netfilter: move checksum indirection to struct nf_ipv6_ops
We cannot make a direct call to nf_ip6_checksum() because that would
result in autoloading the 'ipv6' module because of symbol dependencies.
Therefore, define checksum 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>
diff --git a/net/netfilter/utils.c b/net/netfilter/utils.c
new file mode 100644
index 0000000..159a9cd
--- /dev/null
+++ b/net/netfilter/utils.c
@@ -0,0 +1,26 @@
+#include <linux/kernel.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv6.h>
+
+__sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
+ unsigned int dataoff, 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(skb, hook, dataoff, protocol);
+ break;
+ case AF_INET6:
+ v6ops = rcu_dereference(nf_ipv6_ops);
+ if (v6ops)
+ csum = v6ops->checksum(skb, hook, dataoff, protocol);
+ break;
+ }
+
+ return csum;
+}
+EXPORT_SYMBOL_GPL(nf_checksum);
