Re: [PATCH net-next] net: bpf: hook for inet port bind conflict check

[Alexei Starovoitov]

On Wed, Dec 29, 2021 at 12:56 AM <menglong8.dong@xxxxxxxxx> wrote:
>
> From: Menglong Dong <imagedong@xxxxxxxxxxx>
>
> This hook of cgroup is called while TCP/UDP local port bind conflict
> check. This is different from the 'commit aac3fc320d94 ("bpf: Post-hooks
> for sys_bind")', as it is also called in autobind case.
>
> For TCP, this hook is called during sys_bind() and autobind. And it
> is also called during tcp_v4_connect() before hash the sock to ehash,
> during which src ip, src port, dst ip, and dst port is already
> allocated, means that we have a chance to determine whether this
> connect should continue.
>
> This can be useful when we want some applications not to use some
> port (include auto bind port). For autobind, the kernel has the chance
> to choose another port.

The use case is too vague to consider adding a new hook.
Also there are no selftests.