lwn.git/include/net/udp_tunnel.h, branch docs-fixes

ipv6: remove ipv6_stub infrastructure completely

2026-03-29T18:21:24+00:00

As IPv6 is built-in only and there are no more users of ipv6_stub, the ipv6_stub is now entirely obsolete. Remove all the code related to the definition, initialization and usage. Signed-off-by: Fernando Fernandez Mancera Tested-by: Ricardo B. Marlière Link: https://patch.msgid.link/20260325120928.15848-11-fmancera@suse.de Signed-off-by: Jakub Kicinski

net: convert remaining ipv6_stub users to direct function calls

2026-03-29T18:21:23+00:00

As IPv6 is built-in only, the ipv6_stub infrastructure is no longer necessary. Convert remaining ipv6_stub users to make direct function calls. The fallback functions introduced previously will prevent linkage errors when CONFIG_IPV6 is disabled. Signed-off-by: Fernando Fernandez Mancera Tested-by: Ricardo B. Marlière Link: https://patch.msgid.link/20260325120928.15848-9-fmancera@suse.de Signed-off-by: Jakub Kicinski

udp_tunnel: fix NULL deref caused by udp_sock_create6 when CONFIG_IPV6=n

2026-03-19T01:00:07+00:00

When CONFIG_IPV6 is disabled, the udp_sock_create6() function returns 0 (success) without actually creating a socket. Callers such as fou_create() then proceed to dereference the uninitialized socket pointer, resulting in a NULL pointer dereference. The captured NULL deref crash: BUG: kernel NULL pointer dereference, address: 0000000000000018 RIP: 0010:fou_nl_add_doit (net/ipv4/fou_core.c:590 net/ipv4/fou_core.c:764) [...] Call Trace: genl_family_rcv_msg_doit.constprop.0 (net/netlink/genetlink.c:1114) genl_rcv_msg (net/netlink/genetlink.c:1194 net/netlink/genetlink.c:1209) [...] netlink_rcv_skb (net/netlink/af_netlink.c:2550) genl_rcv (net/netlink/genetlink.c:1219) netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344) netlink_sendmsg (net/netlink/af_netlink.c:1894) __sock_sendmsg (net/socket.c:727 (discriminator 1) net/socket.c:742 (discriminator 1)) __sys_sendto (./include/linux/file.h:62 (discriminator 1) ./include/linux/file.h:83 (discriminator 1) net/socket.c:2183 (discriminator 1)) __x64_sys_sendto (net/socket.c:2213 (discriminator 1) net/socket.c:2209 (discriminator 1) net/socket.c:2209 (discriminator 1)) 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 (net/arch/x86/entry/entry_64.S:130) This patch makes udp_sock_create6 return -EPFNOSUPPORT instead, so callers correctly take their error paths. There is only one caller of the vulnerable function and only privileged users can trigger it. Fixes: fd384412e199b ("udp_tunnel: Seperate ipv6 functions into its own file.") Reported-by: Weiming Shi Signed-off-by: Xiang Mei Link: https://patch.msgid.link/20260317010241.1893893-1-xmei5@asu.edu Signed-off-by: Jakub Kicinski

geneve: expose gso partial features for tunnel offload

2026-01-23T19:31:14+00:00

GSO partial features for tunnels do not require any kind of support from the underlying device: we can safely add them to the geneve UDP tunnel. The only point of attention is the skb required features propagation in the device xmit op: partial features must be stripped, except for UDP_TUNNEL*. Keep partial features disabled by default. Signed-off-by: Paolo Abeni Link: https://patch.msgid.link/d851ca8e928cf05d68310bcbaeaa5e9e0b01e058.1769011015.git.pabeni@redhat.com Signed-off-by: Jakub Kicinski

udp_tunnel: fix deadlock in udp_tunnel_nic_set_port_priv()

