net/ipv4/ipvs/ip_vs_proto_udp.c

   1 /*
   2  * ip_vs_proto_udp.c:   UDP load balancing support for IPVS
   3  *
   4  * Version:     $Id: ip_vs_proto_udp.c,v 1.3 2002/11/30 01:50:35 wensong Exp $
   5  *
   6  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
   7  *              Julian Anastasov <ja@ssi.bg>
   8  *
   9  *              This program is free software; you can redistribute it and/or
  10  *              modify it under the terms of the GNU General Public License
  11  *              as published by the Free Software Foundation; either version
  12  *              2 of the License, or (at your option) any later version.
  13  *
  14  * Changes:
  15  *
  16  */
  17
  18 #include <linux/in.h>
  19 #include <linux/ip.h>
  20 #include <linux/kernel.h>
  21 #include <linux/netfilter_ipv4.h>
  22 #include <linux/udp.h>
  23
  24 #include <net/ip_vs.h>
  25
  26
  27 static struct ip_vs_conn *
  28 udp_conn_in_get(const struct sk_buff *skb, struct ip_vs_protocol *pp,
  29                 const struct iphdr *iph, unsigned int proto_off, 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(iph->protocol,
  40                                        iph->saddr, pptr[0],
  41                                        iph->daddr, pptr[1]);
  42         } else {
  43                 cp = ip_vs_conn_in_get(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(const struct sk_buff *skb, struct ip_vs_protocol *pp,
  54                  const struct iphdr *iph, unsigned int proto_off, int inverse)
  55 {
  56         struct ip_vs_conn *cp;
  57         __be16 _ports[2], *pptr;
  58
  59         pptr = skb_header_pointer(skb, skb->nh.iph->ihl*4,
  60                                   sizeof(_ports), _ports);
  61         if (pptr == NULL)
  62                 return NULL;
  63
  64         if (likely(!inverse)) {
  65                 cp = ip_vs_conn_out_get(iph->protocol,
  66                                         iph->saddr, pptr[0],
  67                                         iph->daddr, pptr[1]);
  68         } else {
  69                 cp = ip_vs_conn_out_get(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(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
  85         uh = skb_header_pointer(skb, skb->nh.iph->ihl*4,
  86                                 sizeof(_udph), &_udph);
  87         if (uh == NULL) {
  88                 *verdict = NF_DROP;
  89                 return 0;
  90         }
  91
  92         if ((svc = ip_vs_service_get(skb->mark, skb->nh.iph->protocol,
  93                                      skb->nh.iph->daddr, uh->dest))) {
  94                 if (ip_vs_todrop()) {
  95                         /*
  96                          * It seems that we are very loaded.
  97                          * We have to drop this packet :(
  98                          */
  99                         ip_vs_service_put(svc);
 100                         *verdict = NF_DROP;
 101                         return 0;
 102                 }
 103
 104                 /*
 105                  * Let the virtual server select a real server for the
 106                  * incoming connection, and create a connection entry.
