git.oblomov.eu Git - linux-2.6/blob - net/ipv4/ipvs/ip_vs_core.c

   1 /*
   2  * IPVS         An implementation of the IP virtual server support for the
   3  *              LINUX operating system.  IPVS is now implemented as a module
   4  *              over the Netfilter framework. IPVS can be used to build a
   5  *              high-performance and highly available server based on a
   6  *              cluster of servers.
   7  *
   8  * Version:     $Id: ip_vs_core.c,v 1.34 2003/05/10 03:05:23 wensong Exp $
   9  *
  10  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
  11  *              Peter Kese <peter.kese@ijs.si>
  12  *              Julian Anastasov <ja@ssi.bg>
  13  *
  14  *              This program is free software; you can redistribute it and/or
  15  *              modify it under the terms of the GNU General Public License
  16  *              as published by the Free Software Foundation; either version
  17  *              2 of the License, or (at your option) any later version.
  18  *
  19  * The IPVS code for kernel 2.2 was done by Wensong Zhang and Peter Kese,
  20  * with changes/fixes from Julian Anastasov, Lars Marowsky-Bree, Horms
  21  * and others.
  22  *
  23  * Changes:
  24  *      Paul `Rusty' Russell            properly handle non-linear skbs
  25  *      Harald Welte                    don't use nfcache
  26  *
  27  */
  28
  29 #include <linux/module.h>
  30 #include <linux/kernel.h>
  31 #include <linux/ip.h>
  32 #include <linux/tcp.h>
  33 #include <linux/icmp.h>
  34
  35 #include <net/ip.h>
  36 #include <net/tcp.h>
  37 #include <net/udp.h>
  38 #include <net/icmp.h>                   /* for icmp_send */
  39 #include <net/route.h>
  40
  41 #include <linux/netfilter.h>
  42 #include <linux/netfilter_ipv4.h>
  43
  44 #include <net/ip_vs.h>
  45
  46
  47 EXPORT_SYMBOL(register_ip_vs_scheduler);
  48 EXPORT_SYMBOL(unregister_ip_vs_scheduler);
  49 EXPORT_SYMBOL(ip_vs_skb_replace);
  50 EXPORT_SYMBOL(ip_vs_proto_name);
  51 EXPORT_SYMBOL(ip_vs_conn_new);
  52 EXPORT_SYMBOL(ip_vs_conn_in_get);
  53 EXPORT_SYMBOL(ip_vs_conn_out_get);
  54 #ifdef CONFIG_IP_VS_PROTO_TCP
  55 EXPORT_SYMBOL(ip_vs_tcp_conn_listen);
  56 #endif
  57 EXPORT_SYMBOL(ip_vs_conn_put);
  58 #ifdef CONFIG_IP_VS_DEBUG
  59 EXPORT_SYMBOL(ip_vs_get_debug_level);
  60 #endif
  61
  62
  63 /* ID used in ICMP lookups */
  64 #define icmp_id(icmph)          (((icmph)->un).echo.id)
  65
  66 const char *ip_vs_proto_name(unsigned proto)
  67 {
  68         static char buf[20];
  69
  70         switch (proto) {
  71         case IPPROTO_IP:
  72                 return "IP";
  73         case IPPROTO_UDP:
  74                 return "UDP";
  75         case IPPROTO_TCP:
  76                 return "TCP";
  77         case IPPROTO_ICMP:
  78                 return "ICMP";
  79         default:
  80                 sprintf(buf, "IP_%d", proto);
  81                 return buf;
  82         }
  83 }
  84
  85 void ip_vs_init_hash_table(struct list_head *table, int rows)
  86 {
  87         while (--rows >= 0)
  88                 INIT_LIST_HEAD(&table[rows]);
  89 }
  90
  91 static inline void
  92 ip_vs_in_stats(struct ip_vs_conn *cp, struct sk_buff *skb)
  93 {
  94         struct ip_vs_dest *dest = cp->dest;
  95         if (dest && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
  96                 spin_lock(&dest->stats.lock);
  97                 dest->stats.inpkts++;
  98                 dest->stats.inbytes += skb->len;
  99                 spin_unlock(&dest->stats.lock);
 100
 101                 spin_lock(&dest->svc->stats.lock);
 102                 dest->svc->stats.inpkts++;
 103                 dest->svc->stats.inbytes += skb->len;
 104                 spin_unlock(&dest->svc->stats.lock);
 105
 106                 spin_lock(&ip_vs_stats.lock);
 107                 ip_vs_stats.inpkts++;
 108                 ip_vs_stats.inbytes += skb->len;
 109                 spin_unlock(&ip_vs_stats.lock);
 110         }
 111 }
 112
 113
 114 static inline void
 115 ip_vs_out_stats(struct ip_vs_conn *cp, struct sk_buff *skb)
 116 {
 117         struct ip_vs_dest *dest = cp->dest;
 118         if (dest && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
 119                 spin_lock(&dest->stats.lock);
 120                 dest->stats.outpkts++;
 121                 dest->stats.outbytes += skb->len;
 122                 spin_unlock(&dest->stats.lock);
 123
 124                 spin_lock(&dest->svc->stats.lock);
 125                 dest->svc->stats.outpkts++;
 126                 dest->svc->stats.outbytes += skb->len;
 127                 spin_unlock(&dest->svc->stats.lock);
 128
 129                 spin_lock(&ip_vs_stats.lock);
 130                 ip_vs_stats.outpkts++;
 131                 ip_vs_stats.outbytes += skb->len;
 132                 spin_unlock(&ip_vs_stats.lock);
 133         }
 134 }
 135
 136
 137 static inline void
 138 ip_vs_conn_stats(struct ip_vs_conn *cp, struct ip_vs_service *svc)
 139 {
 140         spin_lock(&cp->dest->stats.lock);
 141         cp->dest->stats.conns++;
 142         spin_unlock(&cp->dest->stats.lock);
 143
 144         spin_lock(&svc->stats.lock);
 145         svc->stats.conns++;
 146         spin_unlock(&svc->stats.lock);
 147
 148         spin_lock(&ip_vs_stats.lock);
 149         ip_vs_stats.conns++;
 150         spin_unlock(&ip_vs_stats.lock);
 151 }
 152
 153
 154 static inline int
 155 ip_vs_set_state(struct ip_vs_conn *cp, int direction,
 156                 const struct sk_buff *skb,
 157                 struct ip_vs_protocol *pp)
 158 {
 159         if (unlikely(!pp->state_transition))
 160                 return 0;
 161         return pp->state_transition(cp, direction, skb, pp);
 162 }
 163
 164
 165 /*
 166  *  IPVS persistent scheduling function
 167  *  It creates a connection entry according to its template if exists,
 168  *  or selects a server and creates a connection entry plus a template.
