net/core/netfilter.c

   1 /* netfilter.c: look after the filters for various protocols.
   2  * Heavily influenced by the old firewall.c by David Bonn and Alan Cox.
   3  *
   4  * Thanks to Rob `CmdrTaco' Malda for not influencing this code in any
   5  * way.
   6  *
   7  * Rusty Russell (C)2000 -- This code is GPL.
   8  *
   9  * February 2000: Modified by James Morris to have 1 queue per protocol.
  10  * 15-Mar-2000:   Added NF_REPEAT --RR.
  11  * 08-May-2003:   Internal logging interface added by Jozsef Kadlecsik.
  12  */
  13 #include <linux/config.h>
  14 #include <linux/kernel.h>
  15 #include <linux/netfilter.h>
  16 #include <net/protocol.h>
  17 #include <linux/init.h>
  18 #include <linux/skbuff.h>
  19 #include <linux/wait.h>
  20 #include <linux/module.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/if.h>
  23 #include <linux/netdevice.h>
  24 #include <linux/inetdevice.h>
  25 #include <linux/tcp.h>
  26 #include <linux/udp.h>
  27 #include <linux/icmp.h>
  28 #include <net/sock.h>
  29 #include <net/route.h>
  30 #include <linux/ip.h>
  31
  32 /* In this code, we can be waiting indefinitely for userspace to
  33  * service a packet if a hook returns NF_QUEUE.  We could keep a count
  34  * of skbuffs queued for userspace, and not deregister a hook unless
  35  * this is zero, but that sucks.  Now, we simply check when the
  36  * packets come back: if the hook is gone, the packet is discarded. */
  37 #ifdef CONFIG_NETFILTER_DEBUG
  38 #define NFDEBUG(format, args...)  printk(format , ## args)
  39 #else
  40 #define NFDEBUG(format, args...)
  41 #endif
  42
  43 /* Sockopts only registered and called from user context, so
  44    net locking would be overkill.  Also, [gs]etsockopt calls may
  45    sleep. */
  46 static DECLARE_MUTEX(nf_sockopt_mutex);
  47
  48 struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
  49 static LIST_HEAD(nf_sockopts);
  50 static DEFINE_SPINLOCK(nf_hook_lock);
  51
  52 /*
  53  * A queue handler may be registered for each protocol.  Each is protected by
  54  * long term mutex.  The handler must provide an an outfn() to accept packets
  55  * for queueing and must reinject all packets it receives, no matter what.
  56  */
  57 static struct nf_queue_handler_t {
  58         nf_queue_outfn_t outfn;
  59         void *data;
  60 } queue_handler[NPROTO];
  61 static DEFINE_RWLOCK(queue_handler_lock);
  62
  63 int nf_register_hook(struct nf_hook_ops *reg)
  64 {
  65         struct list_head *i;
  66
  67         spin_lock_bh(&nf_hook_lock);
  68         list_for_each(i, &nf_hooks[reg->pf][reg->hooknum]) {
  69                 if (reg->priority < ((struct nf_hook_ops *)i)->priority)
  70                         break;
  71         }
  72         list_add_rcu(&reg->list, i->prev);
  73         spin_unlock_bh(&nf_hook_lock);
  74
  75         synchronize_net();
  76         return 0;
  77 }
  78
  79 void nf_unregister_hook(struct nf_hook_ops *reg)
  80 {
  81         spin_lock_bh(&nf_hook_lock);
  82         list_del_rcu(&reg->list);
  83         spin_unlock_bh(&nf_hook_lock);
  84
  85         synchronize_net();
  86 }
  87
  88 /* Do exclusive ranges overlap? */
  89 static inline int overlap(int min1, int max1, int min2, int max2)
  90 {
  91         return max1 > min2 && min1 < max2;
