Re: [PATCH mptcp-net 0/7] mptcp: pm: nl: announce deny-join-id0 attribute

[Matthieu Baerts <matttbe@kernel.org>]

Hello,

On 29/08/2025 22:33, Matthieu Baerts (NGI0) wrote:
> During the connection establishment, a peer can tell the other that it
> cannot establish new subflows to the initial IP address and port by
> setting the 'C' flag [1]. Doing so makes sense when the sender is behind
> a strict NAT, operating behind a legacy Layer 4 load balancer, or using
> anycast IP address for example.
> 
> When this 'C' flag is set, the path-managers must then not try to
> establish new subflow to the other peer's initial IP address and port.
> The in-kernel PM has access to this info, but the userspace PM didn't.
> 
> The last patch is adding the new attribute in the Netlink events. Please
> see the note with a question about how to add this new attribute.
> 
> But before that, a few fixes have been added:
> 
> - Patch 1: add remote_deny_join_id0 info on passive connections. A fix
>   for v5.14.
> 
> - Patch 2: respect the deny_join_id0 attribute by blocking the creation
>   of new subflows to the initial IP address and port if set. A fix for
>   v5.19.
> 
> - Patch 3: record the deny_join_id0 info when TFO is used. A fix for
>   v6.2.
> 
> - Patch 4: fix a wrong attribute type in the Netlink MPTCP specs. A fix
>   for v6.7.
> 
> - Patch 5: stop mentioning net.mptcp.pm_type in the doc as it is
>   deprecated. A fix for v6.15.
> 
> - Patch 6: support Shellcheck v0.11.0 in the MPTCP selftests.
> 
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
> ---
> Matthieu Baerts (NGI0) (7):
>       mptcp: set remote_deny_join_id0 on SYN recv
>       mptcp: pm: userspace: respect deny_join_id0 attr
>       mptcp: tfo: record 'deny join id0' info

>       netlink: specs: mptcp: fix if-idx attribute type
>       doc: mptcp: net.mptcp.pm_type is deprecated
>       selftests: mptcp: shellcheck: support v0.11.0

I just applied these last 3 patches, reviewed by Geliang (Thanks)

New patches for t/upstream-net and t/upstream:
- 7dae247dbfe1: netlink: specs: mptcp: fix if-idx attribute type
- ef0f22271156: doc: mptcp: net.mptcp.pm_type is deprecated
- f44e77b81e04: selftests: mptcp: shellcheck: support v0.11.0
- Results: 64d8ee7c00d0..d449a1cf7863 (export-net)
- Results: 64f95ae49169..f6a1bd069542 (export)

Tests are now in progress:

- export-net:
https://github.com/multipath-tcp/mptcp_net-next/commit/bdfdb385586b1310d7789298f64a9a4075d879c5/checks
- export:
https://github.com/multipath-tcp/mptcp_net-next/commit/9c5417b6ec48952bda958c08960c129f69f0314a/checks

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