[deliverable/linux.git] / net / netfilter / nf_conntrack_helper.c

/* Helper handling for netfilter. */

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
 * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/types.h>
#include <linux/netfilter.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/vmalloc.h>
#include <linux/stddef.h>
#include <linux/random.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/rculist.h>
#include <linux/rtnetlink.h>

#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_l3proto.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_extend.h>

static DEFINE_MUTEX(nf_ct_helper_mutex);
static struct hlist_head *nf_ct_helper_hash __read_mostly;
static unsigned int nf_ct_helper_hsize __read_mostly;
static unsigned int nf_ct_helper_count __read_mostly;


/* Stupid hash, but collision free for the default registrations of the
 * helpers currently in the kernel. */
static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
{
	return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^
		(__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
}

static struct nf_conntrack_helper *
__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
{
	struct nf_conntrack_helper *helper;
	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
	struct hlist_node *n;
	unsigned int h;

	if (!nf_ct_helper_count)
		return NULL;

	h = helper_hash(tuple);
	hlist_for_each_entry_rcu(helper, n, &nf_ct_helper_hash[h], hnode) {
		if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
			return helper;
	}
	return NULL;
}

struct nf_conntrack_helper *
__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
{
	struct nf_conntrack_helper *h;
	struct hlist_node *n;
	unsigned int i;

	for (i = 0; i < nf_ct_helper_hsize; i++) {
		hlist_for_each_entry_rcu(h, n, &nf_ct_helper_hash[i], hnode) {
			if (!strcmp(h->name, name) &&
			    h->tuple.src.l3num == l3num &&
			    h->tuple.dst.protonum == protonum)
				return h;
		}
	}
	return NULL;
}
EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);

struct nf_conntrack_helper *
nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
{
	struct nf_conntrack_helper *h;

	h = __nf_conntrack_helper_find(name, l3num, protonum);
#ifdef CONFIG_MODULES
	if (h == NULL) {
		if (request_module("nfct-helper-%s", name) == 0)
			h = __nf_conntrack_helper_find(name, l3num, protonum);
	}
#endif
	if (h != NULL && !try_module_get(h->me))
		h = NULL;

	return h;
}
EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);

struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp)
{
	struct nf_conn_help *help;

	help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, gfp);
	if (help)
		INIT_HLIST_HEAD(&help->expectations);
	else
		pr_debug("failed to add helper extension area");
	return help;
}
EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);

int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
			      gfp_t flags)
{
	struct nf_conntrack_helper *helper = NULL;
	struct nf_conn_help *help;
	int ret = 0;

	if (tmpl != NULL) {
		help = nfct_help(tmpl);
		if (help != NULL)
			helper = help->helper;
	}

	help = nfct_help(ct);
	if (helper == NULL)
		helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
	if (helper == NULL) {
		if (help)
			rcu_assign_pointer(help->helper, NULL);
		goto out;
	}

	if (help == NULL) {
		help = nf_ct_helper_ext_add(ct, flags);
		if (help == NULL) {
			ret = -ENOMEM;
			goto out;
		}
	} else {
		memset(&help->help, 0, sizeof(help->help));
	}

	rcu_assign_pointer(help->helper, helper);
out:
	return ret;
}
EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);

static inline int unhelp(struct nf_conntrack_tuple_hash *i,
			 const struct nf_conntrack_helper *me)
{
	struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
	struct nf_conn_help *help = nfct_help(ct);

	if (help && rcu_dereference_protected(
			help->helper,
			lockdep_is_held(&nf_conntrack_lock)
			) == me) {
		nf_conntrack_event(IPCT_HELPER, ct);
		rcu_assign_pointer(help->helper, NULL);
	}
	return 0;
}

void nf_ct_helper_destroy(struct nf_conn *ct)
{
	struct nf_conn_help *help = nfct_help(ct);
	struct nf_conntrack_helper *helper;

	if (help) {
		rcu_read_lock();
		helper = rcu_dereference(help->helper);
		if (helper && helper->destroy)
			helper->destroy(ct);
		rcu_read_unlock();
	}
}

int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
{
	unsigned int h = helper_hash(&me->tuple);

