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: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netfilter/xt_recent.c b/net/netfilter/xt_recent.c
index 2ff8aae..b65eca9 100644
--- a/net/netfilter/xt_recent.c
+++ b/net/netfilter/xt_recent.c
@@ -143,6 +143,25 @@
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 @@
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 @@
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 "
