netfilter: move checksum_partial indirection to struct nf_ipv6_ops

We cannot make a direct call to nf_ip6_checksum_partial() because that
would result in autoloading the 'ipv6' module because of symbol
dependencies.  Therefore, define checksum_partial indirection in
nf_ipv6_ops where this really belongs to.

For IPv4, we can indeed make a direct function call, which is faster,
given IPv4 is built-in in the networking code by default. Still,
CONFIG_INET=n and CONFIG_NETFILTER=y is possible, so define empty inline
stub for IPv4 in such case.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/net/netfilter/utils.c b/net/netfilter/utils.c
index 159a9cdcfe1e..ca6d8d62496d 100644
--- a/net/netfilter/utils.c
+++ b/net/netfilter/utils.c
@@ -24,3 +24,27 @@ __sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
 	return csum;
 }
 EXPORT_SYMBOL_GPL(nf_checksum);
+
+__sum16 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
+			    unsigned int dataoff, unsigned int len,
+			    u_int8_t protocol, unsigned short family)
+{
+	const struct nf_ipv6_ops *v6ops;
+	__sum16 csum = 0;
+
+	switch (family) {
+	case AF_INET:
+		csum = nf_ip_checksum_partial(skb, hook, dataoff, len,
+					      protocol);
+		break;
+	case AF_INET6:
+		v6ops = rcu_dereference(nf_ipv6_ops);
+		if (v6ops)
+			csum = v6ops->checksum_partial(skb, hook, dataoff, len,
+						       protocol);
+		break;
+	}
+
+	return csum;
+}
+EXPORT_SYMBOL_GPL(nf_checksum_partial);