[mirror_ubuntu-artful-kernel.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);
struct hlist_head *nf_ct_helper_hash __read_mostly;
EXPORT_SYMBOL_GPL(nf_ct_helper_hash);
unsigned int nf_ct_helper_hsize __read_mostly;
EXPORT_SYMBOL_GPL(nf_ct_helper_hsize);
static unsigned int nf_ct_helper_count __read_mostly;

static bool nf_ct_auto_assign_helper __read_mostly = true;
module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
MODULE_PARM_DESC(nf_conntrack_helper,
		 "Enable automatic conntrack helper assignment (default 1)");

#ifdef CONFIG_SYSCTL
static struct ctl_table helper_sysctl_table[] = {
	{
		.procname	= "nf_conntrack_helper",
		.data		= &init_net.ct.sysctl_auto_assign_helper,
		.maxlen		= sizeof(unsigned int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
	{}
};

static int nf_conntrack_helper_init_sysctl(struct net *net)
{
	struct ctl_table *table;

	table = kmemdup(helper_sysctl_table, sizeof(helper_sysctl_table),
			GFP_KERNEL);
	if (!table)
		goto out;

	table[0].data = &net->ct.sysctl_auto_assign_helper;

	net->ct.helper_sysctl_header =
		register_net_sysctl(net, "net/netfilter", table);

	if (!net->ct.helper_sysctl_header) {
		pr_err("nf_conntrack_helper: can't register to sysctl.\n");
		goto out_register;
	}
	return 0;

out_register:
	kfree(table);
out:
	return -ENOMEM;
}

static void nf_conntrack_helper_fini_sysctl(struct net *net)
{
	struct ctl_table *table;

	table = net->ct.helper_sysctl_header->ctl_table_arg;
	unregister_net_sysctl_table(net->ct.helper_sysctl_header);
	kfree(table);
}
#else
static int nf_conntrack_helper_init_sysctl(struct net *net)
{
	return 0;
}

static void nf_conntrack_helper_fini_sysctl(struct net *net)
{
}
#endif /* CONFIG_SYSCTL */

/* 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,
		     struct nf_conntrack_helper *helper, gfp_t gfp)
{
	struct nf_conn_help *help;

	help = nf_ct_ext_add_length(ct, NF_CT_EXT_HELPER,
				    helper->data_len, 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;
	struct net *net = nf_ct_net(ct);
	int ret = 0;

	/* We already got a helper explicitly attached. The function
	 * nf_conntrack_alter_reply - in case NAT is in use - asks for looking
	 * the helper up again. Since now the user is in full control of
	 * making consistent helper configurations, skip this automatic
	 * re-lookup, otherwise we'll lose the helper.
	 */
	if (test_bit(IPS_HELPER_BIT, &ct->status))
		return 0;

	if (tmpl != NULL) {
		help = nfct_help(tmpl);
		if (help != NULL) {
			helper = help->helper;
			set_bit(IPS_HELPER_BIT, &ct->status);
		}
	}

	help = nfct_help(ct);
	if (net->ct.sysctl_auto_assign_helper && helper == NULL) {
		helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
		if (unlikely(!net->ct.auto_assign_helper_warned && helper)) {
			pr_info("nf_conntrack: automatic helper "
				"assignment is deprecated and it will "
				"be removed soon. Use the iptables CT target "
				"to attach helpers instead.\n");
			net->ct.auto_assign_helper_warned = true;
		}
	}

	if (helper == NULL) {
		if (help)
			RCU_INIT_POINTER(help->helper, NULL);
		goto out;
	}

