[linux-2.6-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>
#include <net/netfilter/nf_log.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) };
	unsigned int h;

	if (!nf_ct_helper_count)
		return NULL;

	h = helper_hash(tuple);
	hlist_for_each_entry_rcu(helper, &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;
	unsigned int i;

	for (i = 0; i < nf_ct_helper_hsize; i++) {
		hlist_for_each_entry_rcu(h, &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.
		 */
		struct nf_conntrack_helper *tmp = rcu_dereference(help->helper);

		if (tmp && tmp->help != helper->help) {
			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);

__printf(3, 4)
void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
		      const char *fmt, ...)
{
	const struct nf_conn_help *help;
	const struct nf_conntrack_helper *helper;

	/* Called from the helper function, this call never fails */
	help = nfct_help(ct);

	/* rcu_read_lock()ed by nf_hook_slow */
	helper = rcu_dereference(help->helper);

	nf_log_packet(nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL,
		      "nf_ct_%s: dropping packet: %s ", helper->name, fmt);
}
EXPORT_SYMBOL_GPL(nf_ct_helper_log);

int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
{
	int ret = 0;
	struct nf_conntrack_helper *cur;
	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, &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 *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, 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>
b20ab9cc	31	#include <net/netfilter/nf_log.h>
7e5d03bb	32
58a3c9bb	33	static DEFINE_MUTEX(nf_ct_helper_mutex);
12f7a505 PNA	34	struct hlist_head *nf_ct_helper_hash __read_mostly;
	35	EXPORT_SYMBOL_GPL(nf_ct_helper_hash);
	36	unsigned int nf_ct_helper_hsize __read_mostly;
	37	EXPORT_SYMBOL_GPL(nf_ct_helper_hsize);
b8a7fe6c	38	static unsigned int nf_ct_helper_count __read_mostly;
b8a7fe6c	39
a9006892 EL	40	static bool nf_ct_auto_assign_helper __read_mostly = true;
	41	module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
	42	MODULE_PARM_DESC(nf_conntrack_helper,
	43	"Enable automatic conntrack helper assignment (default 1)");
	44
	45	#ifdef CONFIG_SYSCTL
	46	static struct ctl_table helper_sysctl_table[] = {
	47	{
	48	.procname = "nf_conntrack_helper",
	49	.data = &init_net.ct.sysctl_auto_assign_helper,
	50	.maxlen = sizeof(unsigned int),
	51	.mode = 0644,
	52	.proc_handler = proc_dointvec,
	53	},
	54	{}
	55	};
	56
	57	static int nf_conntrack_helper_init_sysctl(struct net *net)
	58	{
	59	struct ctl_table *table;
	60
	61	table = kmemdup(helper_sysctl_table, sizeof(helper_sysctl_table),
	62	GFP_KERNEL);
	63	if (!table)
	64	goto out;
	65
	66	table[0].data = &net->ct.sysctl_auto_assign_helper;
	67
464dc801 EB	68	/* Don't export sysctls to unprivileged users */
	69	if (net->user_ns != &init_user_ns)
	70	table[0].procname = NULL;
	71
a9006892 EL	72	net->ct.helper_sysctl_header =
	73	register_net_sysctl(net, "net/netfilter", table);
	74
	75	if (!net->ct.helper_sysctl_header) {
	76	pr_err("nf_conntrack_helper: can't register to sysctl.\n");
	77	goto out_register;
	78	}
	79	return 0;
	80
	81	out_register:
	82	kfree(table);
	83	out:
	84	return -ENOMEM;
	85	}
	86
	87	static void nf_conntrack_helper_fini_sysctl(struct net *net)
	88	{
	89	struct ctl_table *table;
	90
	91	table = net->ct.helper_sysctl_header->ctl_table_arg;
	92	unregister_net_sysctl_table(net->ct.helper_sysctl_header);
	93	kfree(table);
	94	}
	95	#else
	96	static int nf_conntrack_helper_init_sysctl(struct net *net)
	97	{
	98	return 0;
	99	}
	100
	101	static void nf_conntrack_helper_fini_sysctl(struct net *net)
	102	{
	103	}
	104	#endif /* CONFIG_SYSCTL */
b8a7fe6c PM	105
	106	/* Stupid hash, but collision free for the default registrations of the
	107	* helpers currently in the kernel. */
	108	static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
	109	{
	110	return (((tuple->src.l3num << 8) \| tuple->dst.protonum) ^
a34c4589	111	(__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
