[NETFILTER]: Add partial checksum validation helper

[linux-2.6-omap-h63xx.git] / net / ipv4 / netfilter.c

diff --git a/net/ipv4/netfilter.c b/net/ipv4/netfilter.c
index 9a904c6c0dc8d0d72244ecac2c53ce49cf68cb65..f8edacdf991df1d74fac5e0bafad89c9caa481ce 100644 (file)
--- a/net/ipv4/netfilter.c
+++ b/net/ipv4/netfilter.c
@@ -182,21 +182,44 @@ __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
        }
        return csum;
 }
-
 EXPORT_SYMBOL(nf_ip_checksum);
 
+static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
+                                     unsigned int dataoff, unsigned int len,
+                                     u_int8_t protocol)
+{
+       const struct iphdr *iph = ip_hdr(skb);
+       __sum16 csum = 0;
+
+       switch (skb->ip_summed) {
+       case CHECKSUM_COMPLETE:
+               if (len == skb->len - dataoff)
+                       return nf_ip_checksum(skb, hook, dataoff, protocol);
+               /* fall through */
+       case CHECKSUM_NONE:
+               skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
+                                              skb->len - dataoff, 0);
+               skb->ip_summed = CHECKSUM_NONE;
+               csum = __skb_checksum_complete_head(skb, dataoff + len);
+               if (!csum)
+                       skb->ip_summed = CHECKSUM_UNNECESSARY;
+       }
+       return csum;
+}
+
 static int nf_ip_route(struct dst_entry **dst, struct flowi *fl)
 {
        return ip_route_output_key(&init_net, (struct rtable **)dst, fl);
 }
 
 static const struct nf_afinfo nf_ip_afinfo = {
-       .family         = AF_INET,
-       .checksum       = nf_ip_checksum,
-       .route          = nf_ip_route,
-       .saveroute      = nf_ip_saveroute,
-       .reroute        = nf_ip_reroute,
-       .route_key_size = sizeof(struct ip_rt_info),
+       .family                 = AF_INET,
+       .checksum               = nf_ip_checksum,
+       .checksum_partial       = nf_ip_checksum_partial,
+       .route                  = nf_ip_route,
+       .saveroute              = nf_ip_saveroute,
+       .reroute                = nf_ip_reroute,
+       .route_key_size         = sizeof(struct ip_rt_info),
 };
 
 static int ipv4_netfilter_init(void)