289 lines
7.2 KiB
C
289 lines
7.2 KiB
C
/* netfilter.c: look after the filters for various protocols.
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* Heavily influenced by the old firewall.c by David Bonn and Alan Cox.
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*
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* Thanks to Rob `CmdrTaco' Malda for not influencing this code in any
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* way.
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*
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* Rusty Russell (C)2000 -- This code is GPL.
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*
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* February 2000: Modified by James Morris to have 1 queue per protocol.
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* 15-Mar-2000: Added NF_REPEAT --RR.
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* 08-May-2003: Internal logging interface added by Jozsef Kadlecsik.
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*/
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#include <linux/kernel.h>
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#include <linux/netfilter.h>
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#include <net/protocol.h>
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#include <linux/init.h>
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#include <linux/skbuff.h>
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#include <linux/wait.h>
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/if.h>
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#include <linux/netdevice.h>
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#include <linux/inetdevice.h>
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#include <linux/proc_fs.h>
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#include <net/sock.h>
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#include "nf_internals.h"
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static DEFINE_SPINLOCK(afinfo_lock);
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struct nf_afinfo *nf_afinfo[NPROTO];
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EXPORT_SYMBOL(nf_afinfo);
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int nf_register_afinfo(struct nf_afinfo *afinfo)
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{
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spin_lock(&afinfo_lock);
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rcu_assign_pointer(nf_afinfo[afinfo->family], afinfo);
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spin_unlock(&afinfo_lock);
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return 0;
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}
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EXPORT_SYMBOL_GPL(nf_register_afinfo);
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void nf_unregister_afinfo(struct nf_afinfo *afinfo)
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{
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spin_lock(&afinfo_lock);
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rcu_assign_pointer(nf_afinfo[afinfo->family], NULL);
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spin_unlock(&afinfo_lock);
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synchronize_rcu();
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}
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EXPORT_SYMBOL_GPL(nf_unregister_afinfo);
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/* In this code, we can be waiting indefinitely for userspace to
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* service a packet if a hook returns NF_QUEUE. We could keep a count
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* of skbuffs queued for userspace, and not deregister a hook unless
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* this is zero, but that sucks. Now, we simply check when the
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* packets come back: if the hook is gone, the packet is discarded. */
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struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
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EXPORT_SYMBOL(nf_hooks);
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static DEFINE_SPINLOCK(nf_hook_lock);
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int nf_register_hook(struct nf_hook_ops *reg)
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{
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struct list_head *i;
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spin_lock_bh(&nf_hook_lock);
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list_for_each(i, &nf_hooks[reg->pf][reg->hooknum]) {
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if (reg->priority < ((struct nf_hook_ops *)i)->priority)
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break;
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}
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list_add_rcu(®->list, i->prev);
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spin_unlock_bh(&nf_hook_lock);
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synchronize_net();
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return 0;
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}
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EXPORT_SYMBOL(nf_register_hook);
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void nf_unregister_hook(struct nf_hook_ops *reg)
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{
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spin_lock_bh(&nf_hook_lock);
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list_del_rcu(®->list);
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spin_unlock_bh(&nf_hook_lock);
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synchronize_net();
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}
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EXPORT_SYMBOL(nf_unregister_hook);
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int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n)
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{
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unsigned int i;
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int err = 0;
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for (i = 0; i < n; i++) {
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err = nf_register_hook(®[i]);
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if (err)
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goto err;
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}
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return err;
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err:
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if (i > 0)
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nf_unregister_hooks(reg, i);
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return err;
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}
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EXPORT_SYMBOL(nf_register_hooks);
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void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n)
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{
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unsigned int i;
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for (i = 0; i < n; i++)
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nf_unregister_hook(®[i]);
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}
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EXPORT_SYMBOL(nf_unregister_hooks);
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unsigned int nf_iterate(struct list_head *head,
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struct sk_buff **skb,
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int hook,
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const struct net_device *indev,
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const struct net_device *outdev,
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struct list_head **i,
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int (*okfn)(struct sk_buff *),
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int hook_thresh)
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{
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unsigned int verdict;
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/*
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* The caller must not block between calls to this
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* function because of risk of continuing from deleted element.
