Change the source class type and simplify the data-flow step

Author: luchua-bc

java/ql/src/experimental/Security/CWE/CWE-749/UnsafeAndroidAccess.ql

@@ -71,16 +71,10 @@ class IntentGetExtraMethodAccess extends MethodAccess {
 }
 
 /**
- * Source of fetching URLs
+ * Source of fetching URLs from intent extras
  */
-class UntrustedResourceSource extends RemoteFlowSource {
-  UntrustedResourceSource() {
-    exists(IntentGetExtraMethodAccess ma |
-      this.asExpr().(VarAccess).getVariable().getAnAssignedValue() = ma
-    )
-  }
-
-  override string getSourceType() { result = "UntrustedIntentExtraSource" }
+class UntrustedResourceSource extends DataFlow::ExprNode {
+  UntrustedResourceSource() { this.asExpr() instanceof IntentGetExtraMethodAccess }
 }
 
 /**

java/ql/test/experimental/query-tests/security/CWE-749/UnsafeAndroidAccess.expected

@@ -1,3 +1,3 @@
-| UnsafeAndroidAccess.java:30:3:30:21 | loadUrl(...) | UnsafeAndroidAccess.java:30:14:30:20 | thisUrl | UnsafeAndroidAccess.java:30:14:30:20 | thisUrl | Unsafe resource fetching in Android webview due to $@. | UnsafeAndroidAccess.java:30:14:30:20 | thisUrl | user input vulnerable to cross-origin and sensitive resource disclosure attacks |
-| UnsafeAndroidAccess.java:53:3:53:21 | loadUrl(...) | UnsafeAndroidAccess.java:53:14:53:20 | thisUrl | UnsafeAndroidAccess.java:53:14:53:20 | thisUrl | Unsafe resource fetching in Android webview due to $@. | UnsafeAndroidAccess.java:53:14:53:20 | thisUrl | user input vulnerable to cross-origin and sensitive resource disclosure attacks |
-| UnsafeAndroidAccess.java:95:3:95:21 | loadUrl(...) | UnsafeAndroidAccess.java:95:14:95:20 | thisUrl | UnsafeAndroidAccess.java:95:14:95:20 | thisUrl | Unsafe resource fetching in Android webview due to $@. | UnsafeAndroidAccess.java:95:14:95:20 | thisUrl | user input vulnerable to XSS attacks |
+| UnsafeAndroidAccess.java:30:3:30:21 | loadUrl(...) | UnsafeAndroidAccess.java:29:20:29:59 | getString(...) : String | UnsafeAndroidAccess.java:30:14:30:20 | thisUrl | Unsafe resource fetching in Android webview due to $@. | UnsafeAndroidAccess.java:29:20:29:59 | getString(...) | user input vulnerable to cross-origin and sensitive resource disclosure attacks |
+| UnsafeAndroidAccess.java:53:3:53:21 | loadUrl(...) | UnsafeAndroidAccess.java:52:20:52:52 | getStringExtra(...) : String | UnsafeAndroidAccess.java:53:14:53:20 | thisUrl | Unsafe resource fetching in Android webview due to $@. | UnsafeAndroidAccess.java:52:20:52:52 | getStringExtra(...) | user input vulnerable to cross-origin and sensitive resource disclosure attacks |
+| UnsafeAndroidAccess.java:95:3:95:21 | loadUrl(...) | UnsafeAndroidAccess.java:94:20:94:52 | getStringExtra(...) : String | UnsafeAndroidAccess.java:95:14:95:20 | thisUrl | Unsafe resource fetching in Android webview due to $@. | UnsafeAndroidAccess.java:94:20:94:52 | getStringExtra(...) | user input vulnerable to XSS attacks |