  92 }
  93
  94 /* Functions to register sockopt ranges (exclusive). */
  95 int nf_register_sockopt(struct nf_sockopt_ops *reg)
  96 {
  97         struct list_head *i;
  98         int ret = 0;
  99
 100         if (down_interruptible(&nf_sockopt_mutex) != 0)
 101                 return -EINTR;
 102
 103         list_for_each(i, &nf_sockopts) {
 104                 struct nf_sockopt_ops *ops = (struct nf_sockopt_ops *)i;
 105                 if (ops->pf == reg->pf
 106                     && (overlap(ops->set_optmin, ops->set_optmax,
 107                                 reg->set_optmin, reg->set_optmax)
 108                         || overlap(ops->get_optmin, ops->get_optmax,
 109                                    reg->get_optmin, reg->get_optmax))) {
 110                         NFDEBUG("nf_sock overlap: %u-%u/%u-%u v %u-%u/%u-%u\n",
 111                                 ops->set_optmin, ops->set_optmax,
 112                                 ops->get_optmin, ops->get_optmax,
 113                                 reg->set_optmin, reg->set_optmax,
 114                                 reg->get_optmin, reg->get_optmax);
 115                         ret = -EBUSY;
 116                         goto out;
 117                 }
 118         }
 119
 120         list_add(&reg->list, &nf_sockopts);
 121 out:
 122         up(&nf_sockopt_mutex);
 123         return ret;
 124 }
 125
 126 void nf_unregister_sockopt(struct nf_sockopt_ops *reg)
 127 {
 128         /* No point being interruptible: we're probably in cleanup_module() */
 129  restart:
 130         down(&nf_sockopt_mutex);
 131         if (reg->use != 0) {
 132                 /* To be woken by nf_sockopt call... */
 133                 /* FIXME: Stuart Young's name appears gratuitously. */
 134                 set_current_state(TASK_UNINTERRUPTIBLE);
 135                 reg->cleanup_task = current;
 136                 up(&nf_sockopt_mutex);
 137                 schedule();
 138                 goto restart;
 139         }
 140         list_del(&reg->list);
 141         up(&nf_sockopt_mutex);
 142 }
 143
 144 #ifdef CONFIG_NETFILTER_DEBUG
 145 #include <net/ip.h>
 146 #include <net/tcp.h>
 147 #include <linux/netfilter_ipv4.h>
 148
 149 static void debug_print_hooks_ip(unsigned int nf_debug)
 150 {
 151         if (nf_debug & (1 << NF_IP_PRE_ROUTING)) {
 152                 printk("PRE_ROUTING ");
 153                 nf_debug ^= (1 << NF_IP_PRE_ROUTING);
 154         }
 155         if (nf_debug & (1 << NF_IP_LOCAL_IN)) {
 156                 printk("LOCAL_IN ");
 157                 nf_debug ^= (1 << NF_IP_LOCAL_IN);
 158         }
 159         if (nf_debug & (1 << NF_IP_FORWARD)) {
 160                 printk("FORWARD ");
 161                 nf_debug ^= (1 << NF_IP_FORWARD);
 162         }
 163         if (nf_debug & (1 << NF_IP_LOCAL_OUT)) {
 164                 printk("LOCAL_OUT ");
 165                 nf_debug ^= (1 << NF_IP_LOCAL_OUT);
 166         }
 167         if (nf_debug & (1 << NF_IP_POST_ROUTING)) {
 168                 printk("POST_ROUTING ");
 169                 nf_debug ^= (1 << NF_IP_POST_ROUTING);
 170         }
 171         if (nf_debug)
 172                 printk("Crap bits: 0x%04X", nf_debug);
 173         printk("\n");
 174 }
 175
