From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrey Vagin Subject: [PATCH] tcp: don't apply tsoffset if rcv_tsecr is zero Date: Tue, 27 Aug 2013 12:21:55 +0400 Message-ID: <1377591715-1742-1-git-send-email-avagin@openvz.org> Cc: Cyrill Gorcunov , linux-kernel@vger.kernel.org, Andrew Vagin , Pavel Emelyanov , Eric Dumazet , "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy To: netdev@vger.kernel.org Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Andrew Vagin The zero value means that tsecr is not valid, so it's a special case. tsoffset is used to customize tcp_time_stamp for one socket. tsoffset is usually zero, it's used when a socket was moved from one host to another host. Currently this issue affects logic of tcp_rcv_rtt_measure_ts. Due to incorrect value of rcv_tsecr, tcp_rcv_rtt_measure_ts sets rto to TCP_RTO_MAX. Cc: Pavel Emelyanov Cc: Eric Dumazet Cc: "David S. Miller" Cc: Alexey Kuznetsov Cc: James Morris Cc: Hideaki YOSHIFUJI Cc: Patrick McHardy Reported-by: Cyrill Gorcunov Signed-off-by: Andrey Vagin --- net/ipv4/tcp_input.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 28af45a..3ca2139 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3535,7 +3535,10 @@ static bool tcp_parse_aligned_timestamp(struct tcp_sock *tp, const struct tcphdr ++ptr; tp->rx_opt.rcv_tsval = ntohl(*ptr); ++ptr; - tp->rx_opt.rcv_tsecr = ntohl(*ptr) - tp->tsoffset; + if (*ptr) + tp->rx_opt.rcv_tsecr = ntohl(*ptr) - tp->tsoffset; + else + tp->rx_opt.rcv_tsecr = 0; return true; } return false; @@ -3560,7 +3563,7 @@ static bool tcp_fast_parse_options(const struct sk_buff *skb, } tcp_parse_options(skb, &tp->rx_opt, 1, NULL); - if (tp->rx_opt.saw_tstamp) + if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr) tp->rx_opt.rcv_tsecr -= tp->tsoffset; return true; @@ -5316,7 +5319,7 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, int saved_clamp = tp->rx_opt.mss_clamp; tcp_parse_options(skb, &tp->rx_opt, 0, &foc); - if (tp->rx_opt.saw_tstamp) + if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr) tp->rx_opt.rcv_tsecr -= tp->tsoffset; if (th->ack) { -- 1.8.3.1