[NETFILTER]: nf_conntrack_ftp: fix newline sequence number calculation

When the packet size is changed by the FTP NAT helper, the connection
tracking helper adjusts the sequence number of the newline character
by the size difference. This is wrong because NAT sequence number
adjustment happens after helpers are called, so the unadjusted number
is compared to the already adjusted one.

Based on report by YU, Haitao <yuhaitao@tsinghua.org.cn>

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/nf_conntrack_ftp.c b/net/netfilter/nf_conntrack_ftp.c
index 4bb669c..82db2aa 100644
--- a/net/netfilter/nf_conntrack_ftp.c
+++ b/net/netfilter/nf_conntrack_ftp.c
@@ -48,8 +48,7 @@
 				enum nf_ct_ftp_type type,
 				unsigned int matchoff,
 				unsigned int matchlen,
-				struct nf_conntrack_expect *exp,
-				u32 *seq);
+				struct nf_conntrack_expect *exp);
 EXPORT_SYMBOL_GPL(nf_nat_ftp_hook);
 
 #if 0
@@ -521,7 +520,7 @@
 	nf_nat_ftp = rcu_dereference(nf_nat_ftp_hook);
 	if (nf_nat_ftp && ct->status & IPS_NAT_MASK)
 		ret = nf_nat_ftp(pskb, ctinfo, search[dir][i].ftptype,
-				 matchoff, matchlen, exp, &seq);
+				 matchoff, matchlen, exp);
 	else {
 		/* Can't expect this?  Best to drop packet now. */
 		if (nf_conntrack_expect_related(exp) != 0)