[mirror_ubuntu-artful-kernel.git] / net / netfilter / 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 = &reg->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);
	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, &reg[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, &reg[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(&reg->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(&reg->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(&reg[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(&reg[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 == -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 *, 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);

struct nfq_ct_hook __rcu *nfq_ct_hook __read_mostly;
EXPORT_SYMBOL_GPL(nfq_ct_hook);

/* 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;
}
Commit	Line	Data
601e68e1	1	/* netfilter.c: look after the filters for various protocols.
f6ebe77f HW	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.
f229f6ce	8	* Patrick McHardy (c) 2006-2012
f6ebe77f	9	*/
f6ebe77f HW	10	#include <linux/kernel.h>
	11	#include <linux/netfilter.h>
	12	#include <net/protocol.h>
	13	#include <linux/init.h>
	14	#include <linux/skbuff.h>
	15	#include <linux/wait.h>
	16	#include <linux/module.h>
	17	#include <linux/interrupt.h>
	18	#include <linux/if.h>
	19	#include <linux/netdevice.h>
56768644	20	#include <linux/netfilter_ipv6.h>
f6ebe77f HW	21	#include <linux/inetdevice.h>
f6ebe77f HW	22	#include <linux/proc_fs.h>
d486dd1f	23	#include <linux/mutex.h>
5a0e3ad6	24	#include <linux/slab.h>
457c4cbc	25	#include <net/net_namespace.h>
f6ebe77f HW	26	#include <net/sock.h>
	27
	28	#include "nf_internals.h"
	29
d486dd1f	30	static DEFINE_MUTEX(afinfo_mutex);
bce8032e	31
0906a372	32	const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly;
bce8032e	33	EXPORT_SYMBOL(nf_afinfo);
2a7851bf FW	34	const struct nf_ipv6_ops __rcu *nf_ipv6_ops __read_mostly;
2a7851bf FW	35	EXPORT_SYMBOL_GPL(nf_ipv6_ops);
bce8032e	36
e7c8899f FW	37	DEFINE_PER_CPU(bool, nf_skb_duplicated);
	38	EXPORT_SYMBOL_GPL(nf_skb_duplicated);
	39
1e796fda	40	int nf_register_afinfo(const struct nf_afinfo *afinfo)
bce8032e	41	{
7926dbfa	42	mutex_lock(&afinfo_mutex);
a9b3cd7f	43	RCU_INIT_POINTER(nf_afinfo[afinfo->family], afinfo);
d486dd1f	44	mutex_unlock(&afinfo_mutex);
bce8032e PM	45	return 0;
	46	}
	47	EXPORT_SYMBOL_GPL(nf_register_afinfo);
	48
1e796fda	49	void nf_unregister_afinfo(const struct nf_afinfo *afinfo)
bce8032e	50	{
d486dd1f	51	mutex_lock(&afinfo_mutex);
a9b3cd7f	52	RCU_INIT_POINTER(nf_afinfo[afinfo->family], NULL);
d486dd1f	53	mutex_unlock(&afinfo_mutex);
bce8032e PM	54	synchronize_rcu();
	55	}
	56	EXPORT_SYMBOL_GPL(nf_unregister_afinfo);
	57
d1c85c2e	58	#ifdef HAVE_JUMP_LABEL
c5905afb	59	struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
a2d7ec58 ED	60	EXPORT_SYMBOL(nf_hooks_needed);
	61	#endif
	62
fd706d69	63	static DEFINE_MUTEX(nf_hook_mutex);
