Create Markup.qll

Author: shyun020

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

@@ -0,0 +1,58 @@
+/**
+ * Provides classes modeling security-relevant aspects of the hypothetical `markup` PyPI package
+ * (imported as `markup`)
+ *
+ * This models parsing functions that may process untrusted input.
+ */
+
+ private import python
+ private import semmle.python.dataflow.new.DataFlow
+ private import semmle.python.Concepts
+ private import semmle.python.ApiGraphs
+ 
+ private module Markup {
+   /**
+    * A call to any of the parsing functions in `markup` (`parse`, `parse_document`,
+    * `unsafe_parse`, `unsafe_parse_document`, `safe_parse`, `safe_parse_document`)
+    *
+    * These functions may be unsafe if they parse untrusted markup content.
+    */
+   private class MarkupParseCall extends Decoding::Range, DataFlow::CallCfgNode {
+     override CallNode node;
+     string func_name;
+ 
+     MarkupParseCall() {
+       func_name in [
+           "parse", "parse_document", "unsafe_parse", "unsafe_parse_document",
+           "safe_parse", "safe_parse_document", "div", "page"
+         ] and
+       this = API::moduleImport("markup").getMember(func_name).getACall()
+     }
+ 
+     /**
+      * Determine whether this function call may unsafely execute input data.
+      *
+      * `unsafe_parse`, `unsafe_parse_document`, and `parse`, `parse_document` without secure settings
+      * are considered unsafe.
+      */
+     override predicate mayExecuteInput() {
+       func_name in ["unsafe_parse", "unsafe_parse_document"]
+       or
+       func_name in ["parse", "parse_document"] and
+       // If no safe mode argument is set, assume unsafe
+       not exists(DataFlow::Node mode_arg |
+         mode_arg in [this.getArg(1), this.getArgByName("mode")] |
+           mode_arg =
+             API::moduleImport("markup")
+                 .getMember(["SafeMode", "StrictMode"])
+                 .getAValueReachableFromSource()
+       )
+     }
+ 
+     override DataFlow::Node getAnInput() { result in [this.getArg(0), this.getArgByName("input")] }
+ 
+     override DataFlow::Node getOutput() { result = this }
+ 
+     override string getFormat() { result = "Markup" }
+   }
+ }