linux/fs/proc/root.c
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   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
  24static int proc_test_super(struct super_block *sb, void *data)
  25{
  26        return sb->s_fs_info == data;
  27}
  28
  29static 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
  38static struct dentry *proc_mount(struct file_system_type *fs_type,
  39        int flags, const char *dev_name, void *data)
  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 ERR_CAST(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_PTR(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        }
  83
  84        return dget(sb->s_root);
  85}
  86
  87static void proc_kill_sb(struct super_block *sb)
  88{
  89        struct pid_namespace *ns;
  90
  91        ns = (struct pid_namespace *)sb->s_fs_info;
  92        kill_anon_super(sb);
  93        put_pid_ns(ns);
  94}
  95
  96static struct file_system_type proc_fs_type = {
  97        .name           = "proc",
  98        .mount          = proc_mount,
  99        .kill_sb        = proc_kill_sb,
 100};
 101
 102void __init proc_root_init(void)
 103{
 104        int err;
 105
 106        proc_init_inodecache();
 107        err = register_filesystem(&proc_fs_type);
 108        if (err)
 109                return;
 110        proc_mnt = kern_mount_data(&proc_fs_type, &init_pid_ns);
 111        if (IS_ERR(proc_mnt)) {
 112                unregister_filesystem(&proc_fs_type);
 113                return;
 114        }
 115
 116        init_pid_ns.proc_mnt = proc_mnt;
 117        proc_symlink("mounts", NULL, "self/mounts");
 118
 119        proc_net_init();
 120
 121#ifdef CONFIG_SYSVIPC
 122        proc_mkdir("sysvipc", NULL);
 123#endif
 124        proc_mkdir("fs", NULL);
 125        proc_mkdir("driver", NULL);
 126        proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
 127#if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
 128        /* just give it a mountpoint */
 129        proc_mkdir("openprom", NULL);
 130#endif
 131        proc_tty_init();
 132#ifdef CONFIG_PROC_DEVICETREE
 133        proc_device_tree_init();
 134#endif
 135        proc_mkdir("bus", NULL);
 136        proc_sys_init();
 137}
 138
 139static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
 140)
 141{
 142        generic_fillattr(dentry->d_inode, stat);
 143        stat->nlink = proc_root.nlink + nr_processes();
 144        return 0;
 145}
 146
 147static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
 148{
 149        if (!proc_lookup(dir, dentry, nd)) {
 150                return NULL;
 151        }
 152        
 153        return proc_pid_lookup(dir, dentry, nd);
 154}
 155
 156static int proc_root_readdir(struct file * filp,
 157        void * dirent, filldir_t filldir)
 158{
 159        unsigned int nr = filp->f_pos;
 160        int ret;
 161
 162        if (nr < FIRST_PROCESS_ENTRY) {
 163                int error = proc_readdir(filp, dirent, filldir);
 164                if (error <= 0)
 165                        return error;
 166                filp->f_pos = FIRST_PROCESS_ENTRY;
 167        }
 168
 169        ret = proc_pid_readdir(filp, dirent, filldir);
 170        return ret;
 171}
 172
 173/*
 174 * The root /proc directory is special, as it has the
 175 * <pid> directories. Thus we don't use the generic
 176 * directory handling functions for that..
 177 */
 178static const struct file_operations proc_root_operations = {
 179        .read            = generic_read_dir,
 180        .readdir         = proc_root_readdir,
 181        .llseek         = default_llseek,
 182};
 183
 184/*
 185 * proc root can do almost nothing..
 186 */
 187static const struct inode_operations proc_root_inode_operations = {
 188        .lookup         = proc_root_lookup,
 189        .getattr        = proc_root_getattr,
 190};
 191
 192/*
 193 * This is the root "inode" in the /proc tree..
 194 */
 195struct proc_dir_entry proc_root = {
 196        .low_ino        = PROC_ROOT_INO, 
 197        .namelen        = 5, 
 198        .name           = "/proc",
 199        .mode           = S_IFDIR | S_IRUGO | S_IXUGO, 
 200        .nlink          = 2, 
 201        .count          = ATOMIC_INIT(1),
 202        .proc_iops      = &proc_root_inode_operations, 
 203        .proc_fops      = &proc_root_operations,
 204        .parent         = &proc_root,
 205};
 206
 207int pid_ns_prepare_proc(struct pid_namespace *ns)
 208{
 209        struct vfsmount *mnt;
 210
 211        mnt = kern_mount_data(&proc_fs_type, ns);
 212        if (IS_ERR(mnt))
 213                return PTR_ERR(mnt);
 214
 215        ns->proc_mnt = mnt;
 216        return 0;
 217}
 218
 219void pid_ns_release_proc(struct pid_namespace *ns)
 220{
 221        mntput(ns->proc_mnt);
 222}
 223