https://github.com/torvalds/linux
Tip revision: c3b46c73264b03000d1e18b22f5caf63332547c9 authored by Linus Torvalds on 18 April 2016, 02:13:32 UTC
Linux 4.6-rc4
Linux 4.6-rc4
Tip revision: c3b46c7
core.c
/* 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.
* Patrick McHardy (c) 2006-2012
*/
#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/netfilter_ipv6.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);
const struct nf_ipv6_ops __rcu *nf_ipv6_ops __read_mostly;
EXPORT_SYMBOL_GPL(nf_ipv6_ops);
DEFINE_PER_CPU(bool, nf_skb_duplicated);
EXPORT_SYMBOL_GPL(nf_skb_duplicated);
int nf_register_afinfo(const struct nf_afinfo *afinfo)
{
mutex_lock(&afinfo_mutex);
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);
#ifdef HAVE_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);
static struct list_head *nf_find_hook_list(struct net *net,
const struct nf_hook_ops *reg)
{
struct list_head *hook_list = NULL;
if (reg->pf != NFPROTO_NETDEV)
hook_list = &net->nf.hooks[reg->pf][reg->hooknum];
else if (reg->hooknum == NF_NETDEV_INGRESS) {
#ifdef CONFIG_NETFILTER_INGRESS
if (reg->dev && dev_net(reg->dev) == net)
hook_list = ®->dev->nf_hooks_ingress;
#endif
}
return hook_list;
}
struct nf_hook_entry {
const struct nf_hook_ops *orig_ops;
struct nf_hook_ops ops;
};
int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
{
struct list_head *hook_list;
struct nf_hook_entry *entry;
struct nf_hook_ops *elem;
entry = kmalloc(sizeof(*entry), GFP_KERNEL);
if (!entry)
return -ENOMEM;
entry->orig_ops = reg;
entry->ops = *reg;
hook_list = nf_find_hook_list(net, reg);
if (!hook_list) {
kfree(entry);
return -ENOENT;
}
mutex_lock(&nf_hook_mutex);
list_for_each_entry(elem, hook_list, list) {
if (reg->priority < elem->priority)
break;
}
list_add_rcu(&entry->ops.list, elem->list.prev);
mutex_unlock(&nf_hook_mutex);
#ifdef CONFIG_NETFILTER_INGRESS
if (reg->pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS)
net_inc_ingress_queue();
#endif
#ifdef HAVE_JUMP_LABEL
static_key_slow_inc(&nf_hooks_needed[reg->pf][reg->hooknum]);
#endif
return 0;
}
EXPORT_SYMBOL(nf_register_net_hook);
void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
{
struct list_head *hook_list;
struct nf_hook_entry *entry;
struct nf_hook_ops *elem;
hook_list = nf_find_hook_list(net, reg);
if (!hook_list)
return;
mutex_lock(&nf_hook_mutex);
list_for_each_entry(elem, hook_list, list) {
entry = container_of(elem, struct nf_hook_entry, ops);
if (entry->orig_ops == reg) {
list_del_rcu(&entry->ops.list);
break;
}
}
mutex_unlock(&nf_hook_mutex);
if (&elem->list == hook_list) {
WARN(1, "nf_unregister_net_hook: hook not found!\n");
return;
}
#ifdef CONFIG_NETFILTER_INGRESS
if (reg->pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS)
net_dec_ingress_queue();
#endif
#ifdef HAVE_JUMP_LABEL
static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
#endif
synchronize_net();
nf_queue_nf_hook_drop(net, &entry->ops);
/* other cpu might still process nfqueue verdict that used reg */
synchronize_net();
kfree(entry);
}
EXPORT_SYMBOL(nf_unregister_net_hook);
int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
unsigned int n)
{
unsigned int i;
int err = 0;
for (i = 0; i < n; i++) {
err = nf_register_net_hook(net, ®[i]);
if (err)
goto err;
}
return err;
err:
if (i > 0)
nf_unregister_net_hooks(net, reg, i);
return err;
}
EXPORT_SYMBOL(nf_register_net_hooks);
void nf_unregister_net_hooks(struct net *net, const struct nf_hook_ops *reg,
unsigned int n)
{
while (n-- > 0)
nf_unregister_net_hook(net, ®[n]);
}
EXPORT_SYMBOL(nf_unregister_net_hooks);
static LIST_HEAD(nf_hook_list);
int nf_register_hook(struct nf_hook_ops *reg)
{
struct net *net, *last;
int ret;
rtnl_lock();
for_each_net(net) {
ret = nf_register_net_hook(net, reg);
if (ret && ret != -ENOENT)
goto rollback;
}
list_add_tail(®->list, &nf_hook_list);
rtnl_unlock();
return 0;
rollback:
last = net;
for_each_net(net) {
if (net == last)
break;
nf_unregister_net_hook(net, reg);
}
rtnl_unlock();
return ret;
}
EXPORT_SYMBOL(nf_register_hook);
void nf_unregister_hook(struct nf_hook_ops *reg)
{
struct net *net;
rtnl_lock();
list_del(®->list);
for_each_net(net)
nf_unregister_net_hook(net, reg);
rtnl_unlock();
}
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,
struct nf_hook_state *state,
struct nf_hook_ops **elemp)
{
unsigned int verdict;
/*
* The caller must not block between calls to this
* function because of risk of continuing from deleted element.
