[PATCH net-next] net: add an ioctl to get a socket network namespace

[David Miller]

From: Andrei Vagin <avagin at openvz.org>
Date: Mon, 24 Oct 2016 18:29:13 -0700

> From: Andrey Vagin <avagin at openvz.org>
> 
> Each socket operates in a network namespace where it has been created,
> so if we want to dump and restore a socket, we have to know its network
> namespace.
> 
> We have a socket_diag to get information about sockets, it doesn't
> report sockets which are not bound or connected.
> 
> This patch introduces a new socket ioctl, which is called SIOCGSKNS
> and used to get a file descriptor for a socket network namespace.
> 
> A task must have CAP_NET_ADMIN in a target network namespace to
> use this ioctl.
> 
> Cc: "David S. Miller" <davem at davemloft.net>
> Cc: Eric W. Biederman <ebiederm at xmission.com>
> Signed-off-by: Andrei Vagin <avagin at openvz.org>

Applied.