[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 <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);

int nf_register_afinfo(const struct nf_afinfo *afinfo)
{
	int err;

	err = mutex_lock_interruptible(&afinfo_mutex);
	if (err < 0)
		return err;
	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);

struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS] __read_mostly;
EXPORT_SYMBOL(nf_hooks);

#if defined(CONFIG_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);

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);
#if defined(CONFIG_JUMP_LABEL)
	static_key_slow_inc(&nf_hooks_needed[reg->pf][reg->hooknum]);
#endif
	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);
#if defined(CONFIG_JUMP_LABEL)
	static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
#endif
	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)
{
	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,
			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;
	struct nf_hook_ops *elem = list_entry_rcu(*i, struct nf_hook_ops, list);

	/*
	 * The caller must not block between calls to this
	 * function because of risk of continuing from deleted element.
	 */
	list_for_each_entry_continue_rcu(elem, head, list) {
		if (hook_thresh > elem->priority)
			continue;

		/* Optimization: we don't need to hold module
		   reference here, since function can't sleep. --RR */
repeat:
		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) {
				*i = &elem->list;
				return verdict;
			}
			goto repeat;
		}
	}
	*i = &elem->list;
	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_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, pf, hook, indev, outdev, okfn,
						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 *, struct sk_buff *) __rcu __read_mostly;
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 *) __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);

