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.
v2: fix comment
Signed-off-by: Florian Westphal <f...@strlen.de>
---
include/net/netfilter/nf_conntrack.h | 5 +++++
net/netfilter/nf_conntrack_proto_udp.c | 16 +++++++++++++---
2 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/include/net/netfilter/nf_conntrack.h
b/include/net/netfilter/nf_conntrack.h
index 7e012312cd61..249d0a5b12b8 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -27,12 +27,17 @@
#include <net/netfilter/nf_conntrack_tuple.h>
+struct nf_ct_udp {
+ unsigned long stream_ts;
+};
+
/* per conntrack: protocol private data */
union nf_conntrack_proto {
/* insert conntrack proto private data here */
struct nf_ct_dccp dccp;
struct ip_ct_sctp sctp;
struct ip_ct_tcp tcp;
+ struct nf_ct_udp udp;
struct nf_ct_gre gre;
unsigned int tmpl_padto;
};
diff --git a/net/netfilter/nf_conntrack_proto_udp.c
b/net/netfilter/nf_conntrack_proto_udp.c
index ebf151054ad6..82da6b2625b1 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);
--
2.19.2