	BUG_ON(me->expect_policy == NULL);
	BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
	BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);

	mutex_lock(&nf_ct_helper_mutex);
	hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
	nf_ct_helper_count++;
	mutex_unlock(&nf_ct_helper_mutex);

	return 0;
}
EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);

static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
					     struct net *net)
{
	struct nf_conntrack_tuple_hash *h;
	struct nf_conntrack_expect *exp;
	const struct hlist_node *n, *next;
	const struct hlist_nulls_node *nn;
	unsigned int i;

	/* Get rid of expectations */
	for (i = 0; i < nf_ct_expect_hsize; i++) {
		hlist_for_each_entry_safe(exp, n, next,
					  &net->ct.expect_hash[i], hnode) {
			struct nf_conn_help *help = nfct_help(exp->master);
			if ((rcu_dereference_protected(
					help->helper,
					lockdep_is_held(&nf_conntrack_lock)
					) == me || exp->helper == me) &&
			    del_timer(&exp->timeout)) {
				nf_ct_unlink_expect(exp);
				nf_ct_expect_put(exp);
			}
		}
	}

	/* Get rid of expecteds, set helpers to NULL. */
	hlist_nulls_for_each_entry(h, nn, &net->ct.unconfirmed, hnnode)
		unhelp(h, me);
	for (i = 0; i < net->ct.htable_size; i++) {
		hlist_nulls_for_each_entry(h, nn, &net->ct.hash[i], hnnode)
			unhelp(h, me);
	}
}

void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
{
	struct net *net;

	mutex_lock(&nf_ct_helper_mutex);
	hlist_del_rcu(&me->hnode);
	nf_ct_helper_count--;
	mutex_unlock(&nf_ct_helper_mutex);

	/* Make sure every nothing is still using the helper unless its a
	 * connection in the hash.
	 */
	synchronize_rcu();

	rtnl_lock();
	spin_lock_bh(&nf_conntrack_lock);
	for_each_net(net)
		__nf_conntrack_helper_unregister(me, net);
	spin_unlock_bh(&nf_conntrack_lock);
	rtnl_unlock();
}
EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);

static struct nf_ct_ext_type helper_extend __read_mostly = {
	.len	= sizeof(struct nf_conn_help),
	.align	= __alignof__(struct nf_conn_help),
	.id	= NF_CT_EXT_HELPER,
};

int nf_conntrack_helper_init(void)
{
	int err;

	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
	nf_ct_helper_hash = nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
	if (!nf_ct_helper_hash)
		return -ENOMEM;

	err = nf_ct_extend_register(&helper_extend);
	if (err < 0)
		goto err1;

	return 0;

