Spring Security OAuth2: InsufficientAuthenticationException - spring-security

Question

First of all, I disabled basic auth:
security.basic.enabled=false
Then I access the authorization page:
http://localhost:8080/oauth/authorize?client_id=client&response_type=code&redirect_uri=http://www.baidu.com
I got following exception:
org.springframework.security.authentication.InsufficientAuthenticationException: User must be authenticated with Spring Security before authorization can be completed.
at org.springframework.security.oauth2.provider.endpoint.AuthorizationEndpoint.authorize(AuthorizationEndpoint.java:138) ~[spring-security-oauth2-2.0.10.RELEASE.jar:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_45]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_45]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_45]
at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_45]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:832) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:743) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:961) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:895) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at ...
I don't understand why I have to do authentication first before OAuth?

Answer 1

The flow for the authorization code grant goes like this:
Client redirects the user to auth server's authorization page. Hence the http://localhost:8080/oauth/authorize?client_id=client&response_type=code&redirect_uri=http://www.baidu.com
If the user were already logged in, the user would be immediately shown an authorization page where he can approve the authorization request. If the user is not yet logged in, he should be redirected to a login page first to authenticate himself to let Spring Security know who is giving the authorization.
What you probably need to do is secure the authorization endpoint by requiring a role granted like this in xml:
<security:http disable-url-rewriting="true"
use-expressions="true"
entry-point-ref="loginEntryPoint">
...
<security:intercept-url pattern="/oauth/authorize" access="hasRole('ROLE_USER')"/>
...
</security:http>
If the user is not yet logged in, this will trigger Spring Security to redirect the user to login as configured in your loginEntryPoint. Typically, you would redirect the user to a login page. After successfully authenticating, the user will return to the authorization endpoint.