[IPVS]: ip_vs_ftp breaks connections using persistence

ip_vs_ftp when loaded can create NAT connections with unknown client
port for passive FTP. For such expectations we lookup with cport=0 on
incoming packet but it matches the format of the persistence templates
causing packets to other persistent virtual servers to be forwarded to
real server without creating connection. Later the reply packets are
treated as foreign and not SNAT-ed.

This patch changes the connection lookup for packets from clients:

* introduce IP_VS_CONN_F_TEMPLATE connection flag to mark the
  connection as template

* create new connection lookup function just for templates -
  ip_vs_ct_in_get

* make sure ip_vs_conn_in_get hits only connections with
  IP_VS_CONN_F_NO_CPORT flag set when s_port is 0. By this way
  we avoid returning template when looking for cport=0 (ftp)

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

1 files changed, 14 insertions, 6 deletions

diff --git a/net/ipv4/ipvs/ip_vs_sync.c b/net/ipv4/ipvs/ip_vs_sync.c
index 574d1f509b46..2e5ced3d8062 100644
--- a/net/ipv4/ipvs/ip_vs_sync.c
+++ b/net/ipv4/ipvs/ip_vs_sync.c
@@ -297,16 +297,24 @@ static void ip_vs_process_message(const char *buffer, const size_t buflen)
 
 	p = (char *)buffer + sizeof(struct ip_vs_sync_mesg);
 	for (i=0; i<m->nr_conns; i++) {
+		unsigned flags;
+
 		s = (struct ip_vs_sync_conn *)p;
-		cp = ip_vs_conn_in_get(s->protocol,
-				       s->caddr, s->cport,
-				       s->vaddr, s->vport);
+		flags = ntohs(s->flags);
+		if (!(flags & IP_VS_CONN_F_TEMPLATE))
+			cp = ip_vs_conn_in_get(s->protocol,
+					       s->caddr, s->cport,
+					       s->vaddr, s->vport);
+		else
+			cp = ip_vs_ct_in_get(s->protocol,
+					       s->caddr, s->cport,
+					       s->vaddr, s->vport);
 		if (!cp) {
 			cp = ip_vs_conn_new(s->protocol,
 					    s->caddr, s->cport,
 					    s->vaddr, s->vport,
 					    s->daddr, s->dport,
-					    ntohs(s->flags), NULL);
+					    flags, NULL);
 			if (!cp) {
 				IP_VS_ERR("ip_vs_conn_new failed\n");
 				return;
@@ -315,11 +323,11 @@ static void ip_vs_process_message(const char *buffer, const size_t buflen)
 		} else if (!cp->dest) {
 			/* it is an entry created by the synchronization */
 			cp->state = ntohs(s->state);
-			cp->flags = ntohs(s->flags) | IP_VS_CONN_F_HASHED;
+			cp->flags = flags | IP_VS_CONN_F_HASHED;
 		}	/* Note that we don't touch its state and flags
 			   if it is a normal entry. */
 
-		if (ntohs(s->flags) & IP_VS_CONN_F_SEQ_MASK) {
+		if (flags & IP_VS_CONN_F_SEQ_MASK) {
 			opt = (struct ip_vs_sync_conn_options *)&s[1];
 			memcpy(&cp->in_seq, opt, sizeof(*opt));
 			p += FULL_CONN_SIZE;