net/ipv4/ipvs/ip_vs_proto_udp.c

   1 /*
   2  * ip_vs_proto_udp.c:   UDP load balancing support for IPVS
   3  *
   4  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
   5  *              Julian Anastasov <ja@ssi.bg>
   6  *
   7  *              This program is free software; you can redistribute it and/or
   8  *              modify it under the terms of the GNU General Public License
   9  *              as published by the Free Software Foundation; either version
  10  *              2 of the License, or (at your option) any later version.
  11  *
  12  * Changes:
  13  *
  14  */
  15
  16 #include <linux/in.h>
  17 #include <linux/ip.h>
  18 #include <linux/kernel.h>
  19 #include <linux/netfilter.h>
  20 #include <linux/netfilter_ipv4.h>
  21 #include <linux/udp.h>
  22
  23 #include <net/ip_vs.h>
  24 #include <net/ip.h>
  25
  26 static struct ip_vs_conn *
  27 udp_conn_in_get(int af, const struct sk_buff *skb, struct ip_vs_protocol *pp,
  28                 const struct ip_vs_iphdr *iph, unsigned int proto_off,
  29                 int inverse)
  30 {
  31         struct ip_vs_conn *cp;
  32         __be16 _ports[2], *pptr;
  33
  34         pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
  35         if (pptr == NULL)
  36                 return NULL;
  37
  38         if (likely(!inverse)) {
  39                 cp = ip_vs_conn_in_get(af, iph->protocol,
  40                                        &iph->saddr, pptr[0],
  41                                        &iph->daddr, pptr[1]);
  42         } else {
  43                 cp = ip_vs_conn_in_get(af, iph->protocol,
  44                                        &iph->daddr, pptr[1],
  45                                        &iph->saddr, pptr[0]);
  46         }
  47
  48         return cp;
  49 }
  50
  51
  52 static struct ip_vs_conn *
  53 udp_conn_out_get(int af, const struct sk_buff *skb, struct ip_vs_protocol *pp,
  54                  const struct ip_vs_iphdr *iph, unsigned int proto_off,
  55                  int inverse)
  56 {
  57         struct ip_vs_conn *cp;
  58         __be16 _ports[2], *pptr;
  59
  60         pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
  61         if (pptr == NULL)
  62                 return NULL;
  63
  64         if (likely(!inverse)) {
  65                 cp = ip_vs_conn_out_get(af, iph->protocol,
  66                                         &iph->saddr, pptr[0],
  67                                         &iph->daddr, pptr[1]);
  68         } else {
  69                 cp = ip_vs_conn_out_get(af, iph->protocol,
  70                                         &iph->daddr, pptr[1],
  71                                         &iph->saddr, pptr[0]);
  72         }
  73
  74         return cp;
  75 }
  76
  77
  78 static int
  79 udp_conn_schedule(int af, struct sk_buff *skb, struct ip_vs_protocol *pp,
  80                   int *verdict, struct ip_vs_conn **cpp)
  81 {
  82         struct ip_vs_service *svc;
  83         struct udphdr _udph, *uh;
  84         struct ip_vs_iphdr iph;
  85
  86         ip_vs_fill_iphdr(af, skb_network_header(skb), &iph);
  87
  88         uh = skb_header_pointer(skb, iph.len, sizeof(_udph), &_udph);
  89         if (uh == NULL) {
  90                 *verdict = NF_DROP;
  91                 return 0;
  92         }
  93
  94         svc = ip_vs_service_get(af, skb->mark, iph.protocol,
  95                                 &iph.daddr, uh->dest);
  96         if (svc) {
  97                 if (ip_vs_todrop()) {
  98                         /*
  99                          * It seems that we are very loaded.
 100                          * We have to drop this packet :(
 101                          */
 102                         ip_vs_service_put(svc);
 103                         *verdict = NF_DROP;
 104                         return 0;
 105                 }
 106
 107                 /*
 108                  * Let the virtual server select a real server for the
 109                  * incoming connection, and create a connection entry.
