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ovpn: use datagram_poll_queue for socket readiness in TCP

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openvpn TCP encapsulation uses a custom queue to deliver packets to
userspace. Currently it relies on datagram_poll, which checks
sk_receive_queue, leading to false readiness signals when that queue
contains non-userspace packets.

Switch ovpn_tcp_poll to use datagram_poll_queue with the peer's
user_queue, ensuring poll only signals readiness when userspace data is
actually available. Also refactor ovpn_tcp_poll in order to enforce the
assumption we can make on the lifetime of ovpn_sock and peer.

Fixes: 11851cbd60 ("ovpn: implement TCP transport")
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Signed-off-by: Ralf Lici <ralf@mandelbit.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://patch.msgid.link/20251021100942.195010-4-ralf@mandelbit.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Ralf Lici
2025-10-21 12:09:42 +02:00
committed by Paolo Abeni
parent 0fc3e32c2c
commit efd729408b
1 changed files with 22 additions and 4 deletions
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26
drivers/net/ovpn/tcp.c
View File

@@ -560,16 +560,34 @@ static void ovpn_tcp_close(struct sock *sk, long timeout)
static __poll_t ovpn_tcp_poll(struct file *file, struct socket *sock,
poll_table *wait)
{
__poll_t mask = datagram_poll(file, sock, wait);
struct sk_buff_head *queue = &sock->sk->sk_receive_queue;
struct ovpn_socket *ovpn_sock;
struct ovpn_peer *peer = NULL;
__poll_t mask;
rcu_read_lock();
ovpn_sock = rcu_dereference_sk_user_data(sock->sk);
if (ovpn_sock && ovpn_sock->peer &&
!skb_queue_empty(&ovpn_sock->peer->tcp.user_queue))
mask |= EPOLLIN | EPOLLRDNORM;
/* if we landed in this callback, we expect to have a
* meaningful state. The ovpn_socket lifecycle would
* prevent it otherwise.
*/
if (WARN(!ovpn_sock || !ovpn_sock->peer,
"ovpn: null state in ovpn_tcp_poll!")) {
rcu_read_unlock();
return 0;
}
if (ovpn_peer_hold(ovpn_sock->peer)) {
peer = ovpn_sock->peer;
queue = &peer->tcp.user_queue;
}
rcu_read_unlock();
mask = datagram_poll_queue(file, sock, wait, queue);
if (peer)
ovpn_peer_put(peer);
return mask;
}