= Reactive Migrations

If you have already performed the xref:migration/index.adoc[initial migration steps] for your Reactive application, you're now ready to perform steps specific to Reactive applications.

== Exploit Protection Migrations

The following steps relate to changes around how to configure CSRF.

=== Configure `tokenFromMultipartDataEnabled`

In Spring Security 5.8, the method `tokenFromMultipartDataEnabled` was deprecated in favor of `ServerCsrfTokenRequestAttributeHandler#setTokenFromMultipartDataEnabled`.

To address the deprecation, the following code:

.Configure `tokenFromMultipartDataEnabled` with DSL
====
.Java
[source,java,role="primary"]
----
@Bean
SecurityWebFilterChain securityWebFilterChain(ServerHttpSecurity http) {
	http
		// ...
		.csrf((csrf) -> csrf
			.tokenFromMultipartDataEnabled(true)
		);
	return http.build();
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
open fun securityWebFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
	return http {
		// ...
		csrf {
			tokenFromMultipartDataEnabled = true
		}
	}
}
----
====

can be replaced with:

.Configure `tokenFromMultipartDataEnabled` with `ServerCsrfTokenRequestAttributeHandler`
====
.Java
[source,java,role="primary"]
----
@Bean
SecurityWebFilterChain securityWebFilterChain(ServerHttpSecurity http) {
	ServerCsrfTokenRequestAttributeHandler requestHandler = new ServerCsrfTokenRequestAttributeHandler();
	requestHandler.setTokenFromMultipartDataEnabled(true);
	http
		// ...
		.csrf((csrf) -> csrf
			.csrfTokenRequestHandler(requestHandler)
		);
	return http.build();
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
open fun securityWebFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
	val requestHandler = ServerCsrfTokenRequestAttributeHandler()
	requestHandler.tokenFromMultipartDataEnabled = true
	return http {
		// ...
		csrf {
			csrfTokenRequestHandler = requestHandler
		}
	}
}
----
====

=== Protect against CSRF BREACH

You can opt into Spring Security 6's default support for BREACH protection of the `CsrfToken` using the following configuration:

.`CsrfToken` BREACH Protection
====
.Java
[source,java,role="primary"]
----
@Bean
SecurityWebFilterChain securityWebFilterChain(ServerHttpSecurity http) {
	XorServerCsrfTokenRequestAttributeHandler requestHandler = new XorServerCsrfTokenRequestAttributeHandler();
	// ...
	http
		// ...
		.csrf((csrf) -> csrf
			.csrfTokenRequestHandler(requestHandler)
		);
	return http.build();
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
open fun securityWebFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
	val requestHandler = XorServerCsrfTokenRequestAttributeHandler()
	// ...
	return http {
		// ...
		csrf {
			csrfTokenRequestHandler = requestHandler
		}
	}
}
----
====

[[reactive-csrf-breach-opt-out]]
=== Opt-out Steps

If configuring CSRF BREACH protection gives you trouble, take a look at these scenarios for optimal opt out behavior:

==== I am using AngularJS or another Javascript framework

If you are using AngularJS and the https://angular.io/api/common/http/HttpClientXsrfModule[HttpClientXsrfModule] (or a similar module in another framework) along with `CookieServerCsrfTokenRepository.withHttpOnlyFalse()`, you may find that automatic support no longer works.

In this case, you can configure Spring Security to validate the raw `CsrfToken` from the cookie while keeping CSRF BREACH protection of the response using a custom `ServerCsrfTokenRequestHandler` with delegation, like so:

.Configure `CsrfToken` BREACH Protection to validate raw tokens
====
.Java
[source,java,role="primary"]
----
@Bean
SecurityWebFilterChain securityWebFilterChain(ServerHttpSecurity http) {
	CookieServerCsrfTokenRepository tokenRepository = CookieServerCsrfTokenRepository.withHttpOnlyFalse();
	XorServerCsrfTokenRequestAttributeHandler delegate = new XorServerCsrfTokenRequestAttributeHandler();
	// Use only the handle() method of XorServerCsrfTokenRequestAttributeHandler and the
	// default implementation of resolveCsrfTokenValue() from ServerCsrfTokenRequestHandler
	ServerCsrfTokenRequestHandler requestHandler = delegate::handle;
	http
		// ...
		.csrf((csrf) -> csrf
			.csrfTokenRepository(tokenRepository)
			.csrfTokenRequestHandler(requestHandler)
		);

