kernel.git/net/mptcp/protocol.c, branch linux-6.15.y

mptcp: reset fallback status gracefully at disconnect() time

2025-07-24T06:58:26Z

commit da9b2fc7b73d147d88abe1922de5ab72d72d7756 upstream. mptcp_disconnect() clears the fallback bit unconditionally, without touching the associated flags. The bit clear is safe, as no fallback operation can race with that -- all subflow are already in TCP_CLOSE status thanks to the previous FASTCLOSE -- but we need to consistently reset all the fallback related status. Also acquire the relevant lock, to avoid fouling static analyzers. Fixes: b29fcfb54cd7 ("mptcp: full disconnect implementation") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250714-net-mptcp-fallback-races-v1-3-391aff963322@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

mptcp: plug races between subflow fail and subflow creation

2025-07-24T06:58:26Z

commit def5b7b2643ebba696fc60ddf675dca13f073486 upstream. We have races similar to the one addressed by the previous patch between subflow failing and additional subflow creation. They are just harder to trigger. The solution is similar. Use a separate flag to track the condition 'socket state prevent any additional subflow creation' protected by the fallback lock. The socket fallback makes such flag true, and also receiving or sending an MP_FAIL option. The field 'allow_infinite_fallback' is now always touched under the relevant lock, we can drop the ONCE annotation on write. Fixes: 478d770008b0 ("mptcp: send out MP_FAIL when data checksum fails") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250714-net-mptcp-fallback-races-v1-2-391aff963322@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

mptcp: make fallback action and fallback decision atomic

2025-07-24T06:58:26Z

commit f8a1d9b18c5efc76784f5a326e905f641f839894 upstream. Syzkaller reported the following splat: WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 __mptcp_do_fallback net/mptcp/protocol.h:1223 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_do_fallback net/mptcp/protocol.h:1244 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 check_fully_established net/mptcp/options.c:982 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153 Modules linked in: CPU: 1 UID: 0 PID: 7704 Comm: syz.3.1419 Not tainted 6.16.0-rc3-gbd5ce2324dba #20 PREEMPT(voluntary) Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:__mptcp_do_fallback net/mptcp/protocol.h:1223 [inline] RIP: 0010:mptcp_do_fallback net/mptcp/protocol.h:1244 [inline] RIP: 0010:check_fully_established net/mptcp/options.c:982 [inline] RIP: 0010:mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153 Code: 24 18 e8 bb 2a 00 fd e9 1b df ff ff e8 b1 21 0f 00 e8 ec 5f c4 fc 44 0f b7 ac 24 b0 00 00 00 e9 54 f1 ff ff e8 d9 5f c4 fc 90 <0f> 0b 90 e9 b8 f4 ff ff e8 8b 2a 00 fd e9 8d e6 ff ff e8 81 2a 00 RSP: 0018:ffff8880a3f08448 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8880180a8000 RCX: ffffffff84afcf45 RDX: ffff888090223700 RSI: ffffffff84afdaa7 RDI: 0000000000000001 RBP: ffff888017955780 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8880180a8910 R14: ffff8880a3e9d058 R15: 0000000000000000 FS: 00005555791b8500(0000) GS:ffff88811c495000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c2800b7 CR3: 0000000058e44000 CR4: 0000000000350ef0 Call Trace: tcp_reset+0x26f/0x2b0 net/ipv4/tcp_input.c:4432 tcp_validate_incoming+0x1057/0x1b60 net/ipv4/tcp_input.c:5975 tcp_rcv_established+0x5b5/0x21f0 net/ipv4/tcp_input.c:6166 tcp_v4_do_rcv+0x5dc/0xa70 net/ipv4/tcp_ipv4.c:1925 tcp_v4_rcv+0x3473/0x44a0 net/ipv4/tcp_ipv4.c:2363 ip_protocol_deliver_rcu+0xba/0x480 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x2f1/0x500 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:317 [inline] NF_HOOK include/linux/netfilter.h:311 [inline] ip_local_deliver+0x1be/0x560 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:469 [inline] ip_rcv_finish net/ipv4/ip_input.c:447 [inline] NF_HOOK include/linux/netfilter.h:317 [inline] NF_HOOK include/linux/netfilter.h:311 [inline] ip_rcv+0x514/0x810 net/ipv4/ip_input.c:567 __netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:5975 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6088 process_backlog+0x301/0x1360 net/core/dev.c:6440 __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7453 napi_poll net/core/dev.c:7517 [inline] net_rx_action+0xb44/0x1010 net/core/dev.c:7644 handle_softirqs+0x1d0/0x770 kernel/softirq.c:579 do_softirq+0x3f/0x90 kernel/softirq.c:480 __local_bh_enable_ip+0xed/0x110 kernel/softirq.c:407 local_bh_enable include/linux/bottom_half.h:33 [inline] inet_csk_listen_stop+0x2c5/0x1070 net/ipv4/inet_connection_sock.c:1524 mptcp_check_listen_stop.part.0+0x1cc/0x220 net/mptcp/protocol.c:2985 mptcp_check_listen_stop net/mptcp/mib.h:118 [inline] __mptcp_close+0x9b9/0xbd0 net/mptcp/protocol.c:3000 mptcp_close+0x2f/0x140 net/mptcp/protocol.c:3066 inet_release+0xed/0x200 net/ipv4/af_inet.c:435 inet6_release+0x4f/0x70 net/ipv6/af_inet6.c:487 __sock_release+0xb3/0x270 net/socket.c:649 sock_close+0x1c/0x30 net/socket.c:1439 __fput+0x402/0xb70 fs/file_table.c:465 task_work_run+0x150/0x240 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xd4/0xe0 kernel/entry/common.c:114 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline] do_syscall_64+0x245/0x360 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc92f8a36ad Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffcf52802d8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007ffcf52803a8 RCX: 00007fc92f8a36ad RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007fc92fae7ba0 R08: 0000000000000001 R09: 0000002800000000 R10: 00007fc92f700000 R11: 0000000000000246 R12: 00007fc92fae5fac R13: 00007fc92fae5fa0 R14: 0000000000026d00 R15: 0000000000026c51 irq event stamp: 4068 hardirqs last enabled at (4076): [] __up_console_sem+0x76/0x80 kernel/printk/printk.c:344 hardirqs last disabled at (4085): [] __up_console_sem+0x5b/0x80 kernel/printk/printk.c:342 softirqs last enabled at (3096): [] local_bh_enable include/linux/bottom_half.h:33 [inline] softirqs last enabled at (3096): [] inet_csk_listen_stop+0x2c0/0x1070 net/ipv4/inet_connection_sock.c:1524 softirqs last disabled at (3097): [] do_softirq+0x3f/0x90 kernel/softirq.c:480 Since we need to track the 'fallback is possible' condition and the fallback status separately, there are a few possible races open between the check and the actual fallback action. Add a spinlock to protect the fallback related information and use it close all the possible related races. While at it also remove the too-early clearing of allow_infinite_fallback in __mptcp_subflow_connect(): the field will be correctly cleared by subflow_finish_connect() if/when the connection will complete successfully. If fallback is not possible, as per RFC, reset the current subflow. Since the fallback operation can now fail and return value should be checked, rename the helper accordingly. Fixes: 0530020a7c8f ("mptcp: track and update contiguous data status") Cc: stable@vger.kernel.org Reported-by: Matthieu Baerts Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/570 Reported-by: syzbot+5cf807c20386d699b524@syzkaller.appspotmail.com Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/555 Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250714-net-mptcp-fallback-races-v1-1-391aff963322@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

