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at 2024-04-08T20:10:54+00:00

Bug 41901: Hardcode normalized FontSubstitutes.

Windows has a system to set font aliases through the registry.
This allows some customization that could be used as a fingerprinting
vector.
Moreover, this mechanism is used by Windows itself, and different SKUs
might have different default FontSubstitutes.

@@ -199,3 +199,68 @@ static const char* kLangPackFonts[] = {
  //  "Rockwell Nova",  // Pan-European Supplemental Fonts - EXCLUDED
  //  "Verdana Pro",  // Pan-European Supplemental Fonts - EXCLUDED
  };
++
 +struct FontSubstitute {
 +  const char *substituteName;
 +  const char *actualFontName;
 +};
++
 +static const FontSubstitute kFontSubstitutes[] = {
 +  // Common substitutions
 +  {"Arabic Transparent", "Arial"},
 +  {"Arabic Transparent Bold", "Arial Bold"},
 +  {"Arial Baltic", "Arial"},
 +  {"Arial CE", "Arial"},
 +  {"Arial CYR", "Arial"},
 +  {"Arial Greek", "Arial"},
 +  {"Arial TUR", "Arial"},
 +  {"Courier New Baltic", "Courier New"},
 +  {"Courier New CE", "Courier New"},
 +  {"Courier New CYR", "Courier New"},
 +  {"Courier New Greek", "Courier New"},
 +  {"Courier New TUR", "Courier New"},
 +  {"Helv", "MS Sans Serif"},
 +  {"Helvetica", "Arial"},
 +  {"MS Shell Dlg 2", "Tahoma"},
 +  {"Tahoma Armenian", "Tahoma"},
 +  {"Times", "Times New Roman"},
 +  {"Times New Roman Baltic", "Times New Roman"},
 +  {"Times New Roman CE", "Times New Roman"},
 +  {"Times New Roman CYR", "Times New Roman"},
 +  {"Times New Roman Greek", "Times New Roman"},
 +  {"Times New Roman TUR", "Times New Roman"},
 +  {"Tms Rmn", "MS Serif"},
 +  // Common, except Japanese (which uses MS UI Gothic, instead)
 +  {"MS Shell Dlg", "Microsoft Sans Serif"},
 +  // Arabic
 +  {"Arial (Arabic)", "Arial"},
 +  {"Courier New (Arabic)", "Courier New"},
 +  {"Times New Roman (Arabic)", "Times New Roman"},
 +  // Cyrillic + Greek
 +  {"Courier", "Courier New"},
 +  // Greek
 +  {"Fixedsys Greek", "Fixedsys"},
 +  {"MS Serif Greek", "MS Serif"},
 +  {"MS Sans Serif Greek", "MS Sans Serif"},
 +  {"Small Fonts Greek", "Small Fonts"},
 +  {"System Greek", "System"},
 +  // Hebrew
 +  {"Arial (Hebrew)", "Arial"},
 +  {"Courier New (Hebrew)", "Courier New"},
 +  {"David Transparent", "David"},
 +  {"Fixed Miriam Transparent", "Miriam Fixed"},
 +  {"Miriam Transparent", "Miriam"},
 +  {"Rod Transparent", "Rod"},
 +  {"Times New Roman (Hebrew)", "Times New Roman"},
 +  // Japanese
 +  {"標準明朝", "ＭＳ 明朝"},
 +  {"標準ゴシック", "ＭＳ ゴシック"},
 +  {"ゴシック", "ＭＳ ゴシック"},
 +  {"ｺﾞｼｯｸ", "ＭＳ ゴシック"},
 +  {"ｸｰﾘｴ", "Courier"},
 +  {"ﾀｲﾑｽﾞﾛﾏﾝ", "Times New Roman"},
 +  {"ﾍﾙﾍﾞﾁｶ", "Arial"},
 +  // Simplified Chinese
 +  {"FangSong_GB2312", "FangSong"},
 +  {"KaiTi_GB2312", "KaiTi"},
 +};

