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authorEric Dumazet <edumazet@google.com>2012-11-13 05:37:18 +0000
committerDavid S. Miller <davem@davemloft.net>2012-11-13 14:35:17 -0500
commitbd090dfc634ddd711a5fbd0cadc6e0ab4977bcaf (patch)
tree0bea170c7ad25ecef637002cf2ebadc83086fea8 /net
parentbbc8d9228ea8e37ce29fa96150d10b85a2c7be60 (diff)
downloadvexpress-lsk-bd090dfc634ddd711a5fbd0cadc6e0ab4977bcaf.tar.gz
tcp: tcp_replace_ts_recent() should not be called from tcp_validate_incoming()
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@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Nandita Dukkipati <nanditad@google.com> Cc: H.K. Jerry Chu <hkchu@google.com> Cc: Romain Francoise <romain@orebokech.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp_input.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 2c2b13a999e..609ff98aeb4 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5313,11 +5313,6 @@ 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
@@ -5552,6 +5547,11 @@ 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. */
@@ -6130,6 +6130,11 @@ 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);