	return http.build();
}

@Bean
WebFilter csrfCookieWebFilter() {
	return (exchange, chain) -> {
		Mono<CsrfToken> csrfToken = exchange.getAttributeOrDefault(CsrfToken.class.getName(), Mono.empty());
		return csrfToken.doOnSuccess(token -> {
			/* Ensures the token is subscribed to. */
		}).then(chain.filter(exchange));
	};
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
open fun securityWebFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
	val tokenRepository = CookieServerCsrfTokenRepository.withHttpOnlyFalse()
	val delegate = XorServerCsrfTokenRequestAttributeHandler()
	// Use only the handle() method of XorServerCsrfTokenRequestAttributeHandler and the
	// default implementation of resolveCsrfTokenValue() from ServerCsrfTokenRequestHandler
	val requestHandler = ServerCsrfTokenRequestHandler(delegate::handle)
	return http.invoke {
		// ...
		csrf {
			csrfTokenRepository = tokenRepository
			csrfTokenRequestHandler = requestHandler
		}
	}
}

@Bean
fun csrfCookieWebFilter(): WebFilter {
	return WebFilter { exchange, chain ->
		val csrfToken = exchange.getAttribute<Mono<CsrfToken>>(CsrfToken::class.java.name) ?: Mono.empty()
		csrfToken.doOnSuccess {
            /* Ensures the token is subscribed to. */
		}.then(chain.filter(exchange))
	}
}
----
====

==== I need to opt out of CSRF BREACH protection for another reason

If CSRF BREACH protection does not work for you for another reason, you can opt out using the following configuration:

.Opt out of `CsrfToken` BREACH protection
====
.Java
[source,java,role="primary"]
----
@Bean
SecurityWebFilterChain securityWebFilterChain(ServerHttpSecurity http) {
	ServerCsrfTokenRequestAttributeHandler requestHandler = new ServerCsrfTokenRequestAttributeHandler();
	http
		// ...
		.csrf((csrf) -> csrf
			.csrfTokenRequestHandler(requestHandler)
		);
	return http.build();
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
open fun securityWebFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
	val requestHandler = ServerCsrfTokenRequestAttributeHandler()
	return http {
		// ...
		csrf {
			csrfTokenRequestHandler = requestHandler
		}
	}
}
----
====

== Use `AuthorizationManager` for Method Security

xref:reactive/authorization/method.adoc[Method Security] has been xref:reactive/authorization/method.adoc#jc-enable-reactive-method-security-authorization-manager[improved] through {security-api-url}org/springframework/security/authorization/AuthorizationManager.html[the `AuthorizationManager` API] and direct use of Spring AOP.

Should you run into trouble with making these changes, you can follow the
<<reactive-authorizationmanager-methods-opt-out,opt out steps>> at the end of this section.

In Spring Security 5.8, `useAuthorizationManager` was added to {security-api-url}org/springframework/security/config/annotation/method/configuration/EnableReactiveMethodSecurity.html[`@EnableReactiveMethodSecurity`] to allow applications to opt in to ``AuthorizationManager``'s features.

[[reactive-change-to-useauthorizationmanager]]
=== Change `useAuthorizationManager` to `true`

To opt in, change `useAuthorizationManager` to `true` like so:

====
.Java
[source,java,role="primary"]
----
@EnableReactiveMethodSecurity
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableReactiveMethodSecurity
----
====

changes to:

====
.Java
[source,java,role="primary"]
----
@EnableReactiveMethodSecurity(useAuthorizationManager = true)
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableReactiveMethodSecurity(useAuthorizationManager = true)
----
====

[[reactive-check-for-annotationconfigurationexceptions]]
=== Check for ``AnnotationConfigurationException``s

`useAuthorizationManager` activates stricter enforcement of Spring Security's non-repeatable or otherwise incompatible annotations.
If after turning on `useAuthorizationManager` you see ``AnnotationConfigurationException``s in your logs, follow the instructions in the exception message to clean up your application's method security annotation usage.

[[reactive-authorizationmanager-methods-opt-out]]
=== Opt-out Steps

If you ran into trouble with `AuthorizationManager` for reactive method security, you can opt out by changing:

====
.Java
[source,java,role="primary"]
----
@EnableReactiveMethodSecurity
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableReactiveMethodSecurity
----
====

to:

====
.Java
[source,java,role="primary"]
----
@EnableReactiveMethodSecurity(useAuthorizationManager = false)
----

.Kotlin
[source,kotlin,role="secondary"]
----
@EnableReactiveMethodSecurity(useAuthorizationManager = false)
----
====

== Propagate ``AuthenticationServiceException``s

{security-api-url}org/springframework/security/web/server/Webauthentication/AuthenticationWebFilter.html[`AuthenticationFilter`] propagates {security-api-url}org/springframework/security/authentication/AuthenticationServiceException.html[``AuthenticationServiceException``]s to the {security-api-url}org/springframework/security/web/server/ServerAuthenticationEntryPoint.html[`ServerAuthenticationEntryPoint`].
Because ``AuthenticationServiceException``s  represent a server-side error instead of a client-side error, in 6.0, this changes to propagate them to the container.

