[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);

struct nf_afinfo *nf_afinfo[NPROTO] __read_mostly;
EXPORT_SYMBOL(nf_afinfo);

int nf_register_afinfo(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(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);

/* 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] __read_mostly;
EXPORT_SYMBOL(nf_hooks);
static DEFINE_MUTEX(nf_hook_mutex);

int nf_register_hook(struct nf_hook_ops *reg)
{
	struct list_head *i;
	int err;

	err = mutex_lock_interruptible(&nf_hook_mutex);
	if (err < 0)
		return err;
	list_for_each(i, &nf_hooks[reg->pf][reg->hooknum]) {
		if (reg->priority < ((struct nf_hook_ops *)i)->priority)
			break;
	}
	list_add_rcu(&reg->list, i->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,
			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_cloned(*pskb) && !skb_clone_writable(*pskb, writable_len))
		goto copy_skb;
	if (skb_shared(*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);

void nf_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
			    __be32 from, __be32 to, int pseudohdr)
{
	__be32 diff[] = { ~from, to };
	if (skb->ip_summed != CHECKSUM_PARTIAL) {
		*sum = csum_fold(csum_partial(diff, sizeof(diff),
				~csum_unfold(*sum)));
		if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
			skb->csum = ~csum_partial(diff, sizeof(diff),
						~skb->csum);
	} else if (pseudohdr)
		*sum = ~csum_fold(csum_partial(diff, sizeof(diff),
				csum_unfold(*sum)));
}
EXPORT_SYMBOL(nf_proto_csum_replace4);

