Re: [RFC PATCH bpf-next 0/5] Add bpf_link support for sk_msg prog

[Jakub Sitnicki <jakub@cloudflare.com>]

On Tue, Mar 05, 2024 at 12:21 PM -08, Yonghong Song wrote:
> One of our internal services started to use sk_msg program and currently
> it used existing prog attach/detach2 as demonstrated in selftests.
> But attach/detach of all other bpf programs are based on bpf_link.
> Consistent attach/detach APIs for all programs will make things easy to
> undersand and less error prone. So this patch added bpf_link
> support for BPF_PROG_TYPE_SK_MSG.
>
> I marked the patch as RFC as not all functionality are covered
> by tests yet, e.g. update_prog(). Maybe somebody can suggest
> an existing test which I can look into.
> Or maybe some other tests need to be added as well.

I have a general remark, not specific to this work.

We can't attach with links from CLI, apart from when auto-attach is
supported.  `bpftool prog attach` doesn't use bpf links. For instance:

bpftool prog attach \
        pinned /sys/fs/bpf/test/sk_msg_prog \
        sk_msg_verdict \
        pinned /sys/fs/bpf/test/sock_map

Is there a plan for the CLI tooling to support it?