kni: check abi version between kmod and lib

[Ray Kinsella]

Stephen Hemminger <stephen at networkplumber.org> writes:

> 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.

Well look, it is out-of-tree and never likely to be in-tree, so those
rules don't apply. Making sure the ABI doesn't change during the ABI
stablity period, should be good enough?

-- 
Regards, Ray K