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|
/*
* ip_vs_proto_tcp.c: TCP load balancing support for IPVS
*
* Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
* Julian Anastasov <ja@ssi.bg>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Changes: Hans Schillstrom <hans.schillstrom@ericsson.com>
*
* Network name space (netns) aware.
* Global data moved to netns i.e struct netns_ipvs
* tcp_timeouts table has copy per netns in a hash table per
* protocol ip_vs_proto_data and is handled by netns
*/
#define KMSG_COMPONENT "IPVS"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/kernel.h>
#include <linux/ip.h>
#include <linux/tcp.h> /* for tcphdr */
#include <net/ip.h>
#include <net/tcp.h> /* for csum_tcpudp_magic */
#include <net/ip6_checksum.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <net/ip_vs.h>
static int
tcp_conn_schedule(int af, struct sk_buff *skb, struct ip_vs_proto_data *pd,
int *verdict, struct ip_vs_conn **cpp,
struct ip_vs_iphdr *iph)
{
struct net *net;
struct ip_vs_service *svc;
struct tcphdr _tcph, *th;
struct netns_ipvs *ipvs;
th = skb_header_pointer(skb, iph->len, sizeof(_tcph), &_tcph);
if (th == NULL) {
*verdict = NF_DROP;
return 0;
}
net = skb_net(skb);
ipvs = net_ipvs(net);
/* No !th->ack check to allow scheduling on SYN+ACK for Active FTP */
rcu_read_lock();
if ((th->syn || sysctl_sloppy_tcp(ipvs)) && !th->rst &&
(svc = ip_vs_service_find(net, af, skb->mark, iph->protocol,
&iph->daddr, th->dest))) {
int ignored;
if (ip_vs_todrop(ipvs)) {
/*
* It seems that we are very loaded.
* We have to drop this packet :(
*/
rcu_read_unlock();
*verdict = NF_DROP;
return 0;
}
/*
* Let the virtual server select a real server for the
* incoming connection, and create a connection entry.
*/
*cpp = ip_vs_schedule(svc, skb, pd, &ignored, iph);
if (!*cpp && ignored <= 0) {
if (!ignored)
*verdict = ip_vs_leave(svc, skb, pd, iph);
else
*verdict = NF_DROP;
rcu_read_unlock();
return 0;
}
}
rcu_read_unlock();
/* NF_ACCEPT */
return 1;
}
static inline void
tcp_fast_csum_update(int af, struct tcphdr *tcph,
const union nf_inet_addr *oldip,
const union nf_inet_addr *newip,
__be16 oldport, __be16 newport)
{
#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(oldport, newport,
~csum_unfold(tcph->check))));
else
#endif
tcph->check =
csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
ip_vs_check_diff2(oldport, newport,
~csum_unfold(tcph->check))));
}
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 ip_vs_iphdr *iph)
{
struct tcphdr *tcph;
unsigned int tcphoff = iph->len;
int oldlen;
int payload_csum = 0;
#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6 && iph->fragoffs)
return 1;
#endif
oldlen = skb->len - tcphoff;
/* csum_check requires unshared skb */
if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
return 0;
if (unlikely(cp->app != NULL)) {
int ret;
/* Some checks before mangling */
if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
return 0;
/* Call application helper if needed */
if (!(ret = ip_vs_app_pkt_out(cp, skb)))
return 0;
/* ret=2: csum update is needed after payload mangling */
if (ret == 1)
oldlen = skb->len - tcphoff;
else
payload_csum = 1;
}
tcph = (void *)skb_network_header(skb) + tcphoff;
tcph->source = cp->vport;
/* Adjust TCP checksums */
if (skb->ip_summed == CHECKSUM_PARTIAL) {
tcp_partial_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,
htons(oldlen),
htons(skb->len - tcphoff));
} else if (!payload_csum) {
/* 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);
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = (cp->app && pp->csum_check) ?
CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
} else {
/* full checksum calculation */
tcph->check = 0;
skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6)
tcph->check = csum_ipv6_magic(&cp->vaddr.in6,
&
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