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*/
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list_for_each_continue_rcu(*i, head) {
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struct nf_hook_ops *elem = (struct nf_hook_ops *)*i;
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if (hook_thresh > elem->priority)
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continue;
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/* Optimization: we don't need to hold module
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reference here, since function can't sleep. --RR */
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verdict = elem->hook(hook, skb, indev, outdev, okfn);
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if (verdict != NF_ACCEPT) {
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#ifdef CONFIG_NETFILTER_DEBUG
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if (unlikely((verdict & NF_VERDICT_MASK)
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> NF_MAX_VERDICT)) {
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NFDEBUG("Evil return from %p(%u).\n",
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elem->hook, hook);
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continue;
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}
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#endif
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if (verdict != NF_REPEAT)
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return verdict;
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*i = (*i)->prev;
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}
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}
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return NF_ACCEPT;
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}
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/* Returns 1 if okfn() needs to be executed by the caller,
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* -EPERM for NF_DROP, 0 otherwise. */
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int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb,
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struct net_device *indev,
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struct net_device *outdev,
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int (*okfn)(struct sk_buff *),
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int hook_thresh)
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{
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struct list_head *elem;
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unsigned int verdict;
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int ret = 0;
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/* We may already have this, but read-locks nest anyway */
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rcu_read_lock();
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elem = &nf_hooks[pf][hook];
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next_hook:
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verdict = nf_iterate(&nf_hooks[pf][hook], pskb, hook, indev,
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outdev, &elem, okfn, hook_thresh);
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if (verdict == NF_ACCEPT || verdict == NF_STOP) {
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ret = 1;
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goto unlock;
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} else if (verdict == NF_DROP) {
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kfree_skb(*pskb);
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ret = -EPERM;
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} else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
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NFDEBUG("nf_hook: Verdict = QUEUE.\n");
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if (!nf_queue(*pskb, elem, pf, hook, indev, outdev, okfn,
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verdict >> NF_VERDICT_BITS))
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goto next_hook;
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}
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unlock:
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rcu_read_unlock();
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return ret;
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}
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EXPORT_SYMBOL(nf_hook_slow);
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int skb_make_writable(struct sk_buff **pskb, unsigned int writable_len)
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{
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struct sk_buff *nskb;
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if (writable_len > (*pskb)->len)
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return 0;
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/* Not exclusive use of packet? Must copy. */
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if (skb_shared(*pskb) || skb_cloned(*pskb))
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goto copy_skb;
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return pskb_may_pull(*pskb, writable_len);
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copy_skb:
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nskb = skb_copy(*pskb, GFP_ATOMIC);
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if (!nskb)
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return 0;
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BUG_ON(skb_is_nonlinear(nskb));
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/* Rest of kernel will get very unhappy if we pass it a
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suddenly-orphaned skbuff */
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if ((*pskb)->sk)
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skb_set_owner_w(nskb, (*pskb)->sk);
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kfree_skb(*pskb);
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*pskb = nskb;
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return 1;
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}
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EXPORT_SYMBOL(skb_make_writable);
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u_int16_t nf_csum_update(u_int32_t oldval, u_int32_t newval, u_int32_t csum)
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{
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u_int32_t diff[] = { oldval, newval };
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return csum_fold(csum_partial((char *)diff, sizeof(diff), ~csum));
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}
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EXPORT_SYMBOL(nf_csum_update);
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u_int16_t nf_proto_csum_update(struct sk_buff *skb,
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u_int32_t oldval, u_int32_t newval,
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u_int16_t csum, int pseudohdr)
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{
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if (skb->ip_summed != CHECKSUM_PARTIAL) {
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csum = nf_csum_update(oldval, newval, csum);
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if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
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skb->csum = nf_csum_update(oldval, newval, skb->csum);
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} else if (pseudohdr)
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csum = ~nf_csum_update(oldval, newval, ~csum);
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return csum;
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}
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EXPORT_SYMBOL(nf_proto_csum_update);
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/* This does not belong here, but locally generated errors need it if connection
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tracking in use: without this, connection may not be in hash table, and hence
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manufactured ICMP or RST packets will not be associated with it. */
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void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
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EXPORT_SYMBOL(ip_ct_attach);
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void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb)
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{
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void (*attach)(struct sk_buff *, struct sk_buff *);
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if (skb->nfct && (attach = ip_ct_attach) != NULL) {
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mb(); /* Just to be sure: must be read before executing this */
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attach(new, skb);
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}
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}
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EXPORT_SYMBOL(nf_ct_attach);
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#ifdef CONFIG_PROC_FS
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struct proc_dir_entry *proc_net_netfilter;
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EXPORT_SYMBOL(proc_net_netfilter);
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#endif
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void __init netfilter_init(void)
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{
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int i, h;
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for (i = 0; i < NPROTO; i++) {
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for (h = 0; h < NF_MAX_HOOKS; h++)
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INIT_LIST_HEAD(&nf_hooks[i][h]);
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}
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#ifdef CONFIG_PROC_FS
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proc_net_netfilter = proc_mkdir("netfilter", proc_net);
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if (!proc_net_netfilter)
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panic("cannot create netfilter proc entry");
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#endif
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if (netfilter_queue_init() < 0)
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panic("cannot initialize nf_queue");
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if (netfilter_log_init() < 0)
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panic("cannot initialize nf_log");
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}
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