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/kernel.h>
  19 #include <linux/netfilter_ipv4.h>
  20
  21 #include <net/ip_vs.h>
  22
  23
  24 static struct ip_vs_conn *
  25 udp_conn_in_get(const struct sk_buff *skb, struct ip_vs_protocol *pp,
  26                 const struct iphdr *iph, unsigned int proto_off, int inverse)
  27 {
  28         struct ip_vs_conn *cp;
  29         __u16 _ports[2], *pptr;
  30
  31         pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
  32         if (pptr == NULL)
  33                 return NULL;
  34
  35         if (likely(!inverse)) {
  36                 cp = ip_vs_conn_in_get(iph->protocol,
  37                                        iph->saddr, pptr[0],
  38                                        iph->daddr, pptr[1]);
  39         } else {
  40                 cp = ip_vs_conn_in_get(iph->protocol,
  41                                        iph->daddr, pptr[1],
  42                                        iph->saddr, pptr[0]);
  43         }
  44
  45         return cp;
  46 }
  47
  48
  49 static struct ip_vs_conn *
  50 udp_conn_out_get(const struct sk_buff *skb, struct ip_vs_protocol *pp,
  51                  const struct iphdr *iph, unsigned int proto_off, int inverse)
  52 {
  53         struct ip_vs_conn *cp;
  54         __u16 _ports[2], *pptr;
  55
  56         pptr = skb_header_pointer(skb, skb->nh.iph->ihl*4,
  57                                   sizeof(_ports), _ports);
  58         if (pptr == NULL)
  59                 return NULL;
  60
  61         if (likely(!inverse)) {
  62                 cp = ip_vs_conn_out_get(iph->protocol,
  63                                         iph->saddr, pptr[0],
  64                                         iph->daddr, pptr[1]);
  65         } else {
  66                 cp = ip_vs_conn_out_get(iph->protocol,
  67                                         iph->daddr, pptr[1],
  68                                         iph->saddr, pptr[0]);
  69         }
  70
  71         return cp;
  72 }
  73
  74
  75 static int
  76 udp_conn_schedule(struct sk_buff *skb, struct ip_vs_protocol *pp,
  77                   int *verdict, struct ip_vs_conn **cpp)
  78 {
  79         struct ip_vs_service *svc;
  80         struct udphdr _udph, *uh;
  81
  82         uh = skb_header_pointer(skb, skb->nh.iph->ihl*4,
  83                                 sizeof(_udph), &_udph);
  84         if (uh == NULL) {
  85                 *verdict = NF_DROP;
  86                 return 0;
  87         }
  88
  89         if ((svc = ip_vs_service_get(skb->nfmark, skb->nh.iph->protocol,
  90                                      skb->nh.iph->daddr, uh->dest))) {
  91                 if (ip_vs_todrop()) {
  92                         /*
  93                          * It seems that we are very loaded.
  94                          * We have to drop this packet :(
  95                          */
  96                         ip_vs_service_put(svc);
  97                         *verdict = NF_DROP;
  98                         return 0;
  99                 }
 100
 101                 /*
 102                  * Let the virtual server select a real server for the
 103                  * incoming connection, and create a connection entry.
