Re: [PATCH mptcp-next v3 1/2] mptcp: add bpf_iter_task for mptcp_sock

[Matthieu Baerts <matttbe@kernel.org>]

Hi Geliang,

On 21/03/2025 05:14, Geliang Tang wrote:
> On Tue, 2025-03-18 at 12:26 +0100, Matthieu Baerts wrote:

(...)

>> Mmh, all 8 callbacks from add_addr to here seem to be linked to
>> Netlink
>> commands, right? If yes, they should not be here: they don't make
>> sense
>> for a BPF PM, no? BPF PMs should be configured with BPF, and not via
>
> Do you have any idea how we can pass commands like ADD_ADDR and
> addresses from user space to BPF?

The userspace can inject any kind of BPF program. Additional addresses
can then be hardcoded in this program, or it can load them from eBPF
maps, or read skel->bss->(...), etc.

Netlink is then not needed.

> What I can think of is passing through sockopt, the user space passes
> the command and the address through setsockopt, and the BPF program
> handles it through the custom "cgroup/setsockopt". I would like to hear
> your opinions. If you also agree to use sockopt to implement it, I can
> write a test program for this.
That's a good idea for userspace apps which want to control how the
MPTCP PM is acting. I guess MPTCP BPF PM will generally not be linked to
network apps: a separate application dedicated to inject and configure
the BPF PM, no?

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.