[PATCH net 2/2] 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: v4.0-rc1
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <redacted>
---
 net/core/rtnetlink.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 155e675f656c..0a0b1c081d68 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,

-- 
2.2.1