246 строки
6.0 KiB
C
246 строки
6.0 KiB
C
/* Netfilter messages via netlink socket. Allows for user space
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* protocol helpers and general trouble making from userspace.
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*
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* (C) 2001 by Jay Schulist <jschlst@samba.org>,
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* (C) 2002-2005 by Harald Welte <laforge@gnumonks.org>
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* (C) 2005,2007 by Pablo Neira Ayuso <pablo@netfilter.org>
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*
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* Initial netfilter messages via netlink development funded and
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* generally made possible by Network Robots, Inc. (www.networkrobots.com)
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*
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* Further development of this code funded by Astaro AG (http://www.astaro.com)
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*
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* This software may be used and distributed according to the terms
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* of the GNU General Public License, incorporated herein by reference.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/sockios.h>
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#include <linux/net.h>
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#include <linux/skbuff.h>
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#include <asm/uaccess.h>
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#include <asm/system.h>
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#include <net/sock.h>
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#include <net/netlink.h>
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#include <linux/init.h>
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#include <linux/netlink.h>
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#include <linux/netfilter/nfnetlink.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
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MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
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static char __initdata nfversion[] = "0.30";
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static const struct nfnetlink_subsystem __rcu *subsys_table[NFNL_SUBSYS_COUNT];
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static DEFINE_MUTEX(nfnl_mutex);
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void nfnl_lock(void)
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{
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mutex_lock(&nfnl_mutex);
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}
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EXPORT_SYMBOL_GPL(nfnl_lock);
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void nfnl_unlock(void)
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{
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mutex_unlock(&nfnl_mutex);
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}
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EXPORT_SYMBOL_GPL(nfnl_unlock);
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int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
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{
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nfnl_lock();
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if (subsys_table[n->subsys_id]) {
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nfnl_unlock();
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return -EBUSY;
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}
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rcu_assign_pointer(subsys_table[n->subsys_id], n);
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nfnl_unlock();
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return 0;
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}
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EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
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int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
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{
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nfnl_lock();
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subsys_table[n->subsys_id] = NULL;
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nfnl_unlock();
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synchronize_rcu();
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return 0;
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}
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EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
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static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
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{
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u_int8_t subsys_id = NFNL_SUBSYS_ID(type);
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if (subsys_id >= NFNL_SUBSYS_COUNT)
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return NULL;
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return rcu_dereference(subsys_table[subsys_id]);
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}
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static inline const struct nfnl_callback *
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nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss)
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{
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u_int8_t cb_id = NFNL_MSG_TYPE(type);
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if (cb_id >= ss->cb_count)
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return NULL;
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return &ss->cb[cb_id];
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}
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int nfnetlink_has_listeners(struct net *net, unsigned int group)
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{
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return netlink_has_listeners(net->nfnl, group);
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}
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EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
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int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 pid,
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unsigned group, int echo, gfp_t flags)
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{
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return nlmsg_notify(net->nfnl, skb, pid, group, echo, flags);
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}
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EXPORT_SYMBOL_GPL(nfnetlink_send);
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int nfnetlink_set_err(struct net *net, u32 pid, u32 group, int error)
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{
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return netlink_set_err(net->nfnl, pid, group, error);
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}
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EXPORT_SYMBOL_GPL(nfnetlink_set_err);
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int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u_int32_t pid, int flags)
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{
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return netlink_unicast(net->nfnl, skb, pid, flags);
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}
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EXPORT_SYMBOL_GPL(nfnetlink_unicast);
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/* Process one complete nfnetlink message. */
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static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
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{
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struct net *net = sock_net(skb->sk);
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const struct nfnl_callback *nc;
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const struct nfnetlink_subsystem *ss;
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int type, err;
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if (security_netlink_recv(skb, CAP_NET_ADMIN))
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return -EPERM;
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/* All the messages must at least contain nfgenmsg */
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if (nlh->nlmsg_len < NLMSG_LENGTH(sizeof(struct nfgenmsg)))
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return 0;
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type = nlh->nlmsg_type;
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replay:
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rcu_read_lock();
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ss = nfnetlink_get_subsys(type);
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if (!ss) {
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#ifdef CONFIG_MODULES
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rcu_read_unlock();
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request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
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rcu_read_lock();
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ss = nfnetlink_get_subsys(type);
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if (!ss)
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#endif
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{
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rcu_read_unlock();
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return -EINVAL;
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}
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}
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nc = nfnetlink_find_client(type, ss);
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if (!nc) {
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rcu_read_unlock();
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return -EINVAL;
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}
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{
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int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
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u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
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struct nlattr *cda[ss->cb[cb_id].attr_count + 1];
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struct nlattr *attr = (void *)nlh + min_len;
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int attrlen = nlh->nlmsg_len - min_len;
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err = nla_parse(cda, ss->cb[cb_id].attr_count,
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attr, attrlen, ss->cb[cb_id].policy);
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if (err < 0)
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return err;
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if (nc->call_rcu) {
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err = nc->call_rcu(net->nfnl, skb, nlh,
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(const struct nlattr **)cda);
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rcu_read_unlock();
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} else {
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rcu_read_unlock();
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nfnl_lock();
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if (rcu_dereference_protected(
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subsys_table[NFNL_SUBSYS_ID(type)],
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lockdep_is_held(&nfnl_mutex)) != ss ||
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nfnetlink_find_client(type, ss) != nc)
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err = -EAGAIN;
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else
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err = nc->call(net->nfnl, skb, nlh,
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(const struct nlattr **)cda);
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nfnl_unlock();
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}
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if (err == -EAGAIN)
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goto replay;
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return err;
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}
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}
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static void nfnetlink_rcv(struct sk_buff *skb)
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{
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netlink_rcv_skb(skb, &nfnetlink_rcv_msg);
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}
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static int __net_init nfnetlink_net_init(struct net *net)
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{
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struct sock *nfnl;
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nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, NFNLGRP_MAX,
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nfnetlink_rcv, NULL, THIS_MODULE);
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if (!nfnl)
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return -ENOMEM;
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net->nfnl_stash = nfnl;
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rcu_assign_pointer(net->nfnl, nfnl);
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return 0;
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}
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static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
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{
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struct net *net;
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list_for_each_entry(net, net_exit_list, exit_list)
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rcu_assign_pointer(net->nfnl, NULL);
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synchronize_net();
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list_for_each_entry(net, net_exit_list, exit_list)
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netlink_kernel_release(net->nfnl_stash);
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}
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static struct pernet_operations nfnetlink_net_ops = {
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.init = nfnetlink_net_init,
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.exit_batch = nfnetlink_net_exit_batch,
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};
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static int __init nfnetlink_init(void)
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{
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pr_info("Netfilter messages via NETLINK v%s.\n", nfversion);
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return register_pernet_subsys(&nfnetlink_net_ops);
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}
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static void __exit nfnetlink_exit(void)
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{
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pr_info("Removing netfilter NETLINK layer.\n");
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unregister_pernet_subsys(&nfnetlink_net_ops);
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}
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module_init(nfnetlink_init);
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module_exit(nfnetlink_exit);
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