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

[Johannes Berg]

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