Fix password change in enterprise auth manager

Authentication with ShiroAuthManager is throwing ExpiredCredentialsException
(if a password change is required) before an identifying principal is assigned.
In this case we have to assign a principal identity with the username to allow
the user to change her password through the changePassword procedure.
At this point we know the username is valid.

enterprise/security/src/main/java/org/neo4j/server/security/enterprise/auth/ShiroAuthManager.java

@@ -25,6 +25,8 @@
 import org.apache.shiro.cache.ehcache.EhCacheManager;
 import org.apache.shiro.mgt.DefaultSecurityManager;
 import org.apache.shiro.mgt.SecurityManager;
+import org.apache.shiro.subject.PrincipalCollection;
+import org.apache.shiro.subject.SimplePrincipalCollection;
 import org.apache.shiro.subject.Subject;
 
 import java.io.IOException;
@@ -130,7 +132,8 @@ public AuthSubject login( String username, String password )
     {
         assertAuthEnabled();
 
-        Subject subject = new Subject.Builder( securityManager ).buildSubject();
+        // Start with an anonymous subject
+        Subject subject = buildSubject( null );
 
         UsernamePasswordToken token = new UsernamePasswordToken( username, password );
         AuthenticationResult result = AuthenticationResult.SUCCESS;
@@ -148,6 +151,10 @@ public AuthSubject login( String username, String password )
             catch ( ExpiredCredentialsException e )
             {
                 result = AuthenticationResult.PASSWORD_CHANGE_REQUIRED;
+
+                // We have to build an identity with the given username to allow the user to change password
+                // At this point we know that the username is valid
+                subject = buildSubject( username );
             }
             catch ( AuthenticationException e )
             {
@@ -195,4 +202,16 @@ public boolean deleteUser( String username ) throws IOException
         return realm.deleteUser( username );
     }
 
+    private Subject buildSubject( String username )
+    {
+        Subject.Builder subjectBuilder = new Subject.Builder( securityManager );
+
+        if ( username != null )
+        {
+            PrincipalCollection identity = new SimplePrincipalCollection( username, realm.getName() );
+            subjectBuilder = subjectBuilder.principals( identity );
+        }
+
+        return subjectBuilder.buildSubject();
+    }
 }

enterprise/security/src/main/java/org/neo4j/server/security/enterprise/auth/ShiroAuthSubject.java

@@ -74,7 +74,8 @@ public void setPassword( String password ) throws IOException, IllegalCredential
 
     public boolean doesUsernameMatch( String username )
     {
-        return subject.getPrincipal().equals( username );
+        Object principal = subject.getPrincipal();
+        return principal != null && username.equals( principal );
     }
 
     @Override

enterprise/security/src/test/java/org/neo4j/server/security/enterprise/auth/ShiroAuthManagerTest.java

@@ -214,6 +214,30 @@ public void shouldSetPassword() throws Throwable
         assertThat( users.findByName( "jake" ), equalTo( user ) );
     }
 
+    @Test
+    public void shouldSetPasswordThroughAuthSubject() throws Throwable
+    {
+        // Given
+        users.create( new User( "neo", Credential.forPassword( "abc123" ), true ) );
+        manager.start();
+        when( authStrategy.isAuthenticationPermitted( "neo" )).thenReturn( true );
+
+        // When
+        AuthSubject authSubject = manager.login( "neo", "abc123" );
+        assertThat( authSubject.getAuthenticationResult(), equalTo( AuthenticationResult.PASSWORD_CHANGE_REQUIRED ) );
+
+        authSubject.setPassword( "hello, world!" );
+
+        // Then
+        User user = manager.getUser( "neo" );
+        assertTrue( user.credentials().matchesPassword( "hello, world!" ) );
+        assertThat( users.findByName( "neo" ), equalTo( user ) );
+
+        authSubject.logout();
+        authSubject = manager.login( "neo", "hello, world!" );
+        assertThat( authSubject.getAuthenticationResult(), equalTo( AuthenticationResult.SUCCESS ) );
+    }
+
     @Test
     public void shouldReturnNullWhenSettingPasswordForUnknownUser() throws Throwable
     {