[linux-block.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;

	/* Don't export sysctls to unprivileged users */
	if (net->user_ns != &init_user_ns)
		table[0].procname = NULL;

	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 {
		/* We only allow helper re-assignment of the same sort since
		 * we cannot reallocate the helper extension area.
		 */
		if (help->helper != helper) {
			RCU_INIT_POINTER(help->helper, NULL);
			goto out;
		}
	}

	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_pernet_init(struct net *net)
{
	net->ct.auto_assign_helper_warned = false;
	net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
	return nf_conntrack_helper_init_sysctl(net);
}

void nf_conntrack_helper_pernet_fini(struct net *net)
{
	nf_conntrack_helper_fini_sysctl(net);
}

int nf_conntrack_helper_init(void)
{
	int ret;
	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;

	ret = nf_ct_extend_register(&helper_extend);
	if (ret < 0) {
		pr_err("nf_ct_helper: Unable to register helper extension.\n");
		goto out_extend;
	}

	return 0;
out_extend:
	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
	return ret;
}

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
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
464dc801 EB	67	/* Don't export sysctls to unprivileged users */
	68	if (net->user_ns != &init_user_ns)
	69	table[0].procname = NULL;
	70
a9006892 EL	71	net->ct.helper_sysctl_header =
	72	register_net_sysctl(net, "net/netfilter", table);
	73
	74	if (!net->ct.helper_sysctl_header) {
	75	pr_err("nf_conntrack_helper: can't register to sysctl.\n");
	76	goto out_register;
	77	}
	78	return 0;
	79
	80	out_register:
	81	kfree(table);
	82	out:
	83	return -ENOMEM;
	84	}
	85
	86	static void nf_conntrack_helper_fini_sysctl(struct net *net)
	87	{
	88	struct ctl_table *table;
	89
	90	table = net->ct.helper_sysctl_header->ctl_table_arg;
	91	unregister_net_sysctl_table(net->ct.helper_sysctl_header);
	92	kfree(table);
	93	}
	94	#else
	95	static int nf_conntrack_helper_init_sysctl(struct net *net)
	96	{
	97	return 0;
	98	}
	99
	100	static void nf_conntrack_helper_fini_sysctl(struct net *net)
	101	{
	102	}
	103	#endif /* CONFIG_SYSCTL */
b8a7fe6c PM	104
	105	/* Stupid hash, but collision free for the default registrations of the
	106	* helpers currently in the kernel. */
	107	static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
	108	{
	109	return (((tuple->src.l3num << 8) \| tuple->dst.protonum) ^
a34c4589	110	(__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
b8a7fe6c	111	}
7e5d03bb	112
226c0c0e	113	static struct nf_conntrack_helper *
7e5d03bb MJ	114	__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
7e5d03bb MJ	115	{
b8a7fe6c	116	struct nf_conntrack_helper *helper;
d4156e8c	117	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
b8a7fe6c PM	118	struct hlist_node *n;
b8a7fe6c PM	119	unsigned int h;
7e5d03bb	120
b8a7fe6c PM	121	if (!nf_ct_helper_count)
	122	return NULL;
	123
	124	h = helper_hash(tuple);
58a3c9bb	125	hlist_for_each_entry_rcu(helper, n, &nf_ct_helper_hash[h], hnode) {
b8a7fe6c PM	126	if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
b8a7fe6c PM	127	return helper;
7e5d03bb MJ	128	}
	129	return NULL;
	130	}
7e5d03bb MJ	131
7e5d03bb MJ	132	struct nf_conntrack_helper *
794e6871	133	__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
7e5d03bb MJ	134	{
7e5d03bb MJ	135	struct nf_conntrack_helper *h;
b8a7fe6c PM	136	struct hlist_node *n;
b8a7fe6c PM	137	unsigned int i;
7e5d03bb	138
b8a7fe6c	139	for (i = 0; i < nf_ct_helper_hsize; i++) {
