net: Verify permission to link_net in newlink

When applicable verify that the caller has permisson to the underlying
network namespace for a newly created network device.

Similary checks exist for the network namespace a network device will
be created in.

Fixes: 317f4810e45e ("rtnl: allow to create device with IFLA_LINK_NETNSID set")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index b237959c7497..2c49355d16c2 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2134,6 +2134,9 @@ replay:
                                 err =  -EINVAL;
                                 goto out;
                         }
+                        err = -EPERM;
+                        if (!netlink_ns_capable(skb, link_net->user_ns, CAP_NET_ADMIN))
+                                goto out;
                 }
 
                 dev = rtnl_create_link(link_net ? : dest_net, ifname,