#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 <linux/sched.h> #include <linux/idr.h> #include <net/net_namespace.h> #include <net/netns/generic.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); LIST_HEAD(net_namespace_list); EXPORT_SYMBOL_GPL(net_namespace_list); struct net init_net; EXPORT_SYMBOL(init_net); #define INITIAL_NET_GEN_PTRS 13 /* +1 for len +2 for rcu_head */ /* * setup_net runs the initializers for the network namespace object. */ static __net_init int setup_net(struct net *net) { /* Must be called with net_mutex held */ struct pernet_operations *ops; int error = 0; atomic_set(&net->count, 1); #ifdef NETNS_REFCNT_DEBUG atomic_set(&net->use_count, 0); #endif list_for_each_entry(ops, &pernet_list, 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. */ list_for_each_entry_continue_reverse(ops, &pernet_list, list) { if (ops->exit) ops->exit(net); } rcu_barrier(); goto out; } static struct net_generic *net_alloc_generic(void) { struct net_generic *ng; size_t generic_size = sizeof(struct net_generic) + INITIAL_NET_GEN_PTRS * sizeof(void *); ng = kzalloc(generic_size, GFP_KERNEL); if (ng) ng->len = INITIAL_NET_GEN_PTRS; return ng; } #ifdef CONFIG_NET_NS static struct kmem_cache *net_cachep; static struct workqueue_struct *netns_wq; static struct net *net_alloc(void) { struct net *net = NULL; struct net_generic *ng; ng = net_alloc_generic(); if (!ng) goto out; net = kmem_cache_zalloc(net_cachep, GFP_KERNEL); if (!net) goto out_free; rcu_assign_pointer(net->gen, ng); out: return net; out_free: kfree(ng); goto out; } static void net_free(struct net *net) { #ifdef NETNS_REFCNT_DEBUG if (unlikely(atomic_read(&net->use_count) != 0)) { printk(KERN_EMERG "network namespace not free! Usage: %d\n", atomic_read(&net->use_count)); return; } #endif kfree(net->gen); kmem_cache_free(net_cachep, net); } struct net *copy_net_ns(unsigned long flags, struct net *old_net) { struct net *new_net = NULL; int err; get_net(old_net); if (!(flags & CLONE_NEWNET)) return old_net; err = -ENOMEM; new_net = net_alloc(); if (!new_net) goto out_err; mutex_lock(&net_mutex); err = setup_net(new_net); if (!err) { rtnl_lock(); list_add_tail(&new_net->list, &net_namespace_list); rtnl_unlock(); } mutex_unlock(&net_mutex); if (err) goto out_free; out: put_net(old_net); return new_net; out_free: net_free(new_net); out_err: new_net = ERR_PTR(err); goto out; } static void cleanup_net(struct work_struct *work) { struct pernet_operations *ops; struct net *net; /* Be very certain incoming network packets will not find us */ rcu_barrier(); net = container_of(work, struct net, work); mutex_lock(&net_mutex); /* Don't let anyone else find us. */ rtnl_lock(); list_del(&net->list); rtnl_unlock(); /* Run all of the network namespace exit methods */ list_for_each_entry_reverse(ops, &pernet_list, 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); queue_work(netns_wq, &net->work); } EXPORT_SYMBOL_GPL(__put_net); #else struct net *copy_net_ns(unsigned long flags, struct net *old_net) { if (flags & CLONE_NEWNET) return ERR_PTR(-EINVAL); return old_net; } #endif static int __init net_ns_init(void) { struct net_generic *ng; int err; printk(KERN_INFO "net_namespace: %zd bytes\n", sizeof(struct net)); #ifdef CONFIG_NET_NS net_cachep = kmem_cache_create("net_namespace", sizeof(struct net), SMP_CACHE_BYTES, SLAB_PANIC, NULL); /* Create workqueue for cleanup */ netns_wq = create_singlethread_workqueue("netns"); if (!netns_wq) panic("Could not create netns workq"); #endif ng = net_alloc_generic(); if (!ng) panic("Could not allocate generic netns"); rcu_assign_pointer(init_net.gen, ng); mutex_lock(&net_mutex); err = setup_net(&init_net); rtnl_lock(); list_add_tail(&init_net.list, &net_namespace_list); rtnl_unlock(); mutex_unlock(&net_mutex); if (err) panic("Could not setup the initial network namespace"); return 