err1:
	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
	return err;
}

void nf_conntrack_helper_fini(void)
{
	nf_ct_extend_unregister(&helper_extend);
	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
}
Commit	Line	Data
	1	/* Helper handling for netfilter. */
	2
	3	/* (C) 1999-2001 Paul `Rusty' Russell
	4	* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
	5	* (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*/
	11
	12	#include <linux/types.h>
	13	#include <linux/netfilter.h>
	14	#include <linux/module.h>
	15	#include <linux/skbuff.h>
	16	#include <linux/vmalloc.h>
	17	#include <linux/stddef.h>
	18	#include <linux/random.h>
	19	#include <linux/err.h>
	20	#include <linux/kernel.h>
	21	#include <linux/netdevice.h>
	22	#include <linux/rculist.h>
	23	#include <linux/rtnetlink.h>
	24
	25	#include <net/netfilter/nf_conntrack.h>
	26	#include <net/netfilter/nf_conntrack_l3proto.h>
	27	#include <net/netfilter/nf_conntrack_l4proto.h>
	28	#include <net/netfilter/nf_conntrack_helper.h>
	29	#include <net/netfilter/nf_conntrack_core.h>
	30	#include <net/netfilter/nf_conntrack_extend.h>
	31
	32	static DEFINE_MUTEX(nf_ct_helper_mutex);
	33	static struct hlist_head *nf_ct_helper_hash __read_mostly;
	34	static unsigned int nf_ct_helper_hsize __read_mostly;
	35	static unsigned int nf_ct_helper_count __read_mostly;
	36
	37
	38	/* Stupid hash, but collision free for the default registrations of the
	39	* helpers currently in the kernel. */
	40	static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
	41	{
	42	return (((tuple->src.l3num << 8) \| tuple->dst.protonum) ^
	43	(__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
	44	}
	45
	46	static struct nf_conntrack_helper *
	47	__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
	48	{
	49	struct nf_conntrack_helper *helper;
	50	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
	51	struct hlist_node *n;
	52	unsigned int h;
	53
	54	if (!nf_ct_helper_count)
	55	return NULL;
	56
	57	h = helper_hash(tuple);
	58	hlist_for_each_entry_rcu(helper, n, &nf_ct_helper_hash[h], hnode) {
	59	if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
	60	return helper;
	61	}
	62	return NULL;
	63	}
	64
	65	struct nf_conntrack_helper *
	66	__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
	67	{
	68	struct nf_conntrack_helper *h;
	69	struct hlist_node *n;
	70	unsigned int i;
	71
	72	for (i = 0; i < nf_ct_helper_hsize; i++) {
	73	hlist_for_each_entry_rcu(h, n, &nf_ct_helper_hash[i], hnode) {
	74	if (!strcmp(h->name, name) &&
	75	h->tuple.src.l3num == l3num &&
	76	h->tuple.dst.protonum == protonum)
	77	return h;
	78	}
	79	}
	80	return NULL;
	81	}
	82	EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
	83
	84	struct nf_conntrack_helper *
	85	nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
	86	{
	87	struct nf_conntrack_helper *h;
	88
	89	h = __nf_conntrack_helper_find(name, l3num, protonum);
	90	#ifdef CONFIG_MODULES
	91	if (h == NULL) {
	92	if (request_module("nfct-helper-%s", name) == 0)
	93	h = __nf_conntrack_helper_find(name, l3num, protonum);
	94	}
	95	#endif
	96	if (h != NULL && !try_module_get(h->me))
	97	h = NULL;
	98
	99	return h;
	100	}
	101	EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
	102
	103	struct nf_conn_help nf_ct_helper_ext_add(struct nf_conn ct, gfp_t gfp)
	104	{
	105	struct nf_conn_help *help;
	106
	107	help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, gfp);
	108	if (help)
	109	INIT_HLIST_HEAD(&help->expectations);
	110	else
	111	pr_debug("failed to add helper extension area");
	112	return help;
	113	}
	114	EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
	115
	116	int __nf_ct_try_assign_helper(struct nf_conn ct, struct nf_conn tmpl,
	117	gfp_t flags)
	118	{
	119	struct nf_conntrack_helper *helper = NULL;
	120	struct nf_conn_help *help;
	121	int ret = 0;
	122
	123	if (tmpl != NULL) {
	124	help = nfct_help(tmpl);
	125	if (help != NULL)
	126	helper = help->helper;
	127	}
	128
	129	help = nfct_help(ct);
	130	if (helper == NULL)
	131	helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
	132	if (helper == NULL) {
	133	if (help)
	134	rcu_assign_pointer(help->helper, NULL);
	135	goto out;
	136	}
	137
	138	if (help == NULL) {
