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2025-12-23mptcp: ensure context reset on disconnect()Paolo Abeni
After the blamed commit below, if the MPC subflow is already in TCP_CLOSE status or has fallback to TCP at mptcp_disconnect() time, mptcp_do_fastclose() skips setting the `send_fastclose flag` and the later __mptcp_close_ssk() does not reset anymore the related subflow context. Any later connection will be created with both the `request_mptcp` flag and the msk-level fallback status off (it is unconditionally cleared at MPTCP disconnect time), leading to a warning in subflow_data_ready(): WARNING: CPU: 26 PID: 8996 at net/mptcp/subflow.c:1519 subflow_data_ready (net/mptcp/subflow.c:1519 (discriminator 13)) Modules linked in: CPU: 26 UID: 0 PID: 8996 Comm: syz.22.39 Not tainted 6.18.0-rc7-05427-g11fc074f6c36 #1 PREEMPT(voluntary) Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 RIP: 0010:subflow_data_ready (net/mptcp/subflow.c:1519 (discriminator 13)) Code: 90 0f 0b 90 90 e9 04 fe ff ff e8 b7 1e f5 fe 89 ee bf 07 00 00 00 e8 db 19 f5 fe 83 fd 07 0f 84 35 ff ff ff e8 9d 1e f5 fe 90 <0f> 0b 90 e9 27 ff ff ff e8 8f 1e f5 fe 4c 89 e7 48 89 de e8 14 09 RSP: 0018:ffffc9002646fb30 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff88813b218000 RCX: ffffffff825c8435 RDX: ffff8881300b3580 RSI: ffffffff825c8443 RDI: 0000000000000005 RBP: 000000000000000b R08: ffffffff825c8435 R09: 000000000000000b R10: 0000000000000005 R11: 0000000000000007 R12: ffff888131ac0000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f88330af6c0(0000) GS:ffff888a93dd2000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f88330aefe8 CR3: 000000010ff59000 CR4: 0000000000350ef0 Call Trace: <TASK> tcp_data_ready (net/ipv4/tcp_input.c:5356) tcp_data_queue (net/ipv4/tcp_input.c:5445) tcp_rcv_state_process (net/ipv4/tcp_input.c:7165) tcp_v4_do_rcv (net/ipv4/tcp_ipv4.c:1955) __release_sock (include/net/sock.h:1158 (discriminator 6) net/core/sock.c:3180 (discriminator 6)) release_sock (net/core/sock.c:3737) mptcp_sendmsg (net/mptcp/protocol.c:1763 net/mptcp/protocol.c:1857) inet_sendmsg (net/ipv4/af_inet.c:853 (discriminator 7)) __sys_sendto (net/socket.c:727 (discriminator 15) net/socket.c:742 (discriminator 15) net/socket.c:2244 (discriminator 15)) __x64_sys_sendto (net/socket.c:2247) do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1)) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) RIP: 0033:0x7f883326702d Address the issue setting an explicit `fastclosing` flag at fastclose time, and checking such flag after mptcp_do_fastclose(). Fixes: ae155060247b ("mptcp: fix duplicate reset on fastclose") 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/20251212-net-mptcp-subflow_data_ready-warn-v1-2-d1f9fd1c36c8@kernel.org Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-12-23mptcp: fallback earlier on simult connectionPaolo Abeni
Syzkaller reports a simult-connect race leading to inconsistent fallback status: WARNING: CPU: 3 PID: 33 at net/mptcp/subflow.c:1515 subflow_data_ready+0x40b/0x7c0 net/mptcp/subflow.c:1515 Modules linked in: CPU: 3 UID: 0 PID: 33 Comm: ksoftirqd/3 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:subflow_data_ready+0x40b/0x7c0 net/mptcp/subflow.c:1515 Code: 89 ee e8 78 61 3c f6 40 84 ed 75 21 e8 8e 66 3c f6 44 89 fe bf 07 00 00 00 e8 c1 61 3c f6 41 83 ff 07 74 09 e8 76 66 3c f6 90 <0f> 0b 90 e8 6d 66 3c f6 48 89 df e8 e5 ad ff ff 31 ff 89 c5 89 c6 RSP: 0018:ffffc900006cf338 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff888031acd100 RCX: ffffffff8b7f2abf RDX: ffff88801e6ea440 RSI: ffffffff8b7f2aca RDI: 0000000000000005 RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000007 R10: 0000000000000004 R11: 0000000000002c10 R12: ffff88802ba69900 R13: 1ffff920000d9e67 R14: ffff888046f81800 R15: 0000000000000004 FS: 0000000000000000(0000) GS:ffff8880d69bc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000560fc0ca1670 CR3: 0000000032c3a000 CR4: 0000000000352ef0 Call Trace: <TASK> tcp_data_queue+0x13b0/0x4f90 net/ipv4/tcp_input.c:5197 tcp_rcv_state_process+0xfdf/0x4ec0 net/ipv4/tcp_input.c:6922 tcp_v6_do_rcv+0x492/0x1740 net/ipv6/tcp_ipv6.c:1672 tcp_v6_rcv+0x2976/0x41e0 net/ipv6/tcp_ipv6.c:1918 ip6_protocol_deliver_rcu+0x188/0x1520 net/ipv6/ip6_input.c:438 ip6_input_finish+0x1e4/0x4b0 net/ipv6/ip6_input.c:489 NF_HOOK include/linux/netfilter.h:318 [inline] NF_HOOK include/linux/netfilter.h:312 [inline] ip6_input+0x105/0x2f0 net/ipv6/ip6_input.c:500 dst_input include/net/dst.h:471 [inline] ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline] NF_HOOK include/linux/netfilter.h:318 [inline] NF_HOOK include/linux/netfilter.h:312 [inline] ipv6_rcv+0x264/0x650 net/ipv6/ip6_input.c:311 __netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:5979 __netif_receive_skb+0x1d/0x160 net/core/dev.c:6092 process_backlog+0x442/0x15e0 net/core/dev.c:6444 __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7494 napi_poll net/core/dev.c:7557 [inline] net_rx_action+0xa9f/0xfe0 net/core/dev.c:7684 handle_softirqs+0x216/0x8e0 kernel/softirq.c:579 run_ksoftirqd kernel/softirq.c:968 [inline] run_ksoftirqd+0x3a/0x60 kernel/softirq.c:960 smpboot_thread_fn+0x3f7/0xae0 kernel/smpboot.c:160 kthread+0x3c2/0x780 kernel/kthread.c:463 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK> The TCP subflow can process the simult-connect syn-ack packet after transitioning to TCP_FIN1 state, bypassing the MPTCP fallback check, as the sk_state_change() callback is not invoked for * -> FIN_WAIT1 transitions. That will move the msk socket to an inconsistent status and the next incoming data will hit the reported splat. Close the race moving the simult-fallback check at the earliest possible stage - that is at syn-ack generation time. About the fixes tags: [2] was supposed to also fix this issue introduced by [3]. [1] is required as a dependence: it was not explicitly marked as a fix, but it is one and it has already been backported before [3]. In other words, this commit should be backported up to [3], including [2] and [1] if that's not already there. Fixes: 23e89e8ee7be ("tcp: Don't drop SYN+ACK for simultaneous connect().") [1] Fixes: 4fd19a307016 ("mptcp: fix inconsistent state on fastopen race") [2] Fixes: 1e777f39b4d7 ("mptcp: add MSG_FASTOPEN sendmsg flag support") [3] Cc: stable@vger.kernel.org Reported-by: syzbot+0ff6b771b4f7a5bce83b@syzkaller.appspotmail.com Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/586 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/20251212-net-mptcp-subflow_data_ready-warn-v1-1-d1f9fd1c36c8@kernel.org Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-12-08mptcp: avoid deadlock on fallback while reinjectingPaolo Abeni
Jakub reported an MPTCP deadlock at fallback time: WARNING: possible recursive locking detected 6.18.0-rc7-virtme #1 Not tainted -------------------------------------------- mptcp_connect/20858 is trying to acquire lock: ff1100001da18b60 (&msk->fallback_lock){+.-.}-{3:3}, at: __mptcp_try_fallback+0xd8/0x280 but task is already holding lock: ff1100001da18b60 (&msk->fallback_lock){+.-.}-{3:3}, at: __mptcp_retrans+0x352/0xaa0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&msk->fallback_lock); lock(&msk->fallback_lock); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by mptcp_connect/20858: #0: ff1100001da18290 (sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_sendmsg+0x114/0x1bc0 #1: ff1100001db40fd0 (k-sk_lock-AF_INET#2){+.+.}-{0:0}, at: __mptcp_retrans+0x2cb/0xaa0 #2: ff1100001da18b60 (&msk->fallback_lock){+.-.