Spring security authentication based on request parameter

Question

The application I'm working on already has Spring Security to handle form based authentication. Now the requirement is to login a user programmatically via an external service if a token is found in one of the request parameters.

In other words, if a particular request parameter, say "token", exists, it needs to call an external service with that token to verify if it's a valid token. If it is then the user will be logged in.

I can't figure out how and where to "trigger" or "hook on to" Spring Security to check this parameter and make the verification then authenticate the user when appropriate since there is no login form. I thought there should be something in Spring Security that can be extended or customized to do this?

I looked through Spring Security documentation and wonder if AbstractPreAuthenticatedProcessingFilter is the right thing to start with?

Answer 1

I have a similar setup in my application. Here are the basic elements as far as I can tell:

You need to create an AuthenticationProvider like so:

public class TokenAuthenticationProvider implements AuthenticationProvider {

    @Autowired private SomeService userSvc;

    @Override
    public Authentication authenticate(Authentication auth) throws AuthenticationException {
        if (auth.isAuthenticated())
            return auth;

        String token = auth.getCredentials().toString();
        User user = userSvc.validateApiAuthenticationToken(token);
        if (user != null) {
            auth = new PreAuthenticatedAuthenticationToken(user, token);
            auth.setAuthenticated(true);
            logger.debug("Token authentication. Token: " + token + "; user: " + user.getDisplayName());
        } else
            throw new BadCredentialsException("Invalid token " + token);
        return auth;
    }
}

You also need to create a Filter to turn the custom parameter into an authentication token:

public class AuthenticationTokenFilter implements Filter {


    @Override
    public void init(FilterConfig fc) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain fc) throws IOException, ServletException {
        SecurityContext context = SecurityContextHolder.getContext();
        if (context.getAuthentication() != null && context.getAuthentication().isAuthenticated()) {
            // do nothing
        } else {
            Map<String,String[]> params = req.getParameterMap();
            if (!params.isEmpty() && params.containsKey("auth_token")) {
                String token = params.get("auth_token")[0];
                if (token != null) {
                    Authentication auth = new TokenAuthentication(token);
                    SecurityContextHolder.getContext().setAuthentication(auth);
                }
            }
        }

        fc.doFilter(req, res);
    }

    @Override
    public void destroy() {

    }

    class TokenAuthentication implements Authentication {
        private String token;
        private TokenAuthentication(String token) {
            this.token = token;
        }
        @Override
        public Collection<? extends GrantedAuthority> getAuthorities() {
            return new ArrayList<GrantedAuthority>(0);
        }
        @Override
        public Object getCredentials() {
            return token;
        }
        @Override
        public Object getDetails() {
            return null;
        }
        @Override
        public Object getPrincipal() {
            return null;
        }
        @Override
        public boolean isAuthenticated() {
            return false;
        }
        @Override
        public void setAuthenticated(boolean isAuthenticated) throws IllegalArgumentException {
        }
        @Override
        public String getName() {
            // your custom logic here
        }
    }

 }

You need to create beans for these:

<beans:bean id="authTokenFilter" class="com.example.security.AuthenticationTokenFilter" scope="singleton" />
<beans:bean id="tokenAuthProvider" class="com.example.security.TokenAuthenticationProvider" />

Finally, you need to wire these beans into your security config (adjust accordingly):

<sec:http >
   <!-- other configs here -->
   <sec:custom-filter ref="authTokenFilter" after="BASIC_AUTH_FILTER" /> <!-- or other appropriate filter -->
</sec:http>

<sec:authentication-manager>
    <!-- other configs here -->
    <sec:authentication-provider ref="tokenAuthProvider" />
</sec:authentication-manager>

There might be another way, but this definitely works (using Spring Security 3.1 at the moment).