can: initial support for network namespaces

This patch adds initial support for network namespaces. The changes only
enable support in the CAN raw, proc and af_can code. GW and BCM still
have their checks that ensure that they are used only from the main
namespace.

The patch boils down to moving the global structures, i.e. the global
filter list and their /proc stats, into a per-namespace structure and passing
around the corresponding "struct net" in a lot of different places.

Changes since v1:
 - rebased on current HEAD (2bfe01e)
 - fixed overlong line

Signed-off-by: Mario Kicherer <[email protected]>
Signed-off-by: Marc Kleine-Budde <[email protected]>

Author: anyc

include/linux/can/core.h

@@ -45,12 +45,13 @@ struct can_proto {
 extern int  can_proto_register(const struct can_proto *cp);
 extern void can_proto_unregister(const struct can_proto *cp);
 
-int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
+int can_rx_register(struct net *net, struct net_device *dev,
+		    canid_t can_id, canid_t mask,
 		    void (*func)(struct sk_buff *, void *),
 		    void *data, char *ident, struct sock *sk);
 
-extern void can_rx_unregister(struct net_device *dev, canid_t can_id,
-			      canid_t mask,
+extern void can_rx_unregister(struct net *net, struct net_device *dev,
+			      canid_t can_id, canid_t mask,
 			      void (*func)(struct sk_buff *, void *),
 			      void *data);
 

include/net/net_namespace.h

@@ -27,6 +27,7 @@
 #include <net/netns/nftables.h>
 #include <net/netns/xfrm.h>
 #include <net/netns/mpls.h>
+#include <net/netns/can.h>
 #include <linux/ns_common.h>
 #include <linux/idr.h>
 #include <linux/skbuff.h>
@@ -140,6 +141,9 @@ struct net {
 #endif
 #if IS_ENABLED(CONFIG_MPLS)
 	struct netns_mpls	mpls;
+#endif
+#if IS_ENABLED(CONFIG_CAN)
+	struct netns_can	can;
 #endif
 	struct sock		*diag_nlsk;
 	atomic_t		fnhe_genid;

include/net/netns/can.h

@@ -0,0 +1,31 @@
+/*
+ * can in net namespaces
+ */
+
+#ifndef __NETNS_CAN_H__
+#define __NETNS_CAN_H__
+
+#include <linux/spinlock.h>
+
+struct dev_rcv_lists;
+
+struct netns_can {
+#if IS_ENABLED(CONFIG_PROC_FS)
+	struct proc_dir_entry *proc_dir;
+	struct proc_dir_entry *pde_version;
+	struct proc_dir_entry *pde_stats;
+	struct proc_dir_entry *pde_reset_stats;
+	struct proc_dir_entry *pde_rcvlist_all;
+	struct proc_dir_entry *pde_rcvlist_fil;
+	struct proc_dir_entry *pde_rcvlist_inv;
+	struct proc_dir_entry *pde_rcvlist_sff;
+	struct proc_dir_entry *pde_rcvlist_eff;
+	struct proc_dir_entry *pde_rcvlist_err;
+#endif
+
+	/* receive filters subscribed for 'all' CAN devices */
+	struct dev_rcv_lists *can_rx_alldev_list;
+	spinlock_t can_rcvlists_lock;
+};
+
+#endif /* __NETNS_CAN_H__ */

net/can/af_can.c

@@ -75,9 +75,7 @@ static int stats_timer __read_mostly = 1;
 module_param(stats_timer, int, S_IRUGO);
 MODULE_PARM_DESC(stats_timer, "enable timer for statistics (default:on)");
 
-/* receive filters subscribed for 'all' CAN devices */
-struct dev_rcv_lists can_rx_alldev_list;
-static DEFINE_SPINLOCK(can_rcvlists_lock);
+static int can_net_id;
 
 static struct kmem_cache *rcv_cache __read_mostly;
 
@@ -145,9 +143,6 @@ static int can_create(struct net *net, struct socket *sock, int protocol,
 	if (protocol < 0 || protocol >= CAN_NPROTO)
 		return -EINVAL;
 
-	if (!net_eq(net, &init_net))
-		return -EAFNOSUPPORT;
-
 	cp = can_get_proto(protocol);
 
 #ifdef CONFIG_MODULES
@@ -331,10 +326,11 @@ EXPORT_SYMBOL(can_send);
  * af_can rx path
  */
 
