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From:   Arnd Bergmann <arnd@arndb.de>
To:     Pablo Neira Ayuso <pablo@netfilter.org>,
        Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
        Florian Westphal <fw@strlen.de>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        "David S. Miller" <davem@davemloft.net>, wenxu <wenxu@ucloud.cn>,
        netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH net-next] netfilter: fix nf_conntrack_bridge/ipv6 link error
Date:   Mon, 17 Jun 2019 15:15:04 +0200
Message-Id: <20190617131515.2334941-1-arnd@arndb.de>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

When CONFIG_IPV6 is disabled, the bridge netfilter code
produces a link error:

ERROR: "br_ip6_fragment" [net/bridge/netfilter/nf_conntrack_bridge.ko] undefined!
ERROR: "nf_ct_frag6_gather" [net/bridge/netfilter/nf_conntrack_bridge.ko] undefined!

The problem is that it assumes that whenever IPV6 is not a loadable
module, we can call the functions direction. This is clearly
not true when IPV6 is disabled.

There are two other functions defined like this in linux/netfilter_ipv6.h,
so change them all the same way.

Fixes: 764dd163ac92 ("netfilter: nf_conntrack_bridge: add support for IPv6")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/linux/netfilter_ipv6.h | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/include/linux/netfilter_ipv6.h b/include/linux/netfilter_ipv6.h
index 3a3dc4b1f0e7..85d61db88b05 100644
--- a/include/linux/netfilter_ipv6.h
+++ b/include/linux/netfilter_ipv6.h
@@ -70,8 +70,10 @@ static inline int nf_ipv6_chk_addr(struct net *net, const struct in6_addr *addr,
 		return 1;
 
 	return v6_ops->chk_addr(net, addr, dev, strict);
-#else
+#elif IS_BUILTIN(CONFIG_IPV6)
 	return ipv6_chk_addr(net, addr, dev, strict);
+#else
+	return 1;
 #endif
 }
 
@@ -108,8 +110,10 @@ static inline int nf_ipv6_br_defrag(struct net *net, struct sk_buff *skb,
 		return 1;
 
 	return v6_ops->br_defrag(net, skb, user);
-#else
+#elif IS_BUILTIN(CONFIG_IPV6)
 	return nf_ct_frag6_gather(net, skb, user);
+#else
+	return 1;
 #endif
 }
 
@@ -133,8 +137,10 @@ static inline int nf_br_ip6_fragment(struct net *net, struct sock *sk,
 		return 1;
 
 	return v6_ops->br_fragment(net, sk, skb, data, output);
-#else
+#elif IS_BUILTIN(CONFIG_IPV6)
 	return br_ip6_fragment(net, sk, skb, data, output);
+#else
+	return 1;
 #endif
 }
 
@@ -149,8 +155,10 @@ static inline int nf_ip6_route_me_harder(struct net *net, struct sk_buff *skb)
 		return -EHOSTUNREACH;
 
 	return v6_ops->route_me_harder(net, skb);
-#else
+#elif IS_BUILTIN(CONFIG_IPV6)
 	return ip6_route_me_harder(net, skb);
+#else
+	return -EHOSTUNREACH;
 #endif
 }
 
-- 
2.20.0