 169  *  Locking: we are svc user (svc->refcnt), so we hold all dests too
 170  *  Protocols supported: TCP, UDP
 171  */
 172 static struct ip_vs_conn *
 173 ip_vs_sched_persist(struct ip_vs_service *svc,
 174                     const struct sk_buff *skb,
 175                     __be16 ports[2])
 176 {
 177         struct ip_vs_conn *cp = NULL;
 178         struct iphdr *iph = ip_hdr(skb);
 179         struct ip_vs_dest *dest;
 180         struct ip_vs_conn *ct;
 181         __be16  dport;   /* destination port to forward */
 182         __be32  snet;    /* source network of the client, after masking */
 183
 184         /* Mask saddr with the netmask to adjust template granularity */
 185         snet = iph->saddr & svc->netmask;
 186
 187         IP_VS_DBG(6, "p-schedule: src %u.%u.%u.%u:%u dest %u.%u.%u.%u:%u "
 188                   "mnet %u.%u.%u.%u\n",
 189                   NIPQUAD(iph->saddr), ntohs(ports[0]),
 190                   NIPQUAD(iph->daddr), ntohs(ports[1]),
 191                   NIPQUAD(snet));
 192
 193         /*
 194          * As far as we know, FTP is a very complicated network protocol, and
 195          * it uses control connection and data connections. For active FTP,
 196          * FTP server initialize data connection to the client, its source port
 197          * is often 20. For passive FTP, FTP server tells the clients the port
 198          * that it passively listens to,  and the client issues the data
 199          * connection. In the tunneling or direct routing mode, the load
 200          * balancer is on the client-to-server half of connection, the port
 201          * number is unknown to the load balancer. So, a conn template like
 202          * <caddr, 0, vaddr, 0, daddr, 0> is created for persistent FTP
 203          * service, and a template like <caddr, 0, vaddr, vport, daddr, dport>
 204          * is created for other persistent services.
 205          */
 206         if (ports[1] == svc->port) {
 207                 /* Check if a template already exists */
 208                 if (svc->port != FTPPORT)
 209                         ct = ip_vs_ct_in_get(iph->protocol, snet, 0,
 210                                                iph->daddr, ports[1]);
 211                 else
 212                         ct = ip_vs_ct_in_get(iph->protocol, snet, 0,
 213                                                iph->daddr, 0);
 214
 215                 if (!ct || !ip_vs_check_template(ct)) {
 216                         /*
 217                          * No template found or the dest of the connection
 218                          * template is not available.
 219                          */
 220                         dest = svc->scheduler->schedule(svc, skb);
 221                         if (dest == NULL) {
 222                                 IP_VS_DBG(1, "p-schedule: no dest found.\n");
 223                                 return NULL;
 224                         }
 225
 226                         /*
 227                          * Create a template like <protocol,caddr,0,
 228                          * vaddr,vport,daddr,dport> for non-ftp service,
 229                          * and <protocol,caddr,0,vaddr,0,daddr,0>
 230                          * for ftp service.
 231                          */
 232                         if (svc->port != FTPPORT)
 233                                 ct = ip_vs_conn_new(iph->protocol,
 234                                                     snet, 0,
 235                                                     iph->daddr,
 236                                                     ports[1],
 237                                                     dest->addr, dest->port,
 238                                                     IP_VS_CONN_F_TEMPLATE,
 239                                                     dest);
 240                         else
 241                                 ct = ip_vs_conn_new(iph->protocol,
 242                                                     snet, 0,
 243                                                     iph->daddr, 0,
 244                                                     dest->addr, 0,
 245                                                     IP_VS_CONN_F_TEMPLATE,
 246                                                     dest);
 247                         if (ct == NULL)
 248                                 return NULL;
 249
 250                         ct->timeout = svc->timeout;
 251                 } else {
 252                         /* set destination with the found template */
 253                         dest = ct->dest;
 254                 }
 255                 dport = dest->port;
 256         } else {
 257                 /*
 258                  * Note: persistent fwmark-based services and persistent
 259                  * port zero service are handled here.
 260                  * fwmark template: <IPPROTO_IP,caddr,0,fwmark,0,daddr,0>
 261                  * port zero template: <protocol,caddr,0,vaddr,0,daddr,0>
 262                  */
 263                 if (svc->fwmark)
 264                         ct = ip_vs_ct_in_get(IPPROTO_IP, snet, 0,
 265                                                htonl(svc->fwmark), 0);
 266                 else
 267                         ct = ip_vs_ct_in_get(iph->protocol, snet, 0,
 268                                                iph->daddr, 0);
 269
 270                 if (!ct || !ip_vs_check_template(ct)) {
 271                         /*
 272                          * If it is not persistent port zero, return NULL,
 273                          * otherwise create a connection template.
