/* * ip_vs_proto_tcp.c: TCP load balancing support for IPVS * * Version: $Id: ip_vs_proto_tcp.c,v 1.3 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/ip.h> #include <net/tcp.h> /* for csum_tcpudp_magic */ #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) { __u16 _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) { __u16 _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, skb->nh.iph->ihl*4, sizeof(_tcph), &_tcph); if (th == NULL) { *verdict = NF_DROP; return 0; } if (th->syn && (svc = ip_vs_service_get(skb->nfmark, skb->nh.iph->protocol, skb->nh.iph->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, u32 oldip, u32 newip, u16 oldport, u16 newport) { tcph->check = ip_vs_check_diff(~oldip, newip, ip_vs_check_diff(oldport ^ 0xFFFF, newport, tcph->check)); } static int tcp_snat_handler(struct sk_buff **pskb, struct ip_vs_protocol *pp, struct ip_vs_conn *cp) { struct tcphdr *tcph; unsigned int tcphoff = (*pskb)->nh.iph->ihl * 4; /* csum_check requires unshared skb */ if (!ip_vs_make_skb_writable(pskb, tcphoff+sizeof(*tcph))) return 0; if (unlikely(cp->app != NULL)) { /* Some checks before mangling */ if (pp->csum_check && !pp->csum_check(*pskb, pp)) return 0; /* Call application helper if needed */ if (!ip_vs_app_pkt_out(cp, pskb)) return 0; } tcph = (void *)(*pskb)->nh.iph + 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 ((*pskb)->ip_summed == CHECKSUM_HW) (*pskb)->ip_summed = CHECKSUM_NONE; } else { /* full checksum calculation */ tcph->check = 0; (*pskb)->csum = skb_checksum(*pskb, tcphoff, (*pskb)->len - tcphoff, 0); tcph->check = csum_tcpudp_magic(cp->vaddr, cp->caddr, (*pskb)->len - tcphoff, cp->protocol, (*pskb)->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 **pskb, struct ip_vs_protocol *pp, struct ip_vs_conn *cp) { struct tcphdr *tcph; unsigned int tcphoff = (*pskb)->nh.iph->ihl * 4; /* csum_check requires unshared skb */ if (!ip_vs_make_skb_writable(pskb, tcphoff+sizeof(*tcph))) return 0; if (unlikely(cp->app != NULL)) { /* Some checks before mangling */ if (pp->csum_check && !pp->csum_check(*pskb, 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, pskb)) return 0; } tcph = (void *)(*pskb)->nh.iph + 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 ((*pskb)->ip_summed == CHECKSUM_HW) (*pskb)->ip_summed = CHECKSUM_NONE; } else { /* full checksum calculation */ tcph->check = 0; (*pskb)->csum = skb_checksum(*pskb, tcphoff, (*pskb)->len - tcphoff, 0); tcph->check = csum_tcpudp_magic(cp->caddr, cp->daddr, (*pskb)->len - tcphoff, cp->protocol, (*pskb)->csum); (*pskb)->ip_summed = CHECKSUM_UNNECESSARY; } return 1; } static int tcp_csum_check(struct sk_buff *skb, struct ip_vs_protocol *pp) { unsigned int tcphoff = skb->nh.iph->ihl*4; switch (skb->ip_summed) { case CHECKSUM_NONE: skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0); case CHECKSUM_HW: if (csum_tcpudp_magic(skb->nh.iph->saddr, skb->nh.iph->daddr, skb->len - tcphoff, skb->nh.iph->protocol, skb->csum)) { IP_VS_DBG_RL_PKT(0, pp, skb, 0, "Failed checksum for"); return 0; } break; default: /* CHECKSUM_UNNECESSARY */ 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, skb->nh.iph->ihl*4, 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(__u16 port) { return ((port >> TCP_APP_TAB_BITS) ^ port) & TCP_APP_TAB_MASK; } static int tcp_register_app(struct ip_vs_app *inc) { struct ip_vs_app *i; __u16 hash, 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", __FUNCTION__, 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, .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, };