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 <linux/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/user_namespace.h>
  20 #include <linux/mount.h>
  21 #include <linux/pid_namespace.h>
  22 #include <linux/parser.h>
  23 #include <linux/cred.h>
  24
  25 #include "internal.h"
  26
  27 enum {
  28         Opt_gid, Opt_hidepid, Opt_err,
  29 };
  30
  31 static const match_table_t tokens = {
  32         {Opt_hidepid, "hidepid=%u"},
  33         {Opt_gid, "gid=%u"},
  34         {Opt_err, NULL},
  35 };
  36
  37 int proc_parse_options(char *options, struct pid_namespace *pid)
  38 {
  39         char *p;
  40         substring_t args[MAX_OPT_ARGS];
  41         int option;
  42
  43         if (!options)
  44                 return 1;
  45
  46         while ((p = strsep(&options, ",")) != NULL) {
  47                 int token;
  48                 if (!*p)
  49                         continue;
  50
  51                 args[0].to = args[0].from = NULL;
  52                 token = match_token(p, tokens, args);
  53                 switch (token) {
  54                 case Opt_gid:
  55                         if (match_int(&args[0], &option))
  56                                 return 0;
  57                         pid->pid_gid = make_kgid(current_user_ns(), option);
  58                         break;
  59                 case Opt_hidepid:
  60                         if (match_int(&args[0], &option))
  61                                 return 0;
  62                         if (option < HIDEPID_OFF ||
  63                             option > HIDEPID_INVISIBLE) {
  64                                 pr_err("proc: hidepid value must be between 0 and 2.\n");
  65                                 return 0;
  66                         }
  67                         pid->hide_pid = option;
  68                         break;
  69                 default:
  70                         pr_err("proc: unrecognized mount option \"%s\" "
  71                                "or missing value\n", p);
  72                         return 0;
  73                 }
  74         }
  75
  76         return 1;
  77 }
  78
  79 int proc_remount(struct super_block *sb, int *flags, char *data)
  80 {
  81         struct pid_namespace *pid = sb->s_fs_info;
  82
  83         sync_filesystem(sb);
  84         return !proc_parse_options(data, pid);
  85 }
  86
  87 static struct dentry *proc_mount(struct file_system_type *fs_type,
  88         int flags, const char *dev_name, void *data)
  89 {
  90         struct pid_namespace *ns;
  91
  92         if (flags & MS_KERNMOUNT) {
  93                 ns = data;
  94                 data = NULL;
  95         } else {
  96                 ns = task_active_pid_ns(current);
  97         }
  98
  99         return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super);
 100 }
 101
 102 static void proc_kill_sb(struct super_block *sb)
 103 {
 104         struct pid_namespace *ns;
 105
 106         ns = (struct pid_namespace *)sb->s_fs_info;
 107         if (ns->proc_self)
 108                 dput(ns->proc_self);
 109         if (ns->proc_thread_self)
 110                 dput(ns->proc_thread_self);
 111         kill_anon_super(sb);
 112         put_pid_ns(ns);
 113 }
 114
 115 static struct file_system_type proc_fs_type = {
 116         .name           = "proc",
 117         .mount          = proc_mount,
 118         .kill_sb        = proc_kill_sb,
 119         .fs_flags       = FS_USERNS_MOUNT,
 120 };
 121
 122 void __init proc_root_init(void)
 123 {
 124         int err;
 125
 126         proc_init_inodecache();
 127         set_proc_pid_nlink();
 128         err = register_filesystem(&proc_fs_type);
 129         if (err)
 130                 return;
 131
 132         proc_self_init();
 133         proc_thread_self_init();
 134         proc_symlink("mounts", NULL, "self/mounts");
 135
 136         proc_net_init();
 137
 138 #ifdef CONFIG_SYSVIPC
 139         proc_mkdir("sysvipc", NULL);
 140 #endif
 141         proc_mkdir("fs", NULL);
 142         proc_mkdir("driver", NULL);
 143         proc_create_mount_point("fs/nfsd"); /* somewhere for the nfsd filesystem to be mounted */
 144 #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
 145         /* just give it a mountpoint */
 146         proc_create_mount_point("openprom");
 147 #endif
 148         proc_tty_init();
 149         proc_mkdir("bus", NULL);
 150         proc_sys_init();
 151 }
 152
 153 static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
 154 )
 155 {
 156         generic_fillattr(d_inode(dentry), stat);
 157         stat->nlink = proc_root.nlink + nr_processes();
 158         return 0;
 159 }
 160
 161 static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
 162 {
 163         if (!proc_pid_lookup(dir, dentry, flags))
 164                 return NULL;
 165
 166         return proc_lookup(dir, dentry, flags);
 167 }
 168
 169 static int proc_root_readdir(struct file *file, struct dir_context *ctx)
 170 {
 171         if (ctx->pos < FIRST_PROCESS_ENTRY) {
 172                 int error = proc_readdir(file, ctx);
 173                 if (unlikely(error <= 0))
 174                         return error;
 175                 ctx->pos = FIRST_PROCESS_ENTRY;
 176         }
 177
 178         return proc_pid_readdir(file, ctx);
 179 }
 180
 181 /*
 182  * The root /proc directory is special, as it has the
 183  * <pid> directories. Thus we don't use the generic
 184  * directory handling functions for that..
 185  */
 186 static const struct file_operations proc_root_operations = {
 187         .read            = generic_read_dir,
 188         .iterate_shared  = proc_root_readdir,
 189         .llseek         = generic_file_llseek,
 190 };
 191
 192 /*
 193  * proc root can do almost nothing..
 194  */
 195 static const struct inode_operations proc_root_inode_operations = {
 196         .lookup         = proc_root_lookup,
 197         .getattr        = proc_root_getattr,
 198 };
 199
 200 /*
 201  * This is the root "inode" in the /proc tree..
 202  */
 203 struct proc_dir_entry proc_root = {
 204         .low_ino        = PROC_ROOT_INO,
 205         .namelen        = 5,
 206         .mode           = S_IFDIR | S_IRUGO | S_IXUGO,
 207         .nlink          = 2,
 208         .count          = ATOMIC_INIT(1),
 209         .proc_iops      = &proc_root_inode_operations,
 210         .proc_fops      = &proc_root_operations,
 211         .parent         = &proc_root,
 212         .subdir         = RB_ROOT,
 213         .name           = "/proc",
 214 };
 215
 216 int pid_ns_prepare_proc(struct pid_namespace *ns)
 217 {
 218         struct vfsmount *mnt;
 219
 220         mnt = kern_mount_data(&proc_fs_type, ns);
 221         if (IS_ERR(mnt))
 222                 return PTR_ERR(mnt);
 223
 224         ns->proc_mnt = mnt;
 225         return 0;
 226 }
 227
 228 void pid_ns_release_proc(struct pid_namespace *ns)
 229 {
 230         kern_unmount(ns->proc_mnt);
 231 }