/browser/brave_shields/cookie_expiry_browsertest.cc",
     "//brave/browser/brave_shields/cookie_pref_service_browsertest.cc",
     "//brave/browser/brave_shields/domain_block_page_browsertest.cc",

diff --git a/test/filters/browser_tests-linux.filter b/test/filters/browser_tests-linux.filter
@@ -17,13 +17,15 @@
 -ExternalProtocolHandlerSandboxBrowserTest.*
 -IndividualNetworkContextsPrefetchProxyBrowserTest.*
 -LayoutInstabilityTest.*
+-MetricIntegrationTest.FirstInputDelay
 -MultiscreenWindowPlacementPermissionContextTest.IsExtendedCrossOriginAllow
 -MultiscreenWindowPlacementPermissionContextTest.IsExtendedCrossOriginDeny
 -MultiscreenWindowPlacementPermissionContextTest.IsExtendedSameOriginAllow
 -NewTabUIBrowserTest.*
 -NewTabUIProcessPerTabTest.*
 -OzonePlatformTest.*
 -PolicyTestPrefetchProxyBrowserTest.*
+-PolicyTestSetTimeoutWithout1MsClamp.DisablePolicy
 -PPAPINaClPNaClNonSfiTest.*
 -PrefetchProxyBrowserTest.*
 -PrefetchProxyWithDecoyRequestsBrowserTest.*