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Date:   Mon, 27 Nov 2023 13:38:06 +0100
From:   Pablo Neira Ayuso <pablo@netfilter.org>
To:     Felix Huettner <felix.huettner@mail.schwarz>
Cc:     linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org,
        coreteam@netfilter.org, netdev@vger.kernel.org,
        linux-kselftest@vger.kernel.org, kadlec@netfilter.org,
        fw@strlen.de, davem@davemloft.net, edumazet@google.com,
        pabeni@redhat.com, shuah@kernel.org, luca.czesla@mail.schwarz,
        max.lamprecht@mail.schwarz
Subject: Re: [PATCH net-next v2] net: ctnetlink: support filtering by zone
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References: <ZWSCPKtDuYRG1XWt@kernel-bug-kernel-bug>
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Hi,

On Mon, Nov 27, 2023 at 11:49:16AM +0000, Felix Huettner wrote:
> conntrack zones are heavily used by tools like openvswitch to run
> multiple virtual "routers" on a single machine. In this context each
> conntrack zone matches to a single router, thereby preventing
> overlapping IPs from becoming issues.
> In these systems it is common to operate on all conntrack entries of a
> given zone, e.g. to delete them when a router is deleted. Previously this
> required these tools to dump the full conntrack table and filter out the
> relevant entries in userspace potentially causing performance issues.
> 
> To do this we reuse the existing CTA_ZONE attribute. This was previous
> parsed but not used during dump and flush requests. Now if CTA_ZONE is
> set we filter these operations based on the provided zone.
> However this means that users that previously passed CTA_ZONE will
> experience a difference in functionality.
> 
> Alternatively CTA_FILTER could have been used for the same
> functionality. However it is not yet supported during flush requests and
> is only available when using AF_INET or AF_INET6.

You mean, AF_UNSPEC cannot be specified in CTA_FILTER?

Please, extend libnetfilter_conntrack to support for this feature,
there is a filter API that can be used for this purpose.

Thanks.