Phonet: disable network namespace support

[Solved differently upstream]

Network namespace in the Phonet socket stack causes an OOPS when a
namespace is destroyed. This occurs as the loopback exit_net handler is
called after the Phonet exit_net handler, and re-enters the Phonet
stack. I cannot think of any nice way to fix this in kernel <= 2.6.32.

For lack of a better solution, disable namespace support completely.
If you need that, upgrade to a newer kernel.

Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Acked-by: David S. Miller <davem@davemloft.net>

net/phonet/af_phonet.c

@@ -67,6 +67,8 @@ static int pn_socket_create(struct net *net, struct socket *sock, int protocol)
 	struct phonet_protocol *pnp;
 	int err;
 
+	if (!net_eq(net, &init_net))
+		return -EAFNOSUPPORT;
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
@@ -353,6 +355,8 @@ static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
 	struct sockaddr_pn sa;
 	u16 len;
 
+	if (!net_eq(net, &init_net))
+		goto out;
 	/* check we have at least a full Phonet header */
 	if (!pskb_pull(skb, sizeof(struct phonethdr)))
 		goto out;

net/phonet/pn_dev.c

@@ -246,7 +246,11 @@ static struct notifier_block phonet_device_notifier = {
 /* Per-namespace Phonet devices handling */
 static int phonet_init_net(struct net *net)
 {
-	struct phonet_net *pnn = kmalloc(sizeof(*pnn), GFP_KERNEL);
+	struct phonet_net *pnn;
+
+	if (!net_eq(net, &init_net))
+		return 0;
+	pnn = kmalloc(sizeof(*pnn), GFP_KERNEL);
 	if (!pnn)
 		return -ENOMEM;
 
@@ -263,9 +267,13 @@ static int phonet_init_net(struct net *net)
 
 static void phonet_exit_net(struct net *net)
 {
-	struct phonet_net *pnn = net_generic(net, phonet_net_id);
+	struct phonet_net *pnn;
 	struct net_device *dev;
 
+	if (!net_eq(net, &init_net))
+		return;
+	pnn = net_generic(net, phonet_net_id);
+
 	rtnl_lock();
 	for_each_netdev(net, dev)
 		phonet_device_destroy(dev);

net/phonet/pn_netlink.c

@@ -68,6 +68,8 @@ static int addr_doit(struct sk_buff *skb, struct nlmsghdr *nlh, void *attr)
 	int err;
 	u8 pnaddr;
 
+	if (!net_eq(net, &init_net))
+		return -EOPNOTSUPP;
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
@@ -124,12 +126,16 @@ static int fill_addr(struct sk_buff *skb, struct net_device *dev, u8 addr,
 
 static int getaddr_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 {
+	struct net *net = sock_net(skb->sk);
 	struct phonet_device_list *pndevs;
 	struct phonet_device *pnd;
 	int dev_idx = 0, dev_start_idx = cb->args[0];
 	int addr_idx = 0, addr_start_idx = cb->args[1];
 
-	pndevs = phonet_device_list(sock_net(skb->sk));
+	if (!net_eq(net, &init_net))
+		goto skip;
+
+	pndevs = phonet_device_list(net);
 	spin_lock_bh(&pndevs->lock);
 	list_for_each_entry(pnd, &pndevs->list, list) {
 		u8 addr;
@@ -154,6 +160,7 @@ static int getaddr_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 
 out:
 	spin_unlock_bh(&pndevs->lock);
+skip:
 	cb->args[0] = dev_idx;
 	cb->args[1] = addr_idx;