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