[GitHub/mt8127/android_kernel_alcatel_ttab.git] / net / netfilter / nfnetlink_cthelper.c

/*
 * (C) 2012 Pablo Neira Ayuso <pablo@netfilter.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 (or any later at your option).
 *
 * This software has been sponsored by Vyatta Inc. <http://www.vyatta.com>
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/rculist.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/errno.h>
#include <net/netlink.h>
#include <net/sock.h>

#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_ecache.h>

#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_conntrack.h>
#include <linux/netfilter/nfnetlink_cthelper.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
MODULE_DESCRIPTION("nfnl_cthelper: User-space connection tracking helpers");

static int
nfnl_userspace_cthelper(struct sk_buff *skb, unsigned int protoff,
			struct nf_conn *ct, enum ip_conntrack_info ctinfo)
{
	const struct nf_conn_help *help;
	struct nf_conntrack_helper *helper;

	help = nfct_help(ct);
	if (help == NULL)
		return NF_DROP;

	/* rcu_read_lock()ed by nf_hook_slow */
	helper = rcu_dereference(help->helper);
	if (helper == NULL)
		return NF_DROP;

	/* This is an user-space helper not yet configured, skip. */
	if ((helper->flags &
	    (NF_CT_HELPER_F_USERSPACE | NF_CT_HELPER_F_CONFIGURED)) ==
	     NF_CT_HELPER_F_USERSPACE)
		return NF_ACCEPT;

	/* If the user-space helper is not available, don't block traffic. */
	return NF_QUEUE_NR(helper->queue_num) | NF_VERDICT_FLAG_QUEUE_BYPASS;
}

static const struct nla_policy nfnl_cthelper_tuple_pol[NFCTH_TUPLE_MAX+1] = {
	[NFCTH_TUPLE_L3PROTONUM] = { .type = NLA_U16, },
	[NFCTH_TUPLE_L4PROTONUM] = { .type = NLA_U8, },
};

static int
nfnl_cthelper_parse_tuple(struct nf_conntrack_tuple *tuple,
			  const struct nlattr *attr)
{
	struct nlattr *tb[NFCTH_TUPLE_MAX+1];

	nla_parse_nested(tb, NFCTH_TUPLE_MAX, attr, nfnl_cthelper_tuple_pol);

	if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM])
		return -EINVAL;

	tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM]));
	tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]);

	return 0;
}

static int
nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
{
	const struct nf_conn_help *help = nfct_help(ct);

	if (attr == NULL)
		return -EINVAL;

	if (help->helper->data_len == 0)
		return -EINVAL;

	memcpy(&help->data, nla_data(attr), help->helper->data_len);
	return 0;
}

static int
nfnl_cthelper_to_nlattr(struct sk_buff *skb, const struct nf_conn *ct)
{
	const struct nf_conn_help *help = nfct_help(ct);

	if (help->helper->data_len &&
	    nla_put(skb, CTA_HELP_INFO, help->helper->data_len, &help->data))
		goto nla_put_failure;

	return 0;

nla_put_failure:
	return -ENOSPC;
}

static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
	[NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
				.len = NF_CT_HELPER_NAME_LEN-1 },
	[NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
	[NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
};

static int
nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
			    const struct nlattr *attr)
{
	struct nlattr *tb[NFCTH_POLICY_MAX+1];

	nla_parse_nested(tb, NFCTH_POLICY_MAX, attr, nfnl_cthelper_expect_pol);

	if (!tb[NFCTH_POLICY_NAME] ||
	    !tb[NFCTH_POLICY_EXPECT_MAX] ||
	    !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
		return -EINVAL;

	strncpy(expect_policy->name,
		nla_data(tb[NFCTH_POLICY_NAME]), NF_CT_HELPER_NAME_LEN);
	expect_policy->max_expected =
		ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
	expect_policy->timeout =
		ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));

	return 0;
}

static const struct nla_policy
nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
	[NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
};

static int
nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
				  const struct nlattr *attr)
{
	int i, ret;
	struct nf_conntrack_expect_policy *expect_policy;
	struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];

	nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
					nfnl_cthelper_expect_policy_set);

	if (!tb[NFCTH_POLICY_SET_NUM])
		return -EINVAL;

	helper->expect_class_max =
		ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));

	if (helper->expect_class_max != 0 &&
	    helper->expect_class_max > NF_CT_MAX_EXPECT_CLASSES)
		return -EOVERFLOW;

	expect_policy = kzalloc(sizeof(struct nf_conntrack_expect_policy) *
				helper->expect_class_max, GFP_KERNEL);
	if (expect_policy == NULL)
		return -ENOMEM;

	for (i=0; i<helper->expect_class_max; i++) {
		if (!tb[NFCTH_POLICY_SET+i])
			goto err;

		ret = nfnl_cthelper_expect_policy(&expect_policy[i],
						  tb[NFCTH_POLICY_SET+i]);
		if (ret < 0)
			goto err;
	}
	helper->expect_policy = expect_policy;
	return 0;
err:
	kfree(expect_policy);
	return -EINVAL;
}

static int
nfnl_cthelper_create(const struct nlattr * const tb[],
		     struct nf_conntrack_tuple *tuple)
{
	struct nf_conntrack_helper *helper;
	int ret;

	if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
		return -EINVAL;

	helper = kzalloc(sizeof(struct nf_conntrack_helper), GFP_KERNEL);
	if (helper == NULL)
		return -ENOMEM;

	ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
	if (ret < 0)
		goto err;

	strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN);
	helper->data_len = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
	helper->flags |= NF_CT_HELPER_F_USERSPACE;
	memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));

	helper->me = THIS_MODULE;
	helper->help = nfnl_userspace_cthelper;
	helper->from_nlattr = nfnl_cthelper_from_nlattr;
	helper->to_nlattr = nfnl_cthelper_to_nlattr;

	/* Default to queue number zero, this can be updated at any time. */
	if (tb[NFCTH_QUEUE_NUM])
		helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));

	if (tb[NFCTH_STATUS]) {
		int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));

		switch(status) {
		case NFCT_HELPER_STATUS_ENABLED:
			helper->flags |= NF_CT_HELPER_F_CONFIGURED;
			break;
		case NFCT_HELPER_STATUS_DISABLED:
			helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
			break;
		}
	}

	ret = nf_conntrack_helper_register(helper);
	if (ret < 0)
		goto err;

	return 0;
err:
	kfree(helper);
	return ret;
}

static int
nfnl_cthelper_update(const struct nlattr * const tb[],
		     struct nf_conntrack_helper *helper)
{
	int ret;

	if (tb[NFCTH_PRIV_DATA_LEN])
		return -EBUSY;

	if (tb[NFCTH_POLICY]) {
		ret = nfnl_cthelper_parse_expect_policy(helper,
							tb[NFCTH_POLICY]);
		if (ret < 0)
			return ret;
	}
	if (tb[NFCTH_QUEUE_NUM])
		helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));

	if (tb[NFCTH_STATUS]) {
		int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));

		switch(status) {
		case NFCT_HELPER_STATUS_ENABLED:
			helper->flags |= NF_CT_HELPER_F_CONFIGURED;
			break;
		case NFCT_HELPER_STATUS_DISABLED:
			helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
			break;
		}
	}
	return 0;
}

static int
nfnl_cthelper_new(struct sock *nfnl, struct sk_buff *skb,
		  const struct nlmsghdr *nlh, const struct nlattr * const tb[])
{
	const char *helper_name;
	struct nf_conntrack_helper *cur, *helper = NULL;
	struct nf_conntrack_tuple tuple;
	int ret = 0, i;

	if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
		return -EINVAL;

	helper_name = nla_data(tb[NFCTH_NAME]);

	ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
	if (ret < 0)
		return ret;

	rcu_read_lock();
	for (i = 0; i < nf_ct_helper_hsize && !helper; i++) {
		hlist_for_each_entry_rcu(cur, &nf_ct_helper_hash[i], hnode) {

			/* skip non-userspace conntrack helpers. */
			if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
				continue;

			if (strncmp(cur->name, helper_name,
					NF_CT_HELPER_NAME_LEN) != 0)
				continue;

			if ((tuple.src.l3num != cur->tuple.src.l3num ||
			     tuple.dst.protonum != cur->tuple.dst.protonum))
				continue;

			if (nlh->nlmsg_flags & NLM_F_EXCL) {
				ret = -EEXIST;
				goto err;
			}
			helper = cur;
			break;
		}
	}
	rcu_read_unlock();

	if (helper == NULL)
		ret = nfnl_cthelper_create(tb, &tuple);
	else
		ret = nfnl_cthelper_update(tb, helper);

	return ret;
err:
	rcu_read_unlock();
	return ret;
}

static int
nfnl_cthelper_dump_tuple(struct sk_buff *skb,
			 struct nf_conntrack_helper *helper)
{
	struct nlattr *nest_parms;

	nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
	if (nest_parms == NULL)
		goto nla_put_failure;

	if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
			 htons(helper->tuple.src.l3num)))
		goto nla_put_failure;

	if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
		goto nla_put_failure;

	nla_nest_end(skb, nest_parms);
	return 0;

nla_put_failure:
	return -1;
}

static int
nfnl_cthelper_dump_policy(struct sk_buff *skb,
			struct nf_conntrack_helper *helper)
{
	int i;
	struct nlattr *nest_parms1, *nest_parms2;

	nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
	if (nest_parms1 == NULL)
		goto nla_put_failure;

	if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
			 htonl(helper->expect_class_max)))
		goto nla_put_failure;

	for (i=0; i<helper->expect_class_max; i++) {
		nest_parms2 = nla_nest_start(skb,
				(NFCTH_POLICY_SET+i) | NLA_F_NESTED);
		if (nest_parms2 == NULL)
			goto nla_put_failure;

		if (nla_put_string(skb, NFCTH_POLICY_NAME,
				   helper->expect_policy[i].name))
			goto nla_put_failure;

		if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
				 htonl(helper->expect_policy[i].max_expected)))
			goto nla_put_failure;

		if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
				 htonl(helper->expect_policy[i].timeout)))
			goto nla_put_failure;

