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   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 int
 145 udp_snat_handler(struct sk_buff *skb,
 146                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
 147 {
 148         struct udphdr *udph;
 149         unsigned int udphoff;
 150
 151 #ifdef CONFIG_IP_VS_IPV6
 152         if (cp->af == AF_INET6)
 153                 udphoff = sizeof(struct ipv6hdr);
 154         else
 155 #endif
 156                 udphoff = ip_hdrlen(skb);
 157
 158         /* csum_check requires unshared skb */
 159         if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
 160                 return 0;
 161
 162         if (unlikely(cp->app != NULL)) {
 163                 /* Some checks before mangling */
 164                 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
 165                         return 0;
 166
 167                 /*
 168                  *      Call application helper if needed
 169                  */
 170                 if (!ip_vs_app_pkt_out(cp, skb))
 171                         return 0;
 172         }
 173
 174         udph = (void *)skb_network_header(skb) + udphoff;
 175         udph->source = cp->vport;
 176
 177         /*
 178          *      Adjust UDP checksums
 179          */
 180         if (!cp->app && (udph->check != 0)) {
 181                 /* Only port and addr are changed, do fast csum update */
 182                 udp_fast_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
 183                                      cp->dport, cp->vport);
 184                 if (skb->ip_summed == CHECKSUM_COMPLETE)
 185                         skb->ip_summed = CHECKSUM_NONE;
 186         } else {
 187                 /* full checksum calculation */
 188                 udph->check = 0;
 189                 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
 190 #ifdef CONFIG_IP_VS_IPV6
 191                 if (cp->af == AF_INET6)
 192                         udph->check = csum_ipv6_magic(&cp->vaddr.in6,
 193                                                       &cp->caddr.in6,
 194                                                       skb->len - udphoff,
 195                                                       cp->protocol, skb->csum);
 196                 else
 197 #endif
 198                         udph->check = csum_tcpudp_magic(cp->vaddr.ip,
 199                                                         cp->caddr.ip,
 200                                                         skb->len - udphoff,
 201                                                         cp->protocol,
 202                                                         skb->csum);
 203                 if (udph->check == 0)
 204                         udph->check = CSUM_MANGLED_0;
 205                 IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
 206                           pp->name, udph->check,
 207                           (char*)&(udph->check) - (char*)udph);
 208         }
 209         return 1;
 210 }
 211
 212
 213 static int
 214 udp_dnat_handler(struct sk_buff *skb,
 215                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
 216 {
 217         struct udphdr *udph;
 218         unsigned int udphoff;
 219
 220 #ifdef CONFIG_IP_VS_IPV6
 221         if (cp->af == AF_INET6)
 222                 udphoff = sizeof(struct ipv6hdr);
 223         else
 224 #endif
 225                 udphoff = ip_hdrlen(skb);
 226
 227         /* csum_check requires unshared skb */
 228         if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
 229                 return 0;
 230
 231         if (unlikely(cp->app != NULL)) {
 232                 /* Some checks before mangling */
 233                 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
 234                         return 0;
 235
 236                 /*
 237                  *      Attempt ip_vs_app call.
