On Mon, May 11, 2020 at 08:52:03PM +0200, Jakub Sitnicki wrote:
[ ... ]
> +BPF_CALL_3(bpf_sk_lookup_assign, struct bpf_sk_lookup_kern *, ctx,
> + struct sock *, sk, u64, flags)
The SK_LOOKUP bpf_prog may have already selected the proper reuseport sk.
It is possible by looking up sk from sock_map.
Thus, it is not always desired to do lookup_reuseport() after sk_assign()
in patch 5. e.g. reuseport_select_sock() just uses a normal hash if
there is no reuse->prog.
A flag (e.g. "BPF_F_REUSEPORT_SELECT") can be added here to
specifically do the reuseport_select_sock() after sk_assign().
If not set, reuseport_select_sock() should not be called.
> +{
> + if (unlikely(flags != 0))
> + return -EINVAL;
> + if (unlikely(sk_is_refcounted(sk)))
> + return -ESOCKTNOSUPPORT;
> +
> + /* Check if socket is suitable for packet L3/L4 protocol */
> + if (sk->sk_protocol != ctx->protocol)
> + return -EPROTOTYPE;
> + if (sk->sk_family != ctx->family &&
> + (sk->sk_family == AF_INET || ipv6_only_sock(sk)))
> + return -EAFNOSUPPORT;
> +
> + /* Select socket as lookup result */
> + ctx->selected_sk = sk;
> + return 0;
> +}
> +
