[GitHub/mt8127/android_kernel_alcatel_ttab.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.
 */
#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 <net/net_namespace.h>
#include <net/sock.h>

#include "nf_internals.h"

static DEFINE_MUTEX(afinfo_mutex);

const struct nf_afinfo *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_assign_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_assign_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);
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(&reg->list, elem->list.prev);
	mutex_unlock(&nf_hook_mutex);
	return 0;
}
EXPORT_SYMBOL(nf_register_hook);

void nf_unregister_hook(struct nf_hook_ops *reg)
{
	mutex_lock(&nf_hook_mutex);
	list_del_rcu(&reg->list);
	mutex_unlock(&nf_hook_mutex);

	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(&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)
{
	unsigned int i;

	for (i = 0; i < n; i++)
		nf_unregister_hook(&reg[i]);
}
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 */
		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(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_DROP) {
		kfree_skb(skb);
		ret = -EPERM;
	} else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
		if (!nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
			      verdict >> NF_VERDICT_BITS))
			goto next_hook;
	}
	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 defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
/* 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) {
		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 *);
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);
#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)
		panic("cannot initialize nf_log");
}

#ifdef CONFIG_SYSCTL
struct ctl_path nf_net_netfilter_sysctl_path[] = {
	{ .procname = "net", },
	{ .procname = "netfilter", },
	{ }
};
EXPORT_SYMBOL_GPL(nf_net_netfilter_sysctl_path);
#endif /* CONFIG_SYSCTL */
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.
f6ebe77f	8	*/
f6ebe77f HW	9	#include <linux/kernel.h>
	10	#include <linux/netfilter.h>
	11	#include <net/protocol.h>
	12	#include <linux/init.h>
	13	#include <linux/skbuff.h>
	14	#include <linux/wait.h>
	15	#include <linux/module.h>
	16	#include <linux/interrupt.h>
	17	#include <linux/if.h>
	18	#include <linux/netdevice.h>
	19	#include <linux/inetdevice.h>
	20	#include <linux/proc_fs.h>
d486dd1f	21	#include <linux/mutex.h>
457c4cbc	22	#include <net/net_namespace.h>
f6ebe77f HW	23	#include <net/sock.h>
	24
	25	#include "nf_internals.h"
	26
d486dd1f	27	static DEFINE_MUTEX(afinfo_mutex);
bce8032e	28
7e9c6eeb	29	const struct nf_afinfo *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly;
bce8032e PM	30	EXPORT_SYMBOL(nf_afinfo);
bce8032e PM	31
1e796fda	32	int nf_register_afinfo(const struct nf_afinfo *afinfo)
bce8032e	33	{
d486dd1f PM	34	int err;
	35
	36	err = mutex_lock_interruptible(&afinfo_mutex);
	37	if (err < 0)
	38	return err;
bce8032e	39	rcu_assign_pointer(nf_afinfo[afinfo->family], afinfo);
d486dd1f	40	mutex_unlock(&afinfo_mutex);
bce8032e PM	41	return 0;
	42	}
	43	EXPORT_SYMBOL_GPL(nf_register_afinfo);
	44
1e796fda	45	void nf_unregister_afinfo(const struct nf_afinfo *afinfo)
bce8032e	46	{
d486dd1f	47	mutex_lock(&afinfo_mutex);
bce8032e	48	rcu_assign_pointer(nf_afinfo[afinfo->family], NULL);
d486dd1f	49	mutex_unlock(&afinfo_mutex);
bce8032e PM	50	synchronize_rcu();
	51	}
	52	EXPORT_SYMBOL_GPL(nf_unregister_afinfo);
