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: Simon Horman <horms@xxxxxxxxxxxx>
---
This patch implements *_partial_csum_update() in the style
of the existing *_fast_csum_update() code. A subsequent patch
will reimplement these functions in terms of the more standard
inet_proto_csum_replace*() functions.
net/ipv4/ipvs/ip_vs_proto_tcp.c | 37 +++++++++++++++++++++++++++++++++++--
net/ipv4/ipvs/ip_vs_proto_udp.c | 37 +++++++++++++++++++++++++++++++++++--
2 files changed, 70 insertions(+), 4 deletions(-)
Index: lvs-2.6/net/ipv4/ipvs/ip_vs_proto_tcp.c
===================================================================
--- lvs-2.6.orig/net/ipv4/ipvs/ip_vs_proto_tcp.c 2008-09-08 11:46:28.000000000 +1000
+++ lvs-2.6/net/ipv4/ipvs/ip_vs_proto_tcp.c 2008-09-08 11:56:10.000000000 +1000
@@ -134,12 +134,34 @@ tcp_fast_csum_update(int af, struct 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);
Index: lvs-2.6/net/ipv4/ipvs/ip_vs_proto_udp.c
===================================================================
--- lvs-2.6.orig/net/ipv4/ipvs/ip_vs_proto_udp.c 2008-09-08 11:46:28.000000000 +1000
+++ lvs-2.6/net/ipv4/ipvs/ip_vs_proto_udp.c 2008-09-08 11:56:10.000000000 +1000
@@ -141,12 +141,34 @@ udp_fast_csum_update(int af, struct udph
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);
--
--
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