Messages in this thread | | | From | Arnd Bergmann <> | Date | Tue, 10 Jul 2018 11:10:40 +0200 | Subject | Re: [PATCH] netfilter: NFT_SOCKET don't use NF_SOCKET_IPV6 without NF_TABLES_IPV6 |
| |
On Tue, Jul 10, 2018 at 10:05 AM, Máté Eckl <ecklm94@gmail.com> wrote: > On Tue, Jul 10, 2018 at 10:02:27AM +0200, Máté Eckl wrote: >> On Mon, Jul 09, 2018 at 11:35:09PM +0200, Arnd Bergmann wrote: >> > It is now possible to build the nft_socket module as built-in when >> > NF_TABLES_IPV6 is disabled, and have NF_SOCKET_IPV6=m set manually. >> > >> > In this case, the NF_SOCKET_IPV6 functionality will be useless according >> > to the explanation in commit 35bf1ccecaaa ("netfilter: Kconfig: Change >> > IPv6 select dependencies"), but on top of that it also causes a link >> > error: >> > >> > net/netfilter/nft_socket.o: In function `nft_socket_eval': >> > nft_socket.c:(.text+0x162): undefined reference to `nf_sk_lookup_slow_v6' >> > >> > This changes the compile-time check so we don't attempt to use >> > the NF_SOCKET_IPV6 code when it cannot be used, and make it all >> > compile again. That may lead to unexpected behavior when a user >> > enables NF_SOCKET_IPV6 but cannot use it, but seems to be the >> > logical conclusion of the 35bf1ccecaaa change. >> > >> > Fixes: 35bf1ccecaaa ("netfilter: Kconfig: Change IPv6 select dependencies") >> > Signed-off-by: Arnd Bergmann <arnd@arndb.de> >> >> I think this should be fixed in the Kconfig rather than inside the module(s).
Should we revert your patch then, or do you have a better idea?
>> I did some investigation and it turns out that you missed a circumstance. This >> link error occures only if NFT_SOCKET=y && NF_SOCKET_IPV6=m && NF_TABLES_IPV6=y >> (cannot be m here if NFT_SOCKET is y).
No, if NF_TABLES_IPV6=y the problem cannot happen, since NFT_SOCKET then selects NF_SOCKET_IPV6=y as well. Before your patch, it would always select NF_SOCKET_IPV6 when it could, so it worked in all configurations.
>> And probably the same with >> iptables-related modules. Probably this possibility should be eliminated. > > NF_TPROXY_IPV6 might be in the same situation.
I tried coming up with a combination that is broken for NF_TPROXY_IPV6=m but could not. From what I can see with
config NETFILTER_XT_TARGET_TPROXY tristate '"TPROXY" target transparent proxying support' depends on IP6_NF_IPTABLES || IP6_NF_IPTABLES=n select NF_TPROXY_IPV6 if IP6_NF_IPTABLES
and
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
inside of net/netfilter/xt_TPROXY.c, there is no way we can end up with xt_TPROXY calling into the nf_tproxy_ipv6 loadable module from a built-in context. This is the same approach I used in my patch, just with IP6_NF_IPTABLES instead of NF_SOCKET_IPV6, in both the Kconfig dependency and the module.
Arnd
| |