kernel/linux.git/drivers/net/ovpn/peer.c, branch linux-7.1.y

ovpn: fix race between deleting interface and adding new peer

2026-05-14T14:24:45+00:00

While deleting an existing ovpn interface, there is a very narrow window where adding a new peer via netlink may cause the netdevice to hang and prevent its unregistration. It may happen during ovpn_dellink(), when all existing peers are freed and the device is queued for deregistration, but a CMD_PEER_NEW message comes in adding a new peer that takes again a reference to the netdev. At this point there is no way to release the device because we are under the assumption that all peers were already released. Fix the race condition by releasing all peers in ndo_uninit(), when the netdevice has already been removed from the netdev list. Also ovpn_peer_add() has now an extra check that forces the function to bail out if the device reg_state is not REGISTERED. This way any incoming CMD_PEER_NEW racing with the interface deletion routine will simply stop before adding the peer. Note that the above check happens while holding the netdev_lock to prevent racing netdev state changes. ovpn_dellink() is now empty and can be removed. Reported-by: Hyunwoo Kim Closes: https://lore.kernel.org/netdev/aaVgJ16edTfQkYbx@v4bel/ Suggested-by: Sabrina Dubroca Fixes: 80747caef33d ("ovpn: introduce the ovpn_peer object") Reviewed-by: Sabrina Dubroca Signed-off-by: Antonio Quartulli

ovpn: respect peer refcount in CMD_NEW_PEER error path

2026-05-14T14:24:45+00:00

ovpn_nl_peer_new_doit()'s error path calls ovpn_peer_release() directly rather than ovpn_peer_put(), bypassing the kref. The accompanying comment ("peer was not yet hashed, thus it is not used in any context") holds for UDP but not for TCP. For UDP, the ovpn_socket union uses the .ovpn arm and never points back at a peer; UDP encap_recv looks up peers via the not-yet-populated hashtables, so the new peer is unreachable until ovpn_peer_add() publishes it. For TCP, ovpn_socket_new() sets ovpn_sock->peer and ovpn_tcp_socket_attach() publishes ovpn_sock via rcu_assign_sk_user_data(). From that moment until ovpn_socket_release() detaches in the error path, the TCP fd is fully wired: userspace recvmsg / sendmsg / close / poll on the fd, as well as the strparser-driven ovpn_tcp_rcv() path, can reach the peer through sk_user_data -> ovpn_sock->peer and bump its refcount via ovpn_peer_hold(). ovpn_tcp_socket_wait_finish() (called inside ovpn_socket_release()) drains strparser and the tx work, but does not synchronize with userspace syscall callers that already hold a peer reference. If ovpn_nl_peer_modify() or ovpn_peer_add() returns an error while such a caller is in flight - notably an ovpn_tcp_recvmsg() blocked in __skb_recv_datagram() on peer->tcp.user_queue - the direct ovpn_peer_release() destroys the peer while the caller still holds the reference, and the eventual ovpn_peer_put() from that caller operates on freed memory. Replace the direct destructor call with ovpn_peer_put() so the kref correctly defers destruction until the last reference is dropped. In the common case where no concurrent user is present, behaviour is unchanged: the kref hits zero immediately and ovpn_peer_release_kref() runs the same destructor. With this conversion ovpn_peer_release() has no callers outside peer.c - ovpn_peer_release_kref() in the same translation unit is the only remaining user - so make it static and drop its declaration from peer.h. Fixes: 11851cbd60ea ("ovpn: implement TCP transport") Reviewed-by: Sabrina Dubroca Assisted-by: Claude:claude-opus-4-7 Signed-off-by: David Carlier Signed-off-by: Antonio Quartulli

drivers: net: drop ipv6_stub usage and use 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 all drivers currently utilizing ipv6_stub 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 Reviewed-by: Jason A. Donenfeld Reviewed-by: Antonio Quartulli Reviewed-by: Edward Cree Link: https://patch.msgid.link/20260325120928.15848-7-fmancera@suse.de Signed-off-by: Jakub Kicinski

ovpn: add support for asymmetric peer IDs

2026-03-17T10:09:05+00:00

In order to support the multipeer architecture, upon connection setup each side of a tunnel advertises a unique ID that the other side must include in packets sent to them. Therefore when transmitting a packet, a peer inserts the recipient's advertised ID for that specific tunnel into the peer ID field. When receiving a packet, a peer expects to find its own unique receive ID for that specific tunnel in the peer ID field. Add support for the TX peer ID and embed it into transmitting packets. If no TX peer ID is specified, fallback to using the same peer ID both for RX and TX in order to be compatible with the non-multipeer compliant peers. Cc: horms@kernel.org Cc: donald.hunter@gmail.com Signed-off-by: Ralf Lici Signed-off-by: Antonio Quartulli Reviewed-by: Sabrina Dubroca

ovpn: notify userspace on client float event

2026-03-17T10:08:55+00:00

Send a netlink notification when a client updates its remote UDP endpoint. The notification includes the new IP address, port, and scope ID (for IPv6). Cc: linux-kselftest@vger.kernel.org Cc: horms@kernel.org Cc: shuah@kernel.org Cc: donald.hunter@gmail.com Signed-off-by: Ralf Lici Signed-off-by: Antonio Quartulli Reviewed-by: Sabrina Dubroca

