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Commit fe6092ea authored by Patrick McHardy's avatar Patrick McHardy Committed by David S. Miller
Browse files

[NETFILTER]: nf_nat: use HW checksumming when possible 



When mangling packets forwarded to a HW checksumming capable device,
offload recalculation of the checksum instead of doing it in software.

Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c15bf6e6

net/ipv4/netfilter/nf_nat_helper.c

+37 −12
Original line number Diff line number Diff line
@@ -153,6 +153,7 @@ nf_nat_mangle_tcp_packet(struct sk_buff **pskb, 
			 const char *rep_buffer,

			 unsigned int rep_len)

{

	struct rtable *rt = (struct rtable *)(*pskb)->dst;

	struct iphdr *iph;

	struct tcphdr *tcph;

	int oldlen, datalen;
@@ -176,11 +177,22 @@ nf_nat_mangle_tcp_packet(struct sk_buff **pskb, 


	datalen = (*pskb)->len - iph->ihl*4;

	if ((*pskb)->ip_summed != CHECKSUM_PARTIAL) {

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

		    (*pskb)->dev->features & NETIF_F_ALL_CSUM) {

			(*pskb)->ip_summed = CHECKSUM_PARTIAL;

			(*pskb)->csum_start = skb_headroom(*pskb) +

					      skb_network_offset(*pskb) +

					      iph->ihl * 4;

			(*pskb)->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((char *)tcph,

								datalen, 0));

		}

	} else

		nf_proto_csum_replace2(&tcph->check, *pskb,

				       htons(oldlen), htons(datalen), 1);
@@ -217,6 +229,7 @@ nf_nat_mangle_udp_packet(struct sk_buff **pskb, 
			 const char *rep_buffer,

			 unsigned int rep_len)

{

	struct rtable *rt = (struct rtable *)(*pskb)->dst;

	struct iphdr *iph;

	struct udphdr *udph;

	int datalen, oldlen;
@@ -251,6 +264,17 @@ nf_nat_mangle_udp_packet(struct sk_buff **pskb, 
		return 1;



	if ((*pskb)->ip_summed != CHECKSUM_PARTIAL) {

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

		    (*pskb)->dev->features & NETIF_F_ALL_CSUM) {

			(*pskb)->ip_summed = CHECKSUM_PARTIAL;

			(*pskb)->csum_start = skb_headroom(*pskb) +

					      skb_network_offset(*pskb) +

					      iph->ihl * 4;

			(*pskb)->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,
@@ -258,6 +282,7 @@ nf_nat_mangle_udp_packet(struct sk_buff **pskb, 
								     datalen, 0));

			if (!udph->check)

				udph->check = CSUM_MANGLED_0;

		}

	} else

		nf_proto_csum_replace2(&udph->check, *pskb,

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