		nla_nest_end(skb, nest_parms2);
	}
	nla_nest_end(skb, nest_parms1);
	return 0;

nla_put_failure:
	return -1;
}

static int
nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
			int event, struct nf_conntrack_helper *helper)
{
	struct nlmsghdr *nlh;
	struct nfgenmsg *nfmsg;
	unsigned int flags = portid ? NLM_F_MULTI : 0;
	int status;

	event |= NFNL_SUBSYS_CTHELPER << 8;
	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
	if (nlh == NULL)
		goto nlmsg_failure;

	nfmsg = nlmsg_data(nlh);
	nfmsg->nfgen_family = AF_UNSPEC;
	nfmsg->version = NFNETLINK_V0;
	nfmsg->res_id = 0;

	if (nla_put_string(skb, NFCTH_NAME, helper->name))
		goto nla_put_failure;

	if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
		goto nla_put_failure;

	if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
		goto nla_put_failure;

	if (nfnl_cthelper_dump_policy(skb, helper) < 0)
		goto nla_put_failure;

	if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
		goto nla_put_failure;

	if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
		status = NFCT_HELPER_STATUS_ENABLED;
	else
		status = NFCT_HELPER_STATUS_DISABLED;

	if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
		goto nla_put_failure;

	nlmsg_end(skb, nlh);
	return skb->len;

nlmsg_failure:
nla_put_failure:
	nlmsg_cancel(skb, nlh);
	return -1;
}

static int
nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
{
	struct nf_conntrack_helper *cur, *last;

	rcu_read_lock();
	last = (struct nf_conntrack_helper *)cb->args[1];
	for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
restart:
		hlist_for_each_entry_rcu(cur,
				&nf_ct_helper_hash[cb->args[0]], hnode) {

			/* skip non-userspace conntrack helpers. */
			if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
				continue;

			if (cb->args[1]) {
				if (cur != last)
					continue;
				cb->args[1] = 0;
			}
			if (nfnl_cthelper_fill_info(skb,
					    NETLINK_CB(cb->skb).portid,
					    cb->nlh->nlmsg_seq,
					    NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
					    NFNL_MSG_CTHELPER_NEW, cur) < 0) {
				cb->args[1] = (unsigned long)cur;
				goto out;
			}
		}
	}
	if (cb->args[1]) {
		cb->args[1] = 0;
		goto restart;
	}
out:
	rcu_read_unlock();
	return skb->len;
}

static int
nfnl_cthelper_get(struct sock *nfnl, struct sk_buff *skb,
		  const struct nlmsghdr *nlh, const struct nlattr * const tb[])
{
	int ret = -ENOENT, i;
	struct nf_conntrack_helper *cur;
	struct sk_buff *skb2;
	char *helper_name = NULL;
	struct nf_conntrack_tuple tuple;
	bool tuple_set = false;

	if (nlh->nlmsg_flags & NLM_F_DUMP) {
		struct netlink_dump_control c = {
			.dump = nfnl_cthelper_dump_table,
		};
		return netlink_dump_start(nfnl, skb, nlh, &c);
	}

	if (tb[NFCTH_NAME])
		helper_name = nla_data(tb[NFCTH_NAME]);

	if (tb[NFCTH_TUPLE]) {
		ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
		if (ret < 0)
			return ret;

		tuple_set = true;
	}

	for (i = 0; i < nf_ct_helper_hsize; i++) {
		hlist_for_each_entry_rcu(cur, &nf_ct_helper_hash[i], hnode) {

			/* skip non-userspace conntrack helpers. */
			if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
				continue;

			if (helper_name && strncmp(cur->name, helper_name,
						NF_CT_HELPER_NAME_LEN) != 0) {
				continue;
			}
			if (tuple_set &&
			    (tuple.src.l3num != cur->tuple.src.l3num ||
			     tuple.dst.protonum != cur->tuple.dst.protonum))
				continue;

			skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
			if (skb2 == NULL) {
				ret = -ENOMEM;
				break;
			}

			ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
						nlh->nlmsg_seq,
						NFNL_MSG_TYPE(nlh->nlmsg_type),
						NFNL_MSG_CTHELPER_NEW, cur);
			if (ret <= 0) {
				kfree_skb(skb2);
				break;
			}

			ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
						MSG_DONTWAIT);
			if (ret > 0)
				ret = 0;

			/* this avoids a loop in nfnetlink. */
			return ret == -EAGAIN ? -ENOBUFS : ret;
		}
	}
	return ret;
}

static int
nfnl_cthelper_del(struct sock *nfnl, struct sk_buff *skb,
	     const struct nlmsghdr *nlh, const struct nlattr * const tb[])
{
	char *helper_name = NULL;
	struct nf_conntrack_helper *cur;
	struct hlist_node *tmp;
	struct nf_conntrack_tuple tuple;
	bool tuple_set = false, found = false;
	int i, j = 0, ret;

	if (tb[NFCTH_NAME])
		helper_name = nla_data(tb[NFCTH_NAME]);

	if (tb[NFCTH_TUPLE]) {
		ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
		if (ret < 0)
			return ret;

