fs/proc/root.c

   1 /*
   2  *  linux/fs/proc/root.c
   3  *
   4  *  Copyright (C) 1991, 1992 Linus Torvalds
   5  *
   6  *  proc root directory handling functions
   7  */
   8
   9 #include <asm/uaccess.h>
  10
  11 #include <linux/errno.h>
  12 #include <linux/time.h>
  13 #include <linux/proc_fs.h>
  14 #include <linux/stat.h>
  15 #include <linux/init.h>
  16 #include <linux/sched.h>
  17 #include <linux/module.h>
  18 #include <linux/bitops.h>
  19 #include <linux/mount.h>
  20 #include <linux/pid_namespace.h>
  21
  22 #include "internal.h"
  23
  24 static int proc_test_super(struct super_block *sb, void *data)
  25 {
  26         return sb->s_fs_info == data;
  27 }
  28
  29 static int proc_set_super(struct super_block *sb, void *data)
  30 {
  31         struct pid_namespace *ns;
  32
  33         ns = (struct pid_namespace *)data;
  34         sb->s_fs_info = get_pid_ns(ns);
  35         return set_anon_super(sb, NULL);
  36 }
  37
  38 static struct dentry *proc_mount(struct file_system_type *fs_type,
  39         int flags, const char *dev_name, void *data)
  40 {
  41         int err;
  42         struct super_block *sb;
  43         struct pid_namespace *ns;
  44         struct proc_inode *ei;
  45
  46         if (flags & MS_KERNMOUNT)
  47                 ns = (struct pid_namespace *)data;
  48         else
  49                 ns = current->nsproxy->pid_ns;
  50
  51         sb = sget(fs_type, proc_test_super, proc_set_super, ns);
  52         if (IS_ERR(sb))
  53                 return ERR_CAST(sb);
  54
  55         if (!sb->s_root) {
  56                 sb->s_flags = flags;
  57                 err = proc_fill_super(sb);
  58                 if (err) {
  59                         deactivate_locked_super(sb);
  60                         return ERR_PTR(err);
  61                 }
  62
  63                 sb->s_flags |= MS_ACTIVE;
  64         }
  65
  66         ei = PROC_I(sb->s_root->d_inode);
  67         if (!ei->pid) {
  68                 rcu_read_lock();
  69                 ei->pid = get_pid(find_pid_ns(1, ns));
  70                 rcu_read_unlock();
  71         }
  72
  73         return dget(sb->s_root);
  74 }
  75
  76 static void proc_kill_sb(struct super_block *sb)
  77 {
  78         struct pid_namespace *ns;
  79
  80         ns = (struct pid_namespace *)sb->s_fs_info;
  81         kill_anon_super(sb);
  82         put_pid_ns(ns);
  83 }
  84
  85 static struct file_system_type proc_fs_type = {
  86         .name           = "proc",
  87         .mount          = proc_mount,
  88         .kill_sb        = proc_kill_sb,
  89 };
  90
  91 void __init proc_root_init(void)
  92 {
  93         struct vfsmount *mnt;
  94         int err;
  95
  96         proc_init_inodecache();
  97         err = register_filesystem(&proc_fs_type);
  98         if (err)
  99                 return;
 100         mnt = kern_mount_data(&proc_fs_type, &init_pid_ns);
 101         if (IS_ERR(mnt)) {
 102                 unregister_filesystem(&proc_fs_type);
 103                 return;
 104         }
 105
 106         init_pid_ns.proc_mnt = mnt;
 107         proc_symlink("mounts", NULL, "self/mounts");
 108
 109         proc_net_init();
 110
 111 #ifdef CONFIG_SYSVIPC
 112         proc_mkdir("sysvipc", NULL);
 113 #endif
 114         proc_mkdir("fs", NULL);
 115         proc_mkdir("driver", NULL);
 116         proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
 117 #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
 118         /* just give it a mountpoint */
 119         proc_mkdir("openprom", NULL);
 120 #endif
 121         proc_tty_init();
 122 #ifdef CONFIG_PROC_DEVICETREE
 123         proc_device_tree_init();
 124 #endif
 125         proc_mkdir("bus", NULL);
 126         proc_sys_init();
 127 }
 128
 129 static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
 130 )
 131 {
 132         generic_fillattr(dentry->d_inode, stat);
 133         stat->nlink = proc_root.nlink + nr_processes();
 134         return 0;
 135 }
 136
 137 static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
 138 {
 139         if (!proc_lookup(dir, dentry, nd)) {
 140                 return NULL;
 141         }
 142
 143         return proc_pid_lookup(dir, dentry, nd);
 144 }
 145
 146 static int proc_root_readdir(struct file * filp,
 147         void * dirent, filldir_t filldir)
 148 {
 149         unsigned int nr = filp->f_pos;
 150         int ret;
 151
 152         if (nr < FIRST_PROCESS_ENTRY) {
 153                 int error = proc_readdir(filp, dirent, filldir);
 154                 if (error <= 0)
 155                         return error;
 156                 filp->f_pos = FIRST_PROCESS_ENTRY;
 157         }
 158
 159         ret = proc_pid_readdir(filp, dirent, filldir);
 160         return ret;
 161 }
 162
 163 /*
 164  * The root /proc directory is special, as it has the
 165  * <pid> directories. Thus we don't use the generic
 166  * directory handling functions for that..
 167  */
 168 static const struct file_operations proc_root_operations = {
 169         .read            = generic_read_dir,
 170         .readdir         = proc_root_readdir,
 171         .llseek         = default_llseek,
 172 };
 173
 174 /*
 175  * proc root can do almost nothing..
 176  */
 177 static const struct inode_operations proc_root_inode_operations = {
 178         .lookup         = proc_root_lookup,
 179         .getattr        = proc_root_getattr,
 180 };
 181
 182 /*
 183  * This is the root "inode" in the /proc tree..
 184  */
 185 struct proc_dir_entry proc_root = {
 186         .low_ino        = PROC_ROOT_INO,
 187         .namelen        = 5,
 188         .name           = "/proc",
 189         .mode           = S_IFDIR | S_IRUGO | S_IXUGO,
 190         .nlink          = 2,
 191         .count          = ATOMIC_INIT(1),
 192         .proc_iops      = &proc_root_inode_operations,
 193         .proc_fops      = &proc_root_operations,
 194         .parent         = &proc_root,
 195 };
 196
 197 int pid_ns_prepare_proc(struct pid_namespace *ns)
 198 {
 199         struct vfsmount *mnt;
 200
 201         mnt = kern_mount_data(&proc_fs_type, ns);
 202         if (IS_ERR(mnt))
 203                 return PTR_ERR(mnt);
 204
 205         ns->proc_mnt = mnt;
 206         return 0;
 207 }
 208
 209 void pid_ns_release_proc(struct pid_namespace *ns)
 210 {
 211         mntput(ns->proc_mnt);
 212 }