 104                  */
 105                 *cpp = ip_vs_schedule(svc, skb);
 106                 if (!*cpp) {
 107                         *verdict = ip_vs_leave(svc, skb, pp);
 108                         return 0;
 109                 }
 110                 ip_vs_service_put(svc);
 111         }
 112         return 1;
 113 }
 114
 115
 116 static inline void
 117 udp_fast_csum_update(struct udphdr *uhdr, u32 oldip, u32 newip,
 118                      u16 oldport, u16 newport)
 119 {
 120         uhdr->check =
 121                 ip_vs_check_diff(~oldip, newip,
 122                                  ip_vs_check_diff(oldport ^ 0xFFFF,
 123                                                   newport, uhdr->check));
 124         if (!uhdr->check)
 125                 uhdr->check = 0xFFFF;
 126 }
 127
 128 static int
 129 udp_snat_handler(struct sk_buff **pskb,
 130                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
 131 {
 132         struct udphdr *udph;
 133         unsigned int udphoff = (*pskb)->nh.iph->ihl * 4;
 134
 135         /* csum_check requires unshared skb */
 136         if (!ip_vs_make_skb_writable(pskb, udphoff+sizeof(*udph)))
 137                 return 0;
 138
 139         if (unlikely(cp->app != NULL)) {
 140                 /* Some checks before mangling */
 141                 if (pp->csum_check && !pp->csum_check(*pskb, pp))
 142                         return 0;
 143
 144                 /*
 145                  *      Call application helper if needed
 146                  */
 147                 if (!ip_vs_app_pkt_out(cp, pskb))
 148                         return 0;
 149         }
 150
 151         udph = (void *)(*pskb)->nh.iph + udphoff;
 152         udph->source = cp->vport;
 153
 154         /*
 155          *      Adjust UDP checksums
 156          */
 157         if (!cp->app && (udph->check != 0)) {
 158                 /* Only port and addr are changed, do fast csum update */
 159                 udp_fast_csum_update(udph, cp->daddr, cp->vaddr,
 160                                      cp->dport, cp->vport);
 161                 if ((*pskb)->ip_summed == CHECKSUM_HW)
 162                         (*pskb)->ip_summed = CHECKSUM_NONE;
 163         } else {
 164                 /* full checksum calculation */
 165                 udph->check = 0;
 166                 (*pskb)->csum = skb_checksum(*pskb, udphoff,
 167                                              (*pskb)->len - udphoff, 0);
 168                 udph->check = csum_tcpudp_magic(cp->vaddr, cp->caddr,
 169                                                 (*pskb)->len - udphoff,
 170                                                 cp->protocol,
 171                                                 (*pskb)->csum);
 172                 if (udph->check == 0)
 173                         udph->check = 0xFFFF;
 174                 IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
 175                           pp->name, udph->check,
 176                           (char*)&(udph->check) - (char*)udph);
 177         }
 178         return 1;
 179 }
 180
 181
 182 static int
 183 udp_dnat_handler(struct sk_buff **pskb,
 184                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
 185 {
 186         struct udphdr *udph;
 187         unsigned int udphoff = (*pskb)->nh.iph->ihl * 4;
 188
 189         /* csum_check requires unshared skb */
 190         if (!ip_vs_make_skb_writable(pskb, udphoff+sizeof(*udph)))
 191                 return 0;
 192
 193         if (unlikely(cp->app != NULL)) {
 194                 /* Some checks before mangling */
 195                 if (pp->csum_check && !pp->csum_check(*pskb, pp))
 196                         return 0;
 197
 198                 /*
 199                  *      Attempt ip_vs_app call.
