From: ebiederm@xmission•com (Eric W. Biederman)
To: Pablo Neira Ayuso <pablo@netfilter•org>
Cc: Cong Wang <xiyou.wangcong@gmail•com>,
Florian Westphal <fw@strlen•de>,
netfilter-devel@vger•kernel.org,
Linux Kernel Network Developers <netdev@vger•kernel.org>
Subject: Re: [PATCH nf-next] netns: add and use net_ns_barrier
Date: Wed, 14 Jun 2017 09:20:25 -0500 [thread overview]
Message-ID: <87wp8eabx2.fsf@xmission.com> (raw)
In-Reply-To: <20170614084147.GC31030@salvia> (Pablo Neira Ayuso's message of "Wed, 14 Jun 2017 10:41:47 +0200")
Pablo Neira Ayuso <pablo@netfilter•org> writes:
> Hi!
>
> On Tue, Jun 13, 2017 at 09:35:20AM -0700, Cong Wang wrote:
>> On Mon, Jun 12, 2017 at 11:16 PM, Florian Westphal <fw@strlen•de> wrote:
>> > Cong Wang <xiyou.wangcong@gmail•com> wrote:
>> >> On Thu, Jun 1, 2017 at 1:52 AM, Florian Westphal <fw@strlen•de> wrote:
>> >> > Joe described it nicely, problem is that after unload we may have
>> >> > conntracks that still have a nf_conn_help extension attached that
>> >> > has a pointer to a structure that resided in the (unloaded) module.
>> >>
>> >> Why not hold a refcnt for its module?
>> >
>> > That would work as well.
>> >
>> > I'm not sure its nice to disallow rmmod of helper modules if they are
>> > used by a connection however.
>>
>> I am _not_ suggesting to disallow rmmod.
>>
>> >
>> > Right now you can "rmmod nf_conntrack_foo" at any time and this should
>> > work just fine without first having to flush affected conntracks
>> > manually.
>>
>> My point is that since netns wq could invoke code of that module,
>> why it doesn't hold a refcnt of that module?
>>
>> I am not familiar with netfilter code base so not sure if that is
>> hard to do or not, but it looks more elegant than this barrier.
>
> Florian has added a new native interface to integrate helpers into
> nftables in a much better way than we do now, that allows much more
> fine grain configuration. This new interface bumps refcounts on
> helpers as you suggest.
>
> However, we still have to sort of keep the existing behaviour around,
> people has been relying on this rmmod feature to globally disable
> helpers. It's very old thing indeed and as you can see, very sparse
> grain for the netns era... But still I think we need this.
>
> So I'm inclined to take this, and keep an eye to deprecate this
> behaviour in a several years ahead once. Probably we can get rid of
> this barrier at some point.
Acked-by: "Eric W. Biederman" <ebiederm@xmission•com>
If it works I don't have any problems with the code and it sounds like
it works.
My apologies for the delay. There is an email black hole between Forian
and myself and I missed his replies. Which gave me a very distored
picture of the conversation.
Eric
next prev parent reply other threads:[~2017-06-14 14:20 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-30 9:38 [PATCH nf-next] netns: add and use net_ns_barrier Florian Westphal
2017-05-31 16:55 ` David Miller
2017-05-31 17:46 ` Eric W. Biederman
2017-05-31 18:13 ` Eric W. Biederman
2017-05-31 20:21 ` Joe Stringer
2017-06-01 8:52 ` Florian Westphal
2017-06-12 21:47 ` Cong Wang
2017-06-13 6:16 ` Florian Westphal
2017-06-13 16:35 ` Cong Wang
2017-06-13 18:07 ` Florian Westphal
2017-06-13 19:27 ` Joe Stringer
2017-06-13 21:16 ` Cong Wang
2017-06-14 8:41 ` Pablo Neira Ayuso
2017-06-14 14:20 ` Eric W. Biederman [this message]
2017-06-12 8:47 ` Pablo Neira Ayuso
2017-06-02 9:38 ` David Laight
2017-06-02 9:53 ` Florian Westphal
2017-06-19 17:10 ` Pablo Neira Ayuso
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