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linux/net/ipv4/ipvs/ip_vs_xmit.c

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/*
* ip_vs_xmit.c: various packet transmitters for IPVS
*
* Version: $Id: ip_vs_xmit.c,v 1.2 2002/11/30 01:50:35 wensong Exp $
*
* 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:
*
*/
#include <linux/kernel.h>
#include <linux/ip.h>
#include <linux/tcp.h> /* for tcphdr */
#include <net/tcp.h> /* for csum_tcpudp_magic */
#include <net/udp.h>
#include <net/icmp.h> /* for icmp_send */
#include <net/route.h> /* for ip_route_output */
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <net/ip_vs.h>
/*
* Destination cache to speed up outgoing route lookup
*/
static inline void
__ip_vs_dst_set(struct ip_vs_dest *dest, u32 rtos, struct dst_entry *dst)
{
struct dst_entry *old_dst;
old_dst = dest->dst_cache;
dest->dst_cache = dst;
dest->dst_rtos = rtos;
dst_release(old_dst);
}
static inline struct dst_entry *
__ip_vs_dst_check(struct ip_vs_dest *dest, u32 rtos, u32 cookie)
{
struct dst_entry *dst = dest->dst_cache;
if (!dst)
return NULL;
if ((dst->obsolete || rtos != dest->dst_rtos) &&
dst->ops->check(dst, cookie) == NULL) {
dest->dst_cache = NULL;
dst_release(dst);
return NULL;
}
dst_hold(dst);
return dst;
}
static inline struct rtable *
__ip_vs_get_out_rt(struct ip_vs_conn *cp, u32 rtos)
{
struct rtable *rt; /* Route to the other host */
struct ip_vs_dest *dest = cp->dest;
if (dest) {
spin_lock(&dest->dst_lock);
if (!(rt = (struct rtable *)
__ip_vs_dst_check(dest, rtos, 0))) {
struct flowi fl = {
.oif = 0,
.nl_u = {
.ip4_u = {
.daddr = dest->addr,
.saddr = 0,
.tos = rtos, } },
};
if (ip_route_output_key(&rt, &fl)) {
spin_unlock(&dest->dst_lock);
IP_VS_DBG_RL("ip_route_output error, "
"dest: %u.%u.%u.%u\n",
NIPQUAD(dest->addr));
return NULL;
}
__ip_vs_dst_set(dest, rtos, dst_clone(&rt->u.dst));
IP_VS_DBG(10, "new dst %u.%u.%u.%u, refcnt=%d, rtos=%X\n",
NIPQUAD(dest->addr),
atomic_read(&rt->u.dst.__refcnt), rtos);
}
spin_unlock(&dest->dst_lock);
} else {
struct flowi fl = {
.oif = 0,
.nl_u = {
.ip4_u = {
.daddr = cp->daddr,
.saddr = 0,
.tos = rtos, } },
};
if (ip_route_output_key(&rt, &fl)) {
IP_VS_DBG_RL("ip_route_output error, dest: "
"%u.%u.%u.%u\n", NIPQUAD(cp->daddr));
return NULL;
}
}
return rt;
}
/*
* Release dest->dst_cache before a dest is removed
*/
void
ip_vs_dst_reset(struct ip_vs_dest *dest)
{
struct dst_entry *old_dst;
old_dst = dest->dst_cache;
dest->dst_cache = NULL;
dst_release(old_dst);
}
#define IP_VS_XMIT(skb, rt) \
do { \
(skb)->ipvs_property = 1; \
(skb)->ip_summed = CHECKSUM_NONE; \
NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, (skb), NULL, \
(rt)->u.dst.dev, dst_output); \
} while (0)
/*
* NULL transmitter (do nothing except return NF_ACCEPT)
*/
int
ip_vs_null_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
struct ip_vs_protocol *pp)
{
/* we do not touch skb and do not need pskb ptr */
return NF_ACCEPT;
}
/*
* Bypass transmitter
* Let packets bypass the destination when the destination is not
* available, it may be only used in transparent cache cluster.
*/
int
ip_vs_bypass_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
struct ip_vs_protocol *pp)
{
struct rtable *rt; /* Route to the other host */
struct iphdr *iph = skb->nh.iph;
u8 tos = iph->tos;
int mtu;
struct flowi fl = {
.oif = 0,
.nl_u = {
.ip4_u = {
.daddr = iph->daddr,
.saddr = 0,
.tos = RT_TOS(tos), } },
};
EnterFunction(10);
if (ip_route_output_key(&rt, &fl)) {
IP_VS_DBG_RL("ip_vs_bypass_xmit(): ip_route_output error, "
"dest: %u.%u.%u.%u\n", NIPQUAD(iph->daddr));
goto tx_error_icmp;
}
/* MTU checking */
mtu = dst_mtu(&rt->u.dst);
if ((skb->len > mtu) && (iph->frag_off&__constant_htons(IP_DF))) {
ip_rt_put(rt);
icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
IP_VS_DBG_RL("ip_vs_bypass_xmit(): frag needed\n");
goto tx_error;
}
/*
* Call ip_send_check because we are not sure it is called
* after ip_defrag. Is copy-on-write needed?
