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.h>
  22 #include <linux/netfilter_ipv4.h>
  23 #include <linux/udp.h>
  24
  25 #include <net/ip_vs.h>
  26 #include <net/ip.h>
  27
  28 static struct ip_vs_conn *
  29 udp_conn_in_get(const struct sk_buff *skb, struct ip_vs_protocol *pp,
  30                 const struct iphdr *iph, unsigned int proto_off, int inverse)
  31 {
  32         struct ip_vs_conn *cp;
  33         __be16 _ports[2], *pptr;
  34
  35         pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
  36         if (pptr == NULL)
  37                 return NULL;
  38
  39         if (likely(!inverse)) {
  40                 cp = ip_vs_conn_in_get(iph->protocol,
  41                                        iph->saddr, pptr[0],
  42                                        iph->daddr, pptr[1]);
  43         } else {
  44                 cp = ip_vs_conn_in_get(iph->protocol,
  45                                        iph->daddr, pptr[1],
  46                                        iph->saddr, pptr[0]);
  47         }
  48
  49         return cp;
  50 }
  51
  52
  53 static struct ip_vs_conn *
  54 udp_conn_out_get(const struct sk_buff *skb, struct ip_vs_protocol *pp,
  55                  const struct iphdr *iph, unsigned int proto_off, int inverse)
  56 {
  57         struct ip_vs_conn *cp;
  58         __be16 _ports[2], *pptr;
  59
  60         pptr = skb_header_pointer(skb, ip_hdrlen(skb),
  61                                   sizeof(_ports), _ports);
  62         if (pptr == NULL)
  63                 return NULL;
  64
  65         if (likely(!inverse)) {
  66                 cp = ip_vs_conn_out_get(iph->protocol,
  67                                         iph->saddr, pptr[0],
  68                                         iph->daddr, pptr[1]);
  69         } else {
  70                 cp = ip_vs_conn_out_get(iph->protocol,
  71                                         iph->daddr, pptr[1],
  72                                         iph->saddr, pptr[0]);
  73         }
  74
  75         return cp;
  76 }
  77
  78
  79 static int
  80 udp_conn_schedule(struct sk_buff *skb, struct ip_vs_protocol *pp,
  81                   int *verdict, struct ip_vs_conn **cpp)
  82 {
  83         struct ip_vs_service *svc;
  84         struct udphdr _udph, *uh;
  85
  86         uh = skb_header_pointer(skb, ip_hdrlen(skb),
  87                                 sizeof(_udph), &_udph);
  88         if (uh == NULL) {
  89                 *verdict = NF_DROP;
  90                 return 0;
  91         }
  92
  93         if ((svc = ip_vs_service_get(skb->mark, ip_hdr(skb)->protocol,
  94                                      ip_hdr(skb)->daddr, uh->dest))) {
  95                 if (ip_vs_todrop()) {
  96                         /*
  97                          * It seems that we are very loaded.
  98                          * We have to drop this packet :(
  99                          */
 100                         ip_vs_service_put(svc);
 101                         *verdict = NF_DROP;
 102                         return 0;
 103                 }
 104
 105                 /*
 106                  * Let the virtual server select a real server for the
 107                  * incoming connection, and create a connection entry.
