// SPDX-License-Identifier: GPL-2.0-only
/* Event cache for netfilter. */
/*
* (C) 2005 Harald Welte <[email protected]>
* (C) 2005 Patrick McHardy <[email protected]>
* (C) 2005-2006 Netfilter Core Team <[email protected]>
* (C) 2005 USAGI/WIDE Project <http://www.linux-ipv6.org>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/types.h>
#include <linux/netfilter.h>
#include <linux/skbuff.h>
#include <linux/vmalloc.h>
#include <linux/stddef.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_extend.h>
static DEFINE_MUTEX(nf_ct_ecache_mutex);
#define DYING_NULLS_VAL ((1 << 30) + 1)
#define ECACHE_MAX_JIFFIES msecs_to_jiffies(10)
#define ECACHE_RETRY_JIFFIES msecs_to_jiffies(10)
enum retry_state {
STATE_CONGESTED,
STATE_RESTART,
STATE_DONE,
};
struct nf_conntrack_net_ecache *nf_conn_pernet_ecache(const struct net *net)
{
struct nf_conntrack_net *cnet = nf_ct_pernet(net);
return &cnet->ecache;
}
#if IS_MODULE(CONFIG_NF_CT_NETLINK)
EXPORT_SYMBOL_GPL(nf_conn_pernet_ecache);
#endif
static enum retry_state ecache_work_evict_list(struct nf_conntrack_net *cnet)
{
unsigned long stop = jiffies + ECACHE_MAX_JIFFIES;
struct hlist_nulls_head evicted_list;
enum retry_state ret = STATE_DONE;
struct nf_conntrack_tuple_hash *h;
struct hlist_nulls_node *n;
unsigned int sent;
INIT_HLIST_NULLS_HEAD(&evicted_list, DYING_NULLS_VAL);
next:
sent = 0;
spin_lock_bh(&cnet->ecache.dying_lock);
hlist_nulls_for_each_entry_safe(h, n, &cnet->ecache.dying_list, hnnode) {
struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
/* The worker owns all entries, ct remains valid until nf_ct_put
* in the loop below.
*/
if (nf_conntrack_event(IPCT_DESTROY, ct)) {
ret = STATE_CONGESTED;
break;
}
hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode);
hlist_nulls_add_head(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode, &evicted_list);
if (time_after(stop, jiffies)) {
ret = STATE_RESTART;
break;
}
if (sent++ > 16) {
spin_unlock_bh(&cnet->ecache.dying_lock);
cond_resched();
goto next;
}
}
spin_unlock_bh(&cnet->ecache.dying_lock);
hlist_nulls_for_each_entry_safe(h, n, &evicted_list, hnnode) {
struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode);
nf_ct_put(ct);
cond_resched();
}
return ret;
}
static void ecache_work(struct work_struct *work)
{
struct nf_conntrack_net *cnet = container_of(work, struct nf_conntrack_net, ecache.dwork.work);
int ret, delay = -1;
ret = ecache_work_evict_list(cnet);
switch (ret) {
case STATE_CONGESTED:
delay = ECACHE_RETRY_JIFFIES;
break;
case STATE_RESTART:
delay = 0;
break;
case STATE_DONE:
break;
}
if (delay >= 0)
schedule_delayed_work(&cnet->ecache.dwork, delay);
}
static int __nf_conntrack_eventmask_report(struct nf_conntrack_ecache *e,
const u32 events,
const u32 missed,
const struct nf_ct_event *item)
{
struct net *net = nf_ct_net(item->ct);
struct nf_ct_event_notifier *notify;
u32 old, want;
int ret;
if (!((events | missed) & e->ctmask))
return 0;
rcu_read_lock();
notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
if (!notify) {
rcu_read_unlock();
return 0;
}
ret = notify->ct_event(events | missed, item);
rcu_read_unlock();
if (likely(ret >= 0 && missed == 0))
return 0;
do {
old = READ_ONCE(e->missed);
if (ret < 0)
want = old | events;
else
want = old & ~missed;
} while (cmpxchg(&e->missed, old, want) != old);
return ret;
}
int nf_conntrack_eventmask_report(unsigned int events, struct nf_conn *ct,
u32 portid, int report)
{
struct nf_conntrack_ecache *e;
struct nf_ct_event item;
unsigned int missed;
int ret;
if (!nf_ct_is_confirmed(ct))
return 0;
e = nf_ct_ecache_find(ct);
if (!e)
return 0;
memset(&item, 0, sizeof(item));
item.ct = ct;
item.portid = e->portid ? e->portid : portid;
item.report = report;
/* This is a resent of a destroy event? If so, skip missed */
missed = e->portid ? 0 : e->missed;
ret = __nf_conntrack_eventmask_report(e, events, missed, &item);
if (unlikely(ret < 0 && (events & (1 << IPCT_DESTROY)))) {
/* This is a destroy event that has been triggered by a process,
* we store the PORTID to include it in the retransmission.