f6ebe77f	64
3bbd14e0	65	static struct list_head nf_find_hook_list(struct net net,
085db2c0	66	const struct nf_hook_ops *reg)
f6ebe77f	67	{
3bbd14e0	68	struct list_head *hook_list = NULL;
f6ebe77f	69
0edcf282	70	if (reg->pf != NFPROTO_NETDEV)
3bbd14e0	71	hook_list = &net->nf.hooks[reg->pf][reg->hooknum];
0edcf282	72	else if (reg->hooknum == NF_NETDEV_INGRESS) {
e687ad60	73	#ifdef CONFIG_NETFILTER_INGRESS
085db2c0	74	if (reg->dev && dev_net(reg->dev) == net)
3bbd14e0	75	hook_list = &reg->dev->nf_hooks_ingress;
e687ad60	76	#endif
e687ad60	77	}
3bbd14e0	78	return hook_list;
0edcf282	79	}
e687ad60	80
7181ebaf PNA	81	struct nf_hook_entry {
	82	const struct nf_hook_ops *orig_ops;
	83	struct nf_hook_ops ops;
	84	};
	85
085db2c0	86	int nf_register_net_hook(struct net net, const struct nf_hook_ops reg)
0edcf282	87	{
3bbd14e0	88	struct list_head *hook_list;
7181ebaf PNA	89	struct nf_hook_entry *entry;
7181ebaf PNA	90	struct nf_hook_ops *elem;
085db2c0	91
7181ebaf PNA	92	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
7181ebaf PNA	93	if (!entry)
085db2c0	94	return -ENOMEM;
0edcf282	95
7181ebaf PNA	96	entry->orig_ops = reg;
7181ebaf PNA	97	entry->ops = *reg;
085db2c0	98
3bbd14e0 PNA	99	hook_list = nf_find_hook_list(net, reg);
3bbd14e0 PNA	100	if (!hook_list) {
7181ebaf	101	kfree(entry);
0edcf282	102	return -ENOENT;
e317fa50	103	}
0edcf282 EB	104
0edcf282 EB	105	mutex_lock(&nf_hook_mutex);
3bbd14e0	106	list_for_each_entry(elem, hook_list, list) {
4c610979	107	if (reg->priority < elem->priority)
f6ebe77f HW	108	break;
f6ebe77f HW	109	}
7181ebaf	110	list_add_rcu(&entry->ops.list, elem->list.prev);
fd706d69	111	mutex_unlock(&nf_hook_mutex);
4c091156 EB	112	#ifdef CONFIG_NETFILTER_INGRESS
	113	if (reg->pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS)
	114	net_inc_ingress_queue();
	115	#endif
d1c85c2e	116	#ifdef HAVE_JUMP_LABEL
c5905afb	117	static_key_slow_inc(&nf_hooks_needed[reg->pf][reg->hooknum]);
a2d7ec58	118	#endif
f6ebe77f HW	119	return 0;
f6ebe77f HW	120	}
085db2c0	121	EXPORT_SYMBOL(nf_register_net_hook);
f6ebe77f	122
085db2c0	123	void nf_unregister_net_hook(struct net net, const struct nf_hook_ops reg)
f6ebe77f	124	{
3bbd14e0	125	struct list_head *hook_list;
7181ebaf	126	struct nf_hook_entry *entry;
085db2c0 EB	127	struct nf_hook_ops *elem;
085db2c0 EB	128
3bbd14e0 PNA	129	hook_list = nf_find_hook_list(net, reg);
3bbd14e0 PNA	130	if (!hook_list)
085db2c0 EB	131	return;
085db2c0 EB	132
fd706d69	133	mutex_lock(&nf_hook_mutex);
3bbd14e0	134	list_for_each_entry(elem, hook_list, list) {
7181ebaf PNA	135	entry = container_of(elem, struct nf_hook_entry, ops);
	136	if (entry->orig_ops == reg) {
	137	list_del_rcu(&entry->ops.list);
085db2c0 EB	138	break;
	139	}
	140	}
fd706d69	141	mutex_unlock(&nf_hook_mutex);
3bbd14e0	142	if (&elem->list == hook_list) {
085db2c0 EB	143	WARN(1, "nf_unregister_net_hook: hook not found!\n");
	144	return;
	145	}
e687ad60	146	#ifdef CONFIG_NETFILTER_INGRESS
