Merge pull request #2705 from erik-krogh/CVE75

Approved by asgerf

javascript/ql/src/semmle/javascript/frameworks/NodeJSLib.qll

@@ -906,9 +906,7 @@ module NodeJSLib {
    * An instance of an EventEmitter that is imported through the 'events' module.
    */
   private class ImportedNodeJSEventEmitter extends NodeJSEventEmitter {
-    ImportedNodeJSEventEmitter() {
-      this = getAnEventEmitterImport().getAnInstantiation()
-    }
+    ImportedNodeJSEventEmitter() { this = getAnEventEmitterImport().getAnInstantiation() }
   }
 
   /**
@@ -922,20 +920,33 @@ module NodeJSLib {
   }
 
   /**
-   * An instantiation of a class that extends EventEmitter. 
-   * 
+   * An instantiation of a class that extends EventEmitter.
+   *
    * By extending `NodeJSEventEmitter' we get data-flow on the events passing through this EventEmitter.
    */
-  private class CustomEventEmitter extends NodeJSEventEmitter {
+  class CustomEventEmitter extends NodeJSEventEmitter {
+  	EventEmitterSubClass clazz;
     CustomEventEmitter() {
-      this = any(EventEmitterSubClass clazz).getAClassReference().getAnInstantiation()
+      if exists(clazz.getAClassReference().getAnInstantiation()) then
+        this = clazz.getAClassReference().getAnInstantiation()
+      else
+        // In case there are no explicit instantiations of the clazz, then we still want to track data flow between `this` nodes. 
+        // This cannot produce false flow as the `.ref()` method below is always used when creating event-registrations/event-dispatches. 
+        this = clazz
+    }
+    
+    override DataFlow::SourceNode ref() {
+      result = NodeJSEventEmitter.super.ref() and not this = clazz
+      or
+      result = clazz.getAReceiverNode()
     }
   }
 
   /**
    * A registration of an event handler on a NodeJS EventEmitter instance.
    */
-  private class NodeJSEventRegistration extends EventRegistration::DefaultEventRegistration, DataFlow::MethodCallNode {
+  private class NodeJSEventRegistration extends EventRegistration::DefaultEventRegistration,
+    DataFlow::MethodCallNode {
     override NodeJSEventEmitter emitter;
 
     NodeJSEventRegistration() { this = emitter.ref().getAMethodCall(EventEmitter::on()) }
@@ -944,9 +955,94 @@ module NodeJSLib {
   /**
    * A dispatch of an event on a NodeJS EventEmitter instance.
    */
-  private class NodeJSEventDispatch extends EventDispatch::DefaultEventDispatch, DataFlow::MethodCallNode {
+  private class NodeJSEventDispatch extends EventDispatch::DefaultEventDispatch,
+    DataFlow::MethodCallNode {
     override NodeJSEventEmitter emitter;
 