}-{3:3}, at: __mptcp_retrans+0x352/0xaa0 stack backtrace: CPU: 0 UID: 0 PID: 20858 Comm: mptcp_connect Not tainted 6.18.0-rc7-virtme #1 PREEMPT(full) Hardware name: Bochs, BIOS Bochs 01/01/2011 Call Trace: <TASK> dump_stack_lvl+0x6f/0xa0 print_deadlock_bug.cold+0xc0/0xcd validate_chain+0x2ff/0x5f0 __lock_acquire+0x34c/0x740 lock_acquire.part.0+0xbc/0x260 _raw_spin_lock_bh+0x38/0x50 __mptcp_try_fallback+0xd8/0x280 mptcp_sendmsg_frag+0x16c2/0x3050 __mptcp_retrans+0x421/0xaa0 mptcp_release_cb+0x5aa/0xa70 release_sock+0xab/0x1d0 mptcp_sendmsg+0xd5b/0x1bc0 sock_write_iter+0x281/0x4d0 new_sync_write+0x3c5/0x6f0 vfs_write+0x65e/0xbb0 ksys_write+0x17e/0x200 do_syscall_64+0xbb/0xfd0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7fa5627cbc5e Code: 4d 89 d8 e8 14 bd 00 00 4c 8b 5d f8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 11 c9 c3 0f 1f 80 00 00 00 00 48 8b 45 10 0f 05 <c9> c3 83 e2 39 83 fa 08 75 e7 e8 13 ff ff ff 0f 1f 00 f3 0f 1e fa RSP: 002b:00007fff1fe14700 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fa5627cbc5e RDX: 0000000000001f9c RSI: 00007fff1fe16984 RDI: 0000000000000005 RBP: 00007fff1fe14710 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007fff1fe16920 R13: 0000000000002000 R14: 0000000000001f9c R15: 0000000000001f9c The packet scheduler could attempt a reinjection after receiving an MP_FAIL and before the infinite map has been transmitted, causing a deadlock since MPTCP needs to do the reinjection atomically from WRT fallback. Address the issue explicitly avoiding the reinjection in the critical scenario. Note that this is the only fallback critical section that could potentially send packets and hit the double-lock. Reported-by: Jakub Kicinski <kuba@kernel.org> Closes: https://netdev-ctrl.bots.linux.dev/logs/vmksft/mptcp-dbg/results/412720/1-mptcp-join-sh/stderr Fixes: f8a1d9b18c5e ("mptcp: make fallback action and fallback decision atomic") 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/20251205-net-mptcp-misc-fixes-6-19-rc1-v1-4-9e4781a6c1b8@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-12-08mptcp: schedule rtx timer only after pushing dataPaolo Abeni
The MPTCP protocol usually schedule the retransmission timer only when there is some chances for such retransmissions to happen. With a notable exception: __mptcp_push_pending() currently schedule such timer unconditionally, potentially leading to unnecessary rtx timer expiration. The issue is present since the blamed commit below but become easily reproducible after commit 27b0e701d387 ("mptcp: drop bogus optimization in __mptcp_check_push()") Fixes: 33d41c9cd74c ("mptcp: more accurate timeout") 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/20251205-net-mptcp-misc-fixes-6-19-rc1-v1-3-9e4781a6c1b8@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-12-08mptcp: pm: ignore unknown endpoint flagsMatthieu Baerts (NGI0)
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 <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251205-net-mptcp-misc-fixes-6-19-rc1-v1-1-9e4781a6c1b8@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-12-08mptcp: select CRYPTO_LIB_UTILS instead of CRYPTOEric Biggers
Since the only crypto functions used by the mptcp code are the SHA-256 library functions and crypto_memneq(), select only the options needed for those: CRYPTO_LIB_SHA256 and CRYPTO_LIB_UTILS. Previously, CRYPTO was selected instead of CRYPTO_LIB_UTILS. That does pull in CRYPTO_LIB_UTILS as well, but it's unnecessarily broad. Years ago, the CRYPTO_LIB_* options were visible only when CRYPTO. That may be another reason why CRYPTO is selected here. However, that was fixed years ago, and the libraries can now be selected directly. Signed-off-by: Eric Biggers <ebiggers@kernel.org> Reviewed-by: Mat Martineau <martineau@kernel.org> Link: https://patch.msgid.link/20251204054417.491439-1-ebiggers@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-27Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
Conflicts: net/xdp/xsk.c 0ebc27a4c67d ("xsk: avoid data corruption on cq descriptor number") 8da7bea7db69 ("xsk: add indirect call for xsk_destruct_skb") 30ed05adca4a ("xsk: use a smaller new lock for shared pool case") https://lore.kernel.org/20251127105450.4a1665ec@canb.auug.org.au https://lore.kernel.org/eb4eee14-7e24-4d1b-b312-e9ea738fefee@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-27mptcp: Initialise rcv_mss before calling tcp_send_active_reset() in ↵Kuniyuki Iwashima
mptcp_do_fastclose(). syzbot reported divide-by-zero in __tcp_select_window() by MPTCP socket. [0] We had a similar issue for the bare TCP and fixed in commit 499350a5a6e7 ("tcp: initialize rcv_mss to TCP_MIN_MSS instead of 0"). Let's apply the same fix to mptcp_do_fastclose(). [0]: Oops: divide error: 0000 [#1] SMP KASAN PTI CPU: 0 UID: 0 PID: 6068 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:__tcp_select_window+0x824/0x1320 net/ipv4/tcp_output.c:3336 Code: ff ff ff 44 89 f1 d3 e0 89 c1 f7 d1 41 01 cc 41 21 c4 e9 a9 00 00 00 e8 ca 49 01 f8 e9 9c 00 00 00 e8 c0 49 01 f8 44 89 e0 99 <f7> 7c 24 1c 41 29 d4 48 bb 00 00 00 00 00 fc ff df e9 80 00 00 00 RSP: 0018:ffffc90003017640 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88807b469e40 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90003017730 R08: ffff888033268143 R09: 1ffff1100664d028 R10: dffffc0000000000 R11: ffffed100664d029 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 000055557faa0500(0000) GS:ffff888126135000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f64a1912ff8 CR3: 0000000072122000 CR4: 00000000003526f0 Call Trace: <TASK> tcp_select_window net/ipv4/tcp_output.c:281 [inline] __tcp_transmit_skb+0xbc7/0x3aa0 net/ipv4/tcp_output.c:1568 tcp_transmit_skb net/ipv4/tcp_output.c:1649 [inline] tcp_send_active_reset+0x2d1/0x5b0 net/ipv4/tcp_output.c:3836 mptcp_do_fastclose+0x27e/0x380 net/mptcp/protocol.c:2793 mptcp_disconnect+0x238/0x710 net/mptcp/protocol.c:3253 mptcp_sendmsg_fastopen+0x2f8/0x580 net/mptcp/protocol.c:1776 mptcp_sendmsg+0x1774/0x1980 net/mptcp/protocol.c:1855 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0xe5/0x270 net/socket.c:742 __sys_sendto+0x3bd/0x520 net/socket.c:2244 __do_sys_sendto net/socket.c:2251 [inline] __se_sys_sendto net/socket.c:2247 [inline] __x64_sys_sendto+0xde/0x100 net/socket.c:2247 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f66e998f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffff9acedb8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f66e9be5fa0 RCX: 00007f66e998f749 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007ffff9acee10 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007f66e9be5fa0 R14: 00007f66e9be5fa0 R15: 0000000000000006 </TASK> Fixes: ae155060247b ("mptcp: fix duplicate reset on fastclose") Reported-by: syzbot+3a92d359bc2ec6255a33@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/69260882.a70a0220.d98e3.00b4.GAE@google.com/ Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20251125195331.309558-1-kuniyu@google.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-11-26mptcp: clear scheduled subflows on retransmitPaolo Abeni
When __mptcp_retrans() kicks-in, it schedules one or more subflows for retransmission, but such subflows could be actually left alone if there is no more data to retransmit and/or in case of concurrent fallback. Scheduled subflows could be processed much later in time, i.e. when new data will be transmitted, leading to bad subflow selection. Explicitly clear all scheduled subflows before leaving the retransmission function. Fixes: ee2708aedad0 ("mptcp: use get_retrans wrapper") Cc: stable@vger.kernel.org Reported-by: Filip Pokryvka <fpokryvk@redhat.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/20251125-net-mptcp-clear-sched-rtx-v1-1-1cea4ad2165f@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-25tcp: remove icsk->icsk_retransmit_timerEric Dumazet
Now sk->sk_timer is no longer used by TCP keepalive, we can use its storage for TCP and MPTCP retransmit timers for better cache locality. Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com> Link: https://patch.msgid.link/20251124175013.1473655-5-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-25tcp: introduce icsk->icsk_keepalive_timerEric Dumazet
