![Florian Westphal](/assets/img/avatar_default.png)
Chen Gang reports: the length of nla_data(cda[CTA_TIMEOUT_NAME]) is not limited in server side. And indeed, its used to strcpy to a fixed-sized buffer. Fortunately, nfnetlink users need CAP_NET_ADMIN. Reported-by: Chen Gang <gang.chen@asianux.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
436 lines
11 KiB
C
436 lines
11 KiB
C
/*
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* (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
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* (C) 2012 by Vyatta Inc. <http://www.vyatta.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation (or any later at your option).
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/rculist.h>
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#include <linux/rculist_nulls.h>
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#include <linux/types.h>
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#include <linux/timer.h>
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#include <linux/security.h>
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#include <linux/skbuff.h>
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#include <linux/errno.h>
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#include <linux/netlink.h>
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#include <linux/spinlock.h>
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#include <linux/interrupt.h>
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#include <linux/slab.h>
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#include <linux/netfilter.h>
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#include <net/netlink.h>
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#include <net/sock.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_core.h>
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#include <net/netfilter/nf_conntrack_l3proto.h>
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#include <net/netfilter/nf_conntrack_l4proto.h>
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#include <net/netfilter/nf_conntrack_tuple.h>
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#include <net/netfilter/nf_conntrack_timeout.h>
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#include <linux/netfilter/nfnetlink.h>
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#include <linux/netfilter/nfnetlink_cttimeout.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
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MODULE_DESCRIPTION("cttimeout: Extended Netfilter Connection Tracking timeout tuning");
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static LIST_HEAD(cttimeout_list);
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static const struct nla_policy cttimeout_nla_policy[CTA_TIMEOUT_MAX+1] = {
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[CTA_TIMEOUT_NAME] = { .type = NLA_NUL_STRING,
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.len = CTNL_TIMEOUT_NAME_MAX - 1},
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[CTA_TIMEOUT_L3PROTO] = { .type = NLA_U16 },
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[CTA_TIMEOUT_L4PROTO] = { .type = NLA_U8 },
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[CTA_TIMEOUT_DATA] = { .type = NLA_NESTED },
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};
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static int
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ctnl_timeout_parse_policy(struct ctnl_timeout *timeout,
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struct nf_conntrack_l4proto *l4proto,
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struct net *net,
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const struct nlattr *attr)
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{
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int ret = 0;
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if (likely(l4proto->ctnl_timeout.nlattr_to_obj)) {
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struct nlattr *tb[l4proto->ctnl_timeout.nlattr_max+1];
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nla_parse_nested(tb, l4proto->ctnl_timeout.nlattr_max,
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attr, l4proto->ctnl_timeout.nla_policy);
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ret = l4proto->ctnl_timeout.nlattr_to_obj(tb, net,
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&timeout->data);
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}
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return ret;
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}
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static int
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cttimeout_new_timeout(struct sock *ctnl, struct sk_buff *skb,
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const struct nlmsghdr *nlh,
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const struct nlattr * const cda[])
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{
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__u16 l3num;
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__u8 l4num;
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struct nf_conntrack_l4proto *l4proto;
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struct ctnl_timeout *timeout, *matching = NULL;
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struct net *net = sock_net(skb->sk);
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char *name;
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int ret;
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if (!cda[CTA_TIMEOUT_NAME] ||
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!cda[CTA_TIMEOUT_L3PROTO] ||
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!cda[CTA_TIMEOUT_L4PROTO] ||
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!cda[CTA_TIMEOUT_DATA])
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return -EINVAL;
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name = nla_data(cda[CTA_TIMEOUT_NAME]);
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l3num = ntohs(nla_get_be16(cda[CTA_TIMEOUT_L3PROTO]));
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l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]);
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list_for_each_entry(timeout, &cttimeout_list, head) {
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if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
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continue;
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if (nlh->nlmsg_flags & NLM_F_EXCL)
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return -EEXIST;
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matching = timeout;
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break;
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}
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l4proto = nf_ct_l4proto_find_get(l3num, l4num);
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/* This protocol is not supportted, skip. */
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if (l4proto->l4proto != l4num) {
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ret = -EOPNOTSUPP;
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goto err_proto_put;
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}
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if (matching) {
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if (nlh->nlmsg_flags & NLM_F_REPLACE) {
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/* You cannot replace one timeout policy by another of
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* different kind, sorry.
