/*
   *  linux/fs/proc/net.c
   *
   *  Copyright (C) 2007
   *
   *  Author: Eric Biederman <ebiederm@xmission.com>
   *
   *  proc net directory handling functions
   */
  
  #include <asm/uaccess.h>
  
  #include <linux/errno.h>
  #include <linux/time.h>
  #include <linux/proc_fs.h>
  #include <linux/stat.h>
  #include <linux/slab.h>
  #include <linux/init.h>
  #include <linux/sched.h>
  #include <linux/module.h>
  #include <linux/bitops.h>
  #include <linux/mount.h>
  #include <linux/nsproxy.h>
  #include <net/net_namespace.h>
  #include <linux/seq_file.h>
  
  #include "internal.h"
  
  static inline struct net *PDE_NET(struct proc_dir_entry *pde)
  {
  	return pde->parent->data;
  }
  
  static struct net *get_proc_net(const struct inode *inode)
  {
  	return maybe_get_net(PDE_NET(PDE(inode)));
  }
  
  int seq_open_net(struct inode *ino, struct file *f,
  		 const struct seq_operations *ops, int size)
  {
  	struct net *net;
  	struct seq_net_private *p;
  
  	BUG_ON(size < sizeof(*p));
  
  	net = get_proc_net(ino);
  	if (net == NULL)
  		return -ENXIO;
  
  	p = __seq_open_private(f, ops, size);
  	if (p == NULL) {
  		put_net(net);
  		return -ENOMEM;
  	}
  #ifdef CONFIG_NET_NS
  	p->net = net;
  #endif
  	return 0;
  }
  EXPORT_SYMBOL_GPL(seq_open_net);
  
  int single_open_net(struct inode *inode, struct file *file,
  		int (*show)(struct seq_file *, void *))
  {
  	int err;
  	struct net *net;
  
  	err = -ENXIO;
  	net = get_proc_net(inode);
  	if (net == NULL)
  		goto err_net;
  
  	err = single_open(file, show, net);
  	if (err < 0)
  		goto err_open;
  
  	return 0;
  
  err_open:
  	put_net(net);
  err_net:
  	return err;
  }
  EXPORT_SYMBOL_GPL(single_open_net);
  
  int seq_release_net(struct inode *ino, struct file *f)
  {
  	struct seq_file *seq;
  
  	seq = f->private_data;
  
  	put_net(seq_file_net(seq));
  	seq_release_private(ino, f);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(seq_release_net);
  
  int single_release_net(struct inode *ino, struct file *f)
  {
  	struct seq_file *seq = f->private_data;
  	put_net(seq->private);
  	return single_release(ino, f);
  }
  EXPORT_SYMBOL_GPL(single_release_net);
  
  static struct net *get_proc_task_net(struct inode *dir)
  {
  	struct task_struct *task;
  	struct nsproxy *ns;
  	struct net *net = NULL;
  
  	rcu_read_lock();
  	task = pid_task(proc_pid(dir), PIDTYPE_PID);
  	if (task != NULL) {
  		ns = task_nsproxy(task);
  		if (ns != NULL)
  			net = get_net(ns->net_ns);
  	}
  	rcu_read_unlock();
  
  	return net;
  }
  
  static struct dentry *proc_tgid_net_lookup(struct inode *dir,
  		struct dentry *dentry, unsigned int flags)
  {
  	struct dentry *de;
  	struct net *net;
  
  	de = ERR_PTR(-ENOENT);
  	net = get_proc_task_net(dir);
  	if (net != NULL) {
  		de = proc_lookup_de(net->proc_net, dir, dentry);
  		put_net(net);
  	}
  	return de;
  }
  
  static int proc_tgid_net_getattr(struct vfsmount *mnt, struct dentry *dentry,
  		struct kstat *stat)
  {
  	struct inode *inode = dentry->d_inode;
  	struct net *net;
  
  	net = get_proc_task_net(inode);
  
  	generic_fillattr(inode, stat);
  
  	if (net != NULL) {
  		stat->nlink = net->proc_net->nlink;
  		put_net(net);
  	}
  
  	return 0;
  }
  
  const struct inode_operations proc_net_inode_operations = {
  	.lookup		= proc_tgid_net_lookup,
  	.getattr	= proc_tgid_net_getattr,
  };
  
  static int proc_tgid_net_readdir(struct file *file, struct dir_context *ctx)
  {
  	int ret;
  	struct net *net;
  
  	ret = -EINVAL;
  	net = get_proc_task_net(file_inode(file));
  	if (net != NULL) {
  		ret = proc_readdir_de(net->proc_net, file, ctx);
  		put_net(net);
  	}
  	return ret;
  }
  
  const struct file_operations proc_net_operations = {
  	.llseek		= generic_file_llseek,
  	.read		= generic_read_dir,
  	.iterate	= proc_tgid_net_readdir,
  };
  
  static __net_init int proc_net_ns_init(struct net *net)
  {
  	struct proc_dir_entry *netd, *net_statd;
  	int err;
  
  	err = -ENOMEM;
  	netd = kzalloc(sizeof(*netd) + 4, GFP_KERNEL);
  	if (!netd)
  		goto out;
  
  	netd->data = net;
  	netd->nlink = 2;
  	netd->namelen = 3;
  	netd->parent = &proc_root;
  	memcpy(netd->name, "net", 4);
  
  	err = -EEXIST;
  	net_statd = proc_net_mkdir(net, "stat", netd);
  	if (!net_statd)
  		goto free_net;
  
  	net->proc_net = netd;
  	net->proc_net_stat = net_statd;
  	return 0;
  
  free_net:
  	kfree(netd);
  out:
  	return err;
  }
  
  static __net_exit void proc_net_ns_exit(struct net *net)
  {
  	remove_proc_entry("stat", net->proc_net);
  	kfree(net->proc_net);
  }
  
  static struct pernet_operations __net_initdata proc_net_ns_ops = {
  	.init = proc_net_ns_init,
  	.exit = proc_net_ns_exit,
  };
  
  int __init proc_net_init(void)
  {
  	proc_symlink("net", NULL, "self/net");
  
  	return register_pernet_subsys(&proc_net_ns_ops);
  }