#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 < 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", 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");
}
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
e2b7606c	29	struct nf_afinfo *nf_afinfo[NPROTO] __read_mostly;
bce8032e PM	30	EXPORT_SYMBOL(nf_afinfo);
	31
	32	int nf_register_afinfo(struct nf_afinfo *afinfo)
	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
	45	void nf_unregister_afinfo(struct nf_afinfo *afinfo)
	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
f6ebe77f HW	54	/* In this code, we can be waiting indefinitely for userspace to
	55	* service a packet if a hook returns NF_QUEUE. We could keep a count
	56	* of skbuffs queued for userspace, and not deregister a hook unless
	57	* this is zero, but that sucks. Now, we simply check when the
	58	* packets come back: if the hook is gone, the packet is discarded. */
e2b7606c	59	struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS] __read_mostly;
f6ebe77f	60	EXPORT_SYMBOL(nf_hooks);
fd706d69	61	static DEFINE_MUTEX(nf_hook_mutex);
f6ebe77f HW	62
	63	int nf_register_hook(struct nf_hook_ops *reg)
	64	{
	65	struct list_head *i;
fd706d69	66	int err;
f6ebe77f	67
fd706d69 PM	68	err = mutex_lock_interruptible(&nf_hook_mutex);
	69	if (err < 0)
	70	return err;
f6ebe77f HW	71	list_for_each(i, &nf_hooks[reg->pf][reg->hooknum]) {
	72	if (reg->priority < ((struct nf_hook_ops *)i)->priority)
	73	break;
	74	}
	75	list_add_rcu(&reg->list, i->prev);
fd706d69	76	mutex_unlock(&nf_hook_mutex);
f6ebe77f HW	77	return 0;
	78	}
	79	EXPORT_SYMBOL(nf_register_hook);
	80
	81	void nf_unregister_hook(struct nf_hook_ops *reg)
	82	{
fd706d69	83	mutex_lock(&nf_hook_mutex);
f6ebe77f	84	list_del_rcu(&reg->list);
fd706d69	85	mutex_unlock(&nf_hook_mutex);
f6ebe77f HW	86
	87	synchronize_net();
	88	}
	89	EXPORT_SYMBOL(nf_unregister_hook);
	90
972d1cb1 PM	91	int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n)
	92	{
	93	unsigned int i;
	94	int err = 0;
	95
	96	for (i = 0; i < n; i++) {
	97	err = nf_register_hook(&reg[i]);
	98	if (err)
	99	goto err;
	100	}
	101	return err;
	102
	103	err:
	104	if (i > 0)
	105	nf_unregister_hooks(reg, i);
	106	return err;
	107	}
	108	EXPORT_SYMBOL(nf_register_hooks);
	109
	110	void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n)
	111	{
	112	unsigned int i;
	113
	114	for (i = 0; i < n; i++)
	115	nf_unregister_hook(&reg[i]);
	116	}
	117	EXPORT_SYMBOL(nf_unregister_hooks);
	118
f6ebe77f HW	119	unsigned int nf_iterate(struct list_head *head,
	120	struct sk_buff **skb,
	121	int hook,
	122	const struct net_device *indev,
	123	const struct net_device *outdev,
	124	struct list_head **i,
	125	int (okfn)(struct sk_buff ),
	126	int hook_thresh)
	127	{
	128	unsigned int verdict;
	129
	130	/*
	131	* The caller must not block between calls to this
	132	* function because of risk of continuing from deleted element.
	133	*/
	134	list_for_each_continue_rcu(*i, head) {
	135	struct nf_hook_ops elem = (struct nf_hook_ops )*i;
	136
	137	if (hook_thresh > elem->priority)
	138	continue;
	139
	140	/* Optimization: we don't need to hold module
601e68e1	141	reference here, since function can't sleep. --RR */
f6ebe77f HW	142	verdict = elem->hook(hook, skb, indev, outdev, okfn);
	143	if (verdict != NF_ACCEPT) {
	144	#ifdef CONFIG_NETFILTER_DEBUG
	145	if (unlikely((verdict & NF_VERDICT_MASK)
	146	> NF_MAX_VERDICT)) {
	147	NFDEBUG("Evil return from %p(%u).\n",
601e68e1	148	elem->hook, hook);
f6ebe77f HW	149	continue;
	150	}
	151	#endif
	152	if (verdict != NF_REPEAT)
	153	return verdict;
	154	i = (i)->prev;
	155	}
	156	}
	157	return NF_ACCEPT;
	158	}
	159
	160
	161	/* Returns 1 if okfn() needs to be executed by the caller,
	162	* -EPERM for NF_DROP, 0 otherwise. */
	163	int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb,
	164	struct net_device *indev,
	165	struct net_device *outdev,
	166	int (okfn)(struct sk_buff ),
	167	int hook_thresh)
	168	{
	169	struct list_head *elem;
	170	unsigned int verdict;
	171	int ret = 0;
	172
	173	/* We may already have this, but read-locks nest anyway */
	174	rcu_read_lock();
	175
	176	elem = &nf_hooks[pf][hook];