	53
7e9c6eeb	54	struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS] __read_mostly;
f6ebe77f	55	EXPORT_SYMBOL(nf_hooks);
fd706d69	56	static DEFINE_MUTEX(nf_hook_mutex);
f6ebe77f HW	57
	58	int nf_register_hook(struct nf_hook_ops *reg)
	59	{
4c610979	60	struct nf_hook_ops *elem;
fd706d69	61	int err;
f6ebe77f	62
fd706d69 PM	63	err = mutex_lock_interruptible(&nf_hook_mutex);
	64	if (err < 0)
	65	return err;
4c610979 LZ	66	list_for_each_entry(elem, &nf_hooks[reg->pf][reg->hooknum], list) {
4c610979 LZ	67	if (reg->priority < elem->priority)
f6ebe77f HW	68	break;
f6ebe77f HW	69	}
4c610979	70	list_add_rcu(&reg->list, elem->list.prev);
fd706d69	71	mutex_unlock(&nf_hook_mutex);
f6ebe77f HW	72	return 0;
	73	}
	74	EXPORT_SYMBOL(nf_register_hook);
	75
	76	void nf_unregister_hook(struct nf_hook_ops *reg)
	77	{
fd706d69	78	mutex_lock(&nf_hook_mutex);
f6ebe77f	79	list_del_rcu(&reg->list);
fd706d69	80	mutex_unlock(&nf_hook_mutex);
f6ebe77f HW	81
	82	synchronize_net();
	83	}
	84	EXPORT_SYMBOL(nf_unregister_hook);
	85
972d1cb1 PM	86	int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n)
	87	{
	88	unsigned int i;
	89	int err = 0;
	90
	91	for (i = 0; i < n; i++) {
	92	err = nf_register_hook(&reg[i]);
	93	if (err)
	94	goto err;
	95	}
	96	return err;
	97
	98	err:
	99	if (i > 0)
	100	nf_unregister_hooks(reg, i);
	101	return err;
	102	}
	103	EXPORT_SYMBOL(nf_register_hooks);
	104
	105	void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n)
	106	{
	107	unsigned int i;
	108
	109	for (i = 0; i < n; i++)
	110	nf_unregister_hook(&reg[i]);
	111	}
	112	EXPORT_SYMBOL(nf_unregister_hooks);
	113
f6ebe77f	114	unsigned int nf_iterate(struct list_head *head,
3db05fea	115	struct sk_buff *skb,
76108cea	116	unsigned int hook,
f6ebe77f HW	117	const struct net_device *indev,
	118	const struct net_device *outdev,
	119	struct list_head **i,
	120	int (okfn)(struct sk_buff ),
	121	int hook_thresh)
	122	{
	123	unsigned int verdict;
	124
	125	/*
	126	* The caller must not block between calls to this
	127	* function because of risk of continuing from deleted element.
	128	*/
	129	list_for_each_continue_rcu(*i, head) {
	130	struct nf_hook_ops elem = (struct nf_hook_ops )*i;
	131
	132	if (hook_thresh > elem->priority)
	133	continue;
	134
	135	/* Optimization: we don't need to hold module
601e68e1	136	reference here, since function can't sleep. --RR */
f6ebe77f HW	137	verdict = elem->hook(hook, skb, indev, outdev, okfn);
	138	if (verdict != NF_ACCEPT) {
	139	#ifdef CONFIG_NETFILTER_DEBUG
	140	if (unlikely((verdict & NF_VERDICT_MASK)
	141	> NF_MAX_VERDICT)) {
	142	NFDEBUG("Evil return from %p(%u).\n",
601e68e1	143	elem->hook, hook);
f6ebe77f HW	144	continue;
	145	}
	146	#endif
	147	if (verdict != NF_REPEAT)
	148	return verdict;
	149	i = (i)->prev;
	150	}
	151	}
	152	return NF_ACCEPT;
	153	}
	154
	155
	156	/* Returns 1 if okfn() needs to be executed by the caller,
	157	* -EPERM for NF_DROP, 0 otherwise. */
76108cea	158	int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
f6ebe77f HW	159	struct net_device *indev,
	160	struct net_device *outdev,
	161	int (okfn)(struct sk_buff ),
	162	int hook_thresh)
	163	{
	164	struct list_head *elem;
	165	unsigned int verdict;
	166	int ret = 0;
	167
	168	/* We may already have this, but read-locks nest anyway */
	169	rcu_read_lock();
	170
	171	elem = &nf_hooks[pf][hook];
	172	next_hook:
3db05fea	173	verdict = nf_iterate(&nf_hooks[pf][hook], skb, hook, indev,
