C#: Re-factor XPathInjection to use the new API.

Author: michaelnebel

csharp/ql/lib/semmle/code/csharp/security/dataflow/XPathInjectionQuery.qll

@@ -24,9 +24,11 @@ abstract class Sink extends DataFlow::ExprNode { }
 abstract class Sanitizer extends DataFlow::ExprNode { }
 
 /**
+ * DEPRECATED: Use `XpathInjection` instead.
+ *
  * A taint-tracking configuration for untrusted user input used in XPath expression.
  */
-class TaintTrackingConfiguration extends TaintTracking::Configuration {
+deprecated class TaintTrackingConfiguration extends TaintTracking::Configuration {
   TaintTrackingConfiguration() { this = "XPathInjection" }
 
   override predicate isSource(DataFlow::Node source) { source instanceof Source }
@@ -36,6 +38,32 @@ class TaintTrackingConfiguration extends TaintTracking::Configuration {
   override predicate isSanitizer(DataFlow::Node node) { node instanceof Sanitizer }
 }
 
+/**
+ * A taint-tracking configuration for untrusted user input used in XPath expression.
+ */
+module XpathInjectionConfig implements DataFlow::ConfigSig {
+  /**
+   * Holds if `source` is a relevant data flow source.
+   */
+  predicate isSource(DataFlow::Node source) { source instanceof Source }
+
+  /**
+   * Holds if `sink` is a relevant data flow sink.
+   */
+  predicate isSink(DataFlow::Node sink) { sink instanceof Sink }
+
+  /**
+   * Holds if data flow through `node` is prohibited. This completely removes
+   * `node` from the data flow graph.
+   */
+  predicate isBarrier(DataFlow::Node node) { node instanceof Sanitizer }
+}
+
+/**
+ * A taint-tracking module for untrusted user input used in XPath expression.
+ */
+module XpathInjection = TaintTracking::Global<XpathInjectionConfig>;
+
 /** A source of remote user input. */
 class RemoteSource extends Source instanceof RemoteFlowSource { }
 

csharp/ql/src/Security Features/CWE-643/StoredXPathInjection.ql

@@ -13,14 +13,20 @@
 
 import csharp
 import semmle.code.csharp.security.dataflow.flowsources.Stored
-import semmle.code.csharp.security.dataflow.XPathInjectionQuery as XPathInjection
-import semmle.code.csharp.dataflow.DataFlow::DataFlow::PathGraph
+import semmle.code.csharp.security.dataflow.XPathInjectionQuery
+import StoredXpathInjection::PathGraph
 
-class StoredTaintTrackingConfiguration extends XPathInjection::TaintTrackingConfiguration {
-  override predicate isSource(DataFlow::Node source) { source instanceof StoredFlowSource }
+module StoredXpathInjectionConfig implements DataFlow::ConfigSig {
+  predicate isSource(DataFlow::Node source) { source instanceof StoredFlowSource }
+
+  predicate isSink = XpathInjectionConfig::isSink/1;
+
+  predicate isBarrier = XpathInjectionConfig::isBarrier/1;
 }
 
-from StoredTaintTrackingConfiguration c, DataFlow::PathNode source, DataFlow::PathNode sink
-where c.hasFlowPath(source, sink)
+module StoredXpathInjection = TaintTracking::Global<StoredXpathInjectionConfig>;
+
+from StoredXpathInjection::PathNode source, StoredXpathInjection::PathNode sink
+where StoredXpathInjection::flowPath(source, sink)
 select sink.getNode(), source, sink, "This XPath expression depends on a $@.", source.getNode(),
   "stored (potentially user-provided) value"

csharp/ql/src/Security Features/CWE-643/XPathInjection.ql

@@ -13,9 +13,9 @@
 
 import csharp
 import semmle.code.csharp.security.dataflow.XPathInjectionQuery
-import semmle.code.csharp.dataflow.DataFlow::DataFlow::PathGraph
+import XpathInjection::PathGraph
 
-from TaintTrackingConfiguration c, DataFlow::PathNode source, DataFlow::PathNode sink
-where c.hasFlowPath(source, sink)
+from XpathInjection::PathNode source, XpathInjection::PathNode sink
+where XpathInjection::flowPath(source, sink)
 select sink.getNode(), source, sink, "This XPath expression depends on a $@.", source.getNode(),
   "user-provided value"