 108                  */
 109                 *cpp = ip_vs_schedule(svc, skb);
 110                 if (!*cpp) {
 111                         *verdict = ip_vs_leave(svc, skb, pp);
 112                         return 0;
 113                 }
 114                 ip_vs_service_put(svc);
 115         }
 116         return 1;
 117 }
 118
 119
 120 static inline void
 121 udp_fast_csum_update(struct udphdr *uhdr, __be32 oldip, __be32 newip,
 122                      __be16 oldport, __be16 newport)
 123 {
 124         uhdr->check =
 125                 csum_fold(ip_vs_check_diff4(oldip, newip,
 126                                  ip_vs_check_diff2(oldport, newport,
 127                                         ~csum_unfold(uhdr->check))));
 128         if (!uhdr->check)
 129                 uhdr->check = CSUM_MANGLED_0;
 130 }
 131
 132 static int
 133 udp_snat_handler(struct sk_buff *skb,
 134                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
 135 {
 136         struct udphdr *udph;
 137         const unsigned int udphoff = ip_hdrlen(skb);
 138
 139         /* csum_check requires unshared skb */
 140         if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
 141                 return 0;
 142
 143         if (unlikely(cp->app != NULL)) {
 144                 /* Some checks before mangling */
 145                 if (pp->csum_check && !pp->csum_check(skb, pp))
 146                         return 0;
 147
 148                 /*
 149                  *      Call application helper if needed
 150                  */
 151                 if (!ip_vs_app_pkt_out(cp, skb))
 152                         return 0;
 153         }
 154
 155         udph = (void *)ip_hdr(skb) + udphoff;
 156         udph->source = cp->vport;
 157
 158         /*
 159          *      Adjust UDP checksums
 160          */
 161         if (!cp->app && (udph->check != 0)) {
 162                 /* Only port and addr are changed, do fast csum update */
 163                 udp_fast_csum_update(udph, cp->daddr, cp->vaddr,
 164                                      cp->dport, cp->vport);
 165                 if (skb->ip_summed == CHECKSUM_COMPLETE)
 166                         skb->ip_summed = CHECKSUM_NONE;
 167         } else {
 168                 /* full checksum calculation */
 169                 udph->check = 0;
 170                 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
 171                 udph->check = csum_tcpudp_magic(cp->vaddr, cp->caddr,
 172                                                 skb->len - udphoff,
 173                                                 cp->protocol, skb->csum);
 174                 if (udph->check == 0)
 175                         udph->check = CSUM_MANGLED_0;
 176                 IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
 177                           pp->name, udph->check,
 178                           (char*)&(udph->check) - (char*)udph);
 179         }
 180         return 1;
 181 }
 182
 183
 184 static int
 185 udp_dnat_handler(struct sk_buff *skb,
 186                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
 187 {
 188         struct udphdr *udph;
 189         unsigned int udphoff = ip_hdrlen(skb);
 190
 191         /* csum_check requires unshared skb */
 192         if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
 193                 return 0;
 194
 195         if (unlikely(cp->app != NULL)) {
 196                 /* Some checks before mangling */
 197                 if (pp->csum_check && !pp->csum_check(skb, pp))
 198                         return 0;
 199
 200                 /*
 201                  *      Attempt ip_vs_app call.
 202                  *      It will fix ip_vs_conn
 203                  */
 204                 if (!ip_vs_app_pkt_in(cp, skb))
 205                         return 0;
 206         }
 207
 208         udph = (void *)ip_hdr(skb) + udphoff;
 209         udph->dest = cp->dport;
 210
 211         /*
 212          *      Adjust UDP checksums
 213          */
 214         if (!cp->app && (udph->check != 0)) {
 215                 /* Only port and addr are changed, do fast csum update */
 216                 udp_fast_csum_update(udph, cp->vaddr, cp->daddr,
 217                                      cp->vport, cp->dport);
 218                 if (skb->ip_summed == CHECKSUM_COMPLETE)
 219                         skb->ip_summed = CHECKSUM_NONE;
 220         } else {
 221                 /* full checksum calculation */
 222                 udph->check = 0;
 223                 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
 224                 udph->check = csum_tcpudp_magic(cp->caddr, cp->daddr,
 225                                                 skb->len - udphoff,
 226                                                 cp->protocol, skb->csum);
 227                 if (udph->check == 0)
 228                         udph->check = CSUM_MANGLED_0;
 229                 skb->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         const unsigned int udphoff = ip_hdrlen(skb);
 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_COMPLETE:
 251                         if (csum_tcpudp_magic(ip_hdr(skb)->saddr,
 252                                               ip_hdr(skb)->daddr,
 253                                               skb->len - udphoff,
