f4618d39a3
Denis V. Lunev <den@sw.ru> noticed that the locking rules for the network namespace list are over complicated and broken. In particular the current register_netdev_notifier currently does not take any lock making the for_each_net iteration racy with network namespace creation and destruction. Oops. The fact that we need to use for_each_net in rtnl_unlock() when the rtnetlink support becomes per network namespace makes designing the proper locking tricky. In addition we need to be able to call rtnl_lock() and rtnl_unlock() when we have the net_mutex held. After thinking about it and looking at the alternatives carefully it looks like the simplest and most maintainable solution is to remove net_list_mutex altogether, and to use the rtnl_mutex instead. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: David S. Miller <davem@davemloft.net>
114 lines
2.6 KiB
C
114 lines
2.6 KiB
C
/*
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* Operations on the network namespace
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*/
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#ifndef __NET_NET_NAMESPACE_H
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#define __NET_NET_NAMESPACE_H
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#include <asm/atomic.h>
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#include <linux/workqueue.h>
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#include <linux/list.h>
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struct proc_dir_entry;
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struct net_device;
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struct net {
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atomic_t count; /* To decided when the network
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* namespace should be freed.
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*/
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atomic_t use_count; /* To track references we
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* destroy on demand
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*/
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struct list_head list; /* list of network namespaces */
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struct work_struct work; /* work struct for freeing */
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struct proc_dir_entry *proc_net;
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struct proc_dir_entry *proc_net_stat;
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struct proc_dir_entry *proc_net_root;
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struct net_device *loopback_dev; /* The loopback */
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struct list_head dev_base_head;
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struct hlist_head *dev_name_head;
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struct hlist_head *dev_index_head;
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};
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#ifdef CONFIG_NET
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/* Init's network namespace */
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extern struct net init_net;
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#define INIT_NET_NS(net_ns) .net_ns = &init_net,
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#else
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#define INIT_NET_NS(net_ns)
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#endif
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extern struct list_head net_namespace_list;
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#ifdef CONFIG_NET
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extern struct net *copy_net_ns(unsigned long flags, struct net *net_ns);
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#else
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static inline struct net *copy_net_ns(unsigned long flags, struct net *net_ns)
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{
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/* There is nothing to copy so this is a noop */
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return net_ns;
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}
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#endif
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extern void __put_net(struct net *net);
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static inline struct net *get_net(struct net *net)
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{
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#ifdef CONFIG_NET
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atomic_inc(&net->count);
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#endif
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return net;
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}
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static inline struct net *maybe_get_net(struct net *net)
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{
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/* Used when we know struct net exists but we
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* aren't guaranteed a previous reference count
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* exists. If the reference count is zero this
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* function fails and returns NULL.
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*/
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if (!atomic_inc_not_zero(&net->count))
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net = NULL;
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return net;
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}
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static inline void put_net(struct net *net)
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{
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#ifdef CONFIG_NET
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if (atomic_dec_and_test(&net->count))
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__put_net(net);
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#endif
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}
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static inline struct net *hold_net(struct net *net)
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{
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#ifdef CONFIG_NET
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atomic_inc(&net->use_count);
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#endif
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return net;
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}
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static inline void release_net(struct net *net)
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{
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#ifdef CONFIG_NET
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atomic_dec(&net->use_count);
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#endif
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}
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#define for_each_net(VAR) \
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list_for_each_entry(VAR, &net_namespace_list, list)
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struct pernet_operations {
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struct list_head list;
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int (*init)(struct net *net);
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void (*exit)(struct net *net);
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};
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extern int register_pernet_subsys(struct pernet_operations *);
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extern void unregister_pernet_subsys(struct pernet_operations *);
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extern int register_pernet_device(struct pernet_operations *);
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extern void unregister_pernet_device(struct pernet_operations *);
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#endif /* __NET_NET_NAMESPACE_H */
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