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/* netfilter.c: look after the filters for various protocols.
* 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.
*/
#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 <linux/mutex.h>
#include <linux/slab.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include "nf_internals.h"
static DEFINE_MUTEX(afinfo_mutex);
const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly;
EXPORT_SYMBOL(nf_afinfo);
int nf_register_afinfo(const struct nf_afinfo *afinfo)
{
int err;
err = mutex_lock_interruptible(&afinfo_mutex);
if (err < 0)
return err;
RCU_INIT_POINTER(nf_afinfo[afinfo->family], afinfo);
mutex_unlock(&afinfo_mutex);
return 0;
}
EXPORT_SYMBOL_GPL(nf_register_afinfo);
void nf_unregister_afinfo(const struct nf_afinfo *afinfo)
{
mutex_lock(&afinfo_mutex);
RCU_INIT_POINTER(nf_afinfo[afinfo->family], NULL);
mutex_unlock(&afinfo_mutex);
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(nf_unregister_afinfo);
struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS] __read_mostly;
EXPORT_SYMBOL(nf_hooks);
#if defined(CONFIG_JUMP_LABEL)
struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
EXPORT_SYMBOL(nf_hooks_needed);
#endif
static DEFINE_MUTEX(nf_hook_mutex);
int nf_register_hook(struct nf_hook_ops *reg)
{
struct nf_hook_ops *elem;
int err;
err = mutex_lock_interruptible(&nf_hook_mutex);
if (err < 0)
return err;
list_for_each_entry(elem, &nf_hooks[reg->pf][reg->hooknum], list) {
if (reg->priority < elem->priority)
break;
}
list_add_rcu(®->list, elem->list.prev);
mutex_unlock(&nf_hook_mutex);
#if defined(CONFIG_JUMP_LABEL)
static_key_slow_inc(&nf_hooks_needed[reg->pf][reg->hooknum]);
#endif
return 0;
}
EXPORT_SYMBOL(nf_register_hook);
void nf_unregister_hook(struct nf_hook_ops *reg)
{
mutex_lock(&nf_hook_mutex);
list_del_rcu(®->list);
mutex_unlock(&nf_hook_mutex);
#if defined(CONFIG_JUMP_LABEL)
static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
#endif
synchronize_net();
}
EXPORT_SYMBOL(nf_unregister_hook);
int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n)
{
unsigned int i;
int err = 0;
for (i = 0; i < n; i++) {
err = nf_register_hook(®[i]);
if (err)
goto err;
}
return err;
err:
if (i > 0)
nf_unregister_hooks(reg, i);
return err;
}
EXPORT_SYMBOL(nf_register_hooks);
void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n)
{
while (n-- > 0)
nf_unregister_hook(®[n]);
}
EXPORT_SYMBOL(nf_unregister_hooks);
unsigned int nf_iterate(struct list_head *head,
struct sk_buff *skb,
unsigned 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 */
repeat:
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;
goto repeat;
}
}
return NF_ACCEPT;
}
/* Returns 1 if okfn() needs to be executed by the caller,
* -EPERM for NF_DROP, 0 otherwise. */
int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
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], skb, hook, indev,
outdev, &elem, okfn, hook_thresh);
if (verdict == NF_ACCEPT || verdict == NF_STOP) {
ret = 1;
} else if ((verdict & NF_VERDICT_MASK) == NF_DROP) {
kfree_skb(skb);
ret = NF_DROP_GETERR(verdict);
if (ret == 0)
ret = -EPERM;
} else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
int err = nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
verdict >> NF_VERDICT_QBITS);
if (err < 0) {
if (err == -ECANCELED)
goto next_hook;
if (err == -ESRCH &&
(verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
goto next_hook;
kfree_skb(skb);
}
}
rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL(nf_hook_slow);
int skb_make_writable(struct sk_buff *skb, unsigned int writable_len)
{
if (writable_len > skb->len)
return 0;
/* Not exclusive use of packet? Must copy. */
if (!skb_cloned(skb)) {
if (writable_len <= skb_headlen(skb))
return 1;
} else if (skb_clone_writable(skb, writable_len))
return 1;
if (writable_len <= skb_headlen(skb))
writable_len = 0;
else
writable_len -= skb_headlen(skb);
return !!__pskb_pull_tail(skb, writable_len);
}
EXPORT_SYMBOL(skb_make_writable);
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
/* 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 *) __rcu __read_mostly;
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) {
rcu_read_lock();
attach = rcu_dereference(ip_ct_attach);
if (attach)
attach(new, skb);
rcu_read_unlock();
}
}
EXPORT_SYMBOL(nf_ct_attach);
void (*nf_ct_destroy)(struct nf_conntrack *) __rcu __read_mostly;
EXPORT_SYMBOL(nf_ct_destroy);
void nf_conntrack_destroy(struct nf_conntrack *nfct)
{
void (*destroy)(struct nf_conntrack *);
rcu_read_lock();
destroy = rcu_dereference(nf_ct_destroy);
BUG_ON(destroy == NULL);
destroy(nfct);
rcu_read_unlock();
}
EXPORT_SYMBOL(nf_conntrack_destroy);
struct nfq_ct_hook __rcu *nfq_ct_hook __read_mostly;
EXPORT_SYMBOL_GPL(nfq_ct_hook);
struct nfq_ct_nat_hook __rcu *nfq_ct_nat_hook __read_mostly;
EXPORT_SYMBOL_GPL(nfq_ct_nat_hook);
#endif /* CONFIG_NF_CONNTRACK */
#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 < ARRAY_SIZE(nf_hooks); 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", init_net.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
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