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linux/net/ipv4/ipvs/ip_vs_core.c

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/*
* IPVS An implementation of the IP virtual server support for the
* LINUX operating system. IPVS is now implemented as a module
* over the Netfilter framework. IPVS can be used to build a
* high-performance and highly available server based on a
* cluster of servers.
*
* Version: $Id: ip_vs_core.c,v 1.34 2003/05/10 03:05:23 wensong Exp $
*
* Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
* Peter Kese <peter.kese@ijs.si>
* 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.
*
* The IPVS code for kernel 2.2 was done by Wensong Zhang and Peter Kese,
* with changes/fixes from Julian Anastasov, Lars Marowsky-Bree, Horms
* and others.
*
* Changes:
* Paul `Rusty' Russell properly handle non-linear skbs
* Harald Welte don't use nfcache
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/icmp.h>
#include <net/ip.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/icmp.h> /* for icmp_send */
#include <net/route.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <net/ip_vs.h>
EXPORT_SYMBOL(register_ip_vs_scheduler);
EXPORT_SYMBOL(unregister_ip_vs_scheduler);
EXPORT_SYMBOL(ip_vs_skb_replace);
EXPORT_SYMBOL(ip_vs_proto_name);
EXPORT_SYMBOL(ip_vs_conn_new);
EXPORT_SYMBOL(ip_vs_conn_in_get);
EXPORT_SYMBOL(ip_vs_conn_out_get);
#ifdef CONFIG_IP_VS_PROTO_TCP
EXPORT_SYMBOL(ip_vs_tcp_conn_listen);
#endif
EXPORT_SYMBOL(ip_vs_conn_put);
#ifdef CONFIG_IP_VS_DEBUG
EXPORT_SYMBOL(ip_vs_get_debug_level);
#endif
EXPORT_SYMBOL(ip_vs_make_skb_writable);
/* ID used in ICMP lookups */
#define icmp_id(icmph) (((icmph)->un).echo.id)
const char *ip_vs_proto_name(unsigned proto)
{
static char buf[20];
switch (proto) {
case IPPROTO_IP:
return "IP";
case IPPROTO_UDP:
return "UDP";
case IPPROTO_TCP:
return "TCP";
case IPPROTO_ICMP:
return "ICMP";
default:
sprintf(buf, "IP_%d", proto);
return buf;
}
}
void ip_vs_init_hash_table(struct list_head *table, int rows)
{
while (--rows >= 0)
INIT_LIST_HEAD(&table[rows]);
}
static inline void
ip_vs_in_stats(struct ip_vs_conn *cp, struct sk_buff *skb)
{
struct ip_vs_dest *dest = cp->dest;
if (dest && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
spin_lock(&dest->stats.lock);
dest->stats.inpkts++;
dest->stats.inbytes += skb->len;
spin_unlock(&dest->stats.lock);
spin_lock(&dest->svc->stats.lock);
dest->svc->stats.inpkts++;
dest->svc->stats.inbytes += skb->len;
spin_unlock(&dest->svc->stats.lock);
spin_lock(&ip_vs_stats.lock);
ip_vs_stats.inpkts++;
ip_vs_stats.inbytes += skb->len;
spin_unlock(&ip_vs_stats.lock);
}
}
static inline void
ip_vs_out_stats(struct ip_vs_conn *cp, struct sk_buff *skb)
{
struct ip_vs_dest *dest = cp->dest;
if (dest && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
spin_lock(&dest->stats.lock);
dest->stats.outpkts++;
dest->stats.outbytes += skb->len;
spin_unlock(&dest->stats.lock);
spin_lock(&dest->svc->stats.lock);
dest->svc->stats.outpkts++;
dest->svc->stats.outbytes += skb->len;
spin_unlock(&dest->svc->stats.lock);
spin_lock(&ip_vs_stats.lock);
ip_vs_stats.outpkts++;
ip_vs_stats.outbytes += skb->len;
spin_unlock(&ip_vs_stats.lock);
}
}
static inline void
ip_vs_conn_stats(struct ip_vs_conn *cp, struct ip_vs_service *svc)
{
spin_lock(&cp->dest->stats.lock);
cp->dest->stats.conns++;
spin_unlock(&cp->dest->stats.lock);
spin_lock(&svc->stats.lock);
svc->stats.conns++;
spin_unlock(&svc->stats.lock);
spin_lock(&ip_vs_stats.lock);
ip_vs_stats.conns++;
spin_unlock(&ip_vs_stats.lock);
}
static inline int
ip_vs_set_state(struct ip_vs_conn *cp, int direction,
const struct sk_buff *skb,
struct ip_vs_protocol *pp)
{
if (unlikely(!pp->state_transition))
return 0;
return pp->state_transition(cp, direction, skb, pp);
}
int ip_vs_make_skb_writable(struct sk_buff **pskb, int writable_len)
{
struct sk_buff *skb = *pskb;
/* skb is already used, better copy skb and its payload */
if (unlikely(skb_shared(skb) || skb->sk))
goto copy_skb;
/* skb data is already used, copy it */
if (unlikely(skb_cloned(skb)))
goto copy_data;
return pskb_may_pull(skb, writable_len);
copy_data:
if (unlikely(writable_len > skb->len))
return 0;
return !pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
copy_skb:
if (unlikely(writable_len > skb->len))
return 0;
skb = skb_copy(skb, GFP_ATOMIC);
if (!skb)
return 0;
BUG_ON(skb_is_nonlinear(skb));
/* Rest of kernel will get very unhappy if we pass it a
suddenly-orphaned skbuff */
if ((*pskb)->sk)
skb_set_owner_w(skb, (*pskb)->sk);
kfree_skb(*pskb);
*pskb = skb;
return 1;
}
/*
* IPVS persistent scheduling function
* It creates a connection entry according to its template if exists,
* or selects a server and creates a connection entry plus a template.
