MPTCP connection requests toward a listening socket created by the in-kernel PM for a port based signal endpoint will never be accepted, they need to be explicitly rejected. - Patch 1: Explicitly reject such requests. A fix for >= v5.12. - Patch 2: Cover this case in the MPTCP selftests to avoid regressions. Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx> --- Changes in v2: - This new version fixes the root cause for the issue Cong Wang sent a patch for a few weeks ago, see the v1, and the explanations below. The new version is very different from the v1, from a different author. Thanks to Cong Wang for the first analysis, and to Paolo for having spot the root cause, and sent a fix for it. - Link to v1: https://lore.kernel.org/r/20240908180620.822579-1-xiyou.wangcong@xxxxxxxxx - Link: https://lore.kernel.org/r/a5289a0d-2557-40b8-9575-6f1a0bbf06e4@xxxxxxxxxx --- Paolo Abeni (2): mptcp: prevent MPC handshake on port-based signal endpoints selftests: mptcp: join: test for prohibited MPC to port-based endp net/mptcp/mib.c | 1 + net/mptcp/mib.h | 1 + net/mptcp/pm_netlink.c | 1 + net/mptcp/protocol.h | 1 + net/mptcp/subflow.c | 11 +++ tools/testing/selftests/net/mptcp/mptcp_join.sh | 117 +++++++++++++++++------- 6 files changed, 101 insertions(+), 31 deletions(-) --- base-commit: 174714f0e505070a16be6fbede30d32b81df789f change-id: 20241014-net-mptcp-mpc-port-endp-4f88bd428ec7 Best regards, -- Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>