linux/net/netfilter/ipvs/ip_vs_proto_tcp.c
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   1/*
   2 * ip_vs_proto_tcp.c:   TCP load balancing support for IPVS
   3 *
   4 * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
   5 *              Julian Anastasov <ja@ssi.bg>
   6 *
   7 *              This program is free software; you can redistribute it and/or
   8 *              modify it under the terms of the GNU General Public License
   9 *              as published by the Free Software Foundation; either version
  10 *              2 of the License, or (at your option) any later version.
  11 *
  12 * Changes:
  13 *
  14 */
  15
  16#define KMSG_COMPONENT "IPVS"
  17#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  18
  19#include <linux/kernel.h>
  20#include <linux/ip.h>
  21#include <linux/tcp.h>                  /* for tcphdr */
  22#include <net/ip.h>
  23#include <net/tcp.h>                    /* for csum_tcpudp_magic */
  24#include <net/ip6_checksum.h>
  25#include <linux/netfilter.h>
  26#include <linux/netfilter_ipv4.h>
  27
  28#include <net/ip_vs.h>
  29
  30
  31static struct ip_vs_conn *
  32tcp_conn_in_get(int af, const struct sk_buff *skb, struct ip_vs_protocol *pp,
  33                const struct ip_vs_iphdr *iph, unsigned int proto_off,
  34                int inverse)
  35{
  36        __be16 _ports[2], *pptr;
  37
  38        pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
  39        if (pptr == NULL)
  40                return NULL;
  41
  42        if (likely(!inverse)) {
  43                return ip_vs_conn_in_get(af, iph->protocol,
  44                                         &iph->saddr, pptr[0],
  45                                         &iph->daddr, pptr[1]);
  46        } else {
  47                return ip_vs_conn_in_get(af, iph->protocol,
  48                                         &iph->daddr, pptr[1],
  49                                         &iph->saddr, pptr[0]);
  50        }
  51}
  52
  53static struct ip_vs_conn *
  54tcp_conn_out_get(int af, const struct sk_buff *skb, struct ip_vs_protocol *pp,
  55                 const struct ip_vs_iphdr *iph, unsigned int proto_off,
  56                 int inverse)
  57{
  58        __be16 _ports[2], *pptr;
  59
  60        pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
  61        if (pptr == NULL)
  62                return NULL;
  63
  64        if (likely(!inverse)) {
  65                return ip_vs_conn_out_get(af, iph->protocol,
  66                                          &iph->saddr, pptr[0],
  67                                          &iph->daddr, pptr[1]);
  68        } else {
  69                return ip_vs_conn_out_get(af, iph->protocol,
  70                                          &iph->daddr, pptr[1],
  71                                          &iph->saddr, pptr[0]);
  72        }
  73}
  74
  75
  76static int
  77tcp_conn_schedule(int af, struct sk_buff *skb, struct ip_vs_protocol *pp,
  78                  int *verdict, struct ip_vs_conn **cpp)
  79{
  80        struct ip_vs_service *svc;
  81        struct tcphdr _tcph, *th;
  82        struct ip_vs_iphdr iph;
  83
  84        ip_vs_fill_iphdr(af, skb_network_header(skb), &iph);
  85
  86        th = skb_header_pointer(skb, iph.len, sizeof(_tcph), &_tcph);
  87        if (th == NULL) {
  88                *verdict = NF_DROP;
  89                return 0;
  90        }
  91
  92        if (th->syn &&
  93            (svc = ip_vs_service_get(af, skb->mark, iph.protocol, &iph.daddr,
  94                                     th->dest))) {
  95                if (ip_vs_todrop()) {
  96                        /*
  97                         * It seems that we are very loaded.
  98                         * We have to drop this packet :(
  99                         */
 100                        ip_vs_service_put(svc);
 101                        *verdict = NF_DROP;
 102                        return 0;
 103                }
 104
 105                /*
 106                 * Let the virtual server select a real server for the
 107                 * incoming connection, and create a connection entry.
