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From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
Date:   Wed, 3 Oct 2018 16:28:56 +0200
Message-ID: <CAHmME9pQn3TJtwKuna=qrgm5Sc4sXN2VYEYXkGyKePezkQGu+Q@mail.gmail.com>
Subject: Re: [PATCH net-next v6 23/23] net: WireGuard secure network tunnel
To:     Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Netdev <netdev@vger.kernel.org>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        David Miller <davem@davemloft.net>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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On Wed, Oct 3, 2018 at 4:25 PM Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> >> On Wed, Oct 3, 2018 at 1:15 PM Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> >>> > +config WIREGUARD
> >>> > +       tristate "WireGuard secure network tunnel"
> >>> > +       depends on NET && INET
> >>>
> >>> I think you need to add IPV6 here
> >>
> >> Nope. Like much of the net tree, WireGuard can function on ipv6-less
> >> kernels. If you do find something in WireGuard isn't working in a
> >> v6-less configuration, I consider that to be a bug that needs fixing.
> >>
> >
> > OK. I hit a build error yesterday, and setting CONFIG_IPV6 fixed it.
> > Let me see if I can reproduce.
>
> I get
>
> drivers/net/wireguard/socket.o: In function `send6':
> socket.c:(.text+0x56c): undefined reference to `ipv6_chk_addr'
> drivers/net/wireguard/socket.o: In function `wg_socket_send_skb_to_peer':
> socket.c:(.text+0x904): undefined reference to `ipv6_chk_addr'
> drivers/net/wireguard/socket.o: In function `wg_socket_init':
> socket.c:(.text+0x161c): undefined reference to `ipv6_mod_enabled'
>
> if I build my kernel with WireGuard built in but IPv6 support enabled
> as a module.

Nice catch. Looks like the norm is adding "depends on IPV6 || !IPV6"
or the like. I'll play and make sure this works for v7. Thanks for
pointing it out.

Jason