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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Fri, 6 Jul 2018 15:05:13 +0200
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Subject: Re: [PATCH net-next] netfilter: fix NETFILTER_XT_TARGET_TEE dependencies
To:     Pablo Neira Ayuso <pablo@netfilter.org>
Cc:     Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
        Florian Westphal <fw@strlen.de>,
        "David S. Miller" <davem@davemloft.net>,
        =?UTF-8?B?TcOhdMOpIEVja2w=?= <ecklm94@gmail.com>,
        Fernando Fernandez Mancera <ffmancera@riseup.net>,
        "Pablo M. Bermudo Garay" <pablombg@gmail.com>,
        Felix Fietkau <nbd@nbd.name>, netfilter-devel@vger.kernel.org,
        coreteam@netfilter.org, Networking <netdev@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, Jul 6, 2018 at 2:48 PM, Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> On Fri, Jul 06, 2018 at 02:45:42PM +0200, Pablo Neira Ayuso wrote:
>> On Fri, Jul 06, 2018 at 02:37:58PM +0200, Arnd Bergmann wrote:
>> > With NETFILTER_XT_TARGET_TEE=y and IP6_NF_IPTABLES=m, we get a link
>> > error when referencing the NF_DUP_IPV6 module:
>> >
>> > net/netfilter/xt_TEE.o: In function `tee_tg6':
>> > xt_TEE.c:(.text+0x14): undefined reference to `nf_dup_ipv6'
>> >
>> > The problem here is the 'select NF_DUP_IPV6 if IP6_NF_IPTABLES'
>> > that forces NF_DUP_IPV6 to be =m as well rather than setting it
>> > to =y as was intended here. Adding a soft dependency on
>> > IP6_NF_IPTABLES avoids that broken configuration.
>>
>> Applied to nf.git, thanks Arnd.
>
> Sorry, let me reconsider.
>
> We many need similar patches to other spots in 35bf1ccecaaa ?
>
> If so, it would be good to fix in the one go.

I'm fairly sure that  NETFILTER_XT_TARGET_LOG is safe, since
NF_LOG_IPV6 already depends on IP6_NF_IPTABLES.

NF_SOCKET_IPV6 like NF_DUP_IPV6 does not depend on
IP6_NF_IPTABLES, so we may have a similar problem there, though
I have not come across that. I have done only a few hundred randconfig
builds since I started yesterday, so I may have missed something,
but I think this is safe because CONFIG_NF_SOCKET_IPV6 is
used like a 'bool' symbol these days, we don't actually control building
a module with it, only a small portion in the nft_socket file.

       Arnd