tcp md5sig: Use skb's saddr when replying to an incoming segment
[ 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@apple.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index d577ec0..b396073 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -828,7 +828,7 @@
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);