sk->sk_timer has been used for TCP keepalives. Keepalive timers are not in fast path, we want to use sk->sk_timer storage for retransmit timers, for better cache locality. Create icsk->icsk_keepalive_timer and change keepalive code to no longer use sk->sk_timer. Added space is reclaimed in the following patch. This includes changes to MPTCP, which was also using sk_timer. Alias icsk->mptcp_tout_timer and icsk->icsk_keepalive_timer for inet_sk_diag_fill() sake. Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com> Link: https://patch.msgid.link/20251124175013.1473655-4-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-25tcp: rename icsk_timeout() to tcp_timeout_expires()Eric Dumazet
In preparation of sk->tcp_timeout_timer introduction, rename icsk_timeout() helper and change its argument to plain 'const struct sock *sk'. Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com> Link: https://patch.msgid.link/20251124175013.1473655-2-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-25tools: ynl-gen: add regeneration commentAsbjørn Sloth Tønnesen
Add a comment on regeneration to the generated files. The comment is placed after the YNL-GEN line[1], as to not interfere with ynl-regen.sh's detection logic. [1] and after the optional YNL-ARG line. Link: https://lore.kernel.org/r/aR5m174O7pklKrMR@zx2c4.com/ Suggested-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Asbjørn Sloth Tønnesen <ast@fiberby.net> Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251120174429.390574-3-ast@fiberby.net Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-24mptcp: leverage the backlog for RX packet processingPaolo Abeni
When the msk socket is owned or the msk receive buffer is full, move the incoming skbs in a msk level backlog list. This avoid traversing the joined subflows and acquiring the subflow level socket lock at reception time, improving the RX performances. When processing the backlog, use the fwd alloc memory borrowed from the incoming subflow. skbs exceeding the msk receive space are not dropped; instead they are kept into the backlog until the receive buffer is freed. Dropping packets already acked at the TCP level is explicitly discouraged by the RFC and would corrupt the data stream for fallback sockets. Special care is needed to avoid adding skbs to the backlog of a closed msk and to avoid leaving dangling references into the backlog at subflow closing time. 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/20251121-net-next-mptcp-memcg-backlog-imp-v1-14-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-24mptcp: introduce mptcp-level backlogPaolo Abeni
We are soon using it for incoming data processing. MPTCP can't leverage the sk_backlog, as the latter is processed before the release callback, and such callback for MPTCP releases and re-acquire the socket spinlock, breaking the sk_backlog processing assumption. Add a skb backlog list inside the mptcp sock struct, and implement basic helper to transfer packet to and purge such list. Packets in the backlog are memory accounted and still use the incoming subflow receive memory, to allow back-pressure. The backlog size is implicitly bounded to the sum of subflows rcvbuf. When a subflow is closed, references from the backlog to such sock are removed. No packet is currently added to the backlog, so no functional changes intended here. 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/20251121-net-next-mptcp-memcg-backlog-imp-v1-13-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-24mptcp: borrow forward memory from subflowPaolo Abeni
In the MPTCP receive path, we release the subflow allocated fwd memory just to allocate it again shortly after for the msk. That could increases the failures chances, especially when we will add backlog processing, with other actions could consume the just released memory before the msk socket has a chance to do the rcv allocation. Replace the skb_orphan() call with an open-coded variant that explicitly borrows, the fwd memory from the subflow socket instead of releasing it. The borrowed memory does not have PAGE_SIZE granularity; rounding to the page size will make the fwd allocated memory higher than what is strictly required and could make the incoming subflow fwd mem consistently negative. Instead, keep track of the accumulated frag and borrow the full page at subflow close time. This allow removing the last drop in the TCP to MPTCP transition and the associated, now unused, MIB. 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/20251121-net-next-mptcp-memcg-backlog-imp-v1-12-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-24mptcp: handle first subflow closing consistentlyPaolo Abeni
Currently, as soon as the PM closes a subflow, the msk stops accepting data from it, even if the TCP socket could be still formally open in the incoming direction, with the notable exception of the first subflow. The root cause of such behavior is that code currently piggy back two separate semantic on the subflow->disposable bit: the subflow context must be released and that the subflow must stop accepting incoming data. The first subflow is never disposed, so it also never stop accepting incoming data. Use a separate bit to mark the latter status and set such bit in __mptcp_close_ssk() for all subflows. Beyond making per subflow behaviour more consistent this will also simplify the next patch. 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/20251121-net-next-mptcp-memcg-backlog-imp-v1-11-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-24mptcp: drop the __mptcp_data_ready() helperPaolo Abeni
It adds little clarity and there is a single user of such helper, just inline it in the caller. Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Geliang Tang <geliang@kernel.org> Tested-by: Geliang Tang <geliang@kernel.org> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251121-net-next-mptcp-memcg-backlog-imp-v1-10-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-24mptcp: make mptcp_destroy_common() staticPaolo Abeni
Such function is only used inside protocol.c, there is no need to expose it to the whole stack. Note that the function definition most be moved earlier to avoid forward declaration. Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Geliang Tang <geliang@kernel.org> Tested-by: Geliang Tang <geliang@kernel.org> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251121-net-next-mptcp-memcg-backlog-imp-v1-9-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-24mptcp: do not miss early first subflow close event notificationPaolo Abeni
The MPTCP protocol is not currently emitting the NL event when the first subflow is closed before msk accept() time. By replacing the in use close helper is such scenario, implicitly introduce the missing notification. Note that in such scenario we want to be sure that mptcp_close_ssk() will not trigger any PM work, move the msk state change update earlier, so that the previous patch will offer such guarantee. Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Geliang Tang <geliang@kernel.org> Tested-by: Geliang Tang <geliang@kernel.org> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251121-net-next-mptcp-memcg-backlog-imp-v1-8-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-24mptcp: ensure the kernel PM does not take action too latePaolo Abeni
The PM hooks can currently take place when the msk is already shutting down. Subflow creation will fail, thanks to the existing check at join time, but we can entirely avoid starting the to be failed operations. Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Geliang Tang <geliang@kernel.org> Tested-by: Geliang Tang <geliang@kernel.org> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251121-net-next-mptcp-memcg-backlog-imp-v1-7-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-24mptcp: cleanup fallback dummy mapping generationPaolo Abeni
