Add Conditions to Generating AuthnRequest

Closes gh-11657

config/src/main/java/org/springframework/security/config/annotation/web/configurers/saml2/Saml2LoginConfigurer.java

@@ -47,10 +47,16 @@
 import org.springframework.security.saml2.provider.service.web.Saml2AuthenticationRequestRepository;
 import org.springframework.security.saml2.provider.service.web.Saml2AuthenticationTokenConverter;
 import org.springframework.security.saml2.provider.service.web.authentication.Saml2AuthenticationRequestResolver;
+import org.springframework.security.web.AuthenticationEntryPoint;
 import org.springframework.security.web.authentication.AuthenticationConverter;
+import org.springframework.security.web.authentication.DelegatingAuthenticationEntryPoint;
 import org.springframework.security.web.authentication.LoginUrlAuthenticationEntryPoint;
 import org.springframework.security.web.authentication.ui.DefaultLoginPageGeneratingFilter;
+import org.springframework.security.web.util.matcher.AndRequestMatcher;
 import org.springframework.security.web.util.matcher.AntPathRequestMatcher;
+import org.springframework.security.web.util.matcher.NegatedRequestMatcher;
+import org.springframework.security.web.util.matcher.OrRequestMatcher;
+import org.springframework.security.web.util.matcher.RequestHeaderRequestMatcher;
 import org.springframework.security.web.util.matcher.RequestMatcher;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -252,8 +258,7 @@ public void init(B http) throws Exception {
 				this.updateAuthenticationDefaults();
 				this.updateAccessDefaults(http);
 				String loginUrl = providerUrlMap.entrySet().iterator().next().getKey();
-				final LoginUrlAuthenticationEntryPoint entryPoint = new LoginUrlAuthenticationEntryPoint(loginUrl);
-				registerAuthenticationEntryPoint(http, entryPoint);
+				registerAuthenticationEntryPoint(http, getLoginEntryPoint(http, loginUrl));
 			}
 			else {
 				super.init(http);
@@ -295,6 +300,22 @@ RelyingPartyRegistrationRepository relyingPartyRegistrationRepository(B http) {
 		return this.relyingPartyRegistrationRepository;
 	}
 
+	private AuthenticationEntryPoint getLoginEntryPoint(B http, String providerLoginPage) {
+		RequestMatcher loginPageMatcher = new AntPathRequestMatcher(this.getLoginPage());
+		RequestMatcher faviconMatcher = new AntPathRequestMatcher("/favicon.ico");
+		RequestMatcher defaultEntryPointMatcher = this.getAuthenticationEntryPointMatcher(http);
+		RequestMatcher defaultLoginPageMatcher = new AndRequestMatcher(
+				new OrRequestMatcher(loginPageMatcher, faviconMatcher), defaultEntryPointMatcher);
+		RequestMatcher notXRequestedWith = new NegatedRequestMatcher(
+				new RequestHeaderRequestMatcher("X-Requested-With", "XMLHttpRequest"));
+		LinkedHashMap<RequestMatcher, AuthenticationEntryPoint> entryPoints = new LinkedHashMap<>();
+		entryPoints.put(new AndRequestMatcher(notXRequestedWith, new NegatedRequestMatcher(defaultLoginPageMatcher)),
+				new LoginUrlAuthenticationEntryPoint(providerLoginPage));
+		DelegatingAuthenticationEntryPoint loginEntryPoint = new DelegatingAuthenticationEntryPoint(entryPoints);
+		loginEntryPoint.setDefaultEntryPoint(this.getAuthenticationEntryPoint());
+		return loginEntryPoint;
+	}
+
 	private void setAuthenticationRequestRepository(B http,
 			Saml2WebSsoAuthenticationFilter saml2WebSsoAuthenticationFilter) {
 		saml2WebSsoAuthenticationFilter.setAuthenticationRequestRepository(getAuthenticationRequestRepository(http));

config/src/test/java/org/springframework/security/config/annotation/web/configurers/saml2/Saml2LoginConfigurerTests.java

@@ -43,6 +43,7 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Import;
 import org.springframework.core.convert.converter.Converter;
+import org.springframework.http.MediaType;
 import org.springframework.mock.web.MockFilterChain;
 import org.springframework.mock.web.MockHttpServletRequest;
 import org.springframework.mock.web.MockHttpServletResponse;
@@ -412,6 +413,16 @@ public void authenticateWhenCustomLoginProcessingUrlAndSaml2AuthenticationTokenC
 		verify(authenticationConverter).convert(any(HttpServletRequest.class));
 	}
 
+	// gh-11657
+	@Test
+	public void getFaviconWhenDefaultConfigurationThenDoesNotSaveAuthnRequest() throws Exception {
+		this.spring.register(Saml2LoginConfig.class).autowire();
+		this.mvc.perform(get("/favicon.ico").accept(MediaType.TEXT_HTML)).andExpect(status().isFound())
+				.andExpect(redirectedUrl("http://localhost/login"));
+		this.mvc.perform(get("/").accept(MediaType.TEXT_HTML)).andExpect(status().isFound())
+				.andExpect(redirectedUrl("http://localhost/saml2/authenticate/registration-id"));
+	}
+
 	private void validateSaml2WebSsoAuthenticationFilterConfiguration() {
 		// get the OpenSamlAuthenticationProvider
 		Saml2WebSsoAuthenticationFilter filter = getSaml2SsoFilter(this.springSecurityFilterChain);