[tor-browser/tor-browser-31.5.0esr-4.5-1] fixup! Bug #5926: Allow customization of content JS locale.

25 Mar 2015

commit 85253fe54b195202ee36907183c81bc8b79da7f4
Author: Arthur Edelstein <arthuredelstein@gmail.com>
Date:   Mon Mar 23 00:18:37 2015 -0700

    fixup! Bug #5926: Allow customization of content JS locale.
    
    See https://trac.torproject.org/projects/tor/ticket/13019#comment:17
    
    This changes commit 6b90e18cd63c6dcad3b2bee1d3a45a7e3645ff50.
---
 browser/base/content/test/general/mochitest.ini    |    1 +
 .../test/general/test_bug_jsdefaultlocale.html     |   41 ++++++++++++++++++++
 xpcom/build/nsXPComInit.cpp                        |   37 +++++++++---------
 3 files changed, 60 insertions(+), 19 deletions(-)

diff --git a/browser/base/content/test/general/mochitest.ini b/browser/base/content/test/general/mochitest.ini
index caccc6f..7f228fe 100644
--- a/browser/base/content/test/general/mochitest.ini
+++ b/browser/base/content/test/general/mochitest.ini
@@ -29,6 +29,7 @@ support-files =
 
 [test_bug364677.html]
 [test_bug395533.html]
+[test_bug_jsdefaultlocale.html]
 [test_contextmenu.html]
 skip-if = toolkit == "gtk2" || toolkit == "gtk3" # disabled on Linux due to bug 513558
 [test_contextmenu_input.html]
diff --git a/browser/base/content/test/general/test_bug_jsdefaultlocale.html b/browser/base/content/test/general/test_bug_jsdefaultlocale.html
new file mode 100644
index 0000000..6566ae0
--- /dev/null
+++ b/browser/base/content/test/general/test_bug_jsdefaultlocale.html
@@ -0,0 +1,41 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugs.torproject.org/13019
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Tor Bug #13019: Prevent fingerprinting of JS-exposed locale</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="/tests/SimpleTest/EventUtils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugs.torproject.org">Bug 13019</a>
+<p id="display"></p>
+<pre id="test"></pre>
+<script type="application/javascript;version=1.8">
+let prefName = "javascript.use_us_english_locale",
+    originalPrefValue = null,
+    date = new Date();
+// Read the current pref value.
+try {
+  originalPrefValue = SpecialPowers.getBoolPref(prefName);
+} catch (e) { }
+// Enable pref "javascript.use_us_english_locale".
+SpecialPowers.setBoolPref(prefName, true);
+// Test that we are getting en-US locale everywhere it is exposed in JavaScript
+is(Intl.Collator().resolvedOptions().locale, "en-US", "content JS locale from Intl.Collator");
+is(Intl.DateTimeFormat().resolvedOptions().locale, "en-US", "content JS locale Intl.DateTimeFormat");
+is(Intl.NumberFormat().resolvedOptions().locale, "en-US", "content JS locale from Intl.NumberFormat");
+is(date.toLocaleString(), date.toLocaleString("en-US"), "Date formatted by JS locale");
+// Return pref to its original value, if it had one.
+if (originalPrefValue === null) {
+  SpecialPowers.clearUserPref(prefName);
+} else {
+  SpecialPowers.setBoolPref(prefName, originalPrefValue);
+}
+
+</script>
+</body>
+</html>
diff --git a/xpcom/build/nsXPComInit.cpp b/xpcom/build/nsXPComInit.cpp
index 979e10b..12e46d4 100644
--- a/xpcom/build/nsXPComInit.cpp
+++ b/xpcom/build/nsXPComInit.cpp
@@ -447,12 +447,12 @@ NS_IMPL_ISUPPORTS(NesteggReporter, nsIMemoryReporter)
 #endif /* MOZ_WEBM */
 
 // Anonymous namespace for customizing the default locale that JavaScript
-// uses, according to the value of the "javascript.default_locale" pref.
+// uses, according to the value of the "javascript.use_us_english_locale" pref.
 // The current default locale can be detected in JavaScript by calling
 // `Intl.DateTimeFormat().resolvedOptions().locale`
 namespace {
 
-#define DEFAULT_LOCALE_PREF "javascript.default_locale"
+#define USE_US_ENGLISH_LOCALE_PREF "javascript.use_us_english_locale"
 
 static char* sSystemLocale;
 static char* sJSLocale;
@@ -468,27 +468,26 @@ JSRuntime* GetRuntime() {
   return rt;
 }
 
