Bug 1303685: Add telemetry for CSP referrer directive. r=ckerschb,francois

dom/base/nsDocument.cpp

@@ -1430,6 +1430,7 @@ nsDocument::~nsDocument()
       // record CSP telemetry on this document
       if (mHasCSP) {
         Accumulate(Telemetry::CSP_DOCUMENTS_COUNT, 1);
+        Accumulate(Telemetry::CSP_REFERRER_DIRECTIVE, mHasReferrerPolicyCSP);
       }
       if (mHasUnsafeInlineCSP) {
         Accumulate(Telemetry::CSP_UNSAFE_INLINE_DOCUMENTS_COUNT, 1);

dom/base/nsIDocument.h

@@ -707,6 +707,14 @@ public:
     return mHasMixedDisplayContentBlocked;
   }
 
+  /**
+  * Set referrer policy CSP flag for this document.
+  */
+  void SetHasReferrerPolicyCSP(bool aHasReferrerPolicyCSP)
+  {
+    mHasReferrerPolicyCSP = aHasReferrerPolicyCSP;
+  }
+
   /**
    * Set the mixed display content blocked flag for this document.
    */
@@ -3080,6 +3088,9 @@ protected:
   // it's false only when we're in bfcache or unloaded.
   bool mVisible : 1;
 
+  // True if a document load has a CSP with referrer attached.
+  bool mHasReferrerPolicyCSP : 1;
+
   // True if our content viewer has been removed from the docshell
   // (it may still be displayed, but in zombie state). Form control data
   // has been saved.

dom/security/nsCSPParser.cpp

@@ -924,6 +924,11 @@ nsCSPParser::referrerDirectiveValue(nsCSPDirective* aDir)
                              params, ArrayLength(params));
 
   // the referrer policy is valid, so go ahead and use it.
+  nsWeakPtr ctx = mCSPContext->GetLoadingContext();
+  nsCOMPtr<nsIDocument> doc = do_QueryReferent(ctx);
+  if (doc) {
+    doc->SetHasReferrerPolicyCSP(true);
+  }
   mPolicy->setReferrerPolicy(&mCurDir[1]);
   mPolicy->addDirective(aDir);
 }

toolkit/components/telemetry/Histograms.json

@@ -4236,6 +4236,13 @@
     "kind": "count",
     "description": "Number of unique pages that contain an unsafe-eval CSP directive"
   },
+  "CSP_REFERRER_DIRECTIVE": {
+    "alert_emails": ["seceng-telemetry@mozilla.com"],
+    "bug_numbers": [1303685],
+    "expires_in_version": "56",
+    "kind": "boolean",
+    "description": "Whether a document with a CSP policy (report-only or enforcing) contains a referrer directive ('true') or not ('false')."
+  },
   "PLACES_PAGES_COUNT": {
     "expires_in_version": "never",
     "kind": "exponential",