*/
if (unlikely((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)) {
ip_rt_put(rt);
return NF_STOLEN;
}
ip_send_check(skb->nh.iph);
/* drop old route */
dst_release(skb->dst);
skb->dst = &rt->u.dst;
/* Another hack: avoid icmp_send in ip_fragment */
skb->local_df = 1;
IP_VS_XMIT(skb, rt);
LeaveFunction(10);
return NF_STOLEN;
tx_error_icmp:
dst_link_failure(skb);
tx_error:
kfree_skb(skb);
LeaveFunction(10);
return NF_STOLEN;
}
/*
* NAT transmitter (only for outside-to-inside nat forwarding)
* Not used for related ICMP
*/
int
ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
struct ip_vs_protocol *pp)
{
struct rtable *rt; /* Route to the other host */
int mtu;
struct iphdr *iph = skb->nh.iph;
EnterFunction(10);
/* check if it is a connection of no-client-port */
if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT)) {
__u16 _pt, *p;
p = skb_header_pointer(skb, iph->ihl*4, sizeof(_pt), &_pt);
if (p == NULL)
goto tx_error;
ip_vs_conn_fill_cport(cp, *p);
IP_VS_DBG(10, "filled cport=%d\n", ntohs(*p));
}
if (!(rt = __ip_vs_get_out_rt(cp, RT_TOS(iph->tos))))
goto tx_error_icmp;
/* MTU checking */
mtu = dst_mtu(&rt->u.dst);
if ((skb->len > mtu) && (iph->frag_off&__constant_htons(IP_DF))) {
ip_rt_put(rt);
icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
IP_VS_DBG_RL_PKT(0, pp, skb, 0, "ip_vs_nat_xmit(): frag needed for");
goto tx_error;
}
/* copy-on-write the packet before mangling it */
if (!ip_vs_make_skb_writable(&skb, sizeof(struct iphdr)))
goto tx_error_put;
if (skb_cow(skb, rt->u.dst.dev->hard_header_len))
goto tx_error_put;
/* drop old route */
dst_release(skb->dst);
skb->dst = &rt->u.dst;
/* mangle the packet */
if (pp->dnat_handler && !pp->dnat_handler(&skb, pp, cp))
goto tx_error;
skb->nh.iph->daddr = cp->daddr;
ip_send_check(skb->nh.iph);
IP_VS_DBG_PKT(10, pp, skb, 0, "After DNAT");
/* FIXME: when application helper enlarges the packet and the length
is larger than the MTU of outgoing device, there will be still
MTU problem. */
/* Another hack: avoid icmp_send in ip_fragment */
skb->local_df = 1;
IP_VS_XMIT(skb, rt);
LeaveFunction(10);
return NF_STOLEN;
tx_error_icmp:
dst_link_failure(skb);
tx_error:
LeaveFunction(10);
kfree_skb(skb);
return NF_STOLEN;
tx_error_put:
ip_rt_put(rt);
goto tx_error;
}
/*
* IP Tunneling transmitter
*
* This function encapsulates the packet in a new IP packet, its
* destination will be set to cp->daddr. Most code of this function
* is taken from ipip.c.
*
* It is used in VS/TUN cluster. The load balancer selects a real
* server from a cluster based on a scheduling algorithm,
* encapsulates the request packet and forwards it to the selected
* server. For example, all real servers are configured with
* "ifconfig tunl0 <Virtual IP Address> up". When the server receives
* the encapsulated packet, it will decapsulate the packet, processe
* the request and return the response packets directly to the client
* without passing the load balancer. This can greatly increase the
* scalability of virtual server.
*
* Used for ANY protocol
*/
int
ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
struct ip_vs_protocol *pp)
{
struct rtable *rt; /* Route to the other host */
struct net_device *tdev; /* Device to other host */
struct iphdr *old_iph = skb->nh.iph;
u8 tos = old_iph->tos;
__be16 df = old_iph->frag_off;
struct iphdr *iph; /* Our new IP header */
int max_headroom; /* The extra header space needed */
int mtu;
EnterFunction(10);
if (skb->protocol != __constant_htons(ETH_P_IP)) {
IP_VS_DBG_RL("ip_vs_tunnel_xmit(): protocol error, "
"ETH_P_IP: %d, skb protocol: %d\n",
__constant_htons(ETH_P_IP), skb->protocol);
goto tx_error;
}
if (!(rt = __ip_vs_get_out_rt(cp, RT_TOS(tos))))
goto tx_error_icmp;
tdev = rt->u.dst.dev;
mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
if (mtu < 68) {
ip_rt_put(rt);
IP_VS_DBG_RL("ip_vs_tunnel_xmit(): mtu less than 68\n");
goto tx_error;
}
if (skb->dst)
skb->dst->ops->update_pmtu(skb->dst, mtu);
df |= (old_iph->frag_off&__constant_htons(IP_DF));
if ((old_iph->frag_off&__constant_htons(IP_DF))
&& mtu < ntohs(old_iph->tot_len)) {
icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
ip_rt_put(rt);
IP_VS_DBG_RL("ip_vs_tunnel_xmit(): frag needed\n");
goto tx_error;
}
/*
* Okay, now see if we can stuff it in the buffer as-is.
