Allow logout+jwt JWT type

Closes gh-15003

config/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/client/OidcBackChannelLogoutAuthenticationProvider.java

@@ -16,6 +16,11 @@
 
 package org.springframework.security.config.annotation.web.configurers.oauth2.client;
 
+import com.nimbusds.jose.JOSEObjectType;
+import com.nimbusds.jose.proc.DefaultJOSEObjectTypeVerifier;
+import com.nimbusds.jose.proc.JOSEObjectTypeVerifier;
+import com.nimbusds.jose.proc.SecurityContext;
+
 import org.springframework.security.authentication.AuthenticationProvider;
 import org.springframework.security.authentication.AuthenticationServiceException;
 import org.springframework.security.core.Authentication;
@@ -30,7 +35,9 @@ import org.springframework.security.oauth2.jwt.BadJwtException;
 import org.springframework.security.oauth2.jwt.Jwt;
 import org.springframework.security.oauth2.jwt.JwtDecoder;
 import org.springframework.security.oauth2.jwt.JwtDecoderFactory;
+import org.springframework.security.oauth2.jwt.NimbusJwtDecoder;
 import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 
 /**
  * An {@link AuthenticationProvider} that authenticates an OIDC Logout Token; namely
@@ -56,9 +63,26 @@ final class OidcBackChannelLogoutAuthenticationProvider implements Authenticatio
 	 * Construct an {@link OidcBackChannelLogoutAuthenticationProvider}
 	 */
 	OidcBackChannelLogoutAuthenticationProvider() {
-		OidcIdTokenDecoderFactory logoutTokenDecoderFactory = new OidcIdTokenDecoderFactory();
-		logoutTokenDecoderFactory.setJwtValidatorFactory(new DefaultOidcLogoutTokenValidatorFactory());
-		this.logoutTokenDecoderFactory = logoutTokenDecoderFactory;
+		DefaultOidcLogoutTokenValidatorFactory jwtValidator = new DefaultOidcLogoutTokenValidatorFactory();
+		this.logoutTokenDecoderFactory = (clientRegistration) -> {
+			String jwkSetUri = clientRegistration.getProviderDetails().getJwkSetUri();
+			if (!StringUtils.hasText(jwkSetUri)) {
+				OAuth2Error oauth2Error = new OAuth2Error("missing_signature_verifier",
+						"Failed to find a Signature Verifier for Client Registration: '"
+								+ clientRegistration.getRegistrationId()
+								+ "'. Check to ensure you have configured the JwkSet URI.",
+						null);
+				throw new OAuth2AuthenticationException(oauth2Error, oauth2Error.toString());
+			}
+			JOSEObjectTypeVerifier<SecurityContext> typeVerifier = new DefaultJOSEObjectTypeVerifier<>(null,
+					JOSEObjectType.JWT, new JOSEObjectType("logout+jwt"));
+			NimbusJwtDecoder decoder = NimbusJwtDecoder.withJwkSetUri(jwkSetUri)
+				.jwtProcessorCustomizer((processor) -> processor.setJWSTypeVerifier(typeVerifier))
+				.build();
+			decoder.setJwtValidator(jwtValidator.apply(clientRegistration));
+			decoder.setClaimSetConverter(OidcIdTokenDecoderFactory.createDefaultClaimTypeConverter());
+			return decoder;
+		};
 	}
 
 	/**

config/src/test/java/org/springframework/security/config/annotation/web/configurers/oauth2/client/OidcLogoutConfigurerTests.java

@@ -73,6 +73,8 @@ import org.springframework.security.oauth2.client.registration.TestClientRegistr
 import org.springframework.security.oauth2.core.oidc.OidcIdToken;
 import org.springframework.security.oauth2.core.oidc.TestOidcIdTokens;
 import org.springframework.security.oauth2.core.oidc.user.OidcUser;
+import org.springframework.security.oauth2.jose.jws.SignatureAlgorithm;
+import org.springframework.security.oauth2.jwt.JwsHeader;
 import org.springframework.security.oauth2.jwt.JwtClaimsSet;
 import org.springframework.security.oauth2.jwt.JwtEncoder;
 import org.springframework.security.oauth2.jwt.JwtEncoderParameters;
@@ -513,8 +515,9 @@ public class OidcLogoutConfigurerTests {
 		String logoutToken(@AuthenticationPrincipal OidcUser user) {
 			OidcLogoutToken token = TestOidcLogoutTokens.withUser(user)
 					.audience(List.of(this.registration.getClientId())).build();
-			JwtEncoderParameters parameters = JwtEncoderParameters
-					.from(JwtClaimsSet.builder().claims((claims) -> claims.putAll(token.getClaims())).build());
+			JwsHeader header = JwsHeader.with(SignatureAlgorithm.RS256).type("logout+jwt").build();
+			JwtClaimsSet claims = JwtClaimsSet.builder().claims((c) -> c.putAll(token.getClaims())).build();
+			JwtEncoderParameters parameters = JwtEncoderParameters.from(header, claims);
 			return this.encoder.encode(parameters).getTokenValue();
 		}
 
@@ -523,8 +526,9 @@ public class OidcLogoutConfigurerTests {
 			OidcLogoutToken token = TestOidcLogoutTokens.withUser(user)
 					.audience(List.of(this.registration.getClientId()))
 					.claims((claims) -> claims.remove(LogoutTokenClaimNames.SID)).build();
-			JwtEncoderParameters parameters = JwtEncoderParameters
-					.from(JwtClaimsSet.builder().claims((claims) -> claims.putAll(token.getClaims())).build());
+			JwsHeader header = JwsHeader.with(SignatureAlgorithm.RS256).type("JWT").build();
+			JwtClaimsSet claims = JwtClaimsSet.builder().claims((c) -> c.putAll(token.getClaims())).build();
+			JwtEncoderParameters parameters = JwtEncoderParameters.from(header, claims);
 			return this.encoder.encode(parameters).getTokenValue();
 		}
 	}