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