		tuple_set = true;
	}

	for (i = 0; i < nf_ct_helper_hsize; i++) {
		hlist_for_each_entry_safe(cur, tmp, &nf_ct_helper_hash[i],
								hnode) {
			/* skip non-userspace conntrack helpers. */
			if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
				continue;

			j++;

			if (helper_name && strncmp(cur->name, helper_name,
						NF_CT_HELPER_NAME_LEN) != 0) {
				continue;
			}
			if (tuple_set &&
			    (tuple.src.l3num != cur->tuple.src.l3num ||
			     tuple.dst.protonum != cur->tuple.dst.protonum))
				continue;

			found = true;
			nf_conntrack_helper_unregister(cur);
		}
	}
	/* Make sure we return success if we flush and there is no helpers */
	return (found || j == 0) ? 0 : -ENOENT;
}

static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
	[NFCTH_NAME] = { .type = NLA_NUL_STRING,
			 .len = NF_CT_HELPER_NAME_LEN-1 },
	[NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
};

static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
	[NFNL_MSG_CTHELPER_NEW]		= { .call = nfnl_cthelper_new,
					    .attr_count = NFCTH_MAX,
					    .policy = nfnl_cthelper_policy },
	[NFNL_MSG_CTHELPER_GET]		= { .call = nfnl_cthelper_get,
					    .attr_count = NFCTH_MAX,
					    .policy = nfnl_cthelper_policy },
	[NFNL_MSG_CTHELPER_DEL]		= { .call = nfnl_cthelper_del,
					    .attr_count = NFCTH_MAX,
					    .policy = nfnl_cthelper_policy },
};

static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
	.name				= "cthelper",
	.subsys_id			= NFNL_SUBSYS_CTHELPER,
	.cb_count			= NFNL_MSG_CTHELPER_MAX,
	.cb				= nfnl_cthelper_cb,
};

MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);

static int __init nfnl_cthelper_init(void)
{
	int ret;

	ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
	if (ret < 0) {
		pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
		goto err_out;
	}
	return 0;
err_out:
	return ret;
}

static void __exit nfnl_cthelper_exit(void)
{
	struct nf_conntrack_helper *cur;
	struct hlist_node *tmp;
	int i;

	nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);

	for (i=0; i<nf_ct_helper_hsize; i++) {
		hlist_for_each_entry_safe(cur, tmp, &nf_ct_helper_hash[i],
									hnode) {
			/* skip non-userspace conntrack helpers. */
			if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
				continue;