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

	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_INIT_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();
	}
}

static LIST_HEAD(nf_ct_helper_expectfn_list);

void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
{
	spin_lock_bh(&nf_conntrack_lock);
	list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
	spin_unlock_bh(&nf_conntrack_lock);
}
EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);

void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
{
	spin_lock_bh(&nf_conntrack_lock);
	list_del_rcu(&n->head);
	spin_unlock_bh(&nf_conntrack_lock);
}
EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);

struct nf_ct_helper_expectfn *
nf_ct_helper_expectfn_find_by_name(const char *name)
{
	struct nf_ct_helper_expectfn *cur;
	bool found = false;

	rcu_read_lock();
	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
		if (!strcmp(cur->name, name)) {
			found = true;
			break;
		}
	}
	rcu_read_unlock();
	return found ? cur : NULL;
}
EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);

struct nf_ct_helper_expectfn *
nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
{
	struct nf_ct_helper_expectfn *cur;
	bool found = false;

	rcu_read_lock();
	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
		if (cur->expectfn == symbol) {
			found = true;
			break;
		}
	}
	rcu_read_unlock();
	return found ? cur : NULL;
}
EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);

int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
{
	int ret = 0;
	struct nf_conntrack_helper *cur;
	struct hlist_node *n;
	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_for_each_entry(cur, n, &nf_ct_helper_hash[h], hnode) {
		if (strncmp(cur->name, me->name, NF_CT_HELPER_NAME_LEN) == 0 &&
		    cur->tuple.src.l3num == me->tuple.src.l3num &&
		    cur->tuple.dst.protonum == me->tuple.dst.protonum) {
			ret = -EEXIST;
			goto out;
		}
	}
	hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
	nf_ct_helper_count++;
out:
	mutex_unlock(&nf_ct_helper_mutex);
	return ret;
}
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(struct net *net)
{
	int err;

	net->ct.auto_assign_helper_warned = false;
	net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;

	if (net_eq(net, &init_net)) {
		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;
	}

	err = nf_conntrack_helper_init_sysctl(net);
	if (err < 0)
		goto out_sysctl;

	return 0;

out_sysctl:
	if (net_eq(net, &init_net))
		nf_ct_extend_unregister(&helper_extend);
err1:
	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
	return err;
}

