/*
* 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:
*
*/
#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 <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <net/ip_vs.h>
static struct ip_vs_conn *
tcp_conn_in_get(const struct sk_buff *skb, struct ip_vs_protocol *pp,
const struct iphdr *iph, unsigned int proto_off, int inverse)
{
__be16 _ports[2], *pptr;
pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
if (pptr == NULL)
return NULL;
if (likely(!inverse)) {
return ip_vs_conn_in_get(iph->protocol,
iph->saddr, pptr[0],
iph->daddr, pptr[1]);
} else {
return ip_vs_conn_in_get(iph->protocol,
iph->daddr, pptr[1],
iph->saddr, pptr[0]);
}
}
static struct ip_vs_conn *
tcp_conn_out_get(const struct sk_buff *skb, struct ip_vs_protocol *pp,
const struct iphdr *iph, unsigned int proto_off, int inverse)
{
__be16 _ports[2], *pptr;
pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
if (pptr == NULL)
return NULL;
if (likely(!inverse)) {
return ip_vs_conn_out_get(iph->protocol,
iph->saddr, pptr[0],
iph->daddr, pptr[1]);
} else {
return ip_vs_conn_out_get(iph->protocol,
iph->daddr, pptr[1],
iph->saddr, pptr[0]);
}
}
static int
tcp_conn_schedule(struct sk_buff *skb,
struct ip_vs_protocol *pp,
int *verdict, struct ip_vs_conn **cpp)
{
struct ip_vs_service *svc;
struct tcphdr _tcph, *th;
th = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_tcph), &_tcph);
if (th == NULL) {
*verdict = NF_DROP;
return 0;
}
if (th->syn &&
(svc = ip_vs_service_get(skb->mark, ip_hdr(skb)->protocol,
ip_hdr(skb)->daddr, th->dest))) {
if (ip_vs_todrop()) {
/*
* It seems that we are very loaded.
* We have to drop this packet :(
*/
ip_vs_service_put(svc);
*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);
if (!*cpp) {
*verdict = ip_vs_leave(svc, skb, pp);
return 0;
}
ip_vs_service_put(svc);
}
return 1;
}
static inline void
tcp_fast_csum_update(struct tcphdr *tcph, __be32 oldip, __be32 newip,
__be16 oldport, __be16 newport)
{
tcph->check =
csum_fold(ip_vs_check_diff4(oldip, newip,
ip_vs_check_diff2(oldport, newport,
~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;
const unsigned int tcphoff = ip_hdrlen(skb);
/* csum_check requires unshared skb */
if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
return 0;
if (unlikely(cp->app != NULL)) {
/* Some checks before mangling */
if (pp->csum_check && !pp->csum_check(skb, pp))
return 0;
/* Call application helper if needed */
if (!ip_vs_app_pkt_out(cp, skb))
return 0;
}
tcph = (void *)ip_hdr(skb) + tcphoff;
tcph->source = cp->vport;
/* Adjust TCP checksums */
if (!cp->app) {
/* Only port and addr are changed, do fast csum update */
tcp_fast_csum_update(tcph, cp->daddr, cp->vaddr,
cp->dport, cp->vport);
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = CHECKSUM_NONE;
} else {
/* full checksum calculation */
tcph->check = 0;
skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
tcph->check = csum_tcpudp_magic(cp->vaddr, cp->caddr,
skb->len - tcphoff,
cp->protocol, skb->csum);
IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
pp->name, tcph->check,
(char*)&(tcph->check) - (char*)tcph);
}
return 1;
}
static int
tcp_dnat_handler(struct sk_buff *skb,
struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
{
struct tcphdr *tcph;
const unsigned int tcphoff = ip_hdrlen(skb);
/* csum_check requires unshared skb */
if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
return 0;
if (unlikely(cp->app != NULL)) {
/* Some checks before mangling */
if (pp->csum_check && !pp->csum_check(skb, pp))
return 0;
/*
* Attempt ip_vs_app call.
