From 96939cec994070aa5df852c10fad5fc303a97ea3 Mon Sep 17 00:00:00 2001 From: "Matthieu Baerts (NGI0)" Date: Fri, 12 Sep 2025 14:52:20 +0200 Subject: [PATCH] mptcp: set remote_deny_join_id0 on SYN recv When a SYN containing the 'C' flag (deny join id0) was received, this piece of information was not propagated to the path-manager. Even if this flag is mainly set on the server side, a client can also tell the server it cannot try to establish new subflows to the client's initial IP address and port. The server's PM should then record such info when received, and before sending events about the new connection. Fixes: df377be38725 ("mptcp: add deny_join_id0 in mptcp_options_received") Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250912-net-mptcp-pm-uspace-deny_join_id0-v1-1-40171884ade8@kernel.org Signed-off-by: Jakub Kicinski --- net/mptcp/subflow.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 3f1b62a9fe889..f31a3a79531a2 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -883,6 +883,10 @@ create_child: ctx->subflow_id = 1; owner = mptcp_sk(ctx->conn); + + if (mp_opt.deny_join_id0) + WRITE_ONCE(owner->pm.remote_deny_join_id0, true); + mptcp_pm_new_connection(owner, child, 1); /* with OoO packets we can reach here without ingress -- 2.47.3