/*
 *  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/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 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, struct nameidata *nd)
{
        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 *filp, void *dirent,
                filldir_t filldir)
{
        int ret;
        struct net *net;

        ret = -EINVAL;
        net = get_proc_task_net(filp->f_path.dentry->d_inode);
        if (net != NULL) {
                ret = proc_readdir_de(net->proc_net, filp, dirent, filldir);
                put_net(net);
        }
        return ret;
}

const struct file_operations proc_net_operations = {
        .llseek         = generic_file_llseek,
        .read           = generic_read_dir,
        .readdir        = proc_tgid_net_readdir,
};


struct proc_dir_entry *proc_net_fops_create(struct net *net,
        const char *name, mode_t mode, const struct file_operations *fops)
{
        return proc_create(name, mode, net->proc_net, fops);
}
EXPORT_SYMBOL_GPL(proc_net_fops_create);

void proc_net_remove(struct net *net, const char *name)
{
        remove_proc_entry(name, net->proc_net);
}
EXPORT_SYMBOL_GPL(proc_net_remove);

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), GFP_KERNEL);
        if (!netd)
                goto out;

        netd->data = net;
        netd->nlink = 2;
        netd->name = "net";
        netd->namelen = 3;
        netd->parent = &proc_root;

        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);
}