			nf_conntrack_helper_unregister(cur);
		}
	}
}

module_init(nfnl_cthelper_init);
module_exit(nfnl_cthelper_exit);
Commit	Line	Data
12f7a505 PNA	1	/*
	2	* (C) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License version 2 as
	6	* published by the Free Software Foundation (or any later at your option).
	7	*
	8	* This software has been sponsored by Vyatta Inc. <http://www.vyatta.com>
	9	*/
	10	#include <linux/init.h>
	11	#include <linux/module.h>
	12	#include <linux/kernel.h>
	13	#include <linux/skbuff.h>
	14	#include <linux/netlink.h>
	15	#include <linux/rculist.h>
	16	#include <linux/slab.h>
	17	#include <linux/types.h>
	18	#include <linux/list.h>
	19	#include <linux/errno.h>
	20	#include <net/netlink.h>
	21	#include <net/sock.h>
	22
	23	#include <net/netfilter/nf_conntrack_helper.h>
	24	#include <net/netfilter/nf_conntrack_expect.h>
	25	#include <net/netfilter/nf_conntrack_ecache.h>
	26
	27	#include <linux/netfilter/nfnetlink.h>
	28	#include <linux/netfilter/nfnetlink_conntrack.h>
	29	#include <linux/netfilter/nfnetlink_cthelper.h>
	30
	31	MODULE_LICENSE("GPL");
	32	MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
	33	MODULE_DESCRIPTION("nfnl_cthelper: User-space connection tracking helpers");
	34
	35	static int
	36	nfnl_userspace_cthelper(struct sk_buff *skb, unsigned int protoff,
	37	struct nf_conn *ct, enum ip_conntrack_info ctinfo)
	38	{
	39	const struct nf_conn_help *help;
	40	struct nf_conntrack_helper *helper;
	41
	42	help = nfct_help(ct);
	43	if (help == NULL)
	44	return NF_DROP;
	45
	46	/* rcu_read_lock()ed by nf_hook_slow */
	47	helper = rcu_dereference(help->helper);
	48	if (helper == NULL)
	49	return NF_DROP;
	50
	51	/* This is an user-space helper not yet configured, skip. */
	52	if ((helper->flags &
	53	(NF_CT_HELPER_F_USERSPACE \| NF_CT_HELPER_F_CONFIGURED)) ==
	54	NF_CT_HELPER_F_USERSPACE)
	55	return NF_ACCEPT;
	56
	57	/* If the user-space helper is not available, don't block traffic. */
	58	return NF_QUEUE_NR(helper->queue_num) \| NF_VERDICT_FLAG_QUEUE_BYPASS;
	59	}
	60
	61	static const struct nla_policy nfnl_cthelper_tuple_pol[NFCTH_TUPLE_MAX+1] = {
	62	[NFCTH_TUPLE_L3PROTONUM] = { .type = NLA_U16, },
	63	[NFCTH_TUPLE_L4PROTONUM] = { .type = NLA_U8, },
	64	};
65
66	static int
67	nfnl_cthelper_parse_tuple(struct nf_conntrack_tuple *tuple,
68	const struct nlattr *attr)
69	{
70	struct nlattr *tb[NFCTH_TUPLE_MAX+1];
71
72	nla_parse_nested(tb, NFCTH_TUPLE_MAX, attr, nfnl_cthelper_tuple_pol);
73
74	if (!tb[NFCTH_TUPLE_L3PROTONUM] \|\| !tb[NFCTH_TUPLE_L4PROTONUM])
75	return -EINVAL;
76
fe31d1a8	77	tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM]));
12f7a505 PNA	78	tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]);
	79
	80	return 0;
	81	}
	82
	83	static int
	84	nfnl_cthelper_from_nlattr(struct nlattr attr, struct nf_conn ct)
	85	{
	86	const struct nf_conn_help *help = nfct_help(ct);
	87
7be54ca4 PNA	88	if (attr == NULL)
	89	return -EINVAL;
	90
12f7a505 PNA	91	if (help->helper->data_len == 0)
	92	return -EINVAL;
	93
	94	memcpy(&help->data, nla_data(attr), help->helper->data_len);
	95	return 0;
	96	}
	97
	98	static int
	99	nfnl_cthelper_to_nlattr(struct sk_buff skb, const struct nf_conn ct)
	100	{
	101	const struct nf_conn_help *help = nfct_help(ct);
	102
	103	if (help->helper->data_len &&
	104	nla_put(skb, CTA_HELP_INFO, help->helper->data_len, &help->data))
	105	goto nla_put_failure;
	106
	107	return 0;
	108
	109	nla_put_failure:
	110	return -ENOSPC;
	111	}
	112
	113	static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
	114	[NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
	115	.len = NF_CT_HELPER_NAME_LEN-1 },
	116	[NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
	117	[NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
	118	};
	119
	120	static int
	121	nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
	122	const struct nlattr *attr)
	123	{
	124	struct nlattr *tb[NFCTH_POLICY_MAX+1];
	125
	126	nla_parse_nested(tb, NFCTH_POLICY_MAX, attr, nfnl_cthelper_expect_pol);
	127
	128	if (!tb[NFCTH_POLICY_NAME] \|\|
	129	!tb[NFCTH_POLICY_EXPECT_MAX] \|\|
	130	!tb[NFCTH_POLICY_EXPECT_TIMEOUT])
	131	return -EINVAL;
	132
	133	strncpy(expect_policy->name,
	134	nla_data(tb[NFCTH_POLICY_NAME]), NF_CT_HELPER_NAME_LEN);
	135	expect_policy->max_expected =
	136	ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
	137	expect_policy->timeout =
	138	ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
	139
	140	return 0;
	141	}
	142
	143	static const struct nla_policy
	144	nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
	145	[NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
	146	};
	147
	148	static int
	149	nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
	150	const struct nlattr *attr)
	151	{
	152	int i, ret;
