Re: [PATCH net-next 2/2] Add a eBPF helper function to retrieve socket uid

[Eric Dumazet]

On Fri, 2017-02-03 at 10:18 +0900, Lorenzo Colitti wrote:
> On Fri, Feb 3, 2017 at 9:31 AM, Eric Dumazet <eric.duma...@gmail.com> wrote:
> >> It should be safe to call sock_net_uid on any type of socket
> >> (including NULL). sk_uid was added to struct sock in 86741ec25462
> >> ("net: core: Add a UID field to struct sock.")
> >
> > But a request socket or a timewait socket do not have this field.
> >
> > Daniel point is valid.
> 
> My bad. Yes.
> 
> It would definitely be useful to have the UID available in request
> sockets, and perhaps timewait sockets as well. That could be done by
> moving the UID to sock_common, or with something along the lines of:
> 
>  static inline kuid_t sock_net_uid(const struct net *net, const struct sock 
> *sk)
>  {
> +       if (sk && sk->sk_state == TCP_NEW_SYN_RECV)
> +               sk = sk->__sk_common.skc_listener;
> +       else if (sk && !sk_fullsock(sk))
> +               sk = NULL;
> +
>         return sk ? sk->sk_uid : make_kuid(net->user_ns, 0);
>  }
> 
> Any thoughts on which is better?

You could use

if (sk) {
    sk = sk_to_full_sk(sk);
    if (sk_fullsock(sk))
        return sk->sk_uid;
}