* Locking: we are svc user (svc->refcnt), so we hold all dests too
* Protocols supported: TCP, UDP
*/
static struct ip_vs_conn *
ip_vs_sched_persist(struct ip_vs_service *svc,
const struct sk_buff *skb,
__u16 ports[2])
{
struct ip_vs_conn *cp = NULL;
struct iphdr *iph = skb->nh.iph;
struct ip_vs_dest *dest;
struct ip_vs_conn *ct;
__u16 dport; /* destination port to forward */
__u32 snet; /* source network of the client, after masking */
/* Mask saddr with the netmask to adjust template granularity */
snet = iph->saddr & svc->netmask;
IP_VS_DBG(6, "p-schedule: src %u.%u.%u.%u:%u dest %u.%u.%u.%u:%u "
"mnet %u.%u.%u.%u\n",
NIPQUAD(iph->saddr), ntohs(ports[0]),
NIPQUAD(iph->daddr), ntohs(ports[1]),
NIPQUAD(snet));
/*
* As far as we know, FTP is a very complicated network protocol, and
* it uses control connection and data connections. For active FTP,
* FTP server initialize data connection to the client, its source port
* is often 20. For passive FTP, FTP server tells the clients the port
* that it passively listens to, and the client issues the data
* connection. In the tunneling or direct routing mode, the load
* balancer is on the client-to-server half of connection, the port
* number is unknown to the load balancer. So, a conn template like
* <caddr, 0, vaddr, 0, daddr, 0> is created for persistent FTP
* service, and a template like <caddr, 0, vaddr, vport, daddr, dport>
* is created for other persistent services.
*/
if (ports[1] == svc->port) {
/* Check if a template already exists */
if (svc->port != FTPPORT)
ct = ip_vs_ct_in_get(iph->protocol, snet, 0,
iph->daddr, ports[1]);
else
ct = ip_vs_ct_in_get(iph->protocol, snet, 0,
iph->daddr, 0);
if (!ct || !ip_vs_check_template(ct)) {
/*
* No template found or the dest of the connection
* template is not available.
*/
dest = svc->scheduler->schedule(svc, skb);
if (dest == NULL) {
IP_VS_DBG(1, "p-schedule: no dest found.\n");
return NULL;
}
/*
* Create a template like <protocol,caddr,0,
* vaddr,vport,daddr,dport> for non-ftp service,
* and <protocol,caddr,0,vaddr,0,daddr,0>
* for ftp service.
*/
if (svc->port != FTPPORT)
ct = ip_vs_conn_new(iph->protocol,
snet, 0,
iph->daddr,
ports[1],
dest->addr, dest->port,
IP_VS_CONN_F_TEMPLATE,
dest);
else
ct = ip_vs_conn_new(iph->protocol,
snet, 0,
iph->daddr, 0,
dest->addr, 0,
IP_VS_CONN_F_TEMPLATE,
dest);
if (ct == NULL)
return NULL;
ct->timeout = svc->timeout;
} else {
/* set destination with the found template */
dest = ct->dest;
}
dport = dest->port;
} else {
/*
* Note: persistent fwmark-based services and persistent
* port zero service are handled here.
