Extract Currently Logged in User information from JWT token using Spring Security

Question

I have implemented JWT and LDAP Authentication using Spring Security Oauth2. It seems to be working fine and I can login with my LDAP credentials.

Now, there is one requirement that I need to use the currently logged in user info to save details in database - specifically like when that user add/update a new record. I tried to get that using Spring security way using

SecurityContextHolder.getContext().getAuthentication().getDetails() 

but it doesn't return all that information which I have in JWT. It just returns Remote IP,the JWT token value and authenticated true. It doesn't even return name().

I am new to JWT, so not sure if I need to extract it by reading that token and even how we can achieve it.

Any pointers will be appreciated.

Thanks.

Answer 1

The first thing you need to do is store the user information inside the JWT when it is created, then you have to extract it when it is used. I had a similar situation and I solved it by extending both the TokenEnhancer and JwtAccessTokenConverter.

I use the TokenEnhancer to embed my extended principal of type CustomUserDetailsinside the JWT additional information.

public class CustomAccessTokenEnhancer implements TokenEnhancer {

    @Override
    public OAuth2AccessToken enhance(OAuth2AccessToken accessToken, OAuth2Authentication authentication) {
        Authentication userAuthentication = authentication.getUserAuthentication();
        if (userAuthentication != null) {
            Object principal = authentication.getUserAuthentication().getPrincipal();
            if (principal instanceof CustomUserDetails) {
                Map<String, Object> additionalInfo = new HashMap<>();
                additionalInfo.put("userDetails", principal);
                ((DefaultOAuth2AccessToken) accessToken).setAdditionalInformation(additionalInfo);
            }
        }
        return accessToken;
    }
}

And then manually extract the extended principal when building the Authentication object when processing an authenticated request.

public class CustomJwtAccessTokenConverter extends JwtAccessTokenConverter {

    @Override
    public OAuth2Authentication extractAuthentication(Map<String, ?> map) {
        OAuth2Authentication authentication = super.extractAuthentication(map);
        Authentication userAuthentication = authentication.getUserAuthentication();

        if (userAuthentication != null) {
            LinkedHashMap userDetails = (LinkedHashMap) map.get("userDetails");
            if (userDetails != null) {

                // build your principal here
                String localUserTableField = (String) userDetails.get("localUserTableField");
                CustomUserDetails extendedPrincipal = new CustomUserDetails(localUserTableField);

                Collection<? extends GrantedAuthority> authorities = userAuthentication.getAuthorities();

                userAuthentication = new UsernamePasswordAuthenticationToken(extendedPrincipal,
                        userAuthentication.getCredentials(), authorities);
            }
        }
        return new OAuth2Authentication(authentication.getOAuth2Request(), userAuthentication);
    }
}

and the AuthorizationServer configuration to tie it all together.

@Configuration
@EnableAuthorizationServer
public class AuthorizationServerConfig extends AuthorizationServerConfigurerAdapter {

    @Autowired
    private AuthenticationManager authenticationManager;

    @Autowired
    private UserDetailsService userDetailsService;

    @Autowired
    private DataSource dataSource;

    @Bean
    public JwtAccessTokenConverter accessTokenConverter() {
        CustomJwtAccessTokenConverter accessTokenConverter = new CustomJwtAccessTokenConverter();
        accessTokenConverter.setSigningKey("a1b2c3d4e5f6g");
        return accessTokenConverter;
    }

    @Bean
    public TokenStore tokenStore() {
        return new JwtTokenStore(accessTokenConverter());
    }

    @Bean
    @Primary
    public DefaultTokenServices tokenServices() {
        DefaultTokenServices defaultTokenServices = new DefaultTokenServices();
        defaultTokenServices.setTokenStore(tokenStore());
        defaultTokenServices.setSupportRefreshToken(true);
        return defaultTokenServices;
    }

    @Bean
    public TokenEnhancer tokenEnhancer() {
        return new CustomAccessTokenEnhancer();
    }

    @Bean
    public PasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }

    @Override
    public void configure(ClientDetailsServiceConfigurer clients) throws Exception {
        clients.jdbc(dataSource).passwordEncoder(passwordEncoder());
    }

    @Override
    public void configure(AuthorizationServerEndpointsConfigurer endpoints) throws Exception {
        TokenEnhancerChain tokenEnhancerChain = new TokenEnhancerChain();
        tokenEnhancerChain.setTokenEnhancers(Arrays.asList(tokenEnhancer(), accessTokenConverter()));
        endpoints
                .tokenStore(tokenStore())
                .tokenEnhancer(tokenEnhancerChain)
                .authenticationManager(authenticationManager)
                .userDetailsService(userDetailsService);
    }

    @Override
    public void configure(AuthorizationServerSecurityConfigurer security) throws Exception {
        security.passwordEncoder(passwordEncoder());
        security.checkTokenAccess("isAuthenticated()");
    }
}

I am then able to access my extended principal in my resource controller like this

@RestController
public class SomeResourceController {

    @RequestMapping("/some-resource")
    public ResponseEntity<?> someResource(Authentication authentication) {
        CustomUserDetails userDetails = (CustomUserDetails) authentication.getPrincipal();
        return ResponseEntity.ok("woo hoo!");
    }

}

Hope this helps!