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 #include <linux/parser.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         int err = set_anon_super(sb, NULL);
  33         if (!err) {
  34                 struct pid_namespace *ns = (struct pid_namespace *)data;
  35                 sb->s_fs_info = get_pid_ns(ns);
  36         }
  37         return err;
  38 }
  39
  40 enum {
  41         Opt_gid, Opt_hidepid, Opt_err,
  42 };
  43
  44 static const match_table_t tokens = {
  45         {Opt_hidepid, "hidepid=%u"},
  46         {Opt_gid, "gid=%u"},
  47         {Opt_err, NULL},
  48 };
  49
  50 static int proc_parse_options(char *options, struct pid_namespace *pid)
  51 {
  52         char *p;
  53         substring_t args[MAX_OPT_ARGS];
  54         int option;
  55
  56         if (!options)
  57                 return 1;
  58
  59         while ((p = strsep(&options, ",")) != NULL) {
  60                 int token;
  61                 if (!*p)
  62                         continue;
  63
  64                 args[0].to = args[0].from = 0;
  65                 token = match_token(p, tokens, args);
  66                 switch (token) {
  67                 case Opt_gid:
  68                         if (match_int(&args[0], &option))
  69                                 return 0;
  70                         pid->pid_gid = make_kgid(current_user_ns(), option);
  71                         break;
  72                 case Opt_hidepid:
  73                         if (match_int(&args[0], &option))
  74                                 return 0;
  75                         if (option < 0 || option > 2) {
  76                                 pr_err("proc: hidepid value must be between 0 and 2.\n");
  77                                 return 0;
  78                         }
  79                         pid->hide_pid = option;
  80                         break;
  81                 default:
  82                         pr_err("proc: unrecognized mount option \"%s\" "
  83                                "or missing value\n", p);
  84                         return 0;
  85                 }
  86         }
  87
  88         return 1;
  89 }
  90
  91 int proc_remount(struct super_block *sb, int *flags, char *data)
  92 {
  93         struct pid_namespace *pid = sb->s_fs_info;
  94         return !proc_parse_options(data, pid);
  95 }
  96
  97 static struct dentry *proc_mount(struct file_system_type *fs_type,
  98         int flags, const char *dev_name, void *data)
  99 {
 100         int err;
 101         struct super_block *sb;
 102         struct pid_namespace *ns;
 103         struct proc_inode *ei;
 104         char *options;
 105
 106         if (flags & MS_KERNMOUNT) {
 107                 ns = (struct pid_namespace *)data;
 108                 options = NULL;
 109         } else {
 110                 ns = current->nsproxy->pid_ns;
 111                 options = data;
 112         }
 113
 114         sb = sget(fs_type, proc_test_super, proc_set_super, ns);
 115         if (IS_ERR(sb))
 116                 return ERR_CAST(sb);
 117
 118         if (!proc_parse_options(options, ns)) {
 119                 deactivate_locked_super(sb);
 120                 return ERR_PTR(-EINVAL);
 121         }
 122
 123         if (!sb->s_root) {
 124                 sb->s_flags = flags;
 125                 err = proc_fill_super(sb);
 126                 if (err) {
 127                         deactivate_locked_super(sb);
 128                         return ERR_PTR(err);
 129                 }
 130
 131                 sb->s_flags |= MS_ACTIVE;
 132         }
 133
 134         ei = PROC_I(sb->s_root->d_inode);
 135         if (!ei->pid) {
 136                 rcu_read_lock();
 137                 ei->pid = get_pid(find_pid_ns(1, ns));
 138                 rcu_read_unlock();
 139         }
 140
 141         return dget(sb->s_root);
 142 }
 143
 144 static void proc_kill_sb(struct super_block *sb)
 145 {
 146         struct pid_namespace *ns;
 147