* fwmark template: <IPPROTO_IP,caddr,0,fwmark,0,daddr,0>
* port zero template: <protocol,caddr,0,vaddr,0,daddr,0>
*/
if (svc->fwmark)
ct = ip_vs_ct_in_get(IPPROTO_IP, snet, 0,
htonl(svc->fwmark), 0);
else
ct = ip_vs_ct_in_get(iph->protocol, snet, 0,
iph->daddr, 0);
if (!ct || !ip_vs_check_template(ct)) {
/*
* If it is not persistent port zero, return NULL,
* otherwise create a connection template.
*/
if (svc->port)
return NULL;
dest = svc->scheduler->schedule(svc, skb);
if (dest == NULL) {
IP_VS_DBG(1, "p-schedule: no dest found.\n");
return NULL;
}
/*
* Create a template according to the service
*/
if (svc->fwmark)
ct = ip_vs_conn_new(IPPROTO_IP,
snet, 0,
htonl(svc->fwmark), 0,
dest->addr, 0,
IP_VS_CONN_F_TEMPLATE,
dest);
else
ct = ip_vs_conn_new(iph->protocol,
snet, 0,
iph->daddr, 0,
dest->addr, 0,
IP_VS_CONN_F_TEMPLATE,
dest);
if (ct == NULL)
return NULL;
ct->timeout = svc->timeout;
} else {
/* set destination with the found template */
dest = ct->dest;
}
dport = ports[1];
}
/*
* Create a new connection according to the template
*/
cp = ip_vs_conn_new(iph->protocol,
iph->saddr, ports[0],
iph->daddr, ports[1],
dest->addr, dport,
0,
dest);
if (cp == NULL) {
ip_vs_conn_put(ct);
return NULL;
}
/*
* Add its control
*/
ip_vs_control_add(cp, ct);
ip_vs_conn_put(ct);
ip_vs_conn_stats(cp, svc);
return cp;
}
/*
* IPVS main scheduling function
* It selects a server according to the virtual service, and
* creates a connection entry.
* Protocols supported: TCP, UDP
*/
struct ip_vs_conn *
ip_vs_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
{
struct ip_vs_conn *cp = NULL;
struct iphdr *iph = skb->nh.iph;
struct ip_vs_dest *dest;
__u16 _ports[2], *pptr;
pptr = skb_header_pointer(skb, iph->ihl*4,
sizeof(_ports), _ports);
if (pptr == NULL)
return NULL;
/*
* Persistent service
*/
if (svc->flags & IP_VS_SVC_F_PERSISTENT)
return ip_vs_sched_persist(svc, skb, pptr);
/*
* Non-persistent service
*/
if (!svc->fwmark && pptr[1] != svc->port) {
if (!svc->port)
IP_VS_ERR("Schedule: port zero only supported "
"in persistent services, "
"check your ipvs configuration\n");
return NULL;
}
dest = svc->scheduler->schedule(svc, skb);
if (dest == NULL) {
IP_VS_DBG(1, "Schedule: no dest found.\n");
return NULL;
}
/*
* Create a connection entry.
*/
cp = ip_vs_conn_new(iph->protocol,
iph->saddr, pptr[0],
iph->daddr, pptr[1],
dest->addr, dest->port?dest->port:pptr[1],
0,
dest);
if (cp == NULL)
return NULL;
IP_VS_DBG(6, "Schedule fwd:%c c:%u.%u.%u.%u:%u v:%u.%u.%u.%u:%u "
"d:%u.%u.%u.%u:%u conn->flags:%X conn->refcnt:%d\n",
ip_vs_fwd_tag(cp),
NIPQUAD(cp->caddr), ntohs(cp->cport),
NIPQUAD(cp->vaddr), ntohs(cp->vport),
NIPQUAD(cp->daddr), ntohs(cp->dport),
cp->flags, atomic_read(&cp->refcnt));
ip_vs_conn_stats(cp, svc);
return cp;
}
/*
* Pass or drop the packet.
* Called by ip_vs_in, when the virtual service is available but
* no destination is available for a new connection.
