This is a note to let you know that I've just added the patch titled
tcp md5sig: Use skb's saddr when replying to an incoming segment
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-md5sig-use-skb-s-saddr-when-replying-to-an-incoming-segment.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 Sun Dec 31 11:20:35 CET 2017
From: Christoph Paasch <cpaasch@xxxxxxxxx>
Date: Mon, 11 Dec 2017 00:05:46 -0800
Subject: tcp md5sig: Use skb's saddr when replying to an incoming segment
From: Christoph Paasch <cpaasch@xxxxxxxxx>
[ Upstream commit 30791ac41927ebd3e75486f9504b6d2280463bf0 ]
The MD5-key that belongs to a connection is identified by the peer's
IP-address. When we are in tcp_v4(6)_reqsk_send_ack(), we are replying
to an incoming segment from tcp_check_req() that failed the seq-number
checks.
Thus, to find the correct key, we need to use the skb's saddr and not
the daddr.
This bug seems to have been there since quite a while, but probably got
unnoticed because the consequences are not catastrophic. We will call
tcp_v4_reqsk_send_ack only to send a challenge-ACK back to the peer,
thus the connection doesn't really fail.
Fixes: 9501f9722922 ("tcp md5sig: Let the caller pass appropriate key for tcp_v{4,6}_do_calc_md5_hash().")
Signed-off-by: Christoph Paasch <cpaasch@xxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/tcp_ipv4.c | 2 +-
net/ipv6/tcp_ipv6.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -823,7 +823,7 @@ static void tcp_v4_reqsk_send_ack(const
tcp_time_stamp,
req->ts_recent,
0,
- tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&ip_hdr(skb)->daddr,
+ tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&ip_hdr(skb)->saddr,
AF_INET),
inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0,
ip_hdr(skb)->tos);
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -949,7 +949,7 @@ static void tcp_v6_reqsk_send_ack(const
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),
+ tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->saddr),
0, 0);
}
Patches currently in stable-queue which might be from cpaasch@xxxxxxxxx are
queue-4.4/tcp-md5sig-use-skb-s-saddr-when-replying-to-an-incoming-segment.patch