netdev - [PATCH v3] TCP: avoid to send keepalive probes if receiving data

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1272249659-2292-1-git-send-email-fleitner@redhat.com>
Date:	Sun, 25 Apr 2010 23:40:59 -0300
From:	Flavio Leitner <fleitner@...hat.com>
To:	netdev@...r.kernel.org
Cc:	David Miller <davem@...emloft.net>,
	Ilpo <ilpo.jarvinen@...sinki.fi>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Flavio Leitner <fleitner@...hat.com>
Subject: [PATCH v3] TCP: avoid to send keepalive probes if receiving data

RFC 1122 says the following:
...
  Keep-alive packets MUST only be sent when no data or
  acknowledgement packets have been received for the
  connection within an interval.
...

The acknowledgement packet is reseting the keepalive
timer but the data packet isn't. This patch fixes it by
checking the timestamp of the last received data packet
too when the keepalive timer expires.

Signed-off-by: Flavio Leitner <fleitner@...hat.com>
---
 net/ipv4/tcp.c       |    5 ++++-
 net/ipv4/tcp_timer.c |    8 ++++++++
 2 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 0f8caf6..94f605c 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2298,7 +2298,10 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
 			if (sock_flag(sk, SOCK_KEEPOPEN) &&
 			    !((1 << sk->sk_state) &
 			      (TCPF_CLOSE | TCPF_LISTEN))) {
-				__u32 elapsed = tcp_time_stamp - tp->rcv_tstamp;
+				u32 elapsed = min_t(u32,
+				      tcp_time_stamp - icsk->icsk_ack.lrcvtime,
+				      tcp_time_stamp - tp->rcv_tstamp);
+
 				if (tp->keepalive_time > elapsed)
 					elapsed = tp->keepalive_time - elapsed;
 				else
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 8a0ab29..9d1bb6f 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -554,6 +554,14 @@ static void tcp_keepalive_timer (unsigned long data)
 	if (tp->packets_out || tcp_send_head(sk))
 		goto resched;
 
+	elapsed = tcp_time_stamp - icsk->icsk_ack.lrcvtime;
+
+	/* receiving data means alive */
+	if (elapsed < keepalive_time_when(tp)) {
+		elapsed = keepalive_time_when(tp) - elapsed;
+		goto resched;
+	}
+
 	elapsed = tcp_time_stamp - tp->rcv_tstamp;
 
 	if (elapsed >= keepalive_time_when(tp)) {
-- 
1.5.5.6

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html