58a3c9bb	140	hlist_for_each_entry_rcu(h, n, &nf_ct_helper_hash[i], hnode) {
794e6871 PM	141	if (!strcmp(h->name, name) &&
	142	h->tuple.src.l3num == l3num &&
	143	h->tuple.dst.protonum == protonum)
b8a7fe6c PM	144	return h;
b8a7fe6c PM	145	}
7e5d03bb	146	}
7e5d03bb MJ	147	return NULL;
7e5d03bb MJ	148	}
794e6871	149	EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
7e5d03bb	150
84f3bb9a PM	151	struct nf_conntrack_helper *
	152	nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
	153	{
	154	struct nf_conntrack_helper *h;
	155
	156	h = __nf_conntrack_helper_find(name, l3num, protonum);
	157	#ifdef CONFIG_MODULES
	158	if (h == NULL) {
	159	if (request_module("nfct-helper-%s", name) == 0)
	160	h = __nf_conntrack_helper_find(name, l3num, protonum);
	161	}
	162	#endif
	163	if (h != NULL && !try_module_get(h->me))
	164	h = NULL;
	165
	166	return h;
	167	}
	168	EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
	169
1afc5679 PNA	170	struct nf_conn_help *
	171	nf_ct_helper_ext_add(struct nf_conn *ct,
	172	struct nf_conntrack_helper *helper, gfp_t gfp)
b560580a PM	173	{
	174	struct nf_conn_help *help;
	175
1afc5679 PNA	176	help = nf_ct_ext_add_length(ct, NF_CT_EXT_HELPER,
1afc5679 PNA	177	helper->data_len, gfp);
b560580a PM	178	if (help)
	179	INIT_HLIST_HEAD(&help->expectations);
	180	else
	181	pr_debug("failed to add helper extension area");
	182	return help;
	183	}
	184	EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
	185
b2a15a60 PM	186	int __nf_ct_try_assign_helper(struct nf_conn ct, struct nf_conn tmpl,
b2a15a60 PM	187	gfp_t flags)
226c0c0e	188	{
b2a15a60 PM	189	struct nf_conntrack_helper *helper = NULL;
b2a15a60 PM	190	struct nf_conn_help *help;
a9006892	191	struct net *net = nf_ct_net(ct);
226c0c0e	192	int ret = 0;
226c0c0e	193
6714cf54 PNA	194	/* We already got a helper explicitly attached. The function
	195	* nf_conntrack_alter_reply - in case NAT is in use - asks for looking
	196	* the helper up again. Since now the user is in full control of
	197	* making consistent helper configurations, skip this automatic
	198	* re-lookup, otherwise we'll lose the helper.
	199	*/
	200	if (test_bit(IPS_HELPER_BIT, &ct->status))
	201	return 0;
	202
b2a15a60 PM	203	if (tmpl != NULL) {
b2a15a60 PM	204	help = nfct_help(tmpl);
6714cf54	205	if (help != NULL) {
b2a15a60	206	helper = help->helper;
6714cf54 PNA	207	set_bit(IPS_HELPER_BIT, &ct->status);
6714cf54 PNA	208	}
b2a15a60 PM	209	}
	210
	211	help = nfct_help(ct);
a9006892	212	if (net->ct.sysctl_auto_assign_helper && helper == NULL) {
b2a15a60	213	helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
a9006892 EL	214	if (unlikely(!net->ct.auto_assign_helper_warned && helper)) {
	215	pr_info("nf_conntrack: automatic helper "
	216	"assignment is deprecated and it will "
	217	"be removed soon. Use the iptables CT target "
	218	"to attach helpers instead.\n");
	219	net->ct.auto_assign_helper_warned = true;
	220	}
	221	}
	222
226c0c0e PNA	223	if (helper == NULL) {
226c0c0e PNA	224	if (help)
a9b3cd7f	225	RCU_INIT_POINTER(help->helper, NULL);
226c0c0e PNA	226	goto out;
	227	}
	228
	229	if (help == NULL) {
1afc5679	230	help = nf_ct_helper_ext_add(ct, helper, flags);
226c0c0e PNA	231	if (help == NULL) {
	232	ret = -ENOMEM;
	233	goto out;
	234	}
	235	} else {
32f53760 PNA	236	/* We only allow helper re-assignment of the same sort since
	237	* we cannot reallocate the helper extension area.
	238	*/
	239	if (help->helper != helper) {
	240	RCU_INIT_POINTER(help->helper, NULL);
	241	goto out;
	242	}
226c0c0e PNA	243	}
226c0c0e PNA	244
cf778b00	245	rcu_assign_pointer(help->helper, helper);
