[PATCH 06/86] tcp: tcp_replace_ts_recent() should not be called fromtcp_validate_incoming()
From: Steven Rostedt
Date: Tue Mar 26 2013 - 14:05:40 EST
3.6.11.1 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit bd090dfc634ddd711a5fbd0cadc6e0ab4977bcaf ]
We added support for RFC 5961 in latest kernels but TCP fails
to perform exhaustive check of ACK sequence.
We can update our view of peer tsval from a frame that is
later discarded by tcp_ack()
This makes timestamps enabled sessions vulnerable to injection of
a high tsval : peers start an ACK storm, since the victim
sends a dupack each time it receives an ACK from the other peer.
As tcp_validate_incoming() is called before tcp_ack(), we should
not peform tcp_replace_ts_recent() from it, and let callers do it
at the right time.
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Neal Cardwell <ncardwell@xxxxxxxxxx>
Cc: Yuchung Cheng <ycheng@xxxxxxxxxx>
Cc: Nandita Dukkipati <nanditad@xxxxxxxxxx>
Cc: H.K. Jerry Chu <hkchu@xxxxxxxxxx>
Cc: Romain Francoise <romain@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
---
net/ipv4/tcp_input.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index c92c4da..7ccf80f 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5340,11 +5340,6 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
goto discard;
}
- /* ts_recent update must be made after we are sure that the packet
- * is in window.
- */
- tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq);
-
/* step 3: check security and precedence [ignored] */
/* step 4: Check for a SYN
@@ -5579,6 +5574,11 @@ step5:
if (th->ack && tcp_ack(sk, skb, FLAG_SLOWPATH) < 0)
goto discard;
+ /* ts_recent update must be made after we are sure that the packet
+ * is in window.
+ */
+ tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq);
+
tcp_rcv_rtt_measure_ts(sk, skb);
/* Process urgent data. */
@@ -6106,6 +6106,11 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
} else
goto discard;
+ /* ts_recent update must be made after we are sure that the packet
+ * is in window.
+ */
+ tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq);
+
/* step 6: check the URG bit */
tcp_urg(sk, skb, th);
--
1.7.10.4
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