linux/net/core/net_namespace.c
Eric Dumazet 073862ba5d netns: fix net_alloc_generic()
When a new net namespace is created, we should attach to it a "struct
net_generic" with enough slots (even empty), or we can hit the following
BUG_ON() :

[  200.752016] kernel BUG at include/net/netns/generic.h:40!
...
[  200.752016]  [<ffffffff825c3cea>] ? get_cfcnfg+0x3a/0x180
[  200.752016]  [<ffffffff821cf0b0>] ? lockdep_rtnl_is_held+0x10/0x20
[  200.752016]  [<ffffffff825c41be>] caif_device_notify+0x2e/0x530
[  200.752016]  [<ffffffff810d61b7>] notifier_call_chain+0x67/0x110
[  200.752016]  [<ffffffff810d67c1>] raw_notifier_call_chain+0x11/0x20
[  200.752016]  [<ffffffff821bae82>] call_netdevice_notifiers+0x32/0x60
[  200.752016]  [<ffffffff821c2b26>] register_netdevice+0x196/0x300
[  200.752016]  [<ffffffff821c2ca9>] register_netdev+0x19/0x30
[  200.752016]  [<ffffffff81c1c67a>] loopback_net_init+0x4a/0xa0
[  200.752016]  [<ffffffff821b5e62>] ops_init+0x42/0x180
[  200.752016]  [<ffffffff821b600b>] setup_net+0x6b/0x100
[  200.752016]  [<ffffffff821b6466>] copy_net_ns+0x86/0x110
[  200.752016]  [<ffffffff810d5789>] create_new_namespaces+0xd9/0x190

net_alloc_generic() should take into account the maximum index into the
ptr array, as a subsystem might use net_generic() anytime.

This also reduces number of reallocations in net_assign_generic()

Reported-by: Sasha Levin <levinsasha928@gmail.com>
Tested-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sjur Brændeland <sjur.brandeland@stericsson.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-26 13:36:19 -05:00