void nf_conntrack_helper_fini(struct net *net)
{
	nf_conntrack_helper_fini_sysctl(net);
	if (net_eq(net, &init_net)) {
		nf_ct_extend_unregister(&helper_extend);
		nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
	}
}
Commit	Line	Data
7e5d03bb MJ	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>
7e5d03bb MJ	18	#include <linux/random.h>
	19	#include <linux/err.h>
	20	#include <linux/kernel.h>
	21	#include <linux/netdevice.h>
2ba4cc31	22	#include <linux/rculist.h>
efb9a8c2	23	#include <linux/rtnetlink.h>
7e5d03bb	24
7e5d03bb MJ	25	#include <net/netfilter/nf_conntrack.h>
7e5d03bb MJ	26	#include <net/netfilter/nf_conntrack_l3proto.h>
605dcad6	27	#include <net/netfilter/nf_conntrack_l4proto.h>
7e5d03bb MJ	28	#include <net/netfilter/nf_conntrack_helper.h>
7e5d03bb MJ	29	#include <net/netfilter/nf_conntrack_core.h>
ceceae1b	30	#include <net/netfilter/nf_conntrack_extend.h>
7e5d03bb	31
58a3c9bb	32	static DEFINE_MUTEX(nf_ct_helper_mutex);
12f7a505 PNA	33	struct hlist_head *nf_ct_helper_hash __read_mostly;
	34	EXPORT_SYMBOL_GPL(nf_ct_helper_hash);
	35	unsigned int nf_ct_helper_hsize __read_mostly;
	36	EXPORT_SYMBOL_GPL(nf_ct_helper_hsize);
b8a7fe6c	37	static unsigned int nf_ct_helper_count __read_mostly;
b8a7fe6c	38
a9006892 EL	39	static bool nf_ct_auto_assign_helper __read_mostly = true;
	40	module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
	41	MODULE_PARM_DESC(nf_conntrack_helper,
	42	"Enable automatic conntrack helper assignment (default 1)");
	43
	44	#ifdef CONFIG_SYSCTL
	45	static struct ctl_table helper_sysctl_table[] = {
	46	{
	47	.procname = "nf_conntrack_helper",
	48	.data = &init_net.ct.sysctl_auto_assign_helper,
	49	.maxlen = sizeof(unsigned int),
	50	.mode = 0644,
	51	.proc_handler = proc_dointvec,
	52	},
	53	{}
	54	};
	55
	56	static int nf_conntrack_helper_init_sysctl(struct net *net)
	57	{
	58	struct ctl_table *table;
	59
	60	table = kmemdup(helper_sysctl_table, sizeof(helper_sysctl_table),
	61	GFP_KERNEL);
	62	if (!table)
	63	goto out;
	64
	65	table[0].data = &net->ct.sysctl_auto_assign_helper;
	66
	67	net->ct.helper_sysctl_header =
	68	register_net_sysctl(net, "net/netfilter", table);
	69
	70	if (!net->ct.helper_sysctl_header) {
	71	pr_err("nf_conntrack_helper: can't register to sysctl.\n");
	72	goto out_register;
	73	}
	74	return 0;
	75
	76	out_register:
	77	kfree(table);
	78	out:
	79	return -ENOMEM;
	80	}
	81
	82	static void nf_conntrack_helper_fini_sysctl(struct net *net)
	83	{
	84	struct ctl_table *table;
	85
	86	table = net->ct.helper_sysctl_header->ctl_table_arg;
	87	unregister_net_sysctl_table(net->ct.helper_sysctl_header);
	88	kfree(table);
	89	}
	90	#else
	91	static int nf_conntrack_helper_init_sysctl(struct net *net)
	92	{
	93	return 0;
	94	}
	95
	96	static void nf_conntrack_helper_fini_sysctl(struct net *net)
	97	{
	98	}
	99	#endif /* CONFIG_SYSCTL */
b8a7fe6c PM	100
	101	/* Stupid hash, but collision free for the default registrations of the
	102	* helpers currently in the kernel. */
	103	static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
	104	{
	105	return (((tuple->src.l3num << 8) \| tuple->dst.protonum) ^
a34c4589	106	(__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
b8a7fe6c	107	}
7e5d03bb	108
226c0c0e	109	static struct nf_conntrack_helper *
7e5d03bb MJ	110	__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
7e5d03bb MJ	111	{
b8a7fe6c	112	struct nf_conntrack_helper *helper;
d4156e8c	113	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
b8a7fe6c PM	114	struct hlist_node *n;
b8a7fe6c PM	115	unsigned int h;
7e5d03bb	116
b8a7fe6c PM	117	if (!nf_ct_helper_count)
	118	return NULL;
	119
	120	h = helper_hash(tuple);
