2013-08-27 08:25:20

by Andrei Vagin

Subject: [PATCH] tcp: don't apply tsoffset if rcv_tsecr is zero

From: Andrew Vagin <[email protected]>

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 <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Alexey Kuznetsov <[email protected]>
Cc: James Morris <[email protected]>
Cc: Hideaki YOSHIFUJI <[email protected]>
Cc: Patrick McHardy <[email protected]>
Reported-by: Cyrill Gorcunov <[email protected]>
Signed-off-by: Andrey Vagin <[email protected]>
---
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

2013-08-29 19:12:18

by David Miller

Subject: Re: [PATCH] tcp: don't apply tsoffset if rcv_tsecr is zero

From: Andrey Vagin <[email protected]>
Date: Tue, 27 Aug 2013 12:21:55 +0400

> From: Andrew Vagin <[email protected]>
>
> 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.
>
> Reported-by: Cyrill Gorcunov <[email protected]>
> Signed-off-by: Andrey Vagin <[email protected]>

Applied and queued up for -stable.