 176 static void nf_dump_skb(int pf, struct sk_buff *skb)
 177 {
 178         printk("skb: pf=%i %s dev=%s len=%u\n",
 179                pf,
 180                skb->sk ? "(owned)" : "(unowned)",
 181                skb->dev ? skb->dev->name : "(no dev)",
 182                skb->len);
 183         switch (pf) {
 184         case PF_INET: {
 185                 const struct iphdr *ip = skb->nh.iph;
 186                 __u32 *opt = (__u32 *) (ip + 1);
 187                 int opti;
 188                 __u16 src_port = 0, dst_port = 0;
 189
 190                 if (ip->protocol == IPPROTO_TCP
 191                     || ip->protocol == IPPROTO_UDP) {
 192                         struct tcphdr *tcp=(struct tcphdr *)((__u32 *)ip+ip->ihl);
 193                         src_port = ntohs(tcp->source);
 194                         dst_port = ntohs(tcp->dest);
 195                 }
 196
 197                 printk("PROTO=%d %u.%u.%u.%u:%hu %u.%u.%u.%u:%hu"
 198                        " L=%hu S=0x%2.2hX I=%hu F=0x%4.4hX T=%hu",
 199                        ip->protocol, NIPQUAD(ip->saddr),
 200                        src_port, NIPQUAD(ip->daddr),
 201                        dst_port,
 202                        ntohs(ip->tot_len), ip->tos, ntohs(ip->id),
 203                        ntohs(ip->frag_off), ip->ttl);
 204
 205                 for (opti = 0; opti < (ip->ihl - sizeof(struct iphdr) / 4); opti++)
 206                         printk(" O=0x%8.8X", *opt++);
 207                 printk(" MARK=%lu (0x%lu)",
 208                        (long unsigned int)skb->nfmark,
 209                        (long unsigned int)skb->nfmark);
 210                 printk("\n");
 211         }
 212         }
 213 }
 214
 215 void nf_debug_ip_local_deliver(struct sk_buff *skb)
 216 {
 217         /* If it's a loopback packet, it must have come through
 218          * NF_IP_LOCAL_OUT, NF_IP_RAW_INPUT, NF_IP_PRE_ROUTING and
 219          * NF_IP_LOCAL_IN.  Otherwise, must have gone through
 220          * NF_IP_RAW_INPUT and NF_IP_PRE_ROUTING.  */
 221         if (!skb->dev) {
 222                 printk("ip_local_deliver: skb->dev is NULL.\n");
 223         } else {
 224                 if (skb->nf_debug != ((1<<NF_IP_PRE_ROUTING)
 225                                       | (1<<NF_IP_LOCAL_IN))) {
 226                         printk("ip_local_deliver: bad skb: ");
 227                         debug_print_hooks_ip(skb->nf_debug);
 228                         nf_dump_skb(PF_INET, skb);
 229                 }
 230         }
 231 }
 232
 233 void nf_debug_ip_loopback_xmit(struct sk_buff *newskb)
 234 {
 235         if (newskb->nf_debug != ((1 << NF_IP_LOCAL_OUT)
 236                                  | (1 << NF_IP_POST_ROUTING))) {
 237                 printk("ip_dev_loopback_xmit: bad owned skb = %p: ",
 238                        newskb);
 239                 debug_print_hooks_ip(newskb->nf_debug);
 240                 nf_dump_skb(PF_INET, newskb);
 241         }
 242 }
 243
 244 void nf_debug_ip_finish_output2(struct sk_buff *skb)
 245 {
 246         /* If it's owned, it must have gone through the
 247          * NF_IP_LOCAL_OUT and NF_IP_POST_ROUTING.
 248          * Otherwise, must have gone through
 249          * NF_IP_PRE_ROUTING, NF_IP_FORWARD and NF_IP_POST_ROUTING.