 110                  */
 111                 *cpp = ip_vs_schedule(svc, skb);
 112                 if (!*cpp) {
 113                         *verdict = ip_vs_leave(svc, skb, pp);
 114                         return 0;
 115                 }
 116                 ip_vs_service_put(svc);
 117         }
 118         return 1;
 119 }
 120
 121
 122 static inline void
 123 udp_fast_csum_update(int af, struct udphdr *uhdr,
 124                      const union nf_inet_addr *oldip,
 125                      const union nf_inet_addr *newip,
 126                      __be16 oldport, __be16 newport)
 127 {
 128 #ifdef CONFIG_IP_VS_IPV6
 129         if (af == AF_INET6)
 130                 uhdr->check =
 131                         csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
 132                                          ip_vs_check_diff2(oldport, newport,
 133                                                 ~csum_unfold(uhdr->check))));
 134         else
 135 #endif
 136                 uhdr->check =
 137                         csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
 138                                          ip_vs_check_diff2(oldport, newport,
 139                                                 ~csum_unfold(uhdr->check))));
 140         if (!uhdr->check)
 141                 uhdr->check = CSUM_MANGLED_0;
 142 }
 143
 144 static inline void
 145 udp_partial_csum_update(int af, struct udphdr *uhdr,
 146                      const union nf_inet_addr *oldip,
 147                      const union nf_inet_addr *newip,
 148                      __be16 oldlen, __be16 newlen)
 149 {
 150 #ifdef CONFIG_IP_VS_IPV6
 151         if (af == AF_INET6)
 152                 uhdr->check =
 153                         csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
 154                                          ip_vs_check_diff2(oldlen, newlen,
 155                                                 ~csum_unfold(uhdr->check))));
 156         else
 157 #endif
 158         uhdr->check =
 159                 csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
 160                                 ip_vs_check_diff2(oldlen, newlen,
 161                                                 ~csum_unfold(uhdr->check))));
 162 }
 163
 164
 165 static int
 166 udp_snat_handler(struct sk_buff *skb,
 167                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
 168 {
 169         struct udphdr *udph;
 170         unsigned int udphoff;
 171         int oldlen;
 172
 173 #ifdef CONFIG_IP_VS_IPV6
 174         if (cp->af == AF_INET6)
 175                 udphoff = sizeof(struct ipv6hdr);
 176         else
 177 #endif
 178                 udphoff = ip_hdrlen(skb);
 179         oldlen = skb->len - udphoff;
 180
 181         /* csum_check requires unshared skb */
 182         if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
 183                 return 0;
 184
 185         if (unlikely(cp->app != NULL)) {
 186                 /* Some checks before mangling */
 187                 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
 188                         return 0;
 189
 190                 /*
 191                  *      Call application helper if needed
 192                  */
 193                 if (!ip_vs_app_pkt_out(cp, skb))
 194                         return 0;
 195         }
 196
 197         udph = (void *)skb_network_header(skb) + udphoff;
 198         udph->source = cp->vport;
 199
 200         /*
 201          *      Adjust UDP checksums
 202          */
 203         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 204                 udp_partial_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
 205                                         htonl(oldlen),
 206                                         htonl(skb->len - udphoff));
 207         } else if (!cp->app && (udph->check != 0)) {
 208                 /* Only port and addr are changed, do fast csum update */
 209                 udp_fast_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
 210                                      cp->dport, cp->vport);
 211                 if (skb->ip_summed == CHECKSUM_COMPLETE)
 212                         skb->ip_summed = CHECKSUM_NONE;
 213         } else {
