Package org.apache.catalina.filters

Class RestCsrfPreventionFilter

java.lang.Object

org.apache.catalina.filters.FilterBase

org.apache.catalina.filters.CsrfPreventionFilterBase

org.apache.catalina.filters.RestCsrfPreventionFilter

All Implemented Interfaces:

Filter

public class RestCsrfPreventionFilter
extends CsrfPreventionFilterBase

Provides basic CSRF protection for REST APIs. The filter assumes that the clients have adapted the transfer of the nonce through the 'X-CSRF-Token' header.

 Positive scenario:
           Client                            Server
              |                                 |
              | GET Fetch Request              \| JSESSIONID
              |---------------------------------| X-CSRF-Token
              |                                /| pair generation
              |/Response to Fetch Request       |
              |---------------------------------|
 JSESSIONID   |\                                |
 X-CSRF-Token |                                 |
 pair cached  | POST Request with valid nonce  \| JSESSIONID
              |---------------------------------| X-CSRF-Token
              |                                /| pair validation
              |/ Response to POST Request       |
              |---------------------------------|
              |\                                |

 Negative scenario:
           Client                            Server
              |                                 |
              | POST Request without nonce     \| JSESSIONID
              |---------------------------------| X-CSRF-Token
              |                                /| pair validation
              |/Request is rejected             |
              |---------------------------------|
              |\                                |

           Client                            Server
              |                                 |
              | POST Request with invalid nonce\| JSESSIONID
              |---------------------------------| X-CSRF-Token
              |                                /| pair validation
              |/Request is rejected             |
              |---------------------------------|
              |\                                |
 

Field Summary

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

sm

Constructor Summary

Constructors

Constructor	Description
RestCsrfPreventionFilter()

Method Summary

Modifier and Type	Method	Description
void	doFilter(ServletRequest request, ServletResponse response, FilterChain chain)	The doFilter method of the Filter is called by the container each time a request/response pair is passed through the chain due to a client request for a resource at the end of the chain.
Set<String>	getPathsAcceptingParams()
void	init(FilterConfig filterConfig)	Iterates over the configuration parameters and either logs a warning, or throws an exception for any parameter that does not have a matching setter in this filter.
void	setPathsAcceptingParams(String pathsList)	A comma separated list of URLs that can accept nonces via request parameter 'X-CSRF-Token'.

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

generateNonce, generateNonce, getDenyStatus, getLogger, getRequestedPath, isConfigProblemFatal, setDenyStatus, setRandomClass

Methods inherited from class java.lang.Object

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

Methods inherited from interface javax.servlet.Filter

destroy

Constructor Details

RestCsrfPreventionFilter

public RestCsrfPreventionFilter()

Method Details

init

public void init(FilterConfig filterConfig)
          throws ServletException

Description copied from class: FilterBase

Iterates over the configuration parameters and either logs a warning, or throws an exception for any parameter that does not have a matching setter in this filter.

Specified by:

init in interface Filter

Overrides:

init in class CsrfPreventionFilterBase

Parameters:

filterConfig - The configuration information associated with the filter instance being initialised

Throws:

ServletException - if FilterBase.isConfigProblemFatal() returns true and a configured parameter does not have a matching setter

doFilter

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

Description copied from interface: javax.servlet.Filter

The doFilter method of the Filter is called by the container each time a request/response pair is passed through the chain due to a client request for a resource at the end of the chain. The FilterChain passed in to this method allows the Filter to pass on the request and response to the next entity in the chain.

A typical implementation of this method would follow the following pattern:-
1. Examine the request
2. Optionally wrap the request object with a custom implementation to filter content or headers for input filtering
3. Optionally wrap the response object with a custom implementation to filter content or headers for output filtering
4. a) Either invoke the next entity in the chain using the FilterChain object (chain.doFilter()),
4. b) or not pass on the request/response pair to the next entity in the filter chain to block the request processing
5. Directly set headers on the response after invocation of the next entity in the filter chain.

Parameters:

request - The request to process

response - The response associated with the request

chain - Provides access to the next filter in the chain for this filter to pass the request and response to for further processing

Throws:

IOException - if an I/O error occurs during this filter's processing of the request

ServletException - if the processing fails for any other reason

setPathsAcceptingParams

public void setPathsAcceptingParams(String pathsList)

A comma separated list of URLs that can accept nonces via request parameter 'X-CSRF-Token'. For use cases when a nonce information cannot be provided via header, one can provide it via request parameters. If there is a X-CSRF-Token header, it will be taken with preference over any parameter with the same name in the request. Request parameters cannot be used to fetch new nonce, only header.

Parameters:

pathsList - Comma separated list of URLs to be configured as paths accepting request parameters with nonce information.

getPathsAcceptingParams

public Set<String> getPathsAcceptingParams()