Revert OAuth2LoginAuthenticationFilter should ignore authenticated requests

Issue #5915
Commit 93ca45540556c4e8ade7f8948883f94fb0851ebb

Fixes gh-6890

config/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/client/OAuth2LoginConfigurer.java

@@ -26,7 +26,6 @@ import org.springframework.security.config.annotation.web.configurers.AbstractHt
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.AuthenticationException;
 import org.springframework.security.core.authority.mapping.GrantedAuthoritiesMapper;
-import org.springframework.security.core.context.SecurityContextHolder;
 import org.springframework.security.oauth2.client.OAuth2AuthorizedClientService;
 import org.springframework.security.oauth2.client.authentication.OAuth2LoginAuthenticationProvider;
 import org.springframework.security.oauth2.client.authentication.OAuth2LoginAuthenticationToken;
@@ -430,9 +429,6 @@ public final class OAuth2LoginConfigurer<B extends HttpSecurityBuilder<B>> exten
 				this.loginProcessingUrl);
 		this.setAuthenticationFilter(authenticationFilter);
 		super.loginProcessingUrl(this.loginProcessingUrl);
-		RequestMatcher authenticationNullMatcher = request -> SecurityContextHolder.getContext().getAuthentication() == null;
-		authenticationFilter.setRequiresAuthenticationRequestMatcher(new AndRequestMatcher(createLoginProcessingUrlMatcher(this.loginProcessingUrl),
-				authenticationNullMatcher));
 
 		if (this.loginPage != null) {
 			// Set custom login page

config/src/test/java/org/springframework/security/config/annotation/web/configurers/oauth2/client/OAuth2LoginConfigurerTests.java

@@ -28,7 +28,6 @@ import org.springframework.http.MediaType;
 import org.springframework.mock.web.MockFilterChain;
 import org.springframework.mock.web.MockHttpServletRequest;
 import org.springframework.mock.web.MockHttpServletResponse;
-import org.springframework.security.authentication.TestingAuthenticationToken;
 import org.springframework.security.authentication.event.AuthenticationSuccessEvent;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
@@ -38,7 +37,6 @@ import org.springframework.security.core.Authentication;
 import org.springframework.security.core.GrantedAuthority;
 import org.springframework.security.core.authority.SimpleGrantedAuthority;
 import org.springframework.security.core.authority.mapping.GrantedAuthoritiesMapper;
-import org.springframework.security.core.context.SecurityContextImpl;
 import org.springframework.security.oauth2.client.endpoint.OAuth2AccessTokenResponseClient;
 import org.springframework.security.oauth2.client.endpoint.OAuth2AuthorizationCodeGrantRequest;
 import org.springframework.security.oauth2.client.oidc.userinfo.OidcUserRequest;
@@ -182,31 +180,6 @@ public class OAuth2LoginConfigurerTests {
 		assertThat(OAuth2LoginConfig.EVENTS.get(0)).isInstanceOf(AuthenticationSuccessEvent.class);
 	}
 
-	@Test
-	public void oauth2LoginWhenAuthenticatedThenIgnored() throws Exception {
-		// setup application context
-		loadConfig(OAuth2LoginConfig.class);
-
-		// authenticate
-		TestingAuthenticationToken expectedAuthentication = new TestingAuthenticationToken("a",
-				"b", "ROLE_TEST");
-
-		this.request.getSession().setAttribute(HttpSessionSecurityContextRepository.SPRING_SECURITY_CONTEXT_KEY, new SecurityContextImpl(expectedAuthentication));
-
-		// setup authentication parameters
-		this.request.setParameter("code", "code123");
-		this.request.setParameter("state", "state");
-
-		// perform test
-		this.springSecurityFilterChain.doFilter(this.request, this.response, this.filterChain);
-
-		// assertions
-		Authentication authentication = this.securityContextRepository
-				.loadContext(new HttpRequestResponseHolder(this.request, this.response))
-				.getAuthentication();
-		assertThat(authentication).isEqualTo(expectedAuthentication);
-	}
-
 	@Test
 	public void oauth2LoginCustomWithConfigurer() throws Exception {
 		// setup application context