     NodeJSEventDispatch() { this = emitter.ref().getAMethodCall("emit") }
   }
+
+  /**
+   * An instance of net.createServer(), which creates a new TCP/IPC server.
+   */
+  private class NodeJSNetServer extends DataFlow::SourceNode {
+    NodeJSNetServer() { this = DataFlow::moduleMember("net", "createServer").getAnInvocation() }
+
+    private DataFlow::SourceNode ref(DataFlow::TypeTracker t) {
+      t.start() and result = this
+      or
+      exists(DataFlow::TypeTracker t2 | result = ref(t2).track(t2, t))
+    }
+
+    /**
+     * Gets a reference to this server.
+     */ 
+    DataFlow::SourceNode ref() { result = ref(DataFlow::TypeTracker::end()) }
+  }
+  
+  /**
+   * A connection opened on a NodeJS net server.
+   */ 
+  private class NodeJSNetServerConnection extends EventEmitter::Range {
+  	NodeJSNetServer server;
+  	
+  	NodeJSNetServerConnection() {
+  	  exists(DataFlow::MethodCallNode call | 
+  	    call = server.ref().getAMethodCall("on") and 
+  	    call.getArgument(0).mayHaveStringValue("connection") 
+  	  | 
+  	    this = call.getCallback(1).getParameter(0)
+  	  )  	  	
+  	}
+  	
+    DataFlow::SourceNode ref() { result = EventEmitter::trackEventEmitter(this) }
+  }
+
+  /**
+   * A registration of an event handler on a NodeJS net server instance.
+   */
+  private class NodeJSNetServerRegistration extends EventRegistration::DefaultEventRegistration,
+    DataFlow::MethodCallNode {
+    override NodeJSNetServerConnection emitter;
+
+    NodeJSNetServerRegistration() { this = emitter.ref().getAMethodCall(EventEmitter::on()) }
+  }
+
+  /**
+   * A data flow node representing data received from a client to a NodeJS net server, viewed as remote user input.
+   */
+  private class NodeJSNetServerItemAsRemoteFlow extends RemoteFlowSource {
+    NodeJSNetServerRegistration reg;
+
+    NodeJSNetServerItemAsRemoteFlow() { this = reg.getReceivedItem(_) }
+
+    override string getSourceType() { result = "NodeJS server" }
+  }
+  
+  /**
+   * An instantiation of the `respjs` library, which is an EventEmitter.
+   */
+  private class RespJS extends NodeJSEventEmitter {
+  	RespJS() {
+  	  this = DataFlow::moduleImport("respjs").getAnInstantiation()	
+  	}
+  }
+  
+  /**
+   * A event dispatch that serializes the input data and emits the result on the "data" channel. 
+   */
+  private class RespWrite extends EventDispatch::DefaultEventDispatch,
+    DataFlow::MethodCallNode {
+    override RespJS emitter;
+
+    RespWrite() { this = emitter.ref().getAMethodCall("write") }
+    
+    override string getChannel() {
+      result = "data"
+    }
+
+    override DataFlow::Node getSentItem(int i) {
+      i = 0 and result = this.getArgument(i)
+    }
+  }
 }

javascript/ql/test/library-tests/frameworks/EventEmitter/customEmitter.js

@@ -0,0 +1,22 @@
+const EventEmitter = require("events");
+
+class MyEmitter extends EventEmitter {
+	foo() {
+		this.emit("foo", "bar");
+		this.on("foo", (data) => {});
+	}
+}
+
+class MySecondEmitter extends EventEmitter {
+	foo() {
+	  this.emit("bar", "baz");
+      this.on("bar", (data) => {});
+	}
+}
+
+var x = new MySecondEmitter();
+x.emit("bar", "baz2");
+
+var y = new MySecondEmitter();
+y.emit("bar", "baz3");
+y.on("bar", (yData) => {})

javascript/ql/test/library-tests/frameworks/EventEmitter/test.expected

@@ -1,3 +1,9 @@
+| customEmitter.js:5:20:5:24 | "bar" | customEmitter.js:6:19:6:22 | data |
+| customEmitter.js:12:21:12:25 | "baz" | customEmitter.js:13:23:13:26 | data |
+| customEmitter.js:12:21:12:25 | "baz" | customEmitter.js:22:14:22:18 | yData |
+| customEmitter.js:18:15:18:20 | "baz2" | customEmitter.js:13:23:13:26 | data |
+| customEmitter.js:21:15:21:20 | "baz3" | customEmitter.js:13:23:13:26 | data |
+| customEmitter.js:21:15:21:20 | "baz3" | customEmitter.js:22:14:22:18 | yData |
 | tst.js:9:23:9:33 | 'FirstData' | tst.js:6:40:6:44 | first |
 | tst.js:10:24:10:35 | 'SecondData' | tst.js:7:32:7:37 | second |
 | tst.js:15:24:15:39 | 'OtherFirstData' | tst.js:14:41:14:50 | otherFirst |