From d0ebf133590abdc035af6e19a6568667af0ab3b0 Mon Sep 17 00:00:00 2001 From: Daniel Hokka Zakrisson Date: Thu, 20 Mar 2008 15:07:10 -0700 Subject: [PATCH] [NETFILTER]: ipt_recent: sanity check hit count 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. Reported-by: Sean Kennedy Signed-off-by: Daniel Hokka Zakrisson Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- 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 68cbe3ca01..8e8f0425a8 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; -- 2.39.5