From d535c8a69c1924e70186d80be0a9cecaf475f166 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 6 Dec 2018 11:50:49 +0100 Subject: netfilter: conntrack: udp: only extend timeout to stream mode after 2s Currently DNS resolvers that send both A and AAAA queries from same source port can trigger stream mode prematurely, which results in non-early-evictable conntrack entry for three minutes, even though DNS requests are done in a few milliseconds. Add a two second grace period where we continue to use the ordinary 30-second default timeout. Its enough for DNS request/response traffic, even if two request/reply packets are involved. ASSURED is still set, else conntrack (and thus a possible NAT mapping ...) gets zapped too in case conntrack table runs full. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_proto_udp.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) (limited to 'net') diff --git a/net/netfilter/nf_conntrack_proto_udp.c b/net/netfilter/nf_conntrack_proto_udp.c index c879d8d78cfd..9f2e05adba69 100644 --- a/net/netfilter/nf_conntrack_proto_udp.c +++ b/net/netfilter/nf_conntrack_proto_udp.c @@ -100,11 +100,21 @@ static int udp_packet(struct nf_conn *ct, if (!timeouts) timeouts = udp_get_timeouts(nf_ct_net(ct)); + if (!nf_ct_is_confirmed(ct)) + ct->proto.udp.stream_ts = 2 * HZ + jiffies; + /* If we've seen traffic both ways, this is some kind of UDP - stream. Extend timeout. */ + * stream. Set Assured. + */ if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { - nf_ct_refresh_acct(ct, ctinfo, skb, - timeouts[UDP_CT_REPLIED]); + unsigned long extra = timeouts[UDP_CT_UNREPLIED]; + + /* Still active after two seconds? Extend timeout. */ + if (time_after(jiffies, ct->proto.udp.stream_ts)) + extra = timeouts[UDP_CT_REPLIED]; + + nf_ct_refresh_acct(ct, ctinfo, skb, extra); + /* Also, more likely to be important, and not a probe */ if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status)) nf_conntrack_event_cache(IPCT_ASSURED, ct); -- cgit v1.2.3-59-g8ed1b