[PATCH AUTOSEL 4.18 009/126] tun: Consistently configure generic netdev params via rtnetlink

Sasha Levin
2018-10-31T23:08:06Z

From: Serhey Popovych <serhe.popovych@gmail.com>

[ Upstream commit df52eab23d703142c766ac00bdb8db19d71238d0 ]

Configuring generic network device parameters on tun will fail in
presence of IFLA_INFO_KIND attribute in IFLA_LINKINFO nested attribute
since tun_validate() always return failure.

This can be visualized with following ip-link(8) command sequences:

# ip link set dev tun0 group 100
# ip link set dev tun0 group 100 type tun
RTNETLINK answers: Invalid argument

with contrast to dummy and veth drivers:

# ip link set dev dummy0 group 100
# ip link set dev dummy0 type dummy

# ip link set dev veth0 group 100
# ip link set dev veth0 group 100 type veth

Fix by returning zero in tun_validate() when @data is NULL that is
always in case since rtnl_link_ops->maxtype is zero in tun driver.

Fixes: f019a7a594d9 ("tun: Implement ip link del tunXXX")
Signed-off-by: Serhey Popovych <serhe.popovych@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/tun.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 725dd63f8413..546081993ecf 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2304,6 +2304,8 @@ static void tun_setup(struct net_device *dev)
static int tun_validate(struct nlattr *tb[], struct nlattr *data[],
struct netlink_ext_ack *extack)
{
+ if (!data)
+ return 0;
return -EINVAL;
}

--
2.17.1