638 lines
14 KiB
C

#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 <linux/rculist.h>
#include <linux/nsproxy.h>
#include <linux/proc_fs.h>
#include <linux/file.h>
#include <linux/export.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 */
static unsigned int max_gen_ptrs = INITIAL_NET_GEN_PTRS;
static struct net_generic *net_alloc_generic(void)
{
struct net_generic *ng;
size_t generic_size = offsetof(struct net_generic, ptr[max_gen_ptrs]);
ng = kzalloc(generic_size, GFP_KERNEL);
if (ng)
ng->len = max_gen_ptrs;
return ng;
}
static 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);
old_ng = rcu_dereference_protected(net->gen,
lockdep_is_held(&net_mutex));
ng = old_ng;
if (old_ng->len >= id)
goto assign;
ng = net_alloc_generic();
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.
*/
memcpy(&ng->ptr, &old_ng->ptr, old_ng->len * sizeof(void*));
rcu_assign_pointer(net->gen, ng);
kfree_rcu(old_ng, rcu);
assign:
ng->ptr[id - 1] = data;
return 0;
}
static int ops_init(const struct pernet_operations *ops, struct net *net)
{
int err;
if (ops->id && ops->size) {
void *data = kzalloc(ops->size, GFP_KERNEL);
if (!data)
return -ENOMEM;
err = net_assign_generic(net, *ops->id, data);
if (err) {
kfree(data);
return err;
}
}
if (ops->init)
return ops->init(net);
return 0;
}
static void ops_free(const struct pernet_operations *ops, struct net *net)
{
if (ops->id && ops->size) {
int id = *ops->id;
kfree(net_generic(net, id));
}
}
static void ops_exit_list(const struct pernet_operations *ops,
struct list_head *net_exit_list)
{
struct net *net;
if (ops->exit) {
list_for_each_entry(net, net_exit_list, exit_list)
ops->exit(net);
}
if (ops->exit_batch)
ops->exit_batch(net_exit_list);
}
static void ops_free_list(const struct pernet_operations *ops,
struct list_head *net_exit_list)
{
struct net *net;
if (ops->size && ops->id) {
list_for_each_entry(net, net_exit_list, exit_list)
ops_free(ops, net);
}
}
/*
* 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 */
const struct pernet_operations *ops, *saved_ops;
int error = 0;
LIST_HEAD(net_exit_list);
atomic_set(&net->count, 1);
atomic_set(&net->passive, 1);
net->dev_base_seq = 1;
#ifdef NETNS_REFCNT_DEBUG
atomic_set(&net->use_count, 0);
#endif
list_for_each_entry(ops, &pernet_list, list) {
error = ops_init(ops, 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_add(&net->exit_list, &net_exit_list);
saved_ops = ops;
list_for_each_entry_continue_reverse(ops, &pernet_list, list)
ops_exit_list(ops, &net_exit_list);
ops = saved_ops;
list_for_each_entry_continue_reverse(ops, &pernet_list, list)
ops_free_list(ops, &net_exit_list);
rcu_barrier();
goto out;
}
#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);
}
void net_drop_ns(void *p)
{
struct net *ns = p;
if (ns && atomic_dec_and_test(&ns->passive))
net_free(ns);
}
struct net *copy_net_ns(unsigned long flags, struct net *old_net)
{
struct net *net;
int rv;
if (!(flags & CLONE_NEWNET))
return get_net(old_net);
net = net_alloc();
if (!net)
return ERR_PTR(-ENOMEM);
mutex_lock(&net_mutex);
rv = setup_net(net);
if (rv == 0) {
rtnl_lock();
list_add_tail_rcu(&net->list, &net_namespace_list);
rtnl_unlock();
}
mutex_unlock(&net_mutex);
if (rv < 0) {
net_drop_ns(net);
return ERR_PTR(rv);
}
return net;
}
static DEFINE_SPINLOCK(cleanup_list_lock);
static LIST_HEAD(cleanup_list); /* Must hold cleanup_list_lock to touch */
static void cleanup_net(struct work_struct *work)
{
const struct pernet_operations *ops;
struct net *net, *tmp;
LIST_HEAD(net_kill_list);
LIST_HEAD(net_exit_list);
/* Atomically snapshot the list of namespaces to cleanup */
spin_lock_irq(&cleanup_list_lock);
list_replace_init(&cleanup_list, &net_kill_list);
spin_unlock_irq(&cleanup_list_lock);
mutex_lock(&net_mutex);
/* Don't let anyone else find us. */
rtnl_lock();
list_for_each_entry(net, &net_kill_list, cleanup_list) {
list_del_rcu(&net->list);
list_add_tail(&net->exit_list, &net_exit_list);
}
rtnl_unlock();
/*
* Another CPU might be rcu-iterating the list, wait for it.
* This needs to be before calling the exit() notifiers, so
* the rcu_barrier() below isn't sufficient alone.
*/
synchronize_rcu();
/* Run all of the network namespace exit methods */
list_for_each_entry_reverse(ops, &pernet_list, list)
ops_exit_list(ops, &net_exit_list);
/* Free the net generic variables */
list_for_each_entry_reverse(ops, &pernet_list, list)
ops_free_list(ops, &net_exit_list);
