[NETFILTER]: Convert conntrack/ipt_REJECT to new checksumming functions

Besides removing lots of duplicate code, all converted users benefit
from improved HW checksum error handling. Tested with and without HW
checksums in almost all combinations.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/nf_conntrack_proto_udp.c b/net/netfilter/nf_conntrack_proto_udp.c
index 831d206..d93edbf 100644
--- a/net/netfilter/nf_conntrack_proto_udp.c
+++ b/net/netfilter/nf_conntrack_proto_udp.c
@@ -103,8 +103,7 @@
 static int udp_error(struct sk_buff *skb, unsigned int dataoff,
 		     enum ip_conntrack_info *ctinfo,
 		     int pf,
-		     unsigned int hooknum,
-		     int (*csum)(const struct sk_buff *, unsigned int))
+		     unsigned int hooknum)
 {
 	unsigned int udplen = skb->len - dataoff;
 	struct udphdr _hdr, *hdr;
@@ -136,9 +135,8 @@
 	 * and moreover root might send raw packets.
 	 * FIXME: Source route IP option packets --RR */
 	if (((pf == PF_INET && hooknum == NF_IP_PRE_ROUTING) ||
-	     (pf == PF_INET6 && hooknum == NF_IP6_PRE_ROUTING))
-	    && skb->ip_summed != CHECKSUM_UNNECESSARY
-	    && csum(skb, dataoff)) {
+	     (pf == PF_INET6 && hooknum == NF_IP6_PRE_ROUTING)) &&
+	    nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
 		if (LOG_INVALID(IPPROTO_UDP))
 			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 				"nf_ct_udp: bad UDP checksum ");
@@ -148,44 +146,6 @@
 	return NF_ACCEPT;
 }
 
-static int csum4(const struct sk_buff *skb, unsigned int dataoff)
-{
-	return csum_tcpudp_magic(skb->nh.iph->saddr, skb->nh.iph->daddr,
-				 skb->len - dataoff, IPPROTO_UDP,
-				 skb->ip_summed == CHECKSUM_HW ? skb->csum
-				 : skb_checksum(skb, dataoff,
-						skb->len - dataoff, 0));
-}
-
-static int csum6(const struct sk_buff *skb, unsigned int dataoff)
-{
-	return csum_ipv6_magic(&skb->nh.ipv6h->saddr, &skb->nh.ipv6h->daddr,
-			       skb->len - dataoff, IPPROTO_UDP,
-			       skb->ip_summed == CHECKSUM_HW
-			       ? csum_sub(skb->csum,
-					  skb_checksum(skb, 0, dataoff, 0))
-			       : skb_checksum(skb, dataoff, skb->len - dataoff,
-					      0));
-}
-
-static int udp_error4(struct sk_buff *skb,
-		      unsigned int dataoff,
-		      enum ip_conntrack_info *ctinfo,
-		      int pf,
-		      unsigned int hooknum)
-{
-	return udp_error(skb, dataoff, ctinfo, pf, hooknum, csum4);
-}
-
-static int udp_error6(struct sk_buff *skb,
-		      unsigned int dataoff,
-		      enum ip_conntrack_info *ctinfo,
-		      int pf,
-		      unsigned int hooknum)
-{
-	return udp_error(skb, dataoff, ctinfo, pf, hooknum, csum6);
-}
-
 struct nf_conntrack_protocol nf_conntrack_protocol_udp4 =
 {
 	.l3proto		= PF_INET,
@@ -197,7 +157,7 @@
 	.print_conntrack	= udp_print_conntrack,
 	.packet			= udp_packet,
 	.new			= udp_new,
-	.error			= udp_error4,
+	.error			= udp_error,
 #if defined(CONFIG_NF_CT_NETLINK) || \
     defined(CONFIG_NF_CT_NETLINK_MODULE)
 	.tuple_to_nfattr	= nf_ct_port_tuple_to_nfattr,
@@ -216,7 +176,7 @@
 	.print_conntrack	= udp_print_conntrack,
 	.packet			= udp_packet,
 	.new			= udp_new,
-	.error			= udp_error6,
+	.error			= udp_error,
 #if defined(CONFIG_NF_CT_NETLINK) || \
     defined(CONFIG_NF_CT_NETLINK_MODULE)
 	.tuple_to_nfattr	= nf_ct_port_tuple_to_nfattr,