58a3c9bb	121	hlist_for_each_entry_rcu(helper, n, &nf_ct_helper_hash[h], hnode) {
b8a7fe6c PM	122	if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
b8a7fe6c PM	123	return helper;
7e5d03bb MJ	124	}
	125	return NULL;
	126	}
7e5d03bb MJ	127
7e5d03bb MJ	128	struct nf_conntrack_helper *
794e6871	129	__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
7e5d03bb MJ	130	{
7e5d03bb MJ	131	struct nf_conntrack_helper *h;
b8a7fe6c PM	132	struct hlist_node *n;
b8a7fe6c PM	133	unsigned int i;
7e5d03bb	134
b8a7fe6c	135	for (i = 0; i < nf_ct_helper_hsize; i++) {
58a3c9bb	136	hlist_for_each_entry_rcu(h, n, &nf_ct_helper_hash[i], hnode) {
794e6871 PM	137	if (!strcmp(h->name, name) &&
	138	h->tuple.src.l3num == l3num &&
	139	h->tuple.dst.protonum == protonum)
b8a7fe6c PM	140	return h;
b8a7fe6c PM	141	}
7e5d03bb	142	}
7e5d03bb MJ	143	return NULL;
7e5d03bb MJ	144	}
794e6871	145	EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
7e5d03bb	146
84f3bb9a PM	147	struct nf_conntrack_helper *
	148	nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
	149	{
	150	struct nf_conntrack_helper *h;
	151
	152	h = __nf_conntrack_helper_find(name, l3num, protonum);
	153	#ifdef CONFIG_MODULES
	154	if (h == NULL) {
	155	if (request_module("nfct-helper-%s", name) == 0)
	156	h = __nf_conntrack_helper_find(name, l3num, protonum);
	157	}
	158	#endif
	159	if (h != NULL && !try_module_get(h->me))
	160	h = NULL;
	161
	162	return h;
	163	}
	164	EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
	165
1afc5679 PNA	166	struct nf_conn_help *
	167	nf_ct_helper_ext_add(struct nf_conn *ct,
	168	struct nf_conntrack_helper *helper, gfp_t gfp)
b560580a PM	169	{
	170	struct nf_conn_help *help;
	171
1afc5679 PNA	172	help = nf_ct_ext_add_length(ct, NF_CT_EXT_HELPER,
1afc5679 PNA	173	helper->data_len, gfp);
b560580a PM	174	if (help)
	175	INIT_HLIST_HEAD(&help->expectations);
	176	else
	177	pr_debug("failed to add helper extension area");
	178	return help;
	179	}
	180	EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
	181
b2a15a60 PM	182	int __nf_ct_try_assign_helper(struct nf_conn ct, struct nf_conn tmpl,
b2a15a60 PM	183	gfp_t flags)
226c0c0e	184	{
b2a15a60 PM	185	struct nf_conntrack_helper *helper = NULL;
b2a15a60 PM	186	struct nf_conn_help *help;
a9006892	187	struct net *net = nf_ct_net(ct);
226c0c0e	188	int ret = 0;
226c0c0e	189
6714cf54 PNA	190	/* We already got a helper explicitly attached. The function
	191	* nf_conntrack_alter_reply - in case NAT is in use - asks for looking
	192	* the helper up again. Since now the user is in full control of
	193	* making consistent helper configurations, skip this automatic
	194	* re-lookup, otherwise we'll lose the helper.
	195	*/
	196	if (test_bit(IPS_HELPER_BIT, &ct->status))
	197	return 0;
	198
b2a15a60 PM	199	if (tmpl != NULL) {
b2a15a60 PM	200	help = nfct_help(tmpl);
6714cf54	201	if (help != NULL) {
b2a15a60	202	helper = help->helper;
6714cf54 PNA	203	set_bit(IPS_HELPER_BIT, &ct->status);
6714cf54 PNA	204	}
b2a15a60 PM	205	}
	206
	207	help = nfct_help(ct);
a9006892	208	if (net->ct.sysctl_auto_assign_helper && helper == NULL) {
b2a15a60	209	helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
a9006892 EL	210	if (unlikely(!net->ct.auto_assign_helper_warned && helper)) {
	211	pr_info("nf_conntrack: automatic helper "
	212	"assignment is deprecated and it will "
	213	"be removed soon. Use the iptables CT target "
	214	"to attach helpers instead.\n");
	215	net->ct.auto_assign_helper_warned = true;
	216	}
	217	}
	218
226c0c0e PNA	219	if (helper == NULL) {
226c0c0e PNA	220	if (help)
a9b3cd7f	221	RCU_INIT_POINTER(help->helper, NULL);
226c0c0e PNA	222	goto out;
	223	}
	224
	225	if (help == NULL) {
1afc5679	226	help = nf_ct_helper_ext_add(ct, helper, flags);
