Allow for multiple Jwt to GrantedAuthorizies converters

[rolaca11]

It is quite hard to have multiple converters extract granted authorities from JWT tokens.

In the case of an authorization server created with the latest version of spring-security supporting one, the Jwt tokens generated by the auth server contains a claim named authorities, which is an array of strings based on what authorities a user has.

The new version of OAuth Resource server ignores this claim and the only granted authorities of a user are ROLE_USER and SCOPE_<scope> which in my opinion are inadequate.

One could write one's own converter, but to use it, a new instance of JwtAuthenticationConverter has to be created. Also, this solution means that the previously existing ROLE_USER and SCOPE_<scope> would not be available without code duplicating or having to deal with a SCOPE_ prefix before all roles, which is not desirable.

The solution could be an implementation of JwtAuthenticationConverter which holds a DelegatingJwtGrantedAuthoritiesConverter able to iterate over multiple JwtGrantedAuthoritiesConverters, merging the results of one another.

This solution could be wired into the JwtConfigurer as well, allowing the developer to add multiple converters without the need to replace default instances.

[jzheaux]

Thanks for your interest in making Spring Security better, @rolaca11.

It seems to me that supporting the authorities claim is already pretty simple:

JwtGrantedAuthoritiesConverter authorities = new JwtGrantedAuthoritiesConverter();
authorities.setAuthoritiesClaimName("authorities");

http
    .oauth2ResourceServer()
        .jwt()
            .jwtAuthenticationConverter(jwt -> 
                new JwtAuthenticationToken(jwt, authorities.convert(jwt)));

So, I'm not really seeing the benefit of adding complexity to the DSL.

There may be value in a DelegatingJwtGrantedAuthoritiesConverter, though. Can you explain more about what you are trying to achieve in your application? Is it simply that you have JWTs that have both an authorities claim and a scope claim?

Also, I'm a little confused by this statement:

the only granted authorities of a user are ROLE_USER and SCOPE_

Spring Security's Resource Server support only adds SCOPE_<scope> authorities. Can you clarify how you are getting a ROLE_USER authority?

[rolaca11]

Hi,

Is it simply that you have JWTs that have both an authorities claim and a scope claim?

Yes and originally partly no. Partly no, because I didn't realize you can set a claimName to the JwtGrantedAuthoritiesConverter, so that was my mistake. However, I do want to extract my granted authorities from both the scope and authorities.

Another concern is that no matter what, the prefix extracted by an instance of JwtGrantedAuthoritiesConverter will have the same prefix. So if I have authorities from scope, I'd like the extracted authority from that to be SCOPE_ (the default behavior). If I'd like to have my authorities extracted from authorities to have a different scope, I'd need to use another instance of the converter, where I set the prefix to be something different.

Can you clarify how you are getting a ROLE_USER authority?

Of course, the ROLE_USER authority comes from the fact that OAuth2UserAuthority is instantiated with a constructor only accepting attributes. This constructor defaults the authority name to ROLE_USER. I can't find the usage of this at the moment, because I'm not in front of my computer.

[jzheaux]

If I'd like to have my authorities extracted from authorities to have a different scope, I'd need to use another instance of the converter, where I set the prefix to be something different.

That makes sense, yes. So then you could do:

JwtGrantedAuthoritiesConverter authorities = new JwtGrantedAuthoritiesConverter();
authorities.setAuthorityPrefix("ROLE_");
authorities.setAuthoritiesClaimName("authorities");
// ... etc.

However, I do want to extract my granted authorities from both the scope and authorities.

Okay, great. Yes, I think there's value in making this a bit simpler, I think in the same way that it's done with DelegatingOAuth2TokenValidator.

Would you be interested in changing your PR to only introduce DelegatingJwtGrantedAuthoritiesConverter and its corresponding tests? I'd like to hold off for now on changing the DSL, but I think adding the class is helpful.

At that point, you could do:

JwtGrantedAuthoritiesConverter composite =
    new DelegatingJwtGrantedAuthoritiesConverter(authorities(), scope());

http
    .oauth2ResourceServer()
        .jwt()
             .jwtAuthoritiesConverter(jwt -> new JwtAuthenticationToken(jwt, composite.convert(jwt)));

// ...

JwtGrantedAuthoritiesConverter authorities() {
    JwtGrantedAuthoritiesConverter authorities = new JwtGrantedAuthoritiesConverter();
    authorities.setAuthorityPrefix("ROLE_");
    authorities.setAuthoritiesClaimName("authorities");
    return authorities;
}

JwtGrantedAuthoritiesConverter scope() {
    return new JwtGrantedAuthoritiesConverter();
}

Of course, the ROLE_USER authority comes from the fact that OAuth2UserAuthority is instantiated with a constructor only accepting attributes.

It sounds like you might be mixing Spring Security's OAuth 2.0 Client and Resource Server support together in your application. OAuth2UserAuthority isn't used by Resource Server.

[rolaca11]

Would you be interested in changing your PR to only introduce DelegatingJwtGrantedAuthoritiesConverter and its corresponding tests?

Of course, however I'll need some time with it, because I'll be busy with other stuff this week

[NeluAkejelu]

JwtGrantedAuthoritiesConverter composite =
new DelegatingJwtGrantedAuthoritiesConverter(authorities(), scope());

Please any information on the status of this addition DelegatingJwtGrantedAuthoritiesConverter ? I need to implement something similar that allows to extract my granted authorities from both the scope and authorities.

[jzheaux]

Thanks for the ping, @NeluAkejelu. My apologies as this one fell off my radar. Please see the related PR to see if it suits your needs.

[NeluAkejelu]

@jzheaux Thanks. I'll take a look.