ipvs: avoid oops for passive FTP

Fix Passive FTP problem in ip_vs_ftp:

- Do not oops in nf_nat_set_seq_adjust (adjust_tcp_sequence) when
  iptable_nat module is not loaded

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/netfilter/ipvs/ip_vs_ftp.c b/net/netfilter/ipvs/ip_vs_ftp.c
index f228a17ec649..33b329bfc2d2 100644
--- a/net/netfilter/ipvs/ip_vs_ftp.c
+++ b/net/netfilter/ipvs/ip_vs_ftp.c
@@ -45,6 +45,7 @@
 #include <linux/netfilter.h>
 #include <net/netfilter/nf_conntrack.h>
 #include <net/netfilter/nf_conntrack_expect.h>
+#include <net/netfilter/nf_nat.h>
 #include <net/netfilter/nf_nat_helper.h>
 #include <linux/gfp.h>
 #include <net/protocol.h>
@@ -359,7 +360,7 @@ static int ip_vs_ftp_out(struct ip_vs_app *app, struct ip_vs_conn *cp,
                 buf_len = strlen(buf);
 
                 ct = nf_ct_get(skb, &ctinfo);
-                if (ct && !nf_ct_is_untracked(ct)) {
+                if (ct && !nf_ct_is_untracked(ct) && nfct_nat(ct)) {
                         /* If mangling fails this function will return 0
                          * which will cause the packet to be dropped.
                          * Mangling can only fail under memory pressure,