commit 76464d08572d04c7f1ad0516008b2efb9c7f5a69
parent c83fe48d8f341c62e0f20eebf1e5909d7ce78157
Author: Tom Ritter <tom@mozilla.com>
Date: Mon, 8 Dec 2025 16:31:02 +0000
Bug 1873716: Update the heuristics used to identify different fingerprinters r=timhuang
SKIP_BMO_CHECK
Differential Revision: https://phabricator.services.mozilla.com/D274379
Diffstat:
1 file changed, 77 insertions(+), 41 deletions(-)
diff --git a/toolkit/components/resistfingerprinting/nsRFPService.cpp b/toolkit/components/resistfingerprinting/nsRFPService.cpp
@@ -2078,7 +2078,8 @@ CanvasUsage CanvasUsage::CreateUsage(
CanvasFeatureUsage featureUsage = CanvasFeatureUsage::None;
// Only 2D contexts currently expose feature usage metrics.
- if (aContextType == dom::CanvasContextType::Canvas2D && aContext) {
+ if (aContext && (aContextType == dom::CanvasContextType::Canvas2D ||
+ aContextType == dom::CanvasContextType::OffscreenCanvas2D)) {
// Downcast is safe because 2D contexts derive from
// nsICanvasRenderingContextInternal and we gated on the supplied type. The
// header is included so the relationship is known to the compiler.
@@ -2090,7 +2091,6 @@ CanvasUsage CanvasUsage::CreateUsage(
CanvasUsage::GetCanvasUsageSource(aIsOffscreen, aContextType, aApi);
return CanvasUsage(aSize, aContextType, usageSource, featureUsage);
}
-
CanvasUsageSource CanvasUsage::GetCanvasUsageSource(
bool isOffscreen, dom::CanvasContextType contextType,
CanvasExtractionAPI api) {
@@ -2312,52 +2312,64 @@ static void MaybeCurrentCaller(nsACString& aFilename, uint32_t& aLineNum,
return;
}
- uint32_t extractedWebGL = 0;
+ bool extractedWebGL = false;
bool seenExtractedWebGL_300x150 = false;
+ bool seenExtractedWebGL_2000x200 = false;
uint32_t extracted2D = 0;
- bool seenExtracted2D_16x16 = false;
bool seenExtracted2D_122x110 = false;
+ bool seenExtracted2D_220x30 = false;
bool seenExtracted2D_240x60 = false;
- bool seenExtracted2D_280x60 = false;
+ bool seenExtracted2D_250x80 = false;
+ bool seenExtracted2D_300x100 = false;
+ bool seenExtracted2D_650x12 = false;
bool seenExtracted2D_860x6 = false;
+
CanvasFeatureUsage accumulatedFeatureUsage = CanvasFeatureUsage::None;
CanvasUsageSource accumulatedUsageSource = CanvasUsageSource::Unknown;
- uint32_t extractedOther = 0;
+ MOZ_LOG(
+ gFingerprinterDetection, LogLevel::Debug,
+ ("MaybeReportCanvasFingerprinter: examining %zu uses", aUses.Length()));
for (const auto& usage : aUses) {
int32_t width = usage.mSize.width;
int32_t height = usage.mSize.height;
- if (width > 2000 || height > 1000) {
+ if (width > 2500 || height > 1000) {
// Canvases used for fingerprinting are usually relatively small.
continue;
}
+ accumulatedFeatureUsage |= usage.mFeatureUsage;
accumulatedUsageSource |= usage.mUsageSource;
- if (usage.mType == dom::CanvasContextType::Canvas2D) {
+ if (usage.mType == dom::CanvasContextType::Canvas2D ||
+ usage.mType == dom::CanvasContextType::OffscreenCanvas2D) {
accumulatedFeatureUsage |= usage.mFeatureUsage;
extracted2D++;
- if (width == 16 && height == 16) {
- seenExtracted2D_16x16 = true;
+ if (width == 122 && height == 110) {
+ seenExtracted2D_122x110 = true;
+ } else if (width == 220 && height == 30) {
+ seenExtracted2D_220x30 = true;
} else if (width == 240 && height == 60) {
seenExtracted2D_240x60 = true;
- } else if (width == 122 && height == 110) {
- seenExtracted2D_122x110 = true;
- } else if (width == 280 && height == 60) {
- seenExtracted2D_280x60 = true;
+ } else if (width == 250 && height == 80) {
+ seenExtracted2D_250x80 = true;
+ } else if (width == 300 && height == 100) {
+ seenExtracted2D_300x100 = true;
+ } else if (width == 650 && height == 12) {
+ seenExtracted2D_650x12 = true;
} else if (width == 860 && height == 6) {
seenExtracted2D_860x6 = true;
}
} else if (usage.mType == dom::CanvasContextType::WebGL1) {
- extractedWebGL++;
+ extractedWebGL = true;
if (width == 300 && height == 150) {
seenExtractedWebGL_300x150 = true;
+ } else if (width == 2000 && height == 200) {
+ seenExtractedWebGL_2000x200 = true;
}
- } else {
- extractedOther++;
}
}
@@ -2368,15 +2380,40 @@ static void MaybeCurrentCaller(nsACString& aFilename, uint32_t& aLineNum,
if (seenExtractedWebGL_300x150 && seenExtracted2D_240x60 &&
seenExtracted2D_122x110) {
fingerprinter = CanvasFingerprinterAlias::eFingerprintJS;
- } else if (seenExtractedWebGL_300x150 && seenExtracted2D_280x60 &&