 250          */
 251         if (skb->sk) {
 252                 if (skb->nf_debug != ((1 << NF_IP_LOCAL_OUT)
 253                                       | (1 << NF_IP_POST_ROUTING))) {
 254                         printk("ip_finish_output: bad owned skb = %p: ", skb);
 255                         debug_print_hooks_ip(skb->nf_debug);
 256                         nf_dump_skb(PF_INET, skb);
 257                 }
 258         } else {
 259                 if (skb->nf_debug != ((1 << NF_IP_PRE_ROUTING)
 260                                       | (1 << NF_IP_FORWARD)
 261                                       | (1 << NF_IP_POST_ROUTING))) {
 262                         /* Fragments, entunnelled packets, TCP RSTs
 263                            generated by ipt_REJECT will have no
 264                            owners, but still may be local */
 265                         if (skb->nf_debug != ((1 << NF_IP_LOCAL_OUT)
 266                                               | (1 << NF_IP_POST_ROUTING))){
 267                                 printk("ip_finish_output:"
 268                                        " bad unowned skb = %p: ",skb);
 269                                 debug_print_hooks_ip(skb->nf_debug);
 270                                 nf_dump_skb(PF_INET, skb);
 271                         }
 272                 }
 273         }
 274 }
 275 #endif /*CONFIG_NETFILTER_DEBUG*/
 276
 277 /* Call get/setsockopt() */
 278 static int nf_sockopt(struct sock *sk, int pf, int val,
 279                       char __user *opt, int *len, int get)
 280 {
 281         struct list_head *i;
 282         struct nf_sockopt_ops *ops;
 283         int ret;
 284
 285         if (down_interruptible(&nf_sockopt_mutex) != 0)
 286                 return -EINTR;
 287
 288         list_for_each(i, &nf_sockopts) {
 289                 ops = (struct nf_sockopt_ops *)i;
 290                 if (ops->pf == pf) {
 291                         if (get) {
 292                                 if (val >= ops->get_optmin
 293                                     && val < ops->get_optmax) {
 294                                         ops->use++;
 295                                         up(&nf_sockopt_mutex);
 296                                         ret = ops->get(sk, val, opt, len);
 297                                         goto out;
 298                                 }
 299                         } else {
 300                                 if (val >= ops->set_optmin
 301                                     && val < ops->set_optmax) {
 302                                         ops->use++;
 303                                         up(&nf_sockopt_mutex);
 304                                         ret = ops->set(sk, val, opt, *len);
 305                                         goto out;
 306                                 }
 307                         }
 308                 }
 309         }
 310         up(&nf_sockopt_mutex);
 311         return -ENOPROTOOPT;
 312
 313  out:
 314         down(&nf_sockopt_mutex);
 315         ops->use--;
 316         if (ops->cleanup_task)
 317                 wake_up_process(ops->cleanup_task);
 318         up(&nf_sockopt_mutex);
 319         return ret;
 320 }
 321
 322 int nf_setsockopt(struct sock *sk, int pf, int val, char __user *opt,
 323                   int len)
 324 {
 325         return nf_sockopt(sk, pf, val, opt, &len, 0);
 326 }
 327
 328 int nf_getsockopt(struct sock *sk, int pf, int val, char __user *opt, int *len)
 329 {
 330         return nf_sockopt(sk, pf, val, opt, len, 1);
 331 }
 332
 333 static unsigned int nf_iterate(struct list_head *head,
 334                                struct sk_buff **skb,
 335                                int hook,
 336                                const struct net_device *indev,
 337                                const struct net_device *outdev,
 338                                struct list_head **i,
 339                                int (*okfn)(struct sk_buff *),
 340                                int hook_thresh)
 341 {
 342         unsigned int verdict;
 343
 344         /*
 345          * The caller must not block between calls to this
 346          * function because of risk of continuing from deleted element.
 347          */
 348         list_for_each_continue_rcu(*i, head) {
 349                 struct nf_hook_ops *elem = (struct nf_hook_ops *)*i;
 350
 351                 if (hook_thresh > elem->priority)
 352                         continue;
 353
 354                 /* Optimization: we don't need to hold module
 355                    reference here, since function can't sleep. --RR */
 356                 verdict = elem->hook(hook, skb, indev, outdev, okfn);
 357                 if (verdict != NF_ACCEPT) {
 358 #ifdef CONFIG_NETFILTER_DEBUG
 359                         if (unlikely(verdict > NF_MAX_VERDICT)) {
 360                                 NFDEBUG("Evil return from %p(%u).\n",
 361                                         elem->hook, hook);
 362                                 continue;
 363                         }
 364 #endif
 365                         if (verdict != NF_REPEAT)
 366                                 return verdict;
 367                         *i = (*i)->prev;
 368                 }
 369         }
 370         return NF_ACCEPT;
 371 }
 372
 373 int nf_register_queue_handler(int pf, nf_queue_outfn_t outfn, void *data)
 374 {
 375         int ret;
 376
 377         write_lock_bh(&queue_handler_lock);
 378         if (queue_handler[pf].outfn)
 379                 ret = -EBUSY;
 380         else {
 381                 queue_handler[pf].outfn = outfn;
 382                 queue_handler[pf].data = data;
 383                 ret = 0;
 384         }
 385         write_unlock_bh(&queue_handler_lock);
 386
 387         return ret;
 388 }
 389
 390 /* The caller must flush their queue before this */
 391 int nf_unregister_queue_handler(int pf)
 392 {
 393         write_lock_bh(&queue_handler_lock);
 394         queue_handler[pf].outfn = NULL;
 395         queue_handler[pf].data = NULL;
 396         write_unlock_bh(&queue_handler_lock);
 397
 398         return 0;
 399 }
 400
 401 /*
 402  * Any packet that leaves via this function must come back
 403  * through nf_reinject().