226c0c0e PNA	246	out:
	247	return ret;
	248	}
	249	EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
	250
7e5d03bb MJ	251	static inline int unhelp(struct nf_conntrack_tuple_hash *i,
	252	const struct nf_conntrack_helper *me)
	253	{
	254	struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
	255	struct nf_conn_help *help = nfct_help(ct);
	256
c5d277d2 ED	257	if (help && rcu_dereference_protected(
	258	help->helper,
	259	lockdep_is_held(&nf_conntrack_lock)
	260	) == me) {
7e5d03bb	261	nf_conntrack_event(IPCT_HELPER, ct);
a9b3cd7f	262	RCU_INIT_POINTER(help->helper, NULL);
7e5d03bb MJ	263	}
	264	return 0;
	265	}
	266
9858a3ae PNA	267	void nf_ct_helper_destroy(struct nf_conn *ct)
	268	{
	269	struct nf_conn_help *help = nfct_help(ct);
	270	struct nf_conntrack_helper *helper;
	271
	272	if (help) {
	273	rcu_read_lock();
	274	helper = rcu_dereference(help->helper);
	275	if (helper && helper->destroy)
	276	helper->destroy(ct);
	277	rcu_read_unlock();
	278	}
	279	}
	280
544d5c7d PNA	281	static LIST_HEAD(nf_ct_helper_expectfn_list);
	282
	283	void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
	284	{
	285	spin_lock_bh(&nf_conntrack_lock);
	286	list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
	287	spin_unlock_bh(&nf_conntrack_lock);
	288	}
	289	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);
	290
	291	void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
	292	{
	293	spin_lock_bh(&nf_conntrack_lock);
	294	list_del_rcu(&n->head);
	295	spin_unlock_bh(&nf_conntrack_lock);
	296	}
	297	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
	298
	299	struct nf_ct_helper_expectfn *
	300	nf_ct_helper_expectfn_find_by_name(const char *name)
	301	{
	302	struct nf_ct_helper_expectfn *cur;
	303	bool found = false;
	304
	305	rcu_read_lock();
	306	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	307	if (!strcmp(cur->name, name)) {
	308	found = true;
	309	break;
	310	}
	311	}
	312	rcu_read_unlock();
	313	return found ? cur : NULL;
	314	}
	315	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);
	316
	317	struct nf_ct_helper_expectfn *
	318	nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
	319	{
	320	struct nf_ct_helper_expectfn *cur;
	321	bool found = false;
	322
	323	rcu_read_lock();
	324	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	325	if (cur->expectfn == symbol) {
	326	found = true;
	327	break;
	328	}
	329	}
	330	rcu_read_unlock();
	331	return found ? cur : NULL;
	332	}
	333	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
	334
7e5d03bb MJ	335	int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
7e5d03bb MJ	336	{
12f7a505 PNA	337	int ret = 0;
	338	struct nf_conntrack_helper *cur;
	339	struct hlist_node *n;
b8a7fe6c PM	340	unsigned int h = helper_hash(&me->tuple);
b8a7fe6c PM	341
6002f266 PM	342	BUG_ON(me->expect_policy == NULL);
6002f266 PM	343	BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
af9d32ad	344	BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
7e5d03bb	345
58a3c9bb	346	mutex_lock(&nf_ct_helper_mutex);
12f7a505 PNA	347	hlist_for_each_entry(cur, n, &nf_ct_helper_hash[h], hnode) {
	348	if (strncmp(cur->name, me->name, NF_CT_HELPER_NAME_LEN) == 0 &&
	349	cur->tuple.src.l3num == me->tuple.src.l3num &&
	350	cur->tuple.dst.protonum == me->tuple.dst.protonum) {
	351	ret = -EEXIST;
	352	goto out;
	353	}
	354	}
58a3c9bb	355	hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
b8a7fe6c	356	nf_ct_helper_count++;
12f7a505	357	out:
58a3c9bb	358	mutex_unlock(&nf_ct_helper_mutex);
12f7a505	359	return ret;
7e5d03bb	360	}
