Merge pull request #14353 from GeekMasher/py-restframework

Python: support `*args` and `**kwargs` in request handlers

Author: RasmusWL

python/ql/lib/change-notes/2023-11-21-request-handler-args-kwargs.md

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* Added modeling of `*args` and `**kwargs` as routed-parameters in request handlers for django/flask/FastAPI/tornado.

python/ql/lib/semmle/python/Concepts.qll

@@ -928,7 +928,10 @@ module Http {
 
       override Parameter getARoutedParameter() {
         result = rs.getARoutedParameter() and
-        result in [this.getArg(_), this.getArgByName(_)]
+        result in [
+            this.getArg(_), this.getArgByName(_), this.getVararg().(Parameter),
+            this.getKwarg().(Parameter)
+          ]
       }
 
       override string getFramework() { result = rs.getFramework() }

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

@@ -2416,7 +2416,10 @@ module PrivateDjango {
       // Since we don't know the URL pattern, we simply mark all parameters as a routed
       // parameter. This should give us more RemoteFlowSources but could also lead to
       // more FPs. If this turns out to be the wrong tradeoff, we can always change our mind.
-      result in [this.getArg(_), this.getArgByName(_)] and
+      result in [
+          this.getArg(_), this.getArgByName(_), //
+          this.getVararg().(Parameter), this.getKwarg().(Parameter), // TODO: These sources should be modeled as storing content!
+        ] and
       not result = any(int i | i < this.getFirstPossibleRoutedParamIndex() | this.getArg(i))
     }
 
@@ -2452,13 +2455,20 @@ module PrivateDjango {
       // more FPs. If this turns out to be the wrong tradeoff, we can always change our mind.
       exists(DjangoRouteHandler routeHandler | routeHandler = this.getARequestHandler() |
         not exists(this.getUrlPattern()) and
-        result in [routeHandler.getArg(_), routeHandler.getArgByName(_)] and
+        result in [
+            routeHandler.getArg(_), routeHandler.getArgByName(_), //
+            routeHandler.getVararg().(Parameter), routeHandler.getKwarg().(Parameter), // TODO: These sources should be modeled as storing content!
+          ] and
         not result =
           any(int i | i < routeHandler.getFirstPossibleRoutedParamIndex() | routeHandler.getArg(i))
       )
       or
       exists(string name |
-        result = this.getARequestHandler().getArgByName(name) and
+        (
+          result = this.getARequestHandler().getKwarg() // TODO: These sources should be modeled as storing content!
+          or
+          result = this.getARequestHandler().getArgByName(name)
+        ) and
         exists(string match |
           match = this.getUrlPattern().regexpFind(pathRoutedParameterRegex(), _, _) and
           name = match.regexpCapture(pathRoutedParameterRegex(), 2)
@@ -2475,7 +2485,10 @@ module PrivateDjango {
       // more FPs. If this turns out to be the wrong tradeoff, we can always change our mind.
       exists(DjangoRouteHandler routeHandler | routeHandler = this.getARequestHandler() |
         not exists(this.getUrlPattern()) and
-        result in [routeHandler.getArg(_), routeHandler.getArgByName(_)] and
+        result in [
+            routeHandler.getArg(_), routeHandler.getArgByName(_), //
+            routeHandler.getVararg().(Parameter), routeHandler.getKwarg().(Parameter), // TODO: These sources should be modeled as storing content!
+          ] and
         not result =
           any(int i | i < routeHandler.getFirstPossibleRoutedParamIndex() | routeHandler.getArg(i))
       )
@@ -2488,13 +2501,22 @@ module PrivateDjango {
         // either using named capture groups (passed as keyword arguments) or using
         // unnamed capture groups (passed as positional arguments)
         not exists(regex.getGroupName(_, _)) and
-        // first group will have group number 1
-        result =
-          routeHandler
-              .getArg(routeHandler.getFirstPossibleRoutedParamIndex() - 1 +
-                  regex.getGroupNumber(_, _))
+        (
+          // first group will have group number 1
+          result =
+            routeHandler
+                .getArg(routeHandler.getFirstPossibleRoutedParamIndex() - 1 +
+                    regex.getGroupNumber(_, _))
+          or
+          result = routeHandler.getVararg()
+        )
         or
-        result = routeHandler.getArgByName(regex.getGroupName(_, _))
+        exists(regex.getGroupName(_, _)) and
+        (
+          result = routeHandler.getArgByName(regex.getGroupName(_, _))
+          or
+          result = routeHandler.getKwarg()
+        )
       )
     }
   }

