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

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

mptcp: sysctl: add available_path_managers

2025-03-20T09:14:49Z

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

mptcp: sysctl: set path manager by name

2025-03-20T09:14:48Z

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

mptcp: pm: register in-kernel and userspace PM

2025-03-20T09:14:48Z

This patch defines the original in-kernel netlink path manager as a new struct mptcp_pm_ops named "mptcp_pm_kernel", and register it in mptcp_pm_kernel_register(). And define the userspace path manager as a new struct mptcp_pm_ops named "mptcp_pm_userspace", and register it in mptcp_pm_init(). To ensure that there's always a valid path manager available, the default path manager "mptcp_pm_kernel" will be skipped in mptcp_pm_unregister(). Signed-off-by: Geliang Tang Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250313-net-next-mptcp-pm-ops-intro-v1-7-f4e4a88efc50@kernel.org Signed-off-by: Paolo Abeni

mptcp: pm: define struct mptcp_pm_ops

2025-03-20T09:14:48Z

In order to allow users to develop their own BPF-based path manager, this patch defines a struct ops "mptcp_pm_ops" for an MPTCP path manager, which contains a set of interfaces. Currently only init() and release() interfaces are included, subsequent patches will add others step by step. Add a set of functions to register, unregister, find and validate a given path manager struct ops. "list" is used to add this path manager to mptcp_pm_list list when it is registered. "name" is used to identify this path manager. mptcp_pm_find() uses "name" to find a path manager on the list. mptcp_pm_unregister is not used in this set, but will be invoked in .unreg of struct bpf_struct_ops. mptcp_pm_validate() will be invoked in .validate of struct bpf_struct_ops. That's why they are exported. Signed-off-by: Geliang Tang Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250313-net-next-mptcp-pm-ops-intro-v1-6-f4e4a88efc50@kernel.org Signed-off-by: Paolo Abeni

mptcp: pm: add struct_group in mptcp_pm_data

2025-03-20T09:14:48Z

This patch adds a "struct_group(reset, ...)" in struct mptcp_pm_data to simplify the reset, and make sure we don't miss any. Suggested-by: Matthieu Baerts Signed-off-by: Geliang Tang Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250313-net-next-mptcp-pm-ops-intro-v1-5-f4e4a88efc50@kernel.org Signed-off-by: Paolo Abeni

mptcp: pm: split netlink and in-kernel init

2025-03-20T09:14:48Z

The registration of mptcp_genl_family is useful for both the in-kernel and the userspace PM. It should then be done in pm_netlink.c. On the other hand, the registration of the in-kernel pernet subsystem is specific to the in-kernel PM, and should stay there in pm_kernel.c. Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250313-net-next-mptcp-pm-ops-intro-v1-1-f4e4a88efc50@kernel.org Signed-off-by: Paolo Abeni

mptcp: pm: move Netlink PM helpers to pm_netlink.c

2025-03-10T20:35:50Z

Before this patch, the PM code was dispersed in different places: - pm.c had common code for all PMs, but also Netlink specific code that will not be needed with the future BPF path-managers. - pm_netlink.c had common Netlink code. To clarify the code, a reorganisation is suggested here, only by moving code around, and small helper renaming to avoid confusions: - pm_netlink.c now only contains common PM Netlink code: - PM events: this code was already there - shared helpers around Netlink code that were already there as well - shared Netlink commands code from pm.c - pm.c now no longer contain Netlink specific code. - protocol.h has been updated accordingly: - mptcp_nl_fill_addr() no longer need to be exported. The code around the PM is now less confusing, which should help for the maintenance in the long term. This will certainly impact future backports, but because other cleanups have already done recently, and more are coming to ease the addition of a new path-manager controlled with BPF (struct_ops), doing that now seems to be a good time. Also, many issues around the PM have been fixed a few months ago while increasing the code coverage in the selftests, so such big reorganisation can be done with more confidence now. 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-v1-15-abef20ada03b@kernel.org Signed-off-by: Jakub Kicinski

mptcp: pm: move generic PM helpers to pm.c

2025-03-10T20:35:50Z

Before this patch, the PM code was dispersed in different places: - pm.c had common code for all PMs - pm_netlink.c was supposed to be about the in-kernel PM, but also had exported common helpers, callbacks used by the different PMs, NL events for PM userspace daemon, etc. quite confusing. - pm_userspace.c had userspace PM only code, but using specific in-kernel PM helpers To clarify the code, a reorganisation is suggested here, only by moving code around, and (un)exporting functions: - helpers used from both PMs and not linked to Netlink - callbacks used by different PMs, e.g. ADD_ADDR management - some helpers have been marked as 'static' - protocol.h has been updated accordingly - (while at it, a needless if before a kfree(), spot by checkpatch in mptcp_remove_anno_list_by_saddr(), has been removed) The code around the PM is now less confusing, which should help for the maintenance in the long term. This will certainly impact future backports, but because other cleanups have already done recently, and more are coming to ease the addition of a new path-manager controlled with BPF (struct_ops), doing that now seems to be a good time. Also, many issues around the PM have been fixed a few months ago while increasing the code coverage in the selftests, so such big reorganisation can be done with more confidence now. 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-v1-13-abef20ada03b@kernel.org Signed-off-by: Jakub Kicinski