 108                 */
 109                *cpp = ip_vs_schedule(svc, skb);
 110                if (!*cpp) {
 111                        *verdict = ip_vs_leave(svc, skb, pp);
 112                        return 0;
 113                }
 114                ip_vs_service_put(svc);
 115        }
 116        return 1;
 117}
 118
 119
 120static inline void
 121tcp_fast_csum_update(int af, struct tcphdr *tcph,
 122                     const union nf_inet_addr *oldip,
 123                     const union nf_inet_addr *newip,
 124                     __be16 oldport, __be16 newport)
 125{
 126#ifdef CONFIG_IP_VS_IPV6
 127        if (af == AF_INET6)
 128                tcph->check =
 129                        csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
 130                                         ip_vs_check_diff2(oldport, newport,
 131                                                ~csum_unfold(tcph->check))));
 132        else
 133#endif
 134        tcph->check =
 135                csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
 136                                 ip_vs_check_diff2(oldport, newport,
 137                                                ~csum_unfold(tcph->check))));
 138}
 139
 140
 141static inline void
 142tcp_partial_csum_update(int af, struct tcphdr *tcph,
 143                     const union nf_inet_addr *oldip,
 144                     const union nf_inet_addr *newip,
 145                     __be16 oldlen, __be16 newlen)
 146{
 147#ifdef CONFIG_IP_VS_IPV6
 148        if (af == AF_INET6)
 149                tcph->check =
 150                        csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
 151                                         ip_vs_check_diff2(oldlen, newlen,
 152                                                ~csum_unfold(tcph->check))));
 153        else
 154#endif
 155        tcph->check =
 156                csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
 157                                ip_vs_check_diff2(oldlen, newlen,
 158                                                ~csum_unfold(tcph->check))));
 159}
 160
 161
 162static int
 163tcp_snat_handler(struct sk_buff *skb,
 164                 struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
 165{
 166        struct tcphdr *tcph;
 167        unsigned int tcphoff;
 168        int oldlen;
 169
 170#ifdef CONFIG_IP_VS_IPV6
 171        if (cp->af == AF_INET6)
 172                tcphoff = sizeof(struct ipv6hdr);
 173        else
 174#endif
 175                tcphoff = ip_hdrlen(skb);
 176        oldlen = skb->len - tcphoff;
 177
 178        /* csum_check requires unshared skb */
 179        if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
 180                return 0;
 181
 182        if (unlikely(cp->app != NULL)) {
 183                /* Some checks before mangling */
 184                if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
 185                        return 0;
 186
 187                /* Call application helper if needed */
 188                if (!ip_vs_app_pkt_out(cp, skb))
 189                        return 0;
 190        }
 191
 192        tcph = (void *)skb_network_header(skb) + tcphoff;
 193        tcph->source = cp->vport;
 194
 195        /* Adjust TCP checksums */
 196        if (skb->ip_summed == CHECKSUM_PARTIAL) {
 197                tcp_partial_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,
 198                                        htons(oldlen),
 199                                        htons(skb->len - tcphoff));
 200        } else if (!cp->app) {
 201                /* Only port and addr are changed, do fast csum update */
 202                tcp_fast_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,
 203                                     cp->dport, cp->vport);
 204                if (skb->ip_summed == CHECKSUM_COMPLETE)
 205                        skb->ip_summed = CHECKSUM_NONE;
 206        } else {
 207                /* full checksum calculation */
 208                tcph->check = 0;
 209                skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
 210#ifdef CONFIG_IP_VS_IPV6
 211                if (cp->af == AF_INET6)
 212                        tcph->check = csum_ipv6_magic(&cp->vaddr.in6,
 213                                                      &cp->caddr.in6,
 214                                                      skb->len - tcphoff,
 215                                                      cp->protocol, skb->csum);
 216                else
 217#endif
 218                        tcph->check = csum_tcpudp_magic(cp->vaddr.ip,
 219                                                        cp->caddr.ip,
 220                                                        skb->len - tcphoff,
 221                                                        cp->protocol,
 222                                                        skb->csum);
 223
 224                IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
 225                          pp->name, tcph->check,
 226                          (char*)&(tcph->check) - (char*)tcph);
 227        }
 228        return 1;
 229}
 230
 231
 232static int
 233tcp_dnat_handler(struct sk_buff *skb,
 234                 struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
 235{
 236        struct tcphdr *tcph;
 237        unsigned int tcphoff;
 238        int oldlen;
 239
 240#ifdef CONFIG_IP_VS_IPV6
 241        if (cp->af == AF_INET6)
 242                tcphoff = sizeof(struct ipv6hdr);
 243        else
 244#endif
 245                tcphoff = ip_hdrlen(skb);
 246        oldlen = skb->len - tcphoff;
 247
 248        /* csum_check requires unshared skb */
 249        if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
 250                return 0;
 251
 252        if (unlikely(cp->app != NULL)) {
 253                /* Some checks before mangling */
 254                if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
 255                        return 0;
 256
 257                /*
 258                 *      Attempt ip_vs_app call.