f6ebe77f HW	174	outdev, &elem, okfn, hook_thresh);
	175	if (verdict == NF_ACCEPT \|\| verdict == NF_STOP) {
	176	ret = 1;
f6ebe77f	177	} else if (verdict == NF_DROP) {
3db05fea	178	kfree_skb(skb);
f6ebe77f	179	ret = -EPERM;
f9c63990	180	} else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
3db05fea	181	if (!nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
f6ebe77f HW	182	verdict >> NF_VERDICT_BITS))
	183	goto next_hook;
	184	}
f6ebe77f HW	185	rcu_read_unlock();
	186	return ret;
	187	}
	188	EXPORT_SYMBOL(nf_hook_slow);
	189
	190
37d41879	191	int skb_make_writable(struct sk_buff *skb, unsigned int writable_len)
f6ebe77f	192	{
37d41879	193	if (writable_len > skb->len)
f6ebe77f HW	194	return 0;
	195
	196	/* Not exclusive use of packet? Must copy. */
37d41879 HX	197	if (!skb_cloned(skb)) {
	198	if (writable_len <= skb_headlen(skb))
	199	return 1;
	200	} else if (skb_clone_writable(skb, writable_len))
	201	return 1;
	202
	203	if (writable_len <= skb_headlen(skb))
	204	writable_len = 0;
	205	else
	206	writable_len -= skb_headlen(skb);
	207
	208	return !!__pskb_pull_tail(skb, writable_len);
f6ebe77f HW	209	}
	210	EXPORT_SYMBOL(skb_make_writable);
	211
5f79e0f9	212	#if defined(CONFIG_NF_CONNTRACK) \|\| defined(CONFIG_NF_CONNTRACK_MODULE)
f6ebe77f HW	213	/* This does not belong here, but locally generated errors need it if connection
	214	tracking in use: without this, connection may not be in hash table, and hence
	215	manufactured ICMP or RST packets will not be associated with it. */
	216	void (ip_ct_attach)(struct sk_buff , struct sk_buff *);
	217	EXPORT_SYMBOL(ip_ct_attach);
	218
	219	void nf_ct_attach(struct sk_buff new, struct sk_buff skb)
	220	{
	221	void (attach)(struct sk_buff , struct sk_buff *);
	222
c3a47ab3 PM	223	if (skb->nfct) {
	224	rcu_read_lock();
	225	attach = rcu_dereference(ip_ct_attach);
	226	if (attach)
	227	attach(new, skb);
	228	rcu_read_unlock();
f6ebe77f HW	229	}
	230	}
	231	EXPORT_SYMBOL(nf_ct_attach);
de6e05c4 YK	232
	233	void (nf_ct_destroy)(struct nf_conntrack );
	234	EXPORT_SYMBOL(nf_ct_destroy);
	235
	236	void nf_conntrack_destroy(struct nf_conntrack *nfct)
	237	{
	238	void (destroy)(struct nf_conntrack );
	239
	240	rcu_read_lock();
	241	destroy = rcu_dereference(nf_ct_destroy);
	242	BUG_ON(destroy == NULL);
	243	destroy(nfct);
	244	rcu_read_unlock();
	245	}
	246	EXPORT_SYMBOL(nf_conntrack_destroy);
	247	#endif /* CONFIG_NF_CONNTRACK */
f6ebe77f HW	248
	249	#ifdef CONFIG_PROC_FS
	250	struct proc_dir_entry *proc_net_netfilter;
	251	EXPORT_SYMBOL(proc_net_netfilter);
	252	#endif
	253
	254	void __init netfilter_init(void)
	255	{
	256	int i, h;
7e9c6eeb	257	for (i = 0; i < ARRAY_SIZE(nf_hooks); i++) {
f6ebe77f HW	258	for (h = 0; h < NF_MAX_HOOKS; h++)
	259	INIT_LIST_HEAD(&nf_hooks[i][h]);
	260	}
	261
	262	#ifdef CONFIG_PROC_FS
457c4cbc	263	proc_net_netfilter = proc_mkdir("netfilter", init_net.proc_net);
f6ebe77f HW	264	if (!proc_net_netfilter)
	265	panic("cannot create netfilter proc entry");
	266	#endif
	267
	268	if (netfilter_queue_init() < 0)
	269	panic("cannot initialize nf_queue");
	270	if (netfilter_log_init() < 0)
	271	panic("cannot initialize nf_log");
	272	}
4f536522 PM	273
	274	#ifdef CONFIG_SYSCTL
	275	struct ctl_path nf_net_netfilter_sysctl_path[] = {
f8572d8f EB	276	{ .procname = "net", },
f8572d8f EB	277	{ .procname = "netfilter", },
4f536522 PM	278	{ }
	279	};
	280	EXPORT_SYMBOL_GPL(nf_net_netfilter_sysctl_path);
	281	#endif /* CONFIG_SYSCTL */