=== Configure `ServerAuthenticationFailureHandler` to rethrow ``AuthenticationServiceException``s

To prepare for the 6.0 default, `httpBasic` and `oauth2ResourceServer` should be configured to rethrow ``AuthenticationServiceException``s.

For each, construct the appropriate authentication entry point for `httpBasic` and for `oauth2ResourceServer`:

====
.Java
[source,java,role="primary"]
----
ServerAuthenticationEntryPoint bearerEntryPoint = new BearerTokenServerAuthenticationEntryPoint();
ServerAuthenticationEntryPoint basicEntryPoint = new HttpStatusServerEntryPoint(HttpStatus.UNAUTHORIZED);
----

.Kotlin
[source,kotlin,role="secondary"]
----
val bearerEntryPoint: ServerAuthenticationEntryPoint = BearerTokenServerAuthenticationEntryPoint()
val basicEntryPoint: ServerAuthenticationEntryPoint = HttpStatusServerEntryPoint(HttpStatus.UNAUTHORIZED)
----
====

[NOTE]
====
If you use a custom `AuthenticationEntryPoint` for either or both mechanisms, use that one instead for the remaining steps.
====

Then, construct and configure a `ServerAuthenticationEntryPointFailureHandler` for each one:

====
.Java
[source,java,role="primary"]
----
AuthenticationFailureHandler bearerFailureHandler = new ServerAuthenticationEntryPointFailureHandler(bearerEntryPoint);
bearerFailureHandler.setRethrowAuthenticationServiceException(true);
AuthenticationFailureHandler basicFailureHandler = new ServerAuthenticationEntryPointFailureHandler(basicEntryPoint);
basicFailureHandler.setRethrowAuthenticationServiceException(true)
----

.Kotlin
[source,kotlin,role="secondary"]
----
val bearerFailureHandler: AuthenticationFailureHandler = ServerAuthenticationEntryPointFailureHandler(bearerEntryPoint)
bearerFailureHandler.setRethrowAuthenticationServiceException(true)
val basicFailureHandler: AuthenticationFailureHandler = ServerAuthenticationEntryPointFailureHandler(basicEntryPoint)
basicFailureHandler.setRethrowAuthenticationServiceException(true)
----
====

Finally, wire each authentication failure handler into the DSL, like so:

====
.Java
[source,java,role="primary"]
----
http
    .httpBasic((basic) -> basic.authenticationFailureHandler(basicFailureHandler))
    .oauth2ResourceServer((oauth2) -> oauth2.authenticationFailureHandler(bearerFailureHandler))
----

.Kotlin
[source,kotlin,role="secondary"]
----
http {
    httpBasic {
        authenticationFailureHandler = basicFailureHandler
    }
    oauth2ResourceServer {
        authenticationFailureHandler = bearerFailureHandler
    }
}
----
====

[[reactive-authenticationfailurehandler-opt-out]]
=== Opt-out Steps

To opt-out of the 6.0 defaults and instead continue to pass `AuthenticationServiceException` on to ``ServerAuthenticationEntryPoint``s, you can follow the same steps as above, except set `rethrowAuthenticationServiceException` to false.

== Address OAuth2 Client Deprecations

=== `ServerOAuth2AuthorizedClientExchangeFilterFunction`

The method `setAccessTokenExpiresSkew(...)` can be replaced with one of:

* `ClientCredentialsReactiveOAuth2AuthorizedClientProvider#setClockSkew(...)`
* `RefreshTokenReactiveOAuth2AuthorizedClientProvider#setClockSkew(...)`
* `JwtBearerReactiveOAuth2AuthorizedClientProvider#setClockSkew(...)`

The method `setClientCredentialsTokenResponseClient(...)` can be replaced with the constructor `ServerOAuth2AuthorizedClientExchangeFilterFunction(ReactiveOAuth2AuthorizedClientManager)`.

[NOTE]
====
See xref:reactive/oauth2/client/authorization-grants.adoc#oauth2Client-client-creds-grant[Client Credentials] for more information.
====

=== `WebSessionOAuth2ServerAuthorizationRequestRepository`

The method `setAllowMultipleAuthorizationRequests(...)` has no direct replacement.

=== `UnAuthenticatedServerOAuth2AuthorizedClientRepository`

The class `UnAuthenticatedServerOAuth2AuthorizedClientRepository` has no direct replacement. Usage of the class can be replaced with `AuthorizedClientServiceReactiveOAuth2AuthorizedClientManager`.
