8 files changed, 54 insertions, 10 deletions

diff --git a/Documentation/sysctl/net.txt b/Documentation/sysctl/net.txt
index 35c62f522754..5992602469d8 100644
--- a/Documentation/sysctl/net.txt
+++ b/Documentation/sysctl/net.txt
@@ -270,6 +270,18 @@ optmem_max
 Maximum ancillary buffer size allowed per socket. Ancillary data is a sequence
 of struct cmsghdr structures with appended data.
 
+fb_tunnels_only_for_init_net
+----------------------------
+
+Controls if fallback tunnels (like tunl0, gre0, gretap0, erspan0,
+sit0, ip6tnl0, ip6gre0) are automatically created when a new
+network namespace is created, if corresponding tunnel is present
+in initial network namespace.
+If set to 1, these devices are not automatically created, and
+user space is responsible for creating them if needed.
+
+Default : 0  (for compatibility reasons)
+
 2. /proc/sys/net/unix - Parameters for Unix domain sockets
 -------------------------------------------------------
 
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 95a613a7cc1c..9711108c3916 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -585,6 +585,13 @@ struct netdev_queue {
 #endif
 } ____cacheline_aligned_in_smp;
 
+extern int sysctl_fb_tunnels_only_for_init_net;
+
+static inline bool net_has_fallback_tunnels(const struct net *net)
+{
+        return net == &init_net || !sysctl_fb_tunnels_only_for_init_net;
+}
+
 static inline int netdev_queue_numa_node_read(const struct netdev_queue *q)
 {
 #if defined(CONFIG_XPS) && defined(CONFIG_NUMA)
diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
index cbe5addb9293..540a4b4417bf 100644
--- a/include/net/ip_tunnels.h
+++ b/include/net/ip_tunnels.h
@@ -180,8 +180,10 @@ struct tnl_ptk_info {
 
 struct ip_tunnel_net {
         struct net_device *fb_tunnel_dev;
+        struct rtnl_link_ops *rtnl_link_ops;
         struct hlist_head tunnels[IP_TNL_HASH_SIZE];
         struct ip_tunnel __rcu *collect_md_tun;
+        int type;
 };
 
 static inline void ip_tunnel_key_init(struct ip_tunnel_key *key,
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index d714f65782b7..4f47f92459cc 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -32,6 +32,9 @@ static int max_skb_frags = MAX_SKB_FRAGS;
 
 static int net_msg_warn;        /* Unused, but still a sysctl */
 
+int sysctl_fb_tunnels_only_for_init_net __read_mostly = 0;
+EXPORT_SYMBOL(sysctl_fb_tunnels_only_for_init_net);
+
 #ifdef CONFIG_RPS
 static int rps_sock_flow_sysctl(struct ctl_table *table, int write,
                                 void __user *buffer, size_t *lenp, loff_t *ppos)
@@ -513,6 +516,15 @@ static struct ctl_table net_core_table[] = {
                 .proc_handler   = proc_dointvec_minmax,
                 .extra1         = &zero,
         },
+        {
+                .procname       = "fb_tunnels_only_for_init_net",
+                .data           = &sysctl_fb_tunnels_only_for_init_net,
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = &zero,
+                .extra2         = &one,
+        },
         { }
 };
 
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 602597dfc395..5fcb17cb426b 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -347,8 +347,7 @@ static struct ip_tunnel *ip_tunnel_create(struct net *net,
         struct net_device *dev;
         int t_hlen;
 
-        BUG_ON(!itn->fb_tunnel_dev);
-        dev = __ip_tunnel_create(net, itn->fb_tunnel_dev->rtnl_link_ops, parms);
+        dev = __ip_tunnel_create(net, itn->rtnl_link_ops, parms);
         if (IS_ERR(dev))
                 return ERR_CAST(dev);
 
@@ -822,7 +821,6 @@ int ip_tunnel_ioctl(struct net_device *dev, struct ip_tunnel_parm *p, int cmd)
         struct net *net = t->net;
         struct ip_tunnel_net *itn = net_generic(net, t->ip_tnl_net_id);
 
-        BUG_ON(!itn->fb_tunnel_dev);
         switch (cmd) {
         case SIOCGETTUNNEL:
                 if (dev == itn->fb_tunnel_dev) {
@@ -847,7 +845,7 @@ int ip_tunnel_ioctl(struct net_device *dev, struct ip_tunnel_parm *p, int cmd)
                                 p->o_key = 0;
                 }
 
-                t = ip_tunnel_find(itn, p, itn->fb_tunnel_dev->type);
+                t = ip_tunnel_find(itn, p, itn->type);
 
                 if (cmd == SIOCADDTUNNEL) {
                         if (!t) {
@@ -991,10 +989,15 @@ int ip_tunnel_init_net(struct net *net, unsigned int ip_tnl_net_id,
         struct ip_tunnel_parm parms;
         unsigned int i;
 