 238                  *      It will fix ip_vs_conn
 239                  */
 240                 if (!ip_vs_app_pkt_in(cp, skb))
 241                         return 0;
 242         }
 243
 244         udph = (void *)skb_network_header(skb) + udphoff;
 245         udph->dest = cp->dport;
 246
 247         /*
 248          *      Adjust UDP checksums
 249          */
 250         if (!cp->app && (udph->check != 0)) {
 251                 /* Only port and addr are changed, do fast csum update */
 252                 udp_fast_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
 253                                      cp->vport, cp->dport);
 254                 if (skb->ip_summed == CHECKSUM_COMPLETE)
 255                         skb->ip_summed = CHECKSUM_NONE;
 256         } else {
 257                 /* full checksum calculation */
 258                 udph->check = 0;
 259                 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
 260 #ifdef CONFIG_IP_VS_IPV6
 261                 if (cp->af == AF_INET6)
 262                         udph->check = csum_ipv6_magic(&cp->caddr.in6,
 263                                                       &cp->daddr.in6,
 264                                                       skb->len - udphoff,
 265                                                       cp->protocol, skb->csum);
 266                 else
 267 #endif
 268                         udph->check = csum_tcpudp_magic(cp->caddr.ip,
 269                                                         cp->daddr.ip,
 270                                                         skb->len - udphoff,
 271                                                         cp->protocol,
 272                                                         skb->csum);
 273                 if (udph->check == 0)
 274                         udph->check = CSUM_MANGLED_0;
 275                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 276         }
 277         return 1;
 278 }
 279
 280
 281 static int
 282 udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
 283 {
 284         struct udphdr _udph, *uh;
 285         unsigned int udphoff;
 286
 287 #ifdef CONFIG_IP_VS_IPV6
 288         if (af == AF_INET6)
 289                 udphoff = sizeof(struct ipv6hdr);
 290         else
 291 #endif
 292                 udphoff = ip_hdrlen(skb);
 293
 294         uh = skb_header_pointer(skb, udphoff, sizeof(_udph), &_udph);
 295         if (uh == NULL)
 296                 return 0;
 297
 298         if (uh->check != 0) {
 299                 switch (skb->ip_summed) {
 300                 case CHECKSUM_NONE:
 301                         skb->csum = skb_checksum(skb, udphoff,
 302                                                  skb->len - udphoff, 0);
 303                 case CHECKSUM_COMPLETE:
 304 #ifdef CONFIG_IP_VS_IPV6
 305                         if (af == AF_INET6) {
 306                                 if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
 307                                                     &ipv6_hdr(skb)->daddr,
 308                                                     skb->len - udphoff,
 309                                                     ipv6_hdr(skb)->nexthdr,
 310                                                     skb->csum)) {
 311                                         IP_VS_DBG_RL_PKT(0, pp, skb, 0,
 312                                                          "Failed checksum for");
 313                                         return 0;
 314                                 }
 315                         } else
 316 #endif
 317                                 if (csum_tcpudp_magic(ip_hdr(skb)->saddr,
 318                                                       ip_hdr(skb)->daddr,
 319                                                       skb->len - udphoff,
 320                                                       ip_hdr(skb)->protocol,
 321                                                       skb->csum)) {
 322                                         IP_VS_DBG_RL_PKT(0, pp, skb, 0,
 323                                                          "Failed checksum for");
 324                                         return 0;
 325                                 }
 326                         break;
 327                 default:
 328                         /* No need to checksum. */
 329                         break;
 330                 }
 331         }
 332         return 1;
 333 }
 334
 335
 336 /*
 337  *      Note: the caller guarantees that only one of register_app,
 338  *      unregister_app or app_conn_bind is called each time.
 339  */
 340
 341 #define UDP_APP_TAB_BITS        4
 342 #define UDP_APP_TAB_SIZE        (1 << UDP_APP_TAB_BITS)
 343 #define UDP_APP_TAB_MASK        (UDP_APP_TAB_SIZE - 1)
 344
 345 static struct list_head udp_apps[UDP_APP_TAB_SIZE];
 346 static DEFINE_SPINLOCK(udp_app_lock);
 347
 348 static inline __u16 udp_app_hashkey(__be16 port)
 349 {
 350         return (((__force u16)port >> UDP_APP_TAB_BITS) ^ (__force u16)port)
 351                 & UDP_APP_TAB_MASK;
