[PATCH net-next v8 17/24] ovpn: add support for updating local UDP endpoint

[Antonio Quartulli]

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 <anto...@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 
dfaa4c7c012215b3dcd451b9bd1d7ffce9b1291c..f9d8f1d1827fe67dc4b4e0bba41a5b110bb90819
 100644
--- a/drivers/net/ovpn/peer.c
+++ b/drivers/net/ovpn/peer.c
@@ -418,6 +418,51 @@ struct ovpn_peer *ovpn_peer_get_by_id(struct ovpn_struct 
*ovpn, u32 peer_id)
        return peer;
 }
 
+/**
+ * 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_to_family(skb)) {
+       case AF_INET:
+               if (unlikely(bind->local.ipv4.s_addr != ip_hdr(skb)->daddr)) {
+                       netdev_dbg(peer->ovpn->dev,
+                                  "%s: learning local IPv4 for peer %d (%pI4 
-> %pI4)\n",
+                                  __func__, peer->id, &bind->local.ipv4.s_addr,
+                                  &ip_hdr(skb)->daddr);
+                       bind->local.ipv4.s_addr = ip_hdr(skb)->daddr;
+               }
+               break;
+       case AF_INET6:
+               if (unlikely(!ipv6_addr_equal(&bind->local.ipv6,
+                                             &ipv6_hdr(skb)->daddr))) {
+                       netdev_dbg(peer->ovpn->dev,
+                                  "%s: learning local IPv6 for peer %d (%pI6c 
-> %pI6c\n",
+                                  __func__, 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 
e0d8d1255b837b7ddfdcedc5a56e7e747f13e2c5..6b66e169b33510a794f8f43dff757f0357e3e5de
 100644
--- a/drivers/net/ovpn/peer.h
+++ b/drivers/net/ovpn/peer.h
@@ -159,4 +159,7 @@ bool ovpn_peer_check_by_src(struct ovpn_struct *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