2025-06-24T23:31:36+00:00

While configuring a vxlan tunnel in a system with a i40e NIC driver, I observe the following deadlock: WARNING: possible recursive locking detected 6.16.0-rc2.net-next-6.16_92d87230d899+ #13 Tainted: G E -------------------------------------------- kworker/u256:4/1125 is trying to acquire lock: ffff88921ab9c8c8 (&utn->lock){+.+.}-{4:4}, at: i40e_udp_tunnel_set_port (/home/pabeni/net-next/include/net/udp_tunnel.h:343 /home/pabeni/net-next/drivers/net/ethernet/intel/i40e/i40e_main.c:13013) i40e but task is already holding lock: ffff88921ab9c8c8 (&utn->lock){+.+.}-{4:4}, at: udp_tunnel_nic_device_sync_work (/home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:739) udp_tunnel other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&utn->lock); lock(&utn->lock); *** DEADLOCK *** May be due to missing lock nesting notation 4 locks held by kworker/u256:4/1125: #0: ffff8892910ca158 ((wq_completion)udp_tunnel_nic){+.+.}-{0:0}, at: process_one_work (/home/pabeni/net-next/kernel/workqueue.c:3213) #1: ffffc900244efd30 ((work_completion)(&utn->work)){+.+.}-{0:0}, at: process_one_work (/home/pabeni/net-next/kernel/workqueue.c:3214) #2: ffffffff9a14e290 (rtnl_mutex){+.+.}-{4:4}, at: udp_tunnel_nic_device_sync_work (/home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:737) udp_tunnel #3: ffff88921ab9c8c8 (&utn->lock){+.+.}-{4:4}, at: udp_tunnel_nic_device_sync_work (/home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:739) udp_tunnel stack backtrace: Hardware name: Dell Inc. PowerEdge R7525/0YHMCJ, BIOS 2.2.5 04/08/2021 i Call Trace: dump_stack_lvl (/home/pabeni/net-next/lib/dump_stack.c:123) print_deadlock_bug (/home/pabeni/net-next/kernel/locking/lockdep.c:3047) validate_chain (/home/pabeni/net-next/kernel/locking/lockdep.c:3901) __lock_acquire (/home/pabeni/net-next/kernel/locking/lockdep.c:5240) lock_acquire.part.0 (/home/pabeni/net-next/kernel/locking/lockdep.c:473 /home/pabeni/net-next/kernel/locking/lockdep.c:5873) __mutex_lock (/home/pabeni/net-next/kernel/locking/mutex.c:604 /home/pabeni/net-next/kernel/locking/mutex.c:747) i40e_udp_tunnel_set_port (/home/pabeni/net-next/include/net/udp_tunnel.h:343 /home/pabeni/net-next/drivers/net/ethernet/intel/i40e/i40e_main.c:13013) i40e udp_tunnel_nic_device_sync_by_port (/home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:230 /home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:249) udp_tunnel __udp_tunnel_nic_device_sync.part.0 (/home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:292) udp_tunnel udp_tunnel_nic_device_sync_work (/home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:742) udp_tunnel process_one_work (/home/pabeni/net-next/kernel/workqueue.c:3243) worker_thread (/home/pabeni/net-next/kernel/workqueue.c:3315 /home/pabeni/net-next/kernel/workqueue.c:3402) kthread (/home/pabeni/net-next/kernel/kthread.c:464) AFAICS all the existing callsites of udp_tunnel_nic_set_port_priv() are already under the utn lock scope, avoid (re-)acquiring it in such a function. Fixes: 1ead7501094c ("udp_tunnel: remove rtnl_lock dependency") Signed-off-by: Paolo Abeni Acked-by: Stanislav Fomichev Link: https://patch.msgid.link/95a827621ec78c12d1564ec3209e549774f9657d.1750675978.git.pabeni@redhat.com Signed-off-by: Jakub Kicinski

