netdev - [PATCH net-next v8 06/24] ovpn: keep carrier always on

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Message-Id: <20241002-b4-ovpn-v8-6-37ceffcffbde@openvpn.net>
Date: Wed, 02 Oct 2024 11:02:20 +0200
From: Antonio Quartulli <antonio@...nvpn.net>
To: Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
 Paolo Abeni <pabeni@...hat.com>, Donald Hunter <donald.hunter@...il.com>, 
 Antonio Quartulli <antonio@...nvpn.net>, Shuah Khan <shuah@...nel.org>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-kselftest@...r.kernel.org, sd@...asysnail.net, ryazanov.s.a@...il.com, 
 Andrew Lunn <andrew@...n.ch>
Subject: [PATCH net-next v8 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>
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 12f6258f94c8baef855e2ce90cf70380d5af5ca9..87d49b83107aa9c276c5b200ac919965379c99be 100644
--- a/drivers/net/ovpn/main.c
+++ b/drivers/net/ovpn/main.c
@@ -46,6 +46,13 @@ 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;
 }

-- 
2.45.2