proc_net.c

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/*
 *  linux/fs/proc/net.c
 *
 *  Copyright (C) 2007
 *
 *  Author: Eric Biederman <[email protected]>
 *
 *  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 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 *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, umode_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) + 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);
}