* It will fix ip_vs_conn and iph ack_seq stuff
*/
if (!ip_vs_app_pkt_in(cp, skb))
return 0;
}
tcph = (void *)ip_hdr(skb) + tcphoff;
tcph->dest = cp->dport;
/*
* Adjust TCP checksums
*/
if (!cp->app) {
/* Only port and addr are changed, do fast csum update */
tcp_fast_csum_update(tcph, cp->vaddr, cp->daddr,
cp->vport, cp->dport);
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = CHECKSUM_NONE;
} else {
/* full checksum calculation */
tcph->check = 0;
skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
tcph->check = csum_tcpudp_magic(cp->caddr, cp->daddr,
skb->len - tcphoff,
cp->protocol, skb->csum);
skb->ip_summed = CHECKSUM_UNNECESSARY;
}
return 1;
}
static int
tcp_csum_check(struct sk_buff *skb, struct ip_vs_protocol *pp)
{
const unsigned int tcphoff = ip_hdrlen(skb);
switch (skb->ip_summed) {
case CHECKSUM_NONE:
skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
case CHECKSUM_COMPLETE:
if (csum_tcpudp_magic(ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
skb->len - tcphoff,
ip_hdr(skb)->protocol, skb->csum)) {
IP_VS_DBG_RL_PKT(0, pp, skb, 0,
"Failed checksum for");
return 0;
}
break;
default:
/* No need to checksum. */
break;
}
return 1;
}
#define TCP_DIR_INPUT 0
#define TCP_DIR_OUTPUT 4
#define TCP_DIR_INPUT_ONLY 8
static const int tcp_state_off[IP_VS_DIR_LAST] = {
[IP_VS_DIR_INPUT] = TCP_DIR_INPUT,
[IP_VS_DIR_OUTPUT] = TCP_DIR_OUTPUT,
[IP_VS_DIR_INPUT_ONLY] = TCP_DIR_INPUT_ONLY,
};
/*
* Timeout table[state]
*/
static int tcp_timeouts[IP_VS_TCP_S_LAST+1] = {
[IP_VS_TCP_S_NONE] = 2*HZ,
[IP_VS_TCP_S_ESTABLISHED] = 15*60*HZ,
[IP_VS_TCP_S_SYN_SENT] = 2*60*HZ,
[IP_VS_TCP_S_SYN_RECV] = 1*60*HZ,
[IP_VS_TCP_S_FIN_WAIT] = 2*60*HZ,
[IP_VS_TCP_S_TIME_WAIT] = 2*60*HZ,
[IP_VS_TCP_S_CLOSE] = 10*HZ,
[IP_VS_TCP_S_CLOSE_WAIT] = 60*HZ,
[IP_VS_TCP_S_LAST_ACK] = 30*HZ,
[IP_VS_TCP_S_LISTEN] = 2*60*HZ,
[IP_VS_TCP_S_SYNACK] = 120*HZ,
[IP_VS_TCP_S_LAST] = 2*HZ,
};
static char * tcp_state_name_table[IP_VS_TCP_S_LAST+1] = {
[IP_VS_TCP_S_NONE] = "NONE",
[IP_VS_TCP_S_ESTABLISHED] = "ESTABLISHED",
[IP_VS_TCP_S_SYN_SENT] = "SYN_SENT",
[IP_VS_TCP_S_SYN_RECV] = "SYN_RECV",
[IP_VS_TCP_S_FIN_WAIT] = "FIN_WAIT",
[IP_VS_TCP_S_TIME_WAIT] = "TIME_WAIT",
[IP_VS_TCP_S_CLOSE] = "CLOSE",
[IP_VS_TCP_S_CLOSE_WAIT] = "CLOSE_WAIT",
[IP_VS_TCP_S_LAST_ACK] = "LAST_ACK",
[IP_VS_TCP_S_LISTEN] = "LISTEN",
[IP_VS_TCP_S_SYNACK] = "SYNACK",
[IP_VS_TCP_S_LAST] = "BUG!",
};
#define sNO IP_VS_TCP_S_NONE
#define sES IP_VS_TCP_S_ESTABLISHED
#define sSS IP_VS_TCP_S_SYN_SENT
#define sSR IP_VS_TCP_S_SYN_RECV
#define sFW IP_VS_TCP_S_FIN_WAIT
#define sTW IP_VS_TCP_S_TIME_WAIT
#define sCL IP_VS_TCP_S_CLOSE
