kernel/linux.git/include/uapi/linux/mptcp.h, branch v6.12.80

mptcp: pm: ignore unknown endpoint flags

2026-01-08T09:14:57+00:00

[ Upstream commit 0ace3297a7301911e52d8195cb1006414897c859 ] Before this patch, the kernel was saving any flags set by the userspace, even unknown ones. This doesn't cause critical issues because the kernel is only looking at specific ones. But on the other hand, endpoints dumps could tell the userspace some recent flags seem to be supported on older kernel versions. Instead, ignore all unknown flags when parsing them. By doing that, the userspace can continue to set unsupported flags, but it has a way to verify what is supported by the kernel. Note that it sounds better to continue accepting unsupported flags not to change the behaviour, but also that eases things on the userspace side by adding "optional" endpoint types only supported by newer kernel versions without having to deal with the different kernel versions. A note for the backports: there will be conflicts in mptcp.h on older versions not having the mentioned flags, the new line should still be added last, and the '5' needs to be adapted to have the same value as the last entry. Fixes: 01cacb00b35c ("mptcp: add netlink-based PM") Cc: stable@vger.kernel.org Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20251205-net-mptcp-misc-fixes-6-19-rc1-v1-1-9e4781a6c1b8@kernel.org Signed-off-by: Jakub Kicinski [ GENMASK(5, 0) => GENMASK(4, 0) + context ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

mptcp: pm: nl: announce deny-join-id0 flag

2025-09-25T09:13:50+00:00

commit 2293c57484ae64c9a3c847c8807db8c26a3a4d41 upstream. During the connection establishment, a peer can tell the other one 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 subflows 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 RFC8684 [1] is strict about that: (...) therefore the receiver MUST NOT try to open any additional subflows toward this address and port. So it is important to tell the userspace about that as it is responsible for the respect of this flag. When a new connection is created and established, the Netlink events now contain the existing but not currently used 'flags' attribute. When MPTCP_PM_EV_FLAG_DENY_JOIN_ID0 is set, it means no other subflows to the initial IP address and port -- info that are also part of the event -- can be established. Link: https://datatracker.ietf.org/doc/html/rfc8684#section-3.1-20.6 [1] Fixes: 702c2f646d42 ("mptcp: netlink: allow userspace-driven subflow establishment") Reported-by: Marek Majkowski Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/532 Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250912-net-mptcp-pm-uspace-deny_join_id0-v1-2-40171884ade8@kernel.org Signed-off-by: Jakub Kicinski [ Conflicts in mptcp_pm.yaml, because the indentation has been modified in commit ec362192aa9e ("netlink: specs: fix up indentation errors"), which is not in this version. Applying the same modifications, but at a different level. ] Signed-off-by: Matthieu Baerts (NGI0) Signed-off-by: Greg Kroah-Hartman

mptcp: add last time fields in mptcp_info

2024-04-11T15:19:54+00:00

This patch adds "last time" fields last_data_sent, last_data_recv and last_ack_recv in struct mptcp_sock to record the last time data_sent, data_recv and ack_recv happened. They all are initialized as tcp_jiffies32 in __mptcp_init_sock(), and updated as tcp_jiffies32 too when data is sent in __subflow_push_pending(), data is received in __mptcp_move_skbs_from_subflow(), and ack is received in ack_update_msk(). Similar to tcpi_last_data_sent, tcpi_last_data_recv and tcpi_last_ack_recv exposed with TCP, this patch exposes the last time "an action happened" for MPTCP in mptcp_info, named mptcpi_last_data_sent, mptcpi_last_data_recv and mptcpi_last_ack_recv, calculated in mptcp_diag_fill_info() as the time deltas between now and the newly added last time fields in mptcp_sock. Since msk->last_ack_recv needs to be protected by mptcp_data_lock/unlock, and lock_sock_fast can sleep and be quite slow, move the entire mptcp_data_lock/unlock block after the lock/unlock_sock_fast block. Then mptcpi_last_data_sent and mptcpi_last_data_recv are set in lock/unlock_sock_fast block, while mptcpi_last_ack_recv is set in mptcp_data_lock/unlock block, which is protected by a spinlock and should not block for too long. Also add three reserved bytes in struct mptcp_info not to have holes in this structure exposed to userspace. Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/446 Signed-off-by: Geliang Tang Reviewed-by: Mat Martineau Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://lore.kernel.org/r/20240410-upstream-net-next-20240405-mptcp-last-time-info-v2-1-f95bd6b33e51@kernel.org Signed-off-by: Jakub Kicinski

mptcp: add mptcpi_subflows_total counter

2023-11-30T04:06:17+00:00

If the initial subflow has been removed, we cannot know without checking other counters, e.g. ss -ti | grep -c tcp-ulp-mptcp or getsockopt(SOL_MPTCP, MPTCP_FULL_INFO, ...) (or others except MPTCP_INFO of course) and then check mptcp_subflow_data->num_subflows to get the total amount of subflows. This patch adds a new counter mptcpi_subflows_total in mptcpi_flags to store the total amount of subflows, including the initial one. A new helper __mptcp_has_initial_subflow() is added to check whether the initial subflow has been removed or not. With this helper, we can then compute the total amount of subflows from mptcp_info by doing something like: mptcpi_subflows_total = mptcpi_subflows + __mptcp_has_initial_subflow(msk). Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/428 Reviewed-by: Matthieu Baerts Signed-off-by: Geliang Tang Signed-off-by: Mat Martineau Link: https://lore.kernel.org/r/20231128-send-net-next-2023107-v4-1-8d6b94150f6b@kernel.org Signed-off-by: Jakub Kicinski

