[NET]: Make the loopback device per network namespace.

This patch makes loopback_dev per network namespace.  Adding
code to create a different loopback device for each network
namespace and adding the code to free a loopback device
when a network namespace exits.

This patch modifies all users the loopback_dev so they
access it as init_net.loopback_dev, keeping all of the
code compiling and working.  A later pass will be needed to
update the users to use something other than the initial network
namespace.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/loopback.c

@@ -57,6 +57,7 @@
 #include <linux/ip.h>
 #include <linux/tcp.h>
 #include <linux/percpu.h>
+#include <net/net_namespace.h>
 
 struct pcpu_lstats {
 	unsigned long packets;
@@ -252,7 +253,7 @@ static void loopback_setup(struct net_device *dev)
 }
 
 /* Setup and register the loopback device. */
-static int __init loopback_init(void)
+static int loopback_net_init(struct net *net)
 {
 	struct net_device *dev;
 	int err;
@@ -262,12 +263,13 @@ static int __init loopback_init(void)
 	if (!dev)
 		goto out;
 
+	dev->nd_net = net;
 	err = register_netdev(dev);
 	if (err)
 		goto out_free_netdev;
 
 	err = 0;
-	loopback_dev = dev;
+	net->loopback_dev = dev;
 
 out:
 	if (err)
@@ -279,7 +281,21 @@ out_free_netdev:
 	goto out;
 }
 
-fs_initcall(loopback_init);
+static void loopback_net_exit(struct net *net)
+{
+	struct net_device *dev = net->loopback_dev;
+
+	unregister_netdev(dev);
+}
+
+static struct pernet_operations loopback_net_ops = {
+       .init = loopback_net_init,
+       .exit = loopback_net_exit,
+};
+
+static int __init loopback_init(void)
+{
+	return register_pernet_device(&loopback_net_ops);
+}
 
-struct net_device *loopback_dev;
-EXPORT_SYMBOL(loopback_dev);
+fs_initcall(loopback_init);

include/linux/netdevice.h

@@ -742,7 +742,6 @@ struct packet_type {
 #include <linux/interrupt.h>
 #include <linux/notifier.h>
 
-extern struct net_device		*loopback_dev;		/* The loopback */
 extern rwlock_t				dev_base_lock;		/* Device list lock */
 
 

include/net/net_namespace.h

@@ -9,6 +9,7 @@
 #include <linux/list.h>
 
 struct proc_dir_entry;
+struct net_device;
 struct net {
 	atomic_t		count;		/* To decided when the network
 						 *  namespace should be freed.
@@ -23,6 +24,8 @@ struct net {
 	struct proc_dir_entry 	*proc_net_stat;
 	struct proc_dir_entry 	*proc_net_root;
 
+	struct net_device       *loopback_dev;          /* The loopback */
+
 	struct list_head 	dev_base_head;
 	struct hlist_head 	*dev_name_head;
 	struct hlist_head	*dev_index_head;

net/core/dst.c

@@ -18,6 +18,7 @@
 #include <linux/types.h>
 #include <net/net_namespace.h>
 
+#include <net/net_namespace.h>
 #include <net/dst.h>
 
 /*
@@ -278,11 +279,11 @@ static inline void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 	if (!unregister) {
 		dst->input = dst->output = dst_discard;
 	} else {
-		dst->dev = loopback_dev;
+		dst->dev = init_net.loopback_dev;
 		dev_hold(dst->dev);
 		dev_put(dev);
 		if (dst->neighbour && dst->neighbour->dev == dev) {
-			dst->neighbour->dev = loopback_dev;
+			dst->neighbour->dev = init_net.loopback_dev;
 			dev_put(dev);
 			dev_hold(dst->neighbour->dev);
 		}

net/decnet/dn_dev.c

@@ -869,10 +869,10 @@ last_chance:
 		rv = dn_dev_get_first(dev, addr);
 		read_unlock(&dev_base_lock);
 		dev_put(dev);
-		if (rv == 0 || dev == loopback_dev)
+		if (rv == 0 || dev == init_net.loopback_dev)
 			return rv;
 	}
-	dev = loopback_dev;
+	dev = init_net.loopback_dev;
 	dev_hold(dev);
 	goto last_chance;
 }