4c091156 EB	147	if (reg->pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS)
4c091156 EB	148	net_dec_ingress_queue();
e687ad60	149	#endif
d1c85c2e	150	#ifdef HAVE_JUMP_LABEL
c5905afb	151	static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
a2d7ec58	152	#endif
f6ebe77f	153	synchronize_net();
7181ebaf PNA	154	nf_queue_nf_hook_drop(net, &entry->ops);
7181ebaf PNA	155	kfree(entry);
085db2c0 EB	156	}
	157	EXPORT_SYMBOL(nf_unregister_net_hook);
	158
	159	int nf_register_net_hooks(struct net net, const struct nf_hook_ops reg,
	160	unsigned int n)
	161	{
	162	unsigned int i;
	163	int err = 0;
	164
	165	for (i = 0; i < n; i++) {
	166	err = nf_register_net_hook(net, &reg[i]);
	167	if (err)
	168	goto err;
	169	}
	170	return err;
	171
	172	err:
	173	if (i > 0)
	174	nf_unregister_net_hooks(net, reg, i);
	175	return err;
	176	}
	177	EXPORT_SYMBOL(nf_register_net_hooks);
	178
	179	void nf_unregister_net_hooks(struct net net, const struct nf_hook_ops reg,
	180	unsigned int n)
	181	{
	182	while (n-- > 0)
	183	nf_unregister_net_hook(net, &reg[n]);
	184	}
	185	EXPORT_SYMBOL(nf_unregister_net_hooks);
	186
	187	static LIST_HEAD(nf_hook_list);
	188
	189	int nf_register_hook(struct nf_hook_ops *reg)
	190	{
	191	struct net net, last;
	192	int ret;
	193
	194	rtnl_lock();
	195	for_each_net(net) {
	196	ret = nf_register_net_hook(net, reg);
	197	if (ret && ret != -ENOENT)
	198	goto rollback;
	199	}
	200	list_add_tail(&reg->list, &nf_hook_list);
	201	rtnl_unlock();
	202
	203	return 0;
	204	rollback:
	205	last = net;
	206	for_each_net(net) {
	207	if (net == last)
	208	break;
	209	nf_unregister_net_hook(net, reg);
	210	}
	211	rtnl_unlock();
	212	return ret;
	213	}
	214	EXPORT_SYMBOL(nf_register_hook);
	215
	216	void nf_unregister_hook(struct nf_hook_ops *reg)
	217	{
	218	struct net *net;
	219
220	rtnl_lock();
221	list_del(&reg->list);
222	for_each_net(net)
223	nf_unregister_net_hook(net, reg);
224	rtnl_unlock();
f6ebe77f HW	225	}
	226	EXPORT_SYMBOL(nf_unregister_hook);
	227
972d1cb1 PM	228	int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n)
	229	{
	230	unsigned int i;
	231	int err = 0;
	232
	233	for (i = 0; i < n; i++) {
	234	err = nf_register_hook(&reg[i]);
	235	if (err)
	236	goto err;
	237	}
	238	return err;
	239
	240	err:
	241	if (i > 0)
	242	nf_unregister_hooks(reg, i);
	243	return err;
	244	}
	245	EXPORT_SYMBOL(nf_register_hooks);
	246
	247	void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n)
	248	{
f68c5301 CG	249	while (n-- > 0)
f68c5301 CG	250	nf_unregister_hook(&reg[n]);
972d1cb1 PM	251	}
	252	EXPORT_SYMBOL(nf_unregister_hooks);
	253
f6ebe77f	254	unsigned int nf_iterate(struct list_head *head,
3db05fea	255	struct sk_buff *skb,
cfdfab31 DM	256	struct nf_hook_state *state,
cfdfab31 DM	257	struct nf_hook_ops **elemp)
f6ebe77f HW	258	{
	259	unsigned int verdict;
	260
	261	/*
	262	* The caller must not block between calls to this
	263	* function because of risk of continuing from deleted element.
