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  *
  26  */
  27
  28 #include <linux/module.h>
  29 #include <linux/kernel.h>
  30 #include <linux/ip.h>
  31 #include <linux/tcp.h>
  32 #include <linux/icmp.h>
  33
  34 #include <net/ip.h>
  35 #include <net/tcp.h>
  36 #include <net/udp.h>
  37 #include <net/icmp.h>                   /* for icmp_send */
  38 #include <net/route.h>
  39
  40 #include <linux/netfilter.h>
  41 #include <linux/netfilter_ipv4.h>
  42
  43 #include <net/ip_vs.h>
  44
  45
  46 EXPORT_SYMBOL(register_ip_vs_scheduler);
  47 EXPORT_SYMBOL(unregister_ip_vs_scheduler);
  48 EXPORT_SYMBOL(ip_vs_skb_replace);
  49 EXPORT_SYMBOL(ip_vs_proto_name);
  50 EXPORT_SYMBOL(ip_vs_conn_new);
  51 EXPORT_SYMBOL(ip_vs_conn_in_get);
  52 EXPORT_SYMBOL(ip_vs_conn_out_get);
  53 #ifdef CONFIG_IP_VS_PROTO_TCP
  54 EXPORT_SYMBOL(ip_vs_tcp_conn_listen);
  55 #endif
  56 EXPORT_SYMBOL(ip_vs_conn_put);
  57 #ifdef CONFIG_IP_VS_DEBUG
  58 EXPORT_SYMBOL(ip_vs_get_debug_level);
  59 #endif
  60 EXPORT_SYMBOL(check_for_ip_vs_out);
  61 EXPORT_SYMBOL(ip_vs_make_skb_writable);
  62
  63
  64 /* ID used in ICMP lookups */
  65 #define icmp_id(icmph)          (((icmph)->un).echo.id)
  66
  67 const char *ip_vs_proto_name(unsigned proto)
  68 {
  69         static char buf[20];
  70
  71         switch (proto) {
  72         case IPPROTO_IP:
  73                 return "IP";
  74         case IPPROTO_UDP:
  75                 return "UDP";
  76         case IPPROTO_TCP:
  77                 return "TCP";
  78         case IPPROTO_ICMP:
  79                 return "ICMP";
  80         default:
  81                 sprintf(buf, "IP_%d", proto);
  82                 return buf;
  83         }
  84 }
  85
  86 void ip_vs_init_hash_table(struct list_head *table, int rows)
  87 {
  88         while (--rows >= 0)
  89                 INIT_LIST_HEAD(&table[rows]);
  90 }
  91
  92 static inline void
  93 ip_vs_in_stats(struct ip_vs_conn *cp, struct sk_buff *skb)
  94 {
  95         struct ip_vs_dest *dest = cp->dest;
  96         if (dest && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
  97                 spin_lock(&dest->stats.lock);
  98                 dest->stats.inpkts++;
  99                 dest->stats.inbytes += skb->len;
 100                 spin_unlock(&dest->stats.lock);
 101
 102                 spin_lock(&dest->svc->stats.lock);
 103                 dest->svc->stats.inpkts++;
 104                 dest->svc->stats.inbytes += skb->len;
 105                 spin_unlock(&dest->svc->stats.lock);
 106
 107                 spin_lock(&ip_vs_stats.lock);
 108                 ip_vs_stats.inpkts++;
 109                 ip_vs_stats.inbytes += skb->len;
 110                 spin_unlock(&ip_vs_stats.lock);
 111         }
 112 }
 113
 114
 115 static inline void
 116 ip_vs_out_stats(struct ip_vs_conn *cp, struct sk_buff *skb)
 117 {
 118         struct ip_vs_dest *dest = cp->dest;
 119         if (dest && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
 120                 spin_lock(&dest->stats.lock);
 121                 dest->stats.outpkts++;
 122                 dest->stats.outbytes += skb->len;
 123                 spin_unlock(&dest->stats.lock);
 124
 125                 spin_lock(&dest->svc->stats.lock);
 126                 dest->svc->stats.outpkts++;
 127                 dest->svc->stats.outbytes += skb->len;
 128                 spin_unlock(&dest->svc->stats.lock);
 129
 130                 spin_lock(&ip_vs_stats.lock);
 131                 ip_vs_stats.outpkts++;
 132                 ip_vs_stats.outbytes += skb->len;
 133                 spin_unlock(&ip_vs_stats.lock);
 134         }
 135 }
 136
 137
 138 static inline void
 139 ip_vs_conn_stats(struct ip_vs_conn *cp, struct ip_vs_service *svc)
 140 {
 141         spin_lock(&cp->dest->stats.lock);
 142         cp->dest->stats.conns++;
 143         spin_unlock(&cp->dest->stats.lock);
 144
 145         spin_lock(&svc->stats.lock);
 146         svc->stats.conns++;
 147         spin_unlock(&svc->stats.lock);
 148
 149         spin_lock(&ip_vs_stats.lock);
 150         ip_vs_stats.conns++;
 151         spin_unlock(&ip_vs_stats.lock);
 152 }
 153
 154
 155 static inline int
 156 ip_vs_set_state(struct ip_vs_conn *cp, int direction,
 157                 const struct sk_buff *skb,
 158                 struct ip_vs_protocol *pp)
 159 {
 160         if (unlikely(!pp->state_transition))
 161                 return 0;
 162         return pp->state_transition(cp, direction, skb, pp);
 163 }
 164
 165
 166 int ip_vs_make_skb_writable(struct sk_buff **pskb, int writable_len)
 167 {
 168         struct sk_buff *skb = *pskb;
 169
 170         /* skb is already used, better copy skb and its payload */
 171         if (unlikely(skb_shared(skb) || skb->sk))
 172                 goto copy_skb;
 173
 174         /* skb data is already used, copy it */
 175         if (unlikely(skb_cloned(skb)))
 176                 goto copy_data;
 177
 178         return pskb_may_pull(skb, writable_len);
 179
 180   copy_data:
 181         if (unlikely(writable_len > skb->len))
 182                 return 0;
 183         return !pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
 184
 185   copy_skb:
 186         if (unlikely(writable_len > skb->len))
 187                 return 0;
 188         skb = skb_copy(skb, GFP_ATOMIC);
 189         if (!skb)
 190                 return 0;
 191         BUG_ON(skb_is_nonlinear(skb));
 192
 193         /* Rest of kernel will get very unhappy if we pass it a
 194            suddenly-orphaned skbuff */
 195         if ((*pskb)->sk)
 196                 skb_set_owner_w(skb, (*pskb)->sk);
 197         kfree_skb(*pskb);
 198         *pskb = skb;
 199         return 1;
 200 }
 201
 202 /*
 203  *  IPVS persistent scheduling function
 204  *  It creates a connection entry according to its template if exists,
 205  *  or selects a server and creates a connection entry plus a template.
