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Commit 0079c5ae authored by Tim Gardner's avatar Tim Gardner Committed by Patrick McHardy
Browse files

netfilter: xt_recent: add an entry reaper 



One of the problems with the way xt_recent is implemented is that
there is no efficient way to remove expired entries. Of course,
one can write a rule '-m recent --remove', but you have to know
beforehand which entry to delete. This commit adds reaper
logic which checks the head of the LRU list when a rule
is invoked that has a '--seconds' value and XT_RECENT_REAP set. If an
entry ceases to accumulate time stamps, then it will eventually bubble
to the top of the LRU list where it is then reaped.

Signed-off-by: default avatarTim Gardner <tim.gardner@canonical.com>
Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
parent 5be4a4f5

include/linux/netfilter/xt_recent.h

+4 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ enum { 
	XT_RECENT_UPDATE   = 1 << 2,

	XT_RECENT_REMOVE   = 1 << 3,

	XT_RECENT_TTL      = 1 << 4,

	XT_RECENT_REAP     = 1 << 5,



	XT_RECENT_SOURCE   = 0,

	XT_RECENT_DEST     = 1,
@@ -16,6 +17,9 @@ enum { 
	XT_RECENT_NAME_LEN = 200,

};



/* Only allowed with --rcheck and --update */

#define XT_RECENT_MODIFIERS (XT_RECENT_TTL|XT_RECENT_REAP)



struct xt_recent_mtinfo {

	__u32 seconds;

	__u32 hit_count;

net/netfilter/xt_recent.c

+27 −1
Original line number Diff line number Diff line
@@ -143,6 +143,25 @@ static void recent_entry_remove(struct recent_table *t, struct recent_entry *e) 
	t->entries--;

}



/*

 * Drop entries with timestamps older then 'time'.

 */

static void recent_entry_reap(struct recent_table *t, unsigned long time)

{

	struct recent_entry *e;



	/*

	 * The head of the LRU list is always the oldest entry.

	 */

	e = list_entry(t->lru_list.next, struct recent_entry, lru_list);



	/*

	 * The last time stamp is the most recent.

	 */

	if (time_after(time, e->stamps[e->index-1]))

		recent_entry_remove(t, e);

}



static struct recent_entry *

recent_entry_init(struct recent_table *t, const union nf_inet_addr *addr,

		  u_int16_t family, u_int8_t ttl)
@@ -269,6 +288,10 @@ recent_mt(const struct sk_buff *skb, const struct xt_match_param *par) 
				break;

			}

		}



		/* info->seconds must be non-zero */

		if (info->check_set & XT_RECENT_REAP)

			recent_entry_reap(t, time);

	}



	if (info->check_set & XT_RECENT_SET ||
@@ -301,7 +324,10 @@ static bool recent_mt_check(const struct xt_mtchk_param *par) 
		      XT_RECENT_CHECK | XT_RECENT_UPDATE)) != 1)

		return false;

	if ((info->check_set & (XT_RECENT_SET | XT_RECENT_REMOVE)) &&

	    (info->seconds || info->hit_count))

	    (info->seconds || info->hit_count ||

	    (info->check_set & XT_RECENT_MODIFIERS)))

		return false;

	if ((info->check_set & XT_RECENT_REAP) && !info->seconds)

		return false;

	if (info->hit_count > ip_pkt_list_tot) {

		pr_info(KBUILD_MODNAME ": hitcount (%u) is larger than "