 404  */
 405 static int nf_queue(struct sk_buff *skb,
 406                     struct list_head *elem,
 407                     int pf, unsigned int hook,
 408                     struct net_device *indev,
 409                     struct net_device *outdev,
 410                     int (*okfn)(struct sk_buff *))
 411 {
 412         int status;
 413         struct nf_info *info;
 414 #ifdef CONFIG_BRIDGE_NETFILTER
 415         struct net_device *physindev = NULL;
 416         struct net_device *physoutdev = NULL;
 417 #endif
 418
 419         /* QUEUE == DROP if noone is waiting, to be safe. */
 420         read_lock(&queue_handler_lock);
 421         if (!queue_handler[pf].outfn) {
 422                 read_unlock(&queue_handler_lock);
 423                 kfree_skb(skb);
 424                 return 1;
 425         }
 426
 427         info = kmalloc(sizeof(*info), GFP_ATOMIC);
 428         if (!info) {
 429                 if (net_ratelimit())
 430                         printk(KERN_ERR "OOM queueing packet %p\n",
 431                                skb);
 432                 read_unlock(&queue_handler_lock);
 433                 kfree_skb(skb);
 434                 return 1;
 435         }
 436
 437         *info = (struct nf_info) {
 438                 (struct nf_hook_ops *)elem, pf, hook, indev, outdev, okfn };
 439
 440         /* If it's going away, ignore hook. */
 441         if (!try_module_get(info->elem->owner)) {
 442                 read_unlock(&queue_handler_lock);
 443                 kfree(info);
 444                 return 0;
 445         }
 446
 447         /* Bump dev refs so they don't vanish while packet is out */
 448         if (indev) dev_hold(indev);
 449         if (outdev) dev_hold(outdev);
 450
 451 #ifdef CONFIG_BRIDGE_NETFILTER
 452         if (skb->nf_bridge) {
 453                 physindev = skb->nf_bridge->physindev;
 454                 if (physindev) dev_hold(physindev);
 455                 physoutdev = skb->nf_bridge->physoutdev;
 456                 if (physoutdev) dev_hold(physoutdev);
 457         }
 458 #endif
 459
 460         status = queue_handler[pf].outfn(skb, info, queue_handler[pf].data);
 461         read_unlock(&queue_handler_lock);
 462
 463         if (status < 0) {
 464                 /* James M doesn't say fuck enough. */
 465                 if (indev) dev_put(indev);
 466                 if (outdev) dev_put(outdev);
 467 #ifdef CONFIG_BRIDGE_NETFILTER
 468                 if (physindev) dev_put(physindev);
 469                 if (physoutdev) dev_put(physoutdev);
 470 #endif
 471                 module_put(info->elem->owner);
 472                 kfree(info);
 473                 kfree_skb(skb);
 474                 return 1;
 475         }
 476         return 1;
 477 }
 478
 479 /* Returns 1 if okfn() needs to be executed by the caller,
 480  * -EPERM for NF_DROP, 0 otherwise. */
 481 int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb,
 482                  struct net_device *indev,
 483                  struct net_device *outdev,
 484                  int (*okfn)(struct sk_buff *),
 485                  int hook_thresh)
 486 {
 487         struct list_head *elem;
 488         unsigned int verdict;
 489         int ret = 0;
 490
 491         /* We may already have this, but read-locks nest anyway */
 492         rcu_read_lock();
 493
 494 #ifdef CONFIG_NETFILTER_DEBUG
 495         if (unlikely((*pskb)->nf_debug & (1 << hook))) {
 496                 printk("nf_hook: hook %i already set.\n", hook);
 497                 nf_dump_skb(pf, *pskb);
 498         }
 499         (*pskb)->nf_debug |= (1 << hook);
 500 #endif
 501
 502         elem = &nf_hooks[pf][hook];
 503 next_hook:
