netdev - [PATCH net 12/12] batman-adv: fix detection of lower link in batadv_get_real

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Date:   Thu,  1 Oct 2020 09:59:36 +0200
From:   Sabrina Dubroca <sd@...asysnail.net>
To:     netdev@...r.kernel.org
Cc:     Sabrina Dubroca <sd@...asysnail.net>,
        Marek Lindner <mareklindner@...mailbox.ch>,
        Simon Wunderlich <sw@...onwunderlich.de>,
        Antonio Quartulli <a@...table.cc>,
        Sven Eckelmann <sven@...fation.org>,
        b.a.t.m.a.n@...ts.open-mesh.org
Subject: [PATCH net 12/12] batman-adv: fix detection of lower link in batadv_get_real_netdevice

Currently, batadv_get_real_netdevice can return different results in
this situation:

    ip netns add main
    ip netns add peer
    ip -net main link add dummy1 type dummy
    ip -net main link add link dummy1 netns peer type macsec # same ifindex as dummy1
    ip -net main link add link dummy1 netns peer type macsec port 2

Let's use the presence of a ndo_get_iflink operation, rather than the
value it returns, to detect a device without a link.

Fixes: 5ed4a460a1d3 ("batman-adv: additional checks for virtual interfaces on top of WiFi")
Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
---
 net/batman-adv/hard-interface.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 0d87c5d56844..8f7d2dd37321 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -223,7 +223,7 @@ static struct net_device *batadv_get_real_netdevice(struct net_device *netdev)
 	if (!netdev)
 		return NULL;
 
-	if (netdev->ifindex == dev_get_iflink(netdev)) {
+	if (!(netdev->netdev_ops && netdev->netdev_ops->ndo_get_iflink)) {
 		dev_hold(netdev);
 		return netdev;
 	}
-- 
2.28.0