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*/
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if (matching->l3num != l3num ||
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matching->l4proto->l4proto != l4num) {
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ret = -EINVAL;
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goto err_proto_put;
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}
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ret = ctnl_timeout_parse_policy(matching, l4proto, net,
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cda[CTA_TIMEOUT_DATA]);
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return ret;
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}
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ret = -EBUSY;
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goto err_proto_put;
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}
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timeout = kzalloc(sizeof(struct ctnl_timeout) +
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l4proto->ctnl_timeout.obj_size, GFP_KERNEL);
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if (timeout == NULL) {
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ret = -ENOMEM;
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goto err_proto_put;
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}
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ret = ctnl_timeout_parse_policy(timeout, l4proto, net,
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cda[CTA_TIMEOUT_DATA]);
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if (ret < 0)
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goto err;
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strcpy(timeout->name, nla_data(cda[CTA_TIMEOUT_NAME]));
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timeout->l3num = l3num;
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timeout->l4proto = l4proto;
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atomic_set(&timeout->refcnt, 1);
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list_add_tail_rcu(&timeout->head, &cttimeout_list);
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return 0;
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err:
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kfree(timeout);
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err_proto_put:
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nf_ct_l4proto_put(l4proto);
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return ret;
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}
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static int
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ctnl_timeout_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
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int event, struct ctnl_timeout *timeout)
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{
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struct nlmsghdr *nlh;
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struct nfgenmsg *nfmsg;
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unsigned int flags = portid ? NLM_F_MULTI : 0;
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struct nf_conntrack_l4proto *l4proto = timeout->l4proto;
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event |= NFNL_SUBSYS_CTNETLINK_TIMEOUT << 8;
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nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
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if (nlh == NULL)
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goto nlmsg_failure;
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nfmsg = nlmsg_data(nlh);
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nfmsg->nfgen_family = AF_UNSPEC;
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nfmsg->version = NFNETLINK_V0;
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nfmsg->res_id = 0;
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if (nla_put_string(skb, CTA_TIMEOUT_NAME, timeout->name) ||
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nla_put_be16(skb, CTA_TIMEOUT_L3PROTO, htons(timeout->l3num)) ||
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nla_put_u8(skb, CTA_TIMEOUT_L4PROTO, timeout->l4proto->l4proto) ||
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nla_put_be32(skb, CTA_TIMEOUT_USE,
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htonl(atomic_read(&timeout->refcnt))))
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goto nla_put_failure;
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if (likely(l4proto->ctnl_timeout.obj_to_nlattr)) {
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struct nlattr *nest_parms;
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int ret;
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nest_parms = nla_nest_start(skb,
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CTA_TIMEOUT_DATA | NLA_F_NESTED);
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if (!nest_parms)
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goto nla_put_failure;
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ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, &timeout->data);
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if (ret < 0)
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goto nla_put_failure;
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nla_nest_end(skb, nest_parms);
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}
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nlmsg_end(skb, nlh);
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return skb->len;
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nlmsg_failure:
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nla_put_failure:
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nlmsg_cancel(skb, nlh);
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return -1;
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}
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static int
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ctnl_timeout_dump(struct sk_buff *skb, struct netlink_callback *cb)
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{
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struct ctnl_timeout *cur, *last;
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if (cb->args[2])
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return 0;
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last = (struct ctnl_timeout *)cb->args[1];
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if (cb->args[1])
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cb->args[1] = 0;
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rcu_read_lock();
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list_for_each_entry_rcu(cur, &cttimeout_list, head) {
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if (last && cur != last)
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continue;
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if (ctnl_timeout_fill_info(skb, NETLINK_CB(cb->skb).portid,
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cb->nlh->nlmsg_seq,
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NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
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IPCTNL_MSG_TIMEOUT_NEW, cur) < 0) {
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cb->args[1] = (unsigned long)cur;
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break;
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}
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}
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if (!cb->args[1])
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cb->args[2] = 1;
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rcu_read_unlock();
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return skb->len;
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}
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static int
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cttimeout_get_timeout(struct sock *ctnl, struct sk_buff *skb,
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const struct nlmsghdr *nlh,
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const struct nlattr * const cda[])
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{
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int ret = -ENOENT;
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char *name;
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struct ctnl_timeout *cur;
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if (nlh->nlmsg_flags & NLM_F_DUMP) {
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struct netlink_dump_control c = {
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.dump = ctnl_timeout_dump,
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};
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return netlink_dump_start(ctnl, skb, nlh, &c);
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}
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if (!cda[CTA_TIMEOUT_NAME])
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return -EINVAL;
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name = nla_data(cda[CTA_TIMEOUT_NAME]);
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list_for_each_entry(cur, &cttimeout_list, head) {
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struct sk_buff *skb2;
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if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
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continue;
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skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
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if (skb2 == NULL) {
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ret = -ENOMEM;
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break;
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}
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ret = ctnl_timeout_fill_info(skb2, NETLINK_CB(skb).portid,
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nlh->nlmsg_seq,
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NFNL_MSG_TYPE(nlh->nlmsg_type),
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IPCTNL_MSG_TIMEOUT_NEW, cur);
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if (ret <= 0) {
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kfree_skb(skb2);
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break;
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}
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ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).portid,
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MSG_DONTWAIT);
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if (ret > 0)
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ret = 0;
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/* this avoids a loop in nfnetlink. */
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return ret == -EAGAIN ? -ENOBUFS : ret;
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}
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return ret;
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}
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/* try to delete object, fail if it is still in use. */
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static int ctnl_timeout_try_del(struct ctnl_timeout *timeout)
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{
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int ret = 0;
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/* we want to avoid races with nf_ct_timeout_find_get. */
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if (atomic_dec_and_test(&timeout->refcnt)) {
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/* We are protected by nfnl mutex. */
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list_del_rcu(&timeout->head);
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nf_ct_l4proto_put(timeout->l4proto);
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kfree_rcu(timeout, rcu_head);
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} else {
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/* still in use, restore reference counter. */
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atomic_inc(&timeout->refcnt);
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ret = -EBUSY;
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}
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return ret;
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}
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static int
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cttimeout_del_timeout(struct sock *ctnl, struct sk_buff *skb,
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const struct nlmsghdr *nlh,
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const struct nlattr * const cda[])
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{
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char *name;
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struct ctnl_timeout *cur;
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int ret = -ENOENT;
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if (!cda[CTA_TIMEOUT_NAME]) {
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list_for_each_entry(cur, &cttimeout_list, head)
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ctnl_timeout_try_del(cur);
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return 0;
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}
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name = nla_data(cda[CTA_TIMEOUT_NAME]);
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list_for_each_entry(cur, &cttimeout_list, head) {
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if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
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continue;
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ret = ctnl_timeout_try_del(cur);
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if (ret < 0)
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return ret;
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break;
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}
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return ret;
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}
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#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
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static struct ctnl_timeout *ctnl_timeout_find_get(const char *name)
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{
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struct ctnl_timeout *timeout, *matching = NULL;
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rcu_read_lock();
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list_for_each_entry_rcu(timeout, &cttimeout_list, head) {
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if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
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continue;
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if (!try_module_get(THIS_MODULE))
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goto err;
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if (!atomic_inc_not_zero(&timeout->refcnt)) {
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module_put(THIS_MODULE);
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goto err;
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}
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matching = timeout;
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break;
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}
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err:
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rcu_read_unlock();
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return matching;
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}
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static void ctnl_timeout_put(struct ctnl_timeout *timeout)
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{
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atomic_dec(&timeout->refcnt);
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module_put(THIS_MODULE);
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}
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#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
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static const struct nfnl_callback cttimeout_cb[IPCTNL_MSG_TIMEOUT_MAX] = {
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[IPCTNL_MSG_TIMEOUT_NEW] = { .call = cttimeout_new_timeout,
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.attr_count = CTA_TIMEOUT_MAX,
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.policy = cttimeout_nla_policy },
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[IPCTNL_MSG_TIMEOUT_GET] = { .call = cttimeout_get_timeout,
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.attr_count = CTA_TIMEOUT_MAX,
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.policy = cttimeout_nla_policy },
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[IPCTNL_MSG_TIMEOUT_DELETE] = { .call = cttimeout_del_timeout,
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.attr_count = CTA_TIMEOUT_MAX,
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.policy = cttimeout_nla_policy },
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};
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static const struct nfnetlink_subsystem cttimeout_subsys = {
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.name = "conntrack_timeout",
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.subsys_id = NFNL_SUBSYS_CTNETLINK_TIMEOUT,
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.cb_count = IPCTNL_MSG_TIMEOUT_MAX,
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.cb = cttimeout_cb,
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};
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MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK_TIMEOUT);
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static int __init cttimeout_init(void)
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{
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int ret;
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ret = nfnetlink_subsys_register(&cttimeout_subsys);
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if (ret < 0) {
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pr_err("cttimeout_init: cannot register cttimeout with "
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"nfnetlink.\n");
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goto err_out;
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}
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#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
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RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, ctnl_timeout_find_get);
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RCU_INIT_POINTER(nf_ct_timeout_put_hook, ctnl_timeout_put);
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#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
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return 0;
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err_out:
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return ret;
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}
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static void __exit cttimeout_exit(void)
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{
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struct ctnl_timeout *cur, *tmp;
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pr_info("cttimeout: unregistering from nfnetlink.\n");
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nfnetlink_subsys_unregister(&cttimeout_subsys);
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list_for_each_entry_safe(cur, tmp, &cttimeout_list, head) {
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list_del_rcu(&cur->head);
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/* We are sure that our objects have no clients at this point,
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* it's safe to release them all without checking refcnt.
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*/
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nf_ct_l4proto_put(cur->l4proto);
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kfree_rcu(cur, rcu_head);
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}
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#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
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RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, NULL);
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RCU_INIT_POINTER(nf_ct_timeout_put_hook, NULL);
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#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
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}
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module_init(cttimeout_init);
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module_exit(cttimeout_exit);
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