net/netfilter/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:     Hans Schillstrom <hans.schillstrom@ericsson.com>
  13  *              Network name space (netns) aware.
  14  *
  15  */
  16
  17 #define KMSG_COMPONENT "IPVS"
  18 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  19
  20 #include <linux/in.h>
  21 #include <linux/ip.h>
  22 #include <linux/kernel.h>
  23 #include <linux/netfilter.h>
  24 #include <linux/netfilter_ipv4.h>
  25 #include <linux/udp.h>
  26
  27 #include <net/ip_vs.h>
  28 #include <net/ip.h>
  29 #include <net/ip6_checksum.h>
  30
  31 static int
  32 udp_conn_schedule(int af, struct sk_buff *skb, struct ip_vs_proto_data *pd,
  33                   int *verdict, struct ip_vs_conn **cpp,
  34                   struct ip_vs_iphdr *iph)
  35 {
  36         struct net *net;
  37         struct ip_vs_service *svc;
  38         struct udphdr _udph, *uh;
  39
  40         /* IPv6 fragments, only first fragment will hit this */
  41         uh = skb_header_pointer(skb, iph->len, sizeof(_udph), &_udph);
  42         if (uh == NULL) {
  43                 *verdict = NF_DROP;
  44                 return 0;
  45         }
  46         net = skb_net(skb);
  47         rcu_read_lock();
  48         svc = ip_vs_service_find(net, af, skb->mark, iph->protocol,
  49                                  &iph->daddr, uh->dest);
  50         if (svc) {
  51                 int ignored;
  52
  53                 if (ip_vs_todrop(net_ipvs(net))) {
  54                         /*
  55                          * It seems that we are very loaded.
  56                          * We have to drop this packet :(
  57                          */
  58                         rcu_read_unlock();
  59                         *verdict = NF_DROP;
  60                         return 0;
  61                 }
  62
  63                 /*
  64                  * Let the virtual server select a real server for the
  65                  * incoming connection, and create a connection entry.
  66                  */
  67                 *cpp = ip_vs_schedule(svc, skb, pd, &ignored, iph);
  68                 if (!*cpp && ignored <= 0) {
  69                         if (!ignored)
  70                                 *verdict = ip_vs_leave(svc, skb, pd, iph);
  71                         else
  72                                 *verdict = NF_DROP;
  73                         rcu_read_unlock();
  74                         return 0;
  75                 }
  76         }
  77         rcu_read_unlock();
  78         /* NF_ACCEPT */
  79         return 1;
  80 }
  81
  82
  83 static inline void
  84 udp_fast_csum_update(int af, struct udphdr *uhdr,
  85                      const union nf_inet_addr *oldip,
  86                      const union nf_inet_addr *newip,
  87                      __be16 oldport, __be16 newport)
  88 {
  89 #ifdef CONFIG_IP_VS_IPV6
  90         if (af == AF_INET6)
  91                 uhdr->check =
  92                         csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
  93                                          ip_vs_check_diff2(oldport, newport,
  94                                                 ~csum_unfold(uhdr->check))));
  95         else
  96 #endif
  97                 uhdr->check =
  98                         csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
  99                                          ip_vs_check_diff2(oldport, newport,
 100                                                 ~csum_unfold(uhdr->check))));
 101         if (!uhdr->check)
 102                 uhdr->check = CSUM_MANGLED_0;
 103 }
 104
 105 static inline void
 106 udp_partial_csum_update(int af, struct udphdr *uhdr,
 107                      const union nf_inet_addr *oldip,
 108                      const union nf_inet_addr *newip,
 109                      __be16 oldlen, __be16 newlen)
 110 {
 111 #ifdef CONFIG_IP_VS_IPV6
 112         if (af == AF_INET6)
 113                 uhdr->check =
 114                         ~csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
 115                                          ip_vs_check_diff2(oldlen, newlen,
 116                                                 csum_unfold(uhdr->check))));
 117         else
 118 #endif
 119         uhdr->check =
 120                 ~csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
 121                                 ip_vs_check_diff2(oldlen, newlen,
 122                                                 csum_unfold(uhdr->check))));
 123 }
 124
 125
 126 static int
 127 udp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
 128                  struct ip_vs_conn *cp, struct ip_vs_iphdr *iph)
 129 {
 130         struct udphdr *udph;
 131         unsigned int udphoff = iph->len;
 132         int oldlen;
 133         int payload_csum = 0;
 134
 135 #ifdef CONFIG_IP_VS_IPV6
 136         if (cp->af == AF_INET6 && iph->fragoffs)
 137                 return 1;
 138 #endif
 139         oldlen = skb->len - udphoff;
 140
 141         /* csum_check requires unshared skb */
 142         if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
 143                 return 0;
 144
 145         if (unlikely(cp->app != NULL)) {
 146                 int ret;
 147
 148                 /* Some checks before mangling */
