xfrm: Refuse to insert 32 bit userspace socket policies on 64 bit systems

xfrm: Refuse to insert 32 bit userspace socket policies on 64 bit systems

commit 19d7df69fdb2636856dc8919de72fc1bf8f79598 upstream.

We don't have a compat layer for xfrm, so userspace and kernel
structures have different sizes in this case. This results in
a broken configuration, so refuse to configure socket policies
when trying to insert from 32 bit userspace as we do it already
with policies inserted via netlink.

Reported-and-tested-by: syzbot+e1a1577ca8bcb47b769a@syzkaller.appspotmail.com
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
[use is_compat_task() - gregkh]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>