Reactive Resource Server Csrf Bypass

This makes requests identified as bearer token requests skip the csrf
filter.

Fixes: gh-5710

config/src/main/java/org/springframework/security/config/web/server/ServerHttpSecurity.java

@@ -43,6 +43,7 @@ import org.springframework.security.authorization.AuthenticatedReactiveAuthoriza
 import org.springframework.security.authorization.AuthorityReactiveAuthorizationManager;
 import org.springframework.security.authorization.AuthorizationDecision;
 import org.springframework.security.authorization.ReactiveAuthorizationManager;
+import org.springframework.security.core.Authentication;
 import org.springframework.security.core.AuthenticationException;
 import org.springframework.security.oauth2.client.InMemoryReactiveOAuth2AuthorizedClientService;
 import org.springframework.security.oauth2.client.ReactiveOAuth2AuthorizedClientService;
@@ -114,7 +115,9 @@ import org.springframework.security.web.server.savedrequest.ServerRequestCacheWe
 import org.springframework.security.web.server.savedrequest.WebSessionServerRequestCache;
 import org.springframework.security.web.server.ui.LoginPageGeneratingWebFilter;
 import org.springframework.security.web.server.ui.LogoutPageGeneratingWebFilter;
+import org.springframework.security.web.server.util.matcher.AndServerWebExchangeMatcher;
 import org.springframework.security.web.server.util.matcher.MediaTypeServerWebExchangeMatcher;
+import org.springframework.security.web.server.util.matcher.NegatedServerWebExchangeMatcher;
 import org.springframework.security.web.server.util.matcher.PathPatternParserServerWebExchangeMatcher;
 import org.springframework.security.web.server.util.matcher.ServerWebExchangeMatcher;
 import org.springframework.security.web.server.util.matcher.ServerWebExchangeMatcherEntry;
@@ -130,6 +133,8 @@ import org.springframework.web.server.WebFilter;
 import org.springframework.web.server.WebFilterChain;
 
 import static org.springframework.security.web.server.DelegatingServerAuthenticationEntryPoint.DelegateEntry;
+import static org.springframework.security.web.server.util.matcher.ServerWebExchangeMatcher.MatchResult.match;
+import static org.springframework.security.web.server.util.matcher.ServerWebExchangeMatcher.MatchResult.notMatch;
 
 /**
  * A {@link ServerHttpSecurity} is similar to Spring Security's {@code HttpSecurity} but for WebFlux.
@@ -703,6 +708,9 @@ public class ServerHttpSecurity {
 		public class JwtSpec {
 			private ReactiveJwtDecoder jwtDecoder;
 
+			private BearerTokenServerWebExchangeMatcher bearerTokenServerWebExchangeMatcher =
+					new BearerTokenServerWebExchangeMatcher();
+
 			/**
 			 * Configures the {@link ReactiveJwtDecoder} to use
 			 * @param jwtDecoder the decoder to use
@@ -740,13 +748,20 @@ public class ServerHttpSecurity {
 			}
 