 149                 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
 150                         return 0;
 151
 152                 /*
 153                  *      Call application helper if needed
 154                  */
 155                 if (!(ret = ip_vs_app_pkt_out(cp, skb)))
 156                         return 0;
 157                 /* ret=2: csum update is needed after payload mangling */
 158                 if (ret == 1)
 159                         oldlen = skb->len - udphoff;
 160                 else
 161                         payload_csum = 1;
 162         }
 163
 164         udph = (void *)skb_network_header(skb) + udphoff;
 165         udph->source = cp->vport;
 166
 167         /*
 168          *      Adjust UDP checksums
 169          */
 170         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 171                 udp_partial_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
 172                                         htons(oldlen),
 173                                         htons(skb->len - udphoff));
 174         } else if (!payload_csum && (udph->check != 0)) {
 175                 /* Only port and addr are changed, do fast csum update */
 176                 udp_fast_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
 177                                      cp->dport, cp->vport);
 178                 if (skb->ip_summed == CHECKSUM_COMPLETE)
 179                         skb->ip_summed = (cp->app && pp->csum_check) ?
 180                                          CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
 181         } else {
 182                 /* full checksum calculation */
 183                 udph->check = 0;
 184                 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
 185 #ifdef CONFIG_IP_VS_IPV6
 186                 if (cp->af == AF_INET6)
 187                         udph->check = csum_ipv6_magic(&cp->vaddr.in6,
 188                                                       &cp->caddr.in6,
 189                                                       skb->len - udphoff,
 190                                                       cp->protocol, skb->csum);
 191                 else
 192 #endif
 193                         udph->check = csum_tcpudp_magic(cp->vaddr.ip,
 194                                                         cp->caddr.ip,
 195                                                         skb->len - udphoff,
 196                                                         cp->protocol,
 197                                                         skb->csum);
 198                 if (udph->check == 0)
 199                         udph->check = CSUM_MANGLED_0;
 200                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 201                 IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
 202                           pp->name, udph->check,
 203                           (char*)&(udph->check) - (char*)udph);
 204         }
 205         return 1;
 206 }
 207
 208
 209 static int
 210 udp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
 211                  struct ip_vs_conn *cp, struct ip_vs_iphdr *iph)
 212 {
 213         struct udphdr *udph;
 214         unsigned int udphoff = iph->len;
 215         int oldlen;
 216         int payload_csum = 0;
 217
 218 #ifdef CONFIG_IP_VS_IPV6
 219         if (cp->af == AF_INET6 && iph->fragoffs)
 220                 return 1;
 221 #endif
 222         oldlen = skb->len - udphoff;
 223
 224         /* csum_check requires unshared skb */
 225         if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
 226                 return 0;
 227
 228         if (unlikely(cp->app != NULL)) {
 229                 int ret;
 230
 231                 /* Some checks before mangling */
 232                 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
 233                         return 0;
 234
 235                 /*
 236                  *      Attempt ip_vs_app call.
 237                  *      It will fix ip_vs_conn
 238                  */
 239                 if (!(ret = ip_vs_app_pkt_in(cp, skb)))
 240                         return 0;
 241                 /* ret=2: csum update is needed after payload mangling */
 242                 if (ret == 1)
 243                         oldlen = skb->len - udphoff;
 244                 else
 245                         payload_csum = 1;
 246         }
 247
 248         udph = (void *)skb_network_header(skb) + udphoff;
 249         udph->dest = cp->dport;
 250
 251         /*
 252          *      Adjust UDP checksums
 253          */
 254         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 255                 udp_partial_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
 256                                         htons(oldlen),
 257                                         htons(skb->len - udphoff));
 258         } else if (!payload_csum && (udph->check != 0)) {
 259                 /* Only port and addr are changed, do fast csum update */
 260                 udp_fast_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
 261                                      cp->vport, cp->dport);
 262                 if (skb->ip_summed == CHECKSUM_COMPLETE)
 263                         skb->ip_summed = (cp->app && pp->csum_check) ?