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

@@ -66,6 +66,9 @@ private module FastApi {
       result = this.getARequestHandler().getArgByName(_) and
       // type-annotated with `Response`
       not any(Response::RequestHandlerParam src).asExpr() = result
+      or
+      // **kwargs
+      result = this.getARequestHandler().getKwarg()
     }
 
     override DataFlow::Node getUrlPatternArg() {

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

@@ -279,6 +279,9 @@ module Flask {
           name = match.regexpCapture(werkzeug_rule_re(), 4)
         )
       )
+      or
+      // **kwargs
+      result = this.getARequestHandler().getKwarg()
     }
 
     override string getFramework() { result = "Flask" }
@@ -347,6 +350,12 @@ module Flask {
       // more FPs. If this turns out to be the wrong tradeoff, we can always change our mind.
       result in [this.getArg(_), this.getArgByName(_)] and
       not result = this.getArg(0)
+      or
+      // *args
+      result = this.getVararg()
+      or
+      // **kwargs
+      result = this.getKwarg()
     }
 
     override string getFramework() { result = "Flask" }

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

@@ -172,7 +172,10 @@ private module RestFramework {
       // Since we don't know the URL pattern, we simply mark all parameters as a routed
       // parameter. This should give us more RemoteFlowSources but could also lead to
       // more FPs. If this turns out to be the wrong tradeoff, we can always change our mind.
-      result in [this.getArg(_), this.getArgByName(_)] and
+      result in [
+          this.getArg(_), this.getArgByName(_), //
+          this.getVararg().(Parameter), this.getKwarg().(Parameter), // TODO: These sources should be modeled as storing content!
+        ] and
       not result = any(int i | i < this.getFirstPossibleRoutedParamIndex() | this.getArg(i))
     }
 

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

@@ -416,7 +416,10 @@ module Tornado {
       // more FPs. If this turns out to be the wrong tradeoff, we can always change our mind.
       exists(Function requestHandler | requestHandler = this.getARequestHandler() |
         not exists(this.getUrlPattern()) and
-        result in [requestHandler.getArg(_), requestHandler.getArgByName(_)] and
+        result in [
+            requestHandler.getArg(_), requestHandler.getArgByName(_),
+            requestHandler.getVararg().(Parameter), requestHandler.getKwarg().(Parameter)
+          ] and
         not result = requestHandler.getArg(0)
       )
       or
@@ -429,6 +432,12 @@ module Tornado {
         result = requestHandler.getArg(regex.getGroupNumber(_, _))
         or
         result = requestHandler.getArgByName(regex.getGroupName(_, _))
+        or
+        exists(regex.getGroupNumber(_, _)) and
+        result = requestHandler.getVararg()
+        or
+        exists(regex.getGroupName(_, _)) and
+        result = requestHandler.getKwarg()
       )
     }
   }
@@ -446,7 +455,10 @@ module Tornado {
       // Since we don't know the URL pattern, we simply mark all parameters as a routed
       // parameter. This should give us more RemoteFlowSources but could also lead to
       // more FPs. If this turns out to be the wrong tradeoff, we can always change our mind.
-      result in [this.getArg(_), this.getArgByName(_)] and
+      result in [
+          this.getArg(_), this.getArgByName(_), this.getVararg().(Parameter),
+          this.getKwarg().(Parameter)
+        ] and
       not result = this.getArg(0)
     }
 

