tun: forbid iface creation with rtnl ops
It's not supported right now (the goal of the initial patch was to support
'ip link del' only).
Before the patch:
$ ip link add foo type tun
[ 239.632660] BUG: unable to handle kernel NULL pointer dereference at
0000000000000000
[snip]
[ 239.636410] RIP: 0010:register_netdevice+0x8e/0x3a0
This panic occurs because dev->netdev_ops is not set by tun_setup(). But to
have something usable, it will require more than just setting
netdev_ops.
Fixes: f019a7a594d9 ("tun: Implement ip link del tunXXX")
CC: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>