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Ensuring secure XSLT processing everywhere
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201 changes: 201 additions & 0 deletions
201
core/src/main/java/org/apache/syncope/core/rest/controller/XSLTTransformer.java
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| /* | ||
| * 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 | ||
| * | ||
| * http://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.syncope.core.rest.controller; | ||
|
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| import java.util.HashMap; | ||
| import java.util.Map; | ||
| import java.util.regex.Pattern; | ||
| import javax.xml.XMLConstants; | ||
| import javax.xml.transform.Source; | ||
| import javax.xml.transform.Templates; | ||
| import javax.xml.transform.Transformer; | ||
| import javax.xml.transform.TransformerConfigurationException; | ||
| import javax.xml.transform.sax.SAXResult; | ||
| import javax.xml.transform.sax.SAXTransformerFactory; | ||
| import javax.xml.transform.sax.TransformerHandler; | ||
| import org.apache.cocoon.pipeline.SetupException; | ||
| import org.apache.cocoon.pipeline.caching.CacheKey; | ||
| import org.apache.cocoon.pipeline.component.CachingPipelineComponent; | ||
| import org.apache.cocoon.pipeline.util.StringRepresentation; | ||
| import org.apache.cocoon.sax.AbstractSAXTransformer; | ||
| import org.apache.cocoon.sax.SAXConsumer; | ||
| import org.apache.cocoon.sax.util.SAXConsumerAdapter; | ||
| import org.apache.syncope.core.util.VoidURIResolver; | ||
| import org.slf4j.Logger; | ||
| import org.slf4j.LoggerFactory; | ||
|
|
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| public class XSLTTransformer extends AbstractSAXTransformer implements CachingPipelineComponent { | ||
|
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| private static final Logger LOG = LoggerFactory.getLogger(XSLTTransformer.class); | ||
|
|
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| /** | ||
| * A generic transformer factory to parse XSLTs. | ||
| */ | ||
| private static final SAXTransformerFactory TRAX_FACTORY = createNewSAXTransformerFactory(); | ||
|
|
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| /** | ||
| * The XSLT parameters name pattern. | ||
| */ | ||
| private static final Pattern XSLT_PARAMETER_NAME_PATTERN = Pattern.compile("[a-zA-Z_][\\w\\-\\.]*"); | ||
|
|
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| /** | ||
| * The XSLT parameters reference. | ||
| */ | ||
| private Map<String, Object> parameters; | ||
|
|
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| /** | ||
| * The XSLT Template reference. | ||
| */ | ||
| private Templates templates; | ||
|
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| private Source source; | ||
|
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| public XSLTTransformer(final Source source) { | ||
| super(); | ||
| this.load(source, null); | ||
| } | ||
|
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| /** | ||
| * Creates a new transformer reading the XSLT from the Source source and setting the TransformerFactory attributes. | ||
| * | ||
| * This constructor is useful when users want to perform XSLT transformation using <a | ||
| * href="http://xml.apache.org/xalan-j/xsltc_usage.html">xsltc</a>. | ||
| * | ||
| * @param source the XSLT source | ||
| * @param attributes the Transformer Factory attributes | ||
| */ | ||
| public XSLTTransformer(final Source source, final Map<String, Object> attributes) { | ||
| super(); | ||
| this.load(source, attributes); | ||
| } | ||
|
|
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| /** | ||
| * Method useful to create a new transformer reading the XSLT from the URL source and setting the Transformer | ||
| * Factory attributes. | ||
| * | ||
| * This method is useful when users want to perform XSLT transformation using <a | ||
| * href="http://xml.apache.org/xalan-j/xsltc_usage.html">xsltc</a>. | ||
| * | ||
| * @param source the XSLT source | ||
| * @param attributes the Transformer Factory attributes | ||
| */ | ||
| private void load(final Source source, final Map<String, Object> attributes) { | ||
| if (source == null) { | ||
| throw new IllegalArgumentException("The parameter 'source' mustn't be null."); | ||
| } | ||
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| this.source = source; | ||
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| this.load(this.source, this.source.toString(), attributes); | ||
| } | ||
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| private void load(final Source source, final String localCacheKey, final Map<String, Object> attributes) { | ||
| LOG.debug("{} local cache miss: {}", getClass().getSimpleName(), localCacheKey); | ||
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| // XSLT has to be parsed | ||
