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563 lines
13 KiB
563 lines
13 KiB
/*
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* ip_vs_xmit.c: various packet transmitters for IPVS
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*
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* Version: $Id: ip_vs_xmit.c,v 1.2 2002/11/30 01:50:35 wensong Exp $
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*
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* Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
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* Julian Anastasov <ja@ssi.bg>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Changes:
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*
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*/
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#include <linux/kernel.h>
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#include <linux/ip.h>
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#include <linux/tcp.h> /* for tcphdr */
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#include <net/tcp.h> /* for csum_tcpudp_magic */
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#include <net/udp.h>
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#include <net/icmp.h> /* for icmp_send */
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#include <net/route.h> /* for ip_route_output */
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <net/ip_vs.h>
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/*
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* Destination cache to speed up outgoing route lookup
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*/
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static inline void
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__ip_vs_dst_set(struct ip_vs_dest *dest, u32 rtos, struct dst_entry *dst)
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{
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struct dst_entry *old_dst;
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old_dst = dest->dst_cache;
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dest->dst_cache = dst;
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dest->dst_rtos = rtos;
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dst_release(old_dst);
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}
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static inline struct dst_entry *
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__ip_vs_dst_check(struct ip_vs_dest *dest, u32 rtos, u32 cookie)
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{
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struct dst_entry *dst = dest->dst_cache;
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if (!dst)
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return NULL;
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if ((dst->obsolete || rtos != dest->dst_rtos) &&
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dst->ops->check(dst, cookie) == NULL) {
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dest->dst_cache = NULL;
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dst_release(dst);
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return NULL;
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}
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dst_hold(dst);
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return dst;
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}
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static inline struct rtable *
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__ip_vs_get_out_rt(struct ip_vs_conn *cp, u32 rtos)
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{
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struct rtable *rt; /* Route to the other host */
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struct ip_vs_dest *dest = cp->dest;
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if (dest) {
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spin_lock(&dest->dst_lock);
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if (!(rt = (struct rtable *)
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__ip_vs_dst_check(dest, rtos, 0))) {
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struct flowi fl = {
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.oif = 0,
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.nl_u = {
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.ip4_u = {
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.daddr = dest->addr,
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.saddr = 0,
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.tos = rtos, } },
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};
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if (ip_route_output_key(&rt, &fl)) {
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spin_unlock(&dest->dst_lock);
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IP_VS_DBG_RL("ip_route_output error, "
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"dest: %u.%u.%u.%u\n",
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NIPQUAD(dest->addr));
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return NULL;
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}
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__ip_vs_dst_set(dest, rtos, dst_clone(&rt->u.dst));
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IP_VS_DBG(10, "new dst %u.%u.%u.%u, refcnt=%d, rtos=%X\n",
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NIPQUAD(dest->addr),
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atomic_read(&rt->u.dst.__refcnt), rtos);
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}
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spin_unlock(&dest->dst_lock);
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} else {
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struct flowi fl = {
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.oif = 0,
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.nl_u = {
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.ip4_u = {
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.daddr = cp->daddr,
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.saddr = 0,
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.tos = rtos, } },
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};
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if (ip_route_output_key(&rt, &fl)) {
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IP_VS_DBG_RL("ip_route_output error, dest: "
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"%u.%u.%u.%u\n", NIPQUAD(cp->daddr));
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return NULL;
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}
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}
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return rt;
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}
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/*
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* Release dest->dst_cache before a dest is removed
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*/
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void
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ip_vs_dst_reset(struct ip_vs_dest *dest)
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{
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struct dst_entry *old_dst;
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old_dst = dest->dst_cache;
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dest->dst_cache = NULL;
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dst_release(old_dst);
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}
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#define IP_VS_XMIT(skb, rt) \
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do { \
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(skb)->ipvs_property = 1; \
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(skb)->ip_summed = CHECKSUM_NONE; \
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NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, (skb), NULL, \
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(rt)->u.dst.dev, dst_output); \
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} while (0)
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/*
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* NULL transmitter (do nothing except return NF_ACCEPT)
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*/
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int
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ip_vs_null_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
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struct ip_vs_protocol *pp)
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{
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/* we do not touch skb and do not need pskb ptr */
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return NF_ACCEPT;
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}
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/*
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* Bypass transmitter
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* Let packets bypass the destination when the destination is not
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* available, it may be only used in transparent cache cluster.
