JS: Refactor DOM libs to use DataFlow more

javascript/ql/src/semmle/javascript/DOM.qll

@@ -253,4 +253,86 @@ module DOM {
       reason = "must not contain any space characters"
     )
   }
+
+  /** Gets a call that queries the DOM for a collection of DOM nodes. */
+  private DataFlow::SourceNode domElementCollection() {
+    exists(string collectionName |
+      collectionName = "getElementsByClassName" or
+      collectionName = "getElementsByName" or
+      collectionName = "getElementsByTagName" or
+      collectionName = "getElementsByTagNameNS" or
+      collectionName = "querySelectorAll"
+    |
+      (
+        result = documentRef().getAMethodCall(collectionName) or
+        result = DataFlow::globalVarRef(collectionName).getACall()
+      )
+    )
+  }
+
+  /** Gets a call that creates a DOM node or queries the DOM for a DOM node. */
+  private DataFlow::SourceNode domElementCreationOrQuery() {
+    exists(string methodName |
+      methodName = "createElement" or
+      methodName = "createElementNS" or
+      methodName = "createRange" or
+      methodName = "getElementById" or
+      methodName = "querySelector"
+    |
+      result = documentRef().getAMethodCall(methodName) or
+      result = DataFlow::globalVarRef(methodName).getACall()
+    )
+  }
+
+  /** Gets a data flow node that refer directly to a value from the DOM. */
+  DataFlow::SourceNode domValueSource() {
+    result.asExpr().(VarAccess).getVariable() instanceof DOMGlobalVariable or
+    result = domValueRef().getAPropertyRead(_) or
+    result = domElementCreationOrQuery() or
+    result = domElementCollection()
+  }
+
+  /** Gets a data flow node that may refer to a value from the DOM. */
+  private DataFlow::SourceNode domValueRef(DataFlow::TypeTracker t) {
+    t.start() and
+    result = domValueSource()
+    or
+    exists(DataFlow::TypeTracker t2 | result = domValueRef(t2).track(t2, t))
+  }
+
+  /** Gets a data flow node that may refer to a value from the DOM. */
+  DataFlow::SourceNode domValueRef() { result = domValueRef(DataFlow::TypeTracker::end()) }
+
+  /** Gets a data flow node that directly refers to the DOM `location` object. */
+  DataFlow::SourceNode locationSource() {
+    result = domValueRef().getAPropertyRead("location")
+    or
+    result = DataFlow::globalVarRef("location")
+  }
+
+  /** Gets a reference to the DOM `location` object. */
+  private DataFlow::SourceNode locationRef(DataFlow::TypeTracker t) {
+    t.start() and
+    result = locationSource()
+    or
+    exists(DataFlow::TypeTracker t2 | result = locationRef(t2).track(t2, t))
+  }
+
+  /** Gets a reference to the DOM `location` object. */
+  DataFlow::SourceNode locationRef() { result = locationRef(DataFlow::TypeTracker::end()) }
+
+  /**
+   * Gets a reference to the 'document' object.
+   */
+  private DataFlow::SourceNode documentRef(DataFlow::TypeTracker t) {
+    t.start() and
+    result = DataFlow::globalVarRef("document")
+    or
+    exists(DataFlow::TypeTracker t2 | result = documentRef(t2).track(t2, t))
+  }
+
+  /**
+   * Gets a reference to the 'document' object.
+   */
+  DataFlow::SourceNode documentRef() { result = documentRef(DataFlow::TypeTracker::end()) }
 }

javascript/ql/src/semmle/javascript/security/dataflow/ClientSideUrlRedirect.qll

@@ -121,10 +121,9 @@ module ClientSideUrlRedirect {
       )
       or
       // A call to `location.replace` or `location.assign`
-      exists(MethodCallExpr locationCall, string name |
-        isLocation(locationCall.getReceiver()) and
-        name = locationCall.getMethodName() and
-        astNode = locationCall.getArgument(0)
+      exists(DataFlow::MethodCallNode locationCall, string name |
+        locationCall = DOM::locationRef().getAMethodCall(name) and
+        this = locationCall.getArgument(0)
       |
         name = "replace" or name = "assign"
       )
@@ -134,8 +133,7 @@ module ClientSideUrlRedirect {
       or
       // An assignment to `location.href`, `location.protocol` or `location.hostname`
       exists(DataFlow::PropWrite pw, string propName |
-        isLocation(pw.getBase().asExpr()) and
-        propName = pw.getPropertyName() and
+        pw = DOM::locationRef().getAPropertyWrite(propName) and
         this = pw.getRhs()
       |
         propName = "href" or propName = "protocol" or propName = "hostname"

