[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.
 *
 * February 2000: Modified by James Morris to have 1 queue per protocol.
 * 15-Mar-2000:   Added NF_REPEAT --RR.
 * 08-May-2003:	  Internal logging interface added by Jozsef Kadlecsik.
 */
#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/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_shared(*pskb) || skb_cloned(*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((char *)diff, sizeof(diff),
				~csum_unfold(*sum)));
		if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
			skb->csum = ~csum_partial((char *)diff, sizeof(diff),
						~skb->csum);
	} else if (pseudohdr)
		*sum = ~csum_fold(csum_partial((char *)diff, sizeof(diff),
				csum_unfold(*sum)));
}
EXPORT_SYMBOL(nf_proto_csum_replace4);

/* 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);

#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", 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
f6ebe77f HW	1	/* netfilter.c: look after the filters for various protocols.
	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.
	8	*
	9	* February 2000: Modified by James Morris to have 1 queue per protocol.
	10	* 15-Mar-2000: Added NF_REPEAT --RR.
	11	* 08-May-2003: Internal logging interface added by Jozsef Kadlecsik.
	12	*/
f6ebe77f HW	13	#include <linux/kernel.h>
	14	#include <linux/netfilter.h>
	15	#include <net/protocol.h>
	16	#include <linux/init.h>
	17	#include <linux/skbuff.h>
	18	#include <linux/wait.h>
	19	#include <linux/module.h>
	20	#include <linux/interrupt.h>
	21	#include <linux/if.h>
	22	#include <linux/netdevice.h>
	23	#include <linux/inetdevice.h>
	24	#include <linux/proc_fs.h>
d486dd1f	25	#include <linux/mutex.h>
f6ebe77f HW	26	#include <net/sock.h>
	27
	28	#include "nf_internals.h"
	29
d486dd1f	30	static DEFINE_MUTEX(afinfo_mutex);
bce8032e	31
e2b7606c	32	struct nf_afinfo *nf_afinfo[NPROTO] __read_mostly;
bce8032e PM	33	EXPORT_SYMBOL(nf_afinfo);
	34
	35	int nf_register_afinfo(struct nf_afinfo *afinfo)
	36	{
d486dd1f PM	37	int err;
	38
	39	err = mutex_lock_interruptible(&afinfo_mutex);
	40	if (err < 0)
	41	return err;
bce8032e	42	rcu_assign_pointer(nf_afinfo[afinfo->family], afinfo);
d486dd1f	43	mutex_unlock(&afinfo_mutex);
bce8032e PM	44	return 0;
	45	}
	46	EXPORT_SYMBOL_GPL(nf_register_afinfo);
	47
	48	void nf_unregister_afinfo(struct nf_afinfo *afinfo)
	49	{
d486dd1f	50	mutex_lock(&afinfo_mutex);
bce8032e	51	rcu_assign_pointer(nf_afinfo[afinfo->family], NULL);
d486dd1f	52	mutex_unlock(&afinfo_mutex);
bce8032e PM	53	synchronize_rcu();
	54	}
	55	EXPORT_SYMBOL_GPL(nf_unregister_afinfo);
	56
f6ebe77f HW	57	/* In this code, we can be waiting indefinitely for userspace to
	58	* service a packet if a hook returns NF_QUEUE. We could keep a count
	59	* of skbuffs queued for userspace, and not deregister a hook unless
	60	* this is zero, but that sucks. Now, we simply check when the
	61	* packets come back: if the hook is gone, the packet is discarded. */
e2b7606c	62	struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS] __read_mostly;