| final SAXTransformerFactory transformerFactory; | ||
| if (attributes == null || attributes.isEmpty()) { | ||
| transformerFactory = TRAX_FACTORY; | ||
| } else { | ||
| transformerFactory = createNewSAXTransformerFactory(); | ||
| for (Map.Entry<String, Object> attribute : attributes.entrySet()) { | ||
| transformerFactory.setAttribute(attribute.getKey(), attribute.getValue()); | ||
| } | ||
| } | ||
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| try { | ||
| this.templates = transformerFactory.newTemplates(source); | ||
| } catch (TransformerConfigurationException e) { | ||
| throw new SetupException("Impossible to read XSLT from '" + source + "', see nested exception", e); | ||
| } | ||
| } | ||
|
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| /** | ||
| * Sets the XSLT parameters to be applied to XSLT stylesheet. | ||
| * | ||
| * @param parameters the XSLT parameters to be applied to XSLT stylesheet | ||
| */ | ||
| public void setParameters(final Map<String, ? extends Object> parameters) { | ||
| if (parameters == null) { | ||
| this.parameters = null; | ||
| } else { | ||
| this.parameters = new HashMap<String, Object>(parameters); | ||
| } | ||
| } | ||
|
|
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| /** | ||
| * {@inheritDoc} | ||
| */ | ||
| @Override | ||
| protected void setSAXConsumer(final SAXConsumer consumer) { | ||
| TransformerHandler transformerHandler; | ||
| try { | ||
| transformerHandler = TRAX_FACTORY.newTransformerHandler(this.templates); | ||
| } catch (Exception e) { | ||
| throw new SetupException("Could not initialize transformer handler.", e); | ||
| } | ||
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| if (this.parameters != null) { | ||
| final Transformer transformer = transformerHandler.getTransformer(); | ||
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| for (Map.Entry<String, Object> entry : this.parameters.entrySet()) { | ||
| final String name = entry.getKey(); | ||
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| // is valid XSLT parameter name | ||
| if (XSLT_PARAMETER_NAME_PATTERN.matcher(name).matches()) { | ||
| transformer.setParameter(name, entry.getValue()); | ||
| } | ||
| } | ||
| } | ||
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| final SAXResult result = new SAXResult(); | ||
| result.setHandler(consumer); | ||
| // According to TrAX specs, all TransformerHandlers are LexicalHandlers | ||
| result.setLexicalHandler(consumer); | ||
| transformerHandler.setResult(result); | ||
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| final SAXConsumerAdapter saxConsumerAdapter = new SAXConsumerAdapter(); | ||
| saxConsumerAdapter.setContentHandler(transformerHandler); | ||
| super.setSAXConsumer(saxConsumerAdapter); | ||
| } | ||
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| @Override | ||
| public CacheKey constructCacheKey() { | ||
| return null; | ||
| } | ||
|
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| /** | ||
| * Utility method to create a new transformer factory. | ||
| * | ||
| * @return a new transformer factory | ||
| */ | ||
| private static SAXTransformerFactory createNewSAXTransformerFactory() { | ||
| SAXTransformerFactory transformerFactory = (SAXTransformerFactory) SAXTransformerFactory.newInstance(); | ||
| transformerFactory.setURIResolver(new VoidURIResolver()); | ||
| try { | ||
| transformerFactory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true); | ||
| } catch (TransformerConfigurationException e) { | ||
| LOG.error("Could not enable secure XML processing", e); | ||
| } | ||
| return transformerFactory; | ||
| } | ||
|
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| @Override | ||
| public String toString() { | ||
| return StringRepresentation.buildString(this, "src=<" + this.source + ">"); | ||
| } | ||
| } |
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35 changes: 35 additions & 0 deletions
35
core/src/main/java/org/apache/syncope/core/util/VoidURIResolver.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,35 @@ | ||
| /* | ||
| * 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 | ||
| * | ||
| * http://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.syncope.core.util; | ||
|
|
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| import javax.xml.transform.Source; | ||
| import javax.xml.transform.TransformerException; | ||
| import javax.xml.transform.URIResolver; | ||
|
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| /** | ||
| * This implementation disallows any XSLT include, for security reasons. | ||
| */ | ||
| public class VoidURIResolver implements URIResolver { | ||
|
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| @Override | ||
| public Source resolve(final String href, final String base) throws TransformerException { | ||
| return null; | ||
| } | ||
|
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| } |