javascript/ql/src/semmle/javascript/security/dataflow/DOM.qll

@@ -18,113 +18,36 @@ class DOMGlobalVariable extends GlobalVariable {
   }
 }
 
-private DataFlow::SourceNode domElementCollection() {
-  exists(string collectionName |
-    collectionName = "getElementsByClassName" or
-    collectionName = "getElementsByName" or
-    collectionName = "getElementsByTagName" or
-    collectionName = "getElementsByTagNameNS" or
-    collectionName = "querySelectorAll"
-  |
-    (
-      result = document().getAMethodCall(collectionName) or
-      result = DataFlow::globalVarRef(collectionName).getACall()
-    )
-  )
-}
-
-private DataFlow::SourceNode domElementCreationOrQuery() {
-  exists(string methodName |
-    methodName = "createElement" or
-    methodName = "createElementNS" or
-    methodName = "createRange" or
-    methodName = "getElementById" or
-    methodName = "querySelector"
-  |
-    result = document().getAMethodCall(methodName) or
-    result = DataFlow::globalVarRef(methodName).getACall()
-  )
-}
-
-private DataFlow::SourceNode domValueSource(DataFlow::TypeTracker t) {
-  t.start() and
-  (
-    result.asExpr().(VarAccess).getVariable() instanceof DOMGlobalVariable or
-    result = domValueSource().getAPropertyRead(_) or
-    result = domElementCreationOrQuery() or
-    result = domElementCollection()
-  )
-  or
-  exists(DataFlow::TypeTracker t2 |
-    result = domValueSource(t2).track(t2, t)
-  )
-}
-
-private DataFlow::SourceNode domValueSource() {
-  result = domValueSource(DataFlow::TypeTracker::end())
-}
-
 /** Holds if `e` could hold a value that comes from the DOM. */
-predicate isDomValue(Expr e) { domValueSource().flowsToExpr(e) }
-
-/** Gets a reference to the DOM `location` object. */
-private DataFlow::SourceNode locationRef(DataFlow::TypeTracker t) {
-  t.start() and
-  exists(Expr e | result.asExpr() = e |
-    e = domValueSource().getAPropertyReference("location").asExpr() or
-    e.accessesGlobal("location")
-  )
-  or
-  exists(DataFlow::TypeTracker t2 |
-    result = locationRef(t2).track(t2, t)
-  )
-}
-
-/** Gets a reference to the DOM `location` object. */
-private DataFlow::SourceNode locationRef() {
-  result = locationRef(DataFlow::TypeTracker::end())
-}
+predicate isDomValue(Expr e) { DOM::domValueRef().flowsToExpr(e) }
 
 /** Holds if `e` could refer to the `location` property of a DOM node. */
 predicate isLocation(Expr e) {
-  locationRef().flowsToExpr(e)
-}
-
-/**
- * Gets a reference to the 'document' object.
- */
-private DataFlow::SourceNode document(DataFlow::TypeTracker t) {
-  t.start() and
-  result = DataFlow::globalVarRef("document")
+  e = DOM::domValueRef().getAPropertyReference("location").asExpr()
   or
-  exists(DataFlow::TypeTracker t2 |
-    result = document(t2).track(t2, t)
-  )
+  e.accessesGlobal("location")
 }
 
 /**
  * Gets a reference to the 'document' object.
  */
-DataFlow::SourceNode document() { result = document(DataFlow::TypeTracker::end()) }
+DataFlow::SourceNode document() { result = DOM::documentRef() }
 
 /** Holds if `e` could refer to the `document` object. */
-predicate isDocument(Expr e) { document().flowsToExpr(e) }
+predicate isDocument(Expr e) { DOM::documentRef().flowsToExpr(e) }
 
 /** Holds if `e` could refer to the document URL. */
 predicate isDocumentURL(Expr e) {
-  exists(Expr base, string propName | e.(PropAccess).accesses(base, propName) |
-    isDocument(base) and
-    (
-      propName = "documentURI" or
-      propName = "documentURIObject" or
-      propName = "location" or
-      propName = "referrer" or
-      propName = "URL"
-    )
-    or
-    isDomValue(base) and propName = "baseUri"
+  exists(string propName | e = DOM::documentRef().getAPropertyRead(propName).asExpr() |
+    propName = "documentURI" or
+    propName = "documentURIObject" or
+    propName = "location" or
+    propName = "referrer" or
+    propName = "URL"
   )
   or
+  e = DOM::domValueRef().getAPropertyRead("baseUri").asExpr()
+  or
   e.accessesGlobal("location")
 }
 
@@ -134,7 +57,7 @@ predicate isDocumentURL(Expr e) {
  * `href`, `hash` and `search`.
  */
 predicate isSafeLocationProperty(PropAccess pacc) {
-  exists(Expr loc, string prop | isLocation(loc) and pacc.accesses(loc, prop) |
+  exists(string prop | pacc = DOM::locationRef().getAPropertyRead(prop).asExpr() |
     prop != "href" and prop != "hash" and prop != "search"
   )
 }

javascript/ql/src/semmle/javascript/security/dataflow/PropertyInjectionShared.qll

@@ -14,7 +14,7 @@ module PropertyInjection {
     node = DataFlow::globalObjectRef()
     or
     // document.write can be accessed
-    isDocument(node.asExpr())
+    node = DOM::documentRef()
     or
     // 'constructor' property leads to the Function constructor.
     node.analyze().getAValue() instanceof AbstractCallable

javascript/ql/src/semmle/javascript/security/dataflow/XpathInjection.qll

@@ -75,7 +75,7 @@ module XpathInjection {
   class DomXpathSink extends Sink {
     DomXpathSink() {
       exists(string m | m = "evaluate" or m = "createExpression" |
-        this = document().getAMethodCall(m).getArgument(0)
+        this = DOM::documentRef().getAMethodCall(m).getArgument(0)
       )
     }
   }