f6ebe77f	63	EXPORT_SYMBOL(nf_hooks);
fd706d69	64	static DEFINE_MUTEX(nf_hook_mutex);
f6ebe77f HW	65
	66	int nf_register_hook(struct nf_hook_ops *reg)
	67	{
	68	struct list_head *i;
fd706d69	69	int err;
f6ebe77f	70
fd706d69 PM	71	err = mutex_lock_interruptible(&nf_hook_mutex);
	72	if (err < 0)
	73	return err;
f6ebe77f HW	74	list_for_each(i, &nf_hooks[reg->pf][reg->hooknum]) {
	75	if (reg->priority < ((struct nf_hook_ops *)i)->priority)
	76	break;
	77	}
	78	list_add_rcu(&reg->list, i->prev);
fd706d69	79	mutex_unlock(&nf_hook_mutex);
f6ebe77f HW	80	return 0;
	81	}
	82	EXPORT_SYMBOL(nf_register_hook);
	83
	84	void nf_unregister_hook(struct nf_hook_ops *reg)
	85	{
fd706d69	86	mutex_lock(&nf_hook_mutex);
f6ebe77f	87	list_del_rcu(&reg->list);
fd706d69	88	mutex_unlock(&nf_hook_mutex);
f6ebe77f HW	89
	90	synchronize_net();
	91	}
	92	EXPORT_SYMBOL(nf_unregister_hook);
	93
972d1cb1 PM	94	int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n)
	95	{
	96	unsigned int i;
	97	int err = 0;
	98
	99	for (i = 0; i < n; i++) {
	100	err = nf_register_hook(&reg[i]);
	101	if (err)
	102	goto err;
	103	}
	104	return err;
	105
	106	err:
	107	if (i > 0)
	108	nf_unregister_hooks(reg, i);
	109	return err;
	110	}
	111	EXPORT_SYMBOL(nf_register_hooks);
	112
	113	void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n)
	114	{
	115	unsigned int i;
	116
	117	for (i = 0; i < n; i++)
	118	nf_unregister_hook(&reg[i]);
	119	}
	120	EXPORT_SYMBOL(nf_unregister_hooks);
	121
f6ebe77f HW	122	unsigned int nf_iterate(struct list_head *head,
	123	struct sk_buff **skb,
	124	int hook,
	125	const struct net_device *indev,
	126	const struct net_device *outdev,
	127	struct list_head **i,
	128	int (okfn)(struct sk_buff ),
	129	int hook_thresh)
	130	{
	131	unsigned int verdict;
	132
	133	/*
	134	* The caller must not block between calls to this
	135	* function because of risk of continuing from deleted element.
	136	*/
	137	list_for_each_continue_rcu(*i, head) {
	138	struct nf_hook_ops elem = (struct nf_hook_ops )*i;
	139
	140	if (hook_thresh > elem->priority)
	141	continue;
	142
	143	/* Optimization: we don't need to hold module
	144	reference here, since function can't sleep. --RR */
	145	verdict = elem->hook(hook, skb, indev, outdev, okfn);
	146	if (verdict != NF_ACCEPT) {
	147	#ifdef CONFIG_NETFILTER_DEBUG
	148	if (unlikely((verdict & NF_VERDICT_MASK)
	149	> NF_MAX_VERDICT)) {
	150	NFDEBUG("Evil return from %p(%u).\n",
	151	elem->hook, hook);
	152	continue;
	153	}
	154	#endif
	155	if (verdict != NF_REPEAT)
	156	return verdict;
	157	i = (i)->prev;
	158	}
	159	}
	160	return NF_ACCEPT;
	161	}
	162
	163
	164	/* Returns 1 if okfn() needs to be executed by the caller,
	165	* -EPERM for NF_DROP, 0 otherwise. */
	166	int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb,
	167	struct net_device *indev,
	168	struct net_device *outdev,
	169	int (okfn)(struct sk_buff ),
	170	int hook_thresh)
	171	{
	172	struct list_head *elem;
	173	unsigned int verdict;
	174	int ret = 0;
