net/unix: don't show information about sockets from other namespaces
socket_diag shows information only about sockets from a namespace where
a diag socket lives.
But if we request information about one unix socket, the kernel don't
check that its netns is matched with a diag socket namespace, so any
user can get information about any unix socket in a system. This looks
like a bug.
v2: add a Fixes tag
Fixes:
51d7cccf0723 ("net: make sock diag per-namespace")
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>