Re: [RFC PATCH bpf-next 1/5] bpf: Add link support for sk_msg prog

[Jakub Sitnicki <jakub@cloudflare.com>]

On Fri, Mar 08, 2024 at 04:59 PM -08, Andrii Nakryiko wrote:
> On Tue, Mar 5, 2024 at 12:22 PM Yonghong Song <yonghong.song@linux.dev> wrote:
>>
>> Add link support for sk_msg program. This will make user space
>> easy to manage as most common used programs have alrady have
>> link support.
>
> So we have:
>
> SEC("sk_skb/stream_parser") mapping to SK_SKB/BPF_SK_SKB_STREAM_PARSER.
> SEC("sk_skb/stream_verdict") mapping to SK_SKB/BPF_SK_SKB_STREAM_VERDICT.
> SEC("sk_msg") mapping to SK_MSG/BPF_SK_MSG_VERDICT.
>
> Are those all kind of in the same category and should we support link
> for both SK_MSG and SK_SKB? I'm not too familiar, maybe John or
> someone else can clarify.

We also have the most recent SK_SKB/BPF_SK_SKB_VERDICT [1], which is
what one would use instead of SK_SKB/BPF_SK_SKB_STREAM_* prog pair when
chopping the stream of bytes into frames is not needed. For instance,
because we're redirecting from a UDP socket.

I have a cheatsheet that clarifies in which redirect-with-sockmap
configuration what program type + attach type is used [2].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a7ba4558e69a3c2ae4ca521f015832ef44799538
[2] https://github.com/jsitnicki/srecon-2023-sockmap/blob/main/sockmap-cheatsheet.png