Re: [PATCH 4/7 parse attributes with nfattr_parse in nfnetlink_check_attribute

[Thomas Graf <tgraf@suug.ch>]

* Patrick McHardy <kaber@trash.net> 2007-02-13 12:05
> Pablo Neira Ayuso wrote:
> > [PATCH] parse attributes with nfattr_parse in nfnetlink_check_attribute
> > 
> > Use nfattr_parse to parse attributes, this patch also modifies the default 
> > behaviour since unknown attributes will be ignored instead of returning 
> > EINVAL. This ensure backward compatibility: new libraries with new 
> > attributes and old kernels can work.
> 
> Currently other netlink subsystems return errors for the first level
> of attributes and accept unknown attributes on deeper levels. I'm
> not sure which I prefer, ignoring unknown attributes makes it
> impossible for userspace to know that something isn't going to have
> any effect, returning an error makes it harder to support new features.
> 
> I know Thomas had intentions of increasing consistency in this area,
> I'm just not sure in which direction :)
> 
> Thomas, what do you think of this patch?

I believe that all unknown attributes should be ignored so recent
userspace code can function on older kernels. That's the way I'm
working towards.