diff options
| author | Eric Dumazet <edumazet@google.com> | 2012-11-13 05:37:18 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-11-13 14:35:17 -0500 |
| commit | bd090dfc634ddd711a5fbd0cadc6e0ab4977bcaf (patch) | |
| tree | 0bea170c7ad25ecef637002cf2ebadc83086fea8 /net/ipv4/tcp_input.c | |
| parent | bbc8d9228ea8e37ce29fa96150d10b85a2c7be60 (diff) | |
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/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 15 |
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); |