Python: initial sketch

python/ql/src/experimental/semmle/python/frameworks/PEP249.qll

@@ -0,0 +1,99 @@
+private import python
+private import experimental.dataflow.DataFlow
+private import experimental.dataflow.RemoteFlowSources
+private import experimental.semmle.python.Concepts
+
+abstract class PEP249Module extends DataFlow::Node { }
+
+/** Gets a reference to a connect call. */
+private DataFlow::Node connect(DataFlow::TypeTracker t) {
+  t.startInAttr("connect") and
+  result instanceof PEP249Module
+  or
+  exists(DataFlow::TypeTracker t2 | result = connect(t2).track(t2, t))
+}
+
+/** Gets a reference to a connect call. */
+DataFlow::Node connect() { result = connect(DataFlow::TypeTracker::end()) }
+
+/**
+ * Provides models for the `db.Conection` class
+ *
+ * See apiref.
+ */
+module Connection {
+  /**
+   * A source of an instance of `db.Conection`.
+   *
+   * This can include instantiation of the class, return value from function
+   * calls, or a special parameter that will be set when functions are call by external
+   * library.
+   *
+   * Use `Conection::instance()` predicate to get references to instances of `db.Conection`.
+   */
+  abstract class InstanceSource extends DataFlow::Node { }
+
+  /** A direct instantiation of `db.Conection`. */
+  private class ClassInstantiation extends InstanceSource, DataFlow::CfgNode {
+    override CallNode node;
+
+    ClassInstantiation() { node.getFunction() = connect().asCfgNode() }
+  }
+
+  /** Gets a reference to an instance of `db.Conection`. */
+  private DataFlow::Node instance(DataFlow::TypeTracker t) {
+    t.start() and
+    result instanceof InstanceSource
+    or
+    exists(DataFlow::TypeTracker t2 | result = instance(t2).track(t2, t))
+  }
+
+  /** Gets a reference to an instance of `db.Conection`. */
+  DataFlow::Node instance() { result = instance(DataFlow::TypeTracker::end()) }
+}
+
+/** Provides models for the `django.db.connection.cursor` method. */
+module cursor {
+  /** Gets a reference to the `django.db.connection.cursor` metod. */
+  private DataFlow::Node methodRef(DataFlow::TypeTracker t) {
+    t.startInAttr("cursor") and
+    result = Connection::instance()
+    or
+    exists(DataFlow::TypeTracker t2 | result = methodRef(t2).track(t2, t))
+  }
+
+  /** Gets a reference to the `django.db.connection.cursor` metod. */
+  DataFlow::Node methodRef() { result = methodRef(DataFlow::TypeTracker::end()) }
+
+  /** Gets a reference to a result of calling `django.db.connection.cursor`. */
+  private DataFlow::Node methodResult(DataFlow::TypeTracker t) {
+    t.start() and
+    result.asCfgNode().(CallNode).getFunction() = methodRef().asCfgNode()
+    or
+    exists(DataFlow::TypeTracker t2 | result = methodResult(t2).track(t2, t))
+  }
+
+  /** Gets a reference to a result of calling `django.db.connection.cursor`. */
+  DataFlow::Node methodResult() { result = methodResult(DataFlow::TypeTracker::end()) }
+}
+
+/** Gets a reference to the `django.db.connection.cursor.execute` function. */
+private DataFlow::Node execute(DataFlow::TypeTracker t) {
+  t.startInAttr("execute") and
+  result = cursor::methodResult()
+  or
+  exists(DataFlow::TypeTracker t2 | result = execute(t2).track(t2, t))
+}
+
+/** Gets a reference to the `django.db.connection.cursor.execute` function. */
+DataFlow::Node execute() { result = execute(DataFlow::TypeTracker::end()) }
+
+private class DbConnectionExecute extends SqlExecution::Range, DataFlow::CfgNode {
+  override CallNode node;
+
+  DbConnectionExecute() { node.getFunction() = execute().asCfgNode() }
+
+  override DataFlow::Node getSql() {
+    result.asCfgNode() in [node.getArg(0), node.getArgByName("sql")]
+  }
+}