*/
int ip_vs_leave(struct ip_vs_service *svc, struct sk_buff *skb,
struct ip_vs_protocol *pp)
{
__u16 _ports[2], *pptr;
struct iphdr *iph = skb->nh.iph;
pptr = skb_header_pointer(skb, iph->ihl*4,
sizeof(_ports), _ports);
if (pptr == NULL) {
ip_vs_service_put(svc);
return NF_DROP;
}
/* if it is fwmark-based service, the cache_bypass sysctl is up
and the destination is RTN_UNICAST (and not local), then create
a cache_bypass connection entry */
if (sysctl_ip_vs_cache_bypass && svc->fwmark
&& (inet_addr_type(iph->daddr) == RTN_UNICAST)) {
int ret, cs;
struct ip_vs_conn *cp;
ip_vs_service_put(svc);
/* create a new connection entry */
IP_VS_DBG(6, "ip_vs_leave: create a cache_bypass entry\n");
cp = ip_vs_conn_new(iph->protocol,
iph->saddr, pptr[0],
iph->daddr, pptr[1],
0, 0,
IP_VS_CONN_F_BYPASS,
NULL);
if (cp == NULL)
return NF_DROP;
/* statistics */
ip_vs_in_stats(cp, skb);
/* set state */
cs = ip_vs_set_state(cp, IP_VS_DIR_INPUT, skb, pp);
/* transmit the first SYN packet */
ret = cp->packet_xmit(skb, cp, pp);
/* do not touch skb anymore */
atomic_inc(&cp->in_pkts);
ip_vs_conn_put(cp);
return ret;
}
/*
* When the virtual ftp service is presented, packets destined
* for other services on the VIP may get here (except services
* listed in the ipvs table), pass the packets, because it is
* not ipvs job to decide to drop the packets.
*/
if ((svc->port == FTPPORT) && (pptr[1] != FTPPORT)) {
ip_vs_service_put(svc);
return NF_ACCEPT;
}
ip_vs_service_put(svc);
/*
* Notify the client that the destination is unreachable, and
* release the socket buffer.
* Since it is in IP layer, the TCP socket is not actually
* created, the TCP RST packet cannot be sent, instead that
* ICMP_PORT_UNREACH is sent here no matter it is TCP/UDP. --WZ
*/
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
return NF_DROP;
}
/*
* It is hooked before NF_IP_PRI_NAT_SRC at the NF_IP_POST_ROUTING
* chain, and is used for VS/NAT.
* It detects packets for VS/NAT connections and sends the packets
* immediately. This can avoid that iptable_nat mangles the packets
* for VS/NAT.
*/
static unsigned int ip_vs_post_routing(unsigned int hooknum,
struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
if (!((*pskb)->ipvs_property))
return NF_ACCEPT;
/* The packet was sent from IPVS, exit this chain */
return NF_STOP;
}
u16 ip_vs_checksum_complete(struct sk_buff *skb, int offset)
{
return (u16) csum_fold(skb_checksum(skb, offset, skb->len - offset, 0));
}
static inline struct sk_buff *
ip_vs_gather_frags(struct sk_buff *skb, u_int32_t user)
{
skb = ip_defrag(skb, user);
if (skb)
ip_send_check(skb->nh.iph);
return skb;
}
/*
* Packet has been made sufficiently writable in caller
* - inout: 1=in->out, 0=out->in
*/
void ip_vs_nat_icmp(struct sk_buff *skb, struct ip_vs_protocol *pp,
struct ip_vs_conn *cp, int inout)
{
struct iphdr *iph = skb->nh.iph;
unsigned int icmp_offset = iph->ihl*4;
struct icmphdr *icmph = (struct icmphdr *)(skb->nh.raw + icmp_offset);
struct iphdr *ciph = (struct iphdr *)(icmph + 1);
if (inout) {
iph->saddr = cp->vaddr;
ip_send_check(iph);
ciph->daddr = cp->vaddr;
ip_send_check(ciph);
} else {
iph->daddr = cp->daddr;
ip_send_check(iph);
ciph->saddr = cp->daddr;
ip_send_check(ciph);
}
/* the TCP/UDP port */
if (IPPROTO_TCP == ciph->protocol || IPPROTO_UDP == ciph->protocol) {
__u16 *ports = (void *)ciph + ciph->ihl*4;
if (inout)
ports[1] = cp->vport;
else
ports[0] = cp->dport;
}
/* And finally the ICMP checksum */
icmph->checksum = 0;
icmph->checksum = ip_vs_checksum_complete(skb, icmp_offset);
skb->ip_summed = CHECKSUM_UNNECESSARY;
if (inout)
IP_VS_DBG_PKT(11, pp, skb, (void *)ciph - (void *)iph,
"Forwarding altered outgoing ICMP");
else
IP_VS_DBG_PKT(11, pp, skb, (void *)ciph - (void *)iph,
"Forwarding altered incoming ICMP");
}
/*
* Handle ICMP messages in the inside-to-outside direction (outgoing).
* Find any that might be relevant, check against existing connections,
* forward to the right destination host if relevant.
* Currently handles error types - unreachable, quench, ttl exceeded.