 504         verdict = nf_iterate(&nf_hooks[pf][hook], pskb, hook, indev,
 505                              outdev, &elem, okfn, hook_thresh);
 506         if (verdict == NF_ACCEPT || verdict == NF_STOP) {
 507                 ret = 1;
 508                 goto unlock;
 509         } else if (verdict == NF_DROP) {
 510                 kfree_skb(*pskb);
 511                 ret = -EPERM;
 512         } else if (verdict == NF_QUEUE) {
 513                 NFDEBUG("nf_hook: Verdict = QUEUE.\n");
 514                 if (!nf_queue(*pskb, elem, pf, hook, indev, outdev, okfn))
 515                         goto next_hook;
 516         }
 517 unlock:
 518         rcu_read_unlock();
 519         return ret;
 520 }
 521
 522 void nf_reinject(struct sk_buff *skb, struct nf_info *info,
 523                  unsigned int verdict)
 524 {
 525         struct list_head *elem = &info->elem->list;
 526         struct list_head *i;
 527
 528         rcu_read_lock();
 529
 530         /* Release those devices we held, or Alexey will kill me. */
 531         if (info->indev) dev_put(info->indev);
 532         if (info->outdev) dev_put(info->outdev);
 533 #ifdef CONFIG_BRIDGE_NETFILTER
 534         if (skb->nf_bridge) {
 535                 if (skb->nf_bridge->physindev)
 536                         dev_put(skb->nf_bridge->physindev);
 537                 if (skb->nf_bridge->physoutdev)
 538                         dev_put(skb->nf_bridge->physoutdev);
 539         }
 540 #endif
 541
 542         /* Drop reference to owner of hook which queued us. */
 543         module_put(info->elem->owner);
 544
 545         list_for_each_rcu(i, &nf_hooks[info->pf][info->hook]) {
 546                 if (i == elem)
 547                         break;
 548         }
 549
 550         if (elem == &nf_hooks[info->pf][info->hook]) {
 551                 /* The module which sent it to userspace is gone. */
 552                 NFDEBUG("%s: module disappeared, dropping packet.\n",
 553                         __FUNCTION__);
 554                 verdict = NF_DROP;
 555         }
 556
 557         /* Continue traversal iff userspace said ok... */
 558         if (verdict == NF_REPEAT) {
 559                 elem = elem->prev;
 560                 verdict = NF_ACCEPT;
 561         }
 562
 563         if (verdict == NF_ACCEPT) {
 564         next_hook:
 565                 verdict = nf_iterate(&nf_hooks[info->pf][info->hook],
 566                                      &skb, info->hook,
 567                                      info->indev, info->outdev, &elem,
 568                                      info->okfn, INT_MIN);
 569         }
 570
 571         switch (verdict) {
 572         case NF_ACCEPT:
 573                 info->okfn(skb);
 574                 break;
 575
 576         case NF_QUEUE:
 577                 if (!nf_queue(skb, elem, info->pf, info->hook,
 578                               info->indev, info->outdev, info->okfn))
 579                         goto next_hook;
 580                 break;
 581         }
 582         rcu_read_unlock();
 583
 584         if (verdict == NF_DROP)
 585                 kfree_skb(skb);
 586
 587         kfree(info);
 588         return;
 589 }
 590
 591 #ifdef CONFIG_INET
 592 /* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
 593 int ip_route_me_harder(struct sk_buff **pskb)
 594 {
 595         struct iphdr *iph = (*pskb)->nh.iph;
 596         struct rtable *rt;
 597         struct flowi fl = {};
 598         struct dst_entry *odst;
 599         unsigned int hh_len;
 600
 601         /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
 602          * packets with foreign saddr to appear on the NF_IP_LOCAL_OUT hook.