MPTCP currently access ack_seq outside the msk socket log scope to generate the dummy mapping for fallback socket. Soon we are going to introduce backlog usage and even for fallback socket the ack_seq value will be significantly off outside of the msk socket lock scope. Avoid relying on ack_seq for dummy mapping generation, using instead the subflow sequence number. Note that in case of disconnect() and (re)connect() we must ensure that any previous state is re-set. Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Geliang Tang <geliang@kernel.org> Tested-by: Geliang Tang <geliang@kernel.org> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251121-net-next-mptcp-memcg-backlog-imp-v1-6-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-24mptcp: cleanup fallback data fin receptionPaolo Abeni
MPTCP currently generate a dummy data_fin for fallback socket when the fallback subflow has completed data reception using the current ack_seq. We are going to introduce backlog usage for the msk soon, even for fallback sockets: the ack_seq value will not match the most recent sequence number seen by the fallback subflow socket, as it will ignore data_seq sitting in the backlog. Instead use the last map sequence number to set the data_fin, as fallback (dummy) map sequences are always in sequence. Reviewed-by: Geliang Tang <geliang@kernel.org> Tested-by: Geliang Tang <geliang@kernel.org> 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/20251121-net-next-mptcp-memcg-backlog-imp-v1-5-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-24mptcp: fix memcg accounting for passive socketsPaolo Abeni
The passive sockets never got proper memcg accounting: the msk socket is associated with the memcg at accept time, but the passive subflows never got it right. At accept time, traverse the subflows list and associate each of them with the msk memcg, and try to do the same at join completion time, if the msk has been already accepted. Fixes: cf7da0d66cc1 ("mptcp: Create SUBFLOW socket for incoming connections") Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/298 Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/597 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/20251121-net-next-mptcp-memcg-backlog-imp-v1-4-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-24mptcp: grafting MPJ subflow earlierPaolo Abeni
Later patches need to ensure that all MPJ subflows are grafted to the msk socket before accept() completion. Currently the grafting happens under the msk socket lock: potentially at msk release_cb time which make satisfying the above condition a bit tricky. Move the MPJ subflow grafting earlier, under the msk data lock, so that we can use such lock as a synchronization point. 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/20251121-net-next-mptcp-memcg-backlog-imp-v1-3-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-24mptcp: factor-out cgroup data inherit helperPaolo Abeni
MPTCP will soon need the same functionality for passive sockets, factor them out in a common helper. No functional change intended. Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Geliang Tang <geliang@kernel.org> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251121-net-next-mptcp-memcg-backlog-imp-v1-2-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-20Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
Cross-merge networking fixes after downstream PR (net-6.18-rc7). No conflicts, adjacent changes: tools/testing/selftests/net/af_unix/Makefile e1bb28bf13f4 ("selftest: af_unix: Add test for SO_PEEK_OFF.") 45a1cd8346ca ("selftests: af_unix: Add tests for ECONNRESET and EOF semantics") Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-20Merge tag 'net-6.18-rc7' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net Pull networking fixes from Jakub Kicinski: "Including fixes from IPsec and wireless. Previous releases - regressions: - prevent NULL deref in generic_hwtstamp_ioctl_lower(), newer APIs don't populate all the pointers in the request - phylink: add missing supported link modes for the fixed-link - mptcp: fix false positive warning in mptcp_pm_nl_rm_addr Previous releases - always broken: - openvswitch: remove never-working support for setting NSH fields - xfrm: number of fixes for error paths of xfrm_state creation/ modification/deletion - xfrm: fixes for offload - fix the determination of the protocol of the inner packet - don't push locally generated packets directly to L2 tunnel mode offloading, they still need processing from the standard xfrm path - mptcp: fix a couple of corner cases in fallback and fastclose handling - wifi: rtw89: hw_scan: prevent connections from getting stuck, work around apparent bug in FW by tweaking messages we send - af_unix: fix duplicate data if PEEK w/ peek_offset needs to wait - veth: more robust handing of race to avoid txq getting stuck - eth: ps3_gelic_net: handle skb allocation failures" * tag 'net-6.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (47 commits) vsock: Ignore signal/timeout on connect() if already established be2net: pass wrb_params in case of OS2BMC l2tp: reset skb control buffer on xmit net: dsa: microchip: lan937x: Fix RGMII delay tuning selftests: mptcp: add a check for 'add_addr_accepted' mptcp: fix address removal logic in mptcp_pm_nl_rm_addr selftests: mptcp: join: userspace: longer timeout selftests: mptcp: join: endpoints: longer timeout selftests: mptcp: join: fastclose: remove flaky marks mptcp: fix duplicate reset on fastclose mptcp: decouple mptcp fastclose from tcp close mptcp: do not fallback when OoO is present mptcp: fix premature close in case of fallback mptcp: avoid unneeded subflow-level drops mptcp: fix ack generation for fallback msk wifi: rtw89: hw_scan: Don't let the operating channel be last net: phylink: add missing supported link modes for the fixed-link selftest: af_unix: Add test for SO_PEEK_OFF. af_unix: Read sk_peek_offset() again after sleeping in unix_stream_read_generic(). net/mlx5: Clean up only new IRQ glue on request_irq() failure ...
2025-11-19mptcp: fix address removal logic in mptcp_pm_nl_rm_addrGang Yan
Fix inverted WARN_ON_ONCE condition that prevented normal address removal counter updates. The current code only executes decrement logic when the counter is already 0 (abnormal state), while normal removals (counter > 0) are ignored. Signed-off-by: Gang Yan <yangang@kylinos.cn> Fixes: 636113918508 ("mptcp: pm: remove '_nl' from mptcp_pm_nl_rm_addr_received") Cc: stable@vger.kernel.org Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251118-net-mptcp-misc-fixes-6-18-rc6-v1-10-806d3781c95f@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-19mptcp: fix duplicate reset on fastclosePaolo Abeni
The CI reports sporadic failures of the fastclose self-tests. The root cause is a duplicate reset, not carrying the relevant MPTCP option. In the failing scenario the bad reset is received by the peer before the fastclose one, preventing the reception of the latter. Indeed there is window of opportunity at fastclose time for the following race: mptcp_do_fastclose __mptcp_close_ssk __tcp_close() tcp_set_state() [1] tcp_send_active_reset() [2] After [1] the stack will send reset to in-flight data reaching the now closed port. Such reset may race with [2]. Address the issue explicitly sending a single reset on fastclose before explicitly moving the subflow to close status. Fixes: d21f83485518 ("mptcp: use fastclose on more edge scenarios") Cc: stable@vger.kernel.org Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/596 Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Geliang Tang <geliang@kernel.org> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251118-net-mptcp-misc-fixes-6-18-rc6-v1-6-806d3781c95f@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-19mptcp: decouple mptcp fastclose from tcp closePaolo Abeni