	175
	176	/* We may already have this, but read-locks nest anyway */
	177	rcu_read_lock();
	178
	179	elem = &nf_hooks[pf][hook];
	180	next_hook:
	181	verdict = nf_iterate(&nf_hooks[pf][hook], pskb, hook, indev,
	182	outdev, &elem, okfn, hook_thresh);
	183	if (verdict == NF_ACCEPT \|\| verdict == NF_STOP) {
	184	ret = 1;
	185	goto unlock;
186	} else if (verdict == NF_DROP) {
187	kfree_skb(*pskb);
188	ret = -EPERM;
189	} else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
190	NFDEBUG("nf_hook: Verdict = QUEUE.\n");
394f545d	191	if (!nf_queue(*pskb, elem, pf, hook, indev, outdev, okfn,
f6ebe77f HW	192	verdict >> NF_VERDICT_BITS))
	193	goto next_hook;
	194	}
	195	unlock:
	196	rcu_read_unlock();
	197	return ret;
	198	}
	199	EXPORT_SYMBOL(nf_hook_slow);
	200
	201
	202	int skb_make_writable(struct sk_buff **pskb, unsigned int writable_len)
	203	{
	204	struct sk_buff *nskb;
	205
	206	if (writable_len > (*pskb)->len)
	207	return 0;
	208
	209	/* Not exclusive use of packet? Must copy. */
	210	if (skb_shared(pskb) \|\| skb_cloned(pskb))
	211	goto copy_skb;
	212
	213	return pskb_may_pull(*pskb, writable_len);
	214
	215	copy_skb:
	216	nskb = skb_copy(*pskb, GFP_ATOMIC);
	217	if (!nskb)
	218	return 0;
	219	BUG_ON(skb_is_nonlinear(nskb));
	220
	221	/* Rest of kernel will get very unhappy if we pass it a
	222	suddenly-orphaned skbuff */
	223	if ((*pskb)->sk)
	224	skb_set_owner_w(nskb, (*pskb)->sk);
	225	kfree_skb(*pskb);
	226	*pskb = nskb;
	227	return 1;
	228	}
	229	EXPORT_SYMBOL(skb_make_writable);
	230
43bc0ca7 AV	231	void nf_proto_csum_replace4(__sum16 sum, struct sk_buff skb,
43bc0ca7 AV	232	__be32 from, __be32 to, int pseudohdr)
4cf411de	233	{
43bc0ca7	234	__be32 diff[] = { ~from, to };
4cf411de	235	if (skb->ip_summed != CHECKSUM_PARTIAL) {
43bc0ca7 AV	236	sum = csum_fold(csum_partial((char )diff, sizeof(diff),
43bc0ca7 AV	237	~csum_unfold(*sum)));
4cf411de	238	if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
43bc0ca7 AV	239	skb->csum = ~csum_partial((char *)diff, sizeof(diff),
43bc0ca7 AV	240	~skb->csum);
4cf411de	241	} else if (pseudohdr)
43bc0ca7 AV	242	sum = ~csum_fold(csum_partial((char )diff, sizeof(diff),
43bc0ca7 AV	243	csum_unfold(*sum)));
4cf411de	244	}
43bc0ca7	245	EXPORT_SYMBOL(nf_proto_csum_replace4);
f6ebe77f HW	246
	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);
	266
	267	#ifdef CONFIG_PROC_FS
	268	struct proc_dir_entry *proc_net_netfilter;
	269	EXPORT_SYMBOL(proc_net_netfilter);
	270	#endif
	271
	272	void __init netfilter_init(void)
	273	{
	274	int i, h;
	275	for (i = 0; i < NPROTO; i++) {
	276	for (h = 0; h < NF_MAX_HOOKS; h++)
	277	INIT_LIST_HEAD(&nf_hooks[i][h]);
	278	}
	279
	280	#ifdef CONFIG_PROC_FS
	281	proc_net_netfilter = proc_mkdir("netfilter", proc_net);
	282	if (!proc_net_netfilter)
	283	panic("cannot create netfilter proc entry");
	284	#endif
	285
	286	if (netfilter_queue_init() < 0)
	287	panic("cannot initialize nf_queue");
	288	if (netfilter_log_init() < 0)
	289	panic("cannot initialize nf_log");
	290	}