From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Paasch Subject: [PATCH net] tcp md5sig: Use skb's saddr when replying to an incoming segment Date: Mon, 11 Dec 2017 00:05:46 -0800 Message-ID: <20171211080546.89418-1-cpaasch@apple.com> Content-Transfer-Encoding: 7BIT Cc: netdev@vger.kernel.org To: David Miller Return-path: Received: from mail-out4.apple.com ([17.151.62.26]:48986 "EHLO mail-in4.apple.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750836AbdLKIVG (ORCPT ); Mon, 11 Dec 2017 03:21:06 -0500 Sender: netdev-owner@vger.kernel.org List-ID: 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 --- net/ipv4/tcp_ipv4.c | 2 +- net/ipv6/tcp_ipv6.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 77ea45da0fe9..94e28350f420 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -848,7 +848,7 @@ static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb, tcp_time_stamp_raw() + tcp_rsk(req)->ts_off, 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); diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 1f04ec0e4a7a..7178476b3d2f 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -994,7 +994,7 @@ static void tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb, req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale, tcp_time_stamp_raw() + tcp_rsk(req)->ts_off, 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); } -- 2.15.0