[pitboss] phase 05: Track J.3 + Track L.3 — XXE corpus + DocumentBuilder / lxml / libxml / SimpleXML adapters

src/dynamic/framework/adapters/xxe_python.rs

@@ -0,0 +1,120 @@
+//! Python [`super::super::FrameworkAdapter`] matching XXE-prone XML
+//! parser constructions.
+//!
+//! Phase 05 (Track J.3).  Fires when the function body invokes one of
+//! the canonical lxml / stdlib XML entry points
+//! (`lxml.etree.XMLParser`, `lxml.etree.parse`, `lxml.etree.fromstring`,
+//! `xml.etree.ElementTree.parse`, `xml.sax.parse`,
+//! `xml.dom.minidom.parseString`) and the surrounding source mentions
+//! the matching module.  Callee matching is last-segment-aware so
+//! receiver-prefixed calls (`etree.XMLParser`,
+//! `ElementTree.fromstring`) hit the same predicate.
+
+use crate::dynamic::framework::{FrameworkAdapter, FrameworkBinding};
+use crate::evidence::EntryKind;
+use crate::summary::FuncSummary;
+use crate::symbol::Lang;
+
+pub struct XxePythonAdapter;
+
+const ADAPTER_NAME: &str = "xxe-python";
+
+fn callee_is_xml_parser(name: &str) -> bool {
+    let last = name.rsplit_once('.').map(|(_, s)| s).unwrap_or(name);
+    matches!(
+        last,
+        "XMLParser"
+            | "parse"
+            | "fromstring"
+            | "parseString"
+            | "XMLPullParser"
+            | "iterparse"
+    )
+}
+
+fn source_imports_xml(file_bytes: &[u8]) -> bool {
+    const NEEDLES: &[&[u8]] = &[
+        b"lxml.etree",
+        b"lxml import",
+        b"xml.etree",
+        b"ElementTree",
+        b"xml.sax",
+        b"xml.dom",
+        b"defusedxml",
+    ];
+    NEEDLES
+        .iter()
+        .any(|n| file_bytes.windows(n.len()).any(|w| w == *n))
+}
+
+impl FrameworkAdapter for XxePythonAdapter {
+    fn name(&self) -> &'static str {
+        ADAPTER_NAME
+    }
+
+    fn lang(&self) -> Lang {
+        Lang::Python
+    }
+
+    fn detect(
+        &self,
+        summary: &FuncSummary,
+        _ast: tree_sitter::Node<'_>,
+        file_bytes: &[u8],
+    ) -> Option<FrameworkBinding> {
+        let matches_call = super::any_callee_matches(summary, callee_is_xml_parser);
+        let matches_source = source_imports_xml(file_bytes);
+        if matches_call && matches_source {
+            Some(FrameworkBinding {
+                adapter: ADAPTER_NAME.to_owned(),
+                kind: EntryKind::Function,
+                route: None,
+                request_params: Vec::new(),
+                response_writer: None,
+                middleware: Vec::new(),
+            })
+        } else {
+            None
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn parse_python(src: &[u8]) -> tree_sitter::Tree {
+        let mut parser = tree_sitter::Parser::new();
+        let lang = tree_sitter::Language::from(tree_sitter_python::LANGUAGE);
+        parser.set_language(&lang).unwrap();
+        parser.parse(src, None).unwrap()
+    }
+
+    #[test]
+    fn fires_on_lxml_etree_fromstring() {
+        let src: &[u8] = b"from lxml import etree\n\
+            def run(body):\n    return etree.fromstring(body)\n";
+        let tree = parse_python(src);
+        let summary = FuncSummary {
+            name: "run".into(),
+            callees: vec![crate::summary::CalleeSite::bare("fromstring")],
+            ..Default::default()
+        };
+        assert!(XxePythonAdapter
+            .detect(&summary, tree.root_node(), src)
+            .is_some());
+    }
+
+    #[test]
+    fn skips_plain_function() {
+        let src: &[u8] = b"def add(a, b):\n    return a + b\n";
+        let tree = parse_python(src);
+        let summary = FuncSummary {
+            name: "add".into(),
+            ..Default::default()
+        };
+        assert!(XxePythonAdapter
+            .detect(&summary, tree.root_node(), src)
+            .is_none());
+    }
+}