*/
max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct iphdr);
if (skb_headroom(skb) < max_headroom
|| skb_cloned(skb) || skb_shared(skb)) {
struct sk_buff *new_skb =
skb_realloc_headroom(skb, max_headroom);
if (!new_skb) {
ip_rt_put(rt);
kfree_skb(skb);
IP_VS_ERR_RL("ip_vs_tunnel_xmit(): no memory\n");
return NF_STOLEN;
}
kfree_skb(skb);
skb = new_skb;
old_iph = skb->nh.iph;
}
skb->h.raw = (void *) old_iph;
/* fix old IP header checksum */
ip_send_check(old_iph);
skb->nh.raw = skb_push(skb, sizeof(struct iphdr));
memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
/* drop old route */
dst_release(skb->dst);
skb->dst = &rt->u.dst;
/*
* Push down and install the IPIP header.
*/
iph = skb->nh.iph;
iph->version = 4;
iph->ihl = sizeof(struct iphdr)>>2;
iph->frag_off = df;
iph->protocol = IPPROTO_IPIP;
iph->tos = tos;
iph->daddr = rt->rt_dst;
iph->saddr = rt->rt_src;
iph->ttl = old_iph->ttl;
iph->tot_len = htons(skb->len);
ip_select_ident(iph, &rt->u.dst, NULL);
ip_send_check(iph);
/* Another hack: avoid icmp_send in ip_fragment */
skb->local_df = 1;
IP_VS_XMIT(skb, rt);
LeaveFunction(10);
return NF_STOLEN;
tx_error_icmp:
dst_link_failure(skb);
tx_error:
kfree_skb(skb);
LeaveFunction(10);
return NF_STOLEN;
}
/*
* Direct Routing transmitter
* Used for ANY protocol
*/
int
ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
struct ip_vs_protocol *pp)
{
struct rtable *rt; /* Route to the other host */
struct iphdr *iph = skb->nh.iph;
int mtu;
EnterFunction(10);
if (!(rt = __ip_vs_get_out_rt(cp, RT_TOS(iph->tos))))
goto tx_error_icmp;
/* MTU checking */
mtu = dst_mtu(&rt->u.dst);
if ((iph->frag_off&__constant_htons(IP_DF)) && skb->len > mtu) {
icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
ip_rt_put(rt);
IP_VS_DBG_RL("ip_vs_dr_xmit(): frag needed\n");
goto tx_error;
}
/*
* Call ip_send_check because we are not sure it is called
* after ip_defrag. Is copy-on-write needed?
*/
if (unlikely((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)) {
ip_rt_put(rt);
return NF_STOLEN;
}
ip_send_check(skb->nh.iph);
/* drop old route */
dst_release(skb->dst);
skb->dst = &rt->u.dst;
/* Another hack: avoid icmp_send in ip_fragment */
skb->local_df = 1;
IP_VS_XMIT(skb, rt);
LeaveFunction(10);
return NF_STOLEN;
tx_error_icmp:
dst_link_failure(skb);
tx_error:
kfree_skb(skb);
LeaveFunction(10);
return NF_STOLEN;
}
/*
* ICMP packet transmitter
* called by the ip_vs_in_icmp
*/
int
ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
struct ip_vs_protocol *pp, int offset)
{
struct rtable *rt; /* Route to the other host */
int mtu;
int rc;
EnterFunction(10);
/* The ICMP packet for VS/TUN, VS/DR and LOCALNODE will be
forwarded directly here, because there is no need to
translate address/port back */
if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ) {
if (cp->packet_xmit)
rc = cp->packet_xmit(skb, cp, pp);
else
rc = NF_ACCEPT;
/* do not touch skb anymore */
atomic_inc(&cp->in_pkts);
goto out;
}
/*
* mangle and send the packet here (only for VS/NAT)
*/
if (!(rt = __ip_vs_get_out_rt(cp, RT_TOS(skb->nh.iph->tos))))
goto tx_error_icmp;
/* MTU checking */
mtu = dst_mtu(&rt->u.dst);
if ((skb->len > mtu) && (skb->nh.iph->frag_off&__constant_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;
}
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