* (Only used in VS/NAT)
*/
static int ip_vs_out_icmp(struct sk_buff **pskb, int *related)
{
struct sk_buff *skb = *pskb;
struct iphdr *iph;
struct icmphdr _icmph, *ic;
struct iphdr _ciph, *cih; /* The ip header contained within the ICMP */
struct ip_vs_conn *cp;
struct ip_vs_protocol *pp;
unsigned int offset, ihl, verdict;
*related = 1;
/* reassemble IP fragments */
if (skb->nh.iph->frag_off & __constant_htons(IP_MF|IP_OFFSET)) {
skb = ip_vs_gather_frags(skb, IP_DEFRAG_VS_OUT);
if (!skb)
return NF_STOLEN;
*pskb = skb;
}
iph = skb->nh.iph;
offset = ihl = iph->ihl * 4;
ic = skb_header_pointer(skb, offset, sizeof(_icmph), &_icmph);
if (ic == NULL)
return NF_DROP;
IP_VS_DBG(12, "Outgoing ICMP (%d,%d) %u.%u.%u.%u->%u.%u.%u.%u\n",
ic->type, ntohs(icmp_id(ic)),
NIPQUAD(iph->saddr), NIPQUAD(iph->daddr));
/*
* Work through seeing if this is for us.
* These checks are supposed to be in an order that means easy
* things are checked first to speed up processing.... however
* this means that some packets will manage to get a long way
* down this stack and then be rejected, but that's life.
*/
if ((ic->type != ICMP_DEST_UNREACH) &&
(ic->type != ICMP_SOURCE_QUENCH) &&
(ic->type != ICMP_TIME_EXCEEDED)) {
*related = 0;
return NF_ACCEPT;
}
/* Now find the contained IP header */
offset += sizeof(_icmph);
cih = skb_header_pointer(skb, offset, sizeof(_ciph), &_ciph);
if (cih == NULL)
return NF_ACCEPT; /* The packet looks wrong, ignore */
pp = ip_vs_proto_get(cih->protocol);
if (!pp)
return NF_ACCEPT;
/* Is the embedded protocol header present? */
if (unlikely(cih->frag_off & __constant_htons(IP_OFFSET) &&
pp->dont_defrag))
return NF_ACCEPT;
IP_VS_DBG_PKT(11, pp, skb, offset, "Checking outgoing ICMP for");
offset += cih->ihl * 4;
/* The embedded headers contain source and dest in reverse order */
cp = pp->conn_out_get(skb, pp, cih, offset, 1);
if (!cp)
return NF_ACCEPT;
verdict = NF_DROP;
if (IP_VS_FWD_METHOD(cp) != 0) {
IP_VS_ERR("shouldn't reach here, because the box is on the"
"half connection in the tun/dr module.\n");
}
/* Ensure the checksum is correct */
if (skb->ip_summed != CHECKSUM_UNNECESSARY &&
ip_vs_checksum_complete(skb, ihl)) {
/* Failed checksum! */
IP_VS_DBG(1, "Forward ICMP: failed checksum from %d.%d.%d.%d!\n",
NIPQUAD(iph->saddr));
goto out;
}
if (IPPROTO_TCP == cih->protocol || IPPROTO_UDP == cih->protocol)
offset += 2 * sizeof(__u16);
if (!ip_vs_make_skb_writable(pskb, offset))
goto out;
skb = *pskb;
ip_vs_nat_icmp(skb, pp, cp, 1);
/* do the statistics and put it back */
ip_vs_out_stats(cp, skb);
skb->ipvs_property = 1;
verdict = NF_ACCEPT;
out:
__ip_vs_conn_put(cp);
return verdict;
}
static inline int is_tcp_reset(const struct sk_buff *skb)
{
struct tcphdr _tcph, *th;
th = skb_header_pointer(skb, skb->nh.iph->ihl * 4,
sizeof(_tcph), &_tcph);
if (th == NULL)
return 0;
return th->rst;
}
/*
* It is hooked at the NF_IP_FORWARD chain, used only for VS/NAT.
* Check if outgoing packet belongs to the established ip_vs_conn,
* rewrite addresses of the packet and send it on its way...