With the current fastclose implementation, the mptcp_do_fastclose() helper is in charge of two distinct actions: send the fastclose reset and cleanup the subflows. Formally decouple the two steps, ensuring that mptcp explicitly closes all the subflows after the mentioned helper. This will make the upcoming fix simpler, and allows dropping the 2nd argument from mptcp_destroy_common(). The Fixes tag is then the same as in the next commit to help with the backports. Fixes: d21f83485518 ("mptcp: use fastclose on more edge scenarios") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Geliang Tang <geliang@kernel.org> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251118-net-mptcp-misc-fixes-6-18-rc6-v1-5-806d3781c95f@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-19mptcp: do not fallback when OoO is presentPaolo Abeni
In case of DSS corruption, the MPTCP protocol tries to avoid the subflow reset if fallback is possible. Such corruptions happen in the receive path; to ensure fallback is possible the stack additionally needs to check for OoO data, otherwise the fallback will break the data stream. Fixes: e32d262c89e2 ("mptcp: handle consistently DSS corruption") Cc: stable@vger.kernel.org Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/598 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/20251118-net-mptcp-misc-fixes-6-18-rc6-v1-4-806d3781c95f@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-19mptcp: fix premature close in case of fallbackPaolo Abeni
I'm observing very frequent self-tests failures in case of fallback when running on a CONFIG_PREEMPT kernel. The root cause is that subflow_sched_work_if_closed() closes any subflow as soon as it is half-closed and has no incoming data pending. That works well for regular subflows - MPTCP needs bi-directional connectivity to operate on a given subflow - but for fallback socket is race prone. When TCP peer closes the connection before the MPTCP one, subflow_sched_work_if_closed() will schedule the MPTCP worker to gracefully close the subflow, and shortly after will do another schedule to inject and process a dummy incoming DATA_FIN. On CONFIG_PREEMPT kernel, the MPTCP worker can kick-in and close the fallback subflow before subflow_sched_work_if_closed() is able to create the dummy DATA_FIN, unexpectedly interrupting the transfer. Address the issue explicitly avoiding closing fallback subflows on when the peer is only half-closed. Note that, when the subflow is able to create the DATA_FIN before the worker invocation, the worker will change the msk state before trying to close the subflow and will skip the latter operation as the msk will not match anymore the precondition in __mptcp_close_subflow(). Fixes: f09b0ad55a11 ("mptcp: close subflow when receiving TCP+FIN") 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/20251118-net-mptcp-misc-fixes-6-18-rc6-v1-3-806d3781c95f@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-19mptcp: avoid unneeded subflow-level dropsPaolo Abeni
The rcv window is shared among all the subflows. Currently, MPTCP sync the TCP-level rcv window with the MPTCP one at tcp_transmit_skb() time. The above means that incoming data may sporadically observe outdated TCP-level rcv window and being wrongly dropped by TCP. Address the issue checking for the edge condition before queuing the data at TCP level, and eventually syncing the rcv window as needed. Note that the issue is actually present from the very first MPTCP implementation, but backports older than the blamed commit below will range from impossible to useless. Before: $ nstat -n; sleep 1; nstat -z TcpExtBeyondWindow TcpExtBeyondWindow 14 0.0 After: $ nstat -n; sleep 1; nstat -z TcpExtBeyondWindow TcpExtBeyondWindow 0 0.0 Fixes: fa3fe2b15031 ("mptcp: track window announced to peer") 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/20251118-net-mptcp-misc-fixes-6-18-rc6-v1-2-806d3781c95f@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-19mptcp: fix ack generation for fallback mskPaolo Abeni
mptcp_cleanup_rbuf() needs to know the last most recent, mptcp-level rcv_wnd sent, and such information is tracked into the msk->old_wspace field, updated at ack transmission time by mptcp_write_options(). Fallback socket do not add any mptcp options, such helper is never invoked, and msk->old_wspace value remain stale. That in turn makes ack generation at recvmsg() time quite random. Address the issue ensuring mptcp_write_options() is invoked even for fallback sockets, and just update the needed info in such a case. The issue went unnoticed for a long time, as mptcp currently overshots the fallback socket receive buffer autotune significantly. It is going to change in the near future. Fixes: e3859603ba13 ("mptcp: better msk receive window updates") Cc: stable@vger.kernel.org Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/594 Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Geliang Tang <geliang@kernel.org> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251118-net-mptcp-misc-fixes-6-18-rc6-v1-1-806d3781c95f@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-18mptcp: fix a race in mptcp_pm_del_add_timer()Eric Dumazet
mptcp_pm_del_add_timer() can call sk_stop_timer_sync(sk, &entry->add_timer) while another might have free entry already, as reported by syzbot. Add RCU protection to fix this issue. Also change confusing add_timer variable with stop_timer boolean. syzbot report: BUG: KASAN: slab-use-after-free in __timer_delete_sync+0x372/0x3f0 kernel/time/timer.c:1616 Read of size 4 at addr ffff8880311e4150 by task kworker/1:1/44 CPU: 1 UID: 0 PID: 44 Comm: kworker/1:1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Workqueue: events mptcp_worker Call Trace: <TASK> dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xca/0x240 mm/kasan/report.c:482 kasan_report+0x118/0x150 mm/kasan/report.c:595 __timer_delete_sync+0x372/0x3f0 kernel/time/timer.c:1616 sk_stop_timer_sync+0x1b/0x90 net/core/sock.c:3631 mptcp_pm_del_add_timer+0x283/0x310 net/mptcp/pm.c:362 mptcp_incoming_options+0x1357/0x1f60 net/mptcp/options.c:1174 tcp_data_queue+0xca/0x6450 net/ipv4/tcp_input.c:5361 tcp_rcv_established+0x1335/0x2670 net/ipv4/tcp_input.c:6441 tcp_v4_do_rcv+0x98b/0xbf0 net/ipv4/tcp_ipv4.c:1931 tcp_v4_rcv+0x252a/0x2dc0 net/ipv4/tcp_ipv4.c:2374 ip_protocol_deliver_rcu+0x221/0x440 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x3bb/0x6f0 net/ipv4/ip_input.c:239 NF_HOOK+0x30c/0x3a0 include/linux/netfilter.h:318 NF_HOOK+0x30c/0x3a0 include/linux/netfilter.h:318 __netif_receive_skb_one_core net/core/dev.c:6079 [inline] __netif_receive_skb+0x143/0x380 net/core/dev.c:6192 process_backlog+0x31e/0x900 net/core/dev.c:6544 __napi_poll+0xb6/0x540 net/core/dev.c:7594 napi_poll net/core/dev.c:7657 [inline] net_rx_action+0x5f7/0xda0 net/core/dev.c:7784 handle_softirqs+0x22f/0x710 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] __local_bh_enable_ip+0x1a0/0x2e0 kernel/softirq.c:302 mptcp_pm_send_ack net/mptcp/pm.c:210 [inline] mptcp_pm_addr_send_ack+0x41f/0x500 net/mptcp/pm.c:-1 mptcp_pm_worker+0x174/0x320 net/mptcp/pm.c:1002 mptcp_worker+0xd5/0x1170 net/mptcp/protocol.c:2762 process_one_work kernel/workqueue.c:3263 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK> Allocated by task 44: kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 poison_kmalloc_redzone mm/kasan/common.c:400 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:417 kasan_kmalloc include/linux/kasan.h:262 [inline] __kmalloc_cache_noprof+0x1ef/0x6c0 mm/slub.c:5748 kmalloc_noprof include/linux/slab.h:957 [inline] mptcp_pm_alloc_anno_list+0x104/0x460 net/mptcp/pm.c:385 mptcp_pm_create_subflow_or_signal_addr+0xf9d/0x1360 net/mptcp/pm_kernel.c:355 mptcp_pm_nl_fully_established net/mptcp/pm_kernel.c:409 [inline] __mptcp_pm_kernel_worker+0x417/0x1ef0 net/mptcp/pm_kernel.c:1529 mptcp_pm_worker+0x1ee/0x320 net/mptcp/pm.c:1008 mptcp_worker+0xd5/0x1170 net/mptcp/protocol.c:2762 process_one_work kernel/workqueue.c:3263 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Freed by task 6630: kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587 kasan_save_free_info mm/kasan/kasan.h:406 [inline] poison_slab_object mm/kasan/common.c:252 