- seenExtracted2D_16x16) {
+ } else if (seenExtractedWebGL_300x150 &&
+ accumulatedFeatureUsage & CanvasFeatureUsage::KnownText_12 &&
+ accumulatedFeatureUsage & CanvasFeatureUsage::KnownText_13) {
fingerprinter = CanvasFingerprinterAlias::eAkamai;
+ } else if (accumulatedFeatureUsage & CanvasFeatureUsage::KnownText_9 &&
+ accumulatedFeatureUsage & CanvasFeatureUsage::KnownText_10 &&
+ accumulatedFeatureUsage & CanvasFeatureUsage::KnownText_11) {
+ fingerprinter = CanvasFingerprinterAlias::eOzoki;
+ } else if (seenExtractedWebGL_2000x200 && knownTextBitmask == 0) {
+ fingerprinter = CanvasFingerprinterAlias::ePerimeterX;
+ } else if (seenExtracted2D_220x30 &&
+ accumulatedFeatureUsage & CanvasFeatureUsage::KnownText_7) {
+ fingerprinter = CanvasFingerprinterAlias::eSignifyd;
+ } else if (seenExtracted2D_300x100 &&
+ accumulatedFeatureUsage & CanvasFeatureUsage::KnownText_8) {
+ fingerprinter = CanvasFingerprinterAlias::eSignifyd;
+ } else if (seenExtracted2D_240x60 &&
+ accumulatedFeatureUsage & CanvasFeatureUsage::KnownText_4) {
+ fingerprinter = CanvasFingerprinterAlias::eClaydar;
+ } else if (accumulatedFeatureUsage & CanvasFeatureUsage::KnownText_23) {
+ fingerprinter = CanvasFingerprinterAlias::eForter;
+ } else if (seenExtracted2D_250x80 &&
+ accumulatedFeatureUsage & CanvasFeatureUsage::KnownText_6) {
+ fingerprinter = CanvasFingerprinterAlias::eVariant5;
+ } else if (seenExtracted2D_650x12) {
+ fingerprinter = CanvasFingerprinterAlias::eVariant6;
+ } else if (seenExtracted2D_860x6) {
+ fingerprinter = CanvasFingerprinterAlias::eVariant7;
} else if (seenExtractedWebGL_300x150 && extracted2D > 0 &&
(accumulatedFeatureUsage & CanvasFeatureUsage::SetFont)) {
fingerprinter = CanvasFingerprinterAlias::eVariant1;
} else if (extractedWebGL > 0 && extracted2D > 1 && seenExtracted2D_860x6) {
fingerprinter = CanvasFingerprinterAlias::eVariant2;
- } else if (extractedOther > 0 && (extractedWebGL > 0 || extracted2D > 0)) {
+ } else if (extractedWebGL > 0 || extracted2D > 0) {
fingerprinter = CanvasFingerprinterAlias::eVariant3;
} else if (extracted2D > 0 &&
(accumulatedFeatureUsage & CanvasFeatureUsage::SetFont) &&
@@ -2384,36 +2421,35 @@ static void MaybeCurrentCaller(nsACString& aFilename, uint32_t& aLineNum,
(CanvasFeatureUsage::FillRect | CanvasFeatureUsage::LineTo |
CanvasFeatureUsage::Stroke))) {
fingerprinter = CanvasFingerprinterAlias::eVariant4;
- } else if (extractedOther + extractedWebGL + extracted2D > 1) {
- // This I added primarily to not miss anything, but it can cause false
- // positives.
- fingerprinter = CanvasFingerprinterAlias::eMaybe;
- }
-
- if (knownTextBitmask == 0 && fingerprinter == eNoneIdentified) {
- return;
}
- auto event =
- CanvasFingerprintingEvent(fingerprinter, knownTextBitmask, aSource);
-
+ nsAutoCString uri(aURI);
+ nsAutoCString origin(aOriginNoSuffix);
+ nsAutoCString filename;
if (MOZ_LOG_TEST(gFingerprinterDetection, LogLevel::Info)) {
- nsAutoCString filename;
uint32_t lineNum = 0;
uint32_t columnNum = 0;
MaybeCurrentCaller(filename, lineNum, columnNum);
+ }
- nsAutoCString origin(aOriginNoSuffix);
- MOZ_LOG(
- gFingerprinterDetection, LogLevel::Info,
- ("Detected a potential canvas fingerprinter on %s in script %s:%d:%d "
- "(KnownFingerprintTextBitmask: %u, CanvasFingerprinterAlias: %s, "
- "CanvasUsageSource: %s)",
- origin.get(), filename.get(), lineNum, columnNum, knownTextBitmask,
- CanvasFingerprinterToString(fingerprinter),
- CanvasUsageSourceToString(aSource)));
+ if (knownTextBitmask == 0 && fingerprinter == eNoneIdentified) {
+ MOZ_LOG(gFingerprinterDetection, LogLevel::Debug,
+ ("Found no potential canvas fingerprinter on %s on %s in script %s",
+ origin.get(), uri.get(), filename.get()));
+ return;
}
+ auto event = CanvasFingerprintingEvent(fingerprinter, knownTextBitmask,
+ accumulatedUsageSource);
+
+ MOZ_LOG(gFingerprinterDetection, LogLevel::Info,
+ ("Detected a potential canvas fingerprinter on %s on %s in script %s "
+ "(KnownFingerprintTextBitmask: %u, CanvasFingerprinterAlias: %s, "
+ "AccumulatedCanvasUsageSource: %s)",
+ origin.get(), uri.get(), filename.get(), knownTextBitmask,
+ CanvasFingerprinterToString(fingerprinter),
+ CanvasUsageSourceToString(accumulatedUsageSource).get()));
+
ContentBlockingNotifier::OnEvent(
aChannel, false,
nsIWebProgressListener::STATE_ALLOWED_CANVAS_FINGERPRINTING, origin,