 603          */
 604         if (inet_addr_type(iph->saddr) == RTN_LOCAL) {
 605                 fl.nl_u.ip4_u.daddr = iph->daddr;
 606                 fl.nl_u.ip4_u.saddr = iph->saddr;
 607                 fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
 608                 fl.oif = (*pskb)->sk ? (*pskb)->sk->sk_bound_dev_if : 0;
 609 #ifdef CONFIG_IP_ROUTE_FWMARK
 610                 fl.nl_u.ip4_u.fwmark = (*pskb)->nfmark;
 611 #endif
 612                 fl.proto = iph->protocol;
 613                 if (ip_route_output_key(&rt, &fl) != 0)
 614                         return -1;
 615
 616                 /* Drop old route. */
 617                 dst_release((*pskb)->dst);
 618                 (*pskb)->dst = &rt->u.dst;
 619         } else {
 620                 /* non-local src, find valid iif to satisfy
 621                  * rp-filter when calling ip_route_input. */
 622                 fl.nl_u.ip4_u.daddr = iph->saddr;
 623                 if (ip_route_output_key(&rt, &fl) != 0)
 624                         return -1;
 625
 626                 odst = (*pskb)->dst;
 627                 if (ip_route_input(*pskb, iph->daddr, iph->saddr,
 628                                    RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
 629                         dst_release(&rt->u.dst);
 630                         return -1;
 631                 }
 632                 dst_release(&rt->u.dst);
 633                 dst_release(odst);
 634         }
 635
 636         if ((*pskb)->dst->error)
 637                 return -1;
 638
 639         /* Change in oif may mean change in hh_len. */
 640         hh_len = (*pskb)->dst->dev->hard_header_len;
 641         if (skb_headroom(*pskb) < hh_len) {
 642                 struct sk_buff *nskb;
 643
 644                 nskb = skb_realloc_headroom(*pskb, hh_len);
 645                 if (!nskb)
 646                         return -1;
 647                 if ((*pskb)->sk)
 648                         skb_set_owner_w(nskb, (*pskb)->sk);
 649                 kfree_skb(*pskb);
 650                 *pskb = nskb;
 651         }
 652
 653         return 0;
 654 }
 655 EXPORT_SYMBOL(ip_route_me_harder);
 656
 657 int skb_ip_make_writable(struct sk_buff **pskb, unsigned int writable_len)
 658 {
 659         struct sk_buff *nskb;
 660
 661         if (writable_len > (*pskb)->len)
 662                 return 0;
 663
 664         /* Not exclusive use of packet?  Must copy. */
 665         if (skb_shared(*pskb) || skb_cloned(*pskb))
 666                 goto copy_skb;
 667
 668         return pskb_may_pull(*pskb, writable_len);
 669
 670 copy_skb:
 671         nskb = skb_copy(*pskb, GFP_ATOMIC);
 672         if (!nskb)
 673                 return 0;
 674         BUG_ON(skb_is_nonlinear(nskb));
 675
 676         /* Rest of kernel will get very unhappy if we pass it a
 677            suddenly-orphaned skbuff */
 678         if ((*pskb)->sk)
 679                 skb_set_owner_w(nskb, (*pskb)->sk);
 680         kfree_skb(*pskb);
 681         *pskb = nskb;
 682         return 1;
 683 }
 684 EXPORT_SYMBOL(skb_ip_make_writable);
 685 #endif /*CONFIG_INET*/
 686
 687 /* Internal logging interface, which relies on the real
 688    LOG target modules */
 689
 690 #define NF_LOG_PREFIXLEN                128
 691
 692 static nf_logfn *nf_logging[NPROTO]; /* = NULL */
 693 static int reported = 0;
 694 static DEFINE_SPINLOCK(nf_log_lock);
 695
 696 int nf_log_register(int pf, nf_logfn *logfn)
 697 {
 698         int ret = -EBUSY;
 699
 700         /* Any setup of logging members must be done before
 701          * substituting pointer. */
 702         spin_lock(&nf_log_lock);
 703         if (!nf_logging[pf]) {
 704                 rcu_assign_pointer(nf_logging[pf], logfn);
 705                 ret = 0;
 706         }
 707         spin_unlock(&nf_log_lock);
 708         return ret;
 709 }
 710
 711 void nf_log_unregister(int pf, nf_logfn *logfn)
 712 {
 713         spin_lock(&nf_log_lock);
 714         if (nf_logging[pf] == logfn)
 715                 nf_logging[pf] = NULL;
 716         spin_unlock(&nf_log_lock);
 717
 718         /* Give time to concurrent readers. */
 719         synchronize_net();
 720 }
 721
 722 void nf_log_packet(int pf,
 723                    unsigned int hooknum,
 724                    const struct sk_buff *skb,
 725                    const struct net_device *in,
 726                    const struct net_device *out,
 727                    const char *fmt, ...)