	264	*/
2a6decfd	265	list_for_each_entry_continue_rcu((*elemp), head, list) {
cfdfab31	266	if (state->thresh > (*elemp)->priority)
f6ebe77f HW	267	continue;
	268
	269	/* Optimization: we don't need to hold module
601e68e1	270	reference here, since function can't sleep. --RR */
de9963f0	271	repeat:
06198b34	272	verdict = (elemp)->hook((elemp)->priv, skb, state);
f6ebe77f HW	273	if (verdict != NF_ACCEPT) {
	274	#ifdef CONFIG_NETFILTER_DEBUG
	275	if (unlikely((verdict & NF_VERDICT_MASK)
	276	> NF_MAX_VERDICT)) {
	277	NFDEBUG("Evil return from %p(%u).\n",
cfdfab31	278	(*elemp)->hook, state->hook);
f6ebe77f HW	279	continue;
	280	}
	281	#endif
2a6decfd	282	if (verdict != NF_REPEAT)
f6ebe77f	283	return verdict;
de9963f0	284	goto repeat;
f6ebe77f HW	285	}
	286	}
	287	return NF_ACCEPT;
	288	}
	289
	290
	291	/* Returns 1 if okfn() needs to be executed by the caller,
	292	* -EPERM for NF_DROP, 0 otherwise. */
cfdfab31	293	int nf_hook_slow(struct sk_buff skb, struct nf_hook_state state)
f6ebe77f	294	{
2a6decfd	295	struct nf_hook_ops *elem;
f6ebe77f HW	296	unsigned int verdict;
	297	int ret = 0;
	298
	299	/* We may already have this, but read-locks nest anyway */
	300	rcu_read_lock();
	301
f7191483	302	elem = list_entry_rcu(state->hook_list, struct nf_hook_ops, list);
f6ebe77f	303	next_hook:
f7191483	304	verdict = nf_iterate(state->hook_list, skb, state, &elem);
f6ebe77f HW	305	if (verdict == NF_ACCEPT \|\| verdict == NF_STOP) {
f6ebe77f HW	306	ret = 1;
da683650	307	} else if ((verdict & NF_VERDICT_MASK) == NF_DROP) {
3db05fea	308	kfree_skb(skb);
f615df76	309	ret = NF_DROP_GETERR(verdict);
da683650 EP	310	if (ret == 0)
da683650 EP	311	ret = -EPERM;
f9c63990	312	} else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
cfdfab31 DM	313	int err = nf_queue(skb, elem, state,
cfdfab31 DM	314	verdict >> NF_VERDICT_QBITS);
563e1232 FW	315	if (err < 0) {
563e1232 FW	316	if (err == -ECANCELED)
06cdb634	317	goto next_hook;
563e1232	318	if (err == -ESRCH &&
94b27cc3 FW	319	(verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
94b27cc3 FW	320	goto next_hook;
06cdb634 FW	321	kfree_skb(skb);
06cdb634 FW	322	}
f6ebe77f	323	}
f6ebe77f HW	324	rcu_read_unlock();
	325	return ret;
	326	}
	327	EXPORT_SYMBOL(nf_hook_slow);
	328
	329
37d41879	330	int skb_make_writable(struct sk_buff *skb, unsigned int writable_len)
f6ebe77f	331	{
37d41879	332	if (writable_len > skb->len)
f6ebe77f HW	333	return 0;
	334
	335	/* Not exclusive use of packet? Must copy. */
37d41879 HX	336	if (!skb_cloned(skb)) {
	337	if (writable_len <= skb_headlen(skb))
	338	return 1;
	339	} else if (skb_clone_writable(skb, writable_len))
	340	return 1;
	341
	342	if (writable_len <= skb_headlen(skb))
	343	writable_len = 0;
	344	else
	345	writable_len -= skb_headlen(skb);
	346
	347	return !!__pskb_pull_tail(skb, writable_len);
f6ebe77f HW	348	}
	349	EXPORT_SYMBOL(skb_make_writable);
	350
c0cd1156	351	#if IS_ENABLED(CONFIG_NF_CONNTRACK)
f6ebe77f HW	352	/* This does not belong here, but locally generated errors need it if connection
	353	tracking in use: without this, connection may not be in hash table, and hence
	354	manufactured ICMP or RST packets will not be associated with it. */
312a0c16 PM	355	void (ip_ct_attach)(struct sk_buff , const struct sk_buff *)
312a0c16 PM	356	__rcu __read_mostly;
f6ebe77f HW	357	EXPORT_SYMBOL(ip_ct_attach);
f6ebe77f HW	358
312a0c16	359	void nf_ct_attach(struct sk_buff new, const struct sk_buff skb)
f6ebe77f	360	{
312a0c16	361	void (attach)(struct sk_buff , const struct sk_buff *);
f6ebe77f	362