 206  *  Locking: we are svc user (svc->refcnt), so we hold all dests too
 207  *  Protocols supported: TCP, UDP
 208  */
 209 static struct ip_vs_conn *
 210 ip_vs_sched_persist(struct ip_vs_service *svc,
 211                     const struct sk_buff *skb,
 212                     __u16 ports[2])
 213 {
 214         struct ip_vs_conn *cp = NULL;
 215         struct iphdr *iph = skb->nh.iph;
 216         struct ip_vs_dest *dest;
 217         struct ip_vs_conn *ct;
 218         __u16  dport;    /* destination port to forward */
 219         __u32  snet;     /* source network of the client, after masking */
 220
 221         /* Mask saddr with the netmask to adjust template granularity */
 222         snet = iph->saddr & svc->netmask;
 223
 224         IP_VS_DBG(6, "p-schedule: src %u.%u.%u.%u:%u dest %u.%u.%u.%u:%u "
 225                   "mnet %u.%u.%u.%u\n",
 226                   NIPQUAD(iph->saddr), ntohs(ports[0]),
 227                   NIPQUAD(iph->daddr), ntohs(ports[1]),
 228                   NIPQUAD(snet));
 229
 230         /*
 231          * As far as we know, FTP is a very complicated network protocol, and
 232          * it uses control connection and data connections. For active FTP,
 233          * FTP server initialize data connection to the client, its source port
 234          * is often 20. For passive FTP, FTP server tells the clients the port
 235          * that it passively listens to,  and the client issues the data
 236          * connection. In the tunneling or direct routing mode, the load
 237          * balancer is on the client-to-server half of connection, the port
 238          * number is unknown to the load balancer. So, a conn template like
 239          * <caddr, 0, vaddr, 0, daddr, 0> is created for persistent FTP
 240          * service, and a template like <caddr, 0, vaddr, vport, daddr, dport>
 241          * is created for other persistent services.
 242          */
 243         if (ports[1] == svc->port) {
 244                 /* Check if a template already exists */
 245                 if (svc->port != FTPPORT)
 246                         ct = ip_vs_conn_in_get(iph->protocol, snet, 0,
 247                                                iph->daddr, ports[1]);
 248                 else
 249                         ct = ip_vs_conn_in_get(iph->protocol, snet, 0,
 250                                                iph->daddr, 0);
 251
 252                 if (!ct || !ip_vs_check_template(ct)) {
 253                         /*
 254                          * No template found or the dest of the connection
 255                          * template is not available.
 256                          */
 257                         dest = svc->scheduler->schedule(svc, skb);
 258                         if (dest == NULL) {
 259                                 IP_VS_DBG(1, "p-schedule: no dest found.\n");
 260                                 return NULL;
 261                         }
 262
 263                         /*
 264                          * Create a template like <protocol,caddr,0,
 265                          * vaddr,vport,daddr,dport> for non-ftp service,
 266                          * and <protocol,caddr,0,vaddr,0,daddr,0>
 267                          * for ftp service.
 268                          */
 269                         if (svc->port != FTPPORT)
 270                                 ct = ip_vs_conn_new(iph->protocol,
 271                                                     snet, 0,
 272                                                     iph->daddr,
 273                                                     ports[1],
 274                                                     dest->addr, dest->port,
 275                                                     0,
 276                                                     dest);
 277                         else
 278                                 ct = ip_vs_conn_new(iph->protocol,
 279                                                     snet, 0,
 280                                                     iph->daddr, 0,
 281                                                     dest->addr, 0,
 282                                                     0,
 283                                                     dest);
 284                         if (ct == NULL)
 285                                 return NULL;
 286
 287                         ct->timeout = svc->timeout;
 288                 } else {
 289                         /* set destination with the found template */
 290                         dest = ct->dest;
 291                 }
 292                 dport = dest->port;
 293         } else {
 294                 /*
 295                  * Note: persistent fwmark-based services and persistent
 296                  * port zero service are handled here.
 297                  * fwmark template: <IPPROTO_IP,caddr,0,fwmark,0,daddr,0>
 298                  * port zero template: <protocol,caddr,0,vaddr,0,daddr,0>
 299                  */
 300                 if (svc->fwmark)
 301                         ct = ip_vs_conn_in_get(IPPROTO_IP, snet, 0,
 302                                                htonl(svc->fwmark), 0);
 303                 else
 304                         ct = ip_vs_conn_in_get(iph->protocol, snet, 0,
 305                                                iph->daddr, 0);
 306
 307                 if (!ct || !ip_vs_check_template(ct)) {
 308                         /*
 309                          * If it is not persistent port zero, return NULL,
 310                          * otherwise create a connection template.