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 */
list_for_each_entry_safe(net, tmp, &net_exit_list, exit_list) {
list_del_init(&net->exit_list);
net_drop_ns(net);
}
}
static DECLARE_WORK(net_cleanup_work, cleanup_net);
void __put_net(struct net *net)
{
/* Cleanup the network namespace in process context */
unsigned long flags;
spin_lock_irqsave(&cleanup_list_lock, flags);
list_add(&net->cleanup_list, &cleanup_list);
spin_unlock_irqrestore(&cleanup_list_lock, flags);
queue_work(netns_wq, &net_cleanup_work);
}
EXPORT_SYMBOL_GPL(__put_net);
struct net *get_net_ns_by_fd(int fd)
{
struct proc_inode *ei;
struct file *file;
struct net *net;
file = proc_ns_fget(fd);
if (IS_ERR(file))
return ERR_CAST(file);
ei = PROC_I(file->f_dentry->d_inode);
if (ei->ns_ops == &netns_operations)
net = get_net(ei->ns);
else
net = ERR_PTR(-EINVAL);
fput(file);
return 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;
}
struct net *get_net_ns_by_fd(int fd)
{
return ERR_PTR(-EINVAL);
}
#endif
struct net *get_net_ns_by_pid(pid_t pid)
{
struct task_struct *tsk;
struct net *net;
/* Lookup the network namespace */
net = ERR_PTR(-ESRCH);
rcu_read_lock();
tsk = find_task_by_vpid(pid);
if (tsk) {
struct nsproxy *nsproxy;
nsproxy = task_nsproxy(tsk);
if (nsproxy)
net = get_net(nsproxy->net_ns);
}
rcu_read_unlock();
return net;
}
EXPORT_SYMBOL_GPL(get_net_ns_by_pid);
static int __init net_ns_init(void)
{
struct net_generic *ng;
#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);
if (setup_net(&init_net))
panic("Could not setup the initial network namespace");
rtnl_lock();
list_add_tail_rcu(&init_net.list, &net_namespace_list);
rtnl_unlock();
mutex_unlock(&net_mutex);
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;
int error;
LIST_HEAD(net_exit_list);
list_add_tail(&ops->list, list);
if (ops->init || (ops->id && ops->size)) {
for_each_net(net) {
error = ops_init(ops, net);
if (error)
goto out_undo;
list_add_tail(&net->exit_list, &net_exit_list);
}
}
return 0;
out_undo:
/* If I have an error cleanup all namespaces I initialized */
list_del(&ops->list);
ops_exit_list(ops, &net_exit_list);
ops_free_list(ops, &net_exit_list);
return error;
}
static void __unregister_pernet_operations(struct pernet_operations *ops)
{
struct net *net;
LIST_HEAD(net_exit_list);
list_del(&ops->list);
for_each_net(net)
list_add_tail(&net->exit_list, &net_exit_list);
ops_exit_list(ops, &net_exit_list);
ops_free_list(ops, &net_exit_list);
}
#else
static int __register_pernet_operations(struct list_head *list,
struct pernet_operations *ops)
{
int err = 0;
err = ops_init(ops, &init_net);
if (err)
ops_free(ops, &init_net);
return err;
}
static void __unregister_pernet_operations(struct pernet_operations *ops)
{
LIST_HEAD(net_exit_list);
list_add(&init_net.exit_list, &net_exit_list);
ops_exit_list(ops, &net_exit_list);
ops_free_list(ops, &net_exit_list);
}
#endif /* CONFIG_NET_NS */
static DEFINE_IDA(net_generic_ids);
static int register_pernet_operations(struct list_head *list,
struct pernet_operations *ops)
{
int error;
if (ops->id) {
again:
error = ida_get_new_above(&net_generic_ids, 1, ops->id);
if (error < 0) {
if (error == -EAGAIN) {
ida_pre_get(&net_generic_ids, GFP_KERNEL);
goto again;
}
return error;
}
max_gen_ptrs = max_t(unsigned int, max_gen_ptrs, *ops->id);
}
error = __register_pernet_operations(list, ops);
if (error) {
rcu_barrier();
if (ops->id)
ida_remove(&net_generic_ids, *ops->id);
}
return error;
}
static void unregister_pernet_operations(struct pernet_operations *ops)
{
__unregister_pernet_operations(ops);
rcu_barrier();
if (ops->id)
ida_remove(&net_generic_ids, *ops->id);
}
/**
* 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 *ops)
{
mutex_lock(&net_mutex);
unregister_pernet_operations(ops);
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 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);
#ifdef CONFIG_NET_NS
static void *netns_get(struct task_struct *task)
{
struct net *net = NULL;
struct nsproxy *nsproxy;
rcu_read_lock();
nsproxy = task_nsproxy(task);
if (nsproxy)
net = get_net(nsproxy->net_ns);
rcu_read_unlock();
return net;
}
static void netns_put(void *ns)
{
put_net(ns);
}
static int netns_install(struct nsproxy *nsproxy, void *ns)
{
put_net(nsproxy->net_ns);
nsproxy->net_ns = get_net(ns);
return 0;
}
const struct proc_ns_operations netns_operations = {
.name = "net",
.type = CLONE_NEWNET,
.get = netns_get,
.put = netns_put,
.install = netns_install,
};
#endif