[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 66bc52060fd6..e4c66593b5c6 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);