ppkarwasz commented on code in PR #42:
URL: https://github.com/apache/commons-xml/pull/42#discussion_r3857483707
##########
src/test/java/org/apache/commons/xml/EntityResolverFloorTest.java:
##########
@@ -352,7 +361,41 @@ void transformerDeniesUnlisted() {
.transform(AttackTestSupport.streamSource("<root/>"), new
StreamResult(sink));
assertFalse(sink.toString().contains(AttackTestSupport.LEAKED_MARKER),
"unlisted stylesheet import leaked");
} catch (final TransformerException blocked) {
- // Acceptable: rejected at compile rather than resolved to empty.
+ // Throwing is an acceptable outcome, since it doesn't leak the
marker.
+ }
+ }
+
+ @Test
+ @Tag("trax")
+ void transformerParsesOptedInImportHardened() {
+ // The opted-in module carries an external DTD reference; parsed on
the floor the DTD is empty, so its entity cannot expand into the output.
+ final TransformerFactory factory = hardenedTransformerFactory();
+ factory.setURIResolver((href, base) ->
+ href != null && href.endsWith("included.xsl") ?
AttackTestSupport.resourceSource("included-with-entity.xsl") : null);
+ try {
+ final StringWriter sink = new StringWriter();
+
factory.newTemplates(AttackTestSupport.resourceSource("with-import.xsl")).newTransformer()
+ .transform(AttackTestSupport.streamSource("<root/>"), new
StreamResult(sink));
+
assertFalse(sink.toString().contains(AttackTestSupport.LEAKED_MARKER),
"opted-in stylesheet import leaked its external entity");
+ } catch (final TransformerException blocked) {
Review Comment:
It turns out the failure never happens: I probed every CI combination (JDK
8–25 × XSLTC, Xalan, Saxon, over both SAX parsers) and the transform always
completes — the floor resolves to a well-formed empty document that every
implementation accepts, and the entity left undeclared by an emptied DTD is
only a validity violation, which non-validating parsers skip. Since not
throwing is the invariant, d2a3568 drops the try/catch and uses
`assertDoesNotThrow` in all three tests, with comments explaining why the
outcome is deterministic.
##########
src/test/java/org/apache/commons/xml/EntityResolverFloorTest.java:
##########
@@ -352,7 +361,41 @@ void transformerDeniesUnlisted() {
.transform(AttackTestSupport.streamSource("<root/>"), new
StreamResult(sink));
assertFalse(sink.toString().contains(AttackTestSupport.LEAKED_MARKER),
"unlisted stylesheet import leaked");
} catch (final TransformerException blocked) {
- // Acceptable: rejected at compile rather than resolved to empty.
+ // Throwing is an acceptable outcome, since it doesn't leak the
marker.
+ }
+ }
+
+ @Test
+ @Tag("trax")
+ void transformerParsesOptedInImportHardened() {
+ // The opted-in module carries an external DTD reference; parsed on
the floor the DTD is empty, so its entity cannot expand into the output.
+ final TransformerFactory factory = hardenedTransformerFactory();
+ factory.setURIResolver((href, base) ->
+ href != null && href.endsWith("included.xsl") ?
AttackTestSupport.resourceSource("included-with-entity.xsl") : null);
+ try {
+ final StringWriter sink = new StringWriter();
+
factory.newTemplates(AttackTestSupport.resourceSource("with-import.xsl")).newTransformer()
+ .transform(AttackTestSupport.streamSource("<root/>"), new
StreamResult(sink));
+
assertFalse(sink.toString().contains(AttackTestSupport.LEAKED_MARKER),
"opted-in stylesheet import leaked its external entity");
+ } catch (final TransformerException blocked) {
+ // Throwing is an acceptable outcome, since it doesn't leak the
marker.
+ }
+ }
+
+ @Test
+ @Tag("trax")
+ void transformerParsesOptedInDocumentHardened() {
+ // Same contract on the runtime document() channel, which reaches a
different internal reader than the compile-time import.
+ final TransformerFactory factory = hardenedTransformerFactory();
+ factory.setURIResolver((href, base) ->
+ href != null && href.endsWith("referenced.xml") ?
AttackTestSupport.resourceSource("referenced-with-entity.xml") : null);
+ try {
+ final StringWriter sink = new StringWriter();
+
factory.newTemplates(AttackTestSupport.resourceSource("with-document.xsl")).newTransformer()
+ .transform(AttackTestSupport.streamSource("<root/>"), new
StreamResult(sink));
+
assertFalse(sink.toString().contains(AttackTestSupport.LEAKED_MARKER),
"opted-in document() resource leaked its external entity");
+ } catch (final TransformerException blocked) {
+ // Throwing is an acceptable outcome, since it doesn't leak the
marker.
Review Comment:
Same resolution as above: the failure turned out to be impossible on the
tested matrix, so d2a3568 asserts the strict no-throw/no-leak outcome here too.
##########
src/test/java/org/apache/commons/xml/EntityResolverFloorTest.java:
##########
@@ -352,7 +361,41 @@ void transformerDeniesUnlisted() {
.transform(AttackTestSupport.streamSource("<root/>"), new
StreamResult(sink));
assertFalse(sink.toString().contains(AttackTestSupport.LEAKED_MARKER),
"unlisted stylesheet import leaked");
} catch (final TransformerException blocked) {
- // Acceptable: rejected at compile rather than resolved to empty.
+ // Throwing is an acceptable outcome, since it doesn't leak the
marker.
+ }
+ }
+
+ @Test
+ @Tag("trax")
+ void transformerParsesOptedInImportHardened() {
+ // The opted-in module carries an external DTD reference; parsed on
the floor the DTD is empty, so its entity cannot expand into the output.
+ final TransformerFactory factory = hardenedTransformerFactory();
+ factory.setURIResolver((href, base) ->
+ href != null && href.endsWith("included.xsl") ?
AttackTestSupport.resourceSource("included-with-entity.xsl") : null);
+ try {
+ final StringWriter sink = new StringWriter();
+
factory.newTemplates(AttackTestSupport.resourceSource("with-import.xsl")).newTransformer()
+ .transform(AttackTestSupport.streamSource("<root/>"), new
StreamResult(sink));
+
assertFalse(sink.toString().contains(AttackTestSupport.LEAKED_MARKER),
"opted-in stylesheet import leaked its external entity");
+ } catch (final TransformerException blocked) {
Review Comment:
I rechecked and apparently these throws are now stale: both Xalan and Saxon
are happy with the kind of empty resource they receive.
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