org.apache.catalina.filters

Class CsrfPreventionFilter

java.lang.Object

org.apache.catalina.filters.FilterBase

org.apache.catalina.filters.CsrfPreventionFilter

All Implemented Interfaces:

javax.servlet.Filter

public class CsrfPreventionFilter
extends FilterBase

Provides basic CSRF protection for a web application. The filter assumes that:

• The filter is mapped to /*
• HttpServletResponse.encodeRedirectURL(String) and HttpServletResponse.encodeURL(String) are used to encode all URLs returned to the client

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	CsrfPreventionFilter.CsrfResponseWrapper
protected static class	CsrfPreventionFilter.LruCache<T>

Field Summary

Fields

Modifier and Type	Field and Description
protected static Logger	log

Fields inherited from class org.apache.catalina.filters.FilterBase

rb

Constructor Summary

Constructors

Constructor and Description
CsrfPreventionFilter()

Method Summary

Modifier and Type	Method and Description
void	doFilter(javax.servlet.ServletRequest request, javax.servlet.ServletResponse response, javax.servlet.FilterChain chain)
protected String	generateNonce() Generate a once time token (nonce) for authenticating subsequent requests.
protected Logger	getLogger()
void	init(javax.servlet.FilterConfig filterConfig)
protected boolean	isConfigProblemFatal() Determines if an exception when calling a setter or an unknown configuration attribute triggers the failure of the this filter which in turn will prevent the web application from starting.
void	setEntryPoints(String entryPoints) Entry points are URLs that will not be tested for the presence of a valid nonce.
void	setNonceCacheSize(int nonceCacheSize) Sets the number of previously issued nonces that will be cached on a LRU basis to support parallel requests, limited use of the refresh and back in the browser and similar behaviors that may result in the submission of a previous nonce rather than the current one.
void	setRandomClass(String randomClass) Specify the class to use to generate the nonces.

Methods inherited from class org.apache.catalina.filters.FilterBase

destroy

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

log

protected static final Logger log

Constructor Detail

CsrfPreventionFilter

public CsrfPreventionFilter()

Method Detail

getLogger

protected Logger getLogger()

Specified by:

getLogger in class FilterBase

setEntryPoints

public void setEntryPoints(String entryPoints)

Entry points are URLs that will not be tested for the presence of a valid nonce. They are used to provide a way to navigate back to a protected application after navigating away from it. Entry points will be limited to HTTP GET requests and should not trigger any security sensitive actions.

Parameters:

entryPoints - Comma separated list of URLs to be configured as entry points.

setNonceCacheSize

public void setNonceCacheSize(int nonceCacheSize)

Sets the number of previously issued nonces that will be cached on a LRU basis to support parallel requests, limited use of the refresh and back in the browser and similar behaviors that may result in the submission of a previous nonce rather than the current one. If not set, the default value of 5 will be used.

Parameters:

nonceCacheSize - The number of nonces to cache

setRandomClass

public void setRandomClass(String randomClass)

Specify the class to use to generate the nonces. Must be in instance of Random.

Parameters:

randomClass - The name of the class to use

init

public void init(javax.servlet.FilterConfig filterConfig)
          throws javax.servlet.ServletException

Specified by:

init in interface javax.servlet.Filter

Overrides:

init in class FilterBase

Throws:

javax.servlet.ServletException

doFilter

public void doFilter(javax.servlet.ServletRequest request,
                     javax.servlet.ServletResponse response,
                     javax.servlet.FilterChain chain)
              throws IOException,
                     javax.servlet.ServletException

Throws:

IOException

javax.servlet.ServletException

isConfigProblemFatal

protected boolean isConfigProblemFatal()

Description copied from class: FilterBase

Determines if an exception when calling a setter or an unknown configuration attribute triggers the failure of the this filter which in turn will prevent the web application from starting.

Overrides:

isConfigProblemFatal in class FilterBase

Returns:

true if a problem should trigger the failure of this filter, else false

generateNonce

protected String generateNonce()

Generate a once time token (nonce) for authenticating subsequent requests. This will also add the token to the session. The nonce generation is a simplified version of ManagerBase.generateSessionId().