	139	help = nf_ct_helper_ext_add(ct, flags);
	140	if (help == NULL) {
	141	ret = -ENOMEM;
	142	goto out;
	143	}
	144	} else {
	145	memset(&help->help, 0, sizeof(help->help));
	146	}
	147
	148	rcu_assign_pointer(help->helper, helper);
	149	out:
	150	return ret;
	151	}
	152	EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
	153
	154	static inline int unhelp(struct nf_conntrack_tuple_hash *i,
	155	const struct nf_conntrack_helper *me)
	156	{
	157	struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
	158	struct nf_conn_help *help = nfct_help(ct);
	159
	160	if (help && rcu_dereference_protected(
	161	help->helper,
	162	lockdep_is_held(&nf_conntrack_lock)
	163	) == me) {
	164	nf_conntrack_event(IPCT_HELPER, ct);
	165	rcu_assign_pointer(help->helper, NULL);
	166	}
	167	return 0;
	168	}
	169
	170	void nf_ct_helper_destroy(struct nf_conn *ct)
	171	{
	172	struct nf_conn_help *help = nfct_help(ct);
	173	struct nf_conntrack_helper *helper;
	174
	175	if (help) {
	176	rcu_read_lock();
	177	helper = rcu_dereference(help->helper);
	178	if (helper && helper->destroy)
	179	helper->destroy(ct);
	180	rcu_read_unlock();
	181	}
	182	}
	183
	184	int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
	185	{
	186	unsigned int h = helper_hash(&me->tuple);
	187
	188	BUG_ON(me->expect_policy == NULL);
	189	BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
	190	BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
	191
	192	mutex_lock(&nf_ct_helper_mutex);
	193	hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
	194	nf_ct_helper_count++;
	195	mutex_unlock(&nf_ct_helper_mutex);
	196
	197	return 0;
	198	}
	199	EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
	200
	201	static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
	202	struct net *net)
	203	{
	204	struct nf_conntrack_tuple_hash *h;
	205	struct nf_conntrack_expect *exp;
	206	const struct hlist_node n, next;
	207	const struct hlist_nulls_node *nn;
	208	unsigned int i;
	209
	210	/* Get rid of expectations */
	211	for (i = 0; i < nf_ct_expect_hsize; i++) {
	212	hlist_for_each_entry_safe(exp, n, next,
	213	&net->ct.expect_hash[i], hnode) {
	214	struct nf_conn_help *help = nfct_help(exp->master);
	215	if ((rcu_dereference_protected(
	216	help->helper,
	217	lockdep_is_held(&nf_conntrack_lock)
	218	) == me \|\| exp->helper == me) &&
	219	del_timer(&exp->timeout)) {
	220	nf_ct_unlink_expect(exp);
	221	nf_ct_expect_put(exp);
	222	}
	223	}
	224	}
	225
	226	/* Get rid of expecteds, set helpers to NULL. */
	227	hlist_nulls_for_each_entry(h, nn, &net->ct.unconfirmed, hnnode)
	228	unhelp(h, me);
	229	for (i = 0; i < net->ct.htable_size; i++) {
	230	hlist_nulls_for_each_entry(h, nn, &net->ct.hash[i], hnnode)
	231	unhelp(h, me);
	232	}
	233	}
	234
	235	void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
	236	{
	237	struct net *net;
	238
	239	mutex_lock(&nf_ct_helper_mutex);
	240	hlist_del_rcu(&me->hnode);
	241	nf_ct_helper_count--;
	242	mutex_unlock(&nf_ct_helper_mutex);
	243
	244	/* Make sure every nothing is still using the helper unless its a
	245	* connection in the hash.
	246	*/
	247	synchronize_rcu();
	248
	249	rtnl_lock();
	250	spin_lock_bh(&nf_conntrack_lock);
	251	for_each_net(net)
	252	__nf_conntrack_helper_unregister(me, net);
	253	spin_unlock_bh(&nf_conntrack_lock);
	254	rtnl_unlock();
	255	}
	256	EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
	257
	258	static struct nf_ct_ext_type helper_extend __read_mostly = {
	259	.len = sizeof(struct nf_conn_help),
	260	.align = __alignof__(struct nf_conn_help),
	261	.id = NF_CT_EXT_HELPER,
	262	};
	263
	264	int nf_conntrack_helper_init(void)
	265	{
	266	int err;
	267
	268	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
	269	nf_ct_helper_hash = nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
	270	if (!nf_ct_helper_hash)
	271	return -ENOMEM;
	272
	273	err = nf_ct_extend_register(&helper_extend);
	274	if (err < 0)
	275	goto err1;
	276
	277	return 0;
	278
	279	err1:
	280	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
	281	return err;
	282	}
	283
	284	void nf_conntrack_helper_fini(void)
	285	{
	286	nf_ct_extend_unregister(&helper_extend);
	287	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
	288	}