 311                          */
 312                         if (svc->port)
 313                                 return NULL;
 314
 315                         dest = svc->scheduler->schedule(svc, skb);
 316                         if (dest == NULL) {
 317                                 IP_VS_DBG(1, "p-schedule: no dest found.\n");
 318                                 return NULL;
 319                         }
 320
 321                         /*
 322                          * Create a template according to the service
 323                          */
 324                         if (svc->fwmark)
 325                                 ct = ip_vs_conn_new(IPPROTO_IP,
 326                                                     snet, 0,
 327                                                     htonl(svc->fwmark), 0,
 328                                                     dest->addr, 0,
 329                                                     0,
 330                                                     dest);
 331                         else
 332                                 ct = ip_vs_conn_new(iph->protocol,
 333                                                     snet, 0,
 334                                                     iph->daddr, 0,
 335                                                     dest->addr, 0,
 336                                                     0,
 337                                                     dest);
 338                         if (ct == NULL)
 339                                 return NULL;
 340
 341                         ct->timeout = svc->timeout;
 342                 } else {
 343                         /* set destination with the found template */
 344                         dest = ct->dest;
 345                 }
 346                 dport = ports[1];
 347         }
 348
 349         /*
 350          *    Create a new connection according to the template
 351          */
 352         cp = ip_vs_conn_new(iph->protocol,
 353                             iph->saddr, ports[0],
 354                             iph->daddr, ports[1],
 355                             dest->addr, dport,
 356                             0,
 357                             dest);
 358         if (cp == NULL) {
 359                 ip_vs_conn_put(ct);
 360                 return NULL;
 361         }
 362
 363         /*
 364          *    Add its control
 365          */
 366         ip_vs_control_add(cp, ct);
 367         ip_vs_conn_put(ct);
 368
 369         ip_vs_conn_stats(cp, svc);
 370         return cp;
 371 }
 372
 373
 374 /*
 375  *  IPVS main scheduling function
 376  *  It selects a server according to the virtual service, and
 377  *  creates a connection entry.
 378  *  Protocols supported: TCP, UDP
 379  */
 380 struct ip_vs_conn *
 381 ip_vs_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
 382 {
 383         struct ip_vs_conn *cp = NULL;
 384         struct iphdr *iph = skb->nh.iph;
 385         struct ip_vs_dest *dest;
 386         __u16 _ports[2], *pptr;
 387
 388         pptr = skb_header_pointer(skb, iph->ihl*4,
 389                                   sizeof(_ports), _ports);
 390         if (pptr == NULL)
 391                 return NULL;
 392
 393         /*
 394          *    Persistent service
 395          */
 396         if (svc->flags & IP_VS_SVC_F_PERSISTENT)
 397                 return ip_vs_sched_persist(svc, skb, pptr);
 398
 399         /*
 400          *    Non-persistent service
 401          */
 402         if (!svc->fwmark && pptr[1] != svc->port) {
 403                 if (!svc->port)
 404                         IP_VS_ERR("Schedule: port zero only supported "
 405                                   "in persistent services, "
 406                                   "check your ipvs configuration\n");
 407                 return NULL;
 408         }
 409
 410         dest = svc->scheduler->schedule(svc, skb);
 411         if (dest == NULL) {
 412                 IP_VS_DBG(1, "Schedule: no dest found.\n");
 413                 return NULL;
 414         }
 415
 416         /*
 417          *    Create a connection entry.
 418          */
 419         cp = ip_vs_conn_new(iph->protocol,
 420                             iph->saddr, pptr[0],
 421                             iph->daddr, pptr[1],
 422                             dest->addr, dest->port?dest->port:pptr[1],
 423                             0,
 424                             dest);
 425         if (cp == NULL)
 426                 return NULL;
 427
 428         IP_VS_DBG(6, "Schedule fwd:%c c:%u.%u.%u.%u:%u v:%u.%u.%u.%u:%u "
 429                   "d:%u.%u.%u.%u:%u flg:%X cnt:%d\n",
 430                   ip_vs_fwd_tag(cp),
 431                   NIPQUAD(cp->caddr), ntohs(cp->cport),
 432                   NIPQUAD(cp->vaddr), ntohs(cp->vport),
 433                   NIPQUAD(cp->daddr), ntohs(cp->dport),
 434                   cp->flags, atomic_read(&cp->refcnt));
 435
 436         ip_vs_conn_stats(cp, svc);
 437         return cp;
 438 }
 439
 440
 441 /*
 442  *  Pass or drop the packet.
 443  *  Called by ip_vs_in, when the virtual service is available but
 444  *  no destination is available for a new connection.
 445  */
 446 int ip_vs_leave(struct ip_vs_service *svc, struct sk_buff *skb,
 447                 struct ip_vs_protocol *pp)
 448 {
 449         __u16 _ports[2], *pptr;
 450         struct iphdr *iph = skb->nh.iph;
 451
 452         pptr = skb_header_pointer(skb, iph->ihl*4,
 453                                   sizeof(_ports), _ports);
 454         if (pptr == NULL) {
 455                 ip_vs_service_put(svc);
 456                 return NF_DROP;
 457         }
 458
 459         /* if it is fwmark-based service, the cache_bypass sysctl is up
 460            and the destination is RTN_UNICAST (and not local), then create
 461            a cache_bypass connection entry */
 462         if (sysctl_ip_vs_cache_bypass && svc->fwmark
 463             && (inet_addr_type(iph->daddr) == RTN_UNICAST)) {
 464                 int ret, cs;
 465                 struct ip_vs_conn *cp;
 466
 467                 ip_vs_service_put(svc);
 468
 469                 /* create a new connection entry */
 470                 IP_VS_DBG(6, "ip_vs_leave: create a cache_bypass entry\n");
 471                 cp = ip_vs_conn_new(iph->protocol,
 472                                     iph->saddr, pptr[0],
 473                                     iph->daddr, pptr[1],
 474                                     0, 0,
 475                                     IP_VS_CONN_F_BYPASS,
 476                                     NULL);
 477                 if (cp == NULL)
 478                         return NF_DROP;
 479
 480                 /* statistics */
 481                 ip_vs_in_stats(cp, skb);
 482
 483                 /* set state */
 484                 cs = ip_vs_set_state(cp, IP_VS_DIR_INPUT, skb, pp);
 485
 486                 /* transmit the first SYN packet */
 487                 ret = cp->packet_xmit(skb, cp, pp);
 488                 /* do not touch skb anymore */
 489
 490                 atomic_inc(&cp->in_pkts);
 491                 ip_vs_conn_put(cp);
 492                 return ret;
 493         }
 494
 495         /*
 496          * When the virtual ftp service is presented, packets destined
 497          * for other services on the VIP may get here (except services
 498          * listed in the ipvs table), pass the packets, because it is
 499          * not ipvs job to decide to drop the packets.
