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ipvs: handle PARTIAL_CHECKSUM
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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@verge.net.au>
Acked-by: Julius Volz <juliusv@google.com>
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Simon Horman committed Sep 8, 2008
1 parent 178f5e4 commit 503e81f
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Showing 2 changed files with 70 additions and 4 deletions.
37 changes: 35 additions & 2 deletions net/ipv4/ipvs/ip_vs_proto_tcp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -134,19 +134,42 @@ 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)
tcphoff = sizeof(struct ipv6hdr);
else
#endif
tcphoff = ip_hdrlen(skb);
oldlen = skb->len - tcphoff;

/* csum_check requires unshared skb */
if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
Expand All @@ -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);
Expand Down Expand Up @@ -204,13 +231,15 @@ 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)
tcphoff = sizeof(struct ipv6hdr);
else
#endif
tcphoff = ip_hdrlen(skb);
oldlen = skb->len - tcphoff;

/* csum_check requires unshared skb */
if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
Expand All @@ -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);
Expand Down
37 changes: 35 additions & 2 deletions net/ipv4/ipvs/ip_vs_proto_udp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -141,19 +141,42 @@ 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)
udphoff = sizeof(struct ipv6hdr);
else
#endif
udphoff = ip_hdrlen(skb);
oldlen = skb->len - udphoff;

/* csum_check requires unshared skb */
if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
Expand All @@ -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);
Expand Down Expand Up @@ -216,13 +243,15 @@ 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)
udphoff = sizeof(struct ipv6hdr);
else
#endif
udphoff = ip_hdrlen(skb);
oldlen = skb->len - udphoff;

/* csum_check requires unshared skb */
if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
Expand All @@ -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);
Expand Down

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