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 --- 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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