python/ql/test/library-tests/frameworks/django-v2-v3/routing_test.py

@@ -150,3 +150,40 @@ def get(self, request): # $ requestHandler
 urlpatterns = [
     path("UnknownViewSubclass/", UnknownViewSubclass.as_view()),  # $ routeSetup="UnknownViewSubclass/"
 ]
+
+################################################################################
+# Routing to *args and **kwargs
+################################################################################
+
+def kwargs_param(request, **kwargs): # $ requestHandler routedParameter=kwargs
+    ensure_tainted(
+        kwargs, # $ tainted
+        kwargs["foo"], # $ tainted
+        kwargs["bar"]  # $ tainted
+    )
+
+    ensure_tainted(request) # $ tainted
+
+
+def star_args_param(request, *args): # $ requestHandler routedParameter=args
+    ensure_tainted(
+        args, # $ tainted
+        args[0], # $ tainted
+        args[1], # $ tainted
+    )
+    ensure_tainted(request) # $ tainted
+
+
+def star_args_param_check(request, foo, bar): # $ requestHandler routedParameter=foo routedParameter=bar
+    ensure_tainted(
+        foo, # $ tainted
+        bar, # $ tainted
+    )
+    ensure_tainted(request) # $ tainted
+
+
+urlpatterns = [
+    path("test-kwargs_param/<foo>/<bar>", kwargs_param),  # $ routeSetup="test-kwargs_param/<foo>/<bar>"
+    re_path("test-star_args_param/([^/]+)/(.+)", star_args_param),  # $ routeSetup="test-star_args_param/([^/]+)/(.+)"
+    re_path("test-star_args_param_check/([^/]+)/(.+)", star_args_param_check),  # $ routeSetup="test-star_args_param_check/([^/]+)/(.+)"
+]

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

@@ -1,5 +1,6 @@
 from rest_framework.decorators import api_view, parser_classes
 from rest_framework.views import APIView
+from rest_framework.viewsets import ModelViewSet
 from rest_framework.request import Request
 from rest_framework.response import Response
 from rest_framework.parsers import JSONParser
@@ -89,7 +90,7 @@ def test_taint(request: Request, routed_param): # $ requestHandler routedParamet
 
 
 class MyClass(APIView):
-    def initial(self, request, *args, **kwargs): # $ requestHandler
+    def initial(self, request, *args, **kwargs): # $ requestHandler routedParameter=kwargs
         # this method will be called before processing any request
         ensure_tainted(request) # $ tainted
 
@@ -107,12 +108,31 @@ def get(self, request: Request, routed_param): # $ requestHandler routedParamete
 
         return Response("ok") # $ HttpResponse
 
+# Viewsets
+# see https://www.django-rest-framework.org/api-guide/viewsets/
+
+class MyModelViewSet(ModelViewSet):
+    def retrieve(self, request, routed_param): # $ requestHandler routedParameter=routed_param
+        ensure_tainted(
+            request, # $ tainted
+            request.GET, # $ tainted
+            request.GET.get("pk"), # $ tainted
+            request.data # $ tainted
+        )
+
+        ensure_tainted(routed_param) # $ tainted
+
+        # same as for standard Django view
+        ensure_tainted(self.args, self.kwargs) # $ tainted
+
+        return Response("retrieve") # $ HttpResponse
 
 
 # fake setup, you can't actually run this
 urlpatterns = [
     path("test-taint/<routed_param>", test_taint),  # $ routeSetup="test-taint/<routed_param>"
     path("ClassView/<routed_param>", MyClass.as_view()), # $ routeSetup="ClassView/<routed_param>"
+    path("MyModelViewSet/<routed_param>", MyModelViewSet.as_view()) # $ routeSetup="MyModelViewSet/<routed_param>"
 ]
 
 # tests with no route-setup, but we can still tell that these are using Django REST