+        itn->rtnl_link_ops = ops;
         for (i = 0; i < IP_TNL_HASH_SIZE; i++)
                 INIT_HLIST_HEAD(&itn->tunnels[i]);
 
-        if (!ops) {
+        if (!ops || !net_has_fallback_tunnels(net)) {
+                struct ip_tunnel_net *it_init_net;
+
+                it_init_net = net_generic(&init_net, ip_tnl_net_id);
+                itn->type = it_init_net->type;
                 itn->fb_tunnel_dev = NULL;
                 return 0;
         }
@@ -1012,6 +1015,7 @@ int ip_tunnel_init_net(struct net *net, unsigned int ip_tnl_net_id,
                 itn->fb_tunnel_dev->features |= NETIF_F_NETNS_LOCAL;
                 itn->fb_tunnel_dev->mtu = ip_tunnel_bind_dev(itn->fb_tunnel_dev);
                 ip_tunnel_add(itn, netdev_priv(itn->fb_tunnel_dev));
+                itn->type = itn->fb_tunnel_dev->type;
         }
         rtnl_unlock();
 
@@ -1019,10 +1023,10 @@ int ip_tunnel_init_net(struct net *net, unsigned int ip_tnl_net_id,
 }
 EXPORT_SYMBOL_GPL(ip_tunnel_init_net);
 
-static void ip_tunnel_destroy(struct ip_tunnel_net *itn, struct list_head *head,
+static void ip_tunnel_destroy(struct net *net, struct ip_tunnel_net *itn,
+                              struct list_head *head,
                               struct rtnl_link_ops *ops)
 {
-        struct net *net = dev_net(itn->fb_tunnel_dev);
         struct net_device *dev, *aux;
         int h;
 
@@ -1054,7 +1058,7 @@ void ip_tunnel_delete_nets(struct list_head *net_list, unsigned int id,
         rtnl_lock();
         list_for_each_entry(net, net_list, exit_list) {
                 itn = net_generic(net, id);
-                ip_tunnel_destroy(itn, &list, ops);
+                ip_tunnel_destroy(net, itn, &list, ops);
         }
         unregister_netdevice_many(&list);
         rtnl_unlock();
diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 18a3dfbd0300..7d8775c9570d 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -236,7 +236,7 @@ static struct ip6_tnl *ip6gre_tunnel_lookup(struct net_device *dev,
                 return t;
 
         dev = ign->fb_tunnel_dev;
-        if (dev->flags & IFF_UP)
+        if (dev && dev->flags & IFF_UP)
                 return netdev_priv(dev);
 
         return NULL;
@@ -1472,6 +1472,8 @@ static int __net_init ip6gre_init_net(struct net *net)
         struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
         int err;
 
+        if (!net_has_fallback_tunnels(net))
+                return 0;
         ign->fb_tunnel_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6gre0",
                                           NET_NAME_UNKNOWN,
                                           ip6gre_tunnel_setup);
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 56c4967f1868..5c045fa407da 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -2205,6 +2205,8 @@ static int __net_init ip6_tnl_init_net(struct net *net)
         ip6n->tnls[0] = ip6n->tnls_wc;
         ip6n->tnls[1] = ip6n->tnls_r_l;
 
+        if (!net_has_fallback_tunnels(net))
+                return 0;
         err = -ENOMEM;
         ip6n->fb_tnl_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6tnl0",
                                         NET_NAME_UNKNOWN, ip6_tnl_dev_setup);
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index a9c4ac6efe22..8a4f8fddd812 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -182,7 +182,7 @@ static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn)
 #ifdef CONFIG_IPV6_SIT_6RD
         struct ip_tunnel *t = netdev_priv(dev);
 
-        if (dev == sitn->fb_tunnel_dev) {
+        if (dev == sitn->fb_tunnel_dev || !sitn->fb_tunnel_dev) {
                 ipv6_addr_set(&t->ip6rd.prefix, htonl(0x20020000), 0, 0, 0);
                 t->ip6rd.relay_prefix = 0;
                 t->ip6rd.prefixlen = 16;
@@ -1835,6 +1835,9 @@ static int __net_init sit_init_net(struct net *net)
         sitn->tunnels[2] = sitn->tunnels_r;
         sitn->tunnels[3] = sitn->tunnels_r_l;
 
+        if (!net_has_fallback_tunnels(net))
+                return 0;
+
         sitn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
                                            NET_NAME_UNKNOWN,
                                            ipip6_tunnel_setup);