fs/proc/proc_net.c

   1 /*
   2  *  linux/fs/proc/net.c
   3  *
   4  *  Copyright (C) 2007
   5  *
   6  *  Author: Eric Biederman <ebiederm@xmission.com>
   7  *
   8  *  proc net directory handling functions
   9  */
  10
  11 #include <asm/uaccess.h>
  12
  13 #include <linux/errno.h>
  14 #include <linux/time.h>
  15 #include <linux/proc_fs.h>
  16 #include <linux/stat.h>
  17 #include <linux/init.h>
  18 #include <linux/sched.h>
  19 #include <linux/module.h>
  20 #include <linux/bitops.h>
  21 #include <linux/smp_lock.h>
  22 #include <linux/mount.h>
  23 #include <linux/nsproxy.h>
  24 #include <net/net_namespace.h>
  25
  26 #include "internal.h"
  27
  28
  29 struct proc_dir_entry *proc_net_fops_create(struct net *net,
  30         const char *name, mode_t mode, const struct file_operations *fops)
  31 {
  32         struct proc_dir_entry *res;
  33
  34         res = create_proc_entry(name, mode, net->proc_net);
  35         if (res)
  36                 res->proc_fops = fops;
  37         return res;
  38 }
  39 EXPORT_SYMBOL_GPL(proc_net_fops_create);
  40
  41 void proc_net_remove(struct net *net, const char *name)
  42 {
  43         remove_proc_entry(name, net->proc_net);
  44 }
  45 EXPORT_SYMBOL_GPL(proc_net_remove);
  46
  47 struct net *get_proc_net(const struct inode *inode)
  48 {
  49         return maybe_get_net(PDE_NET(PDE(inode)));
  50 }
  51 EXPORT_SYMBOL_GPL(get_proc_net);
  52
  53 static struct proc_dir_entry *proc_net_shadow;
  54
  55 static struct dentry *proc_net_shadow_dentry(struct dentry *parent,
  56                                                 struct proc_dir_entry *de)
  57 {
  58         struct dentry *shadow = NULL;
  59         struct inode *inode;
  60         if (!de)
  61                 goto out;
  62         de_get(de);
  63         inode = proc_get_inode(parent->d_inode->i_sb, de->low_ino, de);
  64         if (!inode)
  65                 goto out_de_put;
  66         shadow = d_alloc_name(parent, de->name);
  67         if (!shadow)
  68                 goto out_iput;
  69         shadow->d_op = parent->d_op; /* proc_dentry_operations */
  70         d_instantiate(shadow, inode);
  71 out:
  72         return shadow;
  73 out_iput:
  74         iput(inode);
  75 out_de_put:
  76         de_put(de);
  77         goto out;
  78 }
  79
  80 static void *proc_net_follow_link(struct dentry *parent, struct nameidata *nd)
  81 {
  82         struct net *net = current->nsproxy->net_ns;
  83         struct dentry *shadow;
  84         shadow = proc_net_shadow_dentry(parent, net->proc_net);
  85         if (!shadow)
  86                 return ERR_PTR(-ENOENT);
  87
  88         dput(nd->dentry);
  89         /* My dentry count is 1 and that should be enough as the
  90          * shadow dentry is thrown away immediately.
  91          */
  92         nd->dentry = shadow;
  93         return NULL;
  94 }
  95
  96 static struct dentry *proc_net_lookup(struct inode *dir, struct dentry *dentry,
  97                                       struct nameidata *nd)
  98 {
  99         struct net *net = current->nsproxy->net_ns;
 100         struct dentry *shadow;
 101
 102         shadow = proc_net_shadow_dentry(nd->dentry, net->proc_net);
 103         if (!shadow)
 104                 return ERR_PTR(-ENOENT);
 105
 106         dput(nd->dentry);
 107         nd->dentry = shadow;
 108
 109         return shadow->d_inode->i_op->lookup(shadow->d_inode, dentry, nd);
 110 }
 111
 112 static int proc_net_setattr(struct dentry *dentry, struct iattr *iattr)
 113 {
 114         struct net *net = current->nsproxy->net_ns;
 115         struct dentry *shadow;
 116         int ret;
 117
 118         shadow = proc_net_shadow_dentry(dentry->d_parent, net->proc_net);
 119         if (!shadow)
 120                 return -ENOENT;
 121         ret = shadow->d_inode->i_op->setattr(shadow, iattr);
 122         dput(shadow);
 123         return ret;
 124 }
 125
 126 static const struct file_operations proc_net_dir_operations = {
 127         .read                   = generic_read_dir,
 128 };
 129
 130 static struct inode_operations proc_net_dir_inode_operations = {
 131         .follow_link    = proc_net_follow_link,
 132         .lookup         = proc_net_lookup,
 133         .setattr        = proc_net_setattr,
 134 };
 135
 136 static __net_init int proc_net_ns_init(struct net *net)
 137 {
 138         struct proc_dir_entry *root, *netd, *net_statd;
 139         int err;
 140
 141         err = -ENOMEM;
 142         root = kzalloc(sizeof(*root), GFP_KERNEL);
 143         if (!root)
 144                 goto out;
 145
 146         err = -EEXIST;
 147         netd = proc_mkdir("net", root);
 148         if (!netd)
 149                 goto free_root;
 150
 151         err = -EEXIST;
 152         net_statd = proc_mkdir("stat", netd);
 153         if (!net_statd)
 154                 goto free_net;
 155
 156         root->data = net;
 157         netd->data = net;
 158         net_statd->data = net;
 159
 160         net->proc_net_root = root;
 161         net->proc_net = netd;
 162         net->proc_net_stat = net_statd;
 163         err = 0;
 164
 165 out:
 166         return err;
 167 free_net:
 168         remove_proc_entry("net", root);
 169 free_root:
 170         kfree(root);
 171         goto out;
 172 }
 173
 174 static __net_exit void proc_net_ns_exit(struct net *net)
 175 {
 176         remove_proc_entry("stat", net->proc_net);
 177         remove_proc_entry("net", net->proc_net_root);
 178         kfree(net->proc_net_root);
 179 }
 180
 181 static struct pernet_operations proc_net_ns_ops = {
 182         .init = proc_net_ns_init,
 183         .exit = proc_net_ns_exit,
 184 };
 185
 186 int __init proc_net_init(void)
 187 {
 188         proc_net_shadow = proc_mkdir("net", NULL);
 189         proc_net_shadow->proc_iops = &proc_net_dir_inode_operations;
 190         proc_net_shadow->proc_fops = &proc_net_dir_operations;
 191
 192         return register_pernet_subsys(&proc_net_ns_ops);
 193 }