linux/include/net/net_namespace.h
Pavel Emelyanov e9720acd72 [NET]: Make /proc/net a symlink on /proc/self/net (v3)
Current /proc/net is done with so called "shadows", but current
implementation is broken and has little chances to get fixed.

The problem is that dentries subtree of /proc/net directory has
fancy revalidation rules to make processes living in different
net namespaces see different entries in /proc/net subtree, but
currently, tasks see in the /proc/net subdir the contents of any
other namespace, depending on who opened the file first.

The proposed fix is to turn /proc/net into a symlink, which points
to /proc/self/net, which in turn shows what previously was in
/proc/net - the network-related info, from the net namespace the
appropriate task lives in.

# ls -l /proc/net
lrwxrwxrwx  1 root root 8 Mar  5 15:17 /proc/net -> self/net

In other words - this behaves like /proc/mounts, but unlike
"mounts", "net" is not a file, but a directory.

Changes from v2:
* Fixed discrepancy of /proc/net nlink count and selinux labeling
  screwup pointed out by Stephen.

  To get the correct nlink count the ->getattr callback for /proc/net
  is overridden to read one from the net->proc_net entry.

  To make selinux still work the net->proc_net entry is initialized
  properly, i.e. with the "net" name and the proc_net parent.

Selinux fixes are
Acked-by:  Stephen Smalley <sds@tycho.nsa.gov>

Changes from v1:
* Fixed a task_struct leak in get_proc_task_net, pointed out by Paul.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-07 11:08:40 -08:00

178 lines
3.9 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>
#include <net/netns/unix.h>
#include <net/netns/packet.h>
#include <net/netns/ipv4.h>
#include <net/netns/ipv6.h>
#include <net/netns/x_tables.h>
struct proc_dir_entry;
struct net_device;
struct sock;
struct ctl_table_header;
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 list_head sysctl_table_headers;
struct net_device *loopback_dev; /* The loopback */
struct list_head dev_base_head;
struct hlist_head *dev_name_head;
struct hlist_head *dev_index_head;
/* core fib_rules */
struct list_head rules_ops;
spinlock_t rules_mod_lock;
struct sock *rtnl; /* rtnetlink socket */
/* core sysctls */
struct ctl_table_header *sysctl_core_hdr;
int sysctl_somaxconn;
struct netns_packet packet;
struct netns_unix unx;
struct netns_ipv4 ipv4;
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
struct netns_ipv6 ipv6;
#endif
#ifdef CONFIG_NETFILTER
struct netns_xt xt;
#endif
};
#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;
#ifdef CONFIG_NET
extern struct net *copy_net_ns(unsigned long flags, struct net *net_ns);
#else
static inline struct net *copy_net_ns(unsigned long flags, struct net *net_ns)
{
/* There is nothing to copy so this is a noop */
return net_ns;
}
#endif
#ifdef CONFIG_NET_NS
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);
}
#else
static inline struct net *get_net(struct net *net)
{
return net;
}
static inline void put_net(struct net *net)
{
}
static inline struct net *hold_net(struct net *net)
{
return net;
}
static inline void release_net(struct net *net)
{
}
static inline struct net *maybe_get_net(struct net *net)
{
return net;
}
#endif
#define for_each_net(VAR) \
list_for_each_entry(VAR, &net_namespace_list, list)
#ifdef CONFIG_NET_NS
#define __net_init
#define __net_exit
#define __net_initdata
#else
#define __net_init __init
#define __net_exit __exit_refok
#define __net_initdata __initdata
#endif
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 *);
struct ctl_path;
struct ctl_table;
struct ctl_table_header;
extern struct ctl_table_header *register_net_sysctl_table(struct net *net,
const struct ctl_path *path, struct ctl_table *table);
extern void unregister_net_sysctl_table(struct ctl_table_header *header);
#endif /* __NET_NET_NAMESPACE_H */