 500          */
 501         if ((svc->port == FTPPORT) && (pptr[1] != FTPPORT)) {
 502                 ip_vs_service_put(svc);
 503                 return NF_ACCEPT;
 504         }
 505
 506         ip_vs_service_put(svc);
 507
 508         /*
 509          * Notify the client that the destination is unreachable, and
 510          * release the socket buffer.
 511          * Since it is in IP layer, the TCP socket is not actually
 512          * created, the TCP RST packet cannot be sent, instead that
 513          * ICMP_PORT_UNREACH is sent here no matter it is TCP/UDP. --WZ
 514          */
 515         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 516         return NF_DROP;
 517 }
 518
 519
 520 /*
 521  *      It is hooked before NF_IP_PRI_NAT_SRC at the NF_IP_POST_ROUTING
 522  *      chain, and is used for VS/NAT.
 523  *      It detects packets for VS/NAT connections and sends the packets
 524  *      immediately. This can avoid that iptable_nat mangles the packets
 525  *      for VS/NAT.
 526  */
 527 static unsigned int ip_vs_post_routing(unsigned int hooknum,
 528                                        struct sk_buff **pskb,
 529                                        const struct net_device *in,
 530                                        const struct net_device *out,
 531                                        int (*okfn)(struct sk_buff *))
 532 {
 533         if (!((*pskb)->nfcache & NFC_IPVS_PROPERTY))
 534                 return NF_ACCEPT;
 535
 536         /* The packet was sent from IPVS, exit this chain */
 537         (*okfn)(*pskb);
 538
 539         return NF_STOLEN;
 540 }
 541
 542 u16 ip_vs_checksum_complete(struct sk_buff *skb, int offset)
 543 {
 544         return (u16) csum_fold(skb_checksum(skb, offset, skb->len - offset, 0));
 545 }
 546
 547 static inline struct sk_buff *
 548 ip_vs_gather_frags(struct sk_buff *skb)
 549 {
 550         skb = ip_defrag(skb);
 551         if (skb)
 552                 ip_send_check(skb->nh.iph);
 553         return skb;
 554 }
 555
 556 /*
 557  * Packet has been made sufficiently writable in caller
 558  * - inout: 1=in->out, 0=out->in
 559  */
 560 void ip_vs_nat_icmp(struct sk_buff *skb, struct ip_vs_protocol *pp,
 561                     struct ip_vs_conn *cp, int inout)
 562 {
 563         struct iphdr *iph        = skb->nh.iph;
 564         unsigned int icmp_offset = iph->ihl*4;
 565         struct icmphdr *icmph    = (struct icmphdr *)(skb->nh.raw + icmp_offset);
 566         struct iphdr *ciph       = (struct iphdr *)(icmph + 1);
 567
 568         if (inout) {
 569                 iph->saddr = cp->vaddr;
 570                 ip_send_check(iph);
 571                 ciph->daddr = cp->vaddr;
 572                 ip_send_check(ciph);
 573         } else {
 574                 iph->daddr = cp->daddr;
 575                 ip_send_check(iph);
 576                 ciph->saddr = cp->daddr;
 577                 ip_send_check(ciph);
 578         }
 579
 580         /* the TCP/UDP port */
 581         if (IPPROTO_TCP == ciph->protocol || IPPROTO_UDP == ciph->protocol) {
 582                 __u16 *ports = (void *)ciph + ciph->ihl*4;
 583
 584                 if (inout)
 585                         ports[1] = cp->vport;
 586                 else
 587                         ports[0] = cp->dport;
 588         }
 589
 590         /* And finally the ICMP checksum */
 591         icmph->checksum = 0;
 592         icmph->checksum = ip_vs_checksum_complete(skb, icmp_offset);
 593         skb->ip_summed = CHECKSUM_UNNECESSARY;
 594
 595         if (inout)
 596                 IP_VS_DBG_PKT(11, pp, skb, (void *)ciph - (void *)iph,
 597                         "Forwarding altered outgoing ICMP");
 598         else
 599                 IP_VS_DBG_PKT(11, pp, skb, (void *)ciph - (void *)iph,
 600                         "Forwarding altered incoming ICMP");
 601 }
 602
 603 /*
 604  *      Handle ICMP messages in the inside-to-outside direction (outgoing).
 605  *      Find any that might be relevant, check against existing connections,
 606  *      forward to the right destination host if relevant.
 607  *      Currently handles error types - unreachable, quench, ttl exceeded.
 608  *      (Only used in VS/NAT)
 609  */
 610 static int ip_vs_out_icmp(struct sk_buff **pskb, int *related)
 611 {
 612         struct sk_buff *skb = *pskb;
 613         struct iphdr *iph;
 614         struct icmphdr  _icmph, *ic;
 615         struct iphdr    _ciph, *cih;    /* The ip header contained within the ICMP */
 616         struct ip_vs_conn *cp;
 617         struct ip_vs_protocol *pp;
 618         unsigned int offset, ihl, verdict;
 619
 620         *related = 1;
 621
 622         /* reassemble IP fragments */
 623         if (skb->nh.iph->frag_off & __constant_htons(IP_MF|IP_OFFSET)) {
 624                 skb = ip_vs_gather_frags(skb);
 625                 if (!skb)
 626                         return NF_STOLEN;
 627                 *pskb = skb;
 628         }
 629
 630         iph = skb->nh.iph;
 631         offset = ihl = iph->ihl * 4;
 632         ic = skb_header_pointer(skb, offset, sizeof(_icmph), &_icmph);
 633         if (ic == NULL)
 634                 return NF_DROP;
 635
 636         IP_VS_DBG(12, "Outgoing ICMP (%d,%d) %u.%u.%u.%u->%u.%u.%u.%u\n",
 637                   ic->type, ntohs(icmp_id(ic)),
 638                   NIPQUAD(iph->saddr), NIPQUAD(iph->daddr));
 639
 640         /*
 641          * Work through seeing if this is for us.