 274                          */
 275                         if (svc->port)
 276                                 return NULL;
 277
 278                         dest = svc->scheduler->schedule(svc, skb);
 279                         if (dest == NULL) {
 280                                 IP_VS_DBG(1, "p-schedule: no dest found.\n");
 281                                 return NULL;
 282                         }
 283
 284                         /*
 285                          * Create a template according to the service
 286                          */
 287                         if (svc->fwmark)
 288                                 ct = ip_vs_conn_new(IPPROTO_IP,
 289                                                     snet, 0,
 290                                                     htonl(svc->fwmark), 0,
 291                                                     dest->addr, 0,
 292                                                     IP_VS_CONN_F_TEMPLATE,
 293                                                     dest);
 294                         else
 295                                 ct = ip_vs_conn_new(iph->protocol,
 296                                                     snet, 0,
 297                                                     iph->daddr, 0,
 298                                                     dest->addr, 0,
 299                                                     IP_VS_CONN_F_TEMPLATE,
 300                                                     dest);
 301                         if (ct == NULL)
 302                                 return NULL;
 303
 304                         ct->timeout = svc->timeout;
 305                 } else {
 306                         /* set destination with the found template */
 307                         dest = ct->dest;
 308                 }
 309                 dport = ports[1];
 310         }
 311
 312         /*
 313          *    Create a new connection according to the template
 314          */
 315         cp = ip_vs_conn_new(iph->protocol,
 316                             iph->saddr, ports[0],
 317                             iph->daddr, ports[1],
 318                             dest->addr, dport,
 319                             0,
 320                             dest);
 321         if (cp == NULL) {
 322                 ip_vs_conn_put(ct);
 323                 return NULL;
 324         }
 325
 326         /*
 327          *    Add its control
 328          */
 329         ip_vs_control_add(cp, ct);
 330         ip_vs_conn_put(ct);
 331
 332         ip_vs_conn_stats(cp, svc);
 333         return cp;
 334 }
 335
 336
 337 /*
 338  *  IPVS main scheduling function
 339  *  It selects a server according to the virtual service, and
 340  *  creates a connection entry.
 341  *  Protocols supported: TCP, UDP
 342  */
 343 struct ip_vs_conn *
 344 ip_vs_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
 345 {
 346         struct ip_vs_conn *cp = NULL;
 347         struct iphdr *iph = ip_hdr(skb);
 348         struct ip_vs_dest *dest;
 349         __be16 _ports[2], *pptr;
 350
 351         pptr = skb_header_pointer(skb, iph->ihl*4,
 352                                   sizeof(_ports), _ports);
 353         if (pptr == NULL)
 354                 return NULL;
 355
 356         /*
 357          *    Persistent service
 358          */
 359         if (svc->flags & IP_VS_SVC_F_PERSISTENT)
 360                 return ip_vs_sched_persist(svc, skb, pptr);
 361
 362         /*
 363          *    Non-persistent service
 364          */
 365         if (!svc->fwmark && pptr[1] != svc->port) {
 366                 if (!svc->port)
 367                         IP_VS_ERR("Schedule: port zero only supported "
 368                                   "in persistent services, "
 369                                   "check your ipvs configuration\n");
 370                 return NULL;
 371         }
 372
 373         dest = svc->scheduler->schedule(svc, skb);
 374         if (dest == NULL) {
 375                 IP_VS_DBG(1, "Schedule: no dest found.\n");
 376                 return NULL;
 377         }
 378
 379         /*
 380          *    Create a connection entry.
 381          */
 382         cp = ip_vs_conn_new(iph->protocol,
 383                             iph->saddr, pptr[0],
 384                             iph->daddr, pptr[1],
 385                             dest->addr, dest->port?dest->port:pptr[1],
 386                             0,
 387                             dest);
 388         if (cp == NULL)
 389                 return NULL;
 390
 391         IP_VS_DBG(6, "Schedule fwd:%c c:%u.%u.%u.%u:%u v:%u.%u.%u.%u:%u "
 392                   "d:%u.%u.%u.%u:%u conn->flags:%X conn->refcnt:%d\n",
 393                   ip_vs_fwd_tag(cp),
 394                   NIPQUAD(cp->caddr), ntohs(cp->cport),
 395                   NIPQUAD(cp->vaddr), ntohs(cp->vport),
 396                   NIPQUAD(cp->daddr), ntohs(cp->dport),
 397                   cp->flags, atomic_read(&cp->refcnt));
 398
 399         ip_vs_conn_stats(cp, svc);
 400         return cp;
 401 }
 402
 403
 404 /*
 405  *  Pass or drop the packet.
 406  *  Called by ip_vs_in, when the virtual service is available but
 407  *  no destination is available for a new connection.