*/
static unsigned int
ip_vs_out(unsigned int hooknum, struct sk_buff **pskb,
const struct net_device *in, const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb = *pskb;
struct iphdr *iph;
struct ip_vs_protocol *pp;
struct ip_vs_conn *cp;
int ihl;
EnterFunction(11);
if (skb->ipvs_property)
return NF_ACCEPT;
iph = skb->nh.iph;
if (unlikely(iph->protocol == IPPROTO_ICMP)) {
int related, verdict = ip_vs_out_icmp(pskb, &related);
if (related)
return verdict;
skb = *pskb;
iph = skb->nh.iph;
}
pp = ip_vs_proto_get(iph->protocol);
if (unlikely(!pp))
return NF_ACCEPT;
/* reassemble IP fragments */
if (unlikely(iph->frag_off & __constant_htons(IP_MF|IP_OFFSET) &&
!pp->dont_defrag)) {
skb = ip_vs_gather_frags(skb, IP_DEFRAG_VS_OUT);
if (!skb)
return NF_STOLEN;
iph = skb->nh.iph;
*pskb = skb;
}
ihl = iph->ihl << 2;
/*
* Check if the packet belongs to an existing entry
*/
cp = pp->conn_out_get(skb, pp, iph, ihl, 0);
if (unlikely(!cp)) {
if (sysctl_ip_vs_nat_icmp_send &&
(pp->protocol == IPPROTO_TCP ||
pp->protocol == IPPROTO_UDP)) {
__u16 _ports[2], *pptr;
pptr = skb_header_pointer(skb, ihl,
sizeof(_ports), _ports);
if (pptr == NULL)
return NF_ACCEPT; /* Not for me */
if (ip_vs_lookup_real_service(iph->protocol,
iph->saddr, pptr[0])) {
/*
* Notify the real server: there is no
* existing entry if it is not RST
* packet or not TCP packet.
*/
if (iph->protocol != IPPROTO_TCP
|| !is_tcp_reset(skb)) {
icmp_send(skb,ICMP_DEST_UNREACH,
ICMP_PORT_UNREACH, 0);
return NF_DROP;
}
}
}
IP_VS_DBG_PKT(12, pp, skb, 0,
"packet continues traversal as normal");
return NF_ACCEPT;
}
IP_VS_DBG_PKT(11, pp, skb, 0, "Outgoing packet");
if (!ip_vs_make_skb_writable(pskb, ihl))
goto drop;
/* mangle the packet */
if (pp->snat_handler && !pp->snat_handler(pskb, pp, cp))
goto drop;
skb = *pskb;
skb->nh.iph->saddr = cp->vaddr;
ip_send_check(skb->nh.iph);
IP_VS_DBG_PKT(10, pp, skb, 0, "After SNAT");
ip_vs_out_stats(cp, skb);
ip_vs_set_state(cp, IP_VS_DIR_OUTPUT, skb, pp);
ip_vs_conn_put(cp);
skb->ipvs_property = 1;
LeaveFunction(11);
return NF_ACCEPT;
drop:
ip_vs_conn_put(cp);
kfree_skb(*pskb);
return NF_STOLEN;
}
/*
* Handle ICMP messages in the outside-to-inside direction (incoming).
* Find any that might be relevant, check against existing connections,
* forward to the right destination host if relevant.
* Currently handles error types - unreachable, quench, ttl exceeded.
*/
static int
ip_vs_in_icmp(struct sk_buff **pskb, int *related, unsigned int hooknum)
{
struct sk_buff *skb = *pskb;
struct iphdr *iph;
struct icmphdr _icmph, *ic;
struct iphdr _ciph, *cih; /* The ip header contained within the ICMP */
struct ip_vs_conn *cp;
struct ip_vs_protocol *pp;
unsigned int offset, ihl, verdict;
*related = 1;
/* reassemble IP fragments */
if (skb->nh.iph->frag_off & __constant_htons(IP_MF|IP_OFFSET)) {
skb = ip_vs_gather_frags(skb,
hooknum == NF_IP_LOCAL_IN ?
IP_DEFRAG_VS_IN : IP_DEFRAG_VS_FWD);
if (!skb)
return NF_STOLEN;
*pskb = skb;
}
iph = skb->nh.iph;
offset = ihl = iph->ihl * 4;
ic = skb_header_pointer(skb, offset, sizeof(_icmph), &_icmph);
if (ic == NULL)
return NF_DROP;
IP_VS_DBG(12, "Incoming ICMP (%d,%d) %u.%u.%u.%u->%u.%u.%u.%u\n",
ic->type, ntohs(icmp_id(ic)),
NIPQUAD(iph->saddr), NIPQUAD(iph->daddr));
/*
* Work through seeing if this is for us.
* These checks are supposed to be in an order that means easy
* things are checked first to speed up processing.... however
* this means that some packets will manage to get a long way
* down this stack and then be rejected, but that's life.
*/
if ((ic->type != ICMP_DEST_UNREACH) &&
(ic->type != ICMP_SOURCE_QUENCH) &&
(ic->type != ICMP_TIME_EXCEEDED)) {
*related = 0;
return NF_ACCEPT;
}
/* Now find the contained IP header */
offset += sizeof(_icmph);
cih = skb_header_pointer(skb, offset, sizeof(_ciph), &_ciph);
if (cih == NULL)
return NF_ACCEPT; /* The packet looks wrong, ignore */
pp = ip_vs_proto_get(cih->protocol);
if (!pp)
return NF_ACCEPT;
/* Is the embedded protocol header present? */
if (unlikely(cih->frag_off & __constant_htons(IP_OFFSET) &&
pp->dont_defrag))
return NF_ACCEPT;
IP_VS_DBG_PKT(11, pp, skb, offset, "Checking incoming ICMP for");
offset += cih->ihl * 4;
/* The embedded headers contain source and dest in reverse order */
cp = pp->conn_in_get(skb, pp, cih, offset, 1);
if (!cp)
return NF_ACCEPT;
verdict = NF_DROP;
/* Ensure the checksum is correct */
if (skb->ip_summed != CHECKSUM_UNNECESSARY &&
ip_vs_checksum_complete(skb, ihl)) {
/* Failed checksum! */
IP_VS_DBG(1, "Incoming ICMP: failed checksum from %d.%d.%d.%d!\n",
NIPQUAD(iph->saddr));
goto out;
}
/* do the statistics and put it back */
ip_vs_in_stats(cp, skb);
if (IPPROTO_TCP == cih->protocol || IPPROTO_UDP == cih->protocol)
offset += 2 * sizeof(__u16);
verdict = ip_vs_icmp_xmit(skb, cp, pp, offset);
/* do not touch skb anymore */
out:
__ip_vs_conn_put(cp);
return verdict;
}
/*
* Check if it's for virtual services, look it up,
* and send it on its way...
*/
static unsigned int
ip_vs_in(unsigned int hooknum, struct sk_buff **pskb,
const struct net_device *in, const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb = *pskb;
struct iphdr *iph;
struct ip_vs_protocol *pp;
struct ip_vs_conn *cp;
int ret, restart;
int ihl;
/*
* Big tappo: only PACKET_HOST (neither loopback nor mcasts)
* ... don't know why 1st test DOES NOT include 2nd (?)
*/
if (unlikely(skb->pkt_type != PACKET_HOST
|| skb->dev == &loopback_dev || skb->sk)) {
IP_VS_DBG(12, "packet type=%d proto=%d daddr=%d.%d.%d.%d ignored\n",
skb->pkt_type,
skb->nh.iph->protocol,
NIPQUAD(skb->nh.iph->daddr));
return NF_ACCEPT;
}
iph = skb->nh.iph;
if (unlikely(iph->protocol == IPPROTO_ICMP)) {
int related, verdict = ip_vs_in_icmp(pskb, &related, hooknum);
if (related)
return verdict;
skb = *pskb;
iph = skb->nh.iph;
}
/* Protocol supported? */
pp = ip_vs_proto_get(iph->protocol);
if (unlikely(!pp))
return NF_ACCEPT;
ihl = iph->ihl << 2;
/*
* Check if the packet belongs to an existing connection entry
*/
cp = pp->conn_in_get(skb, pp, iph, ihl, 0);
if (unlikely(!cp)) {
int v;
if (!pp->conn_schedule(skb, pp, &v, &cp))
return v;
}
if (unlikely(!cp)) {
/* sorry, all this trouble for a no-hit :) */
IP_VS_DBG_PKT(12, pp, skb, 0,
"packet continues traversal as normal");
return NF_ACCEPT;
}
IP_VS_DBG_PKT(11, pp, skb, 0, "Incoming packet");
/* Check the server status */
if (cp->dest && !(cp->dest->flags & IP_VS_DEST_F_AVAILABLE)) {
/* the destination server is not available */
if (sysctl_ip_vs_expire_nodest_conn) {
/* try to expire the connection immediately */
ip_vs_conn_expire_now(cp);
}
/* don't restart its timer, and silently
drop the packet. */
__ip_vs_conn_put(cp);
return NF_DROP;
}
ip_vs_in_stats(cp, skb);
restart = ip_vs_set_state(cp, IP_VS_DIR_INPUT, skb, pp);
if (cp->packet_xmit)
ret = cp->packet_xmit(skb, cp, pp);
/* do not touch skb anymore */
else {
IP_VS_DBG_RL("warning: packet_xmit is null");
ret = NF_ACCEPT;
}
/* increase its packet counter and check if it is needed
to be synchronized */
atomic_inc(&cp->in_pkts);
if ((ip_vs_sync_state & IP_VS_STATE_MASTER) &&
(cp->protocol != IPPROTO_TCP ||
cp->state == IP_VS_TCP_S_ESTABLISHED) &&
(atomic_read(&cp->in_pkts) % sysctl_ip_vs_sync_threshold[1]
== sysctl_ip_vs_sync_threshold[0]))
ip_vs_sync_conn(cp);
ip_vs_conn_put(cp);
return ret;
}
/*
* It is hooked at the NF_IP_FORWARD chain, in order to catch ICMP
* related packets destined for 0.0.0.0/0.
* When fwmark-based virtual service is used, such as transparent
* cache cluster, TCP packets can be marked and routed to ip_vs_in,
* but ICMP destined for 0.0.0.0/0 cannot not be easily marked and
* sent to ip_vs_in_icmp. So, catch them at the NF_IP_FORWARD chain
* and send them to ip_vs_in_icmp.
*/
static unsigned int
ip_vs_forward_icmp(unsigned int hooknum, struct sk_buff **pskb,
const struct net_device *in, const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
int r;
if ((*pskb)->nh.iph->protocol != IPPROTO_ICMP)
return NF_ACCEPT;
return ip_vs_in_icmp(pskb, &r, hooknum);
}
/* After packet filtering, forward packet through VS/DR, VS/TUN,
or VS/NAT(change destination), so that filtering rules can be
applied to IPVS. */
static struct nf_hook_ops ip_vs_in_ops = {
.hook = ip_vs_in,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_IP_LOCAL_IN,
.priority = 100,
};
/* After packet filtering, change source only for VS/NAT */
static struct nf_hook_ops ip_vs_out_ops = {
.hook = ip_vs_out,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_IP_FORWARD,
.priority = 100,
};
/* After packet filtering (but before ip_vs_out_icmp), catch icmp
destined for 0.0.0.0/0, which is for incoming IPVS connections */
static struct nf_hook_ops ip_vs_forward_icmp_ops = {
.hook = ip_vs_forward_icmp,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_IP_FORWARD,
.priority = 99,
};
/* Before the netfilter connection tracking, exit from POST_ROUTING */
static struct nf_hook_ops ip_vs_post_routing_ops = {
.hook = ip_vs_post_routing,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_IP_POST_ROUTING,
.priority = NF_IP_PRI_NAT_SRC-1,
};
/*
* Initialize IP Virtual Server
*/
static int __init ip_vs_init(void)
{
int ret;
ret = ip_vs_control_init();
if (ret < 0) {
IP_VS_ERR("can't setup control.\n");
goto cleanup_nothing;
}
ip_vs_protocol_init();
ret = ip_vs_app_init();
if (ret < 0) {
IP_VS_ERR("can't setup application helper.\n");
goto cleanup_protocol;
}
ret = ip_vs_conn_init();
if (ret < 0) {
IP_VS_ERR("can't setup connection table.\n");
goto cleanup_app;
}
ret = nf_register_hook(&ip_vs_in_ops);
if (ret < 0) {
IP_VS_ERR("can't register in hook.\n");
goto cleanup_conn;
}
ret = nf_register_hook(&ip_vs_out_ops);
if (ret < 0) {
IP_VS_ERR("can't register out hook.\n");
goto cleanup_inops;
}
ret = nf_register_hook(&ip_vs_post_routing_ops);
if (ret < 0) {
IP_VS_ERR("can't register post_routing hook.\n");
goto cleanup_outops;
}
ret = nf_register_hook(&ip_vs_forward_icmp_ops);
if (ret < 0) {
IP_VS_ERR("can't register forward_icmp hook.\n");
goto cleanup_postroutingops;
}
IP_VS_INFO("ipvs loaded.\n");
return ret;
cleanup_postroutingops:
nf_unregister_hook(&ip_vs_post_routing_ops);
cleanup_outops:
nf_unregister_hook(&ip_vs_out_ops);
cleanup_inops:
nf_unregister_hook(&ip_vs_in_ops);
cleanup_conn:
ip_vs_conn_cleanup();
cleanup_app:
ip_vs_app_cleanup();
cleanup_protocol:
ip_vs_protocol_cleanup();
ip_vs_control_cleanup();
cleanup_nothing:
return ret;
}
static void __exit ip_vs_cleanup(void)
{
nf_unregister_hook(&ip_vs_forward_icmp_ops);
nf_unregister_hook(&ip_vs_post_routing_ops);
nf_unregister_hook(&ip_vs_out_ops);
nf_unregister_hook(&ip_vs_in_ops);
ip_vs_conn_cleanup();
ip_vs_app_cleanup();
ip_vs_protocol_cleanup();
ip_vs_control_cleanup();
IP_VS_INFO("ipvs unloaded.\n");
}
module_init(ip_vs_init);
module_exit(ip_vs_cleanup);
MODULE_LICENSE("GPL");
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