JavaScript: Import flow summaries through external predicates.

javascript/ql/src/Security/Summaries/ImportFromExternalPredicates.qll

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+/**
+ * Provides classes for importing source, sink and flow step summaries
+ * through external predicates.
+ */
+
+import javascript
+import semmle.javascript.dataflow.Portals
+import external.ExternalArtifact
+
+/**
+ * An external predicate providing information about additional sources.
+ *
+ * This predicate can be populated from the output of the `ExtractSourceSummaries` query.
+ */
+external predicate additionalSources(string portal, string flowLabel, string config);
+
+/**
+ * An external predicate providing information about additional sinks.
+ *
+ * This predicate can be populated from the output of the `ExtractSinkSummaries` query.
+ */
+external predicate additionalSinks(string portal, string flowLabel, string config);
+
+/**
+ * An external predicate providing information about additional flow steps.
+ *
+ * This predicate can be populated from the output of the `ExtractFlowStepSummaries` query.
+ */
+external predicate additionalSteps(string startPortal, string startFlowLabel, string endPortal, string endFlowLabel, string config);
+
+/**
+ * An additional source specified through the `additionalSources` predicate.
+ */
+private class AdditionalSourceFromSpec extends DataFlow::AdditionalSource {
+  Portal portal;
+  string flowLabel;
+  string config;
+
+  AdditionalSourceFromSpec() {
+    additionalSources(portal.toString(), flowLabel, config) and
+    this = portal.getAnExitNode(_)
+  }
+
+  override predicate isSourceFor(DataFlow::Configuration cfg, DataFlow::FlowLabel lbl) {
+    cfg.toString() = config and
+    lbl = flowLabel
+  }
+}
+
+/**
+ * An additional sink specified through the `additionalSinks` predicate.
+ */
+private class AdditionalSinkFromSpec extends DataFlow::AdditionalSink {
+  Portal portal;
+  string flowLabel;
+  string config;
+
+  AdditionalSinkFromSpec() {
+    additionalSinks(portal.toString(), flowLabel, config) and
+    this = portal.getAnEntryNode(_)
+  }
+
+  override predicate isSinkFor(DataFlow::Configuration cfg, DataFlow::FlowLabel lbl) {
+    cfg.toString() = config and
+    lbl = flowLabel
+  }
+}
+/**
+ * An additional flow step specified through the `additionalSteps` predicate.
+ */
+private class AdditionalFlowStepFromSpec extends DataFlow::Configuration {
+  DataFlow::Node entry;
+  string startFlowLabel;
+  DataFlow::Node exit;
+  string endFlowLabel;
+
+  AdditionalFlowStepFromSpec() {
+    exists (Portal startPortal, Portal endPortal |
+      additionalSteps(startPortal.toString(), startFlowLabel, endPortal.toString(), endFlowLabel, this) and
+      entry = startPortal.getAnEntryNode(_) and
+      exit = endPortal.getAnExitNode(_)
+    )
+  }
+
+  override predicate isAdditionalFlowStep(DataFlow::Node pred, DataFlow::Node succ,
+                                          DataFlow::FlowLabel predlbl, DataFlow::FlowLabel succlbl) {
+    pred = entry and
+    succ = exit and
+    predlbl = startFlowLabel and
+    succlbl = endFlowLabel
+  }
+}