 408  */
 409 int ip_vs_leave(struct ip_vs_service *svc, struct sk_buff *skb,
 410                 struct ip_vs_protocol *pp)
 411 {
 412         __be16 _ports[2], *pptr;
 413         struct iphdr *iph = ip_hdr(skb);
 414
 415         pptr = skb_header_pointer(skb, iph->ihl*4,
 416                                   sizeof(_ports), _ports);
 417         if (pptr == NULL) {
 418                 ip_vs_service_put(svc);
 419                 return NF_DROP;
 420         }
 421
 422         /* if it is fwmark-based service, the cache_bypass sysctl is up
 423            and the destination is RTN_UNICAST (and not local), then create
 424            a cache_bypass connection entry */
 425         if (sysctl_ip_vs_cache_bypass && svc->fwmark
 426             && (inet_addr_type(iph->daddr) == RTN_UNICAST)) {
 427                 int ret, cs;
 428                 struct ip_vs_conn *cp;
 429
 430                 ip_vs_service_put(svc);
 431
 432                 /* create a new connection entry */
 433                 IP_VS_DBG(6, "ip_vs_leave: create a cache_bypass entry\n");
 434                 cp = ip_vs_conn_new(iph->protocol,
 435                                     iph->saddr, pptr[0],
 436                                     iph->daddr, pptr[1],
 437                                     0, 0,
 438                                     IP_VS_CONN_F_BYPASS,
 439                                     NULL);
 440                 if (cp == NULL)
 441                         return NF_DROP;
 442
 443                 /* statistics */
 444                 ip_vs_in_stats(cp, skb);
 445
 446                 /* set state */
 447                 cs = ip_vs_set_state(cp, IP_VS_DIR_INPUT, skb, pp);
 448
 449                 /* transmit the first SYN packet */
 450                 ret = cp->packet_xmit(skb, cp, pp);
 451                 /* do not touch skb anymore */
 452
 453                 atomic_inc(&cp->in_pkts);
 454                 ip_vs_conn_put(cp);
 455                 return ret;
 456         }
 457
 458         /*
 459          * When the virtual ftp service is presented, packets destined
 460          * for other services on the VIP may get here (except services
 461          * listed in the ipvs table), pass the packets, because it is
 462          * not ipvs job to decide to drop the packets.
 463          */
 464         if ((svc->port == FTPPORT) && (pptr[1] != FTPPORT)) {
 465                 ip_vs_service_put(svc);
 466                 return NF_ACCEPT;
 467         }
 468
 469         ip_vs_service_put(svc);
 470
 471         /*
 472          * Notify the client that the destination is unreachable, and
 473          * release the socket buffer.
 474          * Since it is in IP layer, the TCP socket is not actually
 475          * created, the TCP RST packet cannot be sent, instead that
 476          * ICMP_PORT_UNREACH is sent here no matter it is TCP/UDP. --WZ
 477          */
 478         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 479         return NF_DROP;
 480 }
 481
 482
 483 /*
 484  *      It is hooked before NF_IP_PRI_NAT_SRC at the NF_INET_POST_ROUTING
 485  *      chain, and is used for VS/NAT.
 486  *      It detects packets for VS/NAT connections and sends the packets
 487  *      immediately. This can avoid that iptable_nat mangles the packets
 488  *      for VS/NAT.
 489  */
 490 static unsigned int ip_vs_post_routing(unsigned int hooknum,
 491                                        struct sk_buff *skb,
 492                                        const struct net_device *in,
 493                                        const struct net_device *out,
 494                                        int (*okfn)(struct sk_buff *))
 495 {
 496         if (!skb->ipvs_property)
 497                 return NF_ACCEPT;
 498         /* The packet was sent from IPVS, exit this chain */
 499         return NF_STOP;
 500 }
 501
 502 __sum16 ip_vs_checksum_complete(struct sk_buff *skb, int offset)
 503 {
 504         return csum_fold(skb_checksum(skb, offset, skb->len - offset, 0));
 505 }
 506
 507 static inline int ip_vs_gather_frags(struct sk_buff *skb, u_int32_t user)
 508 {
 509         int err = ip_defrag(skb, user);
 510
 511         if (!err)
 512                 ip_send_check(ip_hdr(skb));
 513
 514         return err;
 515 }
 516
 517 /*
 518  * Packet has been made sufficiently writable in caller
 519  * - inout: 1=in->out, 0=out->in
 520  */
 521 void ip_vs_nat_icmp(struct sk_buff *skb, struct ip_vs_protocol *pp,
 522                     struct ip_vs_conn *cp, int inout)
 523 {
 524         struct iphdr *iph        = ip_hdr(skb);
 525         unsigned int icmp_offset = iph->ihl*4;
 526         struct icmphdr *icmph    = (struct icmphdr *)(skb_network_header(skb) +
 527                                                       icmp_offset);
 528         struct iphdr *ciph       = (struct iphdr *)(icmph + 1);
 529
 530         if (inout) {
 531                 iph->saddr = cp->vaddr;
 532                 ip_send_check(iph);
 533                 ciph->daddr = cp->vaddr;
 534                 ip_send_check(ciph);
 535         } else {
 536                 iph->daddr = cp->daddr;
 537                 ip_send_check(iph);
 538                 ciph->saddr = cp->daddr;
 539                 ip_send_check(ciph);
 540         }
 541
 542         /* the TCP/UDP port */
 543         if (IPPROTO_TCP == ciph->protocol || IPPROTO_UDP == ciph->protocol) {
 544                 __be16 *ports = (void *)ciph + ciph->ihl*4;
 545
 546                 if (inout)
 547                         ports[1] = cp->vport;
 548                 else
 549                         ports[0] = cp->dport;
 550         }
 551
 552         /* And finally the ICMP checksum */
 553         icmph->checksum = 0;
 554         icmph->checksum = ip_vs_checksum_complete(skb, icmp_offset);
 555         skb->ip_summed = CHECKSUM_UNNECESSARY;
 556
 557         if (inout)
 558                 IP_VS_DBG_PKT(11, pp, skb, (void *)ciph - (void *)iph,
 559                         "Forwarding altered outgoing ICMP");
 560         else
 561                 IP_VS_DBG_PKT(11, pp, skb, (void *)ciph - (void *)iph,
 562                         "Forwarding altered incoming ICMP");
 563 }
 564
 565 /*
 566  *      Handle ICMP messages in the inside-to-outside direction (outgoing).
 567  *      Find any that might be relevant, check against existing connections,
 568  *      forward to the right destination host if relevant.
