ppkarwasz commented on code in PR #103:
URL:
https://github.com/apache/commons-secure-xml/pull/103#discussion_r4093170504
##########
src/main/javadoc/overview.html:
##########
@@ -526,6 +526,69 @@ <h1>
href="../threat_model.html">Threat Model</a> documents the resulting
contract.
</p>
</section>
+ <section id="jaxb">
+ <h1>
+ <img src="org/apache/commons/xml/secure/doc-files/leaf.svg"
style="height: 1em; padding-right: 0.25em" alt="leaf">Migrating JAXB
Review Comment:
I would add this to the **website** documentation, not the Javadoc, since it
will evolve in time **independently** of the library.
On the same page we could add workarounds for other library limitations: for
example dom4j installs an allow-all resolver on each read and we need to
counter it with:
```java
SAXReader reader = new
SAXReader(SecureSAXParserFactory.newInstance().newSAXParser().getXMLReader());
reader.setEntityResolver((p, s) -> null);
```
##########
src/test/java/org/apache/commons/xml/secure/JaxbExamples.java:
##########
@@ -0,0 +1,73 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.commons.xml.secure;
+
+import java.io.InputStream;
+
+import javax.xml.bind.JAXBContext;
+import javax.xml.bind.Unmarshaller;
+import javax.xml.parsers.SAXParserFactory;
+import javax.xml.stream.XMLInputFactory;
+import javax.xml.stream.XMLStreamReader;
+import javax.xml.transform.sax.SAXSource;
+
+import org.xml.sax.InputSource;
+import org.xml.sax.XMLReader;
+
+/**
+ * Examples for the Javadoc {@code overview.html} file.
+ */
+public class JaxbExamples {
+
+ static class MyJaxbModel {
+ // JAXB model fields and methods
+ }
+
+ public MyJaxbModel unmarshalSecurelyWithSax(InputStream xmlStream) throws
Exception {
+ JAXBContext context = JAXBContext.newInstance(MyJaxbModel.class);
+ Unmarshaller unmarshaller = context.createUnmarshaller();
+
+ // Create a secure SAXParserFactory via Apache Commons Secure XML
+ SAXParserFactory spf = SecureSAXParserFactory.newDefaultNSInstance();
+
+ // Generate a hardened XMLReader and wrap the input source
+ XMLReader xmlReader = spf.newSAXParser().getXMLReader();
+ SAXSource source = new SAXSource(xmlReader, new
InputSource(xmlStream));
+
+ // Safe from XXE injection and entity-expansion DoS attacks
+ return (MyJaxbModel) unmarshaller.unmarshal(source);
Review Comment:
These would be ideal as copy-paste snippets from the website, so it is worth
naming what they replace. Every `Unmarshaller` overload that takes raw bytes or
a location builds the parser internally, so our hardening never applies:
- `unmarshal(File)`
- `unmarshal(InputStream)`
- `unmarshal(Reader)`
- `unmarshal(URL)`
- `unmarshal(InputSource)`
- `unmarshal(Source)` and `unmarshal(Source, Class)`, when given a
`StreamSource` or a `SAXSource` with a null `XMLReader`
We could offer helpers such as `unmarshalSecure(Unmarshaller, File)` that
wrap the input in a `SAXSource` from our factories, giving a mechanical
one-line replacement.
In our tests I would rather **test** that the examples resist entity
expansion and XXE.
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