Python: Add initial rest_framework modeling

I had to make the Django and PrivateDjango modeling non-private :O

docs/codeql/support/reusables/frameworks.rst

@@ -155,6 +155,7 @@ Python built-in support
    Name, Category
    aiohttp.web, Web framework
    Django, Web framework
+   djangorestframework, Web framework
    Flask, Web framework
    Tornado, Web framework
    Twisted, Web framework

python/ql/lib/semmle/python/Frameworks.qll

@@ -25,6 +25,7 @@ private import semmle.python.frameworks.MySQLdb
 private import semmle.python.frameworks.Peewee
 private import semmle.python.frameworks.Psycopg2
 private import semmle.python.frameworks.PyMySQL
+private import semmle.python.frameworks.RestFramework
 private import semmle.python.frameworks.Rsa
 private import semmle.python.frameworks.RuamelYaml
 private import semmle.python.frameworks.Simplejson

python/ql/lib/semmle/python/frameworks/Django.qll

@@ -17,10 +17,12 @@ private import semmle.python.frameworks.internal.SelfRefMixin
 private import semmle.python.frameworks.internal.InstanceTaintStepsHelper
 
 /**
+ * INTERNAL: Do not use.
+ *
  * Provides models for the `django` PyPI package.
  * See https://www.djangoproject.com/.
  */
-private module Django {
+module Django {
   /** Provides models for the `django.views` module */
   module Views {
     /**
@@ -466,10 +468,12 @@ private module Django {
 }
 
 /**
+ * INTERNAL: Do not use.
+ *
  * Provides models for the `django` PyPI package (that we are not quite ready to publicly expose yet).
  * See https://www.djangoproject.com/.
  */
-private module PrivateDjango {
+module PrivateDjango {
   // ---------------------------------------------------------------------------
   // django
   // ---------------------------------------------------------------------------

python/ql/lib/semmle/python/frameworks/RestFramework.qll

@@ -0,0 +1,68 @@
+/**
+ * Provides classes modeling security-relevant aspects of the `djangorestframework` PyPI package
+ * (imported as `rest_framework`)
+ *
+ * See
+ * - https://www.django-rest-framework.org/
+ * - https://pypi.org/project/djangorestframework/
+ */
+
+private import python
+private import semmle.python.dataflow.new.DataFlow
+private import semmle.python.dataflow.new.RemoteFlowSources
+private import semmle.python.dataflow.new.TaintTracking
+private import semmle.python.Concepts
+private import semmle.python.ApiGraphs
+private import semmle.python.frameworks.internal.InstanceTaintStepsHelper
+private import semmle.python.frameworks.Django
+private import semmle.python.frameworks.Stdlib
+
+/**
+ * INTERNAL: Do not use.
+ *
+ * Provides models for the `djangorestframework` PyPI package
+ * (imported as `rest_framework`)
+ *
+ * See
+ * - https://www.django-rest-framework.org/
+ * - https://pypi.org/project/djangorestframework/
+ */
+private module RestFramework {
+  /**
+   * An `API::Node` representing the `rest_framework.views.APIView` class or any subclass
+   * that has explicitly been modeled in the CodeQL libraries.
+   */
+  private class ModeledApiViewClasses extends Django::Views::View::ModeledSubclass {
+    ModeledApiViewClasses() {
+      this = API::moduleImport("rest_framework").getMember("views").getMember("APIView")
+      // TODO: Need to model all known subclasses
+    }
+  }
+
+  /**
+   * A class that has a super-type which is a rest_framework APIView class, therefore also
+   * becoming a APIView class.
+   */
+  class RestFrameworkApiViewClass extends PrivateDjango::DjangoViewClassFromSuperClass {
+    RestFrameworkApiViewClass() {
+      this.getABase() = any(ModeledApiViewClasses c).getASubclass*().getAUse().asExpr()
+    }
+
+    override Function getARequestHandler() {
+      result = super.getARequestHandler()
+      or
+      // TODO: This doesn't handle attribute assignment. Should be OK, but analysis is not as complete as with
+      // points-to and `.lookup`, which would handle `post = my_post_handler` inside class def
+      result = this.getAMethod() and
+      result.getName() in [
+          // these method names where found by looking through the APIView
+          // implementation in
+          // https://github.com/encode/django-rest-framework/blob/master/rest_framework/views.py#L104
+          "initial", "http_method_not_allowed", "permission_denied", "throttled",
+          "get_authenticate_header", "perform_content_negotiation", "perform_authentication",
+          "check_permissions", "check_object_permissions", "check_throttles", "determine_version",
+          "initialize_request", "finalize_response", "dispatch", "options"
+        ]
+    }
+  }
+}

python/ql/test/library-tests/frameworks/rest_framework/taint_test.py

@@ -89,9 +89,9 @@ def test_taint(request: Request, routed_param): # $ requestHandler routedParamet
 
 
 class MyClass(APIView):
-    def initial(self, request, *args, **kwargs):
+    def initial(self, request, *args, **kwargs): # $ requestHandler
         # this method will be called before processing any request
-        ensure_tainted(request) # $ MISSING: tainted
+        ensure_tainted(request) # $ tainted
 
     def get(self, request: Request, routed_param): # $ requestHandler routedParameter=routed_param
         ensure_tainted(routed_param) # $ tainted
@@ -124,5 +124,5 @@ def function_based_no_route(request: Request, possible_routed_param):
 
 
 class ClassBasedNoRoute(APIView):
-    def get(self, request: Request, possible_routed_param):
-        ensure_tainted(request, possible_routed_param) # $ MISSING: tainted
+    def get(self, request: Request, possible_routed_param): # $ requestHandler routedParameter=possible_routed_param
+        ensure_tainted(request, possible_routed_param) # $ tainted