Re: [PATCH net-next v2 3/3] netlink: add validation of NLA_F_NESTED flag

On Tue, 2019-07-23 at 11:02 -0700, Stephen Hemminger wrote:

There are some cases where netlink related to IPv4 does not send nested
flag. You risk breaking older iproute2 and other tools being used on newer
kernel. I.e this patch may break binary compatibility. Have you tried running
with this on a very old distro (like Redhat Linux 9)?

There are *tons* of places where this (and other things) wasn't done
right, but the validation is only added for

 * all attributes on _new operations_ (that old userspace couldn't have
   been using since they're introduced after this patch)
 * _new attributes_ (dito, if the policy 'strict start' is filled)

johannes