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284 kasan_slab_free include/linux/kasan.h:234 [inline] slab_free_hook mm/slub.c:2523 [inline] slab_free mm/slub.c:6611 [inline] kfree+0x197/0x950 mm/slub.c:6818 mptcp_remove_anno_list_by_saddr+0x2d/0x40 net/mptcp/pm.c:158 mptcp_pm_flush_addrs_and_subflows net/mptcp/pm_kernel.c:1209 [inline] mptcp_nl_flush_addrs_list net/mptcp/pm_kernel.c:1240 [inline] mptcp_pm_nl_flush_addrs_doit+0x593/0xbb0 net/mptcp/pm_kernel.c:1281 genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x846/0xa10 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:742 ____sys_sendmsg+0x508/0x820 net/socket.c:2630 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2684 __sys_sendmsg net/socket.c:2716 [inline] __do_sys_sendmsg net/socket.c:2721 [inline] __se_sys_sendmsg net/socket.c:2719 [inline] __x64_sys_sendmsg+0x1a1/0x260 net/socket.c:2719 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Cc: stable@vger.kernel.org Fixes: 00cfd77b9063 ("mptcp: retransmit ADD_ADDR when timeout") Reported-by: syzbot+2a6fbf0f0530375968df@syzkaller.appspotmail.com Closes: https://lore.kernel.org/691ad3c3.a70a0220.f6df1.0004.GAE@google.com Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Geliang Tang <geliang@kernel.org> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251117100745.1913963-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-14mptcp: fix race condition in mptcp_schedule_work()Eric Dumazet
syzbot reported use-after-free in mptcp_schedule_work() [1] Issue here is that mptcp_schedule_work() schedules a work, then gets a refcount on sk->sk_refcnt if the work was scheduled. This refcount will be released by mptcp_worker(). [A] if (schedule_work(...)) { [B] sock_hold(sk); return true; } Problem is that mptcp_worker() can run immediately and complete before [B] We need instead : sock_hold(sk); if (schedule_work(...)) return true; sock_put(sk); [1] refcount_t: addition on 0; use-after-free. WARNING: CPU: 1 PID: 29 at lib/refcount.c:25 refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:25 Call Trace: <TASK> __refcount_add include/linux/refcount.h:-1 [inline] __refcount_inc include/linux/refcount.h:366 [inline] refcount_inc include/linux/refcount.h:383 [inline] sock_hold include/net/sock.h:816 [inline] mptcp_schedule_work+0x164/0x1a0 net/mptcp/protocol.c:943 mptcp_tout_timer+0x21/0xa0 net/mptcp/protocol.c:2316 call_timer_fn+0x17e/0x5f0 kernel/time/timer.c:1747 expire_timers kernel/time/timer.c:1798 [inline] __run_timers kernel/time/timer.c:2372 [inline] __run_timer_base+0x648/0x970 kernel/time/timer.c:2384 run_timer_base kernel/time/timer.c:2393 [inline] run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2403 handle_softirqs+0x22f/0x710 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0xcf/0x190 kernel/softirq.c:1138 smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Cc: stable@vger.kernel.org Fixes: 3b1d6210a957 ("mptcp: implement and use MPTCP-level retransmission") Reported-by: syzbot+355158e7e301548a1424@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6915b46f.050a0220.3565dc.0028.GAE@google.com/T/#u Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251113103924.3737425-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-13mptcp: Fix proto fallback detection with BPFJiayuan Chen
The sockmap feature allows bpf syscall from userspace, or based on bpf sockops, replacing the sk_prot of sockets during protocol stack processing with sockmap's custom read/write interfaces. ''' tcp_rcv_state_process() syn_recv_sock()/subflow_syn_recv_sock() tcp_init_transfer(BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB) bpf_skops_established <== sockops bpf_sock_map_update(sk) <== call bpf helper tcp_bpf_update_proto() <== update sk_prot ''' When the server has MPTCP enabled but the client sends a TCP SYN without MPTCP, subflow_syn_recv_sock() performs a fallback on the subflow, replacing the subflow sk's sk_prot with the native sk_prot. ''' subflow_syn_recv_sock() subflow_ulp_fallback() subflow_drop_ctx() mptcp_subflow_ops_undo_override() ''' Then, this subflow can be normally used by sockmap, which replaces the native sk_prot with sockmap's custom sk_prot. The issue occurs when the user executes accept::mptcp_stream_accept::mptcp_fallback_tcp_ops(). Here, it uses sk->sk_prot to compare with the native sk_prot, but this is incorrect when sockmap is used, as we may incorrectly set sk->sk_socket->ops. This fix uses the more generic sk_family for the comparison instead. Additionally, this also prevents a WARNING from occurring: result from ./scripts/decode_stacktrace.sh: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 337 at net/mptcp/protocol.c:68 mptcp_stream_accept \ (net/mptcp/protocol.c:4005) Modules linked in: ... PKRU: 55555554 Call Trace: <TASK> do_accept (net/socket.c:1989) __sys_accept4 (net/socket.c:2028 net/socket.c:2057) __x64_sys_accept (net/socket.c:2067) x64_sys_call (arch/x86/entry/syscall_64.c:41) do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) RIP: 0033:0x7f87ac92b83d ---[ end trace 0000000000000000 ]--- Fixes: 0b4f33def7bb ("mptcp: fix tcp fallback crash") Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Cc: <stable@vger.kernel.org> Link: https://patch.msgid.link/20251111060307.194196-3-jiayuan.chen@linux.dev
2025-11-13mptcp: Disallow MPTCP subflows from sockmapJiayuan Chen
The sockmap feature allows bpf syscall from userspace, or based on bpf sockops, replacing the sk_prot of sockets during protocol stack processing with sockmap's custom read/write interfaces. ''' tcp_rcv_state_process() subflow_syn_recv_sock() tcp_init_transfer(BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB) bpf_skops_established <== sockops bpf_sock_map_update(sk) <== call bpf helper tcp_bpf_update_proto() <== update sk_prot ''' Consider two scenarios: 1. When the server has MPTCP enabled and the client also requests MPTCP, the sk passed to the BPF program is a subflow sk. Since subflows only handle partial data, replacing their sk_prot is meaningless and will cause traffic disruption. 2. When the server has MPTCP enabled but the client sends a TCP SYN without MPTCP, subflow_syn_recv_sock() performs a fallback on the subflow, replacing the subflow sk's sk_prot with the native sk_prot. ''' subflow_ulp_fallback() subflow_drop_ctx() mptcp_subflow_ops_undo_override() ''' Subsequently, accept::mptcp_stream_accept::mptcp_fallback_tcp_ops() converts the subflow to plain TCP. For the first case, we should prevent it from being combined with sockmap by setting sk_prot->psock_update_sk_prot to NULL, which will be blocked by sockmap's own flow. For the second case, since subflow_syn_recv_sock() has already restored sk_prot to native tcp_prot/tcpv6_prot, no further action is needed. Fixes: cec37a6e41aa ("mptcp: Handle MP_CAPABLE options for outgoing connections") Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Cc: <stable@vger.kernel.org> Link: https://patch.msgid.link/20251111060307.194196-2-jiayuan.chen@linux.dev
2025-11-04net: Convert proto callbacks from sockaddr to sockaddr_unsizedKees Cook
Convert struct proto pre_connect(), connect(), bind(), and bind_add() callback function prototypes from struct sockaddr to struct sockaddr_unsized. This does not change per-implementation use of sockaddr for passing around an arbitrarily sized sockaddr struct. Those will be addressed in future patches. Additionally removes the no longer referenced struct sockaddr from include/net/inet_common.h. No binary changes expected. Signed-off-by: Kees Cook <kees@kernel.org> Link: https://patch.msgid.link/20251104002617.2752303-5-kees@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-04net: Convert proto_ops connect() callbacks to use sockaddr_unsizedKees Cook
Update all struct proto_ops connect() callback function prototypes from "struct sockaddr *" to "struct sockaddr_unsized *" to avoid lying to the compiler about object sizes. Calls into struct proto handlers gain casts that will be removed in the struct proto conversion patch. No binary changes expected. Signed-off-by: Kees Cook <kees@kernel.org> Link: https://patch.msgid.link/20251104002617.2752303-3-kees@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-04net: Convert proto_ops bind() callbacks to use sockaddr_unsizedKees Cook
Update all struct proto_ops bind() callback function prototypes from "struct sockaddr *" to "struct sockaddr_unsized *" to avoid lying to the compiler about object sizes. Calls into struct proto handlers gain casts that will be removed in the struct proto conversion patch. No binary changes expected. Signed-off-by: Kees Cook <kees@kernel.org> Link: https://patch.msgid.link/20251104002617.2752303-2-kees@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-04mptcp: pm: in kernel: only use fullmesh endp if anyMatthieu Baerts (NGI0)
Our documentation is saying that the in-kernel PM is only using fullmesh endpoints to establish subflows to announced addresses when at least one endpoint has a fullmesh flag. But this was not totally correct: only fullmesh endpoints were used if at least one endpoint *from the same address family as the received ADD_ADDR* has the fullmesh flag. This is confusing, and it seems clearer not to have differences depending on the address family. So, now, when at least one MPTCP endpoint has a fullmesh flag, the local addresses are picked from all fullmesh endpoints, which might be 0 if there are no endpoints for the correct address family. One selftest needs to be adapted for this behaviour change. Reviewed-by: Geliang Tang <geliang@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251101-net-next-mptcp-fm-endp-nb-bind-v1-2-b4166772d6bb@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-04mptcp: pm: in-kernel: record fullmesh endp nbMatthieu Baerts (NGI0)
Instead of iterating over all endpoints, under RCU read lock, just to check if one of them as the fullmesh flag, we can keep a counter of fullmesh endpoint, similar to what is done with the other flags. This counter is now checked, before iterating over all endpoints. Similar to the other counters, this new one is also exposed. A userspace app can then know when it is being used in a fullmesh mode, with potentially (too) many subflows. Reviewed-by: Geliang Tang <geliang@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251101-net-next-mptcp-fm-endp-nb-bind-v1-1-b4166772d6bb@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-10-31Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
Cross-merge networking fixes after downstream PR (net-6.18-rc4). No conflicts, adjacent changes: drivers/net/ethernet/stmicro/stmmac/stmmac_main.c ded9813d17d3 ("net: stmmac: Consider Tx VLAN offload tag length for maxSDU") 26ab9830beab ("net: stmmac: replace has_xxxx with core_type") Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-10-29mptcp: zero window probe mibPaolo Abeni
Explicitly account for MPTCP-level zero windows probe, to catch hopefully earlier issues alike the one addressed by the previous patch. Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Tested-by: Geliang Tang <geliang@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251028-net-mptcp-send-timeout-v1-4-38ffff5a9ec8@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-10-29mptcp: restore window probePaolo Abeni
Since commit 72377ab2d671 ("mptcp: more conservative check for zero probes") the MPTCP-level zero window probe check is always disabled, as the TCP-level write queue always contains at least the newly allocated skb. Refine the relevant check tacking in account that the above condition and that such skb can have zero length. Fixes: 72377ab2d671 ("mptcp: more conservative check for zero probes") Cc: stable@vger.kernel.org Reported-by: Geliang Tang <geliang@kernel.org> Closes: https://lore.kernel.org/d0a814c364e744ca6b836ccd5b6e9146882e8d42.camel@kernel.org Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Tested-by: Geliang Tang <geliang@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251028-net-mptcp-send-timeout-v1-3-38ffff5a9ec8@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-10-29mptcp: fix MSG_PEEK stream corruptionPaolo Abeni
If a MSG_PEEK | MSG_WAITALL read operation consumes all the bytes in the receive queue and recvmsg() need to waits for more data - i.e. it's a blocking one - upon arrival of the next packet the MPTCP protocol will start again copying the oldest data present in the receive queue, corrupting the data stream. Address the issue explicitly tracking the peeked sequence number, restarting from the last peeked byte. Fixes: ca4fb892579f ("mptcp: add MSG_PEEK support") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Geliang Tang <geliang@kernel.org> Tested-by: Geliang Tang <geliang@kernel.org> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251028-net-mptcp-send-timeout-v1-2-38ffff5a9ec8@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-10-29mptcp: drop bogus optimization in __mptcp_check_push()Paolo Abeni
Accessing the transmit queue without owning the msk socket lock is inherently racy, hence __mptcp_check_push() could actually quit early even when there is pending data. That in turn could cause unexpected tx lock and timeout. Dropping the early check avoids the race, implicitly relaying on later tests under the relevant lock. With such change, all the other mptcp_send_head() call sites are now under the msk socket lock and we can additionally drop the now unneeded annotation on the transmit head pointer accesses. Fixes: 6e628cd3a8f7 ("mptcp: use mptcp release_cb for delayed tasks") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Geliang Tang <geliang@kernel.org> Tested-by: Geliang Tang <geliang@kernel.org> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20251028-net-mptcp-send-timeout-v1-1-38ffff5a9ec8@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-10-29tcp: fix too slow tcp_rcvbuf_grow() actionEric Dumazet
While the blamed commits apparently avoided an overshoot, they also limited how fast a sender can increase BDP at each RTT. This is not exactly a revert, we do not add the 16 * tp->advmss cushion we had, and we are keeping the out_of_order_queue contribution. Do the same in mptcp_rcvbuf_grow(). Tested: emulated 50ms rtt (tcp_stream --tcp-tx-delay 50000), cubic 20 second flow. net.ipv4.tcp_rmem set to "4096 131072 67000000" perf record -a -e tcp:tcp_rcvbuf_grow sleep 20 perf script Before: We can see we fail to roughly double RWIN at each RTT. Sender is RWIN limited while CWND is ramping up (before getting tcp_wmem limited). tcp_stream 33793 [010] 825.717525: tcp:tcp_rcvbuf_grow: time=100869 rtt_us=50428 copied=49152 inq=0 space=40960 ooo=0 scaling_ratio=219 rcvbuf=131072 rcv_ssthresh=103970 window_clamp=112128 rcv_wnd=106496 tcp_stream 33793 [010] 825.768966: tcp:tcp_rcvbuf_grow: time=51447 rtt_us=50362 copied=86016 inq=0 space=49152 ooo=0 scaling_ratio=219 rcvbuf=131072 rcv_ssthresh=107474 window_clamp=112128 rcv_wnd=106496 tcp_stream 33793 [010] 825.821539: tcp:tcp_rcvbuf_grow: time=52577 rtt_us=50243 copied=114688 inq=0 space=86016 ooo=0 scaling_ratio=219 rcvbuf=201096 rcv_ssthresh=167377 window_clamp=172031 rcv_wnd=167936 tcp_stream 33793 [010] 825.871781: tcp:tcp_rcvbuf_grow: time=50248 rtt_us=50237 copied=167936 inq=0 space=114688 ooo=0 scaling_ratio=219 rcvbuf=268129 rcv_ssthresh=224722 window_clamp=229375 rcv_wnd=225280 tcp_stream 33793 [010] 825.922475: tcp:tcp_rcvbuf_grow: time=50698 rtt_us=50183 copied=241664 inq=0 space=167936 ooo=0 scaling_ratio=219 rcvbuf=392617 rcv_ssthresh=331217 window_clamp=335871 rcv_wnd=323584 tcp_stream 33793 [010] 825.973326: tcp:tcp_rcvbuf_grow: time=50855 rtt_us=50213 copied=339968 inq=0 space=241664 ooo=0 scaling_ratio=219 rcvbuf=564986 rcv_ssthresh=478674 window_clamp=483327 rcv_wnd=462848 tcp_stream 33793 [010] 826.023970: tcp:tcp_rcvbuf_grow: time=50647 rtt_us=50248 copied=491520 inq=0 space=339968 ooo=0 scaling_ratio=219 rcvbuf=794811 rcv_ssthresh=671778 window_clamp=679935 