Commit 35dfb013 authored by Andrew Sy Kim's avatar Andrew Sy Kim Committed by Pablo Neira Ayuso
Browse files

ipvs: queue delayed work to expire no destination connections if expire_nodest_conn=1 



When expire_nodest_conn=1 and a destination is deleted, IPVS does not
expire the existing connections until the next matching incoming packet.
If there are many connection entries from a single client to a single
destination, many packets may get dropped before all the connections are
expired (more likely with lots of UDP traffic). An optimization can be
made where upon deletion of a destination, IPVS queues up delayed work
to immediately expire any connections with a deleted destination. This
ensures any reused source ports from a client (within the IPVS timeouts)
are scheduled to new real servers instead of silently dropped.

Signed-off-by: default avatarAndrew Sy Kim <kim.andrewsy@gmail.com>
Signed-off-by: default avatarJulian Anastasov <ja@ssi.bg>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 336f531a

include/net/ip_vs.h

+29 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/spinlock.h>             /* for struct rwlock_t */

#include <linux/atomic.h>               /* for struct atomic_t */

#include <linux/refcount.h>             /* for struct refcount_t */

#include <linux/workqueue.h>



#include <linux/compiler.h>

#include <linux/timer.h>
@@ -886,6 +887,8 @@ struct netns_ipvs { 
	atomic_t		conn_out_counter;



#ifdef CONFIG_SYSCTL

	/* delayed work for expiring no dest connections */

	struct delayed_work	expire_nodest_conn_work;

	/* 1/rate drop and drop-entry variables */

	struct delayed_work	defense_work;   /* Work handler */

	int			drop_rate;
@@ -1051,6 +1054,11 @@ static inline int sysctl_conn_reuse_mode(struct netns_ipvs *ipvs) 
	return ipvs->sysctl_conn_reuse_mode;

}



static inline int sysctl_expire_nodest_conn(struct netns_ipvs *ipvs)

{

	return ipvs->sysctl_expire_nodest_conn;

}



static inline int sysctl_schedule_icmp(struct netns_ipvs *ipvs)

{

	return ipvs->sysctl_schedule_icmp;
@@ -1138,6 +1146,11 @@ static inline int sysctl_conn_reuse_mode(struct netns_ipvs *ipvs) 
	return 1;

}



static inline int sysctl_expire_nodest_conn(struct netns_ipvs *ipvs)

{

	return 0;

}



static inline int sysctl_schedule_icmp(struct netns_ipvs *ipvs)

{

	return 0;
@@ -1507,6 +1520,22 @@ static inline int ip_vs_todrop(struct netns_ipvs *ipvs) 
static inline int ip_vs_todrop(struct netns_ipvs *ipvs) { return 0; }

#endif



#ifdef CONFIG_SYSCTL

/* Enqueue delayed work for expiring no dest connections

 * Only run when sysctl_expire_nodest=1

 */

static inline void ip_vs_enqueue_expire_nodest_conns(struct netns_ipvs *ipvs)

{

	if (sysctl_expire_nodest_conn(ipvs))

		queue_delayed_work(system_long_wq,

				   &ipvs->expire_nodest_conn_work, 1);

}



void ip_vs_expire_nodest_conn_flush(struct netns_ipvs *ipvs);

#else

static inline void ip_vs_enqueue_expire_nodest_conns(struct netns_ipvs *ipvs) {}

#endif



#define IP_VS_DFWD_METHOD(dest) (atomic_read(&(dest)->conn_flags) & \

				 IP_VS_CONN_F_FWD_MASK)

net/netfilter/ipvs/ip_vs_conn.c

+39 −0
Original line number Diff line number Diff line
@@ -1389,6 +1389,45 @@ flush_again: 
		goto flush_again;

	}

}



#ifdef CONFIG_SYSCTL

void ip_vs_expire_nodest_conn_flush(struct netns_ipvs *ipvs)

{

	int idx;

	struct ip_vs_conn *cp, *cp_c;

	struct ip_vs_dest *dest;



	rcu_read_lock();

	for (idx = 0; idx < ip_vs_conn_tab_size; idx++) {

		hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[idx], c_list) {

			if (cp->ipvs != ipvs)

				continue;



			dest = cp->dest;

			if (!dest || (dest->flags & IP_VS_DEST_F_AVAILABLE))

				continue;



			if (atomic_read(&cp->n_control))

				continue;



			cp_c = cp->control;

			IP_VS_DBG(4, "del connection\n");

			ip_vs_conn_del(cp);

			if (cp_c && !atomic_read(&cp_c->n_control)) {

				IP_VS_DBG(4, "del controlling connection\n");

				ip_vs_conn_del(cp_c);

			}

		}

		cond_resched_rcu();



		/* netns clean up started, abort delayed work */

		if (!ipvs->enable)

			break;

	}

	rcu_read_unlock();

