Revert "sctp: do not peel off an assoc from one netns to another one"

BugLink: http://bugs.launchpad.net/bugs/1744873

This reverts commit 2a0e6090 which is
commit df80cd9b upstream as I messed up
by applying it to the tree twice.
Reported-by: Michal Kubecek <mkubecek@suse.cz>
Cc: ChunYu Wang <chunwang@redhat.com>
Cc: Xin Long <lucien.xin@gmail.com>
Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

net/sctp/socket.c

@@ -4453,10 +4453,6 @@ int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp)
 	struct socket *sock;
 	int err = 0;
 
-	/* Do not peel off from one netns to another one. */
-	if (!net_eq(current->nsproxy->net_ns, sock_net(sk)))
-		return -EINVAL;
-
 	/* Do not peel off from one netns to another one. */
 	if (!net_eq(current->nsproxy->net_ns, sock_net(sk)))
 		return -EINVAL;