[NETFILTER]: TCP conntrack: improve dead connection detection

Don't count window updates as retransmissions.

Signed-off-by: George Hansper <georgeh@anstat.com.au>
Signed-off-by: Patrick McHardy <kaber@trash.net>

3 files changed, 7 insertions, 2 deletions

diff --git a/include/linux/netfilter/nf_conntrack_tcp.h b/include/linux/netfilter/nf_conntrack_tcp.h
index b2feeffde384..6b01ba297727 100644
--- a/include/linux/netfilter/nf_conntrack_tcp.h
+++ b/include/linux/netfilter/nf_conntrack_tcp.h
@@ -49,6 +49,7 @@ struct ip_ct_tcp
         u_int32_t       last_seq;       /* Last sequence number seen in dir */
         u_int32_t       last_ack;       /* Last sequence number seen in opposite dir */
         u_int32_t       last_end;       /* Last seq + len */
+        u_int16_t       last_win;       /* Last window advertisement seen in dir */
 };
 
 #endif /* __KERNEL__ */
diff --git a/net/ipv4/netfilter/ip_conntrack_proto_tcp.c b/net/ipv4/netfilter/ip_conntrack_proto_tcp.c
index 75a7237eb8c1..03ae9a04cb37 100644
--- a/net/ipv4/netfilter/ip_conntrack_proto_tcp.c
+++ b/net/ipv4/netfilter/ip_conntrack_proto_tcp.c
@@ -731,13 +731,15 @@ static int tcp_in_window(struct ip_ct_tcp *state,
                         if (state->last_dir == dir
                             && state->last_seq == seq
                             && state->last_ack == ack
-                            && state->last_end == end)
+                            && state->last_end == end
+                            && state->last_win == win)
                                 state->retrans++;
                         else {
                                 state->last_dir = dir;
                                 state->last_seq = seq;
                                 state->last_ack = ack;
                                 state->last_end = end;
+                                state->last_win = win;
                                 state->retrans = 0;
                         }
                 }
diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index 9fc0ee61f92a..238bbb5b72ef 100644
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -688,13 +688,15 @@ static int tcp_in_window(struct ip_ct_tcp *state,
                         if (state->last_dir == dir
                             && state->last_seq == seq
                             && state->last_ack == ack
-                            && state->last_end == end)
+                            && state->last_end == end
+                            && state->last_win == win)
                                 state->retrans++;
                         else {
                                 state->last_dir = dir;
                                 state->last_seq = seq;
                                 state->last_ack = ack;
                                 state->last_end = end;
+                                state->last_win = win;
                                 state->retrans = 0;
                         }
                 }