net/decnet/dn_route.c

@@ -887,7 +887,7 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowi *old
 					.scope = RT_SCOPE_UNIVERSE,
 				     } },
 			    .mark = oldflp->mark,
-			    .iif = loopback_dev->ifindex,
+			    .iif = init_net.loopback_dev->ifindex,
 			    .oif = oldflp->oif };
 	struct dn_route *rt = NULL;
 	struct net_device *dev_out = NULL, *dev;
@@ -904,7 +904,7 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowi *old
 		       "dn_route_output_slow: dst=%04x src=%04x mark=%d"
 		       " iif=%d oif=%d\n", dn_ntohs(oldflp->fld_dst),
 		       dn_ntohs(oldflp->fld_src),
-		       oldflp->mark, loopback_dev->ifindex, oldflp->oif);
+		       oldflp->mark, init_net.loopback_dev->ifindex, oldflp->oif);
 
 	/* If we have an output interface, verify its a DECnet device */
 	if (oldflp->oif) {
@@ -957,7 +957,7 @@ source_ok:
 		err = -EADDRNOTAVAIL;
 		if (dev_out)
 			dev_put(dev_out);
-		dev_out = loopback_dev;
+		dev_out = init_net.loopback_dev;
 		dev_hold(dev_out);
 		if (!fl.fld_dst) {
 			fl.fld_dst =
@@ -966,7 +966,7 @@ source_ok:
 			if (!fl.fld_dst)
 				goto out;
 		}
-		fl.oif = loopback_dev->ifindex;
+		fl.oif = init_net.loopback_dev->ifindex;
 		res.type = RTN_LOCAL;
 		goto make_route;
 	}
@@ -1012,7 +1012,7 @@ source_ok:
 					if (dev_out)
 						dev_put(dev_out);
 					if (dn_dev_islocal(neigh->dev, fl.fld_dst)) {
-						dev_out = loopback_dev;
+						dev_out = init_net.loopback_dev;
 						res.type = RTN_LOCAL;
 					} else {
 						dev_out = neigh->dev;
@@ -1033,7 +1033,7 @@ source_ok:
 		/* Possible improvement - check all devices for local addr */
 		if (dn_dev_islocal(dev_out, fl.fld_dst)) {
 			dev_put(dev_out);
-			dev_out = loopback_dev;
+			dev_out = init_net.loopback_dev;
 			dev_hold(dev_out);
 			res.type = RTN_LOCAL;
 			goto select_source;
@@ -1069,7 +1069,7 @@ select_source:
 			fl.fld_src = fl.fld_dst;
 		if (dev_out)
 			dev_put(dev_out);
-		dev_out = loopback_dev;
+		dev_out = init_net.loopback_dev;
 		dev_hold(dev_out);
 		fl.oif = dev_out->ifindex;
 		if (res.fi)