tcp/dccp: remove icsk->icsk_ack.timeout

2025-03-25T17:34:33Z

icsk->icsk_ack.timeout can be replaced by icsk->csk_delack_timer.expires This saves 8 bytes in TCP/DCCP sockets and helps for better cache locality. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250324203607.703850-3-edumazet@google.com Signed-off-by: Jakub Kicinski

tcp/dccp: remove icsk->icsk_timeout

2025-03-25T17:34:33Z

icsk->icsk_timeout can be replaced by icsk->icsk_retransmit_timer.expires This saves 8 bytes in TCP/DCCP sockets and helps for better cache locality. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250324203607.703850-2-edumazet@google.com Signed-off-by: Jakub Kicinski

mptcp: pm: avoid calling PM specific code from core

2025-03-10T20:35:49Z

When destroying an MPTCP socket, some userspace PM specific code was called from mptcp_destroy_common() in protocol.c. That feels wrong, and it is the only case. Instead, the core now calls mptcp_pm_destroy() from pm.c which is now in charge of cleaning the announced addresses list, and ask the different PMs to do extra cleaning if needed, e.g. the userspace PM, if used, will clean the local addresses list. While at it, the userspace PM specific helper has been prefixed with 'mptcp_userspace_pm_' like the other ones. No behavioural changes intended. Reviewed-by: Geliang Tang Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250307-net-next-mptcp-pm-reorg-v1-9-abef20ada03b@kernel.org Signed-off-by: Jakub Kicinski

mptcp: pm: remove '_nl' from mptcp_pm_nl_work

2025-03-10T20:35:49Z

Currently, in-kernel PM specific helpers are prefixed with 'mptcp_pm_nl_'. But here 'mptcp_pm_nl_work' is not specific to this PM: it is called from the core to call helpers, some of them needed by both the in-kernel and userspace PMs. To avoid confusions, the '_nl' bit has been removed from the name. Also used 'worker' instead of 'work', similar to protocol.c's worker. No behavioural changes intended. Reviewed-by: Geliang Tang Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250307-net-next-mptcp-pm-reorg-v1-4-abef20ada03b@kernel.org Signed-off-by: Jakub Kicinski

net: use sock_kmemdup for ip_options

2025-03-04T01:16:34Z

Instead of using sock_kmalloc() to allocate an ip_options and then immediately duplicate another ip_options to the newly allocated one in ipv6_dup_options(), mptcp_copy_ip_options() and sctp_v4_copy_ip_options(), the newly added sock_kmemdup() helper can be used to simplify the code. Signed-off-by: Geliang Tang Reviewed-by: Kuniyuki Iwashima Acked-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/91ae749d66600ec6fb679e0e518fda6acb5c3e6f.1740735165.git.tanggeliang@kylinos.cn Signed-off-by: Jakub Kicinski

mptcp: micro-optimize __mptcp_move_skb()

2025-02-20T03:05:29Z

After the RX path refactor the mentioned function is expected to run frequently, let's optimize it a bit. Scan for ready subflow from the last processed one, and stop after traversing the list once or reaching the msk memory limit - instead of looking for dubious per-subflow conditions. Also re-order the memory limit checks, to avoid duplicate tests. Signed-off-by: Paolo Abeni Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250218-net-next-mptcp-rx-path-refactor-v1-7-4a47d90d7998@kernel.org Signed-off-by: Jakub Kicinski

mptcp: dismiss __mptcp_rmem()

2025-02-20T03:05:28Z

After the RX path refactor, it become a wrapper for sk_rmem_alloc access, with a slightly misleading name. Just drop it. Signed-off-by: Paolo Abeni Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250218-net-next-mptcp-rx-path-refactor-v1-6-4a47d90d7998@kernel.org Signed-off-by: Jakub Kicinski