[mirror_ubuntu-hirsute-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>
#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) };
	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.
		 */
		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;
	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>
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 PM	119	struct hlist_node *n;
b8a7fe6c PM	120	unsigned int h;
7e5d03bb	121
b8a7fe6c PM	122	if (!nf_ct_helper_count)
	123	return NULL;
	124
	125	h = helper_hash(tuple);
58a3c9bb	126	hlist_for_each_entry_rcu(helper, n, &nf_ct_helper_hash[h], hnode) {
b8a7fe6c PM	127	if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
b8a7fe6c PM	128	return helper;
7e5d03bb MJ	129	}
	130	return NULL;
	131	}
7e5d03bb MJ	132
7e5d03bb MJ	133	struct nf_conntrack_helper *
794e6871	134	__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
7e5d03bb MJ	135	{
7e5d03bb MJ	136	struct nf_conntrack_helper *h;
b8a7fe6c PM	137	struct hlist_node *n;
b8a7fe6c PM	138	unsigned int i;
7e5d03bb	139
b8a7fe6c	140	for (i = 0; i < nf_ct_helper_hsize; i++) {
58a3c9bb	141	hlist_for_each_entry_rcu(h, n, &nf_ct_helper_hash[i], hnode) {
794e6871 PM	142	if (!strcmp(h->name, name) &&
	143	h->tuple.src.l3num == l3num &&
	144	h->tuple.dst.protonum == protonum)
b8a7fe6c PM	145	return h;
b8a7fe6c PM	146	}
7e5d03bb	147	}
7e5d03bb MJ	148	return NULL;
7e5d03bb MJ	149	}
794e6871	150	EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
7e5d03bb	151
84f3bb9a PM	152	struct nf_conntrack_helper *
	153	nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
	154	{
	155	struct nf_conntrack_helper *h;
	156
	157	h = __nf_conntrack_helper_find(name, l3num, protonum);
	158	#ifdef CONFIG_MODULES
	159	if (h == NULL) {
	160	if (request_module("nfct-helper-%s", name) == 0)
	161	h = __nf_conntrack_helper_find(name, l3num, protonum);
	162	}
	163	#endif
	164	if (h != NULL && !try_module_get(h->me))
	165	h = NULL;
	166
	167	return h;
	168	}
	169	EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
	170
1afc5679 PNA	171	struct nf_conn_help *
	172	nf_ct_helper_ext_add(struct nf_conn *ct,
	173	struct nf_conntrack_helper *helper, gfp_t gfp)
b560580a PM	174	{
	175	struct nf_conn_help *help;
	176
1afc5679 PNA	177	help = nf_ct_ext_add_length(ct, NF_CT_EXT_HELPER,
1afc5679 PNA	178	helper->data_len, gfp);
b560580a PM	179	if (help)
	180	INIT_HLIST_HEAD(&help->expectations);
	181	else
	182	pr_debug("failed to add helper extension area");
	183	return help;
	184	}
	185	EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
	186
b2a15a60 PM	187	int __nf_ct_try_assign_helper(struct nf_conn ct, struct nf_conn tmpl,
b2a15a60 PM	188	gfp_t flags)
226c0c0e	189	{
b2a15a60 PM	190	struct nf_conntrack_helper *helper = NULL;
b2a15a60 PM	191	struct nf_conn_help *help;
a9006892	192	struct net *net = nf_ct_net(ct);
226c0c0e	193	int ret = 0;
226c0c0e	194
6714cf54 PNA	195	/* We already got a helper explicitly attached. The function
	196	* nf_conntrack_alter_reply - in case NAT is in use - asks for looking
	197	* the helper up again. Since now the user is in full control of
	198	* making consistent helper configurations, skip this automatic
	199	* re-lookup, otherwise we'll lose the helper.
	200	*/
	201	if (test_bit(IPS_HELPER_BIT, &ct->status))
	202	return 0;
	203
b2a15a60 PM	204	if (tmpl != NULL) {
b2a15a60 PM	205	help = nfct_help(tmpl);
6714cf54	206	if (help != NULL) {
b2a15a60	207	helper = help->helper;
6714cf54 PNA	208	set_bit(IPS_HELPER_BIT, &ct->status);
6714cf54 PNA	209	}
b2a15a60 PM	210	}
	211
	212	help = nfct_help(ct);
a9006892	213	if (net->ct.sysctl_auto_assign_helper && helper == NULL) {
b2a15a60	214	helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
a9006892 EL	215	if (unlikely(!net->ct.auto_assign_helper_warned && helper)) {
	216	pr_info("nf_conntrack: automatic helper "
	217	"assignment is deprecated and it will "
	218	"be removed soon. Use the iptables CT target "
	219	"to attach helpers instead.\n");
	220	net->ct.auto_assign_helper_warned = true;
	221	}
	222	}
	223
226c0c0e PNA	224	if (helper == NULL) {
226c0c0e PNA	225	if (help)
a9b3cd7f	226	RCU_INIT_POINTER(help->helper, NULL);
226c0c0e PNA	227	goto out;
	228	}
	229
	230	if (help == NULL) {
1afc5679	231	help = nf_ct_helper_ext_add(ct, helper, flags);
226c0c0e PNA	232	if (help == NULL) {
	233	ret = -ENOMEM;
	234	goto out;
	235	}
	236	} else {
32f53760 PNA	237	/* We only allow helper re-assignment of the same sort since
	238	* we cannot reallocate the helper extension area.