 642          * These checks are supposed to be in an order that means easy
 643          * things are checked first to speed up processing.... however
 644          * this means that some packets will manage to get a long way
 645          * down this stack and then be rejected, but that's life.
 646          */
 647         if ((ic->type != ICMP_DEST_UNREACH) &&
 648             (ic->type != ICMP_SOURCE_QUENCH) &&
 649             (ic->type != ICMP_TIME_EXCEEDED)) {
 650                 *related = 0;
 651                 return NF_ACCEPT;
 652         }
 653
 654         /* Now find the contained IP header */
 655         offset += sizeof(_icmph);
 656         cih = skb_header_pointer(skb, offset, sizeof(_ciph), &_ciph);
 657         if (cih == NULL)
 658                 return NF_ACCEPT; /* The packet looks wrong, ignore */
 659
 660         pp = ip_vs_proto_get(cih->protocol);
 661         if (!pp)
 662                 return NF_ACCEPT;
 663
 664         /* Is the embedded protocol header present? */
 665         if (unlikely(cih->frag_off & __constant_htons(IP_OFFSET) &&
 666                      pp->dont_defrag))
 667                 return NF_ACCEPT;
 668
 669         IP_VS_DBG_PKT(11, pp, skb, offset, "Checking outgoing ICMP for");
 670
 671         offset += cih->ihl * 4;
 672
 673         /* The embedded headers contain source and dest in reverse order */
 674         cp = pp->conn_out_get(skb, pp, cih, offset, 1);
 675         if (!cp)
 676                 return NF_ACCEPT;
 677
 678         verdict = NF_DROP;
 679
 680         if (IP_VS_FWD_METHOD(cp) != 0) {
 681                 IP_VS_ERR("shouldn't reach here, because the box is on the"
 682                           "half connection in the tun/dr module.\n");
 683         }
 684
 685         /* Ensure the checksum is correct */
 686         if (skb->ip_summed != CHECKSUM_UNNECESSARY &&
 687             ip_vs_checksum_complete(skb, ihl)) {
 688                 /* Failed checksum! */
 689                 IP_VS_DBG(1, "Forward ICMP: failed checksum from %d.%d.%d.%d!\n",
 690                           NIPQUAD(iph->saddr));
 691                 goto out;
 692         }
 693
 694         if (IPPROTO_TCP == cih->protocol || IPPROTO_UDP == cih->protocol)
 695                 offset += 2 * sizeof(__u16);
 696         if (!ip_vs_make_skb_writable(pskb, offset))
 697                 goto out;
 698         skb = *pskb;
 699
 700         ip_vs_nat_icmp(skb, pp, cp, 1);
 701
 702         /* do the statistics and put it back */
 703         ip_vs_out_stats(cp, skb);
 704
 705         skb->nfcache |= NFC_IPVS_PROPERTY;
 706         verdict = NF_ACCEPT;
 707
 708   out:
 709         __ip_vs_conn_put(cp);
 710
 711         return verdict;
 712 }
 713
 714 static inline int is_tcp_reset(const struct sk_buff *skb)
 715 {
 716         struct tcphdr _tcph, *th;
 717
 718         th = skb_header_pointer(skb, skb->nh.iph->ihl * 4,
 719                                 sizeof(_tcph), &_tcph);
 720         if (th == NULL)
 721                 return 0;
 722         return th->rst;
 723 }
 724
 725 /*
 726  *      It is hooked at the NF_IP_FORWARD chain, used only for VS/NAT.
 727  *      Check if outgoing packet belongs to the established ip_vs_conn,
 728  *      rewrite addresses of the packet and send it on its way...
 729  */
 730 static unsigned int
 731 ip_vs_out(unsigned int hooknum, struct sk_buff **pskb,
 732           const struct net_device *in, const struct net_device *out,
 733           int (*okfn)(struct sk_buff *))
 734 {
 735         struct sk_buff  *skb = *pskb;
 736         struct iphdr    *iph;
 737         struct ip_vs_protocol *pp;
 738         struct ip_vs_conn *cp;
 739         int ihl;
 740
 741         EnterFunction(11);
 742
 743         if (skb->nfcache & NFC_IPVS_PROPERTY)
 744                 return NF_ACCEPT;
 745
 746         iph = skb->nh.iph;
 747         if (unlikely(iph->protocol == IPPROTO_ICMP)) {
 748                 int related, verdict = ip_vs_out_icmp(pskb, &related);
 749
 750                 if (related)
 751                         return verdict;
 752                 skb = *pskb;
 753                 iph = skb->nh.iph;
 754         }
 755
 756         pp = ip_vs_proto_get(iph->protocol);
 757         if (unlikely(!pp))
 758                 return NF_ACCEPT;
 759
 760         /* reassemble IP fragments */
 761         if (unlikely(iph->frag_off & __constant_htons(IP_MF|IP_OFFSET) &&
 762                      !pp->dont_defrag)) {
 763                 skb = ip_vs_gather_frags(skb);
 764                 if (!skb)
 765                         return NF_STOLEN;
 766                 iph = skb->nh.iph;
 767                 *pskb = skb;
 768         }
 769
 770         ihl = iph->ihl << 2;
 771
 772         /*
 773          * Check if the packet belongs to an existing entry
 774          */
 775         cp = pp->conn_out_get(skb, pp, iph, ihl, 0);
 776
 777         if (unlikely(!cp)) {
 778                 if (sysctl_ip_vs_nat_icmp_send &&
 779                     (pp->protocol == IPPROTO_TCP ||
 780                      pp->protocol == IPPROTO_UDP)) {
 781                         __u16 _ports[2], *pptr;
 782
 783                         pptr = skb_header_pointer(skb, ihl,
 784                                                   sizeof(_ports), _ports);
 785                         if (pptr == NULL)
 786                                 return NF_ACCEPT;       /* Not for me */
 787                         if (ip_vs_lookup_real_service(iph->protocol,
 788                                                       iph->saddr, pptr[0])) {
 789                                 /*
 790                                  * Notify the real server: there is no
 791                                  * existing entry if it is not RST
 792                                  * packet or not TCP packet.
