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         struct vfsmount *mnt;
  95         int err;
  96
  97         proc_init_inodecache();
  98         err = register_filesystem(&proc_fs_type);
  99         if (err)
 100                 return;
 101         mnt = kern_mount_data(&proc_fs_type, &init_pid_ns);
 102         if (IS_ERR(mnt)) {
 103                 unregister_filesystem(&proc_fs_type);
 104                 return;
 105         }
 106
 107         init_pid_ns.proc_mnt = mnt;
 108         proc_symlink("mounts", NULL, "self/mounts");
 109
 110         proc_net_init();
 111
 112 #ifdef CONFIG_SYSVIPC
 113         proc_mkdir("sysvipc", NULL);
 114 #endif
 115         proc_mkdir("fs", NULL);
 116         proc_mkdir("driver", NULL);
 117         proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
 118 #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
 119         /* just give it a mountpoint */
 120         proc_mkdir("openprom", NULL);
 121 #endif
 122         proc_tty_init();
 123 #ifdef CONFIG_PROC_DEVICETREE
 124         proc_device_tree_init();
 125 #endif
 126         proc_mkdir("bus", NULL);
 127         proc_sys_init();
 128 }
 129
 130 static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
 131 )
 132 {
 133         generic_fillattr(dentry->d_inode, stat);
 134         stat->nlink = proc_root.nlink + nr_processes();
 135         return 0;
 136 }
 137
 138 static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
 139 {
 140         if (!proc_lookup(dir, dentry, nd)) {
 141                 return NULL;
 142         }
 143
 144         return proc_pid_lookup(dir, dentry, nd);
 145 }
 146
 147 static int proc_root_readdir(struct file * filp,
 148         void * dirent, filldir_t filldir)
 149 {
 150         unsigned int nr = filp->f_pos;
 151         int ret;
 152
 153         if (nr < FIRST_PROCESS_ENTRY) {
 154                 int error = proc_readdir(filp, dirent, filldir);
 155                 if (error <= 0)
 156                         return error;
 157                 filp->f_pos = FIRST_PROCESS_ENTRY;
 158         }
 159
 160         ret = proc_pid_readdir(filp, dirent, filldir);
 161         return ret;
 162 }
 163
 164 /*
 165  * The root /proc directory is special, as it has the
 166  * <pid> directories. Thus we don't use the generic
 167  * directory handling functions for that..
 168  */
 169 static const struct file_operations proc_root_operations = {
 170         .read            = generic_read_dir,
 171         .readdir         = proc_root_readdir,
 172         .llseek         = default_llseek,
 173 };
 174
 175 /*
 176  * proc root can do almost nothing..
 177  */
 178 static const struct inode_operations proc_root_inode_operations = {
 179         .lookup         = proc_root_lookup,
 180         .getattr        = proc_root_getattr,
 181 };
 182
 183 /*
 184  * This is the root "inode" in the /proc tree..
 185  */
 186 struct proc_dir_entry proc_root = {
 187         .low_ino        = PROC_ROOT_INO,
 188         .namelen        = 5,
 189         .name           = "/proc",
 190         .mode           = S_IFDIR | S_IRUGO | S_IXUGO,
 191         .nlink          = 2,
 192         .count          = ATOMIC_INIT(1),
 193         .proc_iops      = &proc_root_inode_operations,
 194         .proc_fops      = &proc_root_operations,
 195         .parent         = &proc_root,
 196 };
 197
 198 int pid_ns_prepare_proc(struct pid_namespace *ns)
 199 {
 200         struct vfsmount *mnt;
 201
 202         mnt = kern_mount_data(&proc_fs_type, ns);
 203         if (IS_ERR(mnt))
 204                 return PTR_ERR(mnt);
 205
 206         ns->proc_mnt = mnt;
 207         return 0;
 208 }
 209
 210 void pid_ns_release_proc(struct pid_namespace *ns)
 211 {
 212         mntput(ns->proc_mnt);
 213 }