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

ovpn: Replace use of system_wq with system_percpu_wq

2026-02-05T04:41:38+00:00

This patch continues the effort to refactor workqueue APIs, which has begun with the changes introducing new workqueues and a new alloc_workqueue flag: commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq") commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag") The point of the refactoring is to eventually alter the default behavior of workqueues to become unbound by default so that their workload placement is optimized by the scheduler. Before that to happen after a careful review and conversion of each individual case, workqueue users must be converted to the better named new workqueues with no intended behaviour changes: system_wq -> system_percpu_wq system_unbound_wq -> system_dfl_wq This way the old obsolete workqueues (system_wq, system_unbound_wq) can be removed in the future. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Acked-by: Antonio Quartulli Link: https://patch.msgid.link/20251224155006.114824-1-marco.crivellari@suse.com Signed-off-by: Jakub Kicinski

ovpn: ensure sk is still valid during cleanup

2025-06-03T11:08:15+00:00

Removing a peer while userspace attempts to close its transport socket triggers a race condition resulting in the following crash: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000077: 0000 [#1] SMP KASAN KASAN: null-ptr-deref in range [0x00000000000003b8-0x00000000000003bf] CPU: 12 UID: 0 PID: 162 Comm: kworker/12:1 Tainted: G O 6.15.0-rc2-00635-g521139ac3840 #272 PREEMPT(full) Tainted: [O]=OOT_MODULE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-20240910_120124-localhost 04/01/2014 Workqueue: events ovpn_peer_keepalive_work [ovpn] RIP: 0010:ovpn_socket_release+0x23c/0x500 [ovpn] Code: ea 03 80 3c 02 00 0f 85 71 02 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b 64 24 18 49 8d bc 24 be 03 00 00 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 01 38 d0 7c 08 84 d2 0f 85 30 RSP: 0018:ffffc90000c9fb18 EFLAGS: 00010217 RAX: dffffc0000000000 RBX: ffff8881148d7940 RCX: ffffffff817787bb RDX: 0000000000000077 RSI: 0000000000000008 RDI: 00000000000003be RBP: ffffc90000c9fb30 R08: 0000000000000000 R09: fffffbfff0d3e840 R10: ffffffff869f4207 R11: 0000000000000000 R12: 0000000000000000 R13: ffff888115eb9300 R14: ffffc90000c9fbc8 R15: 000000000000000c FS: 0000000000000000(0000) GS:ffff8882b0151000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f37266b6114 CR3: 00000000054a8000 CR4: 0000000000750ef0 PKRU: 55555554 Call Trace: unlock_ovpn+0x8b/0xe0 [ovpn] ovpn_peer_keepalive_work+0xe3/0x540 [ovpn] ? ovpn_peers_free+0x780/0x780 [ovpn] ? lock_acquire+0x56/0x70 ? process_one_work+0x888/0x1740 process_one_work+0x933/0x1740 ? pwq_dec_nr_in_flight+0x10b0/0x10b0 ? move_linked_works+0x12d/0x2c0 ? assign_work+0x163/0x270 worker_thread+0x4d6/0xd90 ? preempt_count_sub+0x4c/0x70 ? process_one_work+0x1740/0x1740 kthread+0x36c/0x710 ? trace_preempt_on+0x8c/0x1e0 ? kthread_is_per_cpu+0xc0/0xc0 ? preempt_count_sub+0x4c/0x70 ? _raw_spin_unlock_irq+0x36/0x60 ? calculate_sigpending+0x7b/0xa0 ? kthread_is_per_cpu+0xc0/0xc0 ret_from_fork+0x3a/0x80 ? kthread_is_per_cpu+0xc0/0xc0 ret_from_fork_asm+0x11/0x20 Modules linked in: ovpn(O) This happens because the peer deletion operation reaches ovpn_socket_release() while ovpn_sock->sock (struct socket *) and its sk member (struct sock *) are still both valid. Here synchronize_rcu() is invoked, after which ovpn_sock->sock->sk becomes NULL, due to the concurrent socket closing triggered from userspace. After having invoked synchronize_rcu(), ovpn_socket_release() will attempt dereferencing ovpn_sock->sock->sk, triggering the crash reported above. The reason for accessing sk is that we need to retrieve its protocol and continue the cleanup routine accordingly. This crash can be easily produced by running openvpn userspace in client mode with `--keepalive 10 20`, while entirely omitting this option on the server side. After 20 seconds ovpn will assume the peer (server) to be dead, will start removing it and will notify userspace. The latter will receive the notification and close the transport socket, thus triggering the crash. To fix the race condition for good, we need to refactor struct ovpn_socket. Since ovpn is always only interested in the sock->sk member (struct sock *) we can directly hold a reference to it, raher than accessing it via its struct socket container. This means changing "struct socket *ovpn_socket->sock" to "struct sock *ovpn_socket->sk". While acquiring a reference to sk, we can increase its refcounter without affecting the socket close()/destroy() notification (which we rely on when userspace closes a socket we are using). By increasing sk's refcounter we know we can dereference it in ovpn_socket_release() without incurring in any race condition anymore. ovpn_socket_release() will ultimately decrease the reference counter. Cc: Oleksandr Natalenko Fixes: 11851cbd60ea ("ovpn: implement TCP transport") Reported-by: Qingfang Deng Closes: https://github.com/OpenVPN/ovpn-net-next/issues/1 Tested-by: Gert Doering Link: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg31575.html Reviewed-by: Michal Swiatkowski Signed-off-by: Antonio Quartulli

ovpn: improve 'no route to host' debug message

2025-05-15T11:09:36+00:00

When debugging a 'no route to host' error it can be beneficial to know the address of the unreachable destination. Print it along the debugging text. While at it, add a missing parenthesis in a different debugging message inside ovpn_peer_endpoints_update(). Signed-off-by: Antonio Quartulli