 200                  *      It will fix ip_vs_conn
 201                  */
 202                 if (!ip_vs_app_pkt_in(cp, pskb))
 203                         return 0;
 204         }
 205
 206         udph = (void *)(*pskb)->nh.iph + udphoff;
 207         udph->dest = cp->dport;
 208
 209         /*
 210          *      Adjust UDP checksums
 211          */
 212         if (!cp->app && (udph->check != 0)) {
 213                 /* Only port and addr are changed, do fast csum update */
 214                 udp_fast_csum_update(udph, cp->vaddr, cp->daddr,
 215                                      cp->vport, cp->dport);
 216                 if ((*pskb)->ip_summed == CHECKSUM_HW)
 217                         (*pskb)->ip_summed = CHECKSUM_NONE;
 218         } else {
 219                 /* full checksum calculation */
 220                 udph->check = 0;
 221                 (*pskb)->csum = skb_checksum(*pskb, udphoff,
 222                                              (*pskb)->len - udphoff, 0);
 223                 udph->check = csum_tcpudp_magic(cp->caddr, cp->daddr,
 224                                                 (*pskb)->len - udphoff,
 225                                                 cp->protocol,
 226                                                 (*pskb)->csum);
 227                 if (udph->check == 0)
 228                         udph->check = 0xFFFF;
 229                 (*pskb)->ip_summed = CHECKSUM_UNNECESSARY;
 230         }
 231         return 1;
 232 }
 233
 234
 235 static int
 236 udp_csum_check(struct sk_buff *skb, struct ip_vs_protocol *pp)
 237 {
 238         struct udphdr _udph, *uh;
 239         unsigned int udphoff = skb->nh.iph->ihl*4;
 240
 241         uh = skb_header_pointer(skb, udphoff, sizeof(_udph), &_udph);
 242         if (uh == NULL)
 243                 return 0;
 244
 245         if (uh->check != 0) {
 246                 switch (skb->ip_summed) {
 247                 case CHECKSUM_NONE:
 248                         skb->csum = skb_checksum(skb, udphoff,
 249                                                  skb->len - udphoff, 0);
 250                 case CHECKSUM_HW:
 251                         if (csum_tcpudp_magic(skb->nh.iph->saddr,
 252                                               skb->nh.iph->daddr,
 253                                               skb->len - udphoff,
 254                                               skb->nh.iph->protocol,
 255                                               skb->csum)) {
 256                                 IP_VS_DBG_RL_PKT(0, pp, skb, 0,
 257                                                  "Failed checksum for");
 258                                 return 0;
 259                         }
 260                         break;
 261                 default:
 262                         /* CHECKSUM_UNNECESSARY */
 263                         break;
 264                 }
 265         }
 266         return 1;
 267 }
 268
 269
 270 /*
 271  *      Note: the caller guarantees that only one of register_app,
 272  *      unregister_app or app_conn_bind is called each time.
 273  */
 274
 275 #define UDP_APP_TAB_BITS        4
 276 #define UDP_APP_TAB_SIZE        (1 << UDP_APP_TAB_BITS)
 277 #define UDP_APP_TAB_MASK        (UDP_APP_TAB_SIZE - 1)
 278
 279 static struct list_head udp_apps[UDP_APP_TAB_SIZE];
 280 static DEFINE_SPINLOCK(udp_app_lock);
 281
 282 static inline __u16 udp_app_hashkey(__u16 port)
 283 {
 284         return ((port >> UDP_APP_TAB_BITS) ^ port) & UDP_APP_TAB_MASK;
 285 }
 286
 287
 288 static int udp_register_app(struct ip_vs_app *inc)
 289 {
 290         struct ip_vs_app *i;
 291         __u16 hash, port = inc->port;
 292         int ret = 0;
 293
 294         hash = udp_app_hashkey(port);
 295
 296
 297         spin_lock_bh(&udp_app_lock);
 298         list_for_each_entry(i, &udp_apps[hash], p_list) {
 299                 if (i->port == port) {
 300                         ret = -EEXIST;
 301                         goto out;
 302                 }
 303         }
 304         list_add(&inc->p_list, &udp_apps[hash]);
 305         atomic_inc(&ip_vs_protocol_udp.appcnt);
 306
 307   out:
 308         spin_unlock_bh(&udp_app_lock);
 309         return ret;
 310 }
 311
 312
 313 static void