 793                                  */
 794                                 if (iph->protocol != IPPROTO_TCP
 795                                     || !is_tcp_reset(skb)) {
 796                                         icmp_send(skb,ICMP_DEST_UNREACH,
 797                                                   ICMP_PORT_UNREACH, 0);
 798                                         return NF_DROP;
 799                                 }
 800                         }
 801                 }
 802                 IP_VS_DBG_PKT(12, pp, skb, 0,
 803                               "packet continues traversal as normal");
 804                 return NF_ACCEPT;
 805         }
 806
 807         IP_VS_DBG_PKT(11, pp, skb, 0, "Outgoing packet");
 808
 809         if (!ip_vs_make_skb_writable(pskb, ihl))
 810                 goto drop;
 811
 812         /* mangle the packet */
 813         if (pp->snat_handler && !pp->snat_handler(pskb, pp, cp))
 814                 goto drop;
 815         skb = *pskb;
 816         skb->nh.iph->saddr = cp->vaddr;
 817         ip_send_check(skb->nh.iph);
 818
 819         IP_VS_DBG_PKT(10, pp, skb, 0, "After SNAT");
 820
 821         ip_vs_out_stats(cp, skb);
 822         ip_vs_set_state(cp, IP_VS_DIR_OUTPUT, skb, pp);
 823         ip_vs_conn_put(cp);
 824
 825         skb->nfcache |= NFC_IPVS_PROPERTY;
 826
 827         LeaveFunction(11);
 828         return NF_ACCEPT;
 829
 830   drop:
 831         ip_vs_conn_put(cp);
 832         kfree_skb(*pskb);
 833         return NF_STOLEN;
 834 }
 835
 836
 837 /*
 838  *      Check if the packet is for VS/NAT connections, then send it
 839  *      immediately.
 840  *      Called by ip_fw_compact to detect packets for VS/NAT before
 841  *      they are changed by ipchains masquerading code.
 842  */
 843 unsigned int
 844 check_for_ip_vs_out(struct sk_buff **pskb, int (*okfn)(struct sk_buff *))
 845 {
 846         unsigned int ret;
 847
 848         ret = ip_vs_out(NF_IP_FORWARD, pskb, NULL, NULL, NULL);
 849         if (ret != NF_ACCEPT) {
 850                 return ret;
 851         } else {
 852                 /* send the packet immediately if it is already mangled
 853                    by ip_vs_out */
 854                 if ((*pskb)->nfcache & NFC_IPVS_PROPERTY) {
 855                         (*okfn)(*pskb);
 856                         return NF_STOLEN;
 857                 }
 858         }
 859         return NF_ACCEPT;
 860 }
 861
 862 /*
 863  *      Handle ICMP messages in the outside-to-inside direction (incoming).
 864  *      Find any that might be relevant, check against existing connections,
 865  *      forward to the right destination host if relevant.
 866  *      Currently handles error types - unreachable, quench, ttl exceeded.
 867  */
 868 static int ip_vs_in_icmp(struct sk_buff **pskb, int *related)
 869 {
 870         struct sk_buff *skb = *pskb;
 871         struct iphdr *iph;
 872         struct icmphdr  _icmph, *ic;
 873         struct iphdr    _ciph, *cih;    /* The ip header contained within the ICMP */
 874         struct ip_vs_conn *cp;
 875         struct ip_vs_protocol *pp;
 876         unsigned int offset, ihl, verdict;
 877
 878         *related = 1;
 879
 880         /* reassemble IP fragments */
 881         if (skb->nh.iph->frag_off & __constant_htons(IP_MF|IP_OFFSET)) {
 882                 skb = ip_vs_gather_frags(skb);
 883                 if (!skb)
 884                         return NF_STOLEN;
 885                 *pskb = skb;
 886         }
 887
 888         iph = skb->nh.iph;
 889         offset = ihl = iph->ihl * 4;
 890         ic = skb_header_pointer(skb, offset, sizeof(_icmph), &_icmph);
 891         if (ic == NULL)
 892                 return NF_DROP;
 893
 894         IP_VS_DBG(12, "Incoming ICMP (%d,%d) %u.%u.%u.%u->%u.%u.%u.%u\n",
 895                   ic->type, ntohs(icmp_id(ic)),
 896                   NIPQUAD(iph->saddr), NIPQUAD(iph->daddr));
 897
 898         /*
 899          * Work through seeing if this is for us.
 900          * These checks are supposed to be in an order that means easy
 901          * things are checked first to speed up processing.... however
 902          * this means that some packets will manage to get a long way
 903          * down this stack and then be rejected, but that's life.
