ip_tunnel: Don't allow to add the same tunnel multiple times.

When we try to add an already existing tunnel, we don't return an error. Instead we continue and call ip_tunnel_update(). This means that we can change existing tunnels by adding the same tunnel multiple times. It is even possible to change the tunnel endpoints of the fallback device. We fix this by returning an error if we try to add an existing tunnel. Signed-off-by: Steffen Klassert <[email protected]> Signed-off-by: David S. Miller <[email protected]>
cbmeeks · Sep 26, 2014 · d61746b · d61746b
1 parent b94d525
commit d61746b
Showing 1 changed file with 8 additions and 3 deletions.
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
@@ -764,9 +764,14 @@ int ip_tunnel_ioctl(struct net_device *dev, struct ip_tunnel_parm *p, int cmd)
 
 		t = ip_tunnel_find(itn, p, itn->fb_tunnel_dev->type);
 
-		if (!t && (cmd == SIOCADDTUNNEL)) {
-			t = ip_tunnel_create(net, itn, p);
-			err = PTR_ERR_OR_ZERO(t);
+		if (cmd == SIOCADDTUNNEL) {
+			if (!t) {
+				t = ip_tunnel_create(net, itn, p);
+				err = PTR_ERR_OR_ZERO(t);
+				break;
+			}
+
+			err = -EEXIST;
 			break;
 		}
 		if (dev != itn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {