// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * (C) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
 *
 * 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 <linux/capability.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");

struct nfnl_cthelper {
        struct list_head                list;
        struct nf_conntrack_helper      helper;
};

static LIST_HEAD(nfnl_cthelper_list);

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_thresh */
        helper = rcu_dereference(help->helper);
        if (helper == NULL)
                return NF_DROP;

        /* This is a 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)
{
        int err;
        struct nlattr *tb[NFCTH_TUPLE_MAX+1];

        err = nla_parse_nested_deprecated(tb, NFCTH_TUPLE_MAX, attr,
                                          nfnl_cthelper_tuple_pol, NULL);
        if (err < 0)
                return err;

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

        /* Not all fields are initialized so first zero the tuple */
        memset(tuple, 0, sizeof(struct nf_conntrack_tuple));

        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)
{
        struct nf_conn_help *help = nfct_help(ct);
        const struct nf_conntrack_helper *helper;

        if (attr == NULL)
                return -EINVAL;

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

        nla_memcpy(help->data, attr, sizeof(help->data));
        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);
        const struct nf_conntrack_helper *helper;

        helper = rcu_dereference(help->helper);
        if (helper && helper->data_len &&
            nla_put(skb, CTA_HELP_INFO, 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)
{
        int err;
        struct nlattr *tb[NFCTH_POLICY_MAX+1];

        err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_MAX, attr,
                                          nfnl_cthelper_expect_pol, NULL);
        if (err < 0)
                return err;

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

        nla_strscpy(expect_policy->name,
                    tb[NFCTH_POLICY_NAME], NF_CT_HELPER_NAME_LEN);
        expect_policy->max_expected =
                ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
        if (expect_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
                return -EINVAL;

        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];
        unsigned int class_max;

        ret = nla_parse_nested_deprecated(tb, NFCTH_POLICY_SET_MAX, attr,
                                          nfnl_cthelper_expect_policy_set,
                                          NULL);
        if (ret < 0)
                return ret;

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

        class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
        if (class_max == 0)
                return -EINVAL;
        if (class_max > NF_CT_MAX_EXPECT_CLASSES)
                return -EOVERFLOW;

        expect_policy = kzalloc_objs(struct nf_conntrack_expect_policy,
                                     class_max);
        if (expect_policy == NULL)
                return -ENOMEM;

        for (i = 0; i < 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_class_max = class_max - 1;
        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;
        struct nfnl_cthelper *nfcth;
        unsigned int size;
        int ret;

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

        nfcth = kzalloc_obj(*nfcth);
        if (nfcth == NULL)
                return -ENOMEM;
        helper = &nfcth->helper;

        ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
        if (ret < 0)
                goto err1;

        nla_strscpy(helper->name,
                    tb[NFCTH_NAME], NF_CT_HELPER_NAME_LEN);
        size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
        if (size > sizeof_field(struct nf_conn_help, data)) {
                ret = -ENOMEM;
                goto err2;
        }
        helper->data_len = size;

        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 err2;

        list_add_tail(&nfcth->list, &nfnl_cthelper_list);
        return 0;
err2:
        kfree(helper->expect_policy);
err1:
        kfree(nfcth);
        return ret;
}

static int
nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy *policy,
                                struct nf_conntrack_expect_policy *new_policy,
                                const struct nlattr *attr)
{
        struct nlattr *tb[NFCTH_POLICY_MAX + 1];
        int err;

        err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_MAX, attr,
                                          nfnl_cthelper_expect_pol, NULL);
        if (err < 0)
                return err;

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

        if (nla_strcmp(tb[NFCTH_POLICY_NAME], policy->name))
                return -EBUSY;

        new_policy->max_expected =
                ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
        if (new_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
                return -EINVAL;

        new_policy->timeout =
                ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));

        return 0;
}

static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
                                           struct nf_conntrack_helper *helper)
{
        struct nf_conntrack_expect_policy *new_policy;
        struct nf_conntrack_expect_policy *policy;
        int i, ret = 0;

        new_policy = kmalloc_objs(*new_policy, helper->expect_class_max + 1);
        if (!new_policy)
                return -ENOMEM;

        /* Check first that all policy attributes are well-formed, so we don't
         * leave things in inconsistent state on errors.
         */
        for (i = 0; i < helper->expect_class_max + 1; i++) {

                if (!tb[NFCTH_POLICY_SET + i]) {
                        ret = -EINVAL;
                        goto err;
                }

                ret = nfnl_cthelper_update_policy_one(&helper->expect_policy[i],
                                                      &new_policy[i],
                                                      tb[NFCTH_POLICY_SET + i]);
                if (ret < 0)
                        goto err;
        }
        /* Now we can safely update them. */
        for (i = 0; i < helper->expect_class_max + 1; i++) {
                policy = (struct nf_conntrack_expect_policy *)
                                &helper->expect_policy[i];
                policy->max_expected = new_policy->max_expected;
                policy->timeout = new_policy->timeout;
        }

err:
        kfree(new_policy);
        return ret;
}

static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
                                       const struct nlattr *attr)
{
        struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
        unsigned int class_max;
        int err;

        err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_SET_MAX, attr,
                                          nfnl_cthelper_expect_policy_set,
                                          NULL);
        if (err < 0)
                return err;

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

        class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
        if (helper->expect_class_max + 1 != class_max)
                return -EBUSY;

        return nfnl_cthelper_update_policy_all(tb, helper);
}

static int
nfnl_cthelper_update(const struct nlattr * const tb[],
                     struct nf_conntrack_helper *helper)
{
        u32 size;
        int ret;

        if (tb[NFCTH_PRIV_DATA_LEN]) {
                size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
                if (size != helper->data_len)
                        return -EBUSY;
        }

        if (tb[NFCTH_POLICY]) {
                ret = nfnl_cthelper_update_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 sk_buff *skb, const struct nfnl_info *info,
                             const struct nlattr * const tb[])
{
        const char *helper_name;
        struct nf_conntrack_helper *cur, *helper = NULL;
        struct nf_conntrack_tuple tuple;
        struct nfnl_cthelper *nlcth;
        int ret = 0;

        if (!capable(CAP_NET_ADMIN))
                return -EPERM;

        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;

        list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
                cur = &nlcth->helper;

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

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

                if (info->nlh->nlmsg_flags & NLM_F_EXCL)
                        return -EEXIST;

                helper = cur;
                break;
        }

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

        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);
        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);
        if (nest_parms1 == NULL)
                goto nla_put_failure;

        if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
                         htonl(helper->expect_class_max + 1)))
                goto nla_put_failure;

        for (i = 0; i < helper->expect_class_max + 1; i++) {
                nest_parms2 = nla_nest_start(skb, (NFCTH_POLICY_SET + i));
                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;
        unsigned int flags = portid ? NLM_F_MULTI : 0;
        int status;

        event = nfnl_msg_type(NFNL_SUBSYS_CTHELPER, event);
        nlh = nfnl_msg_put(skb, portid, seq, event, flags, AF_UNSPEC,
                           NFNETLINK_V0, 0);
        if (!nlh)
                goto nlmsg_failure;

        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 sk_buff *skb, const struct nfnl_info *info,
                             const struct nlattr * const tb[])
{
        int ret = -ENOENT;
        struct nf_conntrack_helper *cur;
        struct sk_buff *skb2;
        char *helper_name = NULL;
        struct nf_conntrack_tuple tuple;
        struct nfnl_cthelper *nlcth;
        bool tuple_set = false;

        if (!capable(CAP_NET_ADMIN))
                return -EPERM;

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

        list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
                cur = &nlcth->helper;
                if (helper_name &&
                    strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
                        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,
                                              info->nlh->nlmsg_seq,
                                              NFNL_MSG_TYPE(info->nlh->nlmsg_type),
                                              NFNL_MSG_CTHELPER_NEW, cur);
                if (ret <= 0) {
                        kfree_skb(skb2);
                        break;
                }

                ret = nfnetlink_unicast(skb2, info->net, NETLINK_CB(skb).portid);
                break;
        }

        return ret;
}

static int nfnl_cthelper_del(struct sk_buff *skb, const struct nfnl_info *info,
                             const struct nlattr * const tb[])
{
        char *helper_name = NULL;
        struct nf_conntrack_helper *cur;
        struct nf_conntrack_tuple tuple;
        bool tuple_set = false, found = false;
        struct nfnl_cthelper *nlcth, *n;
        int j = 0, ret;

        if (!capable(CAP_NET_ADMIN))
                return -EPERM;

        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;
        }

        ret = -ENOENT;
        list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
                cur = &nlcth->helper;
                j++;

                if (helper_name &&
                    strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
                        continue;

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

                if (refcount_dec_if_one(&cur->refcnt)) {
                        found = true;
                        nf_conntrack_helper_unregister(cur);
                        kfree(cur->expect_policy);

                        list_del(&nlcth->list);
                        kfree(nlcth);
                } else {
                        ret = -EBUSY;
                }
        }

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

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, },
        [NFCTH_PRIV_DATA_LEN] = { .type = NLA_U32, },
        [NFCTH_STATUS] = { .type = NLA_U32, },
};

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

        nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);

        list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
                cur = &nlcth->helper;

                nf_conntrack_helper_unregister(cur);
                kfree(cur->expect_policy);
                kfree(nlcth);
        }
}

module_init(nfnl_cthelper_init);
module_exit(nfnl_cthelper_exit);