b8a7fe6c	112	}
7e5d03bb	113
226c0c0e	114	static struct nf_conntrack_helper *
7e5d03bb MJ	115	__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
7e5d03bb MJ	116	{
b8a7fe6c	117	struct nf_conntrack_helper *helper;
d4156e8c	118	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
b8a7fe6c	119	unsigned int h;
7e5d03bb	120
b8a7fe6c PM	121	if (!nf_ct_helper_count)
	122	return NULL;
	123
	124	h = helper_hash(tuple);
b67bfe0d	125	hlist_for_each_entry_rcu(helper, &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	136	unsigned int i;
7e5d03bb	137
b8a7fe6c	138	for (i = 0; i < nf_ct_helper_hsize; i++) {
b67bfe0d	139	hlist_for_each_entry_rcu(h, &nf_ct_helper_hash[i], hnode) {
794e6871 PM	140	if (!strcmp(h->name, name) &&
	141	h->tuple.src.l3num == l3num &&
	142	h->tuple.dst.protonum == protonum)
b8a7fe6c PM	143	return h;
b8a7fe6c PM	144	}
7e5d03bb	145	}
7e5d03bb MJ	146	return NULL;
7e5d03bb MJ	147	}
794e6871	148	EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
7e5d03bb	149
84f3bb9a PM	150	struct nf_conntrack_helper *
	151	nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
	152	{
	153	struct nf_conntrack_helper *h;
	154
	155	h = __nf_conntrack_helper_find(name, l3num, protonum);
	156	#ifdef CONFIG_MODULES
	157	if (h == NULL) {
	158	if (request_module("nfct-helper-%s", name) == 0)
	159	h = __nf_conntrack_helper_find(name, l3num, protonum);
	160	}
	161	#endif
	162	if (h != NULL && !try_module_get(h->me))
	163	h = NULL;
	164
	165	return h;
	166	}
	167	EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
	168
1afc5679 PNA	169	struct nf_conn_help *
	170	nf_ct_helper_ext_add(struct nf_conn *ct,
	171	struct nf_conntrack_helper *helper, gfp_t gfp)
b560580a PM	172	{
	173	struct nf_conn_help *help;
	174
1afc5679 PNA	175	help = nf_ct_ext_add_length(ct, NF_CT_EXT_HELPER,
1afc5679 PNA	176	helper->data_len, gfp);
b560580a PM	177	if (help)
	178	INIT_HLIST_HEAD(&help->expectations);
	179	else
	180	pr_debug("failed to add helper extension area");
	181	return help;
	182	}
	183	EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
	184
b2a15a60 PM	185	int __nf_ct_try_assign_helper(struct nf_conn ct, struct nf_conn tmpl,
b2a15a60 PM	186	gfp_t flags)
226c0c0e	187	{
b2a15a60 PM	188	struct nf_conntrack_helper *helper = NULL;
b2a15a60 PM	189	struct nf_conn_help *help;
a9006892	190	struct net *net = nf_ct_net(ct);
226c0c0e	191	int ret = 0;
226c0c0e	192
6714cf54 PNA	193	/* We already got a helper explicitly attached. The function
	194	* nf_conntrack_alter_reply - in case NAT is in use - asks for looking
	195	* the helper up again. Since now the user is in full control of
	196	* making consistent helper configurations, skip this automatic
	197	* re-lookup, otherwise we'll lose the helper.
	198	*/
	199	if (test_bit(IPS_HELPER_BIT, &ct->status))
	200	return 0;
	201
b2a15a60 PM	202	if (tmpl != NULL) {
b2a15a60 PM	203	help = nfct_help(tmpl);
6714cf54	204	if (help != NULL) {
b2a15a60	205	helper = help->helper;
6714cf54 PNA	206	set_bit(IPS_HELPER_BIT, &ct->status);
6714cf54 PNA	207	}
b2a15a60 PM	208	}
	209
	210	help = nfct_help(ct);
a9006892	211	if (net->ct.sysctl_auto_assign_helper && helper == NULL) {
b2a15a60	212	helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
a9006892 EL	213	if (unlikely(!net->ct.auto_assign_helper_warned && helper)) {
	214	pr_info("nf_conntrack: automatic helper "
	215	"assignment is deprecated and it will "
	216	"be removed soon. Use the iptables CT target "
	217	"to attach helpers instead.\n");
	218	net->ct.auto_assign_helper_warned = true;
	219	}
	220	}
	221
226c0c0e PNA	222	if (helper == NULL) {
226c0c0e PNA	223	if (help)
a9b3cd7f	224	RCU_INIT_POINTER(help->helper, NULL);
226c0c0e PNA	225	goto out;
	226	}
	227
	228	if (help == NULL) {
1afc5679	229	help = nf_ct_helper_ext_add(ct, helper, flags);
226c0c0e PNA	230	if (help == NULL) {
	231	ret = -ENOMEM;
	232	goto out;
	233	}
	234	} else {
32f53760 PNA	235	/* We only allow helper re-assignment of the same sort since
	236	* we cannot reallocate the helper extension area.