 569  *      Currently handles error types - unreachable, quench, ttl exceeded.
 570  *      (Only used in VS/NAT)
 571  */
 572 static int ip_vs_out_icmp(struct sk_buff *skb, int *related)
 573 {
 574         struct iphdr *iph;
 575         struct icmphdr  _icmph, *ic;
 576         struct iphdr    _ciph, *cih;    /* The ip header contained within the ICMP */
 577         struct ip_vs_conn *cp;
 578         struct ip_vs_protocol *pp;
 579         unsigned int offset, ihl, verdict;
 580
 581         *related = 1;
 582
 583         /* reassemble IP fragments */
 584         if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
 585                 if (ip_vs_gather_frags(skb, IP_DEFRAG_VS_OUT))
 586                         return NF_STOLEN;
 587         }
 588
 589         iph = ip_hdr(skb);
 590         offset = ihl = iph->ihl * 4;
 591         ic = skb_header_pointer(skb, offset, sizeof(_icmph), &_icmph);
 592         if (ic == NULL)
 593                 return NF_DROP;
 594
 595         IP_VS_DBG(12, "Outgoing ICMP (%d,%d) %u.%u.%u.%u->%u.%u.%u.%u\n",
 596                   ic->type, ntohs(icmp_id(ic)),
 597                   NIPQUAD(iph->saddr), NIPQUAD(iph->daddr));
 598
 599         /*
 600          * Work through seeing if this is for us.
 601          * These checks are supposed to be in an order that means easy
 602          * things are checked first to speed up processing.... however
 603          * this means that some packets will manage to get a long way
 604          * down this stack and then be rejected, but that's life.
 605          */
 606         if ((ic->type != ICMP_DEST_UNREACH) &&
 607             (ic->type != ICMP_SOURCE_QUENCH) &&
 608             (ic->type != ICMP_TIME_EXCEEDED)) {
 609                 *related = 0;
 610                 return NF_ACCEPT;
 611         }
 612
 613         /* Now find the contained IP header */
 614         offset += sizeof(_icmph);
 615         cih = skb_header_pointer(skb, offset, sizeof(_ciph), &_ciph);
 616         if (cih == NULL)
 617                 return NF_ACCEPT; /* The packet looks wrong, ignore */
 618
 619         pp = ip_vs_proto_get(cih->protocol);
 620         if (!pp)
 621                 return NF_ACCEPT;
 622
 623         /* Is the embedded protocol header present? */
 624         if (unlikely(cih->frag_off & htons(IP_OFFSET) &&
 625                      pp->dont_defrag))
 626                 return NF_ACCEPT;
 627
 628         IP_VS_DBG_PKT(11, pp, skb, offset, "Checking outgoing ICMP for");
 629
 630         offset += cih->ihl * 4;
 631
 632         /* The embedded headers contain source and dest in reverse order */
 633         cp = pp->conn_out_get(skb, pp, cih, offset, 1);
 634         if (!cp)
 635                 return NF_ACCEPT;
 636
 637         verdict = NF_DROP;
 638
 639         if (IP_VS_FWD_METHOD(cp) != 0) {
 640                 IP_VS_ERR("shouldn't reach here, because the box is on the "
 641                           "half connection in the tun/dr module.\n");
 642         }
 643
 644         /* Ensure the checksum is correct */
 645         if (!skb_csum_unnecessary(skb) && ip_vs_checksum_complete(skb, ihl)) {
 646                 /* Failed checksum! */
 647                 IP_VS_DBG(1, "Forward ICMP: failed checksum from %d.%d.%d.%d!\n",
 648                           NIPQUAD(iph->saddr));
 649                 goto out;
 650         }
 651
 652         if (IPPROTO_TCP == cih->protocol || IPPROTO_UDP == cih->protocol)
 653                 offset += 2 * sizeof(__u16);
 654         if (!skb_make_writable(skb, offset))
 655                 goto out;
 656
 657         ip_vs_nat_icmp(skb, pp, cp, 1);
 658
 659         /* do the statistics and put it back */
 660         ip_vs_out_stats(cp, skb);
 661
 662         skb->ipvs_property = 1;
 663         verdict = NF_ACCEPT;
 664
 665   out:
 666         __ip_vs_conn_put(cp);
 667
 668         return verdict;
 669 }
 670
 671 static inline int is_tcp_reset(const struct sk_buff *skb)
 672 {
 673         struct tcphdr _tcph, *th;
 674
 675         th = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_tcph), &_tcph);
 676         if (th == NULL)
 677                 return 0;
 678         return th->rst;
 679 }
 680
 681 /*
 682  *      It is hooked at the NF_INET_FORWARD chain, used only for VS/NAT.
 683  *      Check if outgoing packet belongs to the established ip_vs_conn,
 684  *      rewrite addresses of the packet and send it on its way...
