Re: [RFC PATCH] xfrm: fix handling of XFRM policies mark and mask.

Emmanuel Thierry
2013-02-08T14:16:49Z

Hello,

Le 7 févr. 2013 à 13:54, Steffen Klassert <steffen.klassert@secunet.com> a écrit :

> On Thu, Feb 07, 2013 at 12:08:22PM +0100, Emmanuel Thierry wrote:
>>
>> This is a nice idea, however you keep the insertion asymmetric. The usage of xfrm marks in non-conflicting cases will be made possible, but it stays disturbing for a user as the initial example will still have the same behavior:
>> * Inserting the marked one then the unmarked will succeed
>> * Inserting the unmarked then the marked one will fail
>> This gives to the user the feeling of an indeterministic behavior of the xfrm module.
>
> This was intended. Inserting the marked one then the unmarked
> is a working scenario. Some users might rely on it, so we can't
> change this as you proposed.
>
> On the other hand, inserting the unmarked one then the marked
> might result in a wrong policy lookup, so we can't allow this.
> The only possibility we have, is inserting with different
> priorites and that's what I'm proposing.
>
> I fear we have to live with that asymmetric behaviour if
> both policies have the same priority.
>

Ok, actually i understand the concern of backward compatibility you expose. It is true that users might be disturbed if we change such a behavior they would rely on.
Anyway, i'm ok with your patch.

Best regards
Emmanuel Thierry