226c0c0e PNA	227	if (help == NULL) {
	228	ret = -ENOMEM;
	229	goto out;
	230	}
	231	} else {
1afc5679	232	memset(help->data, 0, helper->data_len);
226c0c0e PNA	233	}
226c0c0e PNA	234
cf778b00	235	rcu_assign_pointer(help->helper, helper);
226c0c0e PNA	236	out:
	237	return ret;
	238	}
	239	EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
	240
7e5d03bb MJ	241	static inline int unhelp(struct nf_conntrack_tuple_hash *i,
	242	const struct nf_conntrack_helper *me)
	243	{
	244	struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
	245	struct nf_conn_help *help = nfct_help(ct);
	246
c5d277d2 ED	247	if (help && rcu_dereference_protected(
	248	help->helper,
	249	lockdep_is_held(&nf_conntrack_lock)
	250	) == me) {
7e5d03bb	251	nf_conntrack_event(IPCT_HELPER, ct);
a9b3cd7f	252	RCU_INIT_POINTER(help->helper, NULL);
7e5d03bb MJ	253	}
	254	return 0;
	255	}
	256
9858a3ae PNA	257	void nf_ct_helper_destroy(struct nf_conn *ct)
	258	{
	259	struct nf_conn_help *help = nfct_help(ct);
	260	struct nf_conntrack_helper *helper;
	261
	262	if (help) {
	263	rcu_read_lock();
	264	helper = rcu_dereference(help->helper);
	265	if (helper && helper->destroy)
	266	helper->destroy(ct);
	267	rcu_read_unlock();
	268	}
	269	}
	270
544d5c7d PNA	271	static LIST_HEAD(nf_ct_helper_expectfn_list);
	272
	273	void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
	274	{
	275	spin_lock_bh(&nf_conntrack_lock);
	276	list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
	277	spin_unlock_bh(&nf_conntrack_lock);
	278	}
	279	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);
	280
	281	void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
	282	{
	283	spin_lock_bh(&nf_conntrack_lock);
	284	list_del_rcu(&n->head);
	285	spin_unlock_bh(&nf_conntrack_lock);
	286	}
	287	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
	288
	289	struct nf_ct_helper_expectfn *
	290	nf_ct_helper_expectfn_find_by_name(const char *name)
	291	{
	292	struct nf_ct_helper_expectfn *cur;
	293	bool found = false;
	294
	295	rcu_read_lock();
	296	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	297	if (!strcmp(cur->name, name)) {
	298	found = true;
	299	break;
	300	}
	301	}
	302	rcu_read_unlock();
	303	return found ? cur : NULL;
	304	}
	305	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);
	306
	307	struct nf_ct_helper_expectfn *
	308	nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
	309	{
	310	struct nf_ct_helper_expectfn *cur;
	311	bool found = false;
	312
	313	rcu_read_lock();
	314	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	315	if (cur->expectfn == symbol) {
	316	found = true;
	317	break;
	318	}
	319	}
	320	rcu_read_unlock();
	321	return found ? cur : NULL;
	322	}
	323	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
	324
7e5d03bb MJ	325	int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
7e5d03bb MJ	326	{
12f7a505 PNA	327	int ret = 0;
	328	struct nf_conntrack_helper *cur;
	329	struct hlist_node *n;
b8a7fe6c PM	330	unsigned int h = helper_hash(&me->tuple);
b8a7fe6c PM	331
6002f266 PM	332	BUG_ON(me->expect_policy == NULL);
6002f266 PM	333	BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
af9d32ad	334	BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
7e5d03bb	335
58a3c9bb	336	mutex_lock(&nf_ct_helper_mutex);
12f7a505 PNA	337	hlist_for_each_entry(cur, n, &nf_ct_helper_hash[h], hnode) {
	338	if (strncmp(cur->name, me->name, NF_CT_HELPER_NAME_LEN) == 0 &&
	339	cur->tuple.src.l3num == me->tuple.src.l3num &&
	340	cur->tuple.dst.protonum == me->tuple.dst.protonum) {
	341	ret = -EEXIST;
	342	goto out;
	343	}
	344	}
58a3c9bb	345	hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
b8a7fe6c	346	nf_ct_helper_count++;
