net/netfilter/ipvs/ip_vs_proto_tcp.c

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