[NETFILTER]: ip_nat_tftp: Fix expectation NAT

When a TFTP client is SNATed so that the port is also changed, the
port is never changed back for the expected connection.

Signed-off-by: Marcus Sundberg <marcus@ingate.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/ipv4/netfilter/ip_nat_tftp.c b/net/ipv4/netfilter/ip_nat_tftp.c
index 2215317c76b7..43c3bd7c118e 100644
--- a/net/ipv4/netfilter/ip_nat_tftp.c
+++ b/net/ipv4/netfilter/ip_nat_tftp.c
@@ -42,7 +42,10 @@ static unsigned int help(struct sk_buff **pskb,
                          enum ip_conntrack_info ctinfo,
                          struct ip_conntrack_expect *exp)
 {
-        exp->saved_proto.udp.port = exp->tuple.dst.u.tcp.port;
+        struct ip_conntrack *ct = exp->master;
+
+        exp->saved_proto.udp.port
+                = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
         exp->dir = IP_CT_DIR_REPLY;
         exp->expectfn = ip_nat_follow_master;
         if (ip_conntrack_expect_related(exp) != 0)