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/smp_lock.h>
  20 #include <linux/mount.h>
  21 #include <linux/pid_namespace.h>
  22
  23 #include "internal.h"
  24
  25 struct proc_dir_entry *proc_bus, *proc_root_fs, *proc_root_driver;
  26
  27 static int proc_test_super(struct super_block *sb, void *data)
  28 {
  29         return sb->s_fs_info == data;
  30 }
  31
  32 static int proc_set_super(struct super_block *sb, void *data)
  33 {
  34         struct pid_namespace *ns;
  35
  36         ns = (struct pid_namespace *)data;
  37         sb->s_fs_info = get_pid_ns(ns);
  38         return set_anon_super(sb, NULL);
  39 }
  40
  41 static int proc_get_sb(struct file_system_type *fs_type,
  42         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
  43 {
  44         int err;
  45         struct super_block *sb;
  46         struct pid_namespace *ns;
  47         struct proc_inode *ei;
  48
  49         if (proc_mnt) {
  50                 /* Seed the root directory with a pid so it doesn't need
  51                  * to be special in base.c.  I would do this earlier but
  52                  * the only task alive when /proc is mounted the first time
  53                  * is the init_task and it doesn't have any pids.
  54                  */
  55                 ei = PROC_I(proc_mnt->mnt_sb->s_root->d_inode);
  56                 if (!ei->pid)
  57                         ei->pid = find_get_pid(1);
  58         }
  59
  60         if (flags & MS_KERNMOUNT)
  61                 ns = (struct pid_namespace *)data;
  62         else
  63                 ns = current->nsproxy->pid_ns;
  64
  65         sb = sget(fs_type, proc_test_super, proc_set_super, ns);
  66         if (IS_ERR(sb))
  67                 return PTR_ERR(sb);
  68
  69         if (!sb->s_root) {
  70                 sb->s_flags = flags;
  71                 err = proc_fill_super(sb);
  72                 if (err) {
  73                         up_write(&sb->s_umount);
  74                         deactivate_super(sb);
  75                         return err;
  76                 }
  77
  78                 ei = PROC_I(sb->s_root->d_inode);
  79                 if (!ei->pid) {
  80                         rcu_read_lock();
  81                         ei->pid = get_pid(find_pid_ns(1, ns));
  82                         rcu_read_unlock();
  83                 }
  84
  85                 sb->s_flags |= MS_ACTIVE;
  86                 ns->proc_mnt = mnt;
  87         }
  88
  89         return simple_set_mnt(mnt, sb);
  90 }
  91
  92 static void proc_kill_sb(struct super_block *sb)
  93 {
  94         struct pid_namespace *ns;
  95
  96         ns = (struct pid_namespace *)sb->s_fs_info;
  97         kill_anon_super(sb);
  98         put_pid_ns(ns);
  99 }
 100
 101 static struct file_system_type proc_fs_type = {
 102         .name           = "proc",
 103         .get_sb         = proc_get_sb,
 104         .kill_sb        = proc_kill_sb,
 105 };
 106
 107 void __init proc_root_init(void)
 108 {
 109         int err = proc_init_inodecache();
 110         if (err)
 111                 return;
 112         err = register_filesystem(&proc_fs_type);
 113         if (err)
 114                 return;
 115         proc_mnt = kern_mount_data(&proc_fs_type, &init_pid_ns);
 116         err = PTR_ERR(proc_mnt);
 117         if (IS_ERR(proc_mnt)) {
 118                 unregister_filesystem(&proc_fs_type);
 119                 return;
 120         }
 121
 122         proc_misc_init();
 123
 124         proc_net_init();
 125
 126 #ifdef CONFIG_SYSVIPC
 127         proc_mkdir("sysvipc", NULL);
 128 #endif
 129         proc_root_fs = proc_mkdir("fs", NULL);
 130         proc_root_driver = proc_mkdir("driver", NULL);
 131         proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
 132 #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
 133         /* just give it a mountpoint */
 134         proc_mkdir("openprom", NULL);
 135 #endif
 136         proc_tty_init();
 137 #ifdef CONFIG_PROC_DEVICETREE
 138         proc_device_tree_init();
 139 #endif
 140         proc_bus = proc_mkdir("bus", NULL);
 141         proc_sys_init();
 142 }
 143
 144 static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
 145 )
 146 {
 147         generic_fillattr(dentry->d_inode, stat);
 148         stat->nlink = proc_root.nlink + nr_processes();
 149         return 0;
 150 }
 151
 152 static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
 153 {
 154         if (!proc_lookup(dir, dentry, nd)) {
 155                 return NULL;
 156         }
 157
 158         return proc_pid_lookup(dir, dentry, nd);
 159 }
 160
 161 static int proc_root_readdir(struct file * filp,
 162         void * dirent, filldir_t filldir)
 163 {
 164         unsigned int nr = filp->f_pos;
 165         int ret;
 166
 167         lock_kernel();
 168
 169         if (nr < FIRST_PROCESS_ENTRY) {
 170                 int error = proc_readdir(filp, dirent, filldir);
 171                 if (error <= 0) {
 172                         unlock_kernel();
 173                         return error;
 174                 }
 175                 filp->f_pos = FIRST_PROCESS_ENTRY;
 176         }
 177         unlock_kernel();
 178
 179         ret = proc_pid_readdir(filp, dirent, filldir);
 180         return ret;
 181 }
 182
 183 /*
 184  * The root /proc directory is special, as it has the
 185  * <pid> directories. Thus we don't use the generic
 186  * directory handling functions for that..
 187  */
 188 static const struct file_operations proc_root_operations = {
 189         .read            = generic_read_dir,
 190         .readdir         = proc_root_readdir,
 191 };
 192
 193 /*
 194  * proc root can do almost nothing..
 195  */
 196 static const struct inode_operations proc_root_inode_operations = {
 197         .lookup         = proc_root_lookup,
 198         .getattr        = proc_root_getattr,
 199 };
 200
 201 /*
 202  * This is the root "inode" in the /proc tree..
 203  */
 204 struct proc_dir_entry proc_root = {
 205         .low_ino        = PROC_ROOT_INO,
 206         .namelen        = 5,
 207         .name           = "/proc",
 208         .mode           = S_IFDIR | S_IRUGO | S_IXUGO,
 209         .nlink          = 2,
 210         .count          = ATOMIC_INIT(1),
 211         .proc_iops      = &proc_root_inode_operations,
 212         .proc_fops      = &proc_root_operations,
 213         .parent         = &proc_root,
 214 };
 215
 216 int pid_ns_prepare_proc(struct pid_namespace *ns)
 217 {
 218         struct vfsmount *mnt;
 219
 220         mnt = kern_mount_data(&proc_fs_type, ns);
 221         if (IS_ERR(mnt))
 222                 return PTR_ERR(mnt);
 223
 224         return 0;
 225 }
 226
 227 void pid_ns_release_proc(struct pid_namespace *ns)
 228 {
 229         mntput(ns->proc_mnt);
 230 }
 231
 232 EXPORT_SYMBOL(proc_symlink);
 233 EXPORT_SYMBOL(proc_mkdir);
 234 EXPORT_SYMBOL(create_proc_entry);
 235 EXPORT_SYMBOL(proc_create);
 236 EXPORT_SYMBOL(remove_proc_entry);
 237 EXPORT_SYMBOL(proc_root);
 238 EXPORT_SYMBOL(proc_root_fs);
 239 EXPORT_SYMBOL(proc_bus);
 240 EXPORT_SYMBOL(proc_root_driver);