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