	239	*/
6e2f0aa8 FW	240	struct nf_conntrack_helper *tmp = rcu_dereference(help->helper);
	241
	242	if (tmp && tmp->help != helper->help) {
32f53760 PNA	243	RCU_INIT_POINTER(help->helper, NULL);
	244	goto out;
	245	}
226c0c0e PNA	246	}
226c0c0e PNA	247
cf778b00	248	rcu_assign_pointer(help->helper, helper);
226c0c0e PNA	249	out:
	250	return ret;
	251	}
	252	EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
	253
7e5d03bb MJ	254	static inline int unhelp(struct nf_conntrack_tuple_hash *i,
	255	const struct nf_conntrack_helper *me)
	256	{
	257	struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
	258	struct nf_conn_help *help = nfct_help(ct);
	259
c5d277d2 ED	260	if (help && rcu_dereference_protected(
	261	help->helper,
	262	lockdep_is_held(&nf_conntrack_lock)
	263	) == me) {
7e5d03bb	264	nf_conntrack_event(IPCT_HELPER, ct);
a9b3cd7f	265	RCU_INIT_POINTER(help->helper, NULL);
7e5d03bb MJ	266	}
	267	return 0;
	268	}
	269
9858a3ae PNA	270	void nf_ct_helper_destroy(struct nf_conn *ct)
	271	{
	272	struct nf_conn_help *help = nfct_help(ct);
	273	struct nf_conntrack_helper *helper;
	274
	275	if (help) {
	276	rcu_read_lock();
	277	helper = rcu_dereference(help->helper);
	278	if (helper && helper->destroy)
	279	helper->destroy(ct);
	280	rcu_read_unlock();
	281	}
	282	}
	283
544d5c7d PNA	284	static LIST_HEAD(nf_ct_helper_expectfn_list);
	285
	286	void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
	287	{
	288	spin_lock_bh(&nf_conntrack_lock);
	289	list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
	290	spin_unlock_bh(&nf_conntrack_lock);
	291	}
	292	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);
	293
	294	void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
	295	{
	296	spin_lock_bh(&nf_conntrack_lock);
	297	list_del_rcu(&n->head);
	298	spin_unlock_bh(&nf_conntrack_lock);
	299	}
	300	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
	301
	302	struct nf_ct_helper_expectfn *
	303	nf_ct_helper_expectfn_find_by_name(const char *name)
	304	{
	305	struct nf_ct_helper_expectfn *cur;
	306	bool found = false;
	307
	308	rcu_read_lock();
	309	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	310	if (!strcmp(cur->name, name)) {
	311	found = true;
	312	break;
	313	}
	314	}
	315	rcu_read_unlock();
	316	return found ? cur : NULL;
	317	}
	318	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);
	319
	320	struct nf_ct_helper_expectfn *
	321	nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
	322	{
	323	struct nf_ct_helper_expectfn *cur;
	324	bool found = false;
	325
	326	rcu_read_lock();
	327	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	328	if (cur->expectfn == symbol) {
	329	found = true;
	330	break;
	331	}
	332	}
	333	rcu_read_unlock();
	334	return found ? cur : NULL;
	335	}
	336	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
	337
b20ab9cc PNA	338	__printf(3, 4)
	339	void nf_ct_helper_log(struct sk_buff skb, const struct nf_conn ct,
	340	const char *fmt, ...)
