92 lines
3.1 KiB
Java
92 lines
3.1 KiB
Java
/*
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* Copyright 2018 Red Hat, Inc. and/or its affiliates
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* and other contributors as indicated by the @author tags.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.keycloak.theme;
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import freemarker.template.TemplateMethodModelEx;
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import freemarker.template.TemplateModelException;
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import org.owasp.html.Encoding;
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import java.util.List;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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/**
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* Allows sanitizing of html that uses Freemarker ?no_esc. This way, html
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* can be allowed but it is still cleaned up for safety. Tags and attributes
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* deemed unsafe will be stripped out.
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*/
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public class KeycloakSanitizerMethod implements TemplateMethodModelEx {
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private static final Pattern HREF_PATTERN = Pattern.compile("\\s+href=\"([^\"]*)\"");
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@Override
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public Object exec(List list) throws TemplateModelException {
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if ((list.isEmpty()) || (list.get(0) == null)) {
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throw new NullPointerException("Can not escape null value.");
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}
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String html = list.get(0).toString();
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html = decodeHtmlFull(html);
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String sanitized = KeycloakSanitizerPolicy.POLICY_DEFINITION.sanitize(html);
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return fixURLs(sanitized);
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}
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// Fully decode HTML. Assume it can be encoded multiple times
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private String decodeHtmlFull(String html) {
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if (html == null) return null;
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int MAX_DECODING_COUNT = 5; // Max count of attempts for decoding HTML (in case it was encoded multiple times)
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String decodedHtml;
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for (int i = 0; i < MAX_DECODING_COUNT; i++) {
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decodedHtml = Encoding.decodeHtml(html);
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if (decodedHtml.equals(html)) {
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// HTML is decoded. We can return it
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return html;
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} else {
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// Next attempt
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html = decodedHtml;
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}
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}
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return "";
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}
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private String fixURLs(String msg) {
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Matcher matcher = HREF_PATTERN.matcher(msg);
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if (matcher.find()) {
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int last = 0;
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StringBuilder result = new StringBuilder(msg.length());
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do {
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String href = matcher.group(1).replaceAll("=", "=")
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.replaceAll("\\.\\.", ".")
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.replaceAll("&", "&");
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result.append(msg.substring(last, matcher.start(1))).append(href);
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last = matcher.end(1);
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} while (matcher.find());
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result.append(msg.substring(last));
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return result.toString();
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}
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return msg;
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}
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}
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