linux-kernel - Re: [PATCH v3 net-next] net: filter: cleanup sk_* and bpf

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Message-ID: <CAMEtUuxsFdmWM5DFXNRMnDKzqfgsaEashsMvDsKcjnF=T8pbpA@mail.gmail.com>
Date:	Tue, 29 Jul 2014 10:25:25 -0700
From:	Alexei Starovoitov <ast@...mgrid.com>
To:	Pablo Neira Ayuso <pablo@...filter.org>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Daniel Borkmann <dborkman@...hat.com>,
	Willem de Bruijn <willemb@...gle.com>,
	Kees Cook <keescook@...omium.org>,
	Network Development <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	netfilter-devel <netfilter-devel@...r.kernel.org>
Subject: Re: [PATCH v3 net-next] net: filter: cleanup sk_* and bpf_* names

On Tue, Jul 29, 2014 at 9:42 AM, Pablo Neira Ayuso <pablo@...filter.org> wrote:
> On Tue, Jul 29, 2014 at 08:55:04AM -0700, Alexei Starovoitov wrote:
>> > I don't think this is the right moment to add this, but we have to
>> > keep in mind that something similar to this will need to be
>> > accomodated in struct sk_filter at some point to avoid sloppy changes
>> > that may result in reintroducing code later on.
>>
>> I thought in v1 series you were arguing exactly about introducing them now...
>> ok, I will drop callbacks and keep refcnt,rcu,filter_size and bpf_prog pointer
>> in there. Sounds good?
>
> Agreed.
>
>> > Next step should be to wrap the specific bpf fields in struct
>> > bpf_prog in some clean way IMO, which was partially the aim of this
>> > patch.
>>
>> it seems your only objection is 'rcu_head' still being there and rebasing
>> on top of yours will fix it...
>
> Almost. I just wanted to leave in place struct sk_filter for the
> coming up generalization, that structure should contain the refcnt,
> rcu_head and the struct bpf_prog after some of your follow up patches.

Yes. something like:
struct sk_filter {
        atomic_t refcnt;
        struct rcu_head rcu;
        u32 filter_size;
        struct bpf_prog *prog;
};
filter_size also makes sense to add right now to cleanup charging.

> Please, also leave sk_filter_charge/uncharge/get_filter whatever will
> provide the room the generalization under net/core/filter.c, not need
> to move these to kernel/bpf/

of course, that was never the intent.
all socket related stuff should keep sk_* prefix and stay in net/
only net-independent things makes sense to move.

> After my patch (and your follow up), we don't have sloppy usage of
> rcu_head for unattached filter anymore and I guess Willem is going to
> same save bytes in his iptables/bpf rules given that he can directly
> use bpf_prog instead of sk_filter.

yes. exactly.

btw, Dave may request to do a fresh repost of both of your
patches with v2 tag... Alternatively I can do rebase + fix what we
discussed above + split and repost yours and mine as single
series, since they're addressing one area...
Also I want to do some more testing of your #2 patch for seccomp
to make sure all is clean.
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