rcv_wnd=651264 tcp_stream 33793 [010] 826.074612: tcp:tcp_rcvbuf_grow: time=50648 rtt_us=50227 copied=700416 inq=0 space=491520 ooo=0 scaling_ratio=219 rcvbuf=1149124 rcv_ssthresh=974881 window_clamp=983039 rcv_wnd=942080 tcp_stream 33793 [010] 826.125452: tcp:tcp_rcvbuf_grow: time=50845 rtt_us=50225 copied=987136 inq=8192 space=700416 ooo=0 scaling_ratio=219 rcvbuf=1637502 rcv_ssthresh=1392674 window_clamp=1400831 rcv_wnd=1339392 tcp_stream 33793 [010] 826.175698: tcp:tcp_rcvbuf_grow: time=50250 rtt_us=50198 copied=1347584 inq=0 space=978944 ooo=0 scaling_ratio=219 rcvbuf=2288672 rcv_ssthresh=1949729 window_clamp=1957887 rcv_wnd=1945600 tcp_stream 33793 [010] 826.225947: tcp:tcp_rcvbuf_grow: time=50252 rtt_us=50240 copied=1945600 inq=0 space=1347584 ooo=0 scaling_ratio=219 rcvbuf=3150516 rcv_ssthresh=2687010 window_clamp=2695167 rcv_wnd=2691072 tcp_stream 33793 [010] 826.276175: tcp:tcp_rcvbuf_grow: time=50233 rtt_us=50224 copied=2691072 inq=0 space=1945600 ooo=0 scaling_ratio=219 rcvbuf=4548617 rcv_ssthresh=3883041 window_clamp=3891199 rcv_wnd=3887104 tcp_stream 33793 [010] 826.326403: tcp:tcp_rcvbuf_grow: time=50233 rtt_us=50229 copied=3887104 inq=0 space=2691072 ooo=0 scaling_ratio=219 rcvbuf=6291456 rcv_ssthresh=5370482 window_clamp=5382144 rcv_wnd=5373952 tcp_stream 33793 [010] 826.376723: tcp:tcp_rcvbuf_grow: time=50323 rtt_us=50218 copied=5373952 inq=0 space=3887104 ooo=0 scaling_ratio=219 rcvbuf=9087658 rcv_ssthresh=7755537 window_clamp=7774207 rcv_wnd=7757824 tcp_stream 33793 [010] 826.426991: tcp:tcp_rcvbuf_grow: time=50274 rtt_us=50196 copied=7757824 inq=180224 space=5373952 ooo=0 scaling_ratio=219 rcvbuf=12563759 rcv_ssthresh=10729233 window_clamp=10747903 rcv_wnd=10575872 tcp_stream 33793 [010] 826.477229: tcp:tcp_rcvbuf_grow: time=50241 rtt_us=50078 copied=10731520 inq=180224 space=7577600 ooo=0 scaling_ratio=219 rcvbuf=17715667 rcv_ssthresh=15136529 window_clamp=15155199 rcv_wnd=14983168 tcp_stream 33793 [010] 826.527482: tcp:tcp_rcvbuf_grow: time=50258 rtt_us=50153 copied=15138816 inq=360448 space=10551296 ooo=0 scaling_ratio=219 rcvbuf=24667870 rcv_ssthresh=21073410 window_clamp=21102591 rcv_wnd=20766720 tcp_stream 33793 [010] 826.577712: tcp:tcp_rcvbuf_grow: time=50234 rtt_us=50228 copied=21073920 inq=0 space=14778368 ooo=0 scaling_ratio=219 rcvbuf=34550339 rcv_ssthresh=29517041 window_clamp=29556735 rcv_wnd=29519872 tcp_stream 33793 [010] 826.627982: tcp:tcp_rcvbuf_grow: time=50275 rtt_us=50220 copied=29519872 inq=540672 space=21073920 ooo=0 scaling_ratio=219 rcvbuf=49268707 rcv_ssthresh=42090625 window_clamp=42147839 rcv_wnd=41627648 tcp_stream 33793 [010] 826.678274: tcp:tcp_rcvbuf_grow: time=50296 rtt_us=50185 copied=42053632 inq=761856 space=28979200 ooo=0 scaling_ratio=219 rcvbuf=67000000 rcv_ssthresh=57238168 window_clamp=57316406 rcv_wnd=56606720 tcp_stream 33793 [010] 826.728627: tcp:tcp_rcvbuf_grow: time=50357 rtt_us=50128 copied=43913216 inq=851968 space=41291776 ooo=0 scaling_ratio=219 rcvbuf=67000000 rcv_ssthresh=57290728 window_clamp=57316406 rcv_wnd=56524800 tcp_stream 33793 [010] 827.131364: tcp:tcp_rcvbuf_grow: time=50239 rtt_us=50127 copied=43843584 inq=655360 space=43061248 ooo=0 scaling_ratio=219 rcvbuf=67000000 rcv_ssthresh=57290728 window_clamp=57316406 rcv_wnd=56696832 tcp_stream 33793 [010] 827.181613: tcp:tcp_rcvbuf_grow: time=50254 rtt_us=50115 copied=43843584 inq=524288 space=43188224 ooo=0 scaling_ratio=219 rcvbuf=67000000 rcv_ssthresh=57290728 window_clamp=57316406 rcv_wnd=56807424 tcp_stream 33793 [010] 828.339635: tcp:tcp_rcvbuf_grow: time=50283 rtt_us=50110 copied=43843584 inq=458752 space=43319296 ooo=0 scaling_ratio=219 rcvbuf=67000000 rcv_ssthresh=57290728 window_clamp=57316406 rcv_wnd=56864768 tcp_stream 33793 [010] 828.440350: tcp:tcp_rcvbuf_grow: time=50404 rtt_us=50099 copied=43843584 inq=393216 space=43384832 ooo=0 scaling_ratio=219 rcvbuf=67000000 rcv_ssthresh=57290728 window_clamp=57316406 rcv_wnd=56922112 tcp_stream 33793 [010] 829.195106: tcp:tcp_rcvbuf_grow: time=50154 rtt_us=50077 copied=43843584 inq=196608 space=43450368 ooo=0 scaling_ratio=219 rcvbuf=67000000 rcv_ssthresh=57290728 window_clamp=57316406 rcv_wnd=57090048 After: It takes few steps to increase RWIN. Sender is no longer RWIN limited. tcp_stream 50826 [010] 935.634212: tcp:tcp_rcvbuf_grow: time=100788 rtt_us=50315 copied=49152 inq=0 space=40960 ooo=0 scaling_ratio=219 rcvbuf=131072 rcv_ssthresh=103970 window_clamp=112128 rcv_wnd=106496 tcp_stream 50826 [010] 935.685642: tcp:tcp_rcvbuf_grow: time=51437 rtt_us=50361 copied=86016 inq=0 space=49152 ooo=0 scaling_ratio=219 rcvbuf=160875 rcv_ssthresh=132969 window_clamp=137623 rcv_wnd=131072 tcp_stream 50826 [010] 935.738299: tcp:tcp_rcvbuf_grow: time=52660 rtt_us=50256 copied=139264 inq=0 space=86016 ooo=0 scaling_ratio=219 rcvbuf=502741 rcv_ssthresh=411497 window_clamp=430079 rcv_wnd=413696 tcp_stream 50826 [010] 935.788544: tcp:tcp_rcvbuf_grow: time=50249 rtt_us=50233 copied=307200 inq=0 space=139264 ooo=0 scaling_ratio=219 rcvbuf=728690 rcv_ssthresh=618717 window_clamp=623371 rcv_wnd=618496 tcp_stream 50826 [010] 935.838796: tcp:tcp_rcvbuf_grow: time=50258 rtt_us=50202 copied=618496 inq=0 space=307200 ooo=0 scaling_ratio=219 rcvbuf=2450338 rcv_ssthresh=1855709 window_clamp=2096187 rcv_wnd=1859584 tcp_stream 50826 [010] 935.889140: tcp:tcp_rcvbuf_grow: time=50347 rtt_us=50166 copied=1261568 inq=0 space=618496 ooo=0 scaling_ratio=219 rcvbuf=4376503 rcv_ssthresh=3725291 window_clamp=3743961 rcv_wnd=3706880 tcp_stream 50826 [010] 935.939435: tcp:tcp_rcvbuf_grow: time=50300 rtt_us=50185 copied=2478080 inq=24576 space=1261568 ooo=0 scaling_ratio=219 rcvbuf=9082648 rcv_ssthresh=7733731 window_clamp=7769921 rcv_wnd=7692288 tcp_stream 50826 [010] 935.989681: tcp:tcp_rcvbuf_grow: time=50251 rtt_us=50221 copied=4915200 inq=114688 space=2453504 ooo=0 scaling_ratio=219 rcvbuf=16574936 rcv_ssthresh=14108110 window_clamp=14179339 rcv_wnd=14024704 tcp_stream 50826 [010] 936.039967: tcp:tcp_rcvbuf_grow: time=50289 rtt_us=50279 copied=9830400 inq=114688 space=4800512 ooo=0 scaling_ratio=219 rcvbuf=32695050 rcv_ssthresh=27896187 window_clamp=27969593 rcv_wnd=27815936 tcp_stream 50826 [010] 936.090172: tcp:tcp_rcvbuf_grow: time=50211 rtt_us=50200 copied=19841024 inq=114688 space=9715712 ooo=0 scaling_ratio=219 rcvbuf=67000000 rcv_ssthresh=57245176 window_clamp=57316406 rcv_wnd=57163776 tcp_stream 50826 [010] 936.140430: tcp:tcp_rcvbuf_grow: time=50262 rtt_us=50197 copied=39501824 inq=114688 space=19726336 ooo=0 scaling_ratio=219 rcvbuf=67000000 rcv_ssthresh=57245176 window_clamp=57316406 rcv_wnd=57163776 tcp_stream 50826 [010] 936.190527: tcp:tcp_rcvbuf_grow: time=50101 rtt_us=50071 copied=43655168 inq=262144 space=39387136 ooo=0 scaling_ratio=219 rcvbuf=67000000 rcv_ssthresh=57259192 window_clamp=57316406 rcv_wnd=57032704 tcp_stream 50826 [010] 936.240719: tcp:tcp_rcvbuf_grow: time=50197 rtt_us=50057 copied=43843584 inq=262144 space=43393024 ooo=0 scaling_ratio=219 rcvbuf=67000000 rcv_ssthresh=57259192 window_clamp=57316406 rcv_wnd=57032704 tcp_stream 50826 [010] 936.341271: tcp:tcp_rcvbuf_grow: time=50297 rtt_us=50123 copied=43843584 inq=131072 space=43581440 ooo=0 scaling_ratio=219 rcvbuf=67000000 rcv_ssthresh=57259192 window_clamp=57316406 rcv_wnd=57147392 tcp_stream 50826 [010] 936.642503: tcp:tcp_rcvbuf_grow: time=50131 rtt_us=50084 copied=43843584 inq=0 space=43712512 ooo=0 scaling_ratio=219 rcvbuf=67000000 rcv_ssthresh=57259192 window_clamp=57316406 rcv_wnd=57262080 Fixes: 65c5287892e9 ("tcp: fix sk_rcvbuf overshoot") Fixes: e118cdc34dd1 ("mptcp: rcvbuf auto-tuning improvement") Reported-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/589 Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Reviewed-by: Neal Cardwell <ncardwell@google.com> Link: https://patch.msgid.link/20251028-net-tcp-recv-autotune-v3-4-74b43ba4c84c@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
generated by cgit (git 2.34.1) at 2026-01-09 00:38:53 +0000