	177	next_hook:
	178	verdict = nf_iterate(&nf_hooks[pf][hook], pskb, hook, indev,
	179	outdev, &elem, okfn, hook_thresh);
	180	if (verdict == NF_ACCEPT \|\| verdict == NF_STOP) {
	181	ret = 1;
	182	goto unlock;
	183	} else if (verdict == NF_DROP) {
	184	kfree_skb(*pskb);
	185	ret = -EPERM;
	186	} else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
	187	NFDEBUG("nf_hook: Verdict = QUEUE.\n");
394f545d	188	if (!nf_queue(*pskb, elem, pf, hook, indev, outdev, okfn,
f6ebe77f HW	189	verdict >> NF_VERDICT_BITS))
	190	goto next_hook;
	191	}
	192	unlock:
	193	rcu_read_unlock();
	194	return ret;
	195	}
	196	EXPORT_SYMBOL(nf_hook_slow);
	197
	198
	199	int skb_make_writable(struct sk_buff **pskb, unsigned int writable_len)
	200	{
	201	struct sk_buff *nskb;
	202
	203	if (writable_len > (*pskb)->len)
	204	return 0;
	205
	206	/* Not exclusive use of packet? Must copy. */
334a8132 PM	207	if (skb_cloned(pskb) && !skb_clone_writable(pskb, writable_len))
	208	goto copy_skb;
	209	if (skb_shared(*pskb))
f6ebe77f HW	210	goto copy_skb;
	211
	212	return pskb_may_pull(*pskb, writable_len);
	213
	214	copy_skb:
	215	nskb = skb_copy(*pskb, GFP_ATOMIC);
	216	if (!nskb)
	217	return 0;
	218	BUG_ON(skb_is_nonlinear(nskb));
	219
	220	/* Rest of kernel will get very unhappy if we pass it a
	221	suddenly-orphaned skbuff */
	222	if ((*pskb)->sk)
	223	skb_set_owner_w(nskb, (*pskb)->sk);
	224	kfree_skb(*pskb);
	225	*pskb = nskb;
	226	return 1;
	227	}
	228	EXPORT_SYMBOL(skb_make_writable);
	229
43bc0ca7 AV	230	void nf_proto_csum_replace4(__sum16 sum, struct sk_buff skb,
43bc0ca7 AV	231	__be32 from, __be32 to, int pseudohdr)
4cf411de	232	{
43bc0ca7	233	__be32 diff[] = { ~from, to };
4cf411de	234	if (skb->ip_summed != CHECKSUM_PARTIAL) {
a47362a2	235	*sum = csum_fold(csum_partial(diff, sizeof(diff),
43bc0ca7	236	~csum_unfold(*sum)));
4cf411de	237	if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
a47362a2	238	skb->csum = ~csum_partial(diff, sizeof(diff),
43bc0ca7	239	~skb->csum);
4cf411de	240	} else if (pseudohdr)
a47362a2	241	*sum = ~csum_fold(csum_partial(diff, sizeof(diff),
43bc0ca7	242	csum_unfold(*sum)));
4cf411de	243	}
43bc0ca7	244	EXPORT_SYMBOL(nf_proto_csum_replace4);
f6ebe77f	245
5f79e0f9	246	#if defined(CONFIG_NF_CONNTRACK) \|\| defined(CONFIG_NF_CONNTRACK_MODULE)
f6ebe77f HW	247	/* This does not belong here, but locally generated errors need it if connection
	248	tracking in use: without this, connection may not be in hash table, and hence
	249	manufactured ICMP or RST packets will not be associated with it. */
	250	void (ip_ct_attach)(struct sk_buff , struct sk_buff *);
	251	EXPORT_SYMBOL(ip_ct_attach);
	252
	253	void nf_ct_attach(struct sk_buff new, struct sk_buff skb)
	254	{
	255	void (attach)(struct sk_buff , struct sk_buff *);
	256
c3a47ab3 PM	257	if (skb->nfct) {
	258	rcu_read_lock();
	259	attach = rcu_dereference(ip_ct_attach);
	260	if (attach)
	261	attach(new, skb);
	262	rcu_read_unlock();
f6ebe77f HW	263	}
	264	}
	265	EXPORT_SYMBOL(nf_ct_attach);
de6e05c4 YK	266
	267	void (nf_ct_destroy)(struct nf_conntrack );
	268	EXPORT_SYMBOL(nf_ct_destroy);
	269
	270	void nf_conntrack_destroy(struct nf_conntrack *nfct)
	271	{
	272	void (destroy)(struct nf_conntrack );
	273
	274	rcu_read_lock();
	275	destroy = rcu_dereference(nf_ct_destroy);
	276	BUG_ON(destroy == NULL);
	277	destroy(nfct);
	278	rcu_read_unlock();
	279	}
	280	EXPORT_SYMBOL(nf_conntrack_destroy);
	281	#endif /* CONFIG_NF_CONNTRACK */
f6ebe77f HW	282
	283	#ifdef CONFIG_PROC_FS
	284	struct proc_dir_entry *proc_net_netfilter;
	285	EXPORT_SYMBOL(proc_net_netfilter);
	286	#endif
	287
	288	void __init netfilter_init(void)
	289	{
	290	int i, h;
	291	for (i = 0; i < NPROTO; i++) {
	292	for (h = 0; h < NF_MAX_HOOKS; h++)
	293	INIT_LIST_HEAD(&nf_hooks[i][h]);
	294	}
	295
	296	#ifdef CONFIG_PROC_FS
457c4cbc	297	proc_net_netfilter = proc_mkdir("netfilter", init_net.proc_net);
f6ebe77f HW	298	if (!proc_net_netfilter)
	299	panic("cannot create netfilter proc entry");
	300	#endif
	301
	302	if (netfilter_queue_init() < 0)
	303	panic("cannot initialize nf_queue");
	304	if (netfilter_log_init() < 0)
	305	panic("cannot initialize nf_log");
	306	}