rtnetlink: pass link_net to the newlink handler

When IFLA_LINK_NETNSID is used, the netdevice should be built in this link netns
and moved at the end to another netns (pointed by the socket netns or
IFLA_NET_NS_[PID|FD]).

Existing user of the newlink handler will use the netns argument (src_net) to
find a link netdevice or to check some other information into the link netns.
For example, to find a netdevice, two information are required: an ifindex
(usually from IFLA_LINK) and a netns (this link netns).

Note: when using IFLA_LINK_NETNSID and IFLA_NET_NS_[PID|FD], a user may create a
netdevice that stands in netnsX and with its link part in netnsY, by sending a
rtnl message from netnsZ.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 07447d1665e636d44460dbb6f12c4bbb3ab22cfd..fedd7ab4085a767c7f855bf60cb79412886d0bc7 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2148,7 +2148,7 @@ replay:
                dev->ifindex = ifm->ifi_index;
 
                if (ops->newlink) {
-                       err = ops->newlink(net, dev, tb, data);
+                       err = ops->newlink(link_net ? : net, dev, tb, data);
                        /* Drivers should call free_netdev() in ->destructor
                         * and unregister it on failure after registration
                         * so that device could be finally freed in rtnl_unlock.