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authorEric Dumazet <eric.dumazet@gmail.com>2010-12-16 14:08:34 -0800
committerDavid S. Miller <davem@davemloft.net>2010-12-16 14:08:34 -0800
commitbc2ce894e113ed95b92541134b002fdc641e8080 (patch)
tree7c427099d5a1ab9cd387861e79470fc200153ff8
parent443457242beb6716b43db4d62fe148eab5515505 (diff)
tcp: relax tcp_paws_check()
Some windows versions have wrong RFC1323 implementations, with SYN and SYNACKS messages containing zero tcp timestamps. We relaxed in commit fc1ad92dfc4e363 the passive connection case (Windows connects to a linux machine), but the reverse case (linux connects to a Windows machine) has an analogue problem when tsvals from windows machine are 'negative' (high order bit set) : PAWS triggers and we drops incoming messages. Fix this by making zero ts_recent value special, allowing frame to be processed. Based on a report and initial patch from Dmitiy Balakin Bugzilla reference : https://bugzilla.kernel.org/show_bug.cgi?id=24842 Reported-by: dmitriy.balakin@nicneiron.ru Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/tcp.h8
1 files changed, 7 insertions, 1 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 3f227baee4be..2ab6c9c1c53a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1038,7 +1038,13 @@ static inline int tcp_paws_check(const struct tcp_options_received *rx_opt,
return 1;
if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
return 1;
-
+ /*
+ * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
+ * then following tcp messages have valid values. Ignore 0 value,
+ * or else 'negative' tsval might forbid us to accept their packets.
+ */
+ if (!rx_opt->ts_recent)
+ return 1;
return 0;
}