Re: [PATCH 0/9] netfilter: Compress hook function signatures.

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

On Fri, Apr 03, 2015 at 10:07:34PM -0400, David Miller wrote:
> 
> Currently netfilter hooks have a function signature that is huge and
> has many arguments.  This propagates from the hook entry points down
> into the individual hook implementations themselves.
> 
> This means that if, for example, we want to change the type of one of
> these arguments then we have to touch hundreds of locations.
> 
> The main initial motivation behind this is that we'd like to change
> the signature of "okfn" so that a socket pointer can be passed in (and
> reference counted properly) for the sake of using the proper socket
> context in the case of tunnels whilst not releasing the top level user
> socket from skb->sk (and thus releasing it's socket memory quota
> usage) in order to accomodate this.
> 
> This also makes it clear who actually uses 'okfn', nf_queue().  It is
> absolutely critical to make this obvious because any user of 'okfn'
> down in these hook chains have the be strictly audited for
> escapability.  Specifically, escapability of references to objects
> outside of the packet processing path.  And that's exactly what
> nf_queue() does via it's packet reinjection framework.
> 
> In fact this points out a bug in Jiri's original attempt to push the
> socket pointer down through netfilter's okfn.  It didn't grab and drop
> a reference to the socket in net/netfilter/nf_queue.c as needed.
>
> Furthermore, so many code paths are simplified, and should in fact be
> more efficient because we aren't passing in arguments that often are
> simply not used by the netfilter hook at all.
> 
> Further simplifications are probably possible, but this series takes
> care of the main cases.
> 
> Unfortunately I couldn't convert ebt_do_table() because ebtables is
> complete and utter crap and uses ebt_do_table() outside of the hook
> call chains.  But that should not be news to anyone.
> 
> Signed-off-by: David S. Miller <davem@davemloft.net>

Nice series. If you route them through net-next, please add:

Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>

or I can place them in nf-next, your call.

Regarding Jiri's okfn() signature changes, please let me know on those
patches, they will simplify a patchset I'll submit soon. And count on
me to help on that change too, of course.

Thanks a lot David!