0; } pure_initcall(net_ns_init); #ifdef CONFIG_NET_NS static int register_pernet_operations(struct list_head *list, struct pernet_operations *ops) { struct net *net, *undo_net; int error; list_add_tail(&ops->list, list); if (ops->init) { for_each_net(net) { error = ops->init(net); if (error) goto out_undo; } } return 0; out_undo: /* If I have an error cleanup all namespaces I initialized */ list_del(&ops->list); if (ops->exit) { for_each_net(undo_net) { if (undo_net == net) goto undone; ops->exit(undo_net); } } undone: return error; } static void unregister_pernet_operations(struct pernet_operations *ops) { struct net *net; list_del(&ops->list); if (ops->exit) for_each_net(net) ops->exit(net); } #else static int register_pernet_operations(struct list_head *list, struct pernet_operations *ops) { if (ops->init == NULL) return 0; return ops->init(&init_net); } static void unregister_pernet_operations(struct pernet_operations *ops) { if (ops->exit) ops->exit(&init_net); } #endif static DEFINE_IDA(net_generic_ids); /** * 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 destroyed. 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); int register_pernet_gen_subsys(int *id, struct pernet_operations *ops) { int rv; mutex_lock(&net_mutex); again: rv = ida_get_new_above(&net_generic_ids, 1, id); if (rv < 0) { if (rv == -EAGAIN) { ida_pre_get(&net_generic_ids, GFP_KERNEL); goto again; } goto out; } rv = register_pernet_operations(first_device, ops); if (rv < 0) ida_remove(&net_generic_ids, *id); out: mutex_unlock(&net_mutex); return rv; } EXPORT_SYMBOL_GPL(register_pernet_gen_subsys); void unregister_pernet_gen_subsys(int id, struct pernet_operations *ops) { mutex_lock(&net_mutex); unregister_pernet_operations(ops); ida_remove(&net_generic_ids, id); mutex_unlock(&net_mutex); } EXPORT_SYMBOL_GPL(unregister_pernet_gen_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); int register_pernet_gen_device(int *id, struct pernet_operations *ops) { int error; mutex_lock(&net_mutex); again: error = ida_get_new_above(&net_generic_ids, 1, id); if (error) { if (error == -EAGAIN) { ida_pre_get(&net_generic_ids, GFP_KERNEL); goto again; } goto out; } error = register_pernet_operations(&pernet_list, ops); if (error) ida_remove(&net_generic_ids, *id); else if (first_device == &pernet_list) first_device = &ops->list; out: mutex_unlock(&net_mutex); return error; } EXPORT_SYMBOL_GPL(register_pernet_gen_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 destroyed. 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); void unregister_pernet_gen_device(int id, struct pernet_operations *ops) { mutex_lock(&net_mutex); if (&ops->list == first_device) first_device = first_device->next; unregister_pernet_operations(ops); ida_remove(&net_generic_ids, id); mutex_unlock(&net_mutex); } EXPORT_SYMBOL_GPL(unregister_pernet_gen_device); static void net_generic_release(struct rcu_head *rcu) { struct net_generic *ng; ng = container_of(rcu, struct net_generic, rcu); kfree(ng); } int net_assign_generic(struct net *net, int id, void *data) { struct net_generic *ng, *old_ng; BUG_ON(!mutex_is_locked(&net_mutex)); BUG_ON(id == 0); ng = old_ng = net->gen; if (old_ng->len >= id) goto assign; ng = kzalloc(sizeof(struct net_generic) + id * sizeof(void *), GFP_KERNEL); if (ng == NULL) return -ENOMEM; /* * Some synchronisation notes: * * The net_generic explores the net->gen array inside rcu * read section. Besides once set the net->gen->ptr[x] * pointer never changes (see rules in netns/generic.h). * * That said, we simply duplicate this array and schedule * the old copy for kfree after a grace period. */ ng->len = id; memcpy(&ng->ptr, &old_ng->ptr, old_ng->len); rcu_assign_pointer(net->gen, ng); call_rcu(&old_ng->rcu, net_generic_release); assign: ng->ptr[id - 1] = data; return 0; } EXPORT_SYMBOL_GPL(net_assign_generic);