 264                                          CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
 265         } else {
 266                 /* full checksum calculation */
 267                 udph->check = 0;
 268                 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
 269 #ifdef CONFIG_IP_VS_IPV6
 270                 if (cp->af == AF_INET6)
 271                         udph->check = csum_ipv6_magic(&cp->caddr.in6,
 272                                                       &cp->daddr.in6,
 273                                                       skb->len - udphoff,
 274                                                       cp->protocol, skb->csum);
 275                 else
 276 #endif
 277                         udph->check = csum_tcpudp_magic(cp->caddr.ip,
 278                                                         cp->daddr.ip,
 279                                                         skb->len - udphoff,
 280                                                         cp->protocol,
 281                                                         skb->csum);
 282                 if (udph->check == 0)
 283                         udph->check = CSUM_MANGLED_0;
 284                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 285         }
 286         return 1;
 287 }
 288
 289
 290 static int
 291 udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
 292 {
 293         struct udphdr _udph, *uh;
 294         unsigned int udphoff;
 295
 296 #ifdef CONFIG_IP_VS_IPV6
 297         if (af == AF_INET6)
 298                 udphoff = sizeof(struct ipv6hdr);
 299         else
 300 #endif
 301                 udphoff = ip_hdrlen(skb);
 302
 303         uh = skb_header_pointer(skb, udphoff, sizeof(_udph), &_udph);
 304         if (uh == NULL)
 305                 return 0;
 306
 307         if (uh->check != 0) {
 308                 switch (skb->ip_summed) {
 309                 case CHECKSUM_NONE:
 310                         skb->csum = skb_checksum(skb, udphoff,
 311                                                  skb->len - udphoff, 0);
 312                 case CHECKSUM_COMPLETE:
 313 #ifdef CONFIG_IP_VS_IPV6
 314                         if (af == AF_INET6) {
 315                                 if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
 316                                                     &ipv6_hdr(skb)->daddr,
 317                                                     skb->len - udphoff,
 318                                                     ipv6_hdr(skb)->nexthdr,
 319                                                     skb->csum)) {
 320                                         IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
 321                                                          "Failed checksum for");
 322                                         return 0;
 323                                 }
 324                         } else
 325 #endif
 326                                 if (csum_tcpudp_magic(ip_hdr(skb)->saddr,
 327                                                       ip_hdr(skb)->daddr,
 328                                                       skb->len - udphoff,
 329                                                       ip_hdr(skb)->protocol,
 330                                                       skb->csum)) {
 331                                         IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
 332                                                          "Failed checksum for");
 333                                         return 0;
 334                                 }
 335                         break;
 336                 default:
 337                         /* No need to checksum. */
 338                         break;
 339                 }
 340         }
 341         return 1;
 342 }
 343
 344 static inline __u16 udp_app_hashkey(__be16 port)
 345 {
 346         return (((__force u16)port >> UDP_APP_TAB_BITS) ^ (__force u16)port)
 347                 & UDP_APP_TAB_MASK;
 348 }
 349
 350
 351 static int udp_register_app(struct net *net, struct ip_vs_app *inc)
 352 {
 353         struct ip_vs_app *i;
 354         __u16 hash;
 355         __be16 port = inc->port;
 356         int ret = 0;
 357         struct netns_ipvs *ipvs = net_ipvs(net);
 358         struct ip_vs_proto_data *pd = ip_vs_proto_data_get(net, IPPROTO_UDP);
 359
 360         hash = udp_app_hashkey(port);
 361
 362         list_for_each_entry(i, &ipvs->udp_apps[hash], p_list) {
 363                 if (i->port == port) {
 364                         ret = -EEXIST;
 365                         goto out;
 366                 }
 367         }
 368         list_add_rcu(&inc->p_list, &ipvs->udp_apps[hash]);
 369         atomic_inc(&pd->appcnt);
 370
 371   out:
 372         return ret;
 373 }
