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