kni: check abi version between kmod and lib

[Stephen Hemminger]

On Thu, 21 Apr 2022 12:38:26 +0800
Stephen Coleman <omegacoleman at gmail.com> wrote:

> KNI ioctl functions copy data from userspace lib, and this interface
> of kmod is not compatible indeed. If the user use incompatible rte_kni.ko
> bad things happen: sometimes various fields contain garbage value,
> sometimes it cause a kmod soft lockup.
> 
> Some common distros ship their own rte_kni.ko, so this is likely to
> happen.
> 
> This patch add abi version checking between userland lib and kmod so
> that:
> 
> * if kmod ioctl got a wrong abi magic, it refuse to go on
> * if userland lib, probed a wrong abi version via newly added ioctl, it
>   also refuse to go on
> 
> Bugzilla ID: 998


Kernel API's are supposed to be 99% stable.
If this driver was playing by the upstream kernel rules this would not
have happened.