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Commit 0abee526 authored by Changli Gao's avatar Changli Gao Committed by Patrick McHardy
Browse files

netfilter: nf_nat: add nf_nat_csum() 



Add a static function nf_nat_csum() to replace the duplicate code in
nf_nat_mangle_udp_packet() and __nf_nat_mangle_tcp_packet().

Signed-off-by: default avatarChangli Gao <xiaosuo@gmail.com>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
parent 068e8a30

net/ipv4/netfilter/nf_nat_helper.c

+31 −45
Original line number Diff line number Diff line
@@ -153,6 +153,35 @@ void nf_nat_set_seq_adjust(struct nf_conn *ct, enum ip_conntrack_info ctinfo, 
}

EXPORT_SYMBOL_GPL(nf_nat_set_seq_adjust);



static void nf_nat_csum(struct sk_buff *skb, struct iphdr *iph, void *data,

			int datalen, __sum16 *check, int oldlen)

{

	struct rtable *rt = skb_rtable(skb);



	if (skb->ip_summed != CHECKSUM_PARTIAL) {

		if (!(rt->rt_flags & RTCF_LOCAL) &&

		    skb->dev->features & NETIF_F_V4_CSUM) {

			skb->ip_summed = CHECKSUM_PARTIAL;

			skb->csum_start = skb_headroom(skb) +

					  skb_network_offset(skb) +

					  iph->ihl * 4;

			skb->csum_offset = (void *)check - data;

			*check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,

						    datalen, iph->protocol, 0);

		} else {

			*check = 0;

			*check = csum_tcpudp_magic(iph->saddr, iph->daddr,

						   datalen, iph->protocol,

						   csum_partial(data, datalen,

								0));

			if (iph->protocol == IPPROTO_UDP && !*check)

				*check = CSUM_MANGLED_0;

		}

	} else

		inet_proto_csum_replace2(check, skb,

					 htons(oldlen), htons(datalen), 1);

}



/* Generic function for mangling variable-length address changes inside

 * NATed TCP connections (like the PORT XXX,XXX,XXX,XXX,XXX,XXX

 * command in FTP).
@@ -169,7 +198,6 @@ int __nf_nat_mangle_tcp_packet(struct sk_buff *skb, 
			       const char *rep_buffer,

			       unsigned int rep_len, bool adjust)

{

	struct rtable *rt = skb_rtable(skb);

	struct iphdr *iph;

	struct tcphdr *tcph;

	int oldlen, datalen;
@@ -192,26 +220,7 @@ int __nf_nat_mangle_tcp_packet(struct sk_buff *skb, 
			match_offset, match_len, rep_buffer, rep_len);



	datalen = skb->len - iph->ihl*4;

	if (skb->ip_summed != CHECKSUM_PARTIAL) {

		if (!(rt->rt_flags & RTCF_LOCAL) &&

		    skb->dev->features & NETIF_F_V4_CSUM) {

			skb->ip_summed = CHECKSUM_PARTIAL;

			skb->csum_start = skb_headroom(skb) +

					  skb_network_offset(skb) +

					  iph->ihl * 4;

			skb->csum_offset = offsetof(struct tcphdr, check);

			tcph->check = ~tcp_v4_check(datalen,

						    iph->saddr, iph->daddr, 0);

		} else {

			tcph->check = 0;

			tcph->check = tcp_v4_check(datalen,

						   iph->saddr, iph->daddr,

						   csum_partial(tcph,

								datalen, 0));

		}

	} else

		inet_proto_csum_replace2(&tcph->check, skb,

					 htons(oldlen), htons(datalen), 1);

	nf_nat_csum(skb, iph, tcph, datalen, &tcph->check, oldlen);



	if (adjust && rep_len != match_len)

		nf_nat_set_seq_adjust(ct, ctinfo, tcph->seq,
@@ -240,7 +249,6 @@ nf_nat_mangle_udp_packet(struct sk_buff *skb, 
			 const char *rep_buffer,

			 unsigned int rep_len)

{

	struct rtable *rt = skb_rtable(skb);

	struct iphdr *iph;

	struct udphdr *udph;

	int datalen, oldlen;
@@ -274,29 +282,7 @@ nf_nat_mangle_udp_packet(struct sk_buff *skb, 
	if (!udph->check && skb->ip_summed != CHECKSUM_PARTIAL)

		return 1;



	if (skb->ip_summed != CHECKSUM_PARTIAL) {

		if (!(rt->rt_flags & RTCF_LOCAL) &&

		    skb->dev->features & NETIF_F_V4_CSUM) {

			skb->ip_summed = CHECKSUM_PARTIAL;

			skb->csum_start = skb_headroom(skb) +

					  skb_network_offset(skb) +

					  iph->ihl * 4;

			skb->csum_offset = offsetof(struct udphdr, check);

			udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,

							 datalen, IPPROTO_UDP,

							 0);

		} else {

			udph->check = 0;

			udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr,

							datalen, IPPROTO_UDP,

							csum_partial(udph,

								     datalen, 0));

			if (!udph->check)

				udph->check = CSUM_MANGLED_0;

		}

	} else

		inet_proto_csum_replace2(&udph->check, skb,

					 htons(oldlen), htons(datalen), 1);

	nf_nat_csum(skb, iph, udph, datalen, &udph->check, oldlen);



	return 1;

}