[NETFILTER]: Add partial checksum validation helper

Move the UDP-Lite conntrack checksum validation to a generic helper
similar to nf_checksum() and make it fall back to nf_checksum()
in case the full packet is to be checksummed and hardware checksums
are available. This is to be used by DCCP conntrack, which also
needs to verify partial checksums.

Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 22 insertions, 0 deletions

diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
index 66bc520..e4c6659 100644
--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -234,6 +234,11 @@ struct nf_afinfo {
 	unsigned short	family;
 	__sum16		(*checksum)(struct sk_buff *skb, unsigned int hook,
 				    unsigned int dataoff, u_int8_t protocol);
+	__sum16		(*checksum_partial)(struct sk_buff *skb,
+					    unsigned int hook,
+					    unsigned int dataoff,
+					    unsigned int len,
+					    u_int8_t protocol);
 	int		(*route)(struct dst_entry **dst, struct flowi *fl);
 	void		(*saveroute)(const struct sk_buff *skb,
 				     struct nf_queue_entry *entry);
@@ -263,6 +268,23 @@ nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 	return csum;
 }
 
+static inline __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_afinfo *afinfo;
+	__sum16 csum = 0;
+
+	rcu_read_lock();
+	afinfo = nf_get_afinfo(family);
+	if (afinfo)
+		csum = afinfo->checksum_partial(skb, hook, dataoff, len,
+						protocol);
+	rcu_read_unlock();
+	return csum;
+}
+
 extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);