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*/
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int
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ip_vs_bypass_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
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struct ip_vs_protocol *pp)
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{
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struct rtable *rt; /* Route to the other host */
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struct iphdr *iph = ip_hdr(skb);
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u8 tos = iph->tos;
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int mtu;
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struct flowi fl = {
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.oif = 0,
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.nl_u = {
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.ip4_u = {
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.daddr = iph->daddr,
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.saddr = 0,
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.tos = RT_TOS(tos), } },
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};
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EnterFunction(10);
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if (ip_route_output_key(&rt, &fl)) {
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IP_VS_DBG_RL("ip_vs_bypass_xmit(): ip_route_output error, "
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"dest: %u.%u.%u.%u\n", NIPQUAD(iph->daddr));
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goto tx_error_icmp;
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}
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/* MTU checking */
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mtu = dst_mtu(&rt->u.dst);
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if ((skb->len > mtu) && (iph->frag_off & htons(IP_DF))) {
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ip_rt_put(rt);
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icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
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IP_VS_DBG_RL("ip_vs_bypass_xmit(): frag needed\n");
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goto tx_error;
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}
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/*
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* Call ip_send_check because we are not sure it is called
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* after ip_defrag. Is copy-on-write needed?
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*/
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if (unlikely((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)) {
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ip_rt_put(rt);
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return NF_STOLEN;
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}
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ip_send_check(ip_hdr(skb));
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/* drop old route */
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dst_release(skb->dst);
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skb->dst = &rt->u.dst;
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/* Another hack: avoid icmp_send in ip_fragment */
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skb->local_df = 1;
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IP_VS_XMIT(skb, rt);
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LeaveFunction(10);
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return NF_STOLEN;
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tx_error_icmp:
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dst_link_failure(skb);
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tx_error:
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kfree_skb(skb);
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LeaveFunction(10);
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return NF_STOLEN;
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}
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/*
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* NAT transmitter (only for outside-to-inside nat forwarding)
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* Not used for related ICMP
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*/
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int
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ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
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struct ip_vs_protocol *pp)
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{
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struct rtable *rt; /* Route to the other host */
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int mtu;
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struct iphdr *iph = ip_hdr(skb);
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EnterFunction(10);
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/* check if it is a connection of no-client-port */
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if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT)) {
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__be16 _pt, *p;
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p = skb_header_pointer(skb, iph->ihl*4, sizeof(_pt), &_pt);
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if (p == NULL)
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goto tx_error;
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ip_vs_conn_fill_cport(cp, *p);
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IP_VS_DBG(10, "filled cport=%d\n", ntohs(*p));
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}
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if (!(rt = __ip_vs_get_out_rt(cp, RT_TOS(iph->tos))))
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goto tx_error_icmp;
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/* MTU checking */
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mtu = dst_mtu(&rt->u.dst);
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if ((skb->len > mtu) && (iph->frag_off & htons(IP_DF))) {
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ip_rt_put(rt);
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icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
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IP_VS_DBG_RL_PKT(0, pp, skb, 0, "ip_vs_nat_xmit(): frag needed for");
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goto tx_error;
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}
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/* copy-on-write the packet before mangling it */
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if (!ip_vs_make_skb_writable(&skb, sizeof(struct iphdr)))
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goto tx_error_put;
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if (skb_cow(skb, rt->u.dst.dev->hard_header_len))
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goto tx_error_put;
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/* drop old route */
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dst_release(skb->dst);
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skb->dst = &rt->u.dst;
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/* mangle the packet */
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if (pp->dnat_handler && !pp->dnat_handler(&skb, pp, cp))
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goto tx_error;
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ip_hdr(skb)->daddr = cp->daddr;
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ip_send_check(ip_hdr(skb));
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IP_VS_DBG_PKT(10, pp, skb, 0, "After DNAT");
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/* FIXME: when application helper enlarges the packet and the length
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is larger than the MTU of outgoing device, there will be still
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MTU problem. */
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/* Another hack: avoid icmp_send in ip_fragment */
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skb->local_df = 1;
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IP_VS_XMIT(skb, rt);
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LeaveFunction(10);
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return NF_STOLEN;
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tx_error_icmp:
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dst_link_failure(skb);
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tx_error:
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LeaveFunction(10);
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kfree_skb(skb);
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return NF_STOLEN;
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tx_error_put:
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ip_rt_put(rt);
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goto tx_error;
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}
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/*
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* IP Tunneling transmitter
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*
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* This function encapsulates the packet in a new IP packet, its
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* destination will be set to cp->daddr. Most code of this function
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* is taken from ipip.c.
