If a rule using ipt_recent is created with a hit count greater than
ip_pkt_list_tot, the rule will never match as it cannot keep track
of enough timestamps. This patch makes ipt_recent refuse to create such
rules.
With ip_pkt_list_tot's default value of 20, the following can be used
to reproduce the problem.
nc -u -l 0.0.0.0 1234 &
for i in `seq 1 100`; do echo $i | nc -w 1 -u 127.0.0.1 1234; done
This limits it to 20 packets:
iptables -A OUTPUT -p udp --dport 1234 -m recent --set --name test \
--rsource
iptables -A OUTPUT -p udp --dport 1234 -m recent --update --seconds \
60 --hitcount 20 --name test --rsource -j DROP
While this is unlimited:
iptables -A OUTPUT -p udp --dport 1234 -m recent --set --name test \
--rsource
iptables -A OUTPUT -p udp --dport 1234 -m recent --update --seconds \
60 --hitcount 21 --name test --rsource -j DROP
With the patch the second rule-set will throw an EINVAL.
Signed-off-by: Daniel Hokka Zakrisson <daniel@xxxxxxxxx>
Reported-by: Sean Kennedy <skennedy@xxxxxxx>
---
net/ipv4/netfilter/ipt_recent.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/ipv4/netfilter/ipt_recent.c
b/net/ipv4/netfilter/ipt_recent.c
index 68cbe3c..8e8f042 100644
--- a/net/ipv4/netfilter/ipt_recent.c
+++ b/net/ipv4/netfilter/ipt_recent.c
@@ -252,6 +252,8 @@ recent_mt_check(const char *tablename, const void *ip,
if ((info->check_set & (IPT_RECENT_SET | IPT_RECENT_REMOVE)) &&
(info->seconds || info->hit_count))
return false;
+ if (info->hit_count > ip_pkt_list_tot)
+ return false;
if (info->name[0] == '\0' ||
strnlen(info->name, IPT_RECENT_NAME_LEN) == IPT_RECENT_NAME_LEN)
return false;
--
1.5.3.3
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