Subject: Re: [PATCH] netfilter: Fix build failure when ipv6 but xt_tproxy is built in

From: Patrick McHardy <[email-masked]>
Date: Mon, 04 Apr 2011 15:54:40 +0200

On 30.03.2011 07:35, David Miller wrote:
> From: Steven Rostedt <[email-masked]>
> Date: Tue, 29 Mar 2011 22:13:19 -0400
> 
>> While running ktest.pl doing ranconfigs, the following build error
>> occurred:
> 
> Is sending netfilter patches to the explicitly listed maintainer in
> MAINTAINERS too much to ask Stephen? :-/
> 
> CC:'d
> 
>>
>> net/built-in.o: In function `tproxy_tg6_v1':
>> /home/rostedt/work/autotest/nobackup/linux-test.git/net/netfilter/xt_TPROXY.c:288: undefined reference to `ipv6_find_hdr'
>>
>> This happened because the xt_TPROXY code was compiled into the kernel
>> proper, but the ipv6 netfilter was compiled as a module. The fix is to
>> only enter the code that calls ipv6_find_hdr if ipv6 netfilter is
>> compiled into the kernel, or if it is a module, so is the xt_TPROXY
>> code.

I don't think this is a good fix for the problem since it may lead to
the confusing situation that both TPROXY and ip6tables are enabled,
but TPROXY has no IPv6 support.

I think we should solve this by either adding a Kconfig dependency
on (IP6_NF_IPTABLES || IP6_NF_IPTABLES=n) or using ipv6_skip_exthdr()
instead of ipv6_find_hdr().

Krisztian, what do you think?

>>
>> Signed-off-by: Steven Rostedt <[email-masked]>
>>
>> diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
>> index dcfd57e..5915f94 100644
>> --- a/net/netfilter/xt_TPROXY.c
>> +++ b/net/netfilter/xt_TPROXY.c
>> @@ -22,7 +22,13 @@
>>  
>>  #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
>>  
>> -#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
>> +/*
>> + * Only include the following if ip6 tables is compiled in
>> + * the kernel, or it is a module and this code is also a module.
>> + */
>> +#if defined(CONFIG_IP6_NF_IPTABLES) || \
>> +	(defined(CONFIG_IP6_NF_IPTABLES_MODULE) && \
>> +	 defined(CONFIG_NETFILTER_XT_TARGET_TPROXY_MODULE))
>>  #define XT_TPROXY_HAVE_IPV6 1
>>  #include <net/if_inet6.h>
>>  #include <net/addrconf.h>
>>
>>
>