udp_tunnel: remove rtnl_lock dependency

2025-06-19T01:53:51+00:00

Drivers that are using ops lock and don't depend on RTNL lock still need to manage it because udp_tunnel's RTNL dependency. Introduce new udp_tunnel_nic_lock and use it instead of rtnl_lock. Drop non-UDP_TUNNEL_NIC_INFO_MAY_SLEEP mode from udp_tunnel infra (udp_tunnel_nic_device_sync_work needs to grab udp_tunnel_nic_lock mutex and might sleep). Cover more places in v4: - netlink - udp_tunnel_notify_add_rx_port (ndo_open) - triggers udp_tunnel_nic_device_sync_work - udp_tunnel_notify_del_rx_port (ndo_stop) - triggers udp_tunnel_nic_device_sync_work - udp_tunnel_get_rx_info (__netdev_update_features) - triggers NETDEV_UDP_TUNNEL_PUSH_INFO - udp_tunnel_drop_rx_info (__netdev_update_features) - triggers NETDEV_UDP_TUNNEL_DROP_INFO - udp_tunnel_nic_reset_ntf (ndo_open) - notifiers - udp_tunnel_nic_netdevice_event, depending on the event: - triggers NETDEV_UDP_TUNNEL_PUSH_INFO - triggers NETDEV_UDP_TUNNEL_DROP_INFO - ethnl_tunnel_info_reply_size - udp_tunnel_nic_set_port_priv (two intel drivers) Cc: Michael Chan Suggested-by: Jakub Kicinski Signed-off-by: Stanislav Fomichev Link: https://patch.msgid.link/20250616162117.287806-4-stfomichev@gmail.com Signed-off-by: Jakub Kicinski

net: ipv6: Add a flags argument to ip6tunnel_xmit(), udp_tunnel6_xmit_skb()

2025-06-18T01:18:45+00:00

ip6tunnel_xmit() erases the contents of the SKB control block. In order to be able to set particular IP6CB flags on the SKB, add a corresponding parameter, and propagate it to udp_tunnel6_xmit_skb() as well. In one of the following patches, VXLAN driver will use this facility to mark packets as subject to IPv6 multicast routing. Signed-off-by: Petr Machata Reviewed-by: Ido Schimmel Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/acb4f9f3e40c3a931236c3af08a720b017fbfbfb.1750113335.git.petrm@nvidia.com Signed-off-by: Jakub Kicinski

net: ipv6: Make udp_tunnel6_xmit_skb() void

2025-06-18T01:18:45+00:00

The function always returns zero, thus the return value does not carry any signal. Just make it void. Most callers already ignore the return value. However: - Refold arguments of the call from sctp_v6_xmit() so that they fit into the 80-column limit. - tipc_udp_xmit() initializes err from the return value, but that should already be always zero at that point. So there's no practical change, but elision of the assignment prompts a couple more tweaks to clean up the function. Signed-off-by: Petr Machata Reviewed-by: Ido Schimmel Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/7facacf9d8ca3ca9391a4aee88160913671b868d.1750113335.git.petrm@nvidia.com Signed-off-by: Jakub Kicinski

net: ipv4: Add a flags argument to iptunnel_xmit(), udp_tunnel_xmit_skb()

2025-06-18T01:18:44+00:00

iptunnel_xmit() erases the contents of the SKB control block. In order to be able to set particular IPCB flags on the SKB, add a corresponding parameter, and propagate it to udp_tunnel_xmit_skb() as well. In one of the following patches, VXLAN driver will use this facility to mark packets as subject to IP multicast routing. Signed-off-by: Petr Machata Reviewed-by: Ido Schimmel Reviewed-by: Nikolay Aleksandrov Acked-by: Antonio Quartulli Link: https://patch.msgid.link/89c9daf9f2dc088b6b92ccebcc929f51742de91f.1750113335.git.petrm@nvidia.com Signed-off-by: Jakub Kicinski