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*
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* It is used in VS/TUN cluster. The load balancer selects a real
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* server from a cluster based on a scheduling algorithm,
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* encapsulates the request packet and forwards it to the selected
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* server. For example, all real servers are configured with
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* "ifconfig tunl0 <Virtual IP Address> up". When the server receives
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* the encapsulated packet, it will decapsulate the packet, processe
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* the request and return the response packets directly to the client
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* without passing the load balancer. This can greatly increase the
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* scalability of virtual server.
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*
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* Used for ANY protocol
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*/
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int
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ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
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struct ip_vs_protocol *pp)
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{
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struct rtable *rt; /* Route to the other host */
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struct net_device *tdev; /* Device to other host */
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struct iphdr *old_iph = ip_hdr(skb);
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u8 tos = old_iph->tos;
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__be16 df = old_iph->frag_off;
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sk_buff_data_t old_transport_header = skb->transport_header;
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struct iphdr *iph; /* Our new IP header */
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int max_headroom; /* The extra header space needed */
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int mtu;
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EnterFunction(10);
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if (skb->protocol != htons(ETH_P_IP)) {
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IP_VS_DBG_RL("ip_vs_tunnel_xmit(): protocol error, "
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"ETH_P_IP: %d, skb protocol: %d\n",
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htons(ETH_P_IP), skb->protocol);
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goto tx_error;
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}
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if (!(rt = __ip_vs_get_out_rt(cp, RT_TOS(tos))))
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goto tx_error_icmp;
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tdev = rt->u.dst.dev;
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mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
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if (mtu < 68) {
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ip_rt_put(rt);
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IP_VS_DBG_RL("ip_vs_tunnel_xmit(): mtu less than 68\n");
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goto tx_error;
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}
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if (skb->dst)
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skb->dst->ops->update_pmtu(skb->dst, mtu);
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df |= (old_iph->frag_off & htons(IP_DF));
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if ((old_iph->frag_off & htons(IP_DF))
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&& mtu < ntohs(old_iph->tot_len)) {
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icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
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ip_rt_put(rt);
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IP_VS_DBG_RL("ip_vs_tunnel_xmit(): frag needed\n");
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goto tx_error;
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}
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/*
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* Okay, now see if we can stuff it in the buffer as-is.
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*/
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max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct iphdr);
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if (skb_headroom(skb) < max_headroom
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|| skb_cloned(skb) || skb_shared(skb)) {
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struct sk_buff *new_skb =
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skb_realloc_headroom(skb, max_headroom);
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if (!new_skb) {
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ip_rt_put(rt);
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kfree_skb(skb);
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IP_VS_ERR_RL("ip_vs_tunnel_xmit(): no memory\n");
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return NF_STOLEN;
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}
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kfree_skb(skb);
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skb = new_skb;
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old_iph = ip_hdr(skb);
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}
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skb->transport_header = old_transport_header;
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/* fix old IP header checksum */
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ip_send_check(old_iph);
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skb_push(skb, sizeof(struct iphdr));
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skb_reset_network_header(skb);
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memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
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/* drop old route */
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dst_release(skb->dst);
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skb->dst = &rt->u.dst;
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/*
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* Push down and install the IPIP header.
