diff options
| -rw-r--r-- | include/net/net_namespace.h | 68 | ||||
| -rw-r--r-- | net/core/Makefile | 2 | ||||
| -rw-r--r-- | net/core/net_namespace.c | 292 |
3 files changed, 361 insertions, 1 deletions
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h new file mode 100644 index 00000000000..6344b77f81a --- /dev/null +++ b/include/net/net_namespace.h @@ -0,0 +1,68 @@ +/* + * Operations on the network namespace + */ +#ifndef __NET_NET_NAMESPACE_H +#define __NET_NET_NAMESPACE_H + +#include <asm/atomic.h> +#include <linux/workqueue.h> +#include <linux/list.h> + +struct net { + atomic_t count; /* To decided when the network + * namespace should be freed. + */ + atomic_t use_count; /* To track references we + * destroy on demand + */ + struct list_head list; /* list of network namespaces */ + struct work_struct work; /* work struct for freeing */ +}; + +extern struct net init_net; +extern struct list_head net_namespace_list; + +extern void __put_net(struct net *net); + +static inline struct net *get_net(struct net *net) +{ + atomic_inc(&net->count); + return net; +} + +static inline void put_net(struct net *net) +{ + if (atomic_dec_and_test(&net->count)) + __put_net(net); +} + +static inline struct net *hold_net(struct net *net) +{ + atomic_inc(&net->use_count); + return net; +} + +static inline void release_net(struct net *net) +{ + atomic_dec(&net->use_count); +} + +extern void net_lock(void); +extern void net_unlock(void); + +#define for_each_net(VAR) \ + list_for_each_entry(VAR, &net_namespace_list, list) + + +struct pernet_operations { + struct list_head list; + int (*init)(struct net *net); + void (*exit)(struct net *net); +}; + +extern int register_pernet_subsys(struct pernet_operations *); +extern void unregister_pernet_subsys(struct pernet_operations *); +extern int register_pernet_device(struct pernet_operations *); +extern void unregister_pernet_device(struct pernet_operations *); + +#endif /* __NET_NET_NAMESPACE_H */ diff --git a/net/core/Makefile b/net/core/Makefile index 4751613e1b5..ea9b3f32d1c 100644 --- a/net/core/Makefile +++ b/net/core/Makefile @@ -3,7 +3,7 @@ # obj-y := sock.o request_sock.o skbuff.o iovec.o datagram.o stream.o scm.o \ - gen_stats.o gen_estimator.o + gen_stats.o gen_estimator.o net_namespace.o obj-$(CONFIG_SYSCTL) += sysctl_net_core.o diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c new file mode 100644 index 00000000000..f259a9b6fdc --- /dev/null +++ b/net/core/net_namespace.c @@ -0,0 +1,292 @@ +#include <linux/workqueue.h> +#include <linux/rtnetlink.h> +#include <linux/cache.h> +#include <linux/slab.h> +#include <linux/list.h> +#include <linux/delay.h> +#include <net/net_namespace.h> + +/* + * Our network namespace constructor/destructor lists + */ + +static LIST_HEAD(pernet_list); +static struct list_head *first_device = &pernet_list; +static DEFINE_MUTEX(net_mutex); + +static DEFINE_MUTEX(net_list_mutex); +LIST_HEAD(net_namespace_list); + +static struct kmem_cache *net_cachep; + +struct net init_net; +EXPORT_SYMBOL_GPL(init_net); + +void net_lock(void) +{ + mutex_lock(&net_list_mutex); +} + +void net_unlock(void) +{ + mutex_unlock(&net_list_mutex); +} + +static struct net *net_alloc(void) +{ + return kmem_cache_alloc(net_cachep, GFP_KERNEL); +} + +static void net_free(struct net *net) +{ + if (!net) + return; + + if (unlikely(atomic_read(&net->use_count) != 0)) { + printk(KERN_EMERG "network namespace not free! Usage: %d\n", + atomic_read(&net->use_count)); + return; + } + + kmem_cache_free(net_cachep, net); +} + +static void cleanup_net(struct work_struct *work) +{ + struct pernet_operations *ops; + struct list_head *ptr; + struct net *net; + + net = container_of(work, struct net, work); + + mutex_lock(&net_mutex); + + /* Don't let anyone else find us. */ + net_lock(); + list_del(&net->list); + net_unlock(); + + /* Run all of the network namespace exit methods */ + list_for_each_prev(ptr, &pernet_list) { + ops = list_entry(ptr, struct pernet_operations, list); + if (ops->exit) + ops->exit(net); + } + + mutex_unlock(&net_mutex); + + /* Ensure there are no outstanding rcu callbacks using this + * network namespace. + */ + rcu_barrier(); + + /* Finally it is safe to free my network namespace structure */ + net_free(net); +} + + +void __put_net(struct net *net) +{ + /* Cleanup the network namespace in process context */ + INIT_WORK(&net->work, cleanup_net); + schedule_work(&net->work); +} +EXPORT_SYMBOL_GPL(__put_net); + +/* + * setup_net runs the initializers for the network namespace object. + */ +static int setup_net(struct net *net) +{ + /* Must be called with net_mutex held */ + struct pernet_operations *ops; + struct list_head *ptr; + int error; + + memset(net, 0, sizeof(struct net)); + atomic_set(&net->count, 1); + atomic_set(&net->use_count, 0); + + error = 0; + list_for_each(ptr, &pernet_list) { + ops = list_entry(ptr, struct pernet_operations, list); + if (ops->init) { + error = ops->init(net); + if (error < 0) + goto out_undo; + } + } +out: + return error; +out_undo: + /* Walk through the list backwards calling the exit functions + * for the pernet modules whose init functions did not fail. + */ + for (ptr = ptr->prev; ptr != &pernet_list; ptr = ptr->prev) { + ops = list_entry(ptr, struct pernet_operations, list); + if (ops->exit) + ops->exit(net); + } + goto out; +} + +static int __init net_ns_init(void) +{ + int err; + + printk(KERN_INFO "net_namespace: %zd bytes\n", sizeof(struct net)); + net_cachep = kmem_cache_create("net_namespace", sizeof(struct net), + SMP_CACHE_BYTES, + SLAB_PANIC, NULL); + mutex_lock(&net_mutex); + err = setup_net(&init_net); + + net_lock(); + list_add_tail(&init_net.list, &net_namespace_list); + net_unlock(); + + mutex_unlock(&net_mutex); + if (err) + panic("Could not setup the initial network namespace"); + + return 0; +} + +pure_initcall(net_ns_init); + +static int register_pernet_operations(struct list_head *list, + struct pernet_operations *ops) +{ + struct net *net, *undo_net; + int error; + + error = 0; + list_add_tail(&ops->list, list); + for_each_net(net) { + if (ops->init) { + error = ops->init(net); + if (error) + goto out_undo; + } + } +out: + return error; + +out_undo: + /* If I have an error cleanup all namespaces I initialized */ + list_del(&ops->list); + for_each_net(undo_net) { + if (undo_net == net) + goto undone; + if (ops->exit) + ops->exit(undo_net); + } +undone: + goto out; +} + +static void unregister_pernet_operations(struct pernet_operations *ops) +{ + struct net *net; + + list_del(&ops->list); + for_each_net(net) + if (ops->exit) + ops->exit(net); +} + +/** + * register_pernet_subsys - register a network namespace subsystem + * @ops: pernet operations structure for the subsystem + * + * Register a subsystem which has init and exit functions + * that are called when network namespaces are created and + * destroyed respectively. + * + * When registered all network namespace init functions are + * called for every existing network namespace. Allowing kernel + * modules to have a race free view of the set of network namespaces. + * + * When a new network namespace is created all of the init + * methods are called in the order in which they were registered. + * + * When a network namespace is destroyed all of the exit methods + * are called in the reverse of the order with which they were + * registered. + */ +int register_pernet_subsys(struct pernet_operations *ops) +{ + int error; + mutex_lock(&net_mutex); + error = register_pernet_operations(first_device, ops); + mutex_unlock(&net_mutex); + return error; +} +EXPORT_SYMBOL_GPL(register_pernet_subsys); + +/** + * unregister_pernet_subsys - unregister a network namespace subsystem + * @ops: pernet operations structure to manipulate + * + * Remove the pernet operations structure from the list to be + * used when network namespaces are created or destoryed. In + * addition run the exit method for all existing network + * namespaces. + */ +void unregister_pernet_subsys(struct pernet_operations *module) +{ + mutex_lock(&net_mutex); + unregister_pernet_operations(module); + mutex_unlock(&net_mutex); +} +EXPORT_SYMBOL_GPL(unregister_pernet_subsys); + +/** + * register_pernet_device - register a network namespace device + * @ops: pernet operations structure for the subsystem + * + * Register a device which has init and exit functions + * that are called when network namespaces are created and + * destroyed respectively. + * + * When registered all network namespace init functions are + * called for every existing network namespace. Allowing kernel + * modules to have a race free view of the set of network namespaces. + * + * When a new network namespace is created all of the init + * methods are called in the order in which they were registered. + * + * When a network namespace is destroyed all of the exit methods + * are called in the reverse of the order with which they were + * registered. + */ +int register_pernet_device(struct pernet_operations *ops) +{ + int error; + mutex_lock(&net_mutex); + error = register_pernet_operations(&pernet_list, ops); + if (!error && (first_device == &pernet_list)) + first_device = &ops->list; + mutex_unlock(&net_mutex); + return error; +} +EXPORT_SYMBOL_GPL(register_pernet_device); + +/** + * unregister_pernet_device - unregister a network namespace netdevice + * @ops: pernet operations structure to manipulate + * + * Remove the pernet operations structure from the list to be + * used when network namespaces are created or destoryed. In + * addition run the exit method for all existing network + * namespaces. + */ +void unregister_pernet_device(struct pernet_operations *ops) +{ + mutex_lock(&net_mutex); + if (&ops->list == first_device) + first_device = first_device->next; + unregister_pernet_operations(ops); + mutex_unlock(&net_mutex); +} +EXPORT_SYMBOL_GPL(unregister_pernet_device); |