#define sCW IP_VS_TCP_S_CLOSE_WAIT
#define sLA IP_VS_TCP_S_LAST_ACK
#define sLI IP_VS_TCP_S_LISTEN
#define sSA IP_VS_TCP_S_SYNACK
struct tcp_states_t {
int next_state[IP_VS_TCP_S_LAST];
};
static const char * tcp_state_name(int state)
{
if (state >= IP_VS_TCP_S_LAST)
return "ERR!";
return tcp_state_name_table[state] ? tcp_state_name_table[state] : "?";
}
static struct tcp_states_t tcp_states [] = {
/* INPUT */
/* sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
/*syn*/ {{sSR, sES, sES, sSR, sSR, sSR, sSR, sSR, sSR, sSR, sSR }},
/*fin*/ {{sCL, sCW, sSS, sTW, sTW, sTW, sCL, sCW, sLA, sLI, sTW }},
/*ack*/ {{sCL, sES, sSS, sES, sFW, sTW, sCL, sCW, sCL, sLI, sES }},
/*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sSR }},
/* OUTPUT */
/* sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
/*syn*/ {{sSS, sES, sSS, sSR, sSS, sSS, sSS, sSS, sSS, sLI, sSR }},
/*fin*/ {{sTW, sFW, sSS, sTW, sFW, sTW, sCL, sTW, sLA, sLI, sTW }},
/*ack*/ {{sES, sES, sSS, sES, sFW, sTW, sCL, sCW, sLA, sES, sES }},
/*rst*/ {{sCL, sCL, sSS, sCL, sCL, sTW, sCL, sCL, sCL, sCL, sCL }},
/* INPUT-ONLY */
/* sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
/*syn*/ {{sSR, sES, sES, sSR, sSR, sSR, sSR, sSR, sSR, sSR, sSR }},
/*fin*/ {{sCL, sFW, sSS, sTW, sFW, sTW, sCL, sCW, sLA, sLI, sTW }},
/*ack*/ {{sCL, sES, sSS, sES, sFW, sTW, sCL, sCW, sCL, sLI, sES }},
/*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sCL }},
};
static struct tcp_states_t tcp_states_dos [] = {
/* INPUT */
/* sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
/*syn*/ {{sSR, sES, sES, sSR, sSR, sSR, sSR, sSR, sSR, sSR, sSA }},
/*fin*/ {{sCL, sCW, sSS, sTW, sTW, sTW, sCL, sCW, sLA, sLI, sSA }},
/*ack*/ {{sCL, sES, sSS, sSR, sFW, sTW, sCL, sCW, sCL, sLI, sSA }},
/*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sCL }},
/* OUTPUT */
/* sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
/*syn*/ {{sSS, sES, sSS, sSA, sSS, sSS, sSS, sSS, sSS, sLI, sSA }},
/*fin*/ {{sTW, sFW, sSS, sTW, sFW, sTW, sCL, sTW, sLA, sLI, sTW }},
/*ack*/ {{sES, sES, sSS, sES, sFW, sTW, sCL, sCW, sLA, sES, sES }},
/*rst*/ {{sCL, sCL, sSS, sCL, sCL, sTW, sCL, sCL, sCL, sCL, sCL }},
/* INPUT-ONLY */
/* sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
/*syn*/ {{sSA, sES, sES, sSR, sSA, sSA, sSA, sSA, sSA, sSA, sSA }},
/*fin*/ {{sCL, sFW, sSS, sTW, sFW, sTW, sCL, sCW, sLA, sLI, sTW }},
/*ack*/ {{sCL, sES, sSS, sES, sFW, sTW, sCL, sCW, sCL, sLI, sES }},
/*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sCL }},
};
static struct tcp_states_t *tcp_state_table = tcp_states;
static void tcp_timeout_change(struct ip_vs_protocol *pp, int flags)
{
int on = (flags & 1); /* secure_tcp */
/*
** FIXME: change secure_tcp to independent sysctl var
** or make it per-service or per-app because it is valid
** for most if not for all of the applications. Something
** like "capabilities" (flags) for each object.
*/
tcp_state_table = (on? tcp_states_dos : tcp_states);
}
static int
tcp_set_state_timeout(struct ip_vs_protocol *pp, char *sname, int to)
{
return ip_vs_set_state_timeout(pp->timeout_table, IP_VS_TCP_S_LAST,
tcp_state_name_table, sname, to);
}
static inline int tcp_state_idx(struct tcphdr *th)
{
if (th->rst)
return 3;
if (th->syn)
return 0;
if (th->fin)
return 1;
if (th->ack)
return 2;
return -1;
}
static inline void
set_tcp_state(struct ip_vs_protocol *pp, struct ip_vs_conn *cp,
int direction, struct tcphdr *th)
{
int state_idx;
int new_state = IP_VS_TCP_S_CLOSE;
int state_off = tcp_state_off[direction];
/*
* Update state offset to INPUT_ONLY if necessary
* or delete NO_OUTPUT flag if output packet detected
*/
if (cp->flags & IP_VS_CONN_F_NOOUTPUT) {
if (state_off == TCP_DIR_OUTPUT)
cp->flags &= ~IP_VS_CONN_F_NOOUTPUT;
else
state_off = TCP_DIR_INPUT_ONLY;
}
if ((state_idx = tcp_state_idx(th)) < 0) {
IP_VS_DBG(8, "tcp_state_idx=%d!!!\n", state_idx);
goto tcp_state_out;
}
new_state = tcp_state_table[state_off+state_idx].next_state[cp->state];
tcp_state_out:
if (new_state != cp->state) {
struct ip_vs_dest *dest = cp->dest;
IP_VS_DBG(8, "%s %s [%c%c%c%c] %u.%u.%u.%u:%d->"
"%u.%u.%u.%u:%d state: %s->%s conn->refcnt:%d\n",
pp->name,
(state_off==TCP_DIR_OUTPUT)?"output ":"input ",
th->syn? 'S' : '.',
th->fin? 'F' : '.',
th->ack? 'A' : '.',
th->rst? 'R' : '.',
NIPQUAD(cp->daddr), ntohs(cp->dport),
NIPQUAD(cp->caddr), ntohs(cp->cport),
tcp_state_name(cp->state),
tcp_state_name(new_state),
atomic_read(&cp->refcnt));
if (dest) {
if (!(cp->flags & IP_VS_CONN_F_INACTIVE) &&
(new_state != IP_VS_TCP_S_ESTABLISHED)) {
atomic_dec(&dest->activeconns);
atomic_inc(&dest->inactconns);
cp->flags |= IP_VS_CONN_F_INACTIVE;
} else if ((cp->flags & IP_VS_CONN_F_INACTIVE) &&
(new_state == IP_VS_TCP_S_ESTABLISHED)) {
atomic_inc(&dest->activeconns);
atomic_dec(&dest->inactconns);
cp->flags &= ~IP_VS_CONN_F_INACTIVE;
}
}
}
cp->timeout = pp->timeout_table[cp->state = new_state];
}
/*
* Handle state transitions
*/
static int
tcp_state_transition(struct ip_vs_conn *cp, int direction,
const struct sk_buff *skb,
struct ip_vs_protocol *pp)
{
struct tcphdr _tcph, *th;
th = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_tcph), &_tcph);
if (th == NULL)
return 0;
spin_lock(&cp->lock);
set_tcp_state(pp, cp, direction, th);
spin_unlock(&cp->lock);
return 1;
}
/*
* Hash table for TCP application incarnations
*/
#define TCP_APP_TAB_BITS 4
#define TCP_APP_TAB_SIZE (1 << TCP_APP_TAB_BITS)
#define TCP_APP_TAB_MASK (TCP_APP_TAB_SIZE - 1)
static struct list_head tcp_apps[TCP_APP_TAB_SIZE];
static DEFINE_SPINLOCK(tcp_app_lock);
static inline __u16 tcp_app_hashkey(__be16 port)
{
return (((__force u16)port >> TCP_APP_TAB_BITS) ^ (__force u16)port)
& TCP_APP_TAB_MASK;
}
static int tcp_register_app(struct ip_vs_app *inc)
{
struct ip_vs_app *i;
__u16 hash;
__be16 port = inc->port;
int ret = 0;
hash = tcp_app_hashkey(port);
spin_lock_bh(&tcp_app_lock);
list_for_each_entry(i, &tcp_apps[hash], p_list) {
if (i->port == port) {
ret = -EEXIST;
goto out;
}
}
list_add(&inc->p_list, &tcp_apps[hash]);
atomic_inc(&ip_vs_protocol_tcp.appcnt);
out:
spin_unlock_bh(&tcp_app_lock);
return ret;
}
static void
tcp_unregister_app(struct ip_vs_app *inc)
{
spin_lock_bh(&tcp_app_lock);
atomic_dec(&ip_vs_protocol_tcp.appcnt);
list_del(&inc->p_list);
spin_unlock_bh(&tcp_app_lock);
}
static int
tcp_app_conn_bind(struct ip_vs_conn *cp)
{
int hash;
struct ip_vs_app *inc;
int result = 0;
/* Default binding: bind app only for NAT */
if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
return 0;
/* Lookup application incarnations and bind the right one */
hash = tcp_app_hashkey(cp->vport);
spin_lock(&tcp_app_lock);
list_for_each_entry(inc, &tcp_apps[hash], p_list) {
if (inc->port == cp->vport) {
if (unlikely(!ip_vs_app_inc_get(inc)))
break;
spin_unlock(&tcp_app_lock);
IP_VS_DBG(9, "%s: Binding conn %u.%u.%u.%u:%u->"
"%u.%u.%u.%u:%u to app %s on port %u\n",
__func__,
NIPQUAD(cp->caddr), ntohs(cp->cport),
NIPQUAD(cp->vaddr), ntohs(cp->vport),
inc->name, ntohs(inc->port));
cp->app = inc;
if (inc->init_conn)
result = inc->init_conn(inc, cp);
goto out;
}
}
spin_unlock(&tcp_app_lock);
out:
return result;
}
/*
* Set LISTEN timeout. (ip_vs_conn_put will setup timer)
*/
void ip_vs_tcp_conn_listen(struct ip_vs_conn *cp)
{
spin_lock(&cp->lock);
cp->state = IP_VS_TCP_S_LISTEN;
cp->timeout = ip_vs_protocol_tcp.timeout_table[IP_VS_TCP_S_LISTEN];
spin_unlock(&cp->lock);
}
static void ip_vs_tcp_init(struct ip_vs_protocol *pp)
{
IP_VS_INIT_HASH_TABLE(tcp_apps);
pp->timeout_table = tcp_timeouts;
}
static void ip_vs_tcp_exit(struct ip_vs_protocol *pp)
{
}
struct ip_vs_protocol ip_vs_protocol_tcp = {
.name = "TCP",
.protocol = IPPROTO_TCP,
.num_states = IP_VS_TCP_S_LAST,
.dont_defrag = 0,
.appcnt = ATOMIC_INIT(0),
.init = ip_vs_tcp_init,
.exit = ip_vs_tcp_exit,
.register_app = tcp_register_app,
.unregister_app = tcp_unregister_app,
.conn_schedule = tcp_conn_schedule,
.conn_in_get = tcp_conn_in_get,
.conn_out_get = tcp_conn_out_get,
.snat_handler = tcp_snat_handler,
.dnat_handler = tcp_dnat_handler,
.csum_check = tcp_csum_check,
.state_name = tcp_state_name,
.state_transition = tcp_state_transition,
.app_conn_bind = tcp_app_conn_bind,
.debug_packet = ip_vs_tcpudp_debug_packet,
.timeout_change = tcp_timeout_change,
.set_state_timeout = tcp_set_state_timeout,
};