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*/
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iph = ip_hdr(skb);
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iph->version = 4;
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iph->ihl = sizeof(struct iphdr)>>2;
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iph->frag_off = df;
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iph->protocol = IPPROTO_IPIP;
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iph->tos = tos;
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iph->daddr = rt->rt_dst;
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iph->saddr = rt->rt_src;
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iph->ttl = old_iph->ttl;
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iph->tot_len = htons(skb->len);
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ip_select_ident(iph, &rt->u.dst, NULL);
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ip_send_check(iph);
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/* Another hack: avoid icmp_send in ip_fragment */
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skb->local_df = 1;
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IP_VS_XMIT(skb, rt);
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LeaveFunction(10);
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return NF_STOLEN;
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tx_error_icmp:
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dst_link_failure(skb);
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tx_error:
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kfree_skb(skb);
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LeaveFunction(10);
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return NF_STOLEN;
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}
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/*
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* Direct Routing transmitter
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* Used for ANY protocol
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*/
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int
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ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
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struct ip_vs_protocol *pp)
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{
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struct rtable *rt; /* Route to the other host */
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struct iphdr *iph = ip_hdr(skb);
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int mtu;
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EnterFunction(10);
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if (!(rt = __ip_vs_get_out_rt(cp, RT_TOS(iph->tos))))
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goto tx_error_icmp;
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/* MTU checking */
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mtu = dst_mtu(&rt->u.dst);
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if ((iph->frag_off & htons(IP_DF)) && skb->len > mtu) {
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icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
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ip_rt_put(rt);
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IP_VS_DBG_RL("ip_vs_dr_xmit(): frag needed\n");
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goto tx_error;
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}
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/*
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* Call ip_send_check because we are not sure it is called
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* after ip_defrag. Is copy-on-write needed?
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*/
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if (unlikely((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)) {
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ip_rt_put(rt);
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return NF_STOLEN;
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}
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ip_send_check(ip_hdr(skb));
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/* drop old route */
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dst_release(skb->dst);
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skb->dst = &rt->u.dst;
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/* Another hack: avoid icmp_send in ip_fragment */
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skb->local_df = 1;
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IP_VS_XMIT(skb, rt);
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LeaveFunction(10);
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return NF_STOLEN;
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tx_error_icmp:
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dst_link_failure(skb);
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tx_error:
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kfree_skb(skb);
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LeaveFunction(10);
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return NF_STOLEN;
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}
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|
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/*
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* ICMP packet transmitter
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* called by the ip_vs_in_icmp
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*/
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int
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ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
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struct ip_vs_protocol *pp, int offset)
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{
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struct rtable *rt; /* Route to the other host */
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int mtu;
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int rc;
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EnterFunction(10);
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/* The ICMP packet for VS/TUN, VS/DR and LOCALNODE will be
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forwarded directly here, because there is no need to
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translate address/port back */
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if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ) {
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if (cp->packet_xmit)
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rc = cp->packet_xmit(skb, cp, pp);
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else
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rc = NF_ACCEPT;
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/* do not touch skb anymore */
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atomic_inc(&cp->in_pkts);
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goto out;
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}
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/*
|
|
* mangle and send the packet here (only for VS/NAT)
|
|
*/
|
|
|
|
if (!(rt = __ip_vs_get_out_rt(cp, RT_TOS(ip_hdr(skb)->tos))))
|
|
goto tx_error_icmp;
|
|
|
|
/* MTU checking */
|
|
mtu = dst_mtu(&rt->u.dst);
|
|
if ((skb->len > mtu) && (ip_hdr(skb)->frag_off & htons(IP_DF))) {
|
|
ip_rt_put(rt);
|
|
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
|
|
IP_VS_DBG_RL("ip_vs_in_icmp(): frag needed\n");
|
|
goto tx_error;
|
|
}
|
|
|
|
/* copy-on-write the packet before mangling it */
|
|
if (!ip_vs_make_skb_writable(&skb, offset))
|
|
goto tx_error_put;
|
|
|
|
if (skb_cow(skb, rt->u.dst.dev->hard_header_len))
|
|
goto tx_error_put;
|
|
|
|
/* drop the old route when skb is not shared */
|
|
dst_release(skb->dst);
|
|
skb->dst = &rt->u.dst;
|
|
|
|
ip_vs_nat_icmp(skb, pp, cp, 0);
|
|
|
|
/* Another hack: avoid icmp_send in ip_fragment */
|
|
skb->local_df = 1;
|
|
|
|
IP_VS_XMIT(skb, rt);
|
|
|
|
rc = NF_STOLEN;
|
|
goto out;
|
|
|
|
tx_error_icmp:
|
|
dst_link_failure(skb);
|
|
tx_error:
|
|
dev_kfree_skb(skb);
|
|
rc = NF_STOLEN;
|
|
out:
|
|
LeaveFunction(10);
|
|
return rc;
|
|
tx_error_put:
|
|
ip_rt_put(rt);
|
|
goto tx_error;
|
|
}
|
|
|