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