net/ipv4/route.c

@@ -1402,8 +1402,8 @@ static void ipv4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 {
 	struct rtable *rt = (struct rtable *) dst;
 	struct in_device *idev = rt->idev;
-	if (dev != loopback_dev && idev && idev->dev == dev) {
-		struct in_device *loopback_idev = in_dev_get(loopback_dev);
+	if (dev != init_net.loopback_dev && idev && idev->dev == dev) {
+		struct in_device *loopback_idev = in_dev_get(init_net.loopback_dev);
 		if (loopback_idev) {
 			rt->idev = loopback_idev;
 			in_dev_put(idev);
@@ -1555,7 +1555,7 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 #endif
 	rth->rt_iif	=
 	rth->fl.iif	= dev->ifindex;
-	rth->u.dst.dev	= loopback_dev;
+	rth->u.dst.dev	= init_net.loopback_dev;
 	dev_hold(rth->u.dst.dev);
 	rth->idev	= in_dev_get(rth->u.dst.dev);
 	rth->fl.oif	= 0;
@@ -1812,7 +1812,7 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 	if (res.type == RTN_LOCAL) {
 		int result;
 		result = fib_validate_source(saddr, daddr, tos,
-					     loopback_dev->ifindex,
+					     init_net.loopback_dev->ifindex,
 					     dev, &spec_dst, &itag);
 		if (result < 0)
 			goto martian_source;
@@ -1879,7 +1879,7 @@ local_input:
 #endif
 	rth->rt_iif	=
 	rth->fl.iif	= dev->ifindex;
-	rth->u.dst.dev	= loopback_dev;
+	rth->u.dst.dev	= init_net.loopback_dev;
 	dev_hold(rth->u.dst.dev);
 	rth->idev	= in_dev_get(rth->u.dst.dev);
 	rth->rt_gateway	= daddr;
@@ -2149,7 +2149,7 @@ static int ip_route_output_slow(struct rtable **rp, const struct flowi *oldflp)
 						  RT_SCOPE_UNIVERSE),
 				      } },
 			    .mark = oldflp->mark,
-			    .iif = loopback_dev->ifindex,
+			    .iif = init_net.loopback_dev->ifindex,
 			    .oif = oldflp->oif };
 	struct fib_result res;
 	unsigned flags = 0;
@@ -2243,9 +2243,9 @@ static int ip_route_output_slow(struct rtable **rp, const struct flowi *oldflp)
 			fl.fl4_dst = fl.fl4_src = htonl(INADDR_LOOPBACK);
 		if (dev_out)
 			dev_put(dev_out);
-		dev_out = loopback_dev;
+		dev_out = init_net.loopback_dev;
 		dev_hold(dev_out);
-		fl.oif = loopback_dev->ifindex;
+		fl.oif = init_net.loopback_dev->ifindex;
 		res.type = RTN_LOCAL;
 		flags |= RTCF_LOCAL;
 		goto make_route;
@@ -2290,7 +2290,7 @@ static int ip_route_output_slow(struct rtable **rp, const struct flowi *oldflp)
 			fl.fl4_src = fl.fl4_dst;
 		if (dev_out)
 			dev_put(dev_out);
-		dev_out = loopback_dev;
+		dev_out = init_net.loopback_dev;
 		dev_hold(dev_out);
 		fl.oif = dev_out->ifindex;
 		if (res.fi)

net/ipv4/xfrm4_policy.c

@@ -306,7 +306,7 @@ static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 
 	xdst = (struct xfrm_dst *)dst;
 	if (xdst->u.rt.idev->dev == dev) {
-		struct in_device *loopback_idev = in_dev_get(loopback_dev);
+		struct in_device *loopback_idev = in_dev_get(init_net.loopback_dev);
 		BUG_ON(!loopback_idev);
 
 		do {

net/ipv6/addrconf.c

@@ -2410,7 +2410,7 @@ static int addrconf_ifdown(struct net_device *dev, int how)
 
 	ASSERT_RTNL();
 
-	if (dev == loopback_dev && how == 1)
+	if (dev == init_net.loopback_dev && how == 1)
 		how = 0;
 
 	rt6_ifdown(dev);
@@ -4212,19 +4212,19 @@ int __init addrconf_init(void)
 	 * device and it being up should be removed.
 	 */
 	rtnl_lock();
-	if (!ipv6_add_dev(loopback_dev))
+	if (!ipv6_add_dev(init_net.loopback_dev))
 		err = -ENOMEM;
 	rtnl_unlock();
 	if (err)
 		return err;
 
-	ip6_null_entry.u.dst.dev = loopback_dev;
-	ip6_null_entry.rt6i_idev = in6_dev_get(loopback_dev);
+	ip6_null_entry.u.dst.dev = init_net.loopback_dev;
+	ip6_null_entry.rt6i_idev = in6_dev_get(init_net.loopback_dev);
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
-	ip6_prohibit_entry.u.dst.dev = loopback_dev;
-	ip6_prohibit_entry.rt6i_idev = in6_dev_get(loopback_dev);
-	ip6_blk_hole_entry.u.dst.dev = loopback_dev;
-	ip6_blk_hole_entry.rt6i_idev = in6_dev_get(loopback_dev);
+	ip6_prohibit_entry.u.dst.dev = init_net.loopback_dev;
+	ip6_prohibit_entry.rt6i_idev = in6_dev_get(init_net.loopback_dev);
+	ip6_blk_hole_entry.u.dst.dev = init_net.loopback_dev;
+	ip6_blk_hole_entry.rt6i_idev = in6_dev_get(init_net.loopback_dev);
 #endif
 
 	register_netdevice_notifier(&ipv6_dev_notf);
@@ -4279,7 +4279,7 @@ void __exit addrconf_cleanup(void)
 			continue;
 		addrconf_ifdown(dev, 1);
 	}
-	addrconf_ifdown(loopback_dev, 2);
+	addrconf_ifdown(init_net.loopback_dev, 2);
 
