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
  31 static struct ip_vs_conn *
  32 tcp_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
  53 static struct ip_vs_conn *
  54 tcp_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
  76 static int
  77 tcp_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
 120 static inline void
 121 tcp_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
 141 static inline void
 142 tcp_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
 162 static int
 163 tcp_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
 232 static int
 233 tcp_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
 304 static int
 305 tcp_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
 356 static 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  */
 365 static 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
 380 static 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
 407 struct tcp_states_t {
 408         int next_state[IP_VS_TCP_S_LAST];
 409 };
 410
 411 static 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
 418 static 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
 441 static 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
 464 static struct tcp_states_t *tcp_state_table = tcp_states;
 465
 466
 467 static 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
 480 static int
 481 tcp_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
 487 static 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
 500 static inline void
 501 set_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  */
 569 static int
 570 tcp_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
 601 static struct list_head tcp_apps[TCP_APP_TAB_SIZE];
 602 static DEFINE_SPINLOCK(tcp_app_lock);
 603
 604 static 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
 611 static 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
 636 static void
 637 tcp_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
 646 static int
 647 tcp_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  */
 692 void 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
 701 static 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
 708 static void ip_vs_tcp_exit(struct ip_vs_protocol *pp)
 709 {
 710 }
 711
 712
 713 struct 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 };