udp: properly deal with xfrm encap and ADDRFORM

2025-04-14T21:29:01+00:00

UDP GRO accounting assumes that the GRO receive callback is always set when the UDP tunnel is enabled, but syzkaller proved otherwise, leading tot the following splat: WARNING: CPU: 0 PID: 5837 at net/ipv4/udp_offload.c:123 udp_tunnel_update_gro_rcv+0x28d/0x4c0 net/ipv4/udp_offload.c:123 Modules linked in: CPU: 0 UID: 0 PID: 5837 Comm: syz-executor850 Not tainted 6.14.0-syzkaller-13320-g420aabef3ab5 #0 PREEMPT(full) Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 RIP: 0010:udp_tunnel_update_gro_rcv+0x28d/0x4c0 net/ipv4/udp_offload.c:123 Code: 00 00 e8 c6 5a 2f f7 48 c1 e5 04 48 8d b5 20 53 c7 9a ba 10 00 00 00 4c 89 ff e8 ce 87 99 f7 e9 ce 00 00 00 e8 a4 5a 2f f7 90 <0f> 0b 90 e9 de fd ff ff bf 01 00 00 00 89 ee e8 cf 5e 2f f7 85 ed RSP: 0018:ffffc90003effa88 EFLAGS: 00010293 RAX: ffffffff8a93fc9c RBX: 0000000000000000 RCX: ffff8880306f9e00 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: ffffffff8a93fabe R09: 1ffffffff20bfb2e R10: dffffc0000000000 R11: fffffbfff20bfb2f R12: ffff88814ef21738 R13: dffffc0000000000 R14: ffff88814ef21778 R15: 1ffff11029de42ef FS: 0000000000000000(0000) GS:ffff888124f96000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f04eec760d0 CR3: 000000000eb38000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: udp_tunnel_cleanup_gro include/net/udp_tunnel.h:205 [inline] udpv6_destroy_sock+0x212/0x270 net/ipv6/udp.c:1829 sk_common_release+0x71/0x2e0 net/core/sock.c:3896 inet_release+0x17d/0x200 net/ipv4/af_inet.c:435 __sock_release net/socket.c:647 [inline] sock_close+0xbc/0x240 net/socket.c:1391 __fput+0x3e9/0x9f0 fs/file_table.c:465 task_work_run+0x251/0x310 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0xa11/0x27f0 kernel/exit.c:953 do_group_exit+0x207/0x2c0 kernel/exit.c:1102 __do_sys_exit_group kernel/exit.c:1113 [inline] __se_sys_exit_group kernel/exit.c:1111 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1111 x64_sys_call+0x26c3/0x26d0 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f04eebfac79 Code: Unable to access opcode bytes at 0x7f04eebfac4f. RSP: 002b:00007fffdcaa34a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f04eebfac79 RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000 RBP: 00007f04eec75270 R08: ffffffffffffffb8 R09: 00007fffdcaa36c8 R10: 0000200000000000 R11: 0000000000000246 R12: 00007f04eec75270 R13: 0000000000000000 R14: 00007f04eec75cc0 R15: 00007f04eebcca70 Address the issue moving the accounting hook into setup_udp_tunnel_sock() and set_xfrm_gro_udp_encap_rcv(), where the GRO callback is actually set. set_xfrm_gro_udp_encap_rcv() is prone to races with IPV6_ADDRFORM, run the relevant setsockopt under the socket lock to ensure using consistent values of sk_family and up->encap_type. Refactor the GRO callback selection code, to make it clear that the function pointer is always initialized. Reported-by: syzbot+8c469a2260132cd095c1@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=8c469a2260132cd095c1 Fixes: 172bf009c18d ("xfrm: Support GRO for IPv4 ESP in UDP encapsulation") Fixes: 5d7f5b2f6b935 ("udp_tunnel: use static call for GRO hooks when possible") Signed-off-by: Paolo Abeni Reviewed-by: Sabrina Dubroca Link: https://patch.msgid.link/92bcdb6899145a9a387c8fa9e3ca656642a43634.1744228733.git.pabeni@redhat.com Signed-off-by: Jakub Kicinski