Eric Dumazet wrote:
> Le dimanche 28 février 2010 à 16:12 -0700, Tim Gardner a écrit :
>
>> You are right about the reaper pointer. I'd forgotten that the LRU list
>> was already sorted oldest to newest. Doh! I've cleaned that up some.
>>
>> This version adds the '--reap' flag and only looks at the head of the
>> LRU list once per ip_reaper_freq packets.
>>
>> I also added a check that makes sure --rttl and --reap modify only the
>> --rcheck and --update options.
>>
>> rtg
>
> @@ -272,6 +295,16 @@ recent_mt(const struct sk_buff *skb, const struct
> xt_match_param *par)
> break;
> }
> }
> +
> + /*
> + * Run the reaper every ip_reaper_freq packets.
> + */
> + if ((info->check_set & XT_RECENT_REAP) &&
> + info->seconds &&
>
> This (info->seconds) test is redundant, if you test it _once_ in
> recent_mt_check()
>
> + (++t->reaper_cnt >= ip_reaper_freq)) {
> + t->reaper_cnt = 0;
> + recent_entry_reap(t, time);
> + }
> }
>
>
> ie :
>
> diff --git a/net/netfilter/xt_recent.c b/net/netfilter/xt_recent.c
> index fc70a49..66d68f3 100644
> --- a/net/netfilter/xt_recent.c
> +++ b/net/netfilter/xt_recent.c
> @@ -294,6 +294,8 @@ static bool recent_mt_check(const struct
> xt_mtchk_param *par)
> if ((info->check_set & (XT_RECENT_SET | XT_RECENT_REMOVE)) &&
> (info->seconds || info->hit_count))
> return false;
> + if ((info->check_set & XT_RECENT_REAP) && !info->seconds)
> + return false;
> if (info->hit_count > ip_pkt_list_tot)
> return false;
> if (info->name[0] == '\0' ||
>
>
>
> Then, now that reaping is done as a rule option only, I am not sure we
> still need the reaper_cnt logic, since you probably want ip_reaper_freq
> = 1, or else table size will probably grow at its limit, even in non DOS
> situation.
>
>
>
Agreed, see attached.
--
Tim Gardner timg@xxxxxxx www.tpi.com
OR 503-601-0234 x102 MT 406-443-5357
>From 3cd53e6474b307bba448103865bed63ffe81b626 Mon Sep 17 00:00:00 2001
From: Tim Gardner <tim.gardner@xxxxxxxxxxxxx>
Date: Sat, 27 Feb 2010 20:22:07 -0700
Subject: [PATCH] netfilter: xt_recent: Add an entry reaper (V4)
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@xxxxxxxxxxxxx>
---
include/linux/netfilter/xt_recent.h | 4 ++++
net/netfilter/xt_recent.c | 28 +++++++++++++++++++++++++++-
2 files changed, 31 insertions(+), 1 deletions(-)
diff --git a/include/linux/netfilter/xt_recent.h b/include/linux/netfilter/xt_recent.h
index d2c2766..bba990e 100644
--- a/include/linux/netfilter/xt_recent.h
+++ b/include/linux/netfilter/xt_recent.h
@@ -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;
diff --git a/net/netfilter/xt_recent.c b/net/netfilter/xt_recent.c
index 7073dbb..873a101 100644
--- a/net/netfilter/xt_recent.c
+++ b/net/netfilter/xt_recent.c
@@ -146,6 +146,25 @@ 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)
@@ -272,6 +291,10 @@ 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 ||
@@ -304,7 +327,10 @@ 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 "
--
1.7.0
