tcp: Fix MD5 signature checking on IPv4 mapped sockets

Fix MD5 signature checking so that an IPv4 active open
to an IPv6 socket can succeed.  In particular, use the
correct address family's signature generation function
for the SYN/ACK.

Reported-by:   Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: John Dykstra <john.dykstra1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 19f4150..88af843 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1425,6 +1425,11 @@
 #ifdef CONFIG_TCP_MD5SIG
 	struct tcp_md5sig_key	*(*md5_lookup) (struct sock *sk,
 						struct request_sock *req);
+	int			(*calc_md5_hash) (char *location,
+						  struct tcp_md5sig_key *md5,
+						  struct sock *sk,
+						  struct request_sock *req,
+						  struct sk_buff *skb);
 #endif
 };
 
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 5a1ca26..7c107eb 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1160,6 +1160,7 @@
 #ifdef CONFIG_TCP_MD5SIG
 static struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
 	.md5_lookup	=	tcp_v4_reqsk_md5_lookup,
+	.calc_md5_hash	=	tcp_v4_md5_hash_skb,
 };
 #endif
 
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 5bdf08d..bd62712 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2261,7 +2261,7 @@
 #ifdef CONFIG_TCP_MD5SIG
 	/* Okay, we have all we need - do the md5 hash if needed */
 	if (md5) {
-		tp->af_specific->calc_md5_hash(md5_hash_location,
+		tcp_rsk(req)->af_specific->calc_md5_hash(md5_hash_location,
 					       md5, NULL, req, skb);
 	}
 #endif
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 58810c6..ae3d657 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -896,6 +896,7 @@
 #ifdef CONFIG_TCP_MD5SIG
 static struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
 	.md5_lookup	=	tcp_v6_reqsk_md5_lookup,
+	.calc_md5_hash	=	tcp_v6_md5_hash_skb,
 };
 #endif