 107                  */
 108                 *cpp = ip_vs_schedule(svc, skb);
 109                 if (!*cpp) {
 110                         *verdict = ip_vs_leave(svc, skb, pp);
 111                         return 0;
 112                 }
 113                 ip_vs_service_put(svc);
 114         }
 115         return 1;
 116 }
 117
 118
 119 static inline void
 120 udp_fast_csum_update(struct udphdr *uhdr, __be32 oldip, __be32 newip,
 121                      __be16 oldport, __be16 newport)
 122 {
 123         uhdr->check =
 124                 ip_vs_check_diff(~oldip, newip,
 125                                  ip_vs_check_diff(oldport ^ htons(0xFFFF),
 126                                                   newport, uhdr->check));
 127         if (!uhdr->check)
 128                 uhdr->check = -1;
 129 }
 130
 131 static int
 132 udp_snat_handler(struct sk_buff **pskb,
 133                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
 134 {
 135         struct udphdr *udph;
 136         unsigned int udphoff = (*pskb)->nh.iph->ihl * 4;
 137
 138         /* csum_check requires unshared skb */
 139         if (!ip_vs_make_skb_writable(pskb, udphoff+sizeof(*udph)))
 140                 return 0;
 141
 142         if (unlikely(cp->app != NULL)) {
 143                 /* Some checks before mangling */
 144                 if (pp->csum_check && !pp->csum_check(*pskb, pp))
 145                         return 0;
 146
 147                 /*
 148                  *      Call application helper if needed
 149                  */
 150                 if (!ip_vs_app_pkt_out(cp, pskb))
 151                         return 0;
 152         }
 153
 154         udph = (void *)(*pskb)->nh.iph + udphoff;
 155         udph->source = cp->vport;
 156
 157         /*
 158          *      Adjust UDP checksums
 159          */
 160         if (!cp->app && (udph->check != 0)) {
 161                 /* Only port and addr are changed, do fast csum update */
 162                 udp_fast_csum_update(udph, cp->daddr, cp->vaddr,
 163                                      cp->dport, cp->vport);
 164                 if ((*pskb)->ip_summed == CHECKSUM_COMPLETE)
 165                         (*pskb)->ip_summed = CHECKSUM_NONE;
 166         } else {
 167                 /* full checksum calculation */
 168                 udph->check = 0;
 169                 (*pskb)->csum = skb_checksum(*pskb, udphoff,
 170                                              (*pskb)->len - udphoff, 0);
 171                 udph->check = csum_tcpudp_magic(cp->vaddr, cp->caddr,
 172                                                 (*pskb)->len - udphoff,
 173                                                 cp->protocol,
 174                                                 (*pskb)->csum);
 175                 if (udph->check == 0)
 176                         udph->check = -1;
 177                 IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
 178                           pp->name, udph->check,
 179                           (char*)&(udph->check) - (char*)udph);
 180         }
 181         return 1;
 182 }
 183
 184
 185 static int
 186 udp_dnat_handler(struct sk_buff **pskb,
 187                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
 188 {
 189         struct udphdr *udph;
 190         unsigned int udphoff = (*pskb)->nh.iph->ihl * 4;
 191
 192         /* csum_check requires unshared skb */
 193         if (!ip_vs_make_skb_writable(pskb, udphoff+sizeof(*udph)))
 194                 return 0;
 195
 196         if (unlikely(cp->app != NULL)) {
 197                 /* Some checks before mangling */
 198                 if (pp->csum_check && !pp->csum_check(*pskb, pp))
 199                         return 0;
 200
 201                 /*
 202                  *      Attempt ip_vs_app call.
 203                  *      It will fix ip_vs_conn
 204                  */
 205                 if (!ip_vs_app_pkt_in(cp, pskb))
 206                         return 0;
 207         }
 208
 209         udph = (void *)(*pskb)->nh.iph + udphoff;
 210         udph->dest = cp->dport;
 211
 212         /*
