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_create(struct net *net,
  30         const char *name, mode_t mode, get_info_t *get_info)
  31 {
  32         return create_proc_info_entry(name,mode, net->proc_net, get_info);
  33 }
  34 EXPORT_SYMBOL_GPL(proc_net_create);
  35
  36 struct proc_dir_entry *proc_net_fops_create(struct net *net,
  37         const char *name, mode_t mode, const struct file_operations *fops)
  38 {
  39         struct proc_dir_entry *res;
  40
  41         res = create_proc_entry(name, mode, net->proc_net);
  42         if (res)
  43                 res->proc_fops = fops;
  44         return res;
  45 }
  46 EXPORT_SYMBOL_GPL(proc_net_fops_create);
  47
  48 void proc_net_remove(struct net *net, const char *name)
  49 {
  50         remove_proc_entry(name, net->proc_net);
  51 }
  52 EXPORT_SYMBOL_GPL(proc_net_remove);
  53
  54 struct net *get_proc_net(const struct inode *inode)
  55 {
  56         return maybe_get_net(PDE_NET(PDE(inode)));
  57 }
  58 EXPORT_SYMBOL_GPL(get_proc_net);
  59
  60 static struct proc_dir_entry *proc_net_shadow;
  61
  62 static struct dentry *proc_net_shadow_dentry(struct dentry *parent,
  63                                                 struct proc_dir_entry *de)
  64 {
  65         struct dentry *shadow = NULL;
  66         struct inode *inode;
  67         if (!de)
  68                 goto out;
  69         de_get(de);
  70         inode = proc_get_inode(parent->d_inode->i_sb, de->low_ino, de);
  71         if (!inode)
  72                 goto out_de_put;
  73         shadow = d_alloc_name(parent, de->name);
  74         if (!shadow)
  75                 goto out_iput;
  76         shadow->d_op = parent->d_op; /* proc_dentry_operations */
  77         d_instantiate(shadow, inode);
  78 out:
  79         return shadow;
  80 out_iput:
  81         iput(inode);
  82 out_de_put:
  83         de_put(de);
  84         goto out;
  85 }
  86
  87 static void *proc_net_follow_link(struct dentry *parent, struct nameidata *nd)
  88 {
  89         struct net *net = current->nsproxy->net_ns;
  90         struct dentry *shadow;
  91         shadow = proc_net_shadow_dentry(parent, net->proc_net);
  92         if (!shadow)
  93                 return ERR_PTR(-ENOENT);
  94
  95         dput(nd->dentry);
  96         /* My dentry count is 1 and that should be enough as the
  97          * shadow dentry is thrown away immediately.
  98          */
  99         nd->dentry = shadow;
 100         return NULL;
 101 }
 102
 103 static struct dentry *proc_net_lookup(struct inode *dir, struct dentry *dentry,
 104                                       struct nameidata *nd)
 105 {
 106         struct net *net = current->nsproxy->net_ns;
 107         struct dentry *shadow;
 108
 109         shadow = proc_net_shadow_dentry(nd->dentry, net->proc_net);
 110         if (!shadow)
 111                 return ERR_PTR(-ENOENT);
 112
 113         dput(nd->dentry);
 114         nd->dentry = shadow;
 115
 116         return shadow->d_inode->i_op->lookup(shadow->d_inode, dentry, nd);
 117 }
 118
 119 static int proc_net_setattr(struct dentry *dentry, struct iattr *iattr)
 120 {
 121         struct net *net = current->nsproxy->net_ns;
 122         struct dentry *shadow;
 123         int ret;
 124
 125         shadow = proc_net_shadow_dentry(dentry->d_parent, net->proc_net);
 126         if (!shadow)
 127                 return -ENOENT;
 128         ret = shadow->d_inode->i_op->setattr(shadow, iattr);
 129         dput(shadow);
 130         return ret;
 131 }
 132
 133 static const struct file_operations proc_net_dir_operations = {
 134         .read                   = generic_read_dir,
 135 };
 136
 137 static struct inode_operations proc_net_dir_inode_operations = {
 138         .follow_link    = proc_net_follow_link,
 139         .lookup         = proc_net_lookup,
 140         .setattr        = proc_net_setattr,
 141 };
 142
 143 static __net_init int proc_net_ns_init(struct net *net)
 144 {
 145         struct proc_dir_entry *root, *netd, *net_statd;
 146         int err;
 147
 148         err = -ENOMEM;
 149         root = kzalloc(sizeof(*root), GFP_KERNEL);
 150         if (!root)
 151                 goto out;
 152
 153         err = -EEXIST;
 154         netd = proc_mkdir("net", root);
 155         if (!netd)
 156                 goto free_root;
 157
 158         err = -EEXIST;
 159         net_statd = proc_mkdir("stat", netd);
 160         if (!net_statd)
 161                 goto free_net;
 162
 163         root->data = net;
 164         netd->data = net;
 165         net_statd->data = net;
 166
 167         net->proc_net_root = root;
 168         net->proc_net = netd;
 169         net->proc_net_stat = net_statd;
 170         err = 0;
 171
 172 out:
 173         return err;
 174 free_net:
 175         remove_proc_entry("net", root);
 176 free_root:
 177         kfree(root);
 178         goto out;
 179 }
 180
 181 static __net_exit void proc_net_ns_exit(struct net *net)
 182 {
 183         remove_proc_entry("stat", net->proc_net);
 184         remove_proc_entry("net", net->proc_net_root);
 185         kfree(net->proc_net_root);
 186 }
 187
 188 struct pernet_operations __net_initdata proc_net_ns_ops = {
 189         .init = proc_net_ns_init,
 190         .exit = proc_net_ns_exit,
 191 };
 192
 193 int __init proc_net_init(void)
 194 {
 195         proc_net_shadow = proc_mkdir("net", NULL);
 196         proc_net_shadow->proc_iops = &proc_net_dir_inode_operations;
 197         proc_net_shadow->proc_fops = &proc_net_dir_operations;
 198
 199         return register_pernet_subsys(&proc_net_ns_ops);
 200 }