[PATCH net-next v10 04/13] ieee802154: 6lowpan: Validate link netns in newlink() of rtnl_link_ops

[Xiao Liang <shaw.leon@gmail.com>]

Device denoted by IFLA_LINK is in link_net (IFLA_LINK_NETNSID) or
source netns by design, but 6lowpan uses dev_net.

Note dev->netns_local is set to true and currently link_net is
implemented via a netns change. These together effectively reject
IFLA_LINK_NETNSID.

This patch adds a validation to ensure link_net is either NULL or
identical to dev_net. Thus it would be fine to continue using dev_net
when rtnetlink core begins to create devices directly in target netns.

Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/ieee802154/6lowpan/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ieee802154/6lowpan/core.c b/net/ieee802154/6lowpan/core.c
index 704bf9e3f097..ee318d46817d 100644
--- a/net/ieee802154/6lowpan/core.c
+++ b/net/ieee802154/6lowpan/core.c
@@ -143,6 +143,8 @@ static int lowpan_newlink(struct net_device *ldev,
 
 	if (!tb[IFLA_LINK])
 		return -EINVAL;
+	if (params->link_net && !net_eq(params->link_net, dev_net(ldev)))
+		return -EINVAL;
 	/* find and hold wpan device */
 	wdev = dev_get_by_index(dev_net(ldev), nla_get_u32(tb[IFLA_LINK]));
 	if (!wdev)
-- 
2.48.1