ip6_tunnel: Return an error when adding an existing tunnel.

ip6_tnl_locate() should not return an existing tunnel if
create is true. Otherwise it is possible to add the same
tunnel multiple times without getting an error.

So return NULL if the tunnel that should be created already
exists.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index f9de5a695072..69a84b464009 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -364,8 +364,12 @@ static struct ip6_tnl *ip6_tnl_locate(struct net *net,
              (t = rtnl_dereference(*tp)) != NULL;
              tp = &t->next) {
                 if (ipv6_addr_equal(local, &t->parms.laddr) &&
-                    ipv6_addr_equal(remote, &t->parms.raddr))
+                    ipv6_addr_equal(remote, &t->parms.raddr)) {
+                        if (create)
+                                return NULL;
+
                         return t;
+                }
         }
         if (!create)
                 return NULL;