 259                 *      It will fix ip_vs_conn and iph ack_seq stuff
 260                 */
 261                if (!ip_vs_app_pkt_in(cp, skb))
 262                        return 0;
 263        }
 264
 265        tcph = (void *)skb_network_header(skb) + tcphoff;
 266        tcph->dest = cp->dport;
 267
 268        /*
 269         *      Adjust TCP checksums
 270         */
 271        if (skb->ip_summed == CHECKSUM_PARTIAL) {
 272                tcp_partial_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,
 273                                        htons(oldlen),
 274                                        htons(skb->len - tcphoff));
 275        } else if (!cp->app) {
 276                /* Only port and addr are changed, do fast csum update */
 277                tcp_fast_csum_update(cp->af, tcph, &cp->vaddr, &cp->daddr,
 278                                     cp->vport, cp->dport);
 279                if (skb->ip_summed == CHECKSUM_COMPLETE)
 280                        skb->ip_summed = CHECKSUM_NONE;
 281        } else {
 282                /* full checksum calculation */
 283                tcph->check = 0;
 284                skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
 285#ifdef CONFIG_IP_VS_IPV6
 286                if (cp->af == AF_INET6)
 287                        tcph->check = csum_ipv6_magic(&cp->caddr.in6,
 288                                                      &cp->daddr.in6,
 289                                                      skb->len - tcphoff,
 290                                                      cp->protocol, skb->csum);
 291                else
 292#endif
 293                        tcph->check = csum_tcpudp_magic(cp->caddr.ip,
 294                                                        cp->daddr.ip,
 295                                                        skb->len - tcphoff,
 296                                                        cp->protocol,
 297                                                        skb->csum);
 298                skb->ip_summed = CHECKSUM_UNNECESSARY;
 299        }
 300        return 1;
 301}
 302
 303
 304static int
 305tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
 306{
 307        unsigned int tcphoff;
 308
 309#ifdef CONFIG_IP_VS_IPV6
 310        if (af == AF_INET6)
 311                tcphoff = sizeof(struct ipv6hdr);
 312        else
 313#endif
 314                tcphoff = ip_hdrlen(skb);
 315
 316        switch (skb->ip_summed) {
 317        case CHECKSUM_NONE:
 318                skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
 319        case CHECKSUM_COMPLETE:
 320#ifdef CONFIG_IP_VS_IPV6
 321                if (af == AF_INET6) {
 322                        if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
 323                                            &ipv6_hdr(skb)->daddr,
 324                                            skb->len - tcphoff,
 325                                            ipv6_hdr(skb)->nexthdr,
 326                                            skb->csum)) {
 327                                IP_VS_DBG_RL_PKT(0, pp, skb, 0,
 328                                                 "Failed checksum for");
 329                                return 0;
 330                        }
 331                } else
 332#endif
 333                        if (csum_tcpudp_magic(ip_hdr(skb)->saddr,
 334                                              ip_hdr(skb)->daddr,
 335                                              skb->len - tcphoff,
 336                                              ip_hdr(skb)->protocol,
 337                                              skb->csum)) {
 338                                IP_VS_DBG_RL_PKT(0, pp, skb, 0,
 339                                                 "Failed checksum for");
 340                                return 0;
 341                        }
 342                break;
 343        default:
 344                /* No need to checksum. */
 345                break;
 346        }
 347
 348        return 1;
 349}
 350
 351
 352#define TCP_DIR_INPUT           0
 353#define TCP_DIR_OUTPUT          4
 354#define TCP_DIR_INPUT_ONLY      8
 355
 356static const int tcp_state_off[IP_VS_DIR_LAST] = {
 357        [IP_VS_DIR_INPUT]               =       TCP_DIR_INPUT,
 358        [IP_VS_DIR_OUTPUT]              =       TCP_DIR_OUTPUT,
 359        [IP_VS_DIR_INPUT_ONLY]          =       TCP_DIR_INPUT_ONLY,
 360};
 361
 362/*
 363 *      Timeout table[state]
 364 */
 365static int tcp_timeouts[IP_VS_TCP_S_LAST+1] = {
 366        [IP_VS_TCP_S_NONE]              =       2*HZ,
 367        [IP_VS_TCP_S_ESTABLISHED]       =       15*60*HZ,
 368        [IP_VS_TCP_S_SYN_SENT]          =       2*60*HZ,
 369        [IP_VS_TCP_S_SYN_RECV]          =       1*60*HZ,
 370        [IP_VS_TCP_S_FIN_WAIT]          =       2*60*HZ,
 371        [IP_VS_TCP_S_TIME_WAIT]         =       2*60*HZ,
 372        [IP_VS_TCP_S_CLOSE]             =       10*HZ,
 373        [IP_VS_TCP_S_CLOSE_WAIT]        =       60*HZ,
 374        [IP_VS_TCP_S_LAST_ACK]          =       30*HZ,
 375        [IP_VS_TCP_S_LISTEN]            =       2*60*HZ,
 376        [IP_VS_TCP_S_SYNACK]            =       120*HZ,
 377        [IP_VS_TCP_S_LAST]              =       2*HZ,
 378};
 379
 380static const char *const tcp_state_name_table[IP_VS_TCP_S_LAST+1] = {
 381        [IP_VS_TCP_S_NONE]              =       "NONE",
 382        [IP_VS_TCP_S_ESTABLISHED]       =       "ESTABLISHED",
 383        [IP_VS_TCP_S_SYN_SENT]          =       "SYN_SENT",
 384        [IP_VS_TCP_S_SYN_RECV]          =       "SYN_RECV",
 385        [IP_VS_TCP_S_FIN_WAIT]          =       "FIN_WAIT",
 386        [IP_VS_TCP_S_TIME_WAIT]         =       "TIME_WAIT",
 387        [IP_VS_TCP_S_CLOSE]             =       "CLOSE",
 388        [IP_VS_TCP_S_CLOSE_WAIT]        =       "CLOSE_WAIT",
 389        [IP_VS_TCP_S_LAST_ACK]          =       "LAST_ACK",
 390        [IP_VS_TCP_S_LISTEN]            =       "LISTEN",
 391        [IP_VS_TCP_S_SYNACK]            =       "SYNACK",
 392        [IP_VS_TCP_S_LAST]              =       "BUG!",
 393};
 394
 395#define sNO IP_VS_TCP_S_NONE
 396#define sES IP_VS_TCP_S_ESTABLISHED
 397#define sSS IP_VS_TCP_S_SYN_SENT
 398#define sSR IP_VS_TCP_S_SYN_RECV
 399#define sFW IP_VS_TCP_S_FIN_WAIT
 400#define sTW IP_VS_TCP_S_TIME_WAIT
 401#define sCL IP_VS_TCP_S_CLOSE
 402#define sCW IP_VS_TCP_S_CLOSE_WAIT
 403#define sLA IP_VS_TCP_S_LAST_ACK
 404#define sLI IP_VS_TCP_S_LISTEN
 405#define sSA IP_VS_TCP_S_SYNACK
 406
 407struct tcp_states_t {
 408        int next_state[IP_VS_TCP_S_LAST];
 409};
 410
 411static const char * tcp_state_name(int state)
 412{
 413        if (state >= IP_VS_TCP_S_LAST)
 414                return "ERR!";
 415        return tcp_state_name_table[state] ? tcp_state_name_table[state] : "?";
 416}
 417
 418static struct tcp_states_t tcp_states [] = {
 419/*      INPUT */
 420/*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
 421/*syn*/ {{sSR, sES, sES, sSR, sSR, sSR, sSR, sSR, sSR, sSR, sSR }},
 422/*fin*/ {{sCL, sCW, sSS, sTW, sTW, sTW, sCL, sCW, sLA, sLI, sTW }},
 423/*ack*/ {{sCL, sES, sSS, sES, sFW, sTW, sCL, sCW, sCL, sLI, sES }},
 424/*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sSR }},
 425
 426/*      OUTPUT */
 427/*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
 428/*syn*/ {{sSS, sES, sSS, sSR, sSS, sSS, sSS, sSS, sSS, sLI, sSR }},
 429/*fin*/ {{sTW, sFW, sSS, sTW, sFW, sTW, sCL, sTW, sLA, sLI, sTW }},
 430/*ack*/ {{sES, sES, sSS, sES, sFW, sTW, sCL, sCW, sLA, sES, sES }},
 431/*rst*/ {{sCL, sCL, sSS, sCL, sCL, sTW, sCL, sCL, sCL, sCL, sCL }},
 432
 433/*      INPUT-ONLY */
 434/*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
 435/*syn*/ {{sSR, sES, sES, sSR, sSR, sSR, sSR, sSR, sSR, sSR, sSR }},
 436/*fin*/ {{sCL, sFW, sSS, sTW, sFW, sTW, sCL, sCW, sLA, sLI, sTW }},
 437/*ack*/ {{sCL, sES, sSS, sES, sFW, sTW, sCL, sCW, sCL, sLI, sES }},
 438/*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sCL }},
 439};
 440
 441static struct tcp_states_t tcp_states_dos [] = {
 442/*      INPUT */
 443/*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
 444/*syn*/ {{sSR, sES, sES, sSR, sSR, sSR, sSR, sSR, sSR, sSR, sSA }},
 445/*fin*/ {{sCL, sCW, sSS, sTW, sTW, sTW, sCL, sCW, sLA, sLI, sSA }},
 446/*ack*/ {{sCL, sES, sSS, sSR, sFW, sTW, sCL, sCW, sCL, sLI, sSA }},
 447/*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sCL }},
 448
 449/*      OUTPUT */
 450/*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
 451/*syn*/ {{sSS, sES, sSS, sSA, sSS, sSS, sSS, sSS, sSS, sLI, sSA }},
 452/*fin*/ {{sTW, sFW, sSS, sTW, sFW, sTW, sCL, sTW, sLA, sLI, sTW }},
 453/*ack*/ {{sES, sES, sSS, sES, sFW, sTW, sCL, sCW, sLA, sES, sES }},
 454/*rst*/ {{sCL, sCL, sSS, sCL, sCL, sTW, sCL, sCL, sCL, sCL, sCL }},
 455
 456/*      INPUT-ONLY */
 457/*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
 458/*syn*/ {{sSA, sES, sES, sSR, sSA, sSA, sSA, sSA, sSA, sSA, sSA }},
 459/*fin*/ {{sCL, sFW, sSS, sTW, sFW, sTW, sCL, sCW, sLA, sLI, sTW }},
 460/*ack*/ {{sCL, sES, sSS, sES, sFW, sTW, sCL, sCW, sCL, sLI, sES }},
 461/*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sCL }},
 462};
 463
 464static struct tcp_states_t *tcp_state_table = tcp_states;
 465
 466
 467static void tcp_timeout_change(struct ip_vs_protocol *pp, int flags)
 468{
 469        int on = (flags & 1);           /* secure_tcp */
 470
 471        /*
 472        ** FIXME: change secure_tcp to independent sysctl var
 473        ** or make it per-service or per-app because it is valid
 474        ** for most if not for all of the applications. Something
 475        ** like "capabilities" (flags) for each object.
 476        */
 477        tcp_state_table = (on? tcp_states_dos : tcp_states);
 478}
 479
 480static int
 481tcp_set_state_timeout(struct ip_vs_protocol *pp, char *sname, int to)
 482{
 483        return ip_vs_set_state_timeout(pp->timeout_table, IP_VS_TCP_S_LAST,
 484                                       tcp_state_name_table, sname, to);
 485}
 486
 487static inline int tcp_state_idx(struct tcphdr *th)
 488{
 489        if (th->rst)
 490                return 3;
 491        if (th->syn)
 492                return 0;
 493        if (th->fin)
 494                return 1;
 495        if (th->ack)
 496                return 2;
 497        return -1;
 498}
 499
 500static inline void
 501set_tcp_state(struct ip_vs_protocol *pp, struct ip_vs_conn *cp,
 502              int direction, struct tcphdr *th)
 503{
 504        int state_idx;
 505        int new_state = IP_VS_TCP_S_CLOSE;
 506        int state_off = tcp_state_off[direction];
 507
 508        /*
 509         *    Update state offset to INPUT_ONLY if necessary
 510         *    or delete NO_OUTPUT flag if output packet detected
 511         */
 512        if (cp->flags & IP_VS_CONN_F_NOOUTPUT) {
 513                if (state_off == TCP_DIR_OUTPUT)
 514                        cp->flags &= ~IP_VS_CONN_F_NOOUTPUT;
 515                else
 516                        state_off = TCP_DIR_INPUT_ONLY;
 517        }
 518
 519        if ((state_idx = tcp_state_idx(th)) < 0) {
 520                IP_VS_DBG(8, "tcp_state_idx=%d!!!\n", state_idx);
 521                goto tcp_state_out;
 522        }
 523
 524        new_state = tcp_state_table[state_off+state_idx].next_state[cp->state];
 525
 526  tcp_state_out:
 527        if (new_state != cp->state) {
 528                struct ip_vs_dest *dest = cp->dest;
 529
 530                IP_VS_DBG_BUF(8, "%s %s [%c%c%c%c] %s:%d->"
 531                              "%s:%d state: %s->%s conn->refcnt:%d\n",
 532                              pp->name,
 533                              ((state_off == TCP_DIR_OUTPUT) ?
 534                               "output " : "input "),
 535                              th->syn ? 'S' : '.',
 536                              th->fin ? 'F' : '.',
 537                              th->ack ? 'A' : '.',
 538                              th->rst ? 'R' : '.',
 539                              IP_VS_DBG_ADDR(cp->af, &cp->daddr),
 540                              ntohs(cp->dport),
 541                              IP_VS_DBG_ADDR(cp->af, &cp->caddr),
 542                              ntohs(cp->cport),
 543                              tcp_state_name(cp->state),
 544                              tcp_state_name(new_state),
 545                              atomic_read(&cp->refcnt));
 546
 547                if (dest) {
 548                        if (!(cp->flags & IP_VS_CONN_F_INACTIVE) &&
 549                            (new_state != IP_VS_TCP_S_ESTABLISHED)) {
 550                                atomic_dec(&dest->activeconns);
 551                                atomic_inc(&dest->inactconns);
 552                                cp->flags |= IP_VS_CONN_F_INACTIVE;
 553                        } else if ((cp->flags & IP_VS_CONN_F_INACTIVE) &&
 554                                   (new_state == IP_VS_TCP_S_ESTABLISHED)) {
 555                                atomic_inc(&dest->activeconns);
 556                                atomic_dec(&dest->inactconns);
 557                                cp->flags &= ~IP_VS_CONN_F_INACTIVE;
 558                        }
 559                }
 560        }
 561
 562        cp->timeout = pp->timeout_table[cp->state = new_state];
 563}
 564
 565
 566/*
 567 *      Handle state transitions
 568 */
 569static int
 570tcp_state_transition(struct ip_vs_conn *cp, int direction,
 571                     const struct sk_buff *skb,
 572                     struct ip_vs_protocol *pp)
 573{
 574        struct tcphdr _tcph, *th;
 575
 576#ifdef CONFIG_IP_VS_IPV6
 577        int ihl = cp->af == AF_INET ? ip_hdrlen(skb) : sizeof(struct ipv6hdr);
 578#else
 579        int ihl = ip_hdrlen(skb);
 580#endif
 581
 582        th = skb_header_pointer(skb, ihl, sizeof(_tcph), &_tcph);
 583        if (th == NULL)
 584                return 0;
 585
 586        spin_lock(&cp->lock);
 587        set_tcp_state(pp, cp, direction, th);
 588        spin_unlock(&cp->lock);
 589
 590        return 1;
 591}
 592
 593
 594/*
 595 *      Hash table for TCP application incarnations
 596 */
 597#define TCP_APP_TAB_BITS        4
 598#define TCP_APP_TAB_SIZE        (1 << TCP_APP_TAB_BITS)
 599#define TCP_APP_TAB_MASK        (TCP_APP_TAB_SIZE - 1)
 600
 601static struct list_head tcp_apps[TCP_APP_TAB_SIZE];
 602static DEFINE_SPINLOCK(tcp_app_lock);
 603
 604static inline __u16 tcp_app_hashkey(__be16 port)
 605{
 606        return (((__force u16)port >> TCP_APP_TAB_BITS) ^ (__force u16)port)
 607                & TCP_APP_TAB_MASK;
 608}
 609
 610
 611static int tcp_register_app(struct ip_vs_app *inc)
 612{
 613        struct ip_vs_app *i;
 614        __u16 hash;
 615        __be16 port = inc->port;
 616        int ret = 0;
 617
 618        hash = tcp_app_hashkey(port);
 619
 620        spin_lock_bh(&tcp_app_lock);
 621        list_for_each_entry(i, &tcp_apps[hash], p_list) {
 622                if (i->port == port) {
 623                        ret = -EEXIST;
 624                        goto out;
 625                }
 626        }
 627        list_add(&inc->p_list, &tcp_apps[hash]);
 628        atomic_inc(&ip_vs_protocol_tcp.appcnt);
 629
 630  out:
 631        spin_unlock_bh(&tcp_app_lock);
 632        return ret;
 633}
 634
 635
 636static void
 637tcp_unregister_app(struct ip_vs_app *inc)
 638{
 639        spin_lock_bh(&tcp_app_lock);
 640        atomic_dec(&ip_vs_protocol_tcp.appcnt);
 641        list_del(&inc->p_list);
 642        spin_unlock_bh(&tcp_app_lock);
 643}
 644
 645
 646static int
 647tcp_app_conn_bind(struct ip_vs_conn *cp)
 648{
 649        int hash;
 650        struct ip_vs_app *inc;
 651        int result = 0;
 652
 653        /* Default binding: bind app only for NAT */
 654        if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
 655                return 0;
 656
 657        /* Lookup application incarnations and bind the right one */
 658        hash = tcp_app_hashkey(cp->vport);
 659
 660        spin_lock(&tcp_app_lock);
 661        list_for_each_entry(inc, &tcp_apps[hash], p_list) {
 662                if (inc->port == cp->vport) {
 663                        if (unlikely(!ip_vs_app_inc_get(inc)))
 664                                break;
 665                        spin_unlock(&tcp_app_lock);
 666
 667                        IP_VS_DBG_BUF(9, "%s(): Binding conn %s:%u->"
 668                                      "%s:%u to app %s on port %u\n",
 669                                      __func__,
 670                                      IP_VS_DBG_ADDR(cp->af, &cp->caddr),
 671                                      ntohs(cp->cport),
 672                                      IP_VS_DBG_ADDR(cp->af, &cp->vaddr),
 673                                      ntohs(cp->vport),
 674                                      inc->name, ntohs(inc->port));
 675
 676                        cp->app = inc;
 677                        if (inc->init_conn)
 678                                result = inc->init_conn(inc, cp);
 679                        goto out;
 680                }
 681        }
 682        spin_unlock(&tcp_app_lock);
 683
 684  out:
 685        return result;
 686}
 687
 688
 689/*
 690 *      Set LISTEN timeout. (ip_vs_conn_put will setup timer)
 691 */
 692void ip_vs_tcp_conn_listen(struct ip_vs_conn *cp)
 693{
 694        spin_lock(&cp->lock);
 695        cp->state = IP_VS_TCP_S_LISTEN;
 696        cp->timeout = ip_vs_protocol_tcp.timeout_table[IP_VS_TCP_S_LISTEN];
 697        spin_unlock(&cp->lock);
 698}
 699
 700
 701static void ip_vs_tcp_init(struct ip_vs_protocol *pp)
 702{
 703        IP_VS_INIT_HASH_TABLE(tcp_apps);
 704        pp->timeout_table = tcp_timeouts;
 705}
 706
 707
 708static void ip_vs_tcp_exit(struct ip_vs_protocol *pp)
 709{
 710}
 711
 712
 713struct ip_vs_protocol ip_vs_protocol_tcp = {
 714        .name =                 "TCP",
 715        .protocol =             IPPROTO_TCP,
 716        .num_states =           IP_VS_TCP_S_LAST,
 717        .dont_defrag =          0,
 718        .appcnt =               ATOMIC_INIT(0),
 719        .init =                 ip_vs_tcp_init,
 720        .exit =                 ip_vs_tcp_exit,
 721        .register_app =         tcp_register_app,
 722        .unregister_app =       tcp_unregister_app,
 723        .conn_schedule =        tcp_conn_schedule,
 724        .conn_in_get =          tcp_conn_in_get,
 725        .conn_out_get =         tcp_conn_out_get,
 726        .snat_handler =         tcp_snat_handler,
 727        .dnat_handler =         tcp_dnat_handler,
 728        .csum_check =           tcp_csum_check,
 729        .state_name =           tcp_state_name,
 730        .state_transition =     tcp_state_transition,
 731        .app_conn_bind =        tcp_app_conn_bind,
 732        .debug_packet =         ip_vs_tcpudp_debug_packet,
 733        .timeout_change =       tcp_timeout_change,
 734        .set_state_timeout =    tcp_set_state_timeout,
 735};
 736