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

#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

#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");
}
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>
5a0e3ad6	22	#include <linux/slab.h>
457c4cbc	23	#include <net/net_namespace.h>
f6ebe77f HW	24	#include <net/sock.h>
	25
	26	#include "nf_internals.h"
	27
d486dd1f	28	static DEFINE_MUTEX(afinfo_mutex);
bce8032e	29
0906a372	30	const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly;
bce8032e PM	31	EXPORT_SYMBOL(nf_afinfo);
bce8032e PM	32
1e796fda	33	int nf_register_afinfo(const struct nf_afinfo *afinfo)
bce8032e	34	{
d486dd1f PM	35	int err;
	36
	37	err = mutex_lock_interruptible(&afinfo_mutex);
	38	if (err < 0)
	39	return err;
a9b3cd7f	40	RCU_INIT_POINTER(nf_afinfo[afinfo->family], afinfo);
d486dd1f	41	mutex_unlock(&afinfo_mutex);
bce8032e PM	42	return 0;
	43	}
	44	EXPORT_SYMBOL_GPL(nf_register_afinfo);
	45
1e796fda	46	void nf_unregister_afinfo(const struct nf_afinfo *afinfo)
bce8032e	47	{
d486dd1f	48	mutex_lock(&afinfo_mutex);
a9b3cd7f	49	RCU_INIT_POINTER(nf_afinfo[afinfo->family], NULL);
d486dd1f	50	mutex_unlock(&afinfo_mutex);
bce8032e PM	51	synchronize_rcu();
	52	}
	53	EXPORT_SYMBOL_GPL(nf_unregister_afinfo);
	54
7e9c6eeb	55	struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS] __read_mostly;
f6ebe77f	56	EXPORT_SYMBOL(nf_hooks);
a2d7ec58 ED	57
a2d7ec58 ED	58	#if defined(CONFIG_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 HW	64
	65	int nf_register_hook(struct nf_hook_ops *reg)
	66	{
4c610979	67	struct nf_hook_ops *elem;
fd706d69	68	int err;
f6ebe77f	69
fd706d69 PM	70	err = mutex_lock_interruptible(&nf_hook_mutex);
	71	if (err < 0)
	72	return err;
4c610979 LZ	73	list_for_each_entry(elem, &nf_hooks[reg->pf][reg->hooknum], list) {
4c610979 LZ	74	if (reg->priority < elem->priority)
f6ebe77f HW	75	break;
f6ebe77f HW	76	}
4c610979	77	list_add_rcu(&reg->list, elem->list.prev);
fd706d69	78	mutex_unlock(&nf_hook_mutex);
a2d7ec58	79	#if defined(CONFIG_JUMP_LABEL)
c5905afb	80	static_key_slow_inc(&nf_hooks_needed[reg->pf][reg->hooknum]);
a2d7ec58	81	#endif
f6ebe77f HW	82	return 0;
	83	}
	84	EXPORT_SYMBOL(nf_register_hook);
	85
	86	void nf_unregister_hook(struct nf_hook_ops *reg)
	87	{
fd706d69	88	mutex_lock(&nf_hook_mutex);
f6ebe77f	89	list_del_rcu(&reg->list);
fd706d69	90	mutex_unlock(&nf_hook_mutex);
a2d7ec58	91	#if defined(CONFIG_JUMP_LABEL)
c5905afb	92	static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
a2d7ec58	93	#endif
f6ebe77f HW	94	synchronize_net();
	95	}
	96	EXPORT_SYMBOL(nf_unregister_hook);
	97
972d1cb1 PM	98	int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n)
	99	{
	100	unsigned int i;
	101	int err = 0;
	102
	103	for (i = 0; i < n; i++) {
	104	err = nf_register_hook(&reg[i]);
	105	if (err)
	106	goto err;
	107	}
	108	return err;
	109
	110	err:
	111	if (i > 0)
	112	nf_unregister_hooks(reg, i);
	113	return err;
	114	}
	115	EXPORT_SYMBOL(nf_register_hooks);
	116
	117	void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n)
	118	{
f68c5301 CG	119	while (n-- > 0)
f68c5301 CG	120	nf_unregister_hook(&reg[n]);
972d1cb1 PM	121	}
	122	EXPORT_SYMBOL(nf_unregister_hooks);
	123
f6ebe77f	124	unsigned int nf_iterate(struct list_head *head,
3db05fea	125	struct sk_buff *skb,
76108cea	126	unsigned int hook,
f6ebe77f HW	127	const struct net_device *indev,
	128	const struct net_device *outdev,
	129	struct list_head **i,
	130	int (okfn)(struct sk_buff ),
	131	int hook_thresh)
	132	{
	133	unsigned int verdict;
6705e867	134	struct nf_hook_ops elem = list_entry_rcu(i, struct nf_hook_ops, list);
f6ebe77f HW	135
	136	/*
	137	* The caller must not block between calls to this
	138	* function because of risk of continuing from deleted element.
	139	*/
6705e867	140	list_for_each_entry_continue_rcu(elem, head, list) {
f6ebe77f HW	141	if (hook_thresh > elem->priority)
	142	continue;
	143
	144	/* Optimization: we don't need to hold module
601e68e1	145	reference here, since function can't sleep. --RR */
de9963f0	146	repeat:
f6ebe77f HW	147	verdict = elem->hook(hook, skb, indev, outdev, okfn);
	148	if (verdict != NF_ACCEPT) {
	149	#ifdef CONFIG_NETFILTER_DEBUG
	150	if (unlikely((verdict & NF_VERDICT_MASK)
	151	> NF_MAX_VERDICT)) {
	152	NFDEBUG("Evil return from %p(%u).\n",
601e68e1	153	elem->hook, hook);
f6ebe77f HW	154	continue;
	155	}
