From: Pablo Neira Ayuso <pablo@netfilter.org>
To: David Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org, netfilter-devel@vger.kernel.org,
hannes@stressinduktion.org, jiri@resnulli.us
Subject: Re: [PATCH 0/9] netfilter: Compress hook function signatures.
Date: Sat, 4 Apr 2015 13:49:28 +0200 [thread overview]
Message-ID: <20150404114928.GA3829@salvia> (raw)
In-Reply-To: <20150403.220734.1272465850706339981.davem@davemloft.net>
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!
next prev parent reply other threads:[~2015-04-04 11:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-04 2:07 [PATCH 0/9] netfilter: Compress hook function signatures David Miller
2015-04-04 11:49 ` Pablo Neira Ayuso [this message]
2015-04-04 15:54 ` David Miller
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