	341	{
	342	const struct nf_conn_help *help;
	343	const struct nf_conntrack_helper *helper;
	344
	345	/* Called from the helper function, this call never fails */
	346	help = nfct_help(ct);
	347
	348	/* rcu_read_lock()ed by nf_hook_slow */
	349	helper = rcu_dereference(help->helper);
	350
	351	nf_log_packet(nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL,
	352	"nf_ct_%s: dropping packet: %s ", helper->name, fmt);
	353	}
	354	EXPORT_SYMBOL_GPL(nf_ct_helper_log);
	355
7e5d03bb MJ	356	int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
7e5d03bb MJ	357	{
12f7a505 PNA	358	int ret = 0;
	359	struct nf_conntrack_helper *cur;
	360	struct hlist_node *n;
b8a7fe6c PM	361	unsigned int h = helper_hash(&me->tuple);
b8a7fe6c PM	362
6002f266 PM	363	BUG_ON(me->expect_policy == NULL);
6002f266 PM	364	BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
af9d32ad	365	BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
7e5d03bb	366
58a3c9bb	367	mutex_lock(&nf_ct_helper_mutex);
12f7a505 PNA	368	hlist_for_each_entry(cur, n, &nf_ct_helper_hash[h], hnode) {
	369	if (strncmp(cur->name, me->name, NF_CT_HELPER_NAME_LEN) == 0 &&
	370	cur->tuple.src.l3num == me->tuple.src.l3num &&
	371	cur->tuple.dst.protonum == me->tuple.dst.protonum) {
	372	ret = -EEXIST;
	373	goto out;
	374	}
	375	}
58a3c9bb	376	hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
b8a7fe6c	377	nf_ct_helper_count++;
12f7a505	378	out:
58a3c9bb	379	mutex_unlock(&nf_ct_helper_mutex);
12f7a505	380	return ret;
7e5d03bb	381	}
13b18339	382	EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
7e5d03bb	383
68047937 AD	384	static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
68047937 AD	385	struct net *net)
7e5d03bb	386	{
7e5d03bb	387	struct nf_conntrack_tuple_hash *h;
31f15875	388	struct nf_conntrack_expect *exp;
58c0fb0d	389	const struct hlist_node n, next;
ea781f19	390	const struct hlist_nulls_node *nn;
31f15875	391	unsigned int i;
7e5d03bb	392
7e5d03bb	393	/* Get rid of expectations */
31f15875 PM	394	for (i = 0; i < nf_ct_expect_hsize; i++) {
31f15875 PM	395	hlist_for_each_entry_safe(exp, n, next,
68047937	396	&net->ct.expect_hash[i], hnode) {
31f15875	397	struct nf_conn_help *help = nfct_help(exp->master);
c5d277d2 ED	398	if ((rcu_dereference_protected(
	399	help->helper,
	400	lockdep_is_held(&nf_conntrack_lock)
	401	) == me \|\| exp->helper == me) &&
31f15875 PM	402	del_timer(&exp->timeout)) {
	403	nf_ct_unlink_expect(exp);
	404	nf_ct_expect_put(exp);
	405	}
7e5d03bb MJ	406	}
	407	}
	408
	409	/* Get rid of expecteds, set helpers to NULL. */
38fb0afc	410	hlist_nulls_for_each_entry(h, nn, &net->ct.unconfirmed, hnnode)
7e5d03bb	411	unhelp(h, me);
d696c7bd	412	for (i = 0; i < net->ct.htable_size; i++) {
ea781f19	413	hlist_nulls_for_each_entry(h, nn, &net->ct.hash[i], hnnode)
7e5d03bb MJ	414	unhelp(h, me);
7e5d03bb MJ	415	}
68047937 AD	416	}
	417
	418	void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
	419	{
	420	struct net *net;
	421
	422	mutex_lock(&nf_ct_helper_mutex);
	423	hlist_del_rcu(&me->hnode);
	424	nf_ct_helper_count--;
	425	mutex_unlock(&nf_ct_helper_mutex);
	426
	427	/* Make sure every nothing is still using the helper unless its a
	428	* connection in the hash.
	429	*/
	430	synchronize_rcu();
	431
efb9a8c2	432	rtnl_lock();
68047937 AD	433	spin_lock_bh(&nf_conntrack_lock);
	434	for_each_net(net)
	435	__nf_conntrack_helper_unregister(me, net);
f8ba1aff	436	spin_unlock_bh(&nf_conntrack_lock);
efb9a8c2	437	rtnl_unlock();
7e5d03bb	438	}
13b18339	439	EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
ceceae1b	440
61eb3107	441	static struct nf_ct_ext_type helper_extend __read_mostly = {
ceceae1b YK	442	.len = sizeof(struct nf_conn_help),
	443	.align = __alignof__(struct nf_conn_help),
	444	.id = NF_CT_EXT_HELPER,
	445	};
	446
5e615b22	447	int nf_conntrack_helper_pernet_init(struct net *net)
ceceae1b	448	{
a9006892 EL	449	net->ct.auto_assign_helper_warned = false;
a9006892 EL	450	net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
5e615b22 G	451	return nf_conntrack_helper_init_sysctl(net);
5e615b22 G	452	}
b8a7fe6c	453
5e615b22 G	454	void nf_conntrack_helper_pernet_fini(struct net *net)
	455	{
	456	nf_conntrack_helper_fini_sysctl(net);
	457	}
a9006892	458
5e615b22 G	459	int nf_conntrack_helper_init(void)
	460	{
	461	int ret;
	462	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
	463	nf_ct_helper_hash =
	464	nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
	465	if (!nf_ct_helper_hash)
	466	return -ENOMEM;
	467
	468	ret = nf_ct_extend_register(&helper_extend);
	469	if (ret < 0) {
	470	pr_err("nf_ct_helper: Unable to register helper extension.\n");
	471	goto out_extend;
a9006892 EL	472	}
a9006892 EL	473
b8a7fe6c	474	return 0;
5e615b22	475	out_extend:
d862a662	476	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
5e615b22	477	return ret;
ceceae1b YK	478	}
ceceae1b YK	479
5e615b22	480	void nf_conntrack_helper_fini(void)
ceceae1b	481	{
5e615b22 G	482	nf_ct_extend_unregister(&helper_extend);
5e615b22 G	483	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
ceceae1b	484	}