 728 {
 729         va_list args;
 730         char prefix[NF_LOG_PREFIXLEN];
 731         nf_logfn *logfn;
 732
 733         rcu_read_lock();
 734         logfn = rcu_dereference(nf_logging[pf]);
 735         if (logfn) {
 736                 va_start(args, fmt);
 737                 vsnprintf(prefix, sizeof(prefix), fmt, args);
 738                 va_end(args);
 739                 /* We must read logging before nf_logfn[pf] */
 740                 logfn(hooknum, skb, in, out, prefix);
 741         } else if (!reported) {
 742                 printk(KERN_WARNING "nf_log_packet: can\'t log yet, "
 743                        "no backend logging module loaded in!\n");
 744                 reported++;
 745         }
 746         rcu_read_unlock();
 747 }
 748 EXPORT_SYMBOL(nf_log_register);
 749 EXPORT_SYMBOL(nf_log_unregister);
 750 EXPORT_SYMBOL(nf_log_packet);
 751
 752 /* This does not belong here, but locally generated errors need it if connection
 753    tracking in use: without this, connection may not be in hash table, and hence
 754    manufactured ICMP or RST packets will not be associated with it. */
 755 void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
 756
 757 void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb)
 758 {
 759         void (*attach)(struct sk_buff *, struct sk_buff *);
 760
 761         if (skb->nfct && (attach = ip_ct_attach) != NULL) {
 762                 mb(); /* Just to be sure: must be read before executing this */
 763                 attach(new, skb);
 764         }
 765 }
 766
 767 void __init netfilter_init(void)
 768 {
 769         int i, h;
 770
 771         for (i = 0; i < NPROTO; i++) {
 772                 for (h = 0; h < NF_MAX_HOOKS; h++)
 773                         INIT_LIST_HEAD(&nf_hooks[i][h]);
 774         }
 775 }
 776
 777 EXPORT_SYMBOL(ip_ct_attach);
 778 EXPORT_SYMBOL(nf_ct_attach);
 779 EXPORT_SYMBOL(nf_getsockopt);
 780 EXPORT_SYMBOL(nf_hook_slow);
 781 EXPORT_SYMBOL(nf_hooks);
 782 EXPORT_SYMBOL(nf_register_hook);
 783 EXPORT_SYMBOL(nf_register_queue_handler);
 784 EXPORT_SYMBOL(nf_register_sockopt);
 785 EXPORT_SYMBOL(nf_reinject);
 786 EXPORT_SYMBOL(nf_setsockopt);
 787 EXPORT_SYMBOL(nf_unregister_hook);
 788 EXPORT_SYMBOL(nf_unregister_queue_handler);
 789 EXPORT_SYMBOL(nf_unregister_sockopt);
 790 #ifdef CONFIG_NETFILTER_DEBUG
 791 EXPORT_SYMBOL(nf_dump_skb);
 792 #endif