[PATCH net-next v18 18/25] ovpn: add support for updating local UDP endpoint

Antonio Quartulli
2025-01-13T09:31:29Z

In case of UDP links, the local endpoint used to communicate with a
given peer may change without a connection restart.

Add support for learning the new address in case of change.

Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
---
drivers/net/ovpn/peer.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
drivers/net/ovpn/peer.h | 3 +++
2 files changed, 48 insertions(+)

diff --git a/drivers/net/ovpn/peer.c b/drivers/net/ovpn/peer.c
index d78726718ec40126c93624310ce627ddbd210816..3055804894a1331243833379631c1d2e6a138238 100644
--- a/drivers/net/ovpn/peer.c
+++ b/drivers/net/ovpn/peer.c
@@ -508,6 +508,51 @@ static void ovpn_peer_remove(struct ovpn_peer *peer,
schedule_work(&peer->remove_work);
}

+/**
+ * ovpn_peer_update_local_endpoint - update local endpoint for peer
+ * @peer: peer to update the endpoint for
+ * @skb: incoming packet to retrieve the destination address (local) from
+ */
+void ovpn_peer_update_local_endpoint(struct ovpn_peer *peer,
+ struct sk_buff *skb)
+{
+ struct ovpn_bind *bind;
+
+ rcu_read_lock();
+ bind = rcu_dereference(peer->bind);
+ if (unlikely(!bind))
+ goto unlock;
+
+ spin_lock_bh(&peer->lock);
+ switch (skb->protocol) {
+ case htons(ETH_P_IP):
+ if (unlikely(bind->local.ipv4.s_addr != ip_hdr(skb)->daddr)) {
+ net_dbg_ratelimited("%s: learning local IPv4 for peer %d (%pI4 -> %pI4)\n",
+ netdev_name(peer->ovpn->dev),
+ peer->id, &bind->local.ipv4.s_addr,
+ &ip_hdr(skb)->daddr);
+ bind->local.ipv4.s_addr = ip_hdr(skb)->daddr;
+ }
+ break;
+ case htons(ETH_P_IPV6):
+ if (unlikely(!ipv6_addr_equal(&bind->local.ipv6,
+ &ipv6_hdr(skb)->daddr))) {
+ net_dbg_ratelimited("%s: learning local IPv6 for peer %d (%pI6c -> %pI6c\n",
+ netdev_name(peer->ovpn->dev),
+ peer->id, &bind->local.ipv6,
+ &ipv6_hdr(skb)->daddr);
+ bind->local.ipv6 = ipv6_hdr(skb)->daddr;
+ }
+ break;
+ default:
+ break;
+ }
+ spin_unlock_bh(&peer->lock);
+
+unlock:
+ rcu_read_unlock();
+}
+
/**
* ovpn_peer_get_by_dst - Lookup peer to send skb to
* @ovpn: the private data representing the current VPN session
diff --git a/drivers/net/ovpn/peer.h b/drivers/net/ovpn/peer.h
index c69774877c84f0f335fc7ab8fc5da0c555c0794c..ebe7ef12ff9b63d4eabefcfed1e89454aa2f96a4 100644
--- a/drivers/net/ovpn/peer.h
+++ b/drivers/net/ovpn/peer.h
@@ -154,4 +154,7 @@ bool ovpn_peer_check_by_src(struct ovpn_priv *ovpn, struct sk_buff *skb,
void ovpn_peer_keepalive_set(struct ovpn_peer *peer, u32 interval, u32 timeout);
void ovpn_peer_keepalive_work(struct work_struct *work);

+void ovpn_peer_update_local_endpoint(struct ovpn_peer *peer,
+ struct sk_buff *skb);
+
#endif /* _NET_OVPN_OVPNPEER_H_ */

--
2.45.2