	237	*/
6e2f0aa8 FW	238	struct nf_conntrack_helper *tmp = rcu_dereference(help->helper);
	239
	240	if (tmp && tmp->help != helper->help) {
32f53760 PNA	241	RCU_INIT_POINTER(help->helper, NULL);
	242	goto out;
	243	}
226c0c0e PNA	244	}
226c0c0e PNA	245
cf778b00	246	rcu_assign_pointer(help->helper, helper);
226c0c0e PNA	247	out:
	248	return ret;
	249	}
	250	EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
	251
7e5d03bb MJ	252	static inline int unhelp(struct nf_conntrack_tuple_hash *i,
	253	const struct nf_conntrack_helper *me)
	254	{
	255	struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
	256	struct nf_conn_help *help = nfct_help(ct);
	257
c5d277d2 ED	258	if (help && rcu_dereference_protected(
	259	help->helper,
	260	lockdep_is_held(&nf_conntrack_lock)
	261	) == me) {
7e5d03bb	262	nf_conntrack_event(IPCT_HELPER, ct);
a9b3cd7f	263	RCU_INIT_POINTER(help->helper, NULL);
7e5d03bb MJ	264	}
	265	return 0;
	266	}
	267
9858a3ae PNA	268	void nf_ct_helper_destroy(struct nf_conn *ct)
	269	{
	270	struct nf_conn_help *help = nfct_help(ct);
	271	struct nf_conntrack_helper *helper;
	272
	273	if (help) {
	274	rcu_read_lock();
	275	helper = rcu_dereference(help->helper);
	276	if (helper && helper->destroy)
	277	helper->destroy(ct);
	278	rcu_read_unlock();
	279	}
	280	}
	281
544d5c7d PNA	282	static LIST_HEAD(nf_ct_helper_expectfn_list);
	283
	284	void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
	285	{
	286	spin_lock_bh(&nf_conntrack_lock);
	287	list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
	288	spin_unlock_bh(&nf_conntrack_lock);
	289	}
	290	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);
	291
	292	void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
	293	{
	294	spin_lock_bh(&nf_conntrack_lock);
	295	list_del_rcu(&n->head);
	296	spin_unlock_bh(&nf_conntrack_lock);
	297	}
	298	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
	299
	300	struct nf_ct_helper_expectfn *
	301	nf_ct_helper_expectfn_find_by_name(const char *name)
	302	{
	303	struct nf_ct_helper_expectfn *cur;
	304	bool found = false;
	305
	306	rcu_read_lock();
	307	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	308	if (!strcmp(cur->name, name)) {
	309	found = true;
	310	break;
	311	}
	312	}
	313	rcu_read_unlock();
	314	return found ? cur : NULL;
	315	}
	316	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);
	317
	318	struct nf_ct_helper_expectfn *
	319	nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
	320	{
	321	struct nf_ct_helper_expectfn *cur;
	322	bool found = false;
	323
	324	rcu_read_lock();
	325	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	326	if (cur->expectfn == symbol) {
	327	found = true;
	328	break;
	329	}
	330	}
	331	rcu_read_unlock();
	332	return found ? cur : NULL;
	333	}
	334	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
	335
b20ab9cc PNA	336	__printf(3, 4)
	337	void nf_ct_helper_log(struct sk_buff skb, const struct nf_conn ct,
	338	const char *fmt, ...)
	339	{
	340	const struct nf_conn_help *help;
	341	const struct nf_conntrack_helper *helper;
	342
	343	/* Called from the helper function, this call never fails */
	344	help = nfct_help(ct);
	345
	346	/* rcu_read_lock()ed by nf_hook_slow */
	347	helper = rcu_dereference(help->helper);
	348
	349	nf_log_packet(nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL,
	350	"nf_ct_%s: dropping packet: %s ", helper->name, fmt);
	351	}
	352	EXPORT_SYMBOL_GPL(nf_ct_helper_log);
	353
7e5d03bb MJ	354	int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
7e5d03bb MJ	355	{
12f7a505 PNA	356	int ret = 0;
12f7a505 PNA	357	struct nf_conntrack_helper *cur;
b8a7fe6c PM	358	unsigned int h = helper_hash(&me->tuple);
b8a7fe6c PM	359
6002f266 PM	360	BUG_ON(me->expect_policy == NULL);
6002f266 PM	361	BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
af9d32ad	362	BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
7e5d03bb	363
58a3c9bb	364	mutex_lock(&nf_ct_helper_mutex);
b67bfe0d	365	hlist_for_each_entry(cur, &nf_ct_helper_hash[h], hnode) {
