net: ip6_gre: fix moving ip6gre between namespaces

Support for moving IPv4 GRE tunnels between namespaces was added in
commit b57708a ("gre: add x-netns support"). The respective change
for IPv6 tunnels, commit 22f0806 ("ip6gre: add x-netns support")
did not drop NETIF_F_NETNS_LOCAL flag so moving them from one netns to
another is still denied in IPv6 case. Drop NETIF_F_NETNS_LOCAL flag from
ip6gre tunnels to allow moving ip6gre tunnel endpoints between network
namespaces.

Signed-off-by: Niko Kortstrom <niko.kortstrom@nokia.com>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: William Tu <u9012063@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ip6_gre.c

@@ -1466,7 +1466,6 @@ static int ip6gre_tunnel_init_common(struct net_device *dev)
 		dev->mtu -= 8;
 
 	if (tunnel->parms.collect_md) {
-		dev->features |= NETIF_F_NETNS_LOCAL;
 		netif_keep_dst(dev);
 	}
 	ip6gre_tnl_init_features(dev);
@@ -1894,7 +1893,6 @@ static void ip6gre_tap_setup(struct net_device *dev)
 	dev->needs_free_netdev = true;
 	dev->priv_destructor = ip6gre_dev_free;
 
-	dev->features |= NETIF_F_NETNS_LOCAL;
 	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
 	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
 	netif_keep_dst(dev);
@@ -2197,7 +2195,6 @@ static void ip6erspan_tap_setup(struct net_device *dev)
 	dev->needs_free_netdev = true;
 	dev->priv_destructor = ip6gre_dev_free;
 
-	dev->features |= NETIF_F_NETNS_LOCAL;
 	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
 	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
 	netif_keep_dst(dev);