Messages in this thread Patch in this message | | | Date | Tue, 26 Mar 2013 13:21:05 -0400 | From | Steven Rostedt <> | Subject | [PATCH 06/86] tcp: tcp_replace_ts_recent() should not be called from tcp_validate_incoming() |
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3.6.11.1 stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet <edumazet@google.com>
[ 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@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> --- 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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