 904          */
 905         if ((ic->type != ICMP_DEST_UNREACH) &&
 906             (ic->type != ICMP_SOURCE_QUENCH) &&
 907             (ic->type != ICMP_TIME_EXCEEDED)) {
 908                 *related = 0;
 909                 return NF_ACCEPT;
 910         }
 911
 912         /* Now find the contained IP header */
 913         offset += sizeof(_icmph);
 914         cih = skb_header_pointer(skb, offset, sizeof(_ciph), &_ciph);
 915         if (cih == NULL)
 916                 return NF_ACCEPT; /* The packet looks wrong, ignore */
 917
 918         pp = ip_vs_proto_get(cih->protocol);
 919         if (!pp)
 920                 return NF_ACCEPT;
 921
 922         /* Is the embedded protocol header present? */
 923         if (unlikely(cih->frag_off & __constant_htons(IP_OFFSET) &&
 924                      pp->dont_defrag))
 925                 return NF_ACCEPT;
 926
 927         IP_VS_DBG_PKT(11, pp, skb, offset, "Checking incoming ICMP for");
 928
 929         offset += cih->ihl * 4;
 930
 931         /* The embedded headers contain source and dest in reverse order */
 932         cp = pp->conn_in_get(skb, pp, cih, offset, 1);
 933         if (!cp)
 934                 return NF_ACCEPT;
 935
 936         verdict = NF_DROP;
 937
 938         /* Ensure the checksum is correct */
 939         if (skb->ip_summed != CHECKSUM_UNNECESSARY &&
 940             ip_vs_checksum_complete(skb, ihl)) {
 941                 /* Failed checksum! */
 942                 IP_VS_DBG(1, "Incoming ICMP: failed checksum from %d.%d.%d.%d!\n",
 943                           NIPQUAD(iph->saddr));
 944                 goto out;
 945         }
 946
 947         /* do the statistics and put it back */
 948         ip_vs_in_stats(cp, skb);
 949         if (IPPROTO_TCP == cih->protocol || IPPROTO_UDP == cih->protocol)
 950                 offset += 2 * sizeof(__u16);
 951         verdict = ip_vs_icmp_xmit(skb, cp, pp, offset);
 952         /* do not touch skb anymore */
 953
 954   out:
 955         __ip_vs_conn_put(cp);
 956
 957         return verdict;
 958 }
 959
 960 /*
 961  *      Check if it's for virtual services, look it up,
 962  *      and send it on its way...
 963  */
 964 static unsigned int
 965 ip_vs_in(unsigned int hooknum, struct sk_buff **pskb,
 966          const struct net_device *in, const struct net_device *out,
 967          int (*okfn)(struct sk_buff *))
 968 {
 969         struct sk_buff  *skb = *pskb;
 970         struct iphdr    *iph;
 971         struct ip_vs_protocol *pp;
 972         struct ip_vs_conn *cp;
 973         int ret, restart;
 974         int ihl;
 975
 976         /*
 977          *      Big tappo: only PACKET_HOST (neither loopback nor mcasts)
 978          *      ... don't know why 1st test DOES NOT include 2nd (?)
 979          */
 980         if (unlikely(skb->pkt_type != PACKET_HOST
 981                      || skb->dev == &loopback_dev || skb->sk)) {
 982                 IP_VS_DBG(12, "packet type=%d proto=%d daddr=%d.%d.%d.%d ignored\n",
 983                           skb->pkt_type,
 984                           skb->nh.iph->protocol,
 985                           NIPQUAD(skb->nh.iph->daddr));
 986                 return NF_ACCEPT;
 987         }
 988
 989         iph = skb->nh.iph;
 990         if (unlikely(iph->protocol == IPPROTO_ICMP)) {
 991                 int related, verdict = ip_vs_in_icmp(pskb, &related);
 992
 993                 if (related)
 994                         return verdict;
 995                 skb = *pskb;
 996                 iph = skb->nh.iph;
 997         }
 998
 999         /* Protocol supported? */
1000         pp = ip_vs_proto_get(iph->protocol);
1001         if (unlikely(!pp))
1002                 return NF_ACCEPT;
1003
1004         ihl = iph->ihl << 2;
1005
1006         /*
1007          * Check if the packet belongs to an existing connection entry
1008          */
1009         cp = pp->conn_in_get(skb, pp, iph, ihl, 0);
1010
1011         if (unlikely(!cp)) {
1012                 int v;
1013
1014                 if (!pp->conn_schedule(skb, pp, &v, &cp))
1015                         return v;
1016         }
1017
1018         if (unlikely(!cp)) {
1019                 /* sorry, all this trouble for a no-hit :) */
1020                 IP_VS_DBG_PKT(12, pp, skb, 0,
1021                               "packet continues traversal as normal");
1022                 return NF_ACCEPT;
1023         }
1024
1025         IP_VS_DBG_PKT(11, pp, skb, 0, "Incoming packet");
1026
1027         /* Check the server status */
1028         if (cp->dest && !(cp->dest->flags & IP_VS_DEST_F_AVAILABLE)) {
1029                 /* the destination server is not availabe */
1030
1031                 if (sysctl_ip_vs_expire_nodest_conn) {
1032                         /* try to expire the connection immediately */
1033                         ip_vs_conn_expire_now(cp);
1034                 } else {
1035                         /* don't restart its timer, and silently
1036                            drop the packet. */
1037                         __ip_vs_conn_put(cp);
1038                 }
1039                 return NF_DROP;
1040         }
1041
1042         ip_vs_in_stats(cp, skb);
1043         restart = ip_vs_set_state(cp, IP_VS_DIR_INPUT, skb, pp);
1044         if (cp->packet_xmit)
1045                 ret = cp->packet_xmit(skb, cp, pp);
1046                 /* do not touch skb anymore */
1047         else {
1048                 IP_VS_DBG_RL("warning: packet_xmit is null");
1049                 ret = NF_ACCEPT;
1050         }
1051
1052         /* increase its packet counter and check if it is needed
1053            to be synchronized */
1054         atomic_inc(&cp->in_pkts);
1055         if ((ip_vs_sync_state & IP_VS_STATE_MASTER) &&
1056             (cp->protocol != IPPROTO_TCP ||
1057              cp->state == IP_VS_TCP_S_ESTABLISHED) &&
1058             (atomic_read(&cp->in_pkts) % sysctl_ip_vs_sync_threshold[1]
1059              == sysctl_ip_vs_sync_threshold[0]))
1060                 ip_vs_sync_conn(cp);
1061
1062         ip_vs_conn_put(cp);
1063         return ret;
1064 }
1065
1066
1067 /*
1068  *      It is hooked at the NF_IP_FORWARD chain, in order to catch ICMP
1069  *      related packets destined for 0.0.0.0/0.
