Bug 1769030: Add a configure flag to load policies only from the local...

Bug 1769030: Add a configure flag to load policies only from the local policies.json file r=mkaply,glandium

Add a configuration flag to make Enterprise Policies mechanism only
consult a policies.json file (avoiding the Windows Registry, macOS's
file system attributes, and /etc/firefox/policies/policies.json on
other OS).

Differential Revision: https://phabricator.services.mozilla.com/D146300

toolkit/components/enterprisepolicies/EnterprisePoliciesParent.jsm

@@ -156,9 +156,12 @@ EnterprisePoliciesManager.prototype = {
 
   _chooseProvider() {
     let platformProvider = null;
-    if (AppConstants.platform == "win") {
+    if (AppConstants.platform == "win" && AppConstants.MOZ_SYSTEM_POLICIES) {
       platformProvider = new WindowsGPOPoliciesProvider();
-    } else if (AppConstants.platform == "macosx") {
+    } else if (
+      AppConstants.platform == "macosx" &&
+      AppConstants.MOZ_SYSTEM_POLICIES
+    ) {
       platformProvider = new macOSPoliciesProvider();
     }
     let jsonProvider = new JSONPoliciesProvider();
@@ -542,7 +545,7 @@ class JSONPoliciesProvider {
   _getConfigurationFile() {
     let configFile = null;
 
-    if (AppConstants.platform == "linux") {
+    if (AppConstants.platform == "linux" && AppConstants.MOZ_SYSTEM_POLICIES) {
       let systemConfigFile = Cc["@mozilla.org/file/local;1"].createInstance(
         Ci.nsIFile
       );

toolkit/modules/AppConstants.jsm

@@ -453,6 +453,13 @@ this.AppConstants = Object.freeze({
     false,
 #endif
 
+  MOZ_SYSTEM_POLICIES:
+#ifdef MOZ_SYSTEM_POLICIES
+    true,
+#else
+    false,
+#endif
+
   // Returns true for CN region build when distibution id set as 'MozillaOnline'
   isChinaRepack() {
     return (

toolkit/modules/moz.build

@@ -292,6 +292,7 @@ for var in (
     "MOZ_ALLOW_ADDON_SIDELOAD",
     "MOZ_BACKGROUNDTASKS",
     "MOZ_SYSTEM_NSS",
+    "MOZ_SYSTEM_POLICIES",
     "MOZ_UNSIGNED_APP_SCOPE",
     "MOZ_UNSIGNED_SYSTEM_SCOPE",
     "MOZ_UPDATE_AGENT",

toolkit/moz.configure

@@ -3235,3 +3235,13 @@ with only_when(compile_environment & depends(target.os)(lambda os: os != "WINNT"
     set_define("HAVE_ARC4RANDOM", check_symbol("arc4random"))
     set_define("HAVE_ARC4RANDOM_BUF", check_symbol("arc4random_buf"))
     set_define("HAVE_MALLINFO", check_symbol("mallinfo"))
+
+# System policies
+# ==============================================================
+
+option(
+    "--disable-system-policies",
+    help="Disable reading policies from Windows registry, macOS's file system attributes, and /etc/firefox",
+)
+
+set_config("MOZ_SYSTEM_POLICIES", True, when="--enable-system-policies")