netfilter: nat: remove csum_recalc hook

We can now use direct calls.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_nat_l3proto.h

@@ -4,15 +4,14 @@
 
 struct nf_nat_l3proto {
 	u8	l3proto;
-
-	void	(*csum_recalc)(struct sk_buff *skb, u8 proto,
-			       void *data, __sum16 *check,
-			       int datalen, int oldlen);
 };
 
 unsigned int nf_nat_manip_pkt(struct sk_buff *skb, struct nf_conn *ct,
 			      enum nf_nat_manip_type mtype,
 			      enum ip_conntrack_dir dir);
+void nf_nat_csum_recalc(struct sk_buff *skb,
+			u8 nfproto, u8 proto, void *data, __sum16 *check,
+			int datalen, int oldlen);
 
 int nf_nat_l3proto_register(const struct nf_nat_l3proto *);
 void nf_nat_l3proto_unregister(const struct nf_nat_l3proto *);

net/netfilter/nf_nat_helper.c

@@ -97,7 +97,6 @@ bool __nf_nat_mangle_tcp_packet(struct sk_buff *skb,
 				const char *rep_buffer,
 				unsigned int rep_len, bool adjust)
 {
-	const struct nf_nat_l3proto *l3proto;
 	struct tcphdr *tcph;
 	int oldlen, datalen;
 
@@ -117,9 +116,8 @@ bool __nf_nat_mangle_tcp_packet(struct sk_buff *skb,
 
 	datalen = skb->len - protoff;
 
-	l3proto = __nf_nat_l3proto_find(nf_ct_l3num(ct));
-	l3proto->csum_recalc(skb, IPPROTO_TCP, tcph, &tcph->check,
-			     datalen, oldlen);
+	nf_nat_csum_recalc(skb, nf_ct_l3num(ct), IPPROTO_TCP,
+			   tcph, &tcph->check, datalen, oldlen);
 
 	if (adjust && rep_len != match_len)
 		nf_ct_seqadj_set(ct, ctinfo, tcph->seq,
@@ -149,7 +147,6 @@ nf_nat_mangle_udp_packet(struct sk_buff *skb,
 			 const char *rep_buffer,
 			 unsigned int rep_len)
 {
-	const struct nf_nat_l3proto *l3proto;
 	struct udphdr *udph;
 	int datalen, oldlen;
 
@@ -175,9 +172,8 @@ nf_nat_mangle_udp_packet(struct sk_buff *skb,
 	if (!udph->check && skb->ip_summed != CHECKSUM_PARTIAL)
 		return true;
 
-	l3proto = __nf_nat_l3proto_find(nf_ct_l3num(ct));
-	l3proto->csum_recalc(skb, IPPROTO_UDP, udph, &udph->check,
-			     datalen, oldlen);
+	nf_nat_csum_recalc(skb, nf_ct_l3num(ct), IPPROTO_TCP,
+			   udph, &udph->check, datalen, oldlen);
 
 	return true;
 }

net/netfilter/nf_nat_proto.c

@@ -535,9 +535,28 @@ static void nf_nat_ipv6_csum_recalc(struct sk_buff *skb,
 }
 #endif
 
+void nf_nat_csum_recalc(struct sk_buff *skb,
+			u8 nfproto, u8 proto, void *data, __sum16 *check,
+			int datalen, int oldlen)
+{
+	switch (nfproto) {
+	case NFPROTO_IPV4:
+		nf_nat_ipv4_csum_recalc(skb, proto, data, check,
+					datalen, oldlen);
+		return;
+#if IS_ENABLED(CONFIG_IPV6)
+	case NFPROTO_IPV6:
+		nf_nat_ipv6_csum_recalc(skb, proto, data, check,
+					datalen, oldlen);
+		return;
+#endif
+	}
+
+	WARN_ON_ONCE(1);
+}
+
 static const struct nf_nat_l3proto nf_nat_l3proto_ipv4 = {
 	.l3proto		= NFPROTO_IPV4,
-	.csum_recalc		= nf_nat_ipv4_csum_recalc,
 };
 
 int nf_nat_icmp_reply_translation(struct sk_buff *skb,
@@ -788,7 +807,6 @@ void nf_nat_l3proto_exit(void)
 #if IS_ENABLED(CONFIG_IPV6)
 static const struct nf_nat_l3proto nf_nat_l3proto_ipv6 = {
 	.l3proto		= NFPROTO_IPV6,
-	.csum_recalc		= nf_nat_ipv6_csum_recalc,
 };
 
 int nf_nat_icmpv6_reply_translation(struct sk_buff *skb,