 213          *      Adjust UDP checksums
 214          */
 215         if (!cp->app && (udph->check != 0)) {
 216                 /* Only port and addr are changed, do fast csum update */
 217                 udp_fast_csum_update(udph, cp->vaddr, cp->daddr,
 218                                      cp->vport, cp->dport);
 219                 if ((*pskb)->ip_summed == CHECKSUM_COMPLETE)
 220                         (*pskb)->ip_summed = CHECKSUM_NONE;
 221         } else {
 222                 /* full checksum calculation */
 223                 udph->check = 0;
 224                 (*pskb)->csum = skb_checksum(*pskb, udphoff,
 225                                              (*pskb)->len - udphoff, 0);
 226                 udph->check = csum_tcpudp_magic(cp->caddr, cp->daddr,
 227                                                 (*pskb)->len - udphoff,
 228                                                 cp->protocol,
 229                                                 (*pskb)->csum);
 230                 if (udph->check == 0)
 231                         udph->check = -1;
 232                 (*pskb)->ip_summed = CHECKSUM_UNNECESSARY;
 233         }
 234         return 1;
 235 }
 236
 237
 238 static int
 239 udp_csum_check(struct sk_buff *skb, struct ip_vs_protocol *pp)
 240 {
 241         struct udphdr _udph, *uh;
 242         unsigned int udphoff = skb->nh.iph->ihl*4;
 243
 244         uh = skb_header_pointer(skb, udphoff, sizeof(_udph), &_udph);
 245         if (uh == NULL)
 246                 return 0;
 247
 248         if (uh->check != 0) {
 249                 switch (skb->ip_summed) {
 250                 case CHECKSUM_NONE:
 251                         skb->csum = skb_checksum(skb, udphoff,
 252                                                  skb->len - udphoff, 0);
 253                 case CHECKSUM_COMPLETE:
 254                         if (csum_tcpudp_magic(skb->nh.iph->saddr,
 255                                               skb->nh.iph->daddr,
 256                                               skb->len - udphoff,
 257                                               skb->nh.iph->protocol,
 258                                               skb->csum)) {
 259                                 IP_VS_DBG_RL_PKT(0, pp, skb, 0,
 260                                                  "Failed checksum for");
 261                                 return 0;
 262                         }
 263                         break;
 264                 default:
 265                         /* No need to checksum. */
 266                         break;
 267                 }
 268         }
 269         return 1;
 270 }
 271
 272
 273 /*
 274  *      Note: the caller guarantees that only one of register_app,
 275  *      unregister_app or app_conn_bind is called each time.
 276  */
 277
 278 #define UDP_APP_TAB_BITS        4
 279 #define UDP_APP_TAB_SIZE        (1 << UDP_APP_TAB_BITS)
 280 #define UDP_APP_TAB_MASK        (UDP_APP_TAB_SIZE - 1)
 281
 282 static struct list_head udp_apps[UDP_APP_TAB_SIZE];
 283 static DEFINE_SPINLOCK(udp_app_lock);
 284
 285 static inline __u16 udp_app_hashkey(__u16 port)
 286 {
 287         return ((port >> UDP_APP_TAB_BITS) ^ port) & UDP_APP_TAB_MASK;
 288 }
 289
 290
 291 static int udp_register_app(struct ip_vs_app *inc)
 292 {
 293         struct ip_vs_app *i;
 294         __u16 hash, port = inc->port;
 295         int ret = 0;
 296
 297         hash = udp_app_hashkey(port);
 298
 299
 300         spin_lock_bh(&udp_app_lock);
 301         list_for_each_entry(i, &udp_apps[hash], p_list) {
 302                 if (i->port == port) {
 303                         ret = -EEXIST;
 304                         goto out;
 305                 }
 306         }
 307         list_add(&inc->p_list, &udp_apps[hash]);
 308         atomic_inc(&ip_vs_protocol_udp.appcnt);
 309
 310   out:
 311         spin_unlock_bh(&udp_app_lock);
 312         return ret;
 313 }
 314
 315
 316 static void
 317 udp_unregister_app(struct ip_vs_app *inc)
 318 {
 319         spin_lock_bh(&udp_app_lock);
 320         atomic_dec(&ip_vs_protocol_udp.appcnt);
