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Commit 503e81f6 authored by Simon Horman's avatar Simon Horman
Browse files

ipvs: handle PARTIAL_CHECKSUM 



Now that LVS can load balance locally generated traffic, packets may come
from the loopback device and thus may have a partial checksum.

The existing code allows for the case where there is no checksum at all for
TCP, however Herbert Xu has confirmed that this is not legal.

Signed-off-by: default avatarSimon Horman <horms@verge.net.au>
Acked-by: default avatarJulius Volz <juliusv@google.com>
parent 178f5e49

net/ipv4/ipvs/ip_vs_proto_tcp.c

+35 −2
Original line number Diff line number Diff line
@@ -134,12 +134,34 @@ tcp_fast_csum_update(int af, struct tcphdr *tcph, 
}





static inline void

tcp_partial_csum_update(int af, struct tcphdr *tcph,

		     const union nf_inet_addr *oldip,

		     const union nf_inet_addr *newip,

		     __be16 oldlen, __be16 newlen)

{

#ifdef CONFIG_IP_VS_IPV6

	if (af == AF_INET6)

		tcph->check =

			csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,

					 ip_vs_check_diff2(oldlen, newlen,

						~csum_unfold(tcph->check))));

	else

#endif

	tcph->check =

		csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,

				ip_vs_check_diff2(oldlen, newlen,

						~csum_unfold(tcph->check))));

}





static int

tcp_snat_handler(struct sk_buff *skb,

		 struct ip_vs_protocol *pp, struct ip_vs_conn *cp)

{

	struct tcphdr *tcph;

	unsigned int tcphoff;

	int oldlen;



#ifdef CONFIG_IP_VS_IPV6

	if (cp->af == AF_INET6)
@@ -147,6 +169,7 @@ tcp_snat_handler(struct sk_buff *skb, 
	else

#endif

		tcphoff = ip_hdrlen(skb);

	oldlen = skb->len - tcphoff;



	/* csum_check requires unshared skb */

	if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
@@ -166,7 +189,11 @@ tcp_snat_handler(struct sk_buff *skb, 
	tcph->source = cp->vport;



	/* Adjust TCP checksums */

	if (!cp->app && (tcph->check != 0)) {

	if (skb->ip_summed == CHECKSUM_PARTIAL) {

		tcp_partial_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,

					htonl(oldlen),

					htonl(skb->len - tcphoff));

	} else if (!cp->app) {

		/* Only port and addr are changed, do fast csum update */

		tcp_fast_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,

				     cp->dport, cp->vport);
@@ -204,6 +231,7 @@ tcp_dnat_handler(struct sk_buff *skb, 
{

	struct tcphdr *tcph;

	unsigned int tcphoff;

	int oldlen;



#ifdef CONFIG_IP_VS_IPV6

	if (cp->af == AF_INET6)
@@ -211,6 +239,7 @@ tcp_dnat_handler(struct sk_buff *skb, 
	else

#endif

		tcphoff = ip_hdrlen(skb);

	oldlen = skb->len - tcphoff;



	/* csum_check requires unshared skb */

	if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
@@ -235,7 +264,11 @@ tcp_dnat_handler(struct sk_buff *skb, 
	/*

	 *	Adjust TCP checksums

	 */

	if (!cp->app && (tcph->check != 0)) {

	if (skb->ip_summed == CHECKSUM_PARTIAL) {

		tcp_partial_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,

					htonl(oldlen),

					htonl(skb->len - tcphoff));

	} else if (!cp->app) {

		/* Only port and addr are changed, do fast csum update */

		tcp_fast_csum_update(cp->af, tcph, &cp->vaddr, &cp->daddr,

				     cp->vport, cp->dport);

net/ipv4/ipvs/ip_vs_proto_udp.c

+35 −2
Original line number Diff line number Diff line
@@ -141,12 +141,34 @@ udp_fast_csum_update(int af, struct udphdr *uhdr, 
		uhdr->check = CSUM_MANGLED_0;

}



static inline void

udp_partial_csum_update(int af, struct udphdr *uhdr,

		     const union nf_inet_addr *oldip,

		     const union nf_inet_addr *newip,

		     __be16 oldlen, __be16 newlen)

{

#ifdef CONFIG_IP_VS_IPV6

	if (af == AF_INET6)

		uhdr->check =

			csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,

					 ip_vs_check_diff2(oldlen, newlen,

						~csum_unfold(uhdr->check))));

	else

#endif

	uhdr->check =

		csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,

				ip_vs_check_diff2(oldlen, newlen,

						~csum_unfold(uhdr->check))));

}





static int

udp_snat_handler(struct sk_buff *skb,

		 struct ip_vs_protocol *pp, struct ip_vs_conn *cp)

{

	struct udphdr *udph;

	unsigned int udphoff;

	int oldlen;



#ifdef CONFIG_IP_VS_IPV6

	if (cp->af == AF_INET6)
@@ -154,6 +176,7 @@ udp_snat_handler(struct sk_buff *skb, 
	else

#endif

		udphoff = ip_hdrlen(skb);

	oldlen = skb->len - udphoff;



	/* csum_check requires unshared skb */

	if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
@@ -177,7 +200,11 @@ udp_snat_handler(struct sk_buff *skb, 
	/*

	 *	Adjust UDP checksums

	 */

	if (!cp->app && (udph->check != 0)) {

	if (skb->ip_summed == CHECKSUM_PARTIAL) {

		udp_partial_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,

					htonl(oldlen),

					htonl(skb->len - udphoff));

	} else if (!cp->app && (udph->check != 0)) {

		/* Only port and addr are changed, do fast csum update */

		udp_fast_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,

				     cp->dport, cp->vport);
@@ -216,6 +243,7 @@ udp_dnat_handler(struct sk_buff *skb, 
{

	struct udphdr *udph;

	unsigned int udphoff;

	int oldlen;



#ifdef CONFIG_IP_VS_IPV6

	if (cp->af == AF_INET6)
@@ -223,6 +251,7 @@ udp_dnat_handler(struct sk_buff *skb, 
	else

#endif

		udphoff = ip_hdrlen(skb);

	oldlen = skb->len - udphoff;



	/* csum_check requires unshared skb */

	if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
@@ -247,7 +276,11 @@ udp_dnat_handler(struct sk_buff *skb, 
	/*

	 *	Adjust UDP checksums

	 */

	if (!cp->app && (udph->check != 0)) {

	if (skb->ip_summed == CHECKSUM_PARTIAL) {

		udp_partial_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,

					htonl(oldlen),

					htonl(skb->len - udphoff));

	} else if (!cp->app && (udph->check != 0)) {

		/* Only port and addr are changed, do fast csum update */

		udp_fast_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,

				     cp->vport, cp->dport);