@@ -1923,6 +1923,20 @@ static void RemoveCharsetFromFontSubstitute(nsACString& aName) {
  #define MAX_VALUE_DATA 512
  nsresult gfxDWriteFontList::GetFontSubstitutes() {
 +  if (nsContentUtils::ShouldResistFingerprinting(
 +          "Ignore any fingerprintable user font customization and normalize "
 +          "font substitutes across different Windows SKUs.",
 +          RFPTarget::Unknown)) {
 +    for (const FontSubstitute& fs : kFontSubstitutes) {
 +      nsAutoCString substituteName(fs.substituteName);
 +      nsAutoCString actualFontName(fs.actualFontName);
 +      BuildKeyNameFromFontName(substituteName);
 +      BuildKeyNameFromFontName(actualFontName);
 +      AddSubstitute(substituteName, actualFontName);
 +    }
 +    return NS_OK;
 +  }
++
    HKEY hKey;
    DWORD i, rv, lenAlias, lenActual, valueType;
    WCHAR aliasName[MAX_VALUE_NAME];
@@ -1957,39 +1971,46 @@ nsresult gfxDWriteFontList::GetFontSubstitutes() {
      BuildKeyNameFromFontName(substituteName);
      RemoveCharsetFromFontSubstitute(actualFontName);
      BuildKeyNameFromFontName(actualFontName);
 -    if (SharedFontList()) {
 -      // Skip substitution if the original font is available, unless the option
 -      // to apply substitutions unconditionally is enabled.
 -      if (!StaticPrefs::gfx_windows_font_substitutes_always_AtStartup()) {
 -        // Font substitutions are recorded for the canonical family names; we
 -        // don't need FindFamily to consider localized aliases when searching.
 -        if (SharedFontList()->FindFamily(substituteName,
 -                                         /*aPrimaryNameOnly*/ true)) {
 -          continue;
 -        }
 -      }
 -      if (SharedFontList()->FindFamily(actualFontName,
 +    AddSubstitute(substituteName, actualFontName);
 +  }
++
 +  return NS_OK;
 +}
++
 +void gfxDWriteFontList::AddSubstitute(const nsCString& substituteName,
 +                                      const nsCString& actualFontName) {
 +  if (SharedFontList()) {
 +    // Skip substitution if the original font is available, unless the
 +    // option to apply substitutions unconditionally is enabled.
 +    if (!StaticPrefs::gfx_windows_font_substitutes_always_AtStartup()) {
 +      // Font substitutions are recorded for the canonical family names;
 +      // we don't need FindFamily to consider localized aliases when
 +      // searching.
 +      if (SharedFontList()->FindFamily(substituteName,
                                         /*aPrimaryNameOnly*/ true)) {
 -        mSubstitutions.InsertOrUpdate(substituteName,
 -                                      MakeUnique<nsCString>(actualFontName));
 -      } else if (mSubstitutions.Get(actualFontName)) {
 -        mSubstitutions.InsertOrUpdate(
 -            substituteName,
 -            MakeUnique<nsCString>(*mSubstitutions.Get(actualFontName)));
 -      } else {
 -        mNonExistingFonts.AppendElement(substituteName);
 +        return;
+       }
 +    }
 +    if (SharedFontList()->FindFamily(actualFontName,
 +                                     /*aPrimaryNameOnly*/ true)) {
 +      mSubstitutions.InsertOrUpdate(substituteName,
 +                                    MakeUnique<nsCString>(actualFontName));
 +    } else if (mSubstitutions.Get(actualFontName)) {
 +      mSubstitutions.InsertOrUpdate(
 +          substituteName,
 +          MakeUnique<nsCString>(*mSubstitutions.Get(actualFontName)));
      } else {
 -      gfxFontFamily* ff;
 -      if (!actualFontName.IsEmpty() &&
 -          (ff = mFontFamilies.GetWeak(actualFontName))) {
 -        mFontSubstitutes.InsertOrUpdate(substituteName, RefPtr{ff});
 -      } else {
 -        mNonExistingFonts.AppendElement(substituteName);
 -      }
 +      mNonExistingFonts.AppendElement(substituteName);
 +    }
 +  } else {
 +    gfxFontFamily* ff;
 +    if (!actualFontName.IsEmpty() &&
 +        (ff = mFontFamilies.GetWeak(actualFontName))) {
 +      mFontSubstitutes.InsertOrUpdate(substituteName, RefPtr{ff});
 +    } else {
 +      mNonExistingFonts.AppendElement(substituteName);
+     }
+   }
 -  return NS_OK;
+ }
  struct FontSubstitution {

@@ -466,6 +466,9 @@ class gfxDWriteFontList final : public gfxPlatformFontList {
        const nsTArray<nsCString>* aForceClassicFams = nullptr)
        MOZ_REQUIRES(mLock);
 +  void AddSubstitute(const nsCString& substituteName,
 +                     const nsCString& actualFontName);
++
  #ifdef MOZ_BUNDLED_FONTS
    already_AddRefed<IDWriteFontCollection> CreateBundledFontsCollection(
        IDWriteFactory* aFactory);

@@ -31,6 +31,10 @@
  #include "mozilla/StaticPrefs_gfx.h"
  #include "mozilla/Telemetry.h"
 +#include "nsContentUtils.h"
++
 +#include "StandardFonts-win10.inc"
++
  #include <usp10.h>
  using namespace mozilla;
@@ -50,6 +54,10 @@ static __inline void BuildKeyNameFromFontName(nsAString& aName) {
    if (aName.Length() >= LF_FACESIZE) aName.Truncate(LF_FACESIZE - 1);
    ToLowerCase(aName);
+ }
 +static __inline void BuildKeyNameFromFontName(nsACString& aName) {
 +  if (aName.Length() >= LF_FACESIZE) aName.Truncate(LF_FACESIZE - 1);
 +  ToLowerCase(aName);
 +}
  // Implementation of gfxPlatformFontList for Win32 GDI,
  // using GDI font enumeration APIs to get the list of fonts
@@ -529,6 +537,26 @@ static void RemoveCharsetFromFontSubstitute(nsAString& aName) {
  #define MAX_VALUE_DATA 512
  nsresult gfxGDIFontList::GetFontSubstitutes() {
 +  if (nsContentUtils::ShouldResistFingerprinting(
 +          "Ignore any fingerprintable user font customization and normalize "
 +          "font substitutes across different Windows SKUs.",
 +          RFPTarget::Unknown)) {
 +    for (const FontSubstitute& fs : kFontSubstitutes) {
 +      nsAutoCString substituteName(fs.substituteName);
 +      nsAutoCString actualFontName(fs.actualFontName);
 +      BuildKeyNameFromFontName(substituteName);
 +      BuildKeyNameFromFontName(actualFontName);
 +      gfxFontFamily* ff;
 +      if (!actualFontName.IsEmpty() &&
 +          (ff = mFontFamilies.GetWeak(actualFontName))) {
 +        mFontSubstitutes.InsertOrUpdate(substituteName, RefPtr{ff});
 +      } else {
 +        mNonExistingFonts.AppendElement(substituteName);
 +      }
 +    }
 +    return NS_OK;
 +  }
++
    HKEY hKey;
    DWORD i, rv, lenAlias, lenActual, valueType;
    WCHAR aliasName[MAX_VALUE_NAME];

richard pushed to branch mullvad-browser-115.9.0esr-13.5-1 at The Tor Project / Applications / Mullvad Browser

Commits:

4 changed files:

Changes: