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661 commits

Author SHA1 Message Date
Paolo Abeni
f3ef033573 mptcp: fix bad accounting in __mptcp_subflow_push_pending()
If __subflow_push_pending() errors out we should avoid updating the
copied byte counters, to avoid mismatch push call later on.

Fixes: 0fa1b3783a ("mptcp: use get_send wrapper")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260917-net-mptcp-misc-fixes-7-3-rc4-v2-3-0cf5c72667c8@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-09-17 08:14:33 -07:00
Paolo Abeni
42064de57f mptcp: close race between scheduler and state change
The mptcp scheduler may race with subflow sockets state change: data
transmission on the selected socket may fail and a later release could
try to use mss_now reset to 0 for a divide operation.

Address the issue by explicitly checking for the critical scenario.

Fixes: c886d70286 ("mptcp: do not queue data on closed subflows")
Cc: stable@vger.kernel.org
Reported-by: Shardul Bankar <shardul.b@mpiricsoftware.com>
Reported-by: Xinyang Ge <xinyang@anthropic.com>
Closes: https://lore.kernel.org/20260525194828.1137119-1-shardul.b@mpiricsoftware.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260917-net-mptcp-misc-fixes-7-3-rc4-v2-2-0cf5c72667c8@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-09-17 08:14:33 -07:00
Paolo Abeni
2b0f561f21 mptcp: avoid unneeded actions on subflow reset
Once in a blue moon, the mptcp receive path can recursively call
mptcp_data_ready() via state change under unlucky error conditions, and
then try to hold the data lock again.

Break the recursion loop explicitly checking for the exceptional
condition.

Add a new flag instead of using an existing one like 'closing', to exit
early in subflow_state_change(), and explicitly flush the RX queue at
reset time.

This avoids unneeded processing to check for available data -- calling
get_mapping_status() and more on a dying subflow -- but also in error
reporting and worker scheduling.

Note that we must consume the currently peeked skb before invoking
mptcp_dss_corruption to avoid consuming it again after the eventual
reset has freed it.

Fixes: e32d262c89 ("mptcp: handle consistently DSS corruption")
Cc: stable@vger.kernel.org
Reported-by: Xinyang Ge <xinyang@anthropic.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260917-net-mptcp-misc-fixes-7-3-rc4-v2-1-0cf5c72667c8@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-09-17 08:14:33 -07:00
Mark Amirkan
60404266ef mptcp: return sk_wait_data() errors from recvmsg()
Commit 5813022985 ("mptcp: error out earlier on disconnect") made
mptcp_recvmsg() stop when sk_wait_data() returns an error.  The error is
stored in err, but the function then jumps to a path which returns
copied.  When no data was copied, recvmsg() therefore returns zero and
reports a false EOF.

Store the result in copied, which is the value returned by the function.
This also keeps the usual partial-read result when data was copied before
the error.

A recvmsg() blocked in one thread reproduces the issue when another
thread disconnects the same MPTCP socket with connect(AF_UNSPEC).
Before this change recvmsg() returns zero; afterwards it returns -EPIPE.

Fixes: 5813022985 ("mptcp: error out earlier on disconnect")
Cc: stable@vger.kernel.org
Signed-off-by: Mark Amirkan <markdamirkan@gmail.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260913-b4-send-mptcp-recv-error-v1-1-4eaa3684a8b8@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-09-16 17:28:06 -07:00
Paolo Abeni
f01b827574 mptcp: avoid pruning for OoW data
Pruning is expansive and destructive, do it only when we expect
to accept the skb triggering the cleanup.

Fixes: e468d37118 ("mptcp: implemented OoO queue pruning")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-15-df1de70348b6@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-09-09 13:32:56 -07:00
Paolo Abeni
a4257a91af mptcp: being below memory limit is a likely() condition
The current compiler hint annotation is wrong, due to inverted
logic in the previous revision of the relevant code.

Fixes: e468d37118 ("mptcp: implemented OoO queue pruning")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-14-df1de70348b6@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-09-09 13:32:56 -07:00
Paolo Abeni
caa4a79f74 mptcp: remove unneeded READ_ONCE() annotation
The subflow->fully_established flag is always written under the subflow
socket lock. Reading such value under the same lock does not require any
ONCE annotation.

Fixes: 581c8cbfa9 ("mptcp: annotate data-races around subflow->fully_established")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-10-df1de70348b6@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-09-09 13:32:55 -07:00
Paolo Abeni
85c580b0d8 mptcp: prevent race between disconnect() and rtx
Sashiko noted that the two event can race, leading to inconsistent
status. Prevent the race using the synchronous timer stop operation.

Cc: stable@vger.kernel.org
Fixes: b29fcfb54c ("mptcp: full disconnect implementation")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-6-df1de70348b6@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-09-09 13:32:55 -07:00
Paolo Abeni
e2ab913f68 mptcp: do not reschedule the RTX timer for fallback sockets
On fallback socket the retrans timer is a quite convoluted no-op, but
currently nothing prevents the MPTCP core to keep rescheduling it.

Additionally gate RTX timer reset to the msk not being fallen back to
TCP yet. To avoid adding multiple tests in fast-path, use a new flags
bit for such condition.

The RTX enable bit is clear at close time and set before the msk could
start retransmitting, with a couple of caveats:

- passive sockets inherit the bit from the listener msk; set the bit on
  such socket to avoid flipping it in the fast-path, even if the
  listener will obviously never retransmit.

- while fastopening (MPTFO), mptcp_sendmsg_fastopen still ends-up
  calling mptcp_connect via tcp_sendmsg_fastopen ->
  __inet_stream_connect(ssk->sk_socket), and the first subflow's
  sk_socket points to the msk one.

Fixes: b51f9b80c0 ("mptcp: introduce MPTCP retransmission timer")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-1-df1de70348b6@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-09-09 13:32:54 -07:00
Eric Dumazet
18666c73af tcp: use GFP_ATOMIC in tcp_send_active_reset()
tcp_send_active_reset() can be called from contexts where gfp_any()
(in tcp_disconnect()) or sk->sk_allocation (in __tcp_close() and
mptcp_do_fastclose()) evaluates to GFP_KERNEL, which includes
__GFP_FS and __GFP_DIRECT_RECLAIM.

Allocating with GFP_KERNEL while holding the socket lock (sk_lock) creates
a lockdep dependency:
  sk_lock -> fs_reclaim

This causes false-positive lockdep circular locking warnings with storage
subsystems (such as nvme-tcp) that acquire socket locks in block I/O paths
and invoke tcp_disconnect() or close sockets upon teardown:
  set->srcu -> sk_lock -> fs_reclaim -> elevator_lock -> set->srcu

Active resets are small RST packet headers that should never
enter direct reclaim or block while holding socket locks.

Use sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN) inside tcp_send_active_reset()
and remove its priority argument. This preserves __GFP_MEMALLOC access
for SOCK_MEMALLOC sockets, suppresses allocation failure warnings,
and aligns with other control packet allocations (e.g. tcp_send_fin(),
__tcp_send_ack(), tcp_xmit_probe_skb()).

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260827095936.551524-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-28 15:35:38 -07:00
Shardul Bankar
3420c0fd7e mptcp: add per-event MIB counters for MPTCP_RST_EMPTCP resets
MPTCP_RST_EMPTCP (reset reason 1) is used as a catch-all for several
distinct error conditions across subflow setup, authentication, and
data-path validation.  The existing MPRstTx/MPRstRx counters only
track aggregate reset volume, making it difficult to diagnose which
code path is triggering subflow resets in production.

Add per-event MIB counters covering each MPTCP_RST_EMPTCP use site
that is not already covered by an existing counter, named after the
underlying event or condition rather than the reset action:

  MD5SigReset           MD5SIG enabled on listener (incompatible)
  MPJoinSynAckNoMPJoin  SYN/ACK missing MP_JOIN option
  MPJoinAckNoMPJoin     server-side ACK missing MP_JOIN option
                          (fallback path, MPJoin required)
  MPJoinAckNoCtx        server-side ACK with no subflow context
  MPJoinNoIdFound       MP_JOIN with a valid token but no PM local ID
  DssReset              data mapping invalid (also fires on
                          MAPPING_NODSS / EMIDDLEBOX path)
  MPJoinNotEstablished  JOIN attempted on a not-fully-established msk

MPJoinNoIdFound covers the second half of the no-msk MP_JOIN reset:
the existing MPJoinNoTokenFound (MPTCP_MIB_JOINNOTOKEN) only counts the
missing-token case in subflow_token_join_request(), while a JOIN that
carries a valid token but for which the path manager returns no local
id reaches the same MPTCP_RST_EMPTCP in subflow_check_req() uncounted.

The aggregate MPRstTx/MPRstRx counters are unchanged.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/511
Signed-off-by: Shardul Bankar <shardul.b@mpiricsoftware.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260812-net-next-mptcp-misc-feat-7-3-v1-5-1905a818f6cb@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-17 17:25:49 -07:00
Kalpan Jani
ea4eb2adb0 mptcp: honour configured min/max RTO in retransmit paths
The MPTCP-level retransmit timers (DATA_FIN retransmissions and the
fallback timeout) used the hard-coded TCP_RTO_MIN / TCP_RTO_MAX
constants, ignoring the tcp_rto_min_us and tcp_rto_max_ms sysctls.

Make them follow the sysctls instead: seed icsk_rto_min / icsk_rto_max
on the MPTCP socket from the per-netns sysctls in __mptcp_init_sock()
-- the msk does not go through tcp_init_sock(), so these fields would
otherwise stay zero -- and read them directly where the constants were
used:

- mptcp_set_datafin_timeout(): both the backoff cap computation and
  the resulting timer_ival. The two sysctls are validated
  independently, so rto_min > rto_max is a valid configuration; keep
  a max_t() guard so ilog2() is never called with 0.

- __mptcp_set_timeout(): the fallback when no subflow timeout is
  available.

The icsk fields are read directly instead of using the
tcp_rto_min()/tcp_rto_max() helpers: the MPTCP socket does not perform
routing lookups in these paths, so the rto_min route metric checked by
tcp_rto_min() can never apply here. The TCP_RTO_MIN_US /
TCP_RTO_MAX_MS socket options are not supported by MPTCP setsockopt()
either; this can be revisited if they get supported on MPTCP sockets.

The remaining uses of TCP_RTO_MAX in net/mptcp/ctrl.c (default
add_addr_timeout) and net/mptcp/subflow.c (MP_FAIL timeout) are
intentionally left unchanged: they use the constant as a default
duration, not as an RTO bound on a retransmit timer.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/618
Signed-off-by: Kalpan Jani <kalpan.jani@mpiricsoftware.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260812-net-next-mptcp-misc-feat-7-3-v1-4-1905a818f6cb@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-17 17:25:49 -07:00
Paolo Abeni
e468d37118 mptcp: implemented OoO queue pruning
When moving incoming skbs in the msk receive queue and the latter
is above limits, prune it as needed quite alike what TCP is doing
at the subflow level. The main difference relies in the stop condition:
since MPTCP does not perform collapsing, it's better off dropping the
bare minimum to fit the (newer) incoming packet.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Tested-by: Gang Yan <yangang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260807-net-next-mptcp-oooq-pruning-v3-7-dbc1eb853cc3@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11 18:35:38 -07:00
Paolo Abeni
996643574c mptcp: avoid code duplication in __mptcp_move_skb()
Alike TCP, MPTCP handles in-sequence packets and partially overlapping
ones in a very similar way: we can use the same path to handle both,
avoiding some code duplication.

This will also make the next patch simpler.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260807-net-next-mptcp-oooq-pruning-v3-6-dbc1eb853cc3@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11 18:35:38 -07:00
Paolo Abeni
b1224c4b40 mptcp: enforce hard limit on backlog flushing
Currently a wild producer could keep the backlog flushing operation
spinning for an unbound time.

Since the previous patch, the amount of data present in the backlog is
hard-limited. Move the backlog len update at the end of the flush loop to
prevent it spinning forever.

Also, no need to splice back the remaining skbs list into the backlog, as
such list is always empty after each backlog processing loop.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260807-net-next-mptcp-oooq-pruning-v3-5-dbc1eb853cc3@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11 18:35:37 -07:00
Paolo Abeni
e0e4d56b05 mptcp: explicitly drop over memory limits
Currently the enforcement of the rcvbuf constraint is implemented
when moving the skbs into the msk receive or OoO queue, keeping the
incoming skbs in the subflow queue when over limits.

Under significant memory pressure the above can cause permanent data
transfer stalls, as the skb needed to make forward progress can be
stuck in a subflow queue.

Over memory limits, drop the incoming skb, relying on MPTCP-level
retransmissions.

Note that fallback socket must perform the limit before the skb reaches
the subflow-level queue, as dropping an in-sequence already acked skb
would break the stream.

This is not a complete fix for the stall issue, as the drop strategy
needs refinements that will come in the next patches.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260807-net-next-mptcp-oooq-pruning-v3-4-dbc1eb853cc3@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11 18:35:37 -07:00
Paolo Abeni
96d846e3e2 mptcp: let the retrans scheduler do its job
Currently the MPTCP core enforces that when MPTCP-level retrans timer
fires, at most a single dfrag is retransmitted. In some corner-cases, it
may be necessary to retransmit multiple dfrags, and the MPTCP socket
will need to wait multiple retrans timeout to accomplish that.

Remove the mentioned constraint, allowing to transmit multiple dfrags
per retrans period, as long as the scheduler keeps selecting subflows
for retransmissions and pending data is available in the rtx queue.
The default scheduler will transmit a dfrag per available subflow.

Tested-by: Gang Yan <yangang@kylinos.cn>
Tested-by: Geliang Tang <geliang@kernel.org>
Acked-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260807-net-next-mptcp-oooq-pruning-v3-3-dbc1eb853cc3@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11 18:35:37 -07:00
Paolo Abeni
6cafe51e0f mptcp: move the stale logic out of retrans scheduler
This allow separating the stale logic invocation and the retrans
scheduler, and will simplify the next patch.

It's also a cleaner design as the retrans scheduler has currently
too many side effects. As a possible downside, the retrans work will
now traverse the subflows list additional times; that does not matter
much, as this is slowpath.

While at it, pick more accurate names for the involved helpers and
explicitly note that the per subflow stale data is under msk socket
lock protection.

The scheduler and the stale logic may observe different subflow
statues, as no subflow lock is acquired. This is intentional and not
harmful, worst case leading to slower retransmissions.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260807-net-next-mptcp-oooq-pruning-v3-2-dbc1eb853cc3@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11 18:35:37 -07:00
Paolo Abeni
789e6a844b mptcp: move the retrans loop to a separate helper
This is a cleanup in order to make the next patch simpler.

No functional change intended.

Tested-by: Gang Yan <yangang@kylinos.cn>
Tested-by: Geliang Tang <geliang@kernel.org>
Acked-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260807-net-next-mptcp-oooq-pruning-v3-1-dbc1eb853cc3@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11 18:35:37 -07:00
Paolo Abeni
41b49a8b91 mptcp: reclaim forward-allocated memory on RX path errors
After commit 9db5b3cec4 ("mptcp: borrow forward memory from subflow"),
errors in the receive path prior to queueing skbs into the receive
queue do not trigger forward-allocated memory reclaiming.

Prevent forward memory from growing unboundedly in pathological drop
scenarios by explicitly reclaiming memory when skbs are dropped.

Fixes: 9db5b3cec4 ("mptcp: borrow forward memory from subflow")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260803-net-mptcp-misc-fixes-7-2-rc6-v2-8-b8f496d71664@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-06 08:46:24 -07:00
Kalpan Jani
bd7aae448f mptcp: fix stale skb->sk reference on subflow close
The backlog list is updated by mptcp_data_ready() under
mptcp_data_lock(). The cleanup of backlog references to a closing
subflow, however, was performed in mptcp_close_ssk(), before
__mptcp_close_ssk() acquires the ssk lock, and while holding neither
the ssk lock nor mptcp_data_lock().

Because that traversal ran without mptcp_data_lock(), concurrent softirq
RX processing on another CPU (subflow_data_ready() -> mptcp_data_ready()
-> __mptcp_add_backlog(), under mptcp_data_lock()) could add a backlog
entry referencing the ssk while the cleanup loop was in progress. Such
an entry could be missed by the cleanup, or the concurrent list update
could corrupt the traversal, leaving skb->sk pointing at the ssk after
it is freed.

A later mptcp_backlog_purge() then dereferences the stale pointer,
triggering a warning in inet_sock_destruct() (ssk->sk_rmem_alloc != 0)
followed by a use-after-free in mptcp_backlog_purge().

Fix this by moving the backlog cleanup into __mptcp_close_ssk(), after
subflow->closing is set to 1 and while the ssk lock is still held,
serialized under mptcp_data_lock(). The cleanup runs only on the push
path (MPTCP_CF_PUSH), where backlog references accumulate; on other
teardown paths the caller already handles cleanup.

With subflow->closing set and mptcp_data_lock() held across the purge,
any concurrent mptcp_data_ready() either completes its enqueue before
the purge runs and is caught, or observes closing=1 and bails out. Once
mptcp_data_unlock() is reached, no new skb referencing the ssk can be
enqueued, so the cleanup is exhaustive.

Remove the unprotected traversal from mptcp_close_ssk() entirely.

Fixes: ee458a3f31 ("mptcp: introduce mptcp-level backlog")
Cc: stable@vger.kernel.org
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Reported-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/621
Signed-off-by: Kalpan Jani <kalpan.jani@mpiricsoftware.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260722-net-mptcp-misc-fixes-7-2-rc5-v1-3-6fb595bc86ef@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-07-23 10:50:38 -07:00
Chenguang Zhao
f3ca0ee2cc mptcp: decrement subflows counter on failed passive join
mptcp_pm_allow_new_subflow() increments extra_subflows before
__mptcp_finish_join() on the passive MP_JOIN path.

In case of race conditions, the subflow is dropped without calling
mptcp_close_ssk(), so the counter is not rolled back.

Call mptcp_pm_close_subflow() when the join completion fails to
decrement the subflows counter.

Fixes: 10f6d46c94 ("mptcp: fix race between MP_JOIN and close")
Cc: stable@vger.kernel.org
Signed-off-by: Chenguang Zhao <zhaochenguang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260722-net-mptcp-misc-fixes-7-2-rc5-v1-1-6fb595bc86ef@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-07-23 10:50:38 -07:00
Gang Yan
c378b1a6f8 mptcp: check desc->count in read_sock
__tcp_read_sock() checks desc->count after each skb is consumed and
breaks the loop when it reaches 0. The MPTCP variant lacks this check.

This is a functional bug, other subsystems also rely on this check:
TLS strparser sets desc->count to 0 once a full TLS record is assembled
and depends on this break to stop reading.

Add the same desc->count check to __mptcp_read_sock(), mirroring
__tcp_read_sock().

Fixes: 250d9766a9 ("mptcp: implement .read_sock")
Cc: stable@vger.kernel.org
Co-developed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Gang Yan <yangang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260602-net-mptcp-misc-fixes-7-1-rc7-v2-9-856831229976@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-06-03 19:04:26 -07:00
Paolo Abeni
d1918b36ed mptcp: fix retransmission loop when csum is enabled
Sashiko noted that retransmission with csum enabled can actually
transmit new data, but currently the relevant code does not update
accordingly snd_nxt.

The may cause incoming ack drop and an endless retransmission loop.

Address the issue incrementing snd_nxt as needed.

Fixes: 4e14867d5e ("mptcp: tune re-injections for csum enabled mode")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260602-net-mptcp-misc-fixes-7-1-rc7-v2-2-856831229976@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-06-03 19:04:25 -07:00
Paolo Abeni
9d8d28738f mptcp: fix missing wakeups in edge scenarios
The mptcp_recvmsg() can fill MPTCP socket receive queue via
mptcp_move_skbs(), but currently does not try to wakeup any listener,
because the same process is going to check the receive queue soon.

When multiple threads are reading from the same fd, the above can
cause stall. Add the missing wakeup.

Fixes: 6771bfd9ee ("mptcp: update mptcp ack sequence from work queue")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260602-net-mptcp-misc-fixes-7-1-rc7-v2-1-856831229976@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-06-03 19:04:25 -07:00
Paolo Abeni
0981f90e1a mptcp: reset rcv wnd on disconnect
If the MPTCP socket fallback to TCP before the MP handshake completion,
the IASN remain 0, and the rcv_wnd_sent field is not explicitly
initialized, just incremented over time with the data transfer.

At disconnect time such value is not cleared. If the next connection falls
back to TCP before the MP handshake completion, the data transfer will
keep incrementing the receive window end sequence starting from the last
value used in the previous connection: the announced window will be
unrelated from the actual receiver buffer size and likely too big.

Address the issue zeroing the field at disconnect time.

Fixes: b29fcfb54c ("mptcp: full disconnect implementation")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260515-net-mptcp-misc-fixes-7-1-rc4-v2-4-701e96419f2f@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-05-19 15:36:35 +02:00
Shardul Bankar
50c2d91c5d mptcp: do not drop partial packets
When a packet arrives with map_seq < ack_seq < end_seq, the beginning
of the packet has already been acknowledged but the end contains new
data. Currently the entire packet is dropped as "old data," forcing
the sender to retransmit.

Instead, skip the already-acked bytes by adjusting the skb offset and
enqueue only the new portion. Update bytes_received and ack_seq to
reflect the new data consumed.

A previous attempt at this fix has been sent by Paolo Abeni [1], but had
issues [2]: it also added a zero-window check and changed rcv_wnd_sent
initialization, which caused test regressions. This version addresses
only the partial packet handling without modifying receive window
accounting.

Fixes: ab174ad8ef ("mptcp: move ooo skbs into msk out of order queue.")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/c9b426a4e163aa3c4fe8b80c79f1a610f47ae7d8.1763075056.git.pabeni@redhat.com [1]
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/600 [2]
Signed-off-by: Shardul Bankar <shardul.b@mpiricsoftware.com>
[pabeni@redhat.com: update map]
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260515-net-mptcp-misc-fixes-7-1-rc4-v2-1-701e96419f2f@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-05-19 15:36:35 +02:00
Matthieu Baerts (NGI0)
f14d6e9c36 mptcp: fastclose msk when linger time is 0
The SO_LINGER socket option has been supported for a while with MPTCP
sockets [1], but it didn't cause the equivalent of a TCP reset as
expected when enabled and its time was set to 0. This was causing some
behavioural differences with TCP where some connections were not
promptly stopped as expected.

To fix that, an extra condition is checked at close() time before
sending an MP_FASTCLOSE, the MPTCP equivalent of a TCP reset.

Note that backporting up to [1] will be difficult as more changes are
needed to be able to send MP_FASTCLOSE. It seems better to stop at [2],
which was supposed to already imitate TCP.

Validated with MPTCP packetdrill tests [3].

Fixes: 268b123874 ("mptcp: setsockopt: support SO_LINGER") [1]
Fixes: d21f834855 ("mptcp: use fastclose on more edge scenarios") [2]
Cc: stable@vger.kernel.org
Reported-by: Lance Tuller <lance@lance0.com>
Closes: https://github.com/lance0/xfr/pull/67
Link: https://github.com/multipath-tcp/packetdrill/pull/196 [3]
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260427-net-mptcp-misc-fixes-7-1-rc2-v1-3-7432b7f279fa@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-28 18:36:27 -07:00
Gang Yan
fcf04b1433 mptcp: sync the msk->sndbuf at accept() time
On passive MPTCP connections, the msk sndbuf is not updated correctly.

The root cause is an order issue in the accept path:

- tcp_check_req() -> subflow_syn_recv_sock() -> mptcp_sk_clone_init()
  calls __mptcp_propagate_sndbuf() to copy the ssk sndbuf into msk

- Later, tcp_child_process() -> tcp_init_transfer() ->
  tcp_sndbuf_expand() grows the ssk sndbuf.

So __mptcp_propagate_sndbuf() runs before the ssk sndbuf has been
expanded and the msk ends up with a much smaller sndbuf than the
subflow:

  MPTCP: msk->sndbuf:20480, msk->first->sndbuf:2626560

Fix this by moving the __mptcp_propagate_sndbuf() call from
mptcp_sk_clone_init() -- the ssk sndbuf is not yet finalized there -- to
__mptcp_propagate_sndbuf() at accept() time, when the ssk sndbuf has
been fully expanded by tcp_sndbuf_expand().

Fixes: 8005184fd1 ("mptcp: refactor sndbuf auto-tuning")
Cc: stable@vger.kernel.org
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/602
Signed-off-by: Gang Yan <yangang@kylinos.cn>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260420-net-mptcp-sync-sndbuf-accept-v1-1-e3523e3aeb44@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-04-23 13:20:17 +02:00
Jakub Kicinski
b6e39e4846 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR (net-7.0-rc8).

Conflicts:

net/ipv6/seg6_iptunnel.c
  c3812651b5 ("seg6: separate dst_cache for input and output paths in seg6 lwtunnel")
  78723a62b9 ("seg6: add per-route tunnel source address")
https://lore.kernel.org/adZhwtOYfo-0ImSa@sirena.org.uk

net/ipv4/icmp.c
  fde29fd934 ("ipv4: icmp: fix null-ptr-deref in icmp_build_probe()")
  d98adfbdd5 ("ipv4: drop ipv6_stub usage and use direct function calls")
https://lore.kernel.org/adO3dccqnr6j-BL9@sirena.org.uk

Adjacent changes:

drivers/net/ethernet/stmicro/stmmac/chain_mode.c
  51f4e090b9 ("net: stmmac: fix integer underflow in chain mode")
  6b4286e055 ("net: stmmac: rename STMMAC_GET_ENTRY() -> STMMAC_NEXT_ENTRY()")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-09 13:20:59 -07:00
Paolo Abeni
7272d8131a mptcp: add receive queue awareness in tcp_rcv_space_adjust()
This is the MPTCP counter-part of commit ea33537d82 ("tcp: add receive
queue awareness in tcp_rcv_space_adjust()").

Prior to this commit:

  ESTAB 33165568 0      192.168.255.2:5201 192.168.255.1:53380 \
        skmem:(r33076416,rb33554432,t0,tb91136,f448,w0,o0,bl0,d0)

After:

  ESTAB 3279168 0      192.168.255.2:5201 192.168.255.1]:53042 \
        skmem:(r3190912,rb3719956,t0,tb91136,f1536,w0,o0,bl0,d0)

Same throughput.

Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260407-net-next-mptcp-reduce-rbuf-v2-2-0d1d135bf6f6@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-08 19:32:01 -07:00
Paolo Abeni
d2000361e4 mptcp: better mptcp-level RTT estimator
The current MPTCP-level RTT estimator has several issues. On high speed
links, the MPTCP-level receive buffer auto-tuning happens with a
frequency well above the TCP-level's one. That in turn can cause
excessive/unneeded receive buffer increase.

On such links, the initial rtt_us value is considerably higher than the
actual delay, and the current mptcp_rcv_space_adjust() updates
msk->rcvq_space.rtt_us with a period equal to the such field previous
value. If the initial rtt_us is 40ms, its first update will happen after
40ms, even if the subflows see actual RTT orders of magnitude lower.

Additionally:
- setting the msk RTT to the maximum among all the subflows RTTs makes
  DRS constantly overshooting the rcvbuf size when a subflow has
  considerable higher latency than the other(s).

- during unidirectional bulk transfers with multiple active subflows,
  the TCP-level RTT estimator occasionally sees considerably higher
  value than the real link delay, i.e. when the packet scheduler reacts
  to an incoming ACK on given subflow pushing data on a different
  subflow.

- currently inactive but still open subflows (i.e. switched to backup
  mode) are always considered when computing the msk-level RTT.

Address the all the issues above with a more accurate RTT estimation
strategy: the MPTCP-level RTT is set to the minimum of all the subflows
actually feeding data into the MPTCP receive buffer, using a small
sliding window.

While at it, also use EWMA to compute the msk-level scaling_ratio, to
that MPTCP can avoid traversing the subflow list is
mptcp_rcv_space_adjust().

Use some care to avoid updating msk and ssk level fields too often.

Fixes: a6b118febb ("mptcp: add receive buffer auto-tuning")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260407-net-next-mptcp-reduce-rbuf-v2-1-0d1d135bf6f6@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-08 19:32:00 -07:00
Jiayuan Chen
9b55b25390 mptcp: fix slab-use-after-free in __inet_lookup_established
The ehash table lookups are lockless and rely on
SLAB_TYPESAFE_BY_RCU to guarantee socket memory stability
during RCU read-side critical sections. Both tcp_prot and
tcpv6_prot have their slab caches created with this flag
via proto_register().

However, MPTCP's mptcp_subflow_init() copies tcpv6_prot into
tcpv6_prot_override during inet_init() (fs_initcall, level 5),
before inet6_init() (module_init/device_initcall, level 6) has
called proto_register(&tcpv6_prot). At that point,
tcpv6_prot.slab is still NULL, so tcpv6_prot_override.slab
remains NULL permanently.

This causes MPTCP v6 subflow child sockets to be allocated via
kmalloc (falling into kmalloc-4k) instead of the TCPv6 slab
cache. The kmalloc-4k cache lacks SLAB_TYPESAFE_BY_RCU, so
when these sockets are freed without SOCK_RCU_FREE (which is
cleared for child sockets by design), the memory can be
immediately reused. Concurrent ehash lookups under
rcu_read_lock can then access freed memory, triggering a
slab-use-after-free in __inet_lookup_established.

Fix this by splitting the IPv6-specific initialization out of
mptcp_subflow_init() into a new mptcp_subflow_v6_init(), called
from mptcp_proto_v6_init() before protocol registration. This
ensures tcpv6_prot_override.slab correctly inherits the
SLAB_TYPESAFE_BY_RCU slab cache.

Fixes: b19bc2945b ("mptcp: implement delegated actions")
Cc: stable@vger.kernel.org
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260406031512.189159-1-jiayuan.chen@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-08 19:30:08 -07:00
Geliang Tang
eb477fdd68 tcp: add recv_should_stop helper
Factor out a new helper tcp_recv_should_stop() from tcp_recvmsg_locked()
and tcp_splice_read() to check whether to stop receiving. And use this
helper in mptcp_recvmsg() and mptcp_splice_read() to reduce redundant code.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260403-net-next-mptcp-msg_eor-misc-v1-3-b0b33bea3fed@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-06 19:14:27 -07:00
Gang Yan
7fb2f5f964 mptcp: preserve MSG_EOR semantics in sendmsg path
Extend MPTCP's sendmsg handling to recognize and honor the MSG_EOR flag,
which marks the end of a record for application-level message boundaries.

Data fragments tagged with MSG_EOR are explicitly marked in the
mptcp_data_frag structure and skb context to prevent unintended
coalescing with subsequent data chunks. This ensures the intent of
applications using MSG_EOR is preserved across MPTCP subflows,
maintaining consistent message segmentation behavior.

Signed-off-by: Gang Yan <yangang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260403-net-next-mptcp-msg_eor-misc-v1-2-b0b33bea3fed@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-06 19:14:26 -07:00
Gang Yan
00d46be3c3 mptcp: reduce 'overhead' from u16 to u8
The 'overhead' in struct mptcp_data_frag can safely use u8, as it
represents 'alignment + sizeof(mptcp_data_frag)'. With a maximum
alignment of 7('ALIGN(1, sizeof(long)) - 1'), the overhead is at most
47, well below U8_MAX and validated with BUILD_BUG_ON().

This patch also adds a field named 'unused' for further extensions.

Signed-off-by: Gang Yan <yangang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260403-net-next-mptcp-msg_eor-misc-v1-1-b0b33bea3fed@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-06 19:14:26 -07:00
Jakub Kicinski
8ffb33d770 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR (net-7.0-rc7).

Conflicts:

net/vmw_vsock/af_vsock.c
  b18c833888 ("vsock: initialize child_ns_mode_locked in vsock_net_init()")
  0de607dc4f ("vsock: add G2H fallback for CIDs not owned by H2G transport")

Adjacent changes:

drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
  ceee35e567 ("bnxt_en: Refactor some basic ring setup and adjustment logic")
  57cdfe0dc7 ("bnxt_en: Resize RSS contexts on channel count change")

drivers/net/wireless/intel/iwlwifi/mld/mac80211.c
  4d56037a02 ("wifi: iwlwifi: mld: block EMLSR during TDLS connections")
  687a95d204 ("wifi: iwlwifi: mld: correctly set wifi generation data")

drivers/net/wireless/intel/iwlwifi/mld/scan.h
  b6045c899e ("wifi: iwlwifi: mld: Refactor scan command handling")
  ec66ec6a5a ("wifi: iwlwifi: mld: Fix MLO scan timing")

drivers/net/wireless/intel/iwlwifi/mvm/fw.c
  078df640ef ("wifi: iwlwifi: mld: add support for iwl_mcc_allowed_ap_type_cmd v
2")
  323156c354 ("wifi: iwlwifi: mvm: don't send a 6E related command when not supported")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-02 11:03:13 -07:00
Li Xiasong
5dd8025a49 mptcp: fix soft lockup in mptcp_recvmsg()
syzbot reported a soft lockup in mptcp_recvmsg() [0].

When receiving data with MSG_PEEK | MSG_WAITALL flags, the skb is not
removed from the sk_receive_queue. This causes sk_wait_data() to always
find available data and never perform actual waiting, leading to a soft
lockup.

Fix this by adding a 'last' parameter to track the last peeked skb.
This allows sk_wait_data() to make informed waiting decisions and prevent
infinite loops when MSG_PEEK is used.

[0]:
watchdog: BUG: soft lockup - CPU#2 stuck for 156s! [server:1963]
Modules linked in:
CPU: 2 UID: 0 PID: 1963 Comm: server Not tainted 6.19.0-rc8 #61 PREEMPT(none)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
RIP: 0010:sk_wait_data+0x15/0x190
Code: 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 56 41 55 41 54 49 89 f4 55 48 89 d5 53 48 89 fb <48> 83 ec 30 65 48 8b 05 17 a4 6b 01 48 89 44 24 28 31 c0 65 48 8b
RSP: 0018:ffffc90000603ca0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888102bf0800 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffc90000603d18 RDI: ffff888102bf0800
RBP: 0000000000000000 R08: 0000000000000002 R09: 0000000000000101
R10: 0000000000000000 R11: 0000000000000075 R12: ffffc90000603d18
R13: ffff888102bf0800 R14: ffff888102bf0800 R15: 0000000000000000
FS:  00007f6e38b8c4c0(0000) GS:ffff8881b877e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055aa7bff1680 CR3: 0000000105cbe000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 mptcp_recvmsg+0x547/0x8c0 net/mptcp/protocol.c:2329
 inet_recvmsg+0x11f/0x130 net/ipv4/af_inet.c:891
 sock_recvmsg+0x94/0xc0 net/socket.c:1100
 __sys_recvfrom+0xb2/0x130 net/socket.c:2256
 __x64_sys_recvfrom+0x1f/0x30 net/socket.c:2267
 do_syscall_64+0x59/0x2d0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x76/0x7e arch/x86/entry/entry_64.S:131
RIP: 0033:0x7f6e386a4a1d
Code: 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 8d 05 f1 de 2c 00 41 89 ca 8b 00 85 c0 75 20 45 31 c9 45 31 c0 b8 2d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 6b f3 c3 66 0f 1f 84 00 00 00 00 00 41 56 41
RSP: 002b:00007ffc3c4bb078 EFLAGS: 00000246 ORIG_RAX: 000000000000002d
RAX: ffffffffffffffda RBX: 000000000000861e RCX: 00007f6e386a4a1d
RDX: 00000000000003ff RSI: 00007ffc3c4bb150 RDI: 0000000000000004
RBP: 00007ffc3c4bb570 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000103 R11: 0000000000000246 R12: 00005605dbc00be0
R13: 00007ffc3c4bb650 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Fixes: 8e04ce45a8 ("mptcp: fix MSG_PEEK stream corruption")
Signed-off-by: Li Xiasong <lixiasong1@huawei.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260330120335.659027-1-lixiasong1@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-31 18:58:37 -07:00
Eric Dumazet
8341c989ac net: remove addr_len argument of recvmsg() handlers
Use msg->msg_namelen as a place holder instead of a
temporary variable, notably in inet[6]_recvmsg().

This removes stack canaries and allows tail-calls.

$ scripts/bloat-o-meter -t vmlinux.old vmlinux
add/remove: 0/0 grow/shrink: 2/19 up/down: 26/-532 (-506)
Function                                     old     new   delta
rawv6_recvmsg                                744     767     +23
vsock_dgram_recvmsg                           55      58      +3
vsock_connectible_recvmsg                     50      47      -3
unix_stream_recvmsg                          161     158      -3
unix_seqpacket_recvmsg                        62      59      -3
unix_dgram_recvmsg                            42      39      -3
tcp_recvmsg                                  546     543      -3
mptcp_recvmsg                               1568    1565      -3
ping_recvmsg                                 806     800      -6
tcp_bpf_recvmsg_parser                       983     974      -9
ip_recv_error                                588     576     -12
ipv6_recv_rxpmtu                             442     428     -14
udp_recvmsg                                 1243    1224     -19
ipv6_recv_error                             1046    1024     -22
udpv6_recvmsg                               1487    1461     -26
raw_recvmsg                                  465     437     -28
udp_bpf_recvmsg                             1027     984     -43
sock_common_recvmsg                          103      27     -76
inet_recvmsg                                 257     175     -82
inet6_recvmsg                                257     175     -82
tcp_bpf_recvmsg                              663     568     -95
Total: Before=25143834, After=25143328, chg -0.00%

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260227151120.1346573-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-02 18:17:17 -08:00
Geliang Tang
e5e2e43002 mptcp: allow overridden write_space to be invoked
Future extensions with psock will override their own sk->sk_write_space
callback. This patch ensures that the overridden sk_write_space can be
invoked by MPTCP.

INDIRECT_CALL is used to keep the default path optimised.

Note that sk->sk_write_space was never called directly with MPTCP
sockets, so changing it to sk_stream_write_space in the init, and using
it from mptcp_write_space() is not supposed to change the current
behaviour.

This patch is shared early to ease discussions around future RFC and
avoid confusions with this "fix" that is needed for different future
extensions.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Co-developed-by: Gang Yan <yangang@kylinos.cn>
Signed-off-by: Gang Yan <yangang@kylinos.cn>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260206-net-next-mptcp-write_space-override-v2-1-e0b12be818c6@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-10 19:54:21 -08:00
David Laight
b582090005 mptcp: Change some dubious min_t(int, ...) to min()
There are two:

	min_t(int, xxx, mptcp_wnd_end(msk) - msk->snd_nxt);

Both mptcp_wnd_end(msk) and msk->snd_nxt are u64, their difference
(aka the window size) might be limited to 32 bits - but that isn't
knowable from this code.
So checks being added to min_t() detect the potential discard of
significant bits.

Provided the 'avail_size' and return of mptcp_check_allowed_size()
are changed to an unsigned type (size_t matches the type the caller
uses) both min_t() can be changed to min().

Signed-off-by: David Laight <david.laight.linux@gmail.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
[ wrapped too long lines when declaring mptcp_check_allowed_size() ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260203-net-next-mptcp-misc-feat-6-20-v1-6-31ec8bfc56d1@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-04 18:45:09 -08:00
Paolo Abeni
2002286e68 trace: mptcp: add mptcp_rcvbuf_grow tracepoint
Similar to tcp, provide a new tracepoint to better understand
mptcp_rcv_space_adjust() behavior, which presents many artifacts.

Note that the used format string is so long that I preferred
wrap it, contrary to guidance for quoted strings.

Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260203-net-next-mptcp-misc-feat-6-20-v1-4-31ec8bfc56d1@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-04 18:45:09 -08:00
Paolo Abeni
5c4dcc52c6 mptcp: consolidate rcv space init
MPTCP uses several calls of the mptcp_rcv_space_init() helper to
initialize the receive space, with a catch-up call in
mptcp_rcv_space_adjust().

Drop all the other strictly not needed invocations and move constant
fields initialization at socket init/reset time.

This removes a bit of complexity from mptcp DRS code. No functional
changes intended.

Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260203-net-next-mptcp-misc-feat-6-20-v1-3-31ec8bfc56d1@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-04 18:45:09 -08:00
Paolo Abeni
70274765fe mptcp: fix receive space timestamp initialization
MPTCP initialize the receive buffer stamp in mptcp_rcv_space_init(),
using the provided subflow stamp. Such helper is invoked in several
places; for passive sockets, space init happened at clone time.

In such scenario, MPTCP ends-up accesses the subflow stamp before
its initialization, leading to quite randomic timing for the first
receive buffer auto-tune event, as the timestamp for newly created
subflow is not refreshed there.

Fix the issue moving the stamp initialization out of the mentioned helper,
at the data transfer start, and always using a fresh timestamp.

Fixes: 013e3179db ("mptcp: fix rcv space initialization")
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260203-net-next-mptcp-misc-feat-6-20-v1-2-31ec8bfc56d1@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-04 18:45:09 -08:00
Paolo Abeni
6b32939350 mptcp: do not account for OoO in mptcp_rcvbuf_grow()
MPTCP-level OoOs are physiological when multiple subflows are active
concurrently and will not cause retransmissions nor are caused by
drops.

Accounting for them in mptcp_rcvbuf_grow() causes the rcvbuf slowly
drifting towards tcp_rmem[2].

Remove such accounting. Note that subflows will still account for TCP-level
OoO when the MPTCP-level rcvbuf is propagated.

This also closes a subtle and very unlikely race condition with rcvspace
init; active sockets with user-space holding the msk-level socket lock,
could complete such initialization in the receive callback, after that the
first OoO data reaches the rcvbuf and potentially triggering a divide by
zero Oops.

Fixes: e118cdc34d ("mptcp: rcvbuf auto-tuning improvement")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260203-net-next-mptcp-misc-feat-6-20-v1-1-31ec8bfc56d1@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-04 18:45:08 -08:00
Geliang Tang
22f3bd9bf8 mptcp: implement .splice_read
This patch implements .splice_read interface of mptcp struct proto_ops
as mptcp_splice_read() with reference to tcp_splice_read().

Corresponding to __tcp_splice_read(), __mptcp_splice_read() is defined,
invoking mptcp_read_sock() instead of tcp_read_sock().

mptcp_splice_read() is almost the same as tcp_splice_read(), except for
sock_rps_record_flow().

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260130-net-next-mptcp-splice-v2-4-31332ba70d7f@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-02 18:15:32 -08:00
Geliang Tang
250d9766a9 mptcp: implement .read_sock
Current in-kernel TCP sockets -- i.e. from nvme_tcp_try_recv() -- need
to call .read_sock interface of struct proto_ops, but it's not
implemented in MPTCP.

This patch implements it with reference to __tcp_read_sock() and
__mptcp_recvmsg_mskq().

Corresponding to tcp_recv_skb(), a new helper for MPTCP named
mptcp_recv_skb() is added to peek a skb from sk->sk_receive_queue.

Compared with __mptcp_recvmsg_mskq(), mptcp_read_sock() uses
sk->sk_rcvbuf as the max read length. The LISTEN status is checked
before the while loop, and mptcp_recv_skb() and mptcp_cleanup_rbuf()
are invoked after the loop. In the loop, all flags checks for
__mptcp_recvmsg_mskq() are removed.

Reviewed-by: Hannes Reinecke <hare@kernel.org>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260130-net-next-mptcp-splice-v2-2-31332ba70d7f@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-02 18:15:31 -08:00
Geliang Tang
436510df0c mptcp: add eat_recv_skb helper
This patch extracts the free skb related code in __mptcp_recvmsg_mskq()
into a new helper mptcp_eat_recv_skb().

This new helper will be used in the next patch.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260130-net-next-mptcp-splice-v2-1-31332ba70d7f@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-02 18:15:31 -08:00
Matthieu Baerts (NGI0)
dccf46179d mptcp: only reset subflow errors when propagated
Some subflow socket errors need to be reported to the MPTCP socket: the
initial subflow connect (MP_CAPABLE), and the ones from the fallback
sockets. The others are not propagated.

The issue is that sock_error() was used to retrieve the error, which was
also resetting the sk_err field. Because of that, when notifying the
userspace about subflow close events later on from the MPTCP worker, the
ssk->sk_err field was always 0.

Now, the error (sk_err) is only reset when propagating it to the msk.

Fixes: 15cc104533 ("mptcp: deliver ssk errors to msk")
Cc: stable@vger.kernel.org
Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260127-net-mptcp-dup-nl-events-v1-3-7f71e1bc4feb@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-01-28 20:58:50 -08:00
Matthieu Baerts (NGI0)
280d654324 mptcp: avoid dup SUB_CLOSED events after disconnect
In case of subflow disconnect(), which can also happen with the first
subflow in case of errors like timeout or reset, mptcp_subflow_ctx_reset
will reset most fields from the mptcp_subflow_context structure,
including close_event_done. Then, when another subflow is closed, yet
another SUB_CLOSED event for the disconnected initial subflow is sent.
Because of the previous reset, there are no source address and
destination port.

A solution is then to also check the subflow's local id: it shouldn't be
negative anyway.

Another solution would be not to reset subflow->close_event_done at
disconnect time, but when reused. But then, probably the whole reset
could be done when being reused. Let's not change this logic, similar
to TCP with tcp_disconnect().

Fixes: d82809b6c5 ("mptcp: avoid duplicated SUB_CLOSED events")
Cc: stable@vger.kernel.org
Reported-by: Marco Angaroni <marco.angaroni@italtel.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/603
Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260127-net-mptcp-dup-nl-events-v1-1-7f71e1bc4feb@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-01-28 20:58:50 -08:00