}

#endif



/*

 * per netns init and exit

 */

net/netfilter/ipvs/ip_vs_core.c

+20 −27
Original line number Diff line number Diff line
@@ -694,16 +694,10 @@ static int sysctl_nat_icmp_send(struct netns_ipvs *ipvs) 
	return ipvs->sysctl_nat_icmp_send;

}



static int sysctl_expire_nodest_conn(struct netns_ipvs *ipvs)

{

	return ipvs->sysctl_expire_nodest_conn;

}



#else



static int sysctl_snat_reroute(struct netns_ipvs *ipvs) { return 0; }

static int sysctl_nat_icmp_send(struct netns_ipvs *ipvs) { return 0; }

static int sysctl_expire_nodest_conn(struct netns_ipvs *ipvs) { return 0; }



#endif
@@ -2097,36 +2091,35 @@ ip_vs_in(struct netns_ipvs *ipvs, unsigned int hooknum, struct sk_buff *skb, int 
		}

	}



	if (unlikely(!cp)) {

		int v;



		if (!ip_vs_try_to_schedule(ipvs, af, skb, pd, &v, &cp, &iph))

			return v;

	}



	IP_VS_DBG_PKT(11, af, pp, skb, iph.off, "Incoming packet");



	/* Check the server status */

	if (cp->dest && !(cp->dest->flags & IP_VS_DEST_F_AVAILABLE)) {

	if (cp && cp->dest && !(cp->dest->flags & IP_VS_DEST_F_AVAILABLE)) {

		/* the destination server is not available */

		if (sysctl_expire_nodest_conn(ipvs)) {

			bool old_ct = ip_vs_conn_uses_old_conntrack(cp, skb);



		__u32 flags = cp->flags;



		/* when timer already started, silently drop the packet.*/

		if (timer_pending(&cp->timer))

			__ip_vs_conn_put(cp);

		else

			ip_vs_conn_put(cp);

			if (!old_ct)

				cp->flags &= ~IP_VS_CONN_F_NFCT;



		if (sysctl_expire_nodest_conn(ipvs) &&

		    !(flags & IP_VS_CONN_F_ONE_PACKET)) {

			/* try to expire the connection immediately */

			ip_vs_conn_expire_now(cp);

			__ip_vs_conn_put(cp);

			if (old_ct)

				return NF_DROP;

			cp = NULL;

		} else {

			__ip_vs_conn_put(cp);

			return NF_DROP;

		}

	}



		return NF_DROP;

	if (unlikely(!cp)) {

		int v;



		if (!ip_vs_try_to_schedule(ipvs, af, skb, pd, &v, &cp, &iph))

			return v;

	}



	IP_VS_DBG_PKT(11, af, pp, skb, iph.off, "Incoming packet");



	ip_vs_in_stats(cp, skb);

	ip_vs_set_state(cp, IP_VS_DIR_INPUT, skb, pd);

	if (cp->packet_xmit)

net/netfilter/ipvs/ip_vs_ctl.c

+22 −0
Original line number Diff line number Diff line
@@ -210,6 +210,17 @@ static void update_defense_level(struct netns_ipvs *ipvs) 
	local_bh_enable();

}



/* Handler for delayed work for expiring no

 * destination connections

 */

static void expire_nodest_conn_handler(struct work_struct *work)

{

	struct netns_ipvs *ipvs;



	ipvs = container_of(work, struct netns_ipvs,

			    expire_nodest_conn_work.work);

	ip_vs_expire_nodest_conn_flush(ipvs);

}



/*

 *	Timer for checking the defense
@@ -1164,6 +1175,12 @@ static void __ip_vs_del_dest(struct netns_ipvs *ipvs, struct ip_vs_dest *dest, 
	list_add(&dest->t_list, &ipvs->dest_trash);

	dest->idle_start = 0;

	spin_unlock_bh(&ipvs->dest_trash_lock);



	/* Queue up delayed work to expire all no destination connections.

	 * No-op when CONFIG_SYSCTL is disabled.

	 */

	if (!cleanup)

		ip_vs_enqueue_expire_nodest_conns(ipvs);

}
@@ -4086,6 +4103,10 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs) 
	queue_delayed_work(system_long_wq, &ipvs->defense_work,

			   DEFENSE_TIMER_PERIOD);



	/* Init delayed work for expiring no dest conn */

	INIT_DELAYED_WORK(&ipvs->expire_nodest_conn_work,

			  expire_nodest_conn_handler);



	return 0;

}
@@ -4093,6 +4114,7 @@ static void __net_exit ip_vs_control_net_cleanup_sysctl(struct netns_ipvs *ipvs) 
{

	struct net *net = ipvs->net;



	cancel_delayed_work_sync(&ipvs->expire_nodest_conn_work);

	cancel_delayed_work_sync(&ipvs->defense_work);

	cancel_work_sync(&ipvs->defense_work.work);

	unregister_net_sysctl_table(ipvs->sysctl_hdr);

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