 148         ns = (struct pid_namespace *)sb->s_fs_info;
 149         kill_anon_super(sb);
 150         put_pid_ns(ns);
 151 }
 152
 153 static struct file_system_type proc_fs_type = {
 154         .name           = "proc",
 155         .mount          = proc_mount,
 156         .kill_sb        = proc_kill_sb,
 157 };
 158
 159 void __init proc_root_init(void)
 160 {
 161         int err;
 162
 163         proc_init_inodecache();
 164         err = register_filesystem(&proc_fs_type);
 165         if (err)
 166                 return;
 167         err = pid_ns_prepare_proc(&init_pid_ns);
 168         if (err) {
 169                 unregister_filesystem(&proc_fs_type);
 170                 return;
 171         }
 172
 173         proc_symlink("mounts", NULL, "self/mounts");
 174
 175         proc_net_init();
 176
 177 #ifdef CONFIG_SYSVIPC
 178         proc_mkdir("sysvipc", NULL);
 179 #endif
 180         proc_mkdir("fs", NULL);
 181         proc_mkdir("driver", NULL);
 182         proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
 183 #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
 184         /* just give it a mountpoint */
 185         proc_mkdir("openprom", NULL);
 186 #endif
 187         proc_tty_init();
 188 #ifdef CONFIG_PROC_DEVICETREE
 189         proc_device_tree_init();
 190 #endif
 191         proc_mkdir("bus", NULL);
 192         proc_sys_init();
 193 }
 194
 195 static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
 196 )
 197 {
 198         generic_fillattr(dentry->d_inode, stat);
 199         stat->nlink = proc_root.nlink + nr_processes();
 200         return 0;
 201 }
 202
 203 static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
 204 {
 205         if (!proc_lookup(dir, dentry, nd)) {
 206                 return NULL;
 207         }
 208
 209         return proc_pid_lookup(dir, dentry, nd);
 210 }
 211
 212 static int proc_root_readdir(struct file * filp,
 213         void * dirent, filldir_t filldir)
 214 {
 215         unsigned int nr = filp->f_pos;
 216         int ret;
 217
 218         if (nr < FIRST_PROCESS_ENTRY) {
 219                 int error = proc_readdir(filp, dirent, filldir);
 220                 if (error <= 0)
 221                         return error;
 222                 filp->f_pos = FIRST_PROCESS_ENTRY;
 223         }
 224
 225         ret = proc_pid_readdir(filp, dirent, filldir);
 226         return ret;
 227 }
 228
 229 /*
 230  * The root /proc directory is special, as it has the
 231  * <pid> directories. Thus we don't use the generic
 232  * directory handling functions for that..
 233  */
 234 static const struct file_operations proc_root_operations = {
 235         .read            = generic_read_dir,
 236         .readdir         = proc_root_readdir,
 237         .llseek         = default_llseek,
 238 };
 239
 240 /*
 241  * proc root can do almost nothing..
 242  */
 243 static const struct inode_operations proc_root_inode_operations = {
 244         .lookup         = proc_root_lookup,
 245         .getattr        = proc_root_getattr,
 246 };
 247
 248 /*
 249  * This is the root "inode" in the /proc tree..
 250  */
 251 struct proc_dir_entry proc_root = {
 252         .low_ino        = PROC_ROOT_INO,
 253         .namelen        = 5,
 254         .mode           = S_IFDIR | S_IRUGO | S_IXUGO,
 255         .nlink          = 2,
 256         .count          = ATOMIC_INIT(1),
 257         .proc_iops      = &proc_root_inode_operations,
 258         .proc_fops      = &proc_root_operations,
 259         .parent         = &proc_root,
 260         .name           = "/proc",
 261 };
 262
 263 int pid_ns_prepare_proc(struct pid_namespace *ns)
 264 {
 265         struct vfsmount *mnt;
 266
 267         mnt = kern_mount_data(&proc_fs_type, ns);
 268         if (IS_ERR(mnt))
 269                 return PTR_ERR(mnt);
 270
 271         ns->proc_mnt = mnt;
 272         return 0;
 273 }
 274
 275 void pid_ns_release_proc(struct pid_namespace *ns)
 276 {
 277         kern_unmount(ns->proc_mnt);
 278 }