 			protected void configure(ServerHttpSecurity http) {
+				ServerBearerTokenAuthenticationConverter bearerTokenConverter =
+						new ServerBearerTokenAuthenticationConverter();
+				this.bearerTokenServerWebExchangeMatcher.setBearerTokenConverter(bearerTokenConverter);
+
+				registerDefaultCsrfOverride(http);
+
 				BearerTokenServerAuthenticationEntryPoint entryPoint = new BearerTokenServerAuthenticationEntryPoint();
 				ReactiveJwtDecoder jwtDecoder = getJwtDecoder();
 				JwtReactiveAuthenticationManager authenticationManager = new JwtReactiveAuthenticationManager(
 						jwtDecoder);
 				AuthenticationWebFilter oauth2 = new AuthenticationWebFilter(authenticationManager);
-				oauth2.setServerAuthenticationConverter(new ServerBearerTokenAuthenticationConverter());
+				oauth2.setServerAuthenticationConverter(bearerTokenConverter);
 				oauth2.setAuthenticationFailureHandler(new ServerAuthenticationEntryPointFailureHandler(entryPoint));
+
 				http
 					.exceptionHandling()
 						.authenticationEntryPoint(entryPoint)
@@ -760,6 +775,38 @@ public class ServerHttpSecurity {
 				}
 				return this.jwtDecoder;
 			}
+
+			private void registerDefaultCsrfOverride(ServerHttpSecurity http) {
+				if ( http.csrf != null && !http.csrf.specifiedRequireCsrfProtectionMatcher ) {
+					http
+						.csrf()
+							.requireCsrfProtectionMatcher(
+									new AndServerWebExchangeMatcher(
+											CsrfWebFilter.DEFAULT_CSRF_MATCHER,
+											new NegatedServerWebExchangeMatcher(
+													this.bearerTokenServerWebExchangeMatcher)));
+				}
+			}
+
+			private class BearerTokenServerWebExchangeMatcher implements ServerWebExchangeMatcher {
+				ServerBearerTokenAuthenticationConverter bearerTokenConverter;
+
+				@Override
+				public Mono<MatchResult> matches(ServerWebExchange exchange) {
+					return this.bearerTokenConverter.convert(exchange)
+							.flatMap(this::nullAuthentication)
+							.onErrorResume(e -> notMatch());
+				}
+
+				public void setBearerTokenConverter(ServerBearerTokenAuthenticationConverter bearerTokenConverter) {
+					Assert.notNull(bearerTokenConverter, "bearerTokenConverter cannot be null");
+					this.bearerTokenConverter = bearerTokenConverter;
+				}
+
+				private Mono<MatchResult> nullAuthentication(Authentication authentication) {
+					return authentication == null ? notMatch() : match();
+				}
+			}
 		}
 
 		public ServerHttpSecurity and() {
@@ -1173,6 +1220,8 @@ public class ServerHttpSecurity {
 	public class CsrfSpec {
 		private CsrfWebFilter filter = new CsrfWebFilter();
 
+		private boolean specifiedRequireCsrfProtectionMatcher;
+
 		/**
 		 * Configures the {@link ServerAccessDeniedHandler} used when a CSRF token is invalid. Default is
 		 * to send an {@link org.springframework.http.HttpStatus#FORBIDDEN}.
@@ -1209,6 +1258,7 @@ public class ServerHttpSecurity {
 		public CsrfSpec requireCsrfProtectionMatcher(
 			ServerWebExchangeMatcher requireCsrfProtectionMatcher) {
 			this.filter.setRequireCsrfProtectionMatcher(requireCsrfProtectionMatcher);
+			this.specifiedRequireCsrfProtectionMatcher = true;
 			return this;
 		}
 

config/src/test/java/org/springframework/security/config/web/server/OAuth2ResourceServerSpecTests.java

@@ -48,6 +48,7 @@ import org.springframework.security.web.server.SecurityWebFilterChain;
 import org.springframework.test.context.junit4.SpringRunner;
 import org.springframework.test.web.reactive.server.WebTestClient;
 import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.context.support.GenericWebApplicationContext;
 import org.springframework.web.reactive.DispatcherHandler;
@@ -160,6 +161,25 @@ public class OAuth2ResourceServerSpecTests {
 				.expectStatus().isOk();
 	}
 
+	@Test
+	public void postWhenSignedThenReturnsOk() {
+		this.spring.register(PublicKeyConfig.class, RootController.class).autowire();
+
+		this.client.post()
+				.headers(headers -> headers.setBearerAuth(this.messageReadToken))
+				.exchange()
+				.expectStatus().isOk();
+	}
+
+	@Test
+	public void postWhenMissingTokenThenReturnsForbidden() {
+		this.spring.register(PublicKeyConfig.class, RootController.class).autowire();
+
+		this.client.post()
+				.exchange()
+				.expectStatus().isForbidden();
+	}
+
 	@Test
 	public void getJwtDecoderWhenBeanWiredAndDslWiredThenDslTakesPrecedence() {
 		GenericWebApplicationContext context = autowireWebServerGenericWebApplicationContext();
@@ -301,7 +321,12 @@ public class OAuth2ResourceServerSpecTests {
 	@RestController
 	static class RootController {
 		@GetMapping
-		Mono<String> root() {
+		Mono<String> get() {
+			return Mono.just("ok");
+		}
+
+		@PostMapping
+		Mono<String> post() {
 			return Mono.just("ok");
 		}
 	}