netdev - [PATCH net-next v3 06/24] ovpn: keep carrier always on

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Message-ID: <20240506011637.27272-7-antonio@openvpn.net>
Date: Mon,  6 May 2024 03:16:19 +0200
From: Antonio Quartulli <antonio@...nvpn.net>
To: netdev@...r.kernel.org
Cc: Jakub Kicinski <kuba@...nel.org>,
	Sergey Ryazanov <ryazanov.s.a@...il.com>,
	Paolo Abeni <pabeni@...hat.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Andrew Lunn <andrew@...n.ch>,
	Esben Haabendal <esben@...nix.com>,
	Antonio Quartulli <antonio@...nvpn.net>
Subject: [PATCH net-next v3 06/24] 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>
---
 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 584cd7286aff..cc8a97a1a189 100644
--- a/drivers/net/ovpn/main.c
+++ b/drivers/net/ovpn/main.c
@@ -51,6 +51,13 @@ static int ovpn_net_open(struct net_device *dev)
 		IPV4_DEVCONF_ALL(dev_net(dev), SEND_REDIRECTS) = false;
 	}
 
+	/* 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;
 }
-- 
2.43.2