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