 685  */
 686 static unsigned int
 687 ip_vs_out(unsigned int hooknum, struct sk_buff *skb,
 688           const struct net_device *in, const struct net_device *out,
 689           int (*okfn)(struct sk_buff *))
 690 {
 691         struct iphdr    *iph;
 692         struct ip_vs_protocol *pp;
 693         struct ip_vs_conn *cp;
 694         int ihl;
 695
 696         EnterFunction(11);
 697
 698         if (skb->ipvs_property)
 699                 return NF_ACCEPT;
 700
 701         iph = ip_hdr(skb);
 702         if (unlikely(iph->protocol == IPPROTO_ICMP)) {
 703                 int related, verdict = ip_vs_out_icmp(skb, &related);
 704
 705                 if (related)
 706                         return verdict;
 707                 iph = ip_hdr(skb);
 708         }
 709
 710         pp = ip_vs_proto_get(iph->protocol);
 711         if (unlikely(!pp))
 712                 return NF_ACCEPT;
 713
 714         /* reassemble IP fragments */
 715         if (unlikely(iph->frag_off & htons(IP_MF|IP_OFFSET) &&
 716                      !pp->dont_defrag)) {
 717                 if (ip_vs_gather_frags(skb, IP_DEFRAG_VS_OUT))
 718                         return NF_STOLEN;
 719                 iph = ip_hdr(skb);
 720         }
 721
 722         ihl = iph->ihl << 2;
 723
 724         /*
 725          * Check if the packet belongs to an existing entry
 726          */
 727         cp = pp->conn_out_get(skb, pp, iph, ihl, 0);
 728
 729         if (unlikely(!cp)) {
 730                 if (sysctl_ip_vs_nat_icmp_send &&
 731                     (pp->protocol == IPPROTO_TCP ||
 732                      pp->protocol == IPPROTO_UDP)) {
 733                         __be16 _ports[2], *pptr;
 734
 735                         pptr = skb_header_pointer(skb, ihl,
 736                                                   sizeof(_ports), _ports);
 737                         if (pptr == NULL)
 738                                 return NF_ACCEPT;       /* Not for me */
 739                         if (ip_vs_lookup_real_service(iph->protocol,
 740                                                       iph->saddr, pptr[0])) {
 741                                 /*
 742                                  * Notify the real server: there is no
 743                                  * existing entry if it is not RST
 744                                  * packet or not TCP packet.
 745                                  */
 746                                 if (iph->protocol != IPPROTO_TCP
 747                                     || !is_tcp_reset(skb)) {
 748                                         icmp_send(skb,ICMP_DEST_UNREACH,
 749                                                   ICMP_PORT_UNREACH, 0);
 750                                         return NF_DROP;
 751                                 }
 752                         }
 753                 }
 754                 IP_VS_DBG_PKT(12, pp, skb, 0,
 755                               "packet continues traversal as normal");
 756                 return NF_ACCEPT;
 757         }
 758
 759         IP_VS_DBG_PKT(11, pp, skb, 0, "Outgoing packet");
 760
 761         if (!skb_make_writable(skb, ihl))
 762                 goto drop;
 763
 764         /* mangle the packet */
 765         if (pp->snat_handler && !pp->snat_handler(skb, pp, cp))
 766                 goto drop;
 767         ip_hdr(skb)->saddr = cp->vaddr;
 768         ip_send_check(ip_hdr(skb));
 769
 770         /* For policy routing, packets originating from this
 771          * machine itself may be routed differently to packets
 772          * passing through.  We want this packet to be routed as
 773          * if it came from this machine itself.  So re-compute
 774          * the routing information.
 775          */
 776         if (ip_route_me_harder(skb, RTN_LOCAL) != 0)
 777                 goto drop;
 778
 779         IP_VS_DBG_PKT(10, pp, skb, 0, "After SNAT");
 780
 781         ip_vs_out_stats(cp, skb);
 782         ip_vs_set_state(cp, IP_VS_DIR_OUTPUT, skb, pp);
 783         ip_vs_conn_put(cp);
 784
 785         skb->ipvs_property = 1;
 786
 787         LeaveFunction(11);
 788         return NF_ACCEPT;
 789
 790   drop:
 791         ip_vs_conn_put(cp);
 792         kfree_skb(skb);
 793         return NF_STOLEN;
 794 }
 795
 796
 797 /*
 798  *      Handle ICMP messages in the outside-to-inside direction (incoming).
 799  *      Find any that might be relevant, check against existing connections,
 800  *      forward to the right destination host if relevant.
 801  *      Currently handles error types - unreachable, quench, ttl exceeded.
 802  */
 803 static int
 804 ip_vs_in_icmp(struct sk_buff *skb, int *related, unsigned int hooknum)
 805 {
 806         struct iphdr *iph;
 807         struct icmphdr  _icmph, *ic;
 808         struct iphdr    _ciph, *cih;    /* The ip header contained within the ICMP */
 809         struct ip_vs_conn *cp;
 810         struct ip_vs_protocol *pp;
 811         unsigned int offset, ihl, verdict;
 812
 813         *related = 1;
 814
 815         /* reassemble IP fragments */
 816         if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
 817                 if (ip_vs_gather_frags(skb, hooknum == NF_INET_LOCAL_IN ?
 818                                             IP_DEFRAG_VS_IN : IP_DEFRAG_VS_FWD))
 819                         return NF_STOLEN;
 820         }
 821
 822         iph = ip_hdr(skb);
 823         offset = ihl = iph->ihl * 4;
 824         ic = skb_header_pointer(skb, offset, sizeof(_icmph), &_icmph);
 825         if (ic == NULL)
 826                 return NF_DROP;
 827
 828         IP_VS_DBG(12, "Incoming ICMP (%d,%d) %u.%u.%u.%u->%u.%u.%u.%u\n",
 829                   ic->type, ntohs(icmp_id(ic)),
 830                   NIPQUAD(iph->saddr), NIPQUAD(iph->daddr));
 831
 832         /*
 833          * Work through seeing if this is for us.
 834          * These checks are supposed to be in an order that means easy
 835          * things are checked first to speed up processing.... however
 836          * this means that some packets will manage to get a long way
 837          * down this stack and then be rejected, but that's life.