12f7a505	347	out:
58a3c9bb	348	mutex_unlock(&nf_ct_helper_mutex);
12f7a505	349	return ret;
7e5d03bb	350	}
13b18339	351	EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
7e5d03bb	352
68047937 AD	353	static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
68047937 AD	354	struct net *net)
7e5d03bb	355	{
7e5d03bb	356	struct nf_conntrack_tuple_hash *h;
31f15875	357	struct nf_conntrack_expect *exp;
58c0fb0d	358	const struct hlist_node n, next;
ea781f19	359	const struct hlist_nulls_node *nn;
31f15875	360	unsigned int i;
7e5d03bb	361
7e5d03bb	362	/* Get rid of expectations */
31f15875 PM	363	for (i = 0; i < nf_ct_expect_hsize; i++) {
31f15875 PM	364	hlist_for_each_entry_safe(exp, n, next,
68047937	365	&net->ct.expect_hash[i], hnode) {
31f15875	366	struct nf_conn_help *help = nfct_help(exp->master);
c5d277d2 ED	367	if ((rcu_dereference_protected(
	368	help->helper,
	369	lockdep_is_held(&nf_conntrack_lock)
	370	) == me \|\| exp->helper == me) &&
31f15875 PM	371	del_timer(&exp->timeout)) {
	372	nf_ct_unlink_expect(exp);
	373	nf_ct_expect_put(exp);
	374	}
7e5d03bb MJ	375	}
	376	}
	377
	378	/* Get rid of expecteds, set helpers to NULL. */
38fb0afc	379	hlist_nulls_for_each_entry(h, nn, &net->ct.unconfirmed, hnnode)
7e5d03bb	380	unhelp(h, me);
d696c7bd	381	for (i = 0; i < net->ct.htable_size; i++) {
ea781f19	382	hlist_nulls_for_each_entry(h, nn, &net->ct.hash[i], hnnode)
7e5d03bb MJ	383	unhelp(h, me);
7e5d03bb MJ	384	}
68047937 AD	385	}
	386
	387	void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
	388	{
	389	struct net *net;
	390
	391	mutex_lock(&nf_ct_helper_mutex);
	392	hlist_del_rcu(&me->hnode);
	393	nf_ct_helper_count--;
	394	mutex_unlock(&nf_ct_helper_mutex);
	395
	396	/* Make sure every nothing is still using the helper unless its a
	397	* connection in the hash.
	398	*/
	399	synchronize_rcu();
	400
efb9a8c2	401	rtnl_lock();
68047937 AD	402	spin_lock_bh(&nf_conntrack_lock);
	403	for_each_net(net)
	404	__nf_conntrack_helper_unregister(me, net);
f8ba1aff	405	spin_unlock_bh(&nf_conntrack_lock);
efb9a8c2	406	rtnl_unlock();
7e5d03bb	407	}
13b18339	408	EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
ceceae1b	409
61eb3107	410	static struct nf_ct_ext_type helper_extend __read_mostly = {
ceceae1b YK	411	.len = sizeof(struct nf_conn_help),
	412	.align = __alignof__(struct nf_conn_help),
	413	.id = NF_CT_EXT_HELPER,
	414	};
	415
a9006892	416	int nf_conntrack_helper_init(struct net *net)
ceceae1b	417	{
b8a7fe6c PM	418	int err;
b8a7fe6c PM	419
a9006892 EL	420	net->ct.auto_assign_helper_warned = false;
a9006892 EL	421	net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
b8a7fe6c	422
a9006892 EL	423	if (net_eq(net, &init_net)) {
	424	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
	425	nf_ct_helper_hash =
	426	nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
	427	if (!nf_ct_helper_hash)
	428	return -ENOMEM;
	429
	430	err = nf_ct_extend_register(&helper_extend);
	431	if (err < 0)
	432	goto err1;
	433	}
	434
	435	err = nf_conntrack_helper_init_sysctl(net);
b8a7fe6c	436	if (err < 0)
a9006892	437	goto out_sysctl;
b8a7fe6c PM	438
	439	return 0;
	440
a9006892 EL	441	out_sysctl:
	442	if (net_eq(net, &init_net))
	443	nf_ct_extend_unregister(&helper_extend);
b8a7fe6c	444	err1:
d862a662	445	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
b8a7fe6c	446	return err;
ceceae1b YK	447	}
ceceae1b YK	448
a9006892	449	void nf_conntrack_helper_fini(struct net *net)
ceceae1b	450	{
a9006892 EL	451	nf_conntrack_helper_fini_sysctl(net);
	452	if (net_eq(net, &init_net)) {
	453	nf_ct_extend_unregister(&helper_extend);
	454	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
	455	}
ceceae1b	456	}