13b18339	361	EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
7e5d03bb	362
68047937 AD	363	static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
68047937 AD	364	struct net *net)
7e5d03bb	365	{
7e5d03bb	366	struct nf_conntrack_tuple_hash *h;
31f15875	367	struct nf_conntrack_expect *exp;
58c0fb0d	368	const struct hlist_node n, next;
ea781f19	369	const struct hlist_nulls_node *nn;
31f15875	370	unsigned int i;
7e5d03bb	371
7e5d03bb	372	/* Get rid of expectations */
31f15875 PM	373	for (i = 0; i < nf_ct_expect_hsize; i++) {
31f15875 PM	374	hlist_for_each_entry_safe(exp, n, next,
68047937	375	&net->ct.expect_hash[i], hnode) {
31f15875	376	struct nf_conn_help *help = nfct_help(exp->master);
c5d277d2 ED	377	if ((rcu_dereference_protected(
	378	help->helper,
	379	lockdep_is_held(&nf_conntrack_lock)
	380	) == me \|\| exp->helper == me) &&
31f15875 PM	381	del_timer(&exp->timeout)) {
	382	nf_ct_unlink_expect(exp);
	383	nf_ct_expect_put(exp);
	384	}
7e5d03bb MJ	385	}
	386	}
	387
	388	/* Get rid of expecteds, set helpers to NULL. */
38fb0afc	389	hlist_nulls_for_each_entry(h, nn, &net->ct.unconfirmed, hnnode)
7e5d03bb	390	unhelp(h, me);
d696c7bd	391	for (i = 0; i < net->ct.htable_size; i++) {
ea781f19	392	hlist_nulls_for_each_entry(h, nn, &net->ct.hash[i], hnnode)
7e5d03bb MJ	393	unhelp(h, me);
7e5d03bb MJ	394	}
68047937 AD	395	}
	396
	397	void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
	398	{
	399	struct net *net;
	400
	401	mutex_lock(&nf_ct_helper_mutex);
	402	hlist_del_rcu(&me->hnode);
	403	nf_ct_helper_count--;
	404	mutex_unlock(&nf_ct_helper_mutex);
	405
	406	/* Make sure every nothing is still using the helper unless its a
	407	* connection in the hash.
	408	*/
	409	synchronize_rcu();
	410
efb9a8c2	411	rtnl_lock();
68047937 AD	412	spin_lock_bh(&nf_conntrack_lock);
	413	for_each_net(net)
	414	__nf_conntrack_helper_unregister(me, net);
f8ba1aff	415	spin_unlock_bh(&nf_conntrack_lock);
efb9a8c2	416	rtnl_unlock();
7e5d03bb	417	}
13b18339	418	EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
ceceae1b	419
61eb3107	420	static struct nf_ct_ext_type helper_extend __read_mostly = {
ceceae1b YK	421	.len = sizeof(struct nf_conn_help),
	422	.align = __alignof__(struct nf_conn_help),
	423	.id = NF_CT_EXT_HELPER,
	424	};
	425
5e615b22	426	int nf_conntrack_helper_pernet_init(struct net *net)
ceceae1b	427	{
a9006892 EL	428	net->ct.auto_assign_helper_warned = false;
a9006892 EL	429	net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
5e615b22 G	430	return nf_conntrack_helper_init_sysctl(net);
5e615b22 G	431	}
b8a7fe6c	432
5e615b22 G	433	void nf_conntrack_helper_pernet_fini(struct net *net)
	434	{
	435	nf_conntrack_helper_fini_sysctl(net);
	436	}
a9006892	437
5e615b22 G	438	int nf_conntrack_helper_init(void)
	439	{
	440	int ret;
	441	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
	442	nf_ct_helper_hash =
	443	nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
	444	if (!nf_ct_helper_hash)
	445	return -ENOMEM;
	446
	447	ret = nf_ct_extend_register(&helper_extend);
	448	if (ret < 0) {
	449	pr_err("nf_ct_helper: Unable to register helper extension.\n");
	450	goto out_extend;
a9006892 EL	451	}
a9006892 EL	452
b8a7fe6c	453	return 0;
5e615b22	454	out_extend:
d862a662	455	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
5e615b22	456	return ret;
ceceae1b YK	457	}
ceceae1b YK	458
5e615b22	459	void nf_conntrack_helper_fini(void)
ceceae1b	460	{
5e615b22 G	461	nf_ct_extend_unregister(&helper_extend);
5e615b22 G	462	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
ceceae1b	463	}