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 = NULL;
  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         char *options;
 104
 105         if (flags & MS_KERNMOUNT) {
 106                 ns = (struct pid_namespace *)data;
 107                 options = NULL;
 108         } else {
 109                 ns = task_active_pid_ns(current);
 110                 options = data;
 111         }
 112
 113         sb = sget(fs_type, proc_test_super, proc_set_super, flags, ns);
 114         if (IS_ERR(sb))
 115                 return ERR_CAST(sb);
 116
 117         if (!proc_parse_options(options, ns)) {
 118                 deactivate_locked_super(sb);
 119                 return ERR_PTR(-EINVAL);
 120         }
 121
 122         if (!sb->s_root) {
 123                 err = proc_fill_super(sb);
 124                 if (err) {
 125                         deactivate_locked_super(sb);
 126                         return ERR_PTR(err);
 127                 }
 128
 129                 sb->s_flags |= MS_ACTIVE;
 130         }
 131
 132         return dget(sb->s_root);
 133 }
 134
 135 static void proc_kill_sb(struct super_block *sb)
 136 {
 137         struct pid_namespace *ns;
 138
 139         ns = (struct pid_namespace *)sb->s_fs_info;
 140         kill_anon_super(sb);
 141         put_pid_ns(ns);
 142 }
 143
 144 static struct file_system_type proc_fs_type = {
 145         .name           = "proc",
 146         .mount          = proc_mount,
 147         .kill_sb        = proc_kill_sb,
 148         .fs_flags       = FS_USERNS_MOUNT,
 149 };
 150
 151 void __init proc_root_init(void)
 152 {
 153         int err;
 154
 155         proc_init_inodecache();
 156         err = register_filesystem(&proc_fs_type);
 157         if (err)
 158                 return;
 159
 160         proc_self_init();
 161         proc_symlink("mounts", NULL, "self/mounts");
 162
 163         proc_net_init();
 164
 165 #ifdef CONFIG_SYSVIPC
 166         proc_mkdir("sysvipc", NULL);
 167 #endif
 168         proc_mkdir("fs", NULL);
 169         proc_mkdir("driver", NULL);
 170         proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
 171 #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
 172         /* just give it a mountpoint */
 173         proc_mkdir("openprom", NULL);
 174 #endif
 175         proc_tty_init();
 176 #ifdef CONFIG_PROC_DEVICETREE
 177         proc_device_tree_init();
 178 #endif
 179         proc_mkdir("bus", NULL);
 180         proc_sys_init();
 181 }
 182
 183 static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
 184 )
 185 {
 186         generic_fillattr(dentry->d_inode, stat);
 187         stat->nlink = proc_root.nlink + nr_processes();
 188         return 0;
 189 }
 190
 191 static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
 192 {
 193         if (!proc_lookup(dir, dentry, flags))
 194                 return NULL;
 195
 196         return proc_pid_lookup(dir, dentry, flags);
 197 }
 198
 199 static int proc_root_readdir(struct file * filp,
 200         void * dirent, filldir_t filldir)
 201 {
 202         unsigned int nr = filp->f_pos;
 203         int ret;
 204
 205         if (nr < FIRST_PROCESS_ENTRY) {
 206                 int error = proc_readdir(filp, dirent, filldir);
 207                 if (error <= 0)
 208                         return error;
 209                 filp->f_pos = FIRST_PROCESS_ENTRY;
 210         }
 211
 212         ret = proc_pid_readdir(filp, dirent, filldir);
 213         return ret;
 214 }
 215
 216 /*
 217  * The root /proc directory is special, as it has the
 218  * <pid> directories. Thus we don't use the generic
 219  * directory handling functions for that..
 220  */
 221 static const struct file_operations proc_root_operations = {
 222         .read            = generic_read_dir,
 223         .readdir         = proc_root_readdir,
 224         .llseek         = default_llseek,
 225 };
 226
 227 /*
 228  * proc root can do almost nothing..
 229  */
 230 static const struct inode_operations proc_root_inode_operations = {
 231         .lookup         = proc_root_lookup,
 232         .getattr        = proc_root_getattr,
 233 };
 234
 235 /*
 236  * This is the root "inode" in the /proc tree..
 237  */
 238 struct proc_dir_entry proc_root = {
 239         .low_ino        = PROC_ROOT_INO,
 240         .namelen        = 5,
 241         .mode           = S_IFDIR | S_IRUGO | S_IXUGO,
 242         .nlink          = 2,
 243         .count          = ATOMIC_INIT(1),
 244         .proc_iops      = &proc_root_inode_operations,
 245         .proc_fops      = &proc_root_operations,
 246         .parent         = &proc_root,
 247         .name           = "/proc",
 248 };
 249
 250 int pid_ns_prepare_proc(struct pid_namespace *ns)
 251 {
 252         struct vfsmount *mnt;
 253
 254         mnt = kern_mount_data(&proc_fs_type, ns);
 255         if (IS_ERR(mnt))
 256                 return PTR_ERR(mnt);
 257
 258         ns->proc_mnt = mnt;
 259         return 0;
 260 }
 261
 262 void pid_ns_release_proc(struct pid_namespace *ns)
 263 {
 264         kern_unmount(ns->proc_mnt);
 265 }