Re: [RFC PATCH -next] netfilter: nfqueue: add ability to dump list of supported attributes

[Pablo Neira Ayuso <pablo@netfilter.org>]

Hi Florian,

On Tue, Jun 04, 2013 at 05:37:53PM +0200, Florian Westphal wrote:
> Allows userspace to dump the list of known (extended) attributes.
> For SKB_INFO, we set all the info flag bits supported by the running kernel.
> 
> The latter is required because absence of some bits in the info attribute will
> either mean "skb did not have the property" OR "this kernel doesn't know about
> this flag".
>
> Signed-off-by: Florian Westphal <fw@strlen.de>
> ---
>  Recent discussion of the
>  "netfilter: nf_queue: add NFQA_SKB_CSUM_NOTVERIFIED info flag" patch
>  (http://patchwork.ozlabs.org/patch/246460/) shows that we'll need
>  to tell userspace the supported info bits in the NFAQ_SKB_INFO attribute.

After going back to this issue, I think I prefer to enqueue:

netfilter: nf_queue: add NFQA_SKB_CSUM_NOTVERIFIED info flag

to net-next, and ask for -stable submission once this hits net, as it
will be fixing an inconsistent behaviour. Another reason for that is
that such patch is fairly small (~16 LOC).

Both approaches we discussed that are:

a) adding a new config flags

and

b) adding this infrastructure

look a bit too much to me just to resolve this.

Once this patch hits -stable, we can consistently say that:

NFQA_SKB_CSUMNOTREADY
NFQA_SKB_GSO
NFQA_SKB_CSUM_NOTVERIFIED

are obtained via NFQA_CFG_F_GSO.

For user-space application running with different, they can still send
every configuration incrementally, so you spot a message telling what
is available and what is not. I planned to use this to add GSO support
for the user-space helper infrastructure.

Let me know.