netdev - [PATCH net-next v6 07/25] ovpn: keep carrier always on

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Message-ID: <20240827120805.13681-8-antonio@openvpn.net>
Date: Tue, 27 Aug 2024 14:07:47 +0200
From: Antonio Quartulli <antonio@...nvpn.net>
To: netdev@...r.kernel.org
Cc: kuba@...nel.org,
	pabeni@...hat.com,
	ryazanov.s.a@...il.com,
	edumazet@...gle.com,
	andrew@...n.ch,
	sd@...asysnail.net,
	Antonio Quartulli <antonio@...nvpn.net>
Subject: [PATCH net-next v6 07/25] ovpn: keep carrier always on

An ovpn interface will keep carrier always on and let the user
decide when an interface should be considered disconnected.

This way, even if an ovpn interface is not connected to any peer,
it can still retain all IPs and routes and thus prevent any data
leak.

Signed-off-by: Antonio Quartulli <antonio@...nvpn.net>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
---
 drivers/net/ovpn/main.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/ovpn/main.c b/drivers/net/ovpn/main.c
index f22259d76a0c..bcc90307c108 100644
--- a/drivers/net/ovpn/main.c
+++ b/drivers/net/ovpn/main.c
@@ -50,6 +50,13 @@ static void ovpn_struct_free(struct net_device *net)
 
 static int ovpn_net_open(struct net_device *dev)
 {
+	/* ovpn keeps the carrier always on to avoid losing IP or route
+	 * configuration upon disconnection. This way it can prevent leaks
+	 * of traffic outside of the VPN tunnel.
+	 * The user may override this behaviour by tearing down the interface
+	 * manually.
+	 */
+	netif_carrier_on(dev);
 	netif_tx_start_all_queues(dev);
 	return 0;
 }
-- 
2.44.2