ed86308f61
The CONFIG_PROVE_RCU option discovered a few invalid uses of rcu_dereference() in netfilter. In all these cases, the code code intends to check whether a pointer is already assigned when performing registration or whether the assigned pointer matches when performing unregistration. The entire registration/ unregistration is protected by a mutex, so we don't need the rcu_dereference() calls. Reported-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Signed-off-by: Patrick McHardy <kaber@trash.net>
249 lines
6.0 KiB
C
249 lines
6.0 KiB
C
/* Event cache for netfilter. */
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
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* (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
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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.
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*/
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#include <linux/types.h>
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#include <linux/netfilter.h>
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#include <linux/skbuff.h>
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#include <linux/vmalloc.h>
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#include <linux/stddef.h>
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#include <linux/err.h>
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#include <linux/percpu.h>
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#include <linux/kernel.h>
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#include <linux/netdevice.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_extend.h>
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static DEFINE_MUTEX(nf_ct_ecache_mutex);
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struct nf_ct_event_notifier *nf_conntrack_event_cb __read_mostly;
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EXPORT_SYMBOL_GPL(nf_conntrack_event_cb);
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struct nf_exp_event_notifier *nf_expect_event_cb __read_mostly;
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EXPORT_SYMBOL_GPL(nf_expect_event_cb);
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/* deliver cached events and clear cache entry - must be called with locally
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* disabled softirqs */
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void nf_ct_deliver_cached_events(struct nf_conn *ct)
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{
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unsigned long events;
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struct nf_ct_event_notifier *notify;
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struct nf_conntrack_ecache *e;
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rcu_read_lock();
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notify = rcu_dereference(nf_conntrack_event_cb);
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if (notify == NULL)
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goto out_unlock;
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e = nf_ct_ecache_find(ct);
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if (e == NULL)
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goto out_unlock;
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events = xchg(&e->cache, 0);
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if (nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct) && events) {
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struct nf_ct_event item = {
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.ct = ct,
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.pid = 0,
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.report = 0
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};
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int ret;
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/* We make a copy of the missed event cache without taking
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* the lock, thus we may send missed events twice. However,
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* this does not harm and it happens very rarely. */
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unsigned long missed = e->missed;
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ret = notify->fcn(events | missed, &item);
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if (unlikely(ret < 0 || missed)) {
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spin_lock_bh(&ct->lock);
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if (ret < 0)
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e->missed |= events;
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else
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e->missed &= ~missed;
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spin_unlock_bh(&ct->lock);
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}
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}
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out_unlock:
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rcu_read_unlock();
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}
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EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
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int nf_conntrack_register_notifier(struct nf_ct_event_notifier *new)
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{
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int ret = 0;
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mutex_lock(&nf_ct_ecache_mutex);
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if (nf_conntrack_event_cb != NULL) {
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ret = -EBUSY;
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goto out_unlock;
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}
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rcu_assign_pointer(nf_conntrack_event_cb, new);
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mutex_unlock(&nf_ct_ecache_mutex);
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return ret;
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out_unlock:
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mutex_unlock(&nf_ct_ecache_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
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void nf_conntrack_unregister_notifier(struct nf_ct_event_notifier *new)
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{
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mutex_lock(&nf_ct_ecache_mutex);
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BUG_ON(nf_conntrack_event_cb != new);
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rcu_assign_pointer(nf_conntrack_event_cb, NULL);
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mutex_unlock(&nf_ct_ecache_mutex);
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}
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EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
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int nf_ct_expect_register_notifier(struct nf_exp_event_notifier *new)
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{
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int ret = 0;
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mutex_lock(&nf_ct_ecache_mutex);
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if (nf_expect_event_cb != NULL) {
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ret = -EBUSY;
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goto out_unlock;
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}
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rcu_assign_pointer(nf_expect_event_cb, new);
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mutex_unlock(&nf_ct_ecache_mutex);
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return ret;
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out_unlock:
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mutex_unlock(&nf_ct_ecache_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
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void nf_ct_expect_unregister_notifier(struct nf_exp_event_notifier *new)
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{
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mutex_lock(&nf_ct_ecache_mutex);
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BUG_ON(nf_expect_event_cb != new);
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rcu_assign_pointer(nf_expect_event_cb, NULL);
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mutex_unlock(&nf_ct_ecache_mutex);
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}
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EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
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#define NF_CT_EVENTS_DEFAULT 1
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static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
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static int nf_ct_events_retry_timeout __read_mostly = 15*HZ;
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#ifdef CONFIG_SYSCTL
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static struct ctl_table event_sysctl_table[] = {
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{
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.procname = "nf_conntrack_events",
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.data = &init_net.ct.sysctl_events,
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = proc_dointvec,
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},
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{
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.procname = "nf_conntrack_events_retry_timeout",
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.data = &init_net.ct.sysctl_events_retry_timeout,
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = proc_dointvec_jiffies,
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},
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{}
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};
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#endif /* CONFIG_SYSCTL */
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static struct nf_ct_ext_type event_extend __read_mostly = {
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.len = sizeof(struct nf_conntrack_ecache),
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.align = __alignof__(struct nf_conntrack_ecache),
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.id = NF_CT_EXT_ECACHE,
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};
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#ifdef CONFIG_SYSCTL
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static int nf_conntrack_event_init_sysctl(struct net *net)
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{
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struct ctl_table *table;
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table = kmemdup(event_sysctl_table, sizeof(event_sysctl_table),
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GFP_KERNEL);
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if (!table)
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goto out;
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table[0].data = &net->ct.sysctl_events;
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table[1].data = &net->ct.sysctl_events_retry_timeout;
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net->ct.event_sysctl_header =
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register_net_sysctl_table(net,
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nf_net_netfilter_sysctl_path, table);
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if (!net->ct.event_sysctl_header) {
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printk(KERN_ERR "nf_ct_event: can't register to sysctl.\n");
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goto out_register;
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}
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return 0;
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out_register:
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kfree(table);
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out:
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return -ENOMEM;
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}
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static void nf_conntrack_event_fini_sysctl(struct net *net)
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{
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struct ctl_table *table;
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table = net->ct.event_sysctl_header->ctl_table_arg;
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unregister_net_sysctl_table(net->ct.event_sysctl_header);
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kfree(table);
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}
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#else
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static int nf_conntrack_event_init_sysctl(struct net *net)
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{
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return 0;
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}
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static void nf_conntrack_event_fini_sysctl(struct net *net)
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{
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}
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#endif /* CONFIG_SYSCTL */
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int nf_conntrack_ecache_init(struct net *net)
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{
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int ret;
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net->ct.sysctl_events = nf_ct_events;
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net->ct.sysctl_events_retry_timeout = nf_ct_events_retry_timeout;
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if (net_eq(net, &init_net)) {
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ret = nf_ct_extend_register(&event_extend);
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if (ret < 0) {
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printk(KERN_ERR "nf_ct_event: Unable to register "
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"event extension.\n");
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goto out_extend_register;
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}
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}
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ret = nf_conntrack_event_init_sysctl(net);
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if (ret < 0)
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goto out_sysctl;
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return 0;
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out_sysctl:
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if (net_eq(net, &init_net))
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nf_ct_extend_unregister(&event_extend);
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out_extend_register:
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return ret;
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}
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void nf_conntrack_ecache_fini(struct net *net)
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{
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nf_conntrack_event_fini_sysctl(net);
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if (net_eq(net, &init_net))
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nf_ct_extend_unregister(&event_extend);
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}
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