 214                 /* full checksum calculation */
 215                 udph->check = 0;
 216                 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
 217 #ifdef CONFIG_IP_VS_IPV6
 218                 if (cp->af == AF_INET6)
 219                         udph->check = csum_ipv6_magic(&cp->vaddr.in6,
 220                                                       &cp->caddr.in6,
 221                                                       skb->len - udphoff,
 222                                                       cp->protocol, skb->csum);
 223                 else
 224 #endif
 225                         udph->check = csum_tcpudp_magic(cp->vaddr.ip,
 226                                                         cp->caddr.ip,
 227                                                         skb->len - udphoff,
 228                                                         cp->protocol,
 229                                                         skb->csum);
 230                 if (udph->check == 0)
 231                         udph->check = CSUM_MANGLED_0;
 232                 IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
 233                           pp->name, udph->check,
 234                           (char*)&(udph->check) - (char*)udph);
 235         }
 236         return 1;
 237 }
 238
 239
 240 static int
 241 udp_dnat_handler(struct sk_buff *skb,
 242                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
 243 {
 244         struct udphdr *udph;
 245         unsigned int udphoff;
 246         int oldlen;
 247
 248 #ifdef CONFIG_IP_VS_IPV6
 249         if (cp->af == AF_INET6)
 250                 udphoff = sizeof(struct ipv6hdr);
 251         else
 252 #endif
 253                 udphoff = ip_hdrlen(skb);
 254         oldlen = skb->len - udphoff;
 255
 256         /* csum_check requires unshared skb */
 257         if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
 258                 return 0;
 259
 260         if (unlikely(cp->app != NULL)) {
 261                 /* Some checks before mangling */
 262                 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
 263                         return 0;
 264
 265                 /*
 266                  *      Attempt ip_vs_app call.
 267                  *      It will fix ip_vs_conn
 268                  */
 269                 if (!ip_vs_app_pkt_in(cp, skb))
 270                         return 0;
 271         }
 272
 273         udph = (void *)skb_network_header(skb) + udphoff;
 274         udph->dest = cp->dport;
 275
 276         /*
 277          *      Adjust UDP checksums
 278          */
 279         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 280                 udp_partial_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
 281                                         htonl(oldlen),
 282                                         htonl(skb->len - udphoff));
 283         } else if (!cp->app && (udph->check != 0)) {
 284                 /* Only port and addr are changed, do fast csum update */
 285                 udp_fast_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
 286                                      cp->vport, cp->dport);
 287                 if (skb->ip_summed == CHECKSUM_COMPLETE)
 288                         skb->ip_summed = CHECKSUM_NONE;
 289         } else {
 290                 /* full checksum calculation */
 291                 udph->check = 0;
 292                 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
 293 #ifdef CONFIG_IP_VS_IPV6
 294                 if (cp->af == AF_INET6)
 295                         udph->check = csum_ipv6_magic(&cp->caddr.in6,
 296                                                       &cp->daddr.in6,
 297                                                       skb->len - udphoff,
 298                                                       cp->protocol, skb->csum);
 299                 else
 300 #endif
 301                         udph->check = csum_tcpudp_magic(cp->caddr.ip,
 302                                                         cp->daddr.ip,
 303                                                         skb->len - udphoff,
 304                                                         cp->protocol,
 305                                                         skb->csum);