*/
if (e->portid == 0 && portid != 0)
e->portid = portid;
}
return ret;
}
EXPORT_SYMBOL_GPL(nf_conntrack_eventmask_report);
/* deliver cached events and clear cache entry - must be called with locally
* disabled softirqs */
void nf_ct_deliver_cached_events(struct nf_conn *ct)
{
struct nf_conntrack_ecache *e;
struct nf_ct_event item;
unsigned int events;
if (!nf_ct_is_confirmed(ct) || nf_ct_is_dying(ct))
return;
e = nf_ct_ecache_find(ct);
if (e == NULL)
return;
events = xchg(&e->cache, 0);
item.ct = ct;
item.portid = 0;
item.report = 0;
/* We make a copy of the missed event cache without taking
* the lock, thus we may send missed events twice. However,
* this does not harm and it happens very rarely.
*/
__nf_conntrack_eventmask_report(e, events, e->missed, &item);
}
EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
void nf_ct_expect_event_report(enum ip_conntrack_expect_events event,
struct nf_conntrack_expect *exp,
u32 portid, int report)
{
struct net *net = nf_ct_exp_net(exp);
struct nf_ct_event_notifier *notify;
struct nf_conntrack_ecache *e;
rcu_read_lock();
notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
if (!notify)
goto out_unlock;
e = nf_ct_ecache_find(exp->master);
if (!e)
goto out_unlock;
if (e->expmask & (1 << event)) {
struct nf_exp_event item = {
.exp = exp,
.portid = portid,
.report = report
};
notify->exp_event(1 << event, &item);
}
out_unlock:
rcu_read_unlock();
}
void nf_conntrack_register_notifier(struct net *net,
const struct nf_ct_event_notifier *new)
{
struct nf_ct_event_notifier *notify;
mutex_lock(&nf_ct_ecache_mutex);
notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
lockdep_is_held(&nf_ct_ecache_mutex));
WARN_ON_ONCE(notify);
rcu_assign_pointer(net->ct.nf_conntrack_event_cb, new);
mutex_unlock(&nf_ct_ecache_mutex);
}
EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
void nf_conntrack_unregister_notifier(struct net *net)
{
mutex_lock(&nf_ct_ecache_mutex);
RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL);
mutex_unlock(&nf_ct_ecache_mutex);
/* synchronize_rcu() is called after netns pre_exit */
}
EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
void nf_conntrack_ecache_work(struct net *net, enum nf_ct_ecache_state state)
{
struct nf_conntrack_net *cnet = nf_ct_pernet(net);
if (state == NFCT_ECACHE_DESTROY_FAIL &&
!delayed_work_pending(&cnet->ecache.dwork)) {
schedule_delayed_work(&cnet->ecache.dwork, HZ);
net->ct.ecache_dwork_pending = true;
} else if (state == NFCT_ECACHE_DESTROY_SENT) {
if (!hlist_nulls_empty(&cnet->ecache.dying_list))
mod_delayed_work(system_wq, &cnet->ecache.dwork, 0);
else
net->ct.ecache_dwork_pending = false;
}
}
bool nf_ct_ecache_ext_add(struct nf_conn *ct, u16 ctmask, u16 expmask, gfp_t gfp)
{
struct net *net = nf_ct_net(ct);
struct nf_conntrack_ecache *e;
switch (net->ct.sysctl_events) {
case 0:
/* assignment via template / ruleset? ignore sysctl. */
if (ctmask || expmask)
break;
return true;
case 2: /* autodetect: no event listener, don't allocate extension. */
if (!READ_ONCE(nf_ctnetlink_has_listener))
return true;
fallthrough;
case 1:
/* always allocate an extension. */
if (!ctmask && !expmask) {
ctmask = ~0;
expmask = ~0;
}
break;
default:
WARN_ON_ONCE(1);
return true;
}
e = nf_ct_ext_add(ct, NF_CT_EXT_ECACHE, gfp);
if (e) {
e->ctmask = ctmask;
e->expmask = expmask;
}
return e != NULL;
}
EXPORT_SYMBOL_GPL(nf_ct_ecache_ext_add);
#define NF_CT_EVENTS_DEFAULT 2
static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
void nf_conntrack_ecache_pernet_init(struct net *net)
{
struct nf_conntrack_net *cnet = nf_ct_pernet(net);
net->ct.sysctl_events = nf_ct_events;
INIT_DELAYED_WORK(&cnet->ecache.dwork, ecache_work);
INIT_HLIST_NULLS_HEAD(&cnet->ecache.dying_list, DYING_NULLS_VAL);
spin_lock_init(&cnet->ecache.dying_lock);
BUILD_BUG_ON(__IPCT_MAX >= 16); /* e->ctmask is u16 */
}
void nf_conntrack_ecache_pernet_fini(struct net *net)
{
struct nf_conntrack_net *cnet = nf_ct_pernet(net);
cancel_delayed_work_sync(&cnet->ecache.dwork);
}
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