mirror of
https://github.com/torvalds/linux.git
synced 2024-10-31 17:21:49 +00:00
077130c0cf
The problem: proc_net files remember which network namespace the are against but do not remember hold a reference count (as that would pin the network namespace). So we currently have a small window where the reference count on a network namespace may be incremented when opening a /proc file when it has already gone to zero. To fix this introduce maybe_get_net and get_proc_net. maybe_get_net increments the network namespace reference count only if it is greater then zero, ensuring we don't increment a reference count after it has gone to zero. get_proc_net handles all of the magic to go from a proc inode to the network namespace instance and call maybe_get_net on it. PROC_NET the old accessor is removed so that we don't get confused and use the wrong helper function. Then I fix up the callers to use get_proc_net and handle the case case where get_proc_net returns NULL. In that case I return -ENXIO because effectively the network namespace has already gone away so the files we are trying to access don't exist anymore. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Paul E. McKenney <paulmck@us.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
97 lines
2.2 KiB
C
97 lines
2.2 KiB
C
/*
|
|
* 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 proc_dir_entry;
|
|
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 */
|
|
|
|
struct proc_dir_entry *proc_net;
|
|
struct proc_dir_entry *proc_net_stat;
|
|
struct proc_dir_entry *proc_net_root;
|
|
|
|
struct list_head dev_base_head;
|
|
struct hlist_head *dev_name_head;
|
|
struct hlist_head *dev_index_head;
|
|
};
|
|
|
|
#ifdef CONFIG_NET
|
|
/* Init's network namespace */
|
|
extern struct net init_net;
|
|
#define INIT_NET_NS(net_ns) .net_ns = &init_net,
|
|
#else
|
|
#define INIT_NET_NS(net_ns)
|
|
#endif
|
|
|
|
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 struct net *maybe_get_net(struct net *net)
|
|
{
|
|
/* Used when we know struct net exists but we
|
|
* aren't guaranteed a previous reference count
|
|
* exists. If the reference count is zero this
|
|
* function fails and returns NULL.
|
|
*/
|
|
if (!atomic_inc_not_zero(&net->count))
|
|
net = NULL;
|
|
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 */
|