12f7a505 PNA	366	if (strncmp(cur->name, me->name, NF_CT_HELPER_NAME_LEN) == 0 &&
	367	cur->tuple.src.l3num == me->tuple.src.l3num &&
	368	cur->tuple.dst.protonum == me->tuple.dst.protonum) {
	369	ret = -EEXIST;
	370	goto out;
	371	}
	372	}
58a3c9bb	373	hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
b8a7fe6c	374	nf_ct_helper_count++;
12f7a505	375	out:
58a3c9bb	376	mutex_unlock(&nf_ct_helper_mutex);
12f7a505	377	return ret;
7e5d03bb	378	}
13b18339	379	EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
7e5d03bb	380
68047937 AD	381	static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
68047937 AD	382	struct net *net)
7e5d03bb	383	{
7e5d03bb	384	struct nf_conntrack_tuple_hash *h;
31f15875	385	struct nf_conntrack_expect *exp;
b67bfe0d	386	const struct hlist_node *next;
ea781f19	387	const struct hlist_nulls_node *nn;
31f15875	388	unsigned int i;
7e5d03bb	389
7e5d03bb	390	/* Get rid of expectations */
31f15875	391	for (i = 0; i < nf_ct_expect_hsize; i++) {
b67bfe0d	392	hlist_for_each_entry_safe(exp, next,
68047937	393	&net->ct.expect_hash[i], hnode) {
31f15875	394	struct nf_conn_help *help = nfct_help(exp->master);
c5d277d2 ED	395	if ((rcu_dereference_protected(
	396	help->helper,
	397	lockdep_is_held(&nf_conntrack_lock)
	398	) == me \|\| exp->helper == me) &&
31f15875 PM	399	del_timer(&exp->timeout)) {
	400	nf_ct_unlink_expect(exp);
	401	nf_ct_expect_put(exp);
	402	}
7e5d03bb MJ	403	}
	404	}
	405
	406	/* Get rid of expecteds, set helpers to NULL. */
38fb0afc	407	hlist_nulls_for_each_entry(h, nn, &net->ct.unconfirmed, hnnode)
7e5d03bb	408	unhelp(h, me);
d696c7bd	409	for (i = 0; i < net->ct.htable_size; i++) {
ea781f19	410	hlist_nulls_for_each_entry(h, nn, &net->ct.hash[i], hnnode)
7e5d03bb MJ	411	unhelp(h, me);
7e5d03bb MJ	412	}
68047937 AD	413	}
	414
	415	void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
	416	{
	417	struct net *net;
	418
	419	mutex_lock(&nf_ct_helper_mutex);
	420	hlist_del_rcu(&me->hnode);
	421	nf_ct_helper_count--;
	422	mutex_unlock(&nf_ct_helper_mutex);
	423
	424	/* Make sure every nothing is still using the helper unless its a
	425	* connection in the hash.
	426	*/
	427	synchronize_rcu();
	428
efb9a8c2	429	rtnl_lock();
68047937 AD	430	spin_lock_bh(&nf_conntrack_lock);
	431	for_each_net(net)
	432	__nf_conntrack_helper_unregister(me, net);
f8ba1aff	433	spin_unlock_bh(&nf_conntrack_lock);
efb9a8c2	434	rtnl_unlock();
7e5d03bb	435	}
13b18339	436	EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
ceceae1b	437
61eb3107	438	static struct nf_ct_ext_type helper_extend __read_mostly = {
ceceae1b YK	439	.len = sizeof(struct nf_conn_help),
	440	.align = __alignof__(struct nf_conn_help),
	441	.id = NF_CT_EXT_HELPER,
	442	};
	443
5e615b22	444	int nf_conntrack_helper_pernet_init(struct net *net)
ceceae1b	445	{
a9006892 EL	446	net->ct.auto_assign_helper_warned = false;
a9006892 EL	447	net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
5e615b22 G	448	return nf_conntrack_helper_init_sysctl(net);
5e615b22 G	449	}
b8a7fe6c	450
5e615b22 G	451	void nf_conntrack_helper_pernet_fini(struct net *net)
	452	{
	453	nf_conntrack_helper_fini_sysctl(net);
	454	}
a9006892	455
5e615b22 G	456	int nf_conntrack_helper_init(void)
	457	{
	458	int ret;
	459	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
	460	nf_ct_helper_hash =
	461	nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
	462	if (!nf_ct_helper_hash)
	463	return -ENOMEM;
	464
	465	ret = nf_ct_extend_register(&helper_extend);
	466	if (ret < 0) {
	467	pr_err("nf_ct_helper: Unable to register helper extension.\n");
	468	goto out_extend;
a9006892 EL	469	}
a9006892 EL	470
b8a7fe6c	471	return 0;
5e615b22	472	out_extend:
d862a662	473	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
5e615b22	474	return ret;
ceceae1b YK	475	}
ceceae1b YK	476
5e615b22	477	void nf_conntrack_helper_fini(void)
ceceae1b	478	{
5e615b22 G	479	nf_ct_extend_unregister(&helper_extend);
5e615b22 G	480	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
ceceae1b	481	}