-static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev)
+static struct dev_rcv_lists *find_dev_rcv_lists(struct net *net,
+						struct net_device *dev)
 {
 	if (!dev)
-		return &can_rx_alldev_list;
+		return net->can.can_rx_alldev_list;
 	else
 		return (struct dev_rcv_lists *)dev->ml_priv;
 }
@@ -467,9 +463,9 @@ static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask,
  *  -ENOMEM on missing cache mem to create subscription entry
  *  -ENODEV unknown device
  */
-int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
-		    void (*func)(struct sk_buff *, void *), void *data,
-		    char *ident, struct sock *sk)
+int can_rx_register(struct net *net, struct net_device *dev, canid_t can_id,
+		    canid_t mask, void (*func)(struct sk_buff *, void *),
+		    void *data, char *ident, struct sock *sk)
 {
 	struct receiver *r;
 	struct hlist_head *rl;
@@ -481,13 +477,16 @@ int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
 	if (dev && dev->type != ARPHRD_CAN)
 		return -ENODEV;
 
+	if (dev && !net_eq(net, dev_net(dev)))
+		return -ENODEV;
+
 	r = kmem_cache_alloc(rcv_cache, GFP_KERNEL);
 	if (!r)
 		return -ENOMEM;
 
-	spin_lock(&can_rcvlists_lock);
+	spin_lock(&net->can.can_rcvlists_lock);
 
-	d = find_dev_rcv_lists(dev);
+	d = find_dev_rcv_lists(net, dev);
 	if (d) {
 		rl = find_rcv_list(&can_id, &mask, d);
 
@@ -510,7 +509,7 @@ int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
 		err = -ENODEV;
 	}
 
-	spin_unlock(&can_rcvlists_lock);
+	spin_unlock(&net->can.can_rcvlists_lock);
 
 	return err;
 }
@@ -540,8 +539,9 @@ static void can_rx_delete_receiver(struct rcu_head *rp)
  * Description:
  *  Removes subscription entry depending on given (subscription) values.
  */
-void can_rx_unregister(struct net_device *dev, canid_t can_id, canid_t mask,
-		       void (*func)(struct sk_buff *, void *), void *data)
+void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
+		       canid_t mask, void (*func)(struct sk_buff *, void *),
+		       void *data)
 {
 	struct receiver *r = NULL;
 	struct hlist_head *rl;
@@ -550,9 +550,12 @@ void can_rx_unregister(struct net_device *dev, canid_t can_id, canid_t mask,
 	if (dev && dev->type != ARPHRD_CAN)
 		return;
 
-	spin_lock(&can_rcvlists_lock);
+	if (dev && !net_eq(net, dev_net(dev)))
+		return;
 
-	d = find_dev_rcv_lists(dev);
+	spin_lock(&net->can.can_rcvlists_lock);
+
+	d = find_dev_rcv_lists(net, dev);
 	if (!d) {
 		pr_err("BUG: receive list not found for "
 		       "dev %s, id %03X, mask %03X\n",
@@ -598,7 +601,7 @@ void can_rx_unregister(struct net_device *dev, canid_t can_id, canid_t mask,
 	}
 
  out:
-	spin_unlock(&can_rcvlists_lock);
+	spin_unlock(&net->can.can_rcvlists_lock);
 
 	/* schedule the receiver item for deletion */
 	if (r) {
@@ -696,10 +699,10 @@ static void can_receive(struct sk_buff *skb, struct net_device *dev)
 	rcu_read_lock();
 
 	/* deliver the packet to sockets listening on all devices */
-	matches = can_rcv_filter(&can_rx_alldev_list, skb);
+	matches = can_rcv_filter(dev_net(dev)->can.can_rx_alldev_list, skb);
 
 	/* find receive list for this device */
-	d = find_dev_rcv_lists(dev);
+	d = find_dev_rcv_lists(dev_net(dev), dev);
 	if (d)
 		matches += can_rcv_filter(d, skb);
 
@@ -719,9 +722,6 @@ static int can_rcv(struct sk_buff *skb, struct net_device *dev,
 {
 	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
 
-	if (unlikely(!net_eq(dev_net(dev), &init_net)))
-		goto drop;
-
 	if (WARN_ONCE(dev->type != ARPHRD_CAN ||
 		      skb->len != CAN_MTU ||
 		      cfd->len > CAN_MAX_DLEN,
@@ -743,9 +743,6 @@ static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
 {
 	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
 
-	if (unlikely(!net_eq(dev_net(dev), &init_net)))
-		goto drop;
-
 	if (WARN_ONCE(dev->type != ARPHRD_CAN ||
 		      skb->len != CANFD_MTU ||
 		      cfd->len > CANFD_MAX_DLEN,
@@ -835,9 +832,6 @@ static int can_notifier(struct notifier_block *nb, unsigned long msg,
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 	struct dev_rcv_lists *d;
 
-	if (!net_eq(dev_net(dev), &init_net))
-		return NOTIFY_DONE;
-
 	if (dev->type != ARPHRD_CAN)
 		return NOTIFY_DONE;
 
