cherrypy framework file system access Sinks are added

Author: am0o0

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

@@ -0,0 +1,48 @@
+/**
+ * Provides classes modeling security-relevant aspects of the `cherrypy` PyPI package.
+ */
+
+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
+
+/**
+ * Provides models for the `cherrypy` PyPI package.
+ * See https://cherrypy.dev/.
+ */
+private module Cherrypy {
+  /**
+   * Holds for an instance of `cherrypy.lib.static`
+   */
+  API::Node libStatic() {
+    result = API::moduleImport("cherrypy").getMember("lib").getMember("static")
+  }
+
+  /**
+   * A call to the `serve_file` or `serve_download`or `staticfile` functions of `cherrypy.lib.static` as a sink for Filesystem access.
+   */
+  class FileResponseCall extends FileSystemAccess::Range, API::CallNode {
+    string funcName;
+
+    FileResponseCall() {
+      this = libStatic().getMember("staticfile").getACall() and
+      funcName = "staticfile"
+      or
+      this = libStatic().getMember("serve_file").getACall() and
+      funcName = "serve_file"
+      or
+      this = libStatic().getMember("serve_download").getACall() and
+      funcName = "serve_download"
+    }
+
+    override DataFlow::Node getAPathArgument() {
+      result = this.getParameter(0, "path").asSink() and funcName = ["serve_download", "serve_file"]
+      or
+      result = this.getParameter(0, "filename").asSink() and
+      funcName = "staticfile"
+    }
+  }
+}

python/ql/test/library-tests/frameworks/FileSystemAccess/cherrypy.py

@@ -0,0 +1,8 @@
+import cherrypy
+from cherrypy.lib.static import serve_file, serve_download, staticfile
+
+serve_file("file")  # $ getAPathArgument="file"
+serve_download("file")  # $ getAPathArgument="file"
+staticfile("file")  # $ getAPathArgument="file"
+# root won't make this safe
+staticfile("file", root="/path/to/safe/dir") # $ getAPathArgument="file"