kernel/linux.git/net/mptcp/ctrl.c, branch v6.19.11

mptcp: reset blackhole on success with non-loopback ifaces

2025-09-19T14:06:19+00:00

When a first MPTCP connection gets successfully established after a blackhole period, 'active_disable_times' was supposed to be reset when this connection was done via any non-loopback interfaces. Unfortunately, the opposite condition was checked: only reset when the connection was established via a loopback interface. Fixing this by simply looking at the opposite. This is similar to what is done with TCP FastOpen, see tcp_fastopen_active_disable_ofo_check(). This patch is a follow-up of a previous discussion linked to commit 893c49a78d9f ("mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable()."), see [1]. Fixes: 27069e7cb3d1 ("mptcp: disable active MPTCP in case of blackhole") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/4209a283-8822-47bd-95b7-87e96d9b7ea3@kernel.org [1] Signed-off-by: Matthieu Baerts (NGI0) Reviewed-by: Simon Horman Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250918-net-next-mptcp-blackhole-reset-loopback-v1-1-bf5818326639@kernel.org Signed-off-by: Jakub Kicinski

mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable().

2025-09-18T01:10:22+00:00

mptcp_active_enable() is called from subflow_finish_connect(), which is icsk->icsk_af_ops->sk_rx_dst_set() and it's not always under RCU. Using sk_dst_get(sk)->dev could trigger UAF. Let's use __sk_dst_get() and dst_dev_rcu(). Fixes: 27069e7cb3d1 ("mptcp: disable active MPTCP in case of blackhole") Signed-off-by: Kuniyuki Iwashima Reviewed-by: Matthieu Baerts (NGI0) Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250916214758.650211-8-kuniyu@google.com Signed-off-by: Jakub Kicinski

mptcp: Call dst_release() in mptcp_active_enable().

2025-09-18T01:10:22+00:00

mptcp_active_enable() calls sk_dst_get(), which returns dst with its refcount bumped, but forgot dst_release(). Let's add missing dst_release(). Cc: stable@vger.kernel.org Fixes: 27069e7cb3d1 ("mptcp: disable active MPTCP in case of blackhole") Signed-off-by: Kuniyuki Iwashima Reviewed-by: Matthieu Baerts (NGI0) Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250916214758.650211-7-kuniyu@google.com Signed-off-by: Jakub Kicinski

mptcp: track fallbacks accurately via mibs

2025-07-25T18:29:04+00:00

Add the mibs required to cover the few possible fallback causes still lacking suck info. Move the relevant mib increment into the fallback helper, so that no eventual future fallback operation will miss a paired mib increment. Additionally track failed fallback via its own mib, such mib is incremented only when a fallback mandated by the protocol fails - due to racing subflow creation. While at the above, rename an existing helper to reduce long lines problems all along. Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250723-net-next-mptcp-track-fallbacks-v1-1-a83cce08f2d5@kernel.org Signed-off-by: Jakub Kicinski

mptcp: sysctl: add available_path_managers

2025-03-20T09:14:49+00:00

Similarly to net.mptcp.available_schedulers, this patch adds a new one net.mptcp.available_path_managers to list the available path managers. Signed-off-by: Geliang Tang Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250313-net-next-mptcp-pm-ops-intro-v1-11-f4e4a88efc50@kernel.org Signed-off-by: Paolo Abeni

mptcp: sysctl: map pm_type to path_manager

2025-03-20T09:14:49+00:00

This patch adds a new proc_handler "proc_pm_type" for "pm_type" to map old path manager sysctl "pm_type" to the newly added "path_manager". path_manager pm_type MPTCP_PM_TYPE_KERNEL -> "kernel" MPTCP_PM_TYPE_USERSPACE -> "userspace" It is important to add this to keep a compatibility with the now deprecated pm_type sysctl knob. Signed-off-by: Geliang Tang Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250313-net-next-mptcp-pm-ops-intro-v1-10-f4e4a88efc50@kernel.org Signed-off-by: Paolo Abeni

mptcp: sysctl: map path_manager to pm_type

2025-03-20T09:14:49+00:00

This patch maps the newly added path manager sysctl "path_manager" to the old one "pm_type". path_manager pm_type "kernel" -> MPTCP_PM_TYPE_KERNEL "userspace" -> MPTCP_PM_TYPE_USERSPACE others -> __MPTCP_PM_TYPE_NR It is important to add this to keep a compatibility with the now deprecated pm_type sysctl knob. Signed-off-by: Geliang Tang Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250313-net-next-mptcp-pm-ops-intro-v1-9-f4e4a88efc50@kernel.org Signed-off-by: Paolo Abeni

mptcp: sysctl: set path manager by name

2025-03-20T09:14:48+00:00

Similar to net.mptcp.scheduler, a new net.mptcp.path_manager sysctl knob is added to determine which path manager will be used by each newly created MPTCP socket by setting the name of it. Dealing with an explicit name is easier than with a number, especially when more PMs will be introduced. This sysctl knob makes the old one "pm_type" deprecated. Signed-off-by: Geliang Tang Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250313-net-next-mptcp-pm-ops-intro-v1-8-f4e4a88efc50@kernel.org Signed-off-by: Paolo Abeni

mptcp: blackhole: avoid checking the state twice

2025-02-25T02:23:44+00:00

A small cleanup, reordering the conditions to avoid checking things twice. The code here is called in case of timeout on a TCP connection, before triggering a retransmission. But it only acts on SYN + MPC packets. So the conditions can be re-order to exit early in case of non-MPTCP SYN + MPC. This also reduce the indentation levels. Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250221-net-next-mptcp-pm-misc-cleanup-3-v1-10-2b70ab1cee79@kernel.org Signed-off-by: Jakub Kicinski

mptcp: blackhole only if 1st SYN retrans w/o MPC is accepted

2025-01-30T13:02:19+00:00

The Fixes commit mentioned this: > An MPTCP firewall blackhole can be detected if the following SYN > retransmission after a fallback to "plain" TCP is accepted. But in fact, this blackhole was detected if any following SYN retransmissions after a fallback to TCP was accepted. That's because 'mptcp_subflow_early_fallback()' will set 'request_mptcp' to 0, and 'mpc_drop' will never be reset to 0 after. This is an issue, because some not so unusual situations might cause the kernel to detect a false-positive blackhole, e.g. a client trying to connect to a server while the network is not ready yet, causing a few SYN retransmissions, before reaching the end server. Fixes: 27069e7cb3d1 ("mptcp: disable active MPTCP in case of blackhole") Cc: stable@vger.kernel.org Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Signed-off-by: Paolo Abeni