	153	struct nf_conntrack_expect_policy *expect_policy;
	154	struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];
155
156	nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
157	nfnl_cthelper_expect_policy_set);
158
159	if (!tb[NFCTH_POLICY_SET_NUM])
160	return -EINVAL;
161
162	helper->expect_class_max =
163	ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
164
165	if (helper->expect_class_max != 0 &&
166	helper->expect_class_max > NF_CT_MAX_EXPECT_CLASSES)
167	return -EOVERFLOW;
168
169	expect_policy = kzalloc(sizeof(struct nf_conntrack_expect_policy) *
170	helper->expect_class_max, GFP_KERNEL);
171	if (expect_policy == NULL)
172	return -ENOMEM;
173
174	for (i=0; i<helper->expect_class_max; i++) {
175	if (!tb[NFCTH_POLICY_SET+i])
176	goto err;
177
178	ret = nfnl_cthelper_expect_policy(&expect_policy[i],
179	tb[NFCTH_POLICY_SET+i]);
180	if (ret < 0)
181	goto err;
182	}
183	helper->expect_policy = expect_policy;
184	return 0;
185	err:
186	kfree(expect_policy);
187	return -EINVAL;
188	}
189
190	static int
191	nfnl_cthelper_create(const struct nlattr * const tb[],
192	struct nf_conntrack_tuple *tuple)
193	{
194	struct nf_conntrack_helper *helper;
195	int ret;
196
197	if (!tb[NFCTH_TUPLE] \|\| !tb[NFCTH_POLICY] \|\| !tb[NFCTH_PRIV_DATA_LEN])
198	return -EINVAL;
199
200	helper = kzalloc(sizeof(struct nf_conntrack_helper), GFP_KERNEL);
201	if (helper == NULL)
202	return -ENOMEM;
203
204	ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
205	if (ret < 0)
206	goto err;
207
208	strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN);
209	helper->data_len = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
210	helper->flags \|= NF_CT_HELPER_F_USERSPACE;
211	memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
212
213	helper->me = THIS_MODULE;
214	helper->help = nfnl_userspace_cthelper;
215	helper->from_nlattr = nfnl_cthelper_from_nlattr;
216	helper->to_nlattr = nfnl_cthelper_to_nlattr;
217
218	/* Default to queue number zero, this can be updated at any time. */
219	if (tb[NFCTH_QUEUE_NUM])
220	helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
221
222	if (tb[NFCTH_STATUS]) {
223	int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
224
225	switch(status) {
226	case NFCT_HELPER_STATUS_ENABLED:
227	helper->flags \|= NF_CT_HELPER_F_CONFIGURED;
228	break;
229	case NFCT_HELPER_STATUS_DISABLED:
230	helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
231	break;
232	}
233	}
234
235	ret = nf_conntrack_helper_register(helper);
236	if (ret < 0)
237	goto err;
238
239	return 0;
240	err:
241	kfree(helper);
242	return ret;
243	}
244
245	static int
246	nfnl_cthelper_update(const struct nlattr * const tb[],
247	struct nf_conntrack_helper *helper)
248	{
249	int ret;
250
251	if (tb[NFCTH_PRIV_DATA_LEN])
252	return -EBUSY;
253
254	if (tb[NFCTH_POLICY]) {
255	ret = nfnl_cthelper_parse_expect_policy(helper,
256	tb[NFCTH_POLICY]);
257	if (ret < 0)
258	return ret;
259	}
260	if (tb[NFCTH_QUEUE_NUM])
261	helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
262
263	if (tb[NFCTH_STATUS]) {
264	int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
265
266	switch(status) {
267	case NFCT_HELPER_STATUS_ENABLED:
268	helper->flags \|= NF_CT_HELPER_F_CONFIGURED;
269	break;
270	case NFCT_HELPER_STATUS_DISABLED:
271	helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
272	break;
273	}
274	}
275	return 0;
276	}
277
278	static int
279	nfnl_cthelper_new(struct sock nfnl, struct sk_buff skb,
280	const struct nlmsghdr nlh, const struct nlattr const tb[])
281	{
282	const char *helper_name;
283	struct nf_conntrack_helper cur, helper = NULL;
284	struct nf_conntrack_tuple tuple;
12f7a505 PNA	285	int ret = 0, i;
	286
	287	if (!tb[NFCTH_NAME] \|\| !tb[NFCTH_TUPLE])
	288	return -EINVAL;
	289
	290	helper_name = nla_data(tb[NFCTH_NAME]);
	291
	292	ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
	293	if (ret < 0)
	294	return ret;
	295
	296	rcu_read_lock();
	297	for (i = 0; i < nf_ct_helper_hsize && !helper; i++) {
b67bfe0d	298	hlist_for_each_entry_rcu(cur, &nf_ct_helper_hash[i], hnode) {
12f7a505 PNA	299
	300	/* skip non-userspace conntrack helpers. */
	301	if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
	302	continue;
	303
	304	if (strncmp(cur->name, helper_name,
	305	NF_CT_HELPER_NAME_LEN) != 0)
	306	continue;
	307
	308	if ((tuple.src.l3num != cur->tuple.src.l3num \|\|
	309	tuple.dst.protonum != cur->tuple.dst.protonum))
	310	continue;
	311
	312	if (nlh->nlmsg_flags & NLM_F_EXCL) {
	313	ret = -EEXIST;
	314	goto err;
	315	}
	316	helper = cur;
	317	break;
	318	}
	319	}
	320	rcu_read_unlock();
	321
	322	if (helper == NULL)
	323	ret = nfnl_cthelper_create(tb, &tuple);
	324	else
	325	ret = nfnl_cthelper_update(tb, helper);
	326
	327	return ret;
	328	err:
	329	rcu_read_unlock();
	330	return ret;