	156	#endif
6705e867 MW	157	if (verdict != NF_REPEAT) {
6705e867 MW	158	*i = &elem->list;
f6ebe77f	159	return verdict;
6705e867	160	}
de9963f0	161	goto repeat;
f6ebe77f HW	162	}
f6ebe77f HW	163	}
6705e867	164	*i = &elem->list;
f6ebe77f HW	165	return NF_ACCEPT;
	166	}
	167
	168
	169	/* Returns 1 if okfn() needs to be executed by the caller,
	170	* -EPERM for NF_DROP, 0 otherwise. */
76108cea	171	int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
f6ebe77f HW	172	struct net_device *indev,
	173	struct net_device *outdev,
	174	int (okfn)(struct sk_buff ),
	175	int hook_thresh)
	176	{
	177	struct list_head *elem;
	178	unsigned int verdict;
	179	int ret = 0;
	180
	181	/* We may already have this, but read-locks nest anyway */
	182	rcu_read_lock();
	183
	184	elem = &nf_hooks[pf][hook];
	185	next_hook:
3db05fea	186	verdict = nf_iterate(&nf_hooks[pf][hook], skb, hook, indev,
f6ebe77f HW	187	outdev, &elem, okfn, hook_thresh);
	188	if (verdict == NF_ACCEPT \|\| verdict == NF_STOP) {
	189	ret = 1;
da683650	190	} else if ((verdict & NF_VERDICT_MASK) == NF_DROP) {
3db05fea	191	kfree_skb(skb);
f615df76	192	ret = NF_DROP_GETERR(verdict);
da683650 EP	193	if (ret == 0)
da683650 EP	194	ret = -EPERM;
f9c63990	195	} else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
563e1232 FW	196	int err = nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
	197	verdict >> NF_VERDICT_QBITS);
	198	if (err < 0) {
	199	if (err == -ECANCELED)
06cdb634	200	goto next_hook;
563e1232	201	if (err == -ESRCH &&
94b27cc3 FW	202	(verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
94b27cc3 FW	203	goto next_hook;
06cdb634 FW	204	kfree_skb(skb);
06cdb634 FW	205	}
f6ebe77f	206	}
f6ebe77f HW	207	rcu_read_unlock();
	208	return ret;
	209	}
	210	EXPORT_SYMBOL(nf_hook_slow);
	211
	212
37d41879	213	int skb_make_writable(struct sk_buff *skb, unsigned int writable_len)
f6ebe77f	214	{
37d41879	215	if (writable_len > skb->len)
f6ebe77f HW	216	return 0;
	217
	218	/* Not exclusive use of packet? Must copy. */
37d41879 HX	219	if (!skb_cloned(skb)) {
	220	if (writable_len <= skb_headlen(skb))
	221	return 1;
	222	} else if (skb_clone_writable(skb, writable_len))
	223	return 1;
	224
	225	if (writable_len <= skb_headlen(skb))
	226	writable_len = 0;
	227	else
	228	writable_len -= skb_headlen(skb);
	229
	230	return !!__pskb_pull_tail(skb, writable_len);
f6ebe77f HW	231	}
	232	EXPORT_SYMBOL(skb_make_writable);
	233
c0cd1156	234	#if IS_ENABLED(CONFIG_NF_CONNTRACK)
f6ebe77f HW	235	/* This does not belong here, but locally generated errors need it if connection
	236	tracking in use: without this, connection may not be in hash table, and hence
	237	manufactured ICMP or RST packets will not be associated with it. */
0e60ebe0	238	void (ip_ct_attach)(struct sk_buff , struct sk_buff *) __rcu __read_mostly;
f6ebe77f HW	239	EXPORT_SYMBOL(ip_ct_attach);
	240
	241	void nf_ct_attach(struct sk_buff new, struct sk_buff skb)
	242	{
	243	void (attach)(struct sk_buff , struct sk_buff *);
	244
c3a47ab3 PM	245	if (skb->nfct) {
	246	rcu_read_lock();
	247	attach = rcu_dereference(ip_ct_attach);
	248	if (attach)
	249	attach(new, skb);
	250	rcu_read_unlock();
f6ebe77f HW	251	}
	252	}
	253	EXPORT_SYMBOL(nf_ct_attach);
de6e05c4	254
0e60ebe0	255	void (nf_ct_destroy)(struct nf_conntrack ) __rcu __read_mostly;
de6e05c4 YK	256	EXPORT_SYMBOL(nf_ct_destroy);
	257
	258	void nf_conntrack_destroy(struct nf_conntrack *nfct)
	259	{
	260	void (destroy)(struct nf_conntrack );
	261
	262	rcu_read_lock();
	263	destroy = rcu_dereference(nf_ct_destroy);
	264	BUG_ON(destroy == NULL);
	265	destroy(nfct);
	266	rcu_read_unlock();
	267	}
	268	EXPORT_SYMBOL(nf_conntrack_destroy);
9cb01766	269
5a05fae5	270	struct nfq_ct_hook __rcu *nfq_ct_hook __read_mostly;
9cb01766 PNA	271	EXPORT_SYMBOL_GPL(nfq_ct_hook);
9cb01766 PNA	272
d584a61a PNA	273	struct nfq_ct_nat_hook __rcu *nfq_ct_nat_hook __read_mostly;
	274	EXPORT_SYMBOL_GPL(nfq_ct_nat_hook);
	275
de6e05c4	276	#endif /* CONFIG_NF_CONNTRACK */
f6ebe77f	277
c7232c99 PM	278	#ifdef CONFIG_NF_NAT_NEEDED
	279	void (nf_nat_decode_session_hook)(struct sk_buff , struct flowi *);
	280	EXPORT_SYMBOL(nf_nat_decode_session_hook);
	281	#endif
	282
f6ebe77f HW	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;
7e9c6eeb	291	for (i = 0; i < ARRAY_SIZE(nf_hooks); i++) {
f6ebe77f HW	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	}