 254                                               ip_hdr(skb)->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                         /* No need to checksum. */
 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(__be16 port)
 283 {
 284         return (((__force u16)port >> UDP_APP_TAB_BITS) ^ (__force u16)port)
 285                 & UDP_APP_TAB_MASK;
 286 }
 287
 288
 289 static int udp_register_app(struct ip_vs_app *inc)
 290 {
 291         struct ip_vs_app *i;
 292         __u16 hash;
 293         __be16 port = inc->port;
 294         int ret = 0;
 295
 296         hash = udp_app_hashkey(port);
 297
 298
 299         spin_lock_bh(&udp_app_lock);
 300         list_for_each_entry(i, &udp_apps[hash], p_list) {
 301                 if (i->port == port) {
 302                         ret = -EEXIST;
 303                         goto out;
 304                 }
 305         }
 306         list_add(&inc->p_list, &udp_apps[hash]);
 307         atomic_inc(&ip_vs_protocol_udp.appcnt);
 308
 309   out:
 310         spin_unlock_bh(&udp_app_lock);
 311         return ret;
 312 }
 313
 314
 315 static void
 316 udp_unregister_app(struct ip_vs_app *inc)
 317 {
 318         spin_lock_bh(&udp_app_lock);
 319         atomic_dec(&ip_vs_protocol_udp.appcnt);
 320         list_del(&inc->p_list);
 321         spin_unlock_bh(&udp_app_lock);
 322 }
 323
 324
 325 static int udp_app_conn_bind(struct ip_vs_conn *cp)
 326 {
 327         int hash;
 328         struct ip_vs_app *inc;
 329         int result = 0;
 330
 331         /* Default binding: bind app only for NAT */
 332         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
 333                 return 0;
 334
 335         /* Lookup application incarnations and bind the right one */
 336         hash = udp_app_hashkey(cp->vport);
 337
 338         spin_lock(&udp_app_lock);
 339         list_for_each_entry(inc, &udp_apps[hash], p_list) {
 340                 if (inc->port == cp->vport) {
 341                         if (unlikely(!ip_vs_app_inc_get(inc)))
 342                                 break;
 343                         spin_unlock(&udp_app_lock);
 344
 345                         IP_VS_DBG(9, "%s: Binding conn %u.%u.%u.%u:%u->"
 346                                   "%u.%u.%u.%u:%u to app %s on port %u\n",
 347                                   __func__,
 348                                   NIPQUAD(cp->caddr), ntohs(cp->cport),
 349                                   NIPQUAD(cp->vaddr), ntohs(cp->vport),
 350                                   inc->name, ntohs(inc->port));
 351                         cp->app = inc;
 352                         if (inc->init_conn)
 353                                 result = inc->init_conn(inc, cp);
 354                         goto out;
 355                 }
 356         }
 357         spin_unlock(&udp_app_lock);
 358
 359   out:
 360         return result;
 361 }
 362
 363
 364 static int udp_timeouts[IP_VS_UDP_S_LAST+1] = {
 365         [IP_VS_UDP_S_NORMAL]            =       5*60*HZ,
 366         [IP_VS_UDP_S_LAST]              =       2*HZ,
 367 };
 368
 369 static char * udp_state_name_table[IP_VS_UDP_S_LAST+1] = {
 370         [IP_VS_UDP_S_NORMAL]            =       "UDP",
 371         [IP_VS_UDP_S_LAST]              =       "BUG!",
 372 };
 373
 374
 375 static int
 376 udp_set_state_timeout(struct ip_vs_protocol *pp, char *sname, int to)
 377 {
 378         return ip_vs_set_state_timeout(pp->timeout_table, IP_VS_UDP_S_LAST,
 379                                        udp_state_name_table, sname, to);
 380 }
 381
 382 static const char * udp_state_name(int state)
 383 {
 384         if (state >= IP_VS_UDP_S_LAST)
 385                 return "ERR!";
 386         return udp_state_name_table[state] ? udp_state_name_table[state] : "?";
 387 }
 388
 389 static int
 390 udp_state_transition(struct ip_vs_conn *cp, int direction,
 391                      const struct sk_buff *skb,
 392                      struct ip_vs_protocol *pp)
 393 {
 394         cp->timeout = pp->timeout_table[IP_VS_UDP_S_NORMAL];
 395         return 1;
 396 }
 397
 398 static void udp_init(struct ip_vs_protocol *pp)
 399 {
 400         IP_VS_INIT_HASH_TABLE(udp_apps);
 401         pp->timeout_table = udp_timeouts;
 402 }
 403
 404 static void udp_exit(struct ip_vs_protocol *pp)
 405 {
 406 }
 407
 408
 409 struct ip_vs_protocol ip_vs_protocol_udp = {
 410         .name =                 "UDP",
 411         .protocol =             IPPROTO_UDP,
 412         .dont_defrag =          0,
 413         .init =                 udp_init,
 414         .exit =                 udp_exit,
 415         .conn_schedule =        udp_conn_schedule,
 416         .conn_in_get =          udp_conn_in_get,
 417         .conn_out_get =         udp_conn_out_get,
 418         .snat_handler =         udp_snat_handler,
 419         .dnat_handler =         udp_dnat_handler,
 420         .csum_check =           udp_csum_check,
 421         .state_transition =     udp_state_transition,
 422         .state_name =           udp_state_name,
 423         .register_app =         udp_register_app,
 424         .unregister_app =       udp_unregister_app,
 425         .app_conn_bind =        udp_app_conn_bind,
 426         .debug_packet =         ip_vs_tcpudp_debug_packet,
 427         .timeout_change =       NULL,
 428         .set_state_timeout =    udp_set_state_timeout,
 429 };