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authorPablo Neira Ayuso <pablo@netfilter.org>2010-07-15 17:09:04 +0200
committerPatrick McHardy <kaber@trash.net>2010-07-15 17:09:04 +0200
commitfac42a9a922fe5eb87cac0b597010afb81e7ffe9 (patch)
tree96763bdcfcc4e4b9cafbeeeb8c63c27bdbfc0ce4 /net/netfilter
parentcca5cf91c789f3301cc2541a79c323c53be5a8e1 (diff)
netfilter: nf_ct_tcp: fix flow recovery with TCP window tracking enabled
This patch adds the missing bits to support the recovery of TCP flows without disabling window tracking (aka be_liberal). To ensure a successful recovery, we have to inject the window scale factor via ctnetlink. This patch has been tested with a development snapshot of conntrackd and the new clause `TCPWindowTracking' that allows to perform strict TCP window tracking recovery across fail-overs. With this patch, we don't update the receiver's window until it's not initiated. We require this to perform a successful recovery. Jozsef confirmed in a private email that this spotted a real issue since that should not happen. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu> Signed-off-by: Patrick McHardy <kaber@trash.net>
Diffstat (limited to 'net/netfilter')
-rw-r--r--net/netfilter/nf_conntrack_proto_tcp.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index 802dbffae8b4..c4c885dca3bd 100644
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -585,8 +585,16 @@ static bool tcp_in_window(const struct nf_conn *ct,
* Let's try to use the data from the packet.
*/
sender->td_end = end;
+ win <<= sender->td_scale;
sender->td_maxwin = (win == 0 ? 1 : win);
sender->td_maxend = end + sender->td_maxwin;
+ /*
+ * We haven't seen traffic in the other direction yet
+ * but we have to tweak window tracking to pass III
+ * and IV until that happens.
+ */
+ if (receiver->td_maxwin == 0)
+ receiver->td_end = receiver->td_maxend = sack;
}
} else if (((state->state == TCP_CONNTRACK_SYN_SENT
&& dir == IP_CT_DIR_ORIGINAL)
@@ -680,7 +688,7 @@ static bool tcp_in_window(const struct nf_conn *ct,
/*
* Update receiver data.
*/
- if (after(end, sender->td_maxend))
+ if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
receiver->td_maxwin += end - sender->td_maxend;
if (after(sack + win, receiver->td_maxend - 1)) {
receiver->td_maxend = sack + win;