Messages in this thread Patch in this message | | | Date | Sat, 15 Mar 2008 14:49:53 +0100 (CET) | Subject | [PATCH] netfilter: ipt_recent: sanity check hit count | From | "Daniel Hokka Zakrisson" <> |
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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@hozac.com> Reported-by: Sean Kennedy <skennedy@vcn.com> --- 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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