This is a note to let you know that I've just added the patch titled
tcp: properly scale window in tcp_v[46]_reqsk_send_ack()
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tcp-properly-scale-window-in-tcp_v_reqsk_send_ack.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Wed Sep 21 12:45:10 CEST 2016
From: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Mon, 22 Aug 2016 11:31:10 -0700
Subject: tcp: properly scale window in tcp_v[46]_reqsk_send_ack()
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 20a2b49fc538540819a0c552877086548cff8d8d ]
When sending an ack in SYN_RECV state, we must scale the offered
window if wscale option was negotiated and accepted.
Tested:
Following packetdrill test demonstrates the issue :
0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+0 bind(3, ..., ...) = 0
+0 listen(3, 1) = 0
// Establish a connection.
+0 < S 0:0(0) win 20000 <mss 1000,sackOK,wscale 7, nop, TS val 100 ecr 0>
+0 > S. 0:0(0) ack 1 win 28960 <mss 1460,sackOK, TS val 100 ecr 100, nop, wscale 7>
+0 < . 1:11(10) ack 1 win 156 <nop,nop,TS val 99 ecr 100>
// check that window is properly scaled !
+0 > . 1:1(0) ack 1 win 226 <nop,nop,TS val 200 ecr 100>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Yuchung Cheng <ycheng@xxxxxxxxxx>
Cc: Neal Cardwell <ncardwell@xxxxxxxxxx>
Acked-by: Yuchung Cheng <ycheng@xxxxxxxxxx>
Acked-by: Neal Cardwell <ncardwell@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Tested-by: Holger Hoffstätte <holger@xxxxxxxxxxxxxxxxxxxxxx>
---
net/ipv4/tcp_ipv4.c | 8 +++++++-
net/ipv6/tcp_ipv6.c | 8 +++++++-
2 files changed, 14 insertions(+), 2 deletions(-)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -808,8 +808,14 @@ static void tcp_v4_reqsk_send_ack(const
u32 seq = (sk->sk_state == TCP_LISTEN) ? tcp_rsk(req)->snt_isn + 1 :
tcp_sk(sk)->snd_nxt;
+ /* RFC 7323 2.3
+ * The window field (SEG.WND) of every outgoing segment, with the
+ * exception of <SYN> segments, MUST be right-shifted by
+ * Rcv.Wind.Shift bits:
+ */
tcp_v4_send_ack(sock_net(sk), skb, seq,
- tcp_rsk(req)->rcv_nxt, req->rsk_rcv_wnd,
+ tcp_rsk(req)->rcv_nxt,
+ req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale,
tcp_time_stamp,
req->ts_recent,
0,
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -932,9 +932,15 @@ static void tcp_v6_reqsk_send_ack(const
/* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
* sk->sk_state == TCP_SYN_RECV -> for Fast Open.
*/
+ /* RFC 7323 2.3
+ * The window field (SEG.WND) of every outgoing segment, with the
+ * exception of <SYN> segments, MUST be right-shifted by
+ * Rcv.Wind.Shift bits:
+ */
tcp_v6_send_ack(sk, skb, (sk->sk_state == TCP_LISTEN) ?
tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
- tcp_rsk(req)->rcv_nxt, req->rsk_rcv_wnd,
+ tcp_rsk(req)->rcv_nxt,
+ req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale,
tcp_time_stamp, req->ts_recent, sk->sk_bound_dev_if,
tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->daddr),
0, 0);
Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are
queue-4.4/tcp-properly-scale-window-in-tcp_v_reqsk_send_ack.patch
queue-4.4/tcp-fix-use-after-free-in-tcp_xmit_retransmit_queue.patch
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