*/
list_for_each_entry_continue_rcu((*elemp), head, list) {
if (state->thresh > (*elemp)->priority)
continue;
/* Optimization: we don't need to hold module
reference here, since function can't sleep. --RR */
repeat:
verdict = (*elemp)->hook((*elemp)->priv, skb, state);
if (verdict != NF_ACCEPT) {
#ifdef CONFIG_NETFILTER_DEBUG
if (unlikely((verdict & NF_VERDICT_MASK)
> NF_MAX_VERDICT)) {
NFDEBUG("Evil return from %p(%u).\n",
(*elemp)->hook, state->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(struct sk_buff *skb, struct nf_hook_state *state)
{
struct nf_hook_ops *elem;
unsigned int verdict;
int ret = 0;
/* We may already have this, but read-locks nest anyway */
rcu_read_lock();
elem = list_entry_rcu(state->hook_list, struct nf_hook_ops, list);
next_hook:
verdict = nf_iterate(state->hook_list, skb, state, &elem);
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, state,
verdict >> NF_VERDICT_QBITS);
if (err < 0) {
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);
/* This needs to be compiled in any case to avoid dependencies between the
* nfnetlink_queue code and nf_conntrack.
*/
struct nfnl_ct_hook __rcu *nfnl_ct_hook __read_mostly;
EXPORT_SYMBOL_GPL(nfnl_ct_hook);
#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 *, const struct sk_buff *)
__rcu __read_mostly;
EXPORT_SYMBOL(ip_ct_attach);
void nf_ct_attach(struct sk_buff *new, const struct sk_buff *skb)
{
void (*attach)(struct sk_buff *, const 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);
/* Built-in default zone used e.g. by modules. */
const struct nf_conntrack_zone nf_ct_zone_dflt = {
.id = NF_CT_DEFAULT_ZONE_ID,
.dir = NF_CT_DEFAULT_ZONE_DIR,
};
EXPORT_SYMBOL_GPL(nf_ct_zone_dflt);
#endif /* CONFIG_NF_CONNTRACK */
#ifdef CONFIG_NF_NAT_NEEDED
void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
EXPORT_SYMBOL(nf_nat_decode_session_hook);
#endif
static int nf_register_hook_list(struct net *net)
{
struct nf_hook_ops *elem;
int ret;
rtnl_lock();
list_for_each_entry(elem, &nf_hook_list, list) {
ret = nf_register_net_hook(net, elem);
if (ret && ret != -ENOENT)
goto out_undo;
}
rtnl_unlock();
return 0;
out_undo:
list_for_each_entry_continue_reverse(elem, &nf_hook_list, list)
nf_unregister_net_hook(net, elem);
rtnl_unlock();
return ret;
}
static void nf_unregister_hook_list(struct net *net)
{
struct nf_hook_ops *elem;
rtnl_lock();
list_for_each_entry(elem, &nf_hook_list, list)
nf_unregister_net_hook(net, elem);
rtnl_unlock();
}
static int __net_init netfilter_net_init(struct net *net)
{
int i, h, ret;
for (i = 0; i < ARRAY_SIZE(net->nf.hooks); i++) {
for (h = 0; h < NF_MAX_HOOKS; h++)
INIT_LIST_HEAD(&net->nf.hooks[i][h]);
}
#ifdef CONFIG_PROC_FS
net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter",
net->proc_net);
if (!net->nf.proc_netfilter) {
if (!net_eq(net, &init_net))
pr_err("cannot create netfilter proc entry");
return -ENOMEM;
}
#endif
ret = nf_register_hook_list(net);
if (ret)
remove_proc_entry("netfilter", net->proc_net);
return ret;
}
static void __net_exit netfilter_net_exit(struct net *net)
{
nf_unregister_hook_list(net);
remove_proc_entry("netfilter", net->proc_net);
}
static struct pernet_operations netfilter_net_ops = {
.init = netfilter_net_init,
.exit = netfilter_net_exit,
};
int __init netfilter_init(void)
{
int ret;
ret = register_pernet_subsys(&netfilter_net_ops);
if (ret < 0)
goto err;
ret = netfilter_log_init();
if (ret < 0)
goto err_pernet;
return 0;
err_pernet:
unregister_pernet_subsys(&netfilter_net_ops);
err:
return ret;
}