 838          */
 839         if ((ic->type != ICMP_DEST_UNREACH) &&
 840             (ic->type != ICMP_SOURCE_QUENCH) &&
 841             (ic->type != ICMP_TIME_EXCEEDED)) {
 842                 *related = 0;
 843                 return NF_ACCEPT;
 844         }
 845
 846         /* Now find the contained IP header */
 847         offset += sizeof(_icmph);
 848         cih = skb_header_pointer(skb, offset, sizeof(_ciph), &_ciph);
 849         if (cih == NULL)
 850                 return NF_ACCEPT; /* The packet looks wrong, ignore */
 851
 852         pp = ip_vs_proto_get(cih->protocol);
 853         if (!pp)
 854                 return NF_ACCEPT;
 855
 856         /* Is the embedded protocol header present? */
 857         if (unlikely(cih->frag_off & htons(IP_OFFSET) &&
 858                      pp->dont_defrag))
 859                 return NF_ACCEPT;
 860
 861         IP_VS_DBG_PKT(11, pp, skb, offset, "Checking incoming ICMP for");
 862
 863         offset += cih->ihl * 4;
 864
 865         /* The embedded headers contain source and dest in reverse order */
 866         cp = pp->conn_in_get(skb, pp, cih, offset, 1);
 867         if (!cp)
 868                 return NF_ACCEPT;
 869
 870         verdict = NF_DROP;
 871
 872         /* Ensure the checksum is correct */
 873         if (!skb_csum_unnecessary(skb) && ip_vs_checksum_complete(skb, ihl)) {
 874                 /* Failed checksum! */
 875                 IP_VS_DBG(1, "Incoming ICMP: failed checksum from %d.%d.%d.%d!\n",
 876                           NIPQUAD(iph->saddr));
 877                 goto out;
 878         }
 879
 880         /* do the statistics and put it back */
 881         ip_vs_in_stats(cp, skb);
 882         if (IPPROTO_TCP == cih->protocol || IPPROTO_UDP == cih->protocol)
 883                 offset += 2 * sizeof(__u16);
 884         verdict = ip_vs_icmp_xmit(skb, cp, pp, offset);
 885         /* do not touch skb anymore */
 886
 887   out:
 888         __ip_vs_conn_put(cp);
 889
 890         return verdict;
 891 }
 892
 893 /*
 894  *      Check if it's for virtual services, look it up,
 895  *      and send it on its way...
 896  */
 897 static unsigned int
 898 ip_vs_in(unsigned int hooknum, struct sk_buff *skb,
 899          const struct net_device *in, const struct net_device *out,
 900          int (*okfn)(struct sk_buff *))
 901 {
 902         struct iphdr    *iph;
 903         struct ip_vs_protocol *pp;
 904         struct ip_vs_conn *cp;
 905         int ret, restart;
 906         int ihl;
 907
 908         /*
 909          *      Big tappo: only PACKET_HOST (neither loopback nor mcasts)
 910          *      ... don't know why 1st test DOES NOT include 2nd (?)
 911          */
 912         if (unlikely(skb->pkt_type != PACKET_HOST
 913                      || skb->dev->flags & IFF_LOOPBACK || skb->sk)) {
 914                 IP_VS_DBG(12, "packet type=%d proto=%d daddr=%d.%d.%d.%d ignored\n",
 915                           skb->pkt_type,
 916                           ip_hdr(skb)->protocol,
 917                           NIPQUAD(ip_hdr(skb)->daddr));
 918                 return NF_ACCEPT;
 919         }
 920
 921         iph = ip_hdr(skb);
 922         if (unlikely(iph->protocol == IPPROTO_ICMP)) {
 923                 int related, verdict = ip_vs_in_icmp(skb, &related, hooknum);
 924
 925                 if (related)
 926                         return verdict;
 927                 iph = ip_hdr(skb);
 928         }
 929
 930         /* Protocol supported? */
 931         pp = ip_vs_proto_get(iph->protocol);
 932         if (unlikely(!pp))
 933                 return NF_ACCEPT;
 934
 935         ihl = iph->ihl << 2;
 936
 937         /*
 938          * Check if the packet belongs to an existing connection entry
 939          */
 940         cp = pp->conn_in_get(skb, pp, iph, ihl, 0);
 941
 942         if (unlikely(!cp)) {
 943                 int v;
 944
 945                 if (!pp->conn_schedule(skb, pp, &v, &cp))
 946                         return v;
 947         }
 948
 949         if (unlikely(!cp)) {
 950                 /* sorry, all this trouble for a no-hit :) */
 951                 IP_VS_DBG_PKT(12, pp, skb, 0,
 952                               "packet continues traversal as normal");
 953                 return NF_ACCEPT;
 954         }
 955
 956         IP_VS_DBG_PKT(11, pp, skb, 0, "Incoming packet");
 957
 958         /* Check the server status */
 959         if (cp->dest && !(cp->dest->flags & IP_VS_DEST_F_AVAILABLE)) {
 960                 /* the destination server is not available */
 961
 962                 if (sysctl_ip_vs_expire_nodest_conn) {
 963                         /* try to expire the connection immediately */
 964                         ip_vs_conn_expire_now(cp);
 965                 }
 966                 /* don't restart its timer, and silently
 967                    drop the packet. */
 968                 __ip_vs_conn_put(cp);
 969                 return NF_DROP;
 970         }
 971
 972         ip_vs_in_stats(cp, skb);
 973         restart = ip_vs_set_state(cp, IP_VS_DIR_INPUT, skb, pp);
 974         if (cp->packet_xmit)
 975                 ret = cp->packet_xmit(skb, cp, pp);
 976                 /* do not touch skb anymore */
 977         else {
 978                 IP_VS_DBG_RL("warning: packet_xmit is null");
 979                 ret = NF_ACCEPT;
 980         }
 981
 982         /* Increase its packet counter and check if it is needed
 983          * to be synchronized
 984          *
 985          * Sync connection if it is about to close to
 986          * encorage the standby servers to update the connections timeout
 987          */
 988         atomic_inc(&cp->in_pkts);
 989         if ((ip_vs_sync_state & IP_VS_STATE_MASTER) &&
 990             (((cp->protocol != IPPROTO_TCP ||
 991                cp->state == IP_VS_TCP_S_ESTABLISHED) &&
 992               (atomic_read(&cp->in_pkts) % sysctl_ip_vs_sync_threshold[1]
 993                == sysctl_ip_vs_sync_threshold[0])) ||
 994              ((cp->protocol == IPPROTO_TCP) && (cp->old_state != cp->state) &&
 995               ((cp->state == IP_VS_TCP_S_FIN_WAIT) ||
 996                (cp->state == IP_VS_TCP_S_CLOSE)))))
 997                 ip_vs_sync_conn(cp);
 998         cp->old_state = cp->state;
 999
1000         ip_vs_conn_put(cp);
1001         return ret;
1002 }
1003
1004
1005 /*
1006  *      It is hooked at the NF_INET_FORWARD chain, in order to catch ICMP
1007  *      related packets destined for 0.0.0.0/0.