 314 udp_unregister_app(struct ip_vs_app *inc)
 315 {
 316         spin_lock_bh(&udp_app_lock);
 317         atomic_dec(&ip_vs_protocol_udp.appcnt);
 318         list_del(&inc->p_list);
 319         spin_unlock_bh(&udp_app_lock);
 320 }
 321
 322
 323 static int udp_app_conn_bind(struct ip_vs_conn *cp)
 324 {
 325         int hash;
 326         struct ip_vs_app *inc;
 327         int result = 0;
 328
 329         /* Default binding: bind app only for NAT */
 330         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
 331                 return 0;
 332
 333         /* Lookup application incarnations and bind the right one */
 334         hash = udp_app_hashkey(cp->vport);
 335
 336         spin_lock(&udp_app_lock);
 337         list_for_each_entry(inc, &udp_apps[hash], p_list) {
 338                 if (inc->port == cp->vport) {
 339                         if (unlikely(!ip_vs_app_inc_get(inc)))
 340                                 break;
 341                         spin_unlock(&udp_app_lock);
 342
 343                         IP_VS_DBG(9, "%s: Binding conn %u.%u.%u.%u:%u->"
 344                                   "%u.%u.%u.%u:%u to app %s on port %u\n",
 345                                   __FUNCTION__,
 346                                   NIPQUAD(cp->caddr), ntohs(cp->cport),
 347                                   NIPQUAD(cp->vaddr), ntohs(cp->vport),
 348                                   inc->name, ntohs(inc->port));
 349                         cp->app = inc;
 350                         if (inc->init_conn)
 351                                 result = inc->init_conn(inc, cp);
 352                         goto out;
 353                 }
 354         }
 355         spin_unlock(&udp_app_lock);
 356
 357   out:
 358         return result;
 359 }
 360
 361
 362 static int udp_timeouts[IP_VS_UDP_S_LAST+1] = {
 363         [IP_VS_UDP_S_NORMAL]            =       5*60*HZ,
 364         [IP_VS_UDP_S_LAST]              =       2*HZ,
 365 };
 366
 367 static char * udp_state_name_table[IP_VS_UDP_S_LAST+1] = {
 368         [IP_VS_UDP_S_NORMAL]            =       "UDP",
 369         [IP_VS_UDP_S_LAST]              =       "BUG!",
 370 };
 371
 372
 373 static int
 374 udp_set_state_timeout(struct ip_vs_protocol *pp, char *sname, int to)
 375 {
 376         return ip_vs_set_state_timeout(pp->timeout_table, IP_VS_UDP_S_LAST,
 377                                        udp_state_name_table, sname, to);
 378 }
 379
 380 static const char * udp_state_name(int state)
 381 {
 382         if (state >= IP_VS_UDP_S_LAST)
 383                 return "ERR!";
 384         return udp_state_name_table[state] ? udp_state_name_table[state] : "?";
 385 }
 386
 387 static int
 388 udp_state_transition(struct ip_vs_conn *cp, int direction,
 389                      const struct sk_buff *skb,
 390                      struct ip_vs_protocol *pp)
 391 {
 392         cp->timeout = pp->timeout_table[IP_VS_UDP_S_NORMAL];
 393         return 1;
 394 }
 395
 396 static void udp_init(struct ip_vs_protocol *pp)
 397 {
 398         IP_VS_INIT_HASH_TABLE(udp_apps);
 399         pp->timeout_table = udp_timeouts;
 400 }
 401
 402 static void udp_exit(struct ip_vs_protocol *pp)
 403 {
 404 }
 405
 406
 407 struct ip_vs_protocol ip_vs_protocol_udp = {
 408         .name =                 "UDP",
 409         .protocol =             IPPROTO_UDP,
 410         .dont_defrag =          0,
 411         .init =                 udp_init,
 412         .exit =                 udp_exit,
 413         .conn_schedule =        udp_conn_schedule,
 414         .conn_in_get =          udp_conn_in_get,
 415         .conn_out_get =         udp_conn_out_get,
 416         .snat_handler =         udp_snat_handler,
 417         .dnat_handler =         udp_dnat_handler,
 418         .csum_check =           udp_csum_check,
 419         .state_transition =     udp_state_transition,
 420         .state_name =           udp_state_name,
 421         .register_app =         udp_register_app,
 422         .unregister_app =       udp_unregister_app,
 423         .app_conn_bind =        udp_app_conn_bind,
 424         .debug_packet =         ip_vs_tcpudp_debug_packet,
 425         .timeout_change =       NULL,
 426         .set_state_timeout =    udp_set_state_timeout,
 427 };