1070  *      When fwmark-based virtual service is used, such as transparent
1071  *      cache cluster, TCP packets can be marked and routed to ip_vs_in,
1072  *      but ICMP destined for 0.0.0.0/0 cannot not be easily marked and
1073  *      sent to ip_vs_in_icmp. So, catch them at the NF_IP_FORWARD chain
1074  *      and send them to ip_vs_in_icmp.
1075  */
1076 static unsigned int
1077 ip_vs_forward_icmp(unsigned int hooknum, struct sk_buff **pskb,
1078                    const struct net_device *in, const struct net_device *out,
1079                    int (*okfn)(struct sk_buff *))
1080 {
1081         int r;
1082
1083         if ((*pskb)->nh.iph->protocol != IPPROTO_ICMP)
1084                 return NF_ACCEPT;
1085
1086         return ip_vs_in_icmp(pskb, &r);
1087 }
1088
1089
1090 /* After packet filtering, forward packet through VS/DR, VS/TUN,
1091    or VS/NAT(change destination), so that filtering rules can be
1092    applied to IPVS. */
1093 static struct nf_hook_ops ip_vs_in_ops = {
1094         .hook           = ip_vs_in,
1095         .owner          = THIS_MODULE,
1096         .pf             = PF_INET,
1097         .hooknum        = NF_IP_LOCAL_IN,
1098         .priority       = 100,
1099 };
1100
1101 /* After packet filtering, change source only for VS/NAT */
1102 static struct nf_hook_ops ip_vs_out_ops = {
1103         .hook           = ip_vs_out,
1104         .owner          = THIS_MODULE,
1105         .pf             = PF_INET,
1106         .hooknum        = NF_IP_FORWARD,
1107         .priority       = 100,
1108 };
1109
1110 /* After packet filtering (but before ip_vs_out_icmp), catch icmp
1111    destined for 0.0.0.0/0, which is for incoming IPVS connections */
1112 static struct nf_hook_ops ip_vs_forward_icmp_ops = {
1113         .hook           = ip_vs_forward_icmp,
1114         .owner          = THIS_MODULE,
1115         .pf             = PF_INET,
1116         .hooknum        = NF_IP_FORWARD,
1117         .priority       = 99,
1118 };
1119
1120 /* Before the netfilter connection tracking, exit from POST_ROUTING */
1121 static struct nf_hook_ops ip_vs_post_routing_ops = {
1122         .hook           = ip_vs_post_routing,
1123         .owner          = THIS_MODULE,
1124         .pf             = PF_INET,
1125         .hooknum        = NF_IP_POST_ROUTING,
1126         .priority       = NF_IP_PRI_NAT_SRC-1,
1127 };
1128
1129
1130 /*
1131  *      Initialize IP Virtual Server
1132  */
1133 static int __init ip_vs_init(void)
1134 {
1135         int ret;
1136
1137         ret = ip_vs_control_init();
1138         if (ret < 0) {
1139                 IP_VS_ERR("can't setup control.\n");
1140                 goto cleanup_nothing;
1141         }
1142
1143         ip_vs_protocol_init();
1144
1145         ret = ip_vs_app_init();
1146         if (ret < 0) {
1147                 IP_VS_ERR("can't setup application helper.\n");
1148                 goto cleanup_protocol;
1149         }
1150
1151         ret = ip_vs_conn_init();
1152         if (ret < 0) {
1153                 IP_VS_ERR("can't setup connection table.\n");
1154                 goto cleanup_app;
1155         }
1156
1157         ret = nf_register_hook(&ip_vs_in_ops);
1158         if (ret < 0) {
1159                 IP_VS_ERR("can't register in hook.\n");
1160                 goto cleanup_conn;
1161         }
1162
1163         ret = nf_register_hook(&ip_vs_out_ops);
1164         if (ret < 0) {
1165                 IP_VS_ERR("can't register out hook.\n");
1166                 goto cleanup_inops;
1167         }
1168         ret = nf_register_hook(&ip_vs_post_routing_ops);
1169         if (ret < 0) {
1170                 IP_VS_ERR("can't register post_routing hook.\n");
1171                 goto cleanup_outops;
1172         }
1173         ret = nf_register_hook(&ip_vs_forward_icmp_ops);
1174         if (ret < 0) {
1175                 IP_VS_ERR("can't register forward_icmp hook.\n");
1176                 goto cleanup_postroutingops;
1177         }
1178
1179         IP_VS_INFO("ipvs loaded.\n");
1180         return ret;
1181
1182   cleanup_postroutingops:
1183         nf_unregister_hook(&ip_vs_post_routing_ops);
1184   cleanup_outops:
1185         nf_unregister_hook(&ip_vs_out_ops);
1186   cleanup_inops:
1187         nf_unregister_hook(&ip_vs_in_ops);
1188   cleanup_conn:
1189         ip_vs_conn_cleanup();
1190   cleanup_app:
1191         ip_vs_app_cleanup();
1192   cleanup_protocol:
1193         ip_vs_protocol_cleanup();
1194         ip_vs_control_cleanup();
1195   cleanup_nothing:
1196         return ret;
1197 }
1198
1199 static void __exit ip_vs_cleanup(void)
1200 {
1201         nf_unregister_hook(&ip_vs_forward_icmp_ops);
1202         nf_unregister_hook(&ip_vs_post_routing_ops);
1203         nf_unregister_hook(&ip_vs_out_ops);
1204         nf_unregister_hook(&ip_vs_in_ops);
1205         ip_vs_conn_cleanup();
1206         ip_vs_app_cleanup();
1207         ip_vs_protocol_cleanup();
1208         ip_vs_control_cleanup();
1209         IP_VS_INFO("ipvs unloaded.\n");
1210 }
1211
1212 module_init(ip_vs_init);
1213 module_exit(ip_vs_cleanup);
1214 MODULE_LICENSE("GPL");