1008  *      When fwmark-based virtual service is used, such as transparent
1009  *      cache cluster, TCP packets can be marked and routed to ip_vs_in,
1010  *      but ICMP destined for 0.0.0.0/0 cannot not be easily marked and
1011  *      sent to ip_vs_in_icmp. So, catch them at the NF_INET_FORWARD chain
1012  *      and send them to ip_vs_in_icmp.
1013  */
1014 static unsigned int
1015 ip_vs_forward_icmp(unsigned int hooknum, struct sk_buff *skb,
1016                    const struct net_device *in, const struct net_device *out,
1017                    int (*okfn)(struct sk_buff *))
1018 {
1019         int r;
1020
1021         if (ip_hdr(skb)->protocol != IPPROTO_ICMP)
1022                 return NF_ACCEPT;
1023
1024         return ip_vs_in_icmp(skb, &r, hooknum);
1025 }
1026
1027
1028 static struct nf_hook_ops ip_vs_ops[]  = {
1029         /* After packet filtering, forward packet through VS/DR, VS/TUN,
1030          * or VS/NAT(change destination), so that filtering rules can be
1031          * applied to IPVS. */
1032         {
1033                 .hook           = ip_vs_in,
1034                 .owner          = THIS_MODULE,
1035                 .pf             = PF_INET,
1036                 .hooknum        = NF_INET_LOCAL_IN,
1037                 .priority       = 100,
1038         },
1039         /* After packet filtering, change source only for VS/NAT */
1040         {
1041                 .hook           = ip_vs_out,
1042                 .owner          = THIS_MODULE,
1043                 .pf             = PF_INET,
1044                 .hooknum        = NF_INET_FORWARD,
1045                 .priority       = 100,
1046         },
1047         /* After packet filtering (but before ip_vs_out_icmp), catch icmp
1048          * destined for 0.0.0.0/0, which is for incoming IPVS connections */
1049         {
1050                 .hook           = ip_vs_forward_icmp,
1051                 .owner          = THIS_MODULE,
1052                 .pf             = PF_INET,
1053                 .hooknum        = NF_INET_FORWARD,
1054                 .priority       = 99,
1055         },
1056         /* Before the netfilter connection tracking, exit from POST_ROUTING */
1057         {
1058                 .hook           = ip_vs_post_routing,
1059                 .owner          = THIS_MODULE,
1060                 .pf             = PF_INET,
1061                 .hooknum        = NF_INET_POST_ROUTING,
1062                 .priority       = NF_IP_PRI_NAT_SRC-1,
1063         },
1064 };
1065
1066
1067 /*
1068  *      Initialize IP Virtual Server
1069  */
1070 static int __init ip_vs_init(void)
1071 {
1072         int ret;
1073
1074         ret = ip_vs_control_init();
1075         if (ret < 0) {
1076                 IP_VS_ERR("can't setup control.\n");
1077                 goto cleanup_nothing;
1078         }
1079
1080         ip_vs_protocol_init();
1081
1082         ret = ip_vs_app_init();
1083         if (ret < 0) {
1084                 IP_VS_ERR("can't setup application helper.\n");
1085                 goto cleanup_protocol;
1086         }
1087
1088         ret = ip_vs_conn_init();
1089         if (ret < 0) {
1090                 IP_VS_ERR("can't setup connection table.\n");
1091                 goto cleanup_app;
1092         }
1093
1094         ret = nf_register_hooks(ip_vs_ops, ARRAY_SIZE(ip_vs_ops));
1095         if (ret < 0) {
1096                 IP_VS_ERR("can't register hooks.\n");
1097                 goto cleanup_conn;
1098         }
1099
1100         IP_VS_INFO("ipvs loaded.\n");
1101         return ret;
1102
1103   cleanup_conn:
1104         ip_vs_conn_cleanup();
1105   cleanup_app:
1106         ip_vs_app_cleanup();
1107   cleanup_protocol:
1108         ip_vs_protocol_cleanup();
1109         ip_vs_control_cleanup();
1110   cleanup_nothing:
1111         return ret;
1112 }
1113
1114 static void __exit ip_vs_cleanup(void)
1115 {
1116         nf_unregister_hooks(ip_vs_ops, ARRAY_SIZE(ip_vs_ops));
1117         ip_vs_conn_cleanup();
1118         ip_vs_app_cleanup();
1119         ip_vs_protocol_cleanup();
1120         ip_vs_control_cleanup();
1121         IP_VS_INFO("ipvs unloaded.\n");
1122 }
1123
1124 module_init(ip_vs_init);
1125 module_exit(ip_vs_cleanup);
1126 MODULE_LICENSE("GPL");