 321         list_del(&inc->p_list);
 322         spin_unlock_bh(&udp_app_lock);
 323 }
 324
 325
 326 static int udp_app_conn_bind(struct ip_vs_conn *cp)
 327 {
 328         int hash;
 329         struct ip_vs_app *inc;
 330         int result = 0;
 331
 332         /* Default binding: bind app only for NAT */
 333         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
 334                 return 0;
 335
 336         /* Lookup application incarnations and bind the right one */
 337         hash = udp_app_hashkey(cp->vport);
 338
 339         spin_lock(&udp_app_lock);
 340         list_for_each_entry(inc, &udp_apps[hash], p_list) {
 341                 if (inc->port == cp->vport) {
 342                         if (unlikely(!ip_vs_app_inc_get(inc)))
 343                                 break;
 344                         spin_unlock(&udp_app_lock);
 345
 346                         IP_VS_DBG(9, "%s: Binding conn %u.%u.%u.%u:%u->"
 347                                   "%u.%u.%u.%u:%u to app %s on port %u\n",
 348                                   __FUNCTION__,
 349                                   NIPQUAD(cp->caddr), ntohs(cp->cport),
 350                                   NIPQUAD(cp->vaddr), ntohs(cp->vport),
 351                                   inc->name, ntohs(inc->port));
 352                         cp->app = inc;
 353                         if (inc->init_conn)
 354                                 result = inc->init_conn(inc, cp);
 355                         goto out;
 356                 }
 357         }
 358         spin_unlock(&udp_app_lock);
 359
 360   out:
 361         return result;
 362 }
 363
 364
 365 static int udp_timeouts[IP_VS_UDP_S_LAST+1] = {
 366         [IP_VS_UDP_S_NORMAL]            =       5*60*HZ,
 367         [IP_VS_UDP_S_LAST]              =       2*HZ,
 368 };
 369
 370 static char * udp_state_name_table[IP_VS_UDP_S_LAST+1] = {
 371         [IP_VS_UDP_S_NORMAL]            =       "UDP",
 372         [IP_VS_UDP_S_LAST]              =       "BUG!",
 373 };
 374
 375
 376 static int
 377 udp_set_state_timeout(struct ip_vs_protocol *pp, char *sname, int to)
 378 {
 379         return ip_vs_set_state_timeout(pp->timeout_table, IP_VS_UDP_S_LAST,
 380                                        udp_state_name_table, sname, to);
 381 }
 382
 383 static const char * udp_state_name(int state)
 384 {
 385         if (state >= IP_VS_UDP_S_LAST)
 386                 return "ERR!";
 387         return udp_state_name_table[state] ? udp_state_name_table[state] : "?";
 388 }
 389
 390 static int
 391 udp_state_transition(struct ip_vs_conn *cp, int direction,
 392                      const struct sk_buff *skb,
 393                      struct ip_vs_protocol *pp)
 394 {
 395         cp->timeout = pp->timeout_table[IP_VS_UDP_S_NORMAL];
 396         return 1;
 397 }
 398
 399 static void udp_init(struct ip_vs_protocol *pp)
 400 {
 401         IP_VS_INIT_HASH_TABLE(udp_apps);
 402         pp->timeout_table = udp_timeouts;
 403 }
 404
 405 static void udp_exit(struct ip_vs_protocol *pp)
 406 {
 407 }
 408
 409
 410 struct ip_vs_protocol ip_vs_protocol_udp = {
 411         .name =                 "UDP",
 412         .protocol =             IPPROTO_UDP,
 413         .dont_defrag =          0,
 414         .init =                 udp_init,
 415         .exit =                 udp_exit,
 416         .conn_schedule =        udp_conn_schedule,
 417         .conn_in_get =          udp_conn_in_get,
 418         .conn_out_get =         udp_conn_out_get,
 419         .snat_handler =         udp_snat_handler,
 420         .dnat_handler =         udp_dnat_handler,
 421         .csum_check =           udp_csum_check,
 422         .state_transition =     udp_state_transition,
 423         .state_name =           udp_state_name,
 424         .register_app =         udp_register_app,
 425         .unregister_app =       udp_unregister_app,
 426         .app_conn_bind =        udp_app_conn_bind,
 427         .debug_packet =         ip_vs_tcpudp_debug_packet,
 428         .timeout_change =       NULL,
 429         .set_state_timeout =    udp_set_state_timeout,
 430 };