 	/*
 	 *	Check hash table.

net/ipv6/netfilter/ip6t_REJECT.c

@@ -167,7 +167,7 @@ static inline void
 send_unreach(struct sk_buff *skb_in, unsigned char code, unsigned int hooknum)
 {
 	if (hooknum == NF_IP6_LOCAL_OUT && skb_in->dev == NULL)
-		skb_in->dev = loopback_dev;
+		skb_in->dev = init_net.loopback_dev;
 
 	icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0, NULL);
 }

net/ipv6/route.c

@@ -221,8 +221,8 @@ static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 	struct rt6_info *rt = (struct rt6_info *)dst;
 	struct inet6_dev *idev = rt->rt6i_idev;
 
-	if (dev != loopback_dev && idev != NULL && idev->dev == dev) {
-		struct inet6_dev *loopback_idev = in6_dev_get(loopback_dev);
+	if (dev != init_net.loopback_dev && idev != NULL && idev->dev == dev) {
+		struct inet6_dev *loopback_idev = in6_dev_get(init_net.loopback_dev);
 		if (loopback_idev != NULL) {
 			rt->rt6i_idev = loopback_idev;
 			in6_dev_put(idev);
@@ -1185,12 +1185,12 @@ int ip6_route_add(struct fib6_config *cfg)
 	if ((cfg->fc_flags & RTF_REJECT) ||
 	    (dev && (dev->flags&IFF_LOOPBACK) && !(addr_type&IPV6_ADDR_LOOPBACK))) {
 		/* hold loopback dev/idev if we haven't done so. */
-		if (dev != loopback_dev) {
+		if (dev != init_net.loopback_dev) {
 			if (dev) {
 				dev_put(dev);
 				in6_dev_put(idev);
 			}
-			dev = loopback_dev;
+			dev = init_net.loopback_dev;
 			dev_hold(dev);
 			idev = in6_dev_get(dev);
 			if (!idev) {
@@ -1894,13 +1894,13 @@ struct rt6_info *addrconf_dst_alloc(struct inet6_dev *idev,
 	if (rt == NULL)
 		return ERR_PTR(-ENOMEM);
 
-	dev_hold(loopback_dev);
+	dev_hold(init_net.loopback_dev);
 	in6_dev_hold(idev);
 
 	rt->u.dst.flags = DST_HOST;
 	rt->u.dst.input = ip6_input;
 	rt->u.dst.output = ip6_output;
-	rt->rt6i_dev = loopback_dev;
+	rt->rt6i_dev = init_net.loopback_dev;
 	rt->rt6i_idev = idev;
 	rt->u.dst.metrics[RTAX_MTU-1] = ipv6_get_mtu(rt->rt6i_dev);
 	rt->u.dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(dst_mtu(&rt->u.dst));

net/ipv6/xfrm6_policy.c

@@ -375,7 +375,7 @@ static void xfrm6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 
 	xdst = (struct xfrm_dst *)dst;
 	if (xdst->u.rt6.rt6i_idev->dev == dev) {
-		struct inet6_dev *loopback_idev = in6_dev_get(loopback_dev);
+		struct inet6_dev *loopback_idev = in6_dev_get(init_net.loopback_dev);
 		BUG_ON(!loopback_idev);
 
 		do {

net/xfrm/xfrm_policy.c

@@ -1949,7 +1949,7 @@ static int stale_bundle(struct dst_entry *dst)
 void xfrm_dst_ifdown(struct dst_entry *dst, struct net_device *dev)
 {
 	while ((dst = dst->child) && dst->xfrm && dst->dev == dev) {
-		dst->dev = loopback_dev;
+		dst->dev = init_net.loopback_dev;
 		dev_hold(dst->dev);
 		dev_put(dev);
 	}