1 files changed, 358 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_ecache.c b/net/netfilter/nf_conntrack_ecache.c
new file mode 100644
index 000000000..69948e1d6
--- /dev/null
+++ b/net/netfilter/nf_conntrack_ecache.c
@@ -0,0 +1,358 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Event cache for netfilter. */
+
+/*
+ * (C) 2005 Harald Welte <laforge@gnumonks.org>
+ * (C) 2005 Patrick McHardy <kaber@trash.net>
+ * (C) 2005-2006 Netfilter Core Team <coreteam@netfilter.org>
+ * (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);
+}