4 files changed, 31 insertions, 3 deletions

diff --git a/include/linux/netfilter/nf_conntrack_ftp.h b/include/linux/netfilter/nf_conntrack_ftp.h
index 28f18df36525..8faf3f792d13 100644
--- a/include/linux/netfilter/nf_conntrack_ftp.h
+++ b/include/linux/netfilter/nf_conntrack_ftp.h
@@ -18,13 +18,17 @@ enum nf_ct_ftp_type {
 
 #define FTP_PORT	21
 
+#define NF_CT_FTP_SEQ_PICKUP	(1 << 0)
+
 #define NUM_SEQ_TO_REMEMBER 2
 /* This structure exists only once per master */
 struct nf_ct_ftp_master {
 	/* Valid seq positions for cmd matching after newline */
 	u_int32_t seq_aft_nl[IP_CT_DIR_MAX][NUM_SEQ_TO_REMEMBER];
 	/* 0 means seq_match_aft_nl not set */
-	int seq_aft_nl_num[IP_CT_DIR_MAX];
+	u_int16_t seq_aft_nl_num[IP_CT_DIR_MAX];
+	/* pickup sequence tracking, useful for conntrackd */
+	u_int16_t flags[IP_CT_DIR_MAX];
 };
 
 struct nf_conntrack_expect;
diff --git a/net/netfilter/nf_conntrack_ftp.c b/net/netfilter/nf_conntrack_ftp.c
index f8cc26ad4456..1ce3befb7c8a 100644
--- a/net/netfilter/nf_conntrack_ftp.c
+++ b/net/netfilter/nf_conntrack_ftp.c
@@ -396,6 +396,12 @@ static int help(struct sk_buff *skb,
 
 	/* Look up to see if we're just after a \n. */
 	if (!find_nl_seq(ntohl(th->seq), ct_ftp_info, dir)) {
+		/* We're picking up this, clear flags and let it continue */
+		if (unlikely(ct_ftp_info->flags[dir] & NF_CT_FTP_SEQ_PICKUP)) {
+			ct_ftp_info->flags[dir] ^= NF_CT_FTP_SEQ_PICKUP;
+			goto skip_nl_seq;
+		}
+
 		/* Now if this ends in \n, update ftp info. */
 		pr_debug("nf_conntrack_ftp: wrong seq pos %s(%u) or %s(%u)\n",
 			 ct_ftp_info->seq_aft_nl_num[dir] > 0 ? "" : "(UNSET)",
@@ -406,6 +412,7 @@ static int help(struct sk_buff *skb,
 		goto out_update_nl;
 	}
 
+skip_nl_seq:
 	/* Initialize IP/IPv6 addr to expected address (it's not mentioned
 	   in EPSV responses) */
 	cmd.l3num = nf_ct_l3num(ct);
@@ -512,6 +519,19 @@ out_update_nl:
 	return ret;
 }
 
+static int nf_ct_ftp_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
+{
+	struct nf_ct_ftp_master *ftp = nfct_help_data(ct);
+
+	/* This conntrack has been injected from user-space, always pick up
+	 * sequence tracking. Otherwise, the first FTP command after the
+	 * failover breaks.
+	 */
+	ftp->flags[IP_CT_DIR_ORIGINAL] |= NF_CT_FTP_SEQ_PICKUP;
+	ftp->flags[IP_CT_DIR_REPLY] |= NF_CT_FTP_SEQ_PICKUP;
+	return 0;
+}
+
 static struct nf_conntrack_helper ftp[MAX_PORTS][2] __read_mostly;
 
 static const struct nf_conntrack_expect_policy ftp_exp_policy = {
@@ -561,6 +581,7 @@ static int __init nf_conntrack_ftp_init(void)
 			ftp[i][j].expect_policy = &ftp_exp_policy;
 			ftp[i][j].me = THIS_MODULE;
 			ftp[i][j].help = help;
+			ftp[i][j].from_nlattr = nf_ct_ftp_from_nlattr;
 			if (ports[i] == FTP_PORT)
 				sprintf(ftp[i][j].name, "ftp");
 			else
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 2dcd080b8c4f..7bbfb3deea30 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1238,7 +1238,7 @@ ctnetlink_change_helper(struct nf_conn *ct, const struct nlattr * const cda[])
 	if (help) {
 		if (help->helper == helper) {
 			/* update private helper data if allowed. */
-			if (helper->from_nlattr && helpinfo)
+			if (helper->from_nlattr)
 				helper->from_nlattr(helpinfo, ct);
 			return 0;
 		} else
@@ -1467,7 +1467,7 @@ ctnetlink_create_conntrack(struct net *net, u16 zone,
 				goto err2;
 			}
 			/* set private helper data if allowed. */
-			if (helper->from_nlattr && helpinfo)
+			if (helper->from_nlattr)
 				helper->from_nlattr(helpinfo, ct);
 
 			/* not in hash table yet so not strictly necessary */
diff --git a/net/netfilter/nfnetlink_cthelper.c b/net/netfilter/nfnetlink_cthelper.c
index 3678073360a3..945950a8b1f1 100644
--- a/net/netfilter/nfnetlink_cthelper.c
+++ b/net/netfilter/nfnetlink_cthelper.c
@@ -85,6 +85,9 @@ nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
 {
 	const struct nf_conn_help *help = nfct_help(ct);
 
+	if (attr == NULL)
+		return -EINVAL;
+
 	if (help->helper->data_len == 0)
 		return -EINVAL;