// SPDX-License-Identifier: GPL-2.0-only
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/* Event cache for netfilter. */
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/*
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* (C) 2005 Harald Welte <laforge@gnumonks.org>
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* (C) 2005 Patrick McHardy <kaber@trash.net>
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* (C) 2005-2006 Netfilter Core Team <coreteam@netfilter.org>
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* (C) 2005 USAGI/WIDE Project <http://www.linux-ipv6.org>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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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 <linux/slab.h>
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#include <linux/export.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_ecache.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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#define ECACHE_RETRY_WAIT (HZ/10)
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#define ECACHE_STACK_ALLOC (256 / sizeof(void *))
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enum retry_state {
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STATE_CONGESTED,
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STATE_RESTART,
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STATE_DONE,
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};
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static enum retry_state ecache_work_evict_list(struct ct_pcpu *pcpu)
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{
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struct nf_conn *refs[ECACHE_STACK_ALLOC];
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enum retry_state ret = STATE_DONE;
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struct nf_conntrack_tuple_hash *h;
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struct hlist_nulls_node *n;
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unsigned int evicted = 0;
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spin_lock(&pcpu->lock);
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hlist_nulls_for_each_entry(h, n, &pcpu->dying, hnnode) {
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struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
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struct nf_conntrack_ecache *e;
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if (!nf_ct_is_confirmed(ct))
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continue;
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/* This ecache access is safe because the ct is on the
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* pcpu dying list and we hold the spinlock -- the entry
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* cannot be free'd until after the lock is released.
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*
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* This is true even if ct has a refcount of 0: the
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* cpu that is about to free the entry must remove it
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* from the dying list and needs the lock to do so.
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*/
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e = nf_ct_ecache_find(ct);
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if (!e || e->state != NFCT_ECACHE_DESTROY_FAIL)
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continue;
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/* ct is in NFCT_ECACHE_DESTROY_FAIL state, this means
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* the worker owns this entry: the ct will remain valid
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* until the worker puts its ct reference.
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*/
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if (nf_conntrack_event(IPCT_DESTROY, ct)) {
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ret = STATE_CONGESTED;
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break;
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}
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e->state = NFCT_ECACHE_DESTROY_SENT;
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refs[evicted] = ct;
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if (++evicted >= ARRAY_SIZE(refs)) {
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ret = STATE_RESTART;
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break;
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}
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}
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spin_unlock(&pcpu->lock);
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/* can't _put while holding lock */
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while (evicted)
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nf_ct_put(refs[--evicted]);
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return ret;
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}
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static void ecache_work(struct work_struct *work)
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{
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struct netns_ct *ctnet =
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container_of(work, struct netns_ct, ecache_dwork.work);
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int cpu, delay = -1;
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struct ct_pcpu *pcpu;
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local_bh_disable();
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for_each_possible_cpu(cpu) {
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enum retry_state ret;
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pcpu = per_cpu_ptr(ctnet->pcpu_lists, cpu);
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ret = ecache_work_evict_list(pcpu);
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switch (ret) {
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case STATE_CONGESTED:
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delay = ECACHE_RETRY_WAIT;
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goto out;
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case STATE_RESTART:
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delay = 0;
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break;
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case STATE_DONE:
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break;
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}
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}
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out:
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local_bh_enable();
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ctnet->ecache_dwork_pending = delay > 0;
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if (delay >= 0)
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schedule_delayed_work(&ctnet->ecache_dwork, delay);
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}
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int nf_conntrack_eventmask_report(unsigned int eventmask, struct nf_conn *ct,
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u32 portid, int report)
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{
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int ret = 0;
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struct net *net = nf_ct_net(ct);
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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(net->ct.nf_conntrack_event_cb);
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if (!notify)
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goto out_unlock;
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e = nf_ct_ecache_find(ct);
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if (!e)
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goto out_unlock;
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if (nf_ct_is_confirmed(ct)) {
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struct nf_ct_event item = {
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.ct = ct,
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.portid = e->portid ? e->portid : portid,
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.report = report
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};
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/* This is a resent of a destroy event? If so, skip missed */
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unsigned long missed = e->portid ? 0 : e->missed;
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if (!((eventmask | missed) & e->ctmask))
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goto out_unlock;
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ret = notify->fcn(eventmask | 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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/* This is a destroy event that has been
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* triggered by a process, we store the PORTID
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* to include it in the retransmission.
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*/
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if (eventmask & (1 << IPCT_DESTROY)) {
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if (e->portid == 0 && portid != 0)
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e->portid = portid;
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e->state = NFCT_ECACHE_DESTROY_FAIL;
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} else {
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e->missed |= eventmask;
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}
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} else {
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e->missed &= ~missed;
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}
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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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return ret;
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}
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EXPORT_SYMBOL_GPL(nf_conntrack_eventmask_report);
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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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struct net *net = nf_ct_net(ct);
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unsigned long events, missed;
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struct nf_ct_event_notifier *notify;
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struct nf_conntrack_ecache *e;
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struct nf_ct_event item;
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int ret;
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rcu_read_lock();
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notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
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if (notify == NULL)
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goto out_unlock;
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if (!nf_ct_is_confirmed(ct) || nf_ct_is_dying(ct))
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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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/* 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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missed = e->missed;
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if (!((events | missed) & e->ctmask))
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goto out_unlock;
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item.ct = ct;
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item.portid = 0;
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item.report = 0;
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ret = notify->fcn(events | missed, &item);
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if (likely(ret == 0 && !missed))
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goto out_unlock;
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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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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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void nf_ct_expect_event_report(enum ip_conntrack_expect_events event,
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struct nf_conntrack_expect *exp,
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u32 portid, int report)
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{
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struct net *net = nf_ct_exp_net(exp);
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struct nf_exp_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(net->ct.nf_expect_event_cb);
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if (!notify)
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goto out_unlock;
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e = nf_ct_ecache_find(exp->master);
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if (!e)
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goto out_unlock;
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if (e->expmask & (1 << event)) {
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struct nf_exp_event item = {
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.exp = exp,
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.portid = portid,
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.report = report
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};
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notify->fcn(1 << event, &item);
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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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int nf_conntrack_register_notifier(struct net *net,
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struct nf_ct_event_notifier *new)
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{
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int ret;
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struct nf_ct_event_notifier *notify;
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mutex_lock(&nf_ct_ecache_mutex);
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notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
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lockdep_is_held(&nf_ct_ecache_mutex));
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if (notify != 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(net->ct.nf_conntrack_event_cb, new);
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ret = 0;
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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 net *net,
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struct nf_ct_event_notifier *new)
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{
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struct nf_ct_event_notifier *notify;
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mutex_lock(&nf_ct_ecache_mutex);
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notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
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lockdep_is_held(&nf_ct_ecache_mutex));
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BUG_ON(notify != new);
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RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL);
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mutex_unlock(&nf_ct_ecache_mutex);
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/* synchronize_rcu() is called from ctnetlink_exit. */
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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 net *net,
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struct nf_exp_event_notifier *new)
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{
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int ret;
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struct nf_exp_event_notifier *notify;
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mutex_lock(&nf_ct_ecache_mutex);
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notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
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lockdep_is_held(&nf_ct_ecache_mutex));
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if (notify != 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(net->ct.nf_expect_event_cb, new);
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ret = 0;
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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 net *net,
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struct nf_exp_event_notifier *new)
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{
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struct nf_exp_event_notifier *notify;
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mutex_lock(&nf_ct_ecache_mutex);
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notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
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lockdep_is_held(&nf_ct_ecache_mutex));
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BUG_ON(notify != new);
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RCU_INIT_POINTER(net->ct.nf_expect_event_cb, NULL);
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mutex_unlock(&nf_ct_ecache_mutex);
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/* synchronize_rcu() is called from ctnetlink_exit. */
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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 const struct nf_ct_ext_type event_extend = {
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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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void nf_conntrack_ecache_pernet_init(struct net *net)
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{
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net->ct.sysctl_events = nf_ct_events;
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INIT_DELAYED_WORK(&net->ct.ecache_dwork, ecache_work);
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}
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void nf_conntrack_ecache_pernet_fini(struct net *net)
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{
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cancel_delayed_work_sync(&net->ct.ecache_dwork);
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}
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int nf_conntrack_ecache_init(void)
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{
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int ret = nf_ct_extend_register(&event_extend);
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if (ret < 0)
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pr_err("Unable to register event extension\n");
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BUILD_BUG_ON(__IPCT_MAX >= 16); /* ctmask, missed use u16 */
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return ret;
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}
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void nf_conntrack_ecache_fini(void)
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{
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nf_ct_extend_unregister(&event_extend);
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}
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