 306                 if (udph->check == 0)
 307                         udph->check = CSUM_MANGLED_0;
 308                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 309         }
 310         return 1;
 311 }
 312
 313
 314 static int
 315 udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
 316 {
 317         struct udphdr _udph, *uh;
 318         unsigned int udphoff;
 319
 320 #ifdef CONFIG_IP_VS_IPV6
 321         if (af == AF_INET6)
 322                 udphoff = sizeof(struct ipv6hdr);
 323         else
 324 #endif
 325                 udphoff = ip_hdrlen(skb);
 326
 327         uh = skb_header_pointer(skb, udphoff, sizeof(_udph), &_udph);
 328         if (uh == NULL)
 329                 return 0;
 330
 331         if (uh->check != 0) {
 332                 switch (skb->ip_summed) {
 333                 case CHECKSUM_NONE:
 334                         skb->csum = skb_checksum(skb, udphoff,
 335                                                  skb->len - udphoff, 0);
 336                 case CHECKSUM_COMPLETE:
 337 #ifdef CONFIG_IP_VS_IPV6
 338                         if (af == AF_INET6) {
 339                                 if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
 340                                                     &ipv6_hdr(skb)->daddr,
 341                                                     skb->len - udphoff,
 342                                                     ipv6_hdr(skb)->nexthdr,
 343                                                     skb->csum)) {
 344                                         IP_VS_DBG_RL_PKT(0, pp, skb, 0,
 345                                                          "Failed checksum for");
 346                                         return 0;
 347                                 }
 348                         } else
 349 #endif
 350                                 if (csum_tcpudp_magic(ip_hdr(skb)->saddr,
 351                                                       ip_hdr(skb)->daddr,
 352                                                       skb->len - udphoff,
 353                                                       ip_hdr(skb)->protocol,
 354                                                       skb->csum)) {
 355                                         IP_VS_DBG_RL_PKT(0, pp, skb, 0,
 356                                                          "Failed checksum for");
 357                                         return 0;
 358                                 }
 359                         break;
 360                 default:
 361                         /* No need to checksum. */
 362                         break;
 363                 }
 364         }
 365         return 1;
 366 }
 367
 368
 369 /*
 370  *      Note: the caller guarantees that only one of register_app,
 371  *      unregister_app or app_conn_bind is called each time.
 372  */
 373
 374 #define UDP_APP_TAB_BITS        4
 375 #define UDP_APP_TAB_SIZE        (1 << UDP_APP_TAB_BITS)
 376 #define UDP_APP_TAB_MASK        (UDP_APP_TAB_SIZE - 1)
 377
 378 static struct list_head udp_apps[UDP_APP_TAB_SIZE];
 379 static DEFINE_SPINLOCK(udp_app_lock);
 380
 381 static inline __u16 udp_app_hashkey(__be16 port)
 382 {
 383         return (((__force u16)port >> UDP_APP_TAB_BITS) ^ (__force u16)port)
 384                 & UDP_APP_TAB_MASK;
 385 }
 386
 387
 388 static int udp_register_app(struct ip_vs_app *inc)
 389 {
 390         struct ip_vs_app *i;
 391         __u16 hash;
 392         __be16 port = inc->port;
 393         int ret = 0;
 394
 395         hash = udp_app_hashkey(port);
 396
 397
 398         spin_lock_bh(&udp_app_lock);
 399         list_for_each_entry(i, &udp_apps[hash], p_list) {
 400                 if (i->port == port) {
 401                         ret = -EEXIST;
 402                         goto out;
 403                 }
 404         }
 405         list_add(&inc->p_list, &udp_apps[hash]);
 406         atomic_inc(&ip_vs_protocol_udp.appcnt);
 407
 408   out:
 409         spin_unlock_bh(&udp_app_lock);
 410         return ret;
 411 }
 412
 413
 414 static void
 415 udp_unregister_app(struct ip_vs_app *inc)
 416 {
 417         spin_lock_bh(&udp_app_lock);
 418         atomic_dec(&ip_vs_protocol_udp.appcnt);
 419         list_del(&inc->p_list);
 420         spin_unlock_bh(&udp_app_lock);
 421 }
 422
 423
 424 static int udp_app_conn_bind(struct ip_vs_conn *cp)
 425 {
 426         int hash;
 427         struct ip_vs_app *inc;
 428         int result = 0;
 429
 430         /* Default binding: bind app only for NAT */
 431         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
 432                 return 0;
 433
 434         /* Lookup application incarnations and bind the right one */
 435         hash = udp_app_hashkey(cp->vport);
 436
 437         spin_lock(&udp_app_lock);
 438         list_for_each_entry(inc, &udp_apps[hash], p_list) {
 439                 if (inc->port == cp->vport) {
 440                         if (unlikely(!ip_vs_app_inc_get(inc)))
 441                                 break;
 442                         spin_unlock(&udp_app_lock);
 443
 444                         IP_VS_DBG_BUF(9, "%s: Binding conn %s:%u->"
 445                                       "%s:%u to app %s on port %u\n",
 446                                       __func__,
 447                                       IP_VS_DBG_ADDR(cp->af, &cp->caddr),
 448                                       ntohs(cp->cport),
 449                                       IP_VS_DBG_ADDR(cp->af, &cp->vaddr),
 450                                       ntohs(cp->vport),
 451                                       inc->name, ntohs(inc->port));
 452
 453                         cp->app = inc;
 454                         if (inc->init_conn)
 455                                 result = inc->init_conn(inc, cp);
 456                         goto out;
 457                 }
 458         }
 459         spin_unlock(&udp_app_lock);
 460
 461   out:
 462         return result;
 463 }
 464
 465
 466 static int udp_timeouts[IP_VS_UDP_S_LAST+1] = {
 467         [IP_VS_UDP_S_NORMAL]            =       5*60*HZ,
 468         [IP_VS_UDP_S_LAST]              =       2*HZ,
 469 };
 470
 471 static char * udp_state_name_table[IP_VS_UDP_S_LAST+1] = {
 472         [IP_VS_UDP_S_NORMAL]            =       "UDP",
 473         [IP_VS_UDP_S_LAST]              =       "BUG!",
 474 };
 475
 476
 477 static int
 478 udp_set_state_timeout(struct ip_vs_protocol *pp, char *sname, int to)
 479 {
 480         return ip_vs_set_state_timeout(pp->timeout_table, IP_VS_UDP_S_LAST,
 481                                        udp_state_name_table, sname, to);
 482 }
 483
 484 static const char * udp_state_name(int state)
 485 {
 486         if (state >= IP_VS_UDP_S_LAST)
 487                 return "ERR!";
 488         return udp_state_name_table[state] ? udp_state_name_table[state] : "?";
 489 }
 490
 491 static int
 492 udp_state_transition(struct ip_vs_conn *cp, int direction,
 493                      const struct sk_buff *skb,
 494                      struct ip_vs_protocol *pp)
 495 {
 496         cp->timeout = pp->timeout_table[IP_VS_UDP_S_NORMAL];
 497         return 1;
 498 }
 499
 500 static void udp_init(struct ip_vs_protocol *pp)
 501 {
 502         IP_VS_INIT_HASH_TABLE(udp_apps);
 503         pp->timeout_table = udp_timeouts;
 504 }
 505
 506 static void udp_exit(struct ip_vs_protocol *pp)
 507 {
 508 }
 509
 510
 511 struct ip_vs_protocol ip_vs_protocol_udp = {
 512         .name =                 "UDP",
 513         .protocol =             IPPROTO_UDP,
 514         .num_states =           IP_VS_UDP_S_LAST,
 515         .dont_defrag =          0,
 516         .init =                 udp_init,
 517         .exit =                 udp_exit,
 518         .conn_schedule =        udp_conn_schedule,
 519         .conn_in_get =          udp_conn_in_get,
 520         .conn_out_get =         udp_conn_out_get,
 521         .snat_handler =         udp_snat_handler,
 522         .dnat_handler =         udp_dnat_handler,
 523         .csum_check =           udp_csum_check,
 524         .state_transition =     udp_state_transition,
 525         .state_name =           udp_state_name,
 526         .register_app =         udp_register_app,
 527         .unregister_app =       udp_unregister_app,
 528         .app_conn_bind =        udp_app_conn_bind,
 529         .debug_packet =         ip_vs_tcpudp_debug_packet,
 530         .timeout_change =       NULL,
 531         .set_state_timeout =    udp_set_state_timeout,
 532 };