-// Takes the "javascript.default_locale" pref value and applies it. If the locale
-// is empty, we fall back to the default system and JS locales.
+// If the USE_US_ENGLISH_LOCALE_PREF is active, set all locales to US English.
+// Otherwise, fall back to the default system and JS locales.
 static
-void DefaultLocaleChangedCallback(const char* /* pref */, void* /* closure */) {
+void UseUSEnglishLocalePrefChangedCallback(const char* /* pref */, void* /* closure */) {
   // Get a pointer to the default JS Runtime.
   JSRuntime* rt = GetRuntime();
   if (rt) {
-    // Read the pref, which may contain a custom default locale to be used in JavaScript.
-    nsAutoCString prefLocale;
-    mozilla::Preferences::GetCString(DEFAULT_LOCALE_PREF, &prefLocale);
+    // Read the pref to see if we will use US English locale.
+    bool useUSEnglishLocale = mozilla::Preferences::GetBool(USE_US_ENGLISH_LOCALE_PREF, false);
     // Set the application-wide C-locale. Needed for Date.toLocaleFormat().
-    setlocale(LC_ALL, prefLocale.IsEmpty() ? sSystemLocale : prefLocale.get());
+    setlocale(LC_ALL, useUSEnglishLocale ? "en_US" : sSystemLocale);
     // Now override the JavaScript Runtime Locale that is used by the Intl API
     // as well as Date.toLocaleString, Number.toLocaleString, and String.localeCompare.
-    JS_SetDefaultLocale(rt, prefLocale.IsEmpty() ? sJSLocale : prefLocale.get());
+    JS_SetDefaultLocale(rt, useUSEnglishLocale ? "en-US" : sJSLocale);
   }
 }
 
 static
-void StartWatchingDefaultLocalePref() {
-  // Get the default system locale. To be used if pref is not available.
+void StartWatchingUseUSEnglishLocalePref() {
+  // Get the default system locale. To be used if US English locale pref is deactivated.
   sSystemLocale = strdup(setlocale(LC_ALL,NULL));
   // Store the default JavaScript locale.
   JSRuntime* rt = GetRuntime();
@@ -496,17 +495,17 @@ void StartWatchingDefaultLocalePref() {
     sJSLocale = strdup(JS_GetDefaultLocale(rt));
   }
   // Now keep the locale updated with the current pref value.
-  mozilla::Preferences::RegisterCallbackAndCall(DefaultLocaleChangedCallback, DEFAULT_LOCALE_PREF);
+  mozilla::Preferences::RegisterCallbackAndCall(UseUSEnglishLocalePrefChangedCallback, USE_US_ENGLISH_LOCALE_PREF);
 }
 
 static
-void StopWatchingDefaultLocalePref() {
-  mozilla::Preferences::UnregisterCallback(DefaultLocaleChangedCallback, DEFAULT_LOCALE_PREF);
+void StopWatchingUseUSEnglishLocalePref() {
+  mozilla::Preferences::UnregisterCallback(UseUSEnglishLocalePrefChangedCallback, USE_US_ENGLISH_LOCALE_PREF);
   if (sSystemLocale) free(sSystemLocale);
   if (sJSLocale) JS_free(nullptr, sJSLocale);
 }
 
-} // anonymous namespace for locale pref
+} // anonymous namespace for locale hiding
 
 EXPORT_XPCOM_API(nsresult)
 NS_InitXPCOM2(nsIServiceManager* *result,
@@ -766,8 +765,8 @@ NS_InitXPCOM2(nsIServiceManager* *result,
     mozilla::eventtracer::Init();
 #endif
 
-    // Start watching the javascript.default_locale pref.
-    StartWatchingDefaultLocalePref();
+  // Start watching the "javascript.use_us_english_locale" pref.
+  StartWatchingUseUSEnglishLocalePref();
     return NS_OK;
 }
 
@@ -1033,7 +1032,7 @@ ShutdownXPCOM(nsIServiceManager* servMgr)
         sExitManager = nullptr;
     }
 
-    StopWatchingDefaultLocalePref();
+    StopWatchingUseUSEnglishLocalePref();
 
     Omnijar::CleanUp();

    

mikeperry＠torproject.org

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