c3a47ab3 PM	363	if (skb->nfct) {
	364	rcu_read_lock();
	365	attach = rcu_dereference(ip_ct_attach);
	366	if (attach)
	367	attach(new, skb);
	368	rcu_read_unlock();
f6ebe77f HW	369	}
	370	}
	371	EXPORT_SYMBOL(nf_ct_attach);
de6e05c4	372
0e60ebe0	373	void (nf_ct_destroy)(struct nf_conntrack ) __rcu __read_mostly;
de6e05c4 YK	374	EXPORT_SYMBOL(nf_ct_destroy);
	375
	376	void nf_conntrack_destroy(struct nf_conntrack *nfct)
	377	{
	378	void (destroy)(struct nf_conntrack );
	379
	380	rcu_read_lock();
	381	destroy = rcu_dereference(nf_ct_destroy);
	382	BUG_ON(destroy == NULL);
	383	destroy(nfct);
	384	rcu_read_unlock();
	385	}
	386	EXPORT_SYMBOL(nf_conntrack_destroy);
9cb01766	387
5a05fae5	388	struct nfq_ct_hook __rcu *nfq_ct_hook __read_mostly;
9cb01766 PNA	389	EXPORT_SYMBOL_GPL(nfq_ct_hook);
9cb01766 PNA	390
62da9865 DB	391	/* Built-in default zone used e.g. by modules. */
	392	const struct nf_conntrack_zone nf_ct_zone_dflt = {
	393	.id = NF_CT_DEFAULT_ZONE_ID,
	394	.dir = NF_CT_DEFAULT_ZONE_DIR,
	395	};
	396	EXPORT_SYMBOL_GPL(nf_ct_zone_dflt);
de6e05c4	397	#endif /* CONFIG_NF_CONNTRACK */
f6ebe77f	398
c7232c99 PM	399	#ifdef CONFIG_NF_NAT_NEEDED
	400	void (nf_nat_decode_session_hook)(struct sk_buff , struct flowi *);
	401	EXPORT_SYMBOL(nf_nat_decode_session_hook);
	402	#endif
	403
085db2c0 EB	404	static int nf_register_hook_list(struct net *net)
	405	{
	406	struct nf_hook_ops *elem;
	407	int ret;
	408
	409	rtnl_lock();
	410	list_for_each_entry(elem, &nf_hook_list, list) {
	411	ret = nf_register_net_hook(net, elem);
	412	if (ret && ret != -ENOENT)
	413	goto out_undo;
	414	}
	415	rtnl_unlock();
	416	return 0;
	417
	418	out_undo:
	419	list_for_each_entry_continue_reverse(elem, &nf_hook_list, list)
	420	nf_unregister_net_hook(net, elem);
	421	rtnl_unlock();
	422	return ret;
	423	}
	424
	425	static void nf_unregister_hook_list(struct net *net)
	426	{
	427	struct nf_hook_ops *elem;
	428
	429	rtnl_lock();
	430	list_for_each_entry(elem, &nf_hook_list, list)
	431	nf_unregister_net_hook(net, elem);
	432	rtnl_unlock();
	433	}
	434
f3c1a44a G	435	static int __net_init netfilter_net_init(struct net *net)
f3c1a44a G	436	{
085db2c0 EB	437	int i, h, ret;
	438
	439	for (i = 0; i < ARRAY_SIZE(net->nf.hooks); i++) {
	440	for (h = 0; h < NF_MAX_HOOKS; h++)
	441	INIT_LIST_HEAD(&net->nf.hooks[i][h]);
	442	}
	443
f3c1a44a G	444	#ifdef CONFIG_PROC_FS
	445	net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter",
	446	net->proc_net);
12202fa7 PNA	447	if (!net->nf.proc_netfilter) {
	448	if (!net_eq(net, &init_net))
	449	pr_err("cannot create netfilter proc entry");
	450
f3c1a44a G	451	return -ENOMEM;
	452	}
	453	#endif
085db2c0 EB	454	ret = nf_register_hook_list(net);
	455	if (ret)
	456	remove_proc_entry("netfilter", net->proc_net);
	457
	458	return ret;
f3c1a44a G	459	}
	460
	461	static void __net_exit netfilter_net_exit(struct net *net)
	462	{
085db2c0	463	nf_unregister_hook_list(net);
f3c1a44a G	464	remove_proc_entry("netfilter", net->proc_net);
	465	}
	466
	467	static struct pernet_operations netfilter_net_ops = {
	468	.init = netfilter_net_init,
	469	.exit = netfilter_net_exit,
	470	};
	471
6d11cfdb	472	int __init netfilter_init(void)
f6ebe77f	473	{
085db2c0	474	int ret;
f6ebe77f	475
6d11cfdb PNA	476	ret = register_pernet_subsys(&netfilter_net_ops);
	477	if (ret < 0)
	478	goto err;
	479
	480	ret = netfilter_log_init();
	481	if (ret < 0)
	482	goto err_pernet;
f6ebe77f	483
6d11cfdb PNA	484	return 0;
	485	err_pernet:
	486	unregister_pernet_subsys(&netfilter_net_ops);
	487	err:
	488	return ret;
f6ebe77f	489	}