JS: API graph support for accessors (and classes)

Author: asgerf

javascript/ql/lib/semmle/javascript/ApiGraphs.qll

@@ -538,12 +538,36 @@ module API {
           or
           lbl = Label::promisedError() and
           PromiseFlow::storeStep(rhs, pred, Promises::errorProp())
+          or
+          // The return-value of a getter G counts as a definition of property G
+          // (Ordinary methods and properties are handled as PropWrite nodes)
+          exists(string name | lbl = Label::member(name) |
+            rhs = pred.(DataFlow::ObjectLiteralNode).getPropertyGetter(name).getAReturn()
+            or
+            rhs =
+              pred.(DataFlow::ClassNode)
+                  .getStaticMember(name, DataFlow::MemberKind::getter())
+                  .getAReturn()
+          )
+          or
+          // If `new C()` escapes, generate edges to its instance members
+          exists(DataFlow::ClassNode cls, string name |
+            pred = cls.getAClassReference().getAnInstantiation() and
+            lbl = Label::member(name)
+          |
+            rhs = cls.getInstanceMethod(name)
+            or
+            rhs = cls.getInstanceMember(name, DataFlow::MemberKind::getter()).getAReturn()
+          )
         )
         or
         exists(DataFlow::ClassNode cls, string name |
           base = MkClassInstance(cls) and
-          lbl = Label::member(name) and
+          lbl = Label::member(name)
+        |
           rhs = cls.getInstanceMethod(name)
+          or
+          rhs = cls.getInstanceMember(name, DataFlow::MemberKind::getter()).getAReturn()
         )
         or
         exists(DataFlow::FunctionNode f |

javascript/ql/test/ApiGraphs/accessors/VerifyAssertions.expected

@@ -0,0 +1 @@
+import ApiGraphs.VerifyAssertions

javascript/ql/test/ApiGraphs/accessors/VerifyAssertions.ql

@@ -0,0 +1,65 @@
+const foo = require('foo');
+
+foo({
+    myMethod(x) { /* use (parameter 0 (member myMethod (parameter 0 (member exports (module foo))))) */
+        console.log(x);
+    }
+});
+
+foo({
+    get myMethod() {
+        return function(x) { /* use (parameter 0 (member myMethod (parameter 0 (member exports (module foo))))) */
+            console.log(x)
+        }
+    }
+});
+
+class C {
+    static myMethod(x) { /* use (parameter 0 (member myMethod (parameter 0 (member exports (module foo))))) */
+        console.log(x);
+    }
+}
+foo(C);
+
+class D {
+    myMethod(x) { /* use (parameter 0 (member myMethod (parameter 0 (member exports (module foo))))) */
+        console.log(x);
+    }
+}
+foo(new D());
+
+class E {
+    get myMethod() {
+        return function(x) { /* use (parameter 0 (member myMethod (parameter 0 (member exports (module foo))))) */
+            console.log(x);
+        }
+    }
+}
+foo(new E());
+
+class F {
+    static get myMethod() {
+        return function(x) { /* use (parameter 0 (member myMethod (parameter 0 (member exports (module foo))))) */
+            console.log(x);
+        }
+    }
+}
+foo(F);
+
+// Cases where the class is instantiated in `foo`:
+
+class G {
+    myMethod2(x) { /* use (parameter 0 (member myMethod2 (instance (parameter 0 (member exports (module foo)))))) */
+        console.log(x);
+    }
+}
+foo(G);
+
+class H {
+    get myMethod2() {
+        return function (x) { /* use (parameter 0 (member myMethod2 (instance (parameter 0 (member exports (module foo)))))) */
+            console.log(x);
+        }
+    }
+}
+foo(H);