	331	}
	332
	333	static int
	334	nfnl_cthelper_dump_tuple(struct sk_buff *skb,
	335	struct nf_conntrack_helper *helper)
	336	{
	337	struct nlattr *nest_parms;
	338
	339	nest_parms = nla_nest_start(skb, NFCTH_TUPLE \| NLA_F_NESTED);
	340	if (nest_parms == NULL)
	341	goto nla_put_failure;
	342
	343	if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
	344	htons(helper->tuple.src.l3num)))
	345	goto nla_put_failure;
	346
	347	if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
	348	goto nla_put_failure;
	349
	350	nla_nest_end(skb, nest_parms);
	351	return 0;
	352
	353	nla_put_failure:
	354	return -1;
	355	}
	356
	357	static int
	358	nfnl_cthelper_dump_policy(struct sk_buff *skb,
	359	struct nf_conntrack_helper *helper)
	360	{
	361	int i;
	362	struct nlattr nest_parms1, nest_parms2;
363
364	nest_parms1 = nla_nest_start(skb, NFCTH_POLICY \| NLA_F_NESTED);
365	if (nest_parms1 == NULL)
366	goto nla_put_failure;
367
368	if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
369	htonl(helper->expect_class_max)))
370	goto nla_put_failure;
371
372	for (i=0; i<helper->expect_class_max; i++) {
373	nest_parms2 = nla_nest_start(skb,
374	(NFCTH_POLICY_SET+i) \| NLA_F_NESTED);
375	if (nest_parms2 == NULL)
376	goto nla_put_failure;
377
378	if (nla_put_string(skb, NFCTH_POLICY_NAME,
379	helper->expect_policy[i].name))
380	goto nla_put_failure;
381
382	if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
383	htonl(helper->expect_policy[i].max_expected)))
384	goto nla_put_failure;
385
386	if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
387	htonl(helper->expect_policy[i].timeout)))
388	goto nla_put_failure;
389
390	nla_nest_end(skb, nest_parms2);
391	}
392	nla_nest_end(skb, nest_parms1);
393	return 0;
394
395	nla_put_failure:
396	return -1;
397	}
398
399	static int
15e47304	400	nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
12f7a505 PNA	401	int event, struct nf_conntrack_helper *helper)
	402	{
	403	struct nlmsghdr *nlh;
	404	struct nfgenmsg *nfmsg;
15e47304	405	unsigned int flags = portid ? NLM_F_MULTI : 0;
12f7a505 PNA	406	int status;
	407
	408	event \|= NFNL_SUBSYS_CTHELPER << 8;
15e47304	409	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
12f7a505 PNA	410	if (nlh == NULL)
	411	goto nlmsg_failure;
	412
	413	nfmsg = nlmsg_data(nlh);
	414	nfmsg->nfgen_family = AF_UNSPEC;
	415	nfmsg->version = NFNETLINK_V0;
	416	nfmsg->res_id = 0;
	417
	418	if (nla_put_string(skb, NFCTH_NAME, helper->name))
	419	goto nla_put_failure;
	420
	421	if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
	422	goto nla_put_failure;
	423
	424	if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
	425	goto nla_put_failure;
	426
	427	if (nfnl_cthelper_dump_policy(skb, helper) < 0)
	428	goto nla_put_failure;
	429
	430	if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
	431	goto nla_put_failure;
	432
	433	if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
	434	status = NFCT_HELPER_STATUS_ENABLED;
	435	else
	436	status = NFCT_HELPER_STATUS_DISABLED;
	437
	438	if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
	439	goto nla_put_failure;
	440
	441	nlmsg_end(skb, nlh);
	442	return skb->len;
	443
	444	nlmsg_failure:
	445	nla_put_failure:
	446	nlmsg_cancel(skb, nlh);
	447	return -1;
	448	}
	449
	450	static int
	451	nfnl_cthelper_dump_table(struct sk_buff skb, struct netlink_callback cb)
	452	{
	453	struct nf_conntrack_helper cur, last;
12f7a505 PNA	454
	455	rcu_read_lock();
	456	last = (struct nf_conntrack_helper *)cb->args[1];
	457	for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
	458	restart:
b67bfe0d	459	hlist_for_each_entry_rcu(cur,
12f7a505 PNA	460	&nf_ct_helper_hash[cb->args[0]], hnode) {
	461
	462	/* skip non-userspace conntrack helpers. */
	463	if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
	464	continue;
	465
	466	if (cb->args[1]) {
	467	if (cur != last)
	468	continue;
	469	cb->args[1] = 0;
	470	}
	471	if (nfnl_cthelper_fill_info(skb,
15e47304	472	NETLINK_CB(cb->skb).portid,
12f7a505 PNA	473	cb->nlh->nlmsg_seq,
	474	NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
	475	NFNL_MSG_CTHELPER_NEW, cur) < 0) {
	476	cb->args[1] = (unsigned long)cur;
	477	goto out;
	478	}
	479	}
	480	}
	481	if (cb->args[1]) {
	482	cb->args[1] = 0;
	483	goto restart;
	484	}
	485	out:
	486	rcu_read_unlock();
	487	return skb->len;
	488	}
	489
	490	static int
	491	nfnl_cthelper_get(struct sock nfnl, struct sk_buff skb,
	492	const struct nlmsghdr nlh, const struct nlattr const tb[])
	493	{
	494	int ret = -ENOENT, i;
	495	struct nf_conntrack_helper *cur;
12f7a505 PNA	496	struct sk_buff *skb2;
	497	char *helper_name = NULL;
	498	struct nf_conntrack_tuple tuple;
	499	bool tuple_set = false;
	500
	501	if (nlh->nlmsg_flags & NLM_F_DUMP) {
	502	struct netlink_dump_control c = {