@@ -855,7 +849,7 @@ static int can_notifier(struct notifier_block *nb, unsigned long msg,
 		break;
 
 	case NETDEV_UNREGISTER:
-		spin_lock(&can_rcvlists_lock);
+		spin_lock(&dev_net(dev)->can.can_rcvlists_lock);
 
 		d = dev->ml_priv;
 		if (d) {
@@ -869,14 +863,48 @@ static int can_notifier(struct notifier_block *nb, unsigned long msg,
 			pr_err("can: notifier: receive list not found for dev "
 			       "%s\n", dev->name);
 
-		spin_unlock(&can_rcvlists_lock);
+		spin_unlock(&dev_net(dev)->can.can_rcvlists_lock);
 
 		break;
 	}
 
 	return NOTIFY_DONE;
 }
 
+static int can_pernet_init(struct net *net)
+{
+	net->can.can_rcvlists_lock =
+		__SPIN_LOCK_UNLOCKED(net->can.can_rcvlists_lock);
+	net->can.can_rx_alldev_list =
+		kzalloc(sizeof(struct dev_rcv_lists), GFP_KERNEL);
+
+	if (IS_ENABLED(CONFIG_PROC_FS))
+		can_init_proc(net);
+
+	return 0;
+}
+
+static void can_pernet_exit(struct net *net)
+{
+	struct net_device *dev;
+
+	if (IS_ENABLED(CONFIG_PROC_FS))
+		can_remove_proc(net);
+
+	/* remove created dev_rcv_lists from still registered CAN devices */
+	rcu_read_lock();
+	for_each_netdev_rcu(net, dev) {
+		if (dev->type == ARPHRD_CAN && dev->ml_priv) {
+			struct dev_rcv_lists *d = dev->ml_priv;
+
+			BUG_ON(d->entries);
+			kfree(d);
+			dev->ml_priv = NULL;
+		}
+	}
+	rcu_read_unlock();
+}
+
 /*
  * af_can module init/exit functions
  */
@@ -902,6 +930,13 @@ static struct notifier_block can_netdev_notifier __read_mostly = {
 	.notifier_call = can_notifier,
 };
 
+static struct pernet_operations can_pernet_ops __read_mostly = {
+	.init = can_pernet_init,
+	.exit = can_pernet_exit,
+	.id = &can_net_id,
+	.size = 0,
+};
+
 static __init int can_init(void)
 {
 	/* check for correct padding to be able to use the structs similarly */
@@ -912,8 +947,6 @@ static __init int can_init(void)
 
 	pr_info("can: controller area network core (" CAN_VERSION_STRING ")\n");
 
-	memset(&can_rx_alldev_list, 0, sizeof(can_rx_alldev_list));
-
 	rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver),
 				      0, 0, NULL);
 	if (!rcv_cache)
@@ -925,9 +958,10 @@ static __init int can_init(void)
 			setup_timer(&can_stattimer, can_stat_update, 0);
 			mod_timer(&can_stattimer, round_jiffies(jiffies + HZ));
 		}
-		can_init_proc();
 	}
 
+	register_pernet_subsys(&can_pernet_ops);
+
 	/* protocol register */
 	sock_register(&can_family_ops);
 	register_netdevice_notifier(&can_netdev_notifier);
@@ -939,13 +973,9 @@ static __init int can_init(void)
 
 static __exit void can_exit(void)
 {
-	struct net_device *dev;
-
 	if (IS_ENABLED(CONFIG_PROC_FS)) {
 		if (stats_timer)
 			del_timer_sync(&can_stattimer);
-
-		can_remove_proc();
 	}
 
 	/* protocol unregister */
@@ -954,19 +984,7 @@ static __exit void can_exit(void)
 	unregister_netdevice_notifier(&can_netdev_notifier);
 	sock_unregister(PF_CAN);
 
-	/* remove created dev_rcv_lists from still registered CAN devices */
-	rcu_read_lock();
-	for_each_netdev_rcu(&init_net, dev) {
-		if (dev->type == ARPHRD_CAN && dev->ml_priv) {
-
-			struct dev_rcv_lists *d = dev->ml_priv;
-
-			BUG_ON(d->entries);
-			kfree(d);
-			dev->ml_priv = NULL;
-		}
-	}
-	rcu_read_unlock();
+	unregister_pernet_subsys(&can_pernet_ops);
 
 	rcu_barrier(); /* Wait for completion of call_rcu()'s */
 

net/can/af_can.h

@@ -114,8 +114,8 @@ struct s_pstats {
 extern struct dev_rcv_lists can_rx_alldev_list;
 
 /* function prototypes for the CAN networklayer procfs (proc.c) */
-void can_init_proc(void);
-void can_remove_proc(void);
+void can_init_proc(struct net *net);
+void can_remove_proc(struct net *net);
 void can_stat_update(unsigned long data);
 
 /* structures and variables from af_can.c needed in proc.c for reading */