 352 }
 353
 354
 355 static int udp_register_app(struct ip_vs_app *inc)
 356 {
 357         struct ip_vs_app *i;
 358         __u16 hash;
 359         __be16 port = inc->port;
 360         int ret = 0;
 361
 362         hash = udp_app_hashkey(port);
 363
 364
 365         spin_lock_bh(&udp_app_lock);
 366         list_for_each_entry(i, &udp_apps[hash], p_list) {
 367                 if (i->port == port) {
 368                         ret = -EEXIST;
 369                         goto out;
 370                 }
 371         }
 372         list_add(&inc->p_list, &udp_apps[hash]);
 373         atomic_inc(&ip_vs_protocol_udp.appcnt);
 374
 375   out:
 376         spin_unlock_bh(&udp_app_lock);
 377         return ret;
 378 }
 379
 380
 381 static void
 382 udp_unregister_app(struct ip_vs_app *inc)
 383 {
 384         spin_lock_bh(&udp_app_lock);
 385         atomic_dec(&ip_vs_protocol_udp.appcnt);
 386         list_del(&inc->p_list);
 387         spin_unlock_bh(&udp_app_lock);
 388 }
 389
 390
 391 static int udp_app_conn_bind(struct ip_vs_conn *cp)
 392 {
 393         int hash;
 394         struct ip_vs_app *inc;
 395         int result = 0;
 396
 397         /* Default binding: bind app only for NAT */
 398         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
 399                 return 0;
 400
 401         /* Lookup application incarnations and bind the right one */
 402         hash = udp_app_hashkey(cp->vport);
 403
 404         spin_lock(&udp_app_lock);
 405         list_for_each_entry(inc, &udp_apps[hash], p_list) {
 406                 if (inc->port == cp->vport) {
 407                         if (unlikely(!ip_vs_app_inc_get(inc)))
 408                                 break;
 409                         spin_unlock(&udp_app_lock);
 410
 411                         IP_VS_DBG(9, "%s: Binding conn %u.%u.%u.%u:%u->"
 412                                   "%u.%u.%u.%u:%u to app %s on port %u\n",
 413                                   __func__,
 414                                   NIPQUAD(cp->caddr.ip), ntohs(cp->cport),
 415                                   NIPQUAD(cp->vaddr.ip), ntohs(cp->vport),
 416                                   inc->name, ntohs(inc->port));
 417                         cp->app = inc;
 418                         if (inc->init_conn)
 419                                 result = inc->init_conn(inc, cp);
 420                         goto out;
 421                 }
 422         }
 423         spin_unlock(&udp_app_lock);
 424
 425   out:
 426         return result;
 427 }
 428
 429
 430 static int udp_timeouts[IP_VS_UDP_S_LAST+1] = {
 431         [IP_VS_UDP_S_NORMAL]            =       5*60*HZ,
 432         [IP_VS_UDP_S_LAST]              =       2*HZ,
 433 };
 434
 435 static char * udp_state_name_table[IP_VS_UDP_S_LAST+1] = {
 436         [IP_VS_UDP_S_NORMAL]            =       "UDP",
 437         [IP_VS_UDP_S_LAST]              =       "BUG!",
 438 };
 439
 440
 441 static int
 442 udp_set_state_timeout(struct ip_vs_protocol *pp, char *sname, int to)
 443 {
 444         return ip_vs_set_state_timeout(pp->timeout_table, IP_VS_UDP_S_LAST,
 445                                        udp_state_name_table, sname, to);
 446 }
 447
 448 static const char * udp_state_name(int state)
 449 {
 450         if (state >= IP_VS_UDP_S_LAST)
 451                 return "ERR!";
 452         return udp_state_name_table[state] ? udp_state_name_table[state] : "?";
 453 }
 454
 455 static int
 456 udp_state_transition(struct ip_vs_conn *cp, int direction,
 457                      const struct sk_buff *skb,
 458                      struct ip_vs_protocol *pp)
 459 {
 460         cp->timeout = pp->timeout_table[IP_VS_UDP_S_NORMAL];
 461         return 1;
 462 }
 463
 464 static void udp_init(struct ip_vs_protocol *pp)
 465 {
 466         IP_VS_INIT_HASH_TABLE(udp_apps);
 467         pp->timeout_table = udp_timeouts;
 468 }
 469
 470 static void udp_exit(struct ip_vs_protocol *pp)
 471 {
 472 }
 473
 474
 475 struct ip_vs_protocol ip_vs_protocol_udp = {
 476         .name =                 "UDP",
 477         .protocol =             IPPROTO_UDP,
 478         .num_states =           IP_VS_UDP_S_LAST,
 479         .dont_defrag =          0,
 480         .init =                 udp_init,
 481         .exit =                 udp_exit,
 482         .conn_schedule =        udp_conn_schedule,
 483         .conn_in_get =          udp_conn_in_get,
 484         .conn_out_get =         udp_conn_out_get,
 485         .snat_handler =         udp_snat_handler,
 486         .dnat_handler =         udp_dnat_handler,
 487         .csum_check =           udp_csum_check,
 488         .state_transition =     udp_state_transition,
 489         .state_name =           udp_state_name,
 490         .register_app =         udp_register_app,
 491         .unregister_app =       udp_unregister_app,
 492         .app_conn_bind =        udp_app_conn_bind,
 493         .debug_packet =         ip_vs_tcpudp_debug_packet,
 494         .timeout_change =       NULL,
 495         .set_state_timeout =    udp_set_state_timeout,
 496 };