	503	.dump = nfnl_cthelper_dump_table,
	504	};
	505	return netlink_dump_start(nfnl, skb, nlh, &c);
	506	}
	507
	508	if (tb[NFCTH_NAME])
	509	helper_name = nla_data(tb[NFCTH_NAME]);
	510
	511	if (tb[NFCTH_TUPLE]) {
	512	ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
	513	if (ret < 0)
	514	return ret;
	515
	516	tuple_set = true;
	517	}
	518
	519	for (i = 0; i < nf_ct_helper_hsize; i++) {
b67bfe0d	520	hlist_for_each_entry_rcu(cur, &nf_ct_helper_hash[i], hnode) {
12f7a505 PNA	521
	522	/* skip non-userspace conntrack helpers. */
	523	if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
	524	continue;
	525
	526	if (helper_name && strncmp(cur->name, helper_name,
	527	NF_CT_HELPER_NAME_LEN) != 0) {
	528	continue;
	529	}
	530	if (tuple_set &&
	531	(tuple.src.l3num != cur->tuple.src.l3num \|\|
	532	tuple.dst.protonum != cur->tuple.dst.protonum))
	533	continue;
	534
	535	skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
	536	if (skb2 == NULL) {
	537	ret = -ENOMEM;
	538	break;
	539	}
	540
15e47304	541	ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
12f7a505 PNA	542	nlh->nlmsg_seq,
	543	NFNL_MSG_TYPE(nlh->nlmsg_type),
	544	NFNL_MSG_CTHELPER_NEW, cur);
	545	if (ret <= 0) {
	546	kfree_skb(skb2);
	547	break;
	548	}
	549
15e47304	550	ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
12f7a505 PNA	551	MSG_DONTWAIT);
	552	if (ret > 0)
	553	ret = 0;
	554
	555	/* this avoids a loop in nfnetlink. */
	556	return ret == -EAGAIN ? -ENOBUFS : ret;
	557	}
	558	}
	559	return ret;
	560	}
	561
	562	static int
	563	nfnl_cthelper_del(struct sock nfnl, struct sk_buff skb,
	564	const struct nlmsghdr nlh, const struct nlattr const tb[])
	565	{
	566	char *helper_name = NULL;
	567	struct nf_conntrack_helper *cur;
b67bfe0d	568	struct hlist_node *tmp;
12f7a505 PNA	569	struct nf_conntrack_tuple tuple;
	570	bool tuple_set = false, found = false;
	571	int i, j = 0, ret;
	572
	573	if (tb[NFCTH_NAME])
	574	helper_name = nla_data(tb[NFCTH_NAME]);
	575
	576	if (tb[NFCTH_TUPLE]) {
	577	ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
	578	if (ret < 0)
	579	return ret;
	580
	581	tuple_set = true;
	582	}
	583
	584	for (i = 0; i < nf_ct_helper_hsize; i++) {
b67bfe0d	585	hlist_for_each_entry_safe(cur, tmp, &nf_ct_helper_hash[i],
12f7a505 PNA	586	hnode) {
	587	/* skip non-userspace conntrack helpers. */
	588	if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
	589	continue;
	590
	591	j++;
	592
	593	if (helper_name && strncmp(cur->name, helper_name,
	594	NF_CT_HELPER_NAME_LEN) != 0) {
	595	continue;
	596	}
	597	if (tuple_set &&
	598	(tuple.src.l3num != cur->tuple.src.l3num \|\|
	599	tuple.dst.protonum != cur->tuple.dst.protonum))
	600	continue;
	601
	602	found = true;
	603	nf_conntrack_helper_unregister(cur);
	604	}
	605	}
	606	/* Make sure we return success if we flush and there is no helpers */
	607	return (found \|\| j == 0) ? 0 : -ENOENT;
	608	}
	609
	610	static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
	611	[NFCTH_NAME] = { .type = NLA_NUL_STRING,
	612	.len = NF_CT_HELPER_NAME_LEN-1 },
	613	[NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
	614	};
	615
	616	static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
	617	[NFNL_MSG_CTHELPER_NEW] = { .call = nfnl_cthelper_new,
	618	.attr_count = NFCTH_MAX,
	619	.policy = nfnl_cthelper_policy },
	620	[NFNL_MSG_CTHELPER_GET] = { .call = nfnl_cthelper_get,
	621	.attr_count = NFCTH_MAX,
	622	.policy = nfnl_cthelper_policy },
	623	[NFNL_MSG_CTHELPER_DEL] = { .call = nfnl_cthelper_del,
	624	.attr_count = NFCTH_MAX,
	625	.policy = nfnl_cthelper_policy },
	626	};
	627
	628	static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
	629	.name = "cthelper",
	630	.subsys_id = NFNL_SUBSYS_CTHELPER,
	631	.cb_count = NFNL_MSG_CTHELPER_MAX,
	632	.cb = nfnl_cthelper_cb,
	633	};
	634
	635	MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
	636
	637	static int __init nfnl_cthelper_init(void)
	638	{
	639	int ret;
	640
	641	ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
	642	if (ret < 0) {
	643	pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
	644	goto err_out;
	645	}
	646	return 0;
	647	err_out:
	648	return ret;
	649	}
650
651	static void __exit nfnl_cthelper_exit(void)
652	{
653	struct nf_conntrack_helper *cur;
b67bfe0d	654	struct hlist_node *tmp;
12f7a505 PNA	655	int i;
	656
	657	nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
	658
	659	for (i=0; i<nf_ct_helper_hsize; i++) {
b67bfe0d	660	hlist_for_each_entry_safe(cur, tmp, &nf_ct_helper_hash[i],
12f7a505 PNA	661	hnode) {
	662	/* skip non-userspace conntrack helpers. */
	663	if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
	664	continue;
	665
	666	nf_conntrack_helper_unregister(cur);
	667	}
	668	}
	669	}
	670
	671	module_init(nfnl_cthelper_init);
	672	module_exit(nfnl_cthelper_exit);