org.springframework.security.web.csrf.CsrfFilter Maven / Gradle / Ivy
/*
* Copyright 2002-2013 the original author or authors.
*
* Licensed 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.springframework.security.web.csrf;
import java.io.IOException;
import java.security.MessageDigest;
import java.util.Arrays;
import java.util.HashSet;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.core.log.LogMessage;
import org.springframework.security.access.AccessDeniedException;
import org.springframework.security.crypto.codec.Utf8;
import org.springframework.security.web.access.AccessDeniedHandler;
import org.springframework.security.web.access.AccessDeniedHandlerImpl;
import org.springframework.security.web.util.UrlUtils;
import org.springframework.security.web.util.matcher.RequestMatcher;
import org.springframework.util.Assert;
import org.springframework.web.filter.OncePerRequestFilter;
/**
*
* Applies
* CSRF
* protection using a synchronizer token pattern. Developers are required to ensure that
* {@link CsrfFilter} is invoked for any request that allows state to change. Typically
* this just means that they should ensure their web application follows proper REST
* semantics (i.e. do not change state with the HTTP methods GET, HEAD, TRACE, OPTIONS).
*
*
*
* Typically the {@link CsrfTokenRepository} implementation chooses to store the
* {@link CsrfToken} in {@link HttpSession} with {@link HttpSessionCsrfTokenRepository}
* wrapped by a {@link LazyCsrfTokenRepository}. This is preferred to storing the token in
* a cookie which can be modified by a client application.
*
*
* @author Rob Winch
* @since 3.2
*/
public final class CsrfFilter extends OncePerRequestFilter {
/**
* The default {@link RequestMatcher} that indicates if CSRF protection is required or
* not. The default is to ignore GET, HEAD, TRACE, OPTIONS and process all other
* requests.
*/
public static final RequestMatcher DEFAULT_CSRF_MATCHER = new DefaultRequiresCsrfMatcher();
/**
* The attribute name to use when marking a given request as one that should not be
* filtered.
*
* To use, set the attribute on your {@link HttpServletRequest}:
* CsrfFilter.skipRequest(request);
*
*/
private static final String SHOULD_NOT_FILTER = "SHOULD_NOT_FILTER" + CsrfFilter.class.getName();
private final Log logger = LogFactory.getLog(getClass());
private final CsrfTokenRepository tokenRepository;
private RequestMatcher requireCsrfProtectionMatcher = DEFAULT_CSRF_MATCHER;
private AccessDeniedHandler accessDeniedHandler = new AccessDeniedHandlerImpl();
public CsrfFilter(CsrfTokenRepository csrfTokenRepository) {
Assert.notNull(csrfTokenRepository, "csrfTokenRepository cannot be null");
this.tokenRepository = csrfTokenRepository;
}
@Override
protected boolean shouldNotFilter(HttpServletRequest request) throws ServletException {
return Boolean.TRUE.equals(request.getAttribute(SHOULD_NOT_FILTER));
}
@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
request.setAttribute(HttpServletResponse.class.getName(), response);
CsrfToken csrfToken = this.tokenRepository.loadToken(request);
boolean missingToken = (csrfToken == null);
if (missingToken) {
csrfToken = this.tokenRepository.generateToken(request);
this.tokenRepository.saveToken(csrfToken, request, response);
}
request.setAttribute(CsrfToken.class.getName(), csrfToken);
request.setAttribute(csrfToken.getParameterName(), csrfToken);
if (!this.requireCsrfProtectionMatcher.matches(request)) {
if (this.logger.isTraceEnabled()) {
this.logger.trace("Did not protect against CSRF since request did not match "
+ this.requireCsrfProtectionMatcher);
}
filterChain.doFilter(request, response);
return;
}
String actualToken = request.getHeader(csrfToken.getHeaderName());
if (actualToken == null) {
actualToken = request.getParameter(csrfToken.getParameterName());
}
if (!equalsConstantTime(csrfToken.getToken(), actualToken)) {
this.logger.debug(
LogMessage.of(() -> "Invalid CSRF token found for " + UrlUtils.buildFullRequestUrl(request)));
AccessDeniedException exception = (!missingToken) ? new InvalidCsrfTokenException(csrfToken, actualToken)
: new MissingCsrfTokenException(actualToken);
this.accessDeniedHandler.handle(request, response, exception);
return;
}
filterChain.doFilter(request, response);
}
public static void skipRequest(HttpServletRequest request) {
request.setAttribute(SHOULD_NOT_FILTER, Boolean.TRUE);
}
/**
* Specifies a {@link RequestMatcher} that is used to determine if CSRF protection
* should be applied. If the {@link RequestMatcher} returns true for a given request,
* then CSRF protection is applied.
*
*
* The default is to apply CSRF protection for any HTTP method other than GET, HEAD,
* TRACE, OPTIONS.
*
* @param requireCsrfProtectionMatcher the {@link RequestMatcher} used to determine if
* CSRF protection should be applied.
*/
public void setRequireCsrfProtectionMatcher(RequestMatcher requireCsrfProtectionMatcher) {
Assert.notNull(requireCsrfProtectionMatcher, "requireCsrfProtectionMatcher cannot be null");
this.requireCsrfProtectionMatcher = requireCsrfProtectionMatcher;
}
/**
* Specifies a {@link AccessDeniedHandler} that should be used when CSRF protection
* fails.
*
*
* The default is to use AccessDeniedHandlerImpl with no arguments.
*
* @param accessDeniedHandler the {@link AccessDeniedHandler} to use
*/
public void setAccessDeniedHandler(AccessDeniedHandler accessDeniedHandler) {
Assert.notNull(accessDeniedHandler, "accessDeniedHandler cannot be null");
this.accessDeniedHandler = accessDeniedHandler;
}
/**
* Constant time comparison to prevent against timing attacks.
* @param expected
* @param actual
* @return
*/
private static boolean equalsConstantTime(String expected, String actual) {
byte[] expectedBytes = bytesUtf8(expected);
byte[] actualBytes = bytesUtf8(actual);
return MessageDigest.isEqual(expectedBytes, actualBytes);
}
private static byte[] bytesUtf8(String s) {
// need to check if Utf8.encode() runs in constant time (probably not).
// This may leak length of string.
return (s != null) ? Utf8.encode(s) : null;
}
private static final class DefaultRequiresCsrfMatcher implements RequestMatcher {
private final HashSet allowedMethods = new HashSet<>(Arrays.asList("GET", "HEAD", "TRACE", "OPTIONS"));
@Override
public boolean matches(HttpServletRequest request) {
return !this.allowedMethods.contains(request.getMethod());
}
@Override
public String toString() {
return "CsrfNotRequired " + this.allowedMethods;
}
}
}