doc/netlink: Update schema to support cmd-cnt-name and cmd-max-name

2023-10-27T21:56:04+00:00

allow specifying cmd-cnt-name and cmd-max-name in netlink specs, in accordance with Documentation/userspace-api/netlink/c-code-gen.rst. Use cmd-cnt-name and attr-cnt-name in the mptcp yaml spec and in the corresponding uAPI headers, to preserve the #defines we had in the past and avoid adding new ones. v2: - squash modification in mptcp.yaml and MPTCP uAPI headers Suggested-by: Jakub Kicinski Signed-off-by: Davide Caratti Link: https://lore.kernel.org/r/12d4ed0116d8883cf4b533b856f3125a34e56749.1698415310.git.dcaratti@redhat.com Signed-off-by: Jakub Kicinski

uapi: mptcp: use header file generated from YAML spec

2023-10-24T20:00:31+00:00

generated with: $ ./tools/net/ynl/ynl-gen-c.py --mode uapi \ > --spec Documentation/netlink/specs/mptcp.yaml \ > --header -o include/uapi/linux/mptcp_pm.h Link: https://github.com/multipath-tcp/mptcp_net-next/issues/340 Acked-by: Paolo Abeni Signed-off-by: Davide Caratti Signed-off-by: Mat Martineau Link: https://lore.kernel.org/r/20231023-send-net-next-20231023-1-v2-5-16b1f701f900@kernel.org Signed-off-by: Jakub Kicinski

net: mptcp: convert netlink from small_ops to ops

2023-10-24T20:00:31+00:00

in the current MPTCP control plane, all operations use a netlink attribute of the same type "MPTCP_PM_ATTR". However, add/del/get/flush operations only parse the first element in the message _ the one that describes MPTCP endpoints (that was named MPTCP_PM_ATTR_ADDR and mostly used in ADD_ADDR operations _ probably the similarity of "attr", "addr" and "add" might cause some confusion to human readers). Convert MPTCP from 'small_ops' to 'ops', thus allowing different attributes for each single operation, hopefully makes all this clearer to human readers. - use a separate attribute set for add/del/get/flush address operation, binary compatible with the existing one, to store the endpoint address. MPTCP_PM_ENDPOINT_ADDR is added to the uAPI (with the same value as MPTCP_PM_ATTR_ADDR) for these operations. - convert mptcp_pm_ops[] and add policy files accordingly. this prepares MPTCP control plane to be described as YAML spec. Link: https://github.com/multipath-tcp/mptcp_net-next/issues/340 Acked-by: Paolo Abeni Signed-off-by: Davide Caratti Signed-off-by: Mat Martineau Link: https://lore.kernel.org/r/20231023-send-net-next-20231023-1-v2-3-16b1f701f900@kernel.org Signed-off-by: Jakub Kicinski

mptcp: introduce MPTCP_FULL_INFO getsockopt

2023-06-22T05:45:57+00:00

Some user-space applications want to monitor the subflows utilization. Dumping the per subflow tcp_info is not enough, as the PM could close and re-create the subflows under-the-hood, fooling the accounting. Even checking the src/dst addresses used by each subflow could not be enough, because new subflows could re-use the same address/port of the just closed one. This patch introduces a new socket option, allow dumping all the relevant information all-at-once (everything, everywhere...), in a consistent manner. Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/388 Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts Signed-off-by: Matthieu Baerts Signed-off-by: Jakub Kicinski

mptcp: track some aggregate data counters

2023-06-22T05:45:57+00:00

Currently there are no data transfer counters accounting for all the subflows used by a given MPTCP socket. The user-space can compute such figures aggregating the subflow info, but that is inaccurate if any subflow is closed before the MPTCP socket itself. Add the new counters in the MPTCP socket itself and expose them via the existing diag and sockopt. While touching mptcp_diag_fill_info(), acquire the relevant locks before fetching the msk data, to ensure better data consistency Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/385 Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts Signed-off-by: Matthieu Baerts Signed-off-by: Jakub Kicinski

mptcp: add pm listener events

2022-12-02T04:06:06+00:00

This patch adds two new MPTCP netlink event types for PM listening socket create and close, named MPTCP_EVENT_LISTENER_CREATED and MPTCP_EVENT_LISTENER_CLOSED. Add a new function mptcp_event_pm_listener() to push the new events with family, port and addr to userspace. Invoke mptcp_event_pm_listener() with MPTCP_EVENT_LISTENER_CREATED in mptcp_listen() and mptcp_pm_nl_create_listen_socket(), invoke it with MPTCP_EVENT_LISTENER_CLOSED in __mptcp_close_ssk(). Signed-off-by: Geliang Tang Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts Signed-off-by: Jakub Kicinski