 374
 375
 376 static void
 377 udp_unregister_app(struct net *net, struct ip_vs_app *inc)
 378 {
 379         struct ip_vs_proto_data *pd = ip_vs_proto_data_get(net, IPPROTO_UDP);
 380
 381         atomic_dec(&pd->appcnt);
 382         list_del_rcu(&inc->p_list);
 383 }
 384
 385
 386 static int udp_app_conn_bind(struct ip_vs_conn *cp)
 387 {
 388         struct netns_ipvs *ipvs = net_ipvs(ip_vs_conn_net(cp));
 389         int hash;
 390         struct ip_vs_app *inc;
 391         int result = 0;
 392
 393         /* Default binding: bind app only for NAT */
 394         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
 395                 return 0;
 396
 397         /* Lookup application incarnations and bind the right one */
 398         hash = udp_app_hashkey(cp->vport);
 399
 400         rcu_read_lock();
 401         list_for_each_entry_rcu(inc, &ipvs->udp_apps[hash], p_list) {
 402                 if (inc->port == cp->vport) {
 403                         if (unlikely(!ip_vs_app_inc_get(inc)))
 404                                 break;
 405                         rcu_read_unlock();
 406
 407                         IP_VS_DBG_BUF(9, "%s(): Binding conn %s:%u->"
 408                                       "%s:%u to app %s on port %u\n",
 409                                       __func__,
 410                                       IP_VS_DBG_ADDR(cp->af, &cp->caddr),
 411                                       ntohs(cp->cport),
 412                                       IP_VS_DBG_ADDR(cp->af, &cp->vaddr),
 413                                       ntohs(cp->vport),
 414                                       inc->name, ntohs(inc->port));
 415
 416                         cp->app = inc;
 417                         if (inc->init_conn)
 418                                 result = inc->init_conn(inc, cp);
 419                         goto out;
 420                 }
 421         }
 422         rcu_read_unlock();
 423
 424   out:
 425         return result;
 426 }
 427
 428
 429 static const int udp_timeouts[IP_VS_UDP_S_LAST+1] = {
 430         [IP_VS_UDP_S_NORMAL]            =       5*60*HZ,
 431         [IP_VS_UDP_S_LAST]              =       2*HZ,
 432 };
 433
 434 static const char *const udp_state_name_table[IP_VS_UDP_S_LAST+1] = {
 435         [IP_VS_UDP_S_NORMAL]            =       "UDP",
 436         [IP_VS_UDP_S_LAST]              =       "BUG!",
 437 };
 438
 439 static const char * udp_state_name(int state)
 440 {
 441         if (state >= IP_VS_UDP_S_LAST)
 442                 return "ERR!";
 443         return udp_state_name_table[state] ? udp_state_name_table[state] : "?";
 444 }
 445
 446 static void
 447 udp_state_transition(struct ip_vs_conn *cp, int direction,
 448                      const struct sk_buff *skb,
 449                      struct ip_vs_proto_data *pd)
 450 {
 451         if (unlikely(!pd)) {
 452                 pr_err("UDP no ns data\n");
 453                 return;
 454         }
 455
 456         cp->timeout = pd->timeout_table[IP_VS_UDP_S_NORMAL];
 457 }
 458
 459 static int __udp_init(struct net *net, struct ip_vs_proto_data *pd)
 460 {
 461         struct netns_ipvs *ipvs = net_ipvs(net);
 462
 463         ip_vs_init_hash_table(ipvs->udp_apps, UDP_APP_TAB_SIZE);
 464         pd->timeout_table = ip_vs_create_timeout_table((int *)udp_timeouts,
 465                                                         sizeof(udp_timeouts));
 466         if (!pd->timeout_table)
 467                 return -ENOMEM;
 468         return 0;
 469 }
 470
 471 static void __udp_exit(struct net *net, struct ip_vs_proto_data *pd)
 472 {
 473         kfree(pd->timeout_table);
 474 }
 475
 476
 477 struct ip_vs_protocol ip_vs_protocol_udp = {
 478         .name =                 "UDP",
 479         .protocol =             IPPROTO_UDP,
 480         .num_states =           IP_VS_UDP_S_LAST,
 481         .dont_defrag =          0,
 482         .init =                 NULL,
 483         .exit =                 NULL,
 484         .init_netns =           __udp_init,
 485         .exit_netns =           __udp_exit,
 486         .conn_schedule =        udp_conn_schedule,
 487         .conn_in_get =          ip_vs_conn_in_get_proto,
 488         .conn_out_get =         ip_vs_conn_out_get_proto,
 489         .snat_handler =         udp_snat_handler,
 490         .dnat_handler =         udp_dnat_handler,
 491         .csum_check =           udp_csum_check,
 492         .state_transition =     udp_state_transition,
 493         .state_name =           udp_state_name,
 494         .register_app =         udp_register_app,
 495         .unregister_app =